1 /*
2 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
3 * Use is subject to license terms.
4 */
5
6 /*
7 * Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T
8 * All Rights Reserved.
9 */
10
11 /*
12 * Copyright (c) 1980 Regents of the University of California.
13 * All rights reserved.
14 *
15 * Redistribution and use in source and binary forms are permitted provided
16 * that: (1) source distributions retain this entire copyright notice and
17 * comment, and (2) distributions including binaries display the following
18 * acknowledgement: ``This product includes software developed by the
19 * University of California, Berkeley and its contributors'' in the
20 * documentation or other materials provided with the distribution and in
21 * all advertising materials mentioning features or use of this software.
22 * Neither the name of the University nor the names of its contributors may
23 * be used to endorse or promote products derived from this software without
24 * specific prior written permission.
25 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
26 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
27 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
28 */
29
30 #pragma ident "%Z%%M% %I% %E% SMI"
31
32
33 #include <sys/types.h>
34 #include <sys/socket.h>
35 #include <sys/stat.h>
36 #include <sys/wait.h>
37 #include <sys/file.h>
38 #include <fcntl.h>
39 #include <ctype.h>
40 #include <string.h>
41
42 #include <netinet/in.h>
43
44 #include <stdio.h>
45 #include <sys/ttold.h>
46 #include <utmpx.h>
47 #include <signal.h>
48 #include <errno.h>
49 #include <sys/param.h> /* for MAXHOSTNAMELEN */
50 #include <netdb.h>
51 #include <syslog.h>
52 #include <sys/ioctl.h>
53 #include <pwd.h>
54
55 /*
56 * comsat
57 */
58
59
60 #ifndef UTMPX_FILE
61 #define UTMPX_FILE "/etc/utmpx"
62 #endif /* UTMPX_FILE */
63
64 int debug = 0;
65 #define dsyslog if (debug) syslog
66
67 struct sockaddr_in sin = { AF_INET };
68
69 char hostname[MAXHOSTNAMELEN];
70 struct utmpx *utmp = NULL;
71 int nutmp;
72 int uf;
73 unsigned utmpmtime = 0; /* last modification time for utmp */
74 unsigned utmpsize = 0; /* last malloced size for utmp */
75 time_t lastmsgtime;
76
77 #ifndef SYSV
78 int reapchildren();
79 #else
80
81 #define rindex strrchr
82 #define index strchr
83 #define signal(s, f) sigset((s), (f))
84
85 #ifndef sigmask
86 #define sigmask(m) (1 << ((m)-1))
87 #endif
88
89 #define set2mask(setp) ((setp)->__sigbits[0])
90 #define mask2set(mask, setp) \
91 ((mask) == -1 ? sigfillset(setp) : (((setp)->__sigbits[0]) = (mask)))
92
93 static int
sigsetmask(mask)94 sigsetmask(mask)
95 int mask;
96 {
97 sigset_t oset;
98 sigset_t nset;
99
100 (void) sigprocmask(0, (sigset_t *)0, &nset);
101 mask2set(mask, &nset);
102 (void) sigprocmask(SIG_SETMASK, &nset, &oset);
103 return (set2mask(&oset));
104 }
105
106 static int
sigblock(mask)107 sigblock(mask)
108 int mask;
109 {
110 sigset_t oset;
111 sigset_t nset;
112
113 (void) sigprocmask(0, (sigset_t *)0, &nset);
114 mask2set(mask, &nset);
115 (void) sigprocmask(SIG_BLOCK, &nset, &oset);
116 return (set2mask(&oset));
117 }
118
119 #endif /* SYSV */
120
121
122 #define MAXIDLE 120
123 #define NAMLEN (sizeof (uts[0].ut_name) + 1)
124
125 void jkfprintf(FILE *tp, char *name, int mbox, int offset);
126 void mailfor(char *name);
127 void notify(struct utmpx *utp, int offset);
128 void onalrm(int sig);
129
130 int
main(argc,argv)131 main(argc, argv)
132 int argc;
133 char *argv[];
134 {
135 register int cc;
136 char buf[BUFSIZ];
137 char msgbuf[100];
138 struct sockaddr_in from;
139 socklen_t fromlen;
140 int c;
141 extern int optind;
142 extern int getopt();
143 extern char *optarg;
144
145 openlog("comsat", 0, LOG_DAEMON);
146
147 while ((c = getopt(argc, argv, "d")) != -1) {
148 switch ((char)c) {
149 case'd':
150 debug++;
151 break;
152 default:
153 syslog(LOG_ERR, "invalid argument %s", argv[optind]);
154 exit(1);
155 }
156 }
157
158 /* verify proper invocation */
159 fromlen = (socklen_t)sizeof (from);
160 if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0) {
161 fprintf(stderr, "%s: ", argv[0]);
162 perror("getsockname");
163 _exit(1);
164 }
165
166 #ifdef SYSV
167 chdir("/var/mail");
168 #else
169 chdir("/var/spool/mail");
170 #endif /* SYSV */
171 if ((uf = open(UTMPX_FILE, 0)) < 0) {
172 syslog(LOG_ERR, "%s: %m", UTMPX_FILE);
173 (void) recv(0, msgbuf, sizeof (msgbuf) - 1, 0);
174 exit(1);
175 }
176 (void) time(&lastmsgtime);
177 (void) gethostname(hostname, sizeof (hostname));
178 onalrm(0);
179 (void) signal(SIGALRM, onalrm);
180 (void) signal(SIGTTOU, SIG_IGN);
181 #ifndef SYSV
182 (void) signal(SIGCHLD, reapchildren);
183 #else
184 (void) signal(SIGCHLD, SIG_IGN); /* no zombies */
185 #endif /* SYSV */
186 for (;;) {
187 cc = recv(0, msgbuf, sizeof (msgbuf) - 1, 0);
188 if (cc <= 0) {
189 if (errno != EINTR)
190 sleep(1);
191 errno = 0;
192 continue;
193 }
194 if (nutmp == 0) /* no users (yet) */
195 continue;
196 sigblock(sigmask(SIGALRM));
197 msgbuf[cc] = 0;
198 (void) time(&lastmsgtime);
199 mailfor(msgbuf);
200 sigsetmask(0);
201 }
202 }
203
204 #ifndef SYSV
reapchildren()205 reapchildren()
206 {
207
208 while (wait3((struct wait *)0, WNOHANG, (struct rusage *)0) > 0)
209 ;
210 }
211 #endif /* SYSV */
212
213 /* ARGSUSED */
214 void
onalrm(int sig)215 onalrm(int sig)
216 {
217 struct stat statbf;
218 time_t now;
219
220 (void) time(&now);
221 if ((ulong_t)now - (ulong_t)lastmsgtime >= MAXIDLE)
222 exit(0);
223 dsyslog(LOG_DEBUG, "alarm\n");
224 alarm(15);
225 fstat(uf, &statbf);
226 if (statbf.st_mtime > utmpmtime) {
227 dsyslog(LOG_DEBUG, " changed\n");
228 utmpmtime = statbf.st_mtime;
229 if (statbf.st_size > utmpsize) {
230 utmpsize = statbf.st_size + 10 * sizeof (struct utmpx);
231 if (utmp)
232 utmp = (struct utmpx *)realloc(utmp, utmpsize);
233 else
234 utmp = (struct utmpx *)malloc(utmpsize);
235 if (! utmp) {
236 dsyslog(LOG_DEBUG, "malloc failed\n");
237 exit(1);
238 }
239 }
240 lseek(uf, 0, 0);
241 nutmp = read(uf, utmp, statbf.st_size)/sizeof (struct utmpx);
242 } else
243 dsyslog(LOG_DEBUG, " ok\n");
244 }
245
246 void
mailfor(name)247 mailfor(name)
248 char *name;
249 {
250 struct utmpx *utp = &utmp[nutmp];
251 register char *cp;
252 char *rindex();
253 int offset;
254
255 /*
256 * Don't bother doing anything if nobody is
257 * logged into the system.
258 */
259 if (utmp == NULL || nutmp == 0)
260 return;
261 dsyslog(LOG_DEBUG, "mailfor %s\n", name);
262 cp = name;
263 while (*cp && *cp != '@')
264 cp++;
265 if (*cp == 0) {
266 dsyslog(LOG_DEBUG, "bad format\n");
267 return;
268 }
269 *cp = 0;
270 offset = atoi(cp+1);
271 while (--utp >= utmp)
272 if ((utp->ut_type == USER_PROCESS) &&
273 (!strncmp(utp->ut_name, name, sizeof (utmp[0].ut_name))))
274 notify(utp, offset);
275 }
276
277 char *cr;
278
279 void
notify(utp,offset)280 notify(utp, offset)
281 struct utmpx *utp;
282 {
283 FILE *tp;
284 struct sgttyb gttybuf;
285 char tty[sizeof (utmp[0].ut_line) + 5];
286 char name[sizeof (utmp[0].ut_name) + 1];
287 struct stat stb, stl;
288 time_t timep[2];
289 struct passwd *pwd;
290 int fd, mbox;
291
292
293 strcpy(tty, "/dev/");
294 strncat(tty, utp->ut_line, sizeof (utp->ut_line));
295 dsyslog(LOG_DEBUG, "notify %s on %s\n", utp->ut_name, tty);
296 if (stat(tty, &stb) == -1) {
297 dsyslog(LOG_DEBUG, "can't stat tty\n");
298 return;
299 }
300 if ((stb.st_mode & 0100) == 0) {
301 dsyslog(LOG_DEBUG, "wrong mode\n");
302 return;
303 }
304 if (fork())
305 return;
306 signal(SIGALRM, SIG_DFL);
307 alarm(30);
308
309 strncpy(name, utp->ut_name, sizeof (utp->ut_name));
310 name[sizeof (name) - 1] = '\0';
311
312 /*
313 * Do all operations that check protections as the user who
314 * will be getting the biff.
315 */
316 if ((pwd = getpwnam(name)) == (struct passwd *)-1) {
317 dsyslog(LOG_DEBUG, "getpwnam failed\n");
318 exit(1);
319 }
320 if (setuid(pwd->pw_uid) == -1) {
321 dsyslog(LOG_DEBUG, "setuid failed\n");
322 exit(1);
323 }
324
325 /*
326 * We need to make sure that the tty listed in the utmp
327 * file really is a tty device so that a corrupted utmp
328 * file doesn't cause us to over-write a real file.
329 */
330 if ((fd = open(tty, O_RDWR)) == -1) {
331 dsyslog(LOG_DEBUG, "can't open tty");
332 exit(1);
333 }
334 if (isatty(fd) == 0) {
335 dsyslog(LOG_DEBUG, "line listed in utmp file is not a tty\n");
336 exit(1);
337 }
338
339 /*
340 * For the case where the user getting the biff is root,
341 * we need to make sure that the tty we will be sending
342 * the biff to is also owned by root.
343 *
344 * Check after open, to prevent race on open.
345 */
346
347 if (fstat(fd, &stb) != 0 || stb.st_uid != pwd->pw_uid) {
348 dsyslog(LOG_DEBUG,
349 "tty is not owned by user getting the biff\n");
350 exit(1);
351 }
352
353 /*
354 * Prevent race by doing fdopen on fd, not fopen
355 * Fopen opens w/ O_CREAT, which is dangerous too
356 */
357 if ((tp = fdopen(fd, "w")) == 0) {
358 dsyslog(LOG_DEBUG, "fdopen failed\n");
359 exit(-1);
360 }
361
362 if (ioctl(fd, TIOCGETP, >tybuf) == -1) {
363 dsyslog(LOG_DEBUG, "ioctl TIOCGETP failed\n");
364 exit(1);
365 }
366 cr = (gttybuf.sg_flags&CRMOD) && !(gttybuf.sg_flags&RAW) ? "" : "\r";
367 fprintf(tp, "%s\n\007New mail for %s@%.*s\007 has arrived:%s\n",
368 cr, name, sizeof (hostname), hostname, cr);
369 fprintf(tp, "----%s\n", cr);
370
371 if ((mbox = open(name, O_RDONLY)) == -1) {
372 dsyslog(LOG_DEBUG, "can't open mailbox for %s", name);
373 exit(1);
374 }
375 /*
376 * In case of a worldwritable mail spool directory, we must take
377 * care we don't open and read from the wrong file.
378 */
379 if (fstat(mbox, &stb) == -1 || lstat(name, &stl) == -1) {
380 dsyslog(LOG_DEBUG, "stat() failed on mail file\n");
381 exit(1);
382 }
383
384 /*
385 * Here we make sure that the file wasn't a hardlink or softlink
386 * while we opened it and that it wasn't changed afterwards
387 */
388 if (!S_ISREG(stl.st_mode) ||
389 stl.st_dev != stb.st_dev ||
390 stl.st_ino != stb.st_ino ||
391 stl.st_uid != pwd->pw_uid ||
392 stb.st_nlink != 1) {
393 dsyslog(LOG_DEBUG, "mail spool file must be plain file\n");
394 exit(1);
395 }
396
397 timep[0] = stb.st_atime;
398 timep[1] = stb.st_mtime;
399 jkfprintf(tp, name, mbox, offset);
400 utime(name, timep);
401 exit(0);
402 }
403
404 void
jkfprintf(tp,name,mbox,offset)405 jkfprintf(tp, name, mbox, offset)
406 register FILE *tp;
407 char *name;
408 int mbox;
409 {
410 register FILE *fi;
411 register int linecnt, charcnt;
412 char line[BUFSIZ];
413 int inheader;
414
415 dsyslog(LOG_DEBUG, "HERE %s's mail starting at %d\n",
416 name, offset);
417 if ((fi = fdopen(mbox, "r")) == NULL) {
418 dsyslog(LOG_DEBUG, "Cant read the mail\n");
419 return;
420 }
421
422 fseek(fi, offset, L_SET);
423
424 /*
425 * Print the first 7 lines or 560 characters of the new mail
426 * (whichever comes first). Skip header crap other than
427 * From, Subject, To, and Date.
428 */
429 linecnt = 7;
430 charcnt = 560;
431 inheader = 1;
432
433
434 while (fgets(line, sizeof (line), fi) != NULL) {
435 register char *cp;
436 char *index();
437 int cnt;
438 int i;
439
440 if (linecnt <= 0 || charcnt <= 0) {
441 fprintf(tp, "...more...%s\n", cr);
442 return;
443 }
444 if (strncmp(line, "From ", 5) == 0)
445 continue;
446 if (inheader && (line[0] == ' ' || line[0] == '\t'))
447 continue;
448 cp = index(line, ':');
449 if (cp == 0 || (index(line, ' ') && index(line, ' ') < cp))
450 inheader = 0;
451 else
452 cnt = cp - line;
453 if (inheader &&
454 strncmp(line, "Date", cnt) &&
455 strncmp(line, "From", cnt) &&
456 strncmp(line, "Subject", cnt) &&
457 strncmp(line, "To", cnt))
458 continue;
459 cp = index(line, '\n');
460 if (cp)
461 *cp = '\0';
462
463 for (i = strlen(line); i-- > 0; )
464 if (!isprint(line[i]))
465 line[i] = ' ';
466
467
468 fprintf(tp, "%s%s\n", line, cr);
469 linecnt--, charcnt -= strlen(line);
470 }
471 fprintf(tp, "----%s\n", cr);
472 }
473