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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#) Copyright (c) 1989, 1993 The Regents of the University of California. All rights reserved. 33 * @(#)write.c 8.1 (Berkeley) 6/6/93 34 * $FreeBSD: src/usr.bin/write/write.c,v 1.12 1999/08/28 01:07:48 peter Exp $ 35 */ 36 37 #include <sys/param.h> 38 #include <sys/stat.h> 39 #include <sys/file.h> 40 41 #include <ctype.h> 42 #include <err.h> 43 #include <locale.h> 44 #include <paths.h> 45 #include <pwd.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <signal.h> 50 #include <time.h> 51 #include <unistd.h> 52 #include "utmpentry.h" 53 54 static void done(int); 55 static void do_write(const char *, const char *, uid_t, int *); 56 static void usage(void); 57 static int term_chk(const char *, int *, time_t *, int); 58 static void wr_fputs(unsigned char *s); 59 static void search_utmpx(const char *, char *, size_t, const char *, uid_t); 60 static int utmpx_chk(const char *, const char *); 61 62 int 63 main(int argc, char **argv) 64 { 65 time_t atime; 66 uid_t myuid; 67 int msgsok, mymsgok, myttyfd; 68 char tty[MAXPATHLEN], *mytty; 69 70 setlocale(LC_CTYPE, ""); 71 72 /* check that sender has write enabled */ 73 if (isatty(fileno(stdin))) 74 myttyfd = fileno(stdin); 75 else if (isatty(fileno(stdout))) 76 myttyfd = fileno(stdout); 77 else if (isatty(fileno(stderr))) 78 myttyfd = fileno(stderr); 79 else 80 errx(1, "can't find your tty"); 81 if (!(mytty = ttyname(myttyfd))) 82 errx(1, "can't find your tty's name"); 83 if (!strncmp(mytty, _PATH_DEV, strlen(_PATH_DEV))) 84 mytty += strlen(_PATH_DEV); 85 if (term_chk(mytty, &mymsgok, &atime, 1)) 86 exit(1); 87 if (!mymsgok) 88 warnx("you have write permission turned off (man mesg)"); 89 90 myuid = getuid(); 91 92 /* check args */ 93 switch (argc) { 94 case 2: 95 search_utmpx(argv[1], tty, sizeof tty, mytty, myuid); 96 do_write(tty, mytty, myuid, &mymsgok); 97 break; 98 case 3: 99 if (!strncmp(argv[2], _PATH_DEV, strlen(_PATH_DEV))) 100 argv[2] += strlen(_PATH_DEV); 101 if (utmpx_chk(argv[1], argv[2])) 102 errx(1, "%s is not logged in on %s", argv[1], argv[2]); 103 if (term_chk(argv[2], &msgsok, &atime, 1)) 104 exit(1); 105 if (myuid && !msgsok) 106 errx(1, "%s has messages disabled on %s", argv[1], argv[2]); 107 do_write(argv[2], mytty, myuid, &mymsgok); 108 break; 109 default: 110 usage(); 111 } 112 done(0); 113 return (0); 114 } 115 116 static void 117 usage(void) 118 { 119 fprintf(stderr, "usage: write user [tty]\n"); 120 exit(1); 121 } 122 123 /* 124 * utmpx_chk - checks that the given user is actually logged in on 125 * the given tty 126 */ 127 static int 128 utmpx_chk(const char *user, const char *tty) 129 { 130 struct utmpentry *ep; 131 132 getutentries(NULL, &ep); 133 134 for (; ep; ep = ep->next) { 135 if (strcmp(user, ep->name) == 0 && 136 strcmp(tty, ep->line) == 0) { 137 return(0); 138 } 139 } 140 141 return(1); 142 } 143 144 /* 145 * search_utmpx - search utmpx for the "best" terminal to write to 146 * 147 * Ignores terminals with messages disabled, and of the rest, returns 148 * the one with the most recent access time. Returns as value the number 149 * of the user's terminals with messages enabled, or -1 if the user is 150 * not logged in at all. 151 * 152 * Special case for writing to yourself - ignore the terminal you're 153 * writing from, unless that's the only terminal with messages enabled. 154 */ 155 static void 156 search_utmpx(const char *user, char *tty, size_t ttyl, const char *mytty, uid_t myuid) 157 { 158 struct utmpentry *ep; 159 time_t bestatime, atime; 160 int nloggedttys, nttys, msgsok, user_is_me; 161 162 getutentries(NULL, &ep); 163 164 nloggedttys = nttys = 0; 165 bestatime = 0; 166 user_is_me = 0; 167 for (; ep; ep = ep->next) 168 if (strcmp(user, ep->name) == 0) { 169 ++nloggedttys; 170 if (term_chk(ep->line, &msgsok, &atime, 0)) 171 continue; /* bad term? skip */ 172 if (myuid && !msgsok) 173 continue; /* skip ttys with msgs off */ 174 if (strcmp(ep->line, mytty) == 0) { 175 user_is_me = 1; 176 continue; /* don't write to yourself */ 177 } 178 ++nttys; 179 if (atime > bestatime) { 180 bestatime = atime; 181 strlcpy(tty, ep->line, ttyl); 182 } 183 } 184 185 if (nloggedttys == 0) 186 errx(1, "%s is not logged in", user); 187 if (nttys == 0) { 188 if (user_is_me) { /* ok, so write to yourself! */ 189 strlcpy(tty, mytty, ttyl); 190 return; 191 } 192 errx(1, "%s has messages disabled", user); 193 } else if (nttys > 1) { 194 warnx("%s is logged in more than once; writing to %s", user, tty); 195 } 196 } 197 198 /* 199 * term_chk - check that a terminal exists, and get the message bit 200 * and the access time 201 */ 202 static int 203 term_chk(const char *tty, int *msgsokP, time_t *atimeP, int showerror) 204 { 205 struct stat s; 206 char path[MAXPATHLEN]; 207 208 snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 209 if (stat(path, &s) < 0) { 210 if (showerror) 211 warn("%s", path); 212 return(1); 213 } 214 *msgsokP = (s.st_mode & S_IWGRP) != 0; /* group write bit */ 215 *atimeP = s.st_atime; 216 return(0); 217 } 218 219 /* 220 * do_write - actually make the connection 221 */ 222 static void 223 do_write(const char *tty, const char *mytty, uid_t myuid, int *mymsgok) 224 { 225 const char *login; 226 char *nows; 227 struct passwd *pwd; 228 time_t now; 229 char path[MAXPATHLEN], host[MAXHOSTNAMELEN], line[512]; 230 231 /* Determine our login name before we reopen() stdout */ 232 if ((login = getlogin()) == NULL) { 233 if ((pwd = getpwuid(myuid))) 234 login = pwd->pw_name; 235 else 236 login = "???"; 237 } 238 239 snprintf(path, sizeof(path), "%s%s", _PATH_DEV, tty); 240 if ((freopen(path, "w", stdout)) == NULL) 241 err(1, "%s", path); 242 243 signal(SIGINT, done); 244 signal(SIGHUP, done); 245 246 /* print greeting */ 247 if (gethostname(host, sizeof(host)) < 0) 248 strlcpy(host, "???", sizeof host); 249 now = time(NULL); 250 nows = ctime(&now); 251 nows[16] = '\0'; 252 printf("\r\n\007\007\007Message from %s@%s on %s at %s (%s %s replies)...\r\n", 253 login, host, mytty, nows + 11, login, *mymsgok == 0 ? "does not accept" : "accepts"); 254 255 while (fgets(line, sizeof(line), stdin) != NULL) 256 wr_fputs(line); 257 } 258 259 /* 260 * done - cleanup and exit 261 */ 262 static void 263 done(__unused int n) 264 { 265 printf("EOF\r\n"); 266 exit(0); 267 } 268 269 /* 270 * wr_fputs - like fputs(), but makes control characters visible and 271 * turns \n into \r\n 272 */ 273 static void 274 wr_fputs(unsigned char *s) 275 { 276 277 #define PUTC(c) if (putchar(c) == EOF) err(1, NULL); 278 279 for (; *s != '\0'; ++s) { 280 if (*s == '\n') { 281 PUTC('\r'); 282 } else if (((*s & 0x80) && *s < 0xA0) || 283 /* disable upper controls */ 284 (!isprint(*s) && !isspace(*s) && 285 *s != '\a' && *s != '\b') 286 ) { 287 if (*s & 0x80) { 288 *s &= ~0x80; 289 PUTC('M'); 290 PUTC('-'); 291 } 292 if (iscntrl(*s)) { 293 *s ^= 0x40; 294 PUTC('^'); 295 } 296 } 297 PUTC(*s); 298 } 299 return; 300 #undef PUTC 301 } 302