usr/src/cmd/cmd-inet/usr.sbin/in.comsat.c

   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 #include <stdlib.h>
  55 #include <unistd.h>
  56 #include <utime.h>
  57
  58 /*
  59  * comsat
  60  */
  61
  62
  63 #ifndef UTMPX_FILE
  64 #define UTMPX_FILE "/etc/utmpx"
  65 #endif  /* UTMPX_FILE */
  66
  67 int     debug = 0;
  68 #define dsyslog if (debug) syslog
  69
  70 struct  sockaddr_in sin = { AF_INET };
  71
  72 char    hostname[MAXHOSTNAMELEN];
  73 struct  utmpx *utmp = NULL;
  74 int     nutmp;
  75 int     uf;
  76 unsigned utmpmtime = 0;                 /* last modification time for utmp */
  77 unsigned utmpsize = 0;                  /* last malloced size for utmp */
  78 time_t  lastmsgtime;
  79
  80 #ifndef SYSV
  81 int     reapchildren();
  82 #else
  83
  84 #define rindex strrchr
  85 #define index strchr
  86 #define signal(s, f)    sigset((s), (f))
  87
  88 #ifndef sigmask
  89 #define sigmask(m)      (1 << ((m)-1))
  90 #endif
  91
  92 #define set2mask(setp)  ((setp)->__sigbits[0])
  93 #define mask2set(mask, setp) \
  94         ((mask) == -1 ? sigfillset(setp) : (((setp)->__sigbits[0]) = (mask)))
  95
  96 static int
  97 sigsetmask(mask)
  98 int mask;
  99 {
 100         sigset_t oset;
 101         sigset_t nset;
 102
 103         (void) sigprocmask(0, (sigset_t *)0, &nset);
 104         mask2set(mask, &nset);
 105         (void) sigprocmask(SIG_SETMASK, &nset, &oset);
 106         return (set2mask(&oset));
 107 }
 108
 109 static int
 110 sigblock(mask)
 111 int mask;
 112 {
 113         sigset_t oset;
 114         sigset_t nset;
 115
 116         (void) sigprocmask(0, (sigset_t *)0, &nset);
 117         mask2set(mask, &nset);
 118         (void) sigprocmask(SIG_BLOCK, &nset, &oset);
 119         return (set2mask(&oset));
 120 }
 121
 122 #endif /* SYSV */
 123
 124
 125 #define MAXIDLE 120
 126 #define NAMLEN (sizeof (uts[0].ut_name) + 1)
 127
 128 void jkfprintf(FILE *tp, char *name, int mbox, int offset);
 129 void mailfor(char *name);
 130 void notify(struct utmpx *utp, int offset);
 131 void onalrm(int sig);
 132
 133 int
 134 main(argc, argv)
 135 int argc;
 136 char *argv[];
 137 {
 138         register int cc;
 139         char buf[BUFSIZ];
 140         char msgbuf[100];
 141         struct sockaddr_in from;
 142         socklen_t fromlen;
 143         int c;
 144         extern int optind;
 145         extern int getopt();
 146         extern char *optarg;
 147
 148         openlog("comsat", 0, LOG_DAEMON);
 149
 150         while ((c = getopt(argc, argv, "d")) != -1) {
 151                 switch ((char)c) {
 152                 case'd':
 153                         debug++;
 154                         break;
 155                 default:
 156                         syslog(LOG_ERR, "invalid argument %s", argv[optind]);
 157                         exit(1);
 158                 }
 159         }
 160
 161         /* verify proper invocation */
 162         fromlen = (socklen_t)sizeof (from);
 163         if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0) {
 164                 fprintf(stderr, "%s: ", argv[0]);
 165                 perror("getsockname");
 166                 _exit(1);
 167         }
 168
 169 #ifdef SYSV
 170         chdir("/var/mail");
 171 #else
 172         chdir("/var/spool/mail");
 173 #endif /* SYSV */
 174         if ((uf = open(UTMPX_FILE, O_RDONLY)) < 0) {
 175                 syslog(LOG_ERR, "%s: %m", UTMPX_FILE);
 176                 (void) recv(0, msgbuf, sizeof (msgbuf) - 1, 0);
 177                 exit(1);
 178         }
 179         (void) time(&lastmsgtime);
 180         (void) gethostname(hostname, sizeof (hostname));
 181         onalrm(0);
 182         (void) signal(SIGALRM, onalrm);
 183         (void) signal(SIGTTOU, SIG_IGN);
 184 #ifndef SYSV
 185         (void) signal(SIGCHLD, reapchildren);
 186 #else
 187         (void) signal(SIGCHLD, SIG_IGN); /* no zombies */
 188 #endif /* SYSV */
 189         for (;;) {
 190                 cc = recv(0, msgbuf, sizeof (msgbuf) - 1, 0);
 191                 if (cc <= 0) {
 192                         if (errno != EINTR)
 193                                 sleep(1);
 194                         errno = 0;
 195                         continue;
 196                 }
 197                 if (nutmp == 0)                 /* no users (yet) */
 198                         continue;
 199                 sigblock(sigmask(SIGALRM));
 200                 msgbuf[cc] = 0;
 201                 (void) time(&lastmsgtime);
 202                 mailfor(msgbuf);
 203                 sigsetmask(0);
 204         }
 205 }
 206
 207 #ifndef SYSV
 208 reapchildren()
 209 {
 210
 211         while (wait3(NULL, WNOHANG, NULL) > 0)
 212                 ;
 213 }
 214 #endif /* SYSV */
 215
 216 /* ARGSUSED */
 217 void
 218 onalrm(int sig)
 219 {
 220         struct stat statbf;
 221         time_t now;
 222
 223         (void) time(&now);
 224         if ((ulong_t)now - (ulong_t)lastmsgtime >= MAXIDLE)
 225                 exit(0);
 226         dsyslog(LOG_DEBUG, "alarm\n");
 227         alarm(15);
 228         fstat(uf, &statbf);
 229         if (statbf.st_mtime > utmpmtime) {
 230                 dsyslog(LOG_DEBUG, " changed\n");
 231                 utmpmtime = statbf.st_mtime;
 232                 if (statbf.st_size > utmpsize) {
 233                         utmpsize = statbf.st_size + 10 * sizeof (struct utmpx);
 234                         if (utmp)
 235                                 utmp = (struct utmpx *)realloc(utmp, utmpsize);
 236                         else
 237                                 utmp = (struct utmpx *)malloc(utmpsize);
 238                         if (! utmp) {
 239                                 dsyslog(LOG_DEBUG, "malloc failed\n");
 240                                 exit(1);
 241                         }
 242                 }
 243                 lseek(uf, 0, 0);
 244                 nutmp = read(uf, utmp, statbf.st_size)/sizeof (struct utmpx);
 245         } else
 246                 dsyslog(LOG_DEBUG, " ok\n");
 247 }
 248
 249 void
 250 mailfor(name)
 251 char *name;
 252 {
 253         struct utmpx *utp = &utmp[nutmp];
 254         register char *cp;
 255         char *rindex();
 256         int offset;
 257
 258         /*
 259          * Don't bother doing anything if nobody is
 260          * logged into the system.
 261          */
 262         if (utmp == NULL || nutmp == 0)
 263                 return;
 264         dsyslog(LOG_DEBUG, "mailfor %s\n", name);
 265         cp = name;
 266         while (*cp && *cp != '@')
 267                 cp++;
 268         if (*cp == 0) {
 269                 dsyslog(LOG_DEBUG, "bad format\n");
 270                 return;
 271         }
 272         *cp = 0;
 273         offset = atoi(cp+1);
 274         while (--utp >= utmp)
 275                 if ((utp->ut_type == USER_PROCESS) &&
 276                     (!strncmp(utp->ut_name, name, sizeof (utmp[0].ut_name))))
 277                         notify(utp, offset);
 278 }
 279
 280 char    *cr;
 281
 282 void
 283 notify(utp, offset)
 284 struct utmpx *utp;
 285 {
 286         FILE *tp;
 287         struct sgttyb gttybuf;
 288         char tty[sizeof (utmp[0].ut_line) + 5];
 289         char name[sizeof (utmp[0].ut_name) + 1];
 290         struct stat stb, stl;
 291         struct utimbuf timep;
 292         struct passwd *pwd;
 293         int fd, mbox;
 294
 295
 296         strcpy(tty, "/dev/");
 297         strncat(tty, utp->ut_line, sizeof (utp->ut_line));
 298         dsyslog(LOG_DEBUG, "notify %s on %s\n", utp->ut_name, tty);
 299         if (stat(tty, &stb) == -1) {
 300                 dsyslog(LOG_DEBUG, "can't stat tty\n");
 301                 return;
 302         }
 303         if ((stb.st_mode & 0100) == 0) {
 304                 dsyslog(LOG_DEBUG, "wrong mode\n");
 305                 return;
 306         }
 307         if (fork())
 308                 return;
 309         signal(SIGALRM, SIG_DFL);
 310         alarm(30);
 311
 312         strncpy(name, utp->ut_name, sizeof (utp->ut_name));
 313         name[sizeof (name) - 1] = '\0';
 314
 315         /*
 316          * Do all operations that check protections as the user who
 317          * will be getting the biff.
 318          */
 319         if ((pwd = getpwnam(name)) == (struct passwd *)-1) {
 320                 dsyslog(LOG_DEBUG, "getpwnam failed\n");
 321                 exit(1);
 322         }
 323         if (setuid(pwd->pw_uid) == -1) {
 324                 dsyslog(LOG_DEBUG, "setuid failed\n");
 325                 exit(1);
 326         }
 327
 328         /*
 329          * We need to make sure that the tty listed in the utmp
 330          * file really is a tty device so that a corrupted utmp
 331          * file doesn't cause us to over-write a real file.
 332          */
 333         if ((fd = open(tty, O_RDWR)) == -1) {
 334                 dsyslog(LOG_DEBUG, "can't open tty");
 335                 exit(1);
 336         }
 337         if (isatty(fd) == 0) {
 338                 dsyslog(LOG_DEBUG, "line listed in utmp file is not a tty\n");
 339                 exit(1);
 340         }
 341
 342         /*
 343          * For the case where the user getting the biff is root,
 344          * we need to make sure that the tty we will be sending
 345          * the biff to is also owned by root.
 346          *
 347          * Check after open, to prevent race on open.
 348          */
 349
 350         if (fstat(fd, &stb) != 0 || stb.st_uid != pwd->pw_uid) {
 351                 dsyslog(LOG_DEBUG,
 352                     "tty is not owned by user getting the biff\n");
 353                 exit(1);
 354         }
 355
 356         /*
 357          * Prevent race by doing fdopen on fd, not fopen
 358          * Fopen opens w/ O_CREAT, which is dangerous too
 359          */
 360         if ((tp = fdopen(fd, "w")) == 0) {
 361                 dsyslog(LOG_DEBUG, "fdopen failed\n");
 362                 exit(-1);
 363         }
 364
 365         if (ioctl(fd, TIOCGETP, &gttybuf) == -1) {
 366                 dsyslog(LOG_DEBUG, "ioctl TIOCGETP failed\n");
 367                 exit(1);
 368         }
 369         cr = (gttybuf.sg_flags&CRMOD) && !(gttybuf.sg_flags&RAW) ? "" : "\r";
 370         fprintf(tp, "%s\n\007New mail for %s@%.*s\007 has arrived:%s\n",
 371             cr, name, sizeof (hostname), hostname, cr);
 372         fprintf(tp, "----%s\n", cr);
 373
 374         if ((mbox = open(name, O_RDONLY)) == -1) {
 375                 dsyslog(LOG_DEBUG, "can't open mailbox for %s", name);
 376                 exit(1);
 377         }
 378         /*
 379          * In case of a worldwritable mail spool directory, we must take
 380          * care we don't open and read from the wrong file.
 381          */
 382         if (fstat(mbox, &stb) == -1 || lstat(name, &stl) == -1) {
 383                 dsyslog(LOG_DEBUG, "stat() failed on mail file\n");
 384                 exit(1);
 385         }
 386
 387         /*
 388          * Here we make sure that the file wasn't a hardlink or softlink
 389          * while we opened it and that it wasn't changed afterwards
 390          */
 391         if (!S_ISREG(stl.st_mode) ||
 392             stl.st_dev != stb.st_dev ||
 393             stl.st_ino != stb.st_ino ||
 394             stl.st_uid != pwd->pw_uid ||
 395             stb.st_nlink != 1) {
 396                 dsyslog(LOG_DEBUG, "mail spool file must be plain file\n");
 397                 exit(1);
 398         }
 399
 400         timep.actime = stb.st_atime;
 401         timep.modtime = stb.st_mtime;
 402         jkfprintf(tp, name, mbox, offset);
 403         utime(name, &timep);
 404         exit(0);
 405 }
 406
 407 void
 408 jkfprintf(tp, name, mbox, offset)
 409 register FILE *tp;
 410 char *name;
 411 int mbox;
 412 {
 413         register FILE *fi;
 414         register int linecnt, charcnt;
 415         char line[BUFSIZ];
 416         int inheader;
 417
 418         dsyslog(LOG_DEBUG, "HERE %s's mail starting at %d\n",
 419             name, offset);
 420         if ((fi = fdopen(mbox, "r")) == NULL) {
 421                 dsyslog(LOG_DEBUG, "Cant read the mail\n");
 422                 return;
 423         }
 424
 425         fseek(fi, offset, L_SET);
 426
 427         /*
 428          * Print the first 7 lines or 560 characters of the new mail
 429          * (whichever comes first).  Skip header crap other than
 430          * From, Subject, To, and Date.
 431          */
 432         linecnt = 7;
 433         charcnt = 560;
 434         inheader = 1;
 435
 436
 437         while (fgets(line, sizeof (line), fi) != NULL) {
 438                 register char *cp;
 439                 char *index();
 440                 int cnt;
 441                 int i;
 442
 443                 if (linecnt <= 0 || charcnt <= 0) {
 444                         fprintf(tp, "...more...%s\n", cr);
 445                         return;
 446                 }
 447                 if (strncmp(line, "From ", 5) == 0)
 448                         continue;
 449                 if (inheader && (line[0] == ' ' || line[0] == '\t'))
 450                         continue;
 451                 cp = index(line, ':');
 452                 if (cp == 0 || (index(line, ' ') && index(line, ' ') < cp))
 453                         inheader = 0;
 454                 else
 455                         cnt = cp - line;
 456                 if (inheader &&
 457                     strncmp(line, "Date", cnt) &&
 458                     strncmp(line, "From", cnt) &&
 459                     strncmp(line, "Subject", cnt) &&
 460                     strncmp(line, "To", cnt))
 461                         continue;
 462                 cp = index(line, '\n');
 463                 if (cp)
 464                         *cp = '\0';
 465
 466                 for (i = strlen(line); i-- > 0; )
 467                         if (!isprint(line[i]))
 468                                 line[i] = ' ';
 469
 470
 471                 fprintf(tp, "%s%s\n", line, cr);
 472                 linecnt--, charcnt -= strlen(line);
 473         }
 474         fprintf(tp, "----%s\n", cr);
 475 }