/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 *      name.c
 *
 * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 */

#include "dh_gssapi.h"
#include <pwd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/note.h>
#include <thread.h>

extern int
get_der_length(unsigned char **, unsigned int, unsigned int *);

extern unsigned int
der_length_size(unsigned int);

extern int
put_der_length(unsigned int, unsigned char **, unsigned int);

/* Diffie-Hellman ONC RPC netname name type */
static gss_OID_desc __DH_GSS_C_NT_NETNAME_desc =
        { 9,  "\053\006\004\001\052\002\032\001\001" };

const gss_OID_desc * const __DH_GSS_C_NT_NETNAME = &__DH_GSS_C_NT_NETNAME_desc;

#define OID_MAX_NAME_ENTRIES  32

/*
 * __dh_gss_compare_name: Diffie-Hellman machanism support for
 * gss_compare_name. Given two gss_name_ts that are presumed to
 * be rpc netnames set the *equal parameter to true if they are
 * the same, else set it to false.
 */

OM_uint32
__dh_gss_compare_name(void *ctx,        /* Per mechanism context (not used) */
                    OM_uint32 *minor,   /* Mechanism status */
                    gss_name_t name1,   /* First name to compare */
                    gss_name_t name2,   /* Second name to compare */
                    int *equal          /* The result */)
{
_NOTE(ARGUNUSED(ctx))

        if (minor == 0 || equal == 0)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);

        *minor = DH_SUCCESS;

        if (name1 == 0 || name2 == 0) {
                *minor = DH_BADARG_FAILURE;
                return (GSS_S_BAD_NAME | GSS_S_CALL_INACCESSIBLE_READ);
        }

        *equal = (strcmp((char *)name1, (char *)name2) == 0);

        return (GSS_S_COMPLETE);
}

/*
 * __dh_gss_display_name: Supports gss_display_name for Diffie-Hellman
 * mechanism. This takes a gss internal name and converts it to
 * a counted string suitable for display.
 */
OM_uint32
__dh_gss_display_name(void * ctx, /* Per mechanism context (not used) */
                    OM_uint32* minor, /* Mechanism status */
                    gss_name_t name, /* Diffie-Hellman internal name */
                    gss_buffer_t output, /* Were the printable name goes */
                    gss_OID *name_type /* Name type of the internal name */)
{
_NOTE(ARGUNUSED(ctx))

        if (minor == 0 || output == 0)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);

        if (name == 0)
                return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_BAD_NAME);

        *minor = DH_SUCCESS;

        output->length = 0;
        output->value = (void *)strdup((char *)name);
        if (output->value == NULL) {
                *minor = DH_NOMEM_FAILURE;
                return (GSS_S_FAILURE);
        }
        output->length = strlen((char *)name) + 1;

/*
 * Note: we no longer copy the name type OID. The current draft of
 * the standard specifies:
 *
 * "The returned gss_OID will be a pointer into static stoarge
 *  and should be treated as read-only by the caller (in particular,
 *  it does not need to be freed)."
 *
 *      if (name_type) {
 *              if ((*minor = __OID_copy(name_type, __DH_GSS_C_NT_NETNAME))
 *                      != DH_SUCCESS) {
 *                      free(output->value);
 *                      output->value = NULL;
 *                      return (GSS_S_FAILURE);
 *              }
 *      }
 */

        if (name_type)
                *name_type = (gss_OID) __DH_GSS_C_NT_NETNAME;

        return (GSS_S_COMPLETE);
}

/*
 * Routine that takes a netname as a character string and assigns it
 * to a an gss_name_t pointed to by output.
 */
static OM_uint32
do_netname_nametype(OM_uint32 *minor, char *input, gss_name_t *output)
{
        if (__dh_validate_principal(input) != DH_SUCCESS)
                return (GSS_S_BAD_NAME);

        *minor = DH_SUCCESS;
        *output = (gss_name_t)strdup((char *)input);

        if (*output == NULL) {
                *minor = DH_NOMEM_FAILURE;
                return (GSS_S_FAILURE);
        }

        return (GSS_S_COMPLETE);
}

/*
 * do_uid_nametype converts a uid to a gss_name_t pointed to by output
 */
static OM_uint32
do_uid_nametype(OM_uint32 *minor, uid_t uid, gss_name_t *output)
{
        char netname[MAXNETNAMELEN+1];

        if (!user2netname(netname, uid, NULL)) {
                *minor = DH_NETNAME_FAILURE;
                return (GSS_S_FAILURE);
        }
        return (do_netname_nametype(minor, netname, output));
}

/*
 * do_username_nametype converts a username to a gss_name_t pointed to by
 * output.
 *
 * A username will be represented by the following:
 *      name[/node][@security-domain]
 *
 * Then optional security-domain will represent secure rpc domain if
 * present. If not present the local domain will be used. name is the
 * user name as found in the unix password file. If name is root and
 * node is present, then node will represent the host. If the host is
 * a qualified name we assume that it is a DNS name and will only return
 * the first commponnet since we want host name that are relative to
 * the security domain (secure rpc domain).
 */

static OM_uint32
do_username_nametype(OM_uint32 *minor, char *uname, gss_name_t *output)
{
        char netname[MAXNETNAMELEN+1];
        char *user, *node, *domain;
        struct passwd pwd;
        char buff[1024];

        /* Set outputs to sane values */

        *output = 0;
        *minor = DH_SUCCESS;

        /* See if we have a name */
        if (uname == 0) {
                *minor = DH_NO_SUCH_USER;
                return (GSS_S_FAILURE);
        }

        /* copy the name so that we can do surgery on it */
        user = strdup(uname);
        if (user == 0) {
                *minor = DH_NOMEM_FAILURE;
                return (GSS_S_FAILURE);
        }


        /* Look for optional node part */
        node = strchr(user, '/');
        if (node) {
                /*
                 * user is now just the user portion and node
                 * points to the start of the node part.
                 */
                *node++ = '\0';

                /* Now see if there is a domain */
                domain = strchr(node, '@');
        }
        else
                /* Check for a domain */
                domain = strchr(user, '@');

        /* Set domain to the beginning of the domain part if pressent */
        if (domain)
                *domain++ = '\0';

        /*
         * See if the node part is important. If the user is root get
         * the host from the node. If node is not present we assume
         * we're the local host.
         */
        if (strcmp(user, "root") == 0) {
                char *dot;

                /*
                 * We only want the host part of a qualfied host name. We
                 * assume the domain part of a hostname is a DNS domain,
                 * not an rpc domain. The rpc domain can be specified
                 * in the optional security domain part.
                 */
                if (node) {
                        dot = strchr(node, '.');
                        if (dot)
                                *dot = '\0';
                }
                /*
                 * If node is null, assume local host. If domain is
                 * null assume local domain. See host2netname(3NSL)
                 */
                if (!host2netname(netname, node,  domain)) {
                        *minor = DH_NETNAME_FAILURE;
                        free(user);
                        return (GSS_S_FAILURE);
                }
                free(user);
                return (do_netname_nametype(minor, netname, output));
        }

        /*
         * We use getpwnam_r to convert the name to uid.  Note it is
         * important to use getpwnam_r to preserve MT safty.
         */
        if (getpwnam_r(user, &pwd, buff, sizeof (buff)) == NULL) {
                *minor = DH_NO_SUCH_USER;
                free(user);
                return (GSS_S_FAILURE);
        }

        /* If domain is null assume local domain. See user2netname(3NSL) */
        if (!user2netname(netname, pwd.pw_uid, domain)) {
                *minor = DH_NETNAME_FAILURE;
                free(user);
                return (GSS_S_FAILURE);
        }
        free(user);
        return (do_netname_nametype(minor, netname, output));
}

/*
 * do_hostbase_nametype convert a hostbase service name of the form
 *      service@hostname.
 *
 * For Diffie-Hellman we assume that the service is running with the
 * credtials of the machine, i.e., as root.
 */
static OM_uint32
do_hostbase_nametype(OM_uint32 *minor, char *input, gss_name_t *output)
{
        /* Get the nostname */
        char *host = strchr(input, '@');
        char netname[MAXNETNAMELEN+1];


        /* If no host return bad name */
        if (host == NULL)
                return (GSS_S_BAD_NAME);

        /* Advance pass the "@" sign */
        host += 1;

        /* Convert the hostname to its netname */
        if (!host2netname(netname, host, NULL)) {
                *minor = DH_NETNAME_FAILURE;
                return (GSS_S_FAILURE);
        }

        /* Internalize the netname to output */
        return (do_netname_nametype(minor, netname, output));
}

/*
 * do_exported_netname: Convert an exported Diffie-Hellman name
 * to a Diffie-Hellman internal name.
 */
static OM_uint32
do_exported_netname(dh_context_t ctx, /* Diffie-Hellman mech context */
                    OM_uint32 *minor, /* Mech status */
                    gss_buffer_t input, /* The export name to convert */
                    gss_name_t *output /* The converted internal name */)
{
        /* All export names must start with this */
        const char tokid[] = "\x04\x01";
        const int tokid_len = 2;
        const int OIDlen_len = 2;
        const int namelen_len = 4;
        unsigned char *p = (unsigned char *)input->value;
        OM_uint32 len = input->length;
        int      mechoidlen;
        OM_uint32 oidlen; /* includes object tag len & DER len bytes */
        OM_uint32 namelen;
        OM_uint32 currlen;
        OM_uint32 bytes;

        *minor = DH_BADARG_FAILURE;

        /* The len must be at least this big */
        if (len < tokid_len + OIDlen_len + namelen_len)
                return (GSS_S_DEFECTIVE_TOKEN);

        /* Export names must start with the token id of 0x04 0x01 */
        if (memcmp(p, tokid, tokid_len) != 0)
                return (GSS_S_DEFECTIVE_TOKEN);
        p += tokid_len;

        /* Decode the Mechanism oid */
        oidlen = (*p++ << 8) & 0xff00;
        oidlen |= *p++ & 0xff;

        /* Check that we actually have the mechanism oid elements */
        if (len < tokid_len + OIDlen_len + oidlen + namelen_len)
                return (GSS_S_DEFECTIVE_TOKEN);

        /* Compare that the input is for this mechanism */
        if (*p++ != 0x06)
                return (GSS_S_DEFECTIVE_TOKEN);
        currlen = len - (tokid_len + OIDlen_len + oidlen + namelen_len);
        if ((mechoidlen = get_der_length(&p, currlen, &bytes)) < 0)
                return (GSS_S_DEFECTIVE_TOKEN);
        if (mechoidlen != ctx->mech->length)
                return (GSS_S_DEFECTIVE_TOKEN);
        if (memcmp(p, ctx->mech->elements, mechoidlen) != 0)
                return (GSS_S_DEFECTIVE_TOKEN);
        p += mechoidlen;

        /* Grab the length of the mechanism specific name per RFC 2078 */
        namelen = (*p++ << 24) & 0xff000000;
        namelen |= (*p++ << 16) & 0xff0000;
        namelen |= (*p++ << 8) & 0xff00;
        namelen |= *p++ & 0xff;

        /* This should alway be false */
        if (len < tokid_len + OIDlen_len + oidlen + namelen_len + namelen)
                return (GSS_S_DEFECTIVE_TOKEN);

        /* Make sure the bytes for the netname oid length are available */
        if (namelen < OIDlen_len)
                return (GSS_S_DEFECTIVE_TOKEN);

        /* Get the netname oid length */
        oidlen = (*p++ << 8) & 0xff00;
        oidlen = *p++ & 0xff;

        /* See if we have the elements of the netname oid */
        if (namelen < OIDlen_len + oidlen)
                return (GSS_S_DEFECTIVE_TOKEN);

        /* Check that the oid is really a netname */
        if (oidlen != __DH_GSS_C_NT_NETNAME->length)
                return (GSS_S_DEFECTIVE_TOKEN);
        if (memcmp(p, __DH_GSS_C_NT_NETNAME->elements,
            __DH_GSS_C_NT_NETNAME->length) != 0)
                return (GSS_S_DEFECTIVE_TOKEN);

        /* p now points to the netname wich is null terminated */
        p += oidlen;

        /*
         * How the netname is encoded in an export name type for
         * this mechanism. See _dh_gss_export_name below.
         */

        if (namelen != OIDlen_len + oidlen + strlen((char *)p) + 1)
                return (GSS_S_DEFECTIVE_TOKEN);

        /* Grab the netname */
        *output = (gss_name_t)strdup((char *)p);
        if (*output) {
                *minor = 0;
                return (GSS_S_COMPLETE);
        }

        *minor = DH_NOMEM_FAILURE;
        return (GSS_S_FAILURE);
}

/*
 * __dh_gss_import_name: Diffie-Hellman entry point for gss_import_name.
 * Given an input name of a specified name type, convert this to a
 * Diffie-Hellman internal name (netname).
 *
 * The idea here is simply compare the name_type supplied with each
 * name type that we know how to deal with. If we have a match we call
 * the appropriate support routine form above. If we done't have a match
 * we return GSS_S_BAD_NAMETYPE
 */
OM_uint32
__dh_gss_import_name(void *ctx, /* Per mechanism context */
                    OM_uint32 *minor, /* Mechanism status */
                    gss_buffer_t input, /* The name to convert */
                    gss_OID name_type, /* of this name_type */
                    gss_name_t *output /* The converted name */)
{
        char *name;
        OM_uint32 stat;

        if (minor == NULL || output == NULL)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);

        if (input == NULL || input->value == NULL)
                return (GSS_S_BAD_NAME | GSS_S_CALL_INACCESSIBLE_READ);
        if (name_type == GSS_C_NO_OID)
                return (GSS_S_BAD_NAMETYPE);

        /* Set sane state */
        *minor = DH_SUCCESS;
        *output = GSS_C_NO_NAME;

                /* UID in machine format */
        if (__OID_equal(name_type, GSS_C_NT_MACHINE_UID_NAME)) {
                uid_t uid;
                if (input->length != sizeof (uid_t))
                        return (GSS_S_BAD_NAME);
                uid = *(uid_t *)input->value;
                /* Should we assume that the id is network byte order ??? */
                /* uid = htonl(uid); No, this should be the local orfering */
                return (do_uid_nametype(minor, uid, output));

                /* Name that was exported with __dh_gss_export_name */
        } else if (__OID_equal(name_type, GSS_C_NT_EXPORT_NAME)) {
                stat = do_exported_netname((dh_context_t)ctx, minor,
                    input, output);
                return (stat);
        }

        /* Null ternamte name so we can manipulate as a c-style string */
        name = malloc(input->length+1);
        if (name == NULL) {
                *minor = DH_NOMEM_FAILURE;
                return (GSS_S_FAILURE);
        }
        memcpy(name, input->value, input->length);
        name[input->length] = '\0';


                /* Diffie-Hellman (ONC RPC netname) */
        if (__OID_equal(name_type, __DH_GSS_C_NT_NETNAME)) {
                stat = do_netname_nametype(minor, name, output);
                free(name);
                return (stat);
                /* Host based service name (service@hostname) */
        } else if (__OID_equal(name_type, GSS_C_NT_HOSTBASED_SERVICE)) {
                stat = do_hostbase_nametype(minor, name, output);
                free(name);
                return (stat);
                /* Thus local OS user name */
        } else if (__OID_equal(name_type, GSS_C_NT_USER_NAME)) {
                stat = do_username_nametype(minor, name, output);
                free(name);
                return (stat);
                /* The os user id writen as a string */
        } else if (__OID_equal(name_type, GSS_C_NT_STRING_UID_NAME)) {
                char *p;
                /* Convert the name to a uid */
                uid_t uid = (uid_t)strtol(name, &p, 0);
                free(name);
                if (*p != '\0')
                        return (GSS_S_BAD_NAME);
                return (do_uid_nametype(minor, uid, output));
        } else {
                /* Any thing else */
                free(name);
                return (GSS_S_BAD_NAMETYPE);
        }
}

/*
 * __dh_gss_release_name: DH entry point for gss_release_name.
 * Release an internal DH name.
 */
OM_uint32
__dh_gss_release_name(void *ctx, OM_uint32 *minor, gss_name_t *name)
{
_NOTE(ARGUNUSED(ctx))

        if (minor == 0 || name == 0)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);

        *minor = DH_SUCCESS;

        free(*name);
        *name = GSS_C_NO_NAME;

        return (GSS_S_COMPLETE);
}

/* Lock for initializing oid_name_tab */
static mutex_t name_tab_lock = DEFAULTMUTEX;

/* Table of name types that this mechanism understands */
static const gss_OID_desc * oid_name_tab[OID_MAX_NAME_ENTRIES];

/*
 * __dh_gss_inquire_names_for_mech: DH entry point for
 * gss_inquire_names_for_mech.
 *
 * Return a set of OID name types that a mechanism can understand
 */
OM_uint32
__dh_gss_inquire_names_for_mech(void *ctx, OM_uint32 *minor,
    gss_OID mech, gss_OID_set *names)
{
_NOTE(ARGUNUSED(ctx,mech))

        /* See if we need to initialize the table */
        if (oid_name_tab[0] == 0) {
                mutex_lock(&name_tab_lock);
                /* If nobody sneaked in, initialize the table */
                if (oid_name_tab[0] == 0) {
                        oid_name_tab[0] = __DH_GSS_C_NT_NETNAME;
                        oid_name_tab[1] = GSS_C_NT_HOSTBASED_SERVICE;
                        oid_name_tab[2] = GSS_C_NT_USER_NAME;
                        oid_name_tab[3] = GSS_C_NT_MACHINE_UID_NAME;
                        oid_name_tab[4] = GSS_C_NT_STRING_UID_NAME;
                        oid_name_tab[5] = GSS_C_NT_EXPORT_NAME;
                        /* oid_name_tab[6] = GSS_C_NT_ANONYMOUS_NAME; */
                }
                mutex_unlock(&name_tab_lock);
        }

        /* Return the set of OIDS from the table */
        if ((*minor = __OID_copy_set_from_array(names,
            oid_name_tab, 6)) != DH_SUCCESS)
                return (GSS_S_FAILURE);

        return (GSS_S_COMPLETE);
}


/*
 * Private libgss entry point to convert a principal name to uid.
 */
OM_uint32
__dh_pname_to_uid(void *ctx, /* DH mech context (not used) */
                OM_uint32 *minor, /* Mech status */
                const gss_name_t pname, /* principal */
                uid_t *uid  /* where to put the uid */)
{
_NOTE(ARGUNUSED(ctx))

        gid_t gid;
        gid_t glist[NGRPS];
        int glen;
        /* Convert the principal name to a netname */
        char *netname = (char *)pname;
        char host_netname[MAXNETNAMELEN+1];

        if (pname == 0)
                return (GSS_S_BAD_NAME | GSS_S_CALL_INACCESSIBLE_READ);
        if (minor == 0 || uid == 0)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);

        *minor = DH_SUCCESS;
        *uid = UID_NOBODY;

        /* First try to convert as a user */
        if (netname2user(netname, uid, &gid, &glen, glist))
                return (GSS_S_COMPLETE);
        /* Get this hosts netname */
        else if (host2netname(host_netname, NULL, NULL)) {
                /*
                 * If the netname is this host's netname then we're root
                 * else we're nobody.
                 */
                if (strncmp(netname, host_netname, MAXNETNAMELEN) == 0)
                        *uid = 0;
                return (GSS_S_COMPLETE);
        }

        /* We could not get a netname */
        *minor = DH_NETNAME_FAILURE;
        return (GSS_S_FAILURE);
}

/*
 * __dh_gss_export_name: Diffie-Hellman support for gss_export_name.
 * Given a Diffie-Hellman internal name return the GSS exported format.
 */
OM_uint32
__dh_gss_export_name(void *ctx, /* Per mechanism context */
                    OM_uint32 *minor, /* Mechanism status */
                    const gss_name_t input_name, /* The name to export */
                    gss_buffer_t exported_name /* Exported name goes here */)
{
        /* input_name is dh principal name */
        dh_principal pname = (dh_principal)input_name;
        dh_context_t dc = (dh_context_t)ctx;
        /* Magic for exported blobs */
        const char tokid[] = "\x04\x01";
        const int tokid_len = 2;
        const int OIDlen_len = 2; /* Why did they do this? */
        const int namelen_len = 4;
        const int mechoid_tag_len = 1;
        unsigned char *p;
        OM_uint32 len;
        OM_uint32 namelen;
        OM_uint32 currlen;
        OM_uint32 oid_der_len = 0;

        if (minor == 0 || exported_name == GSS_C_NO_BUFFER)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);
        if (input_name == GSS_C_NO_NAME)
                return (GSS_S_CALL_INACCESSIBLE_READ);

        /* Set sane outputs */
        *minor = DH_SUCCESS;
        exported_name->length = 0;
        exported_name->value = NULL;

        /* Determine the length of the name */
        namelen = OIDlen_len + __DH_GSS_C_NT_NETNAME->length
            + strlen(pname)+1;
        oid_der_len = der_length_size(dc->mech->length);
        /* Find the total length */
        len = tokid_len + OIDlen_len + mechoid_tag_len + oid_der_len
                + dc->mech->length + namelen_len + namelen;

        /* Allocate the blob */
        p = New(unsigned char, len);
        if (p == NULL) {
                *minor = DH_NOMEM_FAILURE;
                return (GSS_S_FAILURE);
        }
        /* Set the blob to the exported name */
        exported_name->length = len;
        exported_name->value = p;

        /* Start with some magic */
        memcpy(p, tokid, tokid_len);
        p += tokid_len;

        /*
         * The spec only allows two bytes for the oid length.
         * We are assuming here that the correct encodeing is MSB first as
         * was done in libgss.
         */

        *p++ = ((mechoid_tag_len + oid_der_len + dc->mech->length)
                        & 0xff00) >> 8;
        *p++ = ((mechoid_tag_len + oid_der_len + dc->mech->length)
                        & 0x00ff);

        /* Now the mechanism OID DER Encoding */
        *p++ = 0x06; /* Universal Tag for OID */
        currlen = len - tokid_len - OIDlen_len - mechoid_tag_len;
        if (!put_der_length(dc->mech->length, &p, currlen) == 0) {
                return (GSS_S_FAILURE);
        }

        /* Now the mechanism OID elements */
        memcpy(p, dc->mech->elements, dc->mech->length);
        p += dc->mech->length;

        /* The name length most MSB first */
        *p++ = (namelen & 0xff000000) >> 24;
        *p++ = (namelen & 0x00ff0000) >> 16;
        *p++ = (namelen & 0x0000ff00) >> 8;
        *p++ = (namelen & 0x000000ff);

        /*
         * We'll now encode the netname oid. Again we'll just use 2 bytes.
         * This is the same encoding that the libgss implementor uses, so
         * we'll just follow along.
         */

        *p++ = (__DH_GSS_C_NT_NETNAME->length & 0xff00) >> 8;
        *p++ = (__DH_GSS_C_NT_NETNAME->length &0x00ff);

        /* The netname oid values */
        memcpy(p, __DH_GSS_C_NT_NETNAME->elements,
            __DH_GSS_C_NT_NETNAME->length);

        p += __DH_GSS_C_NT_NETNAME->length;

        /* Now we copy the netname including the null byte to be safe */
        memcpy(p, pname, strlen(pname) + 1);

        return (GSS_S_COMPLETE);
}

/*
 * Support routine for __dh_internal_release_oid. Return True if
 * the supplied OID points to the reference OID or if the elements
 * of the reference OID are the same as the supplied OID. In the
 * latter case, just free the OID container and set the pointer to it
 * to GSS_C_NO_OID. Otherwise return false
 */
static int
release_oid(const gss_OID_desc * const ref, gss_OID *oid)
{
        gss_OID id = *oid;

        if (id == ref)
                return (TRUE);

        /*
         * If some on create a shallow copy free, the structure point to
         * id and set the pointer to it to GSS_C_NO_OID
         */
        if (id->elements == ref->elements) {
                Free(id);
                *oid = GSS_C_NO_OID;
                return (TRUE);
        }

        return (FALSE);
}

/*
 * __dh_gss_internal_release_oid: DH support for the gss_internal_relaese_oid
 * entry. Check that the refence to an oid is one of our mechanisms static
 * OIDS. If it is return true indicating to libgss that we have handled the
 * release of that OID. Otherwise we return false and let libgss deal with it.
 *
 * The only OIDS we know are the calling mechanism found in the context
 * and the shared DH_GSS_C_NT_NETNAME name type
 */
OM_uint32
__dh_gss_internal_release_oid(void *ctx, OM_uint32 *minor, gss_OID *oid)
{
        dh_context_t dhcxt = (dh_context_t)ctx;

        if (minor == 0)
                return (GSS_S_CALL_INACCESSIBLE_WRITE);

        *minor = DH_SUCCESS;

        if (oid == NULL || *oid == NULL)
                return (GSS_S_COMPLETE);

        if (release_oid(dhcxt->mech, oid))
                return (GSS_S_COMPLETE);

        if (release_oid(__DH_GSS_C_NT_NETNAME, oid))
                return (GSS_S_COMPLETE);

        return (GSS_S_FAILURE);
}