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