crypto/ts/ts_rsp_verify.c

   1 /*
   2  * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/objects.h>
  13 #include <openssl/ts.h>
  14 #include <openssl/pkcs7.h>
  15 #include "ts_lcl.h"
  16
  17 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
  18                           X509 *signer, STACK_OF(X509) **chain);
  19 static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
  20                                   STACK_OF(X509) *chain);
  21 static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si);
  22 static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert);
  23 static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert);
  24 static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
  25                                     PKCS7 *token, TS_TST_INFO *tst_info);
  26 static int ts_check_status_info(TS_RESP *response);
  27 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text);
  28 static int ts_check_policy(ASN1_OBJECT *req_oid, TS_TST_INFO *tst_info);
  29 static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
  30                               X509_ALGOR **md_alg,
  31                               unsigned char **imprint, unsigned *imprint_len);
  32 static int ts_check_imprints(X509_ALGOR *algor_a,
  33                              unsigned char *imprint_a, unsigned len_a,
  34                              TS_TST_INFO *tst_info);
  35 static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info);
  36 static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer);
  37 static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names,
  38                         GENERAL_NAME *name);
  39
  40 /*
  41  * This must be large enough to hold all values in ts_status_text (with
  42  * comma separator) or all text fields in ts_failure_info (also with comma).
  43  */
  44 #define TS_STATUS_BUF_SIZE      256
  45
  46 /*
  47  * Local mapping between response codes and descriptions.
  48  */
  49 static const char *ts_status_text[] = {
  50     "granted",
  51     "grantedWithMods",
  52     "rejection",
  53     "waiting",
  54     "revocationWarning",
  55     "revocationNotification"
  56 };
  57
  58 #define TS_STATUS_TEXT_SIZE     OSSL_NELEM(ts_status_text)
  59
  60 static struct {
  61     int code;
  62     const char *text;
  63 } ts_failure_info[] = {
  64     {TS_INFO_BAD_ALG, "badAlg"},
  65     {TS_INFO_BAD_REQUEST, "badRequest"},
  66     {TS_INFO_BAD_DATA_FORMAT, "badDataFormat"},
  67     {TS_INFO_TIME_NOT_AVAILABLE, "timeNotAvailable"},
  68     {TS_INFO_UNACCEPTED_POLICY, "unacceptedPolicy"},
  69     {TS_INFO_UNACCEPTED_EXTENSION, "unacceptedExtension"},
  70     {TS_INFO_ADD_INFO_NOT_AVAILABLE, "addInfoNotAvailable"},
  71     {TS_INFO_SYSTEM_FAILURE, "systemFailure"}
  72 };
  73
  74
  75 /*-
  76  * This function carries out the following tasks:
  77  *      - Checks if there is one and only one signer.
  78  *      - Search for the signing certificate in 'certs' and in the response.
  79  *      - Check the extended key usage and key usage fields of the signer
  80  *      certificate (done by the path validation).
  81  *      - Build and validate the certificate path.
  82  *      - Check if the certificate path meets the requirements of the
  83  *      SigningCertificate ESS signed attribute.
  84  *      - Verify the signature value.
  85  *      - Returns the signer certificate in 'signer', if 'signer' is not NULL.
  86  */
  87 int TS_RESP_verify_signature(PKCS7 *token, STACK_OF(X509) *certs,
  88                              X509_STORE *store, X509 **signer_out)
  89 {
  90     STACK_OF(PKCS7_SIGNER_INFO) *sinfos = NULL;
  91     PKCS7_SIGNER_INFO *si;
  92     STACK_OF(X509) *signers = NULL;
  93     X509 *signer;
  94     STACK_OF(X509) *chain = NULL;
  95     char buf[4096];
  96     int i, j = 0, ret = 0;
  97     BIO *p7bio = NULL;
  98
  99     /* Some sanity checks first. */
 100     if (!token) {
 101         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_INVALID_NULL_POINTER);
 102         goto err;
 103     }
 104     if (!PKCS7_type_is_signed(token)) {
 105         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_WRONG_CONTENT_TYPE);
 106         goto err;
 107     }
 108     sinfos = PKCS7_get_signer_info(token);
 109     if (!sinfos || sk_PKCS7_SIGNER_INFO_num(sinfos) != 1) {
 110         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_THERE_MUST_BE_ONE_SIGNER);
 111         goto err;
 112     }
 113     si = sk_PKCS7_SIGNER_INFO_value(sinfos, 0);
 114     if (PKCS7_get_detached(token)) {
 115         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_NO_CONTENT);
 116         goto err;
 117     }
 118
 119     /*
 120      * Get hold of the signer certificate, search only internal certificates
 121      * if it was requested.
 122      */
 123     signers = PKCS7_get0_signers(token, certs, 0);
 124     if (!signers || sk_X509_num(signers) != 1)
 125         goto err;
 126     signer = sk_X509_value(signers, 0);
 127
 128     if (!ts_verify_cert(store, certs, signer, &chain))
 129         goto err;
 130     if (!ts_check_signing_certs(si, chain))
 131         goto err;
 132     p7bio = PKCS7_dataInit(token, NULL);
 133
 134     /* We now have to 'read' from p7bio to calculate digests etc. */
 135     while ((i = BIO_read(p7bio, buf, sizeof(buf))) > 0)
 136         continue;
 137
 138     j = PKCS7_signatureVerify(p7bio, token, si, signer);
 139     if (j <= 0) {
 140         TSerr(TS_F_TS_RESP_VERIFY_SIGNATURE, TS_R_SIGNATURE_FAILURE);
 141         goto err;
 142     }
 143
 144     if (signer_out) {
 145         *signer_out = signer;
 146         X509_up_ref(signer);
 147     }
 148     ret = 1;
 149
 150  err:
 151     BIO_free_all(p7bio);
 152     sk_X509_pop_free(chain, X509_free);
 153     sk_X509_free(signers);
 154
 155     return ret;
 156 }
 157
 158 /*
 159  * The certificate chain is returned in chain. Caller is responsible for
 160  * freeing the vector.
 161  */
 162 static int ts_verify_cert(X509_STORE *store, STACK_OF(X509) *untrusted,
 163                           X509 *signer, STACK_OF(X509) **chain)
 164 {
 165     X509_STORE_CTX *cert_ctx = NULL;
 166     int i;
 167     int ret = 0;
 168
 169     *chain = NULL;
 170     cert_ctx = X509_STORE_CTX_new();
 171     if (cert_ctx == NULL) {
 172         TSerr(TS_F_TS_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
 173         goto err;
 174     }
 175     if (!X509_STORE_CTX_init(cert_ctx, store, signer, untrusted))
 176         goto end;
 177     X509_STORE_CTX_set_purpose(cert_ctx, X509_PURPOSE_TIMESTAMP_SIGN);
 178     i = X509_verify_cert(cert_ctx);
 179     if (i <= 0) {
 180         int j = X509_STORE_CTX_get_error(cert_ctx);
 181         TSerr(TS_F_TS_VERIFY_CERT, TS_R_CERTIFICATE_VERIFY_ERROR);
 182         ERR_add_error_data(2, "Verify error:",
 183                            X509_verify_cert_error_string(j));
 184         goto err;
 185     }
 186     *chain = X509_STORE_CTX_get1_chain(cert_ctx);
 187     ret = 1;
 188     goto end;
 189
 190 err:
 191     ret = 0;
 192
 193 end:
 194     X509_STORE_CTX_free(cert_ctx);
 195     return ret;
 196 }
 197
 198 static int ts_check_signing_certs(PKCS7_SIGNER_INFO *si,
 199                                   STACK_OF(X509) *chain)
 200 {
 201     ESS_SIGNING_CERT *ss = ess_get_signing_cert(si);
 202     STACK_OF(ESS_CERT_ID) *cert_ids = NULL;
 203     X509 *cert;
 204     int i = 0;
 205     int ret = 0;
 206
 207     if (!ss)
 208         goto err;
 209     cert_ids = ss->cert_ids;
 210     cert = sk_X509_value(chain, 0);
 211     if (ts_find_cert(cert_ids, cert) != 0)
 212         goto err;
 213
 214     /*
 215      * Check the other certificates of the chain if there are more than one
 216      * certificate ids in cert_ids.
 217      */
 218     if (sk_ESS_CERT_ID_num(cert_ids) > 1) {
 219         for (i = 1; i < sk_X509_num(chain); ++i) {
 220             cert = sk_X509_value(chain, i);
 221             if (ts_find_cert(cert_ids, cert) < 0)
 222                 goto err;
 223         }
 224     }
 225     ret = 1;
 226  err:
 227     if (!ret)
 228         TSerr(TS_F_TS_CHECK_SIGNING_CERTS,
 229               TS_R_ESS_SIGNING_CERTIFICATE_ERROR);
 230     ESS_SIGNING_CERT_free(ss);
 231     return ret;
 232 }
 233
 234 static ESS_SIGNING_CERT *ess_get_signing_cert(PKCS7_SIGNER_INFO *si)
 235 {
 236     ASN1_TYPE *attr;
 237     const unsigned char *p;
 238     attr = PKCS7_get_signed_attribute(si, NID_id_smime_aa_signingCertificate);
 239     if (!attr)
 240         return NULL;
 241     p = attr->value.sequence->data;
 242     return d2i_ESS_SIGNING_CERT(NULL, &p, attr->value.sequence->length);
 243 }
 244
 245 /* Returns < 0 if certificate is not found, certificate index otherwise. */
 246 static int ts_find_cert(STACK_OF(ESS_CERT_ID) *cert_ids, X509 *cert)
 247 {
 248     int i;
 249     unsigned char cert_sha1[SHA_DIGEST_LENGTH];
 250
 251     if (!cert_ids || !cert)
 252         return -1;
 253
 254     X509_digest(cert, EVP_sha1(), cert_sha1, NULL);
 255
 256     /* Recompute SHA1 hash of certificate if necessary (side effect). */
 257     X509_check_purpose(cert, -1, 0);
 258
 259     /* Look for cert in the cert_ids vector. */
 260     for (i = 0; i < sk_ESS_CERT_ID_num(cert_ids); ++i) {
 261         ESS_CERT_ID *cid = sk_ESS_CERT_ID_value(cert_ids, i);
 262
 263         if (cid->hash->length == SHA_DIGEST_LENGTH
 264             && memcmp(cid->hash->data, cert_sha1, SHA_DIGEST_LENGTH) == 0) {
 265             ESS_ISSUER_SERIAL *is = cid->issuer_serial;
 266             if (!is || !ts_issuer_serial_cmp(is, cert))
 267                 return i;
 268         }
 269     }
 270
 271     return -1;
 272 }
 273
 274 static int ts_issuer_serial_cmp(ESS_ISSUER_SERIAL *is, X509 *cert)
 275 {
 276     GENERAL_NAME *issuer;
 277
 278     if (!is || !cert || sk_GENERAL_NAME_num(is->issuer) != 1)
 279         return -1;
 280
 281     issuer = sk_GENERAL_NAME_value(is->issuer, 0);
 282     if (issuer->type != GEN_DIRNAME
 283         || X509_NAME_cmp(issuer->d.dirn, X509_get_issuer_name(cert)))
 284         return -1;
 285
 286     if (ASN1_INTEGER_cmp(is->serial, X509_get_serialNumber(cert)))
 287         return -1;
 288
 289     return 0;
 290 }
 291
 292 /*-
 293  * Verifies whether 'response' contains a valid response with regards
 294  * to the settings of the context:
 295  *      - Gives an error message if the TS_TST_INFO is not present.
 296  *      - Calls _TS_RESP_verify_token to verify the token content.
 297  */
 298 int TS_RESP_verify_response(TS_VERIFY_CTX *ctx, TS_RESP *response)
 299 {
 300     PKCS7 *token = response->token;
 301     TS_TST_INFO *tst_info = response->tst_info;
 302     int ret = 0;
 303
 304     if (!ts_check_status_info(response))
 305         goto err;
 306     if (!int_ts_RESP_verify_token(ctx, token, tst_info))
 307         goto err;
 308     ret = 1;
 309
 310  err:
 311     return ret;
 312 }
 313
 314 /*
 315  * Tries to extract a TS_TST_INFO structure from the PKCS7 token and
 316  * calls the internal int_TS_RESP_verify_token function for verifying it.
 317  */
 318 int TS_RESP_verify_token(TS_VERIFY_CTX *ctx, PKCS7 *token)
 319 {
 320     TS_TST_INFO *tst_info = PKCS7_to_TS_TST_INFO(token);
 321     int ret = 0;
 322     if (tst_info) {
 323         ret = int_ts_RESP_verify_token(ctx, token, tst_info);
 324         TS_TST_INFO_free(tst_info);
 325     }
 326     return ret;
 327 }
 328
 329 /*-
 330  * Verifies whether the 'token' contains a valid time stamp token
 331  * with regards to the settings of the context. Only those checks are
 332  * carried out that are specified in the context:
 333  *      - Verifies the signature of the TS_TST_INFO.
 334  *      - Checks the version number of the response.
 335  *      - Check if the requested and returned policies math.
 336  *      - Check if the message imprints are the same.
 337  *      - Check if the nonces are the same.
 338  *      - Check if the TSA name matches the signer.
 339  *      - Check if the TSA name is the expected TSA.
 340  */
 341 static int int_ts_RESP_verify_token(TS_VERIFY_CTX *ctx,
 342                                     PKCS7 *token, TS_TST_INFO *tst_info)
 343 {
 344     X509 *signer = NULL;
 345     GENERAL_NAME *tsa_name = tst_info->tsa;
 346     X509_ALGOR *md_alg = NULL;
 347     unsigned char *imprint = NULL;
 348     unsigned imprint_len = 0;
 349     int ret = 0;
 350
 351     if ((ctx->flags & TS_VFY_SIGNATURE)
 352         && !TS_RESP_verify_signature(token, ctx->certs, ctx->store, &signer))
 353         goto err;
 354     if ((ctx->flags & TS_VFY_VERSION)
 355         && TS_TST_INFO_get_version(tst_info) != 1) {
 356         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_UNSUPPORTED_VERSION);
 357         goto err;
 358     }
 359     if ((ctx->flags & TS_VFY_POLICY)
 360         && !ts_check_policy(ctx->policy, tst_info))
 361         goto err;
 362     if ((ctx->flags & TS_VFY_IMPRINT)
 363         && !ts_check_imprints(ctx->md_alg, ctx->imprint, ctx->imprint_len,
 364                               tst_info))
 365         goto err;
 366     if ((ctx->flags & TS_VFY_DATA)
 367         && (!ts_compute_imprint(ctx->data, tst_info,
 368                                 &md_alg, &imprint, &imprint_len)
 369             || !ts_check_imprints(md_alg, imprint, imprint_len, tst_info)))
 370         goto err;
 371     if ((ctx->flags & TS_VFY_NONCE)
 372         && !ts_check_nonces(ctx->nonce, tst_info))
 373         goto err;
 374     if ((ctx->flags & TS_VFY_SIGNER)
 375         && tsa_name && !ts_check_signer_name(tsa_name, signer)) {
 376         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_NAME_MISMATCH);
 377         goto err;
 378     }
 379     if ((ctx->flags & TS_VFY_TSA_NAME)
 380         && !ts_check_signer_name(ctx->tsa_name, signer)) {
 381         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_UNTRUSTED);
 382         goto err;
 383     }
 384     ret = 1;
 385
 386  err:
 387     X509_free(signer);
 388     X509_ALGOR_free(md_alg);
 389     OPENSSL_free(imprint);
 390     return ret;
 391 }
 392
 393 static int ts_check_status_info(TS_RESP *response)
 394 {
 395     TS_STATUS_INFO *info = response->status_info;
 396     long status = ASN1_INTEGER_get(info->status);
 397     const char *status_text = NULL;
 398     char *embedded_status_text = NULL;
 399     char failure_text[TS_STATUS_BUF_SIZE] = "";
 400
 401     if (status == 0 || status == 1)
 402         return 1;
 403
 404     /* There was an error, get the description in status_text. */
 405     if (0 <= status && status < (long) OSSL_NELEM(ts_status_text))
 406         status_text = ts_status_text[status];
 407     else
 408         status_text = "unknown code";
 409
 410     if (sk_ASN1_UTF8STRING_num(info->text) > 0
 411         && (embedded_status_text = ts_get_status_text(info->text)) == NULL)
 412         return 0;
 413
 414     /* Fill in failure_text with the failure information. */
 415     if (info->failure_info) {
 416         int i;
 417         int first = 1;
 418         for (i = 0; i < (int)OSSL_NELEM(ts_failure_info); ++i) {
 419             if (ASN1_BIT_STRING_get_bit(info->failure_info,
 420                                         ts_failure_info[i].code)) {
 421                 if (!first)
 422                     strcat(failure_text, ",");
 423                 else
 424                     first = 0;
 425                 strcat(failure_text, ts_failure_info[i].text);
 426             }
 427         }
 428     }
 429     if (failure_text[0] == '\0')
 430         strcpy(failure_text, "unspecified");
 431
 432     TSerr(TS_F_TS_CHECK_STATUS_INFO, TS_R_NO_TIME_STAMP_TOKEN);
 433     ERR_add_error_data(6,
 434                        "status code: ", status_text,
 435                        ", status text: ", embedded_status_text ?
 436                        embedded_status_text : "unspecified",
 437                        ", failure codes: ", failure_text);
 438     OPENSSL_free(embedded_status_text);
 439
 440     return 0;
 441 }
 442
 443 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text)
 444 {
 445     int i;
 446     unsigned int length = 0;
 447     char *result = NULL;
 448     char *p;
 449
 450     for (i = 0; i < sk_ASN1_UTF8STRING_num(text); ++i) {
 451         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
 452         length += ASN1_STRING_length(current);
 453         length += 1;            /* separator character */
 454     }
 455     if ((result = OPENSSL_malloc(length)) == NULL) {
 456         TSerr(TS_F_TS_GET_STATUS_TEXT, ERR_R_MALLOC_FAILURE);
 457         return NULL;
 458     }
 459
 460     for (i = 0, p = result; i < sk_ASN1_UTF8STRING_num(text); ++i) {
 461         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
 462         length = ASN1_STRING_length(current);
 463         if (i > 0)
 464             *p++ = '/';
 465         strncpy(p, (const char *)ASN1_STRING_data(current), length);
 466         p += length;
 467     }
 468     *p = '\0';
 469
 470     return result;
 471 }
 472
 473 static int ts_check_policy(ASN1_OBJECT *req_oid, TS_TST_INFO *tst_info)
 474 {
 475     ASN1_OBJECT *resp_oid = tst_info->policy_id;
 476
 477     if (OBJ_cmp(req_oid, resp_oid) != 0) {
 478         TSerr(TS_F_TS_CHECK_POLICY, TS_R_POLICY_MISMATCH);
 479         return 0;
 480     }
 481
 482     return 1;
 483 }
 484
 485 static int ts_compute_imprint(BIO *data, TS_TST_INFO *tst_info,
 486                               X509_ALGOR **md_alg,
 487                               unsigned char **imprint, unsigned *imprint_len)
 488 {
 489     TS_MSG_IMPRINT *msg_imprint = tst_info->msg_imprint;
 490     X509_ALGOR *md_alg_resp = msg_imprint->hash_algo;
 491     const EVP_MD *md;
 492     EVP_MD_CTX *md_ctx = NULL;
 493     unsigned char buffer[4096];
 494     int length;
 495
 496     *md_alg = NULL;
 497     *imprint = NULL;
 498
 499     if ((*md_alg = X509_ALGOR_dup(md_alg_resp)) == NULL)
 500         goto err;
 501     if ((md = EVP_get_digestbyobj((*md_alg)->algorithm)) == NULL) {
 502         TSerr(TS_F_TS_COMPUTE_IMPRINT, TS_R_UNSUPPORTED_MD_ALGORITHM);
 503         goto err;
 504     }
 505     length = EVP_MD_size(md);
 506     if (length < 0)
 507         goto err;
 508     *imprint_len = length;
 509     if ((*imprint = OPENSSL_malloc(*imprint_len)) == NULL) {
 510         TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
 511         goto err;
 512     }
 513
 514     md_ctx = EVP_MD_CTX_new();
 515     if (md_ctx == NULL) {
 516         TSerr(TS_F_TS_COMPUTE_IMPRINT, ERR_R_MALLOC_FAILURE);
 517         goto err;
 518     }
 519     if (!EVP_DigestInit(md_ctx, md))
 520         goto err;
 521     while ((length = BIO_read(data, buffer, sizeof(buffer))) > 0) {
 522         if (!EVP_DigestUpdate(md_ctx, buffer, length))
 523             goto err;
 524     }
 525     if (!EVP_DigestFinal(md_ctx, *imprint, NULL))
 526         goto err;
 527     EVP_MD_CTX_free(md_ctx);
 528
 529     return 1;
 530  err:
 531     EVP_MD_CTX_free(md_ctx);
 532     X509_ALGOR_free(*md_alg);
 533     OPENSSL_free(*imprint);
 534     *imprint_len = 0;
 535     *imprint = 0;
 536     return 0;
 537 }
 538
 539 static int ts_check_imprints(X509_ALGOR *algor_a,
 540                              unsigned char *imprint_a, unsigned len_a,
 541                              TS_TST_INFO *tst_info)
 542 {
 543     TS_MSG_IMPRINT *b = tst_info->msg_imprint;
 544     X509_ALGOR *algor_b = b->hash_algo;
 545     int ret = 0;
 546
 547     if (algor_a) {
 548         if (OBJ_cmp(algor_a->algorithm, algor_b->algorithm))
 549             goto err;
 550
 551         /* The parameter must be NULL in both. */
 552         if ((algor_a->parameter
 553              && ASN1_TYPE_get(algor_a->parameter) != V_ASN1_NULL)
 554             || (algor_b->parameter
 555                 && ASN1_TYPE_get(algor_b->parameter) != V_ASN1_NULL))
 556             goto err;
 557     }
 558
 559     ret = len_a == (unsigned)ASN1_STRING_length(b->hashed_msg) &&
 560         memcmp(imprint_a, ASN1_STRING_data(b->hashed_msg), len_a) == 0;
 561  err:
 562     if (!ret)
 563         TSerr(TS_F_TS_CHECK_IMPRINTS, TS_R_MESSAGE_IMPRINT_MISMATCH);
 564     return ret;
 565 }
 566
 567 static int ts_check_nonces(const ASN1_INTEGER *a, TS_TST_INFO *tst_info)
 568 {
 569     const ASN1_INTEGER *b = tst_info->nonce;
 570
 571     if (!b) {
 572         TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_NOT_RETURNED);
 573         return 0;
 574     }
 575
 576     /* No error if a nonce is returned without being requested. */
 577     if (ASN1_INTEGER_cmp(a, b) != 0) {
 578         TSerr(TS_F_TS_CHECK_NONCES, TS_R_NONCE_MISMATCH);
 579         return 0;
 580     }
 581
 582     return 1;
 583 }
 584
 585 /*
 586  * Check if the specified TSA name matches either the subject or one of the
 587  * subject alternative names of the TSA certificate.
 588  */
 589 static int ts_check_signer_name(GENERAL_NAME *tsa_name, X509 *signer)
 590 {
 591     STACK_OF(GENERAL_NAME) *gen_names = NULL;
 592     int idx = -1;
 593     int found = 0;
 594
 595     if (tsa_name->type == GEN_DIRNAME
 596         && X509_name_cmp(tsa_name->d.dirn, X509_get_subject_name(signer)) == 0)
 597         return 1;
 598     gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
 599     while (gen_names != NULL) {
 600         found = ts_find_name(gen_names, tsa_name) >= 0;
 601         if (found)
 602             break;
 603         /*
 604          * Get the next subject alternative name, although there should be no
 605          * more than one.
 606          */
 607         GENERAL_NAMES_free(gen_names);
 608         gen_names = X509_get_ext_d2i(signer, NID_subject_alt_name, NULL, &idx);
 609     }
 610     GENERAL_NAMES_free(gen_names);
 611
 612     return found;
 613 }
 614
 615 /* Returns 1 if name is in gen_names, 0 otherwise. */
 616 static int ts_find_name(STACK_OF(GENERAL_NAME) *gen_names, GENERAL_NAME *name)
 617 {
 618     int i, found;
 619     for (i = 0, found = 0; !found && i < sk_GENERAL_NAME_num(gen_names); ++i) {
 620         GENERAL_NAME *current = sk_GENERAL_NAME_value(gen_names, i);
 621         found = GENERAL_NAME_cmp(current, name) == 0;
 622     }
 623     return found ? i - 1 : -1;
 624 }