local.c revision 289123 
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 <sys/types.h>
37#include <sys/wait.h>
38
39#include <err.h>
40#include <errno.h>
41#include <fcntl.h>
42#include <limits.h>
43#include <paths.h>
44#include <signal.h>
45#include <stdint.h>
46#include <stdio.h>
47#include <syslog.h>
48#include <unistd.h>
49
50#include "dma.h"
51
52static int
53create_mbox(const char *name)
54{
55	struct sigaction sa, osa;
56	pid_t child, waitchild;
57	int status;
58	int i;
59	long maxfd;
60	int e;
61	int r = -1;
62
63	/*
64	 * We need to enable SIGCHLD temporarily so that waitpid works.
65	 */
66	bzero(&sa, sizeof(sa));
67	sa.sa_handler = SIG_DFL;
68	sigaction(SIGCHLD, &sa, &osa);
69
70	do_timeout(100, 0);
71
72	child = fork();
73	switch (child) {
74	case 0:
75		/* child */
76		maxfd = sysconf(_SC_OPEN_MAX);
77		if (maxfd == -1)
78			maxfd = 1024;	/* what can we do... */
79
80		for (i = 3; i <= maxfd; ++i)
81			close(i);
82
83		execl(LIBEXEC_PATH "/dma-mbox-create", "dma-mbox-create", name, NULL);
84		syslog(LOG_ERR, "cannot execute "LIBEXEC_PATH"/dma-mbox-create: %m");
85		exit(EX_SOFTWARE);
86
87	default:
88		/* parent */
89		waitchild = waitpid(child, &status, 0);
90
91		e = errno;
92
93		do_timeout(0, 0);
94
95		if (waitchild == -1 && e == EINTR) {
96			syslog(LOG_ERR, "hung child while creating mbox `%s': %m", name);
97			break;
98		}
99
100		if (waitchild == -1) {
101			syslog(LOG_ERR, "child disappeared while creating mbox `%s': %m", name);
102			break;
103		}
104
105		if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
106			syslog(LOG_ERR, "error creating mbox `%s'", name);
107			break;
108		}
109
110		/* success */
111		r = 0;
112		break;
113
114	case -1:
115		/* error */
116		syslog(LOG_ERR, "error creating mbox");
117		break;
118	}
119
120	sigaction(SIGCHLD, &osa, NULL);
121
122	return (r);
123}
124
125int
126deliver_local(struct qitem *it)
127{
128	char fn[PATH_MAX+1];
129	char line[1000];
130	const char *sender;
131	const char *newline = "\n";
132	size_t linelen;
133	int tries = 0;
134	int mbox;
135	int error;
136	int hadnl = 0;
137	off_t mboxlen;
138	time_t now = time(NULL);
139
140	error = snprintf(fn, sizeof(fn), "%s/%s", _PATH_MAILDIR, it->addr);
141	if (error < 0 || (size_t)error >= sizeof(fn)) {
142		syslog(LOG_NOTICE, "local delivery deferred: %m");
143		return (1);
144	}
145
146retry:
147	/* wait for a maximum of 100s to get the lock to the file */
148	do_timeout(100, 0);
149
150	/* don't use O_CREAT here, because we might be running as the wrong user. */
151	mbox = open_locked(fn, O_WRONLY|O_APPEND);
152	if (mbox < 0) {
153		int e = errno;
154
155		do_timeout(0, 0);
156
157		switch (e) {
158		case EACCES:
159		case ENOENT:
160			/*
161			 * The file does not exist or we can't access it.
162			 * Call dma-mbox-create to create it and fix permissions.
163			 */
164			if (tries > 0 || create_mbox(it->addr) != 0) {
165				syslog(LOG_ERR, "local delivery deferred: can not create `%s'", fn);
166				return (1);
167			}
168			++tries;
169			goto retry;
170
171		case EINTR:
172			syslog(LOG_NOTICE, "local delivery deferred: can not lock `%s'", fn);
173			break;
174
175		default:
176			syslog(LOG_NOTICE, "local delivery deferred: can not open `%s': %m", fn);
177			break;
178		}
179		return (1);
180	}
181	do_timeout(0, 0);
182
183	mboxlen = lseek(mbox, 0, SEEK_END);
184
185	/* New mails start with \nFrom ...., unless we're at the beginning of the mbox */
186	if (mboxlen == 0)
187		newline = "";
188
189	/* If we're bouncing a message, claim it comes from MAILER-DAEMON */
190	sender = it->sender;
191	if (strcmp(sender, "") == 0)
192		sender = "MAILER-DAEMON";
193
194	if (fseek(it->mailf, 0, SEEK_SET) != 0) {
195		syslog(LOG_NOTICE, "local delivery deferred: can not seek: %m");
196		goto out;
197	}
198
199	error = snprintf(line, sizeof(line), "%sFrom %s\t%s", newline, sender, ctime(&now));
200	if (error < 0 || (size_t)error >= sizeof(line)) {
201		syslog(LOG_NOTICE, "local delivery deferred: can not write header: %m");
202		goto out;
203	}
204	if (write(mbox, line, error) != error)
205		goto wrerror;
206
207	while (!feof(it->mailf)) {
208		if (fgets(line, sizeof(line), it->mailf) == NULL)
209			break;
210		linelen = strlen(line);
211		if (linelen == 0 || line[linelen - 1] != '\n') {
212			syslog(LOG_CRIT, "local delivery failed: corrupted queue file");
213			snprintf(errmsg, sizeof(errmsg), "corrupted queue file");
214			error = -1;
215			goto chop;
216		}
217
218		/*
219		 * mboxro processing:
220		 * - escape lines that start with "From " with a > sign.
221		 * - be reversable by escaping lines that contain an arbitrary
222		 *   number of > signs, followed by "From ", i.e. />*From / in regexp.
223		 * - strict mbox processing only requires escaping after empty lines,
224		 *   yet most MUAs seem to relax this requirement and will treat any
225		 *   line starting with "From " as the beginning of a new mail.
226		 */
227		if ((!MBOX_STRICT || hadnl) &&
228		    strncmp(&line[strspn(line, ">")], "From ", 5) == 0) {
229			const char *gt = ">";
230
231			if (write(mbox, gt, 1) != 1)
232				goto wrerror;
233			hadnl = 0;
234		} else if (strcmp(line, "\n") == 0) {
235			hadnl = 1;
236		} else {
237			hadnl = 0;
238		}
239		if ((size_t)write(mbox, line, linelen) != linelen)
240			goto wrerror;
241	}
242	close(mbox);
243	return (0);
244
245wrerror:
246	syslog(LOG_ERR, "local delivery failed: write error: %m");
247	error = 1;
248chop:
249	if (ftruncate(mbox, mboxlen) != 0)
250		syslog(LOG_WARNING, "error recovering mbox `%s': %m", fn);
251out:
252	close(mbox);
253	return (error);
254}
255