crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.331 2014/02/26 20:29:29 djm 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 __RCSID("$FreeBSD$");
  44
  45 #include <sys/types.h>
  46 #include <sys/ioctl.h>
  47 #include <sys/un.h>
  48 #include <sys/socket.h>
  49 #ifdef HAVE_SYS_TIME_H
  50 # include <sys/time.h>
  51 #endif
  52
  53 #include <netinet/in.h>
  54 #include <arpa/inet.h>
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <termios.h>
  63 #include <unistd.h>
  64 #include <stdarg.h>
  65
  66 #include "openbsd-compat/sys-queue.h"
  67 #include "xmalloc.h"
  68 #include "ssh.h"
  69 #include "ssh1.h"
  70 #include "ssh2.h"
  71 #include "packet.h"
  72 #include "log.h"
  73 #include "misc.h"
  74 #include "buffer.h"
  75 #include "channels.h"
  76 #include "compat.h"
  77 #include "canohost.h"
  78 #include "key.h"
  79 #include "authfd.h"
  80 #include "pathnames.h"
  81
  82 /* -- channel core */
  83
  84 /*
  85  * Pointer to an array containing all allocated channels.  The array is
  86  * dynamically extended as needed.
  87  */
  88 static Channel **channels = NULL;
  89
  90 /*
  91  * Size of the channel array.  All slots of the array must always be
  92  * initialized (at least the type field); unused slots set to NULL
  93  */
  94 static u_int channels_alloc = 0;
  95
  96 /*
  97  * Maximum file descriptor value used in any of the channels.  This is
  98  * updated in channel_new.
  99  */
 100 static int channel_max_fd = 0;
 101
 102
 103 /* -- tcp forwarding */
 104
 105 /*
 106  * Data structure for storing which hosts are permitted for forward requests.
 107  * The local sides of any remote forwards are stored in this array to prevent
 108  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 109  * network (which might be behind a firewall).
 110  */
 111 typedef struct {
 112         char *host_to_connect;          /* Connect to 'host'. */
 113         u_short port_to_connect;        /* Connect to 'port'. */
 114         u_short listen_port;            /* Remote side should listen port number. */
 115 } ForwardPermission;
 116
 117 /* List of all permitted host/port pairs to connect by the user. */
 118 static ForwardPermission *permitted_opens = NULL;
 119
 120 /* List of all permitted host/port pairs to connect by the admin. */
 121 static ForwardPermission *permitted_adm_opens = NULL;
 122
 123 /* Number of permitted host/port pairs in the array permitted by the user. */
 124 static int num_permitted_opens = 0;
 125
 126 /* Number of permitted host/port pair in the array permitted by the admin. */
 127 static int num_adm_permitted_opens = 0;
 128
 129 /* special-case port number meaning allow any port */
 130 #define FWD_PERMIT_ANY_PORT     0
 131
 132 /*
 133  * If this is true, all opens are permitted.  This is the case on the server
 134  * on which we have to trust the client anyway, and the user could do
 135  * anything after logging in anyway.
 136  */
 137 static int all_opens_permitted = 0;
 138
 139
 140 /* -- X11 forwarding */
 141
 142 /* Maximum number of fake X11 displays to try. */
 143 #define MAX_DISPLAYS  1000
 144
 145 /* Saved X11 local (client) display. */
 146 static char *x11_saved_display = NULL;
 147
 148 /* Saved X11 authentication protocol name. */
 149 static char *x11_saved_proto = NULL;
 150
 151 /* Saved X11 authentication data.  This is the real data. */
 152 static char *x11_saved_data = NULL;
 153 static u_int x11_saved_data_len = 0;
 154
 155 /*
 156  * Fake X11 authentication data.  This is what the server will be sending us;
 157  * we should replace any occurrences of this by the real data.
 158  */
 159 static u_char *x11_fake_data = NULL;
 160 static u_int x11_fake_data_len;
 161
 162
 163 /* -- agent forwarding */
 164
 165 #define NUM_SOCKS       10
 166
 167 /* AF_UNSPEC or AF_INET or AF_INET6 */
 168 static int IPv4or6 = AF_UNSPEC;
 169
 170 /* helper */
 171 static void port_open_helper(Channel *c, char *rtype);
 172
 173 /* non-blocking connect helpers */
 174 static int connect_next(struct channel_connect *);
 175 static void channel_connect_ctx_free(struct channel_connect *);
 176
 177 /* -- channel core */
 178
 179 Channel *
 180 channel_by_id(int id)
 181 {
 182         Channel *c;
 183
 184         if (id < 0 || (u_int)id >= channels_alloc) {
 185                 logit("channel_by_id: %d: bad id", id);
 186                 return NULL;
 187         }
 188         c = channels[id];
 189         if (c == NULL) {
 190                 logit("channel_by_id: %d: bad id: channel free", id);
 191                 return NULL;
 192         }
 193         return c;
 194 }
 195
 196 /*
 197  * Returns the channel if it is allowed to receive protocol messages.
 198  * Private channels, like listening sockets, may not receive messages.
 199  */
 200 Channel *
 201 channel_lookup(int id)
 202 {
 203         Channel *c;
 204
 205         if ((c = channel_by_id(id)) == NULL)
 206                 return (NULL);
 207
 208         switch (c->type) {
 209         case SSH_CHANNEL_X11_OPEN:
 210         case SSH_CHANNEL_LARVAL:
 211         case SSH_CHANNEL_CONNECTING:
 212         case SSH_CHANNEL_DYNAMIC:
 213         case SSH_CHANNEL_OPENING:
 214         case SSH_CHANNEL_OPEN:
 215         case SSH_CHANNEL_INPUT_DRAINING:
 216         case SSH_CHANNEL_OUTPUT_DRAINING:
 217         case SSH_CHANNEL_ABANDONED:
 218                 return (c);
 219         }
 220         logit("Non-public channel %d, type %d.", id, c->type);
 221         return (NULL);
 222 }
 223
 224 /*
 225  * Register filedescriptors for a channel, used when allocating a channel or
 226  * when the channel consumer/producer is ready, e.g. shell exec'd
 227  */
 228 static void
 229 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 230     int extusage, int nonblock, int is_tty)
 231 {
 232         /* Update the maximum file descriptor value. */
 233         channel_max_fd = MAX(channel_max_fd, rfd);
 234         channel_max_fd = MAX(channel_max_fd, wfd);
 235         channel_max_fd = MAX(channel_max_fd, efd);
 236
 237         if (rfd != -1)
 238                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 239         if (wfd != -1 && wfd != rfd)
 240                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 241         if (efd != -1 && efd != rfd && efd != wfd)
 242                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 243
 244         c->rfd = rfd;
 245         c->wfd = wfd;
 246         c->sock = (rfd == wfd) ? rfd : -1;
 247         c->efd = efd;
 248         c->extended_usage = extusage;
 249
 250         if ((c->isatty = is_tty) != 0)
 251                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 252 #ifdef _AIX
 253         /* XXX: Later AIX versions can't push as much data to tty */
 254         c->wfd_isatty = is_tty || isatty(c->wfd);
 255 #endif
 256
 257         /* enable nonblocking mode */
 258         if (nonblock) {
 259                 if (rfd != -1)
 260                         set_nonblock(rfd);
 261                 if (wfd != -1)
 262                         set_nonblock(wfd);
 263                 if (efd != -1)
 264                         set_nonblock(efd);
 265         }
 266 }
 267
 268 /*
 269  * Allocate a new channel object and set its type and socket. This will cause
 270  * remote_name to be freed.
 271  */
 272 Channel *
 273 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 274     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 275 {
 276         int found;
 277         u_int i;
 278         Channel *c;
 279
 280         /* Do initial allocation if this is the first call. */
 281         if (channels_alloc == 0) {
 282                 channels_alloc = 10;
 283                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 284                 for (i = 0; i < channels_alloc; i++)
 285                         channels[i] = NULL;
 286         }
 287         /* Try to find a free slot where to put the new channel. */
 288         for (found = -1, i = 0; i < channels_alloc; i++)
 289                 if (channels[i] == NULL) {
 290                         /* Found a free slot. */
 291                         found = (int)i;
 292                         break;
 293                 }
 294         if (found < 0) {
 295                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 296                 found = channels_alloc;
 297                 if (channels_alloc > 10000)
 298                         fatal("channel_new: internal error: channels_alloc %d "
 299                             "too big.", channels_alloc);
 300                 channels = xrealloc(channels, channels_alloc + 10,
 301                     sizeof(Channel *));
 302                 channels_alloc += 10;
 303                 debug2("channel: expanding %d", channels_alloc);
 304                 for (i = found; i < channels_alloc; i++)
 305                         channels[i] = NULL;
 306         }
 307         /* Initialize and return new channel. */
 308         c = channels[found] = xcalloc(1, sizeof(Channel));
 309         buffer_init(&c->input);
 310         buffer_init(&c->output);
 311         buffer_init(&c->extended);
 312         c->path = NULL;
 313         c->listening_addr = NULL;
 314         c->listening_port = 0;
 315         c->ostate = CHAN_OUTPUT_OPEN;
 316         c->istate = CHAN_INPUT_OPEN;
 317         c->flags = 0;
 318         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 319         c->notbefore = 0;
 320         c->self = found;
 321         c->type = type;
 322         c->ctype = ctype;
 323         c->local_window = window;
 324         c->local_window_max = window;
 325         c->local_consumed = 0;
 326         c->local_maxpacket = maxpack;
 327         c->remote_id = -1;
 328         c->remote_name = xstrdup(remote_name);
 329         c->remote_window = 0;
 330         c->remote_maxpacket = 0;
 331         c->force_drain = 0;
 332         c->single_connection = 0;
 333         c->detach_user = NULL;
 334         c->detach_close = 0;
 335         c->open_confirm = NULL;
 336         c->open_confirm_ctx = NULL;
 337         c->input_filter = NULL;
 338         c->output_filter = NULL;
 339         c->filter_ctx = NULL;
 340         c->filter_cleanup = NULL;
 341         c->ctl_chan = -1;
 342         c->mux_rcb = NULL;
 343         c->mux_ctx = NULL;
 344         c->mux_pause = 0;
 345         c->delayed = 1;         /* prevent call to channel_post handler */
 346         TAILQ_INIT(&c->status_confirms);
 347         debug("channel %d: new [%s]", found, remote_name);
 348         return c;
 349 }
 350
 351 static int
 352 channel_find_maxfd(void)
 353 {
 354         u_int i;
 355         int max = 0;
 356         Channel *c;
 357
 358         for (i = 0; i < channels_alloc; i++) {
 359                 c = channels[i];
 360                 if (c != NULL) {
 361                         max = MAX(max, c->rfd);
 362                         max = MAX(max, c->wfd);
 363                         max = MAX(max, c->efd);
 364                 }
 365         }
 366         return max;
 367 }
 368
 369 int
 370 channel_close_fd(int *fdp)
 371 {
 372         int ret = 0, fd = *fdp;
 373
 374         if (fd != -1) {
 375                 ret = close(fd);
 376                 *fdp = -1;
 377                 if (fd == channel_max_fd)
 378                         channel_max_fd = channel_find_maxfd();
 379         }
 380         return ret;
 381 }
 382
 383 /* Close all channel fd/socket. */
 384 static void
 385 channel_close_fds(Channel *c)
 386 {
 387         channel_close_fd(&c->sock);
 388         channel_close_fd(&c->rfd);
 389         channel_close_fd(&c->wfd);
 390         channel_close_fd(&c->efd);
 391 }
 392
 393 /* Free the channel and close its fd/socket. */
 394 void
 395 channel_free(Channel *c)
 396 {
 397         char *s;
 398         u_int i, n;
 399         struct channel_confirm *cc;
 400
 401         for (n = 0, i = 0; i < channels_alloc; i++)
 402                 if (channels[i])
 403                         n++;
 404         debug("channel %d: free: %s, nchannels %u", c->self,
 405             c->remote_name ? c->remote_name : "???", n);
 406
 407         s = channel_open_message();
 408         debug3("channel %d: status: %s", c->self, s);
 409         free(s);
 410
 411         if (c->sock != -1)
 412                 shutdown(c->sock, SHUT_RDWR);
 413         channel_close_fds(c);
 414         buffer_free(&c->input);
 415         buffer_free(&c->output);
 416         buffer_free(&c->extended);
 417         free(c->remote_name);
 418         c->remote_name = NULL;
 419         free(c->path);
 420         c->path = NULL;
 421         free(c->listening_addr);
 422         c->listening_addr = NULL;
 423         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 424                 if (cc->abandon_cb != NULL)
 425                         cc->abandon_cb(c, cc->ctx);
 426                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 427                 explicit_bzero(cc, sizeof(*cc));
 428                 free(cc);
 429         }
 430         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 431                 c->filter_cleanup(c->self, c->filter_ctx);
 432         channels[c->self] = NULL;
 433         free(c);
 434 }
 435
 436 void
 437 channel_free_all(void)
 438 {
 439         u_int i;
 440
 441         for (i = 0; i < channels_alloc; i++)
 442                 if (channels[i] != NULL)
 443                         channel_free(channels[i]);
 444 }
 445
 446 /*
 447  * Closes the sockets/fds of all channels.  This is used to close extra file
 448  * descriptors after a fork.
 449  */
 450 void
 451 channel_close_all(void)
 452 {
 453         u_int i;
 454
 455         for (i = 0; i < channels_alloc; i++)
 456                 if (channels[i] != NULL)
 457                         channel_close_fds(channels[i]);
 458 }
 459
 460 /*
 461  * Stop listening to channels.
 462  */
 463 void
 464 channel_stop_listening(void)
 465 {
 466         u_int i;
 467         Channel *c;
 468
 469         for (i = 0; i < channels_alloc; i++) {
 470                 c = channels[i];
 471                 if (c != NULL) {
 472                         switch (c->type) {
 473                         case SSH_CHANNEL_AUTH_SOCKET:
 474                         case SSH_CHANNEL_PORT_LISTENER:
 475                         case SSH_CHANNEL_RPORT_LISTENER:
 476                         case SSH_CHANNEL_X11_LISTENER:
 477                                 channel_close_fd(&c->sock);
 478                                 channel_free(c);
 479                                 break;
 480                         }
 481                 }
 482         }
 483 }
 484
 485 /*
 486  * Returns true if no channel has too much buffered data, and false if one or
 487  * more channel is overfull.
 488  */
 489 int
 490 channel_not_very_much_buffered_data(void)
 491 {
 492         u_int i;
 493         Channel *c;
 494
 495         for (i = 0; i < channels_alloc; i++) {
 496                 c = channels[i];
 497                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 498 #if 0
 499                         if (!compat20 &&
 500                             buffer_len(&c->input) > packet_get_maxsize()) {
 501                                 debug2("channel %d: big input buffer %d",
 502                                     c->self, buffer_len(&c->input));
 503                                 return 0;
 504                         }
 505 #endif
 506                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 507                                 debug2("channel %d: big output buffer %u > %u",
 508                                     c->self, buffer_len(&c->output),
 509                                     packet_get_maxsize());
 510                                 return 0;
 511                         }
 512                 }
 513         }
 514         return 1;
 515 }
 516
 517 /* Returns true if any channel is still open. */
 518 int
 519 channel_still_open(void)
 520 {
 521         u_int i;
 522         Channel *c;
 523
 524         for (i = 0; i < channels_alloc; i++) {
 525                 c = channels[i];
 526                 if (c == NULL)
 527                         continue;
 528                 switch (c->type) {
 529                 case SSH_CHANNEL_X11_LISTENER:
 530                 case SSH_CHANNEL_PORT_LISTENER:
 531                 case SSH_CHANNEL_RPORT_LISTENER:
 532                 case SSH_CHANNEL_MUX_LISTENER:
 533                 case SSH_CHANNEL_CLOSED:
 534                 case SSH_CHANNEL_AUTH_SOCKET:
 535                 case SSH_CHANNEL_DYNAMIC:
 536                 case SSH_CHANNEL_CONNECTING:
 537                 case SSH_CHANNEL_ZOMBIE:
 538                 case SSH_CHANNEL_ABANDONED:
 539                         continue;
 540                 case SSH_CHANNEL_LARVAL:
 541                         if (!compat20)
 542                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 543                         continue;
 544                 case SSH_CHANNEL_OPENING:
 545                 case SSH_CHANNEL_OPEN:
 546                 case SSH_CHANNEL_X11_OPEN:
 547                 case SSH_CHANNEL_MUX_CLIENT:
 548                         return 1;
 549                 case SSH_CHANNEL_INPUT_DRAINING:
 550                 case SSH_CHANNEL_OUTPUT_DRAINING:
 551                         if (!compat13)
 552                                 fatal("cannot happen: OUT_DRAIN");
 553                         return 1;
 554                 default:
 555                         fatal("channel_still_open: bad channel type %d", c->type);
 556                         /* NOTREACHED */
 557                 }
 558         }
 559         return 0;
 560 }
 561
 562 /* Returns the id of an open channel suitable for keepaliving */
 563 int
 564 channel_find_open(void)
 565 {
 566         u_int i;
 567         Channel *c;
 568
 569         for (i = 0; i < channels_alloc; i++) {
 570                 c = channels[i];
 571                 if (c == NULL || c->remote_id < 0)
 572                         continue;
 573                 switch (c->type) {
 574                 case SSH_CHANNEL_CLOSED:
 575                 case SSH_CHANNEL_DYNAMIC:
 576                 case SSH_CHANNEL_X11_LISTENER:
 577                 case SSH_CHANNEL_PORT_LISTENER:
 578                 case SSH_CHANNEL_RPORT_LISTENER:
 579                 case SSH_CHANNEL_MUX_LISTENER:
 580                 case SSH_CHANNEL_MUX_CLIENT:
 581                 case SSH_CHANNEL_OPENING:
 582                 case SSH_CHANNEL_CONNECTING:
 583                 case SSH_CHANNEL_ZOMBIE:
 584                 case SSH_CHANNEL_ABANDONED:
 585                         continue;
 586                 case SSH_CHANNEL_LARVAL:
 587                 case SSH_CHANNEL_AUTH_SOCKET:
 588                 case SSH_CHANNEL_OPEN:
 589                 case SSH_CHANNEL_X11_OPEN:
 590                         return i;
 591                 case SSH_CHANNEL_INPUT_DRAINING:
 592                 case SSH_CHANNEL_OUTPUT_DRAINING:
 593                         if (!compat13)
 594                                 fatal("cannot happen: OUT_DRAIN");
 595                         return i;
 596                 default:
 597                         fatal("channel_find_open: bad channel type %d", c->type);
 598                         /* NOTREACHED */
 599                 }
 600         }
 601         return -1;
 602 }
 603
 604
 605 /*
 606  * Returns a message describing the currently open forwarded connections,
 607  * suitable for sending to the client.  The message contains crlf pairs for
 608  * newlines.
 609  */
 610 char *
 611 channel_open_message(void)
 612 {
 613         Buffer buffer;
 614         Channel *c;
 615         char buf[1024], *cp;
 616         u_int i;
 617
 618         buffer_init(&buffer);
 619         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 620         buffer_append(&buffer, buf, strlen(buf));
 621         for (i = 0; i < channels_alloc; i++) {
 622                 c = channels[i];
 623                 if (c == NULL)
 624                         continue;
 625                 switch (c->type) {
 626                 case SSH_CHANNEL_X11_LISTENER:
 627                 case SSH_CHANNEL_PORT_LISTENER:
 628                 case SSH_CHANNEL_RPORT_LISTENER:
 629                 case SSH_CHANNEL_CLOSED:
 630                 case SSH_CHANNEL_AUTH_SOCKET:
 631                 case SSH_CHANNEL_ZOMBIE:
 632                 case SSH_CHANNEL_ABANDONED:
 633                 case SSH_CHANNEL_MUX_CLIENT:
 634                 case SSH_CHANNEL_MUX_LISTENER:
 635                         continue;
 636                 case SSH_CHANNEL_LARVAL:
 637                 case SSH_CHANNEL_OPENING:
 638                 case SSH_CHANNEL_CONNECTING:
 639                 case SSH_CHANNEL_DYNAMIC:
 640                 case SSH_CHANNEL_OPEN:
 641                 case SSH_CHANNEL_X11_OPEN:
 642                 case SSH_CHANNEL_INPUT_DRAINING:
 643                 case SSH_CHANNEL_OUTPUT_DRAINING:
 644                         snprintf(buf, sizeof buf,
 645                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cc %d)\r\n",
 646                             c->self, c->remote_name,
 647                             c->type, c->remote_id,
 648                             c->istate, buffer_len(&c->input),
 649                             c->ostate, buffer_len(&c->output),
 650                             c->rfd, c->wfd, c->ctl_chan);
 651                         buffer_append(&buffer, buf, strlen(buf));
 652                         continue;
 653                 default:
 654                         fatal("channel_open_message: bad channel type %d", c->type);
 655                         /* NOTREACHED */
 656                 }
 657         }
 658         buffer_append(&buffer, "\0", 1);
 659         cp = xstrdup(buffer_ptr(&buffer));
 660         buffer_free(&buffer);
 661         return cp;
 662 }
 663
 664 void
 665 channel_send_open(int id)
 666 {
 667         Channel *c = channel_lookup(id);
 668
 669         if (c == NULL) {
 670                 logit("channel_send_open: %d: bad id", id);
 671                 return;
 672         }
 673         debug2("channel %d: send open", id);
 674         packet_start(SSH2_MSG_CHANNEL_OPEN);
 675         packet_put_cstring(c->ctype);
 676         packet_put_int(c->self);
 677         packet_put_int(c->local_window);
 678         packet_put_int(c->local_maxpacket);
 679         packet_send();
 680 }
 681
 682 void
 683 channel_request_start(int id, char *service, int wantconfirm)
 684 {
 685         Channel *c = channel_lookup(id);
 686
 687         if (c == NULL) {
 688                 logit("channel_request_start: %d: unknown channel id", id);
 689                 return;
 690         }
 691         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 692         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 693         packet_put_int(c->remote_id);
 694         packet_put_cstring(service);
 695         packet_put_char(wantconfirm);
 696 }
 697
 698 void
 699 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 700     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 701 {
 702         struct channel_confirm *cc;
 703         Channel *c;
 704
 705         if ((c = channel_lookup(id)) == NULL)
 706                 fatal("channel_register_expect: %d: bad id", id);
 707
 708         cc = xcalloc(1, sizeof(*cc));
 709         cc->cb = cb;
 710         cc->abandon_cb = abandon_cb;
 711         cc->ctx = ctx;
 712         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 713 }
 714
 715 void
 716 channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
 717 {
 718         Channel *c = channel_lookup(id);
 719
 720         if (c == NULL) {
 721                 logit("channel_register_open_confirm: %d: bad id", id);
 722                 return;
 723         }
 724         c->open_confirm = fn;
 725         c->open_confirm_ctx = ctx;
 726 }
 727
 728 void
 729 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 730 {
 731         Channel *c = channel_by_id(id);
 732
 733         if (c == NULL) {
 734                 logit("channel_register_cleanup: %d: bad id", id);
 735                 return;
 736         }
 737         c->detach_user = fn;
 738         c->detach_close = do_close;
 739 }
 740
 741 void
 742 channel_cancel_cleanup(int id)
 743 {
 744         Channel *c = channel_by_id(id);
 745
 746         if (c == NULL) {
 747                 logit("channel_cancel_cleanup: %d: bad id", id);
 748                 return;
 749         }
 750         c->detach_user = NULL;
 751         c->detach_close = 0;
 752 }
 753
 754 void
 755 channel_register_filter(int id, channel_infilter_fn *ifn,
 756     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 757 {
 758         Channel *c = channel_lookup(id);
 759
 760         if (c == NULL) {
 761                 logit("channel_register_filter: %d: bad id", id);
 762                 return;
 763         }
 764         c->input_filter = ifn;
 765         c->output_filter = ofn;
 766         c->filter_ctx = ctx;
 767         c->filter_cleanup = cfn;
 768 }
 769
 770 void
 771 channel_set_fds(int id, int rfd, int wfd, int efd,
 772     int extusage, int nonblock, int is_tty, u_int window_max)
 773 {
 774         Channel *c = channel_lookup(id);
 775
 776         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 777                 fatal("channel_activate for non-larval channel %d.", id);
 778         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 779         c->type = SSH_CHANNEL_OPEN;
 780         c->local_window = c->local_window_max = window_max;
 781         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 782         packet_put_int(c->remote_id);
 783         packet_put_int(c->local_window);
 784         packet_send();
 785 }
 786
 787 /*
 788  * 'channel_pre*' are called just before select() to add any bits relevant to
 789  * channels in the select bitmasks.
 790  */
 791 /*
 792  * 'channel_post*': perform any appropriate operations for channels which
 793  * have events pending.
 794  */
 795 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 796 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 797 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 798
 799 /* ARGSUSED */
 800 static void
 801 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 802 {
 803         FD_SET(c->sock, readset);
 804 }
 805
 806 /* ARGSUSED */
 807 static void
 808 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 809 {
 810         debug3("channel %d: waiting for connection", c->self);
 811         FD_SET(c->sock, writeset);
 812 }
 813
 814 static void
 815 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 816 {
 817         if (buffer_len(&c->input) < packet_get_maxsize())
 818                 FD_SET(c->sock, readset);
 819         if (buffer_len(&c->output) > 0)
 820                 FD_SET(c->sock, writeset);
 821 }
 822
 823 static void
 824 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 825 {
 826         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 827
 828         if (c->istate == CHAN_INPUT_OPEN &&
 829             limit > 0 &&
 830             buffer_len(&c->input) < limit &&
 831             buffer_check_alloc(&c->input, CHAN_RBUF))
 832                 FD_SET(c->rfd, readset);
 833         if (c->ostate == CHAN_OUTPUT_OPEN ||
 834             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 835                 if (buffer_len(&c->output) > 0) {
 836                         FD_SET(c->wfd, writeset);
 837                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 838                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 839                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 840                                     c->self, c->efd, buffer_len(&c->extended));
 841                         else
 842                                 chan_obuf_empty(c);
 843                 }
 844         }
 845         /** XXX check close conditions, too */
 846         if (compat20 && c->efd != -1 &&
 847             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 848                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 849                     buffer_len(&c->extended) > 0)
 850                         FD_SET(c->efd, writeset);
 851                 else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
 852                     (c->extended_usage == CHAN_EXTENDED_READ ||
 853                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
 854                     buffer_len(&c->extended) < c->remote_window)
 855                         FD_SET(c->efd, readset);
 856         }
 857         /* XXX: What about efd? races? */
 858 }
 859
 860 /* ARGSUSED */
 861 static void
 862 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 863 {
 864         if (buffer_len(&c->input) == 0) {
 865                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 866                 packet_put_int(c->remote_id);
 867                 packet_send();
 868                 c->type = SSH_CHANNEL_CLOSED;
 869                 debug2("channel %d: closing after input drain.", c->self);
 870         }
 871 }
 872
 873 /* ARGSUSED */
 874 static void
 875 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 876 {
 877         if (buffer_len(&c->output) == 0)
 878                 chan_mark_dead(c);
 879         else
 880                 FD_SET(c->sock, writeset);
 881 }
 882
 883 /*
 884  * This is a special state for X11 authentication spoofing.  An opened X11
 885  * connection (when authentication spoofing is being done) remains in this
 886  * state until the first packet has been completely read.  The authentication
 887  * data in that packet is then substituted by the real data if it matches the
 888  * fake data, and the channel is put into normal mode.
 889  * XXX All this happens at the client side.
 890  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 891  */
 892 static int
 893 x11_open_helper(Buffer *b)
 894 {
 895         u_char *ucp;
 896         u_int proto_len, data_len;
 897
 898         /* Check if the fixed size part of the packet is in buffer. */
 899         if (buffer_len(b) < 12)
 900                 return 0;
 901
 902         /* Parse the lengths of variable-length fields. */
 903         ucp = buffer_ptr(b);
 904         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 905                 proto_len = 256 * ucp[6] + ucp[7];
 906                 data_len = 256 * ucp[8] + ucp[9];
 907         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 908                 proto_len = ucp[6] + 256 * ucp[7];
 909                 data_len = ucp[8] + 256 * ucp[9];
 910         } else {
 911                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 912                     ucp[0]);
 913                 return -1;
 914         }
 915
 916         /* Check if the whole packet is in buffer. */
 917         if (buffer_len(b) <
 918             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 919                 return 0;
 920
 921         /* Check if authentication protocol matches. */
 922         if (proto_len != strlen(x11_saved_proto) ||
 923             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 924                 debug2("X11 connection uses different authentication protocol.");
 925                 return -1;
 926         }
 927         /* Check if authentication data matches our fake data. */
 928         if (data_len != x11_fake_data_len ||
 929             timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
 930                 x11_fake_data, x11_fake_data_len) != 0) {
 931                 debug2("X11 auth data does not match fake data.");
 932                 return -1;
 933         }
 934         /* Check fake data length */
 935         if (x11_fake_data_len != x11_saved_data_len) {
 936                 error("X11 fake_data_len %d != saved_data_len %d",
 937                     x11_fake_data_len, x11_saved_data_len);
 938                 return -1;
 939         }
 940         /*
 941          * Received authentication protocol and data match
 942          * our fake data. Substitute the fake data with real
 943          * data.
 944          */
 945         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 946             x11_saved_data, x11_saved_data_len);
 947         return 1;
 948 }
 949
 950 static void
 951 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 952 {
 953         int ret = x11_open_helper(&c->output);
 954
 955         if (ret == 1) {
 956                 /* Start normal processing for the channel. */
 957                 c->type = SSH_CHANNEL_OPEN;
 958                 channel_pre_open_13(c, readset, writeset);
 959         } else if (ret == -1) {
 960                 /*
 961                  * We have received an X11 connection that has bad
 962                  * authentication information.
 963                  */
 964                 logit("X11 connection rejected because of wrong authentication.");
 965                 buffer_clear(&c->input);
 966                 buffer_clear(&c->output);
 967                 channel_close_fd(&c->sock);
 968                 c->sock = -1;
 969                 c->type = SSH_CHANNEL_CLOSED;
 970                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 971                 packet_put_int(c->remote_id);
 972                 packet_send();
 973         }
 974 }
 975
 976 static void
 977 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 978 {
 979         int ret = x11_open_helper(&c->output);
 980
 981         /* c->force_drain = 1; */
 982
 983         if (ret == 1) {
 984                 c->type = SSH_CHANNEL_OPEN;
 985                 channel_pre_open(c, readset, writeset);
 986         } else if (ret == -1) {
 987                 logit("X11 connection rejected because of wrong authentication.");
 988                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 989                 chan_read_failed(c);
 990                 buffer_clear(&c->input);
 991                 chan_ibuf_empty(c);
 992                 buffer_clear(&c->output);
 993                 /* for proto v1, the peer will send an IEOF */
 994                 if (compat20)
 995                         chan_write_failed(c);
 996                 else
 997                         c->type = SSH_CHANNEL_OPEN;
 998                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 999         }
1000 }
1001
1002 static void
1003 channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1004 {
1005         if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
1006             buffer_check_alloc(&c->input, CHAN_RBUF))
1007                 FD_SET(c->rfd, readset);
1008         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1009                 /* clear buffer immediately (discard any partial packet) */
1010                 buffer_clear(&c->input);
1011                 chan_ibuf_empty(c);
1012                 /* Start output drain. XXX just kill chan? */
1013                 chan_rcvd_oclose(c);
1014         }
1015         if (c->ostate == CHAN_OUTPUT_OPEN ||
1016             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
1017                 if (buffer_len(&c->output) > 0)
1018                         FD_SET(c->wfd, writeset);
1019                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
1020                         chan_obuf_empty(c);
1021         }
1022 }
1023
1024 /* try to decode a socks4 header */
1025 /* ARGSUSED */
1026 static int
1027 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1028 {
1029         char *p, *host;
1030         u_int len, have, i, found, need;
1031         char username[256];
1032         struct {
1033                 u_int8_t version;
1034                 u_int8_t command;
1035                 u_int16_t dest_port;
1036                 struct in_addr dest_addr;
1037         } s4_req, s4_rsp;
1038
1039         debug2("channel %d: decode socks4", c->self);
1040
1041         have = buffer_len(&c->input);
1042         len = sizeof(s4_req);
1043         if (have < len)
1044                 return 0;
1045         p = buffer_ptr(&c->input);
1046
1047         need = 1;
1048         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1049         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1050                 debug2("channel %d: socks4a request", c->self);
1051                 /* ... and needs an extra string (the hostname) */
1052                 need = 2;
1053         }
1054         /* Check for terminating NUL on the string(s) */
1055         for (found = 0, i = len; i < have; i++) {
1056                 if (p[i] == '\0') {
1057                         found++;
1058                         if (found == need)
1059                                 break;
1060                 }
1061                 if (i > 1024) {
1062                         /* the peer is probably sending garbage */
1063                         debug("channel %d: decode socks4: too long",
1064                             c->self);
1065                         return -1;
1066                 }
1067         }
1068         if (found < need)
1069                 return 0;
1070         buffer_get(&c->input, (char *)&s4_req.version, 1);
1071         buffer_get(&c->input, (char *)&s4_req.command, 1);
1072         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1073         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1074         have = buffer_len(&c->input);
1075         p = buffer_ptr(&c->input);
1076         if (memchr(p, '\0', have) == NULL)
1077                 fatal("channel %d: decode socks4: user not nul terminated",
1078                     c->self);
1079         len = strlen(p);
1080         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1081         len++;                                  /* trailing '\0' */
1082         if (len > have)
1083                 fatal("channel %d: decode socks4: len %d > have %d",
1084                     c->self, len, have);
1085         strlcpy(username, p, sizeof(username));
1086         buffer_consume(&c->input, len);
1087
1088         free(c->path);
1089         c->path = NULL;
1090         if (need == 1) {                        /* SOCKS4: one string */
1091                 host = inet_ntoa(s4_req.dest_addr);
1092                 c->path = xstrdup(host);
1093         } else {                                /* SOCKS4A: two strings */
1094                 have = buffer_len(&c->input);
1095                 p = buffer_ptr(&c->input);
1096                 len = strlen(p);
1097                 debug2("channel %d: decode socks4a: host %s/%d",
1098                     c->self, p, len);
1099                 len++;                          /* trailing '\0' */
1100                 if (len > have)
1101                         fatal("channel %d: decode socks4a: len %d > have %d",
1102                             c->self, len, have);
1103                 if (len > NI_MAXHOST) {
1104                         error("channel %d: hostname \"%.100s\" too long",
1105                             c->self, p);
1106                         return -1;
1107                 }
1108                 c->path = xstrdup(p);
1109                 buffer_consume(&c->input, len);
1110         }
1111         c->host_port = ntohs(s4_req.dest_port);
1112
1113         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1114             c->self, c->path, c->host_port, s4_req.command);
1115
1116         if (s4_req.command != 1) {
1117                 debug("channel %d: cannot handle: %s cn %d",
1118                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1119                 return -1;
1120         }
1121         s4_rsp.version = 0;                     /* vn: 0 for reply */
1122         s4_rsp.command = 90;                    /* cd: req granted */
1123         s4_rsp.dest_port = 0;                   /* ignored */
1124         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1125         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1126         return 1;
1127 }
1128
1129 /* try to decode a socks5 header */
1130 #define SSH_SOCKS5_AUTHDONE     0x1000
1131 #define SSH_SOCKS5_NOAUTH       0x00
1132 #define SSH_SOCKS5_IPV4         0x01
1133 #define SSH_SOCKS5_DOMAIN       0x03
1134 #define SSH_SOCKS5_IPV6         0x04
1135 #define SSH_SOCKS5_CONNECT      0x01
1136 #define SSH_SOCKS5_SUCCESS      0x00
1137
1138 /* ARGSUSED */
1139 static int
1140 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1141 {
1142         struct {
1143                 u_int8_t version;
1144                 u_int8_t command;
1145                 u_int8_t reserved;
1146                 u_int8_t atyp;
1147         } s5_req, s5_rsp;
1148         u_int16_t dest_port;
1149         char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1150         u_char *p;
1151         u_int have, need, i, found, nmethods, addrlen, af;
1152
1153         debug2("channel %d: decode socks5", c->self);
1154         p = buffer_ptr(&c->input);
1155         if (p[0] != 0x05)
1156                 return -1;
1157         have = buffer_len(&c->input);
1158         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1159                 /* format: ver | nmethods | methods */
1160                 if (have < 2)
1161                         return 0;
1162                 nmethods = p[1];
1163                 if (have < nmethods + 2)
1164                         return 0;
1165                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1166                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1167                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1168                                 found = 1;
1169                                 break;
1170                         }
1171                 }
1172                 if (!found) {
1173                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1174                             c->self);
1175                         return -1;
1176                 }
1177                 buffer_consume(&c->input, nmethods + 2);
1178                 buffer_put_char(&c->output, 0x05);              /* version */
1179                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1180                 FD_SET(c->sock, writeset);
1181                 c->flags |= SSH_SOCKS5_AUTHDONE;
1182                 debug2("channel %d: socks5 auth done", c->self);
1183                 return 0;                               /* need more */
1184         }
1185         debug2("channel %d: socks5 post auth", c->self);
1186         if (have < sizeof(s5_req)+1)
1187                 return 0;                       /* need more */
1188         memcpy(&s5_req, p, sizeof(s5_req));
1189         if (s5_req.version != 0x05 ||
1190             s5_req.command != SSH_SOCKS5_CONNECT ||
1191             s5_req.reserved != 0x00) {
1192                 debug2("channel %d: only socks5 connect supported", c->self);
1193                 return -1;
1194         }
1195         switch (s5_req.atyp){
1196         case SSH_SOCKS5_IPV4:
1197                 addrlen = 4;
1198                 af = AF_INET;
1199                 break;
1200         case SSH_SOCKS5_DOMAIN:
1201                 addrlen = p[sizeof(s5_req)];
1202                 af = -1;
1203                 break;
1204         case SSH_SOCKS5_IPV6:
1205                 addrlen = 16;
1206                 af = AF_INET6;
1207                 break;
1208         default:
1209                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1210                 return -1;
1211         }
1212         need = sizeof(s5_req) + addrlen + 2;
1213         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1214                 need++;
1215         if (have < need)
1216                 return 0;
1217         buffer_consume(&c->input, sizeof(s5_req));
1218         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1219                 buffer_consume(&c->input, 1);    /* host string length */
1220         buffer_get(&c->input, &dest_addr, addrlen);
1221         buffer_get(&c->input, (char *)&dest_port, 2);
1222         dest_addr[addrlen] = '\0';
1223         free(c->path);
1224         c->path = NULL;
1225         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1226                 if (addrlen >= NI_MAXHOST) {
1227                         error("channel %d: dynamic request: socks5 hostname "
1228                             "\"%.100s\" too long", c->self, dest_addr);
1229                         return -1;
1230                 }
1231                 c->path = xstrdup(dest_addr);
1232         } else {
1233                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1234                         return -1;
1235                 c->path = xstrdup(ntop);
1236         }
1237         c->host_port = ntohs(dest_port);
1238
1239         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1240             c->self, c->path, c->host_port, s5_req.command);
1241
1242         s5_rsp.version = 0x05;
1243         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1244         s5_rsp.reserved = 0;                    /* ignored */
1245         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1246         dest_port = 0;                          /* ignored */
1247
1248         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1249         buffer_put_int(&c->output, ntohl(INADDR_ANY)); /* bind address */
1250         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1251         return 1;
1252 }
1253
1254 Channel *
1255 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1256     int in, int out)
1257 {
1258         Channel *c;
1259
1260         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1261             port_to_connect);
1262
1263         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1264             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1265             0, "stdio-forward", /*nonblock*/0);
1266
1267         c->path = xstrdup(host_to_connect);
1268         c->host_port = port_to_connect;
1269         c->listening_port = 0;
1270         c->force_drain = 1;
1271
1272         channel_register_fds(c, in, out, -1, 0, 1, 0);
1273         port_open_helper(c, "direct-tcpip");
1274
1275         return c;
1276 }
1277
1278 /* dynamic port forwarding */
1279 static void
1280 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1281 {
1282         u_char *p;
1283         u_int have;
1284         int ret;
1285
1286         have = buffer_len(&c->input);
1287         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1288         /* buffer_dump(&c->input); */
1289         /* check if the fixed size part of the packet is in buffer. */
1290         if (have < 3) {
1291                 /* need more */
1292                 FD_SET(c->sock, readset);
1293                 return;
1294         }
1295         /* try to guess the protocol */
1296         p = buffer_ptr(&c->input);
1297         switch (p[0]) {
1298         case 0x04:
1299                 ret = channel_decode_socks4(c, readset, writeset);
1300                 break;
1301         case 0x05:
1302                 ret = channel_decode_socks5(c, readset, writeset);
1303                 break;
1304         default:
1305                 ret = -1;
1306                 break;
1307         }
1308         if (ret < 0) {
1309                 chan_mark_dead(c);
1310         } else if (ret == 0) {
1311                 debug2("channel %d: pre_dynamic: need more", c->self);
1312                 /* need more */
1313                 FD_SET(c->sock, readset);
1314         } else {
1315                 /* switch to the next state */
1316                 c->type = SSH_CHANNEL_OPENING;
1317                 port_open_helper(c, "direct-tcpip");
1318         }
1319 }
1320
1321 /* This is our fake X11 server socket. */
1322 /* ARGSUSED */
1323 static void
1324 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1325 {
1326         Channel *nc;
1327         struct sockaddr_storage addr;
1328         int newsock, oerrno;
1329         socklen_t addrlen;
1330         char buf[16384], *remote_ipaddr;
1331         int remote_port;
1332
1333         if (FD_ISSET(c->sock, readset)) {
1334                 debug("X11 connection requested.");
1335                 addrlen = sizeof(addr);
1336                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1337                 if (c->single_connection) {
1338                         oerrno = errno;
1339                         debug2("single_connection: closing X11 listener.");
1340                         channel_close_fd(&c->sock);
1341                         chan_mark_dead(c);
1342                         errno = oerrno;
1343                 }
1344                 if (newsock < 0) {
1345                         if (errno != EINTR && errno != EWOULDBLOCK &&
1346                             errno != ECONNABORTED)
1347                                 error("accept: %.100s", strerror(errno));
1348                         if (errno == EMFILE || errno == ENFILE)
1349                                 c->notbefore = monotime() + 1;
1350                         return;
1351                 }
1352                 set_nodelay(newsock);
1353                 remote_ipaddr = get_peer_ipaddr(newsock);
1354                 remote_port = get_peer_port(newsock);
1355                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1356                     remote_ipaddr, remote_port);
1357
1358                 nc = channel_new("accepted x11 socket",
1359                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1360                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1361                 if (compat20) {
1362                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1363                         packet_put_cstring("x11");
1364                         packet_put_int(nc->self);
1365                         packet_put_int(nc->local_window_max);
1366                         packet_put_int(nc->local_maxpacket);
1367                         /* originator ipaddr and port */
1368                         packet_put_cstring(remote_ipaddr);
1369                         if (datafellows & SSH_BUG_X11FWD) {
1370                                 debug2("ssh2 x11 bug compat mode");
1371                         } else {
1372                                 packet_put_int(remote_port);
1373                         }
1374                         packet_send();
1375                 } else {
1376                         packet_start(SSH_SMSG_X11_OPEN);
1377                         packet_put_int(nc->self);
1378                         if (packet_get_protocol_flags() &
1379                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1380                                 packet_put_cstring(buf);
1381                         packet_send();
1382                 }
1383                 free(remote_ipaddr);
1384         }
1385 }
1386
1387 static void
1388 port_open_helper(Channel *c, char *rtype)
1389 {
1390         int direct;
1391         char buf[1024];
1392         char *local_ipaddr = get_local_ipaddr(c->sock);
1393         int local_port = c->sock == -1 ? 65536 : get_sock_port(c->sock, 1);
1394         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1395         int remote_port = get_peer_port(c->sock);
1396
1397         if (remote_port == -1) {
1398                 /* Fake addr/port to appease peers that validate it (Tectia) */
1399                 free(remote_ipaddr);
1400                 remote_ipaddr = xstrdup("127.0.0.1");
1401                 remote_port = 65535;
1402         }
1403
1404         direct = (strcmp(rtype, "direct-tcpip") == 0);
1405
1406         snprintf(buf, sizeof buf,
1407             "%s: listening port %d for %.100s port %d, "
1408             "connect from %.200s port %d to %.100s port %d",
1409             rtype, c->listening_port, c->path, c->host_port,
1410             remote_ipaddr, remote_port, local_ipaddr, local_port);
1411
1412         free(c->remote_name);
1413         c->remote_name = xstrdup(buf);
1414
1415         if (compat20) {
1416                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1417                 packet_put_cstring(rtype);
1418                 packet_put_int(c->self);
1419                 packet_put_int(c->local_window_max);
1420                 packet_put_int(c->local_maxpacket);
1421                 if (direct) {
1422                         /* target host, port */
1423                         packet_put_cstring(c->path);
1424                         packet_put_int(c->host_port);
1425                 } else {
1426                         /* listen address, port */
1427                         packet_put_cstring(c->path);
1428                         packet_put_int(local_port);
1429                 }
1430                 /* originator host and port */
1431                 packet_put_cstring(remote_ipaddr);
1432                 packet_put_int((u_int)remote_port);
1433                 packet_send();
1434         } else {
1435                 packet_start(SSH_MSG_PORT_OPEN);
1436                 packet_put_int(c->self);
1437                 packet_put_cstring(c->path);
1438                 packet_put_int(c->host_port);
1439                 if (packet_get_protocol_flags() &
1440                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1441                         packet_put_cstring(c->remote_name);
1442                 packet_send();
1443         }
1444         free(remote_ipaddr);
1445         free(local_ipaddr);
1446 }
1447
1448 static void
1449 channel_set_reuseaddr(int fd)
1450 {
1451         int on = 1;
1452
1453         /*
1454          * Set socket options.
1455          * Allow local port reuse in TIME_WAIT.
1456          */
1457         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1458                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1459 }
1460
1461 /*
1462  * This socket is listening for connections to a forwarded TCP/IP port.
1463  */
1464 /* ARGSUSED */
1465 static void
1466 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1467 {
1468         Channel *nc;
1469         struct sockaddr_storage addr;
1470         int newsock, nextstate;
1471         socklen_t addrlen;
1472         char *rtype;
1473
1474         if (FD_ISSET(c->sock, readset)) {
1475                 debug("Connection to port %d forwarding "
1476                     "to %.100s port %d requested.",
1477                     c->listening_port, c->path, c->host_port);
1478
1479                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1480                         nextstate = SSH_CHANNEL_OPENING;
1481                         rtype = "forwarded-tcpip";
1482                 } else {
1483                         if (c->host_port == 0) {
1484                                 nextstate = SSH_CHANNEL_DYNAMIC;
1485                                 rtype = "dynamic-tcpip";
1486                         } else {
1487                                 nextstate = SSH_CHANNEL_OPENING;
1488                                 rtype = "direct-tcpip";
1489                         }
1490                 }
1491
1492                 addrlen = sizeof(addr);
1493                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1494                 if (newsock < 0) {
1495                         if (errno != EINTR && errno != EWOULDBLOCK &&
1496                             errno != ECONNABORTED)
1497                                 error("accept: %.100s", strerror(errno));
1498                         if (errno == EMFILE || errno == ENFILE)
1499                                 c->notbefore = monotime() + 1;
1500                         return;
1501                 }
1502                 set_nodelay(newsock);
1503                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1504                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1505                 nc->listening_port = c->listening_port;
1506                 nc->host_port = c->host_port;
1507                 if (c->path != NULL)
1508                         nc->path = xstrdup(c->path);
1509
1510                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1511                         port_open_helper(nc, rtype);
1512         }
1513 }
1514
1515 /*
1516  * This is the authentication agent socket listening for connections from
1517  * clients.
1518  */
1519 /* ARGSUSED */
1520 static void
1521 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1522 {
1523         Channel *nc;
1524         int newsock;
1525         struct sockaddr_storage addr;
1526         socklen_t addrlen;
1527
1528         if (FD_ISSET(c->sock, readset)) {
1529                 addrlen = sizeof(addr);
1530                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1531                 if (newsock < 0) {
1532                         error("accept from auth socket: %.100s",
1533                             strerror(errno));
1534                         if (errno == EMFILE || errno == ENFILE)
1535                                 c->notbefore = monotime() + 1;
1536                         return;
1537                 }
1538                 nc = channel_new("accepted auth socket",
1539                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1540                     c->local_window_max, c->local_maxpacket,
1541                     0, "accepted auth socket", 1);
1542                 if (compat20) {
1543                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1544                         packet_put_cstring("auth-agent@openssh.com");
1545                         packet_put_int(nc->self);
1546                         packet_put_int(c->local_window_max);
1547                         packet_put_int(c->local_maxpacket);
1548                 } else {
1549                         packet_start(SSH_SMSG_AGENT_OPEN);
1550                         packet_put_int(nc->self);
1551                 }
1552                 packet_send();
1553         }
1554 }
1555
1556 /* ARGSUSED */
1557 static void
1558 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1559 {
1560         int err = 0, sock;
1561         socklen_t sz = sizeof(err);
1562
1563         if (FD_ISSET(c->sock, writeset)) {
1564                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1565                         err = errno;
1566                         error("getsockopt SO_ERROR failed");
1567                 }
1568                 if (err == 0) {
1569                         debug("channel %d: connected to %s port %d",
1570                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1571                         channel_connect_ctx_free(&c->connect_ctx);
1572                         c->type = SSH_CHANNEL_OPEN;
1573                         if (compat20) {
1574                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1575                                 packet_put_int(c->remote_id);
1576                                 packet_put_int(c->self);
1577                                 packet_put_int(c->local_window);
1578                                 packet_put_int(c->local_maxpacket);
1579                         } else {
1580                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1581                                 packet_put_int(c->remote_id);
1582                                 packet_put_int(c->self);
1583                         }
1584                 } else {
1585                         debug("channel %d: connection failed: %s",
1586                             c->self, strerror(err));
1587                         /* Try next address, if any */
1588                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1589                                 close(c->sock);
1590                                 c->sock = c->rfd = c->wfd = sock;
1591                                 channel_max_fd = channel_find_maxfd();
1592                                 return;
1593                         }
1594                         /* Exhausted all addresses */
1595                         error("connect_to %.100s port %d: failed.",
1596                             c->connect_ctx.host, c->connect_ctx.port);
1597                         channel_connect_ctx_free(&c->connect_ctx);
1598                         if (compat20) {
1599                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1600                                 packet_put_int(c->remote_id);
1601                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1602                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1603                                         packet_put_cstring(strerror(err));
1604                                         packet_put_cstring("");
1605                                 }
1606                         } else {
1607                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1608                                 packet_put_int(c->remote_id);
1609                         }
1610                         chan_mark_dead(c);
1611                 }
1612                 packet_send();
1613         }
1614 }
1615
1616 /* ARGSUSED */
1617 static int
1618 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1619 {
1620         char buf[CHAN_RBUF];
1621         int len, force;
1622
1623         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1624         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1625                 errno = 0;
1626                 len = read(c->rfd, buf, sizeof(buf));
1627                 if (len < 0 && (errno == EINTR ||
1628                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1629                         return 1;
1630 #ifndef PTY_ZEROREAD
1631                 if (len <= 0) {
1632 #else
1633                 if ((!c->isatty && len <= 0) ||
1634                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1635 #endif
1636                         debug2("channel %d: read<=0 rfd %d len %d",
1637                             c->self, c->rfd, len);
1638                         if (c->type != SSH_CHANNEL_OPEN) {
1639                                 debug2("channel %d: not open", c->self);
1640                                 chan_mark_dead(c);
1641                                 return -1;
1642                         } else if (compat13) {
1643                                 buffer_clear(&c->output);
1644                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1645                                 debug2("channel %d: input draining.", c->self);
1646                         } else {
1647                                 chan_read_failed(c);
1648                         }
1649                         return -1;
1650                 }
1651                 if (c->input_filter != NULL) {
1652                         if (c->input_filter(c, buf, len) == -1) {
1653                                 debug2("channel %d: filter stops", c->self);
1654                                 chan_read_failed(c);
1655                         }
1656                 } else if (c->datagram) {
1657                         buffer_put_string(&c->input, buf, len);
1658                 } else {
1659                         buffer_append(&c->input, buf, len);
1660                 }
1661         }
1662         return 1;
1663 }
1664
1665 /* ARGSUSED */
1666 static int
1667 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1668 {
1669         struct termios tio;
1670         u_char *data = NULL, *buf;
1671         u_int dlen, olen = 0;
1672         int len;
1673
1674         /* Send buffered output data to the socket. */
1675         if (c->wfd != -1 &&
1676             FD_ISSET(c->wfd, writeset) &&
1677             buffer_len(&c->output) > 0) {
1678                 olen = buffer_len(&c->output);
1679                 if (c->output_filter != NULL) {
1680                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1681                                 debug2("channel %d: filter stops", c->self);
1682                                 if (c->type != SSH_CHANNEL_OPEN)
1683                                         chan_mark_dead(c);
1684                                 else
1685                                         chan_write_failed(c);
1686                                 return -1;
1687                         }
1688                 } else if (c->datagram) {
1689                         buf = data = buffer_get_string(&c->output, &dlen);
1690                 } else {
1691                         buf = data = buffer_ptr(&c->output);
1692                         dlen = buffer_len(&c->output);
1693                 }
1694
1695                 if (c->datagram) {
1696                         /* ignore truncated writes, datagrams might get lost */
1697                         len = write(c->wfd, buf, dlen);
1698                         free(data);
1699                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1700                             errno == EWOULDBLOCK))
1701                                 return 1;
1702                         if (len <= 0) {
1703                                 if (c->type != SSH_CHANNEL_OPEN)
1704                                         chan_mark_dead(c);
1705                                 else
1706                                         chan_write_failed(c);
1707                                 return -1;
1708                         }
1709                         goto out;
1710                 }
1711 #ifdef _AIX
1712                 /* XXX: Later AIX versions can't push as much data to tty */
1713                 if (compat20 && c->wfd_isatty)
1714                         dlen = MIN(dlen, 8*1024);
1715 #endif
1716
1717                 len = write(c->wfd, buf, dlen);
1718                 if (len < 0 &&
1719                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1720                         return 1;
1721                 if (len <= 0) {
1722                         if (c->type != SSH_CHANNEL_OPEN) {
1723                                 debug2("channel %d: not open", c->self);
1724                                 chan_mark_dead(c);
1725                                 return -1;
1726                         } else if (compat13) {
1727                                 buffer_clear(&c->output);
1728                                 debug2("channel %d: input draining.", c->self);
1729                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1730                         } else {
1731                                 chan_write_failed(c);
1732                         }
1733                         return -1;
1734                 }
1735 #ifndef BROKEN_TCGETATTR_ICANON
1736                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1737                         if (tcgetattr(c->wfd, &tio) == 0 &&
1738                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1739                                 /*
1740                                  * Simulate echo to reduce the impact of
1741                                  * traffic analysis. We need to match the
1742                                  * size of a SSH2_MSG_CHANNEL_DATA message
1743                                  * (4 byte channel id + buf)
1744                                  */
1745                                 packet_send_ignore(4 + len);
1746                                 packet_send();
1747                         }
1748                 }
1749 #endif
1750                 buffer_consume(&c->output, len);
1751         }
1752  out:
1753         if (compat20 && olen > 0)
1754                 c->local_consumed += olen - buffer_len(&c->output);
1755         return 1;
1756 }
1757
1758 static int
1759 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1760 {
1761         char buf[CHAN_RBUF];
1762         int len;
1763
1764 /** XXX handle drain efd, too */
1765         if (c->efd != -1) {
1766                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1767                     FD_ISSET(c->efd, writeset) &&
1768                     buffer_len(&c->extended) > 0) {
1769                         len = write(c->efd, buffer_ptr(&c->extended),
1770                             buffer_len(&c->extended));
1771                         debug2("channel %d: written %d to efd %d",
1772                             c->self, len, c->efd);
1773                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1774                             errno == EWOULDBLOCK))
1775                                 return 1;
1776                         if (len <= 0) {
1777                                 debug2("channel %d: closing write-efd %d",
1778                                     c->self, c->efd);
1779                                 channel_close_fd(&c->efd);
1780                         } else {
1781                                 buffer_consume(&c->extended, len);
1782                                 c->local_consumed += len;
1783                         }
1784                 } else if (c->efd != -1 &&
1785                     (c->extended_usage == CHAN_EXTENDED_READ ||
1786                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
1787                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1788                         len = read(c->efd, buf, sizeof(buf));
1789                         debug2("channel %d: read %d from efd %d",
1790                             c->self, len, c->efd);
1791                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1792                             errno == EWOULDBLOCK) && !c->detach_close)))
1793                                 return 1;
1794                         if (len <= 0) {
1795                                 debug2("channel %d: closing read-efd %d",
1796                                     c->self, c->efd);
1797                                 channel_close_fd(&c->efd);
1798                         } else {
1799                                 if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
1800                                         debug3("channel %d: discard efd",
1801                                             c->self);
1802                                 } else
1803                                         buffer_append(&c->extended, buf, len);
1804                         }
1805                 }
1806         }
1807         return 1;
1808 }
1809
1810 static int
1811 channel_check_window(Channel *c)
1812 {
1813         if (c->type == SSH_CHANNEL_OPEN &&
1814             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1815             ((c->local_window_max - c->local_window >
1816             c->local_maxpacket*3) ||
1817             c->local_window < c->local_window_max/2) &&
1818             c->local_consumed > 0) {
1819                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1820                 packet_put_int(c->remote_id);
1821                 packet_put_int(c->local_consumed);
1822                 packet_send();
1823                 debug2("channel %d: window %d sent adjust %d",
1824                     c->self, c->local_window,
1825                     c->local_consumed);
1826                 c->local_window += c->local_consumed;
1827                 c->local_consumed = 0;
1828         }
1829         return 1;
1830 }
1831
1832 static void
1833 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1834 {
1835         channel_handle_rfd(c, readset, writeset);
1836         channel_handle_wfd(c, readset, writeset);
1837         if (!compat20)
1838                 return;
1839         channel_handle_efd(c, readset, writeset);
1840         channel_check_window(c);
1841 }
1842
1843 static u_int
1844 read_mux(Channel *c, u_int need)
1845 {
1846         char buf[CHAN_RBUF];
1847         int len;
1848         u_int rlen;
1849
1850         if (buffer_len(&c->input) < need) {
1851                 rlen = need - buffer_len(&c->input);
1852                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1853                 if (len <= 0) {
1854                         if (errno != EINTR && errno != EAGAIN) {
1855                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1856                                     c->self, c->rfd, len);
1857                                 chan_read_failed(c);
1858                                 return 0;
1859                         }
1860                 } else
1861                         buffer_append(&c->input, buf, len);
1862         }
1863         return buffer_len(&c->input);
1864 }
1865
1866 static void
1867 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1868 {
1869         u_int need;
1870         ssize_t len;
1871
1872         if (!compat20)
1873                 fatal("%s: entered with !compat20", __func__);
1874
1875         if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
1876             (c->istate == CHAN_INPUT_OPEN ||
1877             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1878                 /*
1879                  * Don't not read past the precise end of packets to
1880                  * avoid disrupting fd passing.
1881                  */
1882                 if (read_mux(c, 4) < 4) /* read header */
1883                         return;
1884                 need = get_u32(buffer_ptr(&c->input));
1885 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1886                 if (need > CHANNEL_MUX_MAX_PACKET) {
1887                         debug2("channel %d: packet too big %u > %u",
1888                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1889                         chan_rcvd_oclose(c);
1890                         return;
1891                 }
1892                 if (read_mux(c, need + 4) < need + 4) /* read body */
1893                         return;
1894                 if (c->mux_rcb(c) != 0) {
1895                         debug("channel %d: mux_rcb failed", c->self);
1896                         chan_mark_dead(c);
1897                         return;
1898                 }
1899         }
1900
1901         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1902             buffer_len(&c->output) > 0) {
1903                 len = write(c->wfd, buffer_ptr(&c->output),
1904                     buffer_len(&c->output));
1905                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1906                         return;
1907                 if (len <= 0) {
1908                         chan_mark_dead(c);
1909                         return;
1910                 }
1911                 buffer_consume(&c->output, len);
1912         }
1913 }
1914
1915 static void
1916 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1917 {
1918         Channel *nc;
1919         struct sockaddr_storage addr;
1920         socklen_t addrlen;
1921         int newsock;
1922         uid_t euid;
1923         gid_t egid;
1924
1925         if (!FD_ISSET(c->sock, readset))
1926                 return;
1927
1928         debug("multiplexing control connection");
1929
1930         /*
1931          * Accept connection on control socket
1932          */
1933         memset(&addr, 0, sizeof(addr));
1934         addrlen = sizeof(addr);
1935         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1936             &addrlen)) == -1) {
1937                 error("%s accept: %s", __func__, strerror(errno));
1938                 if (errno == EMFILE || errno == ENFILE)
1939                         c->notbefore = monotime() + 1;
1940                 return;
1941         }
1942
1943         if (getpeereid(newsock, &euid, &egid) < 0) {
1944                 error("%s getpeereid failed: %s", __func__,
1945                     strerror(errno));
1946                 close(newsock);
1947                 return;
1948         }
1949         if ((euid != 0) && (getuid() != euid)) {
1950                 error("multiplex uid mismatch: peer euid %u != uid %u",
1951                     (u_int)euid, (u_int)getuid());
1952                 close(newsock);
1953                 return;
1954         }
1955         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
1956             newsock, newsock, -1, c->local_window_max,
1957             c->local_maxpacket, 0, "mux-control", 1);
1958         nc->mux_rcb = c->mux_rcb;
1959         debug3("%s: new mux channel %d fd %d", __func__,
1960             nc->self, nc->sock);
1961         /* establish state */
1962         nc->mux_rcb(nc);
1963         /* mux state transitions must not elicit protocol messages */
1964         nc->flags |= CHAN_LOCAL;
1965 }
1966
1967 /* ARGSUSED */
1968 static void
1969 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1970 {
1971         int len;
1972
1973         /* Send buffered output data to the socket. */
1974         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1975                 len = write(c->sock, buffer_ptr(&c->output),
1976                             buffer_len(&c->output));
1977                 if (len <= 0)
1978                         buffer_clear(&c->output);
1979                 else
1980                         buffer_consume(&c->output, len);
1981         }
1982 }
1983
1984 static void
1985 channel_handler_init_20(void)
1986 {
1987         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1988         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1989         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1990         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1991         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1992         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1993         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1994         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1995         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
1996         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
1997
1998         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1999         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2000         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
2001         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2002         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2003         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2004         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2005         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
2006         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
2007 }
2008
2009 static void
2010 channel_handler_init_13(void)
2011 {
2012         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
2013         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
2014         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2015         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2016         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2017         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
2018         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
2019         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2020         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2021
2022         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2023         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2024         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2025         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2026         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
2027         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2028         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2029 }
2030
2031 static void
2032 channel_handler_init_15(void)
2033 {
2034         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2035         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2036         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2037         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2038         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2039         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2040         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2041
2042         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2043         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2044         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2045         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2046         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2047         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2048 }
2049
2050 static void
2051 channel_handler_init(void)
2052 {
2053         int i;
2054
2055         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2056                 channel_pre[i] = NULL;
2057                 channel_post[i] = NULL;
2058         }
2059         if (compat20)
2060                 channel_handler_init_20();
2061         else if (compat13)
2062                 channel_handler_init_13();
2063         else
2064                 channel_handler_init_15();
2065 }
2066
2067 /* gc dead channels */
2068 static void
2069 channel_garbage_collect(Channel *c)
2070 {
2071         if (c == NULL)
2072                 return;
2073         if (c->detach_user != NULL) {
2074                 if (!chan_is_dead(c, c->detach_close))
2075                         return;
2076                 debug2("channel %d: gc: notify user", c->self);
2077                 c->detach_user(c->self, NULL);
2078                 /* if we still have a callback */
2079                 if (c->detach_user != NULL)
2080                         return;
2081                 debug2("channel %d: gc: user detached", c->self);
2082         }
2083         if (!chan_is_dead(c, 1))
2084                 return;
2085         debug2("channel %d: garbage collecting", c->self);
2086         channel_free(c);
2087 }
2088
2089 static void
2090 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
2091     time_t *unpause_secs)
2092 {
2093         static int did_init = 0;
2094         u_int i, oalloc;
2095         Channel *c;
2096         time_t now;
2097
2098         if (!did_init) {
2099                 channel_handler_init();
2100                 did_init = 1;
2101         }
2102         now = monotime();
2103         if (unpause_secs != NULL)
2104                 *unpause_secs = 0;
2105         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2106                 c = channels[i];
2107                 if (c == NULL)
2108                         continue;
2109                 if (c->delayed) {
2110                         if (ftab == channel_pre)
2111                                 c->delayed = 0;
2112                         else
2113                                 continue;
2114                 }
2115                 if (ftab[c->type] != NULL) {
2116                         /*
2117                          * Run handlers that are not paused.
2118                          */
2119                         if (c->notbefore <= now)
2120                                 (*ftab[c->type])(c, readset, writeset);
2121                         else if (unpause_secs != NULL) {
2122                                 /*
2123                                  * Collect the time that the earliest
2124                                  * channel comes off pause.
2125                                  */
2126                                 debug3("%s: chan %d: skip for %d more seconds",
2127                                     __func__, c->self,
2128                                     (int)(c->notbefore - now));
2129                                 if (*unpause_secs == 0 ||
2130                                     (c->notbefore - now) < *unpause_secs)
2131                                         *unpause_secs = c->notbefore - now;
2132                         }
2133                 }
2134                 channel_garbage_collect(c);
2135         }
2136         if (unpause_secs != NULL && *unpause_secs != 0)
2137                 debug3("%s: first channel unpauses in %d seconds",
2138                     __func__, (int)*unpause_secs);
2139 }
2140
2141 /*
2142  * Allocate/update select bitmasks and add any bits relevant to channels in
2143  * select bitmasks.
2144  */
2145 void
2146 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2147     u_int *nallocp, time_t *minwait_secs, int rekeying)
2148 {
2149         u_int n, sz, nfdset;
2150
2151         n = MAX(*maxfdp, channel_max_fd);
2152
2153         nfdset = howmany(n+1, NFDBITS);
2154         /* Explicitly test here, because xrealloc isn't always called */
2155         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
2156                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2157         sz = nfdset * sizeof(fd_mask);
2158
2159         /* perhaps check sz < nalloc/2 and shrink? */
2160         if (*readsetp == NULL || sz > *nallocp) {
2161                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2162                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2163                 *nallocp = sz;
2164         }
2165         *maxfdp = n;
2166         memset(*readsetp, 0, sz);
2167         memset(*writesetp, 0, sz);
2168
2169         if (!rekeying)
2170                 channel_handler(channel_pre, *readsetp, *writesetp,
2171                     minwait_secs);
2172 }
2173
2174 /*
2175  * After select, perform any appropriate operations for channels which have
2176  * events pending.
2177  */
2178 void
2179 channel_after_select(fd_set *readset, fd_set *writeset)
2180 {
2181         channel_handler(channel_post, readset, writeset, NULL);
2182 }
2183
2184
2185 /* If there is data to send to the connection, enqueue some of it now. */
2186 void
2187 channel_output_poll(void)
2188 {
2189         Channel *c;
2190         u_int i, len;
2191
2192         for (i = 0; i < channels_alloc; i++) {
2193                 c = channels[i];
2194                 if (c == NULL)
2195                         continue;
2196
2197                 /*
2198                  * We are only interested in channels that can have buffered
2199                  * incoming data.
2200                  */
2201                 if (compat13) {
2202                         if (c->type != SSH_CHANNEL_OPEN &&
2203                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2204                                 continue;
2205                 } else {
2206                         if (c->type != SSH_CHANNEL_OPEN)
2207                                 continue;
2208                 }
2209                 if (compat20 &&
2210                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2211                         /* XXX is this true? */
2212                         debug3("channel %d: will not send data after close", c->self);
2213                         continue;
2214                 }
2215
2216                 /* Get the amount of buffered data for this channel. */
2217                 if ((c->istate == CHAN_INPUT_OPEN ||
2218                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2219                     (len = buffer_len(&c->input)) > 0) {
2220                         if (c->datagram) {
2221                                 if (len > 0) {
2222                                         u_char *data;
2223                                         u_int dlen;
2224
2225                                         data = buffer_get_string(&c->input,
2226                                             &dlen);
2227                                         if (dlen > c->remote_window ||
2228                                             dlen > c->remote_maxpacket) {
2229                                                 debug("channel %d: datagram "
2230                                                     "too big for channel",
2231                                                     c->self);
2232                                                 free(data);
2233                                                 continue;
2234                                         }
2235                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2236                                         packet_put_int(c->remote_id);
2237                                         packet_put_string(data, dlen);
2238                                         packet_send();
2239                                         c->remote_window -= dlen + 4;
2240                                         free(data);
2241                                 }
2242                                 continue;
2243                         }
2244                         /*
2245                          * Send some data for the other side over the secure
2246                          * connection.
2247                          */
2248                         if (compat20) {
2249                                 if (len > c->remote_window)
2250                                         len = c->remote_window;
2251                                 if (len > c->remote_maxpacket)
2252                                         len = c->remote_maxpacket;
2253                         } else {
2254                                 if (packet_is_interactive()) {
2255                                         if (len > 1024)
2256                                                 len = 512;
2257                                 } else {
2258                                         /* Keep the packets at reasonable size. */
2259                                         if (len > packet_get_maxsize()/2)
2260                                                 len = packet_get_maxsize()/2;
2261                                 }
2262                         }
2263                         if (len > 0) {
2264                                 packet_start(compat20 ?
2265                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2266                                 packet_put_int(c->remote_id);
2267                                 packet_put_string(buffer_ptr(&c->input), len);
2268                                 packet_send();
2269                                 buffer_consume(&c->input, len);
2270                                 c->remote_window -= len;
2271                         }
2272                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2273                         if (compat13)
2274                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2275                         /*
2276                          * input-buffer is empty and read-socket shutdown:
2277                          * tell peer, that we will not send more data: send IEOF.
2278                          * hack for extended data: delay EOF if EFD still in use.
2279                          */
2280                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2281                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2282                                     c->self, c->efd, buffer_len(&c->extended));
2283                         else
2284                                 chan_ibuf_empty(c);
2285                 }
2286                 /* Send extended data, i.e. stderr */
2287                 if (compat20 &&
2288                     !(c->flags & CHAN_EOF_SENT) &&
2289                     c->remote_window > 0 &&
2290                     (len = buffer_len(&c->extended)) > 0 &&
2291                     c->extended_usage == CHAN_EXTENDED_READ) {
2292                         debug2("channel %d: rwin %u elen %u euse %d",
2293                             c->self, c->remote_window, buffer_len(&c->extended),
2294                             c->extended_usage);
2295                         if (len > c->remote_window)
2296                                 len = c->remote_window;
2297                         if (len > c->remote_maxpacket)
2298                                 len = c->remote_maxpacket;
2299                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2300                         packet_put_int(c->remote_id);
2301                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2302                         packet_put_string(buffer_ptr(&c->extended), len);
2303                         packet_send();
2304                         buffer_consume(&c->extended, len);
2305                         c->remote_window -= len;
2306                         debug2("channel %d: sent ext data %d", c->self, len);
2307                 }
2308         }
2309 }
2310
2311
2312 /* -- protocol input */
2313
2314 /* ARGSUSED */
2315 void
2316 channel_input_data(int type, u_int32_t seq, void *ctxt)
2317 {
2318         int id;
2319         char *data;
2320         u_int data_len, win_len;
2321         Channel *c;
2322
2323         /* Get the channel number and verify it. */
2324         id = packet_get_int();
2325         c = channel_lookup(id);
2326         if (c == NULL)
2327                 packet_disconnect("Received data for nonexistent channel %d.", id);
2328
2329         /* Ignore any data for non-open channels (might happen on close) */
2330         if (c->type != SSH_CHANNEL_OPEN &&
2331             c->type != SSH_CHANNEL_X11_OPEN)
2332                 return;
2333
2334         /* Get the data. */
2335         data = packet_get_string_ptr(&data_len);
2336         win_len = data_len;
2337         if (c->datagram)
2338                 win_len += 4;  /* string length header */
2339
2340         /*
2341          * Ignore data for protocol > 1.3 if output end is no longer open.
2342          * For protocol 2 the sending side is reducing its window as it sends
2343          * data, so we must 'fake' consumption of the data in order to ensure
2344          * that window updates are sent back.  Otherwise the connection might
2345          * deadlock.
2346          */
2347         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2348                 if (compat20) {
2349                         c->local_window -= win_len;
2350                         c->local_consumed += win_len;
2351                 }
2352                 return;
2353         }
2354
2355         if (compat20) {
2356                 if (win_len > c->local_maxpacket) {
2357                         logit("channel %d: rcvd big packet %d, maxpack %d",
2358                             c->self, win_len, c->local_maxpacket);
2359                 }
2360                 if (win_len > c->local_window) {
2361                         logit("channel %d: rcvd too much data %d, win %d",
2362                             c->self, win_len, c->local_window);
2363                         return;
2364                 }
2365                 c->local_window -= win_len;
2366         }
2367         if (c->datagram)
2368                 buffer_put_string(&c->output, data, data_len);
2369         else
2370                 buffer_append(&c->output, data, data_len);
2371         packet_check_eom();
2372 }
2373
2374 /* ARGSUSED */
2375 void
2376 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2377 {
2378         int id;
2379         char *data;
2380         u_int data_len, tcode;
2381         Channel *c;
2382
2383         /* Get the channel number and verify it. */
2384         id = packet_get_int();
2385         c = channel_lookup(id);
2386
2387         if (c == NULL)
2388                 packet_disconnect("Received extended_data for bad channel %d.", id);
2389         if (c->type != SSH_CHANNEL_OPEN) {
2390                 logit("channel %d: ext data for non open", id);
2391                 return;
2392         }
2393         if (c->flags & CHAN_EOF_RCVD) {
2394                 if (datafellows & SSH_BUG_EXTEOF)
2395                         debug("channel %d: accepting ext data after eof", id);
2396                 else
2397                         packet_disconnect("Received extended_data after EOF "
2398                             "on channel %d.", id);
2399         }
2400         tcode = packet_get_int();
2401         if (c->efd == -1 ||
2402             c->extended_usage != CHAN_EXTENDED_WRITE ||
2403             tcode != SSH2_EXTENDED_DATA_STDERR) {
2404                 logit("channel %d: bad ext data", c->self);
2405                 return;
2406         }
2407         data = packet_get_string(&data_len);
2408         packet_check_eom();
2409         if (data_len > c->local_window) {
2410                 logit("channel %d: rcvd too much extended_data %d, win %d",
2411                     c->self, data_len, c->local_window);
2412                 free(data);
2413                 return;
2414         }
2415         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2416         c->local_window -= data_len;
2417         buffer_append(&c->extended, data, data_len);
2418         free(data);
2419 }
2420
2421 /* ARGSUSED */
2422 void
2423 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2424 {
2425         int id;
2426         Channel *c;
2427
2428         id = packet_get_int();
2429         packet_check_eom();
2430         c = channel_lookup(id);
2431         if (c == NULL)
2432                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2433         chan_rcvd_ieof(c);
2434
2435         /* XXX force input close */
2436         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2437                 debug("channel %d: FORCE input drain", c->self);
2438                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2439                 if (buffer_len(&c->input) == 0)
2440                         chan_ibuf_empty(c);
2441         }
2442
2443 }
2444
2445 /* ARGSUSED */
2446 void
2447 channel_input_close(int type, u_int32_t seq, void *ctxt)
2448 {
2449         int id;
2450         Channel *c;
2451
2452         id = packet_get_int();
2453         packet_check_eom();
2454         c = channel_lookup(id);
2455         if (c == NULL)
2456                 packet_disconnect("Received close for nonexistent channel %d.", id);
2457
2458         /*
2459          * Send a confirmation that we have closed the channel and no more
2460          * data is coming for it.
2461          */
2462         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2463         packet_put_int(c->remote_id);
2464         packet_send();
2465
2466         /*
2467          * If the channel is in closed state, we have sent a close request,
2468          * and the other side will eventually respond with a confirmation.
2469          * Thus, we cannot free the channel here, because then there would be
2470          * no-one to receive the confirmation.  The channel gets freed when
2471          * the confirmation arrives.
2472          */
2473         if (c->type != SSH_CHANNEL_CLOSED) {
2474                 /*
2475                  * Not a closed channel - mark it as draining, which will
2476                  * cause it to be freed later.
2477                  */
2478                 buffer_clear(&c->input);
2479                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2480         }
2481 }
2482
2483 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2484 /* ARGSUSED */
2485 void
2486 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2487 {
2488         int id = packet_get_int();
2489         Channel *c = channel_lookup(id);
2490
2491         packet_check_eom();
2492         if (c == NULL)
2493                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2494         chan_rcvd_oclose(c);
2495 }
2496
2497 /* ARGSUSED */
2498 void
2499 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2500 {
2501         int id = packet_get_int();
2502         Channel *c = channel_lookup(id);
2503
2504         packet_check_eom();
2505         if (c == NULL)
2506                 packet_disconnect("Received close confirmation for "
2507                     "out-of-range channel %d.", id);
2508         if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
2509                 packet_disconnect("Received close confirmation for "
2510                     "non-closed channel %d (type %d).", id, c->type);
2511         channel_free(c);
2512 }
2513
2514 /* ARGSUSED */
2515 void
2516 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2517 {
2518         int id, remote_id;
2519         Channel *c;
2520
2521         id = packet_get_int();
2522         c = channel_lookup(id);
2523
2524         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2525                 packet_disconnect("Received open confirmation for "
2526                     "non-opening channel %d.", id);
2527         remote_id = packet_get_int();
2528         /* Record the remote channel number and mark that the channel is now open. */
2529         c->remote_id = remote_id;
2530         c->type = SSH_CHANNEL_OPEN;
2531
2532         if (compat20) {
2533                 c->remote_window = packet_get_int();
2534                 c->remote_maxpacket = packet_get_int();
2535                 if (c->open_confirm) {
2536                         debug2("callback start");
2537                         c->open_confirm(c->self, 1, c->open_confirm_ctx);
2538                         debug2("callback done");
2539                 }
2540                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2541                     c->remote_window, c->remote_maxpacket);
2542         }
2543         packet_check_eom();
2544 }
2545
2546 static char *
2547 reason2txt(int reason)
2548 {
2549         switch (reason) {
2550         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2551                 return "administratively prohibited";
2552         case SSH2_OPEN_CONNECT_FAILED:
2553                 return "connect failed";
2554         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2555                 return "unknown channel type";
2556         case SSH2_OPEN_RESOURCE_SHORTAGE:
2557                 return "resource shortage";
2558         }
2559         return "unknown reason";
2560 }
2561
2562 /* ARGSUSED */
2563 void
2564 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2565 {
2566         int id, reason;
2567         char *msg = NULL, *lang = NULL;
2568         Channel *c;
2569
2570         id = packet_get_int();
2571         c = channel_lookup(id);
2572
2573         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2574                 packet_disconnect("Received open failure for "
2575                     "non-opening channel %d.", id);
2576         if (compat20) {
2577                 reason = packet_get_int();
2578                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2579                         msg  = packet_get_string(NULL);
2580                         lang = packet_get_string(NULL);
2581                 }
2582                 logit("channel %d: open failed: %s%s%s", id,
2583                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2584                 free(msg);
2585                 free(lang);
2586                 if (c->open_confirm) {
2587                         debug2("callback start");
2588                         c->open_confirm(c->self, 0, c->open_confirm_ctx);
2589                         debug2("callback done");
2590                 }
2591         }
2592         packet_check_eom();
2593         /* Schedule the channel for cleanup/deletion. */
2594         chan_mark_dead(c);
2595 }
2596
2597 /* ARGSUSED */
2598 void
2599 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2600 {
2601         Channel *c;
2602         int id;
2603         u_int adjust;
2604
2605         if (!compat20)
2606                 return;
2607
2608         /* Get the channel number and verify it. */
2609         id = packet_get_int();
2610         c = channel_lookup(id);
2611
2612         if (c == NULL) {
2613                 logit("Received window adjust for non-open channel %d.", id);
2614                 return;
2615         }
2616         adjust = packet_get_int();
2617         packet_check_eom();
2618         debug2("channel %d: rcvd adjust %u", id, adjust);
2619         c->remote_window += adjust;
2620 }
2621
2622 /* ARGSUSED */
2623 void
2624 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2625 {
2626         Channel *c = NULL;
2627         u_short host_port;
2628         char *host, *originator_string;
2629         int remote_id;
2630
2631         remote_id = packet_get_int();
2632         host = packet_get_string(NULL);
2633         host_port = packet_get_int();
2634
2635         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2636                 originator_string = packet_get_string(NULL);
2637         } else {
2638                 originator_string = xstrdup("unknown (remote did not supply name)");
2639         }
2640         packet_check_eom();
2641         c = channel_connect_to(host, host_port,
2642             "connected socket", originator_string);
2643         free(originator_string);
2644         free(host);
2645         if (c == NULL) {
2646                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2647                 packet_put_int(remote_id);
2648                 packet_send();
2649         } else
2650                 c->remote_id = remote_id;
2651 }
2652
2653 /* ARGSUSED */
2654 void
2655 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2656 {
2657         Channel *c;
2658         struct channel_confirm *cc;
2659         int id;
2660
2661         /* Reset keepalive timeout */
2662         packet_set_alive_timeouts(0);
2663
2664         id = packet_get_int();
2665         packet_check_eom();
2666
2667         debug2("channel_input_status_confirm: type %d id %d", type, id);
2668
2669         if ((c = channel_lookup(id)) == NULL) {
2670                 logit("channel_input_status_confirm: %d: unknown", id);
2671                 return;
2672         }
2673         ;
2674         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2675                 return;
2676         cc->cb(type, c, cc->ctx);
2677         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2678         explicit_bzero(cc, sizeof(*cc));
2679         free(cc);
2680 }
2681
2682 /* -- tcp forwarding */
2683
2684 void
2685 channel_set_af(int af)
2686 {
2687         IPv4or6 = af;
2688 }
2689
2690
2691 /*
2692  * Determine whether or not a port forward listens to loopback, the
2693  * specified address or wildcard. On the client, a specified bind
2694  * address will always override gateway_ports. On the server, a
2695  * gateway_ports of 1 (``yes'') will override the client's specification
2696  * and force a wildcard bind, whereas a value of 2 (``clientspecified'')
2697  * will bind to whatever address the client asked for.
2698  *
2699  * Special-case listen_addrs are:
2700  *
2701  * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2702  * "" (empty string), "*"  -> wildcard v4/v6
2703  * "localhost"             -> loopback v4/v6
2704  */
2705 static const char *
2706 channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
2707     int is_client, int gateway_ports)
2708 {
2709         const char *addr = NULL;
2710         int wildcard = 0;
2711
2712         if (listen_addr == NULL) {
2713                 /* No address specified: default to gateway_ports setting */
2714                 if (gateway_ports)
2715                         wildcard = 1;
2716         } else if (gateway_ports || is_client) {
2717                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2718                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2719                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2720                     (!is_client && gateway_ports == 1)) {
2721                         wildcard = 1;
2722                         /*
2723                          * Notify client if they requested a specific listen
2724                          * address and it was overridden.
2725                          */
2726                         if (*listen_addr != '\0' &&
2727                             strcmp(listen_addr, "0.0.0.0") != 0 &&
2728                             strcmp(listen_addr, "*") != 0) {
2729                                 packet_send_debug("Forwarding listen address "
2730                                     "\"%s\" overridden by server "
2731                                     "GatewayPorts", listen_addr);
2732                         }
2733                 }
2734                 else if (strcmp(listen_addr, "localhost") != 0)
2735                         addr = listen_addr;
2736         }
2737         if (wildcardp != NULL)
2738                 *wildcardp = wildcard;
2739         return addr;
2740 }
2741
2742 static int
2743 channel_setup_fwd_listener(int type, const char *listen_addr,
2744     u_short listen_port, int *allocated_listen_port,
2745     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2746 {
2747         Channel *c;
2748         int sock, r, success = 0, wildcard = 0, is_client;
2749         struct addrinfo hints, *ai, *aitop;
2750         const char *host, *addr;
2751         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2752         in_port_t *lport_p;
2753
2754         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2755             listen_addr : host_to_connect;
2756         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2757
2758         if (host == NULL) {
2759                 error("No forward host name.");
2760                 return 0;
2761         }
2762         if (strlen(host) >= NI_MAXHOST) {
2763                 error("Forward host name too long.");
2764                 return 0;
2765         }
2766
2767         /* Determine the bind address, cf. channel_fwd_bind_addr() comment */
2768         addr = channel_fwd_bind_addr(listen_addr, &wildcard,
2769             is_client, gateway_ports);
2770         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2771             type, wildcard, (addr == NULL) ? "NULL" : addr);
2772
2773         /*
2774          * getaddrinfo returns a loopback address if the hostname is
2775          * set to NULL and hints.ai_flags is not AI_PASSIVE
2776          */
2777         memset(&hints, 0, sizeof(hints));
2778         hints.ai_family = IPv4or6;
2779         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2780         hints.ai_socktype = SOCK_STREAM;
2781         snprintf(strport, sizeof strport, "%d", listen_port);
2782         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2783                 if (addr == NULL) {
2784                         /* This really shouldn't happen */
2785                         packet_disconnect("getaddrinfo: fatal error: %s",
2786                             ssh_gai_strerror(r));
2787                 } else {
2788                         error("channel_setup_fwd_listener: "
2789                             "getaddrinfo(%.64s): %s", addr,
2790                             ssh_gai_strerror(r));
2791                 }
2792                 return 0;
2793         }
2794         if (allocated_listen_port != NULL)
2795                 *allocated_listen_port = 0;
2796         for (ai = aitop; ai; ai = ai->ai_next) {
2797                 switch (ai->ai_family) {
2798                 case AF_INET:
2799                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2800                             sin_port;
2801                         break;
2802                 case AF_INET6:
2803                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2804                             sin6_port;
2805                         break;
2806                 default:
2807                         continue;
2808                 }
2809                 /*
2810                  * If allocating a port for -R forwards, then use the
2811                  * same port for all address families.
2812                  */
2813                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2814                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2815                         *lport_p = htons(*allocated_listen_port);
2816
2817                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2818                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2819                         error("channel_setup_fwd_listener: getnameinfo failed");
2820                         continue;
2821                 }
2822                 /* Create a port to listen for the host. */
2823                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2824                 if (sock < 0) {
2825                         /* this is no error since kernel may not support ipv6 */
2826                         verbose("socket: %.100s", strerror(errno));
2827                         continue;
2828                 }
2829
2830                 channel_set_reuseaddr(sock);
2831                 if (ai->ai_family == AF_INET6)
2832                         sock_set_v6only(sock);
2833
2834                 debug("Local forwarding listening on %s port %s.",
2835                     ntop, strport);
2836
2837                 /* Bind the socket to the address. */
2838                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2839                         /* address can be in use ipv6 address is already bound */
2840                         if (!ai->ai_next)
2841                                 error("bind: %.100s", strerror(errno));
2842                         else
2843                                 verbose("bind: %.100s", strerror(errno));
2844
2845                         close(sock);
2846                         continue;
2847                 }
2848                 /* Start listening for connections on the socket. */
2849                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2850                         error("listen: %.100s", strerror(errno));
2851                         close(sock);
2852                         continue;
2853                 }
2854
2855                 /*
2856                  * listen_port == 0 requests a dynamically allocated port -
2857                  * record what we got.
2858                  */
2859                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2860                     allocated_listen_port != NULL &&
2861                     *allocated_listen_port == 0) {
2862                         *allocated_listen_port = get_sock_port(sock, 1);
2863                         debug("Allocated listen port %d",
2864                             *allocated_listen_port);
2865                 }
2866
2867                 /* Allocate a channel number for the socket. */
2868                 c = channel_new("port listener", type, sock, sock, -1,
2869                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2870                     0, "port listener", 1);
2871                 c->path = xstrdup(host);
2872                 c->host_port = port_to_connect;
2873                 c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
2874                 if (listen_port == 0 && allocated_listen_port != NULL &&
2875                     !(datafellows & SSH_BUG_DYNAMIC_RPORT))
2876                         c->listening_port = *allocated_listen_port;
2877                 else
2878                         c->listening_port = listen_port;
2879                 success = 1;
2880         }
2881         if (success == 0)
2882                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2883                     listen_port);
2884         freeaddrinfo(aitop);
2885         return success;
2886 }
2887
2888 int
2889 channel_cancel_rport_listener(const char *host, u_short port)
2890 {
2891         u_int i;
2892         int found = 0;
2893
2894         for (i = 0; i < channels_alloc; i++) {
2895                 Channel *c = channels[i];
2896                 if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
2897                         continue;
2898                 if (strcmp(c->path, host) == 0 && c->listening_port == port) {
2899                         debug2("%s: close channel %d", __func__, i);
2900                         channel_free(c);
2901                         found = 1;
2902                 }
2903         }
2904
2905         return (found);
2906 }
2907
2908 int
2909 channel_cancel_lport_listener(const char *lhost, u_short lport,
2910     int cport, int gateway_ports)
2911 {
2912         u_int i;
2913         int found = 0;
2914         const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, gateway_ports);
2915
2916         for (i = 0; i < channels_alloc; i++) {
2917                 Channel *c = channels[i];
2918                 if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
2919                         continue;
2920                 if (c->listening_port != lport)
2921                         continue;
2922                 if (cport == CHANNEL_CANCEL_PORT_STATIC) {
2923                         /* skip dynamic forwardings */
2924                         if (c->host_port == 0)
2925                                 continue;
2926                 } else {
2927                         if (c->host_port != cport)
2928                                 continue;
2929                 }
2930                 if ((c->listening_addr == NULL && addr != NULL) ||
2931                     (c->listening_addr != NULL && addr == NULL))
2932                         continue;
2933                 if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
2934                         debug2("%s: close channel %d", __func__, i);
2935                         channel_free(c);
2936                         found = 1;
2937                 }
2938         }
2939
2940         return (found);
2941 }
2942
2943 /* protocol local port fwd, used by ssh (and sshd in v1) */
2944 int
2945 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2946     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2947 {
2948         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2949             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2950             gateway_ports);
2951 }
2952
2953 /* protocol v2 remote port fwd, used by sshd */
2954 int
2955 channel_setup_remote_fwd_listener(const char *listen_address,
2956     u_short listen_port, int *allocated_listen_port, int gateway_ports)
2957 {
2958         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2959             listen_address, listen_port, allocated_listen_port,
2960             NULL, 0, gateway_ports);
2961 }
2962
2963 /*
2964  * Translate the requested rfwd listen host to something usable for
2965  * this server.
2966  */
2967 static const char *
2968 channel_rfwd_bind_host(const char *listen_host)
2969 {
2970         if (listen_host == NULL) {
2971                 if (datafellows & SSH_BUG_RFWD_ADDR)
2972                         return "127.0.0.1";
2973                 else
2974                         return "localhost";
2975         } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
2976                 if (datafellows & SSH_BUG_RFWD_ADDR)
2977                         return "0.0.0.0";
2978                 else
2979                         return "";
2980         } else
2981                 return listen_host;
2982 }
2983
2984 /*
2985  * Initiate forwarding of connections to port "port" on remote host through
2986  * the secure channel to host:port from local side.
2987  * Returns handle (index) for updating the dynamic listen port with
2988  * channel_update_permitted_opens().
2989  */
2990 int
2991 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2992     const char *host_to_connect, u_short port_to_connect)
2993 {
2994         int type, success = 0, idx = -1;
2995
2996         /* Send the forward request to the remote side. */
2997         if (compat20) {
2998                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2999                 packet_put_cstring("tcpip-forward");
3000                 packet_put_char(1);             /* boolean: want reply */
3001                 packet_put_cstring(channel_rfwd_bind_host(listen_host));
3002                 packet_put_int(listen_port);
3003                 packet_send();
3004                 packet_write_wait();
3005                 /* Assume that server accepts the request */
3006                 success = 1;
3007         } else {
3008                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
3009                 packet_put_int(listen_port);
3010                 packet_put_cstring(host_to_connect);
3011                 packet_put_int(port_to_connect);
3012                 packet_send();
3013                 packet_write_wait();
3014
3015                 /* Wait for response from the remote side. */
3016                 type = packet_read();
3017                 switch (type) {
3018                 case SSH_SMSG_SUCCESS:
3019                         success = 1;
3020                         break;
3021                 case SSH_SMSG_FAILURE:
3022                         break;
3023                 default:
3024                         /* Unknown packet */
3025                         packet_disconnect("Protocol error for port forward request:"
3026                             "received packet type %d.", type);
3027                 }
3028         }
3029         if (success) {
3030                 /* Record that connection to this host/port is permitted. */
3031                 permitted_opens = xrealloc(permitted_opens,
3032                     num_permitted_opens + 1, sizeof(*permitted_opens));
3033                 idx = num_permitted_opens++;
3034                 permitted_opens[idx].host_to_connect = xstrdup(host_to_connect);
3035                 permitted_opens[idx].port_to_connect = port_to_connect;
3036                 permitted_opens[idx].listen_port = listen_port;
3037         }
3038         return (idx);
3039 }
3040
3041 /*
3042  * Request cancellation of remote forwarding of connection host:port from
3043  * local side.
3044  */
3045 int
3046 channel_request_rforward_cancel(const char *host, u_short port)
3047 {
3048         int i;
3049
3050         if (!compat20)
3051                 return -1;
3052
3053         for (i = 0; i < num_permitted_opens; i++) {
3054                 if (permitted_opens[i].host_to_connect != NULL &&
3055                     permitted_opens[i].listen_port == port)
3056                         break;
3057         }
3058         if (i >= num_permitted_opens) {
3059                 debug("%s: requested forward not found", __func__);
3060                 return -1;
3061         }
3062         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3063         packet_put_cstring("cancel-tcpip-forward");
3064         packet_put_char(0);
3065         packet_put_cstring(channel_rfwd_bind_host(host));
3066         packet_put_int(port);
3067         packet_send();
3068
3069         permitted_opens[i].listen_port = 0;
3070         permitted_opens[i].port_to_connect = 0;
3071         free(permitted_opens[i].host_to_connect);
3072         permitted_opens[i].host_to_connect = NULL;
3073
3074         return 0;
3075 }
3076
3077 /*
3078  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
3079  * listening for the port, and sends back a success reply (or disconnect
3080  * message if there was an error).
3081  */
3082 int
3083 channel_input_port_forward_request(int is_root, int gateway_ports)
3084 {
3085         u_short port, host_port;
3086         int success = 0;
3087         char *hostname;
3088
3089         /* Get arguments from the packet. */
3090         port = packet_get_int();
3091         hostname = packet_get_string(NULL);
3092         host_port = packet_get_int();
3093
3094 #ifndef HAVE_CYGWIN
3095         /*
3096          * Check that an unprivileged user is not trying to forward a
3097          * privileged port.
3098          */
3099         if (port < IPPORT_RESERVED && !is_root)
3100                 packet_disconnect(
3101                     "Requested forwarding of port %d but user is not root.",
3102                     port);
3103         if (host_port == 0)
3104                 packet_disconnect("Dynamic forwarding denied.");
3105 #endif
3106
3107         /* Initiate forwarding */
3108         success = channel_setup_local_fwd_listener(NULL, port, hostname,
3109             host_port, gateway_ports);
3110
3111         /* Free the argument string. */
3112         free(hostname);
3113
3114         return (success ? 0 : -1);
3115 }
3116
3117 /*
3118  * Permits opening to any host/port if permitted_opens[] is empty.  This is
3119  * usually called by the server, because the user could connect to any port
3120  * anyway, and the server has no way to know but to trust the client anyway.
3121  */
3122 void
3123 channel_permit_all_opens(void)
3124 {
3125         if (num_permitted_opens == 0)
3126                 all_opens_permitted = 1;
3127 }
3128
3129 void
3130 channel_add_permitted_opens(char *host, int port)
3131 {
3132         debug("allow port forwarding to host %s port %d", host, port);
3133
3134         permitted_opens = xrealloc(permitted_opens,
3135             num_permitted_opens + 1, sizeof(*permitted_opens));
3136         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
3137         permitted_opens[num_permitted_opens].port_to_connect = port;
3138         num_permitted_opens++;
3139
3140         all_opens_permitted = 0;
3141 }
3142
3143 /*
3144  * Update the listen port for a dynamic remote forward, after
3145  * the actual 'newport' has been allocated. If 'newport' < 0 is
3146  * passed then they entry will be invalidated.
3147  */
3148 void
3149 channel_update_permitted_opens(int idx, int newport)
3150 {
3151         if (idx < 0 || idx >= num_permitted_opens) {
3152                 debug("channel_update_permitted_opens: index out of range:"
3153                     " %d num_permitted_opens %d", idx, num_permitted_opens);
3154                 return;
3155         }
3156         debug("%s allowed port %d for forwarding to host %s port %d",
3157             newport > 0 ? "Updating" : "Removing",
3158             newport,
3159             permitted_opens[idx].host_to_connect,
3160             permitted_opens[idx].port_to_connect);
3161         if (newport >= 0)  {
3162                 permitted_opens[idx].listen_port =
3163                     (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
3164         } else {
3165                 permitted_opens[idx].listen_port = 0;
3166                 permitted_opens[idx].port_to_connect = 0;
3167                 free(permitted_opens[idx].host_to_connect);
3168                 permitted_opens[idx].host_to_connect = NULL;
3169         }
3170 }
3171
3172 int
3173 channel_add_adm_permitted_opens(char *host, int port)
3174 {
3175         debug("config allows port forwarding to host %s port %d", host, port);
3176
3177         permitted_adm_opens = xrealloc(permitted_adm_opens,
3178             num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
3179         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3180              = xstrdup(host);
3181         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3182         return ++num_adm_permitted_opens;
3183 }
3184
3185 void
3186 channel_disable_adm_local_opens(void)
3187 {
3188         channel_clear_adm_permitted_opens();
3189         permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
3190         permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
3191         num_adm_permitted_opens = 1;
3192 }
3193
3194 void
3195 channel_clear_permitted_opens(void)
3196 {
3197         int i;
3198
3199         for (i = 0; i < num_permitted_opens; i++)
3200                 free(permitted_opens[i].host_to_connect);
3201         free(permitted_opens);
3202         permitted_opens = NULL;
3203         num_permitted_opens = 0;
3204 }
3205
3206 void
3207 channel_clear_adm_permitted_opens(void)
3208 {
3209         int i;
3210
3211         for (i = 0; i < num_adm_permitted_opens; i++)
3212                 free(permitted_adm_opens[i].host_to_connect);
3213         free(permitted_adm_opens);
3214         permitted_adm_opens = NULL;
3215         num_adm_permitted_opens = 0;
3216 }
3217
3218 void
3219 channel_print_adm_permitted_opens(void)
3220 {
3221         int i;
3222
3223         printf("permitopen");
3224         if (num_adm_permitted_opens == 0) {
3225                 printf(" any\n");
3226                 return;
3227         }
3228         for (i = 0; i < num_adm_permitted_opens; i++)
3229                 if (permitted_adm_opens[i].host_to_connect == NULL)
3230                         printf(" none");
3231                 else
3232                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3233                             permitted_adm_opens[i].port_to_connect);
3234         printf("\n");
3235 }
3236
3237 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
3238 int
3239 permitopen_port(const char *p)
3240 {
3241         int port;
3242
3243         if (strcmp(p, "*") == 0)
3244                 return FWD_PERMIT_ANY_PORT;
3245         if ((port = a2port(p)) > 0)
3246                 return port;
3247         return -1;
3248 }
3249
3250 static int
3251 port_match(u_short allowedport, u_short requestedport)
3252 {
3253         if (allowedport == FWD_PERMIT_ANY_PORT ||
3254             allowedport == requestedport)
3255                 return 1;
3256         return 0;
3257 }
3258
3259 /* Try to start non-blocking connect to next host in cctx list */
3260 static int
3261 connect_next(struct channel_connect *cctx)
3262 {
3263         int sock, saved_errno;
3264         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
3265
3266         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3267                 if (cctx->ai->ai_family != AF_INET &&
3268                     cctx->ai->ai_family != AF_INET6)
3269                         continue;
3270                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3271                     ntop, sizeof(ntop), strport, sizeof(strport),
3272                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3273                         error("connect_next: getnameinfo failed");
3274                         continue;
3275                 }
3276                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3277                     cctx->ai->ai_protocol)) == -1) {
3278                         if (cctx->ai->ai_next == NULL)
3279                                 error("socket: %.100s", strerror(errno));
3280                         else
3281                                 verbose("socket: %.100s", strerror(errno));
3282                         continue;
3283                 }
3284                 if (set_nonblock(sock) == -1)
3285                         fatal("%s: set_nonblock(%d)", __func__, sock);
3286                 if (connect(sock, cctx->ai->ai_addr,
3287                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3288                         debug("connect_next: host %.100s ([%.100s]:%s): "
3289                             "%.100s", cctx->host, ntop, strport,
3290                             strerror(errno));
3291                         saved_errno = errno;
3292                         close(sock);
3293                         errno = saved_errno;
3294                         continue;       /* fail -- try next */
3295                 }
3296                 debug("connect_next: host %.100s ([%.100s]:%s) "
3297                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3298                 cctx->ai = cctx->ai->ai_next;
3299                 set_nodelay(sock);
3300                 return sock;
3301         }
3302         return -1;
3303 }
3304
3305 static void
3306 channel_connect_ctx_free(struct channel_connect *cctx)
3307 {
3308         free(cctx->host);
3309         if (cctx->aitop)
3310                 freeaddrinfo(cctx->aitop);
3311         memset(cctx, 0, sizeof(*cctx));
3312 }
3313
3314 /* Return CONNECTING channel to remote host, port */
3315 static Channel *
3316 connect_to(const char *host, u_short port, char *ctype, char *rname)
3317 {
3318         struct addrinfo hints;
3319         int gaierr;
3320         int sock = -1;
3321         char strport[NI_MAXSERV];
3322         struct channel_connect cctx;
3323         Channel *c;
3324
3325         memset(&cctx, 0, sizeof(cctx));
3326         memset(&hints, 0, sizeof(hints));
3327         hints.ai_family = IPv4or6;
3328         hints.ai_socktype = SOCK_STREAM;
3329         snprintf(strport, sizeof strport, "%d", port);
3330         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
3331                 error("connect_to %.100s: unknown host (%s)", host,
3332                     ssh_gai_strerror(gaierr));
3333                 return NULL;
3334         }
3335
3336         cctx.host = xstrdup(host);
3337         cctx.port = port;
3338         cctx.ai = cctx.aitop;
3339
3340         if ((sock = connect_next(&cctx)) == -1) {
3341                 error("connect to %.100s port %d failed: %s",
3342                     host, port, strerror(errno));
3343                 channel_connect_ctx_free(&cctx);
3344                 return NULL;
3345         }
3346         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3347             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3348         c->connect_ctx = cctx;
3349         return c;
3350 }
3351
3352 Channel *
3353 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3354 {
3355         int i;
3356
3357         for (i = 0; i < num_permitted_opens; i++) {
3358                 if (permitted_opens[i].host_to_connect != NULL &&
3359                     port_match(permitted_opens[i].listen_port, listen_port)) {
3360                         return connect_to(
3361                             permitted_opens[i].host_to_connect,
3362                             permitted_opens[i].port_to_connect, ctype, rname);
3363                 }
3364         }
3365         error("WARNING: Server requests forwarding for unknown listen_port %d",
3366             listen_port);
3367         return NULL;
3368 }
3369
3370 /* Check if connecting to that port is permitted and connect. */
3371 Channel *
3372 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3373 {
3374         int i, permit, permit_adm = 1;
3375
3376         permit = all_opens_permitted;
3377         if (!permit) {
3378                 for (i = 0; i < num_permitted_opens; i++)
3379                         if (permitted_opens[i].host_to_connect != NULL &&
3380                             port_match(permitted_opens[i].port_to_connect, port) &&
3381                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3382                                 permit = 1;
3383         }
3384
3385         if (num_adm_permitted_opens > 0) {
3386                 permit_adm = 0;
3387                 for (i = 0; i < num_adm_permitted_opens; i++)
3388                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3389                             port_match(permitted_adm_opens[i].port_to_connect, port) &&
3390                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3391                             == 0)
3392                                 permit_adm = 1;
3393         }
3394
3395         if (!permit || !permit_adm) {
3396                 logit("Received request to connect to host %.100s port %d, "
3397                     "but the request was denied.", host, port);
3398                 return NULL;
3399         }
3400         return connect_to(host, port, ctype, rname);
3401 }
3402
3403 void
3404 channel_send_window_changes(void)
3405 {
3406         u_int i;
3407         struct winsize ws;
3408
3409         for (i = 0; i < channels_alloc; i++) {
3410                 if (channels[i] == NULL || !channels[i]->client_tty ||
3411                     channels[i]->type != SSH_CHANNEL_OPEN)
3412                         continue;
3413                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3414                         continue;
3415                 channel_request_start(i, "window-change", 0);
3416                 packet_put_int((u_int)ws.ws_col);
3417                 packet_put_int((u_int)ws.ws_row);
3418                 packet_put_int((u_int)ws.ws_xpixel);
3419                 packet_put_int((u_int)ws.ws_ypixel);
3420                 packet_send();
3421         }
3422 }
3423
3424 /* -- X11 forwarding */
3425
3426 /*
3427  * Creates an internet domain socket for listening for X11 connections.
3428  * Returns 0 and a suitable display number for the DISPLAY variable
3429  * stored in display_numberp , or -1 if an error occurs.
3430  */
3431 int
3432 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3433     int single_connection, u_int *display_numberp, int **chanids)
3434 {
3435         Channel *nc = NULL;
3436         int display_number, sock;
3437         u_short port;
3438         struct addrinfo hints, *ai, *aitop;
3439         char strport[NI_MAXSERV];
3440         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3441
3442         if (chanids == NULL)
3443                 return -1;
3444
3445         for (display_number = x11_display_offset;
3446             display_number < MAX_DISPLAYS;
3447             display_number++) {
3448                 port = 6000 + display_number;
3449                 memset(&hints, 0, sizeof(hints));
3450                 hints.ai_family = IPv4or6;
3451                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3452                 hints.ai_socktype = SOCK_STREAM;
3453                 snprintf(strport, sizeof strport, "%d", port);
3454                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3455                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3456                         return -1;
3457                 }
3458                 for (ai = aitop; ai; ai = ai->ai_next) {
3459                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3460                                 continue;
3461                         sock = socket(ai->ai_family, ai->ai_socktype,
3462                             ai->ai_protocol);
3463                         if (sock < 0) {
3464                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
3465 #ifdef EPFNOSUPPORT
3466                                     && (errno != EPFNOSUPPORT)
3467 #endif
3468                                     ) {
3469                                         error("socket: %.100s", strerror(errno));
3470                                         freeaddrinfo(aitop);
3471                                         return -1;
3472                                 } else {
3473                                         debug("x11_create_display_inet: Socket family %d not supported",
3474                                                  ai->ai_family);
3475                                         continue;
3476                                 }
3477                         }
3478                         if (ai->ai_family == AF_INET6)
3479                                 sock_set_v6only(sock);
3480                         if (x11_use_localhost)
3481                                 channel_set_reuseaddr(sock);
3482                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3483                                 debug2("bind port %d: %.100s", port, strerror(errno));
3484                                 close(sock);
3485
3486                                 for (n = 0; n < num_socks; n++) {
3487                                         close(socks[n]);
3488                                 }
3489                                 num_socks = 0;
3490                                 break;
3491                         }
3492                         socks[num_socks++] = sock;
3493                         if (num_socks == NUM_SOCKS)
3494                                 break;
3495                 }
3496                 freeaddrinfo(aitop);
3497                 if (num_socks > 0)
3498                         break;
3499         }
3500         if (display_number >= MAX_DISPLAYS) {
3501                 error("Failed to allocate internet-domain X11 display socket.");
3502                 return -1;
3503         }
3504         /* Start listening for connections on the socket. */
3505         for (n = 0; n < num_socks; n++) {
3506                 sock = socks[n];
3507                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3508                         error("listen: %.100s", strerror(errno));
3509                         close(sock);
3510                         return -1;
3511                 }
3512         }
3513
3514         /* Allocate a channel for each socket. */
3515         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3516         for (n = 0; n < num_socks; n++) {
3517                 sock = socks[n];
3518                 nc = channel_new("x11 listener",
3519                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3520                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3521                     0, "X11 inet listener", 1);
3522                 nc->single_connection = single_connection;
3523                 (*chanids)[n] = nc->self;
3524         }
3525         (*chanids)[n] = -1;
3526
3527         /* Return the display number for the DISPLAY environment variable. */
3528         *display_numberp = display_number;
3529         return (0);
3530 }
3531
3532 static int
3533 connect_local_xsocket_path(const char *pathname)
3534 {
3535         int sock;
3536         struct sockaddr_un addr;
3537
3538         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3539         if (sock < 0)
3540                 error("socket: %.100s", strerror(errno));
3541         memset(&addr, 0, sizeof(addr));
3542         addr.sun_family = AF_UNIX;
3543         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3544         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3545                 return sock;
3546         close(sock);
3547         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3548         return -1;
3549 }
3550
3551 static int
3552 connect_local_xsocket(u_int dnr)
3553 {
3554         char buf[1024];
3555         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3556         return connect_local_xsocket_path(buf);
3557 }
3558
3559 int
3560 x11_connect_display(void)
3561 {
3562         u_int display_number;
3563         const char *display;
3564         char buf[1024], *cp;
3565         struct addrinfo hints, *ai, *aitop;
3566         char strport[NI_MAXSERV];
3567         int gaierr, sock = 0;
3568
3569         /* Try to open a socket for the local X server. */
3570         display = getenv("DISPLAY");
3571         if (!display) {
3572                 error("DISPLAY not set.");
3573                 return -1;
3574         }
3575         /*
3576          * Now we decode the value of the DISPLAY variable and make a
3577          * connection to the real X server.
3578          */
3579
3580         /* Check if the display is from launchd. */
3581 #ifdef __APPLE__
3582         if (strncmp(display, "/tmp/launch", 11) == 0) {
3583                 sock = connect_local_xsocket_path(display);
3584                 if (sock < 0)
3585                         return -1;
3586
3587                 /* OK, we now have a connection to the display. */
3588                 return sock;
3589         }
3590 #endif
3591         /*
3592          * Check if it is a unix domain socket.  Unix domain displays are in
3593          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3594          */
3595         if (strncmp(display, "unix:", 5) == 0 ||
3596             display[0] == ':') {
3597                 /* Connect to the unix domain socket. */
3598                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3599                         error("Could not parse display number from DISPLAY: %.100s",
3600                             display);
3601                         return -1;
3602                 }
3603                 /* Create a socket. */
3604                 sock = connect_local_xsocket(display_number);
3605                 if (sock < 0)
3606                         return -1;
3607
3608                 /* OK, we now have a connection to the display. */
3609                 return sock;
3610         }
3611         /*
3612          * Connect to an inet socket.  The DISPLAY value is supposedly
3613          * hostname:d[.s], where hostname may also be numeric IP address.
3614          */
3615         strlcpy(buf, display, sizeof(buf));
3616         cp = strchr(buf, ':');
3617         if (!cp) {
3618                 error("Could not find ':' in DISPLAY: %.100s", display);
3619                 return -1;
3620         }
3621         *cp = 0;
3622         /* buf now contains the host name.  But first we parse the display number. */
3623         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3624                 error("Could not parse display number from DISPLAY: %.100s",
3625                     display);
3626                 return -1;
3627         }
3628
3629         /* Look up the host address */
3630         memset(&hints, 0, sizeof(hints));
3631         hints.ai_family = IPv4or6;
3632         hints.ai_socktype = SOCK_STREAM;
3633         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3634         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3635                 error("%.100s: unknown host. (%s)", buf,
3636                 ssh_gai_strerror(gaierr));
3637                 return -1;
3638         }
3639         for (ai = aitop; ai; ai = ai->ai_next) {
3640                 /* Create a socket. */
3641                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3642                 if (sock < 0) {
3643                         debug2("socket: %.100s", strerror(errno));
3644                         continue;
3645                 }
3646                 /* Connect it to the display. */
3647                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3648                         debug2("connect %.100s port %u: %.100s", buf,
3649                             6000 + display_number, strerror(errno));
3650                         close(sock);
3651                         continue;
3652                 }
3653                 /* Success */
3654                 break;
3655         }
3656         freeaddrinfo(aitop);
3657         if (!ai) {
3658                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3659                     strerror(errno));
3660                 return -1;
3661         }
3662         set_nodelay(sock);
3663         return sock;
3664 }
3665
3666 /*
3667  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3668  * the remote channel number.  We should do whatever we want, and respond
3669  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3670  */
3671
3672 /* ARGSUSED */
3673 void
3674 x11_input_open(int type, u_int32_t seq, void *ctxt)
3675 {
3676         Channel *c = NULL;
3677         int remote_id, sock = 0;
3678         char *remote_host;
3679
3680         debug("Received X11 open request.");
3681
3682         remote_id = packet_get_int();
3683
3684         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3685                 remote_host = packet_get_string(NULL);
3686         } else {
3687                 remote_host = xstrdup("unknown (remote did not supply name)");
3688         }
3689         packet_check_eom();
3690
3691         /* Obtain a connection to the real X display. */
3692         sock = x11_connect_display();
3693         if (sock != -1) {
3694                 /* Allocate a channel for this connection. */
3695                 c = channel_new("connected x11 socket",
3696                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3697                     remote_host, 1);
3698                 c->remote_id = remote_id;
3699                 c->force_drain = 1;
3700         }
3701         free(remote_host);
3702         if (c == NULL) {
3703                 /* Send refusal to the remote host. */
3704                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3705                 packet_put_int(remote_id);
3706         } else {
3707                 /* Send a confirmation to the remote host. */
3708                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3709                 packet_put_int(remote_id);
3710                 packet_put_int(c->self);
3711         }
3712         packet_send();
3713 }
3714
3715 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3716 /* ARGSUSED */
3717 void
3718 deny_input_open(int type, u_int32_t seq, void *ctxt)
3719 {
3720         int rchan = packet_get_int();
3721
3722         switch (type) {
3723         case SSH_SMSG_AGENT_OPEN:
3724                 error("Warning: ssh server tried agent forwarding.");
3725                 break;
3726         case SSH_SMSG_X11_OPEN:
3727                 error("Warning: ssh server tried X11 forwarding.");
3728                 break;
3729         default:
3730                 error("deny_input_open: type %d", type);
3731                 break;
3732         }
3733         error("Warning: this is probably a break-in attempt by a malicious server.");
3734         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3735         packet_put_int(rchan);
3736         packet_send();
3737 }
3738
3739 /*
3740  * Requests forwarding of X11 connections, generates fake authentication
3741  * data, and enables authentication spoofing.
3742  * This should be called in the client only.
3743  */
3744 void
3745 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3746     const char *proto, const char *data, int want_reply)
3747 {
3748         u_int data_len = (u_int) strlen(data) / 2;
3749         u_int i, value;
3750         char *new_data;
3751         int screen_number;
3752         const char *cp;
3753         u_int32_t rnd = 0;
3754
3755         if (x11_saved_display == NULL)
3756                 x11_saved_display = xstrdup(disp);
3757         else if (strcmp(disp, x11_saved_display) != 0) {
3758                 error("x11_request_forwarding_with_spoofing: different "
3759                     "$DISPLAY already forwarded");
3760                 return;
3761         }
3762
3763         cp = strchr(disp, ':');
3764         if (cp)
3765                 cp = strchr(cp, '.');
3766         if (cp)
3767                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3768         else
3769                 screen_number = 0;
3770
3771         if (x11_saved_proto == NULL) {
3772                 /* Save protocol name. */
3773                 x11_saved_proto = xstrdup(proto);
3774                 /*
3775                  * Extract real authentication data and generate fake data
3776                  * of the same length.
3777                  */
3778                 x11_saved_data = xmalloc(data_len);
3779                 x11_fake_data = xmalloc(data_len);
3780                 for (i = 0; i < data_len; i++) {
3781                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3782                                 fatal("x11_request_forwarding: bad "
3783                                     "authentication data: %.100s", data);
3784                         if (i % 4 == 0)
3785                                 rnd = arc4random();
3786                         x11_saved_data[i] = value;
3787                         x11_fake_data[i] = rnd & 0xff;
3788                         rnd >>= 8;
3789                 }
3790                 x11_saved_data_len = data_len;
3791                 x11_fake_data_len = data_len;
3792         }
3793
3794         /* Convert the fake data into hex. */
3795         new_data = tohex(x11_fake_data, data_len);
3796
3797         /* Send the request packet. */
3798         if (compat20) {
3799                 channel_request_start(client_session_id, "x11-req", want_reply);
3800                 packet_put_char(0);     /* XXX bool single connection */
3801         } else {
3802                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3803         }
3804         packet_put_cstring(proto);
3805         packet_put_cstring(new_data);
3806         packet_put_int(screen_number);
3807         packet_send();
3808         packet_write_wait();
3809         free(new_data);
3810 }
3811
3812
3813 /* -- agent forwarding */
3814
3815 /* Sends a message to the server to request authentication fd forwarding. */
3816
3817 void
3818 auth_request_forwarding(void)
3819 {
3820         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3821         packet_send();
3822         packet_write_wait();
3823 }