net.c

   1 /*
   2  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
   3  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to The DragonFly Project
   6  * by Matthias Schmidt <matthias@dragonflybsd.org>, University of Marburg,
   7  * Germany.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  *
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in
  17  *    the documentation and/or other materials provided with the
  18  *    distribution.
  19  * 3. Neither the name of The DragonFly Project nor the names of its
  20  *    contributors may be used to endorse or promote products derived
  21  *    from this software without specific, prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  26  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  27  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  29  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  30  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  31  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  32  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  33  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include "dfcompat.h"
  38
  39 #include <sys/param.h>
  40 #include <sys/queue.h>
  41 #include <sys/stat.h>
  42 #include <sys/types.h>
  43 #include <sys/socket.h>
  44 #include <netinet/in.h>
  45 #include <arpa/inet.h>
  46
  47 #include <openssl/ssl.h>
  48 #include <openssl/err.h>
  49
  50 #include <ctype.h>
  51 #include <err.h>
  52 #include <errno.h>
  53 #include <netdb.h>
  54 #include <setjmp.h>
  55 #include <signal.h>
  56 #include <syslog.h>
  57 #include <unistd.h>
  58
  59 #include "dma.h"
  60
  61 char neterr[ERRMSG_SIZE];
  62
  63 char *
  64 ssl_errstr(void)
  65 {
  66         long oerr, nerr;
  67
  68         oerr = 0;
  69         while ((nerr = ERR_get_error()) != 0)
  70                 oerr = nerr;
  71
  72         return (ERR_error_string(oerr, NULL));
  73 }
  74
  75 ssize_t
  76 send_remote_command(int fd, const char* fmt, ...)
  77 {
  78         va_list va;
  79         char cmd[4096];
  80         size_t len, pos;
  81         int s;
  82         ssize_t n;
  83
  84         va_start(va, fmt);
  85         s = vsnprintf(cmd, sizeof(cmd) - 2, fmt, va);
  86         va_end(va);
  87         if (s == sizeof(cmd) - 2 || s < 0) {
  88                 strcpy(neterr, "Internal error: oversized command string");
  89                 return (-1);
  90         }
  91
  92         /* We *know* there are at least two more bytes available */
  93         strcat(cmd, "\r\n");
  94         len = strlen(cmd);
  95
  96         if (((config.features & SECURETRANS) != 0) &&
  97             ((config.features & NOSSL) == 0)) {
  98                 while ((s = SSL_write(config.ssl, (const char*)cmd, len)) <= 0) {
  99                         s = SSL_get_error(config.ssl, s);
 100                         if (s != SSL_ERROR_WANT_READ &&
 101                             s != SSL_ERROR_WANT_WRITE) {
 102                                 strncpy(neterr, ssl_errstr(), sizeof(neterr));
 103                                 return (-1);
 104                         }
 105                 }
 106         }
 107         else {
 108                 pos = 0;
 109                 while (pos < len) {
 110                         n = write(fd, cmd + pos, len - pos);
 111                         if (n < 0)
 112                                 return (-1);
 113                         pos += n;
 114                 }
 115         }
 116
 117         return (len);
 118 }
 119
 120 int
 121 read_remote(int fd, int extbufsize, char *extbuf)
 122 {
 123         ssize_t rlen = 0;
 124         size_t pos, len, copysize;
 125         char buff[BUF_SIZE];
 126         int done = 0, status = 0, status_running = 0, extbufpos = 0;
 127         enum { parse_status, parse_spacedash, parse_rest } parsestate;
 128
 129         if (do_timeout(CON_TIMEOUT, 1) != 0) {
 130                 snprintf(neterr, sizeof(neterr), "Timeout reached");
 131                 return (-1);
 132         }
 133
 134         /*
 135          * Remote reading code from femail.c written by Henning Brauer of
 136          * OpenBSD and released under a BSD style license.
 137          */
 138         len = 0;
 139         pos = 0;
 140         parsestate = parse_status;
 141         neterr[0] = 0;
 142         while (!(done && parsestate == parse_status)) {
 143                 rlen = 0;
 144                 if (pos == 0 ||
 145                     (pos > 0 && memchr(buff + pos, '\n', len - pos) == NULL)) {
 146                         memmove(buff, buff + pos, len - pos);
 147                         len -= pos;
 148                         pos = 0;
 149                         if (((config.features & SECURETRANS) != 0) &&
 150                             (config.features & NOSSL) == 0) {
 151                                 if ((rlen = SSL_read(config.ssl, buff + len, sizeof(buff) - len)) == -1) {
 152                                         strncpy(neterr, ssl_errstr(), sizeof(neterr));
 153                                         goto error;
 154                                 }
 155                         } else {
 156                                 if ((rlen = read(fd, buff + len, sizeof(buff) - len)) == -1) {
 157                                         strncpy(neterr, strerror(errno), sizeof(neterr));
 158                                         goto error;
 159                                 }
 160                         }
 161                         len += rlen;
 162
 163                         copysize = sizeof(neterr) - strlen(neterr) - 1;
 164                         if (copysize > len)
 165                                 copysize = len;
 166                         strncat(neterr, buff, copysize);
 167                 }
 168                 /*
 169                  * If there is an external buffer with a size bigger than zero
 170                  * and as long as there is space in the external buffer and
 171                  * there are new characters read from the mailserver
 172                  * copy them to the external buffer
 173                  */
 174                 if (extbufpos <= (extbufsize - 1) && rlen > 0 && extbufsize > 0 && extbuf != NULL) {
 175                         /* do not write over the bounds of the buffer */
 176                         if(extbufpos + rlen > (extbufsize - 1)) {
 177                                 rlen = extbufsize - extbufpos;
 178                         }
 179                         memcpy(extbuf + extbufpos, buff + len - rlen, rlen);
 180                         extbufpos += rlen;
 181                 }
 182
 183                 if (pos == len)
 184                         continue;
 185
 186                 switch (parsestate) {
 187                 case parse_status:
 188                         for (; pos < len; pos++) {
 189                                 if (isdigit(buff[pos])) {
 190                                         status_running = status_running * 10 + (buff[pos] - '0');
 191                                 } else {
 192                                         status = status_running;
 193                                         status_running = 0;
 194                                         parsestate = parse_spacedash;
 195                                         break;
 196                                 }
 197                         }
 198                         continue;
 199
 200                 case parse_spacedash:
 201                         switch (buff[pos]) {
 202                         case ' ':
 203                                 done = 1;
 204                                 break;
 205
 206                         case '-':
 207                                 /* ignore */
 208                                 /* XXX read capabilities */
 209                                 break;
 210
 211                         default:
 212                                 strcpy(neterr, "invalid syntax in reply from server");
 213                                 goto error;
 214                         }
 215
 216                         pos++;
 217                         parsestate = parse_rest;
 218                         continue;
 219
 220                 case parse_rest:
 221                         /* skip up to \n */
 222                         for (; pos < len; pos++) {
 223                                 if (buff[pos] == '\n') {
 224                                         pos++;
 225                                         parsestate = parse_status;
 226                                         break;
 227                                 }
 228                         }
 229                 }
 230
 231         }
 232
 233         do_timeout(0, 0);
 234
 235         /* chop off trailing newlines */
 236         while (neterr[0] != 0 && strchr("\r\n", neterr[strlen(neterr) - 1]) != 0)
 237                 neterr[strlen(neterr) - 1] = 0;
 238
 239         return (status/100);
 240
 241 error:
 242         do_timeout(0, 0);
 243         return (-1);
 244 }
 245
 246 /*
 247  * Handle SMTP authentication
 248  */
 249 static int
 250 smtp_login(int fd, char *login, char* password, const struct smtp_features* features)
 251 {
 252         char *temp;
 253         int len, res = 0;
 254
 255         // CRAM-MD5
 256         if (features->auth.cram_md5) {
 257                 res = smtp_auth_md5(fd, login, password);
 258                 if (res == 0) {
 259                         return (0);
 260                 } else if (res == -2) {
 261                 /*
 262                  * If the return code is -2, then then the login attempt failed,
 263                  * do not try other login mechanisms
 264                  */
 265                         return (1);
 266                 }
 267         }
 268
 269         // LOGIN
 270         if (features->auth.login) {
 271                 if ((config.features & INSECURE) != 0 ||
 272                     (config.features & SECURETRANS) != 0) {
 273                         /* Send AUTH command according to RFC 2554 */
 274                         send_remote_command(fd, "AUTH LOGIN");
 275                         if (read_remote(fd, 0, NULL) != 3) {
 276                                 syslog(LOG_NOTICE, "remote delivery deferred:"
 277                                                 " AUTH login not available: %s",
 278                                                 neterr);
 279                                 return (1);
 280                         }
 281
 282                         len = base64_encode(login, strlen(login), &temp);
 283                         if (len < 0) {
 284 encerr:
 285                                 syslog(LOG_ERR, "can not encode auth reply: %m");
 286                                 return (1);
 287                         }
 288
 289                         send_remote_command(fd, "%s", temp);
 290                         free(temp);
 291                         res = read_remote(fd, 0, NULL);
 292                         if (res != 3) {
 293                                 syslog(LOG_NOTICE, "remote delivery %s: AUTH login failed: %s",
 294                                        res == 5 ? "failed" : "deferred", neterr);
 295                                 return (res == 5 ? -1 : 1);
 296                         }
 297
 298                         len = base64_encode(password, strlen(password), &temp);
 299                         if (len < 0)
 300                                 goto encerr;
 301
 302                         send_remote_command(fd, "%s", temp);
 303                         free(temp);
 304                         res = read_remote(fd, 0, NULL);
 305                         if (res != 2) {
 306                                 syslog(LOG_NOTICE, "remote delivery %s: Authentication failed: %s",
 307                                                 res == 5 ? "failed" : "deferred", neterr);
 308                                 return (res == 5 ? -1 : 1);
 309                         }
 310                 } else {
 311                         syslog(LOG_WARNING, "non-encrypted SMTP login is disabled in config, so skipping it. ");
 312                         return (1);
 313                 }
 314         }
 315
 316         return (0);
 317 }
 318
 319 static int
 320 open_connection(struct mx_hostentry *h)
 321 {
 322         int fd;
 323
 324         syslog(LOG_INFO, "trying remote delivery to %s [%s] pref %d",
 325                h->host, h->addr, h->pref);
 326
 327         fd = socket(h->ai.ai_family, h->ai.ai_socktype, h->ai.ai_protocol);
 328         if (fd < 0) {
 329                 syslog(LOG_INFO, "socket for %s [%s] failed: %m",
 330                        h->host, h->addr);
 331                 return (-1);
 332         }
 333
 334         if (connect(fd, (struct sockaddr *)&h->sa, h->ai.ai_addrlen) < 0) {
 335                 syslog(LOG_INFO, "connect to %s [%s] failed: %m",
 336                        h->host, h->addr);
 337                 close(fd);
 338                 return (-1);
 339         }
 340
 341         return (fd);
 342 }
 343
 344 static void
 345 close_connection(int fd)
 346 {
 347         if (config.ssl != NULL) {
 348                 if (((config.features & SECURETRANS) != 0) &&
 349                     ((config.features & NOSSL) == 0))
 350                         SSL_shutdown(config.ssl);
 351                 SSL_free(config.ssl);
 352         }
 353
 354         close(fd);
 355 }
 356
 357 static void parse_auth_line(char* line, struct smtp_auth_mechanisms* auth) {
 358         // Skip the auth prefix
 359         line += strlen("AUTH ");
 360
 361         char* method = strtok(line, " ");
 362         while (method) {
 363                 if (strcmp(method, "CRAM-MD5") == 0)
 364                         auth->cram_md5 = 1;
 365
 366                 else if (strcmp(method, "LOGIN") == 0)
 367                         auth->login = 1;
 368
 369                 method = strtok(NULL, " ");
 370         }
 371 }
 372
 373 int perform_server_greeting(int fd, struct smtp_features* features) {
 374         /*
 375                 Send EHLO
 376                 XXX allow HELO fallback
 377         */
 378         send_remote_command(fd, "EHLO %s", hostname());
 379
 380         char buffer[EHLO_RESPONSE_SIZE];
 381         memset(buffer, 0, sizeof(buffer));
 382
 383         int res = read_remote(fd, sizeof(buffer) - 1, buffer);
 384
 385         // Got an unexpected response
 386         if (res != 2)
 387                 return -1;
 388
 389         // Reset all features
 390         memset(features, 0, sizeof(*features));
 391
 392         // Run through the buffer line by line
 393         char linebuffer[EHLO_RESPONSE_SIZE];
 394         char* p = buffer;
 395
 396         while (*p) {
 397                 char* line = linebuffer;
 398                 while (*p && *p != '\n') {
 399                         *line++ = *p++;
 400                 }
 401
 402                 // p should never point to NULL after the loop
 403                 // above unless we reached the end of the buffer.
 404                 // In that case we will raise an error.
 405                 if (!*p) {
 406                         return -1;
 407                 }
 408
 409                 // Otherwise p points to the newline character which
 410                 // we will skip.
 411                 p++;
 412
 413                 // Terminte the string (and remove the carriage-return character)
 414                 *--line = '\0';
 415                 line = linebuffer;
 416
 417                 // End main loop for empty lines
 418                 if (*line == '\0')
 419                         break;
 420
 421                 // Process the line
 422                 // - Must start with 250, followed by dash or space
 423                 // - We won't check for the correct usage of space and dash because
 424                 //    that is already done in read_remote().
 425                 if ((strncmp(line, "250-", 4) != 0) && (strncmp(line, "250 ", 4) != 0)) {
 426                         syslog(LOG_ERR, "Invalid line: %s\n", line);
 427                         return -1;
 428                 }
 429
 430                 // Skip the prefix
 431                 line += 4;
 432
 433                 // Check for STARTTLS
 434                 if (strcmp(line, "STARTTLS") == 0)
 435                         features->starttls = 1;
 436
 437                 // Parse authentication mechanisms
 438                 else if (strncmp(line, "AUTH ", 5) == 0)
 439                         parse_auth_line(line, &features->auth);
 440         }
 441
 442         syslog(LOG_DEBUG, "Server greeting successfully completed");
 443
 444         // STARTTLS
 445         if (features->starttls)
 446                 syslog(LOG_DEBUG, "  Server supports STARTTLS");
 447         else
 448                 syslog(LOG_DEBUG, "  Server does not support STARTTLS");
 449
 450         // Authentication
 451         if (features->auth.cram_md5) {
 452                 syslog(LOG_DEBUG, "  Server supports CRAM-MD5 authentication");
 453         }
 454         if (features->auth.login) {
 455                 syslog(LOG_DEBUG, "  Server supports LOGIN authentication");
 456         }
 457
 458         return 0;
 459 }
 460
 461 static int
 462 deliver_to_host(struct qitem *it, struct mx_hostentry *host)
 463 {
 464         struct authuser *a;
 465         struct smtp_features features;
 466         char line[1000];
 467         size_t linelen;
 468         int fd, error = 0, do_auth = 0, res = 0;
 469
 470         if (fseek(it->mailf, 0, SEEK_SET) != 0) {
 471                 snprintf(errmsg, sizeof(errmsg), "can not seek: %s", strerror(errno));
 472                 return (-1);
 473         }
 474
 475         fd = open_connection(host);
 476         if (fd < 0)
 477                 return (1);
 478
 479 #define READ_REMOTE_CHECK(c, exp)       \
 480         res = read_remote(fd, 0, NULL); \
 481         if (res == 5) { \
 482                 syslog(LOG_ERR, "remote delivery to %s [%s] failed after %s: %s", \
 483                        host->host, host->addr, c, neterr); \
 484                 snprintf(errmsg, sizeof(errmsg), "%s [%s] did not like our %s:\n%s", \
 485                          host->host, host->addr, c, neterr); \
 486                 error = -1; \
 487                 goto out; \
 488         } else if (res != exp) { \
 489                 syslog(LOG_NOTICE, "remote delivery deferred: %s [%s] failed after %s: %s", \
 490                        host->host, host->addr, c, neterr); \
 491                 error = 1; \
 492                 goto out; \
 493         }
 494
 495         /* Check first reply from remote host */
 496         if ((config.features & SECURETRANS) == 0 ||
 497             (config.features & STARTTLS) != 0) {
 498                 config.features |= NOSSL;
 499                 READ_REMOTE_CHECK("connect", 2);
 500
 501                 config.features &= ~NOSSL;
 502         }
 503
 504         if ((config.features & SECURETRANS) != 0) {
 505                 error = smtp_init_crypto(fd, config.features, &features);
 506                 if (error == 0)
 507                         syslog(LOG_DEBUG, "SSL initialization successful");
 508                 else
 509                         goto out;
 510
 511                 if ((config.features & STARTTLS) == 0)
 512                         READ_REMOTE_CHECK("connect", 2);
 513         }
 514
 515         // Say EHLO
 516         if (perform_server_greeting(fd, &features) != 0) {
 517                 syslog(LOG_ERR, "Could not perform server greeting at %s [%s]: %s",
 518                         host->host, host->addr, neterr);
 519                 return -1;
 520         }
 521
 522         /*
 523          * Use SMTP authentication if the user defined an entry for the remote
 524          * or smarthost
 525          */
 526         SLIST_FOREACH(a, &authusers, next) {
 527                 if (strcmp(a->host, host->host) == 0) {
 528                         do_auth = 1;
 529                         break;
 530                 }
 531         }
 532
 533         if (do_auth == 1) {
 534                 /*
 535                  * Check if the user wants plain text login without using
 536                  * encryption.
 537                  */
 538                 syslog(LOG_INFO, "using SMTP authentication for user %s", a->login);
 539                 error = smtp_login(fd, a->login, a->password, &features);
 540                 if (error < 0) {
 541                         syslog(LOG_ERR, "remote delivery failed:"
 542                                         " SMTP login failed: %m");
 543                         snprintf(errmsg, sizeof(errmsg), "SMTP login to %s failed", host->host);
 544                         error = -1;
 545                         goto out;
 546                 }
 547                 /* SMTP login is not available, so try without */
 548                 else if (error > 0) {
 549                         syslog(LOG_WARNING, "SMTP login not available. Trying without.");
 550                 }
 551         }
 552
 553         /* XXX send ESMTP ENVID, RET (FULL/HDRS) and 8BITMIME */
 554         send_remote_command(fd, "MAIL FROM:<%s>", it->sender);
 555         READ_REMOTE_CHECK("MAIL FROM", 2);
 556
 557         /* XXX send ESMTP ORCPT */
 558         send_remote_command(fd, "RCPT TO:<%s>", it->addr);
 559         READ_REMOTE_CHECK("RCPT TO", 2);
 560
 561         send_remote_command(fd, "DATA");
 562         READ_REMOTE_CHECK("DATA", 3);
 563
 564         error = 0;
 565         while (!feof(it->mailf)) {
 566                 if (fgets(line, sizeof(line), it->mailf) == NULL)
 567                         break;
 568                 linelen = strlen(line);
 569                 if (linelen == 0 || line[linelen - 1] != '\n') {
 570                         syslog(LOG_CRIT, "remote delivery failed: corrupted queue file");
 571                         snprintf(errmsg, sizeof(errmsg), "corrupted queue file");
 572                         error = -1;
 573                         goto out;
 574                 }
 575
 576                 /* Remove trailing \n's and escape leading dots */
 577                 trim_line(line);
 578
 579                 /*
 580                  * If the first character is a dot, we escape it so the line
 581                  * length increases
 582                 */
 583                 if (line[0] == '.')
 584                         linelen++;
 585
 586                 if (send_remote_command(fd, "%s", line) != (ssize_t)linelen+1) {
 587                         syslog(LOG_NOTICE, "remote delivery deferred: write error");
 588                         error = 1;
 589                         goto out;
 590                 }
 591         }
 592
 593         send_remote_command(fd, ".");
 594         READ_REMOTE_CHECK("final DATA", 2);
 595
 596         send_remote_command(fd, "QUIT");
 597         if (read_remote(fd, 0, NULL) != 2)
 598                 syslog(LOG_INFO, "remote delivery succeeded but QUIT failed: %s", neterr);
 599 out:
 600
 601         close_connection(fd);
 602         return (error);
 603 }
 604
 605 int
 606 deliver_remote(struct qitem *it)
 607 {
 608         struct mx_hostentry *hosts, *h;
 609         const char *host;
 610         int port;
 611         int error = 1, smarthost = 0;
 612
 613         port = SMTP_PORT;
 614
 615         /* Smarthost support? */
 616         if (config.smarthost != NULL) {
 617                 host = config.smarthost;
 618                 port = config.port;
 619                 syslog(LOG_INFO, "using smarthost (%s:%i)", host, port);
 620                 smarthost = 1;
 621         } else {
 622                 host = strrchr(it->addr, '@');
 623                 /* Should not happen */
 624                 if (host == NULL) {
 625                         snprintf(errmsg, sizeof(errmsg), "Internal error: badly formed address %s",
 626                                  it->addr);
 627                         return(-1);
 628                 } else {
 629                         /* Step over the @ */
 630                         host++;
 631                 }
 632         }
 633
 634         error = dns_get_mx_list(host, port, &hosts, smarthost);
 635         if (error) {
 636                 snprintf(errmsg, sizeof(errmsg), "DNS lookup failure: host %s not found", host);
 637                 syslog(LOG_NOTICE, "remote delivery %s: DNS lookup failure: host %s not found",
 638                        error < 0 ? "failed" : "deferred",
 639                        host);
 640                 return (error);
 641         }
 642
 643         for (h = hosts; *h->host != 0; h++) {
 644                 switch (deliver_to_host(it, h)) {
 645                 case 0:
 646                         /* success */
 647                         error = 0;
 648                         goto out;
 649                 case 1:
 650                         /* temp failure */
 651                         error = 1;
 652                         break;
 653                 default:
 654                         /* perm failure */
 655                         error = -1;
 656                         goto out;
 657                 }
 658         }
 659 out:
 660         free(hosts);
 661
 662         return (error);
 663 }