1/*	$NetBSD: comsat.c,v 1.14 1998/07/06 06:47:38 mrg Exp $	*/
2
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. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *	This product includes software developed by the University of
18 *	California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include <sys/cdefs.h>
37#ifndef lint
38__COPYRIGHT("@(#) Copyright (c) 1980, 1993\n\
39	The Regents of the University of California.  All rights reserved.\n");
40#if 0
41static char sccsid[] = "from: @(#)comsat.c	8.1 (Berkeley) 6/4/93";
42#else
43__RCSID("$NetBSD: comsat.c,v 1.14 1998/07/06 06:47:38 mrg Exp $");
44#endif
45#endif /* not lint */
46
47#include <sys/param.h>
48#include <sys/socket.h>
49#include <sys/stat.h>
50#include <sys/file.h>
51#include <sys/wait.h>
52
53#include <netinet/in.h>
54
55#include <ctype.h>
56#include <errno.h>
57#include <netdb.h>
58#include <paths.h>
59#include <pwd.h>
60#include <signal.h>
61#include <stdio.h>
62#include <stdlib.h>
63#include <string.h>
64#include <syslog.h>
65#include <termios.h>
66#include <time.h>
67#include <vis.h>
68#include <unistd.h>
69#include <utmpx.h>
70
71int	logging;
72int	debug = 0;
73#define	dsyslog	if (debug) syslog
74
75#define MAXIDLE	120
76
77char	hostname[MAXHOSTNAMELEN+1];
78struct	utmpx *utmpx = NULL;
79time_t	lastmsgtime;
80int	nutmpx, uf;
81
82void jkfprintf __P((FILE *, char[], off_t));
83void mailfor __P((char *));
84void notify __P((struct utmpx *, off_t));
85void onalrm __P((int));
86void reapchildren __P((int));
87int main __P((int, char *[]));
88
89int
90main(argc, argv)
91	int argc;
92	char *argv[];
93{
94	struct sockaddr_in from;
95	int cc, ch;
96	socklen_t fromlen;
97	char msgbuf[100];
98	sigset_t sigset;
99	extern char *__progname;
100
101	/* verify proper invocation */
102	fromlen = sizeof(from);
103	if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0) {
104		(void)fprintf(stderr,
105		    "comsat: getsockname: %s.\n", strerror(errno));
106		exit(1);
107	}
108
109	openlog("comsat", LOG_PID, LOG_DAEMON);
110	while ((ch = getopt(argc, argv, "l")) != -1)
111		switch (ch) {
112		case 'l':
113			logging = 1;
114			break;
115		default:
116			syslog(LOG_ERR, "usage: %s [-l]", __progname);
117			exit(1);
118		}
119	if (chdir(_PATH_MAILDIR)) {
120		syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
121		(void)recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
122		exit(1);
123	}
124	if ((uf = open(_PATH_UTMPX, O_RDONLY, 0)) < 0) {
125		syslog(LOG_ERR, "open: %s: %m", _PATH_UTMPX);
126		(void)recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
127		exit(1);
128	}
129	(void)time(&lastmsgtime);
130	(void)gethostname(hostname, sizeof(hostname));
131	hostname[sizeof(hostname) - 1] = '\0';
132	onalrm(0);
133	(void)signal(SIGALRM, onalrm);
134	(void)signal(SIGTTOU, SIG_IGN);
135	(void)signal(SIGCHLD, reapchildren);
136	for (;;) {
137		cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
138		if (cc <= 0) {
139			if (errno != EINTR)
140				sleep(1);
141			errno = 0;
142			continue;
143		}
144		if (!nutmpx)		/* no one has logged in yet */
145			continue;
146		sigemptyset(&sigset);
147		sigaddset(&sigset, SIGALRM);
148		sigprocmask(SIG_SETMASK, &sigset, NULL);
149		msgbuf[cc] = '\0';
150		(void)time(&lastmsgtime);
151		mailfor(msgbuf);
152		sigemptyset(&sigset);
153		sigprocmask(SIG_SETMASK, &sigset, NULL);
154	}
155}
156
157void
158reapchildren(signo)
159	int signo;
160{
161
162	while (wait3(NULL, WNOHANG, NULL) > 0);
163}
164
165void
166onalrm(signo)
167	int signo;
168{
169	static u_int utmpxsize;		/* last malloced size for utmpx */
170	static time_t utmpxmtime;	/* last modification time for utmpx */
171	struct stat statbf;
172
173	if (time(NULL) - lastmsgtime >= MAXIDLE)
174		exit(0);
175	(void)alarm((u_int)15);
176	(void)fstat(uf, &statbf);
177	if (statbf.st_mtime > utmpxmtime) {
178		utmpxmtime = statbf.st_mtime;
179		if (statbf.st_size > utmpxsize) {
180			utmpxsize = statbf.st_size + 10 * sizeof(struct utmpx);
181			if ((utmpx = realloc(utmpx, utmpxsize)) == NULL) {
182				syslog(LOG_ERR, "%s", strerror(errno));
183				exit(1);
184			}
185		}
186		/* the first record is just a signature, so it is skipped */
187		(void)lseek(uf, (off_t)sizeof(struct utmpx), SEEK_SET);
188		nutmpx = read(uf, utmpx, statbf.st_size - sizeof(struct utmpx))/sizeof(struct utmpx);
189	}
190}
191
192void
193mailfor(name)
194	char *name;
195{
196	struct utmpx *utp = &utmpx[nutmpx];
197	char *cp;
198	off_t offset;
199
200	if (!(cp = strchr(name, '@')))
201		return;
202	*cp = '\0';
203	offset = atoi(cp + 1);
204	while (--utp >= utmpx)
205		if (utp->ut_type == USER_PROCESS && !strncmp(utp->ut_user, name, sizeof(utp->ut_user)))
206			notify(utp, offset);
207}
208
209static char *cr;
210
211void
212notify(utp, offset)
213	struct utmpx *utp;
214	off_t offset;
215{
216	FILE *tp;
217	struct passwd *p;
218	struct stat stb;
219	struct termios ttybuf;
220	char tty[40], name[sizeof(utp->ut_user) + 1];
221
222	(void)snprintf(tty, sizeof(tty), "%s%.*s",
223	    _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line);
224	if (strchr(tty + sizeof(_PATH_DEV) - 1, '/')) {
225		/* A slash is an attempt to break security... */
226		/*
227		 * XXX but what about something like "/dev/pts/5"
228		 * that we may one day "support". ?
229		 */
230		syslog(LOG_AUTH | LOG_NOTICE, "'/' in \"%s\"", tty);
231		return;
232	}
233	if (stat(tty, &stb) || !(stb.st_mode & S_IEXEC)) {
234		dsyslog(LOG_DEBUG, "%s: wrong mode on %s", utp->ut_user, tty);
235		return;
236	}
237	dsyslog(LOG_DEBUG, "notify %s on %s\n", utp->ut_user, tty);
238	if (fork())
239		return;
240	(void)signal(SIGALRM, SIG_DFL);
241	(void)alarm((u_int)30);
242	if ((tp = fopen(tty, "w")) == NULL) {
243		dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
244		_exit(-1);
245	}
246	(void)tcgetattr(fileno(tp), &ttybuf);
247	cr = (ttybuf.c_oflag & ONLCR) && (ttybuf.c_oflag & OPOST) ?
248	    "\n" : "\n\r";
249	(void)strncpy(name, utp->ut_user, sizeof(utp->ut_user));
250	name[sizeof(name) - 1] = '\0';
251
252	/* Set uid/gid/groups to users in case mail drop is on nfs */
253	if ((p = getpwnam(name)) == NULL ||
254	    initgroups(p->pw_name, p->pw_gid) < 0 ||
255	    setgid(p->pw_gid) < 0 ||
256	    setuid(p->pw_uid) < 0)
257		_exit(-1);
258
259	if (logging)
260		syslog(LOG_INFO, "biff message for %s", name);
261
262	(void)fprintf(tp, "%s\007New mail for %s@%.*s\007 has arrived:%s----%s",
263	    cr, name, (int)sizeof(hostname), hostname, cr, cr);
264	jkfprintf(tp, name, offset);
265	(void)fclose(tp);
266	_exit(0);
267}
268
269void
270jkfprintf(tp, name, offset)
271	FILE *tp;
272	char name[];
273	off_t offset;
274{
275	FILE *fi;
276	int linecnt, charcnt, inheader;
277	char line[BUFSIZ], visline[BUFSIZ*4];
278
279	if ((fi = fopen(name, "r")) == NULL)
280		return;
281
282	(void)fseek(fi, offset, SEEK_SET);
283	/*
284	 * Print the first 7 lines or 560 characters of the new mail
285	 * (whichever comes first).  Skip header crap other than
286	 * From, Subject, To, and Date.
287	 */
288	linecnt = 7;
289	charcnt = 560;
290	inheader = 1;
291	while (fgets(line, sizeof(line), fi) != NULL) {
292		if (inheader) {
293			if (line[0] == '\n') {
294				inheader = 0;
295				continue;
296			}
297			if (line[0] == ' ' || line[0] == '\t' ||
298			    (strncasecmp(line, "From:", 5) &&
299			    strncasecmp(line, "Subject:", 8)))
300				continue;
301		}
302		if (linecnt <= 0 || charcnt <= 0) {
303			(void)fprintf(tp, "...more...%s", cr);
304			(void)fclose(fi);
305			return;
306		}
307		/* strip weird stuff so can't trojan horse stupid terminals */
308		(void)strvis(visline, line, VIS_CSTYLE);
309		fputs(visline, tp);
310		--linecnt;
311	}
312	(void)fprintf(tp, "----%s\n", cr);
313	(void)fclose(fi);
314}
315