spnego.c

Go to the documentation of this file.

/*
 * Copyright (C) 2006-2015  Internet Systems Consortium, Inc. ("ISC")
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id$ */

/*! \file
 * \brief
 * Portable SPNEGO implementation.
 *
 * This is part of a portable implementation of the SPNEGO protocol
 * (RFCs 2478 and 4178).  This implementation uses the RFC 4178 ASN.1
 * module but is not a full implementation of the RFC 4178 protocol;
 * at the moment, we only support GSS-TSIG with Kerberos
 * authentication, so we only need enough of the SPNEGO protocol to
 * support that.
 *
 * The files that make up this portable SPNEGO implementation are:
 * \li  spnego.c        (this file)
 * \li  spnego.h        (API SPNEGO exports to the rest of lib/dns)
 * \li  spnego.asn1     (SPNEGO ASN.1 module)
 * \li  spnego_asn1.c   (routines generated from spngo.asn1)
 * \li  spnego_asn1.pl  (perl script to generate spnego_asn1.c)
 *
 * Everything but the functions exported in spnego.h is static, to
 * avoid possible conflicts with other libraries (particularly Heimdal,
 * since much of this code comes from Heimdal by way of mod_auth_kerb).
 *
 * spnego_asn1.c is shipped as part of lib/dns because generating it
 * requires both Perl and the Heimdal ASN.1 compiler.  See
 * spnego_asn1.pl for further details.  We've tried to eliminate all
 * compiler warnings from the generated code, but you may see a few
 * when using a compiler version we haven't tested yet.
 */

/*
 * Portions of this code were derived from mod_auth_kerb and Heimdal.
 * These packages are available from:
 *
 *   http://modauthkerb.sourceforge.net/
 *   http://www.pdc.kth.se/heimdal/
 *
 * and were released under the following licenses:
 *
 * ----------------------------------------------------------------
 *
 * Copyright (c) 2004 Masarykova universita
 * (Masaryk University, Brno, Czech Republic)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the University nor the names of its contributors may
 *    be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * ----------------------------------------------------------------
 *
 * Copyright (c) 1997 - 2003 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * XXXSRA We should omit this file entirely in Makefile.in via autoconf,
 * but this will keep it from generating errors until that's written.
 */

#ifdef GSSAPI

/*
 * XXXSRA Some of the following files are almost certainly unnecessary,
 * but using this list (borrowed from gssapictx.c) gets rid of some
 * whacky compilation errors when building with MSVC and should be
 * harmless in any case.
 */

#include <config.h>

#include <stdlib.h>
#include <errno.h>

#include <isc/buffer.h>
#include <isc/dir.h>
#include <isc/entropy.h>
#include <isc/lex.h>
#include <isc/mem.h>
#include <isc/once.h>
#include <isc/random.h>
#include <isc/string.h>
#include <isc/time.h>
#include <isc/util.h>

#include <dns/fixedname.h>
#include <dns/name.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/result.h>
#include <dns/types.h>
#include <dns/keyvalues.h>
#include <dns/log.h>

#include <dst/gssapi.h>
#include <dst/result.h>

#include "dst_internal.h"

/*
 * The API we export
 */
#include "spnego.h"

/* asn1_err.h */
/* Generated from ../../../lib/asn1/asn1_err.et */

#ifndef ERROR_TABLE_BASE_asn1
/* these may be brought in already via gssapi_krb5.h */
typedef enum asn1_error_number {
        ASN1_BAD_TIMEFORMAT = 1859794432,
        ASN1_MISSING_FIELD = 1859794433,
        ASN1_MISPLACED_FIELD = 1859794434,
        ASN1_TYPE_MISMATCH = 1859794435,
        ASN1_OVERFLOW = 1859794436,
        ASN1_OVERRUN = 1859794437,
        ASN1_BAD_ID = 1859794438,
        ASN1_BAD_LENGTH = 1859794439,
        ASN1_BAD_FORMAT = 1859794440,
        ASN1_PARSE_ERROR = 1859794441
} asn1_error_number;

#define ERROR_TABLE_BASE_asn1 1859794432
#endif

#define __asn1_common_definitions__

typedef struct octet_string {
        size_t length;
        void *data;
} octet_string;

typedef char *general_string;

typedef char *utf8_string;

typedef struct oid {
        size_t length;
        unsigned *components;
} oid;

/* der.h */

typedef enum {
        ASN1_C_UNIV = 0, ASN1_C_APPL = 1,
        ASN1_C_CONTEXT = 2, ASN1_C_PRIVATE = 3
} Der_class;

typedef enum {
        PRIM = 0, CONS = 1
} Der_type;

/* Universal tags */

enum {
        UT_Boolean = 1,
        UT_Integer = 2,
        UT_BitString = 3,
        UT_OctetString = 4,
        UT_Null = 5,
        UT_OID = 6,
        UT_Enumerated = 10,
        UT_Sequence = 16,
        UT_Set = 17,
        UT_PrintableString = 19,
        UT_IA5String = 22,
        UT_UTCTime = 23,
        UT_GeneralizedTime = 24,
        UT_VisibleString = 26,
        UT_GeneralString = 27
};

#define ASN1_INDEFINITE 0xdce0deed

static int
der_get_length(const unsigned char *p, size_t len,
               size_t * val, size_t * size);

static int
der_get_octet_string(const unsigned char *p, size_t len,
                     octet_string * data, size_t * size);
static int
der_get_oid(const unsigned char *p, size_t len,
            oid * data, size_t * size);
static int
der_get_tag(const unsigned char *p, size_t len,
            Der_class * class, Der_type * type,
            int *tag, size_t * size);

static int
der_match_tag(const unsigned char *p, size_t len,
              Der_class class, Der_type type,
              int tag, size_t * size);
static int
der_match_tag_and_length(const unsigned char *p, size_t len,
                         Der_class class, Der_type type, int tag,
                         size_t * length_ret, size_t * size);

static int
decode_oid(const unsigned char *p, size_t len,
           oid * k, size_t * size);

static int
decode_enumerated(const unsigned char *p, size_t len, void *num, size_t *size);

static int
decode_octet_string(const unsigned char *, size_t, octet_string *, size_t *);

static int
der_put_int(unsigned char *p, size_t len, int val, size_t *);

static int
der_put_length(unsigned char *p, size_t len, size_t val, size_t *);

static int
der_put_octet_string(unsigned char *p, size_t len,
                     const octet_string * data, size_t *);
static int
der_put_oid(unsigned char *p, size_t len,
            const oid * data, size_t * size);
static int
der_put_tag(unsigned char *p, size_t len, Der_class class, Der_type type,
            int tag, size_t *);
static int
der_put_length_and_tag(unsigned char *, size_t, size_t,
                       Der_class, Der_type, int, size_t *);

static int
encode_enumerated(unsigned char *p, size_t len, const void *data, size_t *);

static int
encode_octet_string(unsigned char *p, size_t len,
                    const octet_string * k, size_t *);
static int
encode_oid(unsigned char *p, size_t len,
           const oid * k, size_t *);

static void
free_octet_string(octet_string * k);

static void
free_oid  (oid * k);

static size_t
length_len(size_t len);

static int
fix_dce(size_t reallen, size_t * len);

/*
 * Include stuff generated by the ASN.1 compiler.
 */

#include "spnego_asn1.c"

static unsigned char gss_krb5_mech_oid_bytes[] = {
        0x2a, 0x86, 0x48, 0x86, 0xf7, 0x12, 0x01, 0x02, 0x02
};

static gss_OID_desc gss_krb5_mech_oid_desc = {
        sizeof(gss_krb5_mech_oid_bytes),
        gss_krb5_mech_oid_bytes
};

static gss_OID GSS_KRB5_MECH = &gss_krb5_mech_oid_desc;

static unsigned char gss_mskrb5_mech_oid_bytes[] = {
        0x2a, 0x86, 0x48, 0x82, 0xf7, 0x12, 0x01, 0x02, 0x02
};

static gss_OID_desc gss_mskrb5_mech_oid_desc = {
        sizeof(gss_mskrb5_mech_oid_bytes),
        gss_mskrb5_mech_oid_bytes
};

static gss_OID GSS_MSKRB5_MECH = &gss_mskrb5_mech_oid_desc;

static unsigned char gss_spnego_mech_oid_bytes[] = {
        0x2b, 0x06, 0x01, 0x05, 0x05, 0x02
};

static gss_OID_desc gss_spnego_mech_oid_desc = {
        sizeof(gss_spnego_mech_oid_bytes),
        gss_spnego_mech_oid_bytes
};

static gss_OID GSS_SPNEGO_MECH = &gss_spnego_mech_oid_desc;

/* spnegokrb5_locl.h */

static OM_uint32
gssapi_spnego_encapsulate(OM_uint32 *,
                          unsigned char *,
                          size_t,
                          gss_buffer_t,
                          const gss_OID);

static OM_uint32
gssapi_spnego_decapsulate(OM_uint32 *,
                          gss_buffer_t,
                          unsigned char **,
                          size_t *,
                          const gss_OID);

/* mod_auth_kerb.c */

static int
cmp_gss_type(gss_buffer_t token, gss_OID gssoid)
{
        unsigned char *p;
        size_t len;

        if (token->length == 0U)
                return (GSS_S_DEFECTIVE_TOKEN);

        p = token->value;
        if (*p++ != 0x60)
                return (GSS_S_DEFECTIVE_TOKEN);
        len = *p++;
        if (len & 0x80) {
                if ((len & 0x7f) > 4U)
                        return (GSS_S_DEFECTIVE_TOKEN);
                p += len & 0x7f;
        }
        if (*p++ != 0x06)
                return (GSS_S_DEFECTIVE_TOKEN);

        if (((OM_uint32) *p++) != gssoid->length)
                return (GSS_S_DEFECTIVE_TOKEN);

        return (memcmp(p, gssoid->elements, gssoid->length));
}

/* accept_sec_context.c */
/*
 * SPNEGO wrapper for Kerberos5 GSS-API kouril@ics.muni.cz, 2003 (mostly
 * based on Heimdal code)
 */

static OM_uint32
code_NegTokenArg(OM_uint32 * minor_status,
                 const NegTokenResp * resp,
                 unsigned char **outbuf,
                 size_t * outbuf_size)
{
        OM_uint32 ret;
        u_char *buf;
        size_t buf_size, buf_len = 0;

        buf_size = 1024;
        buf = malloc(buf_size);
        if (buf == NULL) {
                *minor_status = ENOMEM;
                return (GSS_S_FAILURE);
        }
        do {
                ret = encode_NegTokenResp(buf + buf_size - 1,
                                          buf_size,
                                          resp, &buf_len);
                if (ret == 0) {
                        size_t tmp;

                        ret = der_put_length_and_tag(buf + buf_size - buf_len - 1,
                                                     buf_size - buf_len,
                                                     buf_len,
                                                     ASN1_C_CONTEXT,
                                                     CONS,
                                                     1,
                                                     &tmp);
                        if (ret == 0)
                                buf_len += tmp;
                }
                if (ret) {
                        if (ret == ASN1_OVERFLOW) {
                                u_char *tmp;

                                buf_size *= 2;
                                tmp = realloc(buf, buf_size);
                                if (tmp == NULL) {
                                        *minor_status = ENOMEM;
                                        free(buf);
                                        return (GSS_S_FAILURE);
                                }
                                buf = tmp;
                        } else {
                                *minor_status = ret;
                                free(buf);
                                return (GSS_S_FAILURE);
                        }
                }
        } while (ret == ASN1_OVERFLOW);

        *outbuf = malloc(buf_len);
        if (*outbuf == NULL) {
                *minor_status = ENOMEM;
                free(buf);
                return (GSS_S_FAILURE);
        }
        memmove(*outbuf, buf + buf_size - buf_len, buf_len);
        *outbuf_size = buf_len;

        free(buf);

        return (GSS_S_COMPLETE);
}

static OM_uint32
send_reject(OM_uint32 * minor_status,
            gss_buffer_t output_token)
{
        NegTokenResp resp;
        OM_uint32 ret;

        resp.negState = malloc(sizeof(*resp.negState));
        if (resp.negState == NULL) {
                *minor_status = ENOMEM;
                return (GSS_S_FAILURE);
        }
        *(resp.negState) = reject;

        resp.supportedMech = NULL;
        resp.responseToken = NULL;
        resp.mechListMIC = NULL;

        ret = code_NegTokenArg(minor_status, &resp,
                               (unsigned char **)&output_token->value,
                               &output_token->length);
        free_NegTokenResp(&resp);
        if (ret)
                return (ret);

        return (GSS_S_BAD_MECH);
}

static OM_uint32
send_accept(OM_uint32 * minor_status,
            gss_buffer_t output_token,
            gss_buffer_t mech_token,
            const gss_OID pref)
{
        NegTokenResp resp;
        OM_uint32 ret;

        memset(&resp, 0, sizeof(resp));
        resp.negState = malloc(sizeof(*resp.negState));
        if (resp.negState == NULL) {
                *minor_status = ENOMEM;
                return (GSS_S_FAILURE);
        }
        *(resp.negState) = accept_completed;

        resp.supportedMech = malloc(sizeof(*resp.supportedMech));
        if (resp.supportedMech == NULL) {
                free_NegTokenResp(&resp);
                *minor_status = ENOMEM;
                return (GSS_S_FAILURE);
        }
        ret = der_get_oid(pref->elements,
                          pref->length,
                          resp.supportedMech,
                          NULL);
        if (ret) {
                free_NegTokenResp(&resp);
                *minor_status = ENOMEM;
                return (GSS_S_FAILURE);
        }
        if (mech_token != NULL && mech_token->length != 0U) {
                resp.responseToken = malloc(sizeof(*resp.responseToken));
                if (resp.responseToken == NULL) {
                        free_NegTokenResp(&resp);
                        *minor_status = ENOMEM;
                        return (GSS_S_FAILURE);
                }
                resp.responseToken->length = mech_token->length;
                resp.responseToken->data = mech_token->value;
        }

        ret = code_NegTokenArg(minor_status, &resp,
                               (unsigned char **)&output_token->value,
                               &output_token->length);
        if (resp.responseToken != NULL) {
                free(resp.responseToken);
                resp.responseToken = NULL;
        }
        free_NegTokenResp(&resp);
        if (ret)
                return (ret);

        return (GSS_S_COMPLETE);
}

OM_uint32
gss_accept_sec_context_spnego(OM_uint32 *minor_status,
                              gss_ctx_id_t *context_handle,
                              const gss_cred_id_t acceptor_cred_handle,
                              const gss_buffer_t input_token_buffer,
                              const gss_channel_bindings_t input_chan_bindings,
                              gss_name_t *src_name,
                              gss_OID *mech_type,
                              gss_buffer_t output_token,
                              OM_uint32 *ret_flags,
                              OM_uint32 *time_rec,
                              gss_cred_id_t *delegated_cred_handle)
{
        NegTokenInit init_token;
        OM_uint32 major_status;
        OM_uint32 minor_status2;
        gss_buffer_desc ibuf, obuf;
        gss_buffer_t ot = NULL;
        gss_OID pref = GSS_KRB5_MECH;
        unsigned char *buf;
        size_t buf_size;
        size_t len, taglen, ni_len;
        int found = 0;
        int ret;
        unsigned i;

        /*
         * Before doing anything else, see whether this is a SPNEGO
         * PDU.  If not, dispatch to the GSSAPI library and get out.
         */

        if (cmp_gss_type(input_token_buffer, GSS_SPNEGO_MECH))
                return (gss_accept_sec_context(minor_status,
                                               context_handle,
                                               acceptor_cred_handle,
                                               input_token_buffer,
                                               input_chan_bindings,
                                               src_name,
                                               mech_type,
                                               output_token,
                                               ret_flags,
                                               time_rec,
                                               delegated_cred_handle));

        /*
         * If we get here, it's SPNEGO.
         */

        memset(&init_token, 0, sizeof(init_token));

        ret = gssapi_spnego_decapsulate(minor_status, input_token_buffer,
                                        &buf, &buf_size, GSS_SPNEGO_MECH);
        if (ret)
                return (ret);

        ret = der_match_tag_and_length(buf, buf_size, ASN1_C_CONTEXT, CONS,
                                       0, &len, &taglen);
        if (ret)
                return (ret);

        ret = decode_NegTokenInit(buf + taglen, len, &init_token, &ni_len);
        if (ret) {
                *minor_status = EINVAL; /* XXX */
                return (GSS_S_DEFECTIVE_TOKEN);
        }

        for (i = 0; !found && i < init_token.mechTypes.len; ++i) {
                unsigned char mechbuf[17];
                size_t mech_len;

                ret = der_put_oid(mechbuf + sizeof(mechbuf) - 1,
                                  sizeof(mechbuf),
                                  &init_token.mechTypes.val[i],
                                  &mech_len);
                if (ret) {
                        free_NegTokenInit(&init_token);
                        return (GSS_S_DEFECTIVE_TOKEN);
                }
                if (mech_len == GSS_KRB5_MECH->length &&
                    memcmp(GSS_KRB5_MECH->elements,
                           mechbuf + sizeof(mechbuf) - mech_len,
                           mech_len) == 0) {
                        found = 1;
                        break;
                }
                if (mech_len == GSS_MSKRB5_MECH->length &&
                    memcmp(GSS_MSKRB5_MECH->elements,
                           mechbuf + sizeof(mechbuf) - mech_len,
                           mech_len) == 0) {
                        found = 1;
                        if (i == 0)
                                pref = GSS_MSKRB5_MECH;
                        break;
                }
        }

        if (!found) {
                free_NegTokenInit(&init_token);
                return (send_reject(minor_status, output_token));
        }

        if (i == 0 && init_token.mechToken != NULL) {
                ibuf.length = init_token.mechToken->length;
                ibuf.value = init_token.mechToken->data;

                major_status = gss_accept_sec_context(minor_status,
                                                      context_handle,
                                                      acceptor_cred_handle,
                                                      &ibuf,
                                                      input_chan_bindings,
                                                      src_name,
                                                      mech_type,
                                                      &obuf,
                                                      ret_flags,
                                                      time_rec,
                                                      delegated_cred_handle);
                if (GSS_ERROR(major_status)) {
                        free_NegTokenInit(&init_token);
                        send_reject(&minor_status2, output_token);
                        return (major_status);
                }
                ot = &obuf;
        }
        ret = send_accept(&minor_status2, output_token, ot, pref);
        free_NegTokenInit(&init_token);
        if (ot != NULL && ot->length != 0U)
                gss_release_buffer(&minor_status2, ot);

        return (ret);
}

/* decapsulate.c */

static OM_uint32
gssapi_verify_mech_header(u_char ** str,
                          size_t total_len,
                          const gss_OID mech)
{
        size_t len, len_len, mech_len, foo;
        int e;
        u_char *p = *str;

        if (total_len < 1U)
                return (GSS_S_DEFECTIVE_TOKEN);
        if (*p++ != 0x60)
                return (GSS_S_DEFECTIVE_TOKEN);
        e = der_get_length(p, total_len - 1, &len, &len_len);
        if (e || 1 + len_len + len != total_len)
                return (GSS_S_DEFECTIVE_TOKEN);
        p += len_len;
        if (*p++ != 0x06)
                return (GSS_S_DEFECTIVE_TOKEN);
        e = der_get_length(p, total_len - 1 - len_len - 1,
                           &mech_len, &foo);
        if (e)
                return (GSS_S_DEFECTIVE_TOKEN);
        p += foo;
        if (mech_len != mech->length)
                return (GSS_S_BAD_MECH);
        if (memcmp(p, mech->elements, mech->length) != 0)
                return (GSS_S_BAD_MECH);
        p += mech_len;
        *str = p;
        return (GSS_S_COMPLETE);
}

/*
 * Remove the GSS-API wrapping from `in_token' giving `buf and buf_size' Does
 * not copy data, so just free `in_token'.
 */

static OM_uint32
gssapi_spnego_decapsulate(OM_uint32 *minor_status,
                          gss_buffer_t input_token_buffer,
                          unsigned char **buf,
                          size_t *buf_len,
                          const gss_OID mech)
{
        u_char *p;
        OM_uint32 ret;

        p = input_token_buffer->value;
        ret = gssapi_verify_mech_header(&p,
                                        input_token_buffer->length,
                                        mech);
        if (ret) {
                *minor_status = ret;
                return (GSS_S_FAILURE);
        }
        *buf_len = input_token_buffer->length -
                (p - (u_char *) input_token_buffer->value);
        *buf = p;
        return (GSS_S_COMPLETE);
}

/* der_free.c */

static void
free_octet_string(octet_string *k)
{
        free(k->data);
        k->data = NULL;
}

static void
free_oid(oid *k)
{
        free(k->components);
        k->components = NULL;
}

/* der_get.c */

/*
 * All decoding functions take a pointer `p' to first position in which to
 * read, from the left, `len' which means the maximum number of characters we
 * are able to read, `ret' were the value will be returned and `size' where
 * the number of used bytes is stored. Either 0 or an error code is returned.
 */

static int
der_get_unsigned(const unsigned char *p, size_t len,
                 unsigned *ret, size_t *size)
{
        unsigned val = 0;
        size_t oldlen = len;

        while (len--)
                val = val * 256 + *p++;
        *ret = val;
        if (size)
                *size = oldlen;
        return (0);
}

static int
der_get_int(const unsigned char *p, size_t len,
            int *ret, size_t *size)
{
        int val = 0;
        size_t oldlen = len;

        if (len > 0U) {
                val = (signed char)*p++;
                while (--len)
                        val = val * 256 + *p++;
        }
        *ret = val;
        if (size)
                *size = oldlen;
        return (0);
}

static int
der_get_length(const unsigned char *p, size_t len,
               size_t *val, size_t *size)
{
        size_t v;

        if (len <= 0U)
                return (ASN1_OVERRUN);
        --len;
        v = *p++;
        if (v < 128U) {
                *val = v;
                if (size)
                        *size = 1;
        } else {
                int e;
                size_t l;
                unsigned tmp;

                if (v == 0x80U) {
                        *val = ASN1_INDEFINITE;
                        if (size)
                                *size = 1;
                        return (0);
                }
                v &= 0x7F;
                if (len < v)
                        return (ASN1_OVERRUN);
                e = der_get_unsigned(p, v, &tmp, &l);
                if (e)
                        return (e);
                *val = tmp;
                if (size)
                        *size = l + 1;
        }
        return (0);
}

static int
der_get_octet_string(const unsigned char *p, size_t len,
                     octet_string *data, size_t *size)
{
        data->length = len;
        if (len != 0U) {
                data->data = malloc(len);
                if (data->data == NULL)
                        return (ENOMEM);
                memmove(data->data, p, len);
        } else
                data->data = NULL;
        if (size)
                *size = len;
        return (0);
}

static int
der_get_oid(const unsigned char *p, size_t len,
            oid *data, size_t *size)
{
        int n;
        size_t oldlen = len;

        data->components = NULL;
        data->length = 0;
        if (len < 1U)
                return (ASN1_OVERRUN);

        data->components = malloc(len * sizeof(*data->components));
        if (data->components == NULL && len != 0U)
                return (ENOMEM);
        data->components[0] = (*p) / 40;
        data->components[1] = (*p) % 40;
        --len;
        ++p;
        for (n = 2; len > 0U; ++n) {
                unsigned u = 0;

                do {
                        --len;
                        u = u * 128 + (*p++ % 128);
                } while (len > 0U && p[-1] & 0x80);
                data->components[n] = u;
        }
        if (p[-1] & 0x80) {
                free_oid(data);
                return (ASN1_OVERRUN);
        }
        data->length = n;
        if (size)
                *size = oldlen;
        return (0);
}

static int
der_get_tag(const unsigned char *p, size_t len,
            Der_class *class, Der_type *type,
            int *tag, size_t *size)
{
        if (len < 1U)
                return (ASN1_OVERRUN);
        *class = (Der_class) (((*p) >> 6) & 0x03);
        *type = (Der_type) (((*p) >> 5) & 0x01);
        *tag = (*p) & 0x1F;
        if (size)
                *size = 1;
        return (0);
}

static int
der_match_tag(const unsigned char *p, size_t len,
              Der_class class, Der_type type,
              int tag, size_t *size)
{
        size_t l;
        Der_class thisclass;
        Der_type thistype;
        int thistag;
        int e;

        e = der_get_tag(p, len, &thisclass, &thistype, &thistag, &l);
        if (e)
                return (e);
        if (class != thisclass || type != thistype)
                return (ASN1_BAD_ID);
        if (tag > thistag)
                return (ASN1_MISPLACED_FIELD);
        if (tag < thistag)
                return (ASN1_MISSING_FIELD);
        if (size)
                *size = l;
        return (0);
}

static int
der_match_tag_and_length(const unsigned char *p, size_t len,
                         Der_class class, Der_type type, int tag,
                         size_t *length_ret, size_t *size)
{
        size_t l, ret = 0;
        int e;

        e = der_match_tag(p, len, class, type, tag, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        ret += l;
        e = der_get_length(p, len, length_ret, &l);
        if (e)
                return (e);
        /* p += l; */
        len -= l;
        POST(len);
        ret += l;
        if (size)
                *size = ret;
        return (0);
}

static int
decode_enumerated(const unsigned char *p, size_t len, void *num, size_t *size)
{
        size_t ret = 0;
        size_t l, reallen;
        int e;

        e = der_match_tag(p, len, ASN1_C_UNIV, PRIM, UT_Enumerated, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        ret += l;
        e = der_get_length(p, len, &reallen, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        ret += l;
        e = der_get_int(p, reallen, num, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        POST(p); POST(len);
        ret += l;
        if (size)
                *size = ret;
        return (0);
}

static int
decode_octet_string(const unsigned char *p, size_t len,
                    octet_string *k, size_t *size)
{
        size_t ret = 0;
        size_t l;
        int e;
        size_t slen;

        k->data = NULL;
        k->length = 0;

        e = der_match_tag(p, len, ASN1_C_UNIV, PRIM, UT_OctetString, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        ret += l;

        e = der_get_length(p, len, &slen, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        ret += l;
        if (len < slen)
                return (ASN1_OVERRUN);

        e = der_get_octet_string(p, slen, k, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        POST(p); POST(len);
        ret += l;
        if (size)
                *size = ret;
        return (0);
}

static int
decode_oid(const unsigned char *p, size_t len,
           oid *k, size_t *size)
{
        size_t ret = 0;
        size_t l;
        int e;
        size_t slen;

        e = der_match_tag(p, len, ASN1_C_UNIV, PRIM, UT_OID, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        ret += l;

        e = der_get_length(p, len, &slen, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        ret += l;
        if (len < slen)
                return (ASN1_OVERRUN);

        e = der_get_oid(p, slen, k, &l);
        if (e)
                return (e);
        p += l;
        len -= l;
        POST(p); POST(len);
        ret += l;
        if (size)
                *size = ret;
        return (0);
}

static int
fix_dce(size_t reallen, size_t *len)
{
        if (reallen == ASN1_INDEFINITE)
                return (1);
        if (*len < reallen)
                return (-1);
        *len = reallen;
        return (0);
}

/* der_length.c */

static size_t
len_unsigned(unsigned val)
{
        size_t ret = 0;

        do {
                ++ret;
                val /= 256;
        } while (val);
        return (ret);
}

static size_t
length_len(size_t len)
{
        if (len < 128U)
                return (1);
        else
                return (len_unsigned((unsigned int)len) + 1);
}


/* der_put.c */

/*
 * All encoding functions take a pointer `p' to first position in which to
 * write, from the right, `len' which means the maximum number of characters
 * we are able to write.  The function returns the number of characters
 * written in `size' (if non-NULL). The return value is 0 or an error.
 */

static int
der_put_unsigned(unsigned char *p, size_t len, unsigned val, size_t *size)
{
        unsigned char *base = p;

        if (val) {
                while (len > 0U && val) {
                        *p-- = val % 256;
                        val /= 256;
                        --len;
                }
                if (val != 0)
                        return (ASN1_OVERFLOW);
                else {
                        *size = base - p;
                        return (0);
                }
        } else if (len < 1U)
                return (ASN1_OVERFLOW);
        else {
                *p = 0;
                *size = 1;
                return (0);
        }
}

static int
der_put_int(unsigned char *p, size_t len, int val, size_t *size)
{
        unsigned char *base = p;

        if (val >= 0) {
                do {
                        if (len < 1U)
                                return (ASN1_OVERFLOW);
                        *p-- = val % 256;
                        len--;
                        val /= 256;
                } while (val);
                if (p[1] >= 128) {
                        if (len < 1U)
                                return (ASN1_OVERFLOW);
                        *p-- = 0;
                        len--;
                }
        } else {
                val = ~val;
                do {
                        if (len < 1U)
                                return (ASN1_OVERFLOW);
                        *p-- = ~(val % 256);
                        len--;
                        val /= 256;
                } while (val);
                if (p[1] < 128) {
                        if (len < 1U)
                                return (ASN1_OVERFLOW);
                        *p-- = 0xff;
                        len--;
                }
        }
        *size = base - p;
        return (0);
}

static int
der_put_length(unsigned char *p, size_t len, size_t val, size_t *size)
{
        if (len < 1U)
                return (ASN1_OVERFLOW);
        if (val < 128U) {
                *p = (unsigned char)val;
                *size = 1;
                return (0);
        } else {
                size_t l;
                int e;

                e = der_put_unsigned(p, len - 1, (unsigned int)val, &l);
                if (e)
                        return (e);
                p -= l;
                *p = 0x80 | (unsigned char)l;
                *size = l + 1;
                return (0);
        }
}

static int
der_put_octet_string(unsigned char *p, size_t len,
                     const octet_string *data, size_t *size)
{
        if (len < data->length)
                return (ASN1_OVERFLOW);
        p -= data->length;
        len -= data->length;
        POST(len);
        memmove(p + 1, data->data, data->length);
        *size = data->length;
        return (0);
}

static int
der_put_oid(unsigned char *p, size_t len,
            const oid *data, size_t *size)
{
        unsigned char *base = p;
        size_t n;

        for (n = data->length; n >= 3u; --n) {
                unsigned        u = data->components[n - 1];

                if (len < 1U)
                        return (ASN1_OVERFLOW);
                *p-- = u % 128;
                u /= 128;
                --len;
                while (u > 0) {
                        if (len < 1U)
                                return (ASN1_OVERFLOW);
                        *p-- = 128 + u % 128;
                        u /= 128;
                        --len;
                }
        }
        if (len < 1U)
                return (ASN1_OVERFLOW);
        *p-- = 40 * data->components[0] + data->components[1];
        *size = base - p;
        return (0);
}

static int
der_put_tag(unsigned char *p, size_t len, Der_class class, Der_type type,
            int tag, size_t *size)
{
        if (len < 1U)
                return (ASN1_OVERFLOW);
        *p = (class << 6) | (type << 5) | tag;  /* XXX */
        *size = 1;
        return (0);
}

static int
der_put_length_and_tag(unsigned char *p, size_t len, size_t len_val,
                       Der_class class, Der_type type, int tag, size_t *size)
{
        size_t ret = 0;
        size_t l;
        int e;

        e = der_put_length(p, len, len_val, &l);
        if (e)
                return (e);
        p -= l;
        len -= l;
        ret += l;
        e = der_put_tag(p, len, class, type, tag, &l);
        if (e)
                return (e);
        p -= l;
        len -= l;
        POST(p); POST(len);
        ret += l;
        *size = ret;
        return (0);
}

static int
encode_enumerated(unsigned char *p, size_t len, const void *data, size_t *size)
{
        unsigned num = *(const unsigned *)data;
        size_t ret = 0;
        size_t l;
        int e;

        e = der_put_int(p, len, num, &l);
        if (e)
                return (e);
        p -= l;
        len -= l;
        ret += l;
        e = der_put_length_and_tag(p, len, l, ASN1_C_UNIV, PRIM, UT_Enumerated, &l);
        if (e)
                return (e);
        p -= l;
        len -= l;
        POST(p); POST(len);
        ret += l;
        *size = ret;
        return (0);
}

static int
encode_octet_string(unsigned char *p, size_t len,
                    const octet_string *k, size_t *size)
{
        size_t ret = 0;
        size_t l;
        int e;

        e = der_put_octet_string(p, len, k, &l);
        if (e)
                return (e);
        p -= l;
        len -= l;
        ret += l;
        e = der_put_length_and_tag(p, len, l, ASN1_C_UNIV, PRIM, UT_OctetString, &l);
        if (e)
                return (e);
        p -= l;
        len -= l;
        POST(p); POST(len);
        ret += l;
        *size = ret;
        return (0);
}

static int
encode_oid(unsigned char *p, size_t len,
           const oid *k, size_t *size)
{
        size_t ret = 0;
        size_t l;
        int e;

        e = der_put_oid(p, len, k, &l);
        if (e)
                return (e);
        p -= l;
        len -= l;
        ret += l;
        e = der_put_length_and_tag(p, len, l, ASN1_C_UNIV, PRIM, UT_OID, &l);
        if (e)
                return (e);
        p -= l;
        len -= l;
        POST(p); POST(len);
        ret += l;
        *size = ret;
        return (0);
}


/* encapsulate.c */

static void
gssapi_encap_length(size_t data_len,
                    size_t *len,
                    size_t *total_len,
                    const gss_OID mech)
{
        size_t len_len;

        *len = 1 + 1 + mech->length + data_len;

        len_len = length_len(*len);

        *total_len = 1 + len_len + *len;
}

static u_char *
gssapi_mech_make_header(u_char *p,
                        size_t len,
                        const gss_OID mech)
{
        int e;
        size_t len_len, foo;

        *p++ = 0x60;
        len_len = length_len(len);
        e = der_put_length(p + len_len - 1, len_len, len, &foo);
        if (e || foo != len_len)
                return (NULL);
        p += len_len;
        *p++ = 0x06;
        *p++ = mech->length;
        memmove(p, mech->elements, mech->length);
        p += mech->length;
        return (p);
}

/*
 * Give it a krb5_data and it will encapsulate with extra GSS-API wrappings.
 */

static OM_uint32
gssapi_spnego_encapsulate(OM_uint32 * minor_status,
                          unsigned char *buf,
                          size_t buf_size,
                          gss_buffer_t output_token,
                          const gss_OID mech)
{
        size_t len, outer_len;
        u_char *p;

        gssapi_encap_length(buf_size, &len, &outer_len, mech);

        output_token->length = outer_len;
        output_token->value = malloc(outer_len);
        if (output_token->value == NULL) {
                *minor_status = ENOMEM;
                return (GSS_S_FAILURE);
        }
        p = gssapi_mech_make_header(output_token->value, len, mech);
        if (p == NULL) {
                if (output_token->length != 0U)
                        gss_release_buffer(minor_status, output_token);
                return (GSS_S_FAILURE);
        }
        memmove(p, buf, buf_size);
        return (GSS_S_COMPLETE);
}

/* init_sec_context.c */
/*
 * SPNEGO wrapper for Kerberos5 GSS-API kouril@ics.muni.cz, 2003 (mostly
 * based on Heimdal code)
 */

static int
add_mech(MechTypeList * mech_list, gss_OID mech)
{
        MechType *tmp;
        int ret;

        tmp = realloc(mech_list->val, (mech_list->len + 1) * sizeof(*tmp));
        if (tmp == NULL)
                return (ENOMEM);
        mech_list->val = tmp;

        ret = der_get_oid(mech->elements, mech->length,
                          &mech_list->val[mech_list->len], NULL);
        if (ret)
                return (ret);

        mech_list->len++;
        return (0);
}

/*
 * return the length of the mechanism in token or -1
 * (which implies that the token was bad - GSS_S_DEFECTIVE_TOKEN
 */

static ssize_t
gssapi_krb5_get_mech(const u_char *ptr,
                     size_t total_len,
                     const u_char **mech_ret)
{
        size_t len, len_len, mech_len, foo;
        const u_char *p = ptr;
        int e;

        if (total_len < 1U)
                return (-1);
        if (*p++ != 0x60)
                return (-1);
        e = der_get_length (p, total_len - 1, &len, &len_len);
        if (e || 1 + len_len + len != total_len)
                return (-1);
        p += len_len;
        if (*p++ != 0x06)
                return (-1);
        e = der_get_length (p, total_len - 1 - len_len - 1,
                            &mech_len, &foo);
        if (e)
                return (-1);
        p += foo;
        *mech_ret = p;
        return (mech_len);
}

static OM_uint32
spnego_initial(OM_uint32 *minor_status,
               const gss_cred_id_t initiator_cred_handle,
               gss_ctx_id_t *context_handle,
               const gss_name_t target_name,
               const gss_OID mech_type,
               OM_uint32 req_flags,
               OM_uint32 time_req,
               const gss_channel_bindings_t input_chan_bindings,
               const gss_buffer_t input_token,
               gss_OID *actual_mech_type,
               gss_buffer_t output_token,
               OM_uint32 *ret_flags,
               OM_uint32 *time_rec)
{
        NegTokenInit token_init;
        OM_uint32 major_status, minor_status2;
        gss_buffer_desc krb5_output_token = GSS_C_EMPTY_BUFFER;
        unsigned char *buf = NULL;
        size_t buf_size;
        size_t len;
        int ret;

        (void)mech_type;

        memset(&token_init, 0, sizeof(token_init));

        ret = add_mech(&token_init.mechTypes, GSS_KRB5_MECH);
        if (ret) {
                *minor_status = ret;
                ret = GSS_S_FAILURE;
                goto end;
        }

        major_status = gss_init_sec_context(minor_status,
                                            initiator_cred_handle,
                                            context_handle,
                                            target_name,
                                            GSS_KRB5_MECH,
                                            req_flags,
                                            time_req,
                                            input_chan_bindings,
                                            input_token,
                                            actual_mech_type,
                                            &krb5_output_token,
                                            ret_flags,
                                            time_rec);
        if (GSS_ERROR(major_status)) {
                ret = major_status;
                goto end;
        }
        if (krb5_output_token.length > 0U) {
                token_init.mechToken = malloc(sizeof(*token_init.mechToken));
                if (token_init.mechToken == NULL) {
                        *minor_status = ENOMEM;
                        ret = GSS_S_FAILURE;
                        goto end;
                }
                token_init.mechToken->data = krb5_output_token.value;
                token_init.mechToken->length = krb5_output_token.length;
        }
        /*
         * The MS implementation of SPNEGO seems to not like the mechListMIC
         * field, so we omit it (it's optional anyway)
         */

        buf_size = 1024;
        buf = malloc(buf_size);
        if (buf == NULL) {
                *minor_status = ENOMEM;
                ret = GSS_S_FAILURE;
                goto end;
        }

        do {
                ret = encode_NegTokenInit(buf + buf_size - 1,
                                          buf_size,
                                          &token_init, &len);
                if (ret == 0) {
                        size_t tmp;

                        ret = der_put_length_and_tag(buf + buf_size - len - 1,
                                                     buf_size - len,
                                                     len,
                                                     ASN1_C_CONTEXT,
                                                     CONS,
                                                     0,
                                                     &tmp);
                        if (ret == 0)
                                len += tmp;
                }
                if (ret) {
                        if (ret == ASN1_OVERFLOW) {
                                u_char *tmp;

                                buf_size *= 2;
                                tmp = realloc(buf, buf_size);
                                if (tmp == NULL) {
                                        *minor_status = ENOMEM;
                                        ret = GSS_S_FAILURE;
                                        goto end;
                                }
                                buf = tmp;
                        } else {
                                *minor_status = ret;
                                ret = GSS_S_FAILURE;
                                goto end;
                        }
                }
        } while (ret == ASN1_OVERFLOW);

        ret = gssapi_spnego_encapsulate(minor_status,
                                        buf + buf_size - len, len,
                                        output_token, GSS_SPNEGO_MECH);
        if (ret == GSS_S_COMPLETE)
                ret = major_status;

end:
        if (token_init.mechToken != NULL) {
                free(token_init.mechToken);
                token_init.mechToken = NULL;
        }
        free_NegTokenInit(&token_init);
        if (krb5_output_token.length != 0U)
                gss_release_buffer(&minor_status2, &krb5_output_token);
        if (buf)
                free(buf);

        return (ret);
}

static OM_uint32
spnego_reply(OM_uint32 *minor_status,
             const gss_cred_id_t initiator_cred_handle,
             gss_ctx_id_t *context_handle,
             const gss_name_t target_name,
             const gss_OID mech_type,
             OM_uint32 req_flags,
             OM_uint32 time_req,
             const gss_channel_bindings_t input_chan_bindings,
             const gss_buffer_t input_token,
             gss_OID *actual_mech_type,
             gss_buffer_t output_token,
             OM_uint32 *ret_flags,
             OM_uint32 *time_rec)
{
        OM_uint32 ret;
        NegTokenResp resp;
        unsigned char *buf;
        size_t buf_size;
        u_char oidbuf[17];
        size_t oidlen;
        gss_buffer_desc sub_token;
        ssize_t mech_len;
        const u_char *p;
        size_t len, taglen;

        (void)mech_type;

        output_token->length = 0;
        output_token->value  = NULL;

        /*
         * SPNEGO doesn't include gss wrapping on SubsequentContextToken
         * like the Kerberos 5 mech does. But lets check for it anyway.
         */

        mech_len = gssapi_krb5_get_mech(input_token->value,
                                        input_token->length,
                                        &p);

        if (mech_len < 0) {
                buf = input_token->value;
                buf_size = input_token->length;
        } else if ((size_t)mech_len == GSS_KRB5_MECH->length &&
                   memcmp(GSS_KRB5_MECH->elements, p, mech_len) == 0)
                return (gss_init_sec_context(minor_status,
                                             initiator_cred_handle,
                                             context_handle,
                                             target_name,
                                             GSS_KRB5_MECH,
                                             req_flags,
                                             time_req,
                                             input_chan_bindings,
                                             input_token,
                                             actual_mech_type,
                                             output_token,
                                             ret_flags,
                                             time_rec));
        else if ((size_t)mech_len == GSS_SPNEGO_MECH->length &&
                 memcmp(GSS_SPNEGO_MECH->elements, p, mech_len) == 0) {
                ret = gssapi_spnego_decapsulate(minor_status,
                                                input_token,
                                                &buf,
                                                &buf_size,
                                                GSS_SPNEGO_MECH);
                if (ret)
                        return (ret);
        } else
                return (GSS_S_BAD_MECH);

        ret = der_match_tag_and_length(buf, buf_size,
                                       ASN1_C_CONTEXT, CONS, 1, &len, &taglen);
        if (ret)
                return (ret);

        if(len > buf_size - taglen)
                return (ASN1_OVERRUN);

        ret = decode_NegTokenResp(buf + taglen, len, &resp, NULL);
        if (ret) {
                free_NegTokenResp(&resp);
                *minor_status = ENOMEM;
                return (GSS_S_FAILURE);
        }

        if (resp.negState == NULL ||
            *(resp.negState) == reject ||
            resp.supportedMech == NULL) {
                free_NegTokenResp(&resp);
                return (GSS_S_BAD_MECH);
        }

        ret = der_put_oid(oidbuf + sizeof(oidbuf) - 1,
                          sizeof(oidbuf),
                          resp.supportedMech,
                          &oidlen);
        if (ret || oidlen != GSS_KRB5_MECH->length ||
            memcmp(oidbuf + sizeof(oidbuf) - oidlen,
                   GSS_KRB5_MECH->elements,
                   oidlen) != 0) {
                free_NegTokenResp(&resp);
                return GSS_S_BAD_MECH;
        }

        if (resp.responseToken != NULL) {
                sub_token.length = resp.responseToken->length;
                sub_token.value  = resp.responseToken->data;
        } else {
                sub_token.length = 0;
                sub_token.value  = NULL;
        }

        ret = gss_init_sec_context(minor_status,
                                   initiator_cred_handle,
                                   context_handle,
                                   target_name,
                                   GSS_KRB5_MECH,
                                   req_flags,
                                   time_req,
                                   input_chan_bindings,
                                   &sub_token,
                                   actual_mech_type,
                                   output_token,
                                   ret_flags,
                                   time_rec);
        if (ret) {
                free_NegTokenResp(&resp);
                return (ret);
        }

        /*
         * XXXSRA I don't think this limited implementation ever needs
         * to check the MIC -- our preferred mechanism (Kerberos)
         * authenticates its own messages and is the only mechanism
         * we'll accept, so if the mechanism negotiation completes
         * successfully, we don't need the MIC.  See RFC 4178.
         */

        free_NegTokenResp(&resp);
        return (ret);
}



OM_uint32
gss_init_sec_context_spnego(OM_uint32 *minor_status,
                            const gss_cred_id_t initiator_cred_handle,
                            gss_ctx_id_t *context_handle,
                            const gss_name_t target_name,
                            const gss_OID mech_type,
                            OM_uint32 req_flags,
                            OM_uint32 time_req,
                            const gss_channel_bindings_t input_chan_bindings,
                            const gss_buffer_t input_token,
                            gss_OID *actual_mech_type,
                            gss_buffer_t output_token,
                            OM_uint32 *ret_flags,
                            OM_uint32 *time_rec)
{
        /* Dirty trick to suppress compiler warnings */

        /* Figure out whether we're starting over or processing a reply */

        if (input_token == GSS_C_NO_BUFFER || input_token->length == 0U)
                return (spnego_initial(minor_status,
                                       initiator_cred_handle,
                                       context_handle,
                                       target_name,
                                       mech_type,
                                       req_flags,
                                       time_req,
                                       input_chan_bindings,
                                       input_token,
                                       actual_mech_type,
                                       output_token,
                                       ret_flags,
                                       time_rec));
        else
                return (spnego_reply(minor_status,
                                     initiator_cred_handle,
                                     context_handle,
                                     target_name,
                                     mech_type,
                                     req_flags,
                                     time_req,
                                     input_chan_bindings,
                                     input_token,
                                     actual_mech_type,
                                     output_token,
                                     ret_flags,
                                     time_rec));
}

#endif /* GSSAPI */

---