serverloop.c

   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 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 1.68 2001/06/04 23:07:20 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
  63 static Buffer stdin_buffer;     /* Buffer for stdin data. */
  64 static Buffer stdout_buffer;    /* Buffer for stdout data. */
  65 static Buffer stderr_buffer;    /* Buffer for stderr data. */
  66 static int fdin;                /* Descriptor for stdin (for writing) */
  67 static int fdout;               /* Descriptor for stdout (for reading);
  68                                    May be same number as fdin. */
  69 static int fderr;               /* Descriptor for stderr.  May be -1. */
  70 static long stdin_bytes = 0;    /* Number of bytes written to stdin. */
  71 static long stdout_bytes = 0;   /* Number of stdout bytes sent to client. */
  72 static long stderr_bytes = 0;   /* Number of stderr bytes sent to client. */
  73 static long fdout_bytes = 0;    /* Number of stdout bytes read from program. */
  74 static int stdin_eof = 0;       /* EOF message received from client. */
  75 static int fdout_eof = 0;       /* EOF encountered reading from fdout. */
  76 static int fderr_eof = 0;       /* EOF encountered readung from fderr. */
  77 static int fdin_is_tty = 0;     /* fdin points to a tty. */
  78 static int connection_in;       /* Connection to client (input). */
  79 static int connection_out;      /* Connection to client (output). */
  80 static int connection_closed = 0;       /* Connection to client closed. */
  81 static u_int buffer_high;       /* "Soft" max buffer size. */
  82
  83 /*
  84  * This SIGCHLD kludge is used to detect when the child exits.  The server
  85  * will exit after that, as soon as forwarded connections have terminated.
  86  */
  87 static volatile int child_terminated;   /* The child has terminated. */
  88
  89 void    server_init_dispatch(void);
  90
  91 int client_alive_timeouts = 0;
  92
  93 void
  94 sigchld_handler(int sig)
  95 {
  96         int save_errno = errno;
  97         debug("Received SIGCHLD.");
  98         child_terminated = 1;
  99         mysignal(SIGCHLD, sigchld_handler);
 100         errno = save_errno;
 101 }
 102
 103 /*
 104  * Make packets from buffered stderr data, and buffer it for sending
 105  * to the client.
 106  */
 107 void
 108 make_packets_from_stderr_data(void)
 109 {
 110         int len;
 111
 112         /* Send buffered stderr data to the client. */
 113         while (buffer_len(&stderr_buffer) > 0 &&
 114             packet_not_very_much_data_to_write()) {
 115                 len = buffer_len(&stderr_buffer);
 116                 if (packet_is_interactive()) {
 117                         if (len > 512)
 118                                 len = 512;
 119                 } else {
 120                         /* Keep the packets at reasonable size. */
 121                         if (len > packet_get_maxsize())
 122                                 len = packet_get_maxsize();
 123                 }
 124                 packet_start(SSH_SMSG_STDERR_DATA);
 125                 packet_put_string(buffer_ptr(&stderr_buffer), len);
 126                 packet_send();
 127                 buffer_consume(&stderr_buffer, len);
 128                 stderr_bytes += len;
 129         }
 130 }
 131
 132 /*
 133  * Make packets from buffered stdout data, and buffer it for sending to the
 134  * client.
 135  */
 136 void
 137 make_packets_from_stdout_data(void)
 138 {
 139         int len;
 140
 141         /* Send buffered stdout data to the client. */
 142         while (buffer_len(&stdout_buffer) > 0 &&
 143             packet_not_very_much_data_to_write()) {
 144                 len = buffer_len(&stdout_buffer);
 145                 if (packet_is_interactive()) {
 146                         if (len > 512)
 147                                 len = 512;
 148                 } else {
 149                         /* Keep the packets at reasonable size. */
 150                         if (len > packet_get_maxsize())
 151                                 len = packet_get_maxsize();
 152                 }
 153                 packet_start(SSH_SMSG_STDOUT_DATA);
 154                 packet_put_string(buffer_ptr(&stdout_buffer), len);
 155                 packet_send();
 156                 buffer_consume(&stdout_buffer, len);
 157                 stdout_bytes += len;
 158         }
 159 }
 160
 161 /*
 162  * Sleep in select() until we can do something.  This will initialize the
 163  * select masks.  Upon return, the masks will indicate which descriptors
 164  * have data or can accept data.  Optionally, a maximum time can be specified
 165  * for the duration of the wait (0 = infinite).
 166  */
 167 void
 168 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
 169     u_int max_time_milliseconds)
 170 {
 171         struct timeval tv, *tvp;
 172         int ret;
 173         int client_alive_scheduled = 0;
 174
 175         /*
 176          * if using client_alive, set the max timeout accordingly,
 177          * and indicate that this particular timeout was for client
 178          * alive by setting the client_alive_scheduled flag.
 179          *
 180          * this could be randomized somewhat to make traffic
 181          * analysis more difficult, but we're not doing it yet.
 182          */
 183         if (max_time_milliseconds == 0 && options.client_alive_interval) {
 184                 client_alive_scheduled = 1;
 185                 max_time_milliseconds = options.client_alive_interval * 1000;
 186         } else
 187                 client_alive_scheduled = 0;
 188
 189         /* When select fails we restart from here. */
 190 retry_select:
 191
 192         /* Allocate and update select() masks for channel descriptors. */
 193         channel_prepare_select(readsetp, writesetp, maxfdp, 0);
 194
 195         if (compat20) {
 196                 /* wrong: bad condition XXX */
 197                 if (channel_not_very_much_buffered_data())
 198                         FD_SET(connection_in, *readsetp);
 199         } else {
 200                 /*
 201                  * Read packets from the client unless we have too much
 202                  * buffered stdin or channel data.
 203                  */
 204                 if (buffer_len(&stdin_buffer) < buffer_high &&
 205                     channel_not_very_much_buffered_data())
 206                         FD_SET(connection_in, *readsetp);
 207                 /*
 208                  * If there is not too much data already buffered going to
 209                  * the client, try to get some more data from the program.
 210                  */
 211                 if (packet_not_very_much_data_to_write()) {
 212                         if (!fdout_eof)
 213                                 FD_SET(fdout, *readsetp);
 214                         if (!fderr_eof)
 215                                 FD_SET(fderr, *readsetp);
 216                 }
 217                 /*
 218                  * If we have buffered data, try to write some of that data
 219                  * to the program.
 220                  */
 221                 if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
 222                         FD_SET(fdin, *writesetp);
 223         }
 224
 225         /*
 226          * If we have buffered packet data going to the client, mark that
 227          * descriptor.
 228          */
 229         if (packet_have_data_to_write())
 230                 FD_SET(connection_out, *writesetp);
 231
 232         /*
 233          * If child has terminated and there is enough buffer space to read
 234          * from it, then read as much as is available and exit.
 235          */
 236         if (child_terminated && packet_not_very_much_data_to_write())
 237                 if (max_time_milliseconds == 0 || client_alive_scheduled)
 238                         max_time_milliseconds = 100;
 239
 240         if (max_time_milliseconds == 0)
 241                 tvp = NULL;
 242         else {
 243                 tv.tv_sec = max_time_milliseconds / 1000;
 244                 tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
 245                 tvp = &tv;
 246         }
 247         if (tvp!=NULL)
 248                 debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds);
 249
 250         /* Wait for something to happen, or the timeout to expire. */
 251         ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
 252
 253         if (ret == -1) {
 254                 if (errno != EINTR)
 255                         error("select: %.100s", strerror(errno));
 256                 else
 257                         goto retry_select;
 258         }
 259         if (ret == 0 && client_alive_scheduled) {
 260                 /* timeout, check to see how many we have had */
 261                 client_alive_timeouts++;
 262
 263                 if (client_alive_timeouts > options.client_alive_count_max ) {
 264                         packet_disconnect(
 265                                 "Timeout, your session not responding.");
 266                 } else {
 267                         /*
 268                          * send a bogus channel request with "wantreply"
 269                          * we should get back a failure
 270                          */
 271                         int id;
 272
 273                         id = channel_find_open();
 274                         if (id != -1) {
 275                                 channel_request_start(id,
 276                                   "keepalive@openssh.com", 1);
 277                                 packet_send();
 278                         } else
 279                                 packet_disconnect(
 280                                         "No open channels after timeout!");
 281                 }
 282         }
 283 }
 284
 285 /*
 286  * Processes input from the client and the program.  Input data is stored
 287  * in buffers and processed later.
 288  */
 289 void
 290 process_input(fd_set * readset)
 291 {
 292         int len;
 293         char buf[16384];
 294
 295         /* Read and buffer any input data from the client. */
 296         if (FD_ISSET(connection_in, readset)) {
 297                 len = read(connection_in, buf, sizeof(buf));
 298                 if (len == 0) {
 299                         verbose("Connection closed by remote host.");
 300                         connection_closed = 1;
 301                         if (compat20)
 302                                 return;
 303                         fatal_cleanup();
 304                 } else if (len < 0) {
 305                         if (errno != EINTR && errno != EAGAIN) {
 306                                 verbose("Read error from remote host: %.100s", strerror(errno));
 307                                 fatal_cleanup();
 308                         }
 309                 } else {
 310                         /* Buffer any received data. */
 311                         packet_process_incoming(buf, len);
 312                 }
 313         }
 314         if (compat20)
 315                 return;
 316
 317         /* Read and buffer any available stdout data from the program. */
 318         if (!fdout_eof && FD_ISSET(fdout, readset)) {
 319                 len = read(fdout, buf, sizeof(buf));
 320                 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
 321                         /* do nothing */
 322                 } else if (len <= 0) {
 323                         fdout_eof = 1;
 324                 } else {
 325                         buffer_append(&stdout_buffer, buf, len);
 326                         fdout_bytes += len;
 327                 }
 328         }
 329         /* Read and buffer any available stderr data from the program. */
 330         if (!fderr_eof && FD_ISSET(fderr, readset)) {
 331                 len = read(fderr, buf, sizeof(buf));
 332                 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
 333                         /* do nothing */
 334                 } else if (len <= 0) {
 335                         fderr_eof = 1;
 336                 } else {
 337                         buffer_append(&stderr_buffer, buf, len);
 338                 }
 339         }
 340 }
 341
 342 /*
 343  * Sends data from internal buffers to client program stdin.
 344  */
 345 void
 346 process_output(fd_set * writeset)
 347 {
 348         struct termios tio;
 349         int len;
 350
 351         /* Write buffered data to program stdin. */
 352         if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
 353                 len = write(fdin, buffer_ptr(&stdin_buffer),
 354                     buffer_len(&stdin_buffer));
 355                 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
 356                         /* do nothing */
 357                 } else if (len <= 0) {
 358 #ifdef USE_PIPES
 359                         close(fdin);
 360 #else
 361                         if (fdin != fdout)
 362                                 close(fdin);
 363                         else
 364                                 shutdown(fdin, SHUT_WR); /* We will no longer send. */
 365 #endif
 366                         fdin = -1;
 367                 } else {
 368                         /* Successful write. */
 369                         if (fdin_is_tty && tcgetattr(fdin, &tio) == 0 &&
 370                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
 371                                 /*
 372                                  * Simulate echo to reduce the impact of
 373                                  * traffic analysis
 374                                  */
 375                                 packet_send_ignore(len);
 376                                 packet_send();
 377                         }
 378                         /* Consume the data from the buffer. */
 379                         buffer_consume(&stdin_buffer, len);
 380                         /* Update the count of bytes written to the program. */
 381                         stdin_bytes += len;
 382                 }
 383         }
 384         /* Send any buffered packet data to the client. */
 385         if (FD_ISSET(connection_out, writeset))
 386                 packet_write_poll();
 387 }
 388
 389 /*
 390  * Wait until all buffered output has been sent to the client.
 391  * This is used when the program terminates.
 392  */
 393 void
 394 drain_output(void)
 395 {
 396         /* Send any buffered stdout data to the client. */
 397         if (buffer_len(&stdout_buffer) > 0) {
 398                 packet_start(SSH_SMSG_STDOUT_DATA);
 399                 packet_put_string(buffer_ptr(&stdout_buffer),
 400                                   buffer_len(&stdout_buffer));
 401                 packet_send();
 402                 /* Update the count of sent bytes. */
 403                 stdout_bytes += buffer_len(&stdout_buffer);
 404         }
 405         /* Send any buffered stderr data to the client. */
 406         if (buffer_len(&stderr_buffer) > 0) {
 407                 packet_start(SSH_SMSG_STDERR_DATA);
 408                 packet_put_string(buffer_ptr(&stderr_buffer),
 409                                   buffer_len(&stderr_buffer));
 410                 packet_send();
 411                 /* Update the count of sent bytes. */
 412                 stderr_bytes += buffer_len(&stderr_buffer);
 413         }
 414         /* Wait until all buffered data has been written to the client. */
 415         packet_write_wait();
 416 }
 417
 418 void
 419 process_buffered_input_packets(void)
 420 {
 421         dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL);
 422 }
 423
 424 /*
 425  * Performs the interactive session.  This handles data transmission between
 426  * the client and the program.  Note that the notion of stdin, stdout, and
 427  * stderr in this function is sort of reversed: this function writes to
 428  * stdin (of the child program), and reads from stdout and stderr (of the
 429  * child program).
 430  */
 431 void
 432 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
 433 {
 434         fd_set *readset = NULL, *writeset = NULL;
 435         int max_fd;
 436         int wait_status;        /* Status returned by wait(). */
 437         pid_t wait_pid;         /* pid returned by wait(). */
 438         int waiting_termination = 0;    /* Have displayed waiting close message. */
 439         u_int max_time_milliseconds;
 440         u_int previous_stdout_buffer_bytes;
 441         u_int stdout_buffer_bytes;
 442         int type;
 443
 444         debug("Entering interactive session.");
 445
 446         /* Initialize the SIGCHLD kludge. */
 447         child_terminated = 0;
 448         signal(SIGCHLD, sigchld_handler);
 449
 450         /* Initialize our global variables. */
 451         fdin = fdin_arg;
 452         fdout = fdout_arg;
 453         fderr = fderr_arg;
 454
 455         /* nonblocking IO */
 456         set_nonblock(fdin);
 457         set_nonblock(fdout);
 458         /* we don't have stderr for interactive terminal sessions, see below */
 459         if (fderr != -1)
 460                 set_nonblock(fderr);
 461
 462         if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
 463                 fdin_is_tty = 1;
 464
 465         connection_in = packet_get_connection_in();
 466         connection_out = packet_get_connection_out();
 467
 468         previous_stdout_buffer_bytes = 0;
 469
 470         /* Set approximate I/O buffer size. */
 471         if (packet_is_interactive())
 472                 buffer_high = 4096;
 473         else
 474                 buffer_high = 64 * 1024;
 475
 476         /* Initialize max_fd to the maximum of the known file descriptors. */
 477         max_fd = MAX(fdin, fdout);
 478         if (fderr != -1)
 479                 max_fd = MAX(max_fd, fderr);
 480         max_fd = MAX(max_fd, connection_in);
 481         max_fd = MAX(max_fd, connection_out);
 482
 483         /* Initialize Initialize buffers. */
 484         buffer_init(&stdin_buffer);
 485         buffer_init(&stdout_buffer);
 486         buffer_init(&stderr_buffer);
 487
 488         /*
 489          * If we have no separate fderr (which is the case when we have a pty
 490          * - there we cannot make difference between data sent to stdout and
 491          * stderr), indicate that we have seen an EOF from stderr.  This way
 492          * we don\'t need to check the descriptor everywhere.
 493          */
 494         if (fderr == -1)
 495                 fderr_eof = 1;
 496
 497         server_init_dispatch();
 498
 499         /* Main loop of the server for the interactive session mode. */
 500         for (;;) {
 501
 502                 /* Process buffered packets from the client. */
 503                 process_buffered_input_packets();
 504
 505                 /*
 506                  * If we have received eof, and there is no more pending
 507                  * input data, cause a real eof by closing fdin.
 508                  */
 509                 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
 510 #ifdef USE_PIPES
 511                         close(fdin);
 512 #else
 513                         if (fdin != fdout)
 514                                 close(fdin);
 515                         else
 516                                 shutdown(fdin, SHUT_WR); /* We will no longer send. */
 517 #endif
 518                         fdin = -1;
 519                 }
 520                 /* Make packets from buffered stderr data to send to the client. */
 521                 make_packets_from_stderr_data();
 522
 523                 /*
 524                  * Make packets from buffered stdout data to send to the
 525                  * client. If there is very little to send, this arranges to
 526                  * not send them now, but to wait a short while to see if we
 527                  * are getting more data. This is necessary, as some systems
 528                  * wake up readers from a pty after each separate character.
 529                  */
 530                 max_time_milliseconds = 0;
 531                 stdout_buffer_bytes = buffer_len(&stdout_buffer);
 532                 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
 533                     stdout_buffer_bytes != previous_stdout_buffer_bytes) {
 534                         /* try again after a while */
 535                         max_time_milliseconds = 10;
 536                 } else {
 537                         /* Send it now. */
 538                         make_packets_from_stdout_data();
 539                 }
 540                 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
 541
 542                 /* Send channel data to the client. */
 543                 if (packet_not_very_much_data_to_write())
 544                         channel_output_poll();
 545
 546                 /*
 547                  * Bail out of the loop if the program has closed its output
 548                  * descriptors, and we have no more data to send to the
 549                  * client, and there is no pending buffered data.
 550                  */
 551                 if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
 552                     buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
 553                         if (!channel_still_open())
 554                                 break;
 555                         if (!waiting_termination) {
 556                                 const char *s = "Waiting for forwarded connections to terminate...\r\n";
 557                                 char *cp;
 558                                 waiting_termination = 1;
 559                                 buffer_append(&stderr_buffer, s, strlen(s));
 560
 561                                 /* Display list of open channels. */
 562                                 cp = channel_open_message();
 563                                 buffer_append(&stderr_buffer, cp, strlen(cp));
 564                                 xfree(cp);
 565                         }
 566                 }
 567                 /* Sleep in select() until we can do something. */
 568                 wait_until_can_do_something(&readset, &writeset, &max_fd,
 569                     max_time_milliseconds);
 570
 571                 /* Process any channel events. */
 572                 channel_after_select(readset, writeset);
 573
 574                 /* Process input from the client and from program stdout/stderr. */
 575                 process_input(readset);
 576
 577                 /* Process output to the client and to program stdin. */
 578                 process_output(writeset);
 579         }
 580         if (readset)
 581                 xfree(readset);
 582         if (writeset)
 583                 xfree(writeset);
 584
 585         /* Cleanup and termination code. */
 586
 587         /* Wait until all output has been sent to the client. */
 588         drain_output();
 589
 590         debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
 591               stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
 592
 593         /* Free and clear the buffers. */
 594         buffer_free(&stdin_buffer);
 595         buffer_free(&stdout_buffer);
 596         buffer_free(&stderr_buffer);
 597
 598         /* Close the file descriptors. */
 599         if (fdout != -1)
 600                 close(fdout);
 601         fdout = -1;
 602         fdout_eof = 1;
 603         if (fderr != -1)
 604                 close(fderr);
 605         fderr = -1;
 606         fderr_eof = 1;
 607         if (fdin != -1)
 608                 close(fdin);
 609         fdin = -1;
 610
 611         /* Stop listening for channels; this removes unix domain sockets. */
 612         channel_stop_listening();
 613
 614         /* We no longer want our SIGCHLD handler to be called. */
 615         signal(SIGCHLD, SIG_DFL);
 616
 617         wait_pid = waitpid(-1, &wait_status, child_terminated ? WNOHANG : 0);
 618         if (wait_pid == -1)
 619                 packet_disconnect("wait: %.100s", strerror(errno));
 620         else if (wait_pid != pid)
 621                 error("Strange, wait returned pid %d, expected %d",
 622                     wait_pid, pid);
 623
 624         /* Check if it exited normally. */
 625         if (WIFEXITED(wait_status)) {
 626                 /* Yes, normal exit.  Get exit status and send it to the client. */
 627                 debug("Command exited with status %d.", WEXITSTATUS(wait_status));
 628                 packet_start(SSH_SMSG_EXITSTATUS);
 629                 packet_put_int(WEXITSTATUS(wait_status));
 630                 packet_send();
 631                 packet_write_wait();
 632
 633                 /*
 634                  * Wait for exit confirmation.  Note that there might be
 635                  * other packets coming before it; however, the program has
 636                  * already died so we just ignore them.  The client is
 637                  * supposed to respond with the confirmation when it receives
 638                  * the exit status.
 639                  */
 640                 do {
 641                         int plen;
 642                         type = packet_read(&plen);
 643                 }
 644                 while (type != SSH_CMSG_EXIT_CONFIRMATION);
 645
 646                 debug("Received exit confirmation.");
 647                 return;
 648         }
 649         /* Check if the program terminated due to a signal. */
 650         if (WIFSIGNALED(wait_status))
 651                 packet_disconnect("Command terminated on signal %d.",
 652                                   WTERMSIG(wait_status));
 653
 654         /* Some weird exit cause.  Just exit. */
 655         packet_disconnect("wait returned status %04x.", wait_status);
 656         /* NOTREACHED */
 657 }
 658
 659 void
 660 server_loop2(void)
 661 {
 662         fd_set *readset = NULL, *writeset = NULL;
 663         int rekeying = 0, max_fd, status;
 664         pid_t pid;
 665
 666         debug("Entering interactive session for SSH2.");
 667
 668         mysignal(SIGCHLD, sigchld_handler);
 669         child_terminated = 0;
 670         connection_in = packet_get_connection_in();
 671         connection_out = packet_get_connection_out();
 672
 673         max_fd = MAX(connection_in, connection_out);
 674
 675         server_init_dispatch();
 676
 677         for (;;) {
 678                 process_buffered_input_packets();
 679
 680                 rekeying = (xxx_kex != NULL && !xxx_kex->done);
 681
 682                 if (!rekeying && packet_not_very_much_data_to_write())
 683                         channel_output_poll();
 684                 wait_until_can_do_something(&readset, &writeset, &max_fd,
 685                     rekeying);
 686                 if (child_terminated) {
 687                         while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
 688                                 session_close_by_pid(pid, status);
 689                         child_terminated = 0;
 690                 }
 691                 if (!rekeying)
 692                         channel_after_select(readset, writeset);
 693                 process_input(readset);
 694                 if (connection_closed)
 695                         break;
 696                 process_output(writeset);
 697         }
 698         if (readset)
 699                 xfree(readset);
 700         if (writeset)
 701                 xfree(writeset);
 702
 703         signal(SIGCHLD, SIG_DFL);
 704         while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
 705                 session_close_by_pid(pid, status);
 706         channel_stop_listening();
 707 }
 708
 709 void
 710 server_input_channel_failure(int type, int plen, void *ctxt)
 711 {
 712         debug("Got CHANNEL_FAILURE for keepalive");
 713         /*
 714          * reset timeout, since we got a sane answer from the client.
 715          * even if this was generated by something other than
 716          * the bogus CHANNEL_REQUEST we send for keepalives.
 717          */
 718         client_alive_timeouts = 0;
 719 }
 720
 721
 722 void
 723 server_input_stdin_data(int type, int plen, void *ctxt)
 724 {
 725         char *data;
 726         u_int data_len;
 727
 728         /* Stdin data from the client.  Append it to the buffer. */
 729         /* Ignore any data if the client has closed stdin. */
 730         if (fdin == -1)
 731                 return;
 732         data = packet_get_string(&data_len);
 733         packet_integrity_check(plen, (4 + data_len), type);
 734         buffer_append(&stdin_buffer, data, data_len);
 735         memset(data, 0, data_len);
 736         xfree(data);
 737 }
 738
 739 void
 740 server_input_eof(int type, int plen, void *ctxt)
 741 {
 742         /*
 743          * Eof from the client.  The stdin descriptor to the
 744          * program will be closed when all buffered data has
 745          * drained.
 746          */
 747         debug("EOF received for stdin.");
 748         packet_integrity_check(plen, 0, type);
 749         stdin_eof = 1;
 750 }
 751
 752 void
 753 server_input_window_size(int type, int plen, void *ctxt)
 754 {
 755         int row = packet_get_int();
 756         int col = packet_get_int();
 757         int xpixel = packet_get_int();
 758         int ypixel = packet_get_int();
 759
 760         debug("Window change received.");
 761         packet_integrity_check(plen, 4 * 4, type);
 762         if (fdin != -1)
 763                 pty_change_window_size(fdin, row, col, xpixel, ypixel);
 764 }
 765
 766 Channel *
 767 server_request_direct_tcpip(char *ctype)
 768 {
 769         Channel *c;
 770         int sock;
 771         char *target, *originator;
 772         int target_port, originator_port;
 773
 774         target = packet_get_string(NULL);
 775         target_port = packet_get_int();
 776         originator = packet_get_string(NULL);
 777         originator_port = packet_get_int();
 778         packet_done();
 779
 780         debug("server_request_direct_tcpip: originator %s port %d, target %s port %d",
 781            originator, originator_port, target, target_port);
 782
 783         /* XXX check permission */
 784         sock = channel_connect_to(target, target_port);
 785         xfree(target);
 786         xfree(originator);
 787         if (sock < 0)
 788                 return NULL;
 789         c = channel_new(ctype, SSH_CHANNEL_CONNECTING,
 790             sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT,
 791             CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1);
 792         if (c == NULL) {
 793                 error("server_request_direct_tcpip: channel_new failed");
 794                 close(sock);
 795         }
 796         return c;
 797 }
 798
 799 Channel *
 800 server_request_session(char *ctype)
 801 {
 802         Channel *c;
 803
 804         debug("input_session_request");
 805         packet_done();
 806         /*
 807          * A server session has no fd to read or write until a
 808          * CHANNEL_REQUEST for a shell is made, so we set the type to
 809          * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
 810          * CHANNEL_REQUEST messages is registered.
 811          */
 812         c = channel_new(ctype, SSH_CHANNEL_LARVAL,
 813             -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
 814             0, xstrdup("server-session"), 1);
 815         if (c == NULL) {
 816                 error("server_request_session: channel_new failed");
 817                 return NULL;
 818         }
 819         if (session_open(c->self) != 1) {
 820                 debug("session open failed, free channel %d", c->self);
 821                 channel_free(c);
 822                 return NULL;
 823         }
 824         channel_register_callback(c->self, SSH2_MSG_CHANNEL_REQUEST,
 825             session_input_channel_req, (void *)0);
 826         channel_register_cleanup(c->self, session_close_by_channel);
 827         return c;
 828 }
 829
 830 void
 831 server_input_channel_open(int type, int plen, void *ctxt)
 832 {
 833         Channel *c = NULL;
 834         char *ctype;
 835         u_int len;
 836         int rchan;
 837         int rmaxpack;
 838         int rwindow;
 839
 840         ctype = packet_get_string(&len);
 841         rchan = packet_get_int();
 842         rwindow = packet_get_int();
 843         rmaxpack = packet_get_int();
 844
 845         debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
 846             ctype, rchan, rwindow, rmaxpack);
 847
 848         if (strcmp(ctype, "session") == 0) {
 849                 c = server_request_session(ctype);
 850         } else if (strcmp(ctype, "direct-tcpip") == 0) {
 851                 c = server_request_direct_tcpip(ctype);
 852         }
 853         if (c != NULL) {
 854                 debug("server_input_channel_open: confirm %s", ctype);
 855                 c->remote_id = rchan;
 856                 c->remote_window = rwindow;
 857                 c->remote_maxpacket = rmaxpack;
 858                 if (c->type != SSH_CHANNEL_CONNECTING) {
 859                         packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
 860                         packet_put_int(c->remote_id);
 861                         packet_put_int(c->self);
 862                         packet_put_int(c->local_window);
 863                         packet_put_int(c->local_maxpacket);
 864                         packet_send();
 865                 }
 866         } else {
 867                 debug("server_input_channel_open: failure %s", ctype);
 868                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
 869                 packet_put_int(rchan);
 870                 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
 871                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
 872                         packet_put_cstring("open failed");
 873                         packet_put_cstring("");
 874                 }
 875                 packet_send();
 876         }
 877         xfree(ctype);
 878 }
 879
 880 void
 881 server_input_global_request(int type, int plen, void *ctxt)
 882 {
 883         char *rtype;
 884         int want_reply;
 885         int success = 0;
 886
 887         rtype = packet_get_string(NULL);
 888         want_reply = packet_get_char();
 889         debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
 890
 891         /* -R style forwarding */
 892         if (strcmp(rtype, "tcpip-forward") == 0) {
 893                 struct passwd *pw;
 894                 char *listen_address;
 895                 u_short listen_port;
 896
 897                 pw = auth_get_user();
 898                 if (pw == NULL)
 899                         fatal("server_input_global_request: no user");
 900                 listen_address = packet_get_string(NULL); /* XXX currently ignored */
 901                 listen_port = (u_short)packet_get_int();
 902                 debug("server_input_global_request: tcpip-forward listen %s port %d",
 903                     listen_address, listen_port);
 904
 905                 /* check permissions */
 906                 if (!options.allow_tcp_forwarding ||
 907                     no_port_forwarding_flag ||
 908                     (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) {
 909                         success = 0;
 910                         packet_send_debug("Server has disabled port forwarding.");
 911                 } else {
 912                         /* Start listening on the port */
 913                         success = channel_request_forwarding(
 914                             listen_address, listen_port,
 915                             /*unspec host_to_connect*/ "<unspec host>",
 916                             /*unspec port_to_connect*/ 0,
 917                             options.gateway_ports, /*remote*/ 1);
 918                 }
 919                 xfree(listen_address);
 920         }
 921         if (want_reply) {
 922                 packet_start(success ?
 923                     SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
 924                 packet_send();
 925                 packet_write_wait();
 926         }
 927         xfree(rtype);
 928 }
 929
 930 void
 931 server_init_dispatch_20(void)
 932 {
 933         debug("server_init_dispatch_20");
 934         dispatch_init(&dispatch_protocol_error);
 935         dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
 936         dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
 937         dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
 938         dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
 939         dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
 940         dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
 941         dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
 942         dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request);
 943         dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
 944         dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
 945         /* client_alive */
 946         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure);
 947         /* rekeying */
 948         dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
 949 }
 950 void
 951 server_init_dispatch_13(void)
 952 {
 953         debug("server_init_dispatch_13");
 954         dispatch_init(NULL);
 955         dispatch_set(SSH_CMSG_EOF, &server_input_eof);
 956         dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
 957         dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
 958         dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
 959         dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
 960         dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
 961         dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
 962         dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
 963         dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
 964 }
 965 void
 966 server_init_dispatch_15(void)
 967 {
 968         server_init_dispatch_13();
 969         debug("server_init_dispatch_15");
 970         dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
 971         dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
 972 }
 973 void
 974 server_init_dispatch(void)
 975 {
 976         if (compat20)
 977                 server_init_dispatch_20();
 978         else if (compat13)
 979                 server_init_dispatch_13();
 980         else
 981                 server_init_dispatch_15();
 982 }
 983