1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1980, 1993
5 *	The Regents of the University of California.  All rights reserved.
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 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/param.h>
33#include <sys/socket.h>
34#include <sys/stat.h>
35#include <sys/file.h>
36#include <sys/wait.h>
37
38#include <netinet/in.h>
39
40#include <ctype.h>
41#include <err.h>
42#include <errno.h>
43#include <netdb.h>
44#include <paths.h>
45#include <pwd.h>
46#include <termios.h>
47#include <signal.h>
48#include <stdio.h>
49#include <stdlib.h>
50#include <string.h>
51#include <syslog.h>
52#include <unistd.h>
53#include <utmpx.h>
54
55static int	debug = 0;
56#define	dsyslog	if (debug) syslog
57
58#define MAXIDLE	120
59
60static char	hostname[MAXHOSTNAMELEN];
61
62static void	jkfprintf(FILE *, char[], char[], off_t);
63static void	mailfor(char *);
64static void	notify(struct utmpx *, char[], off_t, int);
65static void	reapchildren(int);
66
67int
68main(int argc __unused, char *argv[] __unused)
69{
70	struct sockaddr_in from;
71	socklen_t fromlen;
72	int cc;
73	char msgbuf[256];
74
75	/* verify proper invocation */
76	fromlen = sizeof(from);
77	if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0)
78		err(1, "getsockname");
79	openlog("comsat", LOG_PID, LOG_DAEMON);
80	if (chdir(_PATH_MAILDIR)) {
81		syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
82		(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
83		exit(1);
84	}
85	(void)gethostname(hostname, sizeof(hostname));
86	(void)signal(SIGTTOU, SIG_IGN);
87	(void)signal(SIGCHLD, reapchildren);
88	for (;;) {
89		cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
90		if (cc <= 0) {
91			if (errno != EINTR)
92				sleep(1);
93			errno = 0;
94			continue;
95		}
96		msgbuf[cc] = '\0';
97		mailfor(msgbuf);
98		sigsetmask(0L);
99	}
100}
101
102static void
103reapchildren(int signo __unused)
104{
105	while (wait3(NULL, WNOHANG, NULL) > 0);
106}
107
108static void
109mailfor(char *name)
110{
111	struct utmpx *utp;
112	char *cp;
113	char *file;
114	off_t offset;
115	int folder;
116	char buf[sizeof(_PATH_MAILDIR) + sizeof(utp->ut_user) + 1];
117	char buf2[sizeof(_PATH_MAILDIR) + sizeof(utp->ut_user) + 1];
118
119	if (!(cp = strchr(name, '@')))
120		return;
121	*cp = '\0';
122	offset = strtoll(cp + 1, NULL, 10);
123	if (!(cp = strchr(cp + 1, ':')))
124		file = name;
125	else
126		file = cp + 1;
127	sprintf(buf, "%s/%.*s", _PATH_MAILDIR, (int)sizeof(utp->ut_user),
128	    name);
129	if (*file != '/') {
130		sprintf(buf2, "%s/%.*s", _PATH_MAILDIR,
131		    (int)sizeof(utp->ut_user), file);
132		file = buf2;
133	}
134	folder = strcmp(buf, file);
135	setutxent();
136	while ((utp = getutxent()) != NULL)
137		if (utp->ut_type == USER_PROCESS && !strcmp(utp->ut_user, name))
138			notify(utp, file, offset, folder);
139	endutxent();
140}
141
142static const char *cr;
143
144static void
145notify(struct utmpx *utp, char file[], off_t offset, int folder)
146{
147	FILE *tp;
148	struct stat stb;
149	struct termios tio;
150	char tty[20];
151	const char *s = utp->ut_line;
152
153	if (strncmp(s, "pts/", 4) == 0)
154		s += 4;
155	if (strchr(s, '/')) {
156		/* A slash is an attempt to break security... */
157		syslog(LOG_AUTH | LOG_NOTICE, "Unexpected `/' in `%s'",
158		    utp->ut_line);
159		return;
160	}
161	(void)snprintf(tty, sizeof(tty), "%s%.*s",
162	    _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line);
163	if (stat(tty, &stb) == -1 || !(stb.st_mode & (S_IXUSR | S_IXGRP))) {
164		dsyslog(LOG_DEBUG, "%s: wrong mode on %s", utp->ut_user, tty);
165		return;
166	}
167	dsyslog(LOG_DEBUG, "notify %s on %s", utp->ut_user, tty);
168	switch (fork()) {
169	case -1:
170		syslog(LOG_NOTICE, "fork failed (%m)");
171		return;
172	case 0:
173		break;
174	default:
175		return;
176	}
177	if ((tp = fopen(tty, "w")) == NULL) {
178		dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
179		_exit(1);
180	}
181	(void)tcgetattr(fileno(tp), &tio);
182	cr = ((tio.c_oflag & (OPOST|ONLCR)) == (OPOST|ONLCR)) ?  "\n" : "\n\r";
183	switch (stb.st_mode & (S_IXUSR | S_IXGRP)) {
184	case S_IXUSR:
185	case (S_IXUSR | S_IXGRP):
186		(void)fprintf(tp,
187		    "%s\007New mail for %s@%.*s\007 has arrived%s%s%s:%s----%s",
188		    cr, utp->ut_user, (int)sizeof(hostname), hostname,
189		    folder ? cr : "", folder ? "to " : "", folder ? file : "",
190		    cr, cr);
191		jkfprintf(tp, utp->ut_user, file, offset);
192		break;
193	case S_IXGRP:
194		(void)fprintf(tp, "\007");
195		(void)fflush(tp);
196		(void)sleep(1);
197		(void)fprintf(tp, "\007");
198		break;
199	default:
200		break;
201	}
202	(void)fclose(tp);
203	_exit(0);
204}
205
206static void
207jkfprintf(FILE *tp, char user[], char file[], off_t offset)
208{
209	unsigned char *cp, ch;
210	FILE *fi;
211	int linecnt, charcnt, inheader;
212	struct passwd *p;
213	unsigned char line[BUFSIZ];
214
215	/* Set effective uid to user in case mail drop is on nfs */
216	if ((p = getpwnam(user)) != NULL)
217		(void) setuid(p->pw_uid);
218
219	if ((fi = fopen(file, "r")) == NULL)
220		return;
221
222	(void)fseeko(fi, offset, SEEK_CUR);
223	/*
224	 * Print the first 7 lines or 560 characters of the new mail
225	 * (whichever comes first).  Skip header crap other than
226	 * From, Subject, To, and Date.
227	 */
228	linecnt = 7;
229	charcnt = 560;
230	inheader = 1;
231	while (fgets(line, sizeof(line), fi) != NULL) {
232		if (inheader) {
233			if (line[0] == '\n') {
234				inheader = 0;
235				continue;
236			}
237			if (line[0] == ' ' || line[0] == '\t' ||
238			    (strncmp(line, "From:", 5) &&
239			    strncmp(line, "Subject:", 8)))
240				continue;
241		}
242		if (linecnt <= 0 || charcnt <= 0) {
243			(void)fprintf(tp, "...more...%s", cr);
244			(void)fclose(fi);
245			return;
246		}
247		/* strip weird stuff so can't trojan horse stupid terminals */
248		for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) {
249			/* disable upper controls and enable all other
250			   8bit codes due to lack of locale knowledge
251			 */
252			if (((ch & 0x80) && ch < 0xA0) ||
253			    (!(ch & 0x80) && !isprint(ch) &&
254			     !isspace(ch) && ch != '\a' && ch != '\b')
255			   ) {
256				if (ch & 0x80) {
257					ch &= ~0x80;
258					(void)fputs("M-", tp);
259				}
260				if (iscntrl(ch)) {
261					ch ^= 0x40;
262					(void)fputc('^', tp);
263				}
264			}
265			(void)fputc(ch, tp);
266		}
267		(void)fputs(cr, tp);
268		--linecnt;
269	}
270	(void)fprintf(tp, "----%s\n", cr);
271	(void)fclose(fi);
272}
273