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
61char neterr[ERRMSG_SIZE];
62
63char *
64ssl_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
75ssize_t
76send_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
120int
121read_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
241error:
242	do_timeout(0, 0);
243	return (-1);
244}
245
246/*
247 * Handle SMTP authentication
248 */
249static int
250smtp_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) {
279encerr:
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
313static int
314open_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
338static void
339close_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
351static int
352deliver_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);
486out:
487
488	close_connection(fd);
489	return (error);
490}
491
492int
493deliver_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	}
546out:
547	free(hosts);
548
549	return (error);
550}
551