xref: /dragonfly/libexec/comsat/comsat.c (revision 60233e58) 
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  * @(#)comsat.c	8.1 (Berkeley) 6/4/93
34  * $FreeBSD: src/libexec/comsat/comsat.c,v 1.17 2005/02/14 17:42:56 stefanf Exp $
35  * $DragonFly: src/libexec/comsat/comsat.c,v 1.6 2005/05/03 17:39:03 liamfoy Exp $
36  */
37 
38 #include <sys/param.h>
39 #include <sys/socket.h>
40 #include <sys/stat.h>
41 #include <sys/file.h>
42 #include <sys/wait.h>
43 
44 #include <netinet/in.h>
45 
46 #include <ctype.h>
47 #include <err.h>
48 #include <errno.h>
49 #include <netdb.h>
50 #include <paths.h>
51 #include <pwd.h>
52 #include <termios.h>
53 #include <signal.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <sysexits.h>
58 #include <syslog.h>
59 #include <unistd.h>
60 #include <utmp.h>
61 
62 int	debug = 0;
63 #define	dsyslog	if (debug) syslog
64 
65 #define MAXIDLE	120
66 
67 char	hostname[MAXHOSTNAMELEN];
68 struct	utmp *utmp = NULL;
69 time_t	lastmsgtime;
70 int	nutmp, uf;
71 
72 void jkfprintf (FILE *, const char *, const char *, off_t);
73 void mailfor (char *);
74 void notify (struct utmp *, char *, off_t, int);
75 void onalrm (int);
76 void reapchildren (int);
77 
78 int
79 main(int argc __unused, char **argv __unused)
80 {
81 	struct sockaddr_in from;
82 	socklen_t fromlen;
83 	int cc;
84 	char msgbuf[256];
85 
86 	/* verify proper invocation */
87 	fromlen = sizeof(from);
88 	if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0)
89 		err(1, "getsockname");
90 	openlog("comsat", LOG_PID, LOG_DAEMON);
91 	if (chdir(_PATH_MAILDIR)) {
92 		syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
93 		recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
94 		exit(1);
95 	}
96 	if ((uf = open(_PATH_UTMP, O_RDONLY, 0)) < 0) {
97 		syslog(LOG_ERR, "open: %s: %m", _PATH_UTMP);
98 		recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
99 		exit(1);
100 	}
101 	time(&lastmsgtime);
102 	gethostname(hostname, sizeof(hostname));
103 	onalrm(0);
104 	signal(SIGALRM, onalrm);
105 	signal(SIGTTOU, SIG_IGN);
106 	signal(SIGCHLD, reapchildren);
107 	for (;;) {
108 		cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
109 		if (cc <= 0) {
110 			if (errno != EINTR)
111 				sleep(1);
112 			errno = 0;
113 			continue;
114 		}
115 		if (!nutmp)		/* no one has logged in yet */
116 			continue;
117 		sigblock(sigmask(SIGALRM));
118 		msgbuf[cc] = '\0';
119 		time(&lastmsgtime);
120 		mailfor(msgbuf);
121 		sigsetmask(0L);
122 	}
123 }
124 
125 void
126 reapchildren(int signo __unused)
127 {
128 	while (wait3(NULL, WNOHANG, NULL) > 0);
129 }
130 
131 void
132 onalrm(int signo __unused)
133 {
134 	static u_int utmpsize;		/* last malloced size for utmp */
135 	static time_t utmpmtime;	/* last modification time for utmp */
136 	struct stat statbf;
137 
138 	if (time(NULL) - lastmsgtime >= MAXIDLE)
139 		exit(EX_OK);
140 	alarm((u_int)15);
141 	fstat(uf, &statbf);
142 	if (statbf.st_mtime > utmpmtime) {
143 		utmpmtime = statbf.st_mtime;
144 		if (statbf.st_size > utmpsize) {
145 			utmpsize = statbf.st_size + 10 * sizeof(struct utmp);
146 			if ((utmp = realloc(utmp, utmpsize)) == NULL) {
147 				syslog(LOG_ERR, "realloc: %m");
148 				exit(1);
149 			}
150 		}
151 		lseek(uf, (off_t)0, SEEK_SET);
152 		nutmp = read(uf, utmp, (size_t)statbf.st_size)/sizeof(struct utmp);
153 	}
154 }
155 
156 void
157 mailfor(char *name)
158 {
159 	struct utmp *utp = &utmp[nutmp];
160 	char *cp;
161 	char *file;
162 	off_t offset;
163 	int folder;
164 	char buf[sizeof(_PATH_MAILDIR) + sizeof(utmp[0].ut_name) + 1];
165 	char buf2[sizeof(_PATH_MAILDIR) + sizeof(utmp[0].ut_name) + 1];
166 
167 	if (!(cp = strchr(name, '@')))
168 		return;
169 	*cp = '\0';
170 	offset = strtoll(cp + 1, NULL, 10);
171 	if (!(cp = strchr(cp + 1, ':')))
172 		file = name;
173 	else
174 		file = cp + 1;
175 	sprintf(buf, "%s/%.*s", _PATH_MAILDIR, (int)sizeof(utmp[0].ut_name),
176 	    name);
177 	if (*file != '/') {
178 		sprintf(buf2, "%s/%.*s", _PATH_MAILDIR,
179 		    (int)sizeof(utmp[0].ut_name), file);
180 		file = buf2;
181 	}
182 	folder = strcmp(buf, file);
183 	while (--utp >= utmp)
184 		if (!strncmp(utp->ut_name, name, sizeof(utmp[0].ut_name)))
185 			notify(utp, file, offset, folder);
186 }
187 
188 static const char *cr;
189 
190 void
191 notify(struct utmp *utp, char *file, off_t offset, int folder)
192 {
193 	FILE *tp;
194 	struct stat stb;
195 	struct termios tio;
196 	char tty[20], name[sizeof(utmp[0].ut_name) + 1];
197 
198 	snprintf(tty, sizeof(tty), "%s%.*s",
199 	    _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line);
200 	if (strchr(tty + sizeof(_PATH_DEV) - 1, '/')) {
201 		/* A slash is an attempt to break security... */
202 		syslog(LOG_AUTH | LOG_NOTICE, "'/' in \"%s\"", tty);
203 		return;
204 	}
205 	if (stat(tty, &stb) || !(stb.st_mode & (S_IXUSR | S_IXGRP))) {
206 		dsyslog(LOG_DEBUG, "%s: wrong mode on %s", utp->ut_name, tty);
207 		return;
208 	}
209 	dsyslog(LOG_DEBUG, "notify %s on %s\n", utp->ut_name, tty);
210 	if (fork())
211 		return;
212 	signal(SIGALRM, SIG_DFL);
213 	alarm((u_int)30);
214 	if ((tp = fopen(tty, "w")) == NULL) {
215 		dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
216 		_exit(1);
217 	}
218 	tcgetattr(fileno(tp), &tio);
219 	cr = ((tio.c_oflag & (OPOST|ONLCR)) == (OPOST|ONLCR)) ?  "\n" : "\n\r";
220 	strncpy(name, utp->ut_name, sizeof(utp->ut_name));
221 	name[sizeof(name) - 1] = '\0';
222 	switch (stb.st_mode & (S_IXUSR | S_IXGRP)) {
223 	case S_IXUSR:
224 	case (S_IXUSR | S_IXGRP):
225 		fprintf(tp,
226 		    "%s\007New mail for %s@%.*s\007 has arrived%s%s%s:%s----%s",
227 		    cr, name, (int)sizeof(hostname), hostname,
228 		    folder ? cr : "", folder ? "to " : "", folder ? file : "",
229 		    cr, cr);
230 		jkfprintf(tp, name, file, offset);
231 		break;
232 	case S_IXGRP:
233 		fprintf(tp, "\007");
234 		fflush(tp);
235 		sleep(1);
236 		fprintf(tp, "\007");
237 		break;
238 	default:
239 		break;
240 	}
241 	fclose(tp);
242 	_exit(EX_OK);
243 }
244 
245 void
246 jkfprintf(FILE *tp, const char *user, const char *file, off_t offset)
247 {
248 	unsigned char *cp, ch;
249 	FILE *fi;
250 	int linecnt, charcnt, inheader;
251 	struct passwd *p;
252 	unsigned char line[BUFSIZ];
253 
254 	/* Set effective uid to user in case mail drop is on nfs */
255 	if ((p = getpwnam(user)) != NULL)
256 		setuid(p->pw_uid);
257 
258 	if ((fi = fopen(file, "r")) == NULL)
259 		return;
260 
261 	fseeko(fi, offset, SEEK_SET);
262 	/*
263 	 * Print the first 7 lines or 560 characters of the new mail
264 	 * (whichever comes first).  Skip header crap other than
265 	 * From, Subject, To, and Date.
266 	 */
267 	linecnt = 7;
268 	charcnt = 560;
269 	inheader = 1;
270 	while (fgets(line, sizeof(line), fi) != NULL) {
271 		if (inheader) {
272 			if (line[0] == '\n') {
273 				inheader = 0;
274 				continue;
275 			}
276 			if (line[0] == ' ' || line[0] == '\t' ||
277 			    (strncmp(line, "From:", 5) &&
278 			    strncmp(line, "Subject:", 8)))
279 				continue;
280 		}
281 		if (linecnt <= 0 || charcnt <= 0) {
282 			fprintf(tp, "...more...%s", cr);
283 			fclose(fi);
284 			return;
285 		}
286 		/* strip weird stuff so can't trojan horse stupid terminals */
287 		for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) {
288 			/* disable upper controls and enable all other
289 			   8bit codes due to lack of locale knowledge
290 			 */
291 			if (((ch & 0x80) && ch < 0xA0) ||
292 			    (!(ch & 0x80) && !isprint(ch) &&
293 			     !isspace(ch) && ch != '\a' && ch != '\b')
294 			   ) {
295 				if (ch & 0x80) {
296 					ch &= ~0x80;
297 					fputs("M-", tp);
298 				}
299 				if (iscntrl(ch)) {
300 					ch ^= 0x40;
301 					fputc('^', tp);
302 				}
303 			}
304 			fputc(ch, tp);
305 		}
306 		fputs(cr, tp);
307 		--linecnt;
308 	}
309 	fprintf(tp, "----%s\n", cr);
310 	fclose(fi);
311 }
312