libexec/comsat/comsat.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   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  * @(#)comsat.c 8.1 (Berkeley) 6/4/93
  32  * $FreeBSD: head/libexec/comsat/comsat.c 326025 2017-11-20 19:49:47Z pfg $
  33  */
  34
  35 #include <sys/param.h>
  36 #include <sys/socket.h>
  37 #include <sys/stat.h>
  38 #include <sys/file.h>
  39 #include <sys/wait.h>
  40
  41 #include <netinet/in.h>
  42
  43 #include <ctype.h>
  44 #include <err.h>
  45 #include <errno.h>
  46 #include <netdb.h>
  47 #include <paths.h>
  48 #include <pwd.h>
  49 #include <termios.h>
  50 #include <signal.h>
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54 #include <sysexits.h>
  55 #include <syslog.h>
  56 #include <unistd.h>
  57 #include <utmpx.h>
  58
  59 static int      debug = 0;
  60 #define dsyslog if (debug) syslog
  61
  62 #define MAXIDLE 120
  63
  64 static char     hostname[MAXHOSTNAMELEN];
  65
  66 static void     jkfprintf(FILE *, char[], char[], off_t);
  67 static void     mailfor(char *);
  68 static void     notify(struct utmpx *, char[], off_t, int);
  69 static void     reapchildren(int);
  70
  71 int
  72 main(int argc __unused, char *argv[] __unused)
  73 {
  74         struct sockaddr_in from;
  75         socklen_t fromlen;
  76         int cc;
  77         char msgbuf[256];
  78
  79         /* verify proper invocation */
  80         fromlen = sizeof(from);
  81         if (getsockname(0, (struct sockaddr *)&from, &fromlen) < 0)
  82                 err(1, "getsockname");
  83         openlog("comsat", LOG_PID, LOG_DAEMON);
  84         if (chdir(_PATH_MAILDIR)) {
  85                 syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR);
  86                 recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
  87                 exit(1);
  88         }
  89         gethostname(hostname, sizeof(hostname));
  90         signal(SIGTTOU, SIG_IGN);
  91         signal(SIGCHLD, reapchildren);
  92         for (;;) {
  93                 cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0);
  94                 if (cc <= 0) {
  95                         if (errno != EINTR)
  96                                 sleep(1);
  97                         errno = 0;
  98                         continue;
  99                 }
 100                 msgbuf[cc] = '\0';
 101                 mailfor(msgbuf);
 102                 sigsetmask(0L);
 103         }
 104 }
 105
 106 static void
 107 reapchildren(int signo __unused)
 108 {
 109         while (wait3(NULL, WNOHANG, NULL) > 0);
 110 }
 111
 112 static void
 113 mailfor(char *name)
 114 {
 115         struct utmpx *utp;
 116         char *cp;
 117         char *file;
 118         off_t offset;
 119         int folder;
 120         char buf[sizeof(_PATH_MAILDIR) + sizeof(utp->ut_user) + 1];
 121         char buf2[sizeof(_PATH_MAILDIR) + sizeof(utp->ut_user) + 1];
 122
 123         if (!(cp = strchr(name, '@')))
 124                 return;
 125         *cp = '\0';
 126         offset = strtoll(cp + 1, NULL, 10);
 127         if (!(cp = strchr(cp + 1, ':')))
 128                 file = name;
 129         else
 130                 file = cp + 1;
 131         sprintf(buf, "%s/%.*s", _PATH_MAILDIR, (int)sizeof(utp->ut_user),
 132             name);
 133         if (*file != '/') {
 134                 sprintf(buf2, "%s/%.*s", _PATH_MAILDIR,
 135                     (int)sizeof(utp->ut_user), file);
 136                 file = buf2;
 137         }
 138         folder = strcmp(buf, file);
 139         setutxent();
 140         while ((utp = getutxent()) != NULL)
 141                 if (utp->ut_type == USER_PROCESS && !strcmp(utp->ut_user, name))
 142                         notify(utp, file, offset, folder);
 143         endutxent();
 144 }
 145
 146 static const char *cr;
 147
 148 static void
 149 notify(struct utmpx *utp, char file[], off_t offset, int folder)
 150 {
 151         FILE *tp;
 152         struct stat stb;
 153         struct termios tio;
 154         char tty[20];
 155         const char *s = utp->ut_line;
 156
 157         if (strncmp(s, "pts/", 4) == 0)
 158                 s += 4;
 159         if (strchr(s, '/')) {
 160                 /* A slash is an attempt to break security... */
 161                 syslog(LOG_AUTH | LOG_NOTICE, "Unexpected `/' in `%s'",
 162                     utp->ut_line);
 163                 return;
 164         }
 165         snprintf(tty, sizeof(tty), "%s%.*s",
 166             _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line);
 167         if (stat(tty, &stb) == -1 || !(stb.st_mode & (S_IXUSR | S_IXGRP))) {
 168                 dsyslog(LOG_DEBUG, "%s: wrong mode on %s", utp->ut_user, tty);
 169                 return;
 170         }
 171         dsyslog(LOG_DEBUG, "notify %s on %s", utp->ut_user, tty);
 172         switch (fork()) {
 173         case -1:
 174                 syslog(LOG_NOTICE, "fork failed (%m)");
 175                 return;
 176         case 0:
 177                 break;
 178         default:
 179                 return;
 180         }
 181         if ((tp = fopen(tty, "w")) == NULL) {
 182                 dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno));
 183                 _exit(1);
 184         }
 185         tcgetattr(fileno(tp), &tio);
 186         cr = ((tio.c_oflag & (OPOST|ONLCR)) == (OPOST|ONLCR)) ?  "\n" : "\n\r";
 187         switch (stb.st_mode & (S_IXUSR | S_IXGRP)) {
 188         case S_IXUSR:
 189         case (S_IXUSR | S_IXGRP):
 190                 fprintf(tp,
 191                     "%s\007New mail for %s@%.*s\007 has arrived%s%s%s:%s----%s",
 192                     cr, utp->ut_user, (int)sizeof(hostname), hostname,
 193                     folder ? cr : "", folder ? "to " : "", folder ? file : "",
 194                     cr, cr);
 195                 jkfprintf(tp, utp->ut_user, file, offset);
 196                 break;
 197         case S_IXGRP:
 198                 fprintf(tp, "\007");
 199                 fflush(tp);
 200                 sleep(1);
 201                 fprintf(tp, "\007");
 202                 break;
 203         default:
 204                 break;
 205         }
 206         fclose(tp);
 207         _exit(EX_OK);
 208 }
 209
 210 static void
 211 jkfprintf(FILE *tp, char user[], char file[], off_t offset)
 212 {
 213         unsigned char *cp, ch;
 214         FILE *fi;
 215         int linecnt, charcnt, inheader;
 216         struct passwd *p;
 217         unsigned char line[BUFSIZ];
 218
 219         /* Set effective uid to user in case mail drop is on nfs */
 220         if ((p = getpwnam(user)) != NULL)
 221                 setuid(p->pw_uid);
 222
 223         if ((fi = fopen(file, "r")) == NULL)
 224                 return;
 225
 226         fseeko(fi, offset, SEEK_CUR);
 227         /*
 228          * Print the first 7 lines or 560 characters of the new mail
 229          * (whichever comes first).  Skip header crap other than
 230          * From, Subject, To, and Date.
 231          */
 232         linecnt = 7;
 233         charcnt = 560;
 234         inheader = 1;
 235         while (fgets(line, sizeof(line), fi) != NULL) {
 236                 if (inheader) {
 237                         if (line[0] == '\n') {
 238                                 inheader = 0;
 239                                 continue;
 240                         }
 241                         if (line[0] == ' ' || line[0] == '\t' ||
 242                             (strncmp(line, "From:", 5) &&
 243                             strncmp(line, "Subject:", 8)))
 244                                 continue;
 245                 }
 246                 if (linecnt <= 0 || charcnt <= 0) {
 247                         fprintf(tp, "...more...%s", cr);
 248                         fclose(fi);
 249                         return;
 250                 }
 251                 /* strip weird stuff so can't trojan horse stupid terminals */
 252                 for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) {
 253                         /* disable upper controls and enable all other
 254                            8bit codes due to lack of locale knowledge
 255                          */
 256                         if (((ch & 0x80) && ch < 0xA0) ||
 257                             (!(ch & 0x80) && !isprint(ch) &&
 258                              !isspace(ch) && ch != '\a' && ch != '\b')
 259                            ) {
 260                                 if (ch & 0x80) {
 261                                         ch &= ~0x80;
 262                                         fputs("M-", tp);
 263                                 }
 264                                 if (iscntrl(ch)) {
 265                                         ch ^= 0x40;
 266                                         fputc('^', tp);
 267                                 }
 268                         }
 269                         fputc(ch, tp);
 270                 }
 271                 fputs(cr, tp);
 272                 --linecnt;
 273         }
 274         fprintf(tp, "----%s\n", cr);
 275         fclose(fi);
 276 }