1 /* $OpenBSD: comsat.c,v 1.37 2012/12/04 02:24:47 deraadt 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/limits.h> 33 #include <sys/socket.h> 34 #include <sys/stat.h> 35 #include <sys/wait.h> 36 37 #include <netinet/in.h> 38 39 #include <ctype.h> 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <netdb.h> 43 #include <paths.h> 44 #include <pwd.h> 45 #include <signal.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <syslog.h> 50 #include <termios.h> 51 #include <unistd.h> 52 #include <utmp.h> 53 #include <vis.h> 54 55 int debug = 0; 56 #define dsyslog if (debug) syslog 57 58 #define MAXIDLE 120 59 60 char hostname[MAXHOSTNAMELEN]; 61 struct utmp *utmp = NULL; 62 time_t lastmsgtime; 63 int nutmp, uf; 64 65 void jkfprintf(FILE *, char[], off_t); 66 void mailfor(char *); 67 void notify(struct utmp *, off_t); 68 void readutmp(int); 69 void doreadutmp(void); 70 void reapchildren(int); 71 72 volatile sig_atomic_t wantreadutmp; 73 74 int 75 main(int argc, char *argv[]) 76 { 77 struct sockaddr_storage from; 78 struct sigaction sa; 79 ssize_t cc; 80 socklen_t fromlen; 81 char msgbuf[100]; 82 sigset_t sigset; 83 84 /* verify proper invocation */ 85 fromlen = sizeof(from); 86 if (getsockname(0, (struct sockaddr *)&from, &fromlen) == -1) { 87 (void)fprintf(stderr, 88 "comsat: getsockname: %s.\n", strerror(errno)); 89 exit(1); 90 } 91 openlog("comsat", LOG_PID, LOG_DAEMON); 92 if (chdir(_PATH_MAILDIR)) { 93 syslog(LOG_ERR, "chdir: %s: %m", _PATH_MAILDIR); 94 (void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0); 95 exit(1); 96 } 97 if ((uf = open(_PATH_UTMP, O_RDONLY, 0)) == -1) { 98 syslog(LOG_ERR, "open: %s: %m", _PATH_UTMP); 99 (void) recv(0, msgbuf, sizeof(msgbuf) - 1, 0); 100 exit(1); 101 } 102 (void)time(&lastmsgtime); 103 (void)gethostname(hostname, sizeof(hostname)); 104 doreadutmp(); 105 106 (void)signal(SIGTTOU, SIG_IGN); 107 108 bzero(&sa, sizeof sa); 109 sigemptyset(&sa.sa_mask); 110 sa.sa_handler = readutmp; 111 sa.sa_flags = 0; /* no SA_RESTART */ 112 (void)sigaction(SIGALRM, &sa, NULL); 113 114 sa.sa_handler = reapchildren; 115 sa.sa_flags = SA_RESTART; 116 (void)sigaction(SIGCHLD, &sa, NULL); 117 118 for (;;) { 119 if (wantreadutmp) { 120 wantreadutmp = 0; 121 doreadutmp(); 122 } 123 124 cc = recv(0, msgbuf, sizeof(msgbuf) - 1, 0); 125 if (cc <= 0) { 126 if (errno != EINTR) 127 sleep(1); 128 continue; 129 } 130 if (!nutmp) /* no one has logged in yet */ 131 continue; 132 sigemptyset(&sigset); 133 sigaddset(&sigset, SIGALRM); 134 sigprocmask(SIG_SETMASK, &sigset, NULL); 135 msgbuf[cc] = '\0'; 136 (void)time(&lastmsgtime); 137 mailfor(msgbuf); 138 sigemptyset(&sigset); 139 sigprocmask(SIG_SETMASK, &sigset, NULL); 140 } 141 } 142 143 /* ARGSUSED */ 144 void 145 reapchildren(int signo) 146 { 147 int save_errno = errno; 148 149 while (wait3(NULL, WNOHANG, NULL) > 0) 150 ; 151 errno = save_errno; 152 } 153 154 /* ARGSUSED */ 155 void 156 readutmp(int signo) 157 { 158 wantreadutmp = 1; 159 } 160 161 void 162 doreadutmp(void) 163 { 164 static u_int utmpsize; /* last malloced size for utmp */ 165 static time_t utmpmtime; /* last modification time for utmp */ 166 struct stat statbf; 167 168 if (time(NULL) - lastmsgtime >= MAXIDLE) 169 exit(0); 170 (void)fstat(uf, &statbf); 171 if (statbf.st_mtime > utmpmtime) { 172 utmpmtime = statbf.st_mtime; 173 /* avoid int overflow */ 174 if (statbf.st_size > INT_MAX - 10 * sizeof(struct utmp)) { 175 syslog(LOG_ALERT, "utmp file excessively large"); 176 exit(1); 177 } 178 if (statbf.st_size > utmpsize) { 179 u_int nutmpsize = statbf.st_size + 10 * 180 sizeof(struct utmp); 181 struct utmp *u; 182 183 if ((u = realloc(utmp, nutmpsize)) == NULL) { 184 free(utmp); 185 syslog(LOG_ERR, "%s", strerror(errno)); 186 exit(1); 187 } 188 utmp = u; 189 utmpsize = nutmpsize; 190 } 191 (void)lseek(uf, 0, SEEK_SET); 192 nutmp = read(uf, utmp, statbf.st_size)/sizeof(struct utmp); 193 } 194 (void)alarm(15); 195 } 196 197 void 198 mailfor(char *name) 199 { 200 struct utmp *utp = &utmp[nutmp]; 201 char utname[UT_NAMESIZE+1]; 202 char *cp; 203 off_t offset; 204 205 if (!(cp = strchr(name, '@'))) 206 return; 207 *cp = '\0'; 208 offset = atoi(cp + 1); 209 while (--utp >= utmp) { 210 memcpy(utname, utp->ut_name, UT_NAMESIZE); 211 utname[UT_NAMESIZE] = '\0'; 212 if (!strncmp(utname, name, UT_NAMESIZE)) 213 notify(utp, offset); 214 } 215 } 216 217 static char *cr; 218 219 void 220 notify(struct utmp *utp, off_t offset) 221 { 222 FILE *tp; 223 struct stat stb; 224 struct termios ttybuf; 225 char tty[MAXPATHLEN], name[UT_NAMESIZE + 1]; 226 227 (void)snprintf(tty, sizeof(tty), "%s%.*s", 228 _PATH_DEV, (int)sizeof(utp->ut_line), utp->ut_line); 229 if (strchr(tty + sizeof(_PATH_DEV) - 1, '/')) { 230 /* A slash is an attempt to break security... */ 231 syslog(LOG_AUTH | LOG_NOTICE, "'/' in \"%s\"", tty); 232 return; 233 } 234 if (stat(tty, &stb) || !(stb.st_mode & S_IEXEC)) { 235 dsyslog(LOG_DEBUG, "%.*s: wrong mode on %s", 236 (int)sizeof(utp->ut_name), utp->ut_name, tty); 237 return; 238 } 239 dsyslog(LOG_DEBUG, "notify %.*s on %s", (int)sizeof(utp->ut_name), 240 utp->ut_name, tty); 241 if (fork()) 242 return; 243 (void)signal(SIGALRM, SIG_DFL); 244 (void)alarm(30); 245 if ((tp = fopen(tty, "w")) == NULL) { 246 dsyslog(LOG_ERR, "%s: %s", tty, strerror(errno)); 247 _exit(1); 248 } 249 (void)tcgetattr(fileno(tp), &ttybuf); 250 cr = (ttybuf.c_oflag & ONLCR) && (ttybuf.c_oflag & OPOST) ? 251 "\n" : "\n\r"; 252 memcpy(name, utp->ut_name, UT_NAMESIZE); 253 name[UT_NAMESIZE] = '\0'; 254 (void)fprintf(tp, "%s\007New mail for %s@%.*s\007 has arrived:%s----%s", 255 cr, name, (int)sizeof(hostname), hostname, cr, cr); 256 jkfprintf(tp, name, offset); 257 (void)fclose(tp); 258 _exit(0); 259 } 260 261 void 262 jkfprintf(FILE *tp, char name[], off_t offset) 263 { 264 char *cp, ch; 265 char visout[5], *s2; 266 FILE *fi; 267 int linecnt, charcnt, inheader; 268 struct passwd *p; 269 char line[BUFSIZ]; 270 271 /* Set effective uid to user in case mail drop is on nfs */ 272 if ((p = getpwnam(name)) != NULL) { 273 (void) seteuid(p->pw_uid); 274 (void) setuid(p->pw_uid); 275 } 276 277 if ((fi = fopen(name, "r")) == NULL) 278 return; 279 280 (void)fseeko(fi, offset, SEEK_SET); 281 /* 282 * Print the first 7 lines or 560 characters of the new mail 283 * (whichever comes first). Skip header crap other than 284 * From, Subject, To, and Date. 285 */ 286 linecnt = 7; 287 charcnt = 560; 288 inheader = 1; 289 while (fgets(line, sizeof(line), fi) != NULL) { 290 if (inheader) { 291 if (line[0] == '\n') { 292 inheader = 0; 293 continue; 294 } 295 if (line[0] == ' ' || line[0] == '\t' || 296 (strncmp(line, "From:", 5) && 297 strncmp(line, "Subject:", 8))) 298 continue; 299 } 300 if (linecnt <= 0 || charcnt <= 0) { 301 (void)fprintf(tp, "...more...%s", cr); 302 (void)fclose(fi); 303 return; 304 } 305 /* strip weird stuff so can't trojan horse stupid terminals */ 306 for (cp = line; (ch = *cp) && ch != '\n'; ++cp, --charcnt) { 307 ch = toascii(ch); 308 vis(visout, ch, VIS_SAFE|VIS_NOSLASH, cp[1]); 309 for (s2 = visout; *s2; s2++) 310 (void)fputc(*s2, tp); 311 } 312 (void)fputs(cr, tp); 313 --linecnt; 314 } 315 (void)fprintf(tp, "----%s\n", cr); 316 (void)fclose(fi); 317 } 318