comsat.c revision 141918 
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
34#ifndef lint
35static const char copyright[] =
36"@(#) Copyright (c) 1980, 1993\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static char sccsid[] = "@(#)comsat.c	8.1 (Berkeley) 6/4/93";
43#endif
44static const char rcsid[] =
45  "$FreeBSD: head/libexec/comsat/comsat.c 141918 2005-02-14 17:42:58Z stefanf $";
46#endif /* not lint */
47
48#include <sys/param.h>
49#include <sys/socket.h>
50#include <sys/stat.h>
51#include <sys/file.h>
52#include <sys/wait.h>
53
54#include <netinet/in.h>
55
56#include <ctype.h>
57#include <err.h>
58#include <errno.h>
59#include <netdb.h>
60#include <paths.h>
61#include <pwd.h>
62#include <termios.h>
63#include <signal.h>
64#include <stdio.h>
65#include <stdlib.h>
66#include <string.h>
67#include <syslog.h>
68#include <unistd.h>
69#include <utmp.h>
70
71int	debug = 0;
72#define	dsyslog	if (debug) syslog
73
74#define MAXIDLE	120
75
76char	hostname[MAXHOSTNAMELEN];
77struct	utmp *utmp = NULL;
78time_t	lastmsgtime;
79int	nutmp, uf;
80
81void jkfprintf(FILE *, char[], char[], off_t);
82void mailfor(char *);
83void notify(struct utmp *, char[], off_t, int);
84void onalrm(int);
85void reapchildren(int);
86
87int
88main(int argc, char *argv[])
89{
90	struct sockaddr_in from;
91	socklen_t fromlen;
92	int cc;
93	char msgbuf[256];
94
95	/* verify proper invocation */
96	fromlen = sizeof(from);
97	if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0)
98		err(1, "getsockname");
99	openlog("comsat", LOG_PID, LOG_DAEMON);
100	if (chdir(_PATH_MAILDIR)) {
101		syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
102		(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
103		exit(1);
104	}
105	if ((uf = open(_PATH_UTMP, O_RDONLY, 0)) < 0) {
106		syslog(LOG_ERR, "open: %s: %m", _PATH_UTMP);
107		(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
108		exit(1);
109	}
110	(void)time(&lastmsgtime);
111	(void)gethostname(hostname, sizeof(hostname));
112	onalrm(0);
113	(void)signal(SIGALRM, onalrm);
114	(void)signal(SIGTTOU, SIG_IGN);
115	(void)signal(SIGCHLD, reapchildren);
116	for (;;) {
117		cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
118		if (cc <= 0) {
119			if (errno != EINTR)
120				sleep(1);
121			errno = 0;
122			continue;
123		}
124		if (!nutmp)		/* no one has logged in yet */
125			continue;
126		sigblock(sigmask(SIGALRM));
127		msgbuf[cc] = '\0';
128		(void)time(&lastmsgtime);
129		mailfor(msgbuf);
130		sigsetmask(0L);
131	}
132}
133
134void
135reapchildren(int signo)
136{
137	while (wait3(NULL, WNOHANG, NULL) > 0);
138}
139
140void
141onalrm(int signo)
142{
143	static u_int utmpsize;		/* last malloced size for utmp */
144	static u_int utmpmtime;		/* last modification time for utmp */
145	struct stat statbf;
146
147	if (time(NULL) - lastmsgtime >= MAXIDLE)
148		exit(0);
149	(void)alarm((u_int)15);
150	(void)fstat(uf, &statbf);
151	if (statbf.st_mtime > utmpmtime) {
152		utmpmtime = statbf.st_mtime;
153		if (statbf.st_size > utmpsize) {
154			utmpsize = statbf.st_size + 10 * sizeof(struct utmp);
155			if ((utmp = realloc(utmp, utmpsize)) == NULL) {
156				syslog(LOG_ERR, "%s", strerror(errno));
157				exit(1);
158			}
159		}
160		(void)lseek(uf, (off_t)0, SEEK_SET);
161		nutmp = read(uf, utmp, (size_t)statbf.st_size)/sizeof(struct utmp);
162	}
163}
164
165void
166mailfor(char *name)
167{
168	struct utmp *utp = &utmp[nutmp];
169	char *cp;
170	char *file;
171	off_t offset;
172	int folder;
173	char buf[sizeof(_PATH_MAILDIR) + sizeof(utmp[0].ut_name) + 1];
174	char buf2[sizeof(_PATH_MAILDIR) + sizeof(utmp[0].ut_name) + 1];
175
176	if (!(cp = strchr(name, '@')))
177		return;
178	*cp = '\0';
179	offset = strtoll(cp + 1, NULL, 10);
180	if (!(cp = strchr(cp + 1, ':')))
181		file = name;
182	else
183		file = cp + 1;
184	sprintf(buf, "%s/%.*s", _PATH_MAILDIR, (int)sizeof(utmp[0].ut_name),
185	    name);
186	if (*file != '/') {
187		sprintf(buf2, "%s/%.*s", _PATH_MAILDIR,
188		    (int)sizeof(utmp[0].ut_name), file);
189		file = buf2;
190	}
191	folder = strcmp(buf, file);
192	while (--utp >= utmp)
193		if (!strncmp(utp->ut_name, name, sizeof(utmp[0].ut_name)))
194			notify(utp, file, offset, folder);
195}
196
197static char *cr;
198
199void
200notify(struct utmp *utp, char file[], off_t offset, int folder)
201{
202	FILE *tp;
203	struct stat stb;
204	struct termios tio;
205	char tty[20], name[sizeof(utmp[0].ut_name) + 1];
206
207	(void)snprintf(tty, sizeof(tty), "%s%.*s",
208	    _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line);
209	if (strchr(tty + sizeof(_PATH_DEV) - 1, '/')) {
210		/* A slash is an attempt to break security... */
211		syslog(LOG_AUTH | LOG_NOTICE, "'/' in \"%s\"", tty);
212		return;
213	}
214	if (stat(tty, &stb) || !(stb.st_mode & (S_IXUSR | S_IXGRP))) {
215		dsyslog(LOG_DEBUG, "%s: wrong mode on %s", utp->ut_name, tty);
216		return;
217	}
218	dsyslog(LOG_DEBUG, "notify %s on %s\n", utp->ut_name, tty);
219	if (fork())
220		return;
221	(void)signal(SIGALRM, SIG_DFL);
222	(void)alarm((u_int)30);
223	if ((tp = fopen(tty, "w")) == NULL) {
224		dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
225		_exit(1);
226	}
227	(void)tcgetattr(fileno(tp), &tio);
228	cr = ((tio.c_oflag & (OPOST|ONLCR)) == (OPOST|ONLCR)) ?  "\n" : "\n\r";
229	(void)strncpy(name, utp->ut_name, sizeof(utp->ut_name));
230	name[sizeof(name) - 1] = '\0';
231	switch (stb.st_mode & (S_IXUSR | S_IXGRP)) {
232	case S_IXUSR:
233	case (S_IXUSR | S_IXGRP):
234		(void)fprintf(tp,
235		    "%s\007New mail for %s@%.*s\007 has arrived%s%s%s:%s----%s",
236		    cr, name, (int)sizeof(hostname), hostname,
237		    folder ? cr : "", folder ? "to " : "", folder ? file : "",
238		    cr, cr);
239		jkfprintf(tp, name, file, offset);
240		break;
241	case S_IXGRP:
242		(void)fprintf(tp, "\007");
243		(void)fflush(tp);
244		(void)sleep(1);
245		(void)fprintf(tp, "\007");
246		break;
247	default:
248		break;
249	}
250	(void)fclose(tp);
251	_exit(0);
252}
253
254void
255jkfprintf(FILE *tp, char user[], char file[], off_t offset)
256{
257	unsigned char *cp, ch;
258	FILE *fi;
259	int linecnt, charcnt, inheader;
260	struct passwd *p;
261	unsigned char line[BUFSIZ];
262
263	/* Set effective uid to user in case mail drop is on nfs */
264	if ((p = getpwnam(user)) != NULL)
265		(void) setuid(p->pw_uid);
266
267	if ((fi = fopen(file, "r")) == NULL)
268		return;
269
270	(void)fseeko(fi, offset, SEEK_CUR);
271	/*
272	 * Print the first 7 lines or 560 characters of the new mail
273	 * (whichever comes first).  Skip header crap other than
274	 * From, Subject, To, and Date.
275	 */
276	linecnt = 7;
277	charcnt = 560;
278	inheader = 1;
279	while (fgets(line, sizeof(line), fi) != NULL) {
280		if (inheader) {
281			if (line[0] == '\n') {
282				inheader = 0;
283				continue;
284			}
285			if (line[0] == ' ' || line[0] == '\t' ||
286			    (strncmp(line, "From:", 5) &&
287			    strncmp(line, "Subject:", 8)))
288				continue;
289		}
290		if (linecnt <= 0 || charcnt <= 0) {
291			(void)fprintf(tp, "...more...%s", cr);
292			(void)fclose(fi);
293			return;
294		}
295		/* strip weird stuff so can't trojan horse stupid terminals */
296		for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) {
297			/* disable upper controls and enable all other
298			   8bit codes due to lack of locale knowledge
299			 */
300			if (((ch & 0x80) && ch < 0xA0) ||
301			    (!(ch & 0x80) && !isprint(ch) &&
302			     !isspace(ch) && ch != '\a' && ch != '\b')
303			   ) {
304				if (ch & 0x80) {
305					ch &= ~0x80;
306					(void)fputs("M-", tp);
307				}
308				if (iscntrl(ch)) {
309					ch ^= 0x40;
310					(void)fputc('^', tp);
311				}
312			}
313			(void)fputc(ch, tp);
314		}
315		(void)fputs(cr, tp);
316		--linecnt;
317	}
318	(void)fprintf(tp, "----%s\n", cr);
319	(void)fclose(fi);
320}
321