comsat.c revision 18471 
1/*
2 * Copyright (c) 1980, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 *	$Id$
34 */
35
36#ifndef lint
37static char copyright[] =
38"@(#) Copyright (c) 1980, 1993\n\
39	The Regents of the University of California.  All rights reserved.\n";
40#endif /* not lint */
41
42#ifndef lint
43static char sccsid[] = "@(#)comsat.c	8.1 (Berkeley) 6/4/93";
44#endif /* not lint */
45
46#include <sys/param.h>
47#include <sys/socket.h>
48#include <sys/stat.h>
49#include <sys/file.h>
50#include <sys/wait.h>
51
52#include <netinet/in.h>
53
54#include <ctype.h>
55#include <errno.h>
56#include <netdb.h>
57#include <paths.h>
58#include <pwd.h>
59#include <termios.h>
60#include <signal.h>
61#include <stdio.h>
62#include <stdlib.h>
63#include <string.h>
64#include <syslog.h>
65#include <unistd.h>
66#include <utmp.h>
67
68int	debug = 0;
69#define	dsyslog	if (debug) syslog
70
71#define MAXIDLE	120
72
73char	hostname[MAXHOSTNAMELEN];
74struct	utmp *utmp = NULL;
75time_t	lastmsgtime;
76int	nutmp, uf;
77
78void jkfprintf __P((FILE *, char[], char[], off_t));
79void mailfor __P((char *));
80void notify __P((struct utmp *, char[], off_t, int));
81void onalrm __P((int));
82void reapchildren __P((int));
83
84int
85main(argc, argv)
86	int argc;
87	char *argv[];
88{
89	struct sockaddr_in from;
90	register int cc;
91	int fromlen;
92	char msgbuf[256];
93
94	/* verify proper invocation */
95	fromlen = sizeof(from);
96	if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0) {
97		(void)fprintf(stderr,
98		    "comsat: getsockname: %s.\n", strerror(errno));
99		exit(1);
100	}
101	openlog("comsat", LOG_PID, LOG_DAEMON);
102	if (chdir(_PATH_MAILDIR)) {
103		syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
104		(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
105		exit(1);
106	}
107	if ((uf = open(_PATH_UTMP, O_RDONLY, 0)) < 0) {
108		syslog(LOG_ERR, "open: %s: %m", _PATH_UTMP);
109		(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
110		exit(1);
111	}
112	(void)time(&lastmsgtime);
113	(void)gethostname(hostname, sizeof(hostname));
114	onalrm(0);
115	(void)signal(SIGALRM, onalrm);
116	(void)signal(SIGTTOU, SIG_IGN);
117	(void)signal(SIGCHLD, reapchildren);
118	for (;;) {
119		cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
120		if (cc <= 0) {
121			if (errno != EINTR)
122				sleep(1);
123			errno = 0;
124			continue;
125		}
126		if (!nutmp)		/* no one has logged in yet */
127			continue;
128		sigblock(sigmask(SIGALRM));
129		msgbuf[cc] = '\0';
130		(void)time(&lastmsgtime);
131		mailfor(msgbuf);
132		sigsetmask(0L);
133	}
134}
135
136void
137reapchildren(signo)
138	int signo;
139{
140	while (wait3(NULL, WNOHANG, NULL) > 0);
141}
142
143void
144onalrm(signo)
145	int signo;
146{
147	static u_int utmpsize;		/* last malloced size for utmp */
148	static u_int utmpmtime;		/* last modification time for utmp */
149	struct stat statbf;
150
151	if (time(NULL) - lastmsgtime >= MAXIDLE)
152		exit(0);
153	(void)alarm((u_int)15);
154	(void)fstat(uf, &statbf);
155	if (statbf.st_mtime > utmpmtime) {
156		utmpmtime = statbf.st_mtime;
157		if (statbf.st_size > utmpsize) {
158			utmpsize = statbf.st_size + 10 * sizeof(struct utmp);
159			if ((utmp = realloc(utmp, utmpsize)) == NULL) {
160				syslog(LOG_ERR, "%s", strerror(errno));
161				exit(1);
162			}
163		}
164		(void)lseek(uf, (off_t)0, L_SET);
165		nutmp = read(uf, utmp, (int)statbf.st_size)/sizeof(struct utmp);
166	}
167}
168
169void
170mailfor(name)
171	char *name;
172{
173	register struct utmp *utp = &utmp[nutmp];
174	register char *cp;
175	char *file;
176	off_t offset;
177	int folder;
178	char buf[sizeof(_PATH_MAILDIR) + sizeof(utmp[0].ut_name) + 1];
179	char buf2[sizeof(_PATH_MAILDIR) + sizeof(utmp[0].ut_name) + 1];
180
181	if (!(cp = strchr(name, '@')))
182		return;
183	*cp = '\0';
184	offset = atoi(cp + 1);
185	if (!(cp = strchr(cp + 1, ':')))
186		file = name;
187	else
188		file = cp + 1;
189	sprintf(buf, "%s/%.*s", _PATH_MAILDIR, sizeof(utmp[0].ut_name), name);
190	if (*file != '/') {
191		sprintf(buf2, "%s/%.*s", _PATH_MAILDIR, sizeof(utmp[0].ut_name), file);
192		file = buf2;
193	}
194	folder = strcmp(buf, file);
195	while (--utp >= utmp)
196		if (!strncmp(utp->ut_name, name, sizeof(utmp[0].ut_name)))
197			notify(utp, file, offset, folder);
198}
199
200static char *cr;
201
202void
203notify(utp, file, offset, folder)
204	register struct utmp *utp;
205	char file[];
206	off_t offset;
207	int folder;
208{
209	FILE *tp;
210	struct stat stb;
211	struct termios tio;
212	char tty[20], name[sizeof(utmp[0].ut_name) + 1];
213
214	(void)snprintf(tty, sizeof(tty), "%s%.*s",
215	    _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line);
216	if (strchr(tty + sizeof(_PATH_DEV) - 1, '/')) {
217		/* A slash is an attempt to break security... */
218		syslog(LOG_AUTH | LOG_NOTICE, "'/' in \"%s\"", tty);
219		return;
220	}
221	if (stat(tty, &stb) || !(stb.st_mode & S_IEXEC)) {
222		dsyslog(LOG_DEBUG, "%s: wrong mode on %s", utp->ut_name, tty);
223		return;
224	}
225	dsyslog(LOG_DEBUG, "notify %s on %s\n", utp->ut_name, tty);
226	if (fork())
227		return;
228	(void)signal(SIGALRM, SIG_DFL);
229	(void)alarm((u_int)30);
230	if ((tp = fopen(tty, "w")) == NULL) {
231		dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
232		_exit(-1);
233	}
234	(void)tcgetattr(fileno(tp), &tio);
235	cr = ((tio.c_oflag & (OPOST|ONLCR)) == (OPOST|ONLCR)) ?  "\n" : "\n\r";
236	(void)strncpy(name, utp->ut_name, sizeof(utp->ut_name));
237	name[sizeof(name) - 1] = '\0';
238	(void)fprintf(tp, "%s\007New mail for %s@%.*s\007 has arrived%s%s%s:%s----%s",
239	    cr, name, (int)sizeof(hostname), hostname,
240	    folder ? cr : "", folder ? "to " : "", folder ? file : "",
241	    cr, cr);
242	jkfprintf(tp, name, file, offset);
243	(void)fclose(tp);
244	_exit(0);
245}
246
247void
248jkfprintf(tp, user, file, offset)
249	register FILE *tp;
250	char user[];
251	char file[];
252	off_t offset;
253{
254	register char *cp, ch;
255	register FILE *fi;
256	register int linecnt, charcnt, inheader;
257	register struct passwd *p;
258	char line[BUFSIZ];
259
260	/* Set effective uid to user in case mail drop is on nfs */
261	if ((p = getpwnam(user)) != NULL)
262		(void) setuid(p->pw_uid);
263
264	if ((fi = fopen(file, "r")) == NULL)
265		return;
266
267	(void)fseek(fi, offset, L_SET);
268	/*
269	 * Print the first 7 lines or 560 characters of the new mail
270	 * (whichever comes first).  Skip header crap other than
271	 * From, Subject, To, and Date.
272	 */
273	linecnt = 7;
274	charcnt = 560;
275	inheader = 1;
276	while (fgets(line, sizeof(line), fi) != NULL) {
277		if (inheader) {
278			if (line[0] == '\n') {
279				inheader = 0;
280				continue;
281			}
282			if (line[0] == ' ' || line[0] == '\t' ||
283			    strncmp(line, "From:", 5) &&
284			    strncmp(line, "Subject:", 8))
285				continue;
286		}
287		if (linecnt <= 0 || charcnt <= 0) {
288			(void)fprintf(tp, "...more...%s", cr);
289			(void)fclose(fi);
290			return;
291		}
292		/* strip weird stuff so can't trojan horse stupid terminals */
293		for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) {
294			if (!isprint(ch)) {
295				if (ch & 0x80)
296					(void)fputs("M-", tp);
297				ch &= 0177;
298				if (!isprint(ch)) {
299					if (ch == 0177)
300						ch = '?';
301					else
302				ch |= 0x40;
303					(void)fputc('^', tp);
304				}
305			}
306			(void)fputc(ch, tp);
307		}
308		(void)fputs(cr, tp);
309		--linecnt;
310	}
311	(void)fprintf(tp, "----%s\n", cr);
312	(void)fclose(fi);
313}
314