1 /* $OpenBSD: client.c,v 1.113 2016/01/19 15:59:12 nicm Exp $ */ 2 3 /* 4 * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER 15 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING 16 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/types.h> 20 #include <sys/file.h> 21 #include <sys/socket.h> 22 #include <sys/stat.h> 23 #include <sys/un.h> 24 #include <sys/wait.h> 25 26 #include <errno.h> 27 #include <event.h> 28 #include <fcntl.h> 29 #include <imsg.h> 30 #include <signal.h> 31 #include <stdlib.h> 32 #include <string.h> 33 #include <unistd.h> 34 35 #include "tmux.h" 36 37 struct tmuxproc *client_proc; 38 struct tmuxpeer *client_peer; 39 int client_flags; 40 struct event client_stdin; 41 enum { 42 CLIENT_EXIT_NONE, 43 CLIENT_EXIT_DETACHED, 44 CLIENT_EXIT_DETACHED_HUP, 45 CLIENT_EXIT_LOST_TTY, 46 CLIENT_EXIT_TERMINATED, 47 CLIENT_EXIT_LOST_SERVER, 48 CLIENT_EXIT_EXITED, 49 CLIENT_EXIT_SERVER_EXITED, 50 } client_exitreason = CLIENT_EXIT_NONE; 51 int client_exitval; 52 enum msgtype client_exittype; 53 const char *client_exitsession; 54 int client_attached; 55 56 __dead void client_exec(const char *,const char *); 57 int client_get_lock(char *); 58 int client_connect(struct event_base *, const char *, int); 59 void client_send_identify(const char *, const char *); 60 void client_stdin_callback(int, short, void *); 61 void client_write(int, const char *, size_t); 62 void client_signal(int); 63 void client_dispatch(struct imsg *, void *); 64 void client_dispatch_attached(struct imsg *); 65 void client_dispatch_wait(struct imsg *, const char *); 66 const char *client_exit_message(void); 67 68 /* 69 * Get server create lock. If already held then server start is happening in 70 * another client, so block until the lock is released and return -2 to 71 * retry. Return -1 on failure to continue and start the server anyway. 72 */ 73 int 74 client_get_lock(char *lockfile) 75 { 76 int lockfd; 77 78 log_debug("lock file is %s", lockfile); 79 80 if ((lockfd = open(lockfile, O_WRONLY|O_CREAT, 0600)) == -1) { 81 log_debug("open failed: %s", strerror(errno)); 82 return (-1); 83 } 84 85 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) { 86 log_debug("flock failed: %s", strerror(errno)); 87 if (errno != EAGAIN) 88 return (lockfd); 89 while (flock(lockfd, LOCK_EX) == -1 && errno == EINTR) 90 /* nothing */; 91 close(lockfd); 92 return (-2); 93 } 94 log_debug("flock succeeded"); 95 96 return (lockfd); 97 } 98 99 /* Connect client to server. */ 100 int 101 client_connect(struct event_base *base, const char *path, int start_server) 102 { 103 struct sockaddr_un sa; 104 size_t size; 105 int fd, lockfd = -1, locked = 0; 106 char *lockfile = NULL; 107 108 memset(&sa, 0, sizeof sa); 109 sa.sun_family = AF_UNIX; 110 size = strlcpy(sa.sun_path, path, sizeof sa.sun_path); 111 if (size >= sizeof sa.sun_path) { 112 errno = ENAMETOOLONG; 113 return (-1); 114 } 115 log_debug("socket is %s", path); 116 117 retry: 118 if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) 119 return (-1); 120 121 log_debug("trying connect"); 122 if (connect(fd, (struct sockaddr *)&sa, sizeof sa) == -1) { 123 log_debug("connect failed: %s", strerror(errno)); 124 if (errno != ECONNREFUSED && errno != ENOENT) 125 goto failed; 126 if (!start_server) 127 goto failed; 128 close(fd); 129 130 if (!locked) { 131 xasprintf(&lockfile, "%s.lock", path); 132 if ((lockfd = client_get_lock(lockfile)) < 0) { 133 log_debug("didn't get lock (%d)", lockfd); 134 135 free(lockfile); 136 lockfile = NULL; 137 138 if (lockfd == -2) 139 goto retry; 140 } 141 log_debug("got lock (%d)", lockfd); 142 143 /* 144 * Always retry at least once, even if we got the lock, 145 * because another client could have taken the lock, 146 * started the server and released the lock between our 147 * connect() and flock(). 148 */ 149 locked = 1; 150 goto retry; 151 } 152 153 if (lockfd >= 0 && unlink(path) != 0 && errno != ENOENT) { 154 free(lockfile); 155 close(lockfd); 156 return (-1); 157 } 158 fd = server_start(base, lockfd, lockfile); 159 } 160 161 if (locked && lockfd >= 0) { 162 free(lockfile); 163 close(lockfd); 164 } 165 setblocking(fd, 0); 166 return (fd); 167 168 failed: 169 if (locked) { 170 free(lockfile); 171 close(lockfd); 172 } 173 close(fd); 174 return (-1); 175 } 176 177 /* Get exit string from reason number. */ 178 const char * 179 client_exit_message(void) 180 { 181 static char msg[256]; 182 183 switch (client_exitreason) { 184 case CLIENT_EXIT_NONE: 185 break; 186 case CLIENT_EXIT_DETACHED: 187 if (client_exitsession != NULL) { 188 xsnprintf(msg, sizeof msg, "detached " 189 "(from session %s)", client_exitsession); 190 return (msg); 191 } 192 return ("detached"); 193 case CLIENT_EXIT_DETACHED_HUP: 194 if (client_exitsession != NULL) { 195 xsnprintf(msg, sizeof msg, "detached and SIGHUP " 196 "(from session %s)", client_exitsession); 197 return (msg); 198 } 199 return ("detached and SIGHUP"); 200 case CLIENT_EXIT_LOST_TTY: 201 return ("lost tty"); 202 case CLIENT_EXIT_TERMINATED: 203 return ("terminated"); 204 case CLIENT_EXIT_LOST_SERVER: 205 return ("lost server"); 206 case CLIENT_EXIT_EXITED: 207 return ("exited"); 208 case CLIENT_EXIT_SERVER_EXITED: 209 return ("server exited"); 210 } 211 return ("unknown reason"); 212 } 213 214 /* Client main loop. */ 215 int 216 client_main(struct event_base *base, int argc, char **argv, int flags, 217 const char *shellcmd) 218 { 219 struct cmd *cmd; 220 struct cmd_list *cmdlist; 221 struct msg_command_data *data; 222 int cmdflags, fd, i; 223 const char *ttynam, *cwd; 224 pid_t ppid; 225 enum msgtype msg; 226 char *cause, path[PATH_MAX]; 227 struct termios tio, saved_tio; 228 size_t size; 229 230 /* Ignore SIGCHLD now or daemon() in the server will leave a zombie. */ 231 signal(SIGCHLD, SIG_IGN); 232 233 /* Save the flags. */ 234 client_flags = flags; 235 236 /* Set up the initial command. */ 237 cmdflags = 0; 238 if (shellcmd != NULL) { 239 msg = MSG_SHELL; 240 cmdflags = CMD_STARTSERVER; 241 } else if (argc == 0) { 242 msg = MSG_COMMAND; 243 cmdflags = CMD_STARTSERVER; 244 } else { 245 msg = MSG_COMMAND; 246 247 /* 248 * It sucks parsing the command string twice (in client and 249 * later in server) but it is necessary to get the start server 250 * flag. 251 */ 252 cmdlist = cmd_list_parse(argc, argv, NULL, 0, &cause); 253 if (cmdlist == NULL) { 254 fprintf(stderr, "%s\n", cause); 255 return (1); 256 } 257 cmdflags &= ~CMD_STARTSERVER; 258 TAILQ_FOREACH(cmd, &cmdlist->list, qentry) { 259 if (cmd->entry->flags & CMD_STARTSERVER) 260 cmdflags |= CMD_STARTSERVER; 261 } 262 cmd_list_free(cmdlist); 263 } 264 265 /* Create client process structure (starts logging). */ 266 client_proc = proc_start("client", base, 0, client_signal); 267 268 /* Initialize the client socket and start the server. */ 269 fd = client_connect(base, socket_path, cmdflags & CMD_STARTSERVER); 270 if (fd == -1) { 271 if (errno == ECONNREFUSED) { 272 fprintf(stderr, "no server running on %s\n", 273 socket_path); 274 } else { 275 fprintf(stderr, "error connecting to %s (%s)\n", 276 socket_path, strerror(errno)); 277 } 278 return (1); 279 } 280 client_peer = proc_add_peer(client_proc, fd, client_dispatch, 281 (void *)shellcmd); 282 283 /* Save these before pledge(). */ 284 if ((cwd = getcwd(path, sizeof path)) == NULL) { 285 if ((cwd = find_home()) == NULL) 286 cwd = "/"; 287 } 288 if ((ttynam = ttyname(STDIN_FILENO)) == NULL) 289 ttynam = ""; 290 291 /* 292 * Drop privileges for client. "proc exec" is needed for -c and for 293 * locking (which uses system(3)). 294 * 295 * "tty" is needed to restore termios(4) and also for some reason -CC 296 * does not work properly without it (input is not recognised). 297 * 298 * "sendfd" is dropped later in client_dispatch_wait(). 299 */ 300 if (pledge("stdio unix sendfd proc exec tty", NULL) != 0) 301 fatal("pledge failed"); 302 303 /* Free stuff that is not used in the client. */ 304 options_free(global_options); 305 options_free(global_s_options); 306 options_free(global_w_options); 307 environ_free(global_environ); 308 309 /* Create stdin handler. */ 310 setblocking(STDIN_FILENO, 0); 311 event_set(&client_stdin, STDIN_FILENO, EV_READ|EV_PERSIST, 312 client_stdin_callback, NULL); 313 if (client_flags & CLIENT_CONTROLCONTROL) { 314 if (tcgetattr(STDIN_FILENO, &saved_tio) != 0) 315 fatal("tcgetattr failed"); 316 cfmakeraw(&tio); 317 tio.c_iflag = ICRNL|IXANY; 318 tio.c_oflag = OPOST|ONLCR; 319 tio.c_lflag = NOKERNINFO; 320 tio.c_cflag = CREAD|CS8|HUPCL; 321 tio.c_cc[VMIN] = 1; 322 tio.c_cc[VTIME] = 0; 323 cfsetispeed(&tio, cfgetispeed(&saved_tio)); 324 cfsetospeed(&tio, cfgetospeed(&saved_tio)); 325 tcsetattr(STDIN_FILENO, TCSANOW, &tio); 326 } 327 328 /* Send identify messages. */ 329 client_send_identify(ttynam, cwd); 330 331 /* Send first command. */ 332 if (msg == MSG_COMMAND) { 333 /* How big is the command? */ 334 size = 0; 335 for (i = 0; i < argc; i++) 336 size += strlen(argv[i]) + 1; 337 data = xmalloc((sizeof *data) + size); 338 339 /* Prepare command for server. */ 340 data->argc = argc; 341 if (cmd_pack_argv(argc, argv, (char *)(data + 1), size) != 0) { 342 fprintf(stderr, "command too long\n"); 343 free(data); 344 return (1); 345 } 346 size += sizeof *data; 347 348 /* Send the command. */ 349 if (proc_send(client_peer, msg, -1, data, size) != 0) { 350 fprintf(stderr, "failed to send command\n"); 351 free(data); 352 return (1); 353 } 354 free(data); 355 } else if (msg == MSG_SHELL) 356 proc_send(client_peer, msg, -1, NULL, 0); 357 358 /* Start main loop. */ 359 proc_loop(client_proc, NULL); 360 361 /* Print the exit message, if any, and exit. */ 362 if (client_attached) { 363 if (client_exitreason != CLIENT_EXIT_NONE) 364 printf("[%s]\n", client_exit_message()); 365 366 ppid = getppid(); 367 if (client_exittype == MSG_DETACHKILL && ppid > 1) 368 kill(ppid, SIGHUP); 369 } else if (client_flags & CLIENT_CONTROLCONTROL) { 370 if (client_exitreason != CLIENT_EXIT_NONE) 371 printf("%%exit %s\n", client_exit_message()); 372 else 373 printf("%%exit\n"); 374 printf("\033\\"); 375 tcsetattr(STDOUT_FILENO, TCSAFLUSH, &saved_tio); 376 } else if (client_exitreason != CLIENT_EXIT_NONE) 377 fprintf(stderr, "%s\n", client_exit_message()); 378 setblocking(STDIN_FILENO, 1); 379 return (client_exitval); 380 } 381 382 /* Send identify messages to server. */ 383 void 384 client_send_identify(const char *ttynam, const char *cwd) 385 { 386 const char *s; 387 char **ss; 388 size_t sslen; 389 int fd, flags = client_flags; 390 pid_t pid; 391 392 proc_send(client_peer, MSG_IDENTIFY_FLAGS, -1, &flags, sizeof flags); 393 394 if ((s = getenv("TERM")) == NULL) 395 s = ""; 396 proc_send(client_peer, MSG_IDENTIFY_TERM, -1, s, strlen(s) + 1); 397 398 proc_send(client_peer, MSG_IDENTIFY_TTYNAME, -1, ttynam, 399 strlen(ttynam) + 1); 400 proc_send(client_peer, MSG_IDENTIFY_CWD, -1, cwd, strlen(cwd) + 1); 401 402 if ((fd = dup(STDIN_FILENO)) == -1) 403 fatal("dup failed"); 404 proc_send(client_peer, MSG_IDENTIFY_STDIN, fd, NULL, 0); 405 406 pid = getpid(); 407 proc_send(client_peer, MSG_IDENTIFY_CLIENTPID, -1, &pid, sizeof pid); 408 409 for (ss = environ; *ss != NULL; ss++) { 410 sslen = strlen(*ss) + 1; 411 if (sslen > MAX_IMSGSIZE - IMSG_HEADER_SIZE) 412 continue; 413 proc_send(client_peer, MSG_IDENTIFY_ENVIRON, -1, *ss, sslen); 414 } 415 416 proc_send(client_peer, MSG_IDENTIFY_DONE, -1, NULL, 0); 417 } 418 419 /* Callback for client stdin read events. */ 420 void 421 client_stdin_callback(__unused int fd, __unused short events, 422 __unused void *arg) 423 { 424 struct msg_stdin_data data; 425 426 data.size = read(STDIN_FILENO, data.data, sizeof data.data); 427 if (data.size < 0 && (errno == EINTR || errno == EAGAIN)) 428 return; 429 430 proc_send(client_peer, MSG_STDIN, -1, &data, sizeof data); 431 if (data.size <= 0) 432 event_del(&client_stdin); 433 } 434 435 /* Force write to file descriptor. */ 436 void 437 client_write(int fd, const char *data, size_t size) 438 { 439 ssize_t used; 440 441 while (size != 0) { 442 used = write(fd, data, size); 443 if (used == -1) { 444 if (errno == EINTR || errno == EAGAIN) 445 continue; 446 break; 447 } 448 data += used; 449 size -= used; 450 } 451 } 452 453 /* Run command in shell; used for -c. */ 454 __dead void 455 client_exec(const char *shell, const char *shellcmd) 456 { 457 const char *name, *ptr; 458 char *argv0; 459 460 log_debug("shell %s, command %s", shell, shellcmd); 461 462 ptr = strrchr(shell, '/'); 463 if (ptr != NULL && *(ptr + 1) != '\0') 464 name = ptr + 1; 465 else 466 name = shell; 467 if (client_flags & CLIENT_LOGIN) 468 xasprintf(&argv0, "-%s", name); 469 else 470 xasprintf(&argv0, "%s", name); 471 setenv("SHELL", shell, 1); 472 473 setblocking(STDIN_FILENO, 1); 474 setblocking(STDOUT_FILENO, 1); 475 setblocking(STDERR_FILENO, 1); 476 closefrom(STDERR_FILENO + 1); 477 478 execl(shell, argv0, "-c", shellcmd, (char *) NULL); 479 fatal("execl failed"); 480 } 481 482 /* Callback to handle signals in the client. */ 483 void 484 client_signal(int sig) 485 { 486 struct sigaction sigact; 487 int status; 488 489 if (sig == SIGCHLD) 490 waitpid(WAIT_ANY, &status, WNOHANG); 491 else if (!client_attached) { 492 if (sig == SIGTERM) 493 proc_exit(client_proc); 494 } else { 495 switch (sig) { 496 case SIGHUP: 497 client_exitreason = CLIENT_EXIT_LOST_TTY; 498 client_exitval = 1; 499 proc_send(client_peer, MSG_EXITING, -1, NULL, 0); 500 break; 501 case SIGTERM: 502 client_exitreason = CLIENT_EXIT_TERMINATED; 503 client_exitval = 1; 504 proc_send(client_peer, MSG_EXITING, -1, NULL, 0); 505 break; 506 case SIGWINCH: 507 proc_send(client_peer, MSG_RESIZE, -1, NULL, 0); 508 break; 509 case SIGCONT: 510 memset(&sigact, 0, sizeof sigact); 511 sigemptyset(&sigact.sa_mask); 512 sigact.sa_flags = SA_RESTART; 513 sigact.sa_handler = SIG_IGN; 514 if (sigaction(SIGTSTP, &sigact, NULL) != 0) 515 fatal("sigaction failed"); 516 proc_send(client_peer, MSG_WAKEUP, -1, NULL, 0); 517 break; 518 } 519 } 520 } 521 522 /* Callback for client read events. */ 523 void 524 client_dispatch(struct imsg *imsg, void *arg) 525 { 526 if (imsg == NULL) { 527 client_exitreason = CLIENT_EXIT_LOST_SERVER; 528 client_exitval = 1; 529 proc_exit(client_proc); 530 return; 531 } 532 533 if (client_attached) 534 client_dispatch_attached(imsg); 535 else 536 client_dispatch_wait(imsg, arg); 537 } 538 539 /* Dispatch imsgs when in wait state (before MSG_READY). */ 540 void 541 client_dispatch_wait(struct imsg *imsg, const char *shellcmd) 542 { 543 char *data; 544 ssize_t datalen; 545 struct msg_stdout_data stdoutdata; 546 struct msg_stderr_data stderrdata; 547 int retval; 548 static int pledge_applied; 549 550 /* 551 * "sendfd" is no longer required once all of the identify messages 552 * have been sent. We know the server won't send us anything until that 553 * point (because we don't ask it to), so we can drop "sendfd" once we 554 * get the first message from the server. 555 */ 556 if (!pledge_applied) { 557 if (pledge("stdio unix proc exec tty", NULL) != 0) 558 fatal("pledge failed"); 559 pledge_applied = 1; 560 }; 561 562 data = imsg->data; 563 datalen = imsg->hdr.len - IMSG_HEADER_SIZE; 564 565 switch (imsg->hdr.type) { 566 case MSG_EXIT: 567 case MSG_SHUTDOWN: 568 if (datalen != sizeof retval && datalen != 0) 569 fatalx("bad MSG_EXIT size"); 570 if (datalen == sizeof retval) { 571 memcpy(&retval, data, sizeof retval); 572 client_exitval = retval; 573 } 574 proc_exit(client_proc); 575 break; 576 case MSG_READY: 577 if (datalen != 0) 578 fatalx("bad MSG_READY size"); 579 580 event_del(&client_stdin); 581 client_attached = 1; 582 proc_send(client_peer, MSG_RESIZE, -1, NULL, 0); 583 break; 584 case MSG_STDIN: 585 if (datalen != 0) 586 fatalx("bad MSG_STDIN size"); 587 588 event_add(&client_stdin, NULL); 589 break; 590 case MSG_STDOUT: 591 if (datalen != sizeof stdoutdata) 592 fatalx("bad MSG_STDOUT size"); 593 memcpy(&stdoutdata, data, sizeof stdoutdata); 594 595 client_write(STDOUT_FILENO, stdoutdata.data, 596 stdoutdata.size); 597 break; 598 case MSG_STDERR: 599 if (datalen != sizeof stderrdata) 600 fatalx("bad MSG_STDERR size"); 601 memcpy(&stderrdata, data, sizeof stderrdata); 602 603 client_write(STDERR_FILENO, stderrdata.data, 604 stderrdata.size); 605 break; 606 case MSG_VERSION: 607 if (datalen != 0) 608 fatalx("bad MSG_VERSION size"); 609 610 fprintf(stderr, "protocol version mismatch " 611 "(client %d, server %u)\n", PROTOCOL_VERSION, 612 imsg->hdr.peerid & 0xff); 613 client_exitval = 1; 614 proc_exit(client_proc); 615 break; 616 case MSG_SHELL: 617 if (datalen == 0 || data[datalen - 1] != '\0') 618 fatalx("bad MSG_SHELL string"); 619 620 clear_signals(0); 621 client_exec(data, shellcmd); 622 /* NOTREACHED */ 623 case MSG_DETACH: 624 case MSG_DETACHKILL: 625 proc_send(client_peer, MSG_EXITING, -1, NULL, 0); 626 break; 627 case MSG_EXITED: 628 proc_exit(client_proc); 629 break; 630 } 631 } 632 633 /* Dispatch imsgs in attached state (after MSG_READY). */ 634 void 635 client_dispatch_attached(struct imsg *imsg) 636 { 637 struct sigaction sigact; 638 char *data; 639 ssize_t datalen; 640 641 data = imsg->data; 642 datalen = imsg->hdr.len - IMSG_HEADER_SIZE; 643 644 switch (imsg->hdr.type) { 645 case MSG_DETACH: 646 case MSG_DETACHKILL: 647 if (datalen == 0 || data[datalen - 1] != '\0') 648 fatalx("bad MSG_DETACH string"); 649 650 client_exitsession = xstrdup(data); 651 client_exittype = imsg->hdr.type; 652 if (imsg->hdr.type == MSG_DETACHKILL) 653 client_exitreason = CLIENT_EXIT_DETACHED_HUP; 654 else 655 client_exitreason = CLIENT_EXIT_DETACHED; 656 proc_send(client_peer, MSG_EXITING, -1, NULL, 0); 657 break; 658 case MSG_EXIT: 659 if (datalen != 0 && datalen != sizeof (int)) 660 fatalx("bad MSG_EXIT size"); 661 662 proc_send(client_peer, MSG_EXITING, -1, NULL, 0); 663 client_exitreason = CLIENT_EXIT_EXITED; 664 break; 665 case MSG_EXITED: 666 if (datalen != 0) 667 fatalx("bad MSG_EXITED size"); 668 669 proc_exit(client_proc); 670 break; 671 case MSG_SHUTDOWN: 672 if (datalen != 0) 673 fatalx("bad MSG_SHUTDOWN size"); 674 675 proc_send(client_peer, MSG_EXITING, -1, NULL, 0); 676 client_exitreason = CLIENT_EXIT_SERVER_EXITED; 677 client_exitval = 1; 678 break; 679 case MSG_SUSPEND: 680 if (datalen != 0) 681 fatalx("bad MSG_SUSPEND size"); 682 683 memset(&sigact, 0, sizeof sigact); 684 sigemptyset(&sigact.sa_mask); 685 sigact.sa_flags = SA_RESTART; 686 sigact.sa_handler = SIG_DFL; 687 if (sigaction(SIGTSTP, &sigact, NULL) != 0) 688 fatal("sigaction failed"); 689 kill(getpid(), SIGTSTP); 690 break; 691 case MSG_LOCK: 692 if (datalen == 0 || data[datalen - 1] != '\0') 693 fatalx("bad MSG_LOCK string"); 694 695 system(data); 696 proc_send(client_peer, MSG_UNLOCK, -1, NULL, 0); 697 break; 698 } 699 } 700