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 Simon Schubert <2@0x2c.org>.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in
16 *    the documentation and/or other materials provided with the
17 *    distribution.
18 * 3. Neither the name of The DragonFly Project nor the names of its
19 *    contributors may be used to endorse or promote products derived
20 *    from this software without specific, prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
25 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
26 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
28 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
29 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
30 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
31 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
32 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include "dfcompat.h"
37
38#include <sys/param.h>
39#include <sys/types.h>
40#include <sys/queue.h>
41#include <sys/stat.h>
42#include <sys/time.h>
43#include <sys/wait.h>
44
45#include <dirent.h>
46#include <err.h>
47#include <errno.h>
48#include <fcntl.h>
49#include <inttypes.h>
50#include <libgen.h>
51#include <paths.h>
52#include <pwd.h>
53#include <signal.h>
54#include <stdarg.h>
55#include <stdio.h>
56#include <stdlib.h>
57#include <string.h>
58#include <syslog.h>
59#include <unistd.h>
60
61#include "dma.h"
62
63
64static void deliver(struct qitem *);
65
66struct aliases aliases = LIST_HEAD_INITIALIZER(aliases);
67struct strlist tmpfs = SLIST_HEAD_INITIALIZER(tmpfs);
68struct authusers authusers = LIST_HEAD_INITIALIZER(authusers);
69char username[USERNAME_SIZE];
70uid_t useruid;
71const char *logident_base;
72char errmsg[ERRMSG_SIZE];
73
74static int daemonize = 1;
75static int doqueue = 0;
76
77struct config config = {
78	.smarthost	= NULL,
79	.port		= 25,
80	.aliases	= "/etc/aliases",
81	.spooldir	= "/var/spool/dma",
82	.authpath	= NULL,
83	.certfile	= NULL,
84	.features	= 0,
85	.mailname	= NULL,
86	.masquerade_host = NULL,
87	.masquerade_user = NULL,
88};
89
90
91static void
92sighup_handler(int signo)
93{
94	(void)signo;	/* so that gcc doesn't complain */
95}
96
97static char *
98set_from(struct queue *queue, const char *osender)
99{
100	const char *addr;
101	char *sender;
102
103	if (osender) {
104		addr = osender;
105	} else if (getenv("EMAIL") != NULL) {
106		addr = getenv("EMAIL");
107	} else {
108		if (config.masquerade_user)
109			addr = config.masquerade_user;
110		else
111			addr = username;
112	}
113
114	if (!strchr(addr, '@')) {
115		const char *from_host = hostname();
116
117		if (config.masquerade_host)
118			from_host = config.masquerade_host;
119
120		if (asprintf(&sender, "%s@%s", addr, from_host) <= 0)
121			return (NULL);
122	} else {
123		sender = strdup(addr);
124		if (sender == NULL)
125			return (NULL);
126	}
127
128	if (strchr(sender, '\n') != NULL) {
129		errno = EINVAL;
130		return (NULL);
131	}
132
133	queue->sender = sender;
134	return (sender);
135}
136
137static int
138read_aliases(void)
139{
140	yyin = fopen(config.aliases, "r");
141	if (yyin == NULL) {
142		/*
143		 * Non-existing aliases file is not a fatal error
144		 */
145		if (errno == ENOENT)
146			return (0);
147		/* Other problems are. */
148		return (-1);
149	}
150	if (yyparse())
151		return (-1);	/* fatal error, probably malloc() */
152	fclose(yyin);
153	return (0);
154}
155
156static int
157do_alias(struct queue *queue, const char *addr)
158{
159	struct alias *al;
160        struct stritem *sit;
161	int aliased = 0;
162
163        LIST_FOREACH(al, &aliases, next) {
164                if (strcmp(al->alias, addr) != 0)
165                        continue;
166		SLIST_FOREACH(sit, &al->dests, next) {
167			if (add_recp(queue, sit->str, EXPAND_ADDR) != 0)
168				return (-1);
169		}
170		aliased = 1;
171        }
172
173        return (aliased);
174}
175
176int
177add_recp(struct queue *queue, const char *str, int expand)
178{
179	struct qitem *it, *tit;
180	struct passwd *pw;
181	char *host;
182	int aliased = 0;
183
184	it = calloc(1, sizeof(*it));
185	if (it == NULL)
186		return (-1);
187	it->addr = strdup(str);
188	if (it->addr == NULL)
189		return (-1);
190
191	it->sender = queue->sender;
192	host = strrchr(it->addr, '@');
193	if (host != NULL &&
194	    (strcmp(host + 1, hostname()) == 0 ||
195	     strcmp(host + 1, "localhost") == 0)) {
196		*host = 0;
197	}
198	LIST_FOREACH(tit, &queue->queue, next) {
199		/* weed out duplicate dests */
200		if (strcmp(tit->addr, it->addr) == 0) {
201			free(it->addr);
202			free(it);
203			return (0);
204		}
205	}
206	LIST_INSERT_HEAD(&queue->queue, it, next);
207
208	/**
209	 * Do local delivery if there is no @.
210	 * Do not do local delivery when NULLCLIENT is set.
211	 */
212	if (strrchr(it->addr, '@') == NULL && (config.features & NULLCLIENT) == 0) {
213		it->remote = 0;
214		if (expand) {
215			aliased = do_alias(queue, it->addr);
216			if (!aliased && expand == EXPAND_WILDCARD)
217				aliased = do_alias(queue, "*");
218			if (aliased < 0)
219				return (-1);
220			if (aliased) {
221				LIST_REMOVE(it, next);
222			} else {
223				/* Local destination, check */
224				pw = getpwnam(it->addr);
225				if (pw == NULL)
226					goto out;
227				/* XXX read .forward */
228				endpwent();
229			}
230		}
231	} else {
232		it->remote = 1;
233	}
234
235	return (0);
236
237out:
238	free(it->addr);
239	free(it);
240	return (-1);
241}
242
243static struct qitem *
244go_background(struct queue *queue)
245{
246	struct sigaction sa;
247	struct qitem *it;
248	pid_t pid;
249
250	if (daemonize && daemon(0, 0) != 0) {
251		syslog(LOG_ERR, "can not daemonize: %m");
252		exit(EX_OSERR);
253	}
254	daemonize = 0;
255
256	bzero(&sa, sizeof(sa));
257	sa.sa_handler = SIG_IGN;
258	sigaction(SIGCHLD, &sa, NULL);
259
260	LIST_FOREACH(it, &queue->queue, next) {
261		/* No need to fork for the last dest */
262		if (LIST_NEXT(it, next) == NULL)
263			goto retit;
264
265		pid = fork();
266		switch (pid) {
267		case -1:
268			syslog(LOG_ERR, "can not fork: %m");
269			exit(EX_OSERR);
270			break;
271
272		case 0:
273			/*
274			 * Child:
275			 *
276			 * return and deliver mail
277			 */
278retit:
279			/*
280			 * If necessary, acquire the queue and * mail files.
281			 * If this fails, we probably were raced by another
282			 * process.  It is okay to be raced if we're supposed
283			 * to flush the queue.
284			 */
285			setlogident("%s", it->queueid);
286			switch (acquirespool(it)) {
287			case 0:
288				break;
289			case 1:
290				if (doqueue)
291					exit(EX_OK);
292				syslog(LOG_WARNING, "could not lock queue file");
293				exit(EX_SOFTWARE);
294			default:
295				exit(EX_SOFTWARE);
296			}
297			dropspool(queue, it);
298			return (it);
299
300		default:
301			/*
302			 * Parent:
303			 *
304			 * fork next child
305			 */
306			break;
307		}
308	}
309
310	syslog(LOG_CRIT, "reached dead code");
311	exit(EX_SOFTWARE);
312}
313
314static void
315deliver(struct qitem *it)
316{
317	int error;
318	unsigned int backoff = MIN_RETRY, slept;
319	struct timeval now;
320	struct stat st;
321
322	snprintf(errmsg, sizeof(errmsg), "unknown bounce reason");
323
324retry:
325	syslog(LOG_INFO, "<%s> trying delivery", it->addr);
326
327	if (it->remote)
328		error = deliver_remote(it);
329	else
330		error = deliver_local(it);
331
332	switch (error) {
333	case 0:
334		syslog(LOG_INFO, "<%s> delivery successful", it->addr);
335		delqueue(it);
336		exit(EX_OK);
337
338	case 1:
339		if (stat(it->queuefn, &st) != 0) {
340			syslog(LOG_ERR, "lost queue file `%s'", it->queuefn);
341			exit(EX_SOFTWARE);
342		}
343		if (gettimeofday(&now, NULL) == 0 &&
344		    (now.tv_sec - st.st_mtim.tv_sec > MAX_TIMEOUT)) {
345			snprintf(errmsg, sizeof(errmsg),
346				 "Could not deliver for the last %d seconds. Giving up.",
347				 MAX_TIMEOUT);
348			goto bounce;
349		}
350		for (slept = 0; slept < backoff;) {
351			slept += SLEEP_TIMEOUT - sleep(SLEEP_TIMEOUT);
352			if (flushqueue_since(slept)) {
353				backoff = MIN_RETRY;
354				goto retry;
355			}
356		}
357		if (slept >= backoff) {
358			/* pick the next backoff between [1.5, 2.5) times backoff */
359			backoff = backoff + backoff / 2 + random() % backoff;
360			if (backoff > MAX_RETRY)
361				backoff = MAX_RETRY;
362		}
363		goto retry;
364
365	case -1:
366	default:
367		break;
368	}
369
370bounce:
371	bounce(it, errmsg);
372	/* NOTREACHED */
373}
374
375void
376run_queue(struct queue *queue)
377{
378	struct qitem *it;
379
380	if (LIST_EMPTY(&queue->queue))
381		return;
382
383	it = go_background(queue);
384	deliver(it);
385	/* NOTREACHED */
386}
387
388static void
389show_queue(struct queue *queue)
390{
391	struct qitem *it;
392	int locked = 0;	/* XXX */
393
394	if (LIST_EMPTY(&queue->queue)) {
395		printf("Mail queue is empty\n");
396		return;
397	}
398
399	LIST_FOREACH(it, &queue->queue, next) {
400		printf("ID\t: %s%s\n"
401		       "From\t: %s\n"
402		       "To\t: %s\n",
403		       it->queueid,
404		       locked ? "*" : "",
405		       it->sender, it->addr);
406
407		if (LIST_NEXT(it, next) != NULL)
408			printf("--\n");
409	}
410}
411
412/*
413 * TODO:
414 *
415 * - alias processing
416 * - use group permissions
417 * - proper sysexit codes
418 */
419
420int
421main(int argc, char **argv)
422{
423	struct sigaction act;
424	char *sender = NULL;
425	struct queue queue;
426	int i, ch;
427	int nodot = 0, showq = 0, queue_only = 0;
428	int recp_from_header = 0;
429
430	set_username();
431
432	/*
433	 * We never run as root.  If called by root, drop permissions
434	 * to the mail user.
435	 */
436	if (geteuid() == 0 || getuid() == 0) {
437		struct passwd *pw;
438
439		errno = 0;
440		pw = getpwnam(DMA_ROOT_USER);
441		if (pw == NULL) {
442			if (errno == 0)
443				errx(EX_CONFIG, "user '%s' not found", DMA_ROOT_USER);
444			else
445				err(EX_OSERR, "cannot drop root privileges");
446		}
447
448		if (setuid(pw->pw_uid) != 0)
449			err(EX_OSERR, "cannot drop root privileges");
450
451		if (geteuid() == 0 || getuid() == 0)
452			errx(EX_OSERR, "cannot drop root privileges");
453	}
454
455	atexit(deltmp);
456	init_random();
457
458	bzero(&queue, sizeof(queue));
459	LIST_INIT(&queue.queue);
460
461	if (strcmp(basename(argv[0]), "mailq") == 0) {
462		argv++; argc--;
463		showq = 1;
464		if (argc != 0)
465			errx(EX_USAGE, "invalid arguments");
466		goto skipopts;
467	} else if (strcmp(argv[0], "newaliases") == 0) {
468		logident_base = "dma";
469		setlogident("%s", logident_base);
470
471		if (read_aliases() != 0)
472			errx(EX_SOFTWARE, "could not parse aliases file `%s'", config.aliases);
473		exit(EX_OK);
474	}
475
476	opterr = 0;
477	while ((ch = getopt(argc, argv, ":A:b:B:C:d:Df:F:h:iL:N:no:O:q:r:R:tUV:vX:")) != -1) {
478		switch (ch) {
479		case 'A':
480			/* -AX is being ignored, except for -A{c,m} */
481			if (optarg[0] == 'c' || optarg[0] == 'm') {
482				break;
483			}
484			/* else FALLTRHOUGH */
485		case 'b':
486			/* -bX is being ignored, except for -bp */
487			if (optarg[0] == 'p') {
488				showq = 1;
489				break;
490			} else if (optarg[0] == 'q') {
491				queue_only = 1;
492				break;
493			}
494			/* else FALLTRHOUGH */
495		case 'D':
496			daemonize = 0;
497			break;
498		case 'L':
499			logident_base = optarg;
500			break;
501		case 'f':
502		case 'r':
503			sender = optarg;
504			break;
505
506		case 't':
507			recp_from_header = 1;
508			break;
509
510		case 'o':
511			/* -oX is being ignored, except for -oi */
512			if (optarg[0] != 'i')
513				break;
514			/* else FALLTRHOUGH */
515		case 'O':
516			break;
517		case 'i':
518			nodot = 1;
519			break;
520
521		case 'q':
522			/* Don't let getopt slup up other arguments */
523			if (optarg && *optarg == '-')
524				optind--;
525			doqueue = 1;
526			break;
527
528		/* Ignored options */
529		case 'B':
530		case 'C':
531		case 'd':
532		case 'F':
533		case 'h':
534		case 'N':
535		case 'n':
536		case 'R':
537		case 'U':
538		case 'V':
539		case 'v':
540		case 'X':
541			break;
542
543		case ':':
544			if (optopt == 'q') {
545				doqueue = 1;
546				break;
547			}
548			/* FALLTHROUGH */
549
550		default:
551			fprintf(stderr, "invalid argument: `-%c'\n", optopt);
552			exit(EX_USAGE);
553		}
554	}
555	argc -= optind;
556	argv += optind;
557	opterr = 1;
558
559	if (argc != 0 && (showq || doqueue))
560		errx(EX_USAGE, "sending mail and queue operations are mutually exclusive");
561
562	if (showq + doqueue > 1)
563		errx(EX_USAGE, "conflicting queue operations");
564
565skipopts:
566	if (logident_base == NULL)
567		logident_base = "dma";
568	setlogident("%s", logident_base);
569
570	act.sa_handler = sighup_handler;
571	act.sa_flags = 0;
572	sigemptyset(&act.sa_mask);
573	if (sigaction(SIGHUP, &act, NULL) != 0)
574		syslog(LOG_WARNING, "can not set signal handler: %m");
575
576	parse_conf(CONF_PATH "/dma.conf");
577
578	if (config.authpath != NULL)
579		parse_authfile(config.authpath);
580
581	if (showq) {
582		if (load_queue(&queue) < 0)
583			errlog(EX_NOINPUT, "can not load queue");
584		show_queue(&queue);
585		return (0);
586	}
587
588	if (doqueue) {
589		flushqueue_signal();
590		if (load_queue(&queue) < 0)
591			errlog(EX_NOINPUT, "can not load queue");
592		run_queue(&queue);
593		return (0);
594	}
595
596	if (read_aliases() != 0)
597		errlog(EX_SOFTWARE, "could not parse aliases file `%s'", config.aliases);
598
599	if ((sender = set_from(&queue, sender)) == NULL)
600		errlog(EX_SOFTWARE, "set_from()");
601
602	if (newspoolf(&queue) != 0)
603		errlog(EX_CANTCREAT, "can not create temp file in `%s'", config.spooldir);
604
605	setlogident("%s", queue.id);
606
607	for (i = 0; i < argc; i++) {
608		if (add_recp(&queue, argv[i], EXPAND_WILDCARD) != 0)
609			errlogx(EX_DATAERR, "invalid recipient `%s'", argv[i]);
610	}
611
612	if (LIST_EMPTY(&queue.queue) && !recp_from_header)
613		errlogx(EX_NOINPUT, "no recipients");
614
615	if (readmail(&queue, nodot, recp_from_header) != 0)
616		errlog(EX_NOINPUT, "can not read mail");
617
618	if (LIST_EMPTY(&queue.queue))
619		errlogx(EX_NOINPUT, "no recipients");
620
621	if (linkspool(&queue) != 0)
622		errlog(EX_CANTCREAT, "can not create spools");
623
624	/* From here on the mail is safe. */
625
626	if (config.features & DEFER || queue_only)
627		return (0);
628
629	run_queue(&queue);
630
631	/* NOTREACHED */
632	return (0);
633}
634