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)
 251 {
 252         char *temp;
 253         int len, res = 0;
 254
 255         res = smtp_auth_md5(fd, login, password);
 256         if (res == 0) {
 257                 return (0);
 258         } else if (res == -2) {
 259         /*
 260          * If the return code is -2, then then the login attempt failed,
 261          * do not try other login mechanisms
 262          */
 263                 return (1);
 264         }
 265
 266         if ((config.features & INSECURE) != 0 ||
 267             (config.features & SECURETRANS) != 0) {
 268                 /* Send AUTH command according to RFC 2554 */
 269                 send_remote_command(fd, "AUTH LOGIN");
 270                 if (read_remote(fd, 0, NULL) != 3) {
 271                         syslog(LOG_NOTICE, "remote delivery deferred:"
 272                                         " AUTH login not available: %s",
 273                                         neterr);
 274                         return (1);
 275                 }
 276
 277                 len = base64_encode(login, strlen(login), &temp);
 278                 if (len < 0) {
 279 encerr:
 280                         syslog(LOG_ERR, "can not encode auth reply: %m");
 281                         return (1);
 282                 }
 283
 284                 send_remote_command(fd, "%s", temp);
 285                 free(temp);
 286                 res = read_remote(fd, 0, NULL);
 287                 if (res != 3) {
 288                         syslog(LOG_NOTICE, "remote delivery %s: AUTH login failed: %s",
 289                                res == 5 ? "failed" : "deferred", neterr);
 290                         return (res == 5 ? -1 : 1);
 291                 }
 292
 293                 len = base64_encode(password, strlen(password), &temp);
 294                 if (len < 0)
 295                         goto encerr;
 296
 297                 send_remote_command(fd, "%s", temp);
 298                 free(temp);
 299                 res = read_remote(fd, 0, NULL);
 300                 if (res != 2) {
 301                         syslog(LOG_NOTICE, "remote delivery %s: Authentication failed: %s",
 302                                         res == 5 ? "failed" : "deferred", neterr);
 303                         return (res == 5 ? -1 : 1);
 304                 }
 305         } else {
 306                 syslog(LOG_WARNING, "non-encrypted SMTP login is disabled in config, so skipping it. ");
 307                 return (1);
 308         }
 309
 310         return (0);
 311 }
 312
 313 static int
 314 open_connection(struct mx_hostentry *h)
 315 {
 316         int fd;
 317
 318         syslog(LOG_INFO, "trying remote delivery to %s [%s] pref %d",
 319                h->host, h->addr, h->pref);
 320
 321         fd = socket(h->ai.ai_family, h->ai.ai_socktype, h->ai.ai_protocol);
 322         if (fd < 0) {
 323                 syslog(LOG_INFO, "socket for %s [%s] failed: %m",
 324                        h->host, h->addr);
 325                 return (-1);
 326         }
 327
 328         if (connect(fd, (struct sockaddr *)&h->sa, h->ai.ai_addrlen) < 0) {
 329                 syslog(LOG_INFO, "connect to %s [%s] failed: %m",
 330                        h->host, h->addr);
 331                 close(fd);
 332                 return (-1);
 333         }
 334
 335         return (fd);
 336 }
 337
 338 static void
 339 close_connection(int fd)
 340 {
 341         if (config.ssl != NULL) {
 342                 if (((config.features & SECURETRANS) != 0) &&
 343                     ((config.features & NOSSL) == 0))
 344                         SSL_shutdown(config.ssl);
 345                 SSL_free(config.ssl);
 346         }
 347
 348         close(fd);
 349 }
 350
 351 static int
 352 deliver_to_host(struct qitem *it, struct mx_hostentry *host)
 353 {
 354         struct authuser *a;
 355         char line[1000];
 356         size_t linelen;
 357         int fd, error = 0, do_auth = 0, res = 0;
 358
 359         if (fseek(it->mailf, 0, SEEK_SET) != 0) {
 360                 snprintf(errmsg, sizeof(errmsg), "can not seek: %s", strerror(errno));
 361                 return (-1);
 362         }
 363
 364         fd = open_connection(host);
 365         if (fd < 0)
 366                 return (1);
 367
 368 #define READ_REMOTE_CHECK(c, exp)       \
 369         res = read_remote(fd, 0, NULL); \
 370         if (res == 5) { \
 371                 syslog(LOG_ERR, "remote delivery to %s [%s] failed after %s: %s", \
 372                        host->host, host->addr, c, neterr); \
 373                 snprintf(errmsg, sizeof(errmsg), "%s [%s] did not like our %s:\n%s", \
 374                          host->host, host->addr, c, neterr); \
 375                 error = -1; \
 376                 goto out; \
 377         } else if (res != exp) { \
 378                 syslog(LOG_NOTICE, "remote delivery deferred: %s [%s] failed after %s: %s", \
 379                        host->host, host->addr, c, neterr); \
 380                 error = 1; \
 381                 goto out; \
 382         }
 383
 384         /* Check first reply from remote host */
 385         if ((config.features & SECURETRANS) == 0 ||
 386             (config.features & STARTTLS) != 0) {
 387                 config.features |= NOSSL;
 388                 READ_REMOTE_CHECK("connect", 2);
 389
 390                 config.features &= ~NOSSL;
 391         }
 392
 393         if ((config.features & SECURETRANS) != 0) {
 394                 error = smtp_init_crypto(fd, config.features);
 395                 if (error == 0)
 396                         syslog(LOG_DEBUG, "SSL initialization successful");
 397                 else
 398                         goto out;
 399
 400                 if ((config.features & STARTTLS) == 0)
 401                         READ_REMOTE_CHECK("connect", 2);
 402         }
 403
 404         /* XXX allow HELO fallback */
 405         /* XXX record ESMTP keywords */
 406         send_remote_command(fd, "EHLO %s", hostname());
 407         READ_REMOTE_CHECK("EHLO", 2);
 408
 409         /*
 410          * Use SMTP authentication if the user defined an entry for the remote
 411          * or smarthost
 412          */
 413         SLIST_FOREACH(a, &authusers, next) {
 414                 if (strcmp(a->host, host->host) == 0) {
 415                         do_auth = 1;
 416                         break;
 417                 }
 418         }
 419
 420         if (do_auth == 1) {
 421                 /*
 422                  * Check if the user wants plain text login without using
 423                  * encryption.
 424                  */
 425                 syslog(LOG_INFO, "using SMTP authentication for user %s", a->login);
 426                 error = smtp_login(fd, a->login, a->password);
 427                 if (error < 0) {
 428                         syslog(LOG_ERR, "remote delivery failed:"
 429                                         " SMTP login failed: %m");
 430                         snprintf(errmsg, sizeof(errmsg), "SMTP login to %s failed", host->host);
 431                         error = -1;
 432                         goto out;
 433                 }
 434                 /* SMTP login is not available, so try without */
 435                 else if (error > 0) {
 436                         syslog(LOG_WARNING, "SMTP login not available. Trying without.");
 437                 }
 438         }
 439
 440         /* XXX send ESMTP ENVID, RET (FULL/HDRS) and 8BITMIME */
 441         send_remote_command(fd, "MAIL FROM:<%s>", it->sender);
 442         READ_REMOTE_CHECK("MAIL FROM", 2);
 443
 444         /* XXX send ESMTP ORCPT */
 445         send_remote_command(fd, "RCPT TO:<%s>", it->addr);
 446         READ_REMOTE_CHECK("RCPT TO", 2);
 447
 448         send_remote_command(fd, "DATA");
 449         READ_REMOTE_CHECK("DATA", 3);
 450
 451         error = 0;
 452         while (!feof(it->mailf)) {
 453                 if (fgets(line, sizeof(line), it->mailf) == NULL)
 454                         break;
 455                 linelen = strlen(line);
 456                 if (linelen == 0 || line[linelen - 1] != '\n') {
 457                         syslog(LOG_CRIT, "remote delivery failed: corrupted queue file");
 458                         snprintf(errmsg, sizeof(errmsg), "corrupted queue file");
 459                         error = -1;
 460                         goto out;
 461                 }
 462
 463                 /* Remove trailing \n's and escape leading dots */
 464                 trim_line(line);
 465
 466                 /*
 467                  * If the first character is a dot, we escape it so the line
 468                  * length increases
 469                 */
 470                 if (line[0] == '.')
 471                         linelen++;
 472
 473                 if (send_remote_command(fd, "%s", line) != (ssize_t)linelen+1) {
 474                         syslog(LOG_NOTICE, "remote delivery deferred: write error");
 475                         error = 1;
 476                         goto out;
 477                 }
 478         }
 479
 480         send_remote_command(fd, ".");
 481         READ_REMOTE_CHECK("final DATA", 2);
 482
 483         send_remote_command(fd, "QUIT");
 484         if (read_remote(fd, 0, NULL) != 2)
 485                 syslog(LOG_INFO, "remote delivery succeeded but QUIT failed: %s", neterr);
 486 out:
 487
 488         close_connection(fd);
 489         return (error);
 490 }
 491
 492 int
 493 deliver_remote(struct qitem *it)
 494 {
 495         struct mx_hostentry *hosts, *h;
 496         const char *host;
 497         int port;
 498         int error = 1, smarthost = 0;
 499
 500         port = SMTP_PORT;
 501
 502         /* Smarthost support? */
 503         if (config.smarthost != NULL) {
 504                 host = config.smarthost;
 505                 port = config.port;
 506                 syslog(LOG_INFO, "using smarthost (%s:%i)", host, port);
 507                 smarthost = 1;
 508         } else {
 509                 host = strrchr(it->addr, '@');
 510                 /* Should not happen */
 511                 if (host == NULL) {
 512                         snprintf(errmsg, sizeof(errmsg), "Internal error: badly formed address %s",
 513                                  it->addr);
 514                         return(-1);
 515                 } else {
 516                         /* Step over the @ */
 517                         host++;
 518                 }
 519         }
 520
 521         error = dns_get_mx_list(host, port, &hosts, smarthost);
 522         if (error) {
 523                 snprintf(errmsg, sizeof(errmsg), "DNS lookup failure: host %s not found", host);
 524                 syslog(LOG_NOTICE, "remote delivery %s: DNS lookup failure: host %s not found",
 525                        error < 0 ? "failed" : "deferred",
 526                        host);
 527                 return (error);
 528         }
 529
 530         for (h = hosts; *h->host != 0; h++) {
 531                 switch (deliver_to_host(it, h)) {
 532                 case 0:
 533                         /* success */
 534                         error = 0;
 535                         goto out;
 536                 case 1:
 537                         /* temp failure */
 538                         error = 1;
 539                         break;
 540                 default:
 541                         /* perm failure */
 542                         error = -1;
 543                         goto out;
 544                 }
 545         }
 546 out:
 547         free(hosts);
 548
 549         return (error);
 550 }