src/src/tls-openssl.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) University of Cambridge 1995 - 2009 */
   6 /* See the file NOTICE for conditions of use and distribution. */
   7
   8 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
   9 library. It is #included into the tls.c file when that library is used. The
  10 code herein is based on a patch that was originally contributed by Steve
  11 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
  12
  13 No cryptographic code is included in Exim. All this module does is to call
  14 functions from the OpenSSL library. */
  15
  16
  17 /* Heading stuff */
  18
  19 #include <openssl/lhash.h>
  20 #include <openssl/ssl.h>
  21 #include <openssl/err.h>
  22 #include <openssl/rand.h>
  23
  24 /* Structure for collecting random data for seeding. */
  25
  26 typedef struct randstuff {
  27   struct timeval tv;
  28   pid_t          p;
  29 } randstuff;
  30
  31 /* Local static variables */
  32
  33 static BOOL verify_callback_called = FALSE;
  34 static const uschar *sid_ctx = US"exim";
  35
  36 static SSL_CTX *ctx = NULL;
  37 static SSL *ssl = NULL;
  38
  39 static char ssl_errstring[256];
  40
  41 static int  ssl_session_timeout = 200;
  42 static BOOL verify_optional = FALSE;
  43
  44
  45
  46
  47
  48 /*************************************************
  49 *               Handle TLS error                 *
  50 *************************************************/
  51
  52 /* Called from lots of places when errors occur before actually starting to do
  53 the TLS handshake, that is, while the session is still in clear. Always returns
  54 DEFER for a server and FAIL for a client so that most calls can use "return
  55 tls_error(...)" to do this processing and then give an appropriate return. A
  56 single function is used for both server and client, because it is called from
  57 some shared functions.
  58
  59 Argument:
  60   prefix    text to include in the logged error
  61   host      NULL if setting up a server;
  62             the connected host if setting up a client
  63   msg       error message or NULL if we should ask OpenSSL
  64
  65 Returns:    OK/DEFER/FAIL
  66 */
  67
  68 static int
  69 tls_error(uschar *prefix, host_item *host, uschar *msg)
  70 {
  71 if (msg == NULL)
  72   {
  73   ERR_error_string(ERR_get_error(), ssl_errstring);
  74   msg = (uschar *)ssl_errstring;
  75   }
  76
  77 if (host == NULL)
  78   {
  79   uschar *conn_info = smtp_get_connection_info();
  80   if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
  81     conn_info += 5;
  82   log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
  83     conn_info, prefix, msg);
  84   return DEFER;
  85   }
  86 else
  87   {
  88   log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s",
  89     host->name, host->address, prefix, msg);
  90   return FAIL;
  91   }
  92 }
  93
  94
  95
  96 /*************************************************
  97 *        Callback to generate RSA key            *
  98 *************************************************/
  99
 100 /*
 101 Arguments:
 102   s          SSL connection
 103   export     not used
 104   keylength  keylength
 105
 106 Returns:     pointer to generated key
 107 */
 108
 109 static RSA *
 110 rsa_callback(SSL *s, int export, int keylength)
 111 {
 112 RSA *rsa_key;
 113 export = export;     /* Shut picky compilers up */
 114 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
 115 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
 116 if (rsa_key == NULL)
 117   {
 118   ERR_error_string(ERR_get_error(), ssl_errstring);
 119   log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
 120     ssl_errstring);
 121   return NULL;
 122   }
 123 return rsa_key;
 124 }
 125
 126
 127
 128
 129 /*************************************************
 130 *        Callback for verification               *
 131 *************************************************/
 132
 133 /* The SSL library does certificate verification if set up to do so. This
 134 callback has the current yes/no state is in "state". If verification succeeded,
 135 we set up the tls_peerdn string. If verification failed, what happens depends
 136 on whether the client is required to present a verifiable certificate or not.
 137
 138 If verification is optional, we change the state to yes, but still log the
 139 verification error. For some reason (it really would help to have proper
 140 documentation of OpenSSL), this callback function then gets called again, this
 141 time with state = 1. In fact, that's useful, because we can set up the peerdn
 142 value, but we must take care not to set the private verified flag on the second
 143 time through.
 144
 145 Note: this function is not called if the client fails to present a certificate
 146 when asked. We get here only if a certificate has been received. Handling of
 147 optional verification for this case is done when requesting SSL to verify, by
 148 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
 149
 150 Arguments:
 151   state      current yes/no state as 1/0
 152   x509ctx    certificate information.
 153
 154 Returns:     1 if verified, 0 if not
 155 */
 156
 157 static int
 158 verify_callback(int state, X509_STORE_CTX *x509ctx)
 159 {
 160 static uschar txt[256];
 161
 162 X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert),
 163   CS txt, sizeof(txt));
 164
 165 if (state == 0)
 166   {
 167   log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
 168     x509ctx->error_depth,
 169     X509_verify_cert_error_string(x509ctx->error),
 170     txt);
 171   tls_certificate_verified = FALSE;
 172   verify_callback_called = TRUE;
 173   if (!verify_optional) return 0;    /* reject */
 174   DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
 175     "tls_try_verify_hosts)\n");
 176   return 1;                          /* accept */
 177   }
 178
 179 if (x509ctx->error_depth != 0)
 180   {
 181   DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n",
 182      x509ctx->error_depth, txt);
 183   }
 184 else
 185   {
 186   DEBUG(D_tls) debug_printf("SSL%s peer: %s\n",
 187     verify_callback_called? "" : " authenticated", txt);
 188   tls_peerdn = txt;
 189   }
 190
 191 if (!verify_callback_called) tls_certificate_verified = TRUE;
 192 verify_callback_called = TRUE;
 193
 194 return 1;   /* accept */
 195 }
 196
 197
 198
 199 /*************************************************
 200 *           Information callback                 *
 201 *************************************************/
 202
 203 /* The SSL library functions call this from time to time to indicate what they
 204 are doing. We copy the string to the debugging output when the level is high
 205 enough.
 206
 207 Arguments:
 208   s         the SSL connection
 209   where
 210   ret
 211
 212 Returns:    nothing
 213 */
 214
 215 static void
 216 info_callback(SSL *s, int where, int ret)
 217 {
 218 where = where;
 219 ret = ret;
 220 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
 221 }
 222
 223
 224
 225 /*************************************************
 226 *                Initialize for DH               *
 227 *************************************************/
 228
 229 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
 230
 231 Arguments:
 232   dhparam   DH parameter file
 233   host      connected host, if client; NULL if server
 234
 235 Returns:    TRUE if OK (nothing to set up, or setup worked)
 236 */
 237
 238 static BOOL
 239 init_dh(uschar *dhparam, host_item *host)
 240 {
 241 BOOL yield = TRUE;
 242 BIO *bio;
 243 DH *dh;
 244 uschar *dhexpanded;
 245
 246 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
 247   return FALSE;
 248
 249 if (dhexpanded == NULL) return TRUE;
 250
 251 if ((bio = BIO_new_file(CS dhexpanded, "r")) == NULL)
 252   {
 253   tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
 254     host, (uschar *)strerror(errno));
 255   yield = FALSE;
 256   }
 257 else
 258   {
 259   if ((dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)) == NULL)
 260     {
 261     tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
 262       host, NULL);
 263     yield = FALSE;
 264     }
 265   else
 266     {
 267     SSL_CTX_set_tmp_dh(ctx, dh);
 268     DEBUG(D_tls)
 269       debug_printf("Diffie-Hellman initialized from %s with %d-bit key\n",
 270         dhexpanded, 8*DH_size(dh));
 271     DH_free(dh);
 272     }
 273   BIO_free(bio);
 274   }
 275
 276 return yield;
 277 }
 278
 279
 280
 281
 282 /*************************************************
 283 *            Initialize for TLS                  *
 284 *************************************************/
 285
 286 /* Called from both server and client code, to do preliminary initialization of
 287 the library.
 288
 289 Arguments:
 290   host            connected host, if client; NULL if server
 291   dhparam         DH parameter file
 292   certificate     certificate file
 293   privatekey      private key
 294   addr            address if client; NULL if server (for some randomness)
 295
 296 Returns:          OK/DEFER/FAIL
 297 */
 298
 299 static int
 300 tls_init(host_item *host, uschar *dhparam, uschar *certificate,
 301   uschar *privatekey, address_item *addr)
 302 {
 303 long init_options;
 304 BOOL okay;
 305
 306 SSL_load_error_strings();          /* basic set up */
 307 OpenSSL_add_ssl_algorithms();
 308
 309 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
 310 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
 311 list of available digests. */
 312 EVP_add_digest(EVP_sha256());
 313 #endif
 314
 315 /* Create a context */
 316
 317 ctx = SSL_CTX_new((host == NULL)?
 318   SSLv23_server_method() : SSLv23_client_method());
 319
 320 if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
 321
 322 /* It turns out that we need to seed the random number generator this early in
 323 order to get the full complement of ciphers to work. It took me roughly a day
 324 of work to discover this by experiment.
 325
 326 On systems that have /dev/urandom, SSL may automatically seed itself from
 327 there. Otherwise, we have to make something up as best we can. Double check
 328 afterwards. */
 329
 330 if (!RAND_status())
 331   {
 332   randstuff r;
 333   gettimeofday(&r.tv, NULL);
 334   r.p = getpid();
 335
 336   RAND_seed((uschar *)(&r), sizeof(r));
 337   RAND_seed((uschar *)big_buffer, big_buffer_size);
 338   if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
 339
 340   if (!RAND_status())
 341     return tls_error(US"RAND_status", host,
 342       US"unable to seed random number generator");
 343   }
 344
 345 /* Set up the information callback, which outputs if debugging is at a suitable
 346 level. */
 347
 348 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
 349
 350 /* Automatically re-try reads/writes after renegotiation. */
 351 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
 352
 353 /* Apply administrator-supplied work-arounds.
 354 Historically we applied just one requested option,
 355 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
 356 moved to an administrator-controlled list of options to specify and
 357 grandfathered in the first one as the default value for "openssl_options".
 358
 359 No OpenSSL version number checks: the options we accept depend upon the
 360 availability of the option value macros from OpenSSL.  */
 361
 362 okay = tls_openssl_options_parse(openssl_options, &init_options);
 363 if (!okay)
 364   return tls_error(US"openssl_options parsing failed", host, NULL);
 365
 366 if (init_options)
 367   {
 368   DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
 369   if (!(SSL_CTX_set_options(ctx, init_options)))
 370     return tls_error(string_sprintf(
 371           "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
 372   }
 373 else
 374   DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
 375
 376 /* Initialize with DH parameters if supplied */
 377
 378 if (!init_dh(dhparam, host)) return DEFER;
 379
 380 /* Set up certificate and key */
 381
 382 if (certificate != NULL)
 383   {
 384   uschar *expanded;
 385   if (!expand_check(certificate, US"tls_certificate", &expanded))
 386     return DEFER;
 387
 388   if (expanded != NULL)
 389     {
 390     DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
 391     if (!SSL_CTX_use_certificate_chain_file(ctx, CS expanded))
 392       return tls_error(string_sprintf(
 393         "SSL_CTX_use_certificate_chain_file file=%s", expanded), host, NULL);
 394     }
 395
 396   if (privatekey != NULL &&
 397       !expand_check(privatekey, US"tls_privatekey", &expanded))
 398     return DEFER;
 399
 400   /* If expansion was forced to fail, key_expanded will be NULL. If the result
 401   of the expansion is an empty string, ignore it also, and assume the private
 402   key is in the same file as the certificate. */
 403
 404   if (expanded != NULL && *expanded != 0)
 405     {
 406     DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
 407     if (!SSL_CTX_use_PrivateKey_file(ctx, CS expanded, SSL_FILETYPE_PEM))
 408       return tls_error(string_sprintf(
 409         "SSL_CTX_use_PrivateKey_file file=%s", expanded), host, NULL);
 410     }
 411   }
 412
 413 /* Set up the RSA callback */
 414
 415 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
 416
 417 /* Finally, set the timeout, and we are done */
 418
 419 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
 420 DEBUG(D_tls) debug_printf("Initialized TLS\n");
 421 return OK;
 422 }
 423
 424
 425
 426
 427 /*************************************************
 428 *           Get name of cipher in use            *
 429 *************************************************/
 430
 431 /* The answer is left in a static buffer, and tls_cipher is set to point
 432 to it.
 433
 434 Argument:   pointer to an SSL structure for the connection
 435 Returns:    nothing
 436 */
 437
 438 static void
 439 construct_cipher_name(SSL *ssl)
 440 {
 441 static uschar cipherbuf[256];
 442 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
 443 yet reflect that.  It should be a safe change anyway, even 0.9.8 versions have
 444 the accessor functions use const in the prototype. */
 445 const SSL_CIPHER *c;
 446 uschar *ver;
 447
 448 switch (ssl->session->ssl_version)
 449   {
 450   case SSL2_VERSION:
 451   ver = US"SSLv2";
 452   break;
 453
 454   case SSL3_VERSION:
 455   ver = US"SSLv3";
 456   break;
 457
 458   case TLS1_VERSION:
 459   ver = US"TLSv1";
 460   break;
 461
 462 #ifdef TLS1_1_VERSION
 463   case TLS1_1_VERSION:
 464   ver = US"TLSv1.1";
 465   break;
 466 #endif
 467
 468 #ifdef TLS1_2_VERSION
 469   case TLS1_2_VERSION:
 470   ver = US"TLSv1.2";
 471   break;
 472 #endif
 473
 474   default:
 475   ver = US"UNKNOWN";
 476   }
 477
 478 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
 479 SSL_CIPHER_get_bits(c, &tls_bits);
 480
 481 string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver,
 482   SSL_CIPHER_get_name(c), tls_bits);
 483 tls_cipher = cipherbuf;
 484
 485 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
 486 }
 487
 488
 489
 490
 491
 492 /*************************************************
 493 *        Set up for verifying certificates       *
 494 *************************************************/
 495
 496 /* Called by both client and server startup
 497
 498 Arguments:
 499   certs         certs file or NULL
 500   crl           CRL file or NULL
 501   host          NULL in a server; the remote host in a client
 502   optional      TRUE if called from a server for a host in tls_try_verify_hosts;
 503                 otherwise passed as FALSE
 504
 505 Returns:        OK/DEFER/FAIL
 506 */
 507
 508 static int
 509 setup_certs(uschar *certs, uschar *crl, host_item *host, BOOL optional)
 510 {
 511 uschar *expcerts, *expcrl;
 512
 513 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
 514   return DEFER;
 515
 516 if (expcerts != NULL)
 517   {
 518   struct stat statbuf;
 519   if (!SSL_CTX_set_default_verify_paths(ctx))
 520     return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
 521
 522   if (Ustat(expcerts, &statbuf) < 0)
 523     {
 524     log_write(0, LOG_MAIN|LOG_PANIC,
 525       "failed to stat %s for certificates", expcerts);
 526     return DEFER;
 527     }
 528   else
 529     {
 530     uschar *file, *dir;
 531     if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
 532       { file = NULL; dir = expcerts; }
 533     else
 534       { file = expcerts; dir = NULL; }
 535
 536     /* If a certificate file is empty, the next function fails with an
 537     unhelpful error message. If we skip it, we get the correct behaviour (no
 538     certificates are recognized, but the error message is still misleading (it
 539     says no certificate was supplied.) But this is better. */
 540
 541     if ((file == NULL || statbuf.st_size > 0) &&
 542           !SSL_CTX_load_verify_locations(ctx, CS file, CS dir))
 543       return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
 544
 545     if (file != NULL)
 546       {
 547       SSL_CTX_set_client_CA_list(ctx, SSL_load_client_CA_file(CS file));
 548       }
 549     }
 550
 551   /* Handle a certificate revocation list. */
 552
 553   #if OPENSSL_VERSION_NUMBER > 0x00907000L
 554
 555   /* This bit of code is now the version supplied by Lars Mainka. (I have
 556    * merely reformatted it into the Exim code style.)
 557
 558    * "From here I changed the code to add support for multiple crl's
 559    * in pem format in one file or to support hashed directory entries in
 560    * pem format instead of a file. This method now uses the library function
 561    * X509_STORE_load_locations to add the CRL location to the SSL context.
 562    * OpenSSL will then handle the verify against CA certs and CRLs by
 563    * itself in the verify callback." */
 564
 565   if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
 566   if (expcrl != NULL && *expcrl != 0)
 567     {
 568     struct stat statbufcrl;
 569     if (Ustat(expcrl, &statbufcrl) < 0)
 570       {
 571       log_write(0, LOG_MAIN|LOG_PANIC,
 572         "failed to stat %s for certificates revocation lists", expcrl);
 573       return DEFER;
 574       }
 575     else
 576       {
 577       /* is it a file or directory? */
 578       uschar *file, *dir;
 579       X509_STORE *cvstore = SSL_CTX_get_cert_store(ctx);
 580       if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
 581         {
 582         file = NULL;
 583         dir = expcrl;
 584         DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
 585         }
 586       else
 587         {
 588         file = expcrl;
 589         dir = NULL;
 590         DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
 591         }
 592       if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
 593         return tls_error(US"X509_STORE_load_locations", host, NULL);
 594
 595       /* setting the flags to check against the complete crl chain */
 596
 597       X509_STORE_set_flags(cvstore,
 598         X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
 599       }
 600     }
 601
 602   #endif  /* OPENSSL_VERSION_NUMBER > 0x00907000L */
 603
 604   /* If verification is optional, don't fail if no certificate */
 605
 606   SSL_CTX_set_verify(ctx,
 607     SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
 608     verify_callback);
 609   }
 610
 611 return OK;
 612 }
 613
 614
 615
 616 /*************************************************
 617 *       Start a TLS session in a server          *
 618 *************************************************/
 619
 620 /* This is called when Exim is running as a server, after having received
 621 the STARTTLS command. It must respond to that command, and then negotiate
 622 a TLS session.
 623
 624 Arguments:
 625   require_ciphers   allowed ciphers
 626   ------------------------------------------------------
 627   require_mac      list of allowed MACs                 ) Not used
 628   require_kx       list of allowed key_exchange methods )   for
 629   require_proto    list of allowed protocols            ) OpenSSL
 630   ------------------------------------------------------
 631
 632 Returns:            OK on success
 633                     DEFER for errors before the start of the negotiation
 634                     FAIL for errors during the negotation; the server can't
 635                       continue running.
 636 */
 637
 638 int
 639 tls_server_start(uschar *require_ciphers, uschar *require_mac,
 640   uschar *require_kx, uschar *require_proto)
 641 {
 642 int rc;
 643 uschar *expciphers;
 644
 645 /* Check for previous activation */
 646
 647 if (tls_active >= 0)
 648   {
 649   tls_error(US"STARTTLS received after TLS started", NULL, US"");
 650   smtp_printf("554 Already in TLS\r\n");
 651   return FAIL;
 652   }
 653
 654 /* Initialize the SSL library. If it fails, it will already have logged
 655 the error. */
 656
 657 rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey, NULL);
 658 if (rc != OK) return rc;
 659
 660 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
 661   return FAIL;
 662
 663 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
 664 are separated by underscores. So that I can use either form in my tests, and
 665 also for general convenience, we turn underscores into hyphens here. */
 666
 667 if (expciphers != NULL)
 668   {
 669   uschar *s = expciphers;
 670   while (*s != 0) { if (*s == '_') *s = '-'; s++; }
 671   DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
 672   if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
 673     return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
 674   }
 675
 676 /* If this is a host for which certificate verification is mandatory or
 677 optional, set up appropriately. */
 678
 679 tls_certificate_verified = FALSE;
 680 verify_callback_called = FALSE;
 681
 682 if (verify_check_host(&tls_verify_hosts) == OK)
 683   {
 684   rc = setup_certs(tls_verify_certificates, tls_crl, NULL, FALSE);
 685   if (rc != OK) return rc;
 686   verify_optional = FALSE;
 687   }
 688 else if (verify_check_host(&tls_try_verify_hosts) == OK)
 689   {
 690   rc = setup_certs(tls_verify_certificates, tls_crl, NULL, TRUE);
 691   if (rc != OK) return rc;
 692   verify_optional = TRUE;
 693   }
 694
 695 /* Prepare for new connection */
 696
 697 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
 698 SSL_clear(ssl);
 699
 700 /* Set context and tell client to go ahead, except in the case of TLS startup
 701 on connection, where outputting anything now upsets the clients and tends to
 702 make them disconnect. We need to have an explicit fflush() here, to force out
 703 the response. Other smtp_printf() calls do not need it, because in non-TLS
 704 mode, the fflush() happens when smtp_getc() is called. */
 705
 706 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
 707 if (!tls_on_connect)
 708   {
 709   smtp_printf("220 TLS go ahead\r\n");
 710   fflush(smtp_out);
 711   }
 712
 713 /* Now negotiate the TLS session. We put our own timer on it, since it seems
 714 that the OpenSSL library doesn't. */
 715
 716 SSL_set_wfd(ssl, fileno(smtp_out));
 717 SSL_set_rfd(ssl, fileno(smtp_in));
 718 SSL_set_accept_state(ssl);
 719
 720 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
 721
 722 sigalrm_seen = FALSE;
 723 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
 724 rc = SSL_accept(ssl);
 725 alarm(0);
 726
 727 if (rc <= 0)
 728   {
 729   tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
 730   if (ERR_get_error() == 0)
 731     log_write(0, LOG_MAIN,
 732         "TLS client disconnected cleanly (rejected our certificate?)");
 733   return FAIL;
 734   }
 735
 736 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
 737
 738 /* TLS has been set up. Adjust the input functions to read via TLS,
 739 and initialize things. */
 740
 741 construct_cipher_name(ssl);
 742
 743 DEBUG(D_tls)
 744   {
 745   uschar buf[2048];
 746   if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL)
 747     debug_printf("Shared ciphers: %s\n", buf);
 748   }
 749
 750
 751 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
 752 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
 753 ssl_xfer_eof = ssl_xfer_error = 0;
 754
 755 receive_getc = tls_getc;
 756 receive_ungetc = tls_ungetc;
 757 receive_feof = tls_feof;
 758 receive_ferror = tls_ferror;
 759 receive_smtp_buffered = tls_smtp_buffered;
 760
 761 tls_active = fileno(smtp_out);
 762 return OK;
 763 }
 764
 765
 766
 767
 768
 769 /*************************************************
 770 *    Start a TLS session in a client             *
 771 *************************************************/
 772
 773 /* Called from the smtp transport after STARTTLS has been accepted.
 774
 775 Argument:
 776   fd               the fd of the connection
 777   host             connected host (for messages)
 778   addr             the first address
 779   dhparam          DH parameter file
 780   certificate      certificate file
 781   privatekey       private key file
 782   verify_certs     file for certificate verify
 783   crl              file containing CRL
 784   require_ciphers  list of allowed ciphers
 785   ------------------------------------------------------
 786   require_mac      list of allowed MACs                 ) Not used
 787   require_kx       list of allowed key_exchange methods )   for
 788   require_proto    list of allowed protocols            ) OpenSSL
 789   ------------------------------------------------------
 790   timeout          startup timeout
 791
 792 Returns:           OK on success
 793                    FAIL otherwise - note that tls_error() will not give DEFER
 794                      because this is not a server
 795 */
 796
 797 int
 798 tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam,
 799   uschar *certificate, uschar *privatekey, uschar *verify_certs, uschar *crl,
 800   uschar *require_ciphers, uschar *require_mac, uschar *require_kx,
 801   uschar *require_proto, int timeout)
 802 {
 803 static uschar txt[256];
 804 uschar *expciphers;
 805 X509* server_cert;
 806 int rc;
 807
 808 rc = tls_init(host, dhparam, certificate, privatekey, addr);
 809 if (rc != OK) return rc;
 810
 811 tls_certificate_verified = FALSE;
 812 verify_callback_called = FALSE;
 813
 814 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
 815   return FAIL;
 816
 817 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
 818 are separated by underscores. So that I can use either form in my tests, and
 819 also for general convenience, we turn underscores into hyphens here. */
 820
 821 if (expciphers != NULL)
 822   {
 823   uschar *s = expciphers;
 824   while (*s != 0) { if (*s == '_') *s = '-'; s++; }
 825   DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
 826   if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
 827     return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
 828   }
 829
 830 rc = setup_certs(verify_certs, crl, host, FALSE);
 831 if (rc != OK) return rc;
 832
 833 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
 834 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
 835 SSL_set_fd(ssl, fd);
 836 SSL_set_connect_state(ssl);
 837
 838 /* There doesn't seem to be a built-in timeout on connection. */
 839
 840 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
 841 sigalrm_seen = FALSE;
 842 alarm(timeout);
 843 rc = SSL_connect(ssl);
 844 alarm(0);
 845
 846 if (rc <= 0)
 847   return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
 848
 849 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
 850
 851 /* Beware anonymous ciphers which lead to server_cert being NULL */
 852 server_cert = SSL_get_peer_certificate (ssl);
 853 if (server_cert)
 854   {
 855   tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
 856     CS txt, sizeof(txt));
 857   tls_peerdn = txt;
 858   }
 859 else
 860   tls_peerdn = NULL;
 861
 862 construct_cipher_name(ssl);   /* Sets tls_cipher */
 863
 864 tls_active = fd;
 865 return OK;
 866 }
 867
 868
 869
 870
 871
 872 /*************************************************
 873 *            TLS version of getc                 *
 874 *************************************************/
 875
 876 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
 877 it refills the buffer via the SSL reading function.
 878
 879 Arguments:  none
 880 Returns:    the next character or EOF
 881 */
 882
 883 int
 884 tls_getc(void)
 885 {
 886 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
 887   {
 888   int error;
 889   int inbytes;
 890
 891   DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
 892     ssl_xfer_buffer, ssl_xfer_buffer_size);
 893
 894   if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
 895   inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
 896   error = SSL_get_error(ssl, inbytes);
 897   alarm(0);
 898
 899   /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
 900   closed down, not that the socket itself has been closed down. Revert to
 901   non-SSL handling. */
 902
 903   if (error == SSL_ERROR_ZERO_RETURN)
 904     {
 905     DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
 906
 907     receive_getc = smtp_getc;
 908     receive_ungetc = smtp_ungetc;
 909     receive_feof = smtp_feof;
 910     receive_ferror = smtp_ferror;
 911     receive_smtp_buffered = smtp_buffered;
 912
 913     SSL_free(ssl);
 914     ssl = NULL;
 915     tls_active = -1;
 916     tls_cipher = NULL;
 917     tls_peerdn = NULL;
 918
 919     return smtp_getc();
 920     }
 921
 922   /* Handle genuine errors */
 923
 924   else if (error == SSL_ERROR_SSL)
 925     {
 926     ERR_error_string(ERR_get_error(), ssl_errstring);
 927     log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
 928     ssl_xfer_error = 1;
 929     return EOF;
 930     }
 931
 932   else if (error != SSL_ERROR_NONE)
 933     {
 934     DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
 935     ssl_xfer_error = 1;
 936     return EOF;
 937     }
 938
 939 #ifndef DISABLE_DKIM
 940   dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
 941 #endif
 942   ssl_xfer_buffer_hwm = inbytes;
 943   ssl_xfer_buffer_lwm = 0;
 944   }
 945
 946 /* Something in the buffer; return next uschar */
 947
 948 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
 949 }
 950
 951
 952
 953 /*************************************************
 954 *          Read bytes from TLS channel           *
 955 *************************************************/
 956
 957 /*
 958 Arguments:
 959   buff      buffer of data
 960   len       size of buffer
 961
 962 Returns:    the number of bytes read
 963             -1 after a failed read
 964 */
 965
 966 int
 967 tls_read(uschar *buff, size_t len)
 968 {
 969 int inbytes;
 970 int error;
 971
 972 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
 973   buff, (unsigned int)len);
 974
 975 inbytes = SSL_read(ssl, CS buff, len);
 976 error = SSL_get_error(ssl, inbytes);
 977
 978 if (error == SSL_ERROR_ZERO_RETURN)
 979   {
 980   DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
 981   return -1;
 982   }
 983 else if (error != SSL_ERROR_NONE)
 984   {
 985   return -1;
 986   }
 987
 988 return inbytes;
 989 }
 990
 991
 992
 993
 994
 995 /*************************************************
 996 *         Write bytes down TLS channel           *
 997 *************************************************/
 998
 999 /*
1000 Arguments:
1001   buff      buffer of data
1002   len       number of bytes
1003
1004 Returns:    the number of bytes after a successful write,
1005             -1 after a failed write
1006 */
1007
1008 int
1009 tls_write(const uschar *buff, size_t len)
1010 {
1011 int outbytes;
1012 int error;
1013 int left = len;
1014
1015 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
1016 while (left > 0)
1017   {
1018   DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
1019   outbytes = SSL_write(ssl, CS buff, left);
1020   error = SSL_get_error(ssl, outbytes);
1021   DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1022   switch (error)
1023     {
1024     case SSL_ERROR_SSL:
1025     ERR_error_string(ERR_get_error(), ssl_errstring);
1026     log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1027     return -1;
1028
1029     case SSL_ERROR_NONE:
1030     left -= outbytes;
1031     buff += outbytes;
1032     break;
1033
1034     case SSL_ERROR_ZERO_RETURN:
1035     log_write(0, LOG_MAIN, "SSL channel closed on write");
1036     return -1;
1037
1038     default:
1039     log_write(0, LOG_MAIN, "SSL_write error %d", error);
1040     return -1;
1041     }
1042   }
1043 return len;
1044 }
1045
1046
1047
1048 /*************************************************
1049 *         Close down a TLS session               *
1050 *************************************************/
1051
1052 /* This is also called from within a delivery subprocess forked from the
1053 daemon, to shut down the TLS library, without actually doing a shutdown (which
1054 would tamper with the SSL session in the parent process).
1055
1056 Arguments:   TRUE if SSL_shutdown is to be called
1057 Returns:     nothing
1058 */
1059
1060 void
1061 tls_close(BOOL shutdown)
1062 {
1063 if (tls_active < 0) return;  /* TLS was not active */
1064
1065 if (shutdown)
1066   {
1067   DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
1068   SSL_shutdown(ssl);
1069   }
1070
1071 SSL_free(ssl);
1072 ssl = NULL;
1073
1074 tls_active = -1;
1075 }
1076
1077
1078
1079
1080 /*************************************************
1081 *         Report the library versions.           *
1082 *************************************************/
1083
1084 /* There have historically been some issues with binary compatibility in
1085 OpenSSL libraries; if Exim (like many other applications) is built against
1086 one version of OpenSSL but the run-time linker picks up another version,
1087 it can result in serious failures, including crashing with a SIGSEGV.  So
1088 report the version found by the compiler and the run-time version.
1089
1090 Arguments:   a FILE* to print the results to
1091 Returns:     nothing
1092 */
1093
1094 void
1095 tls_version_report(FILE *f)
1096 {
1097 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
1098            "                          Runtime: %s\n",
1099            OPENSSL_VERSION_TEXT,
1100            SSLeay_version(SSLEAY_VERSION));
1101 }
1102
1103
1104
1105
1106 /*************************************************
1107 *        Pseudo-random number generation         *
1108 *************************************************/
1109
1110 /* Pseudo-random number generation.  The result is not expected to be
1111 cryptographically strong but not so weak that someone will shoot themselves
1112 in the foot using it as a nonce in input in some email header scheme or
1113 whatever weirdness they'll twist this into.  The result should handle fork()
1114 and avoid repeating sequences.  OpenSSL handles that for us.
1115
1116 Arguments:
1117   max       range maximum
1118 Returns     a random number in range [0, max-1]
1119 */
1120
1121 int
1122 pseudo_random_number(int max)
1123 {
1124 unsigned int r;
1125 int i, needed_len;
1126 uschar *p;
1127 uschar smallbuf[sizeof(r)];
1128
1129 if (max <= 1)
1130   return 0;
1131
1132 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1133 if (!RAND_status())
1134   {
1135   randstuff r;
1136   gettimeofday(&r.tv, NULL);
1137   r.p = getpid();
1138
1139   RAND_seed((uschar *)(&r), sizeof(r));
1140   }
1141 /* We're after pseudo-random, not random; if we still don't have enough data
1142 in the internal PRNG then our options are limited.  We could sleep and hope
1143 for entropy to come along (prayer technique) but if the system is so depleted
1144 in the first place then something is likely to just keep taking it.  Instead,
1145 we'll just take whatever little bit of pseudo-random we can still manage to
1146 get. */
1147
1148 needed_len = sizeof(r);
1149 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
1150 asked for a number less than 10. */
1151 for (r = max, i = 0; r; ++i)
1152   r >>= 1;
1153 i = (i + 7) / 8;
1154 if (i < needed_len)
1155   needed_len = i;
1156
1157 /* We do not care if crypto-strong */
1158 (void) RAND_pseudo_bytes(smallbuf, needed_len);
1159 r = 0;
1160 for (p = smallbuf; needed_len; --needed_len, ++p)
1161   {
1162   r *= 256;
1163   r += *p;
1164   }
1165
1166 /* We don't particularly care about weighted results; if someone wants
1167 smooth distribution and cares enough then they should submit a patch then. */
1168 return r % max;
1169 }
1170
1171
1172
1173
1174 /*************************************************
1175 *        OpenSSL option parse                    *
1176 *************************************************/
1177
1178 /* Parse one option for tls_openssl_options_parse below
1179
1180 Arguments:
1181   name    one option name
1182   value   place to store a value for it
1183 Returns   success or failure in parsing
1184 */
1185
1186 struct exim_openssl_option {
1187   uschar *name;
1188   long    value;
1189 };
1190 /* We could use a macro to expand, but we need the ifdef and not all the
1191 options document which version they were introduced in.  Policylet: include
1192 all options unless explicitly for DTLS, let the administrator choose which
1193 to apply.
1194
1195 This list is current as of:
1196   ==>  1.0.1b  <==  */
1197 static struct exim_openssl_option exim_openssl_options[] = {
1198 /* KEEP SORTED ALPHABETICALLY! */
1199 #ifdef SSL_OP_ALL
1200   { US"all", SSL_OP_ALL },
1201 #endif
1202 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
1203   { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
1204 #endif
1205 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
1206   { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
1207 #endif
1208 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
1209   { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
1210 #endif
1211 #ifdef SSL_OP_EPHEMERAL_RSA
1212   { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
1213 #endif
1214 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
1215   { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
1216 #endif
1217 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
1218   { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
1219 #endif
1220 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
1221   { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
1222 #endif
1223 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
1224   { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
1225 #endif
1226 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
1227   { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
1228 #endif
1229 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
1230   { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
1231 #endif
1232 #ifdef SSL_OP_NO_COMPRESSION
1233   { US"no_compression", SSL_OP_NO_COMPRESSION },
1234 #endif
1235 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
1236   { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
1237 #endif
1238 #ifdef SSL_OP_NO_SSLv2
1239   { US"no_sslv2", SSL_OP_NO_SSLv2 },
1240 #endif
1241 #ifdef SSL_OP_NO_SSLv3
1242   { US"no_sslv3", SSL_OP_NO_SSLv3 },
1243 #endif
1244 #ifdef SSL_OP_NO_TICKET
1245   { US"no_ticket", SSL_OP_NO_TICKET },
1246 #endif
1247 #ifdef SSL_OP_NO_TLSv1
1248   { US"no_tlsv1", SSL_OP_NO_TLSv1 },
1249 #endif
1250 #ifdef SSL_OP_NO_TLSv1_1
1251 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
1252   /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
1253 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
1254 #else
1255   { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
1256 #endif
1257 #endif
1258 #ifdef SSL_OP_NO_TLSv1_2
1259   { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
1260 #endif
1261 #ifdef SSL_OP_SINGLE_DH_USE
1262   { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
1263 #endif
1264 #ifdef SSL_OP_SINGLE_ECDH_USE
1265   { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
1266 #endif
1267 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
1268   { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
1269 #endif
1270 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
1271   { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
1272 #endif
1273 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
1274   { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
1275 #endif
1276 #ifdef SSL_OP_TLS_D5_BUG
1277   { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
1278 #endif
1279 #ifdef SSL_OP_TLS_ROLLBACK_BUG
1280   { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
1281 #endif
1282 };
1283 static int exim_openssl_options_size =
1284   sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
1285
1286
1287 static BOOL
1288 tls_openssl_one_option_parse(uschar *name, long *value)
1289 {
1290 int first = 0;
1291 int last = exim_openssl_options_size;
1292 while (last > first)
1293   {
1294   int middle = (first + last)/2;
1295   int c = Ustrcmp(name, exim_openssl_options[middle].name);
1296   if (c == 0)
1297     {
1298     *value = exim_openssl_options[middle].value;
1299     return TRUE;
1300     }
1301   else if (c > 0)
1302     first = middle + 1;
1303   else
1304     last = middle;
1305   }
1306 return FALSE;
1307 }
1308
1309
1310
1311
1312 /*************************************************
1313 *        OpenSSL option parsing logic            *
1314 *************************************************/
1315
1316 /* OpenSSL has a number of compatibility options which an administrator might
1317 reasonably wish to set.  Interpret a list similarly to decode_bits(), so that
1318 we look like log_selector.
1319
1320 Arguments:
1321   option_spec  the administrator-supplied string of options
1322   results      ptr to long storage for the options bitmap
1323 Returns        success or failure
1324 */
1325
1326 BOOL
1327 tls_openssl_options_parse(uschar *option_spec, long *results)
1328 {
1329 long result, item;
1330 uschar *s, *end;
1331 uschar keep_c;
1332 BOOL adding, item_parsed;
1333
1334 result = 0L;
1335 /* We grandfather in as default the one option which we used to set always. */
1336 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
1337 result |= SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS;
1338 #endif
1339
1340 if (option_spec == NULL)
1341   {
1342   *results = result;
1343   return TRUE;
1344   }
1345
1346 for (s=option_spec; *s != '\0'; /**/)
1347   {
1348   while (isspace(*s)) ++s;
1349   if (*s == '\0')
1350     break;
1351   if (*s != '+' && *s != '-')
1352     {
1353     DEBUG(D_tls) debug_printf("malformed openssl option setting: "
1354         "+ or - expected but found \"%s\"\n", s);
1355     return FALSE;
1356     }
1357   adding = *s++ == '+';
1358   for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
1359   keep_c = *end;
1360   *end = '\0';
1361   item_parsed = tls_openssl_one_option_parse(s, &item);
1362   if (!item_parsed)
1363     {
1364     DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
1365     return FALSE;
1366     }
1367   DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
1368       adding ? "adding" : "removing", result, item, s);
1369   if (adding)
1370     result |= item;
1371   else
1372     result &= ~item;
1373   *end = keep_c;
1374   s = end;
1375   }
1376
1377 *results = result;
1378 return TRUE;
1379 }
1380
1381 /* End of tls-openssl.c */