channels.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  * This file contains functions for generic socket connection forwarding.
   6  * There is also code for initiating connection forwarding for X11 connections,
   7  * arbitrary tcp/ip connections, and the authentication agent connection.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * SSH2 support added by Markus Friedl.
  16  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  17  * Copyright (c) 1999 Dug Song.  All rights reserved.
  18  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  19  *
  20  * Redistribution and use in source and binary forms, with or without
  21  * modification, are permitted provided that the following conditions
  22  * are met:
  23  * 1. Redistributions of source code must retain the above copyright
  24  *    notice, this list of conditions and the following disclaimer.
  25  * 2. Redistributions in binary form must reproduce the above copyright
  26  *    notice, this list of conditions and the following disclaimer in the
  27  *    documentation and/or other materials provided with the distribution.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  30  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  31  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  32  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  33  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  34  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  38  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  39  */
  40
  41 #include "includes.h"
  42 RCSID("$OpenBSD: channels.c,v 1.235 2006/02/20 16:36:14 stevesk Exp $");
  43
  44 #include <sys/ioctl.h>
  45 #include <sys/types.h>
  46 #include <sys/un.h>
  47
  48 #include <termios.h>
  49
  50 #include "ssh.h"
  51 #include "ssh1.h"
  52 #include "ssh2.h"
  53 #include "packet.h"
  54 #include "xmalloc.h"
  55 #include "log.h"
  56 #include "misc.h"
  57 #include "channels.h"
  58 #include "compat.h"
  59 #include "canohost.h"
  60 #include "key.h"
  61 #include "authfd.h"
  62 #include "pathnames.h"
  63 #include "bufaux.h"
  64
  65 /* -- channel core */
  66
  67 /*
  68  * Pointer to an array containing all allocated channels.  The array is
  69  * dynamically extended as needed.
  70  */
  71 static Channel **channels = NULL;
  72
  73 /*
  74  * Size of the channel array.  All slots of the array must always be
  75  * initialized (at least the type field); unused slots set to NULL
  76  */
  77 static u_int channels_alloc = 0;
  78
  79 /*
  80  * Maximum file descriptor value used in any of the channels.  This is
  81  * updated in channel_new.
  82  */
  83 static int channel_max_fd = 0;
  84
  85
  86 /* -- tcp forwarding */
  87
  88 /*
  89  * Data structure for storing which hosts are permitted for forward requests.
  90  * The local sides of any remote forwards are stored in this array to prevent
  91  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  92  * network (which might be behind a firewall).
  93  */
  94 typedef struct {
  95         char *host_to_connect;          /* Connect to 'host'. */
  96         u_short port_to_connect;        /* Connect to 'port'. */
  97         u_short listen_port;            /* Remote side should listen port number. */
  98 } ForwardPermission;
  99
 100 /* List of all permitted host/port pairs to connect. */
 101 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 102
 103 /* Number of permitted host/port pairs in the array. */
 104 static int num_permitted_opens = 0;
 105 /*
 106  * If this is true, all opens are permitted.  This is the case on the server
 107  * on which we have to trust the client anyway, and the user could do
 108  * anything after logging in anyway.
 109  */
 110 static int all_opens_permitted = 0;
 111
 112
 113 /* -- X11 forwarding */
 114
 115 /* Maximum number of fake X11 displays to try. */
 116 #define MAX_DISPLAYS  1000
 117
 118 /* Saved X11 local (client) display. */
 119 static char *x11_saved_display = NULL;
 120
 121 /* Saved X11 authentication protocol name. */
 122 static char *x11_saved_proto = NULL;
 123
 124 /* Saved X11 authentication data.  This is the real data. */
 125 static char *x11_saved_data = NULL;
 126 static u_int x11_saved_data_len = 0;
 127
 128 /*
 129  * Fake X11 authentication data.  This is what the server will be sending us;
 130  * we should replace any occurrences of this by the real data.
 131  */
 132 static char *x11_fake_data = NULL;
 133 static u_int x11_fake_data_len;
 134
 135
 136 /* -- agent forwarding */
 137
 138 #define NUM_SOCKS       10
 139
 140 /* AF_UNSPEC or AF_INET or AF_INET6 */
 141 static int IPv4or6 = AF_UNSPEC;
 142
 143 /* helper */
 144 static void port_open_helper(Channel *c, char *rtype);
 145
 146 /* -- channel core */
 147
 148 Channel *
 149 channel_by_id(int id)
 150 {
 151         Channel *c;
 152
 153         if (id < 0 || (u_int)id >= channels_alloc) {
 154                 logit("channel_by_id: %d: bad id", id);
 155                 return NULL;
 156         }
 157         c = channels[id];
 158         if (c == NULL) {
 159                 logit("channel_by_id: %d: bad id: channel free", id);
 160                 return NULL;
 161         }
 162         return c;
 163 }
 164
 165 /*
 166  * Returns the channel if it is allowed to receive protocol messages.
 167  * Private channels, like listening sockets, may not receive messages.
 168  */
 169 Channel *
 170 channel_lookup(int id)
 171 {
 172         Channel *c;
 173
 174         if ((c = channel_by_id(id)) == NULL)
 175                 return (NULL);
 176
 177         switch(c->type) {
 178         case SSH_CHANNEL_X11_OPEN:
 179         case SSH_CHANNEL_LARVAL:
 180         case SSH_CHANNEL_CONNECTING:
 181         case SSH_CHANNEL_DYNAMIC:
 182         case SSH_CHANNEL_OPENING:
 183         case SSH_CHANNEL_OPEN:
 184         case SSH_CHANNEL_INPUT_DRAINING:
 185         case SSH_CHANNEL_OUTPUT_DRAINING:
 186                 return (c);
 187                 break;
 188         }
 189         logit("Non-public channel %d, type %d.", id, c->type);
 190         return (NULL);
 191 }
 192
 193 /*
 194  * Register filedescriptors for a channel, used when allocating a channel or
 195  * when the channel consumer/producer is ready, e.g. shell exec'd
 196  */
 197
 198 static void
 199 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 200     int extusage, int nonblock)
 201 {
 202         /* Update the maximum file descriptor value. */
 203         channel_max_fd = MAX(channel_max_fd, rfd);
 204         channel_max_fd = MAX(channel_max_fd, wfd);
 205         channel_max_fd = MAX(channel_max_fd, efd);
 206
 207         /* XXX set close-on-exec -markus */
 208
 209         c->rfd = rfd;
 210         c->wfd = wfd;
 211         c->sock = (rfd == wfd) ? rfd : -1;
 212         c->ctl_fd = -1; /* XXX: set elsewhere */
 213         c->efd = efd;
 214         c->extended_usage = extusage;
 215
 216         /* XXX ugly hack: nonblock is only set by the server */
 217         if (nonblock && isatty(c->rfd)) {
 218                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 219                 c->isatty = 1;
 220                 if (!isatty(c->wfd)) {
 221                         error("channel %d: wfd %d is not a tty?",
 222                             c->self, c->wfd);
 223                 }
 224         } else {
 225                 c->isatty = 0;
 226         }
 227         c->wfd_isatty = isatty(c->wfd);
 228
 229         /* enable nonblocking mode */
 230         if (nonblock) {
 231                 if (rfd != -1)
 232                         set_nonblock(rfd);
 233                 if (wfd != -1)
 234                         set_nonblock(wfd);
 235                 if (efd != -1)
 236                         set_nonblock(efd);
 237         }
 238 }
 239
 240 /*
 241  * Allocate a new channel object and set its type and socket. This will cause
 242  * remote_name to be freed.
 243  */
 244
 245 Channel *
 246 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 247     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 248 {
 249         int found;
 250         u_int i;
 251         Channel *c;
 252
 253         /* Do initial allocation if this is the first call. */
 254         if (channels_alloc == 0) {
 255                 channels_alloc = 10;
 256                 channels = xmalloc(channels_alloc * sizeof(Channel *));
 257                 for (i = 0; i < channels_alloc; i++)
 258                         channels[i] = NULL;
 259         }
 260         /* Try to find a free slot where to put the new channel. */
 261         for (found = -1, i = 0; i < channels_alloc; i++)
 262                 if (channels[i] == NULL) {
 263                         /* Found a free slot. */
 264                         found = (int)i;
 265                         break;
 266                 }
 267         if (found < 0) {
 268                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 269                 found = channels_alloc;
 270                 if (channels_alloc > 10000)
 271                         fatal("channel_new: internal error: channels_alloc %d "
 272                             "too big.", channels_alloc);
 273                 channels = xrealloc(channels,
 274                     (channels_alloc + 10) * sizeof(Channel *));
 275                 channels_alloc += 10;
 276                 debug2("channel: expanding %d", channels_alloc);
 277                 for (i = found; i < channels_alloc; i++)
 278                         channels[i] = NULL;
 279         }
 280         /* Initialize and return new channel. */
 281         c = channels[found] = xmalloc(sizeof(Channel));
 282         memset(c, 0, sizeof(Channel));
 283         buffer_init(&c->input);
 284         buffer_init(&c->output);
 285         buffer_init(&c->extended);
 286         c->ostate = CHAN_OUTPUT_OPEN;
 287         c->istate = CHAN_INPUT_OPEN;
 288         c->flags = 0;
 289         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 290         c->self = found;
 291         c->type = type;
 292         c->ctype = ctype;
 293         c->local_window = window;
 294         c->local_window_max = window;
 295         c->local_consumed = 0;
 296         c->local_maxpacket = maxpack;
 297         c->remote_id = -1;
 298         c->remote_name = xstrdup(remote_name);
 299         c->remote_window = 0;
 300         c->remote_maxpacket = 0;
 301         c->force_drain = 0;
 302         c->single_connection = 0;
 303         c->detach_user = NULL;
 304         c->detach_close = 0;
 305         c->confirm = NULL;
 306         c->confirm_ctx = NULL;
 307         c->input_filter = NULL;
 308         c->output_filter = NULL;
 309         debug("channel %d: new [%s]", found, remote_name);
 310         return c;
 311 }
 312
 313 static int
 314 channel_find_maxfd(void)
 315 {
 316         u_int i;
 317         int max = 0;
 318         Channel *c;
 319
 320         for (i = 0; i < channels_alloc; i++) {
 321                 c = channels[i];
 322                 if (c != NULL) {
 323                         max = MAX(max, c->rfd);
 324                         max = MAX(max, c->wfd);
 325                         max = MAX(max, c->efd);
 326                 }
 327         }
 328         return max;
 329 }
 330
 331 int
 332 channel_close_fd(int *fdp)
 333 {
 334         int ret = 0, fd = *fdp;
 335
 336         if (fd != -1) {
 337                 ret = close(fd);
 338                 *fdp = -1;
 339                 if (fd == channel_max_fd)
 340                         channel_max_fd = channel_find_maxfd();
 341         }
 342         return ret;
 343 }
 344
 345 /* Close all channel fd/socket. */
 346
 347 static void
 348 channel_close_fds(Channel *c)
 349 {
 350         debug3("channel %d: close_fds r %d w %d e %d c %d",
 351             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 352
 353         channel_close_fd(&c->sock);
 354         channel_close_fd(&c->ctl_fd);
 355         channel_close_fd(&c->rfd);
 356         channel_close_fd(&c->wfd);
 357         channel_close_fd(&c->efd);
 358 }
 359
 360 /* Free the channel and close its fd/socket. */
 361
 362 void
 363 channel_free(Channel *c)
 364 {
 365         char *s;
 366         u_int i, n;
 367
 368         for (n = 0, i = 0; i < channels_alloc; i++)
 369                 if (channels[i])
 370                         n++;
 371         debug("channel %d: free: %s, nchannels %u", c->self,
 372             c->remote_name ? c->remote_name : "???", n);
 373
 374         s = channel_open_message();
 375         debug3("channel %d: status: %s", c->self, s);
 376         xfree(s);
 377
 378         if (c->sock != -1)
 379                 shutdown(c->sock, SHUT_RDWR);
 380         if (c->ctl_fd != -1)
 381                 shutdown(c->ctl_fd, SHUT_RDWR);
 382         channel_close_fds(c);
 383         buffer_free(&c->input);
 384         buffer_free(&c->output);
 385         buffer_free(&c->extended);
 386         if (c->remote_name) {
 387                 xfree(c->remote_name);
 388                 c->remote_name = NULL;
 389         }
 390         channels[c->self] = NULL;
 391         xfree(c);
 392 }
 393
 394 void
 395 channel_free_all(void)
 396 {
 397         u_int i;
 398
 399         for (i = 0; i < channels_alloc; i++)
 400                 if (channels[i] != NULL)
 401                         channel_free(channels[i]);
 402 }
 403
 404 /*
 405  * Closes the sockets/fds of all channels.  This is used to close extra file
 406  * descriptors after a fork.
 407  */
 408
 409 void
 410 channel_close_all(void)
 411 {
 412         u_int i;
 413
 414         for (i = 0; i < channels_alloc; i++)
 415                 if (channels[i] != NULL)
 416                         channel_close_fds(channels[i]);
 417 }
 418
 419 /*
 420  * Stop listening to channels.
 421  */
 422
 423 void
 424 channel_stop_listening(void)
 425 {
 426         u_int i;
 427         Channel *c;
 428
 429         for (i = 0; i < channels_alloc; i++) {
 430                 c = channels[i];
 431                 if (c != NULL) {
 432                         switch (c->type) {
 433                         case SSH_CHANNEL_AUTH_SOCKET:
 434                         case SSH_CHANNEL_PORT_LISTENER:
 435                         case SSH_CHANNEL_RPORT_LISTENER:
 436                         case SSH_CHANNEL_X11_LISTENER:
 437                                 channel_close_fd(&c->sock);
 438                                 channel_free(c);
 439                                 break;
 440                         }
 441                 }
 442         }
 443 }
 444
 445 /*
 446  * Returns true if no channel has too much buffered data, and false if one or
 447  * more channel is overfull.
 448  */
 449
 450 int
 451 channel_not_very_much_buffered_data(void)
 452 {
 453         u_int i;
 454         Channel *c;
 455
 456         for (i = 0; i < channels_alloc; i++) {
 457                 c = channels[i];
 458                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 459 #if 0
 460                         if (!compat20 &&
 461                             buffer_len(&c->input) > packet_get_maxsize()) {
 462                                 debug2("channel %d: big input buffer %d",
 463                                     c->self, buffer_len(&c->input));
 464                                 return 0;
 465                         }
 466 #endif
 467                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 468                                 debug2("channel %d: big output buffer %u > %u",
 469                                     c->self, buffer_len(&c->output),
 470                                     packet_get_maxsize());
 471                                 return 0;
 472                         }
 473                 }
 474         }
 475         return 1;
 476 }
 477
 478 /* Returns true if any channel is still open. */
 479
 480 int
 481 channel_still_open(void)
 482 {
 483         u_int i;
 484         Channel *c;
 485
 486         for (i = 0; i < channels_alloc; i++) {
 487                 c = channels[i];
 488                 if (c == NULL)
 489                         continue;
 490                 switch (c->type) {
 491                 case SSH_CHANNEL_X11_LISTENER:
 492                 case SSH_CHANNEL_PORT_LISTENER:
 493                 case SSH_CHANNEL_RPORT_LISTENER:
 494                 case SSH_CHANNEL_CLOSED:
 495                 case SSH_CHANNEL_AUTH_SOCKET:
 496                 case SSH_CHANNEL_DYNAMIC:
 497                 case SSH_CHANNEL_CONNECTING:
 498                 case SSH_CHANNEL_ZOMBIE:
 499                         continue;
 500                 case SSH_CHANNEL_LARVAL:
 501                         if (!compat20)
 502                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 503                         continue;
 504                 case SSH_CHANNEL_OPENING:
 505                 case SSH_CHANNEL_OPEN:
 506                 case SSH_CHANNEL_X11_OPEN:
 507                         return 1;
 508                 case SSH_CHANNEL_INPUT_DRAINING:
 509                 case SSH_CHANNEL_OUTPUT_DRAINING:
 510                         if (!compat13)
 511                                 fatal("cannot happen: OUT_DRAIN");
 512                         return 1;
 513                 default:
 514                         fatal("channel_still_open: bad channel type %d", c->type);
 515                         /* NOTREACHED */
 516                 }
 517         }
 518         return 0;
 519 }
 520
 521 /* Returns the id of an open channel suitable for keepaliving */
 522
 523 int
 524 channel_find_open(void)
 525 {
 526         u_int i;
 527         Channel *c;
 528
 529         for (i = 0; i < channels_alloc; i++) {
 530                 c = channels[i];
 531                 if (c == NULL || c->remote_id < 0)
 532                         continue;
 533                 switch (c->type) {
 534                 case SSH_CHANNEL_CLOSED:
 535                 case SSH_CHANNEL_DYNAMIC:
 536                 case SSH_CHANNEL_X11_LISTENER:
 537                 case SSH_CHANNEL_PORT_LISTENER:
 538                 case SSH_CHANNEL_RPORT_LISTENER:
 539                 case SSH_CHANNEL_OPENING:
 540                 case SSH_CHANNEL_CONNECTING:
 541                 case SSH_CHANNEL_ZOMBIE:
 542                         continue;
 543                 case SSH_CHANNEL_LARVAL:
 544                 case SSH_CHANNEL_AUTH_SOCKET:
 545                 case SSH_CHANNEL_OPEN:
 546                 case SSH_CHANNEL_X11_OPEN:
 547                         return i;
 548                 case SSH_CHANNEL_INPUT_DRAINING:
 549                 case SSH_CHANNEL_OUTPUT_DRAINING:
 550                         if (!compat13)
 551                                 fatal("cannot happen: OUT_DRAIN");
 552                         return i;
 553                 default:
 554                         fatal("channel_find_open: bad channel type %d", c->type);
 555                         /* NOTREACHED */
 556                 }
 557         }
 558         return -1;
 559 }
 560
 561
 562 /*
 563  * Returns a message describing the currently open forwarded connections,
 564  * suitable for sending to the client.  The message contains crlf pairs for
 565  * newlines.
 566  */
 567
 568 char *
 569 channel_open_message(void)
 570 {
 571         Buffer buffer;
 572         Channel *c;
 573         char buf[1024], *cp;
 574         u_int i;
 575
 576         buffer_init(&buffer);
 577         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 578         buffer_append(&buffer, buf, strlen(buf));
 579         for (i = 0; i < channels_alloc; i++) {
 580                 c = channels[i];
 581                 if (c == NULL)
 582                         continue;
 583                 switch (c->type) {
 584                 case SSH_CHANNEL_X11_LISTENER:
 585                 case SSH_CHANNEL_PORT_LISTENER:
 586                 case SSH_CHANNEL_RPORT_LISTENER:
 587                 case SSH_CHANNEL_CLOSED:
 588                 case SSH_CHANNEL_AUTH_SOCKET:
 589                 case SSH_CHANNEL_ZOMBIE:
 590                         continue;
 591                 case SSH_CHANNEL_LARVAL:
 592                 case SSH_CHANNEL_OPENING:
 593                 case SSH_CHANNEL_CONNECTING:
 594                 case SSH_CHANNEL_DYNAMIC:
 595                 case SSH_CHANNEL_OPEN:
 596                 case SSH_CHANNEL_X11_OPEN:
 597                 case SSH_CHANNEL_INPUT_DRAINING:
 598                 case SSH_CHANNEL_OUTPUT_DRAINING:
 599                         snprintf(buf, sizeof buf,
 600                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 601                             c->self, c->remote_name,
 602                             c->type, c->remote_id,
 603                             c->istate, buffer_len(&c->input),
 604                             c->ostate, buffer_len(&c->output),
 605                             c->rfd, c->wfd, c->ctl_fd);
 606                         buffer_append(&buffer, buf, strlen(buf));
 607                         continue;
 608                 default:
 609                         fatal("channel_open_message: bad channel type %d", c->type);
 610                         /* NOTREACHED */
 611                 }
 612         }
 613         buffer_append(&buffer, "\0", 1);
 614         cp = xstrdup(buffer_ptr(&buffer));
 615         buffer_free(&buffer);
 616         return cp;
 617 }
 618
 619 void
 620 channel_send_open(int id)
 621 {
 622         Channel *c = channel_lookup(id);
 623
 624         if (c == NULL) {
 625                 logit("channel_send_open: %d: bad id", id);
 626                 return;
 627         }
 628         debug2("channel %d: send open", id);
 629         packet_start(SSH2_MSG_CHANNEL_OPEN);
 630         packet_put_cstring(c->ctype);
 631         packet_put_int(c->self);
 632         packet_put_int(c->local_window);
 633         packet_put_int(c->local_maxpacket);
 634         packet_send();
 635 }
 636
 637 void
 638 channel_request_start(int id, char *service, int wantconfirm)
 639 {
 640         Channel *c = channel_lookup(id);
 641
 642         if (c == NULL) {
 643                 logit("channel_request_start: %d: unknown channel id", id);
 644                 return;
 645         }
 646         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 647         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 648         packet_put_int(c->remote_id);
 649         packet_put_cstring(service);
 650         packet_put_char(wantconfirm);
 651 }
 652 void
 653 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 654 {
 655         Channel *c = channel_lookup(id);
 656
 657         if (c == NULL) {
 658                 logit("channel_register_comfirm: %d: bad id", id);
 659                 return;
 660         }
 661         c->confirm = fn;
 662         c->confirm_ctx = ctx;
 663 }
 664 void
 665 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 666 {
 667         Channel *c = channel_by_id(id);
 668
 669         if (c == NULL) {
 670                 logit("channel_register_cleanup: %d: bad id", id);
 671                 return;
 672         }
 673         c->detach_user = fn;
 674         c->detach_close = do_close;
 675 }
 676 void
 677 channel_cancel_cleanup(int id)
 678 {
 679         Channel *c = channel_by_id(id);
 680
 681         if (c == NULL) {
 682                 logit("channel_cancel_cleanup: %d: bad id", id);
 683                 return;
 684         }
 685         c->detach_user = NULL;
 686         c->detach_close = 0;
 687 }
 688 void
 689 channel_register_filter(int id, channel_infilter_fn *ifn,
 690     channel_outfilter_fn *ofn)
 691 {
 692         Channel *c = channel_lookup(id);
 693
 694         if (c == NULL) {
 695                 logit("channel_register_filter: %d: bad id", id);
 696                 return;
 697         }
 698         c->input_filter = ifn;
 699         c->output_filter = ofn;
 700 }
 701
 702 void
 703 channel_set_fds(int id, int rfd, int wfd, int efd,
 704     int extusage, int nonblock, u_int window_max)
 705 {
 706         Channel *c = channel_lookup(id);
 707
 708         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 709                 fatal("channel_activate for non-larval channel %d.", id);
 710         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 711         c->type = SSH_CHANNEL_OPEN;
 712         c->local_window = c->local_window_max = window_max;
 713         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 714         packet_put_int(c->remote_id);
 715         packet_put_int(c->local_window);
 716         packet_send();
 717 }
 718
 719 /*
 720  * 'channel_pre*' are called just before select() to add any bits relevant to
 721  * channels in the select bitmasks.
 722  */
 723 /*
 724  * 'channel_post*': perform any appropriate operations for channels which
 725  * have events pending.
 726  */
 727 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 728 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 729 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 730
 731 static void
 732 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 733 {
 734         FD_SET(c->sock, readset);
 735 }
 736
 737 static void
 738 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 739 {
 740         debug3("channel %d: waiting for connection", c->self);
 741         FD_SET(c->sock, writeset);
 742 }
 743
 744 static void
 745 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 746 {
 747         if (buffer_len(&c->input) < packet_get_maxsize())
 748                 FD_SET(c->sock, readset);
 749         if (buffer_len(&c->output) > 0)
 750                 FD_SET(c->sock, writeset);
 751 }
 752
 753 static void
 754 channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
 755 {
 756         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 757
 758         /* check buffer limits */
 759         limit = MIN(limit, (BUFFER_MAX_LEN - BUFFER_MAX_CHUNK - CHAN_RBUF));
 760
 761         if (c->istate == CHAN_INPUT_OPEN &&
 762             limit > 0 &&
 763             buffer_len(&c->input) < limit)
 764                 FD_SET(c->rfd, readset);
 765         if (c->ostate == CHAN_OUTPUT_OPEN ||
 766             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 767                 if (buffer_len(&c->output) > 0) {
 768                         FD_SET(c->wfd, writeset);
 769                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 770                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 771                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 772                                     c->self, c->efd, buffer_len(&c->extended));
 773                         else
 774                                 chan_obuf_empty(c);
 775                 }
 776         }
 777         /** XXX check close conditions, too */
 778         if (compat20 && c->efd != -1) {
 779                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 780                     buffer_len(&c->extended) > 0)
 781                         FD_SET(c->efd, writeset);
 782                 else if (!(c->flags & CHAN_EOF_SENT) &&
 783                     c->extended_usage == CHAN_EXTENDED_READ &&
 784                     buffer_len(&c->extended) < c->remote_window)
 785                         FD_SET(c->efd, readset);
 786         }
 787         /* XXX: What about efd? races? */
 788         if (compat20 && c->ctl_fd != -1 &&
 789             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 790                 FD_SET(c->ctl_fd, readset);
 791 }
 792
 793 static void
 794 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 795 {
 796         if (buffer_len(&c->input) == 0) {
 797                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 798                 packet_put_int(c->remote_id);
 799                 packet_send();
 800                 c->type = SSH_CHANNEL_CLOSED;
 801                 debug2("channel %d: closing after input drain.", c->self);
 802         }
 803 }
 804
 805 static void
 806 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 807 {
 808         if (buffer_len(&c->output) == 0)
 809                 chan_mark_dead(c);
 810         else
 811                 FD_SET(c->sock, writeset);
 812 }
 813
 814 /*
 815  * This is a special state for X11 authentication spoofing.  An opened X11
 816  * connection (when authentication spoofing is being done) remains in this
 817  * state until the first packet has been completely read.  The authentication
 818  * data in that packet is then substituted by the real data if it matches the
 819  * fake data, and the channel is put into normal mode.
 820  * XXX All this happens at the client side.
 821  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 822  */
 823 static int
 824 x11_open_helper(Buffer *b)
 825 {
 826         u_char *ucp;
 827         u_int proto_len, data_len;
 828
 829         /* Check if the fixed size part of the packet is in buffer. */
 830         if (buffer_len(b) < 12)
 831                 return 0;
 832
 833         /* Parse the lengths of variable-length fields. */
 834         ucp = buffer_ptr(b);
 835         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 836                 proto_len = 256 * ucp[6] + ucp[7];
 837                 data_len = 256 * ucp[8] + ucp[9];
 838         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 839                 proto_len = ucp[6] + 256 * ucp[7];
 840                 data_len = ucp[8] + 256 * ucp[9];
 841         } else {
 842                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 843                     ucp[0]);
 844                 return -1;
 845         }
 846
 847         /* Check if the whole packet is in buffer. */
 848         if (buffer_len(b) <
 849             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 850                 return 0;
 851
 852         /* Check if authentication protocol matches. */
 853         if (proto_len != strlen(x11_saved_proto) ||
 854             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 855                 debug2("X11 connection uses different authentication protocol.");
 856                 return -1;
 857         }
 858         /* Check if authentication data matches our fake data. */
 859         if (data_len != x11_fake_data_len ||
 860             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 861                 x11_fake_data, x11_fake_data_len) != 0) {
 862                 debug2("X11 auth data does not match fake data.");
 863                 return -1;
 864         }
 865         /* Check fake data length */
 866         if (x11_fake_data_len != x11_saved_data_len) {
 867                 error("X11 fake_data_len %d != saved_data_len %d",
 868                     x11_fake_data_len, x11_saved_data_len);
 869                 return -1;
 870         }
 871         /*
 872          * Received authentication protocol and data match
 873          * our fake data. Substitute the fake data with real
 874          * data.
 875          */
 876         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 877             x11_saved_data, x11_saved_data_len);
 878         return 1;
 879 }
 880
 881 static void
 882 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 883 {
 884         int ret = x11_open_helper(&c->output);
 885
 886         if (ret == 1) {
 887                 /* Start normal processing for the channel. */
 888                 c->type = SSH_CHANNEL_OPEN;
 889                 channel_pre_open_13(c, readset, writeset);
 890         } else if (ret == -1) {
 891                 /*
 892                  * We have received an X11 connection that has bad
 893                  * authentication information.
 894                  */
 895                 logit("X11 connection rejected because of wrong authentication.");
 896                 buffer_clear(&c->input);
 897                 buffer_clear(&c->output);
 898                 channel_close_fd(&c->sock);
 899                 c->sock = -1;
 900                 c->type = SSH_CHANNEL_CLOSED;
 901                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 902                 packet_put_int(c->remote_id);
 903                 packet_send();
 904         }
 905 }
 906
 907 static void
 908 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
 909 {
 910         int ret = x11_open_helper(&c->output);
 911
 912         /* c->force_drain = 1; */
 913
 914         if (ret == 1) {
 915                 c->type = SSH_CHANNEL_OPEN;
 916                 channel_pre_open(c, readset, writeset);
 917         } else if (ret == -1) {
 918                 logit("X11 connection rejected because of wrong authentication.");
 919                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 920                 chan_read_failed(c);
 921                 buffer_clear(&c->input);
 922                 chan_ibuf_empty(c);
 923                 buffer_clear(&c->output);
 924                 /* for proto v1, the peer will send an IEOF */
 925                 if (compat20)
 926                         chan_write_failed(c);
 927                 else
 928                         c->type = SSH_CHANNEL_OPEN;
 929                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 930         }
 931 }
 932
 933 /* try to decode a socks4 header */
 934 static int
 935 channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
 936 {
 937         char *p, *host;
 938         u_int len, have, i, found;
 939         char username[256];
 940         struct {
 941                 u_int8_t version;
 942                 u_int8_t command;
 943                 u_int16_t dest_port;
 944                 struct in_addr dest_addr;
 945         } s4_req, s4_rsp;
 946
 947         debug2("channel %d: decode socks4", c->self);
 948
 949         have = buffer_len(&c->input);
 950         len = sizeof(s4_req);
 951         if (have < len)
 952                 return 0;
 953         p = buffer_ptr(&c->input);
 954         for (found = 0, i = len; i < have; i++) {
 955                 if (p[i] == '\0') {
 956                         found = 1;
 957                         break;
 958                 }
 959                 if (i > 1024) {
 960                         /* the peer is probably sending garbage */
 961                         debug("channel %d: decode socks4: too long",
 962                             c->self);
 963                         return -1;
 964                 }
 965         }
 966         if (!found)
 967                 return 0;
 968         buffer_get(&c->input, (char *)&s4_req.version, 1);
 969         buffer_get(&c->input, (char *)&s4_req.command, 1);
 970         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 971         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 972         have = buffer_len(&c->input);
 973         p = buffer_ptr(&c->input);
 974         len = strlen(p);
 975         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 976         if (len > have)
 977                 fatal("channel %d: decode socks4: len %d > have %d",
 978                     c->self, len, have);
 979         strlcpy(username, p, sizeof(username));
 980         buffer_consume(&c->input, len);
 981         buffer_consume(&c->input, 1);           /* trailing '\0' */
 982
 983         host = inet_ntoa(s4_req.dest_addr);
 984         strlcpy(c->path, host, sizeof(c->path));
 985         c->host_port = ntohs(s4_req.dest_port);
 986
 987         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 988             c->self, host, c->host_port, s4_req.command);
 989
 990         if (s4_req.command != 1) {
 991                 debug("channel %d: cannot handle: socks4 cn %d",
 992                     c->self, s4_req.command);
 993                 return -1;
 994         }
 995         s4_rsp.version = 0;                     /* vn: 0 for reply */
 996         s4_rsp.command = 90;                    /* cd: req granted */
 997         s4_rsp.dest_port = 0;                   /* ignored */
 998         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 999         buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
1000         return 1;
1001 }
1002
1003 /* try to decode a socks5 header */
1004 #define SSH_SOCKS5_AUTHDONE     0x1000
1005 #define SSH_SOCKS5_NOAUTH       0x00
1006 #define SSH_SOCKS5_IPV4         0x01
1007 #define SSH_SOCKS5_DOMAIN       0x03
1008 #define SSH_SOCKS5_IPV6         0x04
1009 #define SSH_SOCKS5_CONNECT      0x01
1010 #define SSH_SOCKS5_SUCCESS      0x00
1011
1012 static int
1013 channel_decode_socks5(Channel *c, fd_set * readset, fd_set * writeset)
1014 {
1015         struct {
1016                 u_int8_t version;
1017                 u_int8_t command;
1018                 u_int8_t reserved;
1019                 u_int8_t atyp;
1020         } s5_req, s5_rsp;
1021         u_int16_t dest_port;
1022         u_char *p, dest_addr[255+1];
1023         u_int have, i, found, nmethods, addrlen, af;
1024
1025         debug2("channel %d: decode socks5", c->self);
1026         p = buffer_ptr(&c->input);
1027         if (p[0] != 0x05)
1028                 return -1;
1029         have = buffer_len(&c->input);
1030         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1031                 /* format: ver | nmethods | methods */
1032                 if (have < 2)
1033                         return 0;
1034                 nmethods = p[1];
1035                 if (have < nmethods + 2)
1036                         return 0;
1037                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1038                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1039                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
1040                                 found = 1;
1041                                 break;
1042                         }
1043                 }
1044                 if (!found) {
1045                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1046                             c->self);
1047                         return -1;
1048                 }
1049                 buffer_consume(&c->input, nmethods + 2);
1050                 buffer_put_char(&c->output, 0x05);              /* version */
1051                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1052                 FD_SET(c->sock, writeset);
1053                 c->flags |= SSH_SOCKS5_AUTHDONE;
1054                 debug2("channel %d: socks5 auth done", c->self);
1055                 return 0;                               /* need more */
1056         }
1057         debug2("channel %d: socks5 post auth", c->self);
1058         if (have < sizeof(s5_req)+1)
1059                 return 0;                       /* need more */
1060         memcpy((char *)&s5_req, p, sizeof(s5_req));
1061         if (s5_req.version != 0x05 ||
1062             s5_req.command != SSH_SOCKS5_CONNECT ||
1063             s5_req.reserved != 0x00) {
1064                 debug2("channel %d: only socks5 connect supported", c->self);
1065                 return -1;
1066         }
1067         switch (s5_req.atyp){
1068         case SSH_SOCKS5_IPV4:
1069                 addrlen = 4;
1070                 af = AF_INET;
1071                 break;
1072         case SSH_SOCKS5_DOMAIN:
1073                 addrlen = p[sizeof(s5_req)];
1074                 af = -1;
1075                 break;
1076         case SSH_SOCKS5_IPV6:
1077                 addrlen = 16;
1078                 af = AF_INET6;
1079                 break;
1080         default:
1081                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1082                 return -1;
1083         }
1084         if (have < 4 + addrlen + 2)
1085                 return 0;
1086         buffer_consume(&c->input, sizeof(s5_req));
1087         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1088                 buffer_consume(&c->input, 1);    /* host string length */
1089         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1090         buffer_get(&c->input, (char *)&dest_port, 2);
1091         dest_addr[addrlen] = '\0';
1092         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1093                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1094         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1095                 return -1;
1096         c->host_port = ntohs(dest_port);
1097
1098         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1099             c->self, c->path, c->host_port, s5_req.command);
1100
1101         s5_rsp.version = 0x05;
1102         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1103         s5_rsp.reserved = 0;                    /* ignored */
1104         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1105         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1106         dest_port = 0;                          /* ignored */
1107
1108         buffer_append(&c->output, (char *)&s5_rsp, sizeof(s5_rsp));
1109         buffer_append(&c->output, (char *)&dest_addr, sizeof(struct in_addr));
1110         buffer_append(&c->output, (char *)&dest_port, sizeof(dest_port));
1111         return 1;
1112 }
1113
1114 /* dynamic port forwarding */
1115 static void
1116 channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
1117 {
1118         u_char *p;
1119         u_int have;
1120         int ret;
1121
1122         have = buffer_len(&c->input);
1123         c->delayed = 0;
1124         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1125         /* buffer_dump(&c->input); */
1126         /* check if the fixed size part of the packet is in buffer. */
1127         if (have < 3) {
1128                 /* need more */
1129                 FD_SET(c->sock, readset);
1130                 return;
1131         }
1132         /* try to guess the protocol */
1133         p = buffer_ptr(&c->input);
1134         switch (p[0]) {
1135         case 0x04:
1136                 ret = channel_decode_socks4(c, readset, writeset);
1137                 break;
1138         case 0x05:
1139                 ret = channel_decode_socks5(c, readset, writeset);
1140                 break;
1141         default:
1142                 ret = -1;
1143                 break;
1144         }
1145         if (ret < 0) {
1146                 chan_mark_dead(c);
1147         } else if (ret == 0) {
1148                 debug2("channel %d: pre_dynamic: need more", c->self);
1149                 /* need more */
1150                 FD_SET(c->sock, readset);
1151         } else {
1152                 /* switch to the next state */
1153                 c->type = SSH_CHANNEL_OPENING;
1154                 port_open_helper(c, "direct-tcpip");
1155         }
1156 }
1157
1158 /* This is our fake X11 server socket. */
1159 static void
1160 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
1161 {
1162         Channel *nc;
1163         struct sockaddr addr;
1164         int newsock;
1165         socklen_t addrlen;
1166         char buf[16384], *remote_ipaddr;
1167         int remote_port;
1168
1169         if (FD_ISSET(c->sock, readset)) {
1170                 debug("X11 connection requested.");
1171                 addrlen = sizeof(addr);
1172                 newsock = accept(c->sock, &addr, &addrlen);
1173                 if (c->single_connection) {
1174                         debug2("single_connection: closing X11 listener.");
1175                         channel_close_fd(&c->sock);
1176                         chan_mark_dead(c);
1177                 }
1178                 if (newsock < 0) {
1179                         error("accept: %.100s", strerror(errno));
1180                         return;
1181                 }
1182                 set_nodelay(newsock);
1183                 remote_ipaddr = get_peer_ipaddr(newsock);
1184                 remote_port = get_peer_port(newsock);
1185                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1186                     remote_ipaddr, remote_port);
1187
1188                 nc = channel_new("accepted x11 socket",
1189                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1190                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1191                 if (compat20) {
1192                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1193                         packet_put_cstring("x11");
1194                         packet_put_int(nc->self);
1195                         packet_put_int(nc->local_window_max);
1196                         packet_put_int(nc->local_maxpacket);
1197                         /* originator ipaddr and port */
1198                         packet_put_cstring(remote_ipaddr);
1199                         if (datafellows & SSH_BUG_X11FWD) {
1200                                 debug2("ssh2 x11 bug compat mode");
1201                         } else {
1202                                 packet_put_int(remote_port);
1203                         }
1204                         packet_send();
1205                 } else {
1206                         packet_start(SSH_SMSG_X11_OPEN);
1207                         packet_put_int(nc->self);
1208                         if (packet_get_protocol_flags() &
1209                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1210                                 packet_put_cstring(buf);
1211                         packet_send();
1212                 }
1213                 xfree(remote_ipaddr);
1214         }
1215 }
1216
1217 static void
1218 port_open_helper(Channel *c, char *rtype)
1219 {
1220         int direct;
1221         char buf[1024];
1222         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1223         int remote_port = get_peer_port(c->sock);
1224
1225         direct = (strcmp(rtype, "direct-tcpip") == 0);
1226
1227         snprintf(buf, sizeof buf,
1228             "%s: listening port %d for %.100s port %d, "
1229             "connect from %.200s port %d",
1230             rtype, c->listening_port, c->path, c->host_port,
1231             remote_ipaddr, remote_port);
1232
1233         xfree(c->remote_name);
1234         c->remote_name = xstrdup(buf);
1235
1236         if (compat20) {
1237                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1238                 packet_put_cstring(rtype);
1239                 packet_put_int(c->self);
1240                 packet_put_int(c->local_window_max);
1241                 packet_put_int(c->local_maxpacket);
1242                 if (direct) {
1243                         /* target host, port */
1244                         packet_put_cstring(c->path);
1245                         packet_put_int(c->host_port);
1246                 } else {
1247                         /* listen address, port */
1248                         packet_put_cstring(c->path);
1249                         packet_put_int(c->listening_port);
1250                 }
1251                 /* originator host and port */
1252                 packet_put_cstring(remote_ipaddr);
1253                 packet_put_int((u_int)remote_port);
1254                 packet_send();
1255         } else {
1256                 packet_start(SSH_MSG_PORT_OPEN);
1257                 packet_put_int(c->self);
1258                 packet_put_cstring(c->path);
1259                 packet_put_int(c->host_port);
1260                 if (packet_get_protocol_flags() &
1261                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1262                         packet_put_cstring(c->remote_name);
1263                 packet_send();
1264         }
1265         xfree(remote_ipaddr);
1266 }
1267
1268 static void
1269 channel_set_reuseaddr(int fd)
1270 {
1271         int on = 1;
1272
1273         /*
1274          * Set socket options.
1275          * Allow local port reuse in TIME_WAIT.
1276          */
1277         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1278                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1279 }
1280
1281 /*
1282  * This socket is listening for connections to a forwarded TCP/IP port.
1283  */
1284 static void
1285 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
1286 {
1287         Channel *nc;
1288         struct sockaddr addr;
1289         int newsock, nextstate;
1290         socklen_t addrlen;
1291         char *rtype;
1292
1293         if (FD_ISSET(c->sock, readset)) {
1294                 debug("Connection to port %d forwarding "
1295                     "to %.100s port %d requested.",
1296                     c->listening_port, c->path, c->host_port);
1297
1298                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1299                         nextstate = SSH_CHANNEL_OPENING;
1300                         rtype = "forwarded-tcpip";
1301                 } else {
1302                         if (c->host_port == 0) {
1303                                 nextstate = SSH_CHANNEL_DYNAMIC;
1304                                 rtype = "dynamic-tcpip";
1305                         } else {
1306                                 nextstate = SSH_CHANNEL_OPENING;
1307                                 rtype = "direct-tcpip";
1308                         }
1309                 }
1310
1311                 addrlen = sizeof(addr);
1312                 newsock = accept(c->sock, &addr, &addrlen);
1313                 if (newsock < 0) {
1314                         error("accept: %.100s", strerror(errno));
1315                         return;
1316                 }
1317                 set_nodelay(newsock);
1318                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1319                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1320                 nc->listening_port = c->listening_port;
1321                 nc->host_port = c->host_port;
1322                 strlcpy(nc->path, c->path, sizeof(nc->path));
1323
1324                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1325                         /*
1326                          * do not call the channel_post handler until
1327                          * this flag has been reset by a pre-handler.
1328                          * otherwise the FD_ISSET calls might overflow
1329                          */
1330                         nc->delayed = 1;
1331                 } else {
1332                         port_open_helper(nc, rtype);
1333                 }
1334         }
1335 }
1336
1337 /*
1338  * This is the authentication agent socket listening for connections from
1339  * clients.
1340  */
1341 static void
1342 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
1343 {
1344         Channel *nc;
1345         int newsock;
1346         struct sockaddr addr;
1347         socklen_t addrlen;
1348
1349         if (FD_ISSET(c->sock, readset)) {
1350                 addrlen = sizeof(addr);
1351                 newsock = accept(c->sock, &addr, &addrlen);
1352                 if (newsock < 0) {
1353                         error("accept from auth socket: %.100s", strerror(errno));
1354                         return;
1355                 }
1356                 nc = channel_new("accepted auth socket",
1357                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1358                     c->local_window_max, c->local_maxpacket,
1359                     0, "accepted auth socket", 1);
1360                 if (compat20) {
1361                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1362                         packet_put_cstring("auth-agent@openssh.com");
1363                         packet_put_int(nc->self);
1364                         packet_put_int(c->local_window_max);
1365                         packet_put_int(c->local_maxpacket);
1366                 } else {
1367                         packet_start(SSH_SMSG_AGENT_OPEN);
1368                         packet_put_int(nc->self);
1369                 }
1370                 packet_send();
1371         }
1372 }
1373
1374 static void
1375 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
1376 {
1377         int err = 0;
1378         socklen_t sz = sizeof(err);
1379
1380         if (FD_ISSET(c->sock, writeset)) {
1381                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1382                         err = errno;
1383                         error("getsockopt SO_ERROR failed");
1384                 }
1385                 if (err == 0) {
1386                         debug("channel %d: connected", c->self);
1387                         c->type = SSH_CHANNEL_OPEN;
1388                         if (compat20) {
1389                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1390                                 packet_put_int(c->remote_id);
1391                                 packet_put_int(c->self);
1392                                 packet_put_int(c->local_window);
1393                                 packet_put_int(c->local_maxpacket);
1394                         } else {
1395                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1396                                 packet_put_int(c->remote_id);
1397                                 packet_put_int(c->self);
1398                         }
1399                 } else {
1400                         debug("channel %d: not connected: %s",
1401                             c->self, strerror(err));
1402                         if (compat20) {
1403                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1404                                 packet_put_int(c->remote_id);
1405                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1406                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1407                                         packet_put_cstring(strerror(err));
1408                                         packet_put_cstring("");
1409                                 }
1410                         } else {
1411                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1412                                 packet_put_int(c->remote_id);
1413                         }
1414                         chan_mark_dead(c);
1415                 }
1416                 packet_send();
1417         }
1418 }
1419
1420 static int
1421 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
1422 {
1423         char buf[CHAN_RBUF];
1424         int len;
1425
1426         if (c->rfd != -1 &&
1427             FD_ISSET(c->rfd, readset)) {
1428                 len = read(c->rfd, buf, sizeof(buf));
1429                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1430                         return 1;
1431                 if (len <= 0) {
1432                         debug2("channel %d: read<=0 rfd %d len %d",
1433                             c->self, c->rfd, len);
1434                         if (c->type != SSH_CHANNEL_OPEN) {
1435                                 debug2("channel %d: not open", c->self);
1436                                 chan_mark_dead(c);
1437                                 return -1;
1438                         } else if (compat13) {
1439                                 buffer_clear(&c->output);
1440                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1441                                 debug2("channel %d: input draining.", c->self);
1442                         } else {
1443                                 chan_read_failed(c);
1444                         }
1445                         return -1;
1446                 }
1447                 if (c->input_filter != NULL) {
1448                         if (c->input_filter(c, buf, len) == -1) {
1449                                 debug2("channel %d: filter stops", c->self);
1450                                 chan_read_failed(c);
1451                         }
1452                 } else if (c->datagram) {
1453                         buffer_put_string(&c->input, buf, len);
1454                 } else {
1455                         buffer_append(&c->input, buf, len);
1456                 }
1457         }
1458         return 1;
1459 }
1460 static int
1461 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
1462 {
1463         struct termios tio;
1464         u_char *data = NULL, *buf;
1465         u_int dlen;
1466         int len;
1467
1468         /* Send buffered output data to the socket. */
1469         if (c->wfd != -1 &&
1470             FD_ISSET(c->wfd, writeset) &&
1471             buffer_len(&c->output) > 0) {
1472                 if (c->output_filter != NULL) {
1473                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1474                                 debug2("channel %d: filter stops", c->self);
1475                                 if (c->type != SSH_CHANNEL_OPEN)
1476                                         chan_mark_dead(c);
1477                                 else
1478                                         chan_write_failed(c);
1479                                 return -1;
1480                         }
1481                 } else if (c->datagram) {
1482                         buf = data = buffer_get_string(&c->output, &dlen);
1483                 } else {
1484                         buf = data = buffer_ptr(&c->output);
1485                         dlen = buffer_len(&c->output);
1486                 }
1487
1488                 if (c->datagram) {
1489                         /* ignore truncated writes, datagrams might get lost */
1490                         c->local_consumed += dlen + 4;
1491                         len = write(c->wfd, buf, dlen);
1492                         xfree(data);
1493                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1494                                 return 1;
1495                         if (len <= 0) {
1496                                 if (c->type != SSH_CHANNEL_OPEN)
1497                                         chan_mark_dead(c);
1498                                 else
1499                                         chan_write_failed(c);
1500                                 return -1;
1501                         }
1502                         return 1;
1503                 }
1504 #ifdef _AIX
1505                 /* XXX: Later AIX versions can't push as much data to tty */
1506                 if (compat20 && c->wfd_isatty)
1507                         dlen = MIN(dlen, 8*1024);
1508 #endif
1509
1510                 len = write(c->wfd, buf, dlen);
1511                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1512                         return 1;
1513                 if (len <= 0) {
1514                         if (c->type != SSH_CHANNEL_OPEN) {
1515                                 debug2("channel %d: not open", c->self);
1516                                 chan_mark_dead(c);
1517                                 return -1;
1518                         } else if (compat13) {
1519                                 buffer_clear(&c->output);
1520                                 debug2("channel %d: input draining.", c->self);
1521                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1522                         } else {
1523                                 chan_write_failed(c);
1524                         }
1525                         return -1;
1526                 }
1527                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1528                         if (tcgetattr(c->wfd, &tio) == 0 &&
1529                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1530                                 /*
1531                                  * Simulate echo to reduce the impact of
1532                                  * traffic analysis. We need to match the
1533                                  * size of a SSH2_MSG_CHANNEL_DATA message
1534                                  * (4 byte channel id + buf)
1535                                  */
1536                                 packet_send_ignore(4 + len);
1537                                 packet_send();
1538                         }
1539                 }
1540                 buffer_consume(&c->output, len);
1541                 if (compat20 && len > 0) {
1542                         c->local_consumed += len;
1543                 }
1544         }
1545         return 1;
1546 }
1547 static int
1548 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
1549 {
1550         char buf[CHAN_RBUF];
1551         int len;
1552
1553 /** XXX handle drain efd, too */
1554         if (c->efd != -1) {
1555                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1556                     FD_ISSET(c->efd, writeset) &&
1557                     buffer_len(&c->extended) > 0) {
1558                         len = write(c->efd, buffer_ptr(&c->extended),
1559                             buffer_len(&c->extended));
1560                         debug2("channel %d: written %d to efd %d",
1561                             c->self, len, c->efd);
1562                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1563                                 return 1;
1564                         if (len <= 0) {
1565                                 debug2("channel %d: closing write-efd %d",
1566                                     c->self, c->efd);
1567                                 channel_close_fd(&c->efd);
1568                         } else {
1569                                 buffer_consume(&c->extended, len);
1570                                 c->local_consumed += len;
1571                         }
1572                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1573                     FD_ISSET(c->efd, readset)) {
1574                         len = read(c->efd, buf, sizeof(buf));
1575                         debug2("channel %d: read %d from efd %d",
1576                             c->self, len, c->efd);
1577                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1578                                 return 1;
1579                         if (len <= 0) {
1580                                 debug2("channel %d: closing read-efd %d",
1581                                     c->self, c->efd);
1582                                 channel_close_fd(&c->efd);
1583                         } else {
1584                                 buffer_append(&c->extended, buf, len);
1585                         }
1586                 }
1587         }
1588         return 1;
1589 }
1590 static int
1591 channel_handle_ctl(Channel *c, fd_set * readset, fd_set * writeset)
1592 {
1593         char buf[16];
1594         int len;
1595
1596         /* Monitor control fd to detect if the slave client exits */
1597         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1598                 len = read(c->ctl_fd, buf, sizeof(buf));
1599                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1600                         return 1;
1601                 if (len <= 0) {
1602                         debug2("channel %d: ctl read<=0", c->self);
1603                         if (c->type != SSH_CHANNEL_OPEN) {
1604                                 debug2("channel %d: not open", c->self);
1605                                 chan_mark_dead(c);
1606                                 return -1;
1607                         } else {
1608                                 chan_read_failed(c);
1609                                 chan_write_failed(c);
1610                         }
1611                         return -1;
1612                 } else
1613                         fatal("%s: unexpected data on ctl fd", __func__);
1614         }
1615         return 1;
1616 }
1617 static int
1618 channel_check_window(Channel *c)
1619 {
1620         if (c->type == SSH_CHANNEL_OPEN &&
1621             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1622             c->local_window < c->local_window_max/2 &&
1623             c->local_consumed > 0) {
1624                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1625                 packet_put_int(c->remote_id);
1626                 packet_put_int(c->local_consumed);
1627                 packet_send();
1628                 debug2("channel %d: window %d sent adjust %d",
1629                     c->self, c->local_window,
1630                     c->local_consumed);
1631                 c->local_window += c->local_consumed;
1632                 c->local_consumed = 0;
1633         }
1634         return 1;
1635 }
1636
1637 static void
1638 channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
1639 {
1640         if (c->delayed)
1641                 return;
1642         channel_handle_rfd(c, readset, writeset);
1643         channel_handle_wfd(c, readset, writeset);
1644         if (!compat20)
1645                 return;
1646         channel_handle_efd(c, readset, writeset);
1647         channel_handle_ctl(c, readset, writeset);
1648         channel_check_window(c);
1649 }
1650
1651 static void
1652 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
1653 {
1654         int len;
1655
1656         /* Send buffered output data to the socket. */
1657         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1658                 len = write(c->sock, buffer_ptr(&c->output),
1659                             buffer_len(&c->output));
1660                 if (len <= 0)
1661                         buffer_clear(&c->output);
1662                 else
1663                         buffer_consume(&c->output, len);
1664         }
1665 }
1666
1667 static void
1668 channel_handler_init_20(void)
1669 {
1670         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1671         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1672         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1673         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1674         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1675         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1676         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1677         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1678
1679         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1680         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1681         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1682         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1683         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1684         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1685         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1686 }
1687
1688 static void
1689 channel_handler_init_13(void)
1690 {
1691         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1692         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1693         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1694         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1695         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1696         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1697         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1698         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1699         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1700
1701         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1702         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1703         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1704         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1705         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1706         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1707         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1708 }
1709
1710 static void
1711 channel_handler_init_15(void)
1712 {
1713         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1714         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1715         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1716         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1717         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1718         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1719         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1720
1721         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1722         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1723         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1724         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1725         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1726         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1727 }
1728
1729 static void
1730 channel_handler_init(void)
1731 {
1732         int i;
1733
1734         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1735                 channel_pre[i] = NULL;
1736                 channel_post[i] = NULL;
1737         }
1738         if (compat20)
1739                 channel_handler_init_20();
1740         else if (compat13)
1741                 channel_handler_init_13();
1742         else
1743                 channel_handler_init_15();
1744 }
1745
1746 /* gc dead channels */
1747 static void
1748 channel_garbage_collect(Channel *c)
1749 {
1750         if (c == NULL)
1751                 return;
1752         if (c->detach_user != NULL) {
1753                 if (!chan_is_dead(c, c->detach_close))
1754                         return;
1755                 debug2("channel %d: gc: notify user", c->self);
1756                 c->detach_user(c->self, NULL);
1757                 /* if we still have a callback */
1758                 if (c->detach_user != NULL)
1759                         return;
1760                 debug2("channel %d: gc: user detached", c->self);
1761         }
1762         if (!chan_is_dead(c, 1))
1763                 return;
1764         debug2("channel %d: garbage collecting", c->self);
1765         channel_free(c);
1766 }
1767
1768 static void
1769 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
1770 {
1771         static int did_init = 0;
1772         u_int i;
1773         Channel *c;
1774
1775         if (!did_init) {
1776                 channel_handler_init();
1777                 did_init = 1;
1778         }
1779         for (i = 0; i < channels_alloc; i++) {
1780                 c = channels[i];
1781                 if (c == NULL)
1782                         continue;
1783                 if (ftab[c->type] != NULL)
1784                         (*ftab[c->type])(c, readset, writeset);
1785                 channel_garbage_collect(c);
1786         }
1787 }
1788
1789 /*
1790  * Allocate/update select bitmasks and add any bits relevant to channels in
1791  * select bitmasks.
1792  */
1793 void
1794 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1795     u_int *nallocp, int rekeying)
1796 {
1797         u_int n, sz;
1798
1799         n = MAX(*maxfdp, channel_max_fd);
1800
1801         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
1802         /* perhaps check sz < nalloc/2 and shrink? */
1803         if (*readsetp == NULL || sz > *nallocp) {
1804                 *readsetp = xrealloc(*readsetp, sz);
1805                 *writesetp = xrealloc(*writesetp, sz);
1806                 *nallocp = sz;
1807         }
1808         *maxfdp = n;
1809         memset(*readsetp, 0, sz);
1810         memset(*writesetp, 0, sz);
1811
1812         if (!rekeying)
1813                 channel_handler(channel_pre, *readsetp, *writesetp);
1814 }
1815
1816 /*
1817  * After select, perform any appropriate operations for channels which have
1818  * events pending.
1819  */
1820 void
1821 channel_after_select(fd_set * readset, fd_set * writeset)
1822 {
1823         channel_handler(channel_post, readset, writeset);
1824 }
1825
1826
1827 /* If there is data to send to the connection, enqueue some of it now. */
1828
1829 void
1830 channel_output_poll(void)
1831 {
1832         Channel *c;
1833         u_int i, len;
1834
1835         for (i = 0; i < channels_alloc; i++) {
1836                 c = channels[i];
1837                 if (c == NULL)
1838                         continue;
1839
1840                 /*
1841                  * We are only interested in channels that can have buffered
1842                  * incoming data.
1843                  */
1844                 if (compat13) {
1845                         if (c->type != SSH_CHANNEL_OPEN &&
1846                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1847                                 continue;
1848                 } else {
1849                         if (c->type != SSH_CHANNEL_OPEN)
1850                                 continue;
1851                 }
1852                 if (compat20 &&
1853                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1854                         /* XXX is this true? */
1855                         debug3("channel %d: will not send data after close", c->self);
1856                         continue;
1857                 }
1858
1859                 /* Get the amount of buffered data for this channel. */
1860                 if ((c->istate == CHAN_INPUT_OPEN ||
1861                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1862                     (len = buffer_len(&c->input)) > 0) {
1863                         if (c->datagram) {
1864                                 if (len > 0) {
1865                                         u_char *data;
1866                                         u_int dlen;
1867
1868                                         data = buffer_get_string(&c->input,
1869                                             &dlen);
1870                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1871                                         packet_put_int(c->remote_id);
1872                                         packet_put_string(data, dlen);
1873                                         packet_send();
1874                                         c->remote_window -= dlen + 4;
1875                                         xfree(data);
1876                                 }
1877                                 continue;
1878                         }
1879                         /*
1880                          * Send some data for the other side over the secure
1881                          * connection.
1882                          */
1883                         if (compat20) {
1884                                 if (len > c->remote_window)
1885                                         len = c->remote_window;
1886                                 if (len > c->remote_maxpacket)
1887                                         len = c->remote_maxpacket;
1888                         } else {
1889                                 if (packet_is_interactive()) {
1890                                         if (len > 1024)
1891                                                 len = 512;
1892                                 } else {
1893                                         /* Keep the packets at reasonable size. */
1894                                         if (len > packet_get_maxsize()/2)
1895                                                 len = packet_get_maxsize()/2;
1896                                 }
1897                         }
1898                         if (len > 0) {
1899                                 packet_start(compat20 ?
1900                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1901                                 packet_put_int(c->remote_id);
1902                                 packet_put_string(buffer_ptr(&c->input), len);
1903                                 packet_send();
1904                                 buffer_consume(&c->input, len);
1905                                 c->remote_window -= len;
1906                         }
1907                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1908                         if (compat13)
1909                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1910                         /*
1911                          * input-buffer is empty and read-socket shutdown:
1912                          * tell peer, that we will not send more data: send IEOF.
1913                          * hack for extended data: delay EOF if EFD still in use.
1914                          */
1915                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1916                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1917                                     c->self, c->efd, buffer_len(&c->extended));
1918                         else
1919                                 chan_ibuf_empty(c);
1920                 }
1921                 /* Send extended data, i.e. stderr */
1922                 if (compat20 &&
1923                     !(c->flags & CHAN_EOF_SENT) &&
1924                     c->remote_window > 0 &&
1925                     (len = buffer_len(&c->extended)) > 0 &&
1926                     c->extended_usage == CHAN_EXTENDED_READ) {
1927                         debug2("channel %d: rwin %u elen %u euse %d",
1928                             c->self, c->remote_window, buffer_len(&c->extended),
1929                             c->extended_usage);
1930                         if (len > c->remote_window)
1931                                 len = c->remote_window;
1932                         if (len > c->remote_maxpacket)
1933                                 len = c->remote_maxpacket;
1934                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1935                         packet_put_int(c->remote_id);
1936                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1937                         packet_put_string(buffer_ptr(&c->extended), len);
1938                         packet_send();
1939                         buffer_consume(&c->extended, len);
1940                         c->remote_window -= len;
1941                         debug2("channel %d: sent ext data %d", c->self, len);
1942                 }
1943         }
1944 }
1945
1946
1947 /* -- protocol input */
1948
1949 void
1950 channel_input_data(int type, u_int32_t seq, void *ctxt)
1951 {
1952         int id;
1953         char *data;
1954         u_int data_len;
1955         Channel *c;
1956
1957         /* Get the channel number and verify it. */
1958         id = packet_get_int();
1959         c = channel_lookup(id);
1960         if (c == NULL)
1961                 packet_disconnect("Received data for nonexistent channel %d.", id);
1962
1963         /* Ignore any data for non-open channels (might happen on close) */
1964         if (c->type != SSH_CHANNEL_OPEN &&
1965             c->type != SSH_CHANNEL_X11_OPEN)
1966                 return;
1967
1968         /* Get the data. */
1969         data = packet_get_string(&data_len);
1970
1971         /*
1972          * Ignore data for protocol > 1.3 if output end is no longer open.
1973          * For protocol 2 the sending side is reducing its window as it sends
1974          * data, so we must 'fake' consumption of the data in order to ensure
1975          * that window updates are sent back.  Otherwise the connection might
1976          * deadlock.
1977          */
1978         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1979                 if (compat20) {
1980                         c->local_window -= data_len;
1981                         c->local_consumed += data_len;
1982                 }
1983                 xfree(data);
1984                 return;
1985         }
1986
1987         if (compat20) {
1988                 if (data_len > c->local_maxpacket) {
1989                         logit("channel %d: rcvd big packet %d, maxpack %d",
1990                             c->self, data_len, c->local_maxpacket);
1991                 }
1992                 if (data_len > c->local_window) {
1993                         logit("channel %d: rcvd too much data %d, win %d",
1994                             c->self, data_len, c->local_window);
1995                         xfree(data);
1996                         return;
1997                 }
1998                 c->local_window -= data_len;
1999         }
2000         packet_check_eom();
2001         if (c->datagram)
2002                 buffer_put_string(&c->output, data, data_len);
2003         else
2004                 buffer_append(&c->output, data, data_len);
2005         xfree(data);
2006 }
2007
2008 void
2009 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2010 {
2011         int id;
2012         char *data;
2013         u_int data_len, tcode;
2014         Channel *c;
2015
2016         /* Get the channel number and verify it. */
2017         id = packet_get_int();
2018         c = channel_lookup(id);
2019
2020         if (c == NULL)
2021                 packet_disconnect("Received extended_data for bad channel %d.", id);
2022         if (c->type != SSH_CHANNEL_OPEN) {
2023                 logit("channel %d: ext data for non open", id);
2024                 return;
2025         }
2026         if (c->flags & CHAN_EOF_RCVD) {
2027                 if (datafellows & SSH_BUG_EXTEOF)
2028                         debug("channel %d: accepting ext data after eof", id);
2029                 else
2030                         packet_disconnect("Received extended_data after EOF "
2031                             "on channel %d.", id);
2032         }
2033         tcode = packet_get_int();
2034         if (c->efd == -1 ||
2035             c->extended_usage != CHAN_EXTENDED_WRITE ||
2036             tcode != SSH2_EXTENDED_DATA_STDERR) {
2037                 logit("channel %d: bad ext data", c->self);
2038                 return;
2039         }
2040         data = packet_get_string(&data_len);
2041         packet_check_eom();
2042         if (data_len > c->local_window) {
2043                 logit("channel %d: rcvd too much extended_data %d, win %d",
2044                     c->self, data_len, c->local_window);
2045                 xfree(data);
2046                 return;
2047         }
2048         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2049         c->local_window -= data_len;
2050         buffer_append(&c->extended, data, data_len);
2051         xfree(data);
2052 }
2053
2054 void
2055 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2056 {
2057         int id;
2058         Channel *c;
2059
2060         id = packet_get_int();
2061         packet_check_eom();
2062         c = channel_lookup(id);
2063         if (c == NULL)
2064                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2065         chan_rcvd_ieof(c);
2066
2067         /* XXX force input close */
2068         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2069                 debug("channel %d: FORCE input drain", c->self);
2070                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2071                 if (buffer_len(&c->input) == 0)
2072                         chan_ibuf_empty(c);
2073         }
2074
2075 }
2076
2077 void
2078 channel_input_close(int type, u_int32_t seq, void *ctxt)
2079 {
2080         int id;
2081         Channel *c;
2082
2083         id = packet_get_int();
2084         packet_check_eom();
2085         c = channel_lookup(id);
2086         if (c == NULL)
2087                 packet_disconnect("Received close for nonexistent channel %d.", id);
2088
2089         /*
2090          * Send a confirmation that we have closed the channel and no more
2091          * data is coming for it.
2092          */
2093         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2094         packet_put_int(c->remote_id);
2095         packet_send();
2096
2097         /*
2098          * If the channel is in closed state, we have sent a close request,
2099          * and the other side will eventually respond with a confirmation.
2100          * Thus, we cannot free the channel here, because then there would be
2101          * no-one to receive the confirmation.  The channel gets freed when
2102          * the confirmation arrives.
2103          */
2104         if (c->type != SSH_CHANNEL_CLOSED) {
2105                 /*
2106                  * Not a closed channel - mark it as draining, which will
2107                  * cause it to be freed later.
2108                  */
2109                 buffer_clear(&c->input);
2110                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2111         }
2112 }
2113
2114 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2115 void
2116 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2117 {
2118         int id = packet_get_int();
2119         Channel *c = channel_lookup(id);
2120
2121         packet_check_eom();
2122         if (c == NULL)
2123                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2124         chan_rcvd_oclose(c);
2125 }
2126
2127 void
2128 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2129 {
2130         int id = packet_get_int();
2131         Channel *c = channel_lookup(id);
2132
2133         packet_check_eom();
2134         if (c == NULL)
2135                 packet_disconnect("Received close confirmation for "
2136                     "out-of-range channel %d.", id);
2137         if (c->type != SSH_CHANNEL_CLOSED)
2138                 packet_disconnect("Received close confirmation for "
2139                     "non-closed channel %d (type %d).", id, c->type);
2140         channel_free(c);
2141 }
2142
2143 void
2144 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2145 {
2146         int id, remote_id;
2147         Channel *c;
2148
2149         id = packet_get_int();
2150         c = channel_lookup(id);
2151
2152         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2153                 packet_disconnect("Received open confirmation for "
2154                     "non-opening channel %d.", id);
2155         remote_id = packet_get_int();
2156         /* Record the remote channel number and mark that the channel is now open. */
2157         c->remote_id = remote_id;
2158         c->type = SSH_CHANNEL_OPEN;
2159
2160         if (compat20) {
2161                 c->remote_window = packet_get_int();
2162                 c->remote_maxpacket = packet_get_int();
2163                 if (c->confirm) {
2164                         debug2("callback start");
2165                         c->confirm(c->self, c->confirm_ctx);
2166                         debug2("callback done");
2167                 }
2168                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2169                     c->remote_window, c->remote_maxpacket);
2170         }
2171         packet_check_eom();
2172 }
2173
2174 static char *
2175 reason2txt(int reason)
2176 {
2177         switch (reason) {
2178         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2179                 return "administratively prohibited";
2180         case SSH2_OPEN_CONNECT_FAILED:
2181                 return "connect failed";
2182         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2183                 return "unknown channel type";
2184         case SSH2_OPEN_RESOURCE_SHORTAGE:
2185                 return "resource shortage";
2186         }
2187         return "unknown reason";
2188 }
2189
2190 void
2191 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2192 {
2193         int id, reason;
2194         char *msg = NULL, *lang = NULL;
2195         Channel *c;
2196
2197         id = packet_get_int();
2198         c = channel_lookup(id);
2199
2200         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2201                 packet_disconnect("Received open failure for "
2202                     "non-opening channel %d.", id);
2203         if (compat20) {
2204                 reason = packet_get_int();
2205                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2206                         msg  = packet_get_string(NULL);
2207                         lang = packet_get_string(NULL);
2208                 }
2209                 logit("channel %d: open failed: %s%s%s", id,
2210                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2211                 if (msg != NULL)
2212                         xfree(msg);
2213                 if (lang != NULL)
2214                         xfree(lang);
2215         }
2216         packet_check_eom();
2217         /* Free the channel.  This will also close the socket. */
2218         channel_free(c);
2219 }
2220
2221 void
2222 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2223 {
2224         Channel *c;
2225         int id;
2226         u_int adjust;
2227
2228         if (!compat20)
2229                 return;
2230
2231         /* Get the channel number and verify it. */
2232         id = packet_get_int();
2233         c = channel_lookup(id);
2234
2235         if (c == NULL) {
2236                 logit("Received window adjust for non-open channel %d.", id);
2237                 return;
2238         }
2239         adjust = packet_get_int();
2240         packet_check_eom();
2241         debug2("channel %d: rcvd adjust %u", id, adjust);
2242         c->remote_window += adjust;
2243 }
2244
2245 void
2246 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2247 {
2248         Channel *c = NULL;
2249         u_short host_port;
2250         char *host, *originator_string;
2251         int remote_id, sock = -1;
2252
2253         remote_id = packet_get_int();
2254         host = packet_get_string(NULL);
2255         host_port = packet_get_int();
2256
2257         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2258                 originator_string = packet_get_string(NULL);
2259         } else {
2260                 originator_string = xstrdup("unknown (remote did not supply name)");
2261         }
2262         packet_check_eom();
2263         sock = channel_connect_to(host, host_port);
2264         if (sock != -1) {
2265                 c = channel_new("connected socket",
2266                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2267                     originator_string, 1);
2268                 c->remote_id = remote_id;
2269         }
2270         xfree(originator_string);
2271         if (c == NULL) {
2272                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2273                 packet_put_int(remote_id);
2274                 packet_send();
2275         }
2276         xfree(host);
2277 }
2278
2279
2280 /* -- tcp forwarding */
2281
2282 void
2283 channel_set_af(int af)
2284 {
2285         IPv4or6 = af;
2286 }
2287
2288 static int
2289 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2290     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2291 {
2292         Channel *c;
2293         int sock, r, success = 0, wildcard = 0, is_client;
2294         struct addrinfo hints, *ai, *aitop;
2295         const char *host, *addr;
2296         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2297
2298         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2299             listen_addr : host_to_connect;
2300         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2301
2302         if (host == NULL) {
2303                 error("No forward host name.");
2304                 return 0;
2305         }
2306         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2307                 error("Forward host name too long.");
2308                 return 0;
2309         }
2310
2311         /*
2312          * Determine whether or not a port forward listens to loopback,
2313          * specified address or wildcard. On the client, a specified bind
2314          * address will always override gateway_ports. On the server, a
2315          * gateway_ports of 1 (``yes'') will override the client's
2316          * specification and force a wildcard bind, whereas a value of 2
2317          * (``clientspecified'') will bind to whatever address the client
2318          * asked for.
2319          *
2320          * Special-case listen_addrs are:
2321          *
2322          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2323          * "" (empty string), "*"  -> wildcard v4/v6
2324          * "localhost"             -> loopback v4/v6
2325          */
2326         addr = NULL;
2327         if (listen_addr == NULL) {
2328                 /* No address specified: default to gateway_ports setting */
2329                 if (gateway_ports)
2330                         wildcard = 1;
2331         } else if (gateway_ports || is_client) {
2332                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2333                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2334                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2335                     (!is_client && gateway_ports == 1))
2336                         wildcard = 1;
2337                 else if (strcmp(listen_addr, "localhost") != 0)
2338                         addr = listen_addr;
2339         }
2340
2341         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2342             type, wildcard, (addr == NULL) ? "NULL" : addr);
2343
2344         /*
2345          * getaddrinfo returns a loopback address if the hostname is
2346          * set to NULL and hints.ai_flags is not AI_PASSIVE
2347          */
2348         memset(&hints, 0, sizeof(hints));
2349         hints.ai_family = IPv4or6;
2350         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2351         hints.ai_socktype = SOCK_STREAM;
2352         snprintf(strport, sizeof strport, "%d", listen_port);
2353         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2354                 if (addr == NULL) {
2355                         /* This really shouldn't happen */
2356                         packet_disconnect("getaddrinfo: fatal error: %s",
2357                             gai_strerror(r));
2358                 } else {
2359                         error("channel_setup_fwd_listener: "
2360                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2361                 }
2362                 return 0;
2363         }
2364
2365         for (ai = aitop; ai; ai = ai->ai_next) {
2366                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2367                         continue;
2368                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2369                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2370                         error("channel_setup_fwd_listener: getnameinfo failed");
2371                         continue;
2372                 }
2373                 /* Create a port to listen for the host. */
2374                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2375                 if (sock < 0) {
2376                         /* this is no error since kernel may not support ipv6 */
2377                         verbose("socket: %.100s", strerror(errno));
2378                         continue;
2379                 }
2380
2381                 channel_set_reuseaddr(sock);
2382
2383                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2384
2385                 /* Bind the socket to the address. */
2386                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2387                         /* address can be in use ipv6 address is already bound */
2388                         if (!ai->ai_next)
2389                                 error("bind: %.100s", strerror(errno));
2390                         else
2391                                 verbose("bind: %.100s", strerror(errno));
2392
2393                         close(sock);
2394                         continue;
2395                 }
2396                 /* Start listening for connections on the socket. */
2397                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2398                         error("listen: %.100s", strerror(errno));
2399                         close(sock);
2400                         continue;
2401                 }
2402                 /* Allocate a channel number for the socket. */
2403                 c = channel_new("port listener", type, sock, sock, -1,
2404                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2405                     0, "port listener", 1);
2406                 strlcpy(c->path, host, sizeof(c->path));
2407                 c->host_port = port_to_connect;
2408                 c->listening_port = listen_port;
2409                 success = 1;
2410         }
2411         if (success == 0)
2412                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2413                     listen_port);
2414         freeaddrinfo(aitop);
2415         return success;
2416 }
2417
2418 int
2419 channel_cancel_rport_listener(const char *host, u_short port)
2420 {
2421         u_int i;
2422         int found = 0;
2423
2424         for (i = 0; i < channels_alloc; i++) {
2425                 Channel *c = channels[i];
2426
2427                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2428                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2429                     c->listening_port == port) {
2430                         debug2("%s: close channel %d", __func__, i);
2431                         channel_free(c);
2432                         found = 1;
2433                 }
2434         }
2435
2436         return (found);
2437 }
2438
2439 /* protocol local port fwd, used by ssh (and sshd in v1) */
2440 int
2441 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2442     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2443 {
2444         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2445             listen_host, listen_port, host_to_connect, port_to_connect,
2446             gateway_ports);
2447 }
2448
2449 /* protocol v2 remote port fwd, used by sshd */
2450 int
2451 channel_setup_remote_fwd_listener(const char *listen_address,
2452     u_short listen_port, int gateway_ports)
2453 {
2454         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2455             listen_address, listen_port, NULL, 0, gateway_ports);
2456 }
2457
2458 /*
2459  * Initiate forwarding of connections to port "port" on remote host through
2460  * the secure channel to host:port from local side.
2461  */
2462
2463 void
2464 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2465     const char *host_to_connect, u_short port_to_connect)
2466 {
2467         int type, success = 0;
2468
2469         /* Record locally that connection to this host/port is permitted. */
2470         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2471                 fatal("channel_request_remote_forwarding: too many forwards");
2472
2473         /* Send the forward request to the remote side. */
2474         if (compat20) {
2475                 const char *address_to_bind;
2476                 if (listen_host == NULL)
2477                         address_to_bind = "localhost";
2478                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2479                         address_to_bind = "";
2480                 else
2481                         address_to_bind = listen_host;
2482
2483                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2484                 packet_put_cstring("tcpip-forward");
2485                 packet_put_char(1);                     /* boolean: want reply */
2486                 packet_put_cstring(address_to_bind);
2487                 packet_put_int(listen_port);
2488                 packet_send();
2489                 packet_write_wait();
2490                 /* Assume that server accepts the request */
2491                 success = 1;
2492         } else {
2493                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2494                 packet_put_int(listen_port);
2495                 packet_put_cstring(host_to_connect);
2496                 packet_put_int(port_to_connect);
2497                 packet_send();
2498                 packet_write_wait();
2499
2500                 /* Wait for response from the remote side. */
2501                 type = packet_read();
2502                 switch (type) {
2503                 case SSH_SMSG_SUCCESS:
2504                         success = 1;
2505                         break;
2506                 case SSH_SMSG_FAILURE:
2507                         logit("Warning: Server denied remote port forwarding.");
2508                         break;
2509                 default:
2510                         /* Unknown packet */
2511                         packet_disconnect("Protocol error for port forward request:"
2512                             "received packet type %d.", type);
2513                 }
2514         }
2515         if (success) {
2516                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2517                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2518                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2519                 num_permitted_opens++;
2520         }
2521 }
2522
2523 /*
2524  * Request cancellation of remote forwarding of connection host:port from
2525  * local side.
2526  */
2527 void
2528 channel_request_rforward_cancel(const char *host, u_short port)
2529 {
2530         int i;
2531
2532         if (!compat20)
2533                 return;
2534
2535         for (i = 0; i < num_permitted_opens; i++) {
2536                 if (permitted_opens[i].host_to_connect != NULL &&
2537                     permitted_opens[i].listen_port == port)
2538                         break;
2539         }
2540         if (i >= num_permitted_opens) {
2541                 debug("%s: requested forward not found", __func__);
2542                 return;
2543         }
2544         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2545         packet_put_cstring("cancel-tcpip-forward");
2546         packet_put_char(0);
2547         packet_put_cstring(host == NULL ? "" : host);
2548         packet_put_int(port);
2549         packet_send();
2550
2551         permitted_opens[i].listen_port = 0;
2552         permitted_opens[i].port_to_connect = 0;
2553         xfree(permitted_opens[i].host_to_connect);
2554         permitted_opens[i].host_to_connect = NULL;
2555 }
2556
2557 /*
2558  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2559  * listening for the port, and sends back a success reply (or disconnect
2560  * message if there was an error).  This never returns if there was an error.
2561  */
2562
2563 void
2564 channel_input_port_forward_request(int is_root, int gateway_ports)
2565 {
2566         u_short port, host_port;
2567         char *hostname;
2568
2569         /* Get arguments from the packet. */
2570         port = packet_get_int();
2571         hostname = packet_get_string(NULL);
2572         host_port = packet_get_int();
2573
2574 #ifndef HAVE_CYGWIN
2575         /*
2576          * Check that an unprivileged user is not trying to forward a
2577          * privileged port.
2578          */
2579         if (port < IPPORT_RESERVED && !is_root)
2580                 packet_disconnect(
2581                     "Requested forwarding of port %d but user is not root.",
2582                     port);
2583         if (host_port == 0)
2584                 packet_disconnect("Dynamic forwarding denied.");
2585 #endif
2586
2587         /* Initiate forwarding */
2588         channel_setup_local_fwd_listener(NULL, port, hostname,
2589             host_port, gateway_ports);
2590
2591         /* Free the argument string. */
2592         xfree(hostname);
2593 }
2594
2595 /*
2596  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2597  * usually called by the server, because the user could connect to any port
2598  * anyway, and the server has no way to know but to trust the client anyway.
2599  */
2600 void
2601 channel_permit_all_opens(void)
2602 {
2603         if (num_permitted_opens == 0)
2604                 all_opens_permitted = 1;
2605 }
2606
2607 void
2608 channel_add_permitted_opens(char *host, int port)
2609 {
2610         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2611                 fatal("channel_request_remote_forwarding: too many forwards");
2612         debug("allow port forwarding to host %s port %d", host, port);
2613
2614         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2615         permitted_opens[num_permitted_opens].port_to_connect = port;
2616         num_permitted_opens++;
2617
2618         all_opens_permitted = 0;
2619 }
2620
2621 void
2622 channel_clear_permitted_opens(void)
2623 {
2624         int i;
2625
2626         for (i = 0; i < num_permitted_opens; i++)
2627                 if (permitted_opens[i].host_to_connect != NULL)
2628                         xfree(permitted_opens[i].host_to_connect);
2629         num_permitted_opens = 0;
2630
2631 }
2632
2633
2634 /* return socket to remote host, port */
2635 static int
2636 connect_to(const char *host, u_short port)
2637 {
2638         struct addrinfo hints, *ai, *aitop;
2639         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2640         int gaierr;
2641         int sock = -1;
2642
2643         memset(&hints, 0, sizeof(hints));
2644         hints.ai_family = IPv4or6;
2645         hints.ai_socktype = SOCK_STREAM;
2646         snprintf(strport, sizeof strport, "%d", port);
2647         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2648                 error("connect_to %.100s: unknown host (%s)", host,
2649                     gai_strerror(gaierr));
2650                 return -1;
2651         }
2652         for (ai = aitop; ai; ai = ai->ai_next) {
2653                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2654                         continue;
2655                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2656                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2657                         error("connect_to: getnameinfo failed");
2658                         continue;
2659                 }
2660                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2661                 if (sock < 0) {
2662                         if (ai->ai_next == NULL)
2663                                 error("socket: %.100s", strerror(errno));
2664                         else
2665                                 verbose("socket: %.100s", strerror(errno));
2666                         continue;
2667                 }
2668                 if (set_nonblock(sock) == -1)
2669                         fatal("%s: set_nonblock(%d)", __func__, sock);
2670                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2671                     errno != EINPROGRESS) {
2672                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2673                             strerror(errno));
2674                         close(sock);
2675                         continue;       /* fail -- try next */
2676                 }
2677                 break; /* success */
2678
2679         }
2680         freeaddrinfo(aitop);
2681         if (!ai) {
2682                 error("connect_to %.100s port %d: failed.", host, port);
2683                 return -1;
2684         }
2685         /* success */
2686         set_nodelay(sock);
2687         return sock;
2688 }
2689
2690 int
2691 channel_connect_by_listen_address(u_short listen_port)
2692 {
2693         int i;
2694
2695         for (i = 0; i < num_permitted_opens; i++)
2696                 if (permitted_opens[i].host_to_connect != NULL &&
2697                     permitted_opens[i].listen_port == listen_port)
2698                         return connect_to(
2699                             permitted_opens[i].host_to_connect,
2700                             permitted_opens[i].port_to_connect);
2701         error("WARNING: Server requests forwarding for unknown listen_port %d",
2702             listen_port);
2703         return -1;
2704 }
2705
2706 /* Check if connecting to that port is permitted and connect. */
2707 int
2708 channel_connect_to(const char *host, u_short port)
2709 {
2710         int i, permit;
2711
2712         permit = all_opens_permitted;
2713         if (!permit) {
2714                 for (i = 0; i < num_permitted_opens; i++)
2715                         if (permitted_opens[i].host_to_connect != NULL &&
2716                             permitted_opens[i].port_to_connect == port &&
2717                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2718                                 permit = 1;
2719
2720         }
2721         if (!permit) {
2722                 logit("Received request to connect to host %.100s port %d, "
2723                     "but the request was denied.", host, port);
2724                 return -1;
2725         }
2726         return connect_to(host, port);
2727 }
2728
2729 void
2730 channel_send_window_changes(void)
2731 {
2732         u_int i;
2733         struct winsize ws;
2734
2735         for (i = 0; i < channels_alloc; i++) {
2736                 if (channels[i] == NULL || !channels[i]->client_tty ||
2737                     channels[i]->type != SSH_CHANNEL_OPEN)
2738                         continue;
2739                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2740                         continue;
2741                 channel_request_start(i, "window-change", 0);
2742                 packet_put_int(ws.ws_col);
2743                 packet_put_int(ws.ws_row);
2744                 packet_put_int(ws.ws_xpixel);
2745                 packet_put_int(ws.ws_ypixel);
2746                 packet_send();
2747         }
2748 }
2749
2750 /* -- X11 forwarding */
2751
2752 /*
2753  * Creates an internet domain socket for listening for X11 connections.
2754  * Returns 0 and a suitable display number for the DISPLAY variable
2755  * stored in display_numberp , or -1 if an error occurs.
2756  */
2757 int
2758 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2759     int single_connection, u_int *display_numberp, int **chanids)
2760 {
2761         Channel *nc = NULL;
2762         int display_number, sock;
2763         u_short port;
2764         struct addrinfo hints, *ai, *aitop;
2765         char strport[NI_MAXSERV];
2766         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2767
2768         if (chanids == NULL)
2769                 return -1;
2770
2771         for (display_number = x11_display_offset;
2772             display_number < MAX_DISPLAYS;
2773             display_number++) {
2774                 port = 6000 + display_number;
2775                 memset(&hints, 0, sizeof(hints));
2776                 hints.ai_family = IPv4or6;
2777                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2778                 hints.ai_socktype = SOCK_STREAM;
2779                 snprintf(strport, sizeof strport, "%d", port);
2780                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2781                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2782                         return -1;
2783                 }
2784                 for (ai = aitop; ai; ai = ai->ai_next) {
2785                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2786                                 continue;
2787                         sock = socket(ai->ai_family, ai->ai_socktype,
2788                             ai->ai_protocol);
2789                         if (sock < 0) {
2790                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2791                                         error("socket: %.100s", strerror(errno));
2792                                         freeaddrinfo(aitop);
2793                                         return -1;
2794                                 } else {
2795                                         debug("x11_create_display_inet: Socket family %d not supported",
2796                                                  ai->ai_family);
2797                                         continue;
2798                                 }
2799                         }
2800 #ifdef IPV6_V6ONLY
2801                         if (ai->ai_family == AF_INET6) {
2802                                 int on = 1;
2803                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2804                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2805                         }
2806 #endif
2807                         channel_set_reuseaddr(sock);
2808                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2809                                 debug2("bind port %d: %.100s", port, strerror(errno));
2810                                 close(sock);
2811
2812                                 if (ai->ai_next)
2813                                         continue;
2814
2815                                 for (n = 0; n < num_socks; n++) {
2816                                         close(socks[n]);
2817                                 }
2818                                 num_socks = 0;
2819                                 break;
2820                         }
2821                         socks[num_socks++] = sock;
2822 #ifndef DONT_TRY_OTHER_AF
2823                         if (num_socks == NUM_SOCKS)
2824                                 break;
2825 #else
2826                         if (x11_use_localhost) {
2827                                 if (num_socks == NUM_SOCKS)
2828                                         break;
2829                         } else {
2830                                 break;
2831                         }
2832 #endif
2833                 }
2834                 freeaddrinfo(aitop);
2835                 if (num_socks > 0)
2836                         break;
2837         }
2838         if (display_number >= MAX_DISPLAYS) {
2839                 error("Failed to allocate internet-domain X11 display socket.");
2840                 return -1;
2841         }
2842         /* Start listening for connections on the socket. */
2843         for (n = 0; n < num_socks; n++) {
2844                 sock = socks[n];
2845                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2846                         error("listen: %.100s", strerror(errno));
2847                         close(sock);
2848                         return -1;
2849                 }
2850         }
2851
2852         /* Allocate a channel for each socket. */
2853         *chanids = xmalloc(sizeof(**chanids) * (num_socks + 1));
2854         for (n = 0; n < num_socks; n++) {
2855                 sock = socks[n];
2856                 nc = channel_new("x11 listener",
2857                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2858                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2859                     0, "X11 inet listener", 1);
2860                 nc->single_connection = single_connection;
2861                 (*chanids)[n] = nc->self;
2862         }
2863         (*chanids)[n] = -1;
2864
2865         /* Return the display number for the DISPLAY environment variable. */
2866         *display_numberp = display_number;
2867         return (0);
2868 }
2869
2870 static int
2871 connect_local_xsocket(u_int dnr)
2872 {
2873         int sock;
2874         struct sockaddr_un addr;
2875
2876         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2877         if (sock < 0)
2878                 error("socket: %.100s", strerror(errno));
2879         memset(&addr, 0, sizeof(addr));
2880         addr.sun_family = AF_UNIX;
2881         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2882         if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2883                 return sock;
2884         close(sock);
2885         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2886         return -1;
2887 }
2888
2889 int
2890 x11_connect_display(void)
2891 {
2892         int display_number, sock = 0;
2893         const char *display;
2894         char buf[1024], *cp;
2895         struct addrinfo hints, *ai, *aitop;
2896         char strport[NI_MAXSERV];
2897         int gaierr;
2898
2899         /* Try to open a socket for the local X server. */
2900         display = getenv("DISPLAY");
2901         if (!display) {
2902                 error("DISPLAY not set.");
2903                 return -1;
2904         }
2905         /*
2906          * Now we decode the value of the DISPLAY variable and make a
2907          * connection to the real X server.
2908          */
2909
2910         /*
2911          * Check if it is a unix domain socket.  Unix domain displays are in
2912          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2913          */
2914         if (strncmp(display, "unix:", 5) == 0 ||
2915             display[0] == ':') {
2916                 /* Connect to the unix domain socket. */
2917                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2918                         error("Could not parse display number from DISPLAY: %.100s",
2919                             display);
2920                         return -1;
2921                 }
2922                 /* Create a socket. */
2923                 sock = connect_local_xsocket(display_number);
2924                 if (sock < 0)
2925                         return -1;
2926
2927                 /* OK, we now have a connection to the display. */
2928                 return sock;
2929         }
2930         /*
2931          * Connect to an inet socket.  The DISPLAY value is supposedly
2932          * hostname:d[.s], where hostname may also be numeric IP address.
2933          */
2934         strlcpy(buf, display, sizeof(buf));
2935         cp = strchr(buf, ':');
2936         if (!cp) {
2937                 error("Could not find ':' in DISPLAY: %.100s", display);
2938                 return -1;
2939         }
2940         *cp = 0;
2941         /* buf now contains the host name.  But first we parse the display number. */
2942         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2943                 error("Could not parse display number from DISPLAY: %.100s",
2944                     display);
2945                 return -1;
2946         }
2947
2948         /* Look up the host address */
2949         memset(&hints, 0, sizeof(hints));
2950         hints.ai_family = IPv4or6;
2951         hints.ai_socktype = SOCK_STREAM;
2952         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2953         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2954                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2955                 return -1;
2956         }
2957         for (ai = aitop; ai; ai = ai->ai_next) {
2958                 /* Create a socket. */
2959                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2960                 if (sock < 0) {
2961                         debug2("socket: %.100s", strerror(errno));
2962                         continue;
2963                 }
2964                 /* Connect it to the display. */
2965                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2966                         debug2("connect %.100s port %d: %.100s", buf,
2967                             6000 + display_number, strerror(errno));
2968                         close(sock);
2969                         continue;
2970                 }
2971                 /* Success */
2972                 break;
2973         }
2974         freeaddrinfo(aitop);
2975         if (!ai) {
2976                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2977                     strerror(errno));
2978                 return -1;
2979         }
2980         set_nodelay(sock);
2981         return sock;
2982 }
2983
2984 /*
2985  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2986  * the remote channel number.  We should do whatever we want, and respond
2987  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2988  */
2989
2990 void
2991 x11_input_open(int type, u_int32_t seq, void *ctxt)
2992 {
2993         Channel *c = NULL;
2994         int remote_id, sock = 0;
2995         char *remote_host;
2996
2997         debug("Received X11 open request.");
2998
2999         remote_id = packet_get_int();
3000
3001         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3002                 remote_host = packet_get_string(NULL);
3003         } else {
3004                 remote_host = xstrdup("unknown (remote did not supply name)");
3005         }
3006         packet_check_eom();
3007
3008         /* Obtain a connection to the real X display. */
3009         sock = x11_connect_display();
3010         if (sock != -1) {
3011                 /* Allocate a channel for this connection. */
3012                 c = channel_new("connected x11 socket",
3013                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3014                     remote_host, 1);
3015                 c->remote_id = remote_id;
3016                 c->force_drain = 1;
3017         }
3018         xfree(remote_host);
3019         if (c == NULL) {
3020                 /* Send refusal to the remote host. */
3021                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3022                 packet_put_int(remote_id);
3023         } else {
3024                 /* Send a confirmation to the remote host. */
3025                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3026                 packet_put_int(remote_id);
3027                 packet_put_int(c->self);
3028         }
3029         packet_send();
3030 }
3031
3032 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3033 void
3034 deny_input_open(int type, u_int32_t seq, void *ctxt)
3035 {
3036         int rchan = packet_get_int();
3037
3038         switch (type) {
3039         case SSH_SMSG_AGENT_OPEN:
3040                 error("Warning: ssh server tried agent forwarding.");
3041                 break;
3042         case SSH_SMSG_X11_OPEN:
3043                 error("Warning: ssh server tried X11 forwarding.");
3044                 break;
3045         default:
3046                 error("deny_input_open: type %d", type);
3047                 break;
3048         }
3049         error("Warning: this is probably a break-in attempt by a malicious server.");
3050         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3051         packet_put_int(rchan);
3052         packet_send();
3053 }
3054
3055 /*
3056  * Requests forwarding of X11 connections, generates fake authentication
3057  * data, and enables authentication spoofing.
3058  * This should be called in the client only.
3059  */
3060 void
3061 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3062     const char *proto, const char *data)
3063 {
3064         u_int data_len = (u_int) strlen(data) / 2;
3065         u_int i, value;
3066         char *new_data;
3067         int screen_number;
3068         const char *cp;
3069         u_int32_t rnd = 0;
3070
3071         if (x11_saved_display == NULL)
3072                 x11_saved_display = xstrdup(disp);
3073         else if (strcmp(disp, x11_saved_display) != 0) {
3074                 error("x11_request_forwarding_with_spoofing: different "
3075                     "$DISPLAY already forwarded");
3076                 return;
3077         }
3078
3079         cp = disp;
3080         if (disp)
3081                 cp = strchr(disp, ':');
3082         if (cp)
3083                 cp = strchr(cp, '.');
3084         if (cp)
3085                 screen_number = atoi(cp + 1);
3086         else
3087                 screen_number = 0;
3088
3089         if (x11_saved_proto == NULL) {
3090                 /* Save protocol name. */
3091                 x11_saved_proto = xstrdup(proto);
3092                 /*
3093                  * Extract real authentication data and generate fake data
3094                  * of the same length.
3095                  */
3096                 x11_saved_data = xmalloc(data_len);
3097                 x11_fake_data = xmalloc(data_len);
3098                 for (i = 0; i < data_len; i++) {
3099                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3100                                 fatal("x11_request_forwarding: bad "
3101                                     "authentication data: %.100s", data);
3102                         if (i % 4 == 0)
3103                                 rnd = arc4random();
3104                         x11_saved_data[i] = value;
3105                         x11_fake_data[i] = rnd & 0xff;
3106                         rnd >>= 8;
3107                 }
3108                 x11_saved_data_len = data_len;
3109                 x11_fake_data_len = data_len;
3110         }
3111
3112         /* Convert the fake data into hex. */
3113         new_data = tohex(x11_fake_data, data_len);
3114
3115         /* Send the request packet. */
3116         if (compat20) {
3117                 channel_request_start(client_session_id, "x11-req", 0);
3118                 packet_put_char(0);     /* XXX bool single connection */
3119         } else {
3120                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3121         }
3122         packet_put_cstring(proto);
3123         packet_put_cstring(new_data);
3124         packet_put_int(screen_number);
3125         packet_send();
3126         packet_write_wait();
3127         xfree(new_data);
3128 }
3129
3130
3131 /* -- agent forwarding */
3132
3133 /* Sends a message to the server to request authentication fd forwarding. */
3134
3135 void
3136 auth_request_forwarding(void)
3137 {
3138         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3139         packet_send();
3140         packet_write_wait();
3141 }