1 /* $NetBSD: comsat.c,v 1.42 2010/05/29 23:12:30 dholland 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. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #ifndef lint
34 __COPYRIGHT("@(#) Copyright (c) 1980, 1993\
35 The Regents of the University of California. All rights reserved.");
36 #if 0
37 static char sccsid[] = "from: @(#)comsat.c 8.1 (Berkeley) 6/4/93";
38 #else
39 __RCSID("$NetBSD: comsat.c,v 1.42 2010/05/29 23:12:30 dholland Exp $");
40 #endif
41 #endif /* not lint */
42
43 #include <sys/param.h>
44 #include <sys/socket.h>
45 #include <sys/stat.h>
46 #include <sys/file.h>
47 #include <sys/wait.h>
48
49 #include <netinet/in.h>
50
51 #include <errno.h>
52 #include <netdb.h>
53 #include <paths.h>
54 #include <pwd.h>
55 #include <err.h>
56 #include <signal.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <syslog.h>
61 #include <termios.h>
62 #include <time.h>
63 #include <vis.h>
64 #include <unistd.h>
65 #ifdef SUPPORT_UTMP
66 #include <utmp.h>
67 #endif
68 #ifdef SUPPORT_UTMPX
69 #include <utmpx.h>
70 #endif
71
72 #include "utmpentry.h"
73
74 #if !defined(SUPPORT_UTMP) && !defined(SUPPORT_UTMPX)
75 #error "SUPPORT_UTMP and/or SUPPORT_UTMPX must be defined"
76 #endif
77
78 #define dsyslog if (debug) syslog
79
80 #define MAXIDLE 120
81
82 static int logging;
83 static int debug;
84 static char hostname[MAXHOSTNAMELEN + 1];
85 static int nutmp;
86 static struct utmpentry *utmp = NULL;
87 static time_t lastmsgtime;
88 static volatile sig_atomic_t needupdate;
89
90 int main(int, char *[]);
91 static void jkfprintf(FILE *, const char *, off_t, const char *);
92 static void mailfor(char *);
93 static void notify(const struct utmpentry *, off_t);
94 static void onalrm(int);
95 static void checkutmp(void);
96
97 int
main(int argc,char * argv[])98 main(int argc, char *argv[])
99 {
100 struct sockaddr_storage from;
101 int cc, ch;
102 socklen_t fromlen;
103 char msgbuf[100];
104 sigset_t nsigset, osigset;
105
106 /* verify proper invocation */
107 fromlen = sizeof(from);
108 if (getsockname(0, (struct sockaddr *)(void *)&from, &fromlen) == -1)
109 err(1, "getsockname");
110
111 openlog("comsat", LOG_PID, LOG_DAEMON);
112 while ((ch = getopt(argc, argv, "l")) != -1)
113 switch (ch) {
114 case 'l':
115 logging = 1;
116 break;
117 default:
118 syslog(LOG_ERR, "Usage: %s [-l]", getprogname());
119 exit(1);
120 }
121 if (chdir(_PATH_MAILDIR) == -1) {
122 syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
123 (void)recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
124 exit(1);
125 }
126 (void)time(&lastmsgtime);
127 (void)gethostname(hostname, sizeof(hostname));
128 hostname[sizeof(hostname) - 1] = '\0';
129 (void)signal(SIGALRM, onalrm);
130 (void)signal(SIGTTOU, SIG_IGN);
131 (void)signal(SIGCHLD, SIG_IGN);
132 (void)sigemptyset(&nsigset);
133 (void)sigaddset(&nsigset, SIGALRM);
134 if (sigprocmask(SIG_SETMASK, NULL, &osigset) == -1) {
135 syslog(LOG_ERR, "sigprocmask get failed (%m)");
136 exit(1);
137 }
138 needupdate = 1;
139 for (;;) {
140 cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
141 if (cc <= 0) {
142 if (errno != EINTR)
143 sleep(1);
144 errno = 0;
145 checkutmp();
146 continue;
147 } else
148 checkutmp();
149 if (!nutmp) /* no one has logged in yet */
150 continue;
151 if (sigprocmask(SIG_SETMASK, &nsigset, NULL) == -1) {
152 syslog(LOG_ERR, "sigprocmask set failed (%m)");
153 exit(1);
154 }
155 msgbuf[cc] = '\0';
156 (void)time(&lastmsgtime);
157 mailfor(msgbuf);
158 if (sigprocmask(SIG_SETMASK, &osigset, NULL) == -1) {
159 syslog(LOG_ERR, "sigprocmask restore failed (%m)");
160 exit(1);
161 }
162 }
163 }
164
165 static void
166 /*ARGSUSED*/
onalrm(int signo)167 onalrm(int signo)
168 {
169 needupdate = 1;
170 }
171
172 static void
checkutmp(void)173 checkutmp(void)
174 {
175 if (!needupdate)
176 return;
177 needupdate = 0;
178
179 if (time(NULL) - lastmsgtime >= MAXIDLE)
180 exit(0);
181 (void)alarm((u_int)15);
182 nutmp = getutentries(NULL, &utmp);
183 }
184
185 static void
mailfor(char * name)186 mailfor(char *name)
187 {
188 struct utmpentry *ep;
189 char *cp, *fn;
190 off_t offset;
191 intmax_t val;
192
193 if (!(cp = strchr(name, '@')))
194 return;
195 *cp = '\0';
196 errno = 0;
197 offset = val = strtoimax(cp + 1, &fn, 10);
198 if (errno == ERANGE || offset != val)
199 return;
200 if (fn && *fn && *fn != '\n') {
201 /*
202 * Procmail sends messages to comsat with a trailing colon
203 * and a pathname to the folder where the new message was
204 * deposited. Since we can't reliably open only regular
205 * files, we need to ignore these. With one exception:
206 * if it mentions the user's system mailbox.
207 */
208 char maildir[MAXPATHLEN];
209 int l = snprintf(maildir, sizeof(maildir), ":%s/%s",
210 _PATH_MAILDIR, name);
211 if (l >= (int)sizeof(maildir) || strcmp(maildir, fn) != 0)
212 return;
213 }
214 for (ep = utmp; ep != NULL; ep = ep->next)
215 if (strcmp(ep->name, name) == 0)
216 notify(ep, offset);
217 }
218
219 static void
notify(const struct utmpentry * ep,off_t offset)220 notify(const struct utmpentry *ep, off_t offset)
221 {
222 FILE *tp;
223 struct passwd *p;
224 struct stat stb;
225 struct termios ttybuf;
226 char tty[sizeof(_PATH_DEV) + sizeof(ep->line) + 1];
227 const char *cr = ep->line;
228
229 if (strncmp(cr, "pts/", 4) == 0)
230 cr += 4;
231 if (strchr(cr, '/')) {
232 /* A slash is an attempt to break security... */
233 syslog(LOG_AUTH | LOG_NOTICE, "Unexpected `/' in `%s'",
234 ep->line);
235 return;
236 }
237 (void)snprintf(tty, sizeof(tty), "%s%s", _PATH_DEV, ep->line);
238 if (stat(tty, &stb) == -1 || !(stb.st_mode & S_IEXEC)) {
239 dsyslog(LOG_DEBUG, "%s: wrong mode on %s", ep->name, tty);
240 return;
241 }
242 dsyslog(LOG_DEBUG, "notify %s on %s", ep->name, tty);
243 switch (fork()) {
244 case -1:
245 syslog(LOG_NOTICE, "fork failed (%m)");
246 return;
247 case 0:
248 break;
249 default:
250 return;
251 }
252 (void)signal(SIGALRM, SIG_DFL);
253 (void)alarm(30);
254 if ((tp = fopen(tty, "w")) == NULL) {
255 dsyslog(LOG_ERR, "open `%s' (%s)", tty, strerror(errno));
256 _exit(1);
257 }
258 if (tcgetattr(fileno(tp), &ttybuf) == -1) {
259 dsyslog(LOG_ERR, "tcgetattr `%s' (%s)", tty, strerror(errno));
260 _exit(1);
261 }
262 cr = (ttybuf.c_oflag & ONLCR) && (ttybuf.c_oflag & OPOST) ?
263 "\n" : "\n\r";
264 /* Set uid/gid/groups to user's in case mail drop is on nfs */
265 if ((p = getpwnam(ep->name)) == NULL ||
266 initgroups(p->pw_name, p->pw_gid) == -1 ||
267 setgid(p->pw_gid) == -1 ||
268 setuid(p->pw_uid) == -1)
269 _exit(1);
270
271 if (logging)
272 syslog(LOG_INFO, "biff message for %s", ep->name);
273
274 (void)fprintf(tp, "%s\007New mail for %s@%.*s\007 has arrived:%s----%s",
275 cr, ep->name, (int)sizeof(hostname), hostname, cr, cr);
276 jkfprintf(tp, ep->name, offset, cr);
277 (void)fclose(tp);
278 _exit(0);
279 }
280
281 static void
jkfprintf(FILE * tp,const char * name,off_t offset,const char * cr)282 jkfprintf(FILE *tp, const char *name, off_t offset, const char *cr)
283 {
284 FILE *fi;
285 int linecnt, charcnt, inheader;
286 char line[BUFSIZ], visline[BUFSIZ * 4 + 1], *nl;
287
288 if ((fi = fopen(name, "r")) == NULL)
289 return;
290
291 (void)fseeko(fi, offset, SEEK_SET);
292 /*
293 * Print the first 7 lines or 560 characters of the new mail
294 * (whichever comes first). Skip header crap other than
295 * From and Subject.
296 */
297 linecnt = 7;
298 charcnt = 560;
299 inheader = 1;
300 while (fgets(line, sizeof(line), fi) != NULL) {
301 line[sizeof(line) - 1] = '\0';
302 if (inheader) {
303 if (line[0] == '\n') {
304 inheader = 0;
305 continue;
306 }
307 if (line[0] == ' ' || line[0] == '\t' ||
308 (strncasecmp(line, "From:", 5) &&
309 strncasecmp(line, "Subject:", 8)))
310 continue;
311 }
312 if (strncmp(line, "From ", 5) == 0) {
313 (void)fprintf(tp, "----%s", cr);
314 (void)fclose(fi);
315 return;
316 }
317 if (linecnt <= 0 || charcnt <= 0) {
318 (void)fprintf(tp, "...more...%s", cr);
319 (void)fclose(fi);
320 return;
321 }
322 if ((nl = strchr(line, '\n')) != NULL)
323 *nl = '\0';
324 /* strip weird stuff so can't trojan horse stupid terminals */
325 (void)strvis(visline, line, VIS_CSTYLE);
326 (void)fputs(visline, tp);
327 (void)fputs(cr, tp);
328 --linecnt;
329 }
330 (void)fprintf(tp, "----%s\n", cr);
331 (void)fclose(fi);
332 }
333