channels.c

   1 /* $OpenBSD: channels.c,v 1.261 2006/07/25 02:59:21 stevesk Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/ioctl.h>
  45 #include <sys/types.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <netdb.h>
  57 #include <string.h>
  58 #include <termios.h>
  59 #include <unistd.h>
  60
  61 #include "ssh.h"
  62 #include "ssh1.h"
  63 #include "ssh2.h"
  64 #include "packet.h"
  65 #include "xmalloc.h"
  66 #include "log.h"
  67 #include "misc.h"
  68 #include "channels.h"
  69 #include "compat.h"
  70 #include "canohost.h"
  71 #include "key.h"
  72 #include "authfd.h"
  73 #include "pathnames.h"
  74 #include "bufaux.h"
  75
  76 /* -- channel core */
  77
  78 /*
  79  * Pointer to an array containing all allocated channels.  The array is
  80  * dynamically extended as needed.
  81  */
  82 static Channel **channels = NULL;
  83
  84 /*
  85  * Size of the channel array.  All slots of the array must always be
  86  * initialized (at least the type field); unused slots set to NULL
  87  */
  88 static u_int channels_alloc = 0;
  89
  90 /*
  91  * Maximum file descriptor value used in any of the channels.  This is
  92  * updated in channel_new.
  93  */
  94 static int channel_max_fd = 0;
  95
  96
  97 /* -- tcp forwarding */
  98
  99 /*
 100  * Data structure for storing which hosts are permitted for forward requests.
 101  * The local sides of any remote forwards are stored in this array to prevent
 102  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 103  * network (which might be behind a firewall).
 104  */
 105 typedef struct {
 106         char *host_to_connect;          /* Connect to 'host'. */
 107         u_short port_to_connect;        /* Connect to 'port'. */
 108         u_short listen_port;            /* Remote side should listen port number. */
 109 } ForwardPermission;
 110
 111 /* List of all permitted host/port pairs to connect by the user. */
 112 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 113
 114 /* List of all permitted host/port pairs to connect by the admin. */
 115 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 116
 117 /* Number of permitted host/port pairs in the array permitted by the user. */
 118 static int num_permitted_opens = 0;
 119
 120 /* Number of permitted host/port pair in the array permitted by the admin. */
 121 static int num_adm_permitted_opens = 0;
 122
 123 /*
 124  * If this is true, all opens are permitted.  This is the case on the server
 125  * on which we have to trust the client anyway, and the user could do
 126  * anything after logging in anyway.
 127  */
 128 static int all_opens_permitted = 0;
 129
 130
 131 /* -- X11 forwarding */
 132
 133 /* Maximum number of fake X11 displays to try. */
 134 #define MAX_DISPLAYS  1000
 135
 136 /* Saved X11 local (client) display. */
 137 static char *x11_saved_display = NULL;
 138
 139 /* Saved X11 authentication protocol name. */
 140 static char *x11_saved_proto = NULL;
 141
 142 /* Saved X11 authentication data.  This is the real data. */
 143 static char *x11_saved_data = NULL;
 144 static u_int x11_saved_data_len = 0;
 145
 146 /*
 147  * Fake X11 authentication data.  This is what the server will be sending us;
 148  * we should replace any occurrences of this by the real data.
 149  */
 150 static u_char *x11_fake_data = NULL;
 151 static u_int x11_fake_data_len;
 152
 153
 154 /* -- agent forwarding */
 155
 156 #define NUM_SOCKS       10
 157
 158 /* AF_UNSPEC or AF_INET or AF_INET6 */
 159 static int IPv4or6 = AF_UNSPEC;
 160
 161 /* helper */
 162 static void port_open_helper(Channel *c, char *rtype);
 163
 164 /* -- channel core */
 165
 166 Channel *
 167 channel_by_id(int id)
 168 {
 169         Channel *c;
 170
 171         if (id < 0 || (u_int)id >= channels_alloc) {
 172                 logit("channel_by_id: %d: bad id", id);
 173                 return NULL;
 174         }
 175         c = channels[id];
 176         if (c == NULL) {
 177                 logit("channel_by_id: %d: bad id: channel free", id);
 178                 return NULL;
 179         }
 180         return c;
 181 }
 182
 183 /*
 184  * Returns the channel if it is allowed to receive protocol messages.
 185  * Private channels, like listening sockets, may not receive messages.
 186  */
 187 Channel *
 188 channel_lookup(int id)
 189 {
 190         Channel *c;
 191
 192         if ((c = channel_by_id(id)) == NULL)
 193                 return (NULL);
 194
 195         switch (c->type) {
 196         case SSH_CHANNEL_X11_OPEN:
 197         case SSH_CHANNEL_LARVAL:
 198         case SSH_CHANNEL_CONNECTING:
 199         case SSH_CHANNEL_DYNAMIC:
 200         case SSH_CHANNEL_OPENING:
 201         case SSH_CHANNEL_OPEN:
 202         case SSH_CHANNEL_INPUT_DRAINING:
 203         case SSH_CHANNEL_OUTPUT_DRAINING:
 204                 return (c);
 205         }
 206         logit("Non-public channel %d, type %d.", id, c->type);
 207         return (NULL);
 208 }
 209
 210 /*
 211  * Register filedescriptors for a channel, used when allocating a channel or
 212  * when the channel consumer/producer is ready, e.g. shell exec'd
 213  */
 214 static void
 215 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 216     int extusage, int nonblock)
 217 {
 218         /* Update the maximum file descriptor value. */
 219         channel_max_fd = MAX(channel_max_fd, rfd);
 220         channel_max_fd = MAX(channel_max_fd, wfd);
 221         channel_max_fd = MAX(channel_max_fd, efd);
 222
 223         /* XXX set close-on-exec -markus */
 224
 225         c->rfd = rfd;
 226         c->wfd = wfd;
 227         c->sock = (rfd == wfd) ? rfd : -1;
 228         c->ctl_fd = -1; /* XXX: set elsewhere */
 229         c->efd = efd;
 230         c->extended_usage = extusage;
 231
 232         /* XXX ugly hack: nonblock is only set by the server */
 233         if (nonblock && isatty(c->rfd)) {
 234                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 235                 c->isatty = 1;
 236                 if (!isatty(c->wfd)) {
 237                         error("channel %d: wfd %d is not a tty?",
 238                             c->self, c->wfd);
 239                 }
 240         } else {
 241                 c->isatty = 0;
 242         }
 243         c->wfd_isatty = isatty(c->wfd);
 244
 245         /* enable nonblocking mode */
 246         if (nonblock) {
 247                 if (rfd != -1)
 248                         set_nonblock(rfd);
 249                 if (wfd != -1)
 250                         set_nonblock(wfd);
 251                 if (efd != -1)
 252                         set_nonblock(efd);
 253         }
 254 }
 255
 256 /*
 257  * Allocate a new channel object and set its type and socket. This will cause
 258  * remote_name to be freed.
 259  */
 260 Channel *
 261 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 262     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 263 {
 264         int found;
 265         u_int i;
 266         Channel *c;
 267
 268         /* Do initial allocation if this is the first call. */
 269         if (channels_alloc == 0) {
 270                 channels_alloc = 10;
 271                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 272                 for (i = 0; i < channels_alloc; i++)
 273                         channels[i] = NULL;
 274         }
 275         /* Try to find a free slot where to put the new channel. */
 276         for (found = -1, i = 0; i < channels_alloc; i++)
 277                 if (channels[i] == NULL) {
 278                         /* Found a free slot. */
 279                         found = (int)i;
 280                         break;
 281                 }
 282         if (found < 0) {
 283                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 284                 found = channels_alloc;
 285                 if (channels_alloc > 10000)
 286                         fatal("channel_new: internal error: channels_alloc %d "
 287                             "too big.", channels_alloc);
 288                 channels = xrealloc(channels, channels_alloc + 10,
 289                     sizeof(Channel *));
 290                 channels_alloc += 10;
 291                 debug2("channel: expanding %d", channels_alloc);
 292                 for (i = found; i < channels_alloc; i++)
 293                         channels[i] = NULL;
 294         }
 295         /* Initialize and return new channel. */
 296         c = channels[found] = xcalloc(1, sizeof(Channel));
 297         buffer_init(&c->input);
 298         buffer_init(&c->output);
 299         buffer_init(&c->extended);
 300         c->ostate = CHAN_OUTPUT_OPEN;
 301         c->istate = CHAN_INPUT_OPEN;
 302         c->flags = 0;
 303         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 304         c->self = found;
 305         c->type = type;
 306         c->ctype = ctype;
 307         c->local_window = window;
 308         c->local_window_max = window;
 309         c->local_consumed = 0;
 310         c->local_maxpacket = maxpack;
 311         c->remote_id = -1;
 312         c->remote_name = xstrdup(remote_name);
 313         c->remote_window = 0;
 314         c->remote_maxpacket = 0;
 315         c->force_drain = 0;
 316         c->single_connection = 0;
 317         c->detach_user = NULL;
 318         c->detach_close = 0;
 319         c->confirm = NULL;
 320         c->confirm_ctx = NULL;
 321         c->input_filter = NULL;
 322         c->output_filter = NULL;
 323         debug("channel %d: new [%s]", found, remote_name);
 324         return c;
 325 }
 326
 327 static int
 328 channel_find_maxfd(void)
 329 {
 330         u_int i;
 331         int max = 0;
 332         Channel *c;
 333
 334         for (i = 0; i < channels_alloc; i++) {
 335                 c = channels[i];
 336                 if (c != NULL) {
 337                         max = MAX(max, c->rfd);
 338                         max = MAX(max, c->wfd);
 339                         max = MAX(max, c->efd);
 340                 }
 341         }
 342         return max;
 343 }
 344
 345 int
 346 channel_close_fd(int *fdp)
 347 {
 348         int ret = 0, fd = *fdp;
 349
 350         if (fd != -1) {
 351                 ret = close(fd);
 352                 *fdp = -1;
 353                 if (fd == channel_max_fd)
 354                         channel_max_fd = channel_find_maxfd();
 355         }
 356         return ret;
 357 }
 358
 359 /* Close all channel fd/socket. */
 360 static void
 361 channel_close_fds(Channel *c)
 362 {
 363         debug3("channel %d: close_fds r %d w %d e %d c %d",
 364             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 365
 366         channel_close_fd(&c->sock);
 367         channel_close_fd(&c->ctl_fd);
 368         channel_close_fd(&c->rfd);
 369         channel_close_fd(&c->wfd);
 370         channel_close_fd(&c->efd);
 371 }
 372
 373 /* Free the channel and close its fd/socket. */
 374 void
 375 channel_free(Channel *c)
 376 {
 377         char *s;
 378         u_int i, n;
 379
 380         for (n = 0, i = 0; i < channels_alloc; i++)
 381                 if (channels[i])
 382                         n++;
 383         debug("channel %d: free: %s, nchannels %u", c->self,
 384             c->remote_name ? c->remote_name : "???", n);
 385
 386         s = channel_open_message();
 387         debug3("channel %d: status: %s", c->self, s);
 388         xfree(s);
 389
 390         if (c->sock != -1)
 391                 shutdown(c->sock, SHUT_RDWR);
 392         if (c->ctl_fd != -1)
 393                 shutdown(c->ctl_fd, SHUT_RDWR);
 394         channel_close_fds(c);
 395         buffer_free(&c->input);
 396         buffer_free(&c->output);
 397         buffer_free(&c->extended);
 398         if (c->remote_name) {
 399                 xfree(c->remote_name);
 400                 c->remote_name = NULL;
 401         }
 402         channels[c->self] = NULL;
 403         xfree(c);
 404 }
 405
 406 void
 407 channel_free_all(void)
 408 {
 409         u_int i;
 410
 411         for (i = 0; i < channels_alloc; i++)
 412                 if (channels[i] != NULL)
 413                         channel_free(channels[i]);
 414 }
 415
 416 /*
 417  * Closes the sockets/fds of all channels.  This is used to close extra file
 418  * descriptors after a fork.
 419  */
 420 void
 421 channel_close_all(void)
 422 {
 423         u_int i;
 424
 425         for (i = 0; i < channels_alloc; i++)
 426                 if (channels[i] != NULL)
 427                         channel_close_fds(channels[i]);
 428 }
 429
 430 /*
 431  * Stop listening to channels.
 432  */
 433 void
 434 channel_stop_listening(void)
 435 {
 436         u_int i;
 437         Channel *c;
 438
 439         for (i = 0; i < channels_alloc; i++) {
 440                 c = channels[i];
 441                 if (c != NULL) {
 442                         switch (c->type) {
 443                         case SSH_CHANNEL_AUTH_SOCKET:
 444                         case SSH_CHANNEL_PORT_LISTENER:
 445                         case SSH_CHANNEL_RPORT_LISTENER:
 446                         case SSH_CHANNEL_X11_LISTENER:
 447                                 channel_close_fd(&c->sock);
 448                                 channel_free(c);
 449                                 break;
 450                         }
 451                 }
 452         }
 453 }
 454
 455 /*
 456  * Returns true if no channel has too much buffered data, and false if one or
 457  * more channel is overfull.
 458  */
 459 int
 460 channel_not_very_much_buffered_data(void)
 461 {
 462         u_int i;
 463         Channel *c;
 464
 465         for (i = 0; i < channels_alloc; i++) {
 466                 c = channels[i];
 467                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 468 #if 0
 469                         if (!compat20 &&
 470                             buffer_len(&c->input) > packet_get_maxsize()) {
 471                                 debug2("channel %d: big input buffer %d",
 472                                     c->self, buffer_len(&c->input));
 473                                 return 0;
 474                         }
 475 #endif
 476                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 477                                 debug2("channel %d: big output buffer %u > %u",
 478                                     c->self, buffer_len(&c->output),
 479                                     packet_get_maxsize());
 480                                 return 0;
 481                         }
 482                 }
 483         }
 484         return 1;
 485 }
 486
 487 /* Returns true if any channel is still open. */
 488 int
 489 channel_still_open(void)
 490 {
 491         u_int i;
 492         Channel *c;
 493
 494         for (i = 0; i < channels_alloc; i++) {
 495                 c = channels[i];
 496                 if (c == NULL)
 497                         continue;
 498                 switch (c->type) {
 499                 case SSH_CHANNEL_X11_LISTENER:
 500                 case SSH_CHANNEL_PORT_LISTENER:
 501                 case SSH_CHANNEL_RPORT_LISTENER:
 502                 case SSH_CHANNEL_CLOSED:
 503                 case SSH_CHANNEL_AUTH_SOCKET:
 504                 case SSH_CHANNEL_DYNAMIC:
 505                 case SSH_CHANNEL_CONNECTING:
 506                 case SSH_CHANNEL_ZOMBIE:
 507                         continue;
 508                 case SSH_CHANNEL_LARVAL:
 509                         if (!compat20)
 510                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 511                         continue;
 512                 case SSH_CHANNEL_OPENING:
 513                 case SSH_CHANNEL_OPEN:
 514                 case SSH_CHANNEL_X11_OPEN:
 515                         return 1;
 516                 case SSH_CHANNEL_INPUT_DRAINING:
 517                 case SSH_CHANNEL_OUTPUT_DRAINING:
 518                         if (!compat13)
 519                                 fatal("cannot happen: OUT_DRAIN");
 520                         return 1;
 521                 default:
 522                         fatal("channel_still_open: bad channel type %d", c->type);
 523                         /* NOTREACHED */
 524                 }
 525         }
 526         return 0;
 527 }
 528
 529 /* Returns the id of an open channel suitable for keepaliving */
 530 int
 531 channel_find_open(void)
 532 {
 533         u_int i;
 534         Channel *c;
 535
 536         for (i = 0; i < channels_alloc; i++) {
 537                 c = channels[i];
 538                 if (c == NULL || c->remote_id < 0)
 539                         continue;
 540                 switch (c->type) {
 541                 case SSH_CHANNEL_CLOSED:
 542                 case SSH_CHANNEL_DYNAMIC:
 543                 case SSH_CHANNEL_X11_LISTENER:
 544                 case SSH_CHANNEL_PORT_LISTENER:
 545                 case SSH_CHANNEL_RPORT_LISTENER:
 546                 case SSH_CHANNEL_OPENING:
 547                 case SSH_CHANNEL_CONNECTING:
 548                 case SSH_CHANNEL_ZOMBIE:
 549                         continue;
 550                 case SSH_CHANNEL_LARVAL:
 551                 case SSH_CHANNEL_AUTH_SOCKET:
 552                 case SSH_CHANNEL_OPEN:
 553                 case SSH_CHANNEL_X11_OPEN:
 554                         return i;
 555                 case SSH_CHANNEL_INPUT_DRAINING:
 556                 case SSH_CHANNEL_OUTPUT_DRAINING:
 557                         if (!compat13)
 558                                 fatal("cannot happen: OUT_DRAIN");
 559                         return i;
 560                 default:
 561                         fatal("channel_find_open: bad channel type %d", c->type);
 562                         /* NOTREACHED */
 563                 }
 564         }
 565         return -1;
 566 }
 567
 568
 569 /*
 570  * Returns a message describing the currently open forwarded connections,
 571  * suitable for sending to the client.  The message contains crlf pairs for
 572  * newlines.
 573  */
 574 char *
 575 channel_open_message(void)
 576 {
 577         Buffer buffer;
 578         Channel *c;
 579         char buf[1024], *cp;
 580         u_int i;
 581
 582         buffer_init(&buffer);
 583         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 584         buffer_append(&buffer, buf, strlen(buf));
 585         for (i = 0; i < channels_alloc; i++) {
 586                 c = channels[i];
 587                 if (c == NULL)
 588                         continue;
 589                 switch (c->type) {
 590                 case SSH_CHANNEL_X11_LISTENER:
 591                 case SSH_CHANNEL_PORT_LISTENER:
 592                 case SSH_CHANNEL_RPORT_LISTENER:
 593                 case SSH_CHANNEL_CLOSED:
 594                 case SSH_CHANNEL_AUTH_SOCKET:
 595                 case SSH_CHANNEL_ZOMBIE:
 596                         continue;
 597                 case SSH_CHANNEL_LARVAL:
 598                 case SSH_CHANNEL_OPENING:
 599                 case SSH_CHANNEL_CONNECTING:
 600                 case SSH_CHANNEL_DYNAMIC:
 601                 case SSH_CHANNEL_OPEN:
 602                 case SSH_CHANNEL_X11_OPEN:
 603                 case SSH_CHANNEL_INPUT_DRAINING:
 604                 case SSH_CHANNEL_OUTPUT_DRAINING:
 605                         snprintf(buf, sizeof buf,
 606                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 607                             c->self, c->remote_name,
 608                             c->type, c->remote_id,
 609                             c->istate, buffer_len(&c->input),
 610                             c->ostate, buffer_len(&c->output),
 611                             c->rfd, c->wfd, c->ctl_fd);
 612                         buffer_append(&buffer, buf, strlen(buf));
 613                         continue;
 614                 default:
 615                         fatal("channel_open_message: bad channel type %d", c->type);
 616                         /* NOTREACHED */
 617                 }
 618         }
 619         buffer_append(&buffer, "\0", 1);
 620         cp = xstrdup(buffer_ptr(&buffer));
 621         buffer_free(&buffer);
 622         return cp;
 623 }
 624
 625 void
 626 channel_send_open(int id)
 627 {
 628         Channel *c = channel_lookup(id);
 629
 630         if (c == NULL) {
 631                 logit("channel_send_open: %d: bad id", id);
 632                 return;
 633         }
 634         debug2("channel %d: send open", id);
 635         packet_start(SSH2_MSG_CHANNEL_OPEN);
 636         packet_put_cstring(c->ctype);
 637         packet_put_int(c->self);
 638         packet_put_int(c->local_window);
 639         packet_put_int(c->local_maxpacket);
 640         packet_send();
 641 }
 642
 643 void
 644 channel_request_start(int id, char *service, int wantconfirm)
 645 {
 646         Channel *c = channel_lookup(id);
 647
 648         if (c == NULL) {
 649                 logit("channel_request_start: %d: unknown channel id", id);
 650                 return;
 651         }
 652         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 653         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 654         packet_put_int(c->remote_id);
 655         packet_put_cstring(service);
 656         packet_put_char(wantconfirm);
 657 }
 658
 659 void
 660 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 661 {
 662         Channel *c = channel_lookup(id);
 663
 664         if (c == NULL) {
 665                 logit("channel_register_comfirm: %d: bad id", id);
 666                 return;
 667         }
 668         c->confirm = fn;
 669         c->confirm_ctx = ctx;
 670 }
 671
 672 void
 673 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 674 {
 675         Channel *c = channel_by_id(id);
 676
 677         if (c == NULL) {
 678                 logit("channel_register_cleanup: %d: bad id", id);
 679                 return;
 680         }
 681         c->detach_user = fn;
 682         c->detach_close = do_close;
 683 }
 684
 685 void
 686 channel_cancel_cleanup(int id)
 687 {
 688         Channel *c = channel_by_id(id);
 689
 690         if (c == NULL) {
 691                 logit("channel_cancel_cleanup: %d: bad id", id);
 692                 return;
 693         }
 694         c->detach_user = NULL;
 695         c->detach_close = 0;
 696 }
 697
 698 void
 699 channel_register_filter(int id, channel_infilter_fn *ifn,
 700     channel_outfilter_fn *ofn)
 701 {
 702         Channel *c = channel_lookup(id);
 703
 704         if (c == NULL) {
 705                 logit("channel_register_filter: %d: bad id", id);
 706                 return;
 707         }
 708         c->input_filter = ifn;
 709         c->output_filter = ofn;
 710 }
 711
 712 void
 713 channel_set_fds(int id, int rfd, int wfd, int efd,
 714     int extusage, int nonblock, u_int window_max)
 715 {
 716         Channel *c = channel_lookup(id);
 717
 718         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 719                 fatal("channel_activate for non-larval channel %d.", id);
 720         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 721         c->type = SSH_CHANNEL_OPEN;
 722         c->local_window = c->local_window_max = window_max;
 723         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 724         packet_put_int(c->remote_id);
 725         packet_put_int(c->local_window);
 726         packet_send();
 727 }
 728
 729 /*
 730  * 'channel_pre*' are called just before select() to add any bits relevant to
 731  * channels in the select bitmasks.
 732  */
 733 /*
 734  * 'channel_post*': perform any appropriate operations for channels which
 735  * have events pending.
 736  */
 737 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 738 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 739 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 740
 741 /* ARGSUSED */
 742 static void
 743 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 744 {
 745         FD_SET(c->sock, readset);
 746 }
 747
 748 /* ARGSUSED */
 749 static void
 750 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 751 {
 752         debug3("channel %d: waiting for connection", c->self);
 753         FD_SET(c->sock, writeset);
 754 }
 755
 756 static void
 757 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 758 {
 759         if (buffer_len(&c->input) < packet_get_maxsize())
 760                 FD_SET(c->sock, readset);
 761         if (buffer_len(&c->output) > 0)
 762                 FD_SET(c->sock, writeset);
 763 }
 764
 765 static void
 766 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 767 {
 768         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 769
 770         if (c->istate == CHAN_INPUT_OPEN &&
 771             limit > 0 &&
 772             buffer_len(&c->input) < limit &&
 773             buffer_check_alloc(&c->input, CHAN_RBUF))
 774                 FD_SET(c->rfd, readset);
 775         if (c->ostate == CHAN_OUTPUT_OPEN ||
 776             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 777                 if (buffer_len(&c->output) > 0) {
 778                         FD_SET(c->wfd, writeset);
 779                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 780                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 781                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 782                                     c->self, c->efd, buffer_len(&c->extended));
 783                         else
 784                                 chan_obuf_empty(c);
 785                 }
 786         }
 787         /** XXX check close conditions, too */
 788         if (compat20 && c->efd != -1) {
 789                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 790                     buffer_len(&c->extended) > 0)
 791                         FD_SET(c->efd, writeset);
 792                 else if (!(c->flags & CHAN_EOF_SENT) &&
 793                     c->extended_usage == CHAN_EXTENDED_READ &&
 794                     buffer_len(&c->extended) < c->remote_window)
 795                         FD_SET(c->efd, readset);
 796         }
 797         /* XXX: What about efd? races? */
 798         if (compat20 && c->ctl_fd != -1 &&
 799             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 800                 FD_SET(c->ctl_fd, readset);
 801 }
 802
 803 /* ARGSUSED */
 804 static void
 805 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 806 {
 807         if (buffer_len(&c->input) == 0) {
 808                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 809                 packet_put_int(c->remote_id);
 810                 packet_send();
 811                 c->type = SSH_CHANNEL_CLOSED;
 812                 debug2("channel %d: closing after input drain.", c->self);
 813         }
 814 }
 815
 816 /* ARGSUSED */
 817 static void
 818 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 819 {
 820         if (buffer_len(&c->output) == 0)
 821                 chan_mark_dead(c);
 822         else
 823                 FD_SET(c->sock, writeset);
 824 }
 825
 826 /*
 827  * This is a special state for X11 authentication spoofing.  An opened X11
 828  * connection (when authentication spoofing is being done) remains in this
 829  * state until the first packet has been completely read.  The authentication
 830  * data in that packet is then substituted by the real data if it matches the
 831  * fake data, and the channel is put into normal mode.
 832  * XXX All this happens at the client side.
 833  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 834  */
 835 static int
 836 x11_open_helper(Buffer *b)
 837 {
 838         u_char *ucp;
 839         u_int proto_len, data_len;
 840
 841         /* Check if the fixed size part of the packet is in buffer. */
 842         if (buffer_len(b) < 12)
 843                 return 0;
 844
 845         /* Parse the lengths of variable-length fields. */
 846         ucp = buffer_ptr(b);
 847         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 848                 proto_len = 256 * ucp[6] + ucp[7];
 849                 data_len = 256 * ucp[8] + ucp[9];
 850         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 851                 proto_len = ucp[6] + 256 * ucp[7];
 852                 data_len = ucp[8] + 256 * ucp[9];
 853         } else {
 854                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 855                     ucp[0]);
 856                 return -1;
 857         }
 858
 859         /* Check if the whole packet is in buffer. */
 860         if (buffer_len(b) <
 861             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 862                 return 0;
 863
 864         /* Check if authentication protocol matches. */
 865         if (proto_len != strlen(x11_saved_proto) ||
 866             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 867                 debug2("X11 connection uses different authentication protocol.");
 868                 return -1;
 869         }
 870         /* Check if authentication data matches our fake data. */
 871         if (data_len != x11_fake_data_len ||
 872             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 873                 x11_fake_data, x11_fake_data_len) != 0) {
 874                 debug2("X11 auth data does not match fake data.");
 875                 return -1;
 876         }
 877         /* Check fake data length */
 878         if (x11_fake_data_len != x11_saved_data_len) {
 879                 error("X11 fake_data_len %d != saved_data_len %d",
 880                     x11_fake_data_len, x11_saved_data_len);
 881                 return -1;
 882         }
 883         /*
 884          * Received authentication protocol and data match
 885          * our fake data. Substitute the fake data with real
 886          * data.
 887          */
 888         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 889             x11_saved_data, x11_saved_data_len);
 890         return 1;
 891 }
 892
 893 static void
 894 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 895 {
 896         int ret = x11_open_helper(&c->output);
 897
 898         if (ret == 1) {
 899                 /* Start normal processing for the channel. */
 900                 c->type = SSH_CHANNEL_OPEN;
 901                 channel_pre_open_13(c, readset, writeset);
 902         } else if (ret == -1) {
 903                 /*
 904                  * We have received an X11 connection that has bad
 905                  * authentication information.
 906                  */
 907                 logit("X11 connection rejected because of wrong authentication.");
 908                 buffer_clear(&c->input);
 909                 buffer_clear(&c->output);
 910                 channel_close_fd(&c->sock);
 911                 c->sock = -1;
 912                 c->type = SSH_CHANNEL_CLOSED;
 913                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 914                 packet_put_int(c->remote_id);
 915                 packet_send();
 916         }
 917 }
 918
 919 static void
 920 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 921 {
 922         int ret = x11_open_helper(&c->output);
 923
 924         /* c->force_drain = 1; */
 925
 926         if (ret == 1) {
 927                 c->type = SSH_CHANNEL_OPEN;
 928                 channel_pre_open(c, readset, writeset);
 929         } else if (ret == -1) {
 930                 logit("X11 connection rejected because of wrong authentication.");
 931                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 932                 chan_read_failed(c);
 933                 buffer_clear(&c->input);
 934                 chan_ibuf_empty(c);
 935                 buffer_clear(&c->output);
 936                 /* for proto v1, the peer will send an IEOF */
 937                 if (compat20)
 938                         chan_write_failed(c);
 939                 else
 940                         c->type = SSH_CHANNEL_OPEN;
 941                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 942         }
 943 }
 944
 945 /* try to decode a socks4 header */
 946 /* ARGSUSED */
 947 static int
 948 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 949 {
 950         char *p, *host;
 951         u_int len, have, i, found;
 952         char username[256];
 953         struct {
 954                 u_int8_t version;
 955                 u_int8_t command;
 956                 u_int16_t dest_port;
 957                 struct in_addr dest_addr;
 958         } s4_req, s4_rsp;
 959
 960         debug2("channel %d: decode socks4", c->self);
 961
 962         have = buffer_len(&c->input);
 963         len = sizeof(s4_req);
 964         if (have < len)
 965                 return 0;
 966         p = buffer_ptr(&c->input);
 967         for (found = 0, i = len; i < have; i++) {
 968                 if (p[i] == '\0') {
 969                         found = 1;
 970                         break;
 971                 }
 972                 if (i > 1024) {
 973                         /* the peer is probably sending garbage */
 974                         debug("channel %d: decode socks4: too long",
 975                             c->self);
 976                         return -1;
 977                 }
 978         }
 979         if (!found)
 980                 return 0;
 981         buffer_get(&c->input, (char *)&s4_req.version, 1);
 982         buffer_get(&c->input, (char *)&s4_req.command, 1);
 983         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 984         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 985         have = buffer_len(&c->input);
 986         p = buffer_ptr(&c->input);
 987         len = strlen(p);
 988         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 989         if (len > have)
 990                 fatal("channel %d: decode socks4: len %d > have %d",
 991                     c->self, len, have);
 992         strlcpy(username, p, sizeof(username));
 993         buffer_consume(&c->input, len);
 994         buffer_consume(&c->input, 1);           /* trailing '\0' */
 995
 996         host = inet_ntoa(s4_req.dest_addr);
 997         strlcpy(c->path, host, sizeof(c->path));
 998         c->host_port = ntohs(s4_req.dest_port);
 999
1000         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1001             c->self, host, c->host_port, s4_req.command);
1002
1003         if (s4_req.command != 1) {
1004                 debug("channel %d: cannot handle: socks4 cn %d",
1005                     c->self, s4_req.command);
1006                 return -1;
1007         }
1008         s4_rsp.version = 0;                     /* vn: 0 for reply */
1009         s4_rsp.command = 90;                    /* cd: req granted */
1010         s4_rsp.dest_port = 0;                   /* ignored */
1011         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1012         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1013         return 1;
1014 }
1015
1016 /* try to decode a socks5 header */
1017 #define SSH_SOCKS5_AUTHDONE     0x1000
1018 #define SSH_SOCKS5_NOAUTH       0x00
1019 #define SSH_SOCKS5_IPV4         0x01
1020 #define SSH_SOCKS5_DOMAIN       0x03
1021 #define SSH_SOCKS5_IPV6         0x04
1022 #define SSH_SOCKS5_CONNECT      0x01
1023 #define SSH_SOCKS5_SUCCESS      0x00
1024
1025 /* ARGSUSED */
1026 static int
1027 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1028 {
1029         struct {
1030                 u_int8_t version;
1031                 u_int8_t command;
1032                 u_int8_t reserved;
1033                 u_int8_t atyp;
1034         } s5_req, s5_rsp;
1035         u_int16_t dest_port;
1036         u_char *p, dest_addr[255+1];
1037         u_int have, need, i, found, nmethods, addrlen, af;
1038
1039         debug2("channel %d: decode socks5", c->self);
1040         p = buffer_ptr(&c->input);
1041         if (p[0] != 0x05)
1042                 return -1;
1043         have = buffer_len(&c->input);
1044         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1045                 /* format: ver | nmethods | methods */
1046                 if (have < 2)
1047                         return 0;
1048                 nmethods = p[1];
1049                 if (have < nmethods + 2)
1050                         return 0;
1051                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1052                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1053                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
1054                                 found = 1;
1055                                 break;
1056                         }
1057                 }
1058                 if (!found) {
1059                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1060                             c->self);
1061                         return -1;
1062                 }
1063                 buffer_consume(&c->input, nmethods + 2);
1064                 buffer_put_char(&c->output, 0x05);              /* version */
1065                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1066                 FD_SET(c->sock, writeset);
1067                 c->flags |= SSH_SOCKS5_AUTHDONE;
1068                 debug2("channel %d: socks5 auth done", c->self);
1069                 return 0;                               /* need more */
1070         }
1071         debug2("channel %d: socks5 post auth", c->self);
1072         if (have < sizeof(s5_req)+1)
1073                 return 0;                       /* need more */
1074         memcpy(&s5_req, p, sizeof(s5_req));
1075         if (s5_req.version != 0x05 ||
1076             s5_req.command != SSH_SOCKS5_CONNECT ||
1077             s5_req.reserved != 0x00) {
1078                 debug2("channel %d: only socks5 connect supported", c->self);
1079                 return -1;
1080         }
1081         switch (s5_req.atyp){
1082         case SSH_SOCKS5_IPV4:
1083                 addrlen = 4;
1084                 af = AF_INET;
1085                 break;
1086         case SSH_SOCKS5_DOMAIN:
1087                 addrlen = p[sizeof(s5_req)];
1088                 af = -1;
1089                 break;
1090         case SSH_SOCKS5_IPV6:
1091                 addrlen = 16;
1092                 af = AF_INET6;
1093                 break;
1094         default:
1095                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1096                 return -1;
1097         }
1098         need = sizeof(s5_req) + addrlen + 2;
1099         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1100                 need++;
1101         if (have < need)
1102                 return 0;
1103         buffer_consume(&c->input, sizeof(s5_req));
1104         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1105                 buffer_consume(&c->input, 1);    /* host string length */
1106         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1107         buffer_get(&c->input, (char *)&dest_port, 2);
1108         dest_addr[addrlen] = '\0';
1109         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1110                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1111         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1112                 return -1;
1113         c->host_port = ntohs(dest_port);
1114
1115         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1116             c->self, c->path, c->host_port, s5_req.command);
1117
1118         s5_rsp.version = 0x05;
1119         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1120         s5_rsp.reserved = 0;                    /* ignored */
1121         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1122         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1123         dest_port = 0;                          /* ignored */
1124
1125         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1126         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1127         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1128         return 1;
1129 }
1130
1131 /* dynamic port forwarding */
1132 static void
1133 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1134 {
1135         u_char *p;
1136         u_int have;
1137         int ret;
1138
1139         have = buffer_len(&c->input);
1140         c->delayed = 0;
1141         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1142         /* buffer_dump(&c->input); */
1143         /* check if the fixed size part of the packet is in buffer. */
1144         if (have < 3) {
1145                 /* need more */
1146                 FD_SET(c->sock, readset);
1147                 return;
1148         }
1149         /* try to guess the protocol */
1150         p = buffer_ptr(&c->input);
1151         switch (p[0]) {
1152         case 0x04:
1153                 ret = channel_decode_socks4(c, readset, writeset);
1154                 break;
1155         case 0x05:
1156                 ret = channel_decode_socks5(c, readset, writeset);
1157                 break;
1158         default:
1159                 ret = -1;
1160                 break;
1161         }
1162         if (ret < 0) {
1163                 chan_mark_dead(c);
1164         } else if (ret == 0) {
1165                 debug2("channel %d: pre_dynamic: need more", c->self);
1166                 /* need more */
1167                 FD_SET(c->sock, readset);
1168         } else {
1169                 /* switch to the next state */
1170                 c->type = SSH_CHANNEL_OPENING;
1171                 port_open_helper(c, "direct-tcpip");
1172         }
1173 }
1174
1175 /* This is our fake X11 server socket. */
1176 /* ARGSUSED */
1177 static void
1178 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1179 {
1180         Channel *nc;
1181         struct sockaddr addr;
1182         int newsock;
1183         socklen_t addrlen;
1184         char buf[16384], *remote_ipaddr;
1185         int remote_port;
1186
1187         if (FD_ISSET(c->sock, readset)) {
1188                 debug("X11 connection requested.");
1189                 addrlen = sizeof(addr);
1190                 newsock = accept(c->sock, &addr, &addrlen);
1191                 if (c->single_connection) {
1192                         debug2("single_connection: closing X11 listener.");
1193                         channel_close_fd(&c->sock);
1194                         chan_mark_dead(c);
1195                 }
1196                 if (newsock < 0) {
1197                         error("accept: %.100s", strerror(errno));
1198                         return;
1199                 }
1200                 set_nodelay(newsock);
1201                 remote_ipaddr = get_peer_ipaddr(newsock);
1202                 remote_port = get_peer_port(newsock);
1203                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1204                     remote_ipaddr, remote_port);
1205
1206                 nc = channel_new("accepted x11 socket",
1207                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1208                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1209                 if (compat20) {
1210                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1211                         packet_put_cstring("x11");
1212                         packet_put_int(nc->self);
1213                         packet_put_int(nc->local_window_max);
1214                         packet_put_int(nc->local_maxpacket);
1215                         /* originator ipaddr and port */
1216                         packet_put_cstring(remote_ipaddr);
1217                         if (datafellows & SSH_BUG_X11FWD) {
1218                                 debug2("ssh2 x11 bug compat mode");
1219                         } else {
1220                                 packet_put_int(remote_port);
1221                         }
1222                         packet_send();
1223                 } else {
1224                         packet_start(SSH_SMSG_X11_OPEN);
1225                         packet_put_int(nc->self);
1226                         if (packet_get_protocol_flags() &
1227                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1228                                 packet_put_cstring(buf);
1229                         packet_send();
1230                 }
1231                 xfree(remote_ipaddr);
1232         }
1233 }
1234
1235 static void
1236 port_open_helper(Channel *c, char *rtype)
1237 {
1238         int direct;
1239         char buf[1024];
1240         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1241         int remote_port = get_peer_port(c->sock);
1242
1243         direct = (strcmp(rtype, "direct-tcpip") == 0);
1244
1245         snprintf(buf, sizeof buf,
1246             "%s: listening port %d for %.100s port %d, "
1247             "connect from %.200s port %d",
1248             rtype, c->listening_port, c->path, c->host_port,
1249             remote_ipaddr, remote_port);
1250
1251         xfree(c->remote_name);
1252         c->remote_name = xstrdup(buf);
1253
1254         if (compat20) {
1255                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1256                 packet_put_cstring(rtype);
1257                 packet_put_int(c->self);
1258                 packet_put_int(c->local_window_max);
1259                 packet_put_int(c->local_maxpacket);
1260                 if (direct) {
1261                         /* target host, port */
1262                         packet_put_cstring(c->path);
1263                         packet_put_int(c->host_port);
1264                 } else {
1265                         /* listen address, port */
1266                         packet_put_cstring(c->path);
1267                         packet_put_int(c->listening_port);
1268                 }
1269                 /* originator host and port */
1270                 packet_put_cstring(remote_ipaddr);
1271                 packet_put_int((u_int)remote_port);
1272                 packet_send();
1273         } else {
1274                 packet_start(SSH_MSG_PORT_OPEN);
1275                 packet_put_int(c->self);
1276                 packet_put_cstring(c->path);
1277                 packet_put_int(c->host_port);
1278                 if (packet_get_protocol_flags() &
1279                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1280                         packet_put_cstring(c->remote_name);
1281                 packet_send();
1282         }
1283         xfree(remote_ipaddr);
1284 }
1285
1286 static void
1287 channel_set_reuseaddr(int fd)
1288 {
1289         int on = 1;
1290
1291         /*
1292          * Set socket options.
1293          * Allow local port reuse in TIME_WAIT.
1294          */
1295         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1296                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1297 }
1298
1299 /*
1300  * This socket is listening for connections to a forwarded TCP/IP port.
1301  */
1302 /* ARGSUSED */
1303 static void
1304 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1305 {
1306         Channel *nc;
1307         struct sockaddr addr;
1308         int newsock, nextstate;
1309         socklen_t addrlen;
1310         char *rtype;
1311
1312         if (FD_ISSET(c->sock, readset)) {
1313                 debug("Connection to port %d forwarding "
1314                     "to %.100s port %d requested.",
1315                     c->listening_port, c->path, c->host_port);
1316
1317                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1318                         nextstate = SSH_CHANNEL_OPENING;
1319                         rtype = "forwarded-tcpip";
1320                 } else {
1321                         if (c->host_port == 0) {
1322                                 nextstate = SSH_CHANNEL_DYNAMIC;
1323                                 rtype = "dynamic-tcpip";
1324                         } else {
1325                                 nextstate = SSH_CHANNEL_OPENING;
1326                                 rtype = "direct-tcpip";
1327                         }
1328                 }
1329
1330                 addrlen = sizeof(addr);
1331                 newsock = accept(c->sock, &addr, &addrlen);
1332                 if (newsock < 0) {
1333                         error("accept: %.100s", strerror(errno));
1334                         return;
1335                 }
1336                 set_nodelay(newsock);
1337                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1338                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1339                 nc->listening_port = c->listening_port;
1340                 nc->host_port = c->host_port;
1341                 strlcpy(nc->path, c->path, sizeof(nc->path));
1342
1343                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1344                         /*
1345                          * do not call the channel_post handler until
1346                          * this flag has been reset by a pre-handler.
1347                          * otherwise the FD_ISSET calls might overflow
1348                          */
1349                         nc->delayed = 1;
1350                 } else {
1351                         port_open_helper(nc, rtype);
1352                 }
1353         }
1354 }
1355
1356 /*
1357  * This is the authentication agent socket listening for connections from
1358  * clients.
1359  */
1360 /* ARGSUSED */
1361 static void
1362 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1363 {
1364         Channel *nc;
1365         int newsock;
1366         struct sockaddr addr;
1367         socklen_t addrlen;
1368
1369         if (FD_ISSET(c->sock, readset)) {
1370                 addrlen = sizeof(addr);
1371                 newsock = accept(c->sock, &addr, &addrlen);
1372                 if (newsock < 0) {
1373                         error("accept from auth socket: %.100s", strerror(errno));
1374                         return;
1375                 }
1376                 nc = channel_new("accepted auth socket",
1377                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1378                     c->local_window_max, c->local_maxpacket,
1379                     0, "accepted auth socket", 1);
1380                 if (compat20) {
1381                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1382                         packet_put_cstring("auth-agent@openssh.com");
1383                         packet_put_int(nc->self);
1384                         packet_put_int(c->local_window_max);
1385                         packet_put_int(c->local_maxpacket);
1386                 } else {
1387                         packet_start(SSH_SMSG_AGENT_OPEN);
1388                         packet_put_int(nc->self);
1389                 }
1390                 packet_send();
1391         }
1392 }
1393
1394 /* ARGSUSED */
1395 static void
1396 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1397 {
1398         int err = 0;
1399         socklen_t sz = sizeof(err);
1400
1401         if (FD_ISSET(c->sock, writeset)) {
1402                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1403                         err = errno;
1404                         error("getsockopt SO_ERROR failed");
1405                 }
1406                 if (err == 0) {
1407                         debug("channel %d: connected", c->self);
1408                         c->type = SSH_CHANNEL_OPEN;
1409                         if (compat20) {
1410                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1411                                 packet_put_int(c->remote_id);
1412                                 packet_put_int(c->self);
1413                                 packet_put_int(c->local_window);
1414                                 packet_put_int(c->local_maxpacket);
1415                         } else {
1416                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1417                                 packet_put_int(c->remote_id);
1418                                 packet_put_int(c->self);
1419                         }
1420                 } else {
1421                         debug("channel %d: not connected: %s",
1422                             c->self, strerror(err));
1423                         if (compat20) {
1424                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1425                                 packet_put_int(c->remote_id);
1426                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1427                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1428                                         packet_put_cstring(strerror(err));
1429                                         packet_put_cstring("");
1430                                 }
1431                         } else {
1432                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1433                                 packet_put_int(c->remote_id);
1434                         }
1435                         chan_mark_dead(c);
1436                 }
1437                 packet_send();
1438         }
1439 }
1440
1441 /* ARGSUSED */
1442 static int
1443 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1444 {
1445         char buf[CHAN_RBUF];
1446         int len;
1447
1448         if (c->rfd != -1 &&
1449             FD_ISSET(c->rfd, readset)) {
1450                 errno = 0;
1451                 len = read(c->rfd, buf, sizeof(buf));
1452                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1453                         return 1;
1454 #ifndef PTY_ZEROREAD
1455                 if (len <= 0) {
1456 #else
1457                 if ((!c->isatty && len <= 0) ||
1458                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1459 #endif
1460                         debug2("channel %d: read<=0 rfd %d len %d",
1461                             c->self, c->rfd, len);
1462                         if (c->type != SSH_CHANNEL_OPEN) {
1463                                 debug2("channel %d: not open", c->self);
1464                                 chan_mark_dead(c);
1465                                 return -1;
1466                         } else if (compat13) {
1467                                 buffer_clear(&c->output);
1468                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1469                                 debug2("channel %d: input draining.", c->self);
1470                         } else {
1471                                 chan_read_failed(c);
1472                         }
1473                         return -1;
1474                 }
1475                 if (c->input_filter != NULL) {
1476                         if (c->input_filter(c, buf, len) == -1) {
1477                                 debug2("channel %d: filter stops", c->self);
1478                                 chan_read_failed(c);
1479                         }
1480                 } else if (c->datagram) {
1481                         buffer_put_string(&c->input, buf, len);
1482                 } else {
1483                         buffer_append(&c->input, buf, len);
1484                 }
1485         }
1486         return 1;
1487 }
1488
1489 /* ARGSUSED */
1490 static int
1491 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1492 {
1493         struct termios tio;
1494         u_char *data = NULL, *buf;
1495         u_int dlen;
1496         int len;
1497
1498         /* Send buffered output data to the socket. */
1499         if (c->wfd != -1 &&
1500             FD_ISSET(c->wfd, writeset) &&
1501             buffer_len(&c->output) > 0) {
1502                 if (c->output_filter != NULL) {
1503                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1504                                 debug2("channel %d: filter stops", c->self);
1505                                 if (c->type != SSH_CHANNEL_OPEN)
1506                                         chan_mark_dead(c);
1507                                 else
1508                                         chan_write_failed(c);
1509                                 return -1;
1510                         }
1511                 } else if (c->datagram) {
1512                         buf = data = buffer_get_string(&c->output, &dlen);
1513                 } else {
1514                         buf = data = buffer_ptr(&c->output);
1515                         dlen = buffer_len(&c->output);
1516                 }
1517
1518                 if (c->datagram) {
1519                         /* ignore truncated writes, datagrams might get lost */
1520                         c->local_consumed += dlen + 4;
1521                         len = write(c->wfd, buf, dlen);
1522                         xfree(data);
1523                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1524                                 return 1;
1525                         if (len <= 0) {
1526                                 if (c->type != SSH_CHANNEL_OPEN)
1527                                         chan_mark_dead(c);
1528                                 else
1529                                         chan_write_failed(c);
1530                                 return -1;
1531                         }
1532                         return 1;
1533                 }
1534 #ifdef _AIX
1535                 /* XXX: Later AIX versions can't push as much data to tty */
1536                 if (compat20 && c->wfd_isatty)
1537                         dlen = MIN(dlen, 8*1024);
1538 #endif
1539
1540                 len = write(c->wfd, buf, dlen);
1541                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1542                         return 1;
1543                 if (len <= 0) {
1544                         if (c->type != SSH_CHANNEL_OPEN) {
1545                                 debug2("channel %d: not open", c->self);
1546                                 chan_mark_dead(c);
1547                                 return -1;
1548                         } else if (compat13) {
1549                                 buffer_clear(&c->output);
1550                                 debug2("channel %d: input draining.", c->self);
1551                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1552                         } else {
1553                                 chan_write_failed(c);
1554                         }
1555                         return -1;
1556                 }
1557                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1558                         if (tcgetattr(c->wfd, &tio) == 0 &&
1559                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1560                                 /*
1561                                  * Simulate echo to reduce the impact of
1562                                  * traffic analysis. We need to match the
1563                                  * size of a SSH2_MSG_CHANNEL_DATA message
1564                                  * (4 byte channel id + buf)
1565                                  */
1566                                 packet_send_ignore(4 + len);
1567                                 packet_send();
1568                         }
1569                 }
1570                 buffer_consume(&c->output, len);
1571                 if (compat20 && len > 0) {
1572                         c->local_consumed += len;
1573                 }
1574         }
1575         return 1;
1576 }
1577
1578 static int
1579 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1580 {
1581         char buf[CHAN_RBUF];
1582         int len;
1583
1584 /** XXX handle drain efd, too */
1585         if (c->efd != -1) {
1586                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1587                     FD_ISSET(c->efd, writeset) &&
1588                     buffer_len(&c->extended) > 0) {
1589                         len = write(c->efd, buffer_ptr(&c->extended),
1590                             buffer_len(&c->extended));
1591                         debug2("channel %d: written %d to efd %d",
1592                             c->self, len, c->efd);
1593                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1594                                 return 1;
1595                         if (len <= 0) {
1596                                 debug2("channel %d: closing write-efd %d",
1597                                     c->self, c->efd);
1598                                 channel_close_fd(&c->efd);
1599                         } else {
1600                                 buffer_consume(&c->extended, len);
1601                                 c->local_consumed += len;
1602                         }
1603                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1604                     FD_ISSET(c->efd, readset)) {
1605                         len = read(c->efd, buf, sizeof(buf));
1606                         debug2("channel %d: read %d from efd %d",
1607                             c->self, len, c->efd);
1608                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1609                                 return 1;
1610                         if (len <= 0) {
1611                                 debug2("channel %d: closing read-efd %d",
1612                                     c->self, c->efd);
1613                                 channel_close_fd(&c->efd);
1614                         } else {
1615                                 buffer_append(&c->extended, buf, len);
1616                         }
1617                 }
1618         }
1619         return 1;
1620 }
1621
1622 /* ARGSUSED */
1623 static int
1624 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1625 {
1626         char buf[16];
1627         int len;
1628
1629         /* Monitor control fd to detect if the slave client exits */
1630         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1631                 len = read(c->ctl_fd, buf, sizeof(buf));
1632                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1633                         return 1;
1634                 if (len <= 0) {
1635                         debug2("channel %d: ctl read<=0", c->self);
1636                         if (c->type != SSH_CHANNEL_OPEN) {
1637                                 debug2("channel %d: not open", c->self);
1638                                 chan_mark_dead(c);
1639                                 return -1;
1640                         } else {
1641                                 chan_read_failed(c);
1642                                 chan_write_failed(c);
1643                         }
1644                         return -1;
1645                 } else
1646                         fatal("%s: unexpected data on ctl fd", __func__);
1647         }
1648         return 1;
1649 }
1650
1651 static int
1652 channel_check_window(Channel *c)
1653 {
1654         if (c->type == SSH_CHANNEL_OPEN &&
1655             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1656             c->local_window < c->local_window_max/2 &&
1657             c->local_consumed > 0) {
1658                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1659                 packet_put_int(c->remote_id);
1660                 packet_put_int(c->local_consumed);
1661                 packet_send();
1662                 debug2("channel %d: window %d sent adjust %d",
1663                     c->self, c->local_window,
1664                     c->local_consumed);
1665                 c->local_window += c->local_consumed;
1666                 c->local_consumed = 0;
1667         }
1668         return 1;
1669 }
1670
1671 static void
1672 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1673 {
1674         if (c->delayed)
1675                 return;
1676         channel_handle_rfd(c, readset, writeset);
1677         channel_handle_wfd(c, readset, writeset);
1678         if (!compat20)
1679                 return;
1680         channel_handle_efd(c, readset, writeset);
1681         channel_handle_ctl(c, readset, writeset);
1682         channel_check_window(c);
1683 }
1684
1685 /* ARGSUSED */
1686 static void
1687 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1688 {
1689         int len;
1690
1691         /* Send buffered output data to the socket. */
1692         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1693                 len = write(c->sock, buffer_ptr(&c->output),
1694                             buffer_len(&c->output));
1695                 if (len <= 0)
1696                         buffer_clear(&c->output);
1697                 else
1698                         buffer_consume(&c->output, len);
1699         }
1700 }
1701
1702 static void
1703 channel_handler_init_20(void)
1704 {
1705         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1706         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1707         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1708         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1709         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1710         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1711         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1712         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1713
1714         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1715         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1716         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1717         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1718         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1719         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1720         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1721 }
1722
1723 static void
1724 channel_handler_init_13(void)
1725 {
1726         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1727         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1728         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1729         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1730         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1731         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1732         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1733         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1734         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1735
1736         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1737         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1738         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1739         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1740         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1741         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1742         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1743 }
1744
1745 static void
1746 channel_handler_init_15(void)
1747 {
1748         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1749         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1750         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1751         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1752         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1753         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1754         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1755
1756         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1757         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1758         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1759         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1760         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1761         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1762 }
1763
1764 static void
1765 channel_handler_init(void)
1766 {
1767         int i;
1768
1769         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1770                 channel_pre[i] = NULL;
1771                 channel_post[i] = NULL;
1772         }
1773         if (compat20)
1774                 channel_handler_init_20();
1775         else if (compat13)
1776                 channel_handler_init_13();
1777         else
1778                 channel_handler_init_15();
1779 }
1780
1781 /* gc dead channels */
1782 static void
1783 channel_garbage_collect(Channel *c)
1784 {
1785         if (c == NULL)
1786                 return;
1787         if (c->detach_user != NULL) {
1788                 if (!chan_is_dead(c, c->detach_close))
1789                         return;
1790                 debug2("channel %d: gc: notify user", c->self);
1791                 c->detach_user(c->self, NULL);
1792                 /* if we still have a callback */
1793                 if (c->detach_user != NULL)
1794                         return;
1795                 debug2("channel %d: gc: user detached", c->self);
1796         }
1797         if (!chan_is_dead(c, 1))
1798                 return;
1799         debug2("channel %d: garbage collecting", c->self);
1800         channel_free(c);
1801 }
1802
1803 static void
1804 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1805 {
1806         static int did_init = 0;
1807         u_int i;
1808         Channel *c;
1809
1810         if (!did_init) {
1811                 channel_handler_init();
1812                 did_init = 1;
1813         }
1814         for (i = 0; i < channels_alloc; i++) {
1815                 c = channels[i];
1816                 if (c == NULL)
1817                         continue;
1818                 if (ftab[c->type] != NULL)
1819                         (*ftab[c->type])(c, readset, writeset);
1820                 channel_garbage_collect(c);
1821         }
1822 }
1823
1824 /*
1825  * Allocate/update select bitmasks and add any bits relevant to channels in
1826  * select bitmasks.
1827  */
1828 void
1829 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1830     u_int *nallocp, int rekeying)
1831 {
1832         u_int n, sz, nfdset;
1833
1834         n = MAX(*maxfdp, channel_max_fd);
1835
1836         nfdset = howmany(n+1, NFDBITS);
1837         /* Explicitly test here, because xrealloc isn't always called */
1838         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1839                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1840         sz = nfdset * sizeof(fd_mask);
1841
1842         /* perhaps check sz < nalloc/2 and shrink? */
1843         if (*readsetp == NULL || sz > *nallocp) {
1844                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1845                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1846                 *nallocp = sz;
1847         }
1848         *maxfdp = n;
1849         memset(*readsetp, 0, sz);
1850         memset(*writesetp, 0, sz);
1851
1852         if (!rekeying)
1853                 channel_handler(channel_pre, *readsetp, *writesetp);
1854 }
1855
1856 /*
1857  * After select, perform any appropriate operations for channels which have
1858  * events pending.
1859  */
1860 void
1861 channel_after_select(fd_set *readset, fd_set *writeset)
1862 {
1863         channel_handler(channel_post, readset, writeset);
1864 }
1865
1866
1867 /* If there is data to send to the connection, enqueue some of it now. */
1868 void
1869 channel_output_poll(void)
1870 {
1871         Channel *c;
1872         u_int i, len;
1873
1874         for (i = 0; i < channels_alloc; i++) {
1875                 c = channels[i];
1876                 if (c == NULL)
1877                         continue;
1878
1879                 /*
1880                  * We are only interested in channels that can have buffered
1881                  * incoming data.
1882                  */
1883                 if (compat13) {
1884                         if (c->type != SSH_CHANNEL_OPEN &&
1885                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1886                                 continue;
1887                 } else {
1888                         if (c->type != SSH_CHANNEL_OPEN)
1889                                 continue;
1890                 }
1891                 if (compat20 &&
1892                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1893                         /* XXX is this true? */
1894                         debug3("channel %d: will not send data after close", c->self);
1895                         continue;
1896                 }
1897
1898                 /* Get the amount of buffered data for this channel. */
1899                 if ((c->istate == CHAN_INPUT_OPEN ||
1900                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1901                     (len = buffer_len(&c->input)) > 0) {
1902                         if (c->datagram) {
1903                                 if (len > 0) {
1904                                         u_char *data;
1905                                         u_int dlen;
1906
1907                                         data = buffer_get_string(&c->input,
1908                                             &dlen);
1909                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1910                                         packet_put_int(c->remote_id);
1911                                         packet_put_string(data, dlen);
1912                                         packet_send();
1913                                         c->remote_window -= dlen + 4;
1914                                         xfree(data);
1915                                 }
1916                                 continue;
1917                         }
1918                         /*
1919                          * Send some data for the other side over the secure
1920                          * connection.
1921                          */
1922                         if (compat20) {
1923                                 if (len > c->remote_window)
1924                                         len = c->remote_window;
1925                                 if (len > c->remote_maxpacket)
1926                                         len = c->remote_maxpacket;
1927                         } else {
1928                                 if (packet_is_interactive()) {
1929                                         if (len > 1024)
1930                                                 len = 512;
1931                                 } else {
1932                                         /* Keep the packets at reasonable size. */
1933                                         if (len > packet_get_maxsize()/2)
1934                                                 len = packet_get_maxsize()/2;
1935                                 }
1936                         }
1937                         if (len > 0) {
1938                                 packet_start(compat20 ?
1939                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1940                                 packet_put_int(c->remote_id);
1941                                 packet_put_string(buffer_ptr(&c->input), len);
1942                                 packet_send();
1943                                 buffer_consume(&c->input, len);
1944                                 c->remote_window -= len;
1945                         }
1946                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1947                         if (compat13)
1948                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1949                         /*
1950                          * input-buffer is empty and read-socket shutdown:
1951                          * tell peer, that we will not send more data: send IEOF.
1952                          * hack for extended data: delay EOF if EFD still in use.
1953                          */
1954                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1955                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1956                                     c->self, c->efd, buffer_len(&c->extended));
1957                         else
1958                                 chan_ibuf_empty(c);
1959                 }
1960                 /* Send extended data, i.e. stderr */
1961                 if (compat20 &&
1962                     !(c->flags & CHAN_EOF_SENT) &&
1963                     c->remote_window > 0 &&
1964                     (len = buffer_len(&c->extended)) > 0 &&
1965                     c->extended_usage == CHAN_EXTENDED_READ) {
1966                         debug2("channel %d: rwin %u elen %u euse %d",
1967                             c->self, c->remote_window, buffer_len(&c->extended),
1968                             c->extended_usage);
1969                         if (len > c->remote_window)
1970                                 len = c->remote_window;
1971                         if (len > c->remote_maxpacket)
1972                                 len = c->remote_maxpacket;
1973                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1974                         packet_put_int(c->remote_id);
1975                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1976                         packet_put_string(buffer_ptr(&c->extended), len);
1977                         packet_send();
1978                         buffer_consume(&c->extended, len);
1979                         c->remote_window -= len;
1980                         debug2("channel %d: sent ext data %d", c->self, len);
1981                 }
1982         }
1983 }
1984
1985
1986 /* -- protocol input */
1987
1988 /* ARGSUSED */
1989 void
1990 channel_input_data(int type, u_int32_t seq, void *ctxt)
1991 {
1992         int id;
1993         char *data;
1994         u_int data_len;
1995         Channel *c;
1996
1997         /* Get the channel number and verify it. */
1998         id = packet_get_int();
1999         c = channel_lookup(id);
2000         if (c == NULL)
2001                 packet_disconnect("Received data for nonexistent channel %d.", id);
2002
2003         /* Ignore any data for non-open channels (might happen on close) */
2004         if (c->type != SSH_CHANNEL_OPEN &&
2005             c->type != SSH_CHANNEL_X11_OPEN)
2006                 return;
2007
2008         /* Get the data. */
2009         data = packet_get_string(&data_len);
2010
2011         /*
2012          * Ignore data for protocol > 1.3 if output end is no longer open.
2013          * For protocol 2 the sending side is reducing its window as it sends
2014          * data, so we must 'fake' consumption of the data in order to ensure
2015          * that window updates are sent back.  Otherwise the connection might
2016          * deadlock.
2017          */
2018         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2019                 if (compat20) {
2020                         c->local_window -= data_len;
2021                         c->local_consumed += data_len;
2022                 }
2023                 xfree(data);
2024                 return;
2025         }
2026
2027         if (compat20) {
2028                 if (data_len > c->local_maxpacket) {
2029                         logit("channel %d: rcvd big packet %d, maxpack %d",
2030                             c->self, data_len, c->local_maxpacket);
2031                 }
2032                 if (data_len > c->local_window) {
2033                         logit("channel %d: rcvd too much data %d, win %d",
2034                             c->self, data_len, c->local_window);
2035                         xfree(data);
2036                         return;
2037                 }
2038                 c->local_window -= data_len;
2039         }
2040         packet_check_eom();
2041         if (c->datagram)
2042                 buffer_put_string(&c->output, data, data_len);
2043         else
2044                 buffer_append(&c->output, data, data_len);
2045         xfree(data);
2046 }
2047
2048 /* ARGSUSED */
2049 void
2050 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2051 {
2052         int id;
2053         char *data;
2054         u_int data_len, tcode;
2055         Channel *c;
2056
2057         /* Get the channel number and verify it. */
2058         id = packet_get_int();
2059         c = channel_lookup(id);
2060
2061         if (c == NULL)
2062                 packet_disconnect("Received extended_data for bad channel %d.", id);
2063         if (c->type != SSH_CHANNEL_OPEN) {
2064                 logit("channel %d: ext data for non open", id);
2065                 return;
2066         }
2067         if (c->flags & CHAN_EOF_RCVD) {
2068                 if (datafellows & SSH_BUG_EXTEOF)
2069                         debug("channel %d: accepting ext data after eof", id);
2070                 else
2071                         packet_disconnect("Received extended_data after EOF "
2072                             "on channel %d.", id);
2073         }
2074         tcode = packet_get_int();
2075         if (c->efd == -1 ||
2076             c->extended_usage != CHAN_EXTENDED_WRITE ||
2077             tcode != SSH2_EXTENDED_DATA_STDERR) {
2078                 logit("channel %d: bad ext data", c->self);
2079                 return;
2080         }
2081         data = packet_get_string(&data_len);
2082         packet_check_eom();
2083         if (data_len > c->local_window) {
2084                 logit("channel %d: rcvd too much extended_data %d, win %d",
2085                     c->self, data_len, c->local_window);
2086                 xfree(data);
2087                 return;
2088         }
2089         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2090         c->local_window -= data_len;
2091         buffer_append(&c->extended, data, data_len);
2092         xfree(data);
2093 }
2094
2095 /* ARGSUSED */
2096 void
2097 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2098 {
2099         int id;
2100         Channel *c;
2101
2102         id = packet_get_int();
2103         packet_check_eom();
2104         c = channel_lookup(id);
2105         if (c == NULL)
2106                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2107         chan_rcvd_ieof(c);
2108
2109         /* XXX force input close */
2110         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2111                 debug("channel %d: FORCE input drain", c->self);
2112                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2113                 if (buffer_len(&c->input) == 0)
2114                         chan_ibuf_empty(c);
2115         }
2116
2117 }
2118
2119 /* ARGSUSED */
2120 void
2121 channel_input_close(int type, u_int32_t seq, void *ctxt)
2122 {
2123         int id;
2124         Channel *c;
2125
2126         id = packet_get_int();
2127         packet_check_eom();
2128         c = channel_lookup(id);
2129         if (c == NULL)
2130                 packet_disconnect("Received close for nonexistent channel %d.", id);
2131
2132         /*
2133          * Send a confirmation that we have closed the channel and no more
2134          * data is coming for it.
2135          */
2136         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2137         packet_put_int(c->remote_id);
2138         packet_send();
2139
2140         /*
2141          * If the channel is in closed state, we have sent a close request,
2142          * and the other side will eventually respond with a confirmation.
2143          * Thus, we cannot free the channel here, because then there would be
2144          * no-one to receive the confirmation.  The channel gets freed when
2145          * the confirmation arrives.
2146          */
2147         if (c->type != SSH_CHANNEL_CLOSED) {
2148                 /*
2149                  * Not a closed channel - mark it as draining, which will
2150                  * cause it to be freed later.
2151                  */
2152                 buffer_clear(&c->input);
2153                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2154         }
2155 }
2156
2157 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2158 /* ARGSUSED */
2159 void
2160 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2161 {
2162         int id = packet_get_int();
2163         Channel *c = channel_lookup(id);
2164
2165         packet_check_eom();
2166         if (c == NULL)
2167                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2168         chan_rcvd_oclose(c);
2169 }
2170
2171 /* ARGSUSED */
2172 void
2173 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2174 {
2175         int id = packet_get_int();
2176         Channel *c = channel_lookup(id);
2177
2178         packet_check_eom();
2179         if (c == NULL)
2180                 packet_disconnect("Received close confirmation for "
2181                     "out-of-range channel %d.", id);
2182         if (c->type != SSH_CHANNEL_CLOSED)
2183                 packet_disconnect("Received close confirmation for "
2184                     "non-closed channel %d (type %d).", id, c->type);
2185         channel_free(c);
2186 }
2187
2188 /* ARGSUSED */
2189 void
2190 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2191 {
2192         int id, remote_id;
2193         Channel *c;
2194
2195         id = packet_get_int();
2196         c = channel_lookup(id);
2197
2198         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2199                 packet_disconnect("Received open confirmation for "
2200                     "non-opening channel %d.", id);
2201         remote_id = packet_get_int();
2202         /* Record the remote channel number and mark that the channel is now open. */
2203         c->remote_id = remote_id;
2204         c->type = SSH_CHANNEL_OPEN;
2205
2206         if (compat20) {
2207                 c->remote_window = packet_get_int();
2208                 c->remote_maxpacket = packet_get_int();
2209                 if (c->confirm) {
2210                         debug2("callback start");
2211                         c->confirm(c->self, c->confirm_ctx);
2212                         debug2("callback done");
2213                 }
2214                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2215                     c->remote_window, c->remote_maxpacket);
2216         }
2217         packet_check_eom();
2218 }
2219
2220 static char *
2221 reason2txt(int reason)
2222 {
2223         switch (reason) {
2224         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2225                 return "administratively prohibited";
2226         case SSH2_OPEN_CONNECT_FAILED:
2227                 return "connect failed";
2228         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2229                 return "unknown channel type";
2230         case SSH2_OPEN_RESOURCE_SHORTAGE:
2231                 return "resource shortage";
2232         }
2233         return "unknown reason";
2234 }
2235
2236 /* ARGSUSED */
2237 void
2238 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2239 {
2240         int id, reason;
2241         char *msg = NULL, *lang = NULL;
2242         Channel *c;
2243
2244         id = packet_get_int();
2245         c = channel_lookup(id);
2246
2247         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2248                 packet_disconnect("Received open failure for "
2249                     "non-opening channel %d.", id);
2250         if (compat20) {
2251                 reason = packet_get_int();
2252                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2253                         msg  = packet_get_string(NULL);
2254                         lang = packet_get_string(NULL);
2255                 }
2256                 logit("channel %d: open failed: %s%s%s", id,
2257                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2258                 if (msg != NULL)
2259                         xfree(msg);
2260                 if (lang != NULL)
2261                         xfree(lang);
2262         }
2263         packet_check_eom();
2264         /* Free the channel.  This will also close the socket. */
2265         channel_free(c);
2266 }
2267
2268 /* ARGSUSED */
2269 void
2270 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2271 {
2272         Channel *c;
2273         int id;
2274         u_int adjust;
2275
2276         if (!compat20)
2277                 return;
2278
2279         /* Get the channel number and verify it. */
2280         id = packet_get_int();
2281         c = channel_lookup(id);
2282
2283         if (c == NULL) {
2284                 logit("Received window adjust for non-open channel %d.", id);
2285                 return;
2286         }
2287         adjust = packet_get_int();
2288         packet_check_eom();
2289         debug2("channel %d: rcvd adjust %u", id, adjust);
2290         c->remote_window += adjust;
2291 }
2292
2293 /* ARGSUSED */
2294 void
2295 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2296 {
2297         Channel *c = NULL;
2298         u_short host_port;
2299         char *host, *originator_string;
2300         int remote_id, sock = -1;
2301
2302         remote_id = packet_get_int();
2303         host = packet_get_string(NULL);
2304         host_port = packet_get_int();
2305
2306         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2307                 originator_string = packet_get_string(NULL);
2308         } else {
2309                 originator_string = xstrdup("unknown (remote did not supply name)");
2310         }
2311         packet_check_eom();
2312         sock = channel_connect_to(host, host_port);
2313         if (sock != -1) {
2314                 c = channel_new("connected socket",
2315                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2316                     originator_string, 1);
2317                 c->remote_id = remote_id;
2318         }
2319         xfree(originator_string);
2320         if (c == NULL) {
2321                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2322                 packet_put_int(remote_id);
2323                 packet_send();
2324         }
2325         xfree(host);
2326 }
2327
2328
2329 /* -- tcp forwarding */
2330
2331 void
2332 channel_set_af(int af)
2333 {
2334         IPv4or6 = af;
2335 }
2336
2337 static int
2338 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2339     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2340 {
2341         Channel *c;
2342         int sock, r, success = 0, wildcard = 0, is_client;
2343         struct addrinfo hints, *ai, *aitop;
2344         const char *host, *addr;
2345         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2346
2347         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2348             listen_addr : host_to_connect;
2349         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2350
2351         if (host == NULL) {
2352                 error("No forward host name.");
2353                 return 0;
2354         }
2355         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2356                 error("Forward host name too long.");
2357                 return 0;
2358         }
2359
2360         /*
2361          * Determine whether or not a port forward listens to loopback,
2362          * specified address or wildcard. On the client, a specified bind
2363          * address will always override gateway_ports. On the server, a
2364          * gateway_ports of 1 (``yes'') will override the client's
2365          * specification and force a wildcard bind, whereas a value of 2
2366          * (``clientspecified'') will bind to whatever address the client
2367          * asked for.
2368          *
2369          * Special-case listen_addrs are:
2370          *
2371          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2372          * "" (empty string), "*"  -> wildcard v4/v6
2373          * "localhost"             -> loopback v4/v6
2374          */
2375         addr = NULL;
2376         if (listen_addr == NULL) {
2377                 /* No address specified: default to gateway_ports setting */
2378                 if (gateway_ports)
2379                         wildcard = 1;
2380         } else if (gateway_ports || is_client) {
2381                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2382                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2383                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2384                     (!is_client && gateway_ports == 1))
2385                         wildcard = 1;
2386                 else if (strcmp(listen_addr, "localhost") != 0)
2387                         addr = listen_addr;
2388         }
2389
2390         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2391             type, wildcard, (addr == NULL) ? "NULL" : addr);
2392
2393         /*
2394          * getaddrinfo returns a loopback address if the hostname is
2395          * set to NULL and hints.ai_flags is not AI_PASSIVE
2396          */
2397         memset(&hints, 0, sizeof(hints));
2398         hints.ai_family = IPv4or6;
2399         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2400         hints.ai_socktype = SOCK_STREAM;
2401         snprintf(strport, sizeof strport, "%d", listen_port);
2402         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2403                 if (addr == NULL) {
2404                         /* This really shouldn't happen */
2405                         packet_disconnect("getaddrinfo: fatal error: %s",
2406                             gai_strerror(r));
2407                 } else {
2408                         error("channel_setup_fwd_listener: "
2409                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2410                 }
2411                 return 0;
2412         }
2413
2414         for (ai = aitop; ai; ai = ai->ai_next) {
2415                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2416                         continue;
2417                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2418                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2419                         error("channel_setup_fwd_listener: getnameinfo failed");
2420                         continue;
2421                 }
2422                 /* Create a port to listen for the host. */
2423                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2424                 if (sock < 0) {
2425                         /* this is no error since kernel may not support ipv6 */
2426                         verbose("socket: %.100s", strerror(errno));
2427                         continue;
2428                 }
2429
2430                 channel_set_reuseaddr(sock);
2431
2432                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2433
2434                 /* Bind the socket to the address. */
2435                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2436                         /* address can be in use ipv6 address is already bound */
2437                         if (!ai->ai_next)
2438                                 error("bind: %.100s", strerror(errno));
2439                         else
2440                                 verbose("bind: %.100s", strerror(errno));
2441
2442                         close(sock);
2443                         continue;
2444                 }
2445                 /* Start listening for connections on the socket. */
2446                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2447                         error("listen: %.100s", strerror(errno));
2448                         close(sock);
2449                         continue;
2450                 }
2451                 /* Allocate a channel number for the socket. */
2452                 c = channel_new("port listener", type, sock, sock, -1,
2453                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2454                     0, "port listener", 1);
2455                 strlcpy(c->path, host, sizeof(c->path));
2456                 c->host_port = port_to_connect;
2457                 c->listening_port = listen_port;
2458                 success = 1;
2459         }
2460         if (success == 0)
2461                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2462                     listen_port);
2463         freeaddrinfo(aitop);
2464         return success;
2465 }
2466
2467 int
2468 channel_cancel_rport_listener(const char *host, u_short port)
2469 {
2470         u_int i;
2471         int found = 0;
2472
2473         for (i = 0; i < channels_alloc; i++) {
2474                 Channel *c = channels[i];
2475
2476                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2477                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2478                     c->listening_port == port) {
2479                         debug2("%s: close channel %d", __func__, i);
2480                         channel_free(c);
2481                         found = 1;
2482                 }
2483         }
2484
2485         return (found);
2486 }
2487
2488 /* protocol local port fwd, used by ssh (and sshd in v1) */
2489 int
2490 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2491     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2492 {
2493         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2494             listen_host, listen_port, host_to_connect, port_to_connect,
2495             gateway_ports);
2496 }
2497
2498 /* protocol v2 remote port fwd, used by sshd */
2499 int
2500 channel_setup_remote_fwd_listener(const char *listen_address,
2501     u_short listen_port, int gateway_ports)
2502 {
2503         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2504             listen_address, listen_port, NULL, 0, gateway_ports);
2505 }
2506
2507 /*
2508  * Initiate forwarding of connections to port "port" on remote host through
2509  * the secure channel to host:port from local side.
2510  */
2511
2512 int
2513 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2514     const char *host_to_connect, u_short port_to_connect)
2515 {
2516         int type, success = 0;
2517
2518         /* Record locally that connection to this host/port is permitted. */
2519         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2520                 fatal("channel_request_remote_forwarding: too many forwards");
2521
2522         /* Send the forward request to the remote side. */
2523         if (compat20) {
2524                 const char *address_to_bind;
2525                 if (listen_host == NULL)
2526                         address_to_bind = "localhost";
2527                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2528                         address_to_bind = "";
2529                 else
2530                         address_to_bind = listen_host;
2531
2532                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2533                 packet_put_cstring("tcpip-forward");
2534                 packet_put_char(1);                     /* boolean: want reply */
2535                 packet_put_cstring(address_to_bind);
2536                 packet_put_int(listen_port);
2537                 packet_send();
2538                 packet_write_wait();
2539                 /* Assume that server accepts the request */
2540                 success = 1;
2541         } else {
2542                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2543                 packet_put_int(listen_port);
2544                 packet_put_cstring(host_to_connect);
2545                 packet_put_int(port_to_connect);
2546                 packet_send();
2547                 packet_write_wait();
2548
2549                 /* Wait for response from the remote side. */
2550                 type = packet_read();
2551                 switch (type) {
2552                 case SSH_SMSG_SUCCESS:
2553                         success = 1;
2554                         break;
2555                 case SSH_SMSG_FAILURE:
2556                         break;
2557                 default:
2558                         /* Unknown packet */
2559                         packet_disconnect("Protocol error for port forward request:"
2560                             "received packet type %d.", type);
2561                 }
2562         }
2563         if (success) {
2564                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2565                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2566                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2567                 num_permitted_opens++;
2568         }
2569         return (success ? 0 : -1);
2570 }
2571
2572 /*
2573  * Request cancellation of remote forwarding of connection host:port from
2574  * local side.
2575  */
2576 void
2577 channel_request_rforward_cancel(const char *host, u_short port)
2578 {
2579         int i;
2580
2581         if (!compat20)
2582                 return;
2583
2584         for (i = 0; i < num_permitted_opens; i++) {
2585                 if (permitted_opens[i].host_to_connect != NULL &&
2586                     permitted_opens[i].listen_port == port)
2587                         break;
2588         }
2589         if (i >= num_permitted_opens) {
2590                 debug("%s: requested forward not found", __func__);
2591                 return;
2592         }
2593         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2594         packet_put_cstring("cancel-tcpip-forward");
2595         packet_put_char(0);
2596         packet_put_cstring(host == NULL ? "" : host);
2597         packet_put_int(port);
2598         packet_send();
2599
2600         permitted_opens[i].listen_port = 0;
2601         permitted_opens[i].port_to_connect = 0;
2602         xfree(permitted_opens[i].host_to_connect);
2603         permitted_opens[i].host_to_connect = NULL;
2604 }
2605
2606 /*
2607  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2608  * listening for the port, and sends back a success reply (or disconnect
2609  * message if there was an error).
2610  */
2611 int
2612 channel_input_port_forward_request(int is_root, int gateway_ports)
2613 {
2614         u_short port, host_port;
2615         int success = 0;
2616         char *hostname;
2617
2618         /* Get arguments from the packet. */
2619         port = packet_get_int();
2620         hostname = packet_get_string(NULL);
2621         host_port = packet_get_int();
2622
2623 #ifndef HAVE_CYGWIN
2624         /*
2625          * Check that an unprivileged user is not trying to forward a
2626          * privileged port.
2627          */
2628         if (port < IPPORT_RESERVED && !is_root)
2629                 packet_disconnect(
2630                     "Requested forwarding of port %d but user is not root.",
2631                     port);
2632         if (host_port == 0)
2633                 packet_disconnect("Dynamic forwarding denied.");
2634 #endif
2635
2636         /* Initiate forwarding */
2637         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2638             host_port, gateway_ports);
2639
2640         /* Free the argument string. */
2641         xfree(hostname);
2642
2643         return (success ? 0 : -1);
2644 }
2645
2646 /*
2647  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2648  * usually called by the server, because the user could connect to any port
2649  * anyway, and the server has no way to know but to trust the client anyway.
2650  */
2651 void
2652 channel_permit_all_opens(void)
2653 {
2654         if (num_permitted_opens == 0)
2655                 all_opens_permitted = 1;
2656 }
2657
2658 void
2659 channel_add_permitted_opens(char *host, int port)
2660 {
2661         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2662                 fatal("channel_add_permitted_opens: too many forwards");
2663         debug("allow port forwarding to host %s port %d", host, port);
2664
2665         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2666         permitted_opens[num_permitted_opens].port_to_connect = port;
2667         num_permitted_opens++;
2668
2669         all_opens_permitted = 0;
2670 }
2671
2672 int
2673 channel_add_adm_permitted_opens(char *host, int port)
2674 {
2675         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2676                 fatal("channel_add_adm_permitted_opens: too many forwards");
2677         debug("config allows port forwarding to host %s port %d", host, port);
2678
2679         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2680              = xstrdup(host);
2681         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2682         return ++num_adm_permitted_opens;
2683 }
2684
2685 void
2686 channel_clear_permitted_opens(void)
2687 {
2688         int i;
2689
2690         for (i = 0; i < num_permitted_opens; i++)
2691                 if (permitted_opens[i].host_to_connect != NULL)
2692                         xfree(permitted_opens[i].host_to_connect);
2693         num_permitted_opens = 0;
2694 }
2695
2696 void
2697 channel_clear_adm_permitted_opens(void)
2698 {
2699         int i;
2700
2701         for (i = 0; i < num_adm_permitted_opens; i++)
2702                 if (permitted_adm_opens[i].host_to_connect != NULL)
2703                         xfree(permitted_adm_opens[i].host_to_connect);
2704         num_adm_permitted_opens = 0;
2705 }
2706
2707 /* return socket to remote host, port */
2708 static int
2709 connect_to(const char *host, u_short port)
2710 {
2711         struct addrinfo hints, *ai, *aitop;
2712         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2713         int gaierr;
2714         int sock = -1;
2715
2716         memset(&hints, 0, sizeof(hints));
2717         hints.ai_family = IPv4or6;
2718         hints.ai_socktype = SOCK_STREAM;
2719         snprintf(strport, sizeof strport, "%d", port);
2720         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2721                 error("connect_to %.100s: unknown host (%s)", host,
2722                     gai_strerror(gaierr));
2723                 return -1;
2724         }
2725         for (ai = aitop; ai; ai = ai->ai_next) {
2726                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2727                         continue;
2728                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2729                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2730                         error("connect_to: getnameinfo failed");
2731                         continue;
2732                 }
2733                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2734                 if (sock < 0) {
2735                         if (ai->ai_next == NULL)
2736                                 error("socket: %.100s", strerror(errno));
2737                         else
2738                                 verbose("socket: %.100s", strerror(errno));
2739                         continue;
2740                 }
2741                 if (set_nonblock(sock) == -1)
2742                         fatal("%s: set_nonblock(%d)", __func__, sock);
2743                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2744                     errno != EINPROGRESS) {
2745                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2746                             strerror(errno));
2747                         close(sock);
2748                         continue;       /* fail -- try next */
2749                 }
2750                 break; /* success */
2751
2752         }
2753         freeaddrinfo(aitop);
2754         if (!ai) {
2755                 error("connect_to %.100s port %d: failed.", host, port);
2756                 return -1;
2757         }
2758         /* success */
2759         set_nodelay(sock);
2760         return sock;
2761 }
2762
2763 int
2764 channel_connect_by_listen_address(u_short listen_port)
2765 {
2766         int i;
2767
2768         for (i = 0; i < num_permitted_opens; i++)
2769                 if (permitted_opens[i].host_to_connect != NULL &&
2770                     permitted_opens[i].listen_port == listen_port)
2771                         return connect_to(
2772                             permitted_opens[i].host_to_connect,
2773                             permitted_opens[i].port_to_connect);
2774         error("WARNING: Server requests forwarding for unknown listen_port %d",
2775             listen_port);
2776         return -1;
2777 }
2778
2779 /* Check if connecting to that port is permitted and connect. */
2780 int
2781 channel_connect_to(const char *host, u_short port)
2782 {
2783         int i, permit, permit_adm = 1;
2784
2785         permit = all_opens_permitted;
2786         if (!permit) {
2787                 for (i = 0; i < num_permitted_opens; i++)
2788                         if (permitted_opens[i].host_to_connect != NULL &&
2789                             permitted_opens[i].port_to_connect == port &&
2790                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2791                                 permit = 1;
2792         }
2793
2794         if (num_adm_permitted_opens > 0) {
2795                 permit_adm = 0;
2796                 for (i = 0; i < num_adm_permitted_opens; i++)
2797                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2798                             permitted_adm_opens[i].port_to_connect == port &&
2799                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2800                             == 0)
2801                                 permit_adm = 1;
2802         }
2803
2804         if (!permit || !permit_adm) {
2805                 logit("Received request to connect to host %.100s port %d, "
2806                     "but the request was denied.", host, port);
2807                 return -1;
2808         }
2809         return connect_to(host, port);
2810 }
2811
2812 void
2813 channel_send_window_changes(void)
2814 {
2815         u_int i;
2816         struct winsize ws;
2817
2818         for (i = 0; i < channels_alloc; i++) {
2819                 if (channels[i] == NULL || !channels[i]->client_tty ||
2820                     channels[i]->type != SSH_CHANNEL_OPEN)
2821                         continue;
2822                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2823                         continue;
2824                 channel_request_start(i, "window-change", 0);
2825                 packet_put_int((u_int)ws.ws_col);
2826                 packet_put_int((u_int)ws.ws_row);
2827                 packet_put_int((u_int)ws.ws_xpixel);
2828                 packet_put_int((u_int)ws.ws_ypixel);
2829                 packet_send();
2830         }
2831 }
2832
2833 /* -- X11 forwarding */
2834
2835 /*
2836  * Creates an internet domain socket for listening for X11 connections.
2837  * Returns 0 and a suitable display number for the DISPLAY variable
2838  * stored in display_numberp , or -1 if an error occurs.
2839  */
2840 int
2841 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2842     int single_connection, u_int *display_numberp, int **chanids)
2843 {
2844         Channel *nc = NULL;
2845         int display_number, sock;
2846         u_short port;
2847         struct addrinfo hints, *ai, *aitop;
2848         char strport[NI_MAXSERV];
2849         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2850
2851         if (chanids == NULL)
2852                 return -1;
2853
2854         for (display_number = x11_display_offset;
2855             display_number < MAX_DISPLAYS;
2856             display_number++) {
2857                 port = 6000 + display_number;
2858                 memset(&hints, 0, sizeof(hints));
2859                 hints.ai_family = IPv4or6;
2860                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2861                 hints.ai_socktype = SOCK_STREAM;
2862                 snprintf(strport, sizeof strport, "%d", port);
2863                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2864                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2865                         return -1;
2866                 }
2867                 for (ai = aitop; ai; ai = ai->ai_next) {
2868                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2869                                 continue;
2870                         sock = socket(ai->ai_family, ai->ai_socktype,
2871                             ai->ai_protocol);
2872                         if (sock < 0) {
2873                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2874                                         error("socket: %.100s", strerror(errno));
2875                                         freeaddrinfo(aitop);
2876                                         return -1;
2877                                 } else {
2878                                         debug("x11_create_display_inet: Socket family %d not supported",
2879                                                  ai->ai_family);
2880                                         continue;
2881                                 }
2882                         }
2883 #ifdef IPV6_V6ONLY
2884                         if (ai->ai_family == AF_INET6) {
2885                                 int on = 1;
2886                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2887                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2888                         }
2889 #endif
2890                         channel_set_reuseaddr(sock);
2891                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2892                                 debug2("bind port %d: %.100s", port, strerror(errno));
2893                                 close(sock);
2894
2895                                 if (ai->ai_next)
2896                                         continue;
2897
2898                                 for (n = 0; n < num_socks; n++) {
2899                                         close(socks[n]);
2900                                 }
2901                                 num_socks = 0;
2902                                 break;
2903                         }
2904                         socks[num_socks++] = sock;
2905 #ifndef DONT_TRY_OTHER_AF
2906                         if (num_socks == NUM_SOCKS)
2907                                 break;
2908 #else
2909                         if (x11_use_localhost) {
2910                                 if (num_socks == NUM_SOCKS)
2911                                         break;
2912                         } else {
2913                                 break;
2914                         }
2915 #endif
2916                 }
2917                 freeaddrinfo(aitop);
2918                 if (num_socks > 0)
2919                         break;
2920         }
2921         if (display_number >= MAX_DISPLAYS) {
2922                 error("Failed to allocate internet-domain X11 display socket.");
2923                 return -1;
2924         }
2925         /* Start listening for connections on the socket. */
2926         for (n = 0; n < num_socks; n++) {
2927                 sock = socks[n];
2928                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2929                         error("listen: %.100s", strerror(errno));
2930                         close(sock);
2931                         return -1;
2932                 }
2933         }
2934
2935         /* Allocate a channel for each socket. */
2936         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2937         for (n = 0; n < num_socks; n++) {
2938                 sock = socks[n];
2939                 nc = channel_new("x11 listener",
2940                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2941                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2942                     0, "X11 inet listener", 1);
2943                 nc->single_connection = single_connection;
2944                 (*chanids)[n] = nc->self;
2945         }
2946         (*chanids)[n] = -1;
2947
2948         /* Return the display number for the DISPLAY environment variable. */
2949         *display_numberp = display_number;
2950         return (0);
2951 }
2952
2953 static int
2954 connect_local_xsocket(u_int dnr)
2955 {
2956         int sock;
2957         struct sockaddr_un addr;
2958
2959         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2960         if (sock < 0)
2961                 error("socket: %.100s", strerror(errno));
2962         memset(&addr, 0, sizeof(addr));
2963         addr.sun_family = AF_UNIX;
2964         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2965         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
2966                 return sock;
2967         close(sock);
2968         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2969         return -1;
2970 }
2971
2972 int
2973 x11_connect_display(void)
2974 {
2975         u_int display_number;
2976         const char *display;
2977         char buf[1024], *cp;
2978         struct addrinfo hints, *ai, *aitop;
2979         char strport[NI_MAXSERV];
2980         int gaierr, sock = 0;
2981
2982         /* Try to open a socket for the local X server. */
2983         display = getenv("DISPLAY");
2984         if (!display) {
2985                 error("DISPLAY not set.");
2986                 return -1;
2987         }
2988         /*
2989          * Now we decode the value of the DISPLAY variable and make a
2990          * connection to the real X server.
2991          */
2992
2993         /*
2994          * Check if it is a unix domain socket.  Unix domain displays are in
2995          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2996          */
2997         if (strncmp(display, "unix:", 5) == 0 ||
2998             display[0] == ':') {
2999                 /* Connect to the unix domain socket. */
3000                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3001                         error("Could not parse display number from DISPLAY: %.100s",
3002                             display);
3003                         return -1;
3004                 }
3005                 /* Create a socket. */
3006                 sock = connect_local_xsocket(display_number);
3007                 if (sock < 0)
3008                         return -1;
3009
3010                 /* OK, we now have a connection to the display. */
3011                 return sock;
3012         }
3013         /*
3014          * Connect to an inet socket.  The DISPLAY value is supposedly
3015          * hostname:d[.s], where hostname may also be numeric IP address.
3016          */
3017         strlcpy(buf, display, sizeof(buf));
3018         cp = strchr(buf, ':');
3019         if (!cp) {
3020                 error("Could not find ':' in DISPLAY: %.100s", display);
3021                 return -1;
3022         }
3023         *cp = 0;
3024         /* buf now contains the host name.  But first we parse the display number. */
3025         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3026                 error("Could not parse display number from DISPLAY: %.100s",
3027                     display);
3028                 return -1;
3029         }
3030
3031         /* Look up the host address */
3032         memset(&hints, 0, sizeof(hints));
3033         hints.ai_family = IPv4or6;
3034         hints.ai_socktype = SOCK_STREAM;
3035         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3036         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3037                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
3038                 return -1;
3039         }
3040         for (ai = aitop; ai; ai = ai->ai_next) {
3041                 /* Create a socket. */
3042                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3043                 if (sock < 0) {
3044                         debug2("socket: %.100s", strerror(errno));
3045                         continue;
3046                 }
3047                 /* Connect it to the display. */
3048                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3049                         debug2("connect %.100s port %u: %.100s", buf,
3050                             6000 + display_number, strerror(errno));
3051                         close(sock);
3052                         continue;
3053                 }
3054                 /* Success */
3055                 break;
3056         }
3057         freeaddrinfo(aitop);
3058         if (!ai) {
3059                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3060                     strerror(errno));
3061                 return -1;
3062         }
3063         set_nodelay(sock);
3064         return sock;
3065 }
3066
3067 /*
3068  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3069  * the remote channel number.  We should do whatever we want, and respond
3070  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3071  */
3072
3073 /* ARGSUSED */
3074 void
3075 x11_input_open(int type, u_int32_t seq, void *ctxt)
3076 {
3077         Channel *c = NULL;
3078         int remote_id, sock = 0;
3079         char *remote_host;
3080
3081         debug("Received X11 open request.");
3082
3083         remote_id = packet_get_int();
3084
3085         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3086                 remote_host = packet_get_string(NULL);
3087         } else {
3088                 remote_host = xstrdup("unknown (remote did not supply name)");
3089         }
3090         packet_check_eom();
3091
3092         /* Obtain a connection to the real X display. */
3093         sock = x11_connect_display();
3094         if (sock != -1) {
3095                 /* Allocate a channel for this connection. */
3096                 c = channel_new("connected x11 socket",
3097                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3098                     remote_host, 1);
3099                 c->remote_id = remote_id;
3100                 c->force_drain = 1;
3101         }
3102         xfree(remote_host);
3103         if (c == NULL) {
3104                 /* Send refusal to the remote host. */
3105                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3106                 packet_put_int(remote_id);
3107         } else {
3108                 /* Send a confirmation to the remote host. */
3109                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3110                 packet_put_int(remote_id);
3111                 packet_put_int(c->self);
3112         }
3113         packet_send();
3114 }
3115
3116 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3117 /* ARGSUSED */
3118 void
3119 deny_input_open(int type, u_int32_t seq, void *ctxt)
3120 {
3121         int rchan = packet_get_int();
3122
3123         switch (type) {
3124         case SSH_SMSG_AGENT_OPEN:
3125                 error("Warning: ssh server tried agent forwarding.");
3126                 break;
3127         case SSH_SMSG_X11_OPEN:
3128                 error("Warning: ssh server tried X11 forwarding.");
3129                 break;
3130         default:
3131                 error("deny_input_open: type %d", type);
3132                 break;
3133         }
3134         error("Warning: this is probably a break-in attempt by a malicious server.");
3135         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3136         packet_put_int(rchan);
3137         packet_send();
3138 }
3139
3140 /*
3141  * Requests forwarding of X11 connections, generates fake authentication
3142  * data, and enables authentication spoofing.
3143  * This should be called in the client only.
3144  */
3145 void
3146 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3147     const char *proto, const char *data)
3148 {
3149         u_int data_len = (u_int) strlen(data) / 2;
3150         u_int i, value;
3151         char *new_data;
3152         int screen_number;
3153         const char *cp;
3154         u_int32_t rnd = 0;
3155
3156         if (x11_saved_display == NULL)
3157                 x11_saved_display = xstrdup(disp);
3158         else if (strcmp(disp, x11_saved_display) != 0) {
3159                 error("x11_request_forwarding_with_spoofing: different "
3160                     "$DISPLAY already forwarded");
3161                 return;
3162         }
3163
3164         cp = disp;
3165         if (disp)
3166                 cp = strchr(disp, ':');
3167         if (cp)
3168                 cp = strchr(cp, '.');
3169         if (cp)
3170                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3171         else
3172                 screen_number = 0;
3173
3174         if (x11_saved_proto == NULL) {
3175                 /* Save protocol name. */
3176                 x11_saved_proto = xstrdup(proto);
3177                 /*
3178                  * Extract real authentication data and generate fake data
3179                  * of the same length.
3180                  */
3181                 x11_saved_data = xmalloc(data_len);
3182                 x11_fake_data = xmalloc(data_len);
3183                 for (i = 0; i < data_len; i++) {
3184                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3185                                 fatal("x11_request_forwarding: bad "
3186                                     "authentication data: %.100s", data);
3187                         if (i % 4 == 0)
3188                                 rnd = arc4random();
3189                         x11_saved_data[i] = value;
3190                         x11_fake_data[i] = rnd & 0xff;
3191                         rnd >>= 8;
3192                 }
3193                 x11_saved_data_len = data_len;
3194                 x11_fake_data_len = data_len;
3195         }
3196
3197         /* Convert the fake data into hex. */
3198         new_data = tohex(x11_fake_data, data_len);
3199
3200         /* Send the request packet. */
3201         if (compat20) {
3202                 channel_request_start(client_session_id, "x11-req", 0);
3203                 packet_put_char(0);     /* XXX bool single connection */
3204         } else {
3205                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3206         }
3207         packet_put_cstring(proto);
3208         packet_put_cstring(new_data);
3209         packet_put_int(screen_number);
3210         packet_send();
3211         packet_write_wait();
3212         xfree(new_data);
3213 }
3214
3215
3216 /* -- agent forwarding */
3217
3218 /* Sends a message to the server to request authentication fd forwarding. */
3219
3220 void
3221 auth_request_forwarding(void)
3222 {
3223         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3224         packet_send();
3225         packet_write_wait();
3226 }