citadel/modules/crypto/serv_crypto.c

   1 // Copyright (c) 1987-2022 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
  44 SSL_CTX *ssl_ctx = NULL;                // This SSL context is used for all sessions.
  45
  46
  47 // If a private key does not exist, generate one now.
  48 void generate_key(char *keyfilename) {
  49         int ret = 0;
  50         RSA *rsa = NULL;
  51         BIGNUM *bne = NULL;
  52         int bits = 2048;
  53         unsigned long e = RSA_F4;
  54         FILE *fp;
  55
  56         if (access(keyfilename, R_OK) == 0) {   // Already have one.
  57                 return;
  58         }
  59
  60         syslog(LOG_INFO, "crypto: generating RSA key pair");
  61
  62         // generate rsa key
  63         bne = BN_new();
  64         ret = BN_set_word(bne,e);
  65         if (ret != 1) {
  66                 goto free_all;
  67         }
  68
  69         rsa = RSA_new();
  70         ret = RSA_generate_key_ex(rsa, bits, bne, NULL);
  71         if (ret != 1) {
  72                 goto free_all;
  73         }
  74
  75         // write the key file
  76         fp = fopen(keyfilename, "w");
  77         if (fp != NULL) {
  78                 chmod(keyfilename, 0600);
  79                 if (PEM_write_RSAPrivateKey(fp, // the file
  80                                         rsa,    // the key
  81                                         NULL,   // no enc
  82                                         NULL,   // no passphrase
  83                                         0,      // no passphrase
  84                                         NULL,   // no callback
  85                                         NULL    // no callback
  86                 ) != 1) {
  87                         syslog(LOG_ERR, "crypto: cannot write key: %s", ERR_reason_error_string(ERR_get_error()));
  88                         unlink(keyfilename);
  89                 }
  90                 fclose(fp);
  91         }
  92
  93         // free the memory we used
  94 free_all:
  95         RSA_free(rsa);
  96         BN_free(bne);
  97 }
  98
  99
 100 // If a certificate does not exist, generate a self-signed one now.
 101 void generate_certificate(char *keyfilename, char *certfilename) {
 102         RSA *private_key = NULL;
 103         EVP_PKEY *public_key = NULL;
 104         X509_REQ *certificate_signing_request = NULL;
 105         X509_NAME *name = NULL;
 106         X509 *certificate = NULL;
 107         FILE *fp;
 108
 109         if (access(certfilename, R_OK) == 0) {                  // already have one.
 110                 return;
 111         }
 112
 113         syslog(LOG_INFO, "crypto: generating a self-signed certificate");
 114
 115         // Read in our private key.
 116         fp = fopen(keyfilename, "r");
 117         if (fp) {
 118                 private_key = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 119                 fclose(fp);
 120         }
 121
 122         if (!private_key) {
 123                 syslog(LOG_ERR, "crypto: cannot read the private key");
 124                 return;
 125         }
 126
 127         // Create a public key from the private key
 128         public_key = EVP_PKEY_new();
 129         if (!public_key) {
 130                 syslog(LOG_ERR, "crypto: cannot allocate public key");
 131                 RSA_free(private_key);
 132                 return;
 133         }
 134         EVP_PKEY_assign_RSA(public_key, private_key);
 135
 136         // Create a certificate signing request
 137         certificate_signing_request = X509_REQ_new();
 138         if (!certificate_signing_request) {
 139                 syslog(LOG_ERR, "crypto: cannot allocate certificate signing request");
 140                 RSA_free(private_key);
 141                 EVP_PKEY_free(public_key);
 142                 return;
 143         }
 144
 145         // Assign the public key to the certificate signing request
 146         X509_REQ_set_pubkey(certificate_signing_request, public_key);
 147         X509_REQ_set_version(certificate_signing_request, 0L);
 148
 149         // Tell it who we are
 150         name = X509_REQ_get_subject_name(certificate_signing_request);
 151         X509_NAME_add_entry_by_txt(name, "C", MBSTRING_ASC, (unsigned const char *)"ZZ", -1, -1, 0);
 152         X509_NAME_add_entry_by_txt(name, "ST", MBSTRING_ASC, (unsigned const char *)"The World", -1, -1, 0);
 153         X509_NAME_add_entry_by_txt(name, "L", MBSTRING_ASC, (unsigned const char *)"My Location", -1, -1, 0);
 154         X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, (unsigned const char *)"Generic certificate", -1, -1, 0);
 155         X509_NAME_add_entry_by_txt(name, "OU", MBSTRING_ASC, (unsigned const char *)"Citadel server", -1, -1, 0);
 156         X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, (unsigned const char *)"*", -1, -1, 0);
 157         X509_REQ_set_subject_name(certificate_signing_request, name);
 158
 159         // Sign the CSR
 160         if (!X509_REQ_sign(certificate_signing_request, public_key, EVP_md5())) {
 161                 syslog(LOG_ERR, "crypto: X509_REQ_sign(): error");
 162                 X509_REQ_free(certificate_signing_request);
 163                 RSA_free(private_key);
 164                 EVP_PKEY_free(public_key);
 165                 return;
 166         }
 167
 168         // Generate the self-signed certificate
 169         certificate = X509_new();
 170         if (!certificate) {
 171                 syslog(LOG_ERR, "crypto: cannot allocate X.509 certificate");
 172                 X509_REQ_free(certificate_signing_request);
 173                 RSA_free(private_key);
 174                 EVP_PKEY_free(public_key);
 175                 return;
 176         }
 177
 178         ASN1_INTEGER_set(X509_get_serialNumber(certificate), 0);
 179         X509_set_issuer_name(certificate, X509_REQ_get_subject_name(certificate_signing_request));
 180         X509_set_subject_name(certificate, X509_REQ_get_subject_name(certificate_signing_request));
 181         X509_gmtime_adj(X509_get_notBefore(certificate), 0);
 182         X509_gmtime_adj(X509_get_notAfter(certificate), (long)60*60*24*SIGN_DAYS);
 183         X509_set_pubkey(certificate, public_key);
 184         X509_REQ_free(certificate_signing_request);             // We're done with the CSR; free it
 185
 186         // Finally, sign the certificate with our private key.
 187         if (!X509_sign(certificate, public_key, EVP_md5())) {
 188                 syslog(LOG_ERR, "crypto: X509_sign() error");
 189                 X509_free(certificate);
 190                 RSA_free(private_key);
 191                 EVP_PKEY_free(public_key);
 192                 return;
 193         }
 194
 195         // Write the certificate to disk
 196         fp = fopen(certfilename, "w");
 197         if (fp != NULL) {
 198                 chmod(certfilename, 0600);
 199                 PEM_write_X509(fp, certificate);
 200                 fclose(fp);
 201         }
 202         else {
 203                 syslog(LOG_ERR, "crypto: %s: %m", certfilename);
 204         }
 205
 206         X509_free(certificate);
 207         EVP_PKEY_free(public_key);
 208         // RSA_free(private_key);                               // private_key is freed by EVP_PKEY_free() above
 209 }
 210
 211
 212 // Set the private key and certificate chain for the global SSL Context.
 213 // This is called during initialization, and can be called again later if the certificate changes.
 214 void bind_to_key_and_certificate(void) {
 215
 216         SSL_CTX *old_ctx = NULL;
 217         SSL_CTX *new_ctx = NULL;
 218
 219         if (!(new_ctx = SSL_CTX_new(TLS_server_method()))) {
 220                 syslog(LOG_ERR, "crypto: SSL_CTX_new failed: %s", ERR_reason_error_string(ERR_get_error()));
 221                 return;
 222         }
 223
 224         syslog(LOG_DEBUG, "crypto: using certificate chain %s", file_crpt_file_cer);
 225         SSL_CTX_use_certificate_chain_file(new_ctx, file_crpt_file_cer);
 226
 227         syslog(LOG_DEBUG, "crypto: using private key %s", file_crpt_file_key);
 228         SSL_CTX_use_PrivateKey_file(new_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 229         if ( !SSL_CTX_check_private_key(new_ctx) ) {
 230                 syslog(LOG_ERR, "crypto: cannot install certificate: %s", ERR_reason_error_string(ERR_get_error()));
 231         }
 232
 233         old_ctx = ssl_ctx;
 234         ssl_ctx = new_ctx;              // All future binds will use the new certificate
 235
 236         if (old_ctx != NULL) {
 237                 sleep(1);               // Hopefully wait until all in-progress binds to the old certificate have completed
 238                 SSL_CTX_free(old_ctx);
 239         }
 240 }
 241
 242
 243 // Check the modification time of the key and certificate files.  Reload if either one changed.
 244 void update_key_and_cert_if_needed(void) {
 245         static time_t previous_mtime = 0;
 246         struct stat keystat;
 247         struct stat certstat;
 248
 249         if (stat(file_crpt_file_key, &keystat) != 0) {
 250                 syslog(LOG_ERR, "%s: %s", file_crpt_file_key, strerror(errno));
 251                 return;
 252         }
 253         if (stat(file_crpt_file_cer, &certstat) != 0) {
 254                 syslog(LOG_ERR, "%s: %s", file_crpt_file_cer, strerror(errno));
 255                 return;
 256         }
 257
 258         if ((keystat.st_mtime + certstat.st_mtime) != previous_mtime) {
 259                 begin_critical_section(S_OPENSSL);
 260                 bind_to_key_and_certificate();
 261                 end_critical_section(S_OPENSSL);
 262                 previous_mtime = keystat.st_mtime + certstat.st_mtime;
 263         }
 264 }
 265
 266
 267 // Initialize the TLS subsystem.
 268 void init_ssl(void) {
 269
 270         // Initialize the OpenSSL library
 271         SSL_load_error_strings();
 272         ERR_load_crypto_strings();
 273         OpenSSL_add_all_algorithms();
 274         SSL_library_init();
 275
 276         // Load (or generate) a key and certificate
 277         mkdir(ctdl_key_dir, 0700);                                      // If the keys directory does not exist, create it
 278         generate_key(file_crpt_file_key);                               // If a private key does not exist, create it
 279         generate_certificate(file_crpt_file_key, file_crpt_file_cer);   // If a certificate does not exist, create it
 280         bind_to_key_and_certificate();                                  // Load key and cert from disk, and bind to them.
 281
 282         // Register some Citadel protocol commands for dealing with encrypted sessions
 283         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start TLS session");
 284         CtdlRegisterProtoHook(cmd_gtls, "GTLS", "Get TLS session status");
 285         CtdlRegisterSessionHook(endtls, EVT_STOP, PRIO_STOP + 10);
 286 }
 287
 288
 289 // client_write_ssl() Send binary data to the client encrypted.
 290 void client_write_ssl(const char *buf, int nbytes) {
 291         int retval;
 292         int nremain;
 293         char junk[1];
 294
 295         nremain = nbytes;
 296
 297         while (nremain > 0) {
 298                 if (SSL_want_write(CC->ssl)) {
 299                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 300                                 syslog(LOG_DEBUG, "crypto: SSL_read in client_write: %s", ERR_reason_error_string(ERR_get_error()));
 301                         }
 302                 }
 303                 retval =
 304                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 305                 if (retval < 1) {
 306                         long errval;
 307
 308                         errval = SSL_get_error(CC->ssl, retval);
 309                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 310                                 sleep(1);
 311                                 continue;
 312                         }
 313                         syslog(LOG_DEBUG, "crypto: SSL_write got error %ld, ret %d", errval, retval);
 314                         if (retval == -1) {
 315                                 syslog(LOG_DEBUG, "crypto: errno is %d", errno);
 316                         }
 317                         endtls();
 318                         client_write(&buf[nbytes - nremain], nremain);
 319                         return;
 320                 }
 321                 nremain -= retval;
 322         }
 323 }
 324
 325
 326 // read data from the encrypted layer.
 327 int client_read_sslbuffer(StrBuf *buf, int timeout) {
 328         char sbuf[16384];       // OpenSSL communicates in 16k blocks, so let's speak its native tongue.
 329         int rlen;
 330         char junk[1];
 331         SSL *pssl = CC->ssl;
 332
 333         if (pssl == NULL) return(-1);
 334
 335         while (1) {
 336                 if (SSL_want_read(pssl)) {
 337                         if ((SSL_write(pssl, junk, 0)) < 1) {
 338                                 syslog(LOG_DEBUG, "crypto: SSL_write in client_read");
 339                         }
 340                 }
 341                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 342                 if (rlen < 1) {
 343                         long errval;
 344
 345                         errval = SSL_get_error(pssl, rlen);
 346                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 347                                 sleep(1);
 348                                 continue;
 349                         }
 350                         syslog(LOG_DEBUG, "crypto: SSL_read got error %ld", errval);
 351                         endtls();
 352                         return (-1);
 353                 }
 354                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 355                 return rlen;
 356         }
 357         return (0);
 358 }
 359
 360
 361 int client_readline_sslbuffer(StrBuf *Line, StrBuf *IOBuf, const char **Pos, int timeout) {
 362         const char *pos = NULL;
 363         const char *pLF;
 364         int len, rlen;
 365         int nSuccessLess = 0;
 366         const char *pch = NULL;
 367
 368         if ((Line == NULL) || (Pos == NULL) || (IOBuf == NULL)) {
 369                 if (Pos != NULL) {
 370                         *Pos = NULL;
 371                 }
 372                 return -1;
 373         }
 374
 375         pos = *Pos;
 376         if ((StrLength(IOBuf) > 0) && (pos != NULL) && (pos < ChrPtr(IOBuf) + StrLength(IOBuf))) {
 377                 pch = pos;
 378                 pch = strchr(pch, '\n');
 379
 380                 if (pch == NULL) {
 381                         StrBufAppendBufPlain(Line, pos, StrLength(IOBuf) - (pos - ChrPtr(IOBuf)), 0);
 382                         FlushStrBuf(IOBuf);
 383                         *Pos = NULL;
 384                 }
 385                 else {
 386                         int n = 0;
 387                         if ((pch > ChrPtr(IOBuf)) && (*(pch - 1) == '\r')) {
 388                                 n = 1;
 389                         }
 390                         StrBufAppendBufPlain(Line, pos, (pch - pos - n), 0);
 391
 392                         if (StrLength(IOBuf) <= (pch - ChrPtr(IOBuf) + 1)) {
 393                                 FlushStrBuf(IOBuf);
 394                                 *Pos = NULL;
 395                         }
 396                         else {
 397                                 *Pos = pch + 1;
 398                         }
 399                         return StrLength(Line);
 400                 }
 401         }
 402
 403         pLF = NULL;
 404         while ((nSuccessLess < timeout) && (pLF == NULL) && (CC->ssl != NULL)) {
 405
 406                 rlen = client_read_sslbuffer(IOBuf, timeout);
 407                 if (rlen < 1) {
 408                         return -1;
 409                 }
 410                 else if (rlen > 0) {
 411                         pLF = strchr(ChrPtr(IOBuf), '\n');
 412                 }
 413         }
 414         *Pos = NULL;
 415         if (pLF != NULL) {
 416                 pos = ChrPtr(IOBuf);
 417                 len = pLF - pos;
 418                 if (len > 0 && (*(pLF - 1) == '\r') )
 419                         len --;
 420                 StrBufAppendBufPlain(Line, pos, len, 0);
 421                 if (pLF + 1 >= ChrPtr(IOBuf) + StrLength(IOBuf)) {
 422                         FlushStrBuf(IOBuf);
 423                 }
 424                 else  {
 425                         *Pos = pLF + 1;
 426                 }
 427                 return StrLength(Line);
 428         }
 429         return -1;
 430 }
 431
 432
 433 int client_read_sslblob(StrBuf *Target, long bytes, int timeout) {
 434         long baselen;
 435         long RemainRead;
 436         int retval = 0;
 437
 438         baselen = StrLength(Target);
 439
 440         if (StrLength(CC->RecvBuf.Buf) > 0) {
 441                 long RemainLen;
 442                 long TotalLen;
 443                 const char *pchs;
 444
 445                 if (CC->RecvBuf.ReadWritePointer == NULL) {
 446                         CC->RecvBuf.ReadWritePointer = ChrPtr(CC->RecvBuf.Buf);
 447                 }
 448                 pchs = ChrPtr(CC->RecvBuf.Buf);
 449                 TotalLen = StrLength(CC->RecvBuf.Buf);
 450                 RemainLen = TotalLen - (pchs - CC->RecvBuf.ReadWritePointer);
 451                 if (RemainLen > bytes) {
 452                         RemainLen = bytes;
 453                 }
 454                 if (RemainLen > 0) {
 455                         StrBufAppendBufPlain(Target, CC->RecvBuf.ReadWritePointer, RemainLen, 0);
 456                         CC->RecvBuf.ReadWritePointer += RemainLen;
 457                 }
 458                 if ((ChrPtr(CC->RecvBuf.Buf) + StrLength(CC->RecvBuf.Buf)) <= CC->RecvBuf.ReadWritePointer) {
 459                         CC->RecvBuf.ReadWritePointer = NULL;
 460                         FlushStrBuf(CC->RecvBuf.Buf);
 461                 }
 462         }
 463
 464         if (StrLength(Target) >= bytes + baselen) {
 465                 return 1;
 466         }
 467
 468         CC->RecvBuf.ReadWritePointer = NULL;
 469
 470         while ((StrLength(Target) < bytes + baselen) && (retval >= 0)) {
 471                 retval = client_read_sslbuffer(CC->RecvBuf.Buf, timeout);
 472                 if (retval >= 0) {
 473                         RemainRead = bytes - (StrLength (Target) - baselen);
 474                         if (RemainRead < StrLength(CC->RecvBuf.Buf)) {
 475                                 StrBufAppendBufPlain(
 476                                         Target,
 477                                         ChrPtr(CC->RecvBuf.Buf),
 478                                         RemainRead, 0);
 479                                 CC->RecvBuf.ReadWritePointer = ChrPtr(CC->RecvBuf.Buf) + RemainRead;
 480                                 break;
 481                         }
 482                         StrBufAppendBuf(Target, CC->RecvBuf.Buf, 0);
 483                         FlushStrBuf(CC->RecvBuf.Buf);
 484                 }
 485                 else {
 486                         FlushStrBuf(CC->RecvBuf.Buf);
 487                         return -1;
 488
 489                 }
 490         }
 491         return 1;
 492 }
 493
 494
 495 // CtdlStartTLS() starts TLS encryption for the current session.  It
 496 // must be supplied with pre-generated strings for responses of "ok," "no
 497 // support for TLS," and "error" so that we can use this in any protocol.
 498 void CtdlStartTLS(char *ok_response, char *nosup_response, char *error_response) {
 499         int retval, bits, alg_bits;
 500
 501         if (CC->redirect_ssl) {
 502                 syslog(LOG_ERR, "crypto: attempt to begin SSL on an already encrypted connection");
 503                 if (error_response != NULL) {
 504                         cprintf("%s", error_response);
 505                 }
 506                 return;
 507         }
 508
 509         if (!ssl_ctx) {
 510                 syslog(LOG_ERR, "crypto: SSL failed: context has not been initialized");
 511                 if (nosup_response != NULL) {
 512                         cprintf("%s", nosup_response);
 513                 }
 514                 return;
 515         }
 516
 517         update_key_and_cert_if_needed();                // did someone update the key or cert?  if so, re-bind them
 518
 519         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 520                 syslog(LOG_ERR, "crypto: SSL_new failed: %s", ERR_reason_error_string(ERR_get_error()));
 521                 if (error_response != NULL) {
 522                         cprintf("%s", error_response);
 523                 }
 524                 return;
 525         }
 526         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 527                 syslog(LOG_ERR, "crypto: SSL_set_fd failed: %s", ERR_reason_error_string(ERR_get_error()));
 528                 SSL_free(CC->ssl);
 529                 CC->ssl = NULL;
 530                 if (error_response != NULL) {
 531                         cprintf("%s", error_response);
 532                 }
 533                 return;
 534         }
 535         if (ok_response != NULL) {
 536                 cprintf("%s", ok_response);
 537         }
 538         retval = SSL_accept(CC->ssl);
 539         if (retval < 1) {
 540                 // Can't notify the client of an error here; they will
 541                 // discover the problem at the SSL layer and should
 542                 // revert to unencrypted communications.
 543                 long errval;
 544                 char error_string[128];
 545
 546                 errval = SSL_get_error(CC->ssl, retval);
 547                 syslog(LOG_ERR, "crypto: SSL_accept failed: retval=%d, errval=%ld, err=%s",
 548                         retval,
 549                         errval,
 550                         ERR_error_string(errval, error_string)
 551                 );
 552                 SSL_free(CC->ssl);
 553                 CC->ssl = NULL;
 554                 return;
 555         }
 556         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 557         syslog(LOG_INFO, "crypto: 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 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 = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 591         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 592                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 593                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 594                 alg_bits, bits);
 595 }
 596
 597
 598 // endtls() shuts down the TLS connection
 599 void endtls(void) {
 600         if (!CC->ssl) {
 601                 CC->redirect_ssl = 0;
 602                 return;
 603         }
 604
 605         syslog(LOG_INFO, "crypto: ending TLS on this session");
 606         SSL_shutdown(CC->ssl);
 607         SSL_free(CC->ssl);
 608         CC->ssl = NULL;
 609         CC->redirect_ssl = 0;
 610 }
 611
 612 #endif  // HAVE_OPENSSL