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<pre>Network Working Group                                             J. Wray
Request for Comments: 2744                                Iris Associates
Obsoletes: <a href="./rfc1509">1509</a>                                              January 2000
Category: Standards Track


          <span class="h1">Generic Security Service API Version 2 : C-bindings</span>

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   This document specifies C language bindings for Version 2, Update 1
   of the Generic Security Service Application Program Interface (GSS-
   API), which is described at a language-independent conceptual level
   in <a href="./rfc2743">RFC-2743</a> [<a href="#ref-GSSAPI" title="&quot;Generic Security Service Application Program Interface Version 2, Update 1&quot;">GSSAPI</a>].  It obsoletes <a href="./rfc1509">RFC-1509</a>, making specific
   incremental changes in response to implementation experience and
   liaison requests.  It is intended, therefore, that this memo or a
   successor version thereof will become the basis for subsequent
   progression of the GSS-API specification on the standards track.

   The Generic Security Service Application Programming Interface
   provides security services to its callers, and is intended for
   implementation atop a variety of underlying cryptographic mechanisms.
   Typically, GSS-API callers will be application protocols into which
   security enhancements are integrated through invocation of services
   provided by the GSS-API. The GSS-API allows a caller application to
   authenticate a principal identity associated with a peer application,
   to delegate rights to a peer, and to apply security services such as
   confidentiality and integrity on a per-message basis.











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<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>.   Introduction</span>

   The Generic Security Service Application Programming Interface
   [<a href="#ref-GSSAPI" title="&quot;Generic Security Service Application Program Interface Version 2, Update 1&quot;">GSSAPI</a>] provides security services to calling applications.  It
   allows a communicating application to authenticate the user
   associated with another application, to delegate rights to another
   application, and to apply security services such as confidentiality
   and integrity on a per-message basis.

   There are four stages to using the GSS-API:

   a) The application acquires a set of credentials with which it may
      prove its identity to other processes. The application's
      credentials vouch for its global identity, which may or may not be
      related to any local username under which it may be running.

   b) A pair of communicating applications establish a joint security
      context using their credentials.  The security context is a pair
      of GSS-API data structures that contain shared state information,
      which is required in order that per-message security services may
      be provided.  Examples of state that might be shared between
      applications as part of a security context are cryptographic keys,
      and message sequence numbers.  As part of the establishment of a
      security context, the context initiator is authenticated to the
      responder, and may require that the responder is authenticated in
      turn.  The initiator may optionally give the responder the right
      to initiate further security contexts, acting as an agent or
      delegate of the initiator.  This transfer of rights is termed
      delegation, and is achieved by creating a set of credentials,
      similar to those used by the initiating application, but which may
      be used by the responder.

      To establish and maintain the shared information that makes up the
      security context, certain GSS-API calls will return a token data
      structure, which is an opaque data type that may contain
      cryptographically protected data.  The caller of such a GSS-API
      routine is responsible for transferring the token to the peer
      application, encapsulated if necessary in an application-
      application protocol.  On receipt of such a token, the peer
      application should pass it to a corresponding GSS-API routine
      which will decode the token and extract the information, updating
      the security context state information accordingly.









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   c) Per-message services are invoked to apply either:

      integrity and data origin authentication, or confidentiality,
      integrity and data origin authentication to application data,
      which are treated by GSS-API as arbitrary octet-strings.  An
      application transmitting a message that it wishes to protect will
      call the appropriate GSS-API routine (gss_get_mic or gss_wrap) to
      apply protection, specifying the appropriate security context, and
      send the resulting token to the receiving application.  The
      receiver will pass the received token (and, in the case of data
      protected by gss_get_mic, the accompanying message-data) to the
      corresponding decoding routine (gss_verify_mic or gss_unwrap) to
      remove the protection and validate the data.

   d) At the completion of a communications session (which may extend
      across several transport connections), each application calls a
      GSS-API routine to delete the security context.  Multiple contexts
      may also be used (either successively or simultaneously) within a
      single communications association, at the option of the
      applications.

<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>.   GSS-API Routines</span>

      This section lists the routines that make up the GSS-API, and
      offers a brief description of the purpose of each routine.
      Detailed descriptions of each routine are listed in alphabetical
      order in <a href="#section-5">section 5</a>.

   Table 2-1  GSS-API Credential-management Routines

   Routine                Section              Function
   -------                -------              --------
   gss_acquire_cred           5.2  Assume a global identity; Obtain
                                   a GSS-API credential handle for
                                   pre-existing credentials.
   gss_add_cred               5.3  Construct credentials
                                   incrementally
   gss_inquire_cred           5.21 Obtain information about a
                                   credential
   gss_inquire_cred_by_mech   5.22 Obtain per-mechanism information
                                   about a credential.
   gss_release_cred           5.27 Discard a credential handle.









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   Table 2-2  GSS-API Context-Level Routines

   Routine                 Section              Function
   -------                 -------              --------
   gss_init_sec_context       5.19 Initiate a security context with
                                   a peer application
   gss_accept_sec_context     5.1  Accept a security context
                                   initiated by a
                                   peer application
   gss_delete_sec_context     5.9  Discard a security context
   gss_process_context_token  5.25 Process a token on a security
                                   context from a peer application
   gss_context_time           5.7  Determine for how long a context
                                   will remain valid
   gss_inquire_context        5.20 Obtain information about a
                                   security context
   gss_wrap_size_limit        5.34 Determine token-size limit for
                                   gss_wrap on a context
   gss_export_sec_context     5.14 Transfer a security context to
                                   another process
   gss_import_sec_context     5.17 Import a transferred context


   Table 2-3  GSS-API Per-message Routines

   Routine                 Section              Function
   -------                 -------              --------
   gss_get_mic                5.15 Calculate a cryptographic message
                                   integrity code (MIC) for a
                                   message; integrity service
   gss_verify_mic             5.32 Check a MIC against a message;
                                   verify integrity of a received
                                   message
   gss_wrap                   5.33 Attach a MIC to a message, and
                                   optionally encrypt the message
                                   content;
                                   confidentiality service
   gss_unwrap                 5.31 Verify a message with attached
                                   MIC, and decrypt message content
                                   if necessary.











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   Table 2-4  GSS-API Name manipulation Routines

   Routine                 Section              Function
   -------                 -------              --------
   gss_import_name            5.16 Convert a contiguous string name
                                   to internal-form
   gss_display_name           5.10 Convert internal-form name to
                                   text
   gss_compare_name           5.6  Compare two internal-form names

   gss_release_name           5.28 Discard an internal-form name
   gss_inquire_names_for_mech 5.24 List the name-types supported by
                                   the specified mechanism
   gss_inquire_mechs_for_name 5.23 List mechanisms that support the
                                   specified name-type
   gss_canonicalize_name      5.5  Convert an internal name to an MN
   gss_export_name            5.13 Convert an MN to export form
   gss_duplicate_name         5.12 Create a copy of an internal name


   Table 2-5  GSS-API Miscellaneous Routines

   Routine                Section              Function
   -------                -------              --------
   gss_add_oid_set_member    5.4  Add an object identifier to
                                  a set
   gss_display_status        5.11 Convert a GSS-API status code
                                  to text
   gss_indicate_mechs        5.18 Determine available underlying
                                  authentication mechanisms
   gss_release_buffer        5.26 Discard a buffer
   gss_release_oid_set       5.29 Discard a set of object
                                  identifiers
   gss_create_empty_oid_set  5.8  Create a set containing no
                                  object identifiers
   gss_test_oid_set_member   5.30 Determines whether an object
                                       identifier is a member of a set.

   Individual GSS-API implementations may augment these routines by
   providing additional mechanism-specific routines if required
   functionality is not available from the generic forms. Applications
   are encouraged to use the generic routines wherever possible on
   portability grounds.








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<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>.   Data Types and Calling Conventions</span>

   The following conventions are used by the GSS-API C-language
   bindings:

<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. Integer types</span>

   GSS-API uses the following integer data type:

   OM_uint32    32-bit unsigned integer

   Where guaranteed minimum bit-count is important, this portable data
   type is used by the GSS-API routine definitions.  Individual GSS-API
   implementations will include appropriate typedef definitions to map
   this type onto a built-in data type.  If the platform supports the
   X/Open xom.h header file, the OM_uint32 definition contained therein
   should be used; the GSS-API header file in <a href="#appendix-A">Appendix A</a> contains logic
   that will detect the prior inclusion of xom.h, and will not attempt
   to re-declare OM_uint32.  If the X/Open header file is not available
   on the platform, the GSS-API implementation should use the smallest
   natural unsigned integer type that provides at least 32 bits of
   precision.

<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. String and similar data</span>

   Many of the GSS-API routines take arguments and return values that
   describe contiguous octet-strings.  All such data is passed between
   the GSS-API and the caller using the gss_buffer_t data type.  This
   data type is a pointer to a buffer descriptor, which consists of a
   length field that contains the total number of bytes in the datum,
   and a value field which contains a pointer to the actual datum:

   typedef struct gss_buffer_desc_struct {
      size_t    length;
      void      *value;
   } gss_buffer_desc, *gss_buffer_t;

   Storage for data returned to the application by a GSS-API routine
   using the gss_buffer_t conventions is allocated by the GSS-API
   routine.  The application may free this storage by invoking the
   gss_release_buffer routine.  Allocation of the gss_buffer_desc object
   is always the responsibility of the application;  unused
   gss_buffer_desc objects may be initialized to the value
   GSS_C_EMPTY_BUFFER.







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<span class="h4"><a class="selflink" id="section-3.2.1" href="#section-3.2.1">3.2.1</a>. Opaque data types</span>

   Certain multiple-word data items are considered opaque data types at
   the GSS-API, because their internal structure has no significance
   either to the GSS-API or to the caller.  Examples of such opaque data
   types are the input_token parameter to gss_init_sec_context (which is
   opaque to the caller), and the input_message parameter to gss_wrap
   (which is opaque to the GSS-API).  Opaque data is passed between the
   GSS-API and the application using the gss_buffer_t datatype.

<span class="h4"><a class="selflink" id="section-3.2.2" href="#section-3.2.2">3.2.2</a>. Character strings</span>

   Certain multiple-word data items may be regarded as simple ISO
   Latin-1 character strings.  Examples are the printable strings passed
   to gss_import_name via the input_name_buffer parameter. Some GSS-API
   routines also return character strings.  All such character strings
   are passed between the application and the GSS-API implementation
   using the gss_buffer_t datatype, which is a pointer to a
   gss_buffer_desc object.

   When a gss_buffer_desc object describes a printable string, the
   length field of the gss_buffer_desc should only count printable
   characters within the string.  In particular, a trailing NUL
   character should NOT be included in the length count, nor should
   either the GSS-API implementation or the application assume the
   presence of an uncounted trailing NUL.

<span class="h3"><a class="selflink" id="section-3.3" href="#section-3.3">3.3</a>. Object Identifiers</span>

   Certain GSS-API procedures take parameters of the type gss_OID, or
   Object identifier.  This is a type containing ISO-defined tree-
   structured values, and is used by the GSS-API caller to select an
   underlying security mechanism and to specify namespaces.  A value of
   type gss_OID has the following structure:

   typedef struct gss_OID_desc_struct {
      OM_uint32   length;
      void        *elements;
   } gss_OID_desc, *gss_OID;

   The elements field of this structure points to the first byte of an
   octet string containing the ASN.1 BER encoding of the value portion
   of the normal BER TLV encoding of the gss_OID.  The length field
   contains the number of bytes in this value.  For example, the gss_OID
   value corresponding to {iso(1) identified-organization(3) icd-
   ecma(12) member-company(2) dec(1011) cryptoAlgorithms(7) DASS(5)},
   meaning the DASS X.509 authentication mechanism, has a length field
   of 7 and an elements field pointing to seven octets containing the



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   following octal values: 53,14,2,207,163,7,5. GSS-API implementations
   should provide constant gss_OID values to allow applications to
   request any supported mechanism, although applications are encouraged
   on portability grounds to accept the default mechanism.  gss_OID
   values should also be provided to allow applications to specify
   particular name types (see <a href="#section-3.10">section 3.10</a>).  Applications should treat
   gss_OID_desc values returned by GSS-API routines as read-only.  In
   particular, the application should not attempt to deallocate them
   with free().  The gss_OID_desc datatype is equivalent to the X/Open
   OM_object_identifier datatype[XOM].

<span class="h3"><a class="selflink" id="section-3.4" href="#section-3.4">3.4</a>. Object Identifier Sets</span>

   Certain GSS-API procedures take parameters of the type gss_OID_set.
   This type represents one or more object identifiers (<a href="#section-2.3">section 2.3</a>).  A
   gss_OID_set object has the following structure:

   typedef struct gss_OID_set_desc_struct {
      size_t    count;
      gss_OID   elements;
   } gss_OID_set_desc, *gss_OID_set;

   The count field contains the number of OIDs within the set.  The
   elements field is a pointer to an array of gss_OID_desc objects, each
   of which describes a single OID.  gss_OID_set values are used to name
   the available mechanisms supported by the GSS-API, to request the use
   of specific mechanisms, and to indicate which mechanisms a given
   credential supports.

   All OID sets returned to the application by GSS-API are dynamic
   objects (the gss_OID_set_desc, the "elements" array of the set, and
   the "elements" array of each member OID are all dynamically
   allocated), and this storage must be deallocated by the application
   using the gss_release_oid_set() routine.

<span class="h3"><a class="selflink" id="section-3.5" href="#section-3.5">3.5</a>. Credentials</span>

   A credential handle is a caller-opaque atomic datum that identifies a
   GSS-API credential data structure.  It is represented by the caller-
   opaque type gss_cred_id_t, which should be implemented as a pointer
   or arithmetic type.  If a pointer implementation is chosen, care must
   be taken to ensure that two gss_cred_id_t values may be compared with
   the == operator.

   GSS-API credentials can contain mechanism-specific principal
   authentication data for multiple mechanisms.  A GSS-API credential is
   composed of a set of credential-elements, each of which is applicable
   to a single mechanism.  A credential may contain at most one



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   credential-element for each supported mechanism. A credential-element
   identifies the data needed by a single mechanism to authenticate a
   single principal, and conceptually contains two credential-references
   that describe the actual mechanism-specific authentication data, one
   to be used by GSS-API for initiating contexts,  and one to be used
   for accepting contexts.  For mechanisms that do not distinguish
   between acceptor and initiator credentials, both references would
   point to the same underlying mechanism-specific authentication data.

   Credentials describe a set of mechanism-specific principals, and give
   their holder the ability to act as any of those principals. All
   principal identities asserted by a single GSS-API credential should
   belong to the same entity, although enforcement of this property is
   an implementation-specific matter.  The GSS-API does not make the
   actual credentials available to applications; instead a credential
   handle is used to identify a particular credential, held internally
   by GSS-API.  The combination of GSS-API credential handle and
   mechanism identifies the principal whose identity will be asserted by
   the credential when used with that mechanism.

   The gss_init_sec_context and gss_accept_sec_context routines allow
   the value GSS_C_NO_CREDENTIAL to be specified as their credential
   handle parameter.  This special credential-handle indicates a desire
   by the application to act as a default principal.  While individual
   GSS-API implementations are free to determine such default behavior
   as appropriate to the mechanism, the following default behavior by
   these routines is recommended for portability:

   gss_init_sec_context

      1) If there is only a single principal capable of initiating
         security contexts for the chosen mechanism that the application
         is authorized to act on behalf of, then that principal shall be
         used, otherwise

      2) If the platform maintains a concept of a default network-
         identity for the chosen mechanism, and if the application is
         authorized to act on behalf of that identity for the purpose of
         initiating security contexts, then the principal corresponding
         to that identity shall be used, otherwise

      3) If the platform maintains a concept of a default local
         identity, and provides a means to map local identities into
         network-identities for the chosen mechanism, and if the
         application is authorized to act on behalf of the network-
         identity image of the default local identity for the purpose of





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         initiating security contexts using the chosen mechanism, then
         the principal corresponding to that identity shall be used,
         otherwise

      4) A user-configurable default identity should be used.

   gss_accept_sec_context

      1) If there is only a single authorized principal identity capable
         of accepting security contexts for the chosen mechanism, then
         that principal shall be used, otherwise

      2) If the mechanism can determine the identity of the target
         principal by examining the context-establishment token, and if
         the accepting application is authorized to act as that
         principal for the purpose of accepting security contexts using
         the chosen mechanism, then that principal identity shall be
         used, otherwise

      3) If the mechanism supports context acceptance by any principal,
         and if mutual authentication was not requested, any principal
         that the application is authorized to accept security contexts
         under using the chosen mechanism may be used, otherwise

      4)A user-configurable default identity shall be used.

   The purpose of the above rules is to allow security contexts to be
   established by both initiator and acceptor using the default behavior
   wherever possible.  Applications requesting default behavior are
   likely to be more portable across mechanisms and platforms than ones
   that use gss_acquire_cred to request a specific identity.

<span class="h3"><a class="selflink" id="section-3.6" href="#section-3.6">3.6</a>. Contexts</span>

   The gss_ctx_id_t data type contains a caller-opaque atomic value that
   identifies one end of a GSS-API security context.  It should be
   implemented as a pointer or arithmetic type.  If a pointer type is
   chosen, care should be taken to ensure that two gss_ctx_id_t values
   may be compared with the == operator.

   The security context holds state information about each end of a peer
   communication, including cryptographic state information.









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<span class="h3"><a class="selflink" id="section-3.7" href="#section-3.7">3.7</a>. Authentication tokens</span>

   A token is a caller-opaque type that GSS-API uses to maintain
   synchronization between the context data structures at each end of a
   GSS-API security context.  The token is a cryptographically protected
   octet-string, generated by the underlying mechanism at one end of a
   GSS-API security context for use by the peer mechanism at the other
   end.  Encapsulation (if required) and transfer of the token are the
   responsibility of the peer applications.  A token is passed between
   the GSS-API and the application using the gss_buffer_t conventions.

<span class="h3"><a class="selflink" id="section-3.8" href="#section-3.8">3.8</a>. Interprocess tokens</span>

   Certain GSS-API routines are intended to transfer data between
   processes in multi-process programs.  These routines use a caller-
   opaque octet-string, generated by the GSS-API in one process for use
   by the GSS-API in another process.  The calling application is
   responsible for transferring such tokens between processes in an OS-
   specific manner.  Note that, while GSS-API implementors are
   encouraged to avoid placing sensitive information within interprocess
   tokens, or to cryptographically protect them, many implementations
   will be unable to avoid placing key material or other sensitive data
   within them.  It is the application's responsibility to ensure that
   interprocess tokens are protected in transit, and transferred only to
   processes that are trustworthy. An interprocess token is passed
   between the GSS-API and the application using the gss_buffer_t
   conventions.

<span class="h3"><a class="selflink" id="section-3.9" href="#section-3.9">3.9</a>. Status values</span>

   Every GSS-API routine returns two distinct values to report status
   information to the caller: GSS status codes and Mechanism status
   codes.

<span class="h4"><a class="selflink" id="section-3.9.1" href="#section-3.9.1">3.9.1</a>. GSS status codes</span>

   GSS-API routines return GSS status codes as their OM_uint32 function
   value.  These codes indicate errors that are independent of the
   underlying mechanism(s) used to provide the security service.  The
   errors that can be indicated via a GSS status code are either generic
   API routine errors (errors that are defined in the GSS-API
   specification) or calling errors (errors that are specific to these
   language bindings).

   A GSS status code can indicate a single fatal generic API error from
   the routine and a single calling error.  In addition, supplementary
   status information may be indicated via the setting of bits in the
   supplementary info field of a GSS status code.



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   These errors are encoded into the 32-bit GSS status code as follows:

      MSB                                                        LSB
      |------------------------------------------------------------|
      |  Calling Error | Routine Error  |    Supplementary Info    |
      |------------------------------------------------------------|
   Bit 31            24 23            16 15                       0

   Hence if a GSS-API routine returns a GSS status code whose upper 16
   bits contain a non-zero value, the call failed.  If the calling error
   field is non-zero, the invoking application's call of the routine was
   erroneous.  Calling errors are defined in table 5-1.  If the routine
   error field is non-zero, the routine failed for one of the routine-
   specific reasons listed below in table 5-2.  Whether or not the upper
   16 bits indicate a failure or a success, the routine may indicate
   additional information by setting bits in the supplementary info
   field of the status code. The meaning of individual bits is listed
   below in table 5-3.

   Table 3-1  Calling Errors

   Name                   Value in field           Meaning
   ----                   --------------           -------
   GSS_S_CALL_INACCESSIBLE_READ  1       A required input parameter
                                         could not be read
   GSS_S_CALL_INACCESSIBLE_WRITE 2       A required output parameter
                                          could not be written.
   GSS_S_CALL_BAD_STRUCTURE      3       A parameter was malformed























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   Table 3-2  Routine Errors

   Name                   Value in field           Meaning
   ----                   --------------           -------
   GSS_S_BAD_MECH                1       An unsupported mechanism
                                         was requested
   GSS_S_BAD_NAME                2       An invalid name was
                                         supplied
   GSS_S_BAD_NAMETYPE            3       A supplied name was of an
                                         unsupported type
   GSS_S_BAD_BINDINGS            4       Incorrect channel bindings
                                         were supplied
   GSS_S_BAD_STATUS              5       An invalid status code was
                                         supplied
   GSS_S_BAD_MIC GSS_S_BAD_SIG   6       A token had an invalid MIC
   GSS_S_NO_CRED                 7       No credentials were
                                         supplied, or the
                                         credentials were
                                         unavailable or
                                         inaccessible.
   GSS_S_NO_CONTEXT              8       No context has been
                                         established
   GSS_S_DEFECTIVE_TOKEN         9       A token was invalid
   GSS_S_DEFECTIVE_CREDENTIAL   10       A credential was invalid
   GSS_S_CREDENTIALS_EXPIRED    11       The referenced credentials
                                         have expired
   GSS_S_CONTEXT_EXPIRED        12       The context has expired
   GSS_S_FAILURE                13       Miscellaneous failure (see
                                         text)
   GSS_S_BAD_QOP                14       The quality-of-protection
                                         requested could not be
                                         provided
   GSS_S_UNAUTHORIZED           15       The operation is forbidden
                                         by local security policy
   GSS_S_UNAVAILABLE            16       The operation or option is
                                         unavailable
   GSS_S_DUPLICATE_ELEMENT      17       The requested credential
                                         element already exists
   GSS_S_NAME_NOT_MN            18       The provided name was not a
                                         mechanism name











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   Table 3-3  Supplementary Status Bits

   Name                   Bit Number           Meaning
   ----                   ----------           -------
   GSS_S_CONTINUE_NEEDED   0 (LSB)   Returned only by
                                     gss_init_sec_context or
                                     gss_accept_sec_context. The
                                     routine must be called again
                                     to complete its function.
                                     See routine documentation for
                                     detailed description
   GSS_S_DUPLICATE_TOKEN   1         The token was a duplicate of
                                     an earlier token
   GSS_S_OLD_TOKEN         2         The token's validity period
                                     has expired
   GSS_S_UNSEQ_TOKEN       3         A later token has already been
                                     processed
   GSS_S_GAP_TOKEN         4         An expected per-message token
                                     was not received

   The routine documentation also uses the name GSS_S_COMPLETE, which is
   a zero value, to indicate an absence of any API errors or
   supplementary information bits.

   All GSS_S_xxx symbols equate to complete OM_uint32 status codes,
   rather than to bitfield values.  For example, the actual value of the
   symbol GSS_S_BAD_NAMETYPE (value 3 in the routine error field) is
   3&lt;&lt;16.  The macros GSS_CALLING_ERROR(), GSS_ROUTINE_ERROR() and
   GSS_SUPPLEMENTARY_INFO() are provided, each of which takes a GSS
   status code and removes all but the relevant field.  For example, the
   value obtained by applying GSS_ROUTINE_ERROR to a status code removes
   the calling errors and supplementary info fields, leaving only the
   routine errors field.  The values delivered by these macros may be
   directly compared with a GSS_S_xxx symbol of the appropriate type.
   The macro GSS_ERROR() is also provided, which when applied to a GSS
   status code returns a non-zero value if the status code indicated a
   calling or routine error, and a zero value otherwise.  All macros
   defined by GSS-API evaluate their argument(s) exactly once.

   A GSS-API implementation may choose to signal calling errors in a
   platform-specific manner instead of, or in addition to the routine
   value;  routine errors and supplementary info should be returned via
   major status values only.

   The GSS major status code GSS_S_FAILURE is used to indicate that the
   underlying mechanism detected an error for which no specific GSS
   status code is defined.  The mechanism-specific status code will
   provide more details about the error.



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<span class="h4"><a class="selflink" id="section-3.9.2" href="#section-3.9.2">3.9.2</a>. Mechanism-specific status codes</span>

   GSS-API routines return a minor_status parameter, which is used to
   indicate specialized errors from the underlying security mechanism.
   This parameter may contain a single mechanism-specific error,
   indicated by a OM_uint32 value.

   The minor_status parameter will always be set by a GSS-API routine,
   even if it returns a calling error or one of the generic API errors
   indicated above as fatal, although most other output parameters may
   remain unset in such cases.  However, output parameters that are
   expected to return pointers to storage allocated by a routine must
   always be set by the routine, even in the event of an error, although
   in such cases the GSS-API routine may elect to set the returned
   parameter value to NULL to indicate that no storage was actually
   allocated.  Any length field associated with such pointers (as in a
   gss_buffer_desc structure) should also be set to zero in such cases.

<span class="h3"><a class="selflink" id="section-3.10" href="#section-3.10">3.10</a>. Names</span>

   A name is used to identify a person or entity.  GSS-API authenticates
   the relationship between a name and the entity claiming the name.

   Since different authentication mechanisms may employ different
   namespaces for identifying their principals, GSSAPI's naming support
   is necessarily complex in multi-mechanism environments (or even in
   some single-mechanism environments where the underlying mechanism
   supports multiple namespaces).

   Two distinct representations are defined for names:

   An internal form.  This is the GSS-API "native" format for names,
      represented by the implementation-specific gss_name_t type.  It is
      opaque to GSS-API callers.  A single gss_name_t object may contain
      multiple names from different namespaces, but all names should
      refer to the same entity.  An example of such an internal name
      would be the name returned from a call to the gss_inquire_cred
      routine, when applied to a credential containing credential
      elements for multiple authentication mechanisms employing
      different namespaces.  This gss_name_t object will contain a
      distinct name for the entity for each authentication mechanism.

      For GSS-API implementations supporting multiple namespaces,
      objects of type gss_name_t must contain sufficient information to
      determine the namespace to which each primitive name belongs.






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   Mechanism-specific contiguous octet-string forms.  A format
      capable of containing a single name (from a single namespace).
      Contiguous string names are always accompanied by an object
      identifier specifying the namespace to which the name belongs, and
      their format is dependent on the authentication mechanism that
      employs the name.  Many, but not all, contiguous string names will
      be printable, and may therefore be used by GSS-API applications
      for communication with their users.

   Routines (gss_import_name and gss_display_name) are provided to
   convert names between contiguous string representations and the
   internal gss_name_t type.  gss_import_name may support multiple
   syntaxes for each supported namespace, allowing users the freedom to
   choose a preferred name representation. gss_display_name should use
   an implementation-chosen printable syntax for each supported name-
   type.

   If an application calls gss_display_name(), passing the internal name
   resulting from a call to gss_import_name(), there is no guarantee the
   the resulting contiguous string name will be the same as the original
   imported string name.  Nor do name-space identifiers necessarily
   survive unchanged after a journey through the internal name-form.  An
   example of this might be a mechanism that authenticates X.500 names,
   but provides an algorithmic mapping of Internet DNS names into X.500.
   That mechanism's implementation of gss_import_name() might, when
   presented with a DNS name, generate an internal name that contained
   both the original DNS name and the equivalent X.500 name.
   Alternatively, it might only store the X.500 name.  In the latter
   case, gss_display_name() would most likely generate a printable X.500
   name, rather than the original DNS name.

   The process of authentication delivers to the context acceptor an
   internal name.  Since this name has been authenticated by a single
   mechanism, it contains only a single name (even if the internal name
   presented by the context initiator to gss_init_sec_context had
   multiple components).  Such names are termed internal mechanism
   names, or "MN"s and the names emitted by gss_accept_sec_context() are
   always of this type.  Since some applications may require MNs without
   wanting to incur the overhead of an authentication operation, a
   second function, gss_canonicalize_name(), is provided to convert a
   general internal name into an MN.

   Comparison of internal-form names may be accomplished via the
   gss_compare_name() routine, which returns true if the two names being
   compared refer to the same entity.  This removes the need for the
   application program to understand the syntaxes of the various
   printable names that a given GSS-API implementation may support.
   Since GSS-API assumes that all primitive names contained within a



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   given internal name refer to the same entity, gss_compare_name() can
   return true if the two names have at least one primitive name in
   common.  If the implementation embodies knowledge of equivalence
   relationships between names taken from different namespaces, this
   knowledge may also allow successful comparison of internal names
   containing no overlapping primitive elements.

   When used in large access control lists, the overhead of invoking
   gss_import_name() and gss_compare_name() on each name from the ACL
   may be prohibitive.  As an alternative way of supporting this case,
   GSS-API defines a special form of the contiguous string name which
   may be compared directly (e.g. with memcmp()).  Contiguous names
   suitable for comparison are generated by the gss_export_name()
   routine, which requires an MN as input.  Exported names may be re-
   imported by the gss_import_name() routine, and the resulting internal
   name will also be an MN.  The gss_OID constant GSS_C_NT_EXPORT_NAME
   indentifies the "export name" type, and the value of this constant is
   given in <a href="#appendix-A">Appendix A</a>.  Structurally, an exported name object consists
   of a header containing an OID identifying the mechanism that
   authenticated the name, and a trailer containing the name itself,
   where the syntax of the trailer is defined by the individual
   mechanism specification.   The precise format of an export name is
   defined in the language-independent GSS-API specification [<a href="#ref-GSSAPI" title="&quot;Generic Security Service Application Program Interface Version 2, Update 1&quot;">GSSAPI</a>].

   Note that the results obtained by using gss_compare_name() will in
   general be different from those obtained by invoking
   gss_canonicalize_name() and gss_export_name(), and then comparing the
   exported names.  The first series of operation determines whether two
   (unauthenticated) names identify the same principal; the second
   whether a particular mechanism would authenticate them as the same
   principal.  These two operations will in general give the same
   results only for MNs.

   The gss_name_t datatype should be implemented as a pointer type. To
   allow the compiler to aid the application programmer by performing
   type-checking, the use of (void *) is discouraged.  A pointer to an
   implementation-defined type is the preferred choice.

   Storage is allocated by routines that return gss_name_t values. A
   procedure, gss_release_name, is provided to free storage associated
   with an internal-form name.










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<span class="h3"><a class="selflink" id="section-3.11" href="#section-3.11">3.11</a>. Channel Bindings</span>

   GSS-API supports the use of user-specified tags to identify a given
   context to the peer application.  These tags are intended to be used
   to identify the particular communications channel that carries the
   context.  Channel bindings are communicated to the GSS-API using the
   following structure:

   typedef struct gss_channel_bindings_struct {
      OM_uint32       initiator_addrtype;
      gss_buffer_desc initiator_address;
      OM_uint32       acceptor_addrtype;
      gss_buffer_desc acceptor_address;
      gss_buffer_desc application_data;
   } *gss_channel_bindings_t;

   The initiator_addrtype and acceptor_addrtype fields denote the type
   of addresses contained in the initiator_address and acceptor_address
   buffers.  The address type should be one of the following:

   GSS_C_AF_UNSPEC     Unspecified address type
   GSS_C_AF_LOCAL      Host-local address type
   GSS_C_AF_INET       Internet address type (e.g. IP)
   GSS_C_AF_IMPLINK    ARPAnet IMP address type
   GSS_C_AF_PUP        pup protocols (eg BSP) address type
   GSS_C_AF_CHAOS      MIT CHAOS protocol address type
   GSS_C_AF_NS         XEROX NS address type
   GSS_C_AF_NBS        nbs address type
   GSS_C_AF_ECMA       ECMA address type
   GSS_C_AF_DATAKIT    datakit protocols address type
   GSS_C_AF_CCITT      CCITT protocols
   GSS_C_AF_SNA        IBM SNA address type
   GSS_C_AF_DECnet     DECnet address type
   GSS_C_AF_DLI        Direct data link interface address type
   GSS_C_AF_LAT        LAT address type
   GSS_C_AF_HYLINK     NSC Hyperchannel address type
   GSS_C_AF_APPLETALK  AppleTalk address type
   GSS_C_AF_BSC        BISYNC 2780/3780 address type
   GSS_C_AF_DSS        Distributed system services address type
   GSS_C_AF_OSI        OSI TP4 address type
   GSS_C_AF_X25        X.25
   GSS_C_AF_NULLADDR   No address specified

   Note that these symbols name address families rather than specific
   addressing formats.  For address families that contain several
   alternative address forms, the initiator_address and acceptor_address
   fields must contain sufficient information to determine which address




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   form is used.  When not otherwise specified, addresses should be
   specified in network byte-order (that is, native byte-ordering for
   the address family).

   Conceptually, the GSS-API concatenates the initiator_addrtype,
   initiator_address, acceptor_addrtype, acceptor_address and
   application_data to form an octet string.  The mechanism calculates a
   MIC over this octet string, and binds the MIC to the context
   establishment token emitted by gss_init_sec_context. The same
   bindings are presented by the context acceptor to
   gss_accept_sec_context, and a MIC is calculated in the same way. The
   calculated MIC is compared with that found in the token, and if the
   MICs differ, gss_accept_sec_context will return a GSS_S_BAD_BINDINGS
   error, and the context will not be established.  Some mechanisms may
   include the actual channel binding data in the token (rather than
   just a MIC); applications should therefore not use confidential data
   as channel-binding components.

   Individual mechanisms may impose additional constraints on addresses
   and address types that may appear in channel bindings.  For example,
   a mechanism may verify that the initiator_address field of the
   channel bindings presented to gss_init_sec_context contains the
   correct network address of the host system.  Portable applications
   should therefore ensure that they either provide correct information
   for the address fields, or omit addressing information, specifying
   GSS_C_AF_NULLADDR as the address-types.

<span class="h3"><a class="selflink" id="section-3.12" href="#section-3.12">3.12</a>. Optional parameters</span>

   Various parameters are described as optional.  This means that they
   follow a convention whereby a default value may be requested.  The
   following conventions are used for omitted parameters.  These
   conventions apply only to those parameters that are explicitly
   documented as optional.

<span class="h4"><a class="selflink" id="section-3.12.1" href="#section-3.12.1">3.12.1</a>. gss_buffer_t types</span>

   Specify GSS_C_NO_BUFFER as a value.  For an input parameter this
   signifies that default behavior is requested, while for an output
   parameter it indicates that the information that would be returned
   via the parameter is not required by the application.

<span class="h4"><a class="selflink" id="section-3.12.2" href="#section-3.12.2">3.12.2</a>. Integer types (input)</span>

   Individual parameter documentation lists values to be used to
   indicate default actions.





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<span class="h4"><a class="selflink" id="section-3.12.3" href="#section-3.12.3">3.12.3</a>. Integer types (output)</span>

   Specify NULL as the value for the pointer.

<span class="h4"><a class="selflink" id="section-3.12.4" href="#section-3.12.4">3.12.4</a>. Pointer types</span>

   Specify NULL as the value.

<span class="h4"><a class="selflink" id="section-3.12.5" href="#section-3.12.5">3.12.5</a>. Object IDs</span>

   Specify GSS_C_NO_OID as the value.

<span class="h4"><a class="selflink" id="section-3.12.6" href="#section-3.12.6">3.12.6</a>. Object ID Sets</span>

   Specify GSS_C_NO_OID_SET as the value.

<span class="h4"><a class="selflink" id="section-3.12.7" href="#section-3.12.7">3.12.7</a>. Channel Bindings</span>

   Specify GSS_C_NO_CHANNEL_BINDINGS to indicate that channel bindings
   are not to be used.

<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>.   Additional Controls</span>

   This section discusses the optional services that a context initiator
   may request of the GSS-API at context establishment. Each of these
   services is requested by setting a flag in the req_flags input
   parameter to gss_init_sec_context.

   The optional services currently defined are:

   Delegation - The (usually temporary) transfer of rights from
       initiator to acceptor, enabling the acceptor to authenticate
       itself as an agent of the initiator.

   Mutual Authentication - In addition to the initiator authenticating
       its identity to the context acceptor, the context acceptor should
       also authenticate itself to the initiator.

   Replay detection - In addition to providing message integrity
       services, gss_get_mic and gss_wrap should include message
       numbering information to enable gss_verify_mic and gss_unwrap to
       detect if a message has been duplicated.

   Out-of-sequence detection - In addition to providing message
       integrity services, gss_get_mic and gss_wrap should include
       message sequencing information to enable gss_verify_mic and
       gss_unwrap to detect if a message has been received out of
       sequence.



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   Anonymous authentication - The establishment of the security context
       should not reveal the initiator's identity to the context
       acceptor.

   Any currently undefined bits within such flag arguments should be
   ignored by GSS-API implementations when presented by an application,
   and should be set to zero when returned to the application by the
   GSS-API implementation.

   Some mechanisms may not support all optional services, and some
   mechanisms may only support some services in conjunction with others.
   Both gss_init_sec_context and gss_accept_sec_context inform the
   applications which services will be available from the context when
   the establishment phase is complete, via the ret_flags output
   parameter.  In general, if the security mechanism is capable of
   providing a requested service, it should do so, even if additional
   services must be enabled in order to provide the requested service.
   If the mechanism is incapable of providing a requested service, it
   should proceed without the service, leaving the application to abort
   the context establishment process if it considers the requested
   service to be mandatory.

   Some mechanisms may specify that support for some services is
   optional, and that implementors of the mechanism need not provide it.
   This is most commonly true of the confidentiality service, often
   because of legal restrictions on the use of data-encryption, but may
   apply to any of the services.  Such mechanisms are required to send
   at least one token from acceptor to initiator during context
   establishment when the initiator indicates a desire to use such a
   service, so that the initiating GSS-API can correctly indicate
   whether the service is supported by the acceptor's GSS-API.

<span class="h3"><a class="selflink" id="section-4.1" href="#section-4.1">4.1</a>. Delegation</span>

   The GSS-API allows delegation to be controlled by the initiating
   application via a boolean parameter to gss_init_sec_context(), the
   routine that establishes a security context.  Some mechanisms do not
   support delegation, and for such mechanisms attempts by an
   application to enable delegation are ignored.

   The acceptor of a security context for which the initiator enabled
   delegation will receive (via the delegated_cred_handle parameter of
   gss_accept_sec_context) a credential handle that contains the
   delegated identity, and this credential handle may be used to
   initiate subsequent GSS-API security contexts as an agent or delegate
   of the initiator.  If the original initiator's identity is "A" and
   the delegate's identity is "B", then, depending on the underlying
   mechanism, the identity embodied by the delegated credential may be



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   either "A" or "B acting for A".

   For many mechanisms that support delegation, a simple boolean does
   not provide enough control.  Examples of additional aspects of
   delegation control that a mechanism might provide to an application
   are duration of delegation, network addresses from which delegation
   is valid, and constraints on the tasks that may be performed by a
   delegate.  Such controls are presently outside the scope of the GSS-
   API.  GSS-API implementations supporting mechanisms offering
   additional controls should provide extension routines that allow
   these controls to be exercised (perhaps by modifying the initiator's
   GSS-API credential prior to its use in establishing a context).
   However, the simple delegation control provided by GSS-API should
   always be able to over-ride other mechanism-specific delegation
   controls - If the application instructs gss_init_sec_context() that
   delegation is not desired, then the implementation must not permit
   delegation to occur. This is an exception to the general rule that a
   mechanism may enable services even if they are not requested -
   delegation may only be provided at the explicit request of the
   application.

<span class="h3"><a class="selflink" id="section-4.2" href="#section-4.2">4.2</a>. Mutual authentication</span>

   Usually, a context acceptor will require that a context initiator
   authenticate itself so that the acceptor may make an access-control
   decision prior to performing a service for the initiator.  In some
   cases, the initiator may also request that the acceptor authenticate
   itself.  GSS-API allows the initiating application to request this
   mutual authentication service by setting a flag when calling
   gss_init_sec_context.

   The initiating application is informed as to whether or not the
   context acceptor has authenticated itself.  Note that some mechanisms
   may not support mutual authentication, and other mechanisms may
   always perform mutual authentication, whether or not the initiating
   application requests it.  In particular, mutual authentication my be
   required by some mechanisms in order to support replay or out-of-
   sequence message detection, and for such mechanisms a request for
   either of these services will automatically enable mutual
   authentication.











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<span class="h3"><a class="selflink" id="section-4.3" href="#section-4.3">4.3</a>. Replay and out-of-sequence detection</span>

   The GSS-API may provide detection of mis-ordered message once a
   security context has been established.  Protection may be applied to
   messages by either application, by calling either gss_get_mic or
   gss_wrap, and verified by the peer application by calling
   gss_verify_mic or gss_unwrap.

   gss_get_mic calculates a cryptographic MIC over an application
   message, and returns that MIC in a token.  The application should
   pass both the token and the message to the peer application, which
   presents them to gss_verify_mic.

   gss_wrap calculates a cryptographic MIC of an application message,
   and places both the MIC and the message inside a single token.  The
   Application should pass the token to the peer application, which
   presents it to gss_unwrap to extract the message and verify the MIC.

   Either pair of routines may be capable of detecting out-of-sequence
   message delivery, or duplication of messages. Details of such mis-
   ordered messages are indicated through supplementary status bits in
   the major status code returned by gss_verify_mic or gss_unwrap.  The
   relevant supplementary bits are:

   GSS_S_DUPLICATE_TOKEN - The token is a duplicate of one that has
                    already been received and processed.  Only
                    contexts that claim to provide replay detection
                    may set this bit.
   GSS_S_OLD_TOKEN - The token is too old to determine whether or
                    not it is a duplicate.  Contexts supporting
                    out-of-sequence detection but not replay
                    detection should always set this bit if
                    GSS_S_UNSEQ_TOKEN is set; contexts that support
                    replay detection should only set this bit if the
                    token is so old that it cannot be checked for
                    duplication.
   GSS_S_UNSEQ_TOKEN - A later token has already been processed.
   GSS_S_GAP_TOKEN - An earlier token has not yet been received.

   A mechanism need not maintain a list of all tokens that have been
   processed in order to support these status codes.  A typical
   mechanism might retain information about only the most recent "N"
   tokens processed, allowing it to distinguish duplicates and missing
   tokens within the most recent "N" messages; the receipt of a token
   older than the most recent "N" would result in a GSS_S_OLD_TOKEN
   status.





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<span class="h3"><a class="selflink" id="section-4.4" href="#section-4.4">4.4</a>. Anonymous Authentication</span>

   In certain situations, an application may wish to initiate the
   authentication process to authenticate a peer, without revealing its
   own identity.  As an example, consider an application providing
   access to a database containing medical information, and offering
   unrestricted access to the service.  A client of such a service might
   wish to authenticate the service (in order to establish trust in any
   information retrieved from it), but might not wish the service to be
   able to obtain the client's identity (perhaps due to privacy concerns
   about the specific inquiries, or perhaps simply to avoid being placed
   on mailing-lists).

   In normal use of the GSS-API, the initiator's identity is made
   available to the acceptor as a result of the context establishment
   process.  However, context initiators may request that their identity
   not be revealed to the context acceptor. Many mechanisms do not
   support anonymous authentication, and for such mechanisms the request
   will not be honored.  An authentication token will be still be
   generated, but the application is always informed if a requested
   service is unavailable, and has the option to abort context
   establishment if anonymity is valued above the other security
   services that would require a context to be established.

   In addition to informing the application that a context is
   established anonymously (via the ret_flags outputs from
   gss_init_sec_context and gss_accept_sec_context), the optional
   src_name output from gss_accept_sec_context and gss_inquire_context
   will, for such contexts, return a reserved internal-form name,
   defined by the implementation.

   When presented to gss_display_name, this reserved internal-form name
   will result in a printable name that is syntactically distinguishable
   from any valid principal name supported by the implementation,
   associated with a name-type object identifier with the value
   GSS_C_NT_ANONYMOUS, whose value us given in <a href="#appendix-A">Appendix A</a>.  The
   printable form of an anonymous name should be chosen such that it
   implies anonymity, since this name may appear in, for example, audit
   logs.  For example, the string "&lt;anonymous&gt;" might be a good choice,
   if no valid printable names supported by the implementation can begin
   with "&lt;" and end with "&gt;".

<span class="h3"><a class="selflink" id="section-4.5" href="#section-4.5">4.5</a>. Confidentiality</span>

   If a context supports the confidentiality service, gss_wrap may be
   used to encrypt application messages.  Messages are selectively
   encrypted, under the control of the conf_req_flag input parameter to
   gss_wrap.



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<span class="h3"><a class="selflink" id="section-4.6" href="#section-4.6">4.6</a>. Inter-process context transfer</span>

   GSS-API V2 provides routines (gss_export_sec_context and
   gss_import_sec_context) which allow a security context to be
   transferred between processes on a single machine.  The most common
   use for such a feature is a client-server design where the server is
   implemented as a single process that accepts incoming security
   contexts, which then launches child processes to deal with the data
   on these contexts.  In such a design, the child processes must have
   access to the security context data structure created within the
   parent by its call to gss_accept_sec_context so that they can use
   per-message protection services and delete the security context when
   the communication session ends.

   Since the security context data structure is expected to contain
   sequencing information, it is impractical in general to share a
   context between processes.  Thus GSS-API provides a call
   (gss_export_sec_context) that the process which currently owns the
   context can call to declare that it has no intention to use the
   context subsequently, and to create an inter-process token containing
   information needed by the adopting process to successfully import the
   context.  After successful completion of gss_export_sec_context, the
   original security context is made inaccessible to the calling process
   by GSS-API, and any context handles referring to this context are no
   longer valid.  The originating process transfers the inter-process
   token to the adopting process, which passes it to
   gss_import_sec_context, and a fresh gss_ctx_id_t is created such that
   it is functionally identical to the original context.

   The inter-process token may contain sensitive data from the original
   security context (including cryptographic keys). Applications using
   inter-process tokens to transfer security contexts must take
   appropriate steps to protect these tokens in transit.

   Implementations are not required to support the inter-process
   transfer of security contexts.  The ability to transfer a security
   context is indicated when the context is created, by
   gss_init_sec_context or gss_accept_sec_context setting the
   GSS_C_TRANS_FLAG bit in their ret_flags parameter.

<span class="h3"><a class="selflink" id="section-4.7" href="#section-4.7">4.7</a>. The use of incomplete contexts</span>

   Some mechanisms may allow the per-message services to be used before
   the context establishment process is complete.  For example, a
   mechanism may include sufficient information in its initial context-
   level token for the context acceptor to immediately decode messages
   protected with gss_wrap or gss_get_mic.  For such a mechanism, the
   initiating application need not wait until subsequent context-level



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   tokens have been sent and received before invoking the per-message
   protection services.

   The ability of a context to provide per-message services in advance
   of complete context establishment is indicated by the setting of the
   GSS_C_PROT_READY_FLAG bit in the ret_flags parameter from
   gss_init_sec_context and gss_accept_sec_context. Applications wishing
   to use per-message protection services on partially-established
   contexts should check this flag before attempting to invoke gss_wrap
   or gss_get_mic.

<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. GSS-API Routine Descriptions</span>

   In addition to the explicit major status codes documented here, the
   code GSS_S_FAILURE may be returned by any routine, indicating an
   implementation-specific or mechanism-specific error condition,
   further details of which are reported via the minor_status parameter.

<span class="h3"><a class="selflink" id="section-5.1" href="#section-5.1">5.1</a>. gss_accept_sec_context</span>

   OM_uint32 gss_accept_sec_context (
     OM_uint32           *minor_status,
     gss_ctx_id_t        *context_handle,
     const gss_cred_id_t acceptor_cred_handle,
     const gss_buffer_t  input_token_buffer,
     const gss_channel_bindings_t  input_chan_bindings,
     const gss_name_t    *src_name,
     gss_OID             *mech_type,
     gss_buffer_t        output_token,
     OM_uint32           *ret_flags,
     OM_uint32           *time_rec,
     gss_cred_id_t       *delegated_cred_handle)

   Purpose:

   Allows a remotely initiated security context between the application
   and a remote peer to be established.  The routine may return a
   output_token which should be transferred to the peer application,
   where the peer application will present it to gss_init_sec_context.
   If no token need be sent, gss_accept_sec_context will indicate this
   by setting the length field of the output_token argument to zero.  To
   complete the context establishment, one or more reply tokens may be
   required from the peer application; if so, gss_accept_sec_context
   will return a status flag of GSS_S_CONTINUE_NEEDED, in which case it
   should be called again when the reply token is received from the peer
   application, passing the token to gss_accept_sec_context via the
   input_token parameters.




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   Portable applications should be constructed to use the token length
   and return status to determine whether a token needs to be sent or
   waited for.  Thus a typical portable caller should always invoke
   gss_accept_sec_context within a loop:

   gss_ctx_id_t context_hdl = GSS_C_NO_CONTEXT;

   do {
     receive_token_from_peer(input_token);
     maj_stat = gss_accept_sec_context(&amp;min_stat,
                                       &amp;context_hdl,
                                       cred_hdl,
                                       input_token,
                                       input_bindings,
                                       &amp;client_name,
                                       &amp;mech_type,
                                       output_token,
                                       &amp;ret_flags,
                                       &amp;time_rec,
                                       &amp;deleg_cred);
     if (GSS_ERROR(maj_stat)) {
       report_error(maj_stat, min_stat);
     };
     if (output_token-&gt;length != 0) {
       send_token_to_peer(output_token);

       gss_release_buffer(&amp;min_stat, output_token);
     };
     if (GSS_ERROR(maj_stat)) {
       if (context_hdl != GSS_C_NO_CONTEXT)
         gss_delete_sec_context(&amp;min_stat,
                                &amp;context_hdl,
                                GSS_C_NO_BUFFER);
       break;
     };
   } while (maj_stat &amp; GSS_S_CONTINUE_NEEDED);

   Whenever the routine returns a major status that includes the value
   GSS_S_CONTINUE_NEEDED, the context is not fully established and the
   following restrictions apply to the output parameters:

   The value returned via the time_rec parameter is undefined Unless the
   accompanying ret_flags parameter contains the bit
   GSS_C_PROT_READY_FLAG, indicating that per-message services may be
   applied in advance of a successful completion status, the value
   returned via the mech_type parameter may be undefined until the
   routine returns a major status value of GSS_S_COMPLETE.




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   The values of the GSS_C_DELEG_FLAG,
   GSS_C_MUTUAL_FLAG,GSS_C_REPLAY_FLAG, GSS_C_SEQUENCE_FLAG,
   GSS_C_CONF_FLAG,GSS_C_INTEG_FLAG and GSS_C_ANON_FLAG bits returned
   via the ret_flags parameter should contain the values that the
   implementation expects would be valid if context establishment were
   to succeed.

   The values of the GSS_C_PROT_READY_FLAG and GSS_C_TRANS_FLAG bits
   within ret_flags should indicate the actual state at the time
   gss_accept_sec_context returns, whether or not the context is fully
   established.

   Although this requires that GSS-API implementations set the
   GSS_C_PROT_READY_FLAG in the final ret_flags returned to a caller
   (i.e. when accompanied by a GSS_S_COMPLETE status code), applications
   should not rely on this behavior as the flag was not defined in
   Version 1 of the GSS-API. Instead, applications should be prepared to
   use per-message services after a successful context establishment,
   according to the GSS_C_INTEG_FLAG and GSS_C_CONF_FLAG values.

   All other bits within the ret_flags argument should be set to zero.
   While the routine returns GSS_S_CONTINUE_NEEDED, the values returned
   via the ret_flags argument indicate the services that the
   implementation expects to be available from the established context.

   If the initial call of gss_accept_sec_context() fails, the
   implementation should not create a context object, and should leave
   the value of the context_handle parameter set to GSS_C_NO_CONTEXT to
   indicate this.  In the event of a failure on a subsequent call, the
   implementation is permitted to delete the "half-built" security
   context (in which case it should set the context_handle parameter to
   GSS_C_NO_CONTEXT), but the preferred behavior is to leave the
   security context (and the context_handle parameter) untouched for the
   application to delete (using gss_delete_sec_context).

   During context establishment, the informational status bits
   GSS_S_OLD_TOKEN and GSS_S_DUPLICATE_TOKEN indicate fatal errors, and
   GSS-API mechanisms should always return them in association with a
   routine error of GSS_S_FAILURE.  This requirement for pairing did not
   exist in version 1 of the GSS-API specification, so applications that
   wish to run over version 1 implementations must special-case these
   codes.









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   Parameters:

   context_handle    gss_ctx_id_t, read/modify context handle for new
                        context.  Supply GSS_C_NO_CONTEXT for first
                        call; use value returned in subsequent calls.
                        Once gss_accept_sec_context() has returned a
                        value via this parameter, resources have been
                        assigned to the corresponding context, and must
                        be freed by the application after use with a
                        call to gss_delete_sec_context().


   acceptor_cred_handle  gss_cred_id_t, read Credential handle claimed
                         by context acceptor. Specify
                         GSS_C_NO_CREDENTIAL to accept the context as a
                         default principal.  If GSS_C_NO_CREDENTIAL is
                         specified, but no default acceptor principal is
                         defined, GSS_S_NO_CRED will be returned.

   input_token_buffer   buffer, opaque, read token obtained from remote
                        application.

   input_chan_bindings  channel bindings, read, optional Application-
                        specified bindings.  Allows application to
                        securely bind channel identification information
                        to the security context.  If channel bindings
                        are not used, specify GSS_C_NO_CHANNEL_BINDINGS.

   src_name             gss_name_t, modify, optional Authenticated name
                        of context initiator.  After use, this name
                        should be deallocated by passing it to
                        gss_release_name().  If not required, specify
                        NULL.

   mech_type            Object ID, modify, optional Security mechanism
                        used.  The returned OID value will be a pointer
                        into static storage, and should be treated as
                        read-only by the caller (in particular, it does
                        not need to be freed).  If not required, specify
                        NULL.

   output_token         buffer, opaque, modify Token to be passed to
                        peer application.  If the length field of the
                        returned token buffer is 0, then no token need
                        be passed to the peer application.  If a non-
                        zero length field is returned, the associated
                        storage must be freed after use by the
                        application with a call to gss_release_buffer().



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   ret_flags            bit-mask, modify, optional Contains various
                        independent flags, each of which indicates that
                        the context supports a specific service option.
                        If not needed, specify NULL.  Symbolic names are
                        provided for each flag, and the symbolic names
                        corresponding to the required flags should be
                        logically-ANDed with the ret_flags value to test
                        whether a given option is supported by the
                        context.  The flags are:
                        GSS_C_DELEG_FLAG
                        True - Delegated credentials are available
                               via the delegated_cred_handle
                               parameter
                        False - No credentials were delegated
                        GSS_C_MUTUAL_FLAG
                        True - Remote peer asked for mutual
                               authentication
                        False - Remote peer did not ask for mutual
                                authentication
                        GSS_C_REPLAY_FLAG
                        True - replay of protected messages
                               will be detected
                        False - replayed messages will not be
                                detected
                        GSS_C_SEQUENCE_FLAG
                        True - out-of-sequence protected
                               messages will be detected
                        False - out-of-sequence messages will not
                                be detected
                        GSS_C_CONF_FLAG
                        True - Confidentiality service may be
                               invoked by calling the gss_wrap
                               routine
                        False - No confidentiality service (via
                                gss_wrap) available. gss_wrap will
                                provide message encapsulation,
                                data-origin authentication and
                                integrity services only.
                        GSS_C_INTEG_FLAG
                        True - Integrity service may be invoked by
                               calling either gss_get_mic or
                               gss_wrap routines.
                        False - Per-message integrity service
                                unavailable.
                        GSS_C_ANON_FLAG
                        True - The initiator does not wish to
                               be authenticated; the src_name
                               parameter (if requested) contains



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                               an anonymous internal name.
                        False - The initiator has been
                                authenticated normally.
                        GSS_C_PROT_READY_FLAG
                        True - Protection services (as specified
                               by the states of the GSS_C_CONF_FLAG
                               and GSS_C_INTEG_FLAG) are available
                               if the accompanying major status
                               return value is either GSS_S_COMPLETE
                               or GSS_S_CONTINUE_NEEDED.
                        False - Protection services (as specified
                                by the states of the GSS_C_CONF_FLAG
                                and GSS_C_INTEG_FLAG) are available
                                only if the accompanying major status
                                return value is GSS_S_COMPLETE.
                        GSS_C_TRANS_FLAG
                        True - The resultant security context may
                               be transferred to other processes via
                               a call to gss_export_sec_context().
                        False - The security context is not
                                transferable.
                        All other bits should be set to zero.

   time_rec             Integer, modify, optional
                        number of seconds for which the context will
                        remain valid. Specify NULL if not required.

   delegated_cred_handle
                        gss_cred_id_t, modify, optional credential
                        handle for credentials received from context
                        initiator.  Only valid if deleg_flag in
                        ret_flags is true, in which case an explicit
                        credential handle (i.e. not GSS_C_NO_CREDENTIAL)
                        will be returned; if deleg_flag is false,
                        gss_accept_context() will set this parameter to
                        GSS_C_NO_CREDENTIAL.  If a credential handle is
                        returned, the associated resources must be
                        released by the application after use with a
                        call to gss_release_cred().  Specify NULL if not
                        required.

   minor_status         Integer, modify
                        Mechanism specific status code.

   GSS_S_CONTINUE_NEEDED Indicates that a token from the peer
                         application is required to complete the
                         context, and that gss_accept_sec_context must
                         be called again with that token.



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   GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed on
                         the input_token failed.

   GSS_S_DEFECTIVE_CREDENTIAL Indicates that consistency checks
                         performed on the credential failed.

   GSS_S_NO_CRED     The supplied credentials were not valid for context
                         acceptance, or the credential handle did not
                         reference any credentials.

   GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.

   GSS_S_BAD_BINDINGS  The input_token contains different channel
                         bindings to those specified via the
                         input_chan_bindings parameter.

   GSS_S_NO_CONTEXT  Indicates that the supplied context handle did not
                         refer to a valid context.

   GSS_S_BAD_SIG     The input_token contains an invalid MIC.

   GSS_S_OLD_TOKEN   The input_token was too old.  This is a fatal error
                         during context establishment.

   GSS_S_DUPLICATE_TOKEN The input_token is valid, but is a duplicate of
                         a token already processed.  This is a fatal
                         error during context establishment.

   GSS_S_BAD_MECH    The received token specified a mechanism that is
                         not supported by the implementation or the
                         provided credential.

<span class="h3"><a class="selflink" id="section-5.2" href="#section-5.2">5.2</a>. gss_acquire_cred</span>

   OM_uint32 gss_acquire_cred (
     OM_uint32         *minor_status,
     const gss_name_t  desired_name,
     OM_uint32         time_req,
     const gss_OID_set desired_mechs,
     gss_cred_usage_t  cred_usage,
     gss_cred_id_t     *output_cred_handle,
     gss_OID_set       *actual_mechs,
     OM_uint32         *time_rec)








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   Purpose:

   Allows an application to acquire a handle for a pre-existing
   credential by name.  GSS-API implementations must impose a local
   access-control policy on callers of this routine to prevent
   unauthorized callers from acquiring credentials to which they are not
   entitled.  This routine is not intended to provide a "login to the
   network" function, as such a function would involve the creation of
   new credentials rather than merely acquiring a handle to existing
   credentials.  Such functions, if required, should be defined in
   implementation-specific extensions to the API.

   If desired_name is GSS_C_NO_NAME, the call is interpreted as a
   request for a credential handle that will invoke default behavior
   when passed to gss_init_sec_context() (if cred_usage is
   GSS_C_INITIATE or GSS_C_BOTH) or gss_accept_sec_context() (if
   cred_usage is GSS_C_ACCEPT or GSS_C_BOTH).

   Mechanisms should honor the desired_mechs parameter, and return a
   credential that is suitable to use only with the requested
   mechanisms.  An exception to this is the case where one underlying
   credential element can be shared by multiple mechanisms; in this case
   it is permissible for an implementation to indicate all mechanisms
   with which the credential element may be used.  If desired_mechs is
   an empty set, behavior is undefined.

   This routine is expected to be used primarily by context acceptors,
   since implementations are likely to provide mechanism-specific ways
   of obtaining GSS-API initiator credentials from the system login
   process.  Some implementations may therefore not support the
   acquisition of GSS_C_INITIATE or GSS_C_BOTH credentials via
   gss_acquire_cred for any name other than GSS_C_NO_NAME, or a name
   produced by applying either gss_inquire_cred to a valid credential,
   or gss_inquire_context to an active context.

   If credential acquisition is time-consuming for a mechanism, the
   mechanism may choose to delay the actual acquisition until the
   credential is required (e.g. by gss_init_sec_context or
   gss_accept_sec_context).  Such mechanism-specific implementation
   decisions should be invisible to the calling application; thus a call
   of gss_inquire_cred immediately following the call of
   gss_acquire_cred must return valid credential data, and may therefore
   incur the overhead of a deferred credential acquisition.








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   Parameters:

   desired_name      gss_name_t, read
                     Name of principal whose credential
                     should be acquired

   time_req          Integer, read, optional
                     number of seconds that credentials
                     should remain valid. Specify GSS_C_INDEFINITE
                     to request that the credentials have the maximum
                     permitted lifetime.

   desired_mechs     Set of Object IDs, read, optional
                     set of underlying security mechanisms that
                     may be used.  GSS_C_NO_OID_SET may be used
                     to obtain an implementation-specific default.

   cred_usage        gss_cred_usage_t, read
                     GSS_C_BOTH - Credentials may be used
                        either to initiate or accept
                        security contexts.
                     GSS_C_INITIATE - Credentials will only be
                        used to initiate security contexts.
                     GSS_C_ACCEPT - Credentials will only be used to
                        accept security contexts.

   output_cred_handle  gss_cred_id_t, modify
                       The returned credential handle.  Resources
                       associated with this credential handle must
                       be released by the application after use
                       with a call to gss_release_cred().

   actual_mechs      Set of Object IDs, modify, optional
                     The set of mechanisms for which the
                     credential is valid.  Storage associated
                     with the returned OID-set must be released by
                     the application after use with a call to
                     gss_release_oid_set().  Specify NULL if not
                     required.

   time_rec          Integer, modify, optional
                     Actual number of seconds for which the
                     returned credentials will remain valid.  If the
                     implementation does not support expiration of
                     credentials, the value GSS_C_INDEFINITE will
                     be returned. Specify NULL if not required





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<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   minor_status      Integer, modify
                     Mechanism specific status code.

   Function value:  GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_MECH    Unavailable mechanism requested

   GSS_S_BAD_NAMETYPE Type contained within desired_name parameter
                      is not supported

   GSS_S_BAD_NAME    Value supplied for desired_name parameter is ill
                     formed.

   GSS_S_CREDENTIALS_EXPIRED The credentials could not be acquired
                             Because they have expired.

   GSS_S_NO_CRED     No credentials were found for the specified name.

<span class="h3"><a class="selflink" id="section-5.3" href="#section-5.3">5.3</a>. gss_add_cred</span>

   OM_uint32 gss_add_cred (
     OM_uint32           *minor_status,
     const gss_cred_id_t input_cred_handle,
     const gss_name_t    desired_name,
     const gss_OID       desired_mech,
     gss_cred_usage_t    cred_usage,
     OM_uint32           initiator_time_req,
     OM_uint32           acceptor_time_req,
     gss_cred_id_t       *output_cred_handle,
     gss_OID_set         *actual_mechs,
     OM_uint32           *initiator_time_rec,
     OM_uint32           *acceptor_time_rec)

   Purpose:

   Adds a credential-element to a credential.  The credential-element is
   identified by the name of the principal to which it refers.  GSS-API
   implementations must impose a local access-control policy on callers
   of this routine to prevent unauthorized callers from acquiring
   credential-elements to which they are not entitled. This routine is
   not intended to provide a "login to the network" function, as such a
   function would involve the creation of new mechanism-specific
   authentication data, rather than merely acquiring a GSS-API handle to
   existing data.  Such functions, if required, should be defined in
   implementation-specific extensions to the API.




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<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   If desired_name is GSS_C_NO_NAME, the call is interpreted as a
   request to add a credential element that will invoke default behavior
   when passed to gss_init_sec_context() (if cred_usage is
   GSS_C_INITIATE or GSS_C_BOTH) or gss_accept_sec_context() (if
   cred_usage is GSS_C_ACCEPT or GSS_C_BOTH).

   This routine is expected to be used primarily by context acceptors,
   since implementations are likely to provide mechanism-specific ways
   of obtaining GSS-API initiator credentials from the system login
   process.  Some implementations may therefore not support the
   acquisition of GSS_C_INITIATE or GSS_C_BOTH credentials via
   gss_acquire_cred for any name other than GSS_C_NO_NAME, or a name
   produced by applying either gss_inquire_cred to a valid credential,
   or gss_inquire_context to an active context.

   If credential acquisition is time-consuming for a mechanism, the
   mechanism may choose to delay the actual acquisition until the
   credential is required (e.g. by gss_init_sec_context or
   gss_accept_sec_context).  Such mechanism-specific implementation
   decisions should be invisible to the calling application; thus a call
   of gss_inquire_cred immediately following the call of gss_add_cred
   must return valid credential data, and may therefore incur the
   overhead of a deferred credential acquisition.

   This routine can be used to either compose a new credential
   containing all credential-elements of the original in addition to the
   newly-acquire credential-element, or to add the new credential-
   element to an existing credential. If NULL is specified for the
   output_cred_handle parameter argument, the new credential-element
   will be added to the credential identified by input_cred_handle; if a
   valid pointer is specified for the output_cred_handle parameter, a
   new credential handle will be created.

   If GSS_C_NO_CREDENTIAL is specified as the input_cred_handle,
   gss_add_cred will compose a credential (and set the
   output_cred_handle parameter accordingly) based on default behavior.
   That is, the call will have the same effect as if the application had
   first made a call to gss_acquire_cred(), specifying the same usage
   and passing GSS_C_NO_NAME as the desired_name parameter to obtain an
   explicit credential handle embodying default behavior, passed this
   credential handle to gss_add_cred(), and finally called
   gss_release_cred() on the first credential handle.

   If GSS_C_NO_CREDENTIAL is specified as the input_cred_handle
   parameter, a non-NULL output_cred_handle must be supplied.






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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-37" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   input_cred_handle gss_cred_id_t, read, optional
                     The credential to which a credential-element
                     will be added.  If GSS_C_NO_CREDENTIAL is
                     specified, the routine will compose the new
                     credential based on default behavior (see
                     description above).  Note that, while the
                     credential-handle is not modified by
                     gss_add_cred(), the underlying credential
                     will be modified if output_credential_handle
                     is NULL.

   desired_name      gss_name_t, read.
                     Name of principal whose credential
                     should be acquired.

   desired_mech      Object ID, read
                     Underlying security mechanism with which the
                     credential may be used.

   cred_usage        gss_cred_usage_t, read
                     GSS_C_BOTH - Credential may be used
                     either to initiate or accept
                     security contexts.
                     GSS_C_INITIATE - Credential will only be
                                      used to initiate security
                                      contexts.
                     GSS_C_ACCEPT - Credential will only be used to
                                    accept security contexts.

   initiator_time_req Integer, read, optional
                      number of seconds that the credential
                      should remain valid for initiating security
                      contexts.  This argument is ignored if the
                      composed credentials are of type GSS_C_ACCEPT.
                      Specify GSS_C_INDEFINITE to request that the
                      credentials have the maximum permitted
                      initiator lifetime.

   acceptor_time_req Integer, read, optional
                     number of seconds that the credential
                     should remain valid for accepting security
                     contexts.  This argument is ignored if the
                     composed credentials are of type GSS_C_INITIATE.



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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-38" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


                     Specify GSS_C_INDEFINITE to request that the
                     credentials have the maximum permitted initiator
                     lifetime.

   output_cred_handle gss_cred_id_t, modify, optional
                      The returned credential handle, containing
                      the new credential-element and all the
                      credential-elements from input_cred_handle.
                      If a valid pointer to a gss_cred_id_t is
                      supplied for this parameter, gss_add_cred
                      creates a new credential handle containing all
                      credential-elements from the input_cred_handle
                      and the newly acquired credential-element; if
                      NULL is specified for this parameter, the newly
                      acquired credential-element will be added
                      to the credential identified by input_cred_handle.

                      The resources associated with any credential
                      handle returned via this parameter must be
                      released by the application after use with a
                      call to gss_release_cred().

   actual_mechs      Set of Object IDs, modify, optional
                     The complete set of mechanisms for which
                     the new credential is valid.  Storage for
                     the returned OID-set must be freed by the
                     application after use with a call to
                     gss_release_oid_set(). Specify NULL if
                     not required.

   initiator_time_rec Integer, modify, optional
                      Actual number of seconds for which the
                      returned credentials will remain valid for
                      initiating contexts using the specified
                      mechanism.  If the implementation or mechanism
                      does not support expiration of credentials, the
                      value GSS_C_INDEFINITE will be returned. Specify
                      NULL if not required

   acceptor_time_rec Integer, modify, optional
                     Actual number of seconds for which the
                     returned credentials will remain valid for
                     accepting security contexts using the specified
                     mechanism.  If the implementation or mechanism
                     does not support expiration of credentials, the
                     value GSS_C_INDEFINITE will be returned. Specify
                     NULL if not required




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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-39" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_MECH    Unavailable mechanism requested

   GSS_S_BAD_NAMETYPE Type contained within desired_name parameter
                     is not supported

   GSS_S_BAD_NAME    Value supplied for desired_name parameter is
                     ill-formed.

   GSS_S_DUPLICATE_ELEMENT The credential already contains an element
                     for the requested mechanism with overlapping
                     usage and validity period.

   GSS_S_CREDENTIALS_EXPIRED The required credentials could not be
                     added because they have expired.

   GSS_S_NO_CRED     No credentials were found for the specified name.

<span class="h3"><a class="selflink" id="section-5.4" href="#section-5.4">5.4</a>. gss_add_oid_set_member</span>

   OM_uint32 gss_add_oid_set_member (
     OM_uint32       *minor_status,
     const gss_OID   member_oid,
     gss_OID_set     *oid_set)

   Purpose:

   Add an Object Identifier to an Object Identifier set.  This routine
   is intended for use in conjunction with gss_create_empty_oid_set when
   constructing a set of mechanism OIDs for input to gss_acquire_cred.
   The oid_set parameter must refer to an OID-set that was created by
   GSS-API (e.g. a set returned by gss_create_empty_oid_set()). GSS-API
   creates a copy of the member_oid and inserts this copy into the set,
   expanding the storage allocated to the OID-set's elements array if
   necessary.  The routine may add the new member OID anywhere within
   the elements array, and implementations should verify that the new
   member_oid is not already contained within the elements array; if the
   member_oid is already present, the oid_set should remain unchanged.

   Parameters:

      minor_status      Integer, modify
                        Mechanism specific status code





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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-40" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


      member_oid        Object ID, read
                        The object identifier to copied into
                        the set.

      oid_set           Set of Object ID, modify
                        The set in which the object identifier
                        should be inserted.

   Function value:   GSS status code

      GSS_S_COMPLETE    Successful completion

<span class="h3"><a class="selflink" id="section-5.5" href="#section-5.5">5.5</a>. gss_canonicalize_name</span>

   OM_uint32 gss_canonicalize_name (
     OM_uint32        *minor_status,
     const gss_name_t input_name,
     const gss_OID    mech_type,
     gss_name_t       *output_name)

   Purpose:

   Generate a canonical mechanism name (MN) from an arbitrary internal
   name.  The mechanism name is the name that would be returned to a
   context acceptor on successful authentication of a context where the
   initiator used the input_name in a successful call to
   gss_acquire_cred, specifying an OID set containing &lt;mech_type&gt; as its
   only member, followed by a call to gss_init_sec_context, specifying
   &lt;mech_type&gt; as the authentication mechanism.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   input_name        gss_name_t, read
                     The name for which a canonical form is
                     desired

   mech_type         Object ID, read
                     The authentication mechanism for which the
                     canonical form of the name is desired.  The
                     desired mechanism must be specified explicitly;
                     no default is provided.







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<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   output_name       gss_name_t, modify
                     The resultant canonical name.  Storage
                     associated with this name must be freed by
                     the application after use with a call to
                     gss_release_name().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion.

   GSS_S_BAD_MECH    The identified mechanism is not supported.

   GSS_S_BAD_NAMETYPE The provided internal name contains no elements
                     that could be processed by the specified
                     mechanism.

   GSS_S_BAD_NAME    The provided internal name was ill-formed.

<span class="h3"><a class="selflink" id="section-5.6" href="#section-5.6">5.6</a>. gss_compare_name</span>

   OM_uint32 gss_compare_name (
     OM_uint32        *minor_status,
     const gss_name_t name1,
     const gss_name_t name2,
     int              *name_equal)

   Purpose:

   Allows an application to compare two internal-form names to determine
   whether they refer to the same entity.

   If either name presented to gss_compare_name denotes an anonymous
   principal, the routines should indicate that the two names do not
   refer to the same identity.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   name1             gss_name_t, read
                     internal-form name

   name2             gss_name_t, read
                     internal-form name






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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-42" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   name_equal        boolean, modify
                     non-zero - names refer to same entity
                     zero - names refer to different entities
                           (strictly, the names are not known
                           to refer to the same identity).

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_NAMETYPE The two names were of incomparable types.

   GSS_S_BAD_NAME    One or both of name1 or name2 was ill-formed.

<span class="h3"><a class="selflink" id="section-5.7" href="#section-5.7">5.7</a>. gss_context_time</span>

   OM_uint32 gss_context_time (
     OM_uint32          *minor_status,
     const gss_ctx_id_t context_handle,
     OM_uint32          *time_rec)

   Purpose:

   Determines the number of seconds for which the specified context will
   remain valid.

   Parameters:

   minor_status      Integer, modify
                     Implementation specific status code.

   context_handle    gss_ctx_id_t, read
                     Identifies the context to be interrogated.

   time_rec          Integer, modify
                     Number of seconds that the context will remain
                     valid.  If the context has already expired,
                     zero will be returned.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_CONTEXT_EXPIRED The context has already expired

   GSS_S_NO_CONTEXT  The context_handle parameter did not identify
                     a valid context




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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-43" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


<span class="h3"><a class="selflink" id="section-5.8" href="#section-5.8">5.8</a>. gss_create_empty_oid_set</span>

   OM_uint32 gss_create_empty_oid_set (
     OM_uint32    *minor_status,
     gss_OID_set  *oid_set)

   Purpose:

   Create an object-identifier set containing no object identifiers, to
   which members may be subsequently added using the
   gss_add_oid_set_member() routine.  These routines are intended to be
   used to construct sets of mechanism object identifiers, for input to
   gss_acquire_cred.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   oid_set           Set of Object IDs, modify
                     The empty object identifier set.
                     The routine will allocate the
                     gss_OID_set_desc object, which the
                     application must free after use with
                     a call to gss_release_oid_set().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

<span class="h3"><a class="selflink" id="section-5.9" href="#section-5.9">5.9</a>. gss_delete_sec_context</span>

   OM_uint32 gss_delete_sec_context (
     OM_uint32    *minor_status,
     gss_ctx_id_t *context_handle,
     gss_buffer_t output_token)

   Purpose:

   Delete a security context.  gss_delete_sec_context will delete the
   local data structures associated with the specified security context,
   and may generate an output_token, which when passed to the peer
   gss_process_context_token will instruct it to do likewise.  If no
   token is required by the mechanism, the GSS-API should set the length
   field of the output_token (if provided) to zero.  No further security
   services may be obtained using the context specified by
   context_handle.




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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-44" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   In addition to deleting established security contexts,
   gss_delete_sec_context must also be able to delete "half-built"
   security contexts resulting from an incomplete sequence of
   gss_init_sec_context()/gss_accept_sec_context() calls.

   The output_token parameter is retained for compatibility with version
   1 of the GSS-API.  It is recommended that both peer applications
   invoke gss_delete_sec_context passing the value GSS_C_NO_BUFFER for
   the output_token parameter, indicating that no token is required, and
   that gss_delete_sec_context should simply delete local context data
   structures.  If the application does pass a valid buffer to
   gss_delete_sec_context, mechanisms are encouraged to return a zero-
   length token, indicating that no peer action is necessary, and that
   no token should be transferred by the application.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   context_handle    gss_ctx_id_t, modify
                     context handle identifying context to delete.
                     After deleting the context, the GSS-API will set
                     this context handle to GSS_C_NO_CONTEXT.

   output_token      buffer, opaque, modify, optional
                     token to be sent to remote application to
                     instruct it to also delete the context.  It
                     is recommended that applications specify
                     GSS_C_NO_BUFFER for this parameter, requesting
                     local deletion only.  If a buffer parameter is
                     provided by the application, the mechanism may
                     return a token in it;  mechanisms that implement
                     only local deletion should set the length field of
                     this token to zero to indicate to the application
                     that no token is to be sent to the peer.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_NO_CONTEXT  No valid context was supplied









<span class="grey">Wray                        Standards Track                    [Page 44]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-45" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


5.10.gss_display_name

   OM_uint32 gss_display_name (
     OM_uint32        *minor_status,
     const gss_name_t input_name,
     gss_buffer_t     output_name_buffer,
     gss_OID          *output_name_type)

   Purpose:

   Allows an application to obtain a textual representation of an opaque
   internal-form  name for display purposes.  The syntax of a printable
   name is defined by the GSS-API implementation.

   If input_name denotes an anonymous principal, the implementation
   should return the gss_OID value GSS_C_NT_ANONYMOUS as the
   output_name_type, and a textual name that is syntactically distinct
   from all valid supported printable names in output_name_buffer.

   If input_name was created by a call to gss_import_name, specifying
   GSS_C_NO_OID as the name-type, implementations that employ lazy
   conversion between name types may return GSS_C_NO_OID via the
   output_name_type parameter.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   input_name        gss_name_t, read
                     name to be displayed

   output_name_buffer  buffer, character-string, modify
                     buffer to receive textual name string.
                     The application must free storage associated
                     with this name after use with a call to
                     gss_release_buffer().

   output_name_type  Object ID, modify, optional
                     The type of the returned name.  The returned
                     gss_OID will be a pointer into static storage,
                     and should be treated as read-only by the caller
                     (in particular, the application should not attempt
                     to free it). Specify NULL if not required.







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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-46" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_NAME    input_name was ill-formed

5.11.gss_display_status

   OM_uint32 gss_display_status (
     OM_uint32      *minor_status,
     OM_uint32      status_value,
     int            status_type,
     const gss_OID  mech_type,
     OM_uint32      *message_context,
     gss_buffer_t   status_string)

   Purpose:

   Allows an application to obtain a textual representation of a GSS-API
   status code, for display to the user or for logging purposes.  Since
   some status values may indicate multiple conditions, applications may
   need to call gss_display_status multiple times, each call generating
   a single text string.  The message_context parameter is used by
   gss_display_status to store state information about which error
   messages have already been extracted from a given status_value;
   message_context must be initialized to 0 by the application prior to
   the first call, and gss_display_status will return a non-zero value
   in this parameter if there are further messages to extract.

   The message_context parameter contains all state information required
   by gss_display_status in order to extract further messages from the
   status_value;  even when a non-zero value is returned in this
   parameter, the application is not required to call gss_display_status
   again unless subsequent messages are desired.  The following code
   extracts all messages from a given status code and prints them to
   stderr:

   OM_uint32 message_context;
   OM_uint32 status_code;
   OM_uint32 maj_status;
   OM_uint32 min_status;
   gss_buffer_desc status_string;

          ...

   message_context = 0;

   do {



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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-47" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


     maj_status = gss_display_status (
                     &amp;min_status,
                     status_code,
                     GSS_C_GSS_CODE,
                     GSS_C_NO_OID,
                     &amp;message_context,
                     &amp;status_string)

     fprintf(stderr,
             "%.*s\n",
            (int)status_string.length,

            (char *)status_string.value);

     gss_release_buffer(&amp;min_status, &amp;status_string);

   } while (message_context != 0);


   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   status_value      Integer, read
                     Status value to be converted

   status_type       Integer, read
                     GSS_C_GSS_CODE - status_value is a GSS status
                     code

   GSS_C_MECH_CODE - status_value is a mechanism
                     status code

   mech_type         Object ID, read, optional
                     Underlying mechanism (used to interpret a
                     minor status value) Supply GSS_C_NO_OID to
                     obtain the system default.

   message_context   Integer, read/modify
                     Should be initialized to zero by the
                     application prior to the first call.
                     On return from gss_display_status(),
                     a non-zero status_value parameter indicates
                     that additional messages may be extracted
                     from the status code via subsequent calls





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<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-48" ></span>
<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


                     to gss_display_status(), passing the same
                     status_value, status_type, mech_type, and
                     message_context parameters.

   status_string     buffer, character string, modify
                     textual interpretation of the status_value.
                     Storage associated with this parameter must
                     be freed by the application after use with
                     a call to gss_release_buffer().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_MECH    Indicates that translation in accordance with
                     an unsupported mechanism type was requested

   GSS_S_BAD_STATUS  The status value was not recognized, or the
                     status type was neither GSS_C_GSS_CODE nor
                     GSS_C_MECH_CODE.

<span class="h3"><a class="selflink" id="section-5.12" href="#section-5.12">5.12</a>. gss_duplicate_name</span>

   OM_uint32 gss_duplicate_name (
     OM_uint32        *minor_status,
     const gss_name_t src_name,
     gss_name_t       *dest_name)

   Purpose:

   Create an exact duplicate of the existing internal name src_name.
   The new dest_name will be independent of src_name (i.e. src_name and
   dest_name must both be released, and the release of one shall not
   affect the validity of the other).

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   src_name          gss_name_t, read
                     internal name to be duplicated.

   dest_name         gss_name_t, modify
                     The resultant copy of &lt;src_name&gt;.
                     Storage associated with this name must
                     be freed by the application after use
                     with a call to gss_release_name().



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   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_NAME    The src_name parameter was ill-formed.

<span class="h3"><a class="selflink" id="section-5.13" href="#section-5.13">5.13</a>. gss_export_name</span>

   OM_uint32 gss_export_name (
     OM_uint32        *minor_status,
     const gss_name_t input_name,
     gss_buffer_t     exported_name)

   Purpose:

   To produce a canonical contiguous string representation of a
   mechanism name (MN), suitable for direct comparison (e.g. with
   memcmp) for use in authorization functions (e.g. matching entries in
   an access-control list).  The &lt;input_name&gt; parameter must specify a
   valid MN (i.e. an internal name generated by gss_accept_sec_context
   or by gss_canonicalize_name).

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   input_name        gss_name_t, read
                     The MN to be exported

   exported_name     gss_buffer_t, octet-string, modify
                     The canonical contiguous string form of
                     &lt;input_name&gt;.  Storage associated with
                     this string must freed by the application
                     after use with gss_release_buffer().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_NAME_NOT_MN The provided internal name was not a mechanism
                     name.

   GSS_S_BAD_NAME    The provided internal name was ill-formed.

   GSS_S_BAD_NAMETYPE The internal name was of a type not supported
                     by the GSS-API implementation.




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<span class="h3"><a class="selflink" id="section-5.14" href="#section-5.14">5.14</a>. gss_export_sec_context</span>

   OM_uint32 gss_export_sec_context (
     OM_uint32    *minor_status,
     gss_ctx_id_t *context_handle,
     gss_buffer_t interprocess_token)

   Purpose:

   Provided to support the sharing of work between multiple processes.
   This routine will typically be used by the context-acceptor, in an
   application where a single process receives incoming connection
   requests and accepts security contexts over them, then passes the
   established context to one or more other processes for message
   exchange. gss_export_sec_context() deactivates the security context
   for the calling process and creates an interprocess token which, when
   passed to gss_import_sec_context in another process, will re-activate
   the context in the second process. Only a single instantiation of a
   given context may be active at any one time; a subsequent attempt by
   a context exporter to access the exported security context will fail.

   The implementation may constrain the set of processes by which the
   interprocess token may be imported, either as a function of local
   security policy, or as a result of implementation decisions.  For
   example, some implementations may constrain contexts to be passed
   only between processes that run under the same account, or which are
   part of the same process group.

   The interprocess token may contain security-sensitive information
   (for example cryptographic keys).  While mechanisms are encouraged to
   either avoid placing such sensitive information within interprocess
   tokens, or to encrypt the token before returning it to the
   application, in a typical object-library GSS-API implementation this
   may not be possible. Thus the application must take care to protect
   the interprocess token, and ensure that any process to which the
   token is transferred is trustworthy.

   If creation of the interprocess token is successful, the
   implementation shall deallocate all process-wide resources associated
   with the security context, and set the context_handle to
   GSS_C_NO_CONTEXT.  In the event of an error that makes it impossible
   to complete the export of the security context, the implementation
   must not return an interprocess token, and should strive to leave the
   security context referenced by the context_handle parameter
   untouched.  If this is impossible, it is permissible for the
   implementation to delete the security context, providing it also sets
   the context_handle parameter to GSS_C_NO_CONTEXT.




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   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   context_handle    gss_ctx_id_t, modify
                     context handle identifying the context to
                     transfer.

   interprocess_token   buffer, opaque, modify
                        token to be transferred to target process.
                        Storage associated with this token must be
                        freed by the application after use with a
                        call to gss_release_buffer().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_CONTEXT_EXPIRED The context has expired

   GSS_S_NO_CONTEXT  The context was invalid

   GSS_S_UNAVAILABLE The operation is not supported.

<span class="h3"><a class="selflink" id="section-5.15" href="#section-5.15">5.15</a>. gss_get_mic</span>

   OM_uint32 gss_get_mic (
     OM_uint32          *minor_status,
     const gss_ctx_id_t context_handle,
     gss_qop_t             qop_req,
     const gss_buffer_t message_buffer,
     gss_buffer_t       msg_token)

   Purpose:

   Generates a cryptographic MIC for the supplied message, and places
   the MIC in a token for transfer to the peer application. The qop_req
   parameter allows a choice between several cryptographic algorithms,
   if supported by the chosen mechanism.

   Since some application-level protocols may wish to use tokens emitted
   by gss_wrap() to provide "secure framing", implementations must
   support derivation of MICs from zero-length messages.







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   Parameters:

   minor_status      Integer, modify
                     Implementation specific status code.

   context_handle    gss_ctx_id_t, read
                     identifies the context on which the message
                     will be sent

   qop_req           gss_qop_t, read, optional
                     Specifies requested quality of protection.
                     Callers are encouraged, on portability grounds,
                     to accept the default quality of protection
                     offered by the chosen mechanism, which may be
                     requested by specifying GSS_C_QOP_DEFAULT for
                     this parameter.  If an unsupported protection
                     strength is requested, gss_get_mic will return a
                     major_status of GSS_S_BAD_QOP.

   message_buffer    buffer, opaque, read
                     message to be protected

   msg_token         buffer, opaque, modify
                     buffer to receive token.  The application must
                     free storage associated with this buffer after
                     use with a call to gss_release_buffer().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_CONTEXT_EXPIRED The context has already expired

   GSS_S_NO_CONTEXT  The context_handle parameter did not identify
                     a valid context

   GSS_S_BAD_QOP     The specified QOP is not supported by the
                     mechanism.

<span class="h3"><a class="selflink" id="section-5.16" href="#section-5.16">5.16</a>. gss_import_name</span>

   OM_uint32 gss_import_name (
     OM_uint32          *minor_status,
     const gss_buffer_t input_name_buffer,
     const gss_OID      input_name_type,
     gss_name_t         *output_name)





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   Purpose:

   Convert a contiguous string name to internal form.  In general, the
   internal name returned (via the &lt;output_name&gt; parameter) will not be
   an MN; the exception to this is if the &lt;input_name_type&gt; indicates
   that the contiguous string provided via the &lt;input_name_buffer&gt;
   parameter is of type GSS_C_NT_EXPORT_NAME, in which case the returned
   internal name will be an MN for the mechanism that exported the name.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   input_name_buffer  buffer, octet-string, read
                     buffer containing contiguous string name to convert

   input_name_type   Object ID, read, optional
                     Object ID specifying type of printable
                     name.  Applications may specify either
                     GSS_C_NO_OID to use a mechanism-specific
                     default printable syntax, or an OID recognized
                     by the GSS-API implementation to name a
                     specific namespace.

   output_name       gss_name_t, modify
                     returned name in internal form.  Storage
                     associated with this name must be freed
                     by the application after use with a call
                     to gss_release_name().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_NAMETYPE The input_name_type was unrecognized

   GSS_S_BAD_NAME    The input_name parameter could not be interpreted
                     as a name of the specified type

   GSS_S_BAD_MECH    The input name-type was GSS_C_NT_EXPORT_NAME,
                     but the mechanism contained within the
                     input-name is not supported








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<span class="h3"><a class="selflink" id="section-5.17" href="#section-5.17">5.17</a>. gss_import_sec_context</span>

   OM_uint32 gss_import_sec_context (
     OM_uint32          *minor_status,
     const gss_buffer_t interprocess_token,
     gss_ctx_id_t       *context_handle)

   Purpose:

   Allows a process to import a security context established by another
   process.  A given interprocess token may be imported only once.  See
   gss_export_sec_context.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   interprocess_token  buffer, opaque, modify
                       token received from exporting process

   context_handle    gss_ctx_id_t, modify
                     context handle of newly reactivated context.
                     Resources associated with this context handle
                     must be released by the application after use
                     with a call to gss_delete_sec_context().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion.

   GSS_S_NO_CONTEXT  The token did not contain a valid context
   reference.

   GSS_S_DEFECTIVE_TOKEN The token was invalid.

   GSS_S_UNAVAILABLE The operation is unavailable.

   GSS_S_UNAUTHORIZED Local policy prevents the import of this context
                      by the current process.

<span class="h3"><a class="selflink" id="section-5.18" href="#section-5.18">5.18</a>. gss_indicate_mechs</span>

   OM_uint32 gss_indicate_mechs (
     OM_uint32   *minor_status,
     gss_OID_set *mech_set)





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   Purpose:

   Allows an application to determine which underlying security
   mechanisms are available.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   mech_set          set of Object IDs, modify
                     set of implementation-supported mechanisms.
                     The returned gss_OID_set value will be a
                     dynamically-allocated OID set, that should
                     be released by the caller after use with a
                     call to gss_release_oid_set().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

<span class="h3"><a class="selflink" id="section-5.19" href="#section-5.19">5.19</a>. gss_init_sec_context</span>

   OM_uint32 gss_init_sec_context (
     OM_uint32                    *minor_status,
     const gss_cred_id_t          initiator_cred_handle,
     gss_ctx_id_t                 *context_handle,\
     const gss_name_t             target_name,
     const gss_OID                mech_type,
     OM_uint32                    req_flags,
     OM_uint32                    time_req,
     const gss_channel_bindings_t input_chan_bindings,
     const gss_buffer_t           input_token
     gss_OID                      *actual_mech_type,
     gss_buffer_t                 output_token,
     OM_uint32                    *ret_flags,
     OM_uint32                    *time_rec )

   Purpose:

   Initiates the establishment of a security context between the
   application and a remote peer.  Initially, the input_token parameter
   should be specified either as GSS_C_NO_BUFFER, or as a pointer to a
   gss_buffer_desc object whose length field contains the value zero.
   The routine may return a output_token which should be transferred to
   the peer application, where the peer application will present it to
   gss_accept_sec_context.  If no token need be sent,
   gss_init_sec_context will indicate this by setting the length field



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   of the output_token argument to zero. To complete the context
   establishment, one or more reply tokens may be required from the peer
   application; if so, gss_init_sec_context will return a status
   containing the supplementary information bit GSS_S_CONTINUE_NEEDED.
   In this case, gss_init_sec_context should be called again when the
   reply token is received from the peer application, passing the reply
   token to gss_init_sec_context via the input_token parameters.

   Portable applications should be constructed to use the token length
   and return status to determine whether a token needs to be sent or
   waited for.  Thus a typical portable caller should always invoke
   gss_init_sec_context within a loop:

   int context_established = 0;
   gss_ctx_id_t context_hdl = GSS_C_NO_CONTEXT;
          ...
   input_token-&gt;length = 0;

   while (!context_established) {
     maj_stat = gss_init_sec_context(&amp;min_stat,
                                     cred_hdl,
                                     &amp;context_hdl,
                                     target_name,
                                     desired_mech,
                                     desired_services,
                                     desired_time,
                                     input_bindings,
                                     input_token,
                                     &amp;actual_mech,
                                     output_token,
                                     &amp;actual_services,
                                     &amp;actual_time);
     if (GSS_ERROR(maj_stat)) {
       report_error(maj_stat, min_stat);
     };

     if (output_token-&gt;length != 0) {
       send_token_to_peer(output_token);
       gss_release_buffer(&amp;min_stat, output_token)
     };
     if (GSS_ERROR(maj_stat)) {

       if (context_hdl != GSS_C_NO_CONTEXT)
         gss_delete_sec_context(&amp;min_stat,
                                &amp;context_hdl,
                                GSS_C_NO_BUFFER);
       break;
     };



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     if (maj_stat &amp; GSS_S_CONTINUE_NEEDED) {
       receive_token_from_peer(input_token);
     } else {
       context_established = 1;
     };
   };

   Whenever the routine returns a major status that includes the value
   GSS_S_CONTINUE_NEEDED, the context is not fully established and the
   following restrictions apply to the output parameters:

      The value returned via the time_rec parameter is undefined Unless
      the accompanying ret_flags parameter contains the bit
      GSS_C_PROT_READY_FLAG, indicating that per-message services may be
      applied in advance of a successful completion status, the value
      returned via the actual_mech_type parameter is undefined until the
      routine returns a major status value of GSS_S_COMPLETE.

      The values of the GSS_C_DELEG_FLAG, GSS_C_MUTUAL_FLAG,
      GSS_C_REPLAY_FLAG, GSS_C_SEQUENCE_FLAG, GSS_C_CONF_FLAG,
      GSS_C_INTEG_FLAG and GSS_C_ANON_FLAG bits returned via the
      ret_flags parameter should contain the values that the
      implementation expects would be valid if context establishment
      were to succeed.  In particular, if the application has requested
      a service such as delegation or anonymous authentication via the
      req_flags argument, and such a service is unavailable from the
      underlying mechanism, gss_init_sec_context should generate a token
      that will not provide the service, and indicate via the ret_flags
      argument that the service will not be supported.  The application
      may choose to abort the context establishment by calling
      gss_delete_sec_context (if it cannot continue in the absence of
      the service), or it may choose to transmit the token and continue
      context establishment (if the service was merely desired but not
      mandatory).

      The values of the GSS_C_PROT_READY_FLAG and GSS_C_TRANS_FLAG bits
      within ret_flags should indicate the actual state at the time
      gss_init_sec_context returns, whether or not the context is fully
      established.

      GSS-API implementations that support per-message protection are
      encouraged to set the GSS_C_PROT_READY_FLAG in the final ret_flags
      returned to a caller (i.e. when accompanied by a GSS_S_COMPLETE
      status code).  However, applications should not rely on this
      behavior as the flag was not defined in Version 1 of the GSS-API.
      Instead, applications should determine what per-message services
      are available after a successful context establishment according
      to the GSS_C_INTEG_FLAG and GSS_C_CONF_FLAG values.



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      All other bits within the ret_flags argument should be set to
      zero.

   If the initial call of gss_init_sec_context() fails, the
   implementation should not create a context object, and should leave
   the value of the context_handle parameter set to GSS_C_NO_CONTEXT to
   indicate this.  In the event of a failure on a subsequent call, the
   implementation is permitted to delete the "half-built" security
   context (in which case it should set the context_handle parameter to
   GSS_C_NO_CONTEXT), but the preferred behavior is to leave the
   security context untouched for the application to delete (using
   gss_delete_sec_context).

   During context establishment, the informational status bits
   GSS_S_OLD_TOKEN and GSS_S_DUPLICATE_TOKEN indicate fatal errors, and
   GSS-API mechanisms should always return them in association with a
   routine error of GSS_S_FAILURE.  This requirement for pairing did not
   exist in version 1 of the GSS-API specification, so applications that
   wish to run over version 1 implementations must special-case these
   codes.

   Parameters:

   minor_status      Integer,  modify
                     Mechanism specific status code.

   initiator_cred_handle  gss_cred_id_t, read, optional
                          handle for credentials claimed.  Supply
                          GSS_C_NO_CREDENTIAL to act as a default
                          initiator principal.  If no default
                          initiator is defined, the function will
                          return GSS_S_NO_CRED.

   context_handle    gss_ctx_id_t, read/modify
                     context handle for new context.  Supply
                     GSS_C_NO_CONTEXT for first call; use value
                     returned by first call in continuation calls.
                     Resources associated with this context-handle
                     must be released by the application after use
                     with a call to gss_delete_sec_context().

   target_name       gss_name_t, read
                     Name of target

   mech_type         OID, read, optional
                     Object ID of desired mechanism. Supply
                     GSS_C_NO_OID to obtain an implementation
                     specific default



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   req_flags         bit-mask, read
                     Contains various independent flags, each of
                     which requests that the context support a
                     specific service option.  Symbolic
                     names are provided for each flag, and the
                     symbolic names corresponding to the required
                     flags should be logically-ORed
                     together to form the bit-mask value.  The
                     flags are:

                     GSS_C_DELEG_FLAG
                       True - Delegate credentials to remote peer
                       False - Don't delegate

                     GSS_C_MUTUAL_FLAG
                       True - Request that remote peer
                              authenticate itself
                       False - Authenticate self to remote peer
                               only

                     GSS_C_REPLAY_FLAG
                       True - Enable replay detection for
                              messages protected with gss_wrap
                              or gss_get_mic
                       False - Don't attempt to detect
                               replayed messages

                     GSS_C_SEQUENCE_FLAG
                       True - Enable detection of out-of-sequence
                              protected messages
                       False - Don't attempt to detect
                               out-of-sequence messages

                     GSS_C_CONF_FLAG
                       True - Request that confidentiality service
                              be made available (via gss_wrap)
                       False - No per-message confidentiality service
                               is required.

                     GSS_C_INTEG_FLAG
                       True - Request that integrity service be
                              made available (via gss_wrap or
                              gss_get_mic)
                       False - No per-message integrity service
                               is required.






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                     GSS_C_ANON_FLAG
                       True - Do not reveal the initiator's
                              identity to the acceptor.
                       False - Authenticate normally.

   time_req          Integer, read, optional
                     Desired number of seconds for which context
                     should remain valid.  Supply 0 to request a
                     default validity period.

   input_chan_bindings  channel bindings, read, optional
                        Application-specified bindings.  Allows
                        application to securely bind channel
                        identification information to the security
                        context.  Specify GSS_C_NO_CHANNEL_BINDINGS
                        if channel bindings are not used.

   input_token       buffer, opaque, read, optional (see text)
                     Token received from peer application.
                     Supply GSS_C_NO_BUFFER, or a pointer to
                     a buffer containing the value GSS_C_EMPTY_BUFFER
                     on initial call.

   actual_mech_type  OID, modify, optional
                     Actual mechanism used.  The OID returned via
                     this parameter will be a pointer to static
                     storage that should be treated as read-only;
                     In particular the application should not attempt
                     to free it.  Specify NULL if not required.

   output_token      buffer, opaque, modify
                     token to be sent to peer application.  If
                     the length field of the returned buffer is
                     zero, no token need be sent to the peer
                     application.  Storage associated with this
                     buffer must be freed by the application
                     after use with a call to gss_release_buffer().

   ret_flags         bit-mask, modify, optional
                     Contains various independent flags, each of which
                     indicates that the context supports a specific
                     service option.  Specify NULL if not
                     required.  Symbolic names are provided
                     for each flag, and the symbolic names
                     corresponding to the required flags should be
                     logically-ANDed with the ret_flags value to test
                     whether a given option is supported by the
                     context.  The flags are:



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                     GSS_C_DELEG_FLAG
                       True - Credentials were delegated to
                              the remote peer
                       False - No credentials were delegated

                     GSS_C_MUTUAL_FLAG
                       True - The remote peer has authenticated
                              itself.
                       False - Remote peer has not authenticated
                               itself.

                     GSS_C_REPLAY_FLAG
                       True - replay of protected messages
                              will be detected
                       False - replayed messages will not be
                               detected

                     GSS_C_SEQUENCE_FLAG
                       True - out-of-sequence protected
                              messages will be detected
                       False - out-of-sequence messages will
                               not be detected

                     GSS_C_CONF_FLAG
                       True - Confidentiality service may be
                              invoked by calling gss_wrap routine
                       False - No confidentiality service (via
                               gss_wrap) available. gss_wrap will
                               provide message encapsulation,
                               data-origin authentication and
                               integrity services only.

                     GSS_C_INTEG_FLAG
                       True - Integrity service may be invoked by
                              calling either gss_get_mic or gss_wrap
                              routines.
                       False - Per-message integrity service
                               unavailable.

                     GSS_C_ANON_FLAG
                       True - The initiator's identity has not been
                              revealed, and will not be revealed if
                              any emitted token is passed to the
                              acceptor.
                       False - The initiator's identity has been or
                               will be authenticated normally.

                     GSS_C_PROT_READY_FLAG



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                       True - Protection services (as specified
                              by the states of the GSS_C_CONF_FLAG
                              and GSS_C_INTEG_FLAG) are available for
                              use if the accompanying major status
                              return value is either GSS_S_COMPLETE or
                              GSS_S_CONTINUE_NEEDED.
                       False - Protection services (as specified
                               by the states of the GSS_C_CONF_FLAG
                               and GSS_C_INTEG_FLAG) are available
                               only if the accompanying major status
                               return value is GSS_S_COMPLETE.

                     GSS_C_TRANS_FLAG
                       True - The resultant security context may
                              be transferred to other processes via
                              a call to gss_export_sec_context().
                       False - The security context is not
                               transferable.

                     All other bits should be set to zero.

   time_rec          Integer, modify, optional
                     number of seconds for which the context
                     will remain valid. If the implementation does
                     not support context expiration, the value
                     GSS_C_INDEFINITE will be returned.  Specify
                     NULL if not required.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_CONTINUE_NEEDED Indicates that a token from the peer
                         application is required to complete the
                         context, and that gss_init_sec_context
                         must be called again with that token.

   GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed
                         on the input_token failed

   GSS_S_DEFECTIVE_CREDENTIAL Indicates that consistency checks
                              performed on the credential failed.

   GSS_S_NO_CRED     The supplied credentials were not valid for
                     context initiation, or the credential handle
                     did not reference any credentials.

   GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired



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   GSS_S_BAD_BINDINGS The input_token contains different channel
                      bindings to those specified via the
                      input_chan_bindings parameter

   GSS_S_BAD_SIG     The input_token contains an invalid MIC, or a MIC
                     that could not be verified

   GSS_S_OLD_TOKEN   The input_token was too old.  This is a fatal
                     error during context establishment

   GSS_S_DUPLICATE_TOKEN The input_token is valid, but is a duplicate
                         of a token already processed.  This is a
                         fatal error during context establishment.

   GSS_S_NO_CONTEXT  Indicates that the supplied context handle did
                     not refer to a valid context

   GSS_S_BAD_NAMETYPE The provided target_name parameter contained an
                      invalid or unsupported type of name

   GSS_S_BAD_NAME    The provided target_name parameter was ill-formed.

   GSS_S_BAD_MECH    The specified mechanism is not supported by the
                     provided credential, or is unrecognized by the
                     implementation.

<span class="h3"><a class="selflink" id="section-5.20" href="#section-5.20">5.20</a>. gss_inquire_context</span>

   OM_uint32 gss_inquire_context (
     OM_uint32          *minor_status,
     const gss_ctx_id_t context_handle,
     gss_name_t         *src_name,
     gss_name_t         *targ_name,
     OM_uint32          *lifetime_rec,
     gss_OID            *mech_type,
     OM_uint32          *ctx_flags,
     int                *locally_initiated,
     int                *open )

   Purpose:

   Obtains information about a security context.  The caller must
   already have obtained a handle that refers to the context, although
   the context need not be fully established.







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   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   context_handle    gss_ctx_id_t, read
                     A handle that refers to the security context.

   src_name          gss_name_t, modify, optional
                     The name of the context initiator.
                     If the context was established using anonymous
                     authentication, and if the application invoking
                     gss_inquire_context is the context acceptor,
                     an anonymous name will be returned.  Storage
                     associated with this name must be freed by the
                     application after use with a call to
                     gss_release_name().  Specify NULL if not
                     required.

   targ_name         gss_name_t, modify, optional
                     The name of the context acceptor.
                     Storage associated with this name must be
                     freed by the application after use with a call
                     to gss_release_name().  If the context acceptor
                     did not authenticate itself, and if the initiator
                     did not specify a target name in its call to
                     gss_init_sec_context(), the value GSS_C_NO_NAME
                     will be returned.  Specify NULL if not required.

   lifetime_rec      Integer, modify, optional
                     The number of seconds for which the context
                     will remain valid.  If the context has
                     expired, this parameter will be set to zero.
                     If the implementation does not support
                     context expiration, the value
                     GSS_C_INDEFINITE will be returned.  Specify
                     NULL if not required.

   mech_type         gss_OID, modify, optional
                     The security mechanism providing the
                     context.  The returned OID will be a
                     pointer to static storage that should
                     be treated as read-only by the application;
                     in particular the application should not
                     attempt to free it.  Specify NULL if not
                     required.





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   ctx_flags         bit-mask, modify, optional
                     Contains various independent flags, each of
                     which indicates that the context supports
                     (or is expected to support, if ctx_open is
                     false) a specific service option.  If not
                     needed, specify NULL.  Symbolic names are
                     provided for each flag, and the symbolic names
                     corresponding to the required flags
                     should be logically-ANDed with the ret_flags
                     value to test whether a given option is
                     supported by the context.  The flags are:

                     GSS_C_DELEG_FLAG
                       True - Credentials were delegated from
                              the initiator to the acceptor.
                       False - No credentials were delegated

                     GSS_C_MUTUAL_FLAG
                       True - The acceptor was authenticated
                              to the initiator
                       False - The acceptor did not authenticate
                               itself.

                     GSS_C_REPLAY_FLAG
                       True - replay of protected messages
                              will be detected
                       False - replayed messages will not be
                               detected

                     GSS_C_SEQUENCE_FLAG
                       True - out-of-sequence protected
                              messages will be detected
                       False - out-of-sequence messages will not
                               be detected

                     GSS_C_CONF_FLAG
                       True - Confidentiality service may be invoked
                              by calling gss_wrap routine
                       False - No confidentiality service (via
                               gss_wrap) available. gss_wrap will
                               provide message encapsulation,
                               data-origin authentication and
                               integrity services only.

                     GSS_C_INTEG_FLAG
                       True - Integrity service may be invoked by
                              calling either gss_get_mic or gss_wrap
                              routines.



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                       False - Per-message integrity service
                               unavailable.

                     GSS_C_ANON_FLAG
                       True - The initiator's identity will not
                              be revealed to the acceptor.
                              The src_name parameter (if
                              requested) contains an anonymous
                              internal name.
                       False - The initiator has been
                               authenticated normally.

                     GSS_C_PROT_READY_FLAG
                       True - Protection services (as specified
                              by the states of the GSS_C_CONF_FLAG
                              and GSS_C_INTEG_FLAG) are available
                              for use.
                       False - Protection services (as specified
                               by the states of the GSS_C_CONF_FLAG
                               and GSS_C_INTEG_FLAG) are available
                               only if the context is fully
                               established (i.e. if the open parameter
                               is non-zero).

                     GSS_C_TRANS_FLAG
                       True - The resultant security context may
                              be transferred to other processes via
                              a call to gss_export_sec_context().
                       False - The security context is not
                               transferable.

   locally_initiated Boolean, modify
                     Non-zero if the invoking application is the
                     context initiator.
                     Specify NULL if not required.

   open              Boolean, modify
                     Non-zero if the context is fully established;
                     Zero if a context-establishment token
                     is expected from the peer application.
                     Specify NULL if not required.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_NO_CONTEXT  The referenced context could not be accessed.




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<span class="h3"><a class="selflink" id="section-5.21" href="#section-5.21">5.21</a>. gss_inquire_cred</span>

   OM_uint32 gss_inquire_cred (
     OM_uint32           *minor_status,
     const gss_cred_id_t cred_handle,
     gss_name_t          *name,
     OM_uint32           *lifetime,
     gss_cred_usage_t    *cred_usage,
     gss_OID_set         *mechanisms )

   Purpose:

   Obtains information about a credential.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   cred_handle       gss_cred_id_t, read
                     A handle that refers to the target credential.
                     Specify GSS_C_NO_CREDENTIAL to inquire about
                     the default initiator principal.

   name              gss_name_t, modify, optional
                     The name whose identity the credential asserts.
                     Storage associated with this name should be freed
                     by the application after use with a call to
                     gss_release_name().  Specify NULL if not required.

   lifetime          Integer, modify, optional
                     The number of seconds for which the credential
                     will remain valid.  If the credential has
                     expired, this parameter will be set to zero.
                     If the implementation does not support
                     credential expiration, the value
                     GSS_C_INDEFINITE will be returned.  Specify
                     NULL if not required.

   cred_usage        gss_cred_usage_t, modify, optional
                     How the credential may be used.  One of the
                     following:
                     GSS_C_INITIATE
                     GSS_C_ACCEPT
                     GSS_C_BOTH
                     Specify NULL if not required.





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   mechanisms        gss_OID_set, modify, optional
                     Set of mechanisms supported by the credential.
                     Storage associated with this OID set must be
                     freed by the application after use with a call
                     to gss_release_oid_set().  Specify NULL if not
                     required.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_NO_CRED     The referenced credentials could not be accessed.

   GSS_S_DEFECTIVE_CREDENTIAL The referenced credentials were invalid.

   GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.
                     If the lifetime parameter was not passed as NULL,
                     it will be set to 0.

<span class="h3"><a class="selflink" id="section-5.22" href="#section-5.22">5.22</a>. gss_inquire_cred_by_mech</span>

   OM_uint32 gss_inquire_cred_by_mech (
     OM_uint32           *minor_status,
     const gss_cred_id_t cred_handle,
     const gss_OID       mech_type,
     gss_name_t          *name,
     OM_uint32           *initiator_lifetime,
     OM_uint32           *acceptor_lifetime,
     gss_cred_usage_t    *cred_usage )

   Purpose:

   Obtains per-mechanism information about a credential.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   cred_handle       gss_cred_id_t, read
                     A handle that refers to the target credential.
                     Specify GSS_C_NO_CREDENTIAL to inquire about
                     the default initiator principal.

   mech_type         gss_OID, read
                     The mechanism for which information should be
                     returned.




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   name              gss_name_t, modify, optional
                     The name whose identity the credential asserts.
                     Storage associated with this name must be
                     freed by the application after use with a call
                     to gss_release_name().  Specify NULL if not
                     required.

   initiator_lifetime  Integer, modify, optional
                     The number of seconds for which the credential
                     will remain capable of initiating security contexts
                     under the specified mechanism.  If the credential
                     can no longer be used to initiate contexts, or if
                     the credential usage for this mechanism is
                     GSS_C_ACCEPT, this parameter will be set to zero.
                     If the implementation does not support expiration
                     of initiator credentials, the value
                     GSS_C_INDEFINITE will be returned.  Specify NULL
                     if not required.

   acceptor_lifetime Integer, modify, optional
                     The number of seconds for which the credential
                     will remain capable of accepting security contexts
                     under the specified mechanism.  If the credential
                     can no longer be used to accept contexts, or if
                     the credential usage for this mechanism is
                     GSS_C_INITIATE, this parameter will be set to zero.

                     If the implementation does not support expiration
                     of acceptor credentials, the value GSS_C_INDEFINITE
                     will be returned.  Specify NULL if not required.

   cred_usage        gss_cred_usage_t, modify, optional
                     How the credential may be used with the specified
                     mechanism.  One of the following:
                       GSS_C_INITIATE
                       GSS_C_ACCEPT
                       GSS_C_BOTH
                     Specify NULL if not required.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_NO_CRED     The referenced credentials could not be accessed.

   GSS_S_DEFECTIVE_CREDENTIAL The referenced credentials were invalid.





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   GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.
                    If the lifetime parameter was not passed as NULL,
                    it will be set to 0.

<span class="h3"><a class="selflink" id="section-5.23" href="#section-5.23">5.23</a>. gss_inquire_mechs_for_name</span>

   OM_uint32 gss_inquire_mechs_for_name (
     OM_uint32        *minor_status,
     const gss_name_t input_name,
     gss_OID_set      *mech_types )

   Purpose:

   Returns the set of mechanisms supported by the GSS-API implementation
   that may be able to process the specified name.

   Each mechanism returned will recognize at least one element within
   the name.  It is permissible for this routine to be implemented
   within a mechanism-independent GSS-API layer, using the type
   information contained within the presented name, and based on
   registration information provided by individual mechanism
   implementations.  This means that the returned mech_types set may
   indicate that a particular mechanism will understand the name when in
   fact it would refuse to accept the name as input to
   gss_canonicalize_name, gss_init_sec_context, gss_acquire_cred or
   gss_add_cred (due to some property of the specific name, as opposed
   to the name type).  Thus this routine should be used only as a pre-
   filter for a call to a subsequent mechanism-specific routine.

   Parameters:

   minor_status      Integer, modify
                     Implementation specific status code.

   input_name        gss_name_t, read
                     The name to which the inquiry relates.

   mech_types        gss_OID_set, modify
                     Set of mechanisms that may support the
                     specified name.  The returned OID set
                     must be freed by the caller after use
                     with a call to gss_release_oid_set().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_NAME    The input_name parameter was ill-formed.



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   GSS_S_BAD_NAMETYPE The input_name parameter contained an invalid or
                      unsupported type of name

<span class="h3"><a class="selflink" id="section-5.24" href="#section-5.24">5.24</a>. gss_inquire_names_for_mech</span>

   OM_uint32 gss_inquire_names_for_mech (
     OM_uint32     *minor_status,
     const gss_OID mechanism,
     gss_OID_set   *name_types)

   Purpose:

   Returns the set of nametypes supported by the specified mechanism.

   Parameters:

   minor_status      Integer, modify
                     Implementation specific status code.

   mechanism         gss_OID, read
                     The mechanism to be interrogated.

   name_types        gss_OID_set, modify
                     Set of name-types supported by the specified
                     mechanism.  The returned OID set must be
                     freed by the application after use with a
                     call to gss_release_oid_set().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

<span class="h3"><a class="selflink" id="section-5.25" href="#section-5.25">5.25</a>. gss_process_context_token</span>

   OM_uint32 gss_process_context_token (
     OM_uint32          *minor_status,
     const gss_ctx_id_t context_handle,
     const gss_buffer_t token_buffer)

        Purpose:

   Provides a way to pass an asynchronous token to the security service.
   Most context-level tokens are emitted and processed synchronously by
   gss_init_sec_context and gss_accept_sec_context, and the application
   is informed as to whether further tokens are expected by the
   GSS_C_CONTINUE_NEEDED major status bit.  Occasionally, a mechanism
   may need to emit a context-level token at a point when the peer
   entity is not expecting a token.  For example, the initiator's final



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   call to gss_init_sec_context may emit a token and return a status of
   GSS_S_COMPLETE, but the acceptor's call to gss_accept_sec_context may
   fail.  The acceptor's mechanism may wish to send a token containing
   an error indication to the initiator, but the initiator is not
   expecting a token at this point, believing that the context is fully
   established.  Gss_process_context_token provides a way to pass such a
   token to the mechanism at any time.

   Parameters:

   minor_status      Integer, modify
                     Implementation specific status code.

   context_handle    gss_ctx_id_t, read
                     context handle of context on which token is to
                     be processed

   token_buffer      buffer, opaque, read
                     token to process

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed
                     on the token failed

   GSS_S_NO_CONTEXT  The context_handle did not refer to a valid context

<span class="h3"><a class="selflink" id="section-5.26" href="#section-5.26">5.26</a>. gss_release_buffer</span>

   OM_uint32 gss_release_buffer (
     OM_uint32    *minor_status,
     gss_buffer_t buffer)

   Purpose:

   Free storage associated with a buffer.  The storage must have been
   allocated by a GSS-API routine.  In addition to freeing the
   associated storage, the routine will zero the length field in the
   descriptor to which the buffer parameter refers, and implementations
   are encouraged to additionally set the pointer field in the
   descriptor to NULL.  Any buffer object returned by a GSS-API routine
   may be passed to gss_release_buffer (even if there is no storage
   associated with the buffer).






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   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   buffer            buffer, modify
                     The storage associated with the buffer will be
                     deleted.  The gss_buffer_desc object will not
                     be freed, but its length field will be zeroed.


   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

<span class="h3"><a class="selflink" id="section-5.27" href="#section-5.27">5.27</a>. gss_release_cred</span>

   OM_uint32 gss_release_cred (
     OM_uint32     *minor_status,
     gss_cred_id_t *cred_handle)

   Purpose:

   Informs GSS-API that the specified credential handle is no longer
   required by the application, and frees associated resources.
   Implementations are encouraged to set the cred_handle to
   GSS_C_NO_CREDENTIAL on successful completion of this call.

   Parameters:

   cred_handle       gss_cred_id_t, modify, optional
                     Opaque handle identifying credential
                     to be released.  If GSS_C_NO_CREDENTIAL
                     is supplied, the routine will complete
                     successfully, but will do nothing.

   minor_status      Integer, modify
                     Mechanism specific status code.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_NO_CRED     Credentials could not be accessed.







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<span class="h3"><a class="selflink" id="section-5.28" href="#section-5.28">5.28</a>. gss_release_name</span>

   OM_uint32 gss_release_name (
     OM_uint32  *minor_status,
     gss_name_t *name)

   Purpose:

   Free GSSAPI-allocated storage associated with an internal-form name.
   Implementations are encouraged to set the name to GSS_C_NO_NAME on
   successful completion of this call.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   name              gss_name_t, modify
                     The name to be deleted

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_BAD_NAME    The name parameter did not contain a valid name

<span class="h3"><a class="selflink" id="section-5.29" href="#section-5.29">5.29</a>. gss_release_oid_set</span>

   OM_uint32 gss_release_oid_set (
     OM_uint32   *minor_status,
     gss_OID_set *set)

   Purpose:

   Free storage associated with a GSSAPI-generated gss_OID_set object.
   The set parameter must refer to an OID-set that was returned from a
   GSS-API routine.  gss_release_oid_set() will free the storage
   associated with each individual member OID, the OID set's elements
   array, and the gss_OID_set_desc.

   Implementations are encouraged to set the gss_OID_set parameter to
   GSS_C_NO_OID_SET on successful completion of this routine.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code




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   set               Set of Object IDs, modify
                     The storage associated with the gss_OID_set
                     will be deleted.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

<span class="h3"><a class="selflink" id="section-5.30" href="#section-5.30">5.30</a>. gss_test_oid_set_member</span>

   OM_uint32 gss_test_oid_set_member (
     OM_uint32         *minor_status,
     const gss_OID     member,
     const gss_OID_set set,
     int               *present)

   Purpose:

   Interrogate an Object Identifier set to determine whether a specified
   Object Identifier is a member.  This routine is intended to be used
   with OID sets returned by gss_indicate_mechs(), gss_acquire_cred(),
   and gss_inquire_cred(), but will also work with user-generated sets.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   member            Object ID, read
                     The object identifier whose presence
                     is to be tested.

   set               Set of Object ID, read
                     The Object Identifier set.

   present           Boolean, modify
                     non-zero if the specified OID is a member
                     of the set, zero if not.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion









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<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


<span class="h3"><a class="selflink" id="section-5.31" href="#section-5.31">5.31</a>. gss_unwrap</span>

   OM_uint32 gss_unwrap (
     OM_uint32          *minor_status,
     const gss_ctx_id_t context_handle,
     const gss_buffer_t input_message_buffer,
     gss_buffer_t       output_message_buffer,
     int                *conf_state,
     gss_qop_t          *qop_state)

   Purpose:

   Converts a message previously protected by gss_wrap back to a usable
   form, verifying the embedded MIC.  The conf_state parameter indicates
   whether the message was encrypted; the qop_state parameter indicates
   the strength of protection that was used to provide the
   confidentiality and integrity services.

   Since some application-level protocols may wish to use tokens emitted
   by gss_wrap() to provide "secure framing", implementations must
   support the wrapping and unwrapping of zero-length messages.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   context_handle    gss_ctx_id_t, read
                     Identifies the context on which the message
                     arrived

   input_message_buffer  buffer, opaque, read
                     protected message

   output_message_buffer  buffer, opaque, modify
                     Buffer to receive unwrapped message.
                     Storage associated with this buffer must
                     be freed by the application after use use
                     with a call to gss_release_buffer().

   conf_state        boolean, modify, optional
                     Non-zero - Confidentiality and integrity
                                protection were used
                     Zero - Integrity service only was used
                     Specify NULL if not required






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   qop_state         gss_qop_t, modify, optional
                     Quality of protection provided.
                     Specify NULL if not required

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_DEFECTIVE_TOKEN The token failed consistency checks

   GSS_S_BAD_SIG     The MIC was incorrect

   GSS_S_DUPLICATE_TOKEN The token was valid, and contained a correct
                         MIC for the message, but it had already been
                         processed

   GSS_S_OLD_TOKEN   The token was valid, and contained a correct MIC
                     for the message, but it is too old to check for
                     duplication.

   GSS_S_UNSEQ_TOKEN The token was valid, and contained a correct MIC
                     for the message, but has been verified out of
                     sequence; a later token has already been
                     received.

   GSS_S_GAP_TOKEN   The token was valid, and contained a correct MIC
                     for the message, but has been verified out of
                     sequence; an earlier expected token has not yet
                     been received.

   GSS_S_CONTEXT_EXPIRED The context has already expired

   GSS_S_NO_CONTEXT  The context_handle parameter did not identify
                     a valid context

<span class="h3"><a class="selflink" id="section-5.32" href="#section-5.32">5.32</a>. gss_verify_mic</span>

   OM_uint32 gss_verify_mic (
     OM_uint32          *minor_status,
     const gss_ctx_id_t context_handle,
     const gss_buffer_t message_buffer,
     const gss_buffer_t token_buffer,
     gss_qop_t          *qop_state)








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   Purpose:

   Verifies that a cryptographic MIC, contained in the token parameter,
   fits the supplied message.  The qop_state parameter allows a message
   recipient to determine the strength of protection that was applied to
   the message.

   Since some application-level protocols may wish to use tokens emitted
   by gss_wrap() to provide "secure framing", implementations must
   support the calculation and verification of MICs over zero-length
   messages.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   context_handle    gss_ctx_id_t, read
                     Identifies the context on which the message
                     arrived

   message_buffer    buffer, opaque, read
                     Message to be verified

   token_buffer      buffer, opaque, read
                     Token associated with message

   qop_state         gss_qop_t, modify, optional
                     quality of protection gained from MIC
                     Specify NULL if not required

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_DEFECTIVE_TOKEN The token failed consistency checks

   GSS_S_BAD_SIG     The MIC was incorrect

   GSS_S_DUPLICATE_TOKEN The token was valid, and contained a correct
                     MIC for the message, but it had already been
                     processed

   GSS_S_OLD_TOKEN   The token was valid, and contained a correct MIC
                     for the message, but it is too old to check for
                     duplication.





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   GSS_S_UNSEQ_TOKEN The token was valid, and contained a correct MIC
                     for the message, but has been verified out of
                     sequence; a later token has already been received.

   GSS_S_GAP_TOKEN   The token was valid, and contained a correct MIC
                     for the message, but has been verified out of
                     sequence; an earlier expected token has not yet
                     been received.

   GSS_S_CONTEXT_EXPIRED The context has already expired

   GSS_S_NO_CONTEXT  The context_handle parameter did not identify a
                     valid context

<span class="h3"><a class="selflink" id="section-5.33" href="#section-5.33">5.33</a>. gss_wrap</span>

   OM_uint32 gss_wrap (
     OM_uint32          *minor_status,
     const gss_ctx_id_t context_handle,
     int               conf_req_flag,
     gss_qop_t          qop_req
     const gss_buffer_t input_message_buffer,
     int                *conf_state,
     gss_buffer_t       output_message_buffer )

   Purpose:

   Attaches a cryptographic MIC and optionally encrypts the specified
   input_message.  The output_message contains both the MIC and the
   message.  The qop_req parameter allows a choice between several
   cryptographic algorithms, if supported by the chosen mechanism.

   Since some application-level protocols may wish to use tokens emitted
   by gss_wrap() to provide "secure framing", implementations must
   support the wrapping of zero-length messages.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code.

   context_handle    gss_ctx_id_t, read
                     Identifies the context on which the message
                     will be sent







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   conf_req_flag     boolean, read
                     Non-zero - Both confidentiality and integrity
                                services are requested
                     Zero - Only integrity service is requested

   qop_req           gss_qop_t, read, optional
                     Specifies required quality of protection.  A
                     mechanism-specific default may be requested by
                     setting qop_req to GSS_C_QOP_DEFAULT.  If an
                     unsupported protection strength is requested,
                     gss_wrap will return a major_status of
                     GSS_S_BAD_QOP.

   input_message_buffer  buffer, opaque, read
                     Message to be protected

   conf_state        boolean, modify, optional
                     Non-zero - Confidentiality, data origin
                                authentication and integrity
                                services have been applied
                     Zero - Integrity and data origin services only
                            has been applied.
                     Specify NULL if not required

   output_message_buffer  buffer, opaque, modify
                     Buffer to receive protected message.
                     Storage associated with this message must
                     be freed by the application after use with
                     a call to gss_release_buffer().

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_CONTEXT_EXPIRED The context has already expired

   GSS_S_NO_CONTEXT  The context_handle parameter did not identify a
                     valid context

   GSS_S_BAD_QOP     The specified QOP is not supported by the
                     mechanism.










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<span class="h3"><a class="selflink" id="section-5.34" href="#section-5.34">5.34</a>. gss_wrap_size_limit</span>

   OM_uint32 gss_wrap_size_limit (
     OM_uint32          *minor_status,
     const gss_ctx_id_t context_handle,
     int                conf_req_flag,
     gss_qop_t          qop_req,
     OM_uint32          req_output_size,
     OM_uint32          *max_input_size)

   Purpose:

   Allows an application to determine the maximum message size that, if
   presented to gss_wrap with the same conf_req_flag and qop_req
   parameters, will result in an output token containing no more than
   req_output_size bytes.

   This call is intended for use by applications that communicate over
   protocols that impose a maximum message size.  It enables the
   application to fragment messages prior to applying protection.

   GSS-API implementations are recommended but not required to detect
   invalid QOP values when gss_wrap_size_limit() is called. This routine
   guarantees only a maximum message size, not the availability of
   specific QOP values for message protection.

   Successful completion of this call does not guarantee that gss_wrap
   will be able to protect a message of length max_input_size bytes,
   since this ability may depend on the availability of system resources
   at the time that gss_wrap is called.  However, if the implementation
   itself imposes an upper limit on the length of messages that may be
   processed by gss_wrap, the implementation should not return a value
   via max_input_bytes that is greater than this length.

   Parameters:

   minor_status      Integer, modify
                     Mechanism specific status code

   context_handle    gss_ctx_id_t, read
                     A handle that refers to the security over
                     which the messages will be sent.

   conf_req_flag     Boolean, read
                     Indicates whether gss_wrap will be asked
                     to apply confidentiality protection in





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                     addition to integrity protection.  See
                     the routine description for gss_wrap
                     for more details.

   qop_req           gss_qop_t, read
                     Indicates the level of protection that
                     gss_wrap will be asked to provide.  See
                     the routine description for gss_wrap for
                     more details.

   req_output_size   Integer, read
                     The desired maximum size for tokens emitted
                     by gss_wrap.

   max_input_size    Integer, modify
                     The maximum input message size that may
                     be presented to gss_wrap in order to
                     guarantee that the emitted token shall
                     be no larger than req_output_size bytes.

   Function value:   GSS status code

   GSS_S_COMPLETE    Successful completion

   GSS_S_NO_CONTEXT  The referenced context could not be accessed.

   GSS_S_CONTEXT_EXPIRED The context has expired.

   GSS_S_BAD_QOP     The specified QOP is not supported by the
                     mechanism.

<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>.   Security Considerations</span>

   This document specifies a service interface for security facilities
   and services; as such, security considerations appear throughout the
   specification. Nonetheless, it is appropriate to summarize certain
   specific points relevant to GSS-API implementors and calling
   applications. Usage of the GSS-API interface does not in itself
   provide security services or assurance; instead, these attributes are
   dependent on the underlying mechanism(s) which support a GSS-API
   implementation. Callers must be attentive to the requests made to
   GSS-API calls and to the status indicators returned by GSS-API, as
   these specify the security service characteristics which GSS-API will
   provide. When the interprocess context transfer facility is used,
   appropriate local controls should be applied to constrain access to
   interprocess tokens and to the sensitive data which they contain.





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<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


   <a href="#appendix-A">Appendix A</a>. GSS-API C header file gssapi.h

   C-language GSS-API implementations should include a copy of the
   following header-file.

   #ifndef GSSAPI_H_
   #define GSSAPI_H_



   /*
    * First, include stddef.h to get size_t defined.
    */
   #include &lt;stddef.h&gt;

   /*
    * If the platform supports the xom.h header file, it should be
    * included here.
    */
   #include &lt;xom.h&gt;


   /*
    * Now define the three implementation-dependent types.
    */
   typedef &lt;platform-specific&gt; gss_ctx_id_t;
   typedef &lt;platform-specific&gt; gss_cred_id_t;
   typedef &lt;platform-specific&gt; gss_name_t;

   /*
    * The following type must be defined as the smallest natural
    * unsigned integer supported by the platform that has at least
    * 32 bits of precision.
    */
   typedef &lt;platform-specific&gt; gss_uint32;


   #ifdef OM_STRING
   /*
    * We have included the xom.h header file.  Verify that OM_uint32
    * is defined correctly.
    */

   #if sizeof(gss_uint32) != sizeof(OM_uint32)
   #error Incompatible definition of OM_uint32 from xom.h
   #endif

   typedef OM_object_identifier gss_OID_desc, *gss_OID;



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   #else

   /*
    * We can't use X/Open definitions, so roll our own.
    */

   typedef gss_uint32 OM_uint32;

   typedef struct gss_OID_desc_struct {
     OM_uint32 length;
     void      *elements;
   } gss_OID_desc, *gss_OID;

   #endif

   typedef struct gss_OID_set_desc_struct  {
     size_t     count;
     gss_OID    elements;
   } gss_OID_set_desc, *gss_OID_set;

   typedef struct gss_buffer_desc_struct {
     size_t length;
     void *value;
   } gss_buffer_desc, *gss_buffer_t;

   typedef struct gss_channel_bindings_struct {
     OM_uint32 initiator_addrtype;
     gss_buffer_desc initiator_address;
     OM_uint32 acceptor_addrtype;
     gss_buffer_desc acceptor_address;
     gss_buffer_desc application_data;
   } *gss_channel_bindings_t;

   /*
    * For now, define a QOP-type as an OM_uint32
    */
   typedef OM_uint32 gss_qop_t;

   typedef int gss_cred_usage_t;

   /*
    * Flag bits for context-level services.
    */








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   #define GSS_C_DELEG_FLAG      1
   #define GSS_C_MUTUAL_FLAG     2
   #define GSS_C_REPLAY_FLAG     4
   #define GSS_C_SEQUENCE_FLAG   8
   #define GSS_C_CONF_FLAG       16
   #define GSS_C_INTEG_FLAG      32
   #define GSS_C_ANON_FLAG       64
   #define GSS_C_PROT_READY_FLAG 128
   #define GSS_C_TRANS_FLAG      256

   /*
    * Credential usage options
    */
   #define GSS_C_BOTH     0
   #define GSS_C_INITIATE 1
   #define GSS_C_ACCEPT   2

   /*
    * Status code types for gss_display_status
    */
   #define GSS_C_GSS_CODE  1
   #define GSS_C_MECH_CODE 2

   /*
    * The constant definitions for channel-bindings address families
    */
   #define GSS_C_AF_UNSPEC     0
   #define GSS_C_AF_LOCAL      1
   #define GSS_C_AF_INET       2
   #define GSS_C_AF_IMPLINK    3
   #define GSS_C_AF_PUP        4
   #define GSS_C_AF_CHAOS      5
   #define GSS_C_AF_NS         6
   #define GSS_C_AF_NBS        7
   #define GSS_C_AF_ECMA       8
   #define GSS_C_AF_DATAKIT    9
   #define GSS_C_AF_CCITT      10
   #define GSS_C_AF_SNA        11
   #define GSS_C_AF_DECnet     12
   #define GSS_C_AF_DLI        13
   #define GSS_C_AF_LAT        14
   #define GSS_C_AF_HYLINK     15
   #define GSS_C_AF_APPLETALK  16
   #define GSS_C_AF_BSC        17
   #define GSS_C_AF_DSS        18
   #define GSS_C_AF_OSI        19
   #define GSS_C_AF_X25        21




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   #define GSS_C_AF_NULLADDR   255

   /*
    * Various Null values
    */
   #define GSS_C_NO_NAME ((gss_name_t) 0)
   #define GSS_C_NO_BUFFER ((gss_buffer_t) 0)
   #define GSS_C_NO_OID ((gss_OID) 0)
   #define GSS_C_NO_OID_SET ((gss_OID_set) 0)
   #define GSS_C_NO_CONTEXT ((gss_ctx_id_t) 0)
   #define GSS_C_NO_CREDENTIAL ((gss_cred_id_t) 0)
   #define GSS_C_NO_CHANNEL_BINDINGS ((gss_channel_bindings_t) 0)
   #define GSS_C_EMPTY_BUFFER {0, NULL}

   /*
    * Some alternate names for a couple of the above
    * values.  These are defined for V1 compatibility.
    */
   #define GSS_C_NULL_OID GSS_C_NO_OID
   #define GSS_C_NULL_OID_SET GSS_C_NO_OID_SET

   /*
    * Define the default Quality of Protection for per-message
    * services.  Note that an implementation that offers multiple
    * levels of QOP may define GSS_C_QOP_DEFAULT to be either zero
    * (as done here) to mean "default protection", or to a specific
    * explicit QOP value.  However, a value of 0 should always be
    * interpreted by a GSS-API implementation as a request for the
    * default protection level.
    */
   #define GSS_C_QOP_DEFAULT 0

   /*
    * Expiration time of 2^32-1 seconds means infinite lifetime for a
    * credential or security context
    */
   #define GSS_C_INDEFINITE 0xfffffffful

   /*
    * The implementation must reserve static storage for a
    * gss_OID_desc object containing the value
    * {10, (void *)"\x2a\x86\x48\x86\xf7\x12"
    * "\x01\x02\x01\x01"},
    * corresponding to an object-identifier value of
    * {iso(1) member-body(2) United States(840) mit(113554)
    * infosys(1) gssapi(2) generic(1) user_name(1)}.  The constant
    * GSS_C_NT_USER_NAME should be initialized to point
    * to that gss_OID_desc.



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    */
   extern gss_OID GSS_C_NT_USER_NAME;

   /*
    * The implementation must reserve static storage for a
    * gss_OID_desc object containing the value
    * {10, (void *)"\x2a\x86\x48\x86\xf7\x12"
    *              "\x01\x02\x01\x02"},
    * corresponding to an object-identifier value of
    * {iso(1) member-body(2) United States(840) mit(113554)
    * infosys(1) gssapi(2) generic(1) machine_uid_name(2)}.
    * The constant GSS_C_NT_MACHINE_UID_NAME should be
    * initialized to point to that gss_OID_desc.
    */
   extern gss_OID GSS_C_NT_MACHINE_UID_NAME;

   /*
    * The implementation must reserve static storage for a
    * gss_OID_desc object containing the value
    * {10, (void *)"\x2a\x86\x48\x86\xf7\x12"
    *              "\x01\x02\x01\x03"},
    * corresponding to an object-identifier value of
    * {iso(1) member-body(2) United States(840) mit(113554)
    * infosys(1) gssapi(2) generic(1) string_uid_name(3)}.
    * The constant GSS_C_NT_STRING_UID_NAME should be
    * initialized to point to that gss_OID_desc.
    */
   extern gss_OID GSS_C_NT_STRING_UID_NAME;

   /*
    * The implementation must reserve static storage for a
    * gss_OID_desc object containing the value
    * {6, (void *)"\x2b\x06\x01\x05\x06\x02"},
    * corresponding to an object-identifier value of
    * {iso(1) org(3) dod(6) internet(1) security(5)
    * nametypes(6) gss-host-based-services(2)).  The constant
    * GSS_C_NT_HOSTBASED_SERVICE_X should be initialized to point
    * to that gss_OID_desc.  This is a deprecated OID value, and
    * implementations wishing to support hostbased-service names
    * should instead use the GSS_C_NT_HOSTBASED_SERVICE OID,
    * defined below, to identify such names;
    * GSS_C_NT_HOSTBASED_SERVICE_X should be accepted a synonym
    * for GSS_C_NT_HOSTBASED_SERVICE when presented as an input
    * parameter, but should not be emitted by GSS-API
    * implementations
    */
   extern gss_OID GSS_C_NT_HOSTBASED_SERVICE_X;




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   /*
    * The implementation must reserve static storage for a
    * gss_OID_desc object containing the value
    * {10, (void *)"\x2a\x86\x48\x86\xf7\x12"
    *              "\x01\x02\x01\x04"}, corresponding to an
    * object-identifier value of {iso(1) member-body(2)
    * Unites States(840) mit(113554) infosys(1) gssapi(2)
    * generic(1) service_name(4)}.  The constant
    * GSS_C_NT_HOSTBASED_SERVICE should be initialized
    * to point to that gss_OID_desc.
    */
   extern gss_OID GSS_C_NT_HOSTBASED_SERVICE;

   /*
    * The implementation must reserve static storage for a
    * gss_OID_desc object containing the value
    * {6, (void *)"\x2b\x06\01\x05\x06\x03"},
    * corresponding to an object identifier value of
    * {1(iso), 3(org), 6(dod), 1(internet), 5(security),
    * 6(nametypes), 3(gss-anonymous-name)}.  The constant
    * and GSS_C_NT_ANONYMOUS should be initialized to point
    * to that gss_OID_desc.
    */
   extern gss_OID GSS_C_NT_ANONYMOUS;


   /*
    * The implementation must reserve static storage for a
    * gss_OID_desc object containing the value
    * {6, (void *)"\x2b\x06\x01\x05\x06\x04"},
    * corresponding to an object-identifier value of
    * {1(iso), 3(org), 6(dod), 1(internet), 5(security),
    * 6(nametypes), 4(gss-api-exported-name)}.  The constant
    * GSS_C_NT_EXPORT_NAME should be initialized to point
    * to that gss_OID_desc.
    */
   extern gss_OID GSS_C_NT_EXPORT_NAME;


   /* Major status codes */

   #define GSS_S_COMPLETE 0

   /*
    * Some "helper" definitions to make the status code macros obvious.
    */
   #define GSS_C_CALLING_ERROR_OFFSET 24
   #define GSS_C_ROUTINE_ERROR_OFFSET 16



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   #define GSS_C_SUPPLEMENTARY_OFFSET 0
   #define GSS_C_CALLING_ERROR_MASK 0377ul
   #define GSS_C_ROUTINE_ERROR_MASK 0377ul
   #define GSS_C_SUPPLEMENTARY_MASK 0177777ul

   /*
    * The macros that test status codes for error conditions.
    * Note that the GSS_ERROR() macro has changed slightly from
    * the V1 GSS-API so that it now evaluates its argument
    * only once.
    */
   #define GSS_CALLING_ERROR(x) \
    (x &amp; (GSS_C_CALLING_ERROR_MASK &lt;&lt; GSS_C_CALLING_ERROR_OFFSET))
   #define GSS_ROUTINE_ERROR(x) \
    (x &amp; (GSS_C_ROUTINE_ERROR_MASK &lt;&lt; GSS_C_ROUTINE_ERROR_OFFSET))
   #define GSS_SUPPLEMENTARY_INFO(x) \
    (x &amp; (GSS_C_SUPPLEMENTARY_MASK &lt;&lt; GSS_C_SUPPLEMENTARY_OFFSET))
   #define GSS_ERROR(x) \
    (x &amp; ((GSS_C_CALLING_ERROR_MASK &lt;&lt; GSS_C_CALLING_ERROR_OFFSET) | \
          (GSS_C_ROUTINE_ERROR_MASK &lt;&lt; GSS_C_ROUTINE_ERROR_OFFSET)))

   /*
    * Now the actual status code definitions
    */

   /*
    * Calling errors:

    */
   #define GSS_S_CALL_INACCESSIBLE_READ \
   (1ul &lt;&lt; GSS_C_CALLING_ERROR_OFFSET)
   #define GSS_S_CALL_INACCESSIBLE_WRITE \
   (2ul &lt;&lt; GSS_C_CALLING_ERROR_OFFSET)
   #define GSS_S_CALL_BAD_STRUCTURE \
   (3ul &lt;&lt; GSS_C_CALLING_ERROR_OFFSET)

   /*
    * Routine errors:
    */
   #define GSS_S_BAD_MECH             (1ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_BAD_NAME             (2ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_BAD_NAMETYPE         (3ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_BAD_BINDINGS         (4ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_BAD_STATUS           (5ul &lt;&lt;



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   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_BAD_SIG              (6ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_BAD_MIC GSS_S_BAD_SIG
   #define GSS_S_NO_CRED              (7ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_NO_CONTEXT           (8ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_DEFECTIVE_TOKEN      (9ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_DEFECTIVE_CREDENTIAL (10ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_CREDENTIALS_EXPIRED  (11ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_CONTEXT_EXPIRED      (12ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_FAILURE              (13ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_BAD_QOP              (14ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_UNAUTHORIZED         (15ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_UNAVAILABLE          (16ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_DUPLICATE_ELEMENT    (17ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)
   #define GSS_S_NAME_NOT_MN          (18ul &lt;&lt;
   GSS_C_ROUTINE_ERROR_OFFSET)

   /*
    * Supplementary info bits:
    */
   #define GSS_S_CONTINUE_NEEDED \
            (1ul &lt;&lt; (GSS_C_SUPPLEMENTARY_OFFSET + 0))
   #define GSS_S_DUPLICATE_TOKEN \
            (1ul &lt;&lt; (GSS_C_SUPPLEMENTARY_OFFSET + 1))
   #define GSS_S_OLD_TOKEN \
            (1ul &lt;&lt; (GSS_C_SUPPLEMENTARY_OFFSET + 2))
   #define GSS_S_UNSEQ_TOKEN \
            (1ul &lt;&lt; (GSS_C_SUPPLEMENTARY_OFFSET + 3))
   #define GSS_S_GAP_TOKEN \
            (1ul &lt;&lt; (GSS_C_SUPPLEMENTARY_OFFSET + 4))

   /*
    * Finally, function prototypes for the GSS-API routines.
    */





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   OM_uint32 gss_acquire_cred
                 (OM_uint32 ,             /*  minor_status */
                  const gss_name_t,       /* desired_name */
                  OM_uint32,              /* time_req */
                  const gss_OID_set,      /* desired_mechs */
                  gss_cred_usage_t,       /* cred_usage */
                  gss_cred_id_t ,         /* output_cred_handle */
                  gss_OID_set ,           /* actual_mechs */
                  OM_uint32 *             /* time_rec */
                 );

   OM_uint32 gss_release_cred
                 (OM_uint32 ,             /* minor_status */
                  gss_cred_id_t *         /* cred_handle */
                 );

   OM_uint32 gss_init_sec_context
                 (OM_uint32 ,             /* minor_status */
                  const gss_cred_id_t,    /* initiator_cred_handle */
                  gss_ctx_id_t ,          /* context_handle */
                  const gss_name_t,       /* target_name */
                  const gss_OID,          /* mech_type */
                  OM_uint32,              /* req_flags */
                  OM_uint32,              /* time_req */
                  const gss_channel_bindings_t,
                                          /* input_chan_bindings */
                  const gss_buffer_t,     /* input_token */
                  gss_OID ,               /* actual_mech_type */
                  gss_buffer_t,           /* output_token */
                  OM_uint32 ,             /* ret_flags */
                  OM_uint32 *             /* time_rec */
                 );

   OM_uint32 gss_accept_sec_context
                 (OM_uint32 ,             /* minor_status */
                  gss_ctx_id_t ,          /* context_handle */
                  const gss_cred_id_t,    /* acceptor_cred_handle */
                  const gss_buffer_t,     /* input_token_buffer */
                  const gss_channel_bindings_t,
                                          /* input_chan_bindings */
                  gss_name_t ,            /* src_name */
                  gss_OID ,               /* mech_type */
                  gss_buffer_t,           /* output_token */
                  OM_uint32 ,             /* ret_flags */
                  OM_uint32 ,             /* time_rec */
                  gss_cred_id_t *         /* delegated_cred_handle */
                 );




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   OM_uint32 gss_process_context_token
                 (OM_uint32 ,             /* minor_status */
                  const gss_ctx_id_t,     /* context_handle */
                  const gss_buffer_t      /* token_buffer */
                 );

   OM_uint32 gss_delete_sec_context
                 (OM_uint32 ,             /* minor_status */
                  gss_ctx_id_t ,          /* context_handle */
                  gss_buffer_t            /* output_token */
                 );

   OM_uint32 gss_context_time
                 (OM_uint32 ,             /* minor_status */
                  const gss_ctx_id_t,     /* context_handle */
                  OM_uint32 *             /* time_rec */
                 );

   OM_uint32 gss_get_mic
                 (OM_uint32 ,             /* minor_status */
                  const gss_ctx_id_t,     /* context_handle */
                  gss_qop_t,              /* qop_req */
                  const gss_buffer_t,     /* message_buffer */
                  gss_buffer_t            /* message_token */
                 );

   OM_uint32 gss_verify_mic
                 (OM_uint32 ,             /* minor_status */
                  const gss_ctx_id_t,     /* context_handle */
                  const gss_buffer_t,     /* message_buffer */
                  const gss_buffer_t,     /* token_buffer */
                  gss_qop_t *             /* qop_state */
                 );

   OM_uint32 gss_wrap
                 (OM_uint32 ,             /* minor_status */
                  const gss_ctx_id_t,     /* context_handle */
                  int,                    /* conf_req_flag */
                  gss_qop_t,              /* qop_req */
                  const gss_buffer_t,     /* input_message_buffer */
                  int ,                   /* conf_state */
                  gss_buffer_t            /* output_message_buffer */
                 );








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   OM_uint32 gss_unwrap
                 (OM_uint32 ,             /* minor_status */
                  const gss_ctx_id_t,     /* context_handle */
                  const gss_buffer_t,     /* input_message_buffer */
                  gss_buffer_t,           /* output_message_buffer */
                  int ,                   /* conf_state */
                  gss_qop_t *             /* qop_state */
                 );



   OM_uint32 gss_display_status
                 (OM_uint32 ,             /* minor_status */
                  OM_uint32,              /* status_value */
                  int,                    /* status_type */
                  const gss_OID,          /* mech_type */
                  OM_uint32 ,             /* message_context */
                  gss_buffer_t            /* status_string */
                 );

   OM_uint32 gss_indicate_mechs
                 (OM_uint32 ,             /* minor_status */
                  gss_OID_set *           /* mech_set */
                 );

   OM_uint32 gss_compare_name
                 (OM_uint32 ,             /* minor_status */
                  const gss_name_t,       /* name1 */
                  const gss_name_t,       /* name2 */
                  int *                   /* name_equal */
                 );

   OM_uint32 gss_display_name
                 (OM_uint32 ,             /* minor_status */
                  const gss_name_t,       /* input_name */
                  gss_buffer_t,           /* output_name_buffer */
                  gss_OID *               /* output_name_type */
                 );

   OM_uint32 gss_import_name
                 (OM_uint32 ,             /* minor_status */
                  const gss_buffer_t,     /* input_name_buffer */
                  const gss_OID,          /* input_name_type */
                  gss_name_t *            /* output_name */
                 );






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   OM_uint32 gss_export_name
                 (OM_uint32,              /* minor_status */
                  const gss_name_t,       /* input_name */
                  gss_buffer_t            /* exported_name */
                 );

   OM_uint32 gss_release_name
                 (OM_uint32 *,            /* minor_status */
                  gss_name_t *            /* input_name */
                 );

   OM_uint32 gss_release_buffer
                 (OM_uint32 ,             /* minor_status */
                  gss_buffer_t            /* buffer */
                 );

   OM_uint32 gss_release_oid_set
                 (OM_uint32 ,             /* minor_status */
                  gss_OID_set *           /* set */
                 );

   OM_uint32 gss_inquire_cred
                 (OM_uint32 ,             /* minor_status */
                  const gss_cred_id_t,    /* cred_handle */
                  gss_name_t ,            /* name */
                  OM_uint32 ,             /* lifetime */
                  gss_cred_usage_t ,      /* cred_usage */
                  gss_OID_set *           /* mechanisms */
                 );

   OM_uint32 gss_inquire_context (
                  OM_uint32 ,             /* minor_status */
                  const gss_ctx_id_t,     /* context_handle */
                  gss_name_t ,            /* src_name */
                  gss_name_t ,            /* targ_name */
                  OM_uint32 ,             /* lifetime_rec */
                  gss_OID ,               /* mech_type */
                  OM_uint32 ,             /* ctx_flags */
                  int ,                   /* locally_initiated */
                  int *                   /* open */
                 );










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   OM_uint32 gss_wrap_size_limit (
                  OM_uint32 ,             /* minor_status */
                  const gss_ctx_id_t,     /* context_handle */
                  int,                    /* conf_req_flag */
                  gss_qop_t,              /* qop_req */
                  OM_uint32,              /* req_output_size */
                  OM_uint32 *             /* max_input_size */
                 );

   OM_uint32 gss_add_cred (
                  OM_uint32 ,             /* minor_status */
                  const gss_cred_id_t,    /* input_cred_handle */
                  const gss_name_t,       /* desired_name */
                  const gss_OID,          /* desired_mech */
                  gss_cred_usage_t,       /* cred_usage */
                  OM_uint32,              /* initiator_time_req */
                  OM_uint32,              /* acceptor_time_req */
                  gss_cred_id_t ,         /* output_cred_handle */
                  gss_OID_set ,           /* actual_mechs */
                  OM_uint32 ,             /* initiator_time_rec */
                  OM_uint32 *             /* acceptor_time_rec */
                 );

   OM_uint32 gss_inquire_cred_by_mech (
                  OM_uint32 ,             /* minor_status */
                  const gss_cred_id_t,    /* cred_handle */
                  const gss_OID,          /* mech_type */
                  gss_name_t ,            /* name */
                  OM_uint32 ,             /* initiator_lifetime */
                  OM_uint32 ,             /* acceptor_lifetime */
                  gss_cred_usage_t *      /* cred_usage */
                 );

   OM_uint32 gss_export_sec_context (
                  OM_uint32 ,             /* minor_status */
                  gss_ctx_id_t ,          /* context_handle */
                  gss_buffer_t            /* interprocess_token */
                 );

   OM_uint32 gss_import_sec_context (
                  OM_uint32 ,             /* minor_status */
                  const gss_buffer_t,     /* interprocess_token */
                  gss_ctx_id_t *          /* context_handle */
                 );







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   OM_uint32 gss_create_empty_oid_set (
                  OM_uint32 ,             /* minor_status */
                  gss_OID_set *           /* oid_set */
                 );

   OM_uint32 gss_add_oid_set_member (
                  OM_uint32 ,             /* minor_status */
                  const gss_OID,          /* member_oid */
                  gss_OID_set *           /* oid_set */
                 );

   OM_uint32 gss_test_oid_set_member (
                  OM_uint32 ,             /* minor_status */
                  const gss_OID,          /* member */
                  const gss_OID_set,      /* set */
                  int *                   /* present */
                 );

   OM_uint32 gss_inquire_names_for_mech (
                  OM_uint32 ,             /* minor_status */
                  const gss_OID,          /* mechanism */
                  gss_OID_set *           /* name_types */
                 );

   OM_uint32 gss_inquire_mechs_for_name (
                  OM_uint32 ,             /* minor_status */
                  const gss_name_t,       /* input_name */
                  gss_OID_set *           /* mech_types */
                 );

   OM_uint32 gss_canonicalize_name (
                  OM_uint32 ,             /* minor_status */
                  const gss_name_t,       /* input_name */
                  const gss_OID,          /* mech_type */
                  gss_name_t *            /* output_name */
                 );

   OM_uint32 gss_duplicate_name (
                  OM_uint32 ,             /* minor_status */
                  const gss_name_t,       /* src_name */
                  gss_name_t *            /* dest_name */
                 );

   /*
    * The following routines are obsolete variants of gss_get_mic,
    * gss_verify_mic, gss_wrap and gss_unwrap.  They should be
    * provided by GSS-API V2 implementations for backwards
    * compatibility with V1 applications.  Distinct entrypoints



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    * (as opposed to #defines) should be provided, both to allow
    * GSS-API V1 applications to link against GSS-API V2
      implementations,
    * and to retain the slight parameter type differences between the
    * obsolete versions of these routines and their current forms.
    */

   OM_uint32 gss_sign
                 (OM_uint32 ,        /* minor_status */
                  gss_ctx_id_t,      /* context_handle */
                  int,               /* qop_req */
                  gss_buffer_t,      /* message_buffer */
                  gss_buffer_t       /* message_token */
                 );


   OM_uint32 gss_verify
                 (OM_uint32 ,        /* minor_status */
                  gss_ctx_id_t,      /* context_handle */
                  gss_buffer_t,      /* message_buffer */
                  gss_buffer_t,      /* token_buffer */
                  int *              /* qop_state */
                 );

   OM_uint32 gss_seal
                 (OM_uint32 ,        /* minor_status */
                  gss_ctx_id_t,      /* context_handle */
                  int,               /* conf_req_flag */
                  int,               /* qop_req */
                  gss_buffer_t,      /* input_message_buffer */
                  int ,              /* conf_state */
                  gss_buffer_t       /* output_message_buffer */
                 );


   OM_uint32 gss_unseal
                 (OM_uint32 ,        /* minor_status */
                  gss_ctx_id_t,      /* context_handle */
                  gss_buffer_t,      /* input_message_buffer */
                  gss_buffer_t,      /* output_message_buffer */
                  int ,              /* conf_state */
                  int *              /* qop_state */
                 );

   #endif /* GSSAPI_H_ */






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<span class="h2"><a class="selflink" id="appendix-B" href="#appendix-B">Appendix B</a>. Additional constraints for application binary portability</span>

   The purpose of this C-bindings document is to encourage source-level
   portability of applications across GSS-API implementations on
   different platforms and atop different mechanisms.  Additional goals
   that have not been explicitly addressed by this document are link-
   time and run-time portability.

   Link-time portability provides the ability to compile an application
   against one implementation of GSS-API, and then link it against a
   different implementation on the same platform.  It is a stricter
   requirement than source-level portability.

   Run-time portability differs from link-time portability only on those
   platforms that implement dynamically loadable GSS-API
   implementations, but do not offer load-time symbol resolution. On
   such platforms, run-time portability is a stricter requirement than
   link-time portability, and will typically include the precise
   placement of the various GSS-API routines within library entrypoint
   vectors.

   Individual platforms will impose their own rules that must be
   followed to achieve link-time (and run-time, if different)
   portability.  In order to ensure either form of binary portability,
   an ABI specification must be written for GSS-API implementations on
   that platform.  However, it is recognized that there are some issues
   that are likely to be common to all such ABI specifications. This
   appendix is intended to be a repository for such common issues, and
   contains some suggestions that individual ABI specifications may
   choose to reference. Since machine architectures vary greatly, it may
   not be possible or desirable to follow these suggestions on all
   platforms.

<span class="h3"><a class="selflink" id="appendix-B.1" href="#appendix-B.1">B.1</a>. Pointers</span>

   While ANSI-C provides a single pointer type for each declared type,
   plus a single (void *) type, some platforms (notably those using
   segmented memory architectures) augment this with various modified
   pointer types (e.g. far pointers, near pointers). These language
   bindings assume ANSI-C, and thus do not address such non-standard
   implementations.  GSS-API implementations for such platforms must
   choose an appropriate memory model, and should use it consistently
   throughout.  For example, if a memory model is chosen that requires
   the use of far pointers when passing routine parameters, then far
   pointers should also be used within the structures defined by GSS-
   API.





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<span class="h3"><a class="selflink" id="appendix-B.2" href="#appendix-B.2">B.2</a>. Internal structure alignment</span>

   GSS-API defines several data-structures containing differently-sized
   fields.  An ABI specification should include a detailed description
   of how the fields of such structures are aligned, and if there is any
   internal padding in these data structures.  The use of compiler
   defaults for the platform is recommended.

<span class="h3"><a class="selflink" id="appendix-B.3" href="#appendix-B.3">B.3</a>. Handle types</span>

   The C bindings specify that the gss_cred_id_t and gss_ctx_id_t types
   should be implemented as either pointer or arithmetic types, and that
   if pointer types are used, care should be taken to ensure that two
   handles may be compared with the == operator. Note that ANSI-C does
   not guarantee that two pointer values may be compared with the ==
   operator unless either the two pointers point to members of a single
   array, or at least one of the pointers contains a NULL value.

   For binary portability, additional constraints are required. The
   following is an attempt at defining platform-independent constraints.

   The size of the handle type must be the same as sizeof(void *), using
   the appropriate memory model.

   The == operator for the chosen type must be a simple bit-wise
   comparison.  That is, for two in-memory handle objects h1 and h2, the
   boolean value of the expression

      (h1 == h2)

   should always be the same as the boolean value of the expression

      (memcmp(&amp;h1, &amp;h2, sizeof(h1)) == 0)

   The actual use of the type (void *) for handle types is discouraged,
   not for binary portability reasons, but since it effectively disables
   much of the compile-time type-checking that the compiler can
   otherwise perform, and is therefore not "programmer-friendly".  If a
   pointer implementation is desired, and if the platform's
   implementation of pointers permits, the handles should be implemented
   as pointers to distinct implementation-defined types.

<span class="h3"><a class="selflink" id="appendix-B.4" href="#appendix-B.4">B.4</a>. The gss_name_t type</span>

   The gss_name_t type, representing the internal name object, should be
   implemented as a pointer type.  The use of the (void *) type is
   discouraged as it does not allow the compiler to perform strong
   type-checking.  However, the pointer type chosen should be of the



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   same size as the (void *) type.  Provided this rule is obeyed, ABI
   specifications need not further constrain the implementation of
   gss_name_t objects.

<span class="h3"><a class="selflink" id="appendix-B.5" href="#appendix-B.5">B.5</a>. The int and size_t types</span>

   Some platforms may support differently sized implementations of the
   "int" and "size_t" types, perhaps chosen through compiler switches,
   and perhaps dependent on memory model.  An ABI specification for such
   a platform should include required implementations for these types.
   It is recommended that the default implementation (for the chosen
   memory model, if appropriate) is chosen.

<span class="h3"><a class="selflink" id="appendix-B.6" href="#appendix-B.6">B.6</a>. Procedure-calling conventions</span>

   Some platforms support a variety of different binary conventions for
   calling procedures.  Such conventions cover things like the format of
   the stack frame, the order in which the routine parameters are pushed
   onto the stack, whether or not a parameter count is pushed onto the
   stack, whether some argument(s) or return values are to be passed in
   registers, and whether the called routine or the caller is
   responsible for removing the stack frame on return.  For such
   platforms, an ABI specification should specify which calling
   convention is to be used for GSS-API implementations.

References

   [<a id="ref-GSSAPI">GSSAPI</a>]    Linn, J., "Generic Security Service Application Program
               Interface Version 2, Update 1", <a href="./rfc2743">RFC 2743</a>, January 2000.

   [<a id="ref-XOM">XOM</a>]       OSI Object Management API Specification, Version 2.0 t",
               X.400 API Association &amp; X/Open Company Limited, August
               24, 1990 Specification of datatypes and routines for
               manipulating information objects.

Author's Address

   John Wray
   Iris Associates
   5 Technology Park Drive,
   Westford, MA  01886
   USA

   Phone: +1-978-392-6689
   EMail: John_Wray@Iris.com






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<span class="grey"><a href="./rfc2744">RFC 2744</a>                 GSS-API V2: C-bindings             January 2000</span>


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