.\" DO NOT MODIFY THIS FILE!  It was generated by gdoc.
.TH "gss_accept_sec_context" 3 "1.0.4" "gss" "gss"
.SH NAME
gss_accept_sec_context \- API function
.SH SYNOPSIS
.B #include <gss.h>
.sp
.BI "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 ");"
.SH ARGUMENTS
.IP "OM_uint32 * minor_status" 12
(Integer, modify) Mechanism specific status code.
.IP "gss_ctx_id_t * context_handle" 12
(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 \fBgss_accept_sec_context()\fP 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 \fBgss_delete_sec_context()\fP.
.IP "const gss_cred_id_t acceptor_cred_handle" 12
(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.
.IP "const gss_buffer_t input_token_buffer" 12
(buffer, opaque, read) Token obtained from
  remote application.
.IP "const gss_channel_bindings_t input_chan_bindings" 12
(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.
.IP "gss_name_t * src_name" 12
(gss_name_t, modify, optional) Authenticated name of
  context initiator.  After use, this name should be deallocated by
  passing it to \fBgss_release_name()\fP.  If not required, specify NULL.
.IP "gss_OID * mech_type" 12
(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.
.IP "gss_buffer_t output_token" 12
(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
  \fBgss_release_buffer()\fP.
.IP "OM_uint32 * ret_flags" 12
(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.  See below for the flags.
.IP "OM_uint32 * time_rec" 12
(Integer, modify, optional) Number of seconds for which
  the context will remain valid. Specify NULL if not required.
.IP "gss_cred_id_t * delegated_cred_handle" 12
(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,
  \fBgss_accept_sec_context()\fP 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 \fBgss_release_cred()\fP.  Specify NULL if not
  required.
.SH "DESCRIPTION"
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.

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

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

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 \fBgss_accept_sec_context()\fP 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.

The `ret_flags` values:

`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 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 \fBgss_export_sec_context()\fP.
\- False \- The security context is not transferable.

All other bits should be set to zero.
.SH "RETURN VALUE"

`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.

`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.
.SH "REPORTING BUGS"
Report bugs to <bug-gss@gnu.org>.
GNU Generic Security Service home page: http://www.gnu.org/software/gss/
General help using GNU software: http://www.gnu.org/gethelp/
.SH COPYRIGHT
Copyright \(co 2003-2022 Simon Josefsson.
.br
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
.SH "SEE ALSO"
The full documentation for
.B gss
is maintained as a Texinfo manual.  If the
.B info
and
.B gss
programs are properly installed at your site, the command
.IP
.B info gss
.PP
should give you access to the complete manual.