File: snmpusm.c

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/* Portions of this file are subject to the following copyright(s).  See
 * the Net-SNMP's COPYING file for more details and other copyrights
 * that may apply:
 */
/*
 * Portions of this file are copyrighted by:
 * Copyright © 2003 Sun Microsystems, Inc. All rights reserved.
 * Use is subject to license terms specified in the COPYING file
 * distributed with the Net-SNMP package.
 *
 * Portions of this file are copyrighted by:
 * Copyright (c) 2016 VMware, Inc. All rights reserved.
 * Use is subject to license terms specified in the COPYING file
 * distributed with the Net-SNMP package.
 */
/*
 * snmpusm.c
 *
 * Routines to manipulate a information about a "user" as
 * defined by the SNMP-USER-BASED-SM-MIB MIB.
 *
 * All functions usm_set_usmStateReference_*() return 0 on success, -1
 * otherwise.
 *
 * !! Tab stops set to 4 in some parts of this file. !!
 *    (Designated on a per function.)
 */

#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-features.h>

#include <sys/types.h>
#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# ifdef HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <net-snmp/types.h>
#include <net-snmp/output_api.h>
#include <net-snmp/config_api.h>
#include <net-snmp/utilities.h>

#include <net-snmp/library/openssl_config.h>
#include <net-snmp/library/asn1.h>
#include <net-snmp/library/snmp_api.h>
#include <net-snmp/library/callback.h>
#include <net-snmp/library/tools.h>
#include <net-snmp/library/keytools.h>
#include <net-snmp/library/snmpv3.h>
#include <net-snmp/library/lcd_time.h>
#include <net-snmp/library/scapi.h>
#include <net-snmp/library/callback.h>
#include <net-snmp/library/snmp_secmod.h>
#include <net-snmp/library/snmpusm.h>
#include <net-snmp/library/transform_oids.h>
#include <net-snmp/library/snmp_enum.h>

#ifdef HAVE_OPENSSL_DH_H
#include <openssl/dh.h>
#endif

netsnmp_feature_child_of(usm_all, libnetsnmp);
netsnmp_feature_child_of(usm_support, usm_all);

netsnmp_feature_require(usm_support);

struct usmStateReference {
    int             refcnt;
    char           *usr_name;
    size_t          usr_name_length;
    u_char         *usr_engine_id;
    size_t          usr_engine_id_length;
    oid            *usr_auth_protocol;
    size_t          usr_auth_protocol_length;
    u_char         *usr_auth_key;
    size_t          usr_auth_key_length;
    oid            *usr_priv_protocol;
    size_t          usr_priv_protocol_length;
    u_char         *usr_priv_key;
    size_t          usr_priv_key_length;
    u_int           usr_sec_level;
};

oid    usmNoAuthProtocol[10] = { NETSNMP_USMAUTH_BASE_OID,
                                 NETSNMP_USMAUTH_NOAUTH };
#ifndef NETSNMP_DISABLE_MD5
oid    usmHMACMD5AuthProtocol[10] = { NETSNMP_USMAUTH_BASE_OID,
                                      NETSNMP_USMAUTH_HMACMD5 };
#endif
oid    usmHMACSHA1AuthProtocol[10] = { NETSNMP_USMAUTH_BASE_OID,
                                       NETSNMP_USMAUTH_HMACSHA1 };

#ifdef HAVE_EVP_SHA384
oid    usmHMAC384SHA512AuthProtocol[10] = { NETSNMP_USMAUTH_BASE_OID,
                                            NETSNMP_USMAUTH_HMAC384SHA512 };
oid    usmHMAC256SHA384AuthProtocol[10] = { NETSNMP_USMAUTH_BASE_OID,
                                            NETSNMP_USMAUTH_HMAC256SHA384 };
#endif /* HAVE_EVP_SHA384 */

#ifdef HAVE_EVP_SHA224
oid    usmHMAC192SHA256AuthProtocol[10] = { NETSNMP_USMAUTH_BASE_OID,
                                            NETSNMP_USMAUTH_HMAC192SHA256 };
oid    usmHMAC128SHA224AuthProtocol[10] = { NETSNMP_USMAUTH_BASE_OID,
                                            NETSNMP_USMAUTH_HMAC128SHA224 };
#endif /* HAVE_EVP_SHA384 */

oid             usmNoPrivProtocol[10] = { 1, 3, 6, 1, 6, 3, 10, 1, 2, 1 };

#ifndef NETSNMP_DISABLE_DES
oid             usmDESPrivProtocol[10] = { 1, 3, 6, 1, 6, 3, 10, 1, 2, 2 };
#endif


oid    usmAESPrivProtocol[10] = { 1, 3, 6, 1, 6, 3, 10, 1, 2, 4 };
/* backwards compat */
oid    *usmAES128PrivProtocol = usmAESPrivProtocol;

#ifdef NETSNMP_DRAFT_BLUMENTHAL_AES_04
    /* OIDs from http://www.snmp.com/eso/esoConsortiumMIB.txt */
oid    usmAES192PrivProtocol[9] = { 1,3,6,1,4,1,14832,1,3 };
oid    usmAES256PrivProtocol[9] = { 1,3,6,1,4,1,14832,1,4 };
    /* OIDs from CISCO MIB */
oid    usmAES192CiscoPrivProtocol[11]  = { 1,3,6,1,4,1,9,12,6,1,1 };
oid    usmAES256CiscoPrivProtocol[11]  = { 1,3,6,1,4,1,9,12,6,1,2 };
/*
 * these OIDs are in pySNMP source as OIDs for AES+Reeder. We'll just
 * use OIDS from CISCO-SNMP-USM-OIDS-MIB
 *
oid    usmAES192Cisco2PrivProtocol[11]  = { 1,3,6,1,4,1,9,12,6,1,101 };
oid    usmAES256Cisco2PrivProtocol[11]  = { 1,3,6,1,4,1,9,12,6,1,102 };
 */
#endif /* NETSNMP_DRAFT_BLUMENTHAL_AES_04 */

typedef struct usm_alg_type_s {
    const char *label;
    int         value;
} usm_alg_type_t;

static const usm_alg_type_t usm_auth_type[] = {
    { "NOAUTH", NETSNMP_USMAUTH_NOAUTH },
    { "SHA", NETSNMP_USMAUTH_HMACSHA1 },
    { "SHA-1", NETSNMP_USMAUTH_HMACSHA1 },
    { "SHA1", NETSNMP_USMAUTH_HMACSHA1 },
#ifndef NETSNMP_DISABLE_MD5
    { "MD5", NETSNMP_USMAUTH_HMACMD5 },
#endif
#ifdef HAVE_EVP_SHA224
    { "SHA-224", NETSNMP_USMAUTH_HMAC128SHA224 },
    { "SHA224", NETSNMP_USMAUTH_HMAC128SHA224 },
    { "SHA-256", NETSNMP_USMAUTH_HMAC192SHA256 },
    { "SHA256", NETSNMP_USMAUTH_HMAC192SHA256 },
#endif
#ifdef HAVE_EVP_SHA384
    { "SHA-384", NETSNMP_USMAUTH_HMAC256SHA384 },
    { "SHA384", NETSNMP_USMAUTH_HMAC256SHA384 },
    { "SHA-512",  NETSNMP_USMAUTH_HMAC384SHA512 },
    { "SHA512",  NETSNMP_USMAUTH_HMAC384SHA512 },
#endif
    { NULL, -1 }
};

static const usm_alg_type_t usm_priv_type[] = {
    { "NOPRIV", USM_CREATE_USER_PRIV_NONE },
#ifndef NETSNMP_DISABLE_DES
    { "DES", USM_CREATE_USER_PRIV_DES },
#endif
#ifdef HAVE_AES
    { "AES", USM_CREATE_USER_PRIV_AES },
    { "AES-128", USM_CREATE_USER_PRIV_AES },
    { "AES128", USM_CREATE_USER_PRIV_AES },
#ifdef NETSNMP_DRAFT_BLUMENTHAL_AES_04
    { "AES-192", USM_CREATE_USER_PRIV_AES192 },
    { "AES192", USM_CREATE_USER_PRIV_AES192 },
    { "AES-256", USM_CREATE_USER_PRIV_AES256 },
    { "AES256", USM_CREATE_USER_PRIV_AES256 },
    /** cisco / pysnmp variations */
    { "AES-192-C", USM_CREATE_USER_PRIV_AES192_CISCO },
    { "AES192C", USM_CREATE_USER_PRIV_AES192_CISCO },
    { "AES-256-C", USM_CREATE_USER_PRIV_AES256_CISCO },
    { "AES256C", USM_CREATE_USER_PRIV_AES256_CISCO },
#endif
#endif
    { NULL, -1 },
};

static u_int    dummy_etime, dummy_eboot;       /* For ISENGINEKNOWN(). */

/*
 * Set up default snmpv3 parameter value storage.
 */
#ifdef NETSNMP_SECMOD_USM
static const oid *defaultAuthType = NULL;
static size_t   defaultAuthTypeLen = 0;
static const oid *defaultPrivType = NULL;
static size_t   defaultPrivTypeLen = 0;
#endif /* NETSNMP_SECMOD_USM */

/*
 * Globals.
 */
static u_int    salt_integer;
#ifdef HAVE_AES
static u_int    salt_integer64_1, salt_integer64_2;
#endif
        /*
         * 1/2 of seed for the salt.   Cf. RFC2274, Sect 8.1.1.1.
         */

static struct usmUser *noNameUser = NULL;
/*
 * Local storage (LCD) of the default user list.
 */
static struct usmUser *userList = NULL;

/*
 * Set a given field of the secStateRef.
 *
 * Allocate <len> bytes for type <type> pointed to by ref-><field>.
 * Then copy in <item> and record its length in ref-><field_len>.
 *
 * Return 0 on success, -1 otherwise.
 */
#define MAKE_ENTRY(ref, type, item, len, field, field_len)      \
do {                                                            \
	if (ref == NULL)                                        \
		return -1;                                      \
	if (ref->field != NULL)	{                               \
		SNMP_ZERO(ref->field, ref->field_len);          \
		SNMP_FREE(ref->field);                          \
	}                                                       \
	ref->field_len = 0;                                     \
        if (len == 0 || item == NULL)                           \
		return 0;                                       \
	ref->field = netsnmp_memdup(item, len * sizeof(type));  \
        if (ref->field == NULL)                                 \
		return -1;                                      \
                                                                \
	ref->field_len = len;                                   \
	return 0;                                               \
} while (0)

static int
usm_clone_usmStateReference(struct usmStateReference *from,
                            struct usmStateReference **to);

static int
free_enginetime_on_shutdown(int majorid, int minorid, void *serverarg,
			    void *clientarg)
{
    u_char engineID[SNMP_MAX_ENG_SIZE];
    size_t engineID_len = sizeof(engineID);

    DEBUGMSGTL(("snmpv3", "free enginetime callback called\n"));

    engineID_len = snmpv3_get_engineID(engineID, engineID_len);
    if (engineID_len > 0)
	free_enginetime(engineID, engineID_len);
    return 0;
}

static struct usmStateReference *
usm_malloc_usmStateReference(void)
{
    struct usmStateReference *retval;

    retval = calloc(1, sizeof(struct usmStateReference));
    if (retval)
        retval->refcnt = 1;

    return retval;
}                               /* end usm_malloc_usmStateReference() */

static int
usm_clone(netsnmp_pdu *pdu, netsnmp_pdu *new_pdu)
{
    struct usmStateReference *ref = pdu->securityStateRef;
    struct usmStateReference **new_ref =
        (struct usmStateReference **)&new_pdu->securityStateRef;
    int ret = 0;

    if (!ref)
        return ret;

    if (pdu->command == SNMP_MSG_TRAP2) {
        netsnmp_assert(pdu->securityModel == SNMP_DEFAULT_SECMODEL);
        ret = usm_clone_usmStateReference(ref, new_ref);
    } else {
        netsnmp_assert(ref == *new_ref);
        ref->refcnt++;
    }

    return ret;
}

static void
usm_free_usmStateReference(void *old)
{
    struct usmStateReference *ref = old;

    if (!ref)
        return;

    if (--ref->refcnt > 0)
        return;

    SNMP_FREE(ref->usr_name);
    SNMP_FREE(ref->usr_engine_id);
    SNMP_FREE(ref->usr_auth_protocol);
    SNMP_FREE(ref->usr_priv_protocol);

    if (ref->usr_auth_key_length && ref->usr_auth_key) {
        SNMP_ZERO(ref->usr_auth_key, ref->usr_auth_key_length);
        SNMP_FREE(ref->usr_auth_key);
    }
    if (ref->usr_priv_key_length && ref->usr_priv_key) {
        SNMP_ZERO(ref->usr_priv_key, ref->usr_priv_key_length);
        SNMP_FREE(ref->usr_priv_key);
    }

    SNMP_FREE(ref);
}                               /* end usm_free_usmStateReference() */

struct usmUser *
usm_get_userList(void)
{
    return userList;
}

static int
usm_set_usmStateReference_name(struct usmStateReference *ref,
                               char *name, size_t name_len)
{
    MAKE_ENTRY(ref, char, name, name_len, usr_name, usr_name_length);
}

static int
usm_set_usmStateReference_engine_id(struct usmStateReference *ref,
                                    u_char * engine_id,
                                    size_t engine_id_len)
{
    MAKE_ENTRY(ref, u_char, engine_id, engine_id_len,
               usr_engine_id, usr_engine_id_length);
}

static int
usm_set_usmStateReference_auth_protocol(struct usmStateReference *ref,
                                        oid * auth_protocol,
                                        size_t auth_protocol_len)
{
    MAKE_ENTRY(ref, oid, auth_protocol, auth_protocol_len,
               usr_auth_protocol, usr_auth_protocol_length);
}

static int
usm_set_usmStateReference_auth_key(struct usmStateReference *ref,
                                   u_char * auth_key, size_t auth_key_len)
{
    MAKE_ENTRY(ref, u_char, auth_key, auth_key_len,
               usr_auth_key, usr_auth_key_length);
}

static int
usm_set_usmStateReference_priv_protocol(struct usmStateReference *ref,
                                        oid * priv_protocol,
                                        size_t priv_protocol_len)
{
    MAKE_ENTRY(ref, oid, priv_protocol, priv_protocol_len,
               usr_priv_protocol, usr_priv_protocol_length);
}

static int
usm_set_usmStateReference_priv_key(struct usmStateReference *ref,
                                   u_char * priv_key, size_t priv_key_len)
{
    MAKE_ENTRY(ref, u_char, priv_key, priv_key_len,
               usr_priv_key, usr_priv_key_length);
}

static int
usm_set_usmStateReference_sec_level(struct usmStateReference *ref,
                                    int sec_level)
{
    if (ref == NULL)
        return -1;
    ref->usr_sec_level = sec_level;
    return 0;
}

static int
usm_clone_usmStateReference(struct usmStateReference *from,
                            struct usmStateReference **to)
{
    struct usmStateReference *cloned_usmStateRef;

    if (from == NULL || to == NULL)
        return -1;

    *to = usm_malloc_usmStateReference();
    cloned_usmStateRef = *to;

    if (usm_set_usmStateReference_name(cloned_usmStateRef, from->usr_name, from->usr_name_length) ||
        usm_set_usmStateReference_engine_id(cloned_usmStateRef, from->usr_engine_id, from->usr_engine_id_length) ||
        usm_set_usmStateReference_auth_protocol(cloned_usmStateRef, from->usr_auth_protocol, from->usr_auth_protocol_length) ||
        usm_set_usmStateReference_auth_key(cloned_usmStateRef, from->usr_auth_key, from->usr_auth_key_length) ||
        usm_set_usmStateReference_priv_protocol(cloned_usmStateRef, from->usr_priv_protocol, from->usr_priv_protocol_length) ||
        usm_set_usmStateReference_priv_key(cloned_usmStateRef, from->usr_priv_key, from->usr_priv_key_length) ||
        usm_set_usmStateReference_sec_level(cloned_usmStateRef, from->usr_sec_level))
    {
        usm_free_usmStateReference(*to);
        *to = NULL;
        return -1;
    }

    return 0;

}

#ifdef NETSNMP_ENABLE_TESTING_CODE
/*******************************************************************-o-******
 * emergency_print
 *
 * Parameters:
 *	*field
 *	 length
 *      
 *	This is a print routine that is solely included so that it can be
 *	used in gdb.  Don't use it as a function, it will be pulled before
 *	a real release of the code.
 *
 *	tab stop 4
 *
 *	XXX fflush() only works on FreeBSD; core dumps on Sun OS's
 */
void
emergency_print(u_char * field, u_int length)
{
    int             iindex;
    int             start = 0;
    int             stop = 25;

    while (start < stop) {
        for (iindex = start; iindex < stop; iindex++)
            printf("%02X ", field[iindex]);

        printf("\n");
        start = stop;
        stop = stop + 25 < length ? stop + 25 : length;
    }
    fflush(0);

}                               /* end emergency_print() */
#endif                          /* NETSNMP_ENABLE_TESTING_CODE */

static struct usmUser *
usm_get_user_from_list(const u_char *engineID, size_t engineIDLen,
                       const char *name, struct usmUser *puserList,
                       int use_default)
{
    struct usmUser *ptr;

    if (name == NULL)
        name = "";
    for (ptr = puserList; ptr != NULL; ptr = ptr->next) {
        if (ptr->name && !strcmp(ptr->name, name)) {
          DEBUGMSGTL(("usm", "match on user %s\n", ptr->name));
          if (ptr->engineIDLen == engineIDLen &&
            ((ptr->engineID == NULL && engineID == NULL) ||
             (ptr->engineID != NULL && engineID != NULL &&
              memcmp(ptr->engineID, engineID, engineIDLen) == 0)))
            return ptr;
          DEBUGMSGTL(("usm", "no match on engineID ("));
          if (engineID) {
              DEBUGMSGHEX(("usm", engineID, engineIDLen));
          } else {
              DEBUGMSGTL(("usm", "Empty EngineID"));
          }
          DEBUGMSG(("usm", ")\n"));
        }
    }

    /*
     * return "" user used to facilitate engineID discovery
     */
    if (use_default && !strcmp(name, ""))
        return noNameUser;
    return NULL;
}

/*
 * usm_get_user(): Returns a user from userList based on the engineID,
 * engineIDLen and name of the requested user.
 */
struct usmUser *
usm_get_user(const u_char *engineID, size_t engineIDLen, const char *name)
{
    DEBUGMSGTL(("usm", "getting user %s\n", name));
    return usm_get_user_from_list(engineID, engineIDLen, name, userList,
                                  1);
}

static struct usmUser *
usm_add_user_to_list(struct usmUser *user, struct usmUser *puserList)
{
    struct usmUser *nptr, *pptr, *optr;

    /*
     * loop through puserList till we find the proper, sorted place to
     * insert the new user
     */
    /* XXX - how to handle a NULL user->name ?? */
    /* XXX - similarly for a NULL nptr->name ?? */
    for (nptr = puserList, pptr = NULL; nptr != NULL;
         pptr = nptr, nptr = nptr->next) {
        if (nptr->engineIDLen > user->engineIDLen)
            break;

        if (user->engineID == NULL && nptr->engineID != NULL)
            break;

        if (nptr->engineIDLen == user->engineIDLen &&
            (nptr->engineID != NULL && user->engineID != NULL &&
             memcmp(nptr->engineID, user->engineID,
                    user->engineIDLen) > 0))
            break;

        if (!(nptr->engineID == NULL && user->engineID != NULL)) {
            if (nptr->engineIDLen == user->engineIDLen &&
                ((nptr->engineID == NULL && user->engineID == NULL) ||
                 memcmp(nptr->engineID, user->engineID,
                        user->engineIDLen) == 0)
                && strlen(nptr->name) > strlen(user->name))
                break;

            if (nptr->engineIDLen == user->engineIDLen &&
                ((nptr->engineID == NULL && user->engineID == NULL) ||
                 memcmp(nptr->engineID, user->engineID,
                        user->engineIDLen) == 0)
                && strlen(nptr->name) == strlen(user->name)
                && strcmp(nptr->name, user->name) > 0)
                break;

            if (nptr->engineIDLen == user->engineIDLen &&
                ((nptr->engineID == NULL && user->engineID == NULL) ||
                 memcmp(nptr->engineID, user->engineID,
                        user->engineIDLen) == 0)
                && strlen(nptr->name) == strlen(user->name)
                && strcmp(nptr->name, user->name) == 0) {
                /*
                 * the user is an exact match of a previous entry.
                 * Credentials may be different, though, so remove
                 * the old entry (and add the new one)!
                 */
                if (pptr) { /* change prev's next pointer */
                  pptr->next = nptr->next;
                }
                if (nptr->next) { /* change next's prev pointer */
                  nptr->next->prev = pptr;
                }
                optr = nptr;
                nptr = optr->next; /* add new user at this position */
                /* free the old user */
                optr->next=NULL;
                optr->prev=NULL;
                usm_free_user(optr);
                break; /* new user will be added below */
            }
        }
    }

    /*
     * nptr should now point to the user that we need to add ourselves
     * in front of, and pptr should be our new 'prev'.
     */

    /*
     * change our pointers
     */
    user->prev = pptr;
    user->next = nptr;

    /*
     * change the next's prev pointer
     */
    if (user->next)
        user->next->prev = user;

    /*
     * change the prev's next pointer
     */
    if (user->prev)
        user->prev->next = user;

    /*
     * rewind to the head of the list and return it (since the new head
     * could be us, we need to notify the above routine who the head now is.
     */
    for (pptr = user; pptr->prev != NULL; pptr = pptr->prev);
    return pptr;
}

/*
 * usm_add_user(): Add's a user to the userList, sorted by the
 * engineIDLength then the engineID then the name length then the name
 * to facilitate getNext calls on a usmUser table which is indexed by
 * these values.
 *
 * returns the head of the list (which could change due to this add).
 */

struct usmUser *
usm_add_user(struct usmUser *user)
{
    struct usmUser *uptr;
    uptr = usm_add_user_to_list(user, userList);
    if (uptr != NULL)
        userList = uptr;
    return uptr;
}

/*
 * usm_remove_usmUser_from_list remove user from (optional) list
 *
 * if list is not specified, defaults to global userList.
 *
 * returns SNMPERR_SUCCESS or SNMPERR_USM_UNKNOWNSECURITYNAME
 */
static int
usm_remove_usmUser_from_list(struct usmUser *user, struct usmUser **ppuserList)
{
    struct usmUser *nptr, *pptr;

    /*
     * NULL pointers aren't allowed
     */
    if (ppuserList == NULL)
        ppuserList = &userList;

    if (*ppuserList == NULL)
        return SNMPERR_USM_UNKNOWNSECURITYNAME;

    /*
     * find the user in the list
     */
    for (nptr = *ppuserList, pptr = NULL; nptr != NULL;
         pptr = nptr, nptr = nptr->next) {
        if (nptr == user)
            break;
    }

    if (nptr) {
        /*
         * remove the user from the linked list
         */
        if (pptr) {
            pptr->next = nptr->next;
        }
        if (nptr->next) {
            nptr->next->prev = pptr;
        }
    } else {
        /*
         * user didn't exist
         */
        return SNMPERR_USM_UNKNOWNSECURITYNAME;
    }
    if (nptr == *ppuserList)    /* we're the head of the list, need to change
                                 * * the head to the next user */
        *ppuserList = nptr->next;
    return SNMPERR_SUCCESS;
}                               /* end usm_remove_usmUser_from_list() */

/*
 * usm_remove_user_from_list
 *
 * removes user from list.
 *
 * returns new list head on success, or NULL on error.
 *
 * NOTE: if there was only one user in the list, list head will be NULL.
 *       So NULL can also mean success. Use the newer usm_remove_usmUser() for
 *       more specific return codes. This function is kept for backwards
 *       compatability with this ambiguous behaviour.
 */
static struct usmUser *
usm_remove_user_from_list(struct usmUser *user,
                          struct usmUser **ppuserList)
{
    int rc = usm_remove_usmUser_from_list(user, ppuserList);
    if (rc != SNMPERR_SUCCESS || NULL == ppuserList)
        return NULL;

    return *ppuserList;
}                               /* end usm_remove_user_from_list() */

/*
 * usm_remove_user(): finds and removes a user from a list
 */
struct usmUser *
usm_remove_user(struct usmUser *user)
{
    return usm_remove_user_from_list(user, &userList);
}

/*
 * usm_free_user():  calls free() on all needed parts of struct usmUser and
 * the user himself.
 *
 * Note: This should *not* be called on an object in a list (IE,
 * remove it from the list first, and set next and prev to NULL), but
 * will try to reconnect the list pieces again if it is called this
 * way.  If called on the head of the list, the entire list will be
 * lost.
 */
struct usmUser *
usm_free_user(struct usmUser *user)
{
    if (user == NULL)
        return NULL;

    SNMP_FREE(user->engineID);
    SNMP_FREE(user->name);
    SNMP_FREE(user->secName);
    SNMP_FREE(user->cloneFrom);
    SNMP_FREE(user->userPublicString);
    SNMP_FREE(user->authProtocol);
    SNMP_FREE(user->privProtocol);

    if (user->authKey != NULL) {
        SNMP_ZERO(user->authKey, user->authKeyLen);
        SNMP_FREE(user->authKey);
    }

    if (user->privKey != NULL) {
        SNMP_ZERO(user->privKey, user->privKeyLen);
        SNMP_FREE(user->privKey);
    }

    if (user->authKeyKu != NULL) {
        SNMP_ZERO(user->authKeyKu, user->authKeyKuLen);
        SNMP_FREE(user->authKeyKu);
    }

    if (user->privKeyKu != NULL) {
        SNMP_ZERO(user->privKeyKu, user->privKeyKuLen);
        SNMP_FREE(user->privKeyKu);
    }

#ifdef NETSNMP_USE_OPENSSL
    if (user->usmDHUserAuthKeyChange)
    {
        DH_free(user->usmDHUserAuthKeyChange);
        user->usmDHUserAuthKeyChange = NULL;
    }

    if (user->usmDHUserPrivKeyChange)
    {
        DH_free(user->usmDHUserPrivKeyChange);
        user->usmDHUserPrivKeyChange = NULL;
    }
#endif

    /*
     * FIX  Why not put this check *first?*
     */
    if (user->prev != NULL && user->prev != (struct usmUser *)-1) {   /* ack, this shouldn't happen */
        user->prev->next = user->next;
    }
    if (user->next != NULL && user->next != (struct usmUser *)-1) {
        user->next->prev = user->prev;
        if (user->prev != NULL) /* ack this is really bad, because it means
                                 * * we'll loose the head of some structure tree */
            DEBUGMSGTL(("usm",
                        "Severe: Asked to free the head of a usmUser tree somewhere."));
    }


    SNMP_ZERO(user, sizeof(*user));
    SNMP_FREE(user);

    return NULL;                /* for convenience to returns from calling functions */

}                               /* end usm_free_user() */

/*******************************************************************-o-******
 * asn_predict_int_length
 *
 * Parameters:
 *	type	(UNUSED)
 *	number
 *	len
 *      
 * Returns:
 *	Number of bytes necessary to store the ASN.1 encoded value of 'number'.
 *
 *
 *	This gives the number of bytes that the ASN.1 encoder (in asn1.c) will
 *	use to encode a particular integer value.
 *
 *	Returns the length of the integer -- NOT THE HEADER!
 *
 *	Do this the same way as asn_build_int()...
 */
static int
asn_predict_int_length(int type, long number, size_t len)
{
    register u_long mask;


    if (len != sizeof(long))
        return -1;

    mask = ((u_long) 0x1FF) << ((8 * (sizeof(long) - 1)) - 1);
    /*
     * mask is 0xFF800000 on a big-endian machine 
     */

    while ((((number & mask) == 0) || ((number & mask) == mask))
           && len > 1) {
        len--;
        number <<= 8;
    }

    return len;

}                               /* end asn_predict_length() */

/*******************************************************************-o-******
 * asn_predict_length
 *
 * Parameters:
 *	 type
 *	*ptr
 *	 u_char_len
 *      
 * Returns:
 *	Length in bytes:	1 + <n> + <u_char_len>, where
 *
 *		1		For the ASN.1 type.
 *		<n>		# of bytes to store length of data.
 *		<u_char_len>	Length of data associated with ASN.1 type.
 *
 *	This gives the number of bytes that the ASN.1 encoder (in asn1.c) will
 *	use to encode a particular integer value.  This is as broken as the
 *	currently used encoder.
 *
 * XXX	How is <n> chosen, exactly??
 */
static int
asn_predict_length(int type, u_char * ptr, size_t u_char_len)
{

    if (type & ASN_SEQUENCE)
        return 1 + 3 + u_char_len;

    if (type & ASN_INTEGER) {
        u_long          value;
        memcpy(&value, ptr, u_char_len);
        u_char_len = asn_predict_int_length(type, value, u_char_len);
    }

    if (u_char_len < 0x80)
        return 1 + 1 + u_char_len;
    else if (u_char_len < 0xFF)
        return 1 + 2 + u_char_len;
    else
        return 1 + 3 + u_char_len;

}                               /* end asn_predict_length() */

/*******************************************************************-o-******
 * usm_calc_offsets
 *
 * Parameters:
 *	(See list below...)
 *      
 * Returns:
 *	0	On success,
 *	-1	Otherwise.
 *
 *
 *	This routine calculates the offsets into an outgoing message buffer
 *	for the necessary values.  The outgoing buffer will generically
 *	look like this:
 *
 *	SNMPv3 Message
 *	SEQ len[11]
 *		INT len version
 *	Header
 *		SEQ len
 *			INT len MsgID
 *			INT len msgMaxSize
 *			OST len msgFlags (OST = OCTET STRING)
 *			INT len msgSecurityModel
 *	MsgSecurityParameters
 *		[1] OST len[2]
 *			SEQ len[3]
 *				OST len msgAuthoritativeEngineID
 *				INT len msgAuthoritativeEngineBoots
 *				INT len msgAuthoritativeEngineTime
 *				OST len msgUserName
 *				OST len[4] [5] msgAuthenticationParameters
 *				OST len[6] [7] msgPrivacyParameters
 *	MsgData
 *		[8] OST len[9] [10] encryptedPDU
 *		or
 *		[8,10] SEQUENCE len[9] scopedPDU
 *	[12]
 *
 *	The bracketed points will be needed to be identified ([x] is an index
 *	value, len[x] means a length value).  Here is a semantic guide to them:
 *
 *	[1] = globalDataLen (input)
 *	[2] = otstlen
 *	[3] = seq_len
 *	[4] = msgAuthParmLen (may be 0 or 12)
 *	[5] = authParamsOffset
 *	[6] = msgPrivParmLen (may be 0 or 8)
 *	[7] = privParamsOffset
 *	[8] = globalDataLen + msgSecParmLen
 *	[9] = datalen
 *	[10] = dataOffset
 *	[11] = theTotalLength - the length of the header itself
 *	[12] = theTotalLength
 */
static int
usm_calc_offsets(size_t globalDataLen,  /* SNMPv3Message + HeaderData */
                 int secLevel, size_t secEngineIDLen, size_t secNameLen, size_t scopedPduLen,   /* An BER encoded sequence. */
                 u_long engineboots,    /* XXX (asn1.c works in long, not int.) */
                 long engine_time,      /* XXX (asn1.c works in long, not int.) */
                 size_t * theTotalLength,       /* globalDataLen + msgSecurityP. + msgData */
                 size_t * authParamsOffset,     /* Distance to auth bytes.                 */
                 size_t * privParamsOffset,     /* Distance to priv bytes.                 */
                 size_t * dataOffset,   /* Distance to scopedPdu SEQ  -or-  the
                                         *   crypted (data) portion of msgData.    */
                 size_t * datalen,      /* Size of msgData OCTET STRING encoding.  */
                 size_t * msgAuthParmLen,       /* Size of msgAuthenticationParameters.    */
                 size_t * msgPrivParmLen,       /* Size of msgPrivacyParameters.           */
                 size_t * otstlen,      /* Size of msgSecurityP. O.S. encoding.    */
                 size_t * seq_len,      /* Size of msgSecurityP. SEQ data.         */
                 size_t * msgSecParmLen)
{                               /* Size of msgSecurityP. SEQ.              */
    int             engIDlen,   /* Sizes of OCTET STRING and SEQ encodings */
                    engBtlen,   /*   for fields within                     */
                    engTmlen,   /*   msgSecurityParameters portion of      */
                    namelen,    /*   SNMPv3Message.                        */
                    authlen, privlen, ret;

    /*
     * If doing authentication, msgAuthParmLen = 12 else msgAuthParmLen = 0.
     * If doing encryption,     msgPrivParmLen = 8  else msgPrivParmLen = 0.
     */
    *msgAuthParmLen = (secLevel == SNMP_SEC_LEVEL_AUTHNOPRIV
                       || secLevel == SNMP_SEC_LEVEL_AUTHPRIV) ? 12 : 0;

    *msgPrivParmLen = (secLevel == SNMP_SEC_LEVEL_AUTHPRIV) ? 8 : 0;


    /*
     * Calculate lengths.
     */
    if ((engIDlen = asn_predict_length(ASN_OCTET_STR,
                                       NULL, secEngineIDLen)) == -1) {
        return -1;
    }

    if ((engBtlen = asn_predict_length(ASN_INTEGER,
                                       (u_char *) & engineboots,
                                       sizeof(long))) == -1) {
        return -1;
    }

    if ((engTmlen = asn_predict_length(ASN_INTEGER,
                                       (u_char *) & engine_time,
                                       sizeof(long))) == -1) {
        return -1;
    }

    if ((namelen = asn_predict_length(ASN_OCTET_STR,
                                      NULL, secNameLen)) == -1) {
        return -1;
    }

    if ((authlen = asn_predict_length(ASN_OCTET_STR,
                                      NULL, *msgAuthParmLen)) == -1) {
        return -1;
    }

    if ((privlen = asn_predict_length(ASN_OCTET_STR,
                                      NULL, *msgPrivParmLen)) == -1) {
        return -1;
    }

    *seq_len =
        engIDlen + engBtlen + engTmlen + namelen + authlen + privlen;

    if ((ret = asn_predict_length(ASN_SEQUENCE,
                                      NULL, *seq_len)) == -1) {
        return -1;
    }
    *otstlen = (size_t)ret;

    if ((ret = asn_predict_length(ASN_OCTET_STR,
                                      NULL, *otstlen)) == -1) {
        return -1;
    }
    *msgSecParmLen = (size_t)ret;

    *authParamsOffset = globalDataLen + +(*msgSecParmLen - *seq_len)
        + engIDlen + engBtlen + engTmlen + namelen
        + (authlen - *msgAuthParmLen);

    *privParamsOffset = *authParamsOffset + *msgAuthParmLen
        + (privlen - *msgPrivParmLen);


    /*
     * Compute the size of the plaintext.  Round up to account for cipher
     * block size, if necessary.
     *
     * XXX  This is hardwired for 1DES... If scopedPduLen is already
     *      a multiple of 8, then *add* 8 more; otherwise, round up
     *      to the next multiple of 8.
     *
     * FIX  Calculation of encrypted portion of msgData and consequent
     *      setting and sanity checking of theTotalLength, et al. should
     *      occur *after* encryption has taken place.
     */
    if (secLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        scopedPduLen = ROUNDUP8(scopedPduLen);

        if ((ret = asn_predict_length(ASN_OCTET_STR, NULL, scopedPduLen)) == -1) {
            return -1;
        }
        *datalen = (size_t)ret;
    } else {
        *datalen = scopedPduLen;
    }

    *dataOffset = globalDataLen + *msgSecParmLen +
        (*datalen - scopedPduLen);
    *theTotalLength = globalDataLen + *msgSecParmLen + *datalen;

    return 0;

}                               /* end usm_calc_offsets() */

#ifndef NETSNMP_DISABLE_DES
/*******************************************************************-o-******
 * usm_set_salt
 *
 * Parameters:
 *	*iv		  (O)   Buffer to contain IV.
 *	*iv_length	  (O)   Length of iv.
 *	*priv_salt	  (I)   Salt portion of private key.
 *	 priv_salt_length (I)   Length of priv_salt.
 *	*msgSalt	  (I/O) Pointer salt portion of outgoing msg buffer.
 *      
 * Returns:
 *	0	On success,
 *	-1	Otherwise.
 *
 *	Determine the initialization vector for the DES-CBC encryption.
 *	(Cf. RFC 2274, 8.1.1.1.)
 *
 *	iv is defined as the concatenation of engineBoots and the
 *		salt integer.
 *	The salt integer is incremented.
 *	The resulting salt is copied into the msgSalt buffer.
 *	The result of the concatenation is then XORed with the salt
 *		portion of the private key (last 8 bytes).
 *	The IV result is returned individually for further use.
 */
static int
usm_set_salt(u_char * iv,
             size_t * iv_length,
             u_char * priv_salt, size_t priv_salt_length, u_char * msgSalt)
{
    size_t          propersize_salt = BYTESIZE(USM_DES_SALT_LENGTH);
    int             net_boots;
    int             net_salt_int;
    /*
     * net_* should be encoded in network byte order.  XXX  Why?
     */
    int             iindex;


    /*
     * Sanity check.
     */
    if (!iv || !iv_length || !priv_salt || (*iv_length != propersize_salt)
        || (priv_salt_length < propersize_salt)) {
        return -1;
    }


    net_boots = htonl(snmpv3_local_snmpEngineBoots());
    net_salt_int = htonl(salt_integer);

    salt_integer += 1;

    memcpy(iv, &net_boots, propersize_salt / 2);
    memcpy(iv + (propersize_salt / 2), &net_salt_int, propersize_salt / 2);

    if (msgSalt)
        memcpy(msgSalt, iv, propersize_salt);


    /*
     * Turn the salt into an IV: XOR <boots, salt_int> with salt
     * portion of priv_key.
     */
    for (iindex = 0; iindex < (int) propersize_salt; iindex++)
        iv[iindex] ^= priv_salt[iindex];


    return 0;

}                               /* end usm_set_salt() */
#endif

#ifdef HAVE_AES
/*******************************************************************-o-******
 * usm_set_aes_iv
 *
 * Parameters:
 *	*iv		  (O)   Buffer to contain IV.
 *	*iv_length	  (O)   Length of iv.
 *      net_boots         (I)   the network byte order of the authEng boots val
 *      net_time         (I)   the network byte order of the authEng time val
 *      *salt             (O)   A buffer for the outgoing salt (= 8 bytes of iv)
 *      
 * Returns:
 *	0	On success,
 *	-1	Otherwise.
 *
 *	Determine the initialization vector for AES encryption.
 *	(draft-blumenthal-aes-usm-03.txt, 3.1.2.2)
 *
 *	iv is defined as the concatenation of engineBoots, engineTime
  	and a 64 bit salt-integer.
 *	The 64 bit salt integer is incremented.
 *	The resulting salt is copied into the salt buffer.
 *	The IV result is returned individually for further use.
 */
static int
usm_set_aes_iv(u_char * iv,
               size_t * iv_length,
               u_int net_boots,
               u_int net_time,
               u_char * salt)
{
    /*
     * net_* should be encoded in network byte order.
     */
    int             net_salt_int1, net_salt_int2;
#define PROPER_AES_IV_SIZE 64

    /*
     * Sanity check.
     */
    if (!iv || !iv_length) {
        return -1;
    }

    net_salt_int1 = htonl(salt_integer64_1);
    net_salt_int2 = htonl(salt_integer64_2);

    if ((salt_integer64_2 += 1) == 0)
        salt_integer64_2 += 1;
    
    /* XXX: warning: hard coded proper lengths */
    memcpy(iv, &net_boots, 4);
    memcpy(iv+4, &net_time, 4);
    memcpy(iv+8, &net_salt_int1, 4);
    memcpy(iv+12, &net_salt_int2, 4);

    memcpy(salt, iv+8, 8); /* only copy the needed portion */
    return 0;
}                               /* end usm_set_aes_iv() */
#endif /* HAVE_AES */

/*******************************************************************-o-******
 * usm_check_secLevel_vs_protocols
 *
 * Parameters:
 *	 level
 *	*authProtocol
 *	 authProtocolLen
 *	*privProtocol
 *	 privProtocolLen
 *
 * Returns:
 *	0	On success,
 *	1	Otherwise.
 *
 * Same as above but with explicitly named transform types instead of taking
 * from the usmUser structure.
 */
static int
usm_check_secLevel_vs_protocols(int level,
                                const oid * authProtocol,
                                u_int authProtocolLen,
                                const oid * privProtocol,
                                u_int privProtocolLen)
{

    if (level == SNMP_SEC_LEVEL_AUTHPRIV
        &&
        (netsnmp_oid_equals
         (privProtocol, privProtocolLen, usmNoPrivProtocol,
          sizeof(usmNoPrivProtocol) / sizeof(oid)) == 0)) {
        DEBUGMSGTL(("usm", "Level: %d\n", level));
        DEBUGMSGTL(("usm", "Auth Protocol: "));
        DEBUGMSGOID(("usm", authProtocol, authProtocolLen));
        DEBUGMSG(("usm", ", Priv Protocol: "));
        DEBUGMSGOID(("usm", privProtocol, privProtocolLen));
        DEBUGMSG(("usm", "\n"));
        return 1;
    }
    if ((level == SNMP_SEC_LEVEL_AUTHPRIV
         || level == SNMP_SEC_LEVEL_AUTHNOPRIV)
        &&
        (netsnmp_oid_equals
         (authProtocol, authProtocolLen, usmNoAuthProtocol,
          sizeof(usmNoAuthProtocol) / sizeof(oid)) == 0)) {
        DEBUGMSGTL(("usm", "Level: %d\n", level));
        DEBUGMSGTL(("usm", "Auth Protocol: "));
        DEBUGMSGOID(("usm", authProtocol, authProtocolLen));
        DEBUGMSG(("usm", ", Priv Protocol: "));
        DEBUGMSGOID(("usm", privProtocol, privProtocolLen));
        DEBUGMSG(("usm", "\n"));
        return 1;
    }

    return 0;

}                               /* end usm_check_secLevel_vs_protocols() */

/*******************************************************************-o-******
 * usm_generate_out_msg
 *
 * Parameters:
 *	(See list below...)
 *      
 * Returns:
 *	SNMPERR_SUCCESS			On success.
 *	SNMPERR_USM_AUTHENTICATIONFAILURE
 *	SNMPERR_USM_ENCRYPTIONERROR
 *	SNMPERR_USM_GENERICERROR
 *	SNMPERR_USM_UNKNOWNSECURITYNAME
 *	SNMPERR_USM_GENERICERROR
 *	SNMPERR_USM_UNSUPPORTEDSECURITYLEVEL
 *	
 *
 * Generates an outgoing message.
 *
 * XXX	Beware of misnomers!
 */
static int
usm_generate_out_msg(int msgProcModel,  /* (UNUSED) */
                     u_char * globalData,       /* IN */
                     /*
                      * Pointer to msg header data will point to the beginning
                      * * of the entire packet buffer to be transmitted on wire,
                      * * memory will be contiguous with secParams, typically
                      * * this pointer will be passed back as beginning of
                      * * wholeMsg below.  asn seq. length is updated w/ new length.
                      * *
                      * * While this points to a buffer that should be big enough
                      * * for the whole message, only the first two parts
                      * * of the message are completed, namely SNMPv3Message and
                      * * HeaderData.  globalDataLen (next parameter) represents
                      * * the length of these two completed parts.
                      */
                     size_t globalDataLen,      /* IN - Length of msg header data.      */
                     int maxMsgSize,    /* (UNUSED) */
                     int secModel,      /* (UNUSED) */
                     const u_char *secEngineID, /* IN - Pointer snmpEngineID. */
                     size_t secEngineIDLen,     /* IN - SnmpEngineID length.  */
                     const char *secName,     /* IN - Pointer to securityName.*/
                     size_t secNameLen, /* IN - SecurityName length.          */
                     int secLevel,      /* IN - AuthNoPriv, authPriv etc.     */
                     const u_char *scopedPdu, /* IN */
                     /*
                      * Pointer to scopedPdu will be encrypted by USM if needed
                      * * and written to packet buffer immediately following
                      * * securityParameters, entire msg will be authenticated by
                      * * USM if needed.
                      */
                     size_t scopedPduLen,       /* IN - scopedPdu length. */
                     const void *secStateRef, /* IN */
                     /*
                      * secStateRef, pointer to cached info provided only for
                      * * Response, otherwise NULL.
                      */
                     u_char * secParams,        /* OUT */
                     /*
                      * BER encoded securityParameters pointer to offset within
                      * * packet buffer where secParams should be written, the
                      * * entire BER encoded OCTET STRING (including header) is
                      * * written here by USM secParams = globalData +
                      * * globalDataLen.
                      */
                     size_t * secParamsLen,     /* IN/OUT - Len available, len returned. */
                     u_char ** wholeMsg,        /* OUT */
                     /*
                      * Complete authenticated/encrypted message - typically
                      * * the pointer to start of packet buffer provided in
                      * * globalData is returned here, could also be a separate
                      * * buffer.
                      */
                     size_t * wholeMsgLen)
{                               /* IN/OUT - Len available, len returned. */
    size_t          otstlen;
    size_t          seq_len;
    size_t          msgAuthParmLen;
    size_t          msgPrivParmLen;
    size_t          msgSecParmLen;
    size_t          authParamsOffset;
    size_t          privParamsOffset;
    size_t          datalen;
    size_t          dataOffset;
    size_t          theTotalLength;

    u_char         *ptr;
    size_t          ptr_len;
    size_t          remaining;
    size_t          offSet;
    u_int           boots_uint;
    u_int           time_uint;
    long            boots_long;
    long            time_long;

    /*
     * Indirection because secStateRef values override parameters.
     * 
     * None of these are to be free'd - they are either pointing to
     * what's in the secStateRef or to something either in the
     * actual prarmeter list or the user list.
     */

    const char     *theName = NULL;
    u_int           theNameLength = 0;
    const u_char   *theEngineID = NULL;
    u_int           theEngineIDLength = 0;
    u_char         *theAuthKey = NULL;
    u_int           theAuthKeyLength = 0;
    const oid      *theAuthProtocol = NULL;
    u_int           theAuthProtocolLength = 0;
    u_char         *thePrivKey = NULL;
    u_int           thePrivKeyLength = 0;
    const oid      *thePrivProtocol = NULL;
    u_int           thePrivProtocolLength = 0;
    int             theSecLevel = 0;    /* No defined const for bad
                                         * value (other then err).
                                         */

    DEBUGMSGTL(("usm", "USM processing has begun.\n"));

    if (secStateRef != NULL) {
        /*
         * To hush the compiler for now.  XXX 
         */
        const struct usmStateReference *ref = secStateRef;

        theName = ref->usr_name;
        theNameLength = ref->usr_name_length;
        theEngineID = ref->usr_engine_id;
        theEngineIDLength = ref->usr_engine_id_length;

        if (!theEngineIDLength) {
            theEngineID = secEngineID;
            theEngineIDLength = secEngineIDLen;
        }

        theAuthProtocol = ref->usr_auth_protocol;
        theAuthProtocolLength = ref->usr_auth_protocol_length;
        theAuthKey = ref->usr_auth_key;
        theAuthKeyLength = ref->usr_auth_key_length;
        thePrivProtocol = ref->usr_priv_protocol;
        thePrivProtocolLength = ref->usr_priv_protocol_length;
        thePrivKey = ref->usr_priv_key;
        thePrivKeyLength = ref->usr_priv_key_length;
        theSecLevel = ref->usr_sec_level;
    }

    /*
     * Identify the user record.
     */
    else {
        struct usmUser *user;

        /*
         * we do allow an unknown user name for
         * unauthenticated requests. 
         */
        if ((user = usm_get_user(secEngineID, secEngineIDLen, secName))
            == NULL && secLevel != SNMP_SEC_LEVEL_NOAUTH) {
            DEBUGMSGTL(("usm", "Unknown User(%s)\n", secName));
            return SNMPERR_USM_UNKNOWNSECURITYNAME;
        }

        theName = secName;
        theNameLength = secNameLen;
        theEngineID = secEngineID;
        theSecLevel = secLevel;
        theEngineIDLength = secEngineIDLen;
        if (user) {
            theAuthProtocol = user->authProtocol;
            theAuthProtocolLength = user->authProtocolLen;
            theAuthKey = user->authKey;
            theAuthKeyLength = user->authKeyLen;
            thePrivProtocol = user->privProtocol;
            thePrivProtocolLength = user->privProtocolLen;
            thePrivKey = user->privKey;
            thePrivKeyLength = user->privKeyLen;
        } else {
            /*
             * unknown users can not do authentication (obviously) 
             */
            theAuthProtocol = usmNoAuthProtocol;
            theAuthProtocolLength =
                sizeof(usmNoAuthProtocol) / sizeof(oid);
            theAuthKey = NULL;
            theAuthKeyLength = 0;
            thePrivProtocol = usmNoPrivProtocol;
            thePrivProtocolLength =
                sizeof(usmNoPrivProtocol) / sizeof(oid);
            thePrivKey = NULL;
            thePrivKeyLength = 0;
        }
    }                           /* endif -- secStateRef==NULL */


    /*
     * From here to the end of the function, avoid reference to
     * secName, secEngineID, secLevel, and associated lengths.
     */


    /*
     * Check to see if the user can use the requested sec services.
     */
    if (usm_check_secLevel_vs_protocols(theSecLevel,
                                        theAuthProtocol,
                                        theAuthProtocolLength,
                                        thePrivProtocol,
                                        thePrivProtocolLength) == 1) {
        DEBUGMSGTL(("usm", "Unsupported Security Level (%d)\n",
                    theSecLevel));
        return SNMPERR_USM_UNSUPPORTEDSECURITYLEVEL;
    }


    /*
     * Retrieve the engine information.
     *
     * XXX  No error is declared in the EoP when sending messages to
     *      unknown engines, processing continues w/ boots/time == (0,0).
     */
    if (get_enginetime(theEngineID, theEngineIDLength,
                       &boots_uint, &time_uint, FALSE) == -1) {
        DEBUGMSGTL(("usm", "%s\n", "Failed to find engine data."));
    }

    boots_long = boots_uint;
    time_long = time_uint;


    /*
     * Set up the Offsets.
     */
    if (usm_calc_offsets(globalDataLen, theSecLevel, theEngineIDLength,
                         theNameLength, scopedPduLen, boots_long,
                         time_long, &theTotalLength, &authParamsOffset,
                         &privParamsOffset, &dataOffset, &datalen,
                         &msgAuthParmLen, &msgPrivParmLen, &otstlen,
                         &seq_len, &msgSecParmLen) == -1) {
        DEBUGMSGTL(("usm", "Failed calculating offsets.\n"));
        return SNMPERR_USM_GENERICERROR;
    }

    /*
     * So, we have the offsets for the three parts that need to be
     * determined, and an overall length.  Now we need to make
     * sure all of this would fit in the outgoing buffer, and
     * whether or not we need to make a new buffer, etc.
     */


    /*
     * Set wholeMsg as a pointer to globalData.  Sanity check for
     * the proper size.
     * 
     * Mark workspace in the message with bytes of all 1's to make it
     * easier to find mistakes in raw message dumps.
     */
    ptr = *wholeMsg = globalData;
    if (theTotalLength > *wholeMsgLen) {
        DEBUGMSGTL(("usm", "Message won't fit in buffer.\n"));
        return SNMPERR_USM_GENERICERROR;
    }

    ptr_len = *wholeMsgLen = theTotalLength;

#ifdef NETSNMP_ENABLE_TESTING_CODE
    memset(&ptr[globalDataLen], 0xFF, theTotalLength - globalDataLen);
#endif                          /* NETSNMP_ENABLE_TESTING_CODE */

    /*
     * Do the encryption.
     */
    if (theSecLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        size_t          encrypted_length = theTotalLength - dataOffset;
        size_t          salt_length = BYTESIZE(USM_MAX_SALT_LENGTH);
        u_char          salt[BYTESIZE(USM_MAX_SALT_LENGTH)];
        int             priv_type = sc_get_privtype(thePrivProtocol,
                                                    thePrivProtocolLength);
#ifdef HAVE_AES
        if (USM_CREATE_USER_PRIV_AES == (priv_type & USM_PRIV_MASK_ALG)) {
            if (!thePrivKey ||
                usm_set_aes_iv(salt, &salt_length,
                               htonl(boots_uint), htonl(time_uint),
                               &ptr[privParamsOffset]) == -1) {
                DEBUGMSGTL(("usm", "Can't set AES iv.\n"));
                return SNMPERR_USM_GENERICERROR;
            }
        }
#endif
#ifndef NETSNMP_DISABLE_DES
        /*
         * XXX  Hardwired to seek into a 1DES private key!
         */
        if (USM_CREATE_USER_PRIV_DES == (priv_type & USM_PRIV_MASK_ALG)) {
            if (!thePrivKey ||
                (usm_set_salt(salt, &salt_length,
                              thePrivKey + 8, thePrivKeyLength - 8,
                              &ptr[privParamsOffset])
                 == -1)) {
                DEBUGMSGTL(("usm", "Can't set DES-CBC salt.\n"));
                return SNMPERR_USM_GENERICERROR;
            }
        }
#endif

        if (sc_encrypt(thePrivProtocol, thePrivProtocolLength,
                       thePrivKey, thePrivKeyLength,
                       salt, salt_length,
                       scopedPdu, scopedPduLen,
                       &ptr[dataOffset], &encrypted_length)
            != SNMP_ERR_NOERROR) {
            DEBUGMSGTL(("usm", "encryption error.\n"));
            return SNMPERR_USM_ENCRYPTIONERROR;
        }
#ifdef NETSNMP_ENABLE_TESTING_CODE
        if (debug_is_token_registered("usm/dump") == SNMPERR_SUCCESS) {
            dump_chunk("usm/dump", "This data was encrypted:",
                       scopedPdu, scopedPduLen);
            dump_chunk("usm/dump", "salt + Encrypted form:",
                       salt, salt_length);
            dump_chunk("usm/dump", NULL,
                       &ptr[dataOffset], encrypted_length);
            dump_chunk("usm/dump", "*wholeMsg:",
                       *wholeMsg, theTotalLength);
        }
#endif


        ptr = *wholeMsg;
        ptr_len = *wholeMsgLen = theTotalLength;


        /*
         * XXX  Sanity check for salt length should be moved up
         *      under usm_calc_offsets() or tossed.
         */
        if ((encrypted_length != (theTotalLength - dataOffset))
            || (salt_length != msgPrivParmLen)) {
            DEBUGMSGTL(("usm", "encryption length error.\n"));
            return SNMPERR_USM_ENCRYPTIONERROR;
        }

        DEBUGMSGTL(("usm", "Encryption successful.\n"));
    }

    /*
     * No encryption for you!
     */
    else {
        memcpy(&ptr[dataOffset], scopedPdu, scopedPduLen);
    }



    /*
     * Start filling in the other fields (in prep for authentication).
     * 
     * offSet is an octet string header, which is different from all
     * the other headers.
     */
    remaining = ptr_len - globalDataLen;

    offSet = ptr_len - remaining;
    asn_build_header(&ptr[offSet], &remaining,
                     (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                               ASN_OCTET_STR), otstlen);

    offSet = ptr_len - remaining;
    asn_build_sequence(&ptr[offSet], &remaining,
                       (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR), seq_len);

    offSet = ptr_len - remaining;
    DEBUGDUMPHEADER("send", "msgAuthoritativeEngineID");
    asn_build_string(&ptr[offSet], &remaining,
                     (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                               ASN_OCTET_STR), theEngineID,
                     theEngineIDLength);
    DEBUGINDENTLESS();

    offSet = ptr_len - remaining;
    DEBUGDUMPHEADER("send", "msgAuthoritativeEngineBoots");
    asn_build_int(&ptr[offSet], &remaining,
                  (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER),
                  &boots_long, sizeof(long));
    DEBUGINDENTLESS();

    offSet = ptr_len - remaining;
    DEBUGDUMPHEADER("send", "msgAuthoritativeEngineTime");
    asn_build_int(&ptr[offSet], &remaining,
                  (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER),
                  &time_long, sizeof(long));
    DEBUGINDENTLESS();

    offSet = ptr_len - remaining;
    DEBUGDUMPHEADER("send", "msgUserName");
    asn_build_string(&ptr[offSet], &remaining,
                     (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                               ASN_OCTET_STR), (const u_char *) theName,
                     theNameLength);
    DEBUGINDENTLESS();


    /*
     * Note: if there is no authentication being done,
     * msgAuthParmLen is 0, and there is no effect (other than
     * inserting a zero-length header) of the following
     * statements.
     */

    offSet = ptr_len - remaining;
    asn_build_header(&ptr[offSet],
                     &remaining,
                     (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                               ASN_OCTET_STR), msgAuthParmLen);

    if (theSecLevel == SNMP_SEC_LEVEL_AUTHNOPRIV
        || theSecLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        offSet = ptr_len - remaining;
        memset(&ptr[offSet], 0, msgAuthParmLen);
    }

    remaining -= msgAuthParmLen;


    /*
     * Note: if there is no encryption being done, msgPrivParmLen
     * is 0, and there is no effect (other than inserting a
     * zero-length header) of the following statements.
     */

    offSet = ptr_len - remaining;
    asn_build_header(&ptr[offSet],
                     &remaining,
                     (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                               ASN_OCTET_STR), msgPrivParmLen);

    remaining -= msgPrivParmLen;        /* Skipping the IV already there. */


    /*
     * For privacy, need to add the octet string header for it.
     */
    if (theSecLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        offSet = ptr_len - remaining;
        asn_build_header(&ptr[offSet],
                         &remaining,
                         (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                                   ASN_OCTET_STR),
                         theTotalLength - dataOffset);
    }


    /*
     * Adjust overall length and store it as the first SEQ length
     * of the SNMPv3Message.
     *
     * FIX  4 is a magic number!
     */
    remaining = theTotalLength;
    asn_build_sequence(ptr, &remaining,
                       (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR),
                       theTotalLength - 4);


    /*
     * Now, time to consider / do authentication.
     */
    if (theSecLevel == SNMP_SEC_LEVEL_AUTHNOPRIV
        || theSecLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        size_t          temp_sig_len = msgAuthParmLen;
        u_char         *temp_sig = (u_char *) malloc(temp_sig_len);

        if (temp_sig == NULL) {
            DEBUGMSGTL(("usm", "Out of memory.\n"));
            return SNMPERR_USM_GENERICERROR;
        }

        if (sc_generate_keyed_hash(theAuthProtocol, theAuthProtocolLength,
                                   theAuthKey, theAuthKeyLength,
                                   ptr, ptr_len, temp_sig, &temp_sig_len)
            != SNMP_ERR_NOERROR) {
            /*
             * FIX temp_sig_len defined?!
             */
            SNMP_ZERO(temp_sig, temp_sig_len);
            SNMP_FREE(temp_sig);
            DEBUGMSGTL(("usm", "Signing failed.\n"));
            return SNMPERR_USM_AUTHENTICATIONFAILURE;
        }

        if (temp_sig_len != msgAuthParmLen) {
            SNMP_ZERO(temp_sig, temp_sig_len);
            SNMP_FREE(temp_sig);
            DEBUGMSGTL(("usm", "Signing lengths failed.\n"));
            return SNMPERR_USM_AUTHENTICATIONFAILURE;
        }

        memcpy(&ptr[authParamsOffset], temp_sig, msgAuthParmLen);

        SNMP_ZERO(temp_sig, temp_sig_len);
        SNMP_FREE(temp_sig);

    }

    /*
     * endif -- create keyed hash 
     */

    DEBUGMSGTL(("usm", "USM processing completed.\n"));

    return SNMPERR_SUCCESS;

}                               /* end usm_generate_out_msg() */

static int
usm_secmod_generate_out_msg(struct snmp_secmod_outgoing_params *parms)
{
    if (!parms)
        return SNMPERR_GENERR;

    return usm_generate_out_msg(parms->msgProcModel,
                                parms->globalData, parms->globalDataLen,
                                parms->maxMsgSize, parms->secModel,
                                parms->secEngineID, parms->secEngineIDLen,
                                parms->secName, parms->secNameLen,
                                parms->secLevel,
                                parms->scopedPdu, parms->scopedPduLen,
                                parms->secStateRef,
                                parms->secParams, parms->secParamsLen,
                                parms->wholeMsg, parms->wholeMsgLen);
}

#ifdef NETSNMP_USE_REVERSE_ASNENCODING
static int
usm_rgenerate_out_msg(int msgProcModel, /* (UNUSED) */
                      u_char * globalData,      /* IN */
                      /*
                       * points at the msgGlobalData, which is of length given by next 
                       * parameter.  
                       */
                      size_t globalDataLen,     /* IN - Length of msg header data.      */
                      int maxMsgSize,   /* (UNUSED) */
                      int secModel,     /* (UNUSED) */
                      const u_char *secEngineID, /* IN - Pointer snmpEngineID.*/
                      size_t secEngineIDLen,     /* IN - SnmpEngineID length. */
                      const char *secName,    /* IN - Pointer to securityName.*/
                      size_t secNameLen,        /* IN - SecurityName length.  */
                      int secLevel,         /* IN - AuthNoPriv, authPriv etc. */
                      const u_char *scopedPdu,       /* IN */
                      /*
                       * Pointer to scopedPdu will be encrypted by USM if needed
                       * * and written to packet buffer immediately following
                       * * securityParameters, entire msg will be authenticated by
                       * * USM if needed.
                       */
                      size_t scopedPduLen,      /* IN - scopedPdu length. */
                      const void *secStateRef,  /* IN */
                      /*
                       * secStateRef, pointer to cached info provided only for
                       * * Response, otherwise NULL.
                       */
                      u_char ** wholeMsg,       /*  IN/OUT  */
                      /*
                       * Points at the pointer to the packet buffer, which might get extended
                       * if necessary via realloc().  
                       */
                      size_t * wholeMsgLen,     /*  IN/OUT  */
                      /*
                       * Length of the entire packet buffer, **not** the length of the
                       * packet.  
                       */
                      size_t * offset           /*  IN/OUT  */
                      /*
                       * Offset from the end of the packet buffer to the start of the packet,
                       * also known as the packet length.  
                       */
    )
{
    size_t          msgAuthParmLen = 0;
    u_int           boots_uint;
    u_int           time_uint;
    long            boots_long;
    long            time_long;

    /*
     * Indirection because secStateRef values override parameters.
     * 
     * None of these are to be free'd - they are either pointing to
     * what's in the secStateRef or to something either in the
     * actual parameter list or the user list.
     */

    const char     *theName = NULL;
    u_int           theNameLength = 0;
    const u_char   *theEngineID = NULL;
    u_int           theEngineIDLength = 0;
    u_char         *theAuthKey = NULL;
    u_int           theAuthKeyLength = 0;
    const oid      *theAuthProtocol = NULL;
    u_int           theAuthProtocolLength = 0;
    u_char         *thePrivKey = NULL;
    u_int           thePrivKeyLength = 0;
    const oid      *thePrivProtocol = NULL;
    u_int           thePrivProtocolLength = 0;
    int             theSecLevel = 0;    /* No defined const for bad
                                         * value (other then err). */
    size_t          salt_length = 0, save_salt_length = 0;
    u_char          salt[BYTESIZE(USM_MAX_SALT_LENGTH)];
    u_char          authParams[USM_MAX_AUTHSIZE];
    u_char          iv[BYTESIZE(USM_MAX_SALT_LENGTH)];
    size_t          sp_offset = 0, mac_offset = 0;
    int             rc = 0;

    DEBUGMSGTL(("usm", "USM processing has begun (offset %d)\n", (int)*offset));

    if (secStateRef != NULL) {
        /*
         * To hush the compiler for now.  XXX 
         */
        const struct usmStateReference *ref = secStateRef;

        theName = ref->usr_name;
        theNameLength = ref->usr_name_length;
        theEngineID = ref->usr_engine_id;
        theEngineIDLength = ref->usr_engine_id_length;

        if (!theEngineIDLength) {
            theEngineID = secEngineID;
            theEngineIDLength = secEngineIDLen;
        }

        theAuthProtocol = ref->usr_auth_protocol;
        theAuthProtocolLength = ref->usr_auth_protocol_length;
        theAuthKey = ref->usr_auth_key;
        theAuthKeyLength = ref->usr_auth_key_length;
        thePrivProtocol = ref->usr_priv_protocol;
        thePrivProtocolLength = ref->usr_priv_protocol_length;
        thePrivKey = ref->usr_priv_key;
        thePrivKeyLength = ref->usr_priv_key_length;
        theSecLevel = ref->usr_sec_level;
    }

    /*
     * * Identify the user record.
     */
    else {
        struct usmUser *user;

        /*
         * we do allow an unknown user name for
         * unauthenticated requests. 
         */
        if ((user = usm_get_user(secEngineID, secEngineIDLen, secName))
            == NULL && secLevel != SNMP_SEC_LEVEL_NOAUTH) {
            DEBUGMSGTL(("usm", "Unknown User\n"));
            return SNMPERR_USM_UNKNOWNSECURITYNAME;
        }

        theName = secName;
        theNameLength = secNameLen;
        theEngineID = secEngineID;
        theSecLevel = secLevel;
        theEngineIDLength = secEngineIDLen;
        if (user) {
            theAuthProtocol = user->authProtocol;
            theAuthProtocolLength = user->authProtocolLen;
            theAuthKey = user->authKey;
            theAuthKeyLength = user->authKeyLen;
            thePrivProtocol = user->privProtocol;
            thePrivProtocolLength = user->privProtocolLen;
            thePrivKey = user->privKey;
            thePrivKeyLength = user->privKeyLen;
        } else {
            /*
             * unknown users can not do authentication (obviously) 
             */
            theAuthProtocol = usmNoAuthProtocol;
            theAuthProtocolLength =
                sizeof(usmNoAuthProtocol) / sizeof(oid);
            theAuthKey = NULL;
            theAuthKeyLength = 0;
            thePrivProtocol = usmNoPrivProtocol;
            thePrivProtocolLength =
                sizeof(usmNoPrivProtocol) / sizeof(oid);
            thePrivKey = NULL;
            thePrivKeyLength = 0;
        }
    }                           /* endif -- secStateRef==NULL */


    /*
     * From here to the end of the function, avoid reference to
     * secName, secEngineID, secLevel, and associated lengths.
     */


    /*
     * Check to see if the user can use the requested sec services.
     */
    if (usm_check_secLevel_vs_protocols(theSecLevel,
                                        theAuthProtocol,
                                        theAuthProtocolLength,
                                        thePrivProtocol,
                                        thePrivProtocolLength) == 1) {
        DEBUGMSGTL(("usm", "Unsupported Security Level or type (%d)\n",
                    theSecLevel));

        return SNMPERR_USM_UNSUPPORTEDSECURITYLEVEL;
    }


    /*
     * * Retrieve the engine information.
     * *
     * * XXX    No error is declared in the EoP when sending messages to
     * *        unknown engines, processing continues w/ boots/time == (0,0).
     */
    if (get_enginetime(theEngineID, theEngineIDLength,
                       &boots_uint, &time_uint, FALSE) == -1) {
        DEBUGMSGTL(("usm", "%s\n", "Failed to find engine data."));
    }

    boots_long = boots_uint;
    time_long = time_uint;

    if (theSecLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        /*
         * Initially assume that the ciphertext will end up the same size as
         * the plaintext plus some padding.  Really sc_encrypt ought to be able
         * to grow this for us, a la asn_realloc_rbuild_<type> functions, but
         * this will do for now.  
         */
        u_char         *ciphertext = NULL;
        size_t          ciphertextlen = scopedPduLen + 64;
        int             priv_type = sc_get_privtype(thePrivProtocol,
                                                    thePrivProtocolLength);

        if ((ciphertext = (u_char *) malloc(ciphertextlen)) == NULL) {
            DEBUGMSGTL(("usm",
                        "couldn't malloc %d bytes for encrypted PDU\n",
                        (int)ciphertextlen));
            return SNMPERR_MALLOC;
        }

        /*
         * XXX Hardwired to seek into a 1DES private key!  
         */
#ifdef HAVE_AES
        if (USM_CREATE_USER_PRIV_AES == (priv_type & USM_PRIV_MASK_ALG)) {
            salt_length = BYTESIZE(USM_AES_SALT_LENGTH);
            save_salt_length = BYTESIZE(USM_AES_SALT_LENGTH)/2;
            if (!thePrivKey ||
                usm_set_aes_iv(salt, &salt_length,
                               htonl(boots_uint), htonl(time_uint),
                               iv) == -1) {
                DEBUGMSGTL(("usm", "Can't set AES iv.\n"));
                SNMP_FREE(ciphertext);
                return SNMPERR_USM_GENERICERROR;
            }
        } 
#endif
#ifndef NETSNMP_DISABLE_DES
        if (USM_CREATE_USER_PRIV_DES == (priv_type & USM_PRIV_MASK_ALG)) {
            salt_length = BYTESIZE(USM_DES_SALT_LENGTH);
            save_salt_length = BYTESIZE(USM_DES_SALT_LENGTH);
            if (!thePrivKey || (usm_set_salt(salt, &salt_length,
                                             thePrivKey + 8,
                                             thePrivKeyLength - 8,
                                             iv) == -1)) {
                DEBUGMSGTL(("usm", "Can't set DES-CBC salt.\n"));
                SNMP_FREE(ciphertext);
                return SNMPERR_USM_GENERICERROR;
            }
        }
#endif
#ifdef NETSNMP_ENABLE_TESTING_CODE
        if (debug_is_token_registered("usm/dump") == SNMPERR_SUCCESS) {
            dump_chunk("usm/dump", "This data was encrypted:",
                       scopedPdu, scopedPduLen);
        }
#endif

        if (sc_encrypt(thePrivProtocol, thePrivProtocolLength,
                       thePrivKey, thePrivKeyLength,
                       salt, salt_length,
                       scopedPdu, scopedPduLen,
                       ciphertext, &ciphertextlen) != SNMP_ERR_NOERROR) {
            DEBUGMSGTL(("usm", "encryption error.\n"));
            SNMP_FREE(ciphertext);
            return SNMPERR_USM_ENCRYPTIONERROR;
        }

        /*
         * Write the encrypted scopedPdu back into the packet buffer.  
         */

        *offset = 0;
        rc = asn_realloc_rbuild_string(wholeMsg, wholeMsgLen, offset, 1,
                                       (u_char) (ASN_UNIVERSAL |
                                                 ASN_PRIMITIVE |
                                                 ASN_OCTET_STR),
                                       ciphertext, ciphertextlen);
        if (rc == 0) {
            DEBUGMSGTL(("usm", "Encryption failed.\n"));
            SNMP_FREE(ciphertext);
            return SNMPERR_USM_ENCRYPTIONERROR;
        }

#ifdef NETSNMP_ENABLE_TESTING_CODE
        if (debug_is_token_registered("usm/dump") == SNMPERR_SUCCESS) {
            dump_chunk("usm/dump", "salt + Encrypted form: ", salt,
                       salt_length);
            dump_chunk("usm/dump", "wholeMsg:",
                       (*wholeMsg + *wholeMsgLen - *offset), *offset);
        }
#endif

        DEBUGMSGTL(("usm", "Encryption successful.\n"));
        SNMP_FREE(ciphertext);
    } else {
        /*
         * theSecLevel != SNMP_SEC_LEVEL_AUTHPRIV  
         */
    }

    /*
     * Start encoding the msgSecurityParameters.  
     */

    sp_offset = *offset;

    DEBUGDUMPHEADER("send", "msgPrivacyParameters");
    /*
     * msgPrivacyParameters (warning: assumes DES salt).  
     */
    rc = asn_realloc_rbuild_string(wholeMsg, wholeMsgLen, offset, 1,
                                   (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE
                                             | ASN_OCTET_STR),
                                   iv,
                                   save_salt_length);
    DEBUGINDENTLESS();
    if (rc == 0) {
        DEBUGMSGTL(("usm", "building privParams failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    DEBUGDUMPHEADER("send", "msgAuthenticationParameters");
    /*
     * msgAuthenticationParameters.
     */
    if (theSecLevel == SNMP_SEC_LEVEL_AUTHNOPRIV
        || theSecLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        memset(authParams, 0, sizeof(authParams));
        msgAuthParmLen =
            sc_get_auth_maclen(sc_get_authtype(theAuthProtocol,
                                               theAuthProtocolLength));
    }

    rc = asn_realloc_rbuild_string(wholeMsg, wholeMsgLen, offset, 1,
                                   (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE
                                             | ASN_OCTET_STR), authParams,
                                   msgAuthParmLen);
    DEBUGINDENTLESS();
    if (rc == 0) {
        DEBUGMSGTL(("usm", "building authParams failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    /*
     * Remember where to put the actual HMAC we calculate later on.  An
     * encoded OCTET STRING of length USM_MD5_AND_SHA_AUTH_LEN has an ASN.1
     * header of length 2, hence the fudge factor.  This works as long as
     * auth lengths stay < 127.
     */
    mac_offset = *offset - 2;

    /*
     * msgUserName.  
     */
    DEBUGDUMPHEADER("send", "msgUserName");
    rc = asn_realloc_rbuild_string(wholeMsg, wholeMsgLen, offset, 1,
                                   (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE
                                             | ASN_OCTET_STR),
                                   (const u_char *) theName, theNameLength);
    DEBUGINDENTLESS();
    if (rc == 0) {
        DEBUGMSGTL(("usm", "building authParams failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    /*
     * msgAuthoritativeEngineTime.  
     */
    DEBUGDUMPHEADER("send", "msgAuthoritativeEngineTime");
    rc = asn_realloc_rbuild_int(wholeMsg, wholeMsgLen, offset, 1,
                                (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                                          ASN_INTEGER), &time_long,
                                sizeof(long));
    DEBUGINDENTLESS();
    if (rc == 0) {
        DEBUGMSGTL(("usm",
                    "building msgAuthoritativeEngineTime failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    /*
     * msgAuthoritativeEngineBoots.  
     */
    DEBUGDUMPHEADER("send", "msgAuthoritativeEngineBoots");
    rc = asn_realloc_rbuild_int(wholeMsg, wholeMsgLen, offset, 1,
                                (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE |
                                          ASN_INTEGER), &boots_long,
                                sizeof(long));
    DEBUGINDENTLESS();
    if (rc == 0) {
        DEBUGMSGTL(("usm",
                    "building msgAuthoritativeEngineBoots failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    DEBUGDUMPHEADER("send", "msgAuthoritativeEngineID");
    rc = asn_realloc_rbuild_string(wholeMsg, wholeMsgLen, offset, 1,
                                   (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE
                                             | ASN_OCTET_STR), theEngineID,
                                   theEngineIDLength);
    DEBUGINDENTLESS();
    if (rc == 0) {
        DEBUGMSGTL(("usm", "building msgAuthoritativeEngineID failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    /*
     * USM msgSecurityParameters sequence header  
     */
    rc = asn_realloc_rbuild_sequence(wholeMsg, wholeMsgLen, offset, 1,
                                     (u_char) (ASN_SEQUENCE |
                                               ASN_CONSTRUCTOR),
                                     *offset - sp_offset);
    if (rc == 0) {
        DEBUGMSGTL(("usm", "building usm security parameters failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    /*
     * msgSecurityParameters OCTET STRING wrapper.  
     */
    rc = asn_realloc_rbuild_header(wholeMsg, wholeMsgLen, offset, 1,
                                   (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE
                                             | ASN_OCTET_STR),
                                   *offset - sp_offset);

    if (rc == 0) {
        DEBUGMSGTL(("usm", "building msgSecurityParameters failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    /*
     * Copy in the msgGlobalData and msgVersion.  
     */
    while ((*wholeMsgLen - *offset) < globalDataLen) {
        if (!asn_realloc(wholeMsg, wholeMsgLen)) {
            DEBUGMSGTL(("usm", "building global data failed.\n"));
            return SNMPERR_TOO_LONG;
        }
    }

    *offset += globalDataLen;
    memcpy(*wholeMsg + *wholeMsgLen - *offset, globalData, globalDataLen);

    /*
     * Total packet sequence.  
     */
    rc = asn_realloc_rbuild_sequence(wholeMsg, wholeMsgLen, offset, 1,
                                     (u_char) (ASN_SEQUENCE |
                                               ASN_CONSTRUCTOR), *offset);
    if (rc == 0) {
        DEBUGMSGTL(("usm", "building master packet sequence failed.\n"));
        return SNMPERR_TOO_LONG;
    }

    /*
     * Now consider / do authentication.  
     */

    if (theSecLevel == SNMP_SEC_LEVEL_AUTHNOPRIV ||
        theSecLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        size_t          temp_sig_len = msgAuthParmLen;
        u_char         *temp_sig = (u_char *) malloc(temp_sig_len);
        u_char         *proto_msg = *wholeMsg + *wholeMsgLen - *offset;
        size_t          proto_msg_len = *offset;


        if (temp_sig == NULL) {
            DEBUGMSGTL(("usm", "Out of memory.\n"));
            return SNMPERR_USM_GENERICERROR;
        }

        if (sc_generate_keyed_hash(theAuthProtocol, theAuthProtocolLength,
                                   theAuthKey, theAuthKeyLength,
                                   proto_msg, proto_msg_len,
                                   temp_sig, &temp_sig_len)
            != SNMP_ERR_NOERROR) {
            SNMP_FREE(temp_sig);
            DEBUGMSGTL(("usm", "Signing failed.\n"));
            return SNMPERR_USM_AUTHENTICATIONFAILURE;
        }

        if (temp_sig_len != msgAuthParmLen) {
            SNMP_FREE(temp_sig);
            DEBUGMSGTL(("usm", "Signing lengths failed.\n"));
            return SNMPERR_USM_AUTHENTICATIONFAILURE;
        }

        memcpy(*wholeMsg + *wholeMsgLen - mac_offset, temp_sig,
               msgAuthParmLen);
        SNMP_FREE(temp_sig);
    }
    /*
     * endif -- create keyed hash 
     */
    DEBUGMSGTL(("usm", "USM processing completed.\n"));
    return SNMPERR_SUCCESS;
}                               /* end usm_rgenerate_out_msg() */

static int
usm_secmod_rgenerate_out_msg(struct snmp_secmod_outgoing_params *parms)
{
    if (!parms)
        return SNMPERR_GENERR;

    return usm_rgenerate_out_msg(parms->msgProcModel,
                                 parms->globalData, parms->globalDataLen,
                                 parms->maxMsgSize, parms->secModel,
                                 parms->secEngineID, parms->secEngineIDLen,
                                 parms->secName, parms->secNameLen,
                                 parms->secLevel,
                                 parms->scopedPdu, parms->scopedPduLen,
                                 parms->secStateRef,
                                 parms->wholeMsg, parms->wholeMsgLen,
                                 parms->wholeMsgOffset);
}
#endif                          /* */

/*******************************************************************-o-******
 * usm_parse_security_parameters
 *
 * Parameters:
 *	(See list below...)
 *      
 * Returns:
 *	0	On success,
 *	-1	Otherwise.
 *
 *	tab stop 4
 *
 *	Extracts values from the security header and data portions of the
 *	incoming buffer.
 */
static int
usm_parse_security_parameters(u_char * secParams,
                              size_t remaining,
                              u_char * secEngineID,
                              size_t * secEngineIDLen,
                              u_int * boots_uint,
                              u_int * time_uint,
                              char *secName,
                              size_t * secNameLen,
                              u_char * signature,
                              size_t * signature_length,
                              u_char * salt,
                              size_t * salt_length, u_char ** data_ptr)
{
    u_char         *parse_ptr = secParams;
    u_char         *value_ptr;
    u_char         *next_ptr;
    u_char          type_value;

    size_t          octet_string_length = remaining;
    size_t          sequence_length;
    size_t          remaining_bytes;

    long            boots_long;
    long            time_long;

    u_int           origNameLen;


    /*
     * Eat the first octet header.
     */
    if ((value_ptr = asn_parse_sequence(parse_ptr, &octet_string_length,
                                        &type_value,
                                        (ASN_UNIVERSAL | ASN_PRIMITIVE |
                                         ASN_OCTET_STR),
                                        "usm first octet")) == NULL) {
        /*
         * RETURN parse error 
         */ return -1;
    }


    /*
     * Eat the sequence header.
     */
    parse_ptr = value_ptr;
    sequence_length = octet_string_length;

    if ((value_ptr = asn_parse_sequence(parse_ptr, &sequence_length,
                                        &type_value,
                                        (ASN_SEQUENCE | ASN_CONSTRUCTOR),
                                        "usm sequence")) == NULL) {
        /*
         * RETURN parse error 
         */ return -1;
    }


    /*
     * Retrieve the engineID.
     */
    parse_ptr = value_ptr;
    remaining_bytes = sequence_length;

    DEBUGDUMPHEADER("recv", "msgAuthoritativeEngineID");
    if ((next_ptr
         = asn_parse_string(parse_ptr, &remaining_bytes, &type_value,
                            secEngineID, secEngineIDLen)) == NULL) {
        DEBUGINDENTLESS();
        /*
         * RETURN parse error 
         */ return -1;
    }
    DEBUGINDENTLESS();

    if (type_value !=
        (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_OCTET_STR)) {
        /*
         * RETURN parse error 
         */ return -1;
    }


    /*
     * Retrieve the engine boots, notice switch in the way next_ptr and
     * remaining_bytes are used (to accomodate the asn code).
     */
    DEBUGDUMPHEADER("recv", "msgAuthoritativeEngineBoots");
    if ((next_ptr = asn_parse_int(next_ptr, &remaining_bytes, &type_value,
                                  &boots_long, sizeof(long))) == NULL) {
        DEBUGINDENTLESS();
        /*
         * RETURN parse error 
         */ return -1;
    }
    DEBUGINDENTLESS();

    if (type_value !=
        (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER)) {
        DEBUGINDENTLESS();
        /*
         * RETURN parse error 
         */ return -1;
    }

    *boots_uint = (u_int) boots_long;


    /*
     * Retrieve the time value.
     */
    DEBUGDUMPHEADER("recv", "msgAuthoritativeEngineTime");
    if ((next_ptr = asn_parse_int(next_ptr, &remaining_bytes, &type_value,
                                  &time_long, sizeof(long))) == NULL) {
        /*
         * RETURN parse error 
         */ return -1;
    }
    DEBUGINDENTLESS();

    if (type_value !=
        (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER)) {
        /*
         * RETURN parse error 
         */ return -1;
    }

    *time_uint = (u_int) time_long;

    if (*boots_uint > ENGINEBOOT_MAX || *time_uint > ENGINETIME_MAX) {
        return -1;
    }

    /*
     * Retrieve the secName.
     */
    origNameLen = *secNameLen;


    DEBUGDUMPHEADER("recv", "msgUserName");
    if ((next_ptr
         = asn_parse_string(next_ptr, &remaining_bytes, &type_value,
                            (u_char *) secName, secNameLen)) == NULL) {
        DEBUGINDENTLESS();
        /*
         * RETURN parse error 
         */ return -1;
    }
    DEBUGINDENTLESS();

    /*
     * FIX -- doesn't this also indicate a buffer overrun?
     */
    if (origNameLen < *secNameLen + 1) {
        /*
         * RETURN parse error, but it's really a parameter error 
         */
        return -1;
    }

    if (*secNameLen > 32) {
        /*
         * This is a USM-specific limitation over and above the above
         * limitation (which will probably default to the length of an
         * SnmpAdminString, i.e. 255).  See RFC 2574, sec. 2.4.  
         */
        return -1;
    }

    secName[*secNameLen] = '\0';

    if (type_value !=
        (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_OCTET_STR)) {
        /*
         * RETURN parse error 
         */ return -1;
    }


    /*
     * Retrieve the signature and blank it if there.
     */
    DEBUGDUMPHEADER("recv", "msgAuthenticationParameters");
    if ((next_ptr
         = asn_parse_string(next_ptr, &remaining_bytes, &type_value,
                            signature, signature_length)) == NULL) {
        DEBUGINDENTLESS();
        /*
         * RETURN parse error 
         */ return -1;
    }
    DEBUGINDENTLESS();

    if (type_value !=
        (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_OCTET_STR)) {
        /*
         * RETURN parse error 
         */ return -1;
    }

    if (*signature_length != 0) {       /* Blanking for authentication step later */
        memset(next_ptr - (u_long) * signature_length,
               0, *signature_length);
    }


    /*
     * Retrieve the salt.
     *
     * Note that the next ptr is where the data section starts.
     */
    DEBUGDUMPHEADER("recv", "msgPrivacyParameters");
    if ((*data_ptr
         = asn_parse_string(next_ptr, &remaining_bytes, &type_value,
                            salt, salt_length)) == NULL) {
        DEBUGINDENTLESS();
        /*
         * RETURN parse error 
         */ return -2;
    }
    DEBUGINDENTLESS();

    if (type_value !=
        (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_OCTET_STR)) {
        /*
         * RETURN parse error 
         */ return -2;
    }

    return 0;

}                               /* end usm_parse_security_parameters() */




/*******************************************************************-o-******
 * usm_check_and_update_timeliness
 *
 * Parameters:
 *	*secEngineID
 *	 secEngineIDen
 *	 boots_uint
 *	 time_uint
 *	*error
 *      
 * Returns:
 *	0	On success,
 *	-1	Otherwise.
 *	
 *
 * Performs the incoming timeliness checking and setting.
 */
static int
usm_check_and_update_timeliness(u_char * secEngineID,
                                size_t secEngineIDLen,
                                u_int boots_uint,
                                u_int time_uint, int *error)
{
    u_char          myID[USM_MAX_ID_LENGTH];
    u_long          myIDLength =
        snmpv3_get_engineID(myID, USM_MAX_ID_LENGTH);
    u_int           myBoots;
    u_int           myTime;



    if ((myIDLength > USM_MAX_ID_LENGTH) || (myIDLength == 0)) {
        /*
         * We're probably already screwed...buffer overwrite.  XXX? 
         */
        DEBUGMSGTL(("usm", "Buffer overflow.\n"));
        *error = SNMPERR_USM_GENERICERROR;
        return -1;
    }

    myBoots = snmpv3_local_snmpEngineBoots();
    myTime = snmpv3_local_snmpEngineTime();


    /*
     * IF the time involved is local
     *     Make sure  message is inside the time window 
     * ELSE 
     *      IF boots is higher or boots is the same and time is higher
     *              remember this new data
     *      ELSE
     *              IF !(boots same and time within USM_TIME_WINDOW secs)
     *                      Message is too old 
     *              ELSE    
     *                      Message is ok, but don't take time
     *              ENDIF
     *      ENDIF
     * ENDIF
     */

    /*
     * This is a local reference.
     */
    if (secEngineIDLen == myIDLength
        && memcmp(secEngineID, myID, myIDLength) == 0) {
        u_int           time_difference = myTime > time_uint ?
            myTime - time_uint : time_uint - myTime;

        if (boots_uint == ENGINEBOOT_MAX
            || boots_uint != myBoots
            || time_difference > USM_TIME_WINDOW) {
            snmp_increment_statistic(STAT_USMSTATSNOTINTIMEWINDOWS);

            DEBUGMSGTL(("usm",
                        "boot_uint %u myBoots %u time_diff %u => not in time window\n",
                        boots_uint, myBoots, time_difference));
            *error = SNMPERR_USM_NOTINTIMEWINDOW;
            return -1;
        }

        *error = SNMPERR_SUCCESS;
        return 0;
    }

    /*
     * This is a remote reference.
     */
    else {
        u_int           theirBoots, theirTime, theirLastTime;
        u_int           time_difference;

        if (get_enginetime_ex(secEngineID, secEngineIDLen,
                              &theirBoots, &theirTime,
                              &theirLastTime, TRUE)
            != SNMPERR_SUCCESS) {
            DEBUGMSGTL(("usm", "%s\n",
                        "Failed to get remote engine's times."));

            *error = SNMPERR_USM_GENERICERROR;
            return -1;
        }

        time_difference = theirTime > time_uint ?
            theirTime - time_uint : time_uint - theirTime;


        /*
         * XXX  Contrary to the pseudocode:
         *      See if boots is invalid first.
         */
        if (theirBoots == ENGINEBOOT_MAX || theirBoots > boots_uint) {
            DEBUGMSGTL(("usm", "%s\n", "Remote boot count invalid."));

            *error = SNMPERR_USM_NOTINTIMEWINDOW;
            return -1;
        }


        /*
         * Boots is ok, see if the boots is the same but the time
         * is old.
         */
        if (theirBoots == boots_uint && time_uint < theirLastTime) {
            if (time_difference > USM_TIME_WINDOW) {
                DEBUGMSGTL(("usm", "%s\n", "Message too old."));
                *error = SNMPERR_USM_NOTINTIMEWINDOW;
                return -1;
            }

            else {              /* Old, but acceptable */

                *error = SNMPERR_SUCCESS;
                return 0;
            }
        }


        /*
         * Message is ok, either boots has been advanced, or
         * time is greater than before with the same boots.
         */

        if (set_enginetime(secEngineID, secEngineIDLen,
                           boots_uint, time_uint, TRUE)
            != SNMPERR_SUCCESS) {
            DEBUGMSGTL(("usm", "%s\n",
                        "Failed updating remote boot/time."));
            *error = SNMPERR_USM_GENERICERROR;
            return -1;
        }

        *error = SNMPERR_SUCCESS;
        return 0;               /* Fresh message and time updated */

    }                           /* endif -- local or remote time reference. */


}                               /* end usm_check_and_update_timeliness() */

/*******************************************************************-o-******
 * usm_check_secLevel
 *
 * Parameters:
 *	 level
 *	*user
 *      
 * Returns:
 *	0	On success,
 *	-1	Otherwise.
 *
 * Checks that a given security level is valid for a given user.
 */
static int
usm_check_secLevel(int level, struct usmUser *user)
{

    if (user->userStatus != RS_ACTIVE)
        return -1;

    DEBUGMSGTL(("comparex", "Comparing: %" NETSNMP_PRIo "u %" NETSNMP_PRIo "u ",
                usmNoPrivProtocol[0], usmNoPrivProtocol[1]));
    DEBUGMSGOID(("comparex", usmNoPrivProtocol,
                 sizeof(usmNoPrivProtocol) / sizeof(oid)));
    DEBUGMSG(("comparex", "\n"));
    if (level == SNMP_SEC_LEVEL_AUTHPRIV
        && (netsnmp_oid_equals(user->privProtocol, user->privProtocolLen,
                             usmNoPrivProtocol,
                             sizeof(usmNoPrivProtocol) / sizeof(oid)) ==
            0)) {
        DEBUGMSGTL(("usm", "Level: %d\n", level));
        DEBUGMSGTL(("usm", "User (%s) Auth Protocol: ", user->name));
        DEBUGMSGOID(("usm", user->authProtocol, user->authProtocolLen));
        DEBUGMSG(("usm", ", User Priv Protocol: "));
        DEBUGMSGOID(("usm", user->privProtocol, user->privProtocolLen));
        DEBUGMSG(("usm", "\n"));
        return 1;
    }
    if ((level == SNMP_SEC_LEVEL_AUTHPRIV
         || level == SNMP_SEC_LEVEL_AUTHNOPRIV)
        &&
        (netsnmp_oid_equals
         (user->authProtocol, user->authProtocolLen, usmNoAuthProtocol,
          sizeof(usmNoAuthProtocol) / sizeof(oid)) == 0)) {
        DEBUGMSGTL(("usm", "Level: %d\n", level));
        DEBUGMSGTL(("usm", "User (%s) Auth Protocol: ", user->name));
        DEBUGMSGOID(("usm", user->authProtocol, user->authProtocolLen));
        DEBUGMSG(("usm", ", User Priv Protocol: "));
        DEBUGMSGOID(("usm", user->privProtocol, user->privProtocolLen));
        DEBUGMSG(("usm", "\n"));
        return 1;
    }

    return 0;
}                               /* end usm_check_secLevel() */

/*******************************************************************-o-******
 * usm_process_in_msg
 *
 * Parameters:
 *	(See list below...)
 *      
 * Returns:
 *	SNMPERR_SUCCESS			On success.
 *	SNMPERR_USM_AUTHENTICATIONFAILURE
 *	SNMPERR_USM_DECRYPTIONERROR
 *	SNMPERR_USM_GENERICERROR
 *	SNMPERR_USM_PARSEERROR
 *	SNMPERR_USM_UNKNOWNENGINEID
 *	SNMPERR_USM_PARSEERROR
 *	SNMPERR_USM_UNKNOWNSECURITYNAME
 *	SNMPERR_USM_UNSUPPORTEDSECURITYLEVEL
 *
 *
 * ASSUMES size of decrypt_buf will always be >= size of encrypted sPDU.
 */
static int
usm_process_in_msg(int msgProcModel,    /* (UNUSED) */
                   size_t maxMsgSize,   /* IN     - Used to calc maxSizeResponse.  */
                   u_char * secParams,  /* IN     - BER encoded securityParameters. */
                   int secModel,        /* (UNUSED) */
                   int secLevel,        /* IN     - AuthNoPriv, authPriv etc.      */
                   u_char * wholeMsg,   /* IN     - Original v3 message.           */
                   size_t wholeMsgLen,  /* IN     - Msg length.                    */
                   u_char * secEngineID,        /* OUT    - Pointer snmpEngineID.          */
                   size_t * secEngineIDLen,     /* IN/OUT - Len available, len returned.   */
                   /*
                    * NOTE: Memory provided by caller.      
                    */
                   char *secName,       /* OUT    - Pointer to securityName.       */
                   size_t * secNameLen, /* IN/OUT - Len available, len returned.   */
                   u_char ** scopedPdu, /* OUT    - Pointer to plaintext scopedPdu. */
                   size_t * scopedPduLen,       /* IN/OUT - Len available, len returned.   */
                   size_t * maxSizeResponse,    /* OUT    - Max size of Response PDU.      */
                   void **secStateRf,   /* OUT    - Ref to security state.         */
                   netsnmp_session * sess,      /* IN     - session which got the message  */
                   u_char msg_flags)
{                               /* IN     - v3 Message flags.              */
    size_t          remaining = wholeMsgLen - (u_int)
        ((u_long) * secParams - (u_long) * wholeMsg);
    u_int           boots_uint;
    u_int           time_uint;
#ifdef HAVE_AES
    u_int           net_boots, net_time;
#endif
#ifndef NETSNMP_DISABLE_DES
    int             i;
#endif
    u_char          signature[USM_MAX_AUTHSIZE];
    size_t          signature_length = USM_MAX_AUTHSIZE;
    u_char          salt[BYTESIZE(USM_MAX_SALT_LENGTH)];
    size_t          salt_length = BYTESIZE(USM_MAX_SALT_LENGTH);
    u_char          iv[BYTESIZE(USM_MAX_SALT_LENGTH)];
    u_int           iv_length = BYTESIZE(USM_MAX_SALT_LENGTH);
    u_char         *data_ptr;
    u_char         *value_ptr;
    u_char          type_value;
    u_char         *end_of_overhead = NULL;
    int             error;
    int             rc = 0;
    struct usmStateReference **secStateRef =
        (struct usmStateReference **) secStateRf;

    struct usmUser *user;


    DEBUGMSGTL(("usm", "USM processing begun...\n"));

    netsnmp_assert(secStateRef);

    usm_free_usmStateReference(*secStateRef);
    *secStateRef = usm_malloc_usmStateReference();
    if (*secStateRef == NULL) {
        DEBUGMSGTL(("usm", "Out of memory.\n"));
        return SNMPERR_USM_GENERICERROR;
    }

    /*
     * Make sure the *secParms is an OCTET STRING.
     * Extract the user name, engine ID, and security level.
     */
    if ((rc = usm_parse_security_parameters(secParams, remaining,
                                            secEngineID, secEngineIDLen,
                                            &boots_uint, &time_uint,
                                            secName, secNameLen,
                                            signature, &signature_length,
                                            salt, &salt_length,
                                            &data_ptr)) < 0) {
        DEBUGMSGTL(("usm", "Parsing failed (rc %d).\n", rc));
        if (rc == -2) {
            /*
             * This indicates a decryptionError.  
             */
            snmp_increment_statistic(STAT_USMSTATSDECRYPTIONERRORS);
            error = SNMPERR_USM_DECRYPTIONERROR;
        } else {
            snmp_increment_statistic(STAT_SNMPINASNPARSEERRS);
            error = SNMPERR_USM_PARSEERROR;
        }
        goto err;
    }

    /*
     * RFC 2574 section 8.3.2
     * 1)  If the privParameters field is not an 8-octet OCTET STRING,
     * then an error indication (decryptionError) is returned to the
     * calling module.
     */
    if ((secLevel == SNMP_SEC_LEVEL_AUTHPRIV) && (salt_length != 8)) {
        snmp_increment_statistic(STAT_USMSTATSDECRYPTIONERRORS);
        error = SNMPERR_USM_DECRYPTIONERROR;
        goto err;
    }

    if (secLevel != SNMP_SEC_LEVEL_AUTHPRIV) {
        /*
         * pull these out now so reports can use them 
         */
        *scopedPdu = data_ptr;
        *scopedPduLen = wholeMsgLen - (data_ptr - wholeMsg);
        end_of_overhead = data_ptr;
    }

    /*
     * Cache the name, engine ID, and security level,
     * * per step 2 (section 3.2)
     */
    if (usm_set_usmStateReference_name
        (*secStateRef, secName, *secNameLen) == -1) {
        DEBUGMSGTL(("usm", "%s\n", "Couldn't cache name."));
        error = SNMPERR_USM_GENERICERROR;
        goto err;
    }

    if (usm_set_usmStateReference_engine_id
        (*secStateRef, secEngineID, *secEngineIDLen) == -1) {
        DEBUGMSGTL(("usm", "%s\n", "Couldn't cache engine id."));
        error = SNMPERR_USM_GENERICERROR;
        goto err;
    }

    if (usm_set_usmStateReference_sec_level(*secStateRef, secLevel) ==
        -1) {
        DEBUGMSGTL(("usm", "%s\n", "Couldn't cache security level."));
        error = SNMPERR_USM_GENERICERROR;
        goto err;
    }

    /*
     * Locate the engine ID record.
     * If it is unknown, then either create one or note this as an error.
     */
    if ((sess && (sess->isAuthoritative == SNMP_SESS_AUTHORITATIVE ||
                  (sess->isAuthoritative == SNMP_SESS_UNKNOWNAUTH &&
                   (msg_flags & SNMP_MSG_FLAG_RPRT_BIT)))) ||
        (!sess && (msg_flags & SNMP_MSG_FLAG_RPRT_BIT))) {
        if (ISENGINEKNOWN(secEngineID, *secEngineIDLen) == FALSE) {
            DEBUGMSGTL(("usm", "Unknown Engine ID.\n"));
            snmp_increment_statistic(STAT_USMSTATSUNKNOWNENGINEIDS);
            error = SNMPERR_USM_UNKNOWNENGINEID;
            goto err;
        }
    } else {
        if (ENSURE_ENGINE_RECORD(secEngineID, *secEngineIDLen)
            != SNMPERR_SUCCESS) {
            DEBUGMSGTL(("usm", "%s\n", "Couldn't ensure engine record."));
            error = SNMPERR_USM_GENERICERROR;
            goto err;
        }

    }


    /*
     * Locate the User record.
     * If the user/engine ID is unknown, report this as an error.
     */
    if ((user = usm_get_user_from_list(secEngineID, *secEngineIDLen,
                                       secName, userList,
                                       (((sess && sess->isAuthoritative ==
                                          SNMP_SESS_AUTHORITATIVE) ||
                                         (!sess)) ? 0 : 1)))
        == NULL) {
        DEBUGMSGTL(("usm", "Unknown User(%s)\n", secName));
        snmp_increment_statistic(STAT_USMSTATSUNKNOWNUSERNAMES);
        error = SNMPERR_USM_UNKNOWNSECURITYNAME;
        goto err;
    }

    /* ensure the user is active */
    if (user->userStatus != RS_ACTIVE) {
        DEBUGMSGTL(("usm", "Attempt to use an inactive user.\n"));
        error = SNMPERR_USM_UNKNOWNSECURITYNAME;
        goto err;
    }

    /*
     * Make sure the security level is appropriate.
     */

    rc = usm_check_secLevel(secLevel, user);
    if (1 == rc) {
        DEBUGMSGTL(("usm", "Unsupported Security Level (%d).\n",
                    secLevel));
        snmp_increment_statistic(STAT_USMSTATSUNSUPPORTEDSECLEVELS);
        error = SNMPERR_USM_UNSUPPORTEDSECURITYLEVEL;
        goto err;
    } else if (rc != 0) {
        DEBUGMSGTL(("usm", "Unknown issue.\n"));
        error = SNMPERR_USM_GENERICERROR;
        goto err;
    }

    /*
     * Check the authentication credentials of the message.
     */
    if (secLevel == SNMP_SEC_LEVEL_AUTHNOPRIV
        || secLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        if (sc_check_keyed_hash(user->authProtocol, user->authProtocolLen,
                                user->authKey, user->authKeyLen,
                                wholeMsg, wholeMsgLen,
                                signature, signature_length)
            != SNMP_ERR_NOERROR) {
            DEBUGMSGTL(("usm", "Verification failed.\n"));
            snmp_increment_statistic(STAT_USMSTATSWRONGDIGESTS);
	    snmp_log(LOG_WARNING, "Authentication failed for %s\n",
				user->name);
            error = SNMPERR_USM_AUTHENTICATIONFAILURE;
            goto err;
        }

        DEBUGMSGTL(("usm", "Verification succeeded.\n"));
    }


    /*
     * Steps 10-11  user is already set - relocated before timeliness 
     * check in case it fails - still save user data for response.
     *
     * Cache the keys and protocol oids, per step 11 (s3.2).
     */
    if (usm_set_usmStateReference_auth_protocol(*secStateRef,
                                                user->authProtocol,
                                                user->
                                                authProtocolLen) == -1) {
        DEBUGMSGTL(("usm", "%s\n",
                    "Couldn't cache authentication protocol."));
        error = SNMPERR_USM_GENERICERROR;
        goto err;
    }

    if (usm_set_usmStateReference_auth_key(*secStateRef,
                                           user->authKey,
                                           user->authKeyLen) == -1) {
        DEBUGMSGTL(("usm", "%s\n",
                    "Couldn't cache authentication key."));
        error = SNMPERR_USM_GENERICERROR;
        goto err;
    }

    if (usm_set_usmStateReference_priv_protocol(*secStateRef,
                                                user->privProtocol,
                                                user->
                                                privProtocolLen) == -1) {
        DEBUGMSGTL(("usm", "%s\n",
                    "Couldn't cache privacy protocol."));
        error = SNMPERR_USM_GENERICERROR;
        goto err;
    }

    if (usm_set_usmStateReference_priv_key(*secStateRef,
                                           user->privKey,
                                           user->privKeyLen) == -1) {
        DEBUGMSGTL(("usm", "%s\n", "Couldn't cache privacy key."));
        error = SNMPERR_USM_GENERICERROR;
        goto err;
    }


    /*
     * Perform the timeliness/time manager functions.
     */
    if (secLevel == SNMP_SEC_LEVEL_AUTHNOPRIV
        || secLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        if (usm_check_and_update_timeliness(secEngineID, *secEngineIDLen,
                                            boots_uint, time_uint,
                                            &error) == -1) {
            goto err;
        }
    }
#ifdef							LCD_TIME_SYNC_OPT
    /*
     * Cache the unauthenticated time to use in case we don't have
     * anything better - this guess will be no worse than (0,0)
     * that we normally use.
     */
    else {
        set_enginetime(secEngineID, *secEngineIDLen,
                       boots_uint, time_uint, FALSE);
    }
#endif                          /* LCD_TIME_SYNC_OPT */


    /*
     * If needed, decrypt the scoped PDU.
     */
    if (secLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
        int priv_type = sc_get_privtype(user->privProtocol,
                                        user->privProtocolLen);
        remaining = wholeMsgLen - (data_ptr - wholeMsg);

        if ((value_ptr = asn_parse_sequence(data_ptr, &remaining,
                                            &type_value,
                                            (ASN_UNIVERSAL | ASN_PRIMITIVE
                                             | ASN_OCTET_STR),
                                            "encrypted sPDU")) == NULL) {
            DEBUGMSGTL(("usm", "%s\n",
                        "Failed while parsing encrypted sPDU."));
            snmp_increment_statistic(STAT_SNMPINASNPARSEERRS);
            usm_free_usmStateReference(*secStateRef);
            *secStateRef = NULL;
            error = SNMPERR_USM_PARSEERROR;
            goto err;
        }

#ifndef NETSNMP_DISABLE_DES
        if (USM_CREATE_USER_PRIV_DES == (priv_type & USM_PRIV_MASK_ALG)) {
            /*
             * From RFC2574:
             * 
             * "Before decryption, the encrypted data length is verified.
             * If the length of the OCTET STRING to be decrypted is not
             * an integral multiple of 8 octets, the decryption process
             * is halted and an appropriate exception noted."  
             */

            if (remaining % 8 != 0) {
                DEBUGMSGTL(("usm",
                            "Ciphertext is %lu bytes, not an integer multiple of 8 (rem %lu)\n",
                            (unsigned long)remaining, (unsigned long)remaining % 8));
                snmp_increment_statistic(STAT_USMSTATSDECRYPTIONERRORS);
                usm_free_usmStateReference(*secStateRef);
                *secStateRef = NULL;
                error = SNMPERR_USM_DECRYPTIONERROR;
                goto err;
            }

            end_of_overhead = value_ptr;

            if ( !user->privKey ) {
                DEBUGMSGTL(("usm", "No privacy pass phrase for %s\n", user->secName));
                snmp_increment_statistic(STAT_USMSTATSDECRYPTIONERRORS);
                usm_free_usmStateReference(*secStateRef);
                *secStateRef = NULL;
                error = SNMPERR_USM_DECRYPTIONERROR;
                goto err;
            }

            /*
             * XOR the salt with the last (iv_length) bytes
             * of the priv_key to obtain the IV.
             */
            iv_length = BYTESIZE(USM_DES_SALT_LENGTH);
            for (i = 0; i < (int) iv_length; i++)
                iv[i] = salt[i] ^ user->privKey[iv_length + i];
        }
#endif
#ifdef HAVE_AES
        if (USM_CREATE_USER_PRIV_AES == (priv_type & USM_PRIV_MASK_ALG)) {
            iv_length = BYTESIZE(USM_AES_SALT_LENGTH);
            net_boots = ntohl(boots_uint);
            net_time = ntohl(time_uint);
            memcpy(iv, &net_boots, 4);
            memcpy(iv+4, &net_time, 4);
            memcpy(iv+8, salt, salt_length);
        }
#endif

#ifdef NETSNMP_ENABLE_TESTING_CODE
        if (debug_is_token_registered("usm/dump") == SNMPERR_SUCCESS) {
            dump_chunk("usm/dump", "Cypher Text", value_ptr, remaining);
            dump_chunk("usm/dump", "salt + Encrypted form:",
                       salt, salt_length);
            dump_chunk("usm/dump", "IV + Encrypted form:", iv, iv_length);
        }
#endif
        if (sc_decrypt(user->privProtocol, user->privProtocolLen,
                       user->privKey, user->privKeyLen,
                       iv, iv_length,
                       value_ptr, remaining, *scopedPdu, scopedPduLen)
            != SNMP_ERR_NOERROR) {
            DEBUGMSGTL(("usm", "%s\n", "Failed decryption."));
            snmp_increment_statistic(STAT_USMSTATSDECRYPTIONERRORS);
            error = SNMPERR_USM_DECRYPTIONERROR;
            goto err;
        }
#ifdef NETSNMP_ENABLE_TESTING_CODE
        if (debug_is_token_registered("usm/dump") == SNMPERR_SUCCESS) {
            dump_chunk("usm/dump", "Decrypted chunk:",
                       *scopedPdu, *scopedPduLen);
        }
#endif
    }
    /*
     * sPDU is plaintext.
     */
    else {
        *scopedPdu = data_ptr;
        *scopedPduLen = wholeMsgLen - (data_ptr - wholeMsg);
        end_of_overhead = data_ptr;

    }                           /* endif -- PDU decryption */


    /*
     * Calculate the biggest sPDU for the response (i.e., whole - ovrhd).
     *
     * FIX  Correct? 
     */
    *maxSizeResponse = maxMsgSize - (end_of_overhead - wholeMsg);


    DEBUGMSGTL(("usm", "USM processing completed.\n"));

    return SNMPERR_SUCCESS;

err:
    usm_free_usmStateReference(*secStateRef);
    *secStateRef = NULL;
    netsnmp_assert(error != SNMPERR_SUCCESS);
    return error;
}                               /* end usm_process_in_msg() */

static int
usm_secmod_process_in_msg(struct snmp_secmod_incoming_params *parms)
{
    if (!parms)
        return SNMPERR_GENERR;

    return usm_process_in_msg(parms->msgProcModel,
                              parms->maxMsgSize,
                              parms->secParams,
                              parms->secModel,
                              parms->secLevel,
                              parms->wholeMsg,
                              parms->wholeMsgLen,
                              parms->secEngineID,
                              parms->secEngineIDLen,
                              parms->secName,
                              parms->secNameLen,
                              parms->scopedPdu,
                              parms->scopedPduLen,
                              parms->maxSizeResponse,
                              parms->secStateRef,
                              parms->sess, parms->msg_flags);
}

static void
usm_handle_report(struct session_list *slp,
                  netsnmp_transport *transport, netsnmp_session *session,
                  int result, netsnmp_pdu *pdu)
{
    /*
     * handle reportable errors 
     */

    /* this will get in our way */
    usm_free_usmStateReference(pdu->securityStateRef);
    pdu->securityStateRef = NULL;

    switch (result) {
    case SNMPERR_USM_AUTHENTICATIONFAILURE:
    {
        int res = session->s_snmp_errno;
        session->s_snmp_errno = result;
        if (session->callback) {
            session->callback(NETSNMP_CALLBACK_OP_RECEIVED_MESSAGE,
                              session, pdu->reqid, pdu,
                              session->callback_magic);
        }
        session->s_snmp_errno = res;
    }  
    /* fallthrough */
    case SNMPERR_USM_UNKNOWNENGINEID:
    case SNMPERR_USM_UNKNOWNSECURITYNAME:
    case SNMPERR_USM_UNSUPPORTEDSECURITYLEVEL:
    case SNMPERR_USM_NOTINTIMEWINDOW:
    case SNMPERR_USM_DECRYPTIONERROR:

        if (SNMP_CMD_CONFIRMED(pdu->command) ||
            (pdu->command == 0
             && (pdu->flags & SNMP_MSG_FLAG_RPRT_BIT))) {
            netsnmp_pdu    *pdu2;
            int             flags = pdu->flags;

            pdu->flags |= UCD_MSG_FLAG_FORCE_PDU_COPY;
            pdu2 = snmp_clone_pdu(pdu);
            pdu->flags = pdu2->flags = flags;
            snmpv3_make_report(pdu2, result);
            if (0 == snmp_sess_send(slp, pdu2)) {
                snmp_free_pdu(pdu2);
                /*
                 * TODO: indicate error 
                 */
            }
        }
        break;
    }       
}

/** utility function to call netsnmp_extend_kul for a usmUser */
int
usm_extend_user_kul(struct usmUser *user, u_int privKeyBufSize)
{
    const netsnmp_priv_alg_info *pai;

    DEBUGMSGTL(("usm", "extending key\n"));

    if (NULL == user) {
        DEBUGMSGTL(("usm", "null user!\n"));
        return SNMPERR_GENERR;
    }

    pai = sc_get_priv_alg_byoid(user->privProtocol, user->privProtocolLen);
    if (NULL == pai) {
        DEBUGMSGTL(("usm", "privProtocol lookup failed!\n"));
        return SNMPERR_GENERR;
    }

    return netsnmp_extend_kul(pai->proper_length, user->authProtocol,
                              user->authProtocolLen, pai->type, user->engineID,
                              user->engineIDLen, &user->privKey,
                              &user->privKeyLen, privKeyBufSize);
}

/* sets up initial default session parameters */
static int
usm_session_init(netsnmp_session *in_session, netsnmp_session *session)
{
    char *cp;
    size_t i;
    
    if (in_session->securityAuthProtoLen > 0) {
        session->securityAuthProto =
            snmp_duplicate_objid(in_session->securityAuthProto,
                                 in_session->securityAuthProtoLen);
        if (session->securityAuthProto == NULL) {
            in_session->s_snmp_errno = SNMPERR_MALLOC;
            return SNMPERR_MALLOC;
        }
    } else if (get_default_authtype(&i) != NULL) {
        session->securityAuthProto =
            snmp_duplicate_objid(get_default_authtype(NULL), i);
        session->securityAuthProtoLen = i;
    }

    if (in_session->securityPrivProtoLen > 0) {
        session->securityPrivProto =
            snmp_duplicate_objid(in_session->securityPrivProto,
                                 in_session->securityPrivProtoLen);
        if (session->securityPrivProto == NULL) {
            in_session->s_snmp_errno = SNMPERR_MALLOC;
            return SNMPERR_MALLOC;
        }
    } else if (get_default_privtype(&i) != NULL) {
        session->securityPrivProto =
            snmp_duplicate_objid(get_default_privtype(NULL), i);
        session->securityPrivProtoLen = i;
    }

    if ((in_session->securityAuthKeyLen <= 0) &&
        ((cp = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
				     NETSNMP_DS_LIB_AUTHMASTERKEY)))) {
        size_t buflen = sizeof(session->securityAuthKey);
        u_char *tmpp = session->securityAuthKey;
        session->securityAuthKeyLen = 0;
        /* it will be a hex string */
        if (!snmp_hex_to_binary(&tmpp, &buflen,
                                &session->securityAuthKeyLen, 0, cp)) {
            snmp_set_detail("error parsing authentication master key");
            return SNMP_ERR_GENERR;
        }
    } else if ((in_session->securityAuthKeyLen <= 0) &&
               ((cp = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
                                            NETSNMP_DS_LIB_AUTHPASSPHRASE)) ||
                (cp = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
                                            NETSNMP_DS_LIB_PASSPHRASE)))) {
        session->securityAuthKeyLen = USM_AUTH_KU_LEN;
        if (generate_Ku(session->securityAuthProto,
                        session->securityAuthProtoLen,
                        (u_char *) cp, strlen(cp),
                        session->securityAuthKey,
                        &session->securityAuthKeyLen) != SNMPERR_SUCCESS) {
            snmp_set_detail
                ("Error generating a key (Ku) from the supplied authentication pass phrase.");
            return SNMP_ERR_GENERR;
        }
    }

    
    if ((in_session->securityPrivKeyLen <= 0) &&
        ((cp = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
				     NETSNMP_DS_LIB_PRIVMASTERKEY)))) {
        size_t buflen = sizeof(session->securityPrivKey);
        u_char *tmpp = session->securityPrivKey;
        session->securityPrivKeyLen = 0;
        /* it will be a hex string */
        if (!snmp_hex_to_binary(&tmpp, &buflen,
                                &session->securityPrivKeyLen, 0, cp)) {
            snmp_set_detail("error parsing encryption master key");
            return SNMP_ERR_GENERR;
        }
    } else if ((in_session->securityPrivKeyLen <= 0) &&
               ((cp = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
                                            NETSNMP_DS_LIB_PRIVPASSPHRASE)) ||
                (cp = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
                                            NETSNMP_DS_LIB_PASSPHRASE)))) {
        session->securityPrivKeyLen = USM_PRIV_KU_LEN;
        if (generate_Ku(session->securityAuthProto,
                        session->securityAuthProtoLen,
                        (u_char *) cp, strlen(cp),
                        session->securityPrivKey,
                        &session->securityPrivKeyLen) != SNMPERR_SUCCESS) {
            snmp_set_detail
                ("Error generating a key (Ku) from the supplied privacy pass phrase.");
            return SNMP_ERR_GENERR;
        }
    }

    return SNMPERR_SUCCESS;
}

static int usm_build_user(struct usmUser **result,
                          const netsnmp_session *session)
{
    struct usmUser *user;

    DEBUGMSGTL(("usm", "Building user %s...\n", session->securityName));
    /*
     * user doesn't exist so we create and add it
     */
    user = calloc(1, sizeof(struct usmUser));
    if (user == NULL)
        goto err;

    /*
     * copy in the securityName
     */
    if (session->securityName) {
        user->name = strdup(session->securityName);
        user->secName = strdup(session->securityName);
        if (user->name == NULL || user->secName == NULL)
            goto err;
    }

    /*
     * copy in the engineID
     */
    user->engineID = netsnmp_memdup(session->securityEngineID,
                                    session->securityEngineIDLen);
    if (session->securityEngineID && !user->engineID)
        goto err;
    user->engineIDLen = session->securityEngineIDLen;
    *result = user;
    return SNMPERR_SUCCESS;

err:
    usm_free_user(user);
    return SNMPERR_GENERR;
}

/*
 * usm_create_user_from_session(netsnmp_session *session):
 * 
 * creates a user in the usm table from the information in a session.
 * If the user already exists, it is updated with the current
 * information from the session
 * 
 * Parameters:
 * session -- IN: pointer to the session to use when creating the user.
 * 
 * Returns:
 * SNMPERR_SUCCESS
 * SNMPERR_GENERR 
 */
int
usm_create_user_from_session(netsnmp_session * session)
{
    struct usmUser *user;
    int             user_just_created = 0;
    char *cp;

    /*
     * - don't create-another/copy-into user for this session by default
     * - bail now (no error) if we don't have an engineID
     */
    if (SNMP_FLAGS_USER_CREATED == (session->flags & SNMP_FLAGS_USER_CREATED) ||
        session->securityModel != SNMP_SEC_MODEL_USM ||
        session->version != SNMP_VERSION_3 ||
        session->securityNameLen == 0 ||
        session->securityEngineIDLen == 0)
        return SNMPERR_SUCCESS;

    DEBUGMSGTL(("usm", "no flag defined...  continuing\n"));
    session->flags |= SNMP_FLAGS_USER_CREATED;

    /*
     * now that we have the engineID, create an entry in the USM list
     * for this user using the information in the session 
     */
    user = usm_get_user_from_list(session->securityEngineID,
                                  session->securityEngineIDLen,
                                  session->securityName,
                                  usm_get_userList(), 0);
    if (NULL != user) {
        DEBUGMSGTL(("usm", "user exists x=%p\n", user));
    } else {
        if (usm_build_user(&user, session) != SNMPERR_SUCCESS)
            return SNMPERR_GENERR;
        user_just_created = 1;
    }

    /*
     * copy the auth protocol 
     */
    if (user->authProtocol == NULL && session->securityAuthProto != NULL) {
        SNMP_FREE(user->authProtocol);
        user->authProtocol =
            snmp_duplicate_objid(session->securityAuthProto,
                                 session->securityAuthProtoLen);
        if (user->authProtocol == NULL) {
            usm_free_user(user);
            return SNMPERR_GENERR;
        }
        user->authProtocolLen = session->securityAuthProtoLen;
    }

    /*
     * copy the priv protocol 
     */
    if (user->privProtocol == NULL && session->securityPrivProto != NULL) {
        SNMP_FREE(user->privProtocol);
        user->privProtocol =
            snmp_duplicate_objid(session->securityPrivProto,
                                 session->securityPrivProtoLen);
        if (user->privProtocol == NULL) {
            usm_free_user(user);
            return SNMPERR_GENERR;
        }
        user->privProtocolLen = session->securityPrivProtoLen;
    }

    /*
     * copy in the authentication Key.  If not localized, localize it 
     */
    if (user->authKey == NULL) {
        if (session->securityAuthLocalKey != NULL
            && session->securityAuthLocalKeyLen != 0) {
            /* already localized key passed in.  use it */
            SNMP_FREE(user->authKey);
            user->authKey = netsnmp_memdup(session->securityAuthLocalKey,
                                           session->securityAuthLocalKeyLen);
            if (!user->authKey) {
                usm_free_user(user);
                return SNMPERR_GENERR;
            }
            user->authKeyLen = session->securityAuthLocalKeyLen;
        } else if (session->securityAuthKeyLen != 0) {
            SNMP_FREE(user->authKey);
            user->authKey = (u_char *) calloc(1, USM_LENGTH_KU_HASHBLOCK);
            user->authKeyLen = USM_LENGTH_KU_HASHBLOCK;
            if ((user->authKey == NULL) ||
                generate_kul(user->authProtocol, user->authProtocolLen,
                             user->engineID, user->engineIDLen,
                             session->securityAuthKey,
                             session->securityAuthKeyLen, user->authKey,
                             &user->authKeyLen) != SNMPERR_SUCCESS) {
                usm_free_user(user);
                return SNMPERR_GENERR;
            }
        } else if ((cp = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
                                               NETSNMP_DS_LIB_AUTHLOCALIZEDKEY))) {
            size_t buflen = USM_AUTH_KU_LEN;
            SNMP_FREE(user->authKey);
            user->authKey = (u_char *)malloc(buflen); /* max length needed */
            user->authKeyLen = 0;
            /* it will be a hex string */
            if ((NULL == user->authKey) ||
                !snmp_hex_to_binary(&user->authKey, &buflen, &user->authKeyLen,
                                    0, cp)) {
                usm_free_user(user);
                return SNMPERR_GENERR;
            }
        }
    }

    /*
     * copy in the privacy Key.  If not localized, localize it 
     */
    if (user->privKey == NULL) {
        /** save buffer size in case we need to extend key */
        int keyBufSize = USM_PRIV_KU_LEN;

        DEBUGMSGTL(("usm", "copying privKey\n"));
        if (session->securityPrivLocalKey != NULL
            && session->securityPrivLocalKeyLen != 0) {
            /* already localized key passed in.  use it */
            SNMP_FREE(user->privKey);
            user->privKey = netsnmp_memdup(session->securityPrivLocalKey,
                                           session->securityPrivLocalKeyLen);
            if (!user->privKey) {
                usm_free_user(user);
                return SNMPERR_GENERR;
            }
            keyBufSize = user->privKeyLen = session->securityPrivLocalKeyLen;
        } else if (session->securityPrivKeyLen != 0) {
            SNMP_FREE(user->privKey);
            user->privKey = (u_char *) calloc(1, keyBufSize);
            user->privKeyLen = keyBufSize;
            if ((user->privKey == NULL) ||
                generate_kul(user->authProtocol, user->authProtocolLen,
                             user->engineID, user->engineIDLen,
                             session->securityPrivKey,
                             session->securityPrivKeyLen, user->privKey,
                             &user->privKeyLen) != SNMPERR_SUCCESS) {
                usm_free_user(user);
                return SNMPERR_GENERR;
            }
        } else if ((cp = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
                                               NETSNMP_DS_LIB_PRIVLOCALIZEDKEY))) {
            size_t buflen = keyBufSize;
            user->privKey = (u_char *)malloc(buflen); /* max length needed */
            user->privKeyLen = 0;
            /* it will be a hex string */
            if ((NULL == user->privKey) ||
                !snmp_hex_to_binary(&user->privKey, &buflen, &user->privKeyLen,
                                    0, cp)) {
                usm_free_user(user);
                return SNMPERR_GENERR;
            }
        }
        if (usm_extend_user_kul(user, keyBufSize) != SNMPERR_SUCCESS) {
            usm_free_user(user);
            return SNMPERR_GENERR;
        }
    }

    if (user_just_created) {
        /*
         * add the user into the database 
         */
        user->userStatus = RS_ACTIVE;
        user->userStorageType = ST_READONLY;
        usm_add_user(user);
    }
    DEBUGMSGTL(("9:usm", "user created\n"));

    return SNMPERR_SUCCESS;


}

/* A wrapper around the hook */
static int
usm_create_user_from_session_hook(struct session_list *slp,
                                  netsnmp_session *session)
{
    DEBUGMSGTL(("usm", "potentially bootstrapping the USM table from session data\n"));
    return usm_create_user_from_session(session);
}

static int
usm_build_probe_pdu(netsnmp_pdu **pdu)
{
    struct usmUser *user;

    /*
     * create the pdu 
     */
    if (!pdu)
        return -1;
    *pdu = snmp_pdu_create(SNMP_MSG_GET);
    if (!(*pdu))
        return -1;
    (*pdu)->version = SNMP_VERSION_3;
    (*pdu)->securityName = strdup("");
    (*pdu)->securityNameLen = strlen((*pdu)->securityName);
    (*pdu)->securityLevel = SNMP_SEC_LEVEL_NOAUTH;
    (*pdu)->securityModel = SNMP_SEC_MODEL_USM;

    /*
     * create the empty user 
     */
    user = usm_get_user(NULL, 0, (*pdu)->securityName);
    if (user == NULL) {
        user = (struct usmUser *) calloc(1, sizeof(struct usmUser));
        if (user == NULL) {
            snmp_free_pdu(*pdu);
            *pdu = (netsnmp_pdu *) NULL;
            return -1;
        }
        user->name = strdup((*pdu)->securityName);
        user->secName = strdup((*pdu)->securityName);
        user->authProtocolLen = sizeof(usmNoAuthProtocol) / sizeof(oid);
        user->authProtocol =
            snmp_duplicate_objid(usmNoAuthProtocol, user->authProtocolLen);
        user->privProtocolLen = sizeof(usmNoPrivProtocol) / sizeof(oid);
        user->privProtocol =
            snmp_duplicate_objid(usmNoPrivProtocol, user->privProtocolLen);
        usm_add_user(user);
    }
    return 0;
}

static int usm_discover_engineid(struct session_list *slp,
                                 netsnmp_session *session)
{
    netsnmp_pdu    *pdu = NULL, *response = NULL;
    int status, i;

    if (slp->session->securityEngineIDLen != 0) {
        DEBUGMSGTL(("snmp_api", "engineID already known, skipping probe\n"));
        return SNMPERR_SUCCESS;
    }

    if (usm_build_probe_pdu(&pdu) != 0) {
        DEBUGMSGTL(("snmp_api", "unable to create probe PDU\n"));
        return SNMP_ERR_GENERR;
    }
    DEBUGMSGTL(("snmp_api", "probing for engineID...\n"));
    session->flags |= SNMP_FLAGS_DONT_PROBE; /* prevent recursion */
    status = snmp_sess_synch_response(slp, pdu, &response);

    if ((response == NULL) && (status == STAT_SUCCESS)) {
        status = STAT_ERROR;
    }

    switch (status) {
    case STAT_SUCCESS:
        session->s_snmp_errno = SNMPERR_INVALID_MSG; /* XX?? */
        DEBUGMSGTL(("snmp_sess_open",
                    "error: expected Report as response to probe: %s (%ld)\n",
                    snmp_errstring(response->errstat),
                    response->errstat));
        break;
    case STAT_ERROR:   /* this is what we expected -> Report == STAT_ERROR */
        session->s_snmp_errno = SNMPERR_UNKNOWN_ENG_ID;
        break;
    case STAT_TIMEOUT:
        session->s_snmp_errno = SNMPERR_TIMEOUT;
        break;
    default:
        DEBUGMSGTL(("snmp_sess_open",
                    "unable to connect with remote engine: %s (%d)\n",
                    snmp_api_errstring(session->s_snmp_errno),
                    session->s_snmp_errno));
        break;
    }

    if (slp->session->securityEngineIDLen == 0) {
        DEBUGMSGTL(("snmp_api",
                    "unable to determine remote engine ID\n"));
        /* clear the flag so that probe occurs on next inform */
        session->flags &= ~SNMP_FLAGS_DONT_PROBE;
        return SNMP_ERR_GENERR;
    }

    session->s_snmp_errno = SNMPERR_SUCCESS;
    if (snmp_get_do_debugging()) {
        DEBUGMSGTL(("snmp_sess_open",
                    "  probe found engineID:  "));
        for (i = 0; i < slp->session->securityEngineIDLen; i++)
            DEBUGMSG(("snmp_sess_open", "%02x",
                      slp->session->securityEngineID[i]));
        DEBUGMSG(("snmp_sess_open", "\n"));
    }

    /*
     * if boot/time supplied set it for this engineID 
     */
    if (session->engineBoots || session->engineTime) {
        set_enginetime(session->securityEngineID,
                       session->securityEngineIDLen,
                       session->engineBoots, session->engineTime,
                       TRUE);
    }
    return SNMPERR_SUCCESS;
}

static int
usm_lookup_alg_type(const char *str, const usm_alg_type_t *types)
{
    int i, l;
    l = strlen(str);
    for (i = 0; types[i].label; ++i) {
        if (0 == strncasecmp(types[i].label, str, l))
            return types[i].value;
    }

    return -1;
}

static const char *
usm_lookup_alg_str(int value, const usm_alg_type_t *types)
{
    int i;
    for (i = 0; types[i].label; ++i)
        if (value == types[i].value)
            return types[i].label;

    return NULL;
}

int
usm_lookup_auth_type(const char *str)
{
    return usm_lookup_alg_type(str, usm_auth_type );
}

int
usm_lookup_priv_type(const char *str)
{
    return usm_lookup_alg_type(str, usm_priv_type );
}

const char *
usm_lookup_auth_str(int value)
{
    return usm_lookup_alg_str(value, usm_auth_type );
}

const char *
usm_lookup_priv_str(int value)
{
    return usm_lookup_alg_str(value, usm_priv_type );
}

static void
clear_user_list(void)
{
    struct usmUser *tmp = userList, *next = NULL;

    while (tmp != NULL) {
	next = tmp->next;
	usm_free_user(tmp);
	tmp = next;
    }
    userList = NULL;

}

#ifndef NETSNMP_NO_WRITE_SUPPORT
/*
 * take a given user and clone the security info into another 
 */
struct usmUser *
usm_cloneFrom_user(struct usmUser *from, struct usmUser *to)
{
    to->flags = from->flags;

    /*
     * copy the authProtocol oid row pointer 
     */
    SNMP_FREE(to->authProtocol);

    if ((to->authProtocol =
         snmp_duplicate_objid(from->authProtocol,
                              from->authProtocolLen)) != NULL)
        to->authProtocolLen = from->authProtocolLen;
    else
        to->authProtocolLen = 0;


    /*
     * copy the authKey 
     */
    SNMP_FREE(to->authKey);

    if (from->authKeyLen > 0 &&
        (to->authKey = (u_char *) malloc(from->authKeyLen))
        != NULL) {
        to->authKeyLen = from->authKeyLen;
        memcpy(to->authKey, from->authKey, to->authKeyLen);
    } else {
        to->authKey = NULL;
        to->authKeyLen = 0;
    }

    /*
     * copy the authKeyKu
     */
    SNMP_FREE(to->authKeyKu);

    if (from->authKeyKuLen > 0 &&
        (to->authKeyKu = (u_char *) malloc(from->authKeyKuLen)) != NULL) {
        to->authKeyKuLen = from->authKeyKuLen;
        memcpy(to->authKeyKu, from->authKeyKu, to->authKeyKuLen);
    } else {
        to->authKeyKu = NULL;
        to->authKeyKuLen = 0;
    }


    /*
     * copy the privProtocol oid row pointer 
     */
    SNMP_FREE(to->privProtocol);

    if ((to->privProtocol =
         snmp_duplicate_objid(from->privProtocol,
                              from->privProtocolLen)) != NULL)
        to->privProtocolLen = from->privProtocolLen;
    else
        to->privProtocolLen = 0;

    /*
     * copy the privKey 
     */
    SNMP_FREE(to->privKey);

    if (from->privKeyLen > 0 &&
        (to->privKey = (u_char *) malloc(from->privKeyLen))
        != NULL) {
        to->privKeyLen = from->privKeyLen;
        memcpy(to->privKey, from->privKey, to->privKeyLen);
    } else {
        to->privKey = NULL;
        to->privKeyLen = 0;
    }

    /*
     * copy the privKeyKu
     */
    SNMP_FREE(to->privKeyKu);
    if (from->privKeyKuLen > 0 &&
        (to->privKeyKu = (u_char *) malloc(from->privKeyKuLen)) != NULL) {
        to->privKeyKuLen = from->privKeyKuLen;
        memcpy(to->privKeyKu, from->privKeyKu, to->privKeyKuLen);
    } else {
        to->privKeyKu = NULL;
        to->privKeyKuLen = 0;
    }
    return to;
}
#endif /* NETSNMP_NO_WRITE_SUPPORT */

/*
 * usm_create_user(void):
 * create a default empty user, instantiating only the auth/priv
 * protocols to noAuth and noPriv OID pointers
 */
struct usmUser *
usm_create_user(void)
{
    struct usmUser *newUser;

    /*
     * create the new user 
     */
    newUser = (struct usmUser *) calloc(1, sizeof(struct usmUser));
    if (newUser == NULL)
        return NULL;

    /*
     * fill the auth/priv protocols 
     */
    if ((newUser->authProtocol =
         snmp_duplicate_objid(usmNoAuthProtocol,
                              sizeof(usmNoAuthProtocol) / sizeof(oid))) ==
        NULL)
        return usm_free_user(newUser);
    newUser->authProtocolLen = sizeof(usmNoAuthProtocol) / sizeof(oid);

    if ((newUser->privProtocol =
         snmp_duplicate_objid(usmNoPrivProtocol,
                              sizeof(usmNoPrivProtocol) / sizeof(oid))) ==
        NULL)
        return usm_free_user(newUser);
    newUser->privProtocolLen = sizeof(usmNoPrivProtocol) / sizeof(oid);

    /*
     * set the storage type to nonvolatile, and the status to ACTIVE 
     */
    newUser->userStorageType = ST_NONVOLATILE;
    newUser->userStatus = RS_ACTIVE;
    return newUser;

}                               /* end usm_clone_user() */

/*
 * usm_create_initial_user(void):
 * creates an initial user, filled with the defaults defined in the
 * USM document.
 */
static struct usmUser *
usm_create_initial_user(const char *name,
                        const oid * authProtocol, size_t authProtocolLen,
                        const oid * privProtocol, size_t privProtocolLen)
{
    struct usmUser *newUser = usm_create_user();
    if (newUser == NULL)
        return NULL;

    if ((newUser->name = strdup(name)) == NULL)
        return usm_free_user(newUser);

    if ((newUser->secName = strdup(name)) == NULL)
        return usm_free_user(newUser);

    if ((newUser->engineID =
         snmpv3_generate_engineID(&newUser->engineIDLen)) == NULL)
        return usm_free_user(newUser);

    if ((newUser->cloneFrom = (oid *) malloc(sizeof(oid) * 2)) == NULL)
        return usm_free_user(newUser);
    newUser->cloneFrom[0] = 0;
    newUser->cloneFrom[1] = 0;
    newUser->cloneFromLen = 2;

    SNMP_FREE(newUser->privProtocol);
    if ((newUser->privProtocol = snmp_duplicate_objid(privProtocol,
                                                      privProtocolLen)) ==
        NULL) {
        return usm_free_user(newUser);
    }
    newUser->privProtocolLen = privProtocolLen;

    SNMP_FREE(newUser->authProtocol);
    if ((newUser->authProtocol = snmp_duplicate_objid(authProtocol,
                                                      authProtocolLen)) ==
        NULL) {
        return usm_free_user(newUser);
    }
    newUser->authProtocolLen = authProtocolLen;

    newUser->userStatus = RS_ACTIVE;
    newUser->userStorageType = ST_READONLY;

    return newUser;
}

/*
 * usm_save_user(): saves a user to the persistent cache 
 */
static void
usm_save_user(struct usmUser *user, const char *token, const char *type)
{
    char            line[4096];
    char           *cptr;

    memset(line, 0, sizeof(line));

    sprintf(line, "%s %d %d ", token, user->userStatus,
            user->userStorageType);
    cptr = &line[strlen(line)]; /* the NULL */
    cptr =
        read_config_save_octet_string(cptr, user->engineID,
                                      user->engineIDLen);
    *cptr++ = ' ';
    cptr = read_config_save_octet_string(cptr, (u_char *) user->name,
                                         (user->name == NULL) ? 0 :
                                         strlen(user->name));
    *cptr++ = ' ';
    cptr = read_config_save_octet_string(cptr, (u_char *) user->secName,
                                         (user->secName == NULL) ? 0 :
                                         strlen(user->secName));
    *cptr++ = ' ';
    cptr =
        read_config_save_objid(cptr, user->cloneFrom, user->cloneFromLen);
    *cptr++ = ' ';
    cptr = read_config_save_objid(cptr, user->authProtocol,
                                  user->authProtocolLen);
    *cptr++ = ' ';
    cptr =
        read_config_save_octet_string(cptr, user->authKey,
                                      user->authKeyLen);
    *cptr++ = ' ';
    cptr = read_config_save_objid(cptr, user->privProtocol,
                                  user->privProtocolLen);
    *cptr++ = ' ';
    cptr =
        read_config_save_octet_string(cptr, user->privKey,
                                      user->privKeyLen);
    *cptr++ = ' ';
    cptr = read_config_save_octet_string(cptr, user->userPublicString,
                                         user->userPublicStringLen);

    read_config_store(type, line);
}

static void
usm_save_users_from_list(struct usmUser *puserList, const char *token,
                         const char *type)
{
    struct usmUser *uptr;
    for (uptr = puserList; uptr != NULL; uptr = uptr->next) {
        if (uptr->userStorageType == ST_NONVOLATILE)
            usm_save_user(uptr, token, type);
    }
}

/*
 * usm_save_users(): saves a list of users to the persistent cache 
 */
static void
usm_save_users(const char *token, const char *type)
{
    usm_save_users_from_list(userList, token, type);
}

/*
 * this is a callback that can store all known users based on a
 * previously registered application ID 
 */
static int
usm_store_users(int majorID, int minorID, void *serverarg, void *clientarg)
{
    /*
     * figure out our application name 
     */
    char           *appname = (char *) clientarg;
    if (appname == NULL) {
        appname = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, 
					NETSNMP_DS_LIB_APPTYPE);
    }

    /*
     * save the user base 
     */
    usm_save_users("usmUser", appname);

    /*
     * never fails 
     */
    return SNMPERR_SUCCESS;
}

/*
 * usm_parse_user(): reads in a line containing a saved user profile
 * and returns a pointer to a newly created struct usmUser. 
 */
static struct usmUser *
usm_read_user(const char *line)
{
    struct usmUser *user;
    size_t          len, proper_length, privtype;

    user = usm_create_user();
    if (user == NULL)
        return NULL;

    user->userStatus = atoi(line);
    line = skip_token_const(line);
    user->userStorageType = atoi(line);
    line = skip_token_const(line);
    line = read_config_read_octet_string_const(line, &user->engineID,
                                               &user->engineIDLen);

    /*
     * set the lcd entry for this engineID to the minimum boots/time
     * values so that its a known engineid and won't return a report pdu.
     * This is mostly important when receiving v3 traps so that the usm
     * will at least continue processing them. 
     */
    set_enginetime(user->engineID, user->engineIDLen, 1, 0, 0);

    line = read_config_read_octet_string(line, (u_char **) & user->name,
                                         &len);
    line = read_config_read_octet_string(line, (u_char **) & user->secName,
                                         &len);
    SNMP_FREE(user->cloneFrom);
    user->cloneFromLen = 0;

    line = read_config_read_objid_const(line, &user->cloneFrom,
                                        &user->cloneFromLen);

    SNMP_FREE(user->authProtocol);
    user->authProtocolLen = 0;

    line = read_config_read_objid_const(line, &user->authProtocol,
                                        &user->authProtocolLen);
    line = read_config_read_octet_string_const(line, &user->authKey,
                                               &user->authKeyLen);
    SNMP_FREE(user->privProtocol);
    user->privProtocolLen = 0;

    line = read_config_read_objid_const(line, &user->privProtocol,
                                        &user->privProtocolLen);
    line = read_config_read_octet_string(line, &user->privKey,
                                         &user->privKeyLen);

    privtype = sc_get_privtype(user->privProtocol, user->privProtocolLen);
    proper_length = sc_get_proper_priv_length_bytype(privtype);
    if (USM_CREATE_USER_PRIV_DES == privtype)
        proper_length *= 2; /* ?? we store salt with key */
    /* For backwards compatibility */
    if (user->privKeyLen > proper_length) {
        user->privKeyLen = proper_length;
    }

    line = read_config_read_octet_string(line, &user->userPublicString,
                                         &user->userPublicStringLen);
    return user;
}

/*
 * snmpd.conf parsing routines 
 */
void
usm_parse_config_usmUser(const char *token, char *line)
{
    struct usmUser *uptr;

    uptr = usm_read_user(line);
    if ( uptr)
        usm_add_user(uptr);
}

/*******************************************************************-o-******
 * usm_set_password
 *
 * Parameters:
 *	*token
 *	*line
 *      
 *
 * format: userSetAuthPass     secname engineIDLen engineID pass
 *     or: userSetPrivPass     secname engineIDLen engineID pass 
 *     or: userSetAuthKey      secname engineIDLen engineID KuLen Ku
 *     or: userSetPrivKey      secname engineIDLen engineID KuLen Ku 
 *     or: userSetAuthLocalKey secname engineIDLen engineID KulLen Kul
 *     or: userSetPrivLocalKey secname engineIDLen engineID KulLen Kul 
 *
 * type is:	1=passphrase; 2=Ku; 3=Kul.
 *
 *
 * ASSUMES  Passwords are null-terminated printable strings.
 */
static void
usm_set_password(const char *token, char *line)
{
    char           *cp;
    char            nameBuf[SNMP_MAXBUF];
    u_char         *engineID = NULL;
    size_t          engineIDLen = 0;
    struct usmUser *user;

    cp = copy_nword(line, nameBuf, sizeof(nameBuf));
    if (cp == NULL) {
        config_perror("invalid name specifier");
        return;
    }

    DEBUGMSGTL(("usm", "comparing: %s and %s\n", cp, WILDCARDSTRING));
    if (strncmp(cp, WILDCARDSTRING, strlen(WILDCARDSTRING)) == 0) {
        /*
         * match against all engineIDs we know about 
         */
        cp = skip_token(cp);
        for (user = userList; user != NULL; user = user->next) {
            if (user->secName && strcmp(user->secName, nameBuf) == 0) {
                usm_set_user_password(user, token, cp);
            }
        }
    } else {
        cp = read_config_read_octet_string(cp, &engineID, &engineIDLen);
        if (cp == NULL) {
            config_perror("invalid engineID specifier");
            SNMP_FREE(engineID);
            return;
        }

        user = usm_get_user(engineID, engineIDLen, nameBuf);
        if (user == NULL) {
            config_perror("not a valid user/engineID pair");
            SNMP_FREE(engineID);
            return;
        }
        usm_set_user_password(user, token, cp);
        SNMP_FREE(engineID);
    }
}

/*
 * uses the rest of LINE to configure USER's password of type TOKEN 
 */
void
usm_set_user_password(struct usmUser *user, const char *token, char *line)
{
    char           *cp = line;
    u_char         *engineID = user->engineID;
    size_t          engineIDLen = user->engineIDLen;

    u_char        **key;
    size_t         *keyLen;
    u_char          userKey[SNMP_MAXBUF_SMALL];
    size_t          userKeyLen = SNMP_MAXBUF_SMALL;
    u_char         *userKeyP = userKey;
    int             type, ret;

    /*
     * Retrieve the "old" key and set the key type.
     */
    if (!token) {
        return;
    } else if (strcmp(token, "userSetAuthPass") == 0) {
        key = &user->authKey;
        keyLen = &user->authKeyLen;
        type = 0;
    } else if (strcmp(token, "userSetPrivPass") == 0) {
        key = &user->privKey;
        keyLen = &user->privKeyLen;
        type = 0;
    } else if (strcmp(token, "userSetAuthKey") == 0) {
        key = &user->authKey;
        keyLen = &user->authKeyLen;
        type = 1;
    } else if (strcmp(token, "userSetPrivKey") == 0) {
        key = &user->privKey;
        keyLen = &user->privKeyLen;
        type = 1;
    } else if (strcmp(token, "userSetAuthLocalKey") == 0) {
        key = &user->authKey;
        keyLen = &user->authKeyLen;
        type = 2;
    } else if (strcmp(token, "userSetPrivLocalKey") == 0) {
        key = &user->privKey;
        keyLen = &user->privKeyLen;
        type = 2;
    } else {
        /*
         * no old key, or token was not recognized 
         */
        return;
    }

    if (*key) {
        /*
         * (destroy and) free the old key 
         */
        memset(*key, 0, *keyLen);
        SNMP_FREE(*key);
    }

    if (type == 0) {
        /*
         * convert the password into a key 
         */
        if (cp == NULL) {
            config_perror("missing user password");
            return;
        }
        ret = generate_Ku(user->authProtocol, user->authProtocolLen,
                          (u_char *) cp, strlen(cp), userKey, &userKeyLen);

        if (ret != SNMPERR_SUCCESS) {
            config_perror("setting key failed (in sc_genKu())");
            return;
        }
        /* save master key */
        if (user->flags & USMUSER_FLAG_KEEP_MASTER_KEY) {
            if (userKey == user->privKey) {
                user->privKeyKu = netsnmp_memdup(userKey, userKeyLen);
                user->privKeyKuLen = userKeyLen;
            } else if (userKey == user->authKey) {
                user->authKeyKu = netsnmp_memdup(userKey, userKeyLen);
                user->authKeyKuLen = userKeyLen;
            }
        }
    } else if (type == 1) {
        cp = read_config_read_octet_string(cp, &userKeyP, &userKeyLen);

        if (cp == NULL) {
            config_perror("invalid user key");
            return;
        }
    }

    if (type < 2) {
        *key = (u_char *) malloc(SNMP_MAXBUF_SMALL);
        *keyLen = SNMP_MAXBUF_SMALL;
        ret = generate_kul(user->authProtocol, user->authProtocolLen,
                           engineID, engineIDLen,
                           userKey, userKeyLen, *key, keyLen);
        if (ret != SNMPERR_SUCCESS) {
            config_perror("setting key failed (in generate_kul())");
            return;
        }

        /*
         * (destroy and) free the old key 
         */
        memset(userKey, 0, sizeof(userKey));

    } else {
        /*
         * the key is given, copy it in 
         */
        cp = read_config_read_octet_string(cp, key, keyLen);

        if (cp == NULL) {
            config_perror("invalid localized user key");
            return;
        }
    }

    if (key == &user->privKey) {
        ret = usm_extend_user_kul(user, *keyLen);
        if (SNMPERR_SUCCESS != ret) {
            config_perror("error extending localized user key");
            return;
        }
    }
}                               /* end usm_set_password() */

/*
 * create a usm user from a string.
 *
 * The format for the string is described in the createUser
 * secion of the snmpd.conf man page.
 *
 * On success, a pointer to the created usmUser struct is returned.
 * On error, a NULL pointer is returned. In this case, if a pointer to a
 *    char pointer is provided in errorMsg, an error string is returned.
 *    This error string points to a static message, and should not be
 *    freed.
 */
static struct usmUser *
usm_create_usmUser_from_string(char *line, const char **errorMsg)
{
    char           *cp;
    const char     *dummy;
    char            buf[SNMP_MAXBUF_MEDIUM];
    struct usmUser *newuser;
    u_char          userKey[SNMP_MAXBUF_SMALL], *tmpp;
    size_t          userKeyLen = SNMP_MAXBUF_SMALL;
    size_t          privKeySize;
    size_t          ret;
    int             ret2, properLen, properPrivKeyLen;
    const oid      *def_auth_prot, *def_priv_prot;
    size_t          def_auth_prot_len, def_priv_prot_len;
    const netsnmp_priv_alg_info *pai;

    def_auth_prot = get_default_authtype(&def_auth_prot_len);
    def_priv_prot = get_default_privtype(&def_priv_prot_len);

    if (NULL == line)
        return NULL;

#ifdef NETSNMP_ENABLE_TESTING_CODE
    DEBUGMSGTL(("usmUser", "new user %s\n", line)); /* logs passphrases */
#endif

    if (NULL == errorMsg)
        errorMsg = &dummy;
    *errorMsg = NULL; /* no errors yet */

    newuser = usm_create_user();
    if (newuser == NULL) {
        *errorMsg = "malloc failure creating new user";
        goto fail;
    }

    /*
     * READ: Security Name 
     */
    cp = copy_nword(line, buf, sizeof(buf));

    /*
     * check for (undocumented) 'keep master key' flag. so far, this is
     * just used for users for informs (who need non-localized keys).
     */
    if (strcmp(buf, "-M") == 0) {
        newuser->flags |= USMUSER_FLAG_KEEP_MASTER_KEY;
        cp = copy_nword(cp, buf, sizeof(buf));
    }

    /*
     * might be a -e ENGINEID argument 
     */
    if (strcmp(buf, "-e") == 0) {
        size_t          ebuf_len = 32, eout_len = 0;
        u_char         *ebuf = (u_char *) malloc(ebuf_len);

        if (ebuf == NULL) {
            *errorMsg = "malloc failure processing -e flag";
            goto fail;
        }

        /*
         * Get the specified engineid from the line.  
         */
        cp = copy_nword(cp, buf, sizeof(buf));
        if (!snmp_hex_to_binary(&ebuf, &ebuf_len, &eout_len, 1, buf)) {
            *errorMsg = "invalid EngineID argument to -e";
            SNMP_FREE(ebuf);
            goto fail;
        }

        newuser->engineID = ebuf;
        newuser->engineIDLen = eout_len;
        cp = copy_nword(cp, buf, sizeof(buf));
    } else {
        newuser->engineID = snmpv3_generate_engineID(&ret);
        if (ret == 0) {
            goto fail;
        }
        newuser->engineIDLen = ret;
    }

    newuser->secName = strdup(buf);
    newuser->name = strdup(buf);

    if (!cp) {
#ifdef NETSNMP_FORCE_SYSTEM_V3_AUTHPRIV
        /** no passwords ok iff defaults are noauth/nopriv */
        if (snmp_oid_compare(usmNoAuthProtocol, OID_LENGTH(usmNoAuthProtocol),
                             def_auth_prot, def_auth_prot_len) != 0) {
            *errorMsg = "no authentication pass phrase";
            goto fail;
        }
        if (snmp_oid_compare(usmNoPrivProtocol, OID_LENGTH(usmNoPrivProtocol),
                             def_priv_prot, def_priv_prot_len) != 0) {
            *errorMsg = "no privacy pass phrase";
            goto fail;
        }
#endif /* NETSNMP_FORCE_SYSTEM_V3_AUTHPRIV */
        goto add;               /* no authentication or privacy type */
    }

    /*
     * READ: Authentication Type 
     */
    newuser->authProtocol[0] = 0;
    cp = copy_nword(cp, buf, sizeof(buf));
    if ((strncmp(cp, "default", 7) == 0) && (NULL != def_auth_prot)) {
        SNMP_FREE(newuser->authProtocol);
        newuser->authProtocol = snmp_duplicate_objid(def_auth_prot,
                                                     def_auth_prot_len);
        if (newuser->authProtocol == NULL) {
            *errorMsg = "malloc failed";
            goto fail;
        }
        newuser->authProtocolLen = def_auth_prot_len;
    } else {
        const oid *auth_prot;
        int auth_type = usm_lookup_auth_type(buf);
        if (auth_type < 0) {
            *errorMsg = "unknown authProtocol";
            goto fail;
        }
        auth_prot = sc_get_auth_oid(auth_type, &newuser->authProtocolLen);
        if (auth_prot) {
            SNMP_FREE(newuser->authProtocol);
            newuser->authProtocol =
                snmp_duplicate_objid(auth_prot, newuser->authProtocolLen);
        }
        if (newuser->authProtocol == NULL) {
            *errorMsg = "malloc failed";
            goto fail;
        }
    }
    if (0 == newuser->authProtocol[0]) {
        *errorMsg = "Unknown authentication protocol";
        goto fail;
    }
#ifdef NETSNMP_FORCE_SYSTEM_V3_AUTHPRIV
    if (snmp_oid_compare(newuser->authProtocol, newuser->authProtocolLen,
                         def_auth_prot, def_auth_prot_len) != 0) {
        *errorMsg = "auth protocol does not match system policy";
        goto fail;
    }
#endif /* NETSNMP_FORCE_SYSTEM_V3_AUTHPRIV */

    /*
     * READ: Authentication Pass Phrase or key
     */
    cp = copy_nword(cp, buf, sizeof(buf));
    if (strcmp(buf,"-m") == 0) {
        /* a master key is specified */
        cp = copy_nword(cp, buf, sizeof(buf));
        ret = sizeof(userKey);
        tmpp = userKey;
        userKeyLen = 0;
        if (!snmp_hex_to_binary(&tmpp, &ret, &userKeyLen, 0, buf)) {
            *errorMsg = "invalid key value argument to -m";
            goto fail;
        }
        /* save master key */
        if (newuser->flags & USMUSER_FLAG_KEEP_MASTER_KEY) {
            newuser->authKeyKu = netsnmp_memdup(userKey, userKeyLen);
            newuser->authKeyKuLen = userKeyLen;
        }
    } else if (strcmp(buf,"-l") != 0) {
        /* a password is specified */
        userKeyLen = sizeof(userKey);
        ret2 = generate_Ku(newuser->authProtocol, newuser->authProtocolLen,
                          (u_char *) buf, strlen(buf), userKey, &userKeyLen);
        if (ret2 != SNMPERR_SUCCESS) {
            *errorMsg = "could not generate the authentication key from the supplied pass phrase.";
            goto fail;
        }
        /* save master key */
        if (newuser->flags & USMUSER_FLAG_KEEP_MASTER_KEY) {
            newuser->authKeyKu = netsnmp_memdup(userKey, userKeyLen);
            newuser->authKeyKuLen = userKeyLen;
        }
    }        
        
    /*
     * And turn it into a localized key 
     */
    properLen = sc_get_proper_auth_length_bytype(
        sc_get_authtype(newuser->authProtocol, newuser->authProtocolLen));
    if (properLen <= 0) {
        *errorMsg = "Could not get proper authentication protocol key length";
        goto fail;
    }
    newuser->authKey = (u_char *) malloc(properLen);
    newuser->authKeyLen = properLen;

    if (strcmp(buf,"-l") == 0) {
        /* a local key is directly specified */
        cp = copy_nword(cp, buf, sizeof(buf));
        ret = newuser->authKeyLen;
        newuser->authKeyLen = 0;
        if (!snmp_hex_to_binary(&newuser->authKey, &ret,
                                &newuser->authKeyLen, 0, buf)) {
            *errorMsg = "invalid key value argument to -l";
            goto fail;
        }
        if (properLen != newuser->authKeyLen) {
            *errorMsg = "improper key length to -l";
            goto fail;
        }
    } else {
        ret2 = generate_kul(newuser->authProtocol, newuser->authProtocolLen,
                           newuser->engineID, newuser->engineIDLen,
                           userKey, userKeyLen,
                           newuser->authKey, &newuser->authKeyLen);
        if (ret2 != SNMPERR_SUCCESS) {
            *errorMsg = "could not generate localized authentication key (Kul) from the master key (Ku).";
            goto fail;
        }
    }

    if (!cp) {
#ifndef NETSNMP_FORCE_SYSTEM_V3_AUTHPRIV
        goto add;               /* no privacy type (which is legal) */
#else
        if (snmp_oid_compare(usmNoPrivProtocol, OID_LENGTH(usmNoPrivProtocol),
                             def_priv_prot, def_priv_prot_len) == 0)
            goto add;
        else {
            *errorMsg = "priv protocol does not match system policy";
            goto fail;
        }
#endif /* NETSNMP_FORCE_SYSTEM_V3_AUTHPRIV */
    }

    /*
     * READ: Privacy Type 
     */
    newuser->privProtocol[0] = 0;
    cp = copy_nword(cp, buf, sizeof(buf));
    if ((strncmp(buf, "default", 7) == 0) && (NULL != def_priv_prot)) {
        SNMP_FREE(newuser->privProtocol);
        newuser->privProtocol =
            snmp_duplicate_objid(def_priv_prot, def_priv_prot_len);
        if (newuser->privProtocol == NULL) {
            *errorMsg = "malloc failed";
            goto fail;
        }
        newuser->privProtocolLen = def_priv_prot_len;
        pai = sc_get_priv_alg_byoid(newuser->privProtocol,
                                    newuser->privProtocolLen);
    } else {
        int priv_type = usm_lookup_priv_type(buf);
        if (priv_type < 0) {
            *errorMsg = "unknown privProtocol";
            DEBUGMSGTL(("usmUser", "%s %s\n", *errorMsg, buf));
            goto fail;
        }
        DEBUGMSGTL(("9:usmUser", "privProtocol %s\n", buf));
        pai = sc_get_priv_alg_bytype(priv_type);
        if (pai) {
            SNMP_FREE(newuser->privProtocol);
            newuser->privProtocolLen = pai->oid_len;
            newuser->privProtocol =
                snmp_duplicate_objid(pai->alg_oid, newuser->privProtocolLen);
            DEBUGMSGTL(("9:usmUser", "pai %s\n", pai->name));
            if (newuser->privProtocol == NULL) {
                *errorMsg = "malloc failed";
                goto fail;
            }
        }
    }
    if (NULL == pai) {
        *errorMsg = "priv protocol lookup failed";
        goto fail;
    }

    if (0 == newuser->privProtocol[0] && NULL == *errorMsg)
        *errorMsg = "Unknown privacy protocol";
    if (NULL != *errorMsg)
        goto fail;
#ifdef NETSNMP_FORCE_SYSTEM_V3_AUTHPRIV
    if (snmp_oid_compare(newuser->privProtocol, newuser->privProtocolLen,
                         def_priv_prot, def_priv_prot_len) != 0) {
        *errorMsg = "priv protocol does not match system policy";
        goto fail;
    }
#endif /* NETSNMP_FORCE_SYSTEM_V3_AUTHPRIV */

    properPrivKeyLen = pai->proper_length;
    if (USM_CREATE_USER_PRIV_DES == pai->type)
        properPrivKeyLen *= 2; /* ?? we store salt with key */

    /*
     * READ: Encryption Pass Phrase or key
     */
    if (!cp) {
        /*
         * assume the same as the authentication key 
         */
        newuser->privKey = netsnmp_memdup(newuser->authKey,
                                          newuser->authKeyLen);
        privKeySize = newuser->privKeyLen = newuser->authKeyLen;
        if (newuser->flags & USMUSER_FLAG_KEEP_MASTER_KEY) {
            newuser->privKeyKu = netsnmp_memdup(newuser->authKeyKu,
                                                newuser->authKeyKuLen);
            newuser->privKeyKuLen = newuser->authKeyKuLen;
        }
    } else {
        cp = copy_nword(cp, buf, sizeof(buf));
        
        if (strcmp(buf,"-m") == 0) {
            /* a master key is specified */
            cp = copy_nword(cp, buf, sizeof(buf));
            ret = sizeof(userKey);
            tmpp = userKey;
            userKeyLen = 0;
            if (!snmp_hex_to_binary(&tmpp, &ret, &userKeyLen, 0, buf)) {
                *errorMsg = "invalid key value argument to -m";
                goto fail;
            }
            /* save master key */
            if (newuser->flags & USMUSER_FLAG_KEEP_MASTER_KEY) {
                newuser->privKeyKu = netsnmp_memdup(userKey, userKeyLen);
                newuser->privKeyKuLen = userKeyLen;
            }
        } else if (strcmp(buf,"-l") != 0) {
            /* a password is specified */
            userKeyLen = sizeof(userKey);
            ret2 = generate_Ku(newuser->authProtocol, newuser->authProtocolLen,
                              (u_char*)buf, strlen(buf), userKey, &userKeyLen);
            if (ret2 != SNMPERR_SUCCESS) {
                *errorMsg = "could not generate the privacy key from the supplied pass phrase.";
                goto fail;
            }
            /* save master key */
            if (newuser->flags & USMUSER_FLAG_KEEP_MASTER_KEY) {
                newuser->privKeyKu = netsnmp_memdup(userKey, userKeyLen);
                newuser->privKeyKuLen = userKeyLen;
            }
        }

        /*
         * And turn it into a localized key
         * Allocate enough space for greater of auth mac and privKey len.
         */
        privKeySize = SNMP_MAX(properPrivKeyLen, properLen);
        newuser->privKey = (u_char *) malloc(privKeySize);
        newuser->privKeyLen = privKeySize;

        if (strcmp(buf,"-l") == 0) {
            /* a local key is directly specified */
            cp = copy_nword(cp, buf, sizeof(buf));
            ret = newuser->privKeyLen;
            newuser->privKeyLen = 0;
            if (!snmp_hex_to_binary(&newuser->privKey, &ret,
                                    &newuser->privKeyLen, 0, buf)) {
                *errorMsg = "invalid key value argument to -l";
                goto fail;
            }
        } else {
            ret2 = generate_kul(newuser->authProtocol, newuser->authProtocolLen,
                               newuser->engineID, newuser->engineIDLen,
                               userKey, userKeyLen,
                               newuser->privKey, &newuser->privKeyLen);
            if (ret2 != SNMPERR_SUCCESS) {
                *errorMsg = "could not generate localized privacy key (Kul) from the master key (Ku).";
                goto fail;
            }
        }

        if (newuser->privKeyLen < properPrivKeyLen) {
            ret = usm_extend_user_kul(newuser, properPrivKeyLen);
            if (ret != SNMPERR_SUCCESS) {
                *errorMsg = "could not extend localized privacy key to required length.";
                goto fail;
            }
        }
    }

    if ((newuser->privKeyLen >= properPrivKeyLen) || (properPrivKeyLen == 0)){
        DEBUGMSGTL(("9:usmUser", "truncating privKeyLen from %" NETSNMP_PRIz "d to %d\n",
                    newuser->privKeyLen, properPrivKeyLen));
        newuser->privKeyLen = properPrivKeyLen;
    }
    else {
        DEBUGMSGTL(("usmUser",
                    "privKey length %" NETSNMP_PRIz "d < %d required by privProtocol\n",
                    newuser->privKeyLen, properPrivKeyLen));
      *errorMsg = "privKey length is less than required by privProtocol";
      goto fail;
    }

  add:
    usm_add_user(newuser);
    DEBUGMSGTL(("usmUser", "created a new user %s at ", newuser->secName));
    DEBUGMSGHEX(("usmUser", newuser->engineID, newuser->engineIDLen));
    DEBUGMSG(("usmUser", "\n"));

    return newuser;

  fail:
    usm_free_user(newuser);
    return NULL;
}

void
usm_parse_create_usmUser(const char *token, char *line)
{
    const char *error = NULL;
    usm_create_usmUser_from_string(line, &error);
    if (error)
        config_perror(error);
}

static void
snmpv3_authtype_conf(const char *word, char *cptr)
{
    int auth_type = usm_lookup_auth_type(cptr);
    if (auth_type < 0)
        config_perror("Unknown authentication type");
    defaultAuthType = sc_get_auth_oid(auth_type, &defaultAuthTypeLen);
    DEBUGMSGTL(("snmpv3", "set default authentication type: %s\n", cptr));
}

const oid      *
get_default_authtype(size_t * len)
{
    if (defaultAuthType == NULL) {
        defaultAuthType = SNMP_DEFAULT_AUTH_PROTO;
        defaultAuthTypeLen = SNMP_DEFAULT_AUTH_PROTOLEN;
    }
    if (len)
        *len = defaultAuthTypeLen;
    return defaultAuthType;
}

static void
snmpv3_privtype_conf(const char *word, char *cptr)
{
    int priv_type = usm_lookup_priv_type(cptr);
    if (priv_type < 0)
        config_perror("Unknown privacy type");
    defaultPrivType = sc_get_priv_oid(priv_type, &defaultPrivTypeLen);
    DEBUGMSGTL(("snmpv3", "set default privacy type: %s\n", cptr));
}

const oid      *
get_default_privtype(size_t * len)
{
    if (defaultPrivType == NULL) {
        defaultPrivType = SNMP_DEFAULT_PRIV_PROTO;
        defaultPrivTypeLen = SNMP_DEFAULT_PRIV_PROTOLEN;
    }
    if (len)
        *len = defaultPrivTypeLen;
    return defaultPrivType;
}

void
init_usm_conf(const char *app)
{
    register_config_handler(app, "usmUser",
                                  usm_parse_config_usmUser, NULL, NULL);
    register_config_handler(app, "createUser",
                                  usm_parse_create_usmUser, NULL,
                                  "username [-e ENGINEID] (MD5|SHA|SHA-512|SHA-384|SHA-256|SHA-224|default) authpassphrase [(DES|AES|default) [privpassphrase]]");

    /*
     * we need to be called back later
     */
    snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_STORE_DATA,
                           usm_store_users, NULL);
}

/*
 * initializations for the USM.
 *
 * Should be called after the (engineid) configuration files have been read.
 *
 * Set "arbitrary" portion of salt to a random number.
 */
static int
init_usm_post_config(int majorid, int minorid, void *serverarg,
                     void *clientarg)
{
    size_t          salt_integer_len = sizeof(salt_integer);

    if (sc_random((u_char *) & salt_integer, &salt_integer_len) !=
        SNMPERR_SUCCESS) {
        DEBUGMSGTL(("usm", "sc_random() failed: using time() as salt.\n"));
        salt_integer = (u_int) time(NULL);
    }

#ifdef HAVE_AES
    salt_integer_len = sizeof (salt_integer64_1);
    if (sc_random((u_char *) & salt_integer64_1, &salt_integer_len) !=
        SNMPERR_SUCCESS) {
        DEBUGMSGTL(("usm", "sc_random() failed: using time() as aes1 salt.\n"));
        salt_integer64_1 = (u_int) time(NULL);
    }
    salt_integer_len = sizeof (salt_integer64_1);
    if (sc_random((u_char *) & salt_integer64_2, &salt_integer_len) !=
        SNMPERR_SUCCESS) {
        DEBUGMSGTL(("usm", "sc_random() failed: using time() as aes2 salt.\n"));
        salt_integer64_2 = (u_int) time(NULL);
    }
#endif

#ifndef NETSNMP_DISABLE_MD5
    noNameUser = usm_create_initial_user("", usmHMACMD5AuthProtocol,
                                         OID_LENGTH(usmHMACMD5AuthProtocol),
                                         SNMP_DEFAULT_PRIV_PROTO,
                                         SNMP_DEFAULT_PRIV_PROTOLEN);
#else
    noNameUser = usm_create_initial_user("", usmHMACSHA1AuthProtocol,
                                         OID_LENGTH(usmHMACSHA1AuthProtocol),
                                         SNMP_DEFAULT_PRIV_PROTO,
                                         SNMP_DEFAULT_PRIV_PROTOLEN);
#endif

    if ( noNameUser ) {
        SNMP_FREE(noNameUser->engineID);
        noNameUser->engineIDLen = 0;
    }

    return SNMPERR_SUCCESS;
}                               /* end init_usm_post_config() */

static int
deinit_usm_post_config(int majorid, int minorid, void *serverarg,
		       void *clientarg)
{
    if (usm_free_user(noNameUser) != NULL) {
	DEBUGMSGTL(("deinit_usm_post_config", "could not free initial user\n"));
	return SNMPERR_GENERR;
    }
    noNameUser = NULL;

    DEBUGMSGTL(("deinit_usm_post_config", "initial user removed\n"));
    return SNMPERR_SUCCESS;
}                               /* end deinit_usm_post_config() */

void
init_usm(void)
{
    struct snmp_secmod_def *def;
    char *type;

    DEBUGMSGTL(("init_usm", "unit_usm: %" NETSNMP_PRIo "u %" NETSNMP_PRIo "u\n",
                usmNoPrivProtocol[0], usmNoPrivProtocol[1]));

    sc_init();                  /* initalize scapi code */

    /*
     * register ourselves as a security service
     */
    def = SNMP_MALLOC_STRUCT(snmp_secmod_def);
    if (def == NULL)
        return;
    /*
     * XXX: def->init_sess_secmod move stuff from snmp_api.c
     */
    def->encode_reverse = usm_secmod_rgenerate_out_msg;
    def->encode_forward = usm_secmod_generate_out_msg;
    def->decode = usm_secmod_process_in_msg;
    def->pdu_clone = usm_clone;
    def->pdu_free_state_ref = usm_free_usmStateReference;
    def->session_setup = usm_session_init;
    def->handle_report = usm_handle_report;
    def->probe_engineid = usm_discover_engineid;
    def->post_probe_engineid = usm_create_user_from_session_hook;
    if (register_sec_mod(USM_SEC_MODEL_NUMBER, "usm", def) != SNMPERR_SUCCESS) {
        SNMP_FREE(def);
        snmp_log(LOG_ERR, "could not register usm sec mod\n");
        return;
    }

    snmp_register_callback(SNMP_CALLBACK_LIBRARY,
                           SNMP_CALLBACK_POST_PREMIB_READ_CONFIG,
                           init_usm_post_config, NULL);

    snmp_register_callback(SNMP_CALLBACK_LIBRARY,
                           SNMP_CALLBACK_SHUTDOWN,
                           deinit_usm_post_config, NULL);

    snmp_register_callback(SNMP_CALLBACK_LIBRARY,
                           SNMP_CALLBACK_SHUTDOWN,
                           free_engineID, NULL);

    register_config_handler("snmp", "defAuthType", snmpv3_authtype_conf,
                            NULL, "MD5|SHA|SHA-512|SHA-384|SHA-256|SHA-224");
    register_config_handler("snmp", "defPrivType", snmpv3_privtype_conf,
                            NULL,
                            "DES"
#ifdef HAVE_AES
                            "|AES|AES-128"
#ifdef NETSNMP_DRAFT_BLUMENTHAL_AES_04
                            "|AES-192|AES-256"
#endif /* NETSNMP_DRAFT_BLUMENTHAL_AES_04 */
#else
                            " (AES support not available)"
#endif
                           );

    /*
     * Free stuff at shutdown time
     */
    snmp_register_callback(SNMP_CALLBACK_LIBRARY,
                           SNMP_CALLBACK_SHUTDOWN,
                           free_enginetime_on_shutdown, NULL);


    type = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID, NETSNMP_DS_LIB_APPTYPE);

    register_config_handler(type, "userSetAuthPass", usm_set_password,
                            NULL, NULL);
    register_config_handler(type, "userSetPrivPass", usm_set_password,
                            NULL, NULL);
    register_config_handler(type, "userSetAuthKey", usm_set_password, NULL,
                            NULL);
    register_config_handler(type, "userSetPrivKey", usm_set_password, NULL,
                            NULL);
    register_config_handler(type, "userSetAuthLocalKey", usm_set_password,
                            NULL, NULL);
    register_config_handler(type, "userSetPrivLocalKey", usm_set_password,
                            NULL, NULL);
}

void
shutdown_usm(void)
{
    free_etimelist();
    clear_user_list();
}