citadel/modules/crypto/serv_crypto.c

   1 // Copyright (c) 1987-2021 by the citadel.org team
   2 //
   3 // This program is open source software; you can redistribute it and/or modify
   4 // it under the terms of the GNU General Public License version 3.
   5 //
   6 // This program is distributed in the hope that it will be useful,
   7 // but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 // GNU General Public License for more details.
  10
  11 #include <string.h>
  12 #include <unistd.h>
  13 #include <sys/stat.h>
  14 #include <sys/types.h>
  15 #include "sysdep.h"
  16
  17 #ifdef HAVE_OPENSSL
  18 #include <openssl/ssl.h>
  19 #include <openssl/err.h>
  20 #include <openssl/rand.h>
  21 #endif
  22
  23 #include <time.h>
  24
  25 #ifdef HAVE_PTHREAD_H
  26 #include <pthread.h>
  27 #endif
  28
  29 #ifdef HAVE_SYS_SELECT_H
  30 #include <sys/select.h>
  31 #endif
  32
  33 #include <stdio.h>
  34 #include <libcitadel.h>
  35 #include "server.h"
  36 #include "serv_crypto.h"
  37 #include "sysdep_decls.h"
  38 #include "citadel.h"
  39 #include "config.h"
  40 #include "ctdl_module.h"
  41
  42 #ifdef HAVE_OPENSSL
  43 SSL_CTX *ssl_ctx;                       // SSL context
  44 pthread_mutex_t **SSLCritters;          // Things needing locking
  45
  46
  47 static unsigned long id_callback(void) {
  48         return (unsigned long) pthread_self();
  49 }
  50
  51
  52 void generate_key(char *keyfilename) {
  53         int ret = 0;
  54         RSA *rsa = NULL;
  55         BIGNUM *bne = NULL;
  56         int bits = 2048;
  57         unsigned long e = RSA_F4;
  58         FILE *fp;
  59
  60         if (access(keyfilename, R_OK) == 0) {
  61                 return;
  62         }
  63
  64         syslog(LOG_INFO, "crypto: generating RSA key pair");
  65
  66         // generate rsa key
  67         bne = BN_new();
  68         ret = BN_set_word(bne,e);
  69         if (ret != 1) {
  70                 goto free_all;
  71         }
  72
  73         rsa = RSA_new();
  74         ret = RSA_generate_key_ex(rsa, bits, bne, NULL);
  75         if (ret != 1) {
  76                 goto free_all;
  77         }
  78
  79         // write the key file
  80         fp = fopen(keyfilename, "w");
  81         if (fp != NULL) {
  82                 chmod(keyfilename, 0600);
  83                 if (PEM_write_RSAPrivateKey(fp, // the file
  84                                         rsa,    // the key
  85                                         NULL,   // no enc
  86                                         NULL,   // no passphrase
  87                                         0,      // no passphrase
  88                                         NULL,   // no callback
  89                                         NULL    // no callback
  90                 ) != 1) {
  91                         syslog(LOG_ERR, "crypto: cannot write key: %s", ERR_reason_error_string(ERR_get_error()));
  92                         unlink(keyfilename);
  93                 }
  94                 fclose(fp);
  95         }
  96
  97     // free the memory we used
  98 free_all:
  99     RSA_free(rsa);
 100     BN_free(bne);
 101 }
 102
 103
 104 void init_ssl(void) {
 105         const SSL_METHOD *ssl_method;
 106         RSA *rsa = NULL;
 107         X509_REQ *req = NULL;
 108         X509 *cer = NULL;
 109         EVP_PKEY *pk = NULL;
 110         EVP_PKEY *req_pkey = NULL;
 111         X509_NAME *name = NULL;
 112         FILE *fp;
 113
 114         SSLCritters = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
 115         if (!SSLCritters) {
 116                 syslog(LOG_ERR, "crypto: can't allocate memory!");
 117                 exit(CTDLEXIT_CRYPTO);
 118         }
 119         else {
 120                 int a;
 121
 122                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 123                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
 124                         if (!SSLCritters[a]) {
 125                                 syslog(LOG_ERR, "crypto: can't allocate memory!!");
 126                                 exit(CTDLEXIT_CRYPTO);
 127                         }
 128                         pthread_mutex_init(SSLCritters[a], NULL);
 129                 }
 130         }
 131
 132         // Initialize SSL transport layer
 133         SSL_library_init();
 134         SSL_load_error_strings();
 135         ssl_method = SSLv23_server_method();
 136         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 137                 syslog(LOG_ERR, "crypto: SSL_CTX_new failed: %s", ERR_reason_error_string(ERR_get_error()));
 138                 return;
 139         }
 140         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 141                 syslog(LOG_ERR, "crypto: No ciphers available");
 142                 SSL_CTX_free(ssl_ctx);
 143                 ssl_ctx = NULL;
 144                 return;
 145         }
 146
 147         CRYPTO_set_locking_callback(ssl_lock);
 148         CRYPTO_set_id_callback(id_callback);
 149
 150         mkdir(ctdl_key_dir, 0700);              // If the keys directory does not exist, create it
 151         generate_key(file_crpt_file_key);       // If a private key does not exist, create it
 152
 153         // If there is no certificate file on disk, we will be generating a self-signed certificate
 154         // in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 155         // the CSR in this step so that the next step may commence.
 156         if ( (access(file_crpt_file_cer, R_OK) != 0) && (access(file_crpt_file_csr, R_OK) != 0) ) {
 157                 syslog(LOG_INFO, "crypto: generating a generic certificate signing request.");
 158
 159                 // Read our key from the file.  No, we don't just keep this
 160                 // in memory from the above key-generation function, because
 161                 // there is the possibility that the key was already on disk
 162                 // and we didn't just generate it now.
 163                 fp = fopen(file_crpt_file_key, "r");
 164                 if (fp) {
 165                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 166                         fclose(fp);
 167                 }
 168
 169                 if (rsa) {
 170
 171                         // Create a public key from the private key
 172                         if (pk=EVP_PKEY_new(), pk != NULL) {
 173                                 EVP_PKEY_assign_RSA(pk, rsa);
 174                                 if (req = X509_REQ_new(), req != NULL) {
 175
 176                                         // Set the public key
 177                                         X509_REQ_set_pubkey(req, pk);
 178                                         X509_REQ_set_version(req, 0L);
 179
 180                                         name = X509_REQ_get_subject_name(req);
 181
 182                                         // Tell it who we are
 183                                         X509_NAME_add_entry_by_txt(name, "C", MBSTRING_ASC, (unsigned const char *)"ZZ", -1, -1, 0);
 184                                         X509_NAME_add_entry_by_txt(name, "ST", MBSTRING_ASC, (unsigned const char *)"The World", -1, -1, 0);
 185                                         X509_NAME_add_entry_by_txt(name, "L", MBSTRING_ASC, (unsigned const char *)"My Location", -1, -1, 0);
 186                                         X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, (unsigned const char *)"Generic certificate", -1, -1, 0);
 187                                         X509_NAME_add_entry_by_txt(name, "OU", MBSTRING_ASC, (unsigned const char *)"Citadel server", -1, -1, 0);
 188                                         X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, (unsigned const char *)"*", -1, -1, 0);
 189                                         X509_REQ_set_subject_name(req, name);
 190
 191                                         // Sign the CSR
 192                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 193                                                 syslog(LOG_ERR, "crypto: X509_REQ_sign(): error");
 194                                         }
 195                                         else {
 196                                                 // Write it to disk
 197                                                 fp = fopen(file_crpt_file_csr, "w");
 198                                                 if (fp != NULL) {
 199                                                         chmod(file_crpt_file_csr, 0600);
 200                                                         PEM_write_X509_REQ(fp, req);
 201                                                         fclose(fp);
 202                                                 }
 203                                         }
 204
 205                                         X509_REQ_free(req);
 206                                 }
 207                         }
 208
 209                         RSA_free(rsa);
 210                 }
 211
 212                 else {
 213                         syslog(LOG_ERR, "crypto: unable to read private key.");
 214                 }
 215         }
 216
 217         // Generate a self-signed certificate if we don't have one.
 218         if (access(file_crpt_file_cer, R_OK) != 0) {
 219                 syslog(LOG_INFO, "crypto: generating a generic self-signed certificate.");
 220
 221                 // Same deal as before: always read the key from disk because
 222                 // it may or may not have just been generated.
 223                 fp = fopen(file_crpt_file_key, "r");
 224                 if (fp) {
 225                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 226                         fclose(fp);
 227                 }
 228
 229                 // This also holds true for the CSR.
 230                 req = NULL;
 231                 cer = NULL;
 232                 pk = NULL;
 233                 if (rsa) {
 234                         if (pk=EVP_PKEY_new(), pk != NULL) {
 235                                 EVP_PKEY_assign_RSA(pk, rsa);
 236                         }
 237
 238                         fp = fopen(file_crpt_file_csr, "r");
 239                         if (fp) {
 240                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 241                                 fclose(fp);
 242                         }
 243
 244                         if (req) {
 245                                 if (cer = X509_new(), cer != NULL) {
 246                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 247                                         X509_set_issuer_name(cer, X509_REQ_get_subject_name(req));
 248                                         X509_set_subject_name(cer, X509_REQ_get_subject_name(req));
 249                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 250                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 251                                         req_pkey = X509_REQ_get_pubkey(req);
 252                                         X509_set_pubkey(cer, req_pkey);
 253                                         EVP_PKEY_free(req_pkey);
 254
 255                                         // Sign the cert
 256                                         if (!X509_sign(cer, pk, EVP_md5())) {
 257                                                 syslog(LOG_ERR, "crypto: X509_sign() error");
 258                                         }
 259                                         else {
 260                                                 // Write it to disk.
 261                                                 fp = fopen(file_crpt_file_cer, "w");
 262                                                 if (fp != NULL) {
 263                                                         chmod(file_crpt_file_cer, 0600);
 264                                                         PEM_write_X509(fp, cer);
 265                                                         fclose(fp);
 266                                                 }
 267                                         }
 268                                         X509_free(cer);
 269                                 }
 270                         }
 271
 272                         RSA_free(rsa);
 273                 }
 274         }
 275
 276         // Now try to bind to the key and certificate.
 277         SSL_CTX_use_certificate_chain_file(ssl_ctx, file_crpt_file_cer);
 278         SSL_CTX_use_PrivateKey_file(ssl_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 279         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 280                 syslog(LOG_ERR, "crypto: cannot install certificate: %s", ERR_reason_error_string(ERR_get_error()));
 281         }
 282
 283         // Finally let the server know we're here
 284         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 285         CtdlRegisterProtoHook(cmd_gtls, "GTLS", "Get SSL/TLS session status");
 286         CtdlRegisterSessionHook(endtls, EVT_STOP, PRIO_STOP + 10);
 287 }
 288
 289
 290 // client_write_ssl() Send binary data to the client encrypted.
 291 void client_write_ssl(const char *buf, int nbytes) {
 292         int retval;
 293         int nremain;
 294         char junk[1];
 295
 296         nremain = nbytes;
 297
 298         while (nremain > 0) {
 299                 if (SSL_want_write(CC->ssl)) {
 300                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 301                                 syslog(LOG_DEBUG, "crypto: SSL_read in client_write: %s", ERR_reason_error_string(ERR_get_error()));
 302                         }
 303                 }
 304                 retval =
 305                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 306                 if (retval < 1) {
 307                         long errval;
 308
 309                         errval = SSL_get_error(CC->ssl, retval);
 310                         if (errval == SSL_ERROR_WANT_READ ||
 311                             errval == SSL_ERROR_WANT_WRITE) {
 312                                 sleep(1);
 313                                 continue;
 314                         }
 315                         syslog(LOG_DEBUG, "crypto: SSL_write got error %ld, ret %d", errval, retval);
 316                         if (retval == -1) {
 317                                 syslog(LOG_DEBUG, "crypto: errno is %d", errno);
 318                         }
 319                         endtls();
 320                         client_write(&buf[nbytes - nremain], nremain);
 321                         return;
 322                 }
 323                 nremain -= retval;
 324         }
 325 }
 326
 327
 328 // read data from the encrypted layer.
 329 int client_read_sslbuffer(StrBuf *buf, int timeout) {
 330         char sbuf[16384];       // OpenSSL communicates in 16k blocks, so let's speak its native tongue.
 331         int rlen;
 332         char junk[1];
 333         SSL *pssl = CC->ssl;
 334
 335         if (pssl == NULL) return(-1);
 336
 337         while (1) {
 338                 if (SSL_want_read(pssl)) {
 339                         if ((SSL_write(pssl, junk, 0)) < 1) {
 340                                 syslog(LOG_DEBUG, "crypto: SSL_write in client_read");
 341                         }
 342                 }
 343                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 344                 if (rlen < 1) {
 345                         long errval;
 346
 347                         errval = SSL_get_error(pssl, rlen);
 348                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 349                                 sleep(1);
 350                                 continue;
 351                         }
 352                         syslog(LOG_DEBUG, "crypto: SSL_read got error %ld", errval);
 353                         endtls();
 354                         return (-1);
 355                 }
 356                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 357                 return rlen;
 358         }
 359         return (0);
 360 }
 361
 362
 363 int client_readline_sslbuffer(StrBuf *Line, StrBuf *IOBuf, const char **Pos, int timeout) {
 364         const char *pos = NULL;
 365         const char *pLF;
 366         int len, rlen;
 367         int nSuccessLess = 0;
 368         const char *pch = NULL;
 369
 370         if ((Line == NULL) || (Pos == NULL) || (IOBuf == NULL))
 371         {
 372                 if (Pos != NULL)
 373                 {
 374                         *Pos = NULL;
 375                 }
 376                 return -1;
 377         }
 378
 379         pos = *Pos;
 380         if ((StrLength(IOBuf) > 0) && (pos != NULL) && (pos < ChrPtr(IOBuf) + StrLength(IOBuf)))
 381         {
 382                 pch = pos;
 383                 pch = strchr(pch, '\n');
 384
 385                 if (pch == NULL) {
 386                         StrBufAppendBufPlain(Line, pos, StrLength(IOBuf) - (pos - ChrPtr(IOBuf)), 0);
 387                         FlushStrBuf(IOBuf);
 388                         *Pos = NULL;
 389                 }
 390                 else {
 391                         int n = 0;
 392                         if ((pch > ChrPtr(IOBuf)) &&
 393                             (*(pch - 1) == '\r')) {
 394                                 n = 1;
 395                         }
 396                         StrBufAppendBufPlain(Line, pos,
 397                                              (pch - pos - n), 0);
 398
 399                         if (StrLength(IOBuf) <= (pch - ChrPtr(IOBuf) + 1)) {
 400                                 FlushStrBuf(IOBuf);
 401                                 *Pos = NULL;
 402                         }
 403                         else
 404                                 *Pos = pch + 1;
 405                         return StrLength(Line);
 406                 }
 407         }
 408
 409         pLF = NULL;
 410         while ((nSuccessLess < timeout) &&
 411                (pLF == NULL) &&
 412                (CC->ssl != NULL)) {
 413
 414                 rlen = client_read_sslbuffer(IOBuf, timeout);
 415                 if (rlen < 1) {
 416                         return -1;
 417                 }
 418                 else if (rlen > 0) {
 419                         pLF = strchr(ChrPtr(IOBuf), '\n');
 420                 }
 421         }
 422         *Pos = NULL;
 423         if (pLF != NULL) {
 424                 pos = ChrPtr(IOBuf);
 425                 len = pLF - pos;
 426                 if (len > 0 && (*(pLF - 1) == '\r') )
 427                         len --;
 428                 StrBufAppendBufPlain(Line, pos, len, 0);
 429                 if (pLF + 1 >= ChrPtr(IOBuf) + StrLength(IOBuf))
 430                 {
 431                         FlushStrBuf(IOBuf);
 432                 }
 433                 else
 434                         *Pos = pLF + 1;
 435                 return StrLength(Line);
 436         }
 437         return -1;
 438 }
 439
 440
 441 int client_read_sslblob(StrBuf *Target, long bytes, int timeout) {
 442         long baselen;
 443         long RemainRead;
 444         int retval = 0;
 445
 446         baselen = StrLength(Target);
 447
 448         if (StrLength(CC->RecvBuf.Buf) > 0) {
 449                 long RemainLen;
 450                 long TotalLen;
 451                 const char *pchs;
 452
 453                 if (CC->RecvBuf.ReadWritePointer == NULL) {
 454                         CC->RecvBuf.ReadWritePointer = ChrPtr(CC->RecvBuf.Buf);
 455                 }
 456                 pchs = ChrPtr(CC->RecvBuf.Buf);
 457                 TotalLen = StrLength(CC->RecvBuf.Buf);
 458                 RemainLen = TotalLen - (pchs - CC->RecvBuf.ReadWritePointer);
 459                 if (RemainLen > bytes) {
 460                         RemainLen = bytes;
 461                 }
 462                 if (RemainLen > 0) {
 463                         StrBufAppendBufPlain(Target, CC->RecvBuf.ReadWritePointer, RemainLen, 0);
 464                         CC->RecvBuf.ReadWritePointer += RemainLen;
 465                 }
 466                 if ((ChrPtr(CC->RecvBuf.Buf) + StrLength(CC->RecvBuf.Buf)) <= CC->RecvBuf.ReadWritePointer) {
 467                         CC->RecvBuf.ReadWritePointer = NULL;
 468                         FlushStrBuf(CC->RecvBuf.Buf);
 469                 }
 470         }
 471
 472         if (StrLength(Target) >= bytes + baselen) {
 473                 return 1;
 474         }
 475
 476         CC->RecvBuf.ReadWritePointer = NULL;
 477
 478         while ((StrLength(Target) < bytes + baselen) && (retval >= 0)) {
 479                 retval = client_read_sslbuffer(CC->RecvBuf.Buf, timeout);
 480                 if (retval >= 0) {
 481                         RemainRead = bytes - (StrLength (Target) - baselen);
 482                         if (RemainRead < StrLength(CC->RecvBuf.Buf)) {
 483                                 StrBufAppendBufPlain(
 484                                         Target,
 485                                         ChrPtr(CC->RecvBuf.Buf),
 486                                         RemainRead, 0);
 487                                 CC->RecvBuf.ReadWritePointer = ChrPtr(CC->RecvBuf.Buf) + RemainRead;
 488                                 break;
 489                         }
 490                         StrBufAppendBuf(Target, CC->RecvBuf.Buf, 0);    // todo: Buf > bytes?
 491                         FlushStrBuf(CC->RecvBuf.Buf);
 492                 }
 493                 else {
 494                         FlushStrBuf(CC->RecvBuf.Buf);
 495                         return -1;
 496
 497                 }
 498         }
 499         return 1;
 500 }
 501
 502
 503 // CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 504 // must be supplied with pre-generated strings for responses of "ok," "no
 505 // support for TLS," and "error" so that we can use this in any protocol.
 506 void CtdlStartTLS(char *ok_response, char *nosup_response, char *error_response) {
 507         int retval, bits, alg_bits;
 508
 509         if (CC->redirect_ssl) {
 510                 syslog(LOG_ERR, "crypto: attempt to begin SSL on an already encrypted connection");
 511                 if (error_response != NULL) {
 512                         cprintf("%s", error_response);
 513                 }
 514                 return;
 515         }
 516
 517         if (!ssl_ctx) {
 518                 syslog(LOG_ERR, "crypto: SSL failed: no ssl_ctx exists?");
 519                 if (nosup_response != NULL) cprintf("%s", nosup_response);
 520                 return;
 521         }
 522         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 523                 syslog(LOG_ERR, "crypto: SSL_new failed: %s", ERR_reason_error_string(ERR_get_error()));
 524                 if (error_response != NULL) {
 525                         cprintf("%s", error_response);
 526                 }
 527                 return;
 528         }
 529         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 530                 syslog(LOG_ERR, "crypto: SSL_set_fd failed: %s", ERR_reason_error_string(ERR_get_error()));
 531                 SSL_free(CC->ssl);
 532                 CC->ssl = NULL;
 533                 if (error_response != NULL) cprintf("%s", error_response);
 534                 return;
 535         }
 536         if (ok_response != NULL) cprintf("%s", ok_response);
 537         retval = SSL_accept(CC->ssl);
 538         if (retval < 1) {
 539                 // Can't notify the client of an error here; they will
 540                 // discover the problem at the SSL layer and should
 541                 // revert to unencrypted communications.
 542                 long errval;
 543                 char error_string[128];
 544
 545                 errval = SSL_get_error(CC->ssl, retval);
 546                 syslog(LOG_ERR, "crypto: SSL_accept failed: retval=%d, errval=%ld, err=%s",
 547                         retval,
 548                         errval,
 549                         ERR_error_string(errval, error_string)
 550                 );
 551                 SSL_free(CC->ssl);
 552                 CC->ssl = NULL;
 553                 return;
 554         }
 555         // BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE); not needed anymore in openssl 1.1 ?
 556         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 557         syslog(LOG_INFO, "crypto: SSL/TLS using %s on %s (%d of %d bits)",
 558                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 559                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 560                 bits, alg_bits
 561         );
 562         CC->redirect_ssl = 1;
 563 }
 564
 565
 566 // cmd_stls() starts SSL/TLS encryption for the current session
 567 void cmd_stls(char *params) {
 568         char ok_response[SIZ];
 569         char nosup_response[SIZ];
 570         char error_response[SIZ];
 571
 572         unbuffer_output();
 573
 574         sprintf(ok_response, "%d Begin TLS negotiation now\n", CIT_OK);
 575         sprintf(nosup_response, "%d TLS not supported here\n", ERROR + CMD_NOT_SUPPORTED);
 576         sprintf(error_response, "%d TLS negotiation error\n", ERROR + INTERNAL_ERROR);
 577
 578         CtdlStartTLS(ok_response, nosup_response, error_response);
 579 }
 580
 581
 582 // cmd_gtls() returns status info about the TLS connection
 583 void cmd_gtls(char *params) {
 584         int bits, alg_bits;
 585
 586         if (!CC->ssl || !CC->redirect_ssl) {
 587                 cprintf("%d Session is not encrypted.\n", ERROR);
 588                 return;
 589         }
 590         bits =
 591             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 592                                 &alg_bits);
 593         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 594                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 595                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 596                 alg_bits, bits);
 597 }
 598
 599
 600 // endtls() shuts down the TLS connection
 601 //
 602 // WARNING:  This may make your session vulnerable to a known plaintext
 603 // attack in the current implmentation.
 604 void endtls(void) {
 605         if (!CC->ssl) {
 606                 CC->redirect_ssl = 0;
 607                 return;
 608         }
 609
 610         syslog(LOG_INFO, "crypto: ending SSL/TLS");
 611         SSL_shutdown(CC->ssl);
 612         SSL_free(CC->ssl);
 613         CC->ssl = NULL;
 614         CC->redirect_ssl = 0;
 615 }
 616
 617
 618 // ssl_lock() callback for OpenSSL mutex locks
 619 void ssl_lock(int mode, int n, const char *file, int line) {
 620         if (mode & CRYPTO_LOCK) {
 621                 pthread_mutex_lock(SSLCritters[n]);
 622         }
 623         else {
 624                 pthread_mutex_unlock(SSLCritters[n]);
 625         }
 626 }
 627 #endif  // HAVE_OPENSSL