1 /* $OpenBSD: client.c,v 1.85 2014/10/20 23:27:14 nicm Exp $ */ 2 3 /* 4 * Copyright (c) 2007 Nicholas Marriott <nicm@users.sourceforge.net> 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 <signal.h> 30 #include <stdlib.h> 31 #include <string.h> 32 #include <unistd.h> 33 34 #include "tmux.h" 35 36 struct imsgbuf client_ibuf; 37 struct event client_event; 38 struct event client_stdin; 39 enum { 40 CLIENT_EXIT_NONE, 41 CLIENT_EXIT_DETACHED, 42 CLIENT_EXIT_DETACHED_HUP, 43 CLIENT_EXIT_LOST_TTY, 44 CLIENT_EXIT_TERMINATED, 45 CLIENT_EXIT_LOST_SERVER, 46 CLIENT_EXIT_EXITED, 47 CLIENT_EXIT_SERVER_EXITED, 48 } client_exitreason = CLIENT_EXIT_NONE; 49 int client_exitval; 50 enum msgtype client_exittype; 51 const char *client_exitsession; 52 int client_attached; 53 54 int client_get_lock(char *); 55 int client_connect(char *, int); 56 void client_send_identify(int); 57 int client_write_one(enum msgtype, int, const void *, size_t); 58 int client_write_server(enum msgtype, const void *, size_t); 59 void client_update_event(void); 60 void client_signal(int, short, void *); 61 void client_stdin_callback(int, short, void *); 62 void client_write(int, const char *, size_t); 63 void client_callback(int, short, void *); 64 int client_dispatch_attached(void); 65 int client_dispatch_wait(void *); 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 -1 to 71 * retry. Ignore other errors - just continue and start the server without the 72 * lock. 73 */ 74 int 75 client_get_lock(char *lockfile) 76 { 77 int lockfd; 78 79 if ((lockfd = open(lockfile, O_WRONLY|O_CREAT, 0600)) == -1) 80 fatal("open failed"); 81 log_debug("lock file is %s", lockfile); 82 83 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) { 84 log_debug("flock failed: %s", strerror(errno)); 85 if (errno != EAGAIN) 86 return (lockfd); 87 while (flock(lockfd, LOCK_EX) == -1 && errno == EINTR) 88 /* nothing */; 89 close(lockfd); 90 return (-1); 91 } 92 log_debug("flock succeeded"); 93 94 return (lockfd); 95 } 96 97 /* Connect client to server. */ 98 int 99 client_connect(char *path, int start_server) 100 { 101 struct sockaddr_un sa; 102 size_t size; 103 int fd, lockfd = -1, locked = 0; 104 char *lockfile = NULL; 105 106 memset(&sa, 0, sizeof sa); 107 sa.sun_family = AF_UNIX; 108 size = strlcpy(sa.sun_path, path, sizeof sa.sun_path); 109 if (size >= sizeof sa.sun_path) { 110 errno = ENAMETOOLONG; 111 return (-1); 112 } 113 log_debug("socket is %s", path); 114 115 retry: 116 if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) 117 fatal("socket failed"); 118 119 log_debug("trying connect"); 120 if (connect(fd, (struct sockaddr *) &sa, SUN_LEN(&sa)) == -1) { 121 log_debug("connect failed: %s", strerror(errno)); 122 if (errno != ECONNREFUSED && errno != ENOENT) 123 goto failed; 124 if (!start_server) 125 goto failed; 126 close(fd); 127 128 if (!locked) { 129 xasprintf(&lockfile, "%s.lock", path); 130 if ((lockfd = client_get_lock(lockfile)) == -1) { 131 log_debug("didn't get lock"); 132 free(lockfile); 133 goto retry; 134 } 135 log_debug("got lock"); 136 137 /* 138 * Always retry at least once, even if we got the lock, 139 * because another client could have taken the lock, 140 * started the server and released the lock between our 141 * connect() and flock(). 142 */ 143 locked = 1; 144 goto retry; 145 } 146 147 if (unlink(path) != 0 && errno != ENOENT) { 148 free(lockfile); 149 close(lockfd); 150 return (-1); 151 } 152 fd = server_start(lockfd, lockfile); 153 } 154 if (locked) { 155 free(lockfile); 156 close(lockfd); 157 } 158 159 setblocking(fd, 0); 160 return (fd); 161 162 failed: 163 close(fd); 164 return (-1); 165 } 166 167 /* Get exit string from reason number. */ 168 const char * 169 client_exit_message(void) 170 { 171 static char msg[256]; 172 173 switch (client_exitreason) { 174 case CLIENT_EXIT_NONE: 175 break; 176 case CLIENT_EXIT_DETACHED: 177 if (client_exitsession != NULL) { 178 xsnprintf(msg, sizeof msg, "detached " 179 "(from session %s)", client_exitsession); 180 return (msg); 181 } 182 return ("detached"); 183 case CLIENT_EXIT_DETACHED_HUP: 184 if (client_exitsession != NULL) { 185 xsnprintf(msg, sizeof msg, "detached and SIGHUP " 186 "(from session %s)", client_exitsession); 187 return (msg); 188 } 189 return ("detached and SIGHUP"); 190 case CLIENT_EXIT_LOST_TTY: 191 return ("lost tty"); 192 case CLIENT_EXIT_TERMINATED: 193 return ("terminated"); 194 case CLIENT_EXIT_LOST_SERVER: 195 return ("lost server"); 196 case CLIENT_EXIT_EXITED: 197 return ("exited"); 198 case CLIENT_EXIT_SERVER_EXITED: 199 return ("server exited"); 200 } 201 return ("unknown reason"); 202 } 203 204 /* Client main loop. */ 205 int 206 client_main(int argc, char **argv, int flags) 207 { 208 struct cmd *cmd; 209 struct cmd_list *cmdlist; 210 struct msg_command_data *data; 211 int cmdflags, fd, i; 212 pid_t ppid; 213 enum msgtype msg; 214 char *cause; 215 struct termios tio, saved_tio; 216 size_t size; 217 218 /* Set up the initial command. */ 219 cmdflags = 0; 220 if (shell_cmd != NULL) { 221 msg = MSG_SHELL; 222 cmdflags = CMD_STARTSERVER; 223 } else if (argc == 0) { 224 msg = MSG_COMMAND; 225 cmdflags = CMD_STARTSERVER|CMD_CANTNEST; 226 } else { 227 msg = MSG_COMMAND; 228 229 /* 230 * It sucks parsing the command string twice (in client and 231 * later in server) but it is necessary to get the start server 232 * flag. 233 */ 234 cmdlist = cmd_list_parse(argc, argv, NULL, 0, &cause); 235 if (cmdlist == NULL) { 236 fprintf(stderr, "%s\n", cause); 237 return (1); 238 } 239 cmdflags &= ~CMD_STARTSERVER; 240 TAILQ_FOREACH(cmd, &cmdlist->list, qentry) { 241 if (cmd->entry->flags & CMD_STARTSERVER) 242 cmdflags |= CMD_STARTSERVER; 243 if (cmd->entry->flags & CMD_CANTNEST) 244 cmdflags |= CMD_CANTNEST; 245 } 246 cmd_list_free(cmdlist); 247 } 248 249 /* 250 * Check if this could be a nested session, if the command can't nest: 251 * if the socket path matches $TMUX, this is probably the same server. 252 */ 253 if (shell_cmd == NULL && environ_path != NULL && 254 (cmdflags & CMD_CANTNEST) && 255 strcmp(socket_path, environ_path) == 0) { 256 fprintf(stderr, "sessions should be nested with care, " 257 "unset $TMUX to force\n"); 258 return (1); 259 } 260 261 /* Set process title, log and signals now this is the client. */ 262 setproctitle("client (%s)", socket_path); 263 logfile("client"); 264 265 /* Initialize the client socket and start the server. */ 266 fd = client_connect(socket_path, cmdflags & CMD_STARTSERVER); 267 if (fd == -1) { 268 fprintf(stderr, "failed to connect to server: %s\n", 269 strerror(errno)); 270 return (1); 271 } 272 273 /* Create imsg. */ 274 imsg_init(&client_ibuf, fd); 275 event_set(&client_event, fd, EV_READ, client_callback, shell_cmd); 276 277 /* Create stdin handler. */ 278 setblocking(STDIN_FILENO, 0); 279 event_set(&client_stdin, STDIN_FILENO, EV_READ|EV_PERSIST, 280 client_stdin_callback, NULL); 281 if (flags & CLIENT_CONTROLCONTROL) { 282 if (tcgetattr(STDIN_FILENO, &saved_tio) != 0) { 283 fprintf(stderr, "tcgetattr failed: %s\n", 284 strerror(errno)); 285 return (1); 286 } 287 cfmakeraw(&tio); 288 tio.c_iflag = ICRNL|IXANY; 289 tio.c_oflag = OPOST|ONLCR; 290 tio.c_lflag = NOKERNINFO; 291 tio.c_cflag = CREAD|CS8|HUPCL; 292 tio.c_cc[VMIN] = 1; 293 tio.c_cc[VTIME] = 0; 294 cfsetispeed(&tio, cfgetispeed(&saved_tio)); 295 cfsetospeed(&tio, cfgetospeed(&saved_tio)); 296 tcsetattr(STDIN_FILENO, TCSANOW, &tio); 297 } 298 299 /* Establish signal handlers. */ 300 set_signals(client_signal); 301 302 /* Send identify messages. */ 303 client_send_identify(flags); 304 305 /* Send first command. */ 306 if (msg == MSG_COMMAND) { 307 /* How big is the command? */ 308 size = 0; 309 for (i = 0; i < argc; i++) 310 size += strlen(argv[i]) + 1; 311 data = xmalloc((sizeof *data) + size); 312 313 /* Prepare command for server. */ 314 data->argc = argc; 315 if (cmd_pack_argv(argc, argv, (char *)(data + 1), size) != 0) { 316 fprintf(stderr, "command too long\n"); 317 free(data); 318 return (1); 319 } 320 size += sizeof *data; 321 322 /* Send the command. */ 323 if (client_write_server(msg, data, size) != 0) { 324 fprintf(stderr, "failed to send command\n"); 325 free(data); 326 return (1); 327 } 328 free(data); 329 } else if (msg == MSG_SHELL) 330 client_write_server(msg, NULL, 0); 331 332 /* Set the event and dispatch. */ 333 client_update_event(); 334 event_dispatch(); 335 336 /* Print the exit message, if any, and exit. */ 337 if (client_attached) { 338 if (client_exitreason != CLIENT_EXIT_NONE && !login_shell) 339 printf("[%s]\n", client_exit_message()); 340 341 ppid = getppid(); 342 if (client_exittype == MSG_DETACHKILL && ppid > 1) 343 kill(ppid, SIGHUP); 344 } else if (flags & CLIENT_CONTROLCONTROL) { 345 if (client_exitreason != CLIENT_EXIT_NONE) 346 printf("%%exit %s\n", client_exit_message()); 347 else 348 printf("%%exit\n"); 349 printf("\033\\"); 350 tcsetattr(STDOUT_FILENO, TCSAFLUSH, &saved_tio); 351 } 352 setblocking(STDIN_FILENO, 1); 353 return (client_exitval); 354 } 355 356 /* Send identify messages to server. */ 357 void 358 client_send_identify(int flags) 359 { 360 const char *s; 361 char **ss; 362 int fd; 363 364 client_write_one(MSG_IDENTIFY_FLAGS, -1, &flags, sizeof flags); 365 366 if ((s = getenv("TERM")) == NULL) 367 s = ""; 368 client_write_one(MSG_IDENTIFY_TERM, -1, s, strlen(s) + 1); 369 370 if ((s = ttyname(STDIN_FILENO)) == NULL) 371 s = ""; 372 client_write_one(MSG_IDENTIFY_TTYNAME, -1, s, strlen(s) + 1); 373 374 if ((fd = open(".", O_RDONLY)) == -1) 375 fd = open("/", O_RDONLY); 376 client_write_one(MSG_IDENTIFY_CWD, fd, NULL, 0); 377 378 if ((fd = dup(STDIN_FILENO)) == -1) 379 fatal("dup failed"); 380 client_write_one(MSG_IDENTIFY_STDIN, fd, NULL, 0); 381 382 for (ss = environ; *ss != NULL; ss++) 383 client_write_one(MSG_IDENTIFY_ENVIRON, -1, *ss, strlen(*ss) + 1); 384 385 client_write_one(MSG_IDENTIFY_DONE, -1, NULL, 0); 386 387 client_update_event(); 388 } 389 390 /* Helper to send one message. */ 391 int 392 client_write_one(enum msgtype type, int fd, const void *buf, size_t len) 393 { 394 int retval; 395 396 retval = imsg_compose(&client_ibuf, type, PROTOCOL_VERSION, -1, fd, 397 (void *)buf, len); 398 if (retval != 1) 399 return (-1); 400 return (0); 401 } 402 403 /* Write a message to the server without a file descriptor. */ 404 int 405 client_write_server(enum msgtype type, const void *buf, size_t len) 406 { 407 int retval; 408 409 retval = client_write_one(type, -1, buf, len); 410 if (retval == 0) 411 client_update_event(); 412 return (retval); 413 } 414 415 /* Update client event based on whether it needs to read or read and write. */ 416 void 417 client_update_event(void) 418 { 419 short events; 420 421 event_del(&client_event); 422 events = EV_READ; 423 if (client_ibuf.w.queued > 0) 424 events |= EV_WRITE; 425 event_set( 426 &client_event, client_ibuf.fd, events, client_callback, shell_cmd); 427 event_add(&client_event, NULL); 428 } 429 430 /* Callback to handle signals in the client. */ 431 void 432 client_signal(int sig, unused short events, unused void *data) 433 { 434 struct sigaction sigact; 435 int status; 436 437 if (sig == SIGCHLD) 438 waitpid(WAIT_ANY, &status, WNOHANG); 439 else if (!client_attached) { 440 if (sig == SIGTERM) 441 event_loopexit(NULL); 442 } else { 443 switch (sig) { 444 case SIGHUP: 445 client_exitreason = CLIENT_EXIT_LOST_TTY; 446 client_exitval = 1; 447 client_write_server(MSG_EXITING, NULL, 0); 448 break; 449 case SIGTERM: 450 client_exitreason = CLIENT_EXIT_TERMINATED; 451 client_exitval = 1; 452 client_write_server(MSG_EXITING, NULL, 0); 453 break; 454 case SIGWINCH: 455 client_write_server(MSG_RESIZE, NULL, 0); 456 break; 457 case SIGCONT: 458 memset(&sigact, 0, sizeof sigact); 459 sigemptyset(&sigact.sa_mask); 460 sigact.sa_flags = SA_RESTART; 461 sigact.sa_handler = SIG_IGN; 462 if (sigaction(SIGTSTP, &sigact, NULL) != 0) 463 fatal("sigaction failed"); 464 client_write_server(MSG_WAKEUP, NULL, 0); 465 break; 466 } 467 } 468 469 client_update_event(); 470 } 471 472 /* Callback for client imsg read events. */ 473 void 474 client_callback(unused int fd, short events, void *data) 475 { 476 ssize_t n; 477 int retval; 478 479 if (events & EV_READ) { 480 if ((n = imsg_read(&client_ibuf)) == -1 || n == 0) 481 goto lost_server; 482 if (client_attached) 483 retval = client_dispatch_attached(); 484 else 485 retval = client_dispatch_wait(data); 486 if (retval != 0) { 487 event_loopexit(NULL); 488 return; 489 } 490 } 491 492 if (events & EV_WRITE) { 493 if (msgbuf_write(&client_ibuf.w) <= 0 && errno != EAGAIN) 494 goto lost_server; 495 } 496 497 client_update_event(); 498 return; 499 500 lost_server: 501 client_exitreason = CLIENT_EXIT_LOST_SERVER; 502 client_exitval = 1; 503 event_loopexit(NULL); 504 } 505 506 /* Callback for client stdin read events. */ 507 void 508 client_stdin_callback(unused int fd, unused short events, unused void *data1) 509 { 510 struct msg_stdin_data data; 511 512 data.size = read(STDIN_FILENO, data.data, sizeof data.data); 513 if (data.size < 0 && (errno == EINTR || errno == EAGAIN)) 514 return; 515 516 client_write_server(MSG_STDIN, &data, sizeof data); 517 if (data.size <= 0) 518 event_del(&client_stdin); 519 client_update_event(); 520 } 521 522 /* Force write to file descriptor. */ 523 void 524 client_write(int fd, const char *data, size_t size) 525 { 526 ssize_t used; 527 528 while (size != 0) { 529 used = write(fd, data, size); 530 if (used == -1) { 531 if (errno == EINTR || errno == EAGAIN) 532 continue; 533 break; 534 } 535 data += used; 536 size -= used; 537 } 538 } 539 540 /* Dispatch imsgs when in wait state (before MSG_READY). */ 541 int 542 client_dispatch_wait(void *data0) 543 { 544 struct imsg imsg; 545 char *data; 546 ssize_t n, datalen; 547 struct msg_stdout_data stdoutdata; 548 struct msg_stderr_data stderrdata; 549 int retval; 550 551 for (;;) { 552 if ((n = imsg_get(&client_ibuf, &imsg)) == -1) 553 fatalx("imsg_get failed"); 554 if (n == 0) 555 return (0); 556 557 data = imsg.data; 558 datalen = imsg.hdr.len - IMSG_HEADER_SIZE; 559 560 log_debug("got %d from server", imsg.hdr.type); 561 switch (imsg.hdr.type) { 562 case MSG_EXIT: 563 case MSG_SHUTDOWN: 564 if (datalen != sizeof retval && datalen != 0) 565 fatalx("bad MSG_EXIT size"); 566 if (datalen == sizeof retval) { 567 memcpy(&retval, data, sizeof retval); 568 client_exitval = retval; 569 } 570 imsg_free(&imsg); 571 return (-1); 572 case MSG_READY: 573 if (datalen != 0) 574 fatalx("bad MSG_READY size"); 575 576 event_del(&client_stdin); 577 client_attached = 1; 578 client_write_server(MSG_RESIZE, NULL, 0); 579 break; 580 case MSG_STDIN: 581 if (datalen != 0) 582 fatalx("bad MSG_STDIN size"); 583 584 event_add(&client_stdin, NULL); 585 break; 586 case MSG_STDOUT: 587 if (datalen != sizeof stdoutdata) 588 fatalx("bad MSG_STDOUT size"); 589 memcpy(&stdoutdata, data, sizeof stdoutdata); 590 591 client_write(STDOUT_FILENO, stdoutdata.data, 592 stdoutdata.size); 593 break; 594 case MSG_STDERR: 595 if (datalen != sizeof stderrdata) 596 fatalx("bad MSG_STDERR size"); 597 memcpy(&stderrdata, data, sizeof stderrdata); 598 599 client_write(STDERR_FILENO, stderrdata.data, 600 stderrdata.size); 601 break; 602 case MSG_VERSION: 603 if (datalen != 0) 604 fatalx("bad MSG_VERSION size"); 605 606 fprintf(stderr, "protocol version mismatch " 607 "(client %u, server %u)\n", PROTOCOL_VERSION, 608 imsg.hdr.peerid); 609 client_exitval = 1; 610 611 imsg_free(&imsg); 612 return (-1); 613 case MSG_SHELL: 614 if (datalen == 0 || data[datalen - 1] != '\0') 615 fatalx("bad MSG_SHELL string"); 616 617 clear_signals(0); 618 shell_exec(data, data0); 619 /* NOTREACHED */ 620 case MSG_DETACH: 621 case MSG_DETACHKILL: 622 client_write_server(MSG_EXITING, NULL, 0); 623 break; 624 case MSG_EXITED: 625 imsg_free(&imsg); 626 return (-1); 627 } 628 629 imsg_free(&imsg); 630 } 631 } 632 633 /* Dispatch imsgs in attached state (after MSG_READY). */ 634 int 635 client_dispatch_attached(void) 636 { 637 struct imsg imsg; 638 struct sigaction sigact; 639 char *data; 640 ssize_t n, datalen; 641 642 for (;;) { 643 if ((n = imsg_get(&client_ibuf, &imsg)) == -1) 644 fatalx("imsg_get failed"); 645 if (n == 0) 646 return (0); 647 648 data = imsg.data; 649 datalen = imsg.hdr.len - IMSG_HEADER_SIZE; 650 651 log_debug("got %d from server", imsg.hdr.type); 652 switch (imsg.hdr.type) { 653 case MSG_DETACH: 654 case MSG_DETACHKILL: 655 if (datalen == 0 || data[datalen - 1] != '\0') 656 fatalx("bad MSG_DETACH string"); 657 658 client_exitsession = xstrdup(data); 659 client_exittype = imsg.hdr.type; 660 if (imsg.hdr.type == MSG_DETACHKILL) 661 client_exitreason = CLIENT_EXIT_DETACHED_HUP; 662 else 663 client_exitreason = CLIENT_EXIT_DETACHED; 664 client_write_server(MSG_EXITING, NULL, 0); 665 break; 666 case MSG_EXIT: 667 if (datalen != 0 && datalen != sizeof (int)) 668 fatalx("bad MSG_EXIT size"); 669 670 client_write_server(MSG_EXITING, NULL, 0); 671 client_exitreason = CLIENT_EXIT_EXITED; 672 break; 673 case MSG_EXITED: 674 if (datalen != 0) 675 fatalx("bad MSG_EXITED size"); 676 677 imsg_free(&imsg); 678 return (-1); 679 case MSG_SHUTDOWN: 680 if (datalen != 0) 681 fatalx("bad MSG_SHUTDOWN size"); 682 683 client_write_server(MSG_EXITING, NULL, 0); 684 client_exitreason = CLIENT_EXIT_SERVER_EXITED; 685 client_exitval = 1; 686 break; 687 case MSG_SUSPEND: 688 if (datalen != 0) 689 fatalx("bad MSG_SUSPEND size"); 690 691 memset(&sigact, 0, sizeof sigact); 692 sigemptyset(&sigact.sa_mask); 693 sigact.sa_flags = SA_RESTART; 694 sigact.sa_handler = SIG_DFL; 695 if (sigaction(SIGTSTP, &sigact, NULL) != 0) 696 fatal("sigaction failed"); 697 kill(getpid(), SIGTSTP); 698 break; 699 case MSG_LOCK: 700 if (datalen == 0 || data[datalen - 1] != '\0') 701 fatalx("bad MSG_LOCK string"); 702 703 system(data); 704 client_write_server(MSG_UNLOCK, NULL, 0); 705 break; 706 } 707 708 imsg_free(&imsg); 709 } 710 } 711