1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #ifndef lint 38 static const char copyright[] = 39 "@(#) Copyright (c) 1989, 1993\n\ 40 The Regents of the University of California. All rights reserved.\n"; 41 #endif 42 43 #if 0 44 #ifndef lint 45 static char sccsid[] = "@(#)write.c 8.1 (Berkeley) 6/6/93"; 46 #endif 47 #endif 48 49 #include <sys/cdefs.h> 50 __FBSDID("$FreeBSD$"); 51 52 #include <sys/param.h> 53 #include <sys/signal.h> 54 #include <sys/stat.h> 55 #include <sys/file.h> 56 #include <sys/time.h> 57 #include <ctype.h> 58 #include <err.h> 59 #include <locale.h> 60 #include <paths.h> 61 #include <pwd.h> 62 #include <stdio.h> 63 #include <stdlib.h> 64 #include <string.h> 65 #include <unistd.h> 66 #include <utmp.h> 67 68 void done(int); 69 void do_write(char *, char *, uid_t); 70 static void usage(void); 71 int term_chk(char *, int *, time_t *, int); 72 void wr_fputs(unsigned char *s); 73 void search_utmp(char *, char *, char *, uid_t); 74 int utmp_chk(char *, char *); 75 76 int 77 main(argc, argv) 78 int argc; 79 char **argv; 80 { 81 register char *cp; 82 time_t atime; 83 uid_t myuid; 84 int msgsok, myttyfd; 85 char tty[MAXPATHLEN], *mytty; 86 87 (void)setlocale(LC_CTYPE, ""); 88 89 while (getopt(argc, argv, "") != -1) 90 usage(); 91 argc -= optind; 92 argv += optind; 93 94 /* check that sender has write enabled */ 95 if (isatty(fileno(stdin))) 96 myttyfd = fileno(stdin); 97 else if (isatty(fileno(stdout))) 98 myttyfd = fileno(stdout); 99 else if (isatty(fileno(stderr))) 100 myttyfd = fileno(stderr); 101 else 102 errx(1, "can't find your tty"); 103 if (!(mytty = ttyname(myttyfd))) 104 errx(1, "can't find your tty's name"); 105 if ((cp = rindex(mytty, '/'))) 106 mytty = cp + 1; 107 if (term_chk(mytty, &msgsok, &atime, 1)) 108 exit(1); 109 if (!msgsok) 110 errx(1, "you have write permission turned off"); 111 112 myuid = getuid(); 113 114 /* check args */ 115 switch (argc) { 116 case 1: 117 search_utmp(argv[0], tty, mytty, myuid); 118 do_write(tty, mytty, myuid); 119 break; 120 case 2: 121 if (!strncmp(argv[1], _PATH_DEV, strlen(_PATH_DEV))) 122 argv[1] += strlen(_PATH_DEV); 123 if (utmp_chk(argv[0], argv[1])) 124 errx(1, "%s is not logged in on %s", argv[0], argv[1]); 125 if (term_chk(argv[1], &msgsok, &atime, 1)) 126 exit(1); 127 if (myuid && !msgsok) 128 errx(1, "%s has messages disabled on %s", argv[0], argv[1]); 129 do_write(argv[1], mytty, myuid); 130 break; 131 default: 132 usage(); 133 } 134 done(0); 135 return (0); 136 } 137 138 static void 139 usage() 140 { 141 (void)fprintf(stderr, "usage: write user [tty]\n"); 142 exit(1); 143 } 144 145 /* 146 * utmp_chk - checks that the given user is actually logged in on 147 * the given tty 148 */ 149 int 150 utmp_chk(user, tty) 151 char *user, *tty; 152 { 153 struct utmp u; 154 int ufd; 155 156 if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) 157 return(0); /* ignore error, shouldn't happen anyway */ 158 159 while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u)) 160 if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0 && 161 strncmp(tty, u.ut_line, sizeof(u.ut_line)) == 0) { 162 (void)close(ufd); 163 return(0); 164 } 165 166 (void)close(ufd); 167 return(1); 168 } 169 170 /* 171 * search_utmp - search utmp for the "best" terminal to write to 172 * 173 * Ignores terminals with messages disabled, and of the rest, returns 174 * the one with the most recent access time. Returns as value the number 175 * of the user's terminals with messages enabled, or -1 if the user is 176 * not logged in at all. 177 * 178 * Special case for writing to yourself - ignore the terminal you're 179 * writing from, unless that's the only terminal with messages enabled. 180 */ 181 void 182 search_utmp(user, tty, mytty, myuid) 183 char *user, *tty, *mytty; 184 uid_t myuid; 185 { 186 struct utmp u; 187 time_t bestatime, atime; 188 int ufd, nloggedttys, nttys, msgsok, user_is_me; 189 char atty[UT_LINESIZE + 1]; 190 191 if ((ufd = open(_PATH_UTMP, O_RDONLY)) < 0) 192 err(1, "utmp"); 193 194 nloggedttys = nttys = 0; 195 bestatime = 0; 196 user_is_me = 0; 197 while (read(ufd, (char *) &u, sizeof(u)) == sizeof(u)) 198 if (strncmp(user, u.ut_name, sizeof(u.ut_name)) == 0) { 199 ++nloggedttys; 200 (void)strncpy(atty, u.ut_line, UT_LINESIZE); 201 atty[UT_LINESIZE] = '\0'; 202 if (term_chk(atty, &msgsok, &atime, 0)) 203 continue; /* bad term? skip */ 204 if (myuid && !msgsok) 205 continue; /* skip ttys with msgs off */ 206 if (strcmp(atty, mytty) == 0) { 207 user_is_me = 1; 208 continue; /* don't write to yourself */ 209 } 210 ++nttys; 211 if (atime > bestatime) { 212 bestatime = atime; 213 (void)strcpy(tty, atty); 214 } 215 } 216 217 (void)close(ufd); 218 if (nloggedttys == 0) 219 errx(1, "%s is not logged in", user); 220 if (nttys == 0) { 221 if (user_is_me) { /* ok, so write to yourself! */ 222 (void)strcpy(tty, mytty); 223 return; 224 } 225 errx(1, "%s has messages disabled", user); 226 } else if (nttys > 1) { 227 warnx("%s is logged in more than once; writing to %s", user, tty); 228 } 229 } 230 231 /* 232 * term_chk - check that a terminal exists, and get the message bit 233 * and the access time 234 */ 235 int 236 term_chk(tty, msgsokP, atimeP, showerror) 237 char *tty; 238 int *msgsokP, showerror; 239 time_t *atimeP; 240 { 241 struct stat s; 242 char path[MAXPATHLEN]; 243 244 (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 245 if (stat(path, &s) < 0) { 246 if (showerror) 247 warn("%s", path); 248 return(1); 249 } 250 *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */ 251 *atimeP = s.st_atime; 252 return(0); 253 } 254 255 /* 256 * do_write - actually make the connection 257 */ 258 void 259 do_write(tty, mytty, myuid) 260 char *tty, *mytty; 261 uid_t myuid; 262 { 263 const char *login; 264 char *nows; 265 struct passwd *pwd; 266 time_t now; 267 char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512]; 268 269 /* Determine our login name before the we reopen() stdout */ 270 if ((login = getlogin()) == NULL) { 271 if ((pwd = getpwuid(myuid))) 272 login = pwd->pw_name; 273 else 274 login = "???"; 275 } 276 277 (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 278 if ((freopen(path, "w", stdout)) == NULL) 279 err(1, "%s", path); 280 281 (void)signal(SIGINT, done); 282 (void)signal(SIGHUP, done); 283 284 /* print greeting */ 285 if (gethostname(host, sizeof(host)) < 0) 286 (void)strcpy(host, "???"); 287 now = time((time_t *)NULL); 288 nows = ctime(&now); 289 nows[16] = '\0'; 290 (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n", 291 login, host, mytty, nows + 11); 292 293 while (fgets(line, sizeof(line), stdin) != NULL) 294 wr_fputs(line); 295 } 296 297 /* 298 * done - cleanup and exit 299 */ 300 void 301 done(n) 302 int n __unused; 303 { 304 (void)printf("EOF\r\n"); 305 exit(0); 306 } 307 308 /* 309 * wr_fputs - like fputs(), but makes control characters visible and 310 * turns \n into \r\n 311 */ 312 void 313 wr_fputs(s) 314 unsigned char *s; 315 { 316 317 #define PUTC(c) if (putchar(c) == EOF) err(1, NULL); 318 319 for (; *s != '\0'; ++s) { 320 if (*s == '\n') { 321 PUTC('\r'); 322 } else if (((*s & 0x80) && *s < 0xA0) || 323 /* disable upper controls */ 324 (!isprint(*s) && !isspace(*s) && 325 *s != '\a' && *s != '\b') 326 ) { 327 if (*s & 0x80) { 328 *s &= ~0x80; 329 PUTC('M'); 330 PUTC('-'); 331 } 332 if (iscntrl(*s)) { 333 *s ^= 0x40; 334 PUTC('^'); 335 } 336 } 337 PUTC(*s); 338 } 339 return; 340 #undef PUTC 341 } 342