crypto/openssh-4/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, 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 1.124 2005/12/13 15:03:02 reyk Exp $");
  39
  40 #include "xmalloc.h"
  41 #include "packet.h"
  42 #include "buffer.h"
  43 #include "log.h"
  44 #include "servconf.h"
  45 #include "canohost.h"
  46 #include "sshpty.h"
  47 #include "channels.h"
  48 #include "compat.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "auth.h"
  52 #include "session.h"
  53 #include "dispatch.h"
  54 #include "auth-options.h"
  55 #include "serverloop.h"
  56 #include "misc.h"
  57 #include "kex.h"
  58
  59 extern ServerOptions options;
  60
  61 /* XXX */
  62 extern Kex *xxx_kex;
  63 extern Authctxt *the_authctxt;
  64 extern int use_privsep;
  65
  66 static Buffer stdin_buffer;     /* Buffer for stdin data. */
  67 static Buffer stdout_buffer;    /* Buffer for stdout data. */
  68 static Buffer stderr_buffer;    /* Buffer for stderr data. */
  69 static int fdin;                /* Descriptor for stdin (for writing) */
  70 static int fdout;               /* Descriptor for stdout (for reading);
  71                                    May be same number as fdin. */
  72 static int fderr;               /* Descriptor for stderr.  May be -1. */
  73 static long stdin_bytes = 0;    /* Number of bytes written to stdin. */
  74 static long stdout_bytes = 0;   /* Number of stdout bytes sent to client. */
  75 static long stderr_bytes = 0;   /* Number of stderr bytes sent to client. */
  76 static long fdout_bytes = 0;    /* Number of stdout bytes read from program. */
  77 static int stdin_eof = 0;       /* EOF message received from client. */
  78 static int fdout_eof = 0;       /* EOF encountered reading from fdout. */
  79 static int fderr_eof = 0;       /* EOF encountered readung from fderr. */
  80 static int fdin_is_tty = 0;     /* fdin points to a tty. */
  81 static int connection_in;       /* Connection to client (input). */
  82 static int connection_out;      /* Connection to client (output). */
  83 static int connection_closed = 0;       /* Connection to client closed. */
  84 static u_int buffer_high;       /* "Soft" max buffer size. */
  85 static int client_alive_timeouts = 0;
  86
  87 /*
  88  * This SIGCHLD kludge is used to detect when the child exits.  The server
  89  * will exit after that, as soon as forwarded connections have terminated.
  90  */
  91
  92 static volatile sig_atomic_t child_terminated = 0;      /* The child has terminated. */
  93
  94 /* Cleanup on signals (!use_privsep case only) */
  95 static volatile sig_atomic_t received_sigterm = 0;
  96
  97 /* prototypes */
  98 static void server_init_dispatch(void);
  99
 100 /*
 101  * we write to this pipe if a SIGCHLD is caught in order to avoid
 102  * the race between select() and child_terminated
 103  */
 104 static int notify_pipe[2];
 105 static void
 106 notify_setup(void)
 107 {
 108         if (pipe(notify_pipe) < 0) {
 109                 error("pipe(notify_pipe) failed %s", strerror(errno));
 110         } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) ||
 111             (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) {
 112                 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno));
 113                 close(notify_pipe[0]);
 114                 close(notify_pipe[1]);
 115         } else {
 116                 set_nonblock(notify_pipe[0]);
 117                 set_nonblock(notify_pipe[1]);
 118                 return;
 119         }
 120         notify_pipe[0] = -1;    /* read end */
 121         notify_pipe[1] = -1;    /* write end */
 122 }
 123 static void
 124 notify_parent(void)
 125 {
 126         if (notify_pipe[1] != -1)
 127                 write(notify_pipe[1], "", 1);
 128 }
 129 static void
 130 notify_prepare(fd_set *readset)
 131 {
 132         if (notify_pipe[0] != -1)
 133                 FD_SET(notify_pipe[0], readset);
 134 }
 135 static void
 136 notify_done(fd_set *readset)
 137 {
 138         char c;
 139
 140         if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
 141                 while (read(notify_pipe[0], &c, 1) != -1)
 142                         debug2("notify_done: reading");
 143 }
 144
 145 static void
 146 sigchld_handler(int sig)
 147 {
 148         int save_errno = errno;
 149         debug("Received SIGCHLD.");
 150         child_terminated = 1;
 151 #ifndef _UNICOS
 152         mysignal(SIGCHLD, sigchld_handler);
 153 #endif
 154         notify_parent();
 155         errno = save_errno;
 156 }
 157
 158 static void
 159 sigterm_handler(int sig)
 160 {
 161         received_sigterm = sig;
 162 }
 163
 164 /*
 165  * Make packets from buffered stderr data, and buffer it for sending
 166  * to the client.
 167  */
 168 static void
 169 make_packets_from_stderr_data(void)
 170 {
 171         u_int len;
 172
 173         /* Send buffered stderr data to the client. */
 174         while (buffer_len(&stderr_buffer) > 0 &&
 175             packet_not_very_much_data_to_write()) {
 176                 len = buffer_len(&stderr_buffer);
 177                 if (packet_is_interactive()) {
 178                         if (len > 512)
 179                                 len = 512;
 180                 } else {
 181                         /* Keep the packets at reasonable size. */
 182                         if (len > packet_get_maxsize())
 183                                 len = packet_get_maxsize();
 184                 }
 185                 packet_start(SSH_SMSG_STDERR_DATA);
 186                 packet_put_string(buffer_ptr(&stderr_buffer), len);
 187                 packet_send();
 188                 buffer_consume(&stderr_buffer, len);
 189                 stderr_bytes += len;
 190         }
 191 }
 192
 193 /*
 194  * Make packets from buffered stdout data, and buffer it for sending to the
 195  * client.
 196  */
 197 static void
 198 make_packets_from_stdout_data(void)
 199 {
 200         u_int len;
 201
 202         /* Send buffered stdout data to the client. */
 203         while (buffer_len(&stdout_buffer) > 0 &&
 204             packet_not_very_much_data_to_write()) {
 205                 len = buffer_len(&stdout_buffer);
 206                 if (packet_is_interactive()) {
 207                         if (len > 512)
 208                                 len = 512;
 209                 } else {
 210                         /* Keep the packets at reasonable size. */
 211                         if (len > packet_get_maxsize())
 212                                 len = packet_get_maxsize();
 213                 }
 214                 packet_start(SSH_SMSG_STDOUT_DATA);
 215                 packet_put_string(buffer_ptr(&stdout_buffer), len);
 216                 packet_send();
 217                 buffer_consume(&stdout_buffer, len);
 218                 stdout_bytes += len;
 219         }
 220 }
 221
 222 static void
 223 client_alive_check(void)
 224 {
 225         int channel_id;
 226
 227         /* timeout, check to see how many we have had */
 228         if (++client_alive_timeouts > options.client_alive_count_max)
 229                 packet_disconnect("Timeout, your session not responding.");
 230
 231         /*
 232          * send a bogus global/channel request with "wantreply",
 233          * we should get back a failure
 234          */
 235         if ((channel_id = channel_find_open()) == -1) {
 236                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
 237                 packet_put_cstring("keepalive@openssh.com");
 238                 packet_put_char(1);     /* boolean: want reply */
 239         } else {
 240                 channel_request_start(channel_id, "keepalive@openssh.com", 1);
 241         }
 242         packet_send();
 243 }
 244
 245 /*
 246  * Sleep in select() until we can do something.  This will initialize the
 247  * select masks.  Upon return, the masks will indicate which descriptors
 248  * have data or can accept data.  Optionally, a maximum time can be specified
 249  * for the duration of the wait (0 = infinite).
 250  */
 251 static void
 252 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
 253     u_int *nallocp, u_int max_time_milliseconds)
 254 {
 255         struct timeval tv, *tvp;
 256         int ret;
 257         int client_alive_scheduled = 0;
 258
 259         /*
 260          * if using client_alive, set the max timeout accordingly,
 261          * and indicate that this particular timeout was for client
 262          * alive by setting the client_alive_scheduled flag.
 263          *
 264          * this could be randomized somewhat to make traffic
 265          * analysis more difficult, but we're not doing it yet.
 266          */
 267         if (compat20 &&
 268             max_time_milliseconds == 0 && options.client_alive_interval) {
 269                 client_alive_scheduled = 1;
 270                 max_time_milliseconds = options.client_alive_interval * 1000;
 271         }
 272
 273         /* Allocate and update select() masks for channel descriptors. */
 274         channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0);
 275
 276         if (compat20) {
 277 #if 0
 278                 /* wrong: bad condition XXX */
 279                 if (channel_not_very_much_buffered_data())
 280 #endif
 281                 FD_SET(connection_in, *readsetp);
 282         } else {
 283                 /*
 284                  * Read packets from the client unless we have too much
 285                  * buffered stdin or channel data.
 286                  */
 287                 if (buffer_len(&stdin_buffer) < buffer_high &&
 288                     channel_not_very_much_buffered_data())
 289                         FD_SET(connection_in, *readsetp);
 290                 /*
 291                  * If there is not too much data already buffered going to
 292                  * the client, try to get some more data from the program.
 293                  */
 294                 if (packet_not_very_much_data_to_write()) {
 295                         if (!fdout_eof)
 296                                 FD_SET(fdout, *readsetp);
 297                         if (!fderr_eof)
 298                                 FD_SET(fderr, *readsetp);
 299                 }
 300                 /*
 301                  * If we have buffered data, try to write some of that data
 302                  * to the program.
 303                  */
 304                 if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
 305                         FD_SET(fdin, *writesetp);
 306         }
 307         notify_prepare(*readsetp);
 308
 309         /*
 310          * If we have buffered packet data going to the client, mark that
 311          * descriptor.
 312          */
 313         if (packet_have_data_to_write())
 314                 FD_SET(connection_out, *writesetp);
 315
 316         /*
 317          * If child has terminated and there is enough buffer space to read
 318          * from it, then read as much as is available and exit.
 319          */
 320         if (child_terminated && packet_not_very_much_data_to_write())
 321                 if (max_time_milliseconds == 0 || client_alive_scheduled)
 322                         max_time_milliseconds = 100;
 323
 324         if (max_time_milliseconds == 0)
 325                 tvp = NULL;
 326         else {
 327                 tv.tv_sec = max_time_milliseconds / 1000;
 328                 tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
 329                 tvp = &tv;
 330         }
 331
 332         /* Wait for something to happen, or the timeout to expire. */
 333         ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
 334
 335         if (ret == -1) {
 336                 memset(*readsetp, 0, *nallocp);
 337                 memset(*writesetp, 0, *nallocp);
 338                 if (errno != EINTR)
 339                         error("select: %.100s", strerror(errno));
 340         } else if (ret == 0 && client_alive_scheduled)
 341                 client_alive_check();
 342
 343         notify_done(*readsetp);
 344 }
 345
 346 /*
 347  * Processes input from the client and the program.  Input data is stored
 348  * in buffers and processed later.
 349  */
 350 static void
 351 process_input(fd_set * readset)
 352 {
 353         int len;
 354         char buf[16384];
 355
 356         /* Read and buffer any input data from the client. */
 357         if (FD_ISSET(connection_in, readset)) {
 358                 len = read(connection_in, buf, sizeof(buf));
 359                 if (len == 0) {
 360                         verbose("Connection closed by %.100s",
 361                             get_remote_ipaddr());
 362                         connection_closed = 1;
 363                         if (compat20)
 364                                 return;
 365                         cleanup_exit(255);
 366                 } else if (len < 0) {
 367                         if (errno != EINTR && errno != EAGAIN) {
 368                                 verbose("Read error from remote host "
 369                                     "%.100s: %.100s",
 370                                     get_remote_ipaddr(), strerror(errno));
 371                                 cleanup_exit(255);
 372                         }
 373                 } else {
 374                         /* Buffer any received data. */
 375                         packet_process_incoming(buf, len);
 376                 }
 377         }
 378         if (compat20)
 379                 return;
 380
 381         /* Read and buffer any available stdout data from the program. */
 382         if (!fdout_eof && FD_ISSET(fdout, readset)) {
 383                 len = read(fdout, buf, sizeof(buf));
 384                 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
 385                         /* do nothing */
 386                 } else if (len <= 0) {
 387                         fdout_eof = 1;
 388                 } else {
 389                         buffer_append(&stdout_buffer, buf, len);
 390                         fdout_bytes += len;
 391                 }
 392         }
 393         /* Read and buffer any available stderr data from the program. */
 394         if (!fderr_eof && FD_ISSET(fderr, readset)) {
 395                 len = read(fderr, buf, sizeof(buf));
 396                 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
 397                         /* do nothing */
 398                 } else if (len <= 0) {
 399                         fderr_eof = 1;
 400                 } else {
 401                         buffer_append(&stderr_buffer, buf, len);
 402                 }
 403         }
 404 }
 405
 406 /*
 407  * Sends data from internal buffers to client program stdin.
 408  */
 409 static void
 410 process_output(fd_set * writeset)
 411 {
 412         struct termios tio;
 413         u_char *data;
 414         u_int dlen;
 415         int len;
 416
 417         /* Write buffered data to program stdin. */
 418         if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
 419                 data = buffer_ptr(&stdin_buffer);
 420                 dlen = buffer_len(&stdin_buffer);
 421                 len = write(fdin, data, dlen);
 422                 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
 423                         /* do nothing */
 424                 } else if (len <= 0) {
 425                         if (fdin != fdout)
 426                                 close(fdin);
 427                         else
 428                                 shutdown(fdin, SHUT_WR); /* We will no longer send. */
 429                         fdin = -1;
 430                 } else {
 431                         /* Successful write. */
 432                         if (fdin_is_tty && dlen >= 1 && data[0] != '\r' &&
 433                             tcgetattr(fdin, &tio) == 0 &&
 434                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
 435                                 /*
 436                                  * Simulate echo to reduce the impact of
 437                                  * traffic analysis
 438                                  */
 439                                 packet_send_ignore(len);
 440                                 packet_send();
 441                         }
 442                         /* Consume the data from the buffer. */
 443                         buffer_consume(&stdin_buffer, len);
 444                         /* Update the count of bytes written to the program. */
 445                         stdin_bytes += len;
 446                 }
 447         }
 448         /* Send any buffered packet data to the client. */
 449         if (FD_ISSET(connection_out, writeset))
 450                 packet_write_poll();
 451 }
 452
 453 /*
 454  * Wait until all buffered output has been sent to the client.
 455  * This is used when the program terminates.
 456  */
 457 static void
 458 drain_output(void)
 459 {
 460         /* Send any buffered stdout data to the client. */
 461         if (buffer_len(&stdout_buffer) > 0) {
 462                 packet_start(SSH_SMSG_STDOUT_DATA);
 463                 packet_put_string(buffer_ptr(&stdout_buffer),
 464                                   buffer_len(&stdout_buffer));
 465                 packet_send();
 466                 /* Update the count of sent bytes. */
 467                 stdout_bytes += buffer_len(&stdout_buffer);
 468         }
 469         /* Send any buffered stderr data to the client. */
 470         if (buffer_len(&stderr_buffer) > 0) {
 471                 packet_start(SSH_SMSG_STDERR_DATA);
 472                 packet_put_string(buffer_ptr(&stderr_buffer),
 473                                   buffer_len(&stderr_buffer));
 474                 packet_send();
 475                 /* Update the count of sent bytes. */
 476                 stderr_bytes += buffer_len(&stderr_buffer);
 477         }
 478         /* Wait until all buffered data has been written to the client. */
 479         packet_write_wait();
 480 }
 481
 482 static void
 483 process_buffered_input_packets(void)
 484 {
 485         dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL);
 486 }
 487
 488 /*
 489  * Performs the interactive session.  This handles data transmission between
 490  * the client and the program.  Note that the notion of stdin, stdout, and
 491  * stderr in this function is sort of reversed: this function writes to
 492  * stdin (of the child program), and reads from stdout and stderr (of the
 493  * child program).
 494  */
 495 void
 496 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
 497 {
 498         fd_set *readset = NULL, *writeset = NULL;
 499         int max_fd = 0;
 500         u_int nalloc = 0;
 501         int wait_status;        /* Status returned by wait(). */
 502         pid_t wait_pid;         /* pid returned by wait(). */
 503         int waiting_termination = 0;    /* Have displayed waiting close message. */
 504         u_int max_time_milliseconds;
 505         u_int previous_stdout_buffer_bytes;
 506         u_int stdout_buffer_bytes;
 507         int type;
 508
 509         debug("Entering interactive session.");
 510
 511         /* Initialize the SIGCHLD kludge. */
 512         child_terminated = 0;
 513         mysignal(SIGCHLD, sigchld_handler);
 514
 515         if (!use_privsep) {
 516                 signal(SIGTERM, sigterm_handler);
 517                 signal(SIGINT, sigterm_handler);
 518                 signal(SIGQUIT, sigterm_handler);
 519         }
 520
 521         /* Initialize our global variables. */
 522         fdin = fdin_arg;
 523         fdout = fdout_arg;
 524         fderr = fderr_arg;
 525
 526         /* nonblocking IO */
 527         set_nonblock(fdin);
 528         set_nonblock(fdout);
 529         /* we don't have stderr for interactive terminal sessions, see below */
 530         if (fderr != -1)
 531                 set_nonblock(fderr);
 532
 533         if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
 534                 fdin_is_tty = 1;
 535
 536         connection_in = packet_get_connection_in();
 537         connection_out = packet_get_connection_out();
 538
 539         notify_setup();
 540
 541         previous_stdout_buffer_bytes = 0;
 542
 543         /* Set approximate I/O buffer size. */
 544         if (packet_is_interactive())
 545                 buffer_high = 4096;
 546         else
 547                 buffer_high = 64 * 1024;
 548
 549 #if 0
 550         /* Initialize max_fd to the maximum of the known file descriptors. */
 551         max_fd = MAX(connection_in, connection_out);
 552         max_fd = MAX(max_fd, fdin);
 553         max_fd = MAX(max_fd, fdout);
 554         if (fderr != -1)
 555                 max_fd = MAX(max_fd, fderr);
 556 #endif
 557
 558         /* Initialize Initialize buffers. */
 559         buffer_init(&stdin_buffer);
 560         buffer_init(&stdout_buffer);
 561         buffer_init(&stderr_buffer);
 562
 563         /*
 564          * If we have no separate fderr (which is the case when we have a pty
 565          * - there we cannot make difference between data sent to stdout and
 566          * stderr), indicate that we have seen an EOF from stderr.  This way
 567          * we don't need to check the descriptor everywhere.
 568          */
 569         if (fderr == -1)
 570                 fderr_eof = 1;
 571
 572         server_init_dispatch();
 573
 574         /* Main loop of the server for the interactive session mode. */
 575         for (;;) {
 576
 577                 /* Process buffered packets from the client. */
 578                 process_buffered_input_packets();
 579
 580                 /*
 581                  * If we have received eof, and there is no more pending
 582                  * input data, cause a real eof by closing fdin.
 583                  */
 584                 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
 585                         if (fdin != fdout)
 586                                 close(fdin);
 587                         else
 588                                 shutdown(fdin, SHUT_WR); /* We will no longer send. */
 589                         fdin = -1;
 590                 }
 591                 /* Make packets from buffered stderr data to send to the client. */
 592                 make_packets_from_stderr_data();
 593
 594                 /*
 595                  * Make packets from buffered stdout data to send to the
 596                  * client. If there is very little to send, this arranges to
 597                  * not send them now, but to wait a short while to see if we
 598                  * are getting more data. This is necessary, as some systems
 599                  * wake up readers from a pty after each separate character.
 600                  */
 601                 max_time_milliseconds = 0;
 602                 stdout_buffer_bytes = buffer_len(&stdout_buffer);
 603                 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
 604                     stdout_buffer_bytes != previous_stdout_buffer_bytes) {
 605                         /* try again after a while */
 606                         max_time_milliseconds = 10;
 607                 } else {
 608                         /* Send it now. */
 609                         make_packets_from_stdout_data();
 610                 }
 611                 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
 612
 613                 /* Send channel data to the client. */
 614                 if (packet_not_very_much_data_to_write())
 615                         channel_output_poll();
 616
 617                 /*
 618                  * Bail out of the loop if the program has closed its output
 619                  * descriptors, and we have no more data to send to the
 620                  * client, and there is no pending buffered data.
 621                  */
 622                 if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
 623                     buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
 624                         if (!channel_still_open())
 625                                 break;
 626                         if (!waiting_termination) {
 627                                 const char *s = "Waiting for forwarded connections to terminate...\r\n";
 628                                 char *cp;
 629                                 waiting_termination = 1;
 630                                 buffer_append(&stderr_buffer, s, strlen(s));
 631
 632                                 /* Display list of open channels. */
 633                                 cp = channel_open_message();
 634                                 buffer_append(&stderr_buffer, cp, strlen(cp));
 635                                 xfree(cp);
 636                         }
 637                 }
 638                 max_fd = MAX(connection_in, connection_out);
 639                 max_fd = MAX(max_fd, fdin);
 640                 max_fd = MAX(max_fd, fdout);
 641                 max_fd = MAX(max_fd, fderr);
 642                 max_fd = MAX(max_fd, notify_pipe[0]);
 643
 644                 /* Sleep in select() until we can do something. */
 645                 wait_until_can_do_something(&readset, &writeset, &max_fd,
 646                     &nalloc, max_time_milliseconds);
 647
 648                 if (received_sigterm) {
 649                         logit("Exiting on signal %d", received_sigterm);
 650                         /* Clean up sessions, utmp, etc. */
 651                         cleanup_exit(255);
 652                 }
 653
 654                 /* Process any channel events. */
 655                 channel_after_select(readset, writeset);
 656
 657                 /* Process input from the client and from program stdout/stderr. */
 658                 process_input(readset);
 659
 660                 /* Process output to the client and to program stdin. */
 661                 process_output(writeset);
 662         }
 663         if (readset)
 664                 xfree(readset);
 665         if (writeset)
 666                 xfree(writeset);
 667
 668         /* Cleanup and termination code. */
 669
 670         /* Wait until all output has been sent to the client. */
 671         drain_output();
 672
 673         debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
 674             stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
 675
 676         /* Free and clear the buffers. */
 677         buffer_free(&stdin_buffer);
 678         buffer_free(&stdout_buffer);
 679         buffer_free(&stderr_buffer);
 680
 681         /* Close the file descriptors. */
 682         if (fdout != -1)
 683                 close(fdout);
 684         fdout = -1;
 685         fdout_eof = 1;
 686         if (fderr != -1)
 687                 close(fderr);
 688         fderr = -1;
 689         fderr_eof = 1;
 690         if (fdin != -1)
 691                 close(fdin);
 692         fdin = -1;
 693
 694         channel_free_all();
 695
 696         /* We no longer want our SIGCHLD handler to be called. */
 697         mysignal(SIGCHLD, SIG_DFL);
 698
 699         while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0)
 700                 if (errno != EINTR)
 701                         packet_disconnect("wait: %.100s", strerror(errno));
 702         if (wait_pid != pid)
 703                 error("Strange, wait returned pid %ld, expected %ld",
 704                     (long)wait_pid, (long)pid);
 705
 706         /* Check if it exited normally. */
 707         if (WIFEXITED(wait_status)) {
 708                 /* Yes, normal exit.  Get exit status and send it to the client. */
 709                 debug("Command exited with status %d.", WEXITSTATUS(wait_status));
 710                 packet_start(SSH_SMSG_EXITSTATUS);
 711                 packet_put_int(WEXITSTATUS(wait_status));
 712                 packet_send();
 713                 packet_write_wait();
 714
 715                 /*
 716                  * Wait for exit confirmation.  Note that there might be
 717                  * other packets coming before it; however, the program has
 718                  * already died so we just ignore them.  The client is
 719                  * supposed to respond with the confirmation when it receives
 720                  * the exit status.
 721                  */
 722                 do {
 723                         type = packet_read();
 724                 }
 725                 while (type != SSH_CMSG_EXIT_CONFIRMATION);
 726
 727                 debug("Received exit confirmation.");
 728                 return;
 729         }
 730         /* Check if the program terminated due to a signal. */
 731         if (WIFSIGNALED(wait_status))
 732                 packet_disconnect("Command terminated on signal %d.",
 733                                   WTERMSIG(wait_status));
 734
 735         /* Some weird exit cause.  Just exit. */
 736         packet_disconnect("wait returned status %04x.", wait_status);
 737         /* NOTREACHED */
 738 }
 739
 740 static void
 741 collect_children(void)
 742 {
 743         pid_t pid;
 744         sigset_t oset, nset;
 745         int status;
 746
 747         /* block SIGCHLD while we check for dead children */
 748         sigemptyset(&nset);
 749         sigaddset(&nset, SIGCHLD);
 750         sigprocmask(SIG_BLOCK, &nset, &oset);
 751         if (child_terminated) {
 752                 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
 753                     (pid < 0 && errno == EINTR))
 754                         if (pid > 0)
 755                                 session_close_by_pid(pid, status);
 756                 child_terminated = 0;
 757         }
 758         sigprocmask(SIG_SETMASK, &oset, NULL);
 759 }
 760
 761 void
 762 server_loop2(Authctxt *authctxt)
 763 {
 764         fd_set *readset = NULL, *writeset = NULL;
 765         int rekeying = 0, max_fd, nalloc = 0;
 766
 767         debug("Entering interactive session for SSH2.");
 768
 769         mysignal(SIGCHLD, sigchld_handler);
 770         child_terminated = 0;
 771         connection_in = packet_get_connection_in();
 772         connection_out = packet_get_connection_out();
 773
 774         if (!use_privsep) {
 775                 signal(SIGTERM, sigterm_handler);
 776                 signal(SIGINT, sigterm_handler);
 777                 signal(SIGQUIT, sigterm_handler);
 778         }
 779
 780         notify_setup();
 781
 782         max_fd = MAX(connection_in, connection_out);
 783         max_fd = MAX(max_fd, notify_pipe[0]);
 784
 785         server_init_dispatch();
 786
 787         for (;;) {
 788                 process_buffered_input_packets();
 789
 790                 rekeying = (xxx_kex != NULL && !xxx_kex->done);
 791
 792                 if (!rekeying && packet_not_very_much_data_to_write())
 793                         channel_output_poll();
 794                 wait_until_can_do_something(&readset, &writeset, &max_fd,
 795                     &nalloc, 0);
 796
 797                 if (received_sigterm) {
 798                         logit("Exiting on signal %d", received_sigterm);
 799                         /* Clean up sessions, utmp, etc. */
 800                         cleanup_exit(255);
 801                 }
 802
 803                 collect_children();
 804                 if (!rekeying) {
 805                         channel_after_select(readset, writeset);
 806                         if (packet_need_rekeying()) {
 807                                 debug("need rekeying");
 808                                 xxx_kex->done = 0;
 809                                 kex_send_kexinit(xxx_kex);
 810                         }
 811                 }
 812                 process_input(readset);
 813                 if (connection_closed)
 814                         break;
 815                 process_output(writeset);
 816         }
 817         collect_children();
 818
 819         if (readset)
 820                 xfree(readset);
 821         if (writeset)
 822                 xfree(writeset);
 823
 824         /* free all channels, no more reads and writes */
 825         channel_free_all();
 826
 827         /* free remaining sessions, e.g. remove wtmp entries */
 828         session_destroy_all(NULL);
 829 }
 830
 831 static void
 832 server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
 833 {
 834         debug("Got %d/%u for keepalive", type, seq);
 835         /*
 836          * reset timeout, since we got a sane answer from the client.
 837          * even if this was generated by something other than
 838          * the bogus CHANNEL_REQUEST we send for keepalives.
 839          */
 840         client_alive_timeouts = 0;
 841 }
 842
 843 static void
 844 server_input_stdin_data(int type, u_int32_t seq, void *ctxt)
 845 {
 846         char *data;
 847         u_int data_len;
 848
 849         /* Stdin data from the client.  Append it to the buffer. */
 850         /* Ignore any data if the client has closed stdin. */
 851         if (fdin == -1)
 852                 return;
 853         data = packet_get_string(&data_len);
 854         packet_check_eom();
 855         buffer_append(&stdin_buffer, data, data_len);
 856         memset(data, 0, data_len);
 857         xfree(data);
 858 }
 859
 860 static void
 861 server_input_eof(int type, u_int32_t seq, void *ctxt)
 862 {
 863         /*
 864          * Eof from the client.  The stdin descriptor to the
 865          * program will be closed when all buffered data has
 866          * drained.
 867          */
 868         debug("EOF received for stdin.");
 869         packet_check_eom();
 870         stdin_eof = 1;
 871 }
 872
 873 static void
 874 server_input_window_size(int type, u_int32_t seq, void *ctxt)
 875 {
 876         int row = packet_get_int();
 877         int col = packet_get_int();
 878         int xpixel = packet_get_int();
 879         int ypixel = packet_get_int();
 880
 881         debug("Window change received.");
 882         packet_check_eom();
 883         if (fdin != -1)
 884                 pty_change_window_size(fdin, row, col, xpixel, ypixel);
 885 }
 886
 887 static Channel *
 888 server_request_direct_tcpip(void)
 889 {
 890         Channel *c;
 891         int sock;
 892         char *target, *originator;
 893         int target_port, originator_port;
 894
 895         target = packet_get_string(NULL);
 896         target_port = packet_get_int();
 897         originator = packet_get_string(NULL);
 898         originator_port = packet_get_int();
 899         packet_check_eom();
 900
 901         debug("server_request_direct_tcpip: originator %s port %d, target %s port %d",
 902             originator, originator_port, target, target_port);
 903
 904         /* XXX check permission */
 905         sock = channel_connect_to(target, target_port);
 906         xfree(target);
 907         xfree(originator);
 908         if (sock < 0)
 909                 return NULL;
 910         c = channel_new("direct-tcpip", SSH_CHANNEL_CONNECTING,
 911             sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT,
 912             CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1);
 913         return c;
 914 }
 915
 916 static Channel *
 917 server_request_tun(void)
 918 {
 919         Channel *c = NULL;
 920         int mode, tun;
 921         int sock;
 922
 923         mode = packet_get_int();
 924         switch (mode) {
 925         case SSH_TUNMODE_POINTOPOINT:
 926         case SSH_TUNMODE_ETHERNET:
 927                 break;
 928         default:
 929                 packet_send_debug("Unsupported tunnel device mode.");
 930                 return NULL;
 931         }
 932         if ((options.permit_tun & mode) == 0) {
 933                 packet_send_debug("Server has rejected tunnel device "
 934                     "forwarding");
 935                 return NULL;
 936         }
 937
 938         tun = packet_get_int();
 939         if (forced_tun_device != -1) {
 940                 if (tun != SSH_TUNID_ANY && forced_tun_device != tun)
 941                         goto done;
 942                 tun = forced_tun_device;
 943         }
 944         sock = tun_open(tun, mode);
 945         if (sock < 0)
 946                 goto done;
 947         c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
 948             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
 949         c->datagram = 1;
 950 #if defined(SSH_TUN_FILTER)
 951         if (mode == SSH_TUNMODE_POINTOPOINT)
 952                 channel_register_filter(c->self, sys_tun_infilter,
 953                     sys_tun_outfilter);
 954 #endif
 955
 956  done:
 957         if (c == NULL)
 958                 packet_send_debug("Failed to open the tunnel device.");
 959         return c;
 960 }
 961
 962 static Channel *
 963 server_request_session(void)
 964 {
 965         Channel *c;
 966
 967         debug("input_session_request");
 968         packet_check_eom();
 969         /*
 970          * A server session has no fd to read or write until a
 971          * CHANNEL_REQUEST for a shell is made, so we set the type to
 972          * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
 973          * CHANNEL_REQUEST messages is registered.
 974          */
 975         c = channel_new("session", SSH_CHANNEL_LARVAL,
 976             -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
 977             0, "server-session", 1);
 978         if (session_open(the_authctxt, c->self) != 1) {
 979                 debug("session open failed, free channel %d", c->self);
 980                 channel_free(c);
 981                 return NULL;
 982         }
 983         channel_register_cleanup(c->self, session_close_by_channel, 0);
 984         return c;
 985 }
 986
 987 static void
 988 server_input_channel_open(int type, u_int32_t seq, void *ctxt)
 989 {
 990         Channel *c = NULL;
 991         char *ctype;
 992         int rchan;
 993         u_int rmaxpack, rwindow, len;
 994
 995         ctype = packet_get_string(&len);
 996         rchan = packet_get_int();
 997         rwindow = packet_get_int();
 998         rmaxpack = packet_get_int();
 999
1000         debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
1001             ctype, rchan, rwindow, rmaxpack);
1002
1003         if (strcmp(ctype, "session") == 0) {
1004                 c = server_request_session();
1005         } else if (strcmp(ctype, "direct-tcpip") == 0) {
1006                 c = server_request_direct_tcpip();
1007         } else if (strcmp(ctype, "tun@openssh.com") == 0) {
1008                 c = server_request_tun();
1009         }
1010         if (c != NULL) {
1011                 debug("server_input_channel_open: confirm %s", ctype);
1012                 c->remote_id = rchan;
1013                 c->remote_window = rwindow;
1014                 c->remote_maxpacket = rmaxpack;
1015                 if (c->type != SSH_CHANNEL_CONNECTING) {
1016                         packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1017                         packet_put_int(c->remote_id);
1018                         packet_put_int(c->self);
1019                         packet_put_int(c->local_window);
1020                         packet_put_int(c->local_maxpacket);
1021                         packet_send();
1022                 }
1023         } else {
1024                 debug("server_input_channel_open: failure %s", ctype);
1025                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1026                 packet_put_int(rchan);
1027                 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
1028                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1029                         packet_put_cstring("open failed");
1030                         packet_put_cstring("");
1031                 }
1032                 packet_send();
1033         }
1034         xfree(ctype);
1035 }
1036
1037 static void
1038 server_input_global_request(int type, u_int32_t seq, void *ctxt)
1039 {
1040         char *rtype;
1041         int want_reply;
1042         int success = 0;
1043
1044         rtype = packet_get_string(NULL);
1045         want_reply = packet_get_char();
1046         debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
1047
1048         /* -R style forwarding */
1049         if (strcmp(rtype, "tcpip-forward") == 0) {
1050                 struct passwd *pw;
1051                 char *listen_address;
1052                 u_short listen_port;
1053
1054                 pw = the_authctxt->pw;
1055                 if (pw == NULL || !the_authctxt->valid)
1056                         fatal("server_input_global_request: no/invalid user");
1057                 listen_address = packet_get_string(NULL);
1058                 listen_port = (u_short)packet_get_int();
1059                 debug("server_input_global_request: tcpip-forward listen %s port %d",
1060                     listen_address, listen_port);
1061
1062                 /* check permissions */
1063                 if (!options.allow_tcp_forwarding ||
1064                     no_port_forwarding_flag
1065 #ifndef NO_IPPORT_RESERVED_CONCEPT
1066                     || (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)
1067 #endif
1068                     ) {
1069                         success = 0;
1070                         packet_send_debug("Server has disabled port forwarding.");
1071                 } else {
1072                         /* Start listening on the port */
1073                         success = channel_setup_remote_fwd_listener(
1074                             listen_address, listen_port, options.gateway_ports);
1075                 }
1076                 xfree(listen_address);
1077         } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
1078                 char *cancel_address;
1079                 u_short cancel_port;
1080
1081                 cancel_address = packet_get_string(NULL);
1082                 cancel_port = (u_short)packet_get_int();
1083                 debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
1084                     cancel_address, cancel_port);
1085
1086                 success = channel_cancel_rport_listener(cancel_address,
1087                     cancel_port);
1088         }
1089         if (want_reply) {
1090                 packet_start(success ?
1091                     SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
1092                 packet_send();
1093                 packet_write_wait();
1094         }
1095         xfree(rtype);
1096 }
1097 static void
1098 server_input_channel_req(int type, u_int32_t seq, void *ctxt)
1099 {
1100         Channel *c;
1101         int id, reply, success = 0;
1102         char *rtype;
1103
1104         id = packet_get_int();
1105         rtype = packet_get_string(NULL);
1106         reply = packet_get_char();
1107
1108         debug("server_input_channel_req: channel %d request %s reply %d",
1109             id, rtype, reply);
1110
1111         if ((c = channel_lookup(id)) == NULL)
1112                 packet_disconnect("server_input_channel_req: "
1113                     "unknown channel %d", id);
1114         if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN)
1115                 success = session_input_channel_req(c, rtype);
1116         if (reply) {
1117                 packet_start(success ?
1118                     SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1119                 packet_put_int(c->remote_id);
1120                 packet_send();
1121         }
1122         xfree(rtype);
1123 }
1124
1125 static void
1126 server_init_dispatch_20(void)
1127 {
1128         debug("server_init_dispatch_20");
1129         dispatch_init(&dispatch_protocol_error);
1130         dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
1131         dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
1132         dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
1133         dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
1134         dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
1135         dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1136         dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1137         dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
1138         dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
1139         dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
1140         /* client_alive */
1141         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
1142         dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
1143         dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
1144         /* rekeying */
1145         dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1146 }
1147 static void
1148 server_init_dispatch_13(void)
1149 {
1150         debug("server_init_dispatch_13");
1151         dispatch_init(NULL);
1152         dispatch_set(SSH_CMSG_EOF, &server_input_eof);
1153         dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
1154         dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
1155         dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
1156         dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
1157         dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
1158         dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1159         dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1160         dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
1161 }
1162 static void
1163 server_init_dispatch_15(void)
1164 {
1165         server_init_dispatch_13();
1166         debug("server_init_dispatch_15");
1167         dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
1168         dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
1169 }
1170 static void
1171 server_init_dispatch(void)
1172 {
1173         if (compat20)
1174                 server_init_dispatch_20();
1175         else if (compat13)
1176                 server_init_dispatch_13();
1177         else
1178                 server_init_dispatch_15();
1179 }