libexec/comsat/comsat.c

   1 /*      $NetBSD: comsat.c,v 1.38 2008/07/20 01:09:06 lukem 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 1.38 2008/07/20 01:09:06 lukem 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(const char *);
  93 static void notify(const struct utmpentry *, off_t);
  94 static void onalrm(int);
  95 static void checkutmp(void);
  96
  97 int
  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*/
 167 onalrm(int signo)
 168 {
 169         needupdate = 1;
 170 }
 171
 172 static 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
 186 mailfor(const 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
 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((u_int)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 users 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
 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, Subject, To, and Date.
 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 }