xref: /freebsd/libexec/comsat/comsat.c (revision 2a664c03e55254b0f3b32dcdfc78179c0a57a8d2)
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
35 static 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
42 static char sccsid[] = "@(#)comsat.c	8.1 (Berkeley) 6/4/93";
43 #endif
44 static const char rcsid[] =
45   "$FreeBSD$";
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 <utmpx.h>
70 
71 static int	debug = 0;
72 #define	dsyslog	if (debug) syslog
73 
74 #define MAXIDLE	120
75 
76 static char	hostname[MAXHOSTNAMELEN];
77 
78 static void	jkfprintf(FILE *, char[], char[], off_t);
79 static void	mailfor(char *);
80 static void	notify(struct utmpx *, char[], off_t, int);
81 static void	reapchildren(int);
82 
83 int
84 main(int argc __unused, char *argv[] __unused)
85 {
86 	struct sockaddr_in from;
87 	socklen_t fromlen;
88 	int cc;
89 	char msgbuf[256];
90 
91 	/* verify proper invocation */
92 	fromlen = sizeof(from);
93 	if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0)
94 		err(1, "getsockname");
95 	openlog("comsat", LOG_PID, LOG_DAEMON);
96 	if (chdir(_PATH_MAILDIR)) {
97 		syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
98 		(void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
99 		exit(1);
100 	}
101 	(void)gethostname(hostname, sizeof(hostname));
102 	(void)signal(SIGTTOU, SIG_IGN);
103 	(void)signal(SIGCHLD, reapchildren);
104 	for (;;) {
105 		cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
106 		if (cc <= 0) {
107 			if (errno != EINTR)
108 				sleep(1);
109 			errno = 0;
110 			continue;
111 		}
112 		msgbuf[cc] = '\0';
113 		mailfor(msgbuf);
114 		sigsetmask(0L);
115 	}
116 }
117 
118 static void
119 reapchildren(int signo __unused)
120 {
121 	while (wait3(NULL, WNOHANG, NULL) > 0);
122 }
123 
124 static void
125 mailfor(char *name)
126 {
127 	struct utmpx *utp;
128 	char *cp;
129 	char *file;
130 	off_t offset;
131 	int folder;
132 	char buf[sizeof(_PATH_MAILDIR) + sizeof(utp->ut_user) + 1];
133 	char buf2[sizeof(_PATH_MAILDIR) + sizeof(utp->ut_user) + 1];
134 
135 	if (!(cp = strchr(name, '@')))
136 		return;
137 	*cp = '\0';
138 	offset = strtoll(cp + 1, NULL, 10);
139 	if (!(cp = strchr(cp + 1, ':')))
140 		file = name;
141 	else
142 		file = cp + 1;
143 	sprintf(buf, "%s/%.*s", _PATH_MAILDIR, (int)sizeof(utp->ut_user),
144 	    name);
145 	if (*file != '/') {
146 		sprintf(buf2, "%s/%.*s", _PATH_MAILDIR,
147 		    (int)sizeof(utp->ut_user), file);
148 		file = buf2;
149 	}
150 	folder = strcmp(buf, file);
151 	setutxent();
152 	while ((utp = getutxent()) != NULL)
153 		if (utp->ut_type == USER_PROCESS && !strcmp(utp->ut_user, name))
154 			notify(utp, file, offset, folder);
155 	endutxent();
156 }
157 
158 static const char *cr;
159 
160 static void
161 notify(struct utmpx *utp, char file[], off_t offset, int folder)
162 {
163 	FILE *tp;
164 	struct stat stb;
165 	struct termios tio;
166 	char tty[20];
167 	const char *s = utp->ut_line;
168 
169 	if (strncmp(s, "pts/", 4) == 0)
170 		s += 4;
171 	if (strchr(s, '/')) {
172 		/* A slash is an attempt to break security... */
173 		syslog(LOG_AUTH | LOG_NOTICE, "Unexpected `/' in `%s'",
174 		    utp->ut_line);
175 		return;
176 	}
177 	(void)snprintf(tty, sizeof(tty), "%s%.*s",
178 	    _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line);
179 	if (stat(tty, &stb) == -1 || !(stb.st_mode & (S_IXUSR | S_IXGRP))) {
180 		dsyslog(LOG_DEBUG, "%s: wrong mode on %s", utp->ut_user, tty);
181 		return;
182 	}
183 	dsyslog(LOG_DEBUG, "notify %s on %s", utp->ut_user, tty);
184 	switch (fork()) {
185 	case -1:
186 		syslog(LOG_NOTICE, "fork failed (%m)");
187 		return;
188 	case 0:
189 		break;
190 	default:
191 		return;
192 	}
193 	if ((tp = fopen(tty, "w")) == NULL) {
194 		dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
195 		_exit(1);
196 	}
197 	(void)tcgetattr(fileno(tp), &tio);
198 	cr = ((tio.c_oflag & (OPOST|ONLCR)) == (OPOST|ONLCR)) ?  "\n" : "\n\r";
199 	switch (stb.st_mode & (S_IXUSR | S_IXGRP)) {
200 	case S_IXUSR:
201 	case (S_IXUSR | S_IXGRP):
202 		(void)fprintf(tp,
203 		    "%s\007New mail for %s@%.*s\007 has arrived%s%s%s:%s----%s",
204 		    cr, utp->ut_user, (int)sizeof(hostname), hostname,
205 		    folder ? cr : "", folder ? "to " : "", folder ? file : "",
206 		    cr, cr);
207 		jkfprintf(tp, utp->ut_user, file, offset);
208 		break;
209 	case S_IXGRP:
210 		(void)fprintf(tp, "\007");
211 		(void)fflush(tp);
212 		(void)sleep(1);
213 		(void)fprintf(tp, "\007");
214 		break;
215 	default:
216 		break;
217 	}
218 	(void)fclose(tp);
219 	_exit(0);
220 }
221 
222 static void
223 jkfprintf(FILE *tp, char user[], char file[], off_t offset)
224 {
225 	unsigned char *cp, ch;
226 	FILE *fi;
227 	int linecnt, charcnt, inheader;
228 	struct passwd *p;
229 	unsigned char line[BUFSIZ];
230 
231 	/* Set effective uid to user in case mail drop is on nfs */
232 	if ((p = getpwnam(user)) != NULL)
233 		(void) setuid(p->pw_uid);
234 
235 	if ((fi = fopen(file, "r")) == NULL)
236 		return;
237 
238 	(void)fseeko(fi, offset, SEEK_CUR);
239 	/*
240 	 * Print the first 7 lines or 560 characters of the new mail
241 	 * (whichever comes first).  Skip header crap other than
242 	 * From, Subject, To, and Date.
243 	 */
244 	linecnt = 7;
245 	charcnt = 560;
246 	inheader = 1;
247 	while (fgets(line, sizeof(line), fi) != NULL) {
248 		if (inheader) {
249 			if (line[0] == '\n') {
250 				inheader = 0;
251 				continue;
252 			}
253 			if (line[0] == ' ' || line[0] == '\t' ||
254 			    (strncmp(line, "From:", 5) &&
255 			    strncmp(line, "Subject:", 8)))
256 				continue;
257 		}
258 		if (linecnt <= 0 || charcnt <= 0) {
259 			(void)fprintf(tp, "...more...%s", cr);
260 			(void)fclose(fi);
261 			return;
262 		}
263 		/* strip weird stuff so can't trojan horse stupid terminals */
264 		for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) {
265 			/* disable upper controls and enable all other
266 			   8bit codes due to lack of locale knowledge
267 			 */
268 			if (((ch & 0x80) && ch < 0xA0) ||
269 			    (!(ch & 0x80) && !isprint(ch) &&
270 			     !isspace(ch) && ch != '\a' && ch != '\b')
271 			   ) {
272 				if (ch & 0x80) {
273 					ch &= ~0x80;
274 					(void)fputs("M-", tp);
275 				}
276 				if (iscntrl(ch)) {
277 					ch ^= 0x40;
278 					(void)fputc('^', tp);
279 				}
280 			}
281 			(void)fputc(ch, tp);
282 		}
283 		(void)fputs(cr, tp);
284 		--linecnt;
285 	}
286 	(void)fprintf(tp, "----%s\n", cr);
287 	(void)fclose(fi);
288 }
289