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 <strings.h>
57 #include <string.h>
58 #include <syslog.h>
59 #include <unistd.h>
60
61 #include "dma.h"
62
63 char neterr[ERRMSG_SIZE];
64
65 char *
ssl_errstr(void)66 ssl_errstr(void)
67 {
68 long oerr, nerr;
69
70 oerr = 0;
71 while ((nerr = ERR_get_error()) != 0)
72 oerr = nerr;
73
74 return (ERR_error_string(oerr, NULL));
75 }
76
77 ssize_t
send_remote_command(int fd,const char * fmt,...)78 send_remote_command(int fd, const char* fmt, ...)
79 {
80 va_list va;
81 char cmd[4096];
82 size_t len, pos;
83 int s;
84 ssize_t n;
85
86 va_start(va, fmt);
87 s = vsnprintf(cmd, sizeof(cmd) - 2, fmt, va);
88 va_end(va);
89 if (s == sizeof(cmd) - 2 || s < 0) {
90 strcpy(neterr, "Internal error: oversized command string");
91 return (-1);
92 }
93
94 /* We *know* there are at least two more bytes available */
95 strcat(cmd, "\r\n");
96 len = strlen(cmd);
97
98 pos = 0;
99 while (pos < len) {
100 if (((config.features & SECURETRANSFER) != 0) &&
101 ((config.features & NOSSL) == 0)) {
102 if ((n = SSL_write(config.ssl, (const char*)(cmd + pos), len - pos)) <= 0) {
103 s = SSL_get_error(config.ssl, n);
104 if (s == SSL_ERROR_ZERO_RETURN ||
105 s == SSL_ERROR_SYSCALL ||
106 s == SSL_ERROR_SSL) {
107 strlcpy(neterr, ssl_errstr(), sizeof(neterr));
108 return (-1);
109 }
110 n = 0;
111 }
112 } else {
113 n = write(fd, cmd + pos, len - pos);
114 if (n < 0) {
115 if ((errno != EAGAIN) && (errno != EINTR))
116 return (-1);
117 n = 0;
118 }
119 }
120 pos += n;
121 }
122
123 return (len);
124 }
125
126 int
read_remote(int fd,int extbufsize,char * extbuf)127 read_remote(int fd, int extbufsize, char *extbuf)
128 {
129 ssize_t rlen = 0;
130 size_t pos, len, copysize;
131 char buff[BUF_SIZE];
132 int done = 0, status = 0, status_running = 0, extbufpos = 0;
133 enum { parse_status, parse_spacedash, parse_rest } parsestate;
134
135 if (do_timeout(CON_TIMEOUT, 1) != 0) {
136 snprintf(neterr, sizeof(neterr), "Timeout reached");
137 return (-1);
138 }
139
140 /*
141 * Remote reading code from femail.c written by Henning Brauer of
142 * OpenBSD and released under a BSD style license.
143 */
144 len = 0;
145 pos = 0;
146 parsestate = parse_status;
147 neterr[0] = 0;
148 while (!(done && parsestate == parse_status)) {
149 rlen = 0;
150 if (pos == 0 ||
151 (pos > 0 && memchr(buff + pos, '\n', len - pos) == NULL)) {
152 memmove(buff, buff + pos, len - pos);
153 len -= pos;
154 pos = 0;
155 if (((config.features & SECURETRANSFER) != 0) &&
156 (config.features & NOSSL) == 0) {
157 if ((rlen = SSL_read(config.ssl, buff + len, sizeof(buff) - len)) <= 0) {
158 switch (SSL_get_error(config.ssl, rlen)) {
159 case SSL_ERROR_ZERO_RETURN:
160 case SSL_ERROR_SYSCALL:
161 case SSL_ERROR_SSL:
162 strlcpy(neterr, ssl_errstr(), sizeof(neterr));
163 goto error;
164 default:
165 /* in case of recoverable error, retry after short sleep */
166 usleep(10000);
167 continue;
168 }
169 }
170 } else {
171 if ((rlen = read(fd, buff + len, sizeof(buff) - len)) == -1) {
172 strlcpy(neterr, strerror(errno), sizeof(neterr));
173 goto error;
174 }
175 }
176 len += rlen;
177
178 copysize = sizeof(neterr) - strlen(neterr) - 1;
179 if (copysize > len)
180 copysize = len;
181 strncat(neterr, buff, copysize);
182 }
183 /*
184 * If there is an external buffer with a size bigger than zero
185 * and as long as there is space in the external buffer and
186 * there are new characters read from the mailserver
187 * copy them to the external buffer
188 */
189 if (extbufpos <= (extbufsize - 1) && rlen > 0 && extbufsize > 0 && extbuf != NULL) {
190 /* do not write over the bounds of the buffer */
191 if(extbufpos + rlen > (extbufsize - 1)) {
192 rlen = extbufsize - extbufpos;
193 }
194 memcpy(extbuf + extbufpos, buff + len - rlen, rlen);
195 extbufpos += rlen;
196 }
197
198 if (pos == len)
199 continue;
200
201 switch (parsestate) {
202 case parse_status:
203 for (; pos < len; pos++) {
204 if (isdigit(buff[pos])) {
205 status_running = status_running * 10 + (buff[pos] - '0');
206 } else {
207 status = status_running;
208 status_running = 0;
209 parsestate = parse_spacedash;
210 break;
211 }
212 }
213 continue;
214
215 case parse_spacedash:
216 switch (buff[pos]) {
217 case ' ':
218 done = 1;
219 break;
220
221 case '-':
222 /* ignore */
223 /* XXX read capabilities */
224 break;
225
226 default:
227 strcpy(neterr, "invalid syntax in reply from server");
228 goto error;
229 }
230
231 pos++;
232 parsestate = parse_rest;
233 continue;
234
235 case parse_rest:
236 /* skip up to \n */
237 for (; pos < len; pos++) {
238 if (buff[pos] == '\n') {
239 pos++;
240 parsestate = parse_status;
241 break;
242 }
243 }
244 }
245
246 }
247
248 do_timeout(0, 0);
249
250 /* chop off trailing newlines */
251 while (neterr[0] != 0 && strchr("\r\n", neterr[strlen(neterr) - 1]) != 0)
252 neterr[strlen(neterr) - 1] = 0;
253
254 return (status/100);
255
256 error:
257 do_timeout(0, 0);
258 return (-1);
259 }
260
261 /*
262 * Handle SMTP authentication
263 */
264 static int
smtp_login(int fd,char * login,char * password,const struct smtp_features * features)265 smtp_login(int fd, char *login, char* password, const struct smtp_features* features)
266 {
267 char *temp;
268 int len, res = 0;
269
270 // CRAM-MD5
271 if (features->auth.cram_md5) {
272 res = smtp_auth_md5(fd, login, password);
273 if (res == 0) {
274 return (0);
275 } else if (res == -2) {
276 /*
277 * If the return code is -2, then then the login attempt failed,
278 * do not try other login mechanisms
279 */
280 return (1);
281 }
282 }
283
284 // LOGIN
285 if (features->auth.login) {
286 if ((config.features & INSECURE) != 0 ||
287 (config.features & SECURETRANSFER) != 0) {
288 /* Send AUTH command according to RFC 2554 */
289 send_remote_command(fd, "AUTH LOGIN");
290 if (read_remote(fd, 0, NULL) != 3) {
291 syslog(LOG_NOTICE, "remote delivery deferred:"
292 " AUTH login not available: %s",
293 neterr);
294 return (1);
295 }
296
297 len = base64_encode(login, strlen(login), &temp);
298 if (len < 0) {
299 encerr:
300 syslog(LOG_ERR, "can not encode auth reply: %m");
301 return (1);
302 }
303
304 send_remote_command(fd, "%s", temp);
305 free(temp);
306 res = read_remote(fd, 0, NULL);
307 if (res != 3) {
308 syslog(LOG_NOTICE, "remote delivery %s: AUTH login failed: %s",
309 res == 5 ? "failed" : "deferred", neterr);
310 return (res == 5 ? -1 : 1);
311 }
312
313 len = base64_encode(password, strlen(password), &temp);
314 if (len < 0)
315 goto encerr;
316
317 send_remote_command(fd, "%s", temp);
318 free(temp);
319 res = read_remote(fd, 0, NULL);
320 if (res != 2) {
321 syslog(LOG_NOTICE, "remote delivery %s: Authentication failed: %s",
322 res == 5 ? "failed" : "deferred", neterr);
323 return (res == 5 ? -1 : 1);
324 }
325 } else {
326 syslog(LOG_WARNING, "non-encrypted SMTP login is disabled in config, so skipping it. ");
327 return (1);
328 }
329 }
330
331 return (0);
332 }
333
334 static int
open_connection(struct mx_hostentry * h)335 open_connection(struct mx_hostentry *h)
336 {
337 int fd;
338
339 syslog(LOG_INFO, "trying remote delivery to %s [%s] pref %d",
340 h->host, h->addr, h->pref);
341
342 fd = socket(h->ai.ai_family, h->ai.ai_socktype, h->ai.ai_protocol);
343 if (fd < 0) {
344 syslog(LOG_INFO, "socket for %s [%s] failed: %m",
345 h->host, h->addr);
346 return (-1);
347 }
348
349 if (connect(fd, (struct sockaddr *)&h->sa, h->ai.ai_addrlen) < 0) {
350 syslog(LOG_INFO, "connect to %s [%s] failed: %m",
351 h->host, h->addr);
352 close(fd);
353 return (-1);
354 }
355
356 return (fd);
357 }
358
359 static void
close_connection(int fd)360 close_connection(int fd)
361 {
362 if (config.ssl != NULL) {
363 if (((config.features & SECURETRANSFER) != 0) &&
364 ((config.features & NOSSL) == 0))
365 SSL_shutdown(config.ssl);
366 SSL_free(config.ssl);
367 }
368
369 close(fd);
370 }
371
parse_auth_line(char * line,struct smtp_auth_mechanisms * auth)372 static void parse_auth_line(char* line, struct smtp_auth_mechanisms* auth) {
373 // Skip the auth prefix
374 line += strlen("AUTH ");
375
376 char* method = strtok(line, " ");
377 while (method) {
378 if (strcmp(method, "CRAM-MD5") == 0)
379 auth->cram_md5 = 1;
380
381 else if (strcmp(method, "LOGIN") == 0)
382 auth->login = 1;
383
384 method = strtok(NULL, " ");
385 }
386 }
387
perform_server_greeting(int fd,struct smtp_features * features)388 int perform_server_greeting(int fd, struct smtp_features* features) {
389 /*
390 Send EHLO
391 XXX allow HELO fallback
392 */
393 send_remote_command(fd, "EHLO %s", hostname());
394
395 char buffer[EHLO_RESPONSE_SIZE];
396 memset(buffer, 0, sizeof(buffer));
397
398 int res = read_remote(fd, sizeof(buffer) - 1, buffer);
399
400 // Got an unexpected response
401 if (res != 2)
402 return -1;
403
404 // Reset all features
405 memset(features, 0, sizeof(*features));
406
407 // Run through the buffer line by line
408 char linebuffer[EHLO_RESPONSE_SIZE];
409 char* p = buffer;
410
411 while (*p) {
412 char* line = linebuffer;
413 while (*p && *p != '\n') {
414 *line++ = *p++;
415 }
416
417 // p should never point to NULL after the loop
418 // above unless we reached the end of the buffer.
419 // In that case we will raise an error.
420 if (!*p) {
421 return -1;
422 }
423
424 // Otherwise p points to the newline character which
425 // we will skip.
426 p++;
427
428 // Terminte the string (and remove the carriage-return character)
429 *--line = '\0';
430 line = linebuffer;
431
432 // End main loop for empty lines
433 if (*line == '\0')
434 break;
435
436 // Process the line
437 // - Must start with 250, followed by dash or space
438 // - We won't check for the correct usage of space and dash because
439 // that is already done in read_remote().
440 if ((strncmp(line, "250-", 4) != 0) && (strncmp(line, "250 ", 4) != 0)) {
441 syslog(LOG_ERR, "Invalid line: %s\n", line);
442 return -1;
443 }
444
445 // Skip the prefix
446 line += 4;
447
448 // Check for STARTTLS
449 if (strcmp(line, "STARTTLS") == 0)
450 features->starttls = 1;
451
452 // Parse authentication mechanisms
453 else if (strncmp(line, "AUTH ", 5) == 0)
454 parse_auth_line(line, &features->auth);
455 }
456
457 syslog(LOG_DEBUG, "Server greeting successfully completed");
458
459 // STARTTLS
460 if (features->starttls)
461 syslog(LOG_DEBUG, " Server supports STARTTLS");
462 else
463 syslog(LOG_DEBUG, " Server does not support STARTTLS");
464
465 // Authentication
466 if (features->auth.cram_md5) {
467 syslog(LOG_DEBUG, " Server supports CRAM-MD5 authentication");
468 }
469 if (features->auth.login) {
470 syslog(LOG_DEBUG, " Server supports LOGIN authentication");
471 }
472
473 return 0;
474 }
475
476 static int
deliver_to_host(struct qitem * it,struct mx_hostentry * host)477 deliver_to_host(struct qitem *it, struct mx_hostentry *host)
478 {
479 struct authuser *a;
480 struct smtp_features features;
481 char line[1000], *addrtmp = NULL, *to_addr;
482 size_t linelen;
483 int fd, error = 0, do_auth = 0, res = 0;
484
485 if (fseek(it->mailf, 0, SEEK_SET) != 0) {
486 snprintf(errmsg, sizeof(errmsg), "can not seek: %s", strerror(errno));
487 return (-1);
488 }
489
490 fd = open_connection(host);
491 if (fd < 0)
492 return (1);
493
494 #define READ_REMOTE_CHECK(c, exp) \
495 do { \
496 res = read_remote(fd, 0, NULL); \
497 if (res == 5) { \
498 syslog(LOG_ERR, "remote delivery to %s [%s] failed after %s: %s", \
499 host->host, host->addr, c, neterr); \
500 snprintf(errmsg, sizeof(errmsg), "%s [%s] did not like our %s:\n%s", \
501 host->host, host->addr, c, neterr); \
502 error = -1; \
503 goto out; \
504 } else if (res != exp) { \
505 syslog(LOG_NOTICE, "remote delivery deferred: %s [%s] failed after %s: %s", \
506 host->host, host->addr, c, neterr); \
507 error = 1; \
508 goto out; \
509 } \
510 } while (0)
511
512 /* Check first reply from remote host */
513 if ((config.features & SECURETRANSFER) == 0 ||
514 (config.features & STARTTLS) != 0) {
515 config.features |= NOSSL;
516 READ_REMOTE_CHECK("connect", 2);
517
518 config.features &= ~NOSSL;
519 }
520
521 if ((config.features & SECURETRANSFER) != 0) {
522 error = smtp_init_crypto(fd, config.features, &features);
523 if (error == 0)
524 syslog(LOG_DEBUG, "SSL initialization successful");
525 else
526 goto out;
527
528 if ((config.features & STARTTLS) == 0)
529 READ_REMOTE_CHECK("connect", 2);
530 }
531
532 // Say EHLO
533 if (perform_server_greeting(fd, &features) != 0) {
534 syslog(LOG_ERR, "Could not perform server greeting at %s [%s]: %s",
535 host->host, host->addr, neterr);
536 return -1;
537 }
538
539 /*
540 * Use SMTP authentication if the user defined an entry for the remote
541 * or smarthost
542 */
543 SLIST_FOREACH(a, &authusers, next) {
544 if (strcmp(a->host, host->host) == 0) {
545 do_auth = 1;
546 break;
547 }
548 }
549
550 if (do_auth == 1) {
551 /*
552 * Check if the user wants plain text login without using
553 * encryption.
554 */
555 syslog(LOG_INFO, "using SMTP authentication for user %s", a->login);
556 error = smtp_login(fd, a->login, a->password, &features);
557 if (error < 0) {
558 syslog(LOG_ERR, "remote delivery failed:"
559 " SMTP login failed: %m");
560 snprintf(errmsg, sizeof(errmsg), "SMTP login to %s failed", host->host);
561 error = -1;
562 goto out;
563 }
564 /* SMTP login is not available, so try without */
565 else if (error > 0) {
566 syslog(LOG_WARNING, "SMTP login not available. Trying without.");
567 }
568 }
569
570 /* XXX send ESMTP ENVID, RET (FULL/HDRS) and 8BITMIME */
571 send_remote_command(fd, "MAIL FROM:<%s>", it->sender);
572 READ_REMOTE_CHECK("MAIL FROM", 2);
573
574 /* XXX send ESMTP ORCPT */
575 if ((addrtmp = strdup(it->addr)) == NULL) {
576 syslog(LOG_CRIT, "remote delivery deferred: unable to allocate memory");
577 error = 1;
578 goto out;
579 }
580 to_addr = strtok(addrtmp, ",");
581 while (to_addr != NULL) {
582 send_remote_command(fd, "RCPT TO:<%s>", to_addr);
583 READ_REMOTE_CHECK("RCPT TO", 2);
584 to_addr = strtok(NULL, ",");
585 }
586
587 send_remote_command(fd, "DATA");
588 READ_REMOTE_CHECK("DATA", 3);
589
590 error = 0;
591 while (!feof(it->mailf)) {
592 if (fgets(line, sizeof(line), it->mailf) == NULL)
593 break;
594 linelen = strlen(line);
595 if (linelen == 0 || line[linelen - 1] != '\n') {
596 syslog(LOG_CRIT, "remote delivery failed: corrupted queue file");
597 snprintf(errmsg, sizeof(errmsg), "corrupted queue file");
598 error = -1;
599 goto out;
600 }
601
602 /* Remove trailing \n's and escape leading dots */
603 trim_line(line);
604
605 /*
606 * If the first character is a dot, we escape it so the line
607 * length increases
608 */
609 if (line[0] == '.')
610 linelen++;
611
612 if (send_remote_command(fd, "%s", line) != (ssize_t)linelen+1) {
613 syslog(LOG_NOTICE, "remote delivery deferred: write error");
614 error = 1;
615 goto out;
616 }
617 }
618
619 send_remote_command(fd, ".");
620 READ_REMOTE_CHECK("final DATA", 2);
621
622 send_remote_command(fd, "QUIT");
623 if (read_remote(fd, 0, NULL) != 2)
624 syslog(LOG_INFO, "remote delivery succeeded but QUIT failed: %s", neterr);
625 out:
626
627 free(addrtmp);
628 close_connection(fd);
629 return (error);
630 }
631
632 int
deliver_remote(struct qitem * it)633 deliver_remote(struct qitem *it)
634 {
635 struct mx_hostentry *hosts, *h;
636 const char *host;
637 int port;
638 int error = 1, smarthost = 0;
639
640 port = SMTP_PORT;
641
642 /* Smarthost support? */
643 if (config.smarthost != NULL) {
644 host = config.smarthost;
645 port = config.port;
646 syslog(LOG_INFO, "using smarthost (%s:%i)", host, port);
647 smarthost = 1;
648 } else {
649 host = strrchr(it->addr, '@');
650 /* Should not happen */
651 if (host == NULL) {
652 snprintf(errmsg, sizeof(errmsg), "Internal error: badly formed address %s",
653 it->addr);
654 return(-1);
655 } else {
656 /* Step over the @ */
657 host++;
658 }
659 }
660
661 error = dns_get_mx_list(host, port, &hosts, smarthost);
662 if (error) {
663 snprintf(errmsg, sizeof(errmsg), "DNS lookup failure: host %s not found", host);
664 syslog(LOG_NOTICE, "remote delivery %s: DNS lookup failure: host %s not found",
665 error < 0 ? "failed" : "deferred",
666 host);
667 return (error);
668 }
669
670 for (h = hosts; *h->host != 0; h++) {
671 switch (deliver_to_host(it, h)) {
672 case 0:
673 /* success */
674 error = 0;
675 goto out;
676 case 1:
677 /* temp failure */
678 error = 1;
679 break;
680 default:
681 /* perm failure */
682 error = -1;
683 goto out;
684 }
685 }
686 out:
687 free(hosts);
688
689 return (error);
690 }
691