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 #define _ULOG_POSIX_NAMES 66 #include <ulog.h> 67 #include <unistd.h> 68 69 void done(int); 70 void do_write(char *, char *, uid_t); 71 static void usage(void); 72 int term_chk(char *, int *, time_t *, int); 73 void wr_fputs(unsigned char *s); 74 void search_utmp(char *, char *, char *, uid_t); 75 int utmp_chk(char *, char *); 76 77 int 78 main(int argc, char **argv) 79 { 80 time_t atime; 81 uid_t myuid; 82 int msgsok, myttyfd; 83 char tty[MAXPATHLEN], *mytty; 84 85 (void)setlocale(LC_CTYPE, ""); 86 87 while (getopt(argc, argv, "") != -1) 88 usage(); 89 argc -= optind; 90 argv += optind; 91 92 /* check that sender has write enabled */ 93 if (isatty(fileno(stdin))) 94 myttyfd = fileno(stdin); 95 else if (isatty(fileno(stdout))) 96 myttyfd = fileno(stdout); 97 else if (isatty(fileno(stderr))) 98 myttyfd = fileno(stderr); 99 else 100 errx(1, "can't find your tty"); 101 if (!(mytty = ttyname(myttyfd))) 102 errx(1, "can't find your tty's name"); 103 if (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV))) 104 mytty += strlen(_PATH_DEV); 105 if (term_chk(mytty, &msgsok, &atime, 1)) 106 exit(1); 107 if (!msgsok) 108 errx(1, "you have write permission turned off"); 109 110 myuid = getuid(); 111 112 /* check args */ 113 switch (argc) { 114 case 1: 115 search_utmp(argv[0], tty, mytty, myuid); 116 do_write(tty, mytty, myuid); 117 break; 118 case 2: 119 if (!strncmp(argv[1], _PATH_DEV, strlen(_PATH_DEV))) 120 argv[1] += strlen(_PATH_DEV); 121 if (utmp_chk(argv[0], argv[1])) 122 errx(1, "%s is not logged in on %s", argv[0], argv[1]); 123 if (term_chk(argv[1], &msgsok, &atime, 1)) 124 exit(1); 125 if (myuid && !msgsok) 126 errx(1, "%s has messages disabled on %s", argv[0], argv[1]); 127 do_write(argv[1], mytty, myuid); 128 break; 129 default: 130 usage(); 131 } 132 done(0); 133 return (0); 134 } 135 136 static void 137 usage(void) 138 { 139 (void)fprintf(stderr, "usage: write user [tty]\n"); 140 exit(1); 141 } 142 143 /* 144 * utmp_chk - checks that the given user is actually logged in on 145 * the given tty 146 */ 147 int 148 utmp_chk(char *user, char *tty) 149 { 150 struct utmpx lu, *u; 151 152 strncpy(lu.ut_line, tty, sizeof lu.ut_line); 153 setutxent(); 154 while ((u = getutxline(&lu)) != NULL) 155 if (u->ut_type == USER_PROCESS && 156 strcmp(user, u->ut_user) == 0) { 157 endutxent(); 158 return(0); 159 } 160 endutxent(); 161 return(1); 162 } 163 164 /* 165 * search_utmp - search utmp for the "best" terminal to write to 166 * 167 * Ignores terminals with messages disabled, and of the rest, returns 168 * the one with the most recent access time. Returns as value the number 169 * of the user's terminals with messages enabled, or -1 if the user is 170 * not logged in at all. 171 * 172 * Special case for writing to yourself - ignore the terminal you're 173 * writing from, unless that's the only terminal with messages enabled. 174 */ 175 void 176 search_utmp(char *user, char *tty, char *mytty, uid_t myuid) 177 { 178 struct utmpx *u; 179 time_t bestatime, atime; 180 int nloggedttys, nttys, msgsok, user_is_me; 181 182 nloggedttys = nttys = 0; 183 bestatime = 0; 184 user_is_me = 0; 185 186 setutxent(); 187 while ((u = getutxent()) != NULL) 188 if (u->ut_type == USER_PROCESS && 189 strcmp(user, u->ut_user) == 0) { 190 ++nloggedttys; 191 if (term_chk(u->ut_line, &msgsok, &atime, 0)) 192 continue; /* bad term? skip */ 193 if (myuid && !msgsok) 194 continue; /* skip ttys with msgs off */ 195 if (strcmp(u->ut_line, mytty) == 0) { 196 user_is_me = 1; 197 continue; /* don't write to yourself */ 198 } 199 ++nttys; 200 if (atime > bestatime) { 201 bestatime = atime; 202 (void)strlcpy(tty, u->ut_line, MAXPATHLEN); 203 } 204 } 205 endutxent(); 206 207 if (nloggedttys == 0) 208 errx(1, "%s is not logged in", user); 209 if (nttys == 0) { 210 if (user_is_me) { /* ok, so write to yourself! */ 211 (void)strlcpy(tty, mytty, MAXPATHLEN); 212 return; 213 } 214 errx(1, "%s has messages disabled", user); 215 } else if (nttys > 1) { 216 warnx("%s is logged in more than once; writing to %s", user, tty); 217 } 218 } 219 220 /* 221 * term_chk - check that a terminal exists, and get the message bit 222 * and the access time 223 */ 224 int 225 term_chk(char *tty, int *msgsokP, time_t *atimeP, int showerror) 226 { 227 struct stat s; 228 char path[MAXPATHLEN]; 229 230 (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 231 if (stat(path, &s) < 0) { 232 if (showerror) 233 warn("%s", path); 234 return(1); 235 } 236 *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */ 237 *atimeP = s.st_atime; 238 return(0); 239 } 240 241 /* 242 * do_write - actually make the connection 243 */ 244 void 245 do_write(char *tty, char *mytty, uid_t myuid) 246 { 247 const char *login; 248 char *nows; 249 struct passwd *pwd; 250 time_t now; 251 char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512]; 252 253 /* Determine our login name before we reopen() stdout */ 254 if ((login = getlogin()) == NULL) { 255 if ((pwd = getpwuid(myuid))) 256 login = pwd->pw_name; 257 else 258 login = "???"; 259 } 260 261 (void)snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 262 if ((freopen(path, "w", stdout)) == NULL) 263 err(1, "%s", path); 264 265 (void)signal(SIGINT, done); 266 (void)signal(SIGHUP, done); 267 268 /* print greeting */ 269 if (gethostname(host, sizeof(host)) < 0) 270 (void)strcpy(host, "???"); 271 now = time((time_t *)NULL); 272 nows = ctime(&now); 273 nows[16] = '\0'; 274 (void)printf("\r\n\007\007\007Message from %s@%s on %s at %s ...\r\n", 275 login, host, mytty, nows + 11); 276 277 while (fgets(line, sizeof(line), stdin) != NULL) 278 wr_fputs(line); 279 } 280 281 /* 282 * done - cleanup and exit 283 */ 284 void 285 done(int n __unused) 286 { 287 (void)printf("EOF\r\n"); 288 exit(0); 289 } 290 291 /* 292 * wr_fputs - like fputs(), but makes control characters visible and 293 * turns \n into \r\n 294 */ 295 void 296 wr_fputs(unsigned char *s) 297 { 298 299 #define PUTC(c) if (putchar(c) == EOF) err(1, NULL); 300 301 for (; *s != '\0'; ++s) { 302 if (*s == '\n') { 303 PUTC('\r'); 304 } else if (((*s & 0x80) && *s < 0xA0) || 305 /* disable upper controls */ 306 (!isprint(*s) && !isspace(*s) && 307 *s != '\a' && *s != '\b') 308 ) { 309 if (*s & 0x80) { 310 *s &= ~0x80; 311 PUTC('M'); 312 PUTC('-'); 313 } 314 if (iscntrl(*s)) { 315 *s ^= 0x40; 316 PUTC('^'); 317 } 318 } 319 PUTC(*s); 320 } 321 return; 322 #undef PUTC 323 } 324