1 /* 2 * Author: Tatu Ylonen <ylo@cs.hut.fi> 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 4 * All rights reserved 5 * Server main loop for handling the interactive session. 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * SSH2 support by Markus Friedl. 14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36 37 #include "includes.h" 38 RCSID("$OpenBSD: serverloop.c,v 1.77 2001/09/17 21:04:02 markus Exp $"); 39 40 #include "xmalloc.h" 41 #include "packet.h" 42 #include "buffer.h" 43 #include "log.h" 44 #include "servconf.h" 45 #include "sshpty.h" 46 #include "channels.h" 47 #include "compat.h" 48 #include "ssh1.h" 49 #include "ssh2.h" 50 #include "auth.h" 51 #include "session.h" 52 #include "dispatch.h" 53 #include "auth-options.h" 54 #include "serverloop.h" 55 #include "misc.h" 56 #include "kex.h" 57 58 extern ServerOptions options; 59 60 /* XXX */ 61 extern Kex *xxx_kex; 62 static Authctxt *xxx_authctxt; 63 64 static Buffer stdin_buffer; /* Buffer for stdin data. */ 65 static Buffer stdout_buffer; /* Buffer for stdout data. */ 66 static Buffer stderr_buffer; /* Buffer for stderr data. */ 67 static int fdin; /* Descriptor for stdin (for writing) */ 68 static int fdout; /* Descriptor for stdout (for reading); 69 May be same number as fdin. */ 70 static int fderr; /* Descriptor for stderr. May be -1. */ 71 static long stdin_bytes = 0; /* Number of bytes written to stdin. */ 72 static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ 73 static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ 74 static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ 75 static int stdin_eof = 0; /* EOF message received from client. */ 76 static int fdout_eof = 0; /* EOF encountered reading from fdout. */ 77 static int fderr_eof = 0; /* EOF encountered readung from fderr. */ 78 static int fdin_is_tty = 0; /* fdin points to a tty. */ 79 static int connection_in; /* Connection to client (input). */ 80 static int connection_out; /* Connection to client (output). */ 81 static int connection_closed = 0; /* Connection to client closed. */ 82 static u_int buffer_high; /* "Soft" max buffer size. */ 83 84 /* 85 * This SIGCHLD kludge is used to detect when the child exits. The server 86 * will exit after that, as soon as forwarded connections have terminated. 87 */ 88 89 static volatile int child_terminated; /* The child has terminated. */ 90 91 /* prototypes */ 92 static void server_init_dispatch(void); 93 94 int client_alive_timeouts = 0; 95 96 static void 97 sigchld_handler(int sig) 98 { 99 int save_errno = errno; 100 debug("Received SIGCHLD."); 101 child_terminated = 1; 102 signal(SIGCHLD, sigchld_handler); 103 errno = save_errno; 104 } 105 106 /* 107 * Make packets from buffered stderr data, and buffer it for sending 108 * to the client. 109 */ 110 static void 111 make_packets_from_stderr_data(void) 112 { 113 int len; 114 115 /* Send buffered stderr data to the client. */ 116 while (buffer_len(&stderr_buffer) > 0 && 117 packet_not_very_much_data_to_write()) { 118 len = buffer_len(&stderr_buffer); 119 if (packet_is_interactive()) { 120 if (len > 512) 121 len = 512; 122 } else { 123 /* Keep the packets at reasonable size. */ 124 if (len > packet_get_maxsize()) 125 len = packet_get_maxsize(); 126 } 127 packet_start(SSH_SMSG_STDERR_DATA); 128 packet_put_string(buffer_ptr(&stderr_buffer), len); 129 packet_send(); 130 buffer_consume(&stderr_buffer, len); 131 stderr_bytes += len; 132 } 133 } 134 135 /* 136 * Make packets from buffered stdout data, and buffer it for sending to the 137 * client. 138 */ 139 static void 140 make_packets_from_stdout_data(void) 141 { 142 int len; 143 144 /* Send buffered stdout data to the client. */ 145 while (buffer_len(&stdout_buffer) > 0 && 146 packet_not_very_much_data_to_write()) { 147 len = buffer_len(&stdout_buffer); 148 if (packet_is_interactive()) { 149 if (len > 512) 150 len = 512; 151 } else { 152 /* Keep the packets at reasonable size. */ 153 if (len > packet_get_maxsize()) 154 len = packet_get_maxsize(); 155 } 156 packet_start(SSH_SMSG_STDOUT_DATA); 157 packet_put_string(buffer_ptr(&stdout_buffer), len); 158 packet_send(); 159 buffer_consume(&stdout_buffer, len); 160 stdout_bytes += len; 161 } 162 } 163 164 /* 165 * Sleep in select() until we can do something. This will initialize the 166 * select masks. Upon return, the masks will indicate which descriptors 167 * have data or can accept data. Optionally, a maximum time can be specified 168 * for the duration of the wait (0 = infinite). 169 */ 170 static void 171 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, 172 int *nallocp, u_int max_time_milliseconds) 173 { 174 struct timeval tv, *tvp; 175 int ret; 176 int client_alive_scheduled = 0; 177 178 /* 179 * if using client_alive, set the max timeout accordingly, 180 * and indicate that this particular timeout was for client 181 * alive by setting the client_alive_scheduled flag. 182 * 183 * this could be randomized somewhat to make traffic 184 * analysis more difficult, but we're not doing it yet. 185 */ 186 if (compat20 && 187 max_time_milliseconds == 0 && options.client_alive_interval) { 188 client_alive_scheduled = 1; 189 max_time_milliseconds = options.client_alive_interval * 1000; 190 } 191 192 /* When select fails we restart from here. */ 193 retry_select: 194 195 /* Allocate and update select() masks for channel descriptors. */ 196 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); 197 198 if (compat20) { 199 /* wrong: bad condition XXX */ 200 if (channel_not_very_much_buffered_data()) 201 FD_SET(connection_in, *readsetp); 202 } else { 203 /* 204 * Read packets from the client unless we have too much 205 * buffered stdin or channel data. 206 */ 207 if (buffer_len(&stdin_buffer) < buffer_high && 208 channel_not_very_much_buffered_data()) 209 FD_SET(connection_in, *readsetp); 210 /* 211 * If there is not too much data already buffered going to 212 * the client, try to get some more data from the program. 213 */ 214 if (packet_not_very_much_data_to_write()) { 215 if (!fdout_eof) 216 FD_SET(fdout, *readsetp); 217 if (!fderr_eof) 218 FD_SET(fderr, *readsetp); 219 } 220 /* 221 * If we have buffered data, try to write some of that data 222 * to the program. 223 */ 224 if (fdin != -1 && buffer_len(&stdin_buffer) > 0) 225 FD_SET(fdin, *writesetp); 226 } 227 228 /* 229 * If we have buffered packet data going to the client, mark that 230 * descriptor. 231 */ 232 if (packet_have_data_to_write()) 233 FD_SET(connection_out, *writesetp); 234 235 /* 236 * If child has terminated and there is enough buffer space to read 237 * from it, then read as much as is available and exit. 238 */ 239 if (child_terminated && packet_not_very_much_data_to_write()) 240 if (max_time_milliseconds == 0 || client_alive_scheduled) 241 max_time_milliseconds = 100; 242 243 if (max_time_milliseconds == 0) 244 tvp = NULL; 245 else { 246 tv.tv_sec = max_time_milliseconds / 1000; 247 tv.tv_usec = 1000 * (max_time_milliseconds % 1000); 248 tvp = &tv; 249 } 250 if (tvp!=NULL) 251 debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds); 252 253 /* Wait for something to happen, or the timeout to expire. */ 254 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); 255 256 if (ret == -1) { 257 if (errno != EINTR) 258 error("select: %.100s", strerror(errno)); 259 else 260 goto retry_select; 261 } 262 if (ret == 0 && client_alive_scheduled) { 263 /* timeout, check to see how many we have had */ 264 client_alive_timeouts++; 265 266 if (client_alive_timeouts > options.client_alive_count_max ) { 267 packet_disconnect( 268 "Timeout, your session not responding."); 269 } else { 270 /* 271 * send a bogus channel request with "wantreply" 272 * we should get back a failure 273 */ 274 int id; 275 276 id = channel_find_open(); 277 if (id != -1) { 278 channel_request_start(id, 279 "keepalive@openssh.com", 1); 280 packet_send(); 281 } else 282 packet_disconnect( 283 "No open channels after timeout!"); 284 } 285 } 286 } 287 288 /* 289 * Processes input from the client and the program. Input data is stored 290 * in buffers and processed later. 291 */ 292 static void 293 process_input(fd_set * readset) 294 { 295 int len; 296 char buf[16384]; 297 298 /* Read and buffer any input data from the client. */ 299 if (FD_ISSET(connection_in, readset)) { 300 len = read(connection_in, buf, sizeof(buf)); 301 if (len == 0) { 302 verbose("Connection closed by remote host."); 303 connection_closed = 1; 304 if (compat20) 305 return; 306 fatal_cleanup(); 307 } else if (len < 0) { 308 if (errno != EINTR && errno != EAGAIN) { 309 verbose("Read error from remote host: %.100s", strerror(errno)); 310 fatal_cleanup(); 311 } 312 } else { 313 /* Buffer any received data. */ 314 packet_process_incoming(buf, len); 315 } 316 } 317 if (compat20) 318 return; 319 320 /* Read and buffer any available stdout data from the program. */ 321 if (!fdout_eof && FD_ISSET(fdout, readset)) { 322 len = read(fdout, buf, sizeof(buf)); 323 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 324 /* do nothing */ 325 } else if (len <= 0) { 326 fdout_eof = 1; 327 } else { 328 buffer_append(&stdout_buffer, buf, len); 329 fdout_bytes += len; 330 } 331 } 332 /* Read and buffer any available stderr data from the program. */ 333 if (!fderr_eof && FD_ISSET(fderr, readset)) { 334 len = read(fderr, buf, sizeof(buf)); 335 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 336 /* do nothing */ 337 } else if (len <= 0) { 338 fderr_eof = 1; 339 } else { 340 buffer_append(&stderr_buffer, buf, len); 341 } 342 } 343 } 344 345 /* 346 * Sends data from internal buffers to client program stdin. 347 */ 348 static void 349 process_output(fd_set * writeset) 350 { 351 struct termios tio; 352 u_char *data; 353 u_int dlen; 354 int len; 355 356 /* Write buffered data to program stdin. */ 357 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { 358 data = buffer_ptr(&stdin_buffer); 359 dlen = buffer_len(&stdin_buffer); 360 len = write(fdin, data, dlen); 361 if (len < 0 && (errno == EINTR || errno == EAGAIN)) { 362 /* do nothing */ 363 } else if (len <= 0) { 364 #ifdef USE_PIPES 365 close(fdin); 366 #else 367 if (fdin != fdout) 368 close(fdin); 369 else 370 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 371 #endif 372 fdin = -1; 373 } else { 374 /* Successful write. */ 375 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && 376 tcgetattr(fdin, &tio) == 0 && 377 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { 378 /* 379 * Simulate echo to reduce the impact of 380 * traffic analysis 381 */ 382 packet_send_ignore(len); 383 packet_send(); 384 } 385 /* Consume the data from the buffer. */ 386 buffer_consume(&stdin_buffer, len); 387 /* Update the count of bytes written to the program. */ 388 stdin_bytes += len; 389 } 390 } 391 /* Send any buffered packet data to the client. */ 392 if (FD_ISSET(connection_out, writeset)) 393 packet_write_poll(); 394 } 395 396 /* 397 * Wait until all buffered output has been sent to the client. 398 * This is used when the program terminates. 399 */ 400 static void 401 drain_output(void) 402 { 403 /* Send any buffered stdout data to the client. */ 404 if (buffer_len(&stdout_buffer) > 0) { 405 packet_start(SSH_SMSG_STDOUT_DATA); 406 packet_put_string(buffer_ptr(&stdout_buffer), 407 buffer_len(&stdout_buffer)); 408 packet_send(); 409 /* Update the count of sent bytes. */ 410 stdout_bytes += buffer_len(&stdout_buffer); 411 } 412 /* Send any buffered stderr data to the client. */ 413 if (buffer_len(&stderr_buffer) > 0) { 414 packet_start(SSH_SMSG_STDERR_DATA); 415 packet_put_string(buffer_ptr(&stderr_buffer), 416 buffer_len(&stderr_buffer)); 417 packet_send(); 418 /* Update the count of sent bytes. */ 419 stderr_bytes += buffer_len(&stderr_buffer); 420 } 421 /* Wait until all buffered data has been written to the client. */ 422 packet_write_wait(); 423 } 424 425 static void 426 process_buffered_input_packets(void) 427 { 428 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); 429 } 430 431 /* 432 * Performs the interactive session. This handles data transmission between 433 * the client and the program. Note that the notion of stdin, stdout, and 434 * stderr in this function is sort of reversed: this function writes to 435 * stdin (of the child program), and reads from stdout and stderr (of the 436 * child program). 437 */ 438 void 439 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) 440 { 441 fd_set *readset = NULL, *writeset = NULL; 442 int max_fd = 0, nalloc = 0; 443 int wait_status; /* Status returned by wait(). */ 444 pid_t wait_pid; /* pid returned by wait(). */ 445 int waiting_termination = 0; /* Have displayed waiting close message. */ 446 u_int max_time_milliseconds; 447 u_int previous_stdout_buffer_bytes; 448 u_int stdout_buffer_bytes; 449 int type; 450 451 debug("Entering interactive session."); 452 453 /* Initialize the SIGCHLD kludge. */ 454 child_terminated = 0; 455 signal(SIGCHLD, sigchld_handler); 456 457 /* Initialize our global variables. */ 458 fdin = fdin_arg; 459 fdout = fdout_arg; 460 fderr = fderr_arg; 461 462 /* nonblocking IO */ 463 set_nonblock(fdin); 464 set_nonblock(fdout); 465 /* we don't have stderr for interactive terminal sessions, see below */ 466 if (fderr != -1) 467 set_nonblock(fderr); 468 469 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) 470 fdin_is_tty = 1; 471 472 connection_in = packet_get_connection_in(); 473 connection_out = packet_get_connection_out(); 474 475 previous_stdout_buffer_bytes = 0; 476 477 /* Set approximate I/O buffer size. */ 478 if (packet_is_interactive()) 479 buffer_high = 4096; 480 else 481 buffer_high = 64 * 1024; 482 483 #if 0 484 /* Initialize max_fd to the maximum of the known file descriptors. */ 485 max_fd = MAX(connection_in, connection_out); 486 max_fd = MAX(max_fd, fdin); 487 max_fd = MAX(max_fd, fdout); 488 if (fderr != -1) 489 max_fd = MAX(max_fd, fderr); 490 #endif 491 492 /* Initialize Initialize buffers. */ 493 buffer_init(&stdin_buffer); 494 buffer_init(&stdout_buffer); 495 buffer_init(&stderr_buffer); 496 497 /* 498 * If we have no separate fderr (which is the case when we have a pty 499 * - there we cannot make difference between data sent to stdout and 500 * stderr), indicate that we have seen an EOF from stderr. This way 501 * we don\'t need to check the descriptor everywhere. 502 */ 503 if (fderr == -1) 504 fderr_eof = 1; 505 506 server_init_dispatch(); 507 508 /* Main loop of the server for the interactive session mode. */ 509 for (;;) { 510 511 /* Process buffered packets from the client. */ 512 process_buffered_input_packets(); 513 514 /* 515 * If we have received eof, and there is no more pending 516 * input data, cause a real eof by closing fdin. 517 */ 518 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { 519 #ifdef USE_PIPES 520 close(fdin); 521 #else 522 if (fdin != fdout) 523 close(fdin); 524 else 525 shutdown(fdin, SHUT_WR); /* We will no longer send. */ 526 #endif 527 fdin = -1; 528 } 529 /* Make packets from buffered stderr data to send to the client. */ 530 make_packets_from_stderr_data(); 531 532 /* 533 * Make packets from buffered stdout data to send to the 534 * client. If there is very little to send, this arranges to 535 * not send them now, but to wait a short while to see if we 536 * are getting more data. This is necessary, as some systems 537 * wake up readers from a pty after each separate character. 538 */ 539 max_time_milliseconds = 0; 540 stdout_buffer_bytes = buffer_len(&stdout_buffer); 541 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && 542 stdout_buffer_bytes != previous_stdout_buffer_bytes) { 543 /* try again after a while */ 544 max_time_milliseconds = 10; 545 } else { 546 /* Send it now. */ 547 make_packets_from_stdout_data(); 548 } 549 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); 550 551 /* Send channel data to the client. */ 552 if (packet_not_very_much_data_to_write()) 553 channel_output_poll(); 554 555 /* 556 * Bail out of the loop if the program has closed its output 557 * descriptors, and we have no more data to send to the 558 * client, and there is no pending buffered data. 559 */ 560 if (fdout_eof && fderr_eof && !packet_have_data_to_write() && 561 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { 562 if (!channel_still_open()) 563 break; 564 if (!waiting_termination) { 565 const char *s = "Waiting for forwarded connections to terminate...\r\n"; 566 char *cp; 567 waiting_termination = 1; 568 buffer_append(&stderr_buffer, s, strlen(s)); 569 570 /* Display list of open channels. */ 571 cp = channel_open_message(); 572 buffer_append(&stderr_buffer, cp, strlen(cp)); 573 xfree(cp); 574 } 575 } 576 max_fd = MAX(connection_in, connection_out); 577 max_fd = MAX(max_fd, fdin); 578 max_fd = MAX(max_fd, fdout); 579 max_fd = MAX(max_fd, fderr); 580 581 /* Sleep in select() until we can do something. */ 582 wait_until_can_do_something(&readset, &writeset, &max_fd, 583 &nalloc, max_time_milliseconds); 584 585 /* Process any channel events. */ 586 channel_after_select(readset, writeset); 587 588 /* Process input from the client and from program stdout/stderr. */ 589 process_input(readset); 590 591 /* Process output to the client and to program stdin. */ 592 process_output(writeset); 593 } 594 if (readset) 595 xfree(readset); 596 if (writeset) 597 xfree(writeset); 598 599 /* Cleanup and termination code. */ 600 601 /* Wait until all output has been sent to the client. */ 602 drain_output(); 603 604 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", 605 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); 606 607 /* Free and clear the buffers. */ 608 buffer_free(&stdin_buffer); 609 buffer_free(&stdout_buffer); 610 buffer_free(&stderr_buffer); 611 612 /* Close the file descriptors. */ 613 if (fdout != -1) 614 close(fdout); 615 fdout = -1; 616 fdout_eof = 1; 617 if (fderr != -1) 618 close(fderr); 619 fderr = -1; 620 fderr_eof = 1; 621 if (fdin != -1) 622 close(fdin); 623 fdin = -1; 624 625 channel_free_all(); 626 627 /* We no longer want our SIGCHLD handler to be called. */ 628 signal(SIGCHLD, SIG_DFL); 629 630 wait_pid = waitpid(-1, &wait_status, child_terminated ? WNOHANG : 0); 631 if (wait_pid == -1) 632 packet_disconnect("wait: %.100s", strerror(errno)); 633 else if (wait_pid != pid) 634 error("Strange, wait returned pid %d, expected %d", 635 wait_pid, pid); 636 637 /* Check if it exited normally. */ 638 if (WIFEXITED(wait_status)) { 639 /* Yes, normal exit. Get exit status and send it to the client. */ 640 debug("Command exited with status %d.", WEXITSTATUS(wait_status)); 641 packet_start(SSH_SMSG_EXITSTATUS); 642 packet_put_int(WEXITSTATUS(wait_status)); 643 packet_send(); 644 packet_write_wait(); 645 646 /* 647 * Wait for exit confirmation. Note that there might be 648 * other packets coming before it; however, the program has 649 * already died so we just ignore them. The client is 650 * supposed to respond with the confirmation when it receives 651 * the exit status. 652 */ 653 do { 654 int plen; 655 type = packet_read(&plen); 656 } 657 while (type != SSH_CMSG_EXIT_CONFIRMATION); 658 659 debug("Received exit confirmation."); 660 return; 661 } 662 /* Check if the program terminated due to a signal. */ 663 if (WIFSIGNALED(wait_status)) 664 packet_disconnect("Command terminated on signal %d.", 665 WTERMSIG(wait_status)); 666 667 /* Some weird exit cause. Just exit. */ 668 packet_disconnect("wait returned status %04x.", wait_status); 669 /* NOTREACHED */ 670 } 671 672 void 673 server_loop2(Authctxt *authctxt) 674 { 675 fd_set *readset = NULL, *writeset = NULL; 676 int rekeying = 0, max_fd, status, nalloc = 0; 677 pid_t pid; 678 679 debug("Entering interactive session for SSH2."); 680 681 signal(SIGCHLD, sigchld_handler); 682 child_terminated = 0; 683 connection_in = packet_get_connection_in(); 684 connection_out = packet_get_connection_out(); 685 686 max_fd = MAX(connection_in, connection_out); 687 xxx_authctxt = authctxt; 688 689 server_init_dispatch(); 690 691 for (;;) { 692 process_buffered_input_packets(); 693 694 rekeying = (xxx_kex != NULL && !xxx_kex->done); 695 696 if (!rekeying && packet_not_very_much_data_to_write()) 697 channel_output_poll(); 698 wait_until_can_do_something(&readset, &writeset, &max_fd, 699 &nalloc, 0); 700 if (child_terminated) { 701 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) 702 session_close_by_pid(pid, status); 703 child_terminated = 0; 704 } 705 if (!rekeying) 706 channel_after_select(readset, writeset); 707 process_input(readset); 708 if (connection_closed) 709 break; 710 process_output(writeset); 711 } 712 if (readset) 713 xfree(readset); 714 if (writeset) 715 xfree(writeset); 716 717 signal(SIGCHLD, SIG_DFL); 718 719 while ((pid = waitpid(-1, &status, WNOHANG)) > 0) 720 session_close_by_pid(pid, status); 721 /* 722 * there is a race between channel_free_all() killing children and 723 * children dying before kill() 724 */ 725 channel_detach_all(); 726 channel_stop_listening(); 727 728 while (session_have_children()) { 729 pid = waitpid(-1, &status, 0); 730 if (pid > 0) 731 session_close_by_pid(pid, status); 732 else { 733 error("waitpid returned %d: %s", pid, strerror(errno)); 734 break; 735 } 736 } 737 channel_free_all(); 738 } 739 740 static void 741 server_input_channel_failure(int type, int plen, void *ctxt) 742 { 743 debug("Got CHANNEL_FAILURE for keepalive"); 744 /* 745 * reset timeout, since we got a sane answer from the client. 746 * even if this was generated by something other than 747 * the bogus CHANNEL_REQUEST we send for keepalives. 748 */ 749 client_alive_timeouts = 0; 750 } 751 752 753 static void 754 server_input_stdin_data(int type, int plen, void *ctxt) 755 { 756 char *data; 757 u_int data_len; 758 759 /* Stdin data from the client. Append it to the buffer. */ 760 /* Ignore any data if the client has closed stdin. */ 761 if (fdin == -1) 762 return; 763 data = packet_get_string(&data_len); 764 packet_integrity_check(plen, (4 + data_len), type); 765 buffer_append(&stdin_buffer, data, data_len); 766 memset(data, 0, data_len); 767 xfree(data); 768 } 769 770 static void 771 server_input_eof(int type, int plen, void *ctxt) 772 { 773 /* 774 * Eof from the client. The stdin descriptor to the 775 * program will be closed when all buffered data has 776 * drained. 777 */ 778 debug("EOF received for stdin."); 779 packet_integrity_check(plen, 0, type); 780 stdin_eof = 1; 781 } 782 783 static void 784 server_input_window_size(int type, int plen, void *ctxt) 785 { 786 int row = packet_get_int(); 787 int col = packet_get_int(); 788 int xpixel = packet_get_int(); 789 int ypixel = packet_get_int(); 790 791 debug("Window change received."); 792 packet_integrity_check(plen, 4 * 4, type); 793 if (fdin != -1) 794 pty_change_window_size(fdin, row, col, xpixel, ypixel); 795 } 796 797 static Channel * 798 server_request_direct_tcpip(char *ctype) 799 { 800 Channel *c; 801 int sock; 802 char *target, *originator; 803 int target_port, originator_port; 804 805 target = packet_get_string(NULL); 806 target_port = packet_get_int(); 807 originator = packet_get_string(NULL); 808 originator_port = packet_get_int(); 809 packet_done(); 810 811 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", 812 originator, originator_port, target, target_port); 813 814 /* XXX check permission */ 815 sock = channel_connect_to(target, target_port); 816 xfree(target); 817 xfree(originator); 818 if (sock < 0) 819 return NULL; 820 c = channel_new(ctype, SSH_CHANNEL_CONNECTING, 821 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, 822 CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); 823 if (c == NULL) { 824 error("server_request_direct_tcpip: channel_new failed"); 825 close(sock); 826 } 827 return c; 828 } 829 830 static Channel * 831 server_request_session(char *ctype) 832 { 833 Channel *c; 834 835 debug("input_session_request"); 836 packet_done(); 837 /* 838 * A server session has no fd to read or write until a 839 * CHANNEL_REQUEST for a shell is made, so we set the type to 840 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all 841 * CHANNEL_REQUEST messages is registered. 842 */ 843 c = channel_new(ctype, SSH_CHANNEL_LARVAL, 844 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 845 0, xstrdup("server-session"), 1); 846 if (c == NULL) { 847 error("server_request_session: channel_new failed"); 848 return NULL; 849 } 850 if (session_open(xxx_authctxt, c->self) != 1) { 851 debug("session open failed, free channel %d", c->self); 852 channel_free(c); 853 return NULL; 854 } 855 channel_register_callback(c->self, SSH2_MSG_CHANNEL_REQUEST, 856 session_input_channel_req, (void *)0); 857 channel_register_cleanup(c->self, session_close_by_channel); 858 return c; 859 } 860 861 static void 862 server_input_channel_open(int type, int plen, void *ctxt) 863 { 864 Channel *c = NULL; 865 char *ctype; 866 u_int len; 867 int rchan; 868 int rmaxpack; 869 int rwindow; 870 871 ctype = packet_get_string(&len); 872 rchan = packet_get_int(); 873 rwindow = packet_get_int(); 874 rmaxpack = packet_get_int(); 875 876 debug("server_input_channel_open: ctype %s rchan %d win %d max %d", 877 ctype, rchan, rwindow, rmaxpack); 878 879 if (strcmp(ctype, "session") == 0) { 880 c = server_request_session(ctype); 881 } else if (strcmp(ctype, "direct-tcpip") == 0) { 882 c = server_request_direct_tcpip(ctype); 883 } 884 if (c != NULL) { 885 debug("server_input_channel_open: confirm %s", ctype); 886 c->remote_id = rchan; 887 c->remote_window = rwindow; 888 c->remote_maxpacket = rmaxpack; 889 if (c->type != SSH_CHANNEL_CONNECTING) { 890 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 891 packet_put_int(c->remote_id); 892 packet_put_int(c->self); 893 packet_put_int(c->local_window); 894 packet_put_int(c->local_maxpacket); 895 packet_send(); 896 } 897 } else { 898 debug("server_input_channel_open: failure %s", ctype); 899 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); 900 packet_put_int(rchan); 901 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); 902 if (!(datafellows & SSH_BUG_OPENFAILURE)) { 903 packet_put_cstring("open failed"); 904 packet_put_cstring(""); 905 } 906 packet_send(); 907 } 908 xfree(ctype); 909 } 910 911 static void 912 server_input_global_request(int type, int plen, void *ctxt) 913 { 914 char *rtype; 915 int want_reply; 916 int success = 0; 917 918 rtype = packet_get_string(NULL); 919 want_reply = packet_get_char(); 920 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); 921 922 /* -R style forwarding */ 923 if (strcmp(rtype, "tcpip-forward") == 0) { 924 struct passwd *pw; 925 char *listen_address; 926 u_short listen_port; 927 928 pw = auth_get_user(); 929 if (pw == NULL) 930 fatal("server_input_global_request: no user"); 931 listen_address = packet_get_string(NULL); /* XXX currently ignored */ 932 listen_port = (u_short)packet_get_int(); 933 debug("server_input_global_request: tcpip-forward listen %s port %d", 934 listen_address, listen_port); 935 936 /* check permissions */ 937 if (!options.allow_tcp_forwarding || 938 no_port_forwarding_flag || 939 (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { 940 success = 0; 941 packet_send_debug("Server has disabled port forwarding."); 942 } else { 943 /* Start listening on the port */ 944 success = channel_request_forwarding( 945 listen_address, listen_port, 946 /*unspec host_to_connect*/ "<unspec host>", 947 /*unspec port_to_connect*/ 0, 948 options.gateway_ports, /*remote*/ 1); 949 } 950 xfree(listen_address); 951 } 952 if (want_reply) { 953 packet_start(success ? 954 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); 955 packet_send(); 956 packet_write_wait(); 957 } 958 xfree(rtype); 959 } 960 961 static void 962 server_init_dispatch_20(void) 963 { 964 debug("server_init_dispatch_20"); 965 dispatch_init(&dispatch_protocol_error); 966 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); 967 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); 968 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); 969 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); 970 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); 971 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 972 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 973 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request); 974 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); 975 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); 976 /* client_alive */ 977 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); 978 /* rekeying */ 979 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 980 } 981 static void 982 server_init_dispatch_13(void) 983 { 984 debug("server_init_dispatch_13"); 985 dispatch_init(NULL); 986 dispatch_set(SSH_CMSG_EOF, &server_input_eof); 987 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); 988 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); 989 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); 990 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); 991 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); 992 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); 993 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); 994 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); 995 } 996 static void 997 server_init_dispatch_15(void) 998 { 999 server_init_dispatch_13(); 1000 debug("server_init_dispatch_15"); 1001 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); 1002 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); 1003 } 1004 static void 1005 server_init_dispatch(void) 1006 { 1007 if (compat20) 1008 server_init_dispatch_20(); 1009 else if (compat13) 1010 server_init_dispatch_13(); 1011 else 1012 server_init_dispatch_15(); 1013 } 1014