local.c revision 262282 
1/*
2 * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Simon 'corecode' Schubert <corecode@fs.ei.tum.de>.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in
15 *    the documentation and/or other materials provided with the
16 *    distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 *    contributors may be used to endorse or promote products derived
19 *    from this software without specific, prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/types.h>
36#include <sys/wait.h>
37
38#include <err.h>
39#include <errno.h>
40#include <fcntl.h>
41#include <limits.h>
42#include <paths.h>
43#include <signal.h>
44#include <stdint.h>
45#include <stdio.h>
46#include <syslog.h>
47#include <unistd.h>
48
49#include "dma.h"
50
51static int
52create_mbox(const char *name)
53{
54	struct sigaction sa, osa;
55	pid_t child, waitchild;
56	int status;
57	int i;
58	long maxfd;
59	int e;
60	int r = -1;
61
62	/*
63	 * We need to enable SIGCHLD temporarily so that waitpid works.
64	 */
65	bzero(&sa, sizeof(sa));
66	sa.sa_handler = SIG_DFL;
67	sigaction(SIGCHLD, &sa, &osa);
68
69	do_timeout(100, 0);
70
71	child = fork();
72	switch (child) {
73	case 0:
74		/* child */
75		maxfd = sysconf(_SC_OPEN_MAX);
76		if (maxfd == -1)
77			maxfd = 1024;	/* what can we do... */
78
79		for (i = 3; i <= maxfd; ++i)
80			close(i);
81
82		execl(LIBEXEC_PATH "/dma-mbox-create", "dma-mbox-create", name, NULL);
83		syslog(LOG_ERR, "cannot execute "LIBEXEC_PATH"/dma-mbox-create: %m");
84		exit(1);
85
86	default:
87		/* parent */
88		waitchild = waitpid(child, &status, 0);
89
90		e = errno;
91
92		do_timeout(0, 0);
93
94		if (waitchild == -1 && e == EINTR) {
95			syslog(LOG_ERR, "hung child while creating mbox `%s': %m", name);
96			break;
97		}
98
99		if (waitchild == -1) {
100			syslog(LOG_ERR, "child disappeared while creating mbox `%s': %m", name);
101			break;
102		}
103
104		if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
105			syslog(LOG_ERR, "error creating mbox `%s'", name);
106			break;
107		}
108
109		/* success */
110		r = 0;
111		break;
112
113	case -1:
114		/* error */
115		syslog(LOG_ERR, "error creating mbox");
116		break;
117	}
118
119	sigaction(SIGCHLD, &osa, NULL);
120
121	return (r);
122}
123
124int
125deliver_local(struct qitem *it)
126{
127	char fn[PATH_MAX+1];
128	char line[1000];
129	const char *sender;
130	const char *newline = "\n";
131	size_t linelen;
132	int tries = 0;
133	int mbox;
134	int error;
135	int hadnl = 0;
136	off_t mboxlen;
137	time_t now = time(NULL);
138
139	error = snprintf(fn, sizeof(fn), "%s/%s", _PATH_MAILDIR, it->addr);
140	if (error < 0 || (size_t)error >= sizeof(fn)) {
141		syslog(LOG_NOTICE, "local delivery deferred: %m");
142		return (1);
143	}
144
145retry:
146	/* wait for a maximum of 100s to get the lock to the file */
147	do_timeout(100, 0);
148
149	/* don't use O_CREAT here, because we might be running as the wrong user. */
150	mbox = open_locked(fn, O_WRONLY|O_APPEND);
151	if (mbox < 0) {
152		int e = errno;
153
154		do_timeout(0, 0);
155
156		switch (e) {
157		case EACCES:
158		case ENOENT:
159			/*
160			 * The file does not exist or we can't access it.
161			 * Call dma-mbox-create to create it and fix permissions.
162			 */
163			if (tries > 0 || create_mbox(it->addr) != 0) {
164				syslog(LOG_ERR, "local delivery deferred: can not create `%s'", fn);
165				return (1);
166			}
167			++tries;
168			goto retry;
169
170		case EINTR:
171			syslog(LOG_NOTICE, "local delivery deferred: can not lock `%s'", fn);
172			break;
173
174		default:
175			syslog(LOG_NOTICE, "local delivery deferred: can not open `%s': %m", fn);
176			break;
177		}
178		return (1);
179	}
180	do_timeout(0, 0);
181
182	mboxlen = lseek(mbox, 0, SEEK_END);
183
184	/* New mails start with \nFrom ...., unless we're at the beginning of the mbox */
185	if (mboxlen == 0)
186		newline = "";
187
188	/* If we're bouncing a message, claim it comes from MAILER-DAEMON */
189	sender = it->sender;
190	if (strcmp(sender, "") == 0)
191		sender = "MAILER-DAEMON";
192
193	if (fseek(it->mailf, 0, SEEK_SET) != 0) {
194		syslog(LOG_NOTICE, "local delivery deferred: can not seek: %m");
195		goto out;
196	}
197
198	error = snprintf(line, sizeof(line), "%sFrom %s\t%s", newline, sender, ctime(&now));
199	if (error < 0 || (size_t)error >= sizeof(line)) {
200		syslog(LOG_NOTICE, "local delivery deferred: can not write header: %m");
201		goto out;
202	}
203	if (write(mbox, line, error) != error)
204		goto wrerror;
205
206	while (!feof(it->mailf)) {
207		if (fgets(line, sizeof(line), it->mailf) == NULL)
208			break;
209		linelen = strlen(line);
210		if (linelen == 0 || line[linelen - 1] != '\n') {
211			syslog(LOG_CRIT, "local delivery failed: corrupted queue file");
212			snprintf(errmsg, sizeof(errmsg), "corrupted queue file");
213			error = -1;
214			goto chop;
215		}
216
217		/*
218		 * mboxro processing:
219		 * - escape lines that start with "From " with a > sign.
220		 * - be reversable by escaping lines that contain an arbitrary
221		 *   number of > signs, followed by "From ", i.e. />*From / in regexp.
222		 * - strict mbox processing only requires escaping after empty lines,
223		 *   yet most MUAs seem to relax this requirement and will treat any
224		 *   line starting with "From " as the beginning of a new mail.
225		 */
226		if ((!MBOX_STRICT || hadnl) &&
227		    strncmp(&line[strspn(line, ">")], "From ", 5) == 0) {
228			const char *gt = ">";
229
230			if (write(mbox, gt, 1) != 1)
231				goto wrerror;
232			hadnl = 0;
233		} else if (strcmp(line, "\n") == 0) {
234			hadnl = 1;
235		} else {
236			hadnl = 0;
237		}
238		if ((size_t)write(mbox, line, linelen) != linelen)
239			goto wrerror;
240	}
241	close(mbox);
242	return (0);
243
244wrerror:
245	syslog(LOG_ERR, "local delivery failed: write error: %m");
246	error = 1;
247chop:
248	if (ftruncate(mbox, mboxlen) != 0)
249		syslog(LOG_WARNING, "error recovering mbox `%s': %m", fn);
250out:
251	close(mbox);
252	return (error);
253}
254