crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.319 2012/12/02 20:46:11 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * This file contains functions for generic socket connection forwarding.
   8  * There is also code for initiating connection forwarding for X11 connections,
   9  * arbitrary tcp/ip connections, and the authentication agent connection.
  10  *
  11  * As far as I am concerned, the code I have written for this software
  12  * can be used freely for any purpose.  Any derived versions of this
  13  * software must be clearly marked as such, and if the derived work is
  14  * incompatible with the protocol description in the RFC file, it must be
  15  * called by a name other than "ssh" or "Secure Shell".
  16  *
  17  * SSH2 support added by Markus Friedl.
  18  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  19  * Copyright (c) 1999 Dug Song.  All rights reserved.
  20  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44
  45 #include <sys/types.h>
  46 #include <sys/ioctl.h>
  47 #include <sys/un.h>
  48 #include <sys/socket.h>
  49 #ifdef HAVE_SYS_TIME_H
  50 # include <sys/time.h>
  51 #endif
  52
  53 #include <netinet/in.h>
  54 #include <arpa/inet.h>
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <termios.h>
  63 #include <unistd.h>
  64 #include <stdarg.h>
  65
  66 #include "openbsd-compat/sys-queue.h"
  67 #include "xmalloc.h"
  68 #include "ssh.h"
  69 #include "ssh1.h"
  70 #include "ssh2.h"
  71 #include "packet.h"
  72 #include "log.h"
  73 #include "misc.h"
  74 #include "buffer.h"
  75 #include "channels.h"
  76 #include "compat.h"
  77 #include "canohost.h"
  78 #include "key.h"
  79 #include "authfd.h"
  80 #include "pathnames.h"
  81
  82 /* -- channel core */
  83
  84 /*
  85  * Pointer to an array containing all allocated channels.  The array is
  86  * dynamically extended as needed.
  87  */
  88 static Channel **channels = NULL;
  89
  90 /*
  91  * Size of the channel array.  All slots of the array must always be
  92  * initialized (at least the type field); unused slots set to NULL
  93  */
  94 static u_int channels_alloc = 0;
  95
  96 /*
  97  * Maximum file descriptor value used in any of the channels.  This is
  98  * updated in channel_new.
  99  */
 100 static int channel_max_fd = 0;
 101
 102
 103 /* -- tcp forwarding */
 104
 105 /*
 106  * Data structure for storing which hosts are permitted for forward requests.
 107  * The local sides of any remote forwards are stored in this array to prevent
 108  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 109  * network (which might be behind a firewall).
 110  */
 111 typedef struct {
 112         char *host_to_connect;          /* Connect to 'host'. */
 113         u_short port_to_connect;        /* Connect to 'port'. */
 114         u_short listen_port;            /* Remote side should listen port number. */
 115 } ForwardPermission;
 116
 117 /* List of all permitted host/port pairs to connect by the user. */
 118 static ForwardPermission *permitted_opens = NULL;
 119
 120 /* List of all permitted host/port pairs to connect by the admin. */
 121 static ForwardPermission *permitted_adm_opens = NULL;
 122
 123 /* Number of permitted host/port pairs in the array permitted by the user. */
 124 static int num_permitted_opens = 0;
 125
 126 /* Number of permitted host/port pair in the array permitted by the admin. */
 127 static int num_adm_permitted_opens = 0;
 128
 129 /* special-case port number meaning allow any port */
 130 #define FWD_PERMIT_ANY_PORT     0
 131
 132 /*
 133  * If this is true, all opens are permitted.  This is the case on the server
 134  * on which we have to trust the client anyway, and the user could do
 135  * anything after logging in anyway.
 136  */
 137 static int all_opens_permitted = 0;
 138
 139
 140 /* -- X11 forwarding */
 141
 142 /* Maximum number of fake X11 displays to try. */
 143 #define MAX_DISPLAYS  1000
 144
 145 /* Saved X11 local (client) display. */
 146 static char *x11_saved_display = NULL;
 147
 148 /* Saved X11 authentication protocol name. */
 149 static char *x11_saved_proto = NULL;
 150
 151 /* Saved X11 authentication data.  This is the real data. */
 152 static char *x11_saved_data = NULL;
 153 static u_int x11_saved_data_len = 0;
 154
 155 /*
 156  * Fake X11 authentication data.  This is what the server will be sending us;
 157  * we should replace any occurrences of this by the real data.
 158  */
 159 static u_char *x11_fake_data = NULL;
 160 static u_int x11_fake_data_len;
 161
 162
 163 /* -- agent forwarding */
 164
 165 #define NUM_SOCKS       10
 166
 167 /* AF_UNSPEC or AF_INET or AF_INET6 */
 168 static int IPv4or6 = AF_UNSPEC;
 169
 170 /* helper */
 171 static void port_open_helper(Channel *c, char *rtype);
 172
 173 /* non-blocking connect helpers */
 174 static int connect_next(struct channel_connect *);
 175 static void channel_connect_ctx_free(struct channel_connect *);
 176
 177 /* -- HPN */
 178
 179 static int hpn_disabled = 0;
 180 static u_int buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
 181
 182 /* -- channel core */
 183
 184 Channel *
 185 channel_by_id(int id)
 186 {
 187         Channel *c;
 188
 189         if (id < 0 || (u_int)id >= channels_alloc) {
 190                 logit("channel_by_id: %d: bad id", id);
 191                 return NULL;
 192         }
 193         c = channels[id];
 194         if (c == NULL) {
 195                 logit("channel_by_id: %d: bad id: channel free", id);
 196                 return NULL;
 197         }
 198         return c;
 199 }
 200
 201 /*
 202  * Returns the channel if it is allowed to receive protocol messages.
 203  * Private channels, like listening sockets, may not receive messages.
 204  */
 205 Channel *
 206 channel_lookup(int id)
 207 {
 208         Channel *c;
 209
 210         if ((c = channel_by_id(id)) == NULL)
 211                 return (NULL);
 212
 213         switch (c->type) {
 214         case SSH_CHANNEL_X11_OPEN:
 215         case SSH_CHANNEL_LARVAL:
 216         case SSH_CHANNEL_CONNECTING:
 217         case SSH_CHANNEL_DYNAMIC:
 218         case SSH_CHANNEL_OPENING:
 219         case SSH_CHANNEL_OPEN:
 220         case SSH_CHANNEL_INPUT_DRAINING:
 221         case SSH_CHANNEL_OUTPUT_DRAINING:
 222                 return (c);
 223         }
 224         logit("Non-public channel %d, type %d.", id, c->type);
 225         return (NULL);
 226 }
 227
 228 /*
 229  * Register filedescriptors for a channel, used when allocating a channel or
 230  * when the channel consumer/producer is ready, e.g. shell exec'd
 231  */
 232 static void
 233 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 234     int extusage, int nonblock, int is_tty)
 235 {
 236         /* Update the maximum file descriptor value. */
 237         channel_max_fd = MAX(channel_max_fd, rfd);
 238         channel_max_fd = MAX(channel_max_fd, wfd);
 239         channel_max_fd = MAX(channel_max_fd, efd);
 240
 241         if (rfd != -1)
 242                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 243         if (wfd != -1 && wfd != rfd)
 244                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 245         if (efd != -1 && efd != rfd && efd != wfd)
 246                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 247
 248         c->rfd = rfd;
 249         c->wfd = wfd;
 250         c->sock = (rfd == wfd) ? rfd : -1;
 251         c->efd = efd;
 252         c->extended_usage = extusage;
 253
 254         if ((c->isatty = is_tty) != 0)
 255                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 256         c->wfd_isatty = is_tty || isatty(c->wfd);
 257
 258         /* enable nonblocking mode */
 259         if (nonblock) {
 260                 if (rfd != -1)
 261                         set_nonblock(rfd);
 262                 if (wfd != -1)
 263                         set_nonblock(wfd);
 264                 if (efd != -1)
 265                         set_nonblock(efd);
 266         }
 267 }
 268
 269 /*
 270  * Allocate a new channel object and set its type and socket. This will cause
 271  * remote_name to be freed.
 272  */
 273 Channel *
 274 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 275     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 276 {
 277         int found;
 278         u_int i;
 279         Channel *c;
 280
 281         /* Do initial allocation if this is the first call. */
 282         if (channels_alloc == 0) {
 283                 channels_alloc = 10;
 284                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 285                 for (i = 0; i < channels_alloc; i++)
 286                         channels[i] = NULL;
 287         }
 288         /* Try to find a free slot where to put the new channel. */
 289         for (found = -1, i = 0; i < channels_alloc; i++)
 290                 if (channels[i] == NULL) {
 291                         /* Found a free slot. */
 292                         found = (int)i;
 293                         break;
 294                 }
 295         if (found < 0) {
 296                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 297                 found = channels_alloc;
 298                 if (channels_alloc > 10000)
 299                         fatal("channel_new: internal error: channels_alloc %d "
 300                             "too big.", channels_alloc);
 301                 channels = xrealloc(channels, channels_alloc + 10,
 302                     sizeof(Channel *));
 303                 channels_alloc += 10;
 304                 debug2("channel: expanding %d", channels_alloc);
 305                 for (i = found; i < channels_alloc; i++)
 306                         channels[i] = NULL;
 307         }
 308         /* Initialize and return new channel. */
 309         c = channels[found] = xcalloc(1, sizeof(Channel));
 310         buffer_init(&c->input);
 311         buffer_init(&c->output);
 312         buffer_init(&c->extended);
 313         c->path = NULL;
 314         c->listening_addr = NULL;
 315         c->listening_port = 0;
 316         c->ostate = CHAN_OUTPUT_OPEN;
 317         c->istate = CHAN_INPUT_OPEN;
 318         c->flags = 0;
 319         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 320         c->notbefore = 0;
 321         c->self = found;
 322         c->type = type;
 323         c->ctype = ctype;
 324         c->dynamic_window = 0;
 325         c->local_window = window;
 326         c->local_window_max = window;
 327         c->local_consumed = 0;
 328         c->local_maxpacket = maxpack;
 329         c->remote_id = -1;
 330         c->remote_name = xstrdup(remote_name);
 331         c->remote_window = 0;
 332         c->remote_maxpacket = 0;
 333         c->force_drain = 0;
 334         c->single_connection = 0;
 335         c->detach_user = NULL;
 336         c->detach_close = 0;
 337         c->open_confirm = NULL;
 338         c->open_confirm_ctx = NULL;
 339         c->input_filter = NULL;
 340         c->output_filter = NULL;
 341         c->filter_ctx = NULL;
 342         c->filter_cleanup = NULL;
 343         c->ctl_chan = -1;
 344         c->mux_rcb = NULL;
 345         c->mux_ctx = NULL;
 346         c->mux_pause = 0;
 347         c->delayed = 1;         /* prevent call to channel_post handler */
 348         TAILQ_INIT(&c->status_confirms);
 349         debug("channel %d: new [%s]", found, remote_name);
 350         return c;
 351 }
 352
 353 static int
 354 channel_find_maxfd(void)
 355 {
 356         u_int i;
 357         int max = 0;
 358         Channel *c;
 359
 360         for (i = 0; i < channels_alloc; i++) {
 361                 c = channels[i];
 362                 if (c != NULL) {
 363                         max = MAX(max, c->rfd);
 364                         max = MAX(max, c->wfd);
 365                         max = MAX(max, c->efd);
 366                 }
 367         }
 368         return max;
 369 }
 370
 371 int
 372 channel_close_fd(int *fdp)
 373 {
 374         int ret = 0, fd = *fdp;
 375
 376         if (fd != -1) {
 377                 ret = close(fd);
 378                 *fdp = -1;
 379                 if (fd == channel_max_fd)
 380                         channel_max_fd = channel_find_maxfd();
 381         }
 382         return ret;
 383 }
 384
 385 /* Close all channel fd/socket. */
 386 static void
 387 channel_close_fds(Channel *c)
 388 {
 389         channel_close_fd(&c->sock);
 390         channel_close_fd(&c->rfd);
 391         channel_close_fd(&c->wfd);
 392         channel_close_fd(&c->efd);
 393 }
 394
 395 /* Free the channel and close its fd/socket. */
 396 void
 397 channel_free(Channel *c)
 398 {
 399         char *s;
 400         u_int i, n;
 401         struct channel_confirm *cc;
 402
 403         for (n = 0, i = 0; i < channels_alloc; i++)
 404                 if (channels[i])
 405                         n++;
 406         debug("channel %d: free: %s, nchannels %u", c->self,
 407             c->remote_name ? c->remote_name : "???", n);
 408
 409         s = channel_open_message();
 410         debug3("channel %d: status: %s", c->self, s);
 411         xfree(s);
 412
 413         if (c->sock != -1)
 414                 shutdown(c->sock, SHUT_RDWR);
 415         channel_close_fds(c);
 416         buffer_free(&c->input);
 417         buffer_free(&c->output);
 418         buffer_free(&c->extended);
 419         if (c->remote_name) {
 420                 xfree(c->remote_name);
 421                 c->remote_name = NULL;
 422         }
 423         if (c->path) {
 424                 xfree(c->path);
 425                 c->path = NULL;
 426         }
 427         if (c->listening_addr) {
 428                 xfree(c->listening_addr);
 429                 c->listening_addr = NULL;
 430         }
 431         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 432                 if (cc->abandon_cb != NULL)
 433                         cc->abandon_cb(c, cc->ctx);
 434                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 435                 bzero(cc, sizeof(*cc));
 436                 xfree(cc);
 437         }
 438         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 439                 c->filter_cleanup(c->self, c->filter_ctx);
 440         channels[c->self] = NULL;
 441         xfree(c);
 442 }
 443
 444 void
 445 channel_free_all(void)
 446 {
 447         u_int i;
 448
 449         for (i = 0; i < channels_alloc; i++)
 450                 if (channels[i] != NULL)
 451                         channel_free(channels[i]);
 452 }
 453
 454 /*
 455  * Closes the sockets/fds of all channels.  This is used to close extra file
 456  * descriptors after a fork.
 457  */
 458 void
 459 channel_close_all(void)
 460 {
 461         u_int i;
 462
 463         for (i = 0; i < channels_alloc; i++)
 464                 if (channels[i] != NULL)
 465                         channel_close_fds(channels[i]);
 466 }
 467
 468 /*
 469  * Stop listening to channels.
 470  */
 471 void
 472 channel_stop_listening(void)
 473 {
 474         u_int i;
 475         Channel *c;
 476
 477         for (i = 0; i < channels_alloc; i++) {
 478                 c = channels[i];
 479                 if (c != NULL) {
 480                         switch (c->type) {
 481                         case SSH_CHANNEL_AUTH_SOCKET:
 482                         case SSH_CHANNEL_PORT_LISTENER:
 483                         case SSH_CHANNEL_RPORT_LISTENER:
 484                         case SSH_CHANNEL_X11_LISTENER:
 485                                 channel_close_fd(&c->sock);
 486                                 channel_free(c);
 487                                 break;
 488                         }
 489                 }
 490         }
 491 }
 492
 493 /*
 494  * Returns true if no channel has too much buffered data, and false if one or
 495  * more channel is overfull.
 496  */
 497 int
 498 channel_not_very_much_buffered_data(void)
 499 {
 500         u_int i;
 501         Channel *c;
 502
 503         for (i = 0; i < channels_alloc; i++) {
 504                 c = channels[i];
 505                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 506 #if 0
 507                         if (!compat20 &&
 508                             buffer_len(&c->input) > packet_get_maxsize()) {
 509                                 debug2("channel %d: big input buffer %d",
 510                                     c->self, buffer_len(&c->input));
 511                                 return 0;
 512                         }
 513 #endif
 514                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 515                                 debug2("channel %d: big output buffer %u > %u",
 516                                     c->self, buffer_len(&c->output),
 517                                     packet_get_maxsize());
 518                                 return 0;
 519                         }
 520                 }
 521         }
 522         return 1;
 523 }
 524
 525 /* Returns true if any channel is still open. */
 526 int
 527 channel_still_open(void)
 528 {
 529         u_int i;
 530         Channel *c;
 531
 532         for (i = 0; i < channels_alloc; i++) {
 533                 c = channels[i];
 534                 if (c == NULL)
 535                         continue;
 536                 switch (c->type) {
 537                 case SSH_CHANNEL_X11_LISTENER:
 538                 case SSH_CHANNEL_PORT_LISTENER:
 539                 case SSH_CHANNEL_RPORT_LISTENER:
 540                 case SSH_CHANNEL_MUX_LISTENER:
 541                 case SSH_CHANNEL_CLOSED:
 542                 case SSH_CHANNEL_AUTH_SOCKET:
 543                 case SSH_CHANNEL_DYNAMIC:
 544                 case SSH_CHANNEL_CONNECTING:
 545                 case SSH_CHANNEL_ZOMBIE:
 546                         continue;
 547                 case SSH_CHANNEL_LARVAL:
 548                         if (!compat20)
 549                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 550                         continue;
 551                 case SSH_CHANNEL_OPENING:
 552                 case SSH_CHANNEL_OPEN:
 553                 case SSH_CHANNEL_X11_OPEN:
 554                 case SSH_CHANNEL_MUX_CLIENT:
 555                         return 1;
 556                 case SSH_CHANNEL_INPUT_DRAINING:
 557                 case SSH_CHANNEL_OUTPUT_DRAINING:
 558                         if (!compat13)
 559                                 fatal("cannot happen: OUT_DRAIN");
 560                         return 1;
 561                 default:
 562                         fatal("channel_still_open: bad channel type %d", c->type);
 563                         /* NOTREACHED */
 564                 }
 565         }
 566         return 0;
 567 }
 568
 569 /* Returns the id of an open channel suitable for keepaliving */
 570 int
 571 channel_find_open(void)
 572 {
 573         u_int i;
 574         Channel *c;
 575
 576         for (i = 0; i < channels_alloc; i++) {
 577                 c = channels[i];
 578                 if (c == NULL || c->remote_id < 0)
 579                         continue;
 580                 switch (c->type) {
 581                 case SSH_CHANNEL_CLOSED:
 582                 case SSH_CHANNEL_DYNAMIC:
 583                 case SSH_CHANNEL_X11_LISTENER:
 584                 case SSH_CHANNEL_PORT_LISTENER:
 585                 case SSH_CHANNEL_RPORT_LISTENER:
 586                 case SSH_CHANNEL_MUX_LISTENER:
 587                 case SSH_CHANNEL_MUX_CLIENT:
 588                 case SSH_CHANNEL_OPENING:
 589                 case SSH_CHANNEL_CONNECTING:
 590                 case SSH_CHANNEL_ZOMBIE:
 591                         continue;
 592                 case SSH_CHANNEL_LARVAL:
 593                 case SSH_CHANNEL_AUTH_SOCKET:
 594                 case SSH_CHANNEL_OPEN:
 595                 case SSH_CHANNEL_X11_OPEN:
 596                         return i;
 597                 case SSH_CHANNEL_INPUT_DRAINING:
 598                 case SSH_CHANNEL_OUTPUT_DRAINING:
 599                         if (!compat13)
 600                                 fatal("cannot happen: OUT_DRAIN");
 601                         return i;
 602                 default:
 603                         fatal("channel_find_open: bad channel type %d", c->type);
 604                         /* NOTREACHED */
 605                 }
 606         }
 607         return -1;
 608 }
 609
 610
 611 /*
 612  * Returns a message describing the currently open forwarded connections,
 613  * suitable for sending to the client.  The message contains crlf pairs for
 614  * newlines.
 615  */
 616 char *
 617 channel_open_message(void)
 618 {
 619         Buffer buffer;
 620         Channel *c;
 621         char buf[1024], *cp;
 622         u_int i;
 623
 624         buffer_init(&buffer);
 625         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 626         buffer_append(&buffer, buf, strlen(buf));
 627         for (i = 0; i < channels_alloc; i++) {
 628                 c = channels[i];
 629                 if (c == NULL)
 630                         continue;
 631                 switch (c->type) {
 632                 case SSH_CHANNEL_X11_LISTENER:
 633                 case SSH_CHANNEL_PORT_LISTENER:
 634                 case SSH_CHANNEL_RPORT_LISTENER:
 635                 case SSH_CHANNEL_CLOSED:
 636                 case SSH_CHANNEL_AUTH_SOCKET:
 637                 case SSH_CHANNEL_ZOMBIE:
 638                 case SSH_CHANNEL_MUX_CLIENT:
 639                 case SSH_CHANNEL_MUX_LISTENER:
 640                         continue;
 641                 case SSH_CHANNEL_LARVAL:
 642                 case SSH_CHANNEL_OPENING:
 643                 case SSH_CHANNEL_CONNECTING:
 644                 case SSH_CHANNEL_DYNAMIC:
 645                 case SSH_CHANNEL_OPEN:
 646                 case SSH_CHANNEL_X11_OPEN:
 647                 case SSH_CHANNEL_INPUT_DRAINING:
 648                 case SSH_CHANNEL_OUTPUT_DRAINING:
 649                         snprintf(buf, sizeof buf,
 650                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cc %d)\r\n",
 651                             c->self, c->remote_name,
 652                             c->type, c->remote_id,
 653                             c->istate, buffer_len(&c->input),
 654                             c->ostate, buffer_len(&c->output),
 655                             c->rfd, c->wfd, c->ctl_chan);
 656                         buffer_append(&buffer, buf, strlen(buf));
 657                         continue;
 658                 default:
 659                         fatal("channel_open_message: bad channel type %d", c->type);
 660                         /* NOTREACHED */
 661                 }
 662         }
 663         buffer_append(&buffer, "\0", 1);
 664         cp = xstrdup(buffer_ptr(&buffer));
 665         buffer_free(&buffer);
 666         return cp;
 667 }
 668
 669 void
 670 channel_send_open(int id)
 671 {
 672         Channel *c = channel_lookup(id);
 673
 674         if (c == NULL) {
 675                 logit("channel_send_open: %d: bad id", id);
 676                 return;
 677         }
 678         debug2("channel %d: send open", id);
 679         packet_start(SSH2_MSG_CHANNEL_OPEN);
 680         packet_put_cstring(c->ctype);
 681         packet_put_int(c->self);
 682         packet_put_int(c->local_window);
 683         packet_put_int(c->local_maxpacket);
 684         packet_send();
 685 }
 686
 687 void
 688 channel_request_start(int id, char *service, int wantconfirm)
 689 {
 690         Channel *c = channel_lookup(id);
 691
 692         if (c == NULL) {
 693                 logit("channel_request_start: %d: unknown channel id", id);
 694                 return;
 695         }
 696         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 697         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 698         packet_put_int(c->remote_id);
 699         packet_put_cstring(service);
 700         packet_put_char(wantconfirm);
 701 }
 702
 703 void
 704 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 705     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 706 {
 707         struct channel_confirm *cc;
 708         Channel *c;
 709
 710         if ((c = channel_lookup(id)) == NULL)
 711                 fatal("channel_register_expect: %d: bad id", id);
 712
 713         cc = xmalloc(sizeof(*cc));
 714         cc->cb = cb;
 715         cc->abandon_cb = abandon_cb;
 716         cc->ctx = ctx;
 717         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 718 }
 719
 720 void
 721 channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
 722 {
 723         Channel *c = channel_lookup(id);
 724
 725         if (c == NULL) {
 726                 logit("channel_register_open_confirm: %d: bad id", id);
 727                 return;
 728         }
 729         c->open_confirm = fn;
 730         c->open_confirm_ctx = ctx;
 731 }
 732
 733 void
 734 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 735 {
 736         Channel *c = channel_by_id(id);
 737
 738         if (c == NULL) {
 739                 logit("channel_register_cleanup: %d: bad id", id);
 740                 return;
 741         }
 742         c->detach_user = fn;
 743         c->detach_close = do_close;
 744 }
 745
 746 void
 747 channel_cancel_cleanup(int id)
 748 {
 749         Channel *c = channel_by_id(id);
 750
 751         if (c == NULL) {
 752                 logit("channel_cancel_cleanup: %d: bad id", id);
 753                 return;
 754         }
 755         c->detach_user = NULL;
 756         c->detach_close = 0;
 757 }
 758
 759 void
 760 channel_register_filter(int id, channel_infilter_fn *ifn,
 761     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 762 {
 763         Channel *c = channel_lookup(id);
 764
 765         if (c == NULL) {
 766                 logit("channel_register_filter: %d: bad id", id);
 767                 return;
 768         }
 769         c->input_filter = ifn;
 770         c->output_filter = ofn;
 771         c->filter_ctx = ctx;
 772         c->filter_cleanup = cfn;
 773 }
 774
 775 void
 776 channel_set_fds(int id, int rfd, int wfd, int efd,
 777     int extusage, int nonblock, int is_tty, u_int window_max)
 778 {
 779         Channel *c = channel_lookup(id);
 780
 781         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 782                 fatal("channel_activate for non-larval channel %d.", id);
 783         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 784         c->type = SSH_CHANNEL_OPEN;
 785         c->local_window = c->local_window_max = window_max;
 786         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 787         packet_put_int(c->remote_id);
 788         packet_put_int(c->local_window);
 789         packet_send();
 790 }
 791
 792 /*
 793  * 'channel_pre*' are called just before select() to add any bits relevant to
 794  * channels in the select bitmasks.
 795  */
 796 /*
 797  * 'channel_post*': perform any appropriate operations for channels which
 798  * have events pending.
 799  */
 800 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 801 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 802 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 803
 804 /* ARGSUSED */
 805 static void
 806 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 807 {
 808         FD_SET(c->sock, readset);
 809 }
 810
 811 /* ARGSUSED */
 812 static void
 813 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 814 {
 815         debug3("channel %d: waiting for connection", c->self);
 816         FD_SET(c->sock, writeset);
 817 }
 818
 819 static void
 820 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 821 {
 822         if (buffer_len(&c->input) < packet_get_maxsize())
 823                 FD_SET(c->sock, readset);
 824         if (buffer_len(&c->output) > 0)
 825                 FD_SET(c->sock, writeset);
 826 }
 827
 828 static u_int
 829 channel_tcpwinsz(void)
 830 {
 831         u_int32_t tcpwinsz;
 832         socklen_t optsz;
 833         int ret, sd;
 834         u_int maxlen;
 835
 836         /* If we are not on a socket return 128KB. */
 837         if (!packet_connection_is_on_socket())
 838                 return (128 * 1024);
 839
 840         tcpwinsz = 0;
 841         optsz = sizeof(tcpwinsz);
 842         sd = packet_get_connection_in();
 843         ret = getsockopt(sd, SOL_SOCKET, SO_RCVBUF, &tcpwinsz, &optsz);
 844
 845         /* Return no more than the maximum buffer size. */
 846         maxlen = buffer_get_max_len();
 847         if ((ret == 0) && tcpwinsz > maxlen)
 848                 tcpwinsz = maxlen;
 849         /* In case getsockopt() failed return a minimum. */
 850         if (tcpwinsz == 0)
 851                 tcpwinsz = CHAN_TCP_WINDOW_DEFAULT;
 852         debug2("tcpwinsz: %d for connection: %d", tcpwinsz, sd);
 853         return (tcpwinsz);
 854 }
 855
 856 static void
 857 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 858 {
 859         u_int limit;
 860
 861         /* Check buffer limits. */
 862         if (!c->tcpwinsz || c->dynamic_window > 0)
 863                 c->tcpwinsz = channel_tcpwinsz();
 864
 865         limit = MIN(compat20 ? c->remote_window : packet_get_maxsize(),
 866             2 * c->tcpwinsz);
 867
 868         if (c->istate == CHAN_INPUT_OPEN &&
 869             limit > 0 &&
 870             buffer_len(&c->input) < limit &&
 871             buffer_check_alloc(&c->input, CHAN_RBUF))
 872                 FD_SET(c->rfd, readset);
 873         if (c->ostate == CHAN_OUTPUT_OPEN ||
 874             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 875                 if (buffer_len(&c->output) > 0) {
 876                         FD_SET(c->wfd, writeset);
 877                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 878                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 879                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 880                                     c->self, c->efd, buffer_len(&c->extended));
 881                         else
 882                                 chan_obuf_empty(c);
 883                 }
 884         }
 885         /** XXX check close conditions, too */
 886         if (compat20 && c->efd != -1 &&
 887             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 888                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 889                     buffer_len(&c->extended) > 0)
 890                         FD_SET(c->efd, writeset);
 891                 else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
 892                     (c->extended_usage == CHAN_EXTENDED_READ ||
 893                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
 894                     buffer_len(&c->extended) < c->remote_window)
 895                         FD_SET(c->efd, readset);
 896         }
 897         /* XXX: What about efd? races? */
 898 }
 899
 900 /* ARGSUSED */
 901 static void
 902 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 903 {
 904         if (buffer_len(&c->input) == 0) {
 905                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 906                 packet_put_int(c->remote_id);
 907                 packet_send();
 908                 c->type = SSH_CHANNEL_CLOSED;
 909                 debug2("channel %d: closing after input drain.", c->self);
 910         }
 911 }
 912
 913 /* ARGSUSED */
 914 static void
 915 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 916 {
 917         if (buffer_len(&c->output) == 0)
 918                 chan_mark_dead(c);
 919         else
 920                 FD_SET(c->sock, writeset);
 921 }
 922
 923 /*
 924  * This is a special state for X11 authentication spoofing.  An opened X11
 925  * connection (when authentication spoofing is being done) remains in this
 926  * state until the first packet has been completely read.  The authentication
 927  * data in that packet is then substituted by the real data if it matches the
 928  * fake data, and the channel is put into normal mode.
 929  * XXX All this happens at the client side.
 930  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 931  */
 932 static int
 933 x11_open_helper(Buffer *b)
 934 {
 935         u_char *ucp;
 936         u_int proto_len, data_len;
 937
 938         /* Check if the fixed size part of the packet is in buffer. */
 939         if (buffer_len(b) < 12)
 940                 return 0;
 941
 942         /* Parse the lengths of variable-length fields. */
 943         ucp = buffer_ptr(b);
 944         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 945                 proto_len = 256 * ucp[6] + ucp[7];
 946                 data_len = 256 * ucp[8] + ucp[9];
 947         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 948                 proto_len = ucp[6] + 256 * ucp[7];
 949                 data_len = ucp[8] + 256 * ucp[9];
 950         } else {
 951                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 952                     ucp[0]);
 953                 return -1;
 954         }
 955
 956         /* Check if the whole packet is in buffer. */
 957         if (buffer_len(b) <
 958             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 959                 return 0;
 960
 961         /* Check if authentication protocol matches. */
 962         if (proto_len != strlen(x11_saved_proto) ||
 963             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 964                 debug2("X11 connection uses different authentication protocol.");
 965                 return -1;
 966         }
 967         /* Check if authentication data matches our fake data. */
 968         if (data_len != x11_fake_data_len ||
 969             timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
 970                 x11_fake_data, x11_fake_data_len) != 0) {
 971                 debug2("X11 auth data does not match fake data.");
 972                 return -1;
 973         }
 974         /* Check fake data length */
 975         if (x11_fake_data_len != x11_saved_data_len) {
 976                 error("X11 fake_data_len %d != saved_data_len %d",
 977                     x11_fake_data_len, x11_saved_data_len);
 978                 return -1;
 979         }
 980         /*
 981          * Received authentication protocol and data match
 982          * our fake data. Substitute the fake data with real
 983          * data.
 984          */
 985         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 986             x11_saved_data, x11_saved_data_len);
 987         return 1;
 988 }
 989
 990 static void
 991 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 992 {
 993         int ret = x11_open_helper(&c->output);
 994
 995         if (ret == 1) {
 996                 /* Start normal processing for the channel. */
 997                 c->type = SSH_CHANNEL_OPEN;
 998                 channel_pre_open_13(c, readset, writeset);
 999         } else if (ret == -1) {
1000                 /*
1001                  * We have received an X11 connection that has bad
1002                  * authentication information.
1003                  */
1004                 logit("X11 connection rejected because of wrong authentication.");
1005                 buffer_clear(&c->input);
1006                 buffer_clear(&c->output);
1007                 channel_close_fd(&c->sock);
1008                 c->sock = -1;
1009                 c->type = SSH_CHANNEL_CLOSED;
1010                 packet_start(SSH_MSG_CHANNEL_CLOSE);
1011                 packet_put_int(c->remote_id);
1012                 packet_send();
1013         }
1014 }
1015
1016 static void
1017 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
1018 {
1019         int ret = x11_open_helper(&c->output);
1020
1021         /* c->force_drain = 1; */
1022
1023         if (ret == 1) {
1024                 c->type = SSH_CHANNEL_OPEN;
1025                 channel_pre_open(c, readset, writeset);
1026         } else if (ret == -1) {
1027                 logit("X11 connection rejected because of wrong authentication.");
1028                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
1029                 chan_read_failed(c);
1030                 buffer_clear(&c->input);
1031                 chan_ibuf_empty(c);
1032                 buffer_clear(&c->output);
1033                 /* for proto v1, the peer will send an IEOF */
1034                 if (compat20)
1035                         chan_write_failed(c);
1036                 else
1037                         c->type = SSH_CHANNEL_OPEN;
1038                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
1039         }
1040 }
1041
1042 static void
1043 channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1044 {
1045         if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
1046             buffer_check_alloc(&c->input, CHAN_RBUF))
1047                 FD_SET(c->rfd, readset);
1048         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1049                 /* clear buffer immediately (discard any partial packet) */
1050                 buffer_clear(&c->input);
1051                 chan_ibuf_empty(c);
1052                 /* Start output drain. XXX just kill chan? */
1053                 chan_rcvd_oclose(c);
1054         }
1055         if (c->ostate == CHAN_OUTPUT_OPEN ||
1056             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
1057                 if (buffer_len(&c->output) > 0)
1058                         FD_SET(c->wfd, writeset);
1059                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
1060                         chan_obuf_empty(c);
1061         }
1062 }
1063
1064 /* try to decode a socks4 header */
1065 /* ARGSUSED */
1066 static int
1067 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1068 {
1069         char *p, *host;
1070         u_int len, have, i, found, need;
1071         char username[256];
1072         struct {
1073                 u_int8_t version;
1074                 u_int8_t command;
1075                 u_int16_t dest_port;
1076                 struct in_addr dest_addr;
1077         } s4_req, s4_rsp;
1078
1079         debug2("channel %d: decode socks4", c->self);
1080
1081         have = buffer_len(&c->input);
1082         len = sizeof(s4_req);
1083         if (have < len)
1084                 return 0;
1085         p = buffer_ptr(&c->input);
1086
1087         need = 1;
1088         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1089         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1090                 debug2("channel %d: socks4a request", c->self);
1091                 /* ... and needs an extra string (the hostname) */
1092                 need = 2;
1093         }
1094         /* Check for terminating NUL on the string(s) */
1095         for (found = 0, i = len; i < have; i++) {
1096                 if (p[i] == '\0') {
1097                         found++;
1098                         if (found == need)
1099                                 break;
1100                 }
1101                 if (i > 1024) {
1102                         /* the peer is probably sending garbage */
1103                         debug("channel %d: decode socks4: too long",
1104                             c->self);
1105                         return -1;
1106                 }
1107         }
1108         if (found < need)
1109                 return 0;
1110         buffer_get(&c->input, (char *)&s4_req.version, 1);
1111         buffer_get(&c->input, (char *)&s4_req.command, 1);
1112         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1113         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1114         have = buffer_len(&c->input);
1115         p = buffer_ptr(&c->input);
1116         len = strlen(p);
1117         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1118         len++;                                  /* trailing '\0' */
1119         if (len > have)
1120                 fatal("channel %d: decode socks4: len %d > have %d",
1121                     c->self, len, have);
1122         strlcpy(username, p, sizeof(username));
1123         buffer_consume(&c->input, len);
1124
1125         if (c->path != NULL) {
1126                 xfree(c->path);
1127                 c->path = NULL;
1128         }
1129         if (need == 1) {                        /* SOCKS4: one string */
1130                 host = inet_ntoa(s4_req.dest_addr);
1131                 c->path = xstrdup(host);
1132         } else {                                /* SOCKS4A: two strings */
1133                 have = buffer_len(&c->input);
1134                 p = buffer_ptr(&c->input);
1135                 len = strlen(p);
1136                 debug2("channel %d: decode socks4a: host %s/%d",
1137                     c->self, p, len);
1138                 len++;                          /* trailing '\0' */
1139                 if (len > have)
1140                         fatal("channel %d: decode socks4a: len %d > have %d",
1141                             c->self, len, have);
1142                 if (len > NI_MAXHOST) {
1143                         error("channel %d: hostname \"%.100s\" too long",
1144                             c->self, p);
1145                         return -1;
1146                 }
1147                 c->path = xstrdup(p);
1148                 buffer_consume(&c->input, len);
1149         }
1150         c->host_port = ntohs(s4_req.dest_port);
1151
1152         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1153             c->self, c->path, c->host_port, s4_req.command);
1154
1155         if (s4_req.command != 1) {
1156                 debug("channel %d: cannot handle: %s cn %d",
1157                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1158                 return -1;
1159         }
1160         s4_rsp.version = 0;                     /* vn: 0 for reply */
1161         s4_rsp.command = 90;                    /* cd: req granted */
1162         s4_rsp.dest_port = 0;                   /* ignored */
1163         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1164         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1165         return 1;
1166 }
1167
1168 /* try to decode a socks5 header */
1169 #define SSH_SOCKS5_AUTHDONE     0x1000
1170 #define SSH_SOCKS5_NOAUTH       0x00
1171 #define SSH_SOCKS5_IPV4         0x01
1172 #define SSH_SOCKS5_DOMAIN       0x03
1173 #define SSH_SOCKS5_IPV6         0x04
1174 #define SSH_SOCKS5_CONNECT      0x01
1175 #define SSH_SOCKS5_SUCCESS      0x00
1176
1177 /* ARGSUSED */
1178 static int
1179 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1180 {
1181         struct {
1182                 u_int8_t version;
1183                 u_int8_t command;
1184                 u_int8_t reserved;
1185                 u_int8_t atyp;
1186         } s5_req, s5_rsp;
1187         u_int16_t dest_port;
1188         u_char *p, dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1189         u_int have, need, i, found, nmethods, addrlen, af;
1190
1191         debug2("channel %d: decode socks5", c->self);
1192         p = buffer_ptr(&c->input);
1193         if (p[0] != 0x05)
1194                 return -1;
1195         have = buffer_len(&c->input);
1196         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1197                 /* format: ver | nmethods | methods */
1198                 if (have < 2)
1199                         return 0;
1200                 nmethods = p[1];
1201                 if (have < nmethods + 2)
1202                         return 0;
1203                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1204                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1205                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1206                                 found = 1;
1207                                 break;
1208                         }
1209                 }
1210                 if (!found) {
1211                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1212                             c->self);
1213                         return -1;
1214                 }
1215                 buffer_consume(&c->input, nmethods + 2);
1216                 buffer_put_char(&c->output, 0x05);              /* version */
1217                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1218                 FD_SET(c->sock, writeset);
1219                 c->flags |= SSH_SOCKS5_AUTHDONE;
1220                 debug2("channel %d: socks5 auth done", c->self);
1221                 return 0;                               /* need more */
1222         }
1223         debug2("channel %d: socks5 post auth", c->self);
1224         if (have < sizeof(s5_req)+1)
1225                 return 0;                       /* need more */
1226         memcpy(&s5_req, p, sizeof(s5_req));
1227         if (s5_req.version != 0x05 ||
1228             s5_req.command != SSH_SOCKS5_CONNECT ||
1229             s5_req.reserved != 0x00) {
1230                 debug2("channel %d: only socks5 connect supported", c->self);
1231                 return -1;
1232         }
1233         switch (s5_req.atyp){
1234         case SSH_SOCKS5_IPV4:
1235                 addrlen = 4;
1236                 af = AF_INET;
1237                 break;
1238         case SSH_SOCKS5_DOMAIN:
1239                 addrlen = p[sizeof(s5_req)];
1240                 af = -1;
1241                 break;
1242         case SSH_SOCKS5_IPV6:
1243                 addrlen = 16;
1244                 af = AF_INET6;
1245                 break;
1246         default:
1247                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1248                 return -1;
1249         }
1250         need = sizeof(s5_req) + addrlen + 2;
1251         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1252                 need++;
1253         if (have < need)
1254                 return 0;
1255         buffer_consume(&c->input, sizeof(s5_req));
1256         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1257                 buffer_consume(&c->input, 1);    /* host string length */
1258         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1259         buffer_get(&c->input, (char *)&dest_port, 2);
1260         dest_addr[addrlen] = '\0';
1261         if (c->path != NULL) {
1262                 xfree(c->path);
1263                 c->path = NULL;
1264         }
1265         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1266                 if (addrlen >= NI_MAXHOST) {
1267                         error("channel %d: dynamic request: socks5 hostname "
1268                             "\"%.100s\" too long", c->self, dest_addr);
1269                         return -1;
1270                 }
1271                 c->path = xstrdup(dest_addr);
1272         } else {
1273                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1274                         return -1;
1275                 c->path = xstrdup(ntop);
1276         }
1277         c->host_port = ntohs(dest_port);
1278
1279         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1280             c->self, c->path, c->host_port, s5_req.command);
1281
1282         s5_rsp.version = 0x05;
1283         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1284         s5_rsp.reserved = 0;                    /* ignored */
1285         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1286         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1287         dest_port = 0;                          /* ignored */
1288
1289         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1290         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1291         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1292         return 1;
1293 }
1294
1295 Channel *
1296 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1297     int in, int out)
1298 {
1299         Channel *c;
1300
1301         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1302             port_to_connect);
1303
1304         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1305             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1306             0, "stdio-forward", /*nonblock*/0);
1307
1308         c->path = xstrdup(host_to_connect);
1309         c->host_port = port_to_connect;
1310         c->listening_port = 0;
1311         c->force_drain = 1;
1312
1313         channel_register_fds(c, in, out, -1, 0, 1, 0);
1314         port_open_helper(c, "direct-tcpip");
1315
1316         return c;
1317 }
1318
1319 /* dynamic port forwarding */
1320 static void
1321 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1322 {
1323         u_char *p;
1324         u_int have;
1325         int ret;
1326
1327         have = buffer_len(&c->input);
1328         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1329         /* buffer_dump(&c->input); */
1330         /* check if the fixed size part of the packet is in buffer. */
1331         if (have < 3) {
1332                 /* need more */
1333                 FD_SET(c->sock, readset);
1334                 return;
1335         }
1336         /* try to guess the protocol */
1337         p = buffer_ptr(&c->input);
1338         switch (p[0]) {
1339         case 0x04:
1340                 ret = channel_decode_socks4(c, readset, writeset);
1341                 break;
1342         case 0x05:
1343                 ret = channel_decode_socks5(c, readset, writeset);
1344                 break;
1345         default:
1346                 ret = -1;
1347                 break;
1348         }
1349         if (ret < 0) {
1350                 chan_mark_dead(c);
1351         } else if (ret == 0) {
1352                 debug2("channel %d: pre_dynamic: need more", c->self);
1353                 /* need more */
1354                 FD_SET(c->sock, readset);
1355         } else {
1356                 /* switch to the next state */
1357                 c->type = SSH_CHANNEL_OPENING;
1358                 port_open_helper(c, "direct-tcpip");
1359         }
1360 }
1361
1362 /* This is our fake X11 server socket. */
1363 /* ARGSUSED */
1364 static void
1365 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1366 {
1367         Channel *nc;
1368         struct sockaddr_storage addr;
1369         int newsock;
1370         socklen_t addrlen;
1371         char buf[16384], *remote_ipaddr;
1372         int remote_port;
1373
1374         if (FD_ISSET(c->sock, readset)) {
1375                 debug("X11 connection requested.");
1376                 addrlen = sizeof(addr);
1377                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1378                 if (c->single_connection) {
1379                         debug2("single_connection: closing X11 listener.");
1380                         channel_close_fd(&c->sock);
1381                         chan_mark_dead(c);
1382                 }
1383                 if (newsock < 0) {
1384                         error("accept: %.100s", strerror(errno));
1385                         if (errno == EMFILE || errno == ENFILE)
1386                                 c->notbefore = time(NULL) + 1;
1387                         return;
1388                 }
1389                 set_nodelay(newsock);
1390                 remote_ipaddr = get_peer_ipaddr(newsock);
1391                 remote_port = get_peer_port(newsock);
1392                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1393                     remote_ipaddr, remote_port);
1394
1395                 nc = channel_new("accepted x11 socket",
1396                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1397                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1398                 if (compat20) {
1399                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1400                         packet_put_cstring("x11");
1401                         packet_put_int(nc->self);
1402                         packet_put_int(nc->local_window_max);
1403                         packet_put_int(nc->local_maxpacket);
1404                         /* originator ipaddr and port */
1405                         packet_put_cstring(remote_ipaddr);
1406                         if (datafellows & SSH_BUG_X11FWD) {
1407                                 debug2("ssh2 x11 bug compat mode");
1408                         } else {
1409                                 packet_put_int(remote_port);
1410                         }
1411                         packet_send();
1412                 } else {
1413                         packet_start(SSH_SMSG_X11_OPEN);
1414                         packet_put_int(nc->self);
1415                         if (packet_get_protocol_flags() &
1416                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1417                                 packet_put_cstring(buf);
1418                         packet_send();
1419                 }
1420                 xfree(remote_ipaddr);
1421         }
1422 }
1423
1424 static void
1425 port_open_helper(Channel *c, char *rtype)
1426 {
1427         int direct;
1428         char buf[1024];
1429         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1430         int remote_port = get_peer_port(c->sock);
1431
1432         if (remote_port == -1) {
1433                 /* Fake addr/port to appease peers that validate it (Tectia) */
1434                 xfree(remote_ipaddr);
1435                 remote_ipaddr = xstrdup("127.0.0.1");
1436                 remote_port = 65535;
1437         }
1438
1439         direct = (strcmp(rtype, "direct-tcpip") == 0);
1440
1441         snprintf(buf, sizeof buf,
1442             "%s: listening port %d for %.100s port %d, "
1443             "connect from %.200s port %d",
1444             rtype, c->listening_port, c->path, c->host_port,
1445             remote_ipaddr, remote_port);
1446
1447         xfree(c->remote_name);
1448         c->remote_name = xstrdup(buf);
1449
1450         if (compat20) {
1451                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1452                 packet_put_cstring(rtype);
1453                 packet_put_int(c->self);
1454                 packet_put_int(c->local_window_max);
1455                 packet_put_int(c->local_maxpacket);
1456                 if (direct) {
1457                         /* target host, port */
1458                         packet_put_cstring(c->path);
1459                         packet_put_int(c->host_port);
1460                 } else {
1461                         /* listen address, port */
1462                         packet_put_cstring(c->path);
1463                         packet_put_int(c->listening_port);
1464                 }
1465                 /* originator host and port */
1466                 packet_put_cstring(remote_ipaddr);
1467                 packet_put_int((u_int)remote_port);
1468                 packet_send();
1469         } else {
1470                 packet_start(SSH_MSG_PORT_OPEN);
1471                 packet_put_int(c->self);
1472                 packet_put_cstring(c->path);
1473                 packet_put_int(c->host_port);
1474                 if (packet_get_protocol_flags() &
1475                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1476                         packet_put_cstring(c->remote_name);
1477                 packet_send();
1478         }
1479         xfree(remote_ipaddr);
1480 }
1481
1482 static void
1483 channel_set_reuseaddr(int fd)
1484 {
1485         int on = 1;
1486
1487         /*
1488          * Set socket options.
1489          * Allow local port reuse in TIME_WAIT.
1490          */
1491         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1492                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1493 }
1494
1495 /*
1496  * This socket is listening for connections to a forwarded TCP/IP port.
1497  */
1498 /* ARGSUSED */
1499 static void
1500 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1501 {
1502         Channel *nc;
1503         struct sockaddr_storage addr;
1504         int newsock, nextstate;
1505         socklen_t addrlen;
1506         char *rtype;
1507
1508         if (FD_ISSET(c->sock, readset)) {
1509                 debug("Connection to port %d forwarding "
1510                     "to %.100s port %d requested.",
1511                     c->listening_port, c->path, c->host_port);
1512
1513                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1514                         nextstate = SSH_CHANNEL_OPENING;
1515                         rtype = "forwarded-tcpip";
1516                 } else {
1517                         if (c->host_port == 0) {
1518                                 nextstate = SSH_CHANNEL_DYNAMIC;
1519                                 rtype = "dynamic-tcpip";
1520                         } else {
1521                                 nextstate = SSH_CHANNEL_OPENING;
1522                                 rtype = "direct-tcpip";
1523                         }
1524                 }
1525
1526                 addrlen = sizeof(addr);
1527                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1528                 if (newsock < 0) {
1529                         error("accept: %.100s", strerror(errno));
1530                         if (errno == EMFILE || errno == ENFILE)
1531                                 c->notbefore = time(NULL) + 1;
1532                         return;
1533                 }
1534                 set_nodelay(newsock);
1535                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1536                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1537                 nc->listening_port = c->listening_port;
1538                 nc->host_port = c->host_port;
1539                 if (c->path != NULL)
1540                         nc->path = xstrdup(c->path);
1541
1542                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1543                         port_open_helper(nc, rtype);
1544         }
1545 }
1546
1547 /*
1548  * This is the authentication agent socket listening for connections from
1549  * clients.
1550  */
1551 /* ARGSUSED */
1552 static void
1553 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1554 {
1555         Channel *nc;
1556         int newsock;
1557         struct sockaddr_storage addr;
1558         socklen_t addrlen;
1559
1560         if (FD_ISSET(c->sock, readset)) {
1561                 addrlen = sizeof(addr);
1562                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1563                 if (newsock < 0) {
1564                         error("accept from auth socket: %.100s",
1565                             strerror(errno));
1566                         if (errno == EMFILE || errno == ENFILE)
1567                                 c->notbefore = time(NULL) + 1;
1568                         return;
1569                 }
1570                 nc = channel_new("accepted auth socket",
1571                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1572                     c->local_window_max, c->local_maxpacket,
1573                     0, "accepted auth socket", 1);
1574                 if (compat20) {
1575                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1576                         packet_put_cstring("auth-agent@openssh.com");
1577                         packet_put_int(nc->self);
1578                         packet_put_int(c->local_window_max);
1579                         packet_put_int(c->local_maxpacket);
1580                 } else {
1581                         packet_start(SSH_SMSG_AGENT_OPEN);
1582                         packet_put_int(nc->self);
1583                 }
1584                 packet_send();
1585         }
1586 }
1587
1588 /* ARGSUSED */
1589 static void
1590 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1591 {
1592         int err = 0, sock;
1593         socklen_t sz = sizeof(err);
1594
1595         if (FD_ISSET(c->sock, writeset)) {
1596                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1597                         err = errno;
1598                         error("getsockopt SO_ERROR failed");
1599                 }
1600                 if (err == 0) {
1601                         debug("channel %d: connected to %s port %d",
1602                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1603                         channel_connect_ctx_free(&c->connect_ctx);
1604                         c->type = SSH_CHANNEL_OPEN;
1605                         if (compat20) {
1606                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1607                                 packet_put_int(c->remote_id);
1608                                 packet_put_int(c->self);
1609                                 packet_put_int(c->local_window);
1610                                 packet_put_int(c->local_maxpacket);
1611                         } else {
1612                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1613                                 packet_put_int(c->remote_id);
1614                                 packet_put_int(c->self);
1615                         }
1616                 } else {
1617                         debug("channel %d: connection failed: %s",
1618                             c->self, strerror(err));
1619                         /* Try next address, if any */
1620                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1621                                 close(c->sock);
1622                                 c->sock = c->rfd = c->wfd = sock;
1623                                 channel_max_fd = channel_find_maxfd();
1624                                 return;
1625                         }
1626                         /* Exhausted all addresses */
1627                         error("connect_to %.100s port %d: failed.",
1628                             c->connect_ctx.host, c->connect_ctx.port);
1629                         channel_connect_ctx_free(&c->connect_ctx);
1630                         if (compat20) {
1631                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1632                                 packet_put_int(c->remote_id);
1633                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1634                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1635                                         packet_put_cstring(strerror(err));
1636                                         packet_put_cstring("");
1637                                 }
1638                         } else {
1639                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1640                                 packet_put_int(c->remote_id);
1641                         }
1642                         chan_mark_dead(c);
1643                 }
1644                 packet_send();
1645         }
1646 }
1647
1648 /* ARGSUSED */
1649 static int
1650 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1651 {
1652         char buf[CHAN_RBUF];
1653         int len, force;
1654
1655         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1656         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1657                 errno = 0;
1658                 len = read(c->rfd, buf, sizeof(buf));
1659                 if (len < 0 && (errno == EINTR ||
1660                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1661                         return 1;
1662 #ifndef PTY_ZEROREAD
1663                 if (len <= 0) {
1664 #else
1665                 if ((!c->isatty && len <= 0) ||
1666                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1667 #endif
1668                         debug2("channel %d: read<=0 rfd %d len %d",
1669                             c->self, c->rfd, len);
1670                         if (c->type != SSH_CHANNEL_OPEN) {
1671                                 debug2("channel %d: not open", c->self);
1672                                 chan_mark_dead(c);
1673                                 return -1;
1674                         } else if (compat13) {
1675                                 buffer_clear(&c->output);
1676                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1677                                 debug2("channel %d: input draining.", c->self);
1678                         } else {
1679                                 chan_read_failed(c);
1680                         }
1681                         return -1;
1682                 }
1683                 if (c->input_filter != NULL) {
1684                         if (c->input_filter(c, buf, len) == -1) {
1685                                 debug2("channel %d: filter stops", c->self);
1686                                 chan_read_failed(c);
1687                         }
1688                 } else if (c->datagram) {
1689                         buffer_put_string(&c->input, buf, len);
1690                 } else {
1691                         buffer_append(&c->input, buf, len);
1692                 }
1693         }
1694         return 1;
1695 }
1696
1697 /* ARGSUSED */
1698 static int
1699 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1700 {
1701         struct termios tio;
1702         u_char *data = NULL, *buf;
1703         u_int dlen, olen = 0;
1704         int len;
1705
1706         /* Send buffered output data to the socket. */
1707         if (c->wfd != -1 &&
1708             FD_ISSET(c->wfd, writeset) &&
1709             buffer_len(&c->output) > 0) {
1710                 olen = buffer_len(&c->output);
1711                 if (c->output_filter != NULL) {
1712                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1713                                 debug2("channel %d: filter stops", c->self);
1714                                 if (c->type != SSH_CHANNEL_OPEN)
1715                                         chan_mark_dead(c);
1716                                 else
1717                                         chan_write_failed(c);
1718                                 return -1;
1719                         }
1720                 } else if (c->datagram) {
1721                         buf = data = buffer_get_string(&c->output, &dlen);
1722                 } else {
1723                         buf = data = buffer_ptr(&c->output);
1724                         dlen = buffer_len(&c->output);
1725                 }
1726
1727                 if (c->datagram) {
1728                         /* ignore truncated writes, datagrams might get lost */
1729                         len = write(c->wfd, buf, dlen);
1730                         xfree(data);
1731                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1732                             errno == EWOULDBLOCK))
1733                                 return 1;
1734                         if (len <= 0) {
1735                                 if (c->type != SSH_CHANNEL_OPEN)
1736                                         chan_mark_dead(c);
1737                                 else
1738                                         chan_write_failed(c);
1739                                 return -1;
1740                         }
1741                         goto out;
1742                 }
1743 #ifdef _AIX
1744                 /* XXX: Later AIX versions can't push as much data to tty */
1745                 if (compat20 && c->wfd_isatty)
1746                         dlen = MIN(dlen, 8*1024);
1747 #endif
1748
1749                 len = write(c->wfd, buf, dlen);
1750                 if (len < 0 &&
1751                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1752                         return 1;
1753                 if (len <= 0) {
1754                         if (c->type != SSH_CHANNEL_OPEN) {
1755                                 debug2("channel %d: not open", c->self);
1756                                 chan_mark_dead(c);
1757                                 return -1;
1758                         } else if (compat13) {
1759                                 buffer_clear(&c->output);
1760                                 debug2("channel %d: input draining.", c->self);
1761                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1762                         } else {
1763                                 chan_write_failed(c);
1764                         }
1765                         return -1;
1766                 }
1767 #ifndef BROKEN_TCGETATTR_ICANON
1768                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1769                         if (tcgetattr(c->wfd, &tio) == 0 &&
1770                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1771                                 /*
1772                                  * Simulate echo to reduce the impact of
1773                                  * traffic analysis. We need to match the
1774                                  * size of a SSH2_MSG_CHANNEL_DATA message
1775                                  * (4 byte channel id + buf)
1776                                  */
1777                                 packet_send_ignore(4 + len);
1778                                 packet_send();
1779                         }
1780                 }
1781 #endif
1782                 buffer_consume(&c->output, len);
1783         }
1784  out:
1785         if (compat20 && olen > 0)
1786                 c->local_consumed += olen - buffer_len(&c->output);
1787         return 1;
1788 }
1789
1790 static int
1791 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1792 {
1793         char buf[CHAN_RBUF];
1794         int len;
1795
1796 /** XXX handle drain efd, too */
1797         if (c->efd != -1) {
1798                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1799                     FD_ISSET(c->efd, writeset) &&
1800                     buffer_len(&c->extended) > 0) {
1801                         len = write(c->efd, buffer_ptr(&c->extended),
1802                             buffer_len(&c->extended));
1803                         debug2("channel %d: written %d to efd %d",
1804                             c->self, len, c->efd);
1805                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1806                             errno == EWOULDBLOCK))
1807                                 return 1;
1808                         if (len <= 0) {
1809                                 debug2("channel %d: closing write-efd %d",
1810                                     c->self, c->efd);
1811                                 channel_close_fd(&c->efd);
1812                         } else {
1813                                 buffer_consume(&c->extended, len);
1814                                 c->local_consumed += len;
1815                         }
1816                 } else if (c->efd != -1 &&
1817                     (c->extended_usage == CHAN_EXTENDED_READ ||
1818                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
1819                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1820                         len = read(c->efd, buf, sizeof(buf));
1821                         debug2("channel %d: read %d from efd %d",
1822                             c->self, len, c->efd);
1823                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1824                             errno == EWOULDBLOCK) && !c->detach_close)))
1825                                 return 1;
1826                         if (len <= 0) {
1827                                 debug2("channel %d: closing read-efd %d",
1828                                     c->self, c->efd);
1829                                 channel_close_fd(&c->efd);
1830                         } else {
1831                                 if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
1832                                         debug3("channel %d: discard efd",
1833                                             c->self);
1834                                 } else
1835                                         buffer_append(&c->extended, buf, len);
1836                         }
1837                 }
1838         }
1839         return 1;
1840 }
1841
1842 static int
1843 channel_check_window(Channel *c)
1844 {
1845         if (c->type == SSH_CHANNEL_OPEN &&
1846             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1847             ((c->local_window_max - c->local_window >
1848             c->local_maxpacket*3) ||
1849             c->local_window < c->local_window_max/2) &&
1850             c->local_consumed > 0) {
1851                 u_int addition = 0;
1852
1853                 /* Adjust max window size if we are in a dynamic environment. */
1854                 if (c->dynamic_window && c->tcpwinsz > c->local_window_max) {
1855                         /*
1856                          * Grow the window somewhat aggressively to maintain
1857                          * pressure.
1858                          */
1859                         addition = 1.5 * (c->tcpwinsz - c->local_window_max);
1860                         c->local_window_max += addition;
1861                 }
1862                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1863                 packet_put_int(c->remote_id);
1864                 packet_put_int(c->local_consumed + addition);
1865                 packet_send();
1866                 debug2("channel %d: window %d sent adjust %d",
1867                     c->self, c->local_window,
1868                     c->local_consumed);
1869                 c->local_window += c->local_consumed + addition;
1870                 c->local_consumed = 0;
1871         }
1872         return 1;
1873 }
1874
1875 static void
1876 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1877 {
1878         channel_handle_rfd(c, readset, writeset);
1879         channel_handle_wfd(c, readset, writeset);
1880         if (!compat20)
1881                 return;
1882         channel_handle_efd(c, readset, writeset);
1883         channel_check_window(c);
1884 }
1885
1886 static u_int
1887 read_mux(Channel *c, u_int need)
1888 {
1889         char buf[CHAN_RBUF];
1890         int len;
1891         u_int rlen;
1892
1893         if (buffer_len(&c->input) < need) {
1894                 rlen = need - buffer_len(&c->input);
1895                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1896                 if (len <= 0) {
1897                         if (errno != EINTR && errno != EAGAIN) {
1898                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1899                                     c->self, c->rfd, len);
1900                                 chan_read_failed(c);
1901                                 return 0;
1902                         }
1903                 } else
1904                         buffer_append(&c->input, buf, len);
1905         }
1906         return buffer_len(&c->input);
1907 }
1908
1909 static void
1910 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1911 {
1912         u_int need;
1913         ssize_t len;
1914
1915         if (!compat20)
1916                 fatal("%s: entered with !compat20", __func__);
1917
1918         if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
1919             (c->istate == CHAN_INPUT_OPEN ||
1920             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1921                 /*
1922                  * Don't not read past the precise end of packets to
1923                  * avoid disrupting fd passing.
1924                  */
1925                 if (read_mux(c, 4) < 4) /* read header */
1926                         return;
1927                 need = get_u32(buffer_ptr(&c->input));
1928 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1929                 if (need > CHANNEL_MUX_MAX_PACKET) {
1930                         debug2("channel %d: packet too big %u > %u",
1931                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1932                         chan_rcvd_oclose(c);
1933                         return;
1934                 }
1935                 if (read_mux(c, need + 4) < need + 4) /* read body */
1936                         return;
1937                 if (c->mux_rcb(c) != 0) {
1938                         debug("channel %d: mux_rcb failed", c->self);
1939                         chan_mark_dead(c);
1940                         return;
1941                 }
1942         }
1943
1944         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1945             buffer_len(&c->output) > 0) {
1946                 len = write(c->wfd, buffer_ptr(&c->output),
1947                     buffer_len(&c->output));
1948                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1949                         return;
1950                 if (len <= 0) {
1951                         chan_mark_dead(c);
1952                         return;
1953                 }
1954                 buffer_consume(&c->output, len);
1955         }
1956 }
1957
1958 static void
1959 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1960 {
1961         Channel *nc;
1962         struct sockaddr_storage addr;
1963         socklen_t addrlen;
1964         int newsock;
1965         uid_t euid;
1966         gid_t egid;
1967
1968         if (!FD_ISSET(c->sock, readset))
1969                 return;
1970
1971         debug("multiplexing control connection");
1972
1973         /*
1974          * Accept connection on control socket
1975          */
1976         memset(&addr, 0, sizeof(addr));
1977         addrlen = sizeof(addr);
1978         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1979             &addrlen)) == -1) {
1980                 error("%s accept: %s", __func__, strerror(errno));
1981                 if (errno == EMFILE || errno == ENFILE)
1982                         c->notbefore = time(NULL) + 1;
1983                 return;
1984         }
1985
1986         if (getpeereid(newsock, &euid, &egid) < 0) {
1987                 error("%s getpeereid failed: %s", __func__,
1988                     strerror(errno));
1989                 close(newsock);
1990                 return;
1991         }
1992         if ((euid != 0) && (getuid() != euid)) {
1993                 error("multiplex uid mismatch: peer euid %u != uid %u",
1994                     (u_int)euid, (u_int)getuid());
1995                 close(newsock);
1996                 return;
1997         }
1998         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
1999             newsock, newsock, -1, c->local_window_max,
2000             c->local_maxpacket, 0, "mux-control", 1);
2001         nc->mux_rcb = c->mux_rcb;
2002         debug3("%s: new mux channel %d fd %d", __func__,
2003             nc->self, nc->sock);
2004         /* establish state */
2005         nc->mux_rcb(nc);
2006         /* mux state transitions must not elicit protocol messages */
2007         nc->flags |= CHAN_LOCAL;
2008 }
2009
2010 /* ARGSUSED */
2011 static void
2012 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
2013 {
2014         int len;
2015
2016         /* Send buffered output data to the socket. */
2017         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
2018                 len = write(c->sock, buffer_ptr(&c->output),
2019                             buffer_len(&c->output));
2020                 if (len <= 0)
2021                         buffer_clear(&c->output);
2022                 else
2023                         buffer_consume(&c->output, len);
2024         }
2025 }
2026
2027 static void
2028 channel_handler_init_20(void)
2029 {
2030         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2031         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2032         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2033         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
2034         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2035         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2036         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2037         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2038         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
2039         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
2040
2041         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2042         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2043         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
2044         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2045         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2046         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2047         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2048         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
2049         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
2050 }
2051
2052 static void
2053 channel_handler_init_13(void)
2054 {
2055         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
2056         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
2057         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2058         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2059         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2060         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
2061         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
2062         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2063         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2064
2065         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2066         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2067         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2068         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2069         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
2070         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2071         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2072 }
2073
2074 static void
2075 channel_handler_init_15(void)
2076 {
2077         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2078         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2079         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2080         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2081         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2082         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2083         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2084
2085         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2086         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2087         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2088         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2089         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2090         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2091 }
2092
2093 static void
2094 channel_handler_init(void)
2095 {
2096         int i;
2097
2098         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2099                 channel_pre[i] = NULL;
2100                 channel_post[i] = NULL;
2101         }
2102         if (compat20)
2103                 channel_handler_init_20();
2104         else if (compat13)
2105                 channel_handler_init_13();
2106         else
2107                 channel_handler_init_15();
2108 }
2109
2110 /* gc dead channels */
2111 static void
2112 channel_garbage_collect(Channel *c)
2113 {
2114         if (c == NULL)
2115                 return;
2116         if (c->detach_user != NULL) {
2117                 if (!chan_is_dead(c, c->detach_close))
2118                         return;
2119                 debug2("channel %d: gc: notify user", c->self);
2120                 c->detach_user(c->self, NULL);
2121                 /* if we still have a callback */
2122                 if (c->detach_user != NULL)
2123                         return;
2124                 debug2("channel %d: gc: user detached", c->self);
2125         }
2126         if (!chan_is_dead(c, 1))
2127                 return;
2128         debug2("channel %d: garbage collecting", c->self);
2129         channel_free(c);
2130 }
2131
2132 static void
2133 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
2134     time_t *unpause_secs)
2135 {
2136         static int did_init = 0;
2137         u_int i, oalloc;
2138         Channel *c;
2139         time_t now;
2140
2141         if (!did_init) {
2142                 channel_handler_init();
2143                 did_init = 1;
2144         }
2145         now = time(NULL);
2146         if (unpause_secs != NULL)
2147                 *unpause_secs = 0;
2148         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2149                 c = channels[i];
2150                 if (c == NULL)
2151                         continue;
2152                 if (c->delayed) {
2153                         if (ftab == channel_pre)
2154                                 c->delayed = 0;
2155                         else
2156                                 continue;
2157                 }
2158                 if (ftab[c->type] != NULL) {
2159                         /*
2160                          * Run handlers that are not paused.
2161                          */
2162                         if (c->notbefore <= now)
2163                                 (*ftab[c->type])(c, readset, writeset);
2164                         else if (unpause_secs != NULL) {
2165                                 /*
2166                                  * Collect the time that the earliest
2167                                  * channel comes off pause.
2168                                  */
2169                                 debug3("%s: chan %d: skip for %d more seconds",
2170                                     __func__, c->self,
2171                                     (int)(c->notbefore - now));
2172                                 if (*unpause_secs == 0 ||
2173                                     (c->notbefore - now) < *unpause_secs)
2174                                         *unpause_secs = c->notbefore - now;
2175                         }
2176                 }
2177                 channel_garbage_collect(c);
2178         }
2179         if (unpause_secs != NULL && *unpause_secs != 0)
2180                 debug3("%s: first channel unpauses in %d seconds",
2181                     __func__, (int)*unpause_secs);
2182 }
2183
2184 /*
2185  * Allocate/update select bitmasks and add any bits relevant to channels in
2186  * select bitmasks.
2187  */
2188 void
2189 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2190     u_int *nallocp, time_t *minwait_secs, int rekeying)
2191 {
2192         u_int n, sz, nfdset;
2193
2194         n = MAX(*maxfdp, channel_max_fd);
2195
2196         nfdset = howmany(n+1, NFDBITS);
2197         /* Explicitly test here, because xrealloc isn't always called */
2198         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
2199                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2200         sz = nfdset * sizeof(fd_mask);
2201
2202         /* perhaps check sz < nalloc/2 and shrink? */
2203         if (*readsetp == NULL || sz > *nallocp) {
2204                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2205                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2206                 *nallocp = sz;
2207         }
2208         *maxfdp = n;
2209         memset(*readsetp, 0, sz);
2210         memset(*writesetp, 0, sz);
2211
2212         if (!rekeying)
2213                 channel_handler(channel_pre, *readsetp, *writesetp,
2214                     minwait_secs);
2215 }
2216
2217 /*
2218  * After select, perform any appropriate operations for channels which have
2219  * events pending.
2220  */
2221 void
2222 channel_after_select(fd_set *readset, fd_set *writeset)
2223 {
2224         channel_handler(channel_post, readset, writeset, NULL);
2225 }
2226
2227
2228 /* If there is data to send to the connection, enqueue some of it now. */
2229 void
2230 channel_output_poll(void)
2231 {
2232         Channel *c;
2233         u_int i, len;
2234
2235         for (i = 0; i < channels_alloc; i++) {
2236                 c = channels[i];
2237                 if (c == NULL)
2238                         continue;
2239
2240                 /*
2241                  * We are only interested in channels that can have buffered
2242                  * incoming data.
2243                  */
2244                 if (compat13) {
2245                         if (c->type != SSH_CHANNEL_OPEN &&
2246                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2247                                 continue;
2248                 } else {
2249                         if (c->type != SSH_CHANNEL_OPEN)
2250                                 continue;
2251                 }
2252                 if (compat20 &&
2253                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2254                         /* XXX is this true? */
2255                         debug3("channel %d: will not send data after close", c->self);
2256                         continue;
2257                 }
2258
2259                 /* Get the amount of buffered data for this channel. */
2260                 if ((c->istate == CHAN_INPUT_OPEN ||
2261                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2262                     (len = buffer_len(&c->input)) > 0) {
2263                         if (c->datagram) {
2264                                 if (len > 0) {
2265                                         u_char *data;
2266                                         u_int dlen;
2267
2268                                         data = buffer_get_string(&c->input,
2269                                             &dlen);
2270                                         if (dlen > c->remote_window ||
2271                                             dlen > c->remote_maxpacket) {
2272                                                 debug("channel %d: datagram "
2273                                                     "too big for channel",
2274                                                     c->self);
2275                                                 xfree(data);
2276                                                 continue;
2277                                         }
2278                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2279                                         packet_put_int(c->remote_id);
2280                                         packet_put_string(data, dlen);
2281                                         packet_send();
2282                                         c->remote_window -= dlen + 4;
2283                                         xfree(data);
2284                                 }
2285                                 continue;
2286                         }
2287                         /*
2288                          * Send some data for the other side over the secure
2289                          * connection.
2290                          */
2291                         if (compat20) {
2292                                 if (len > c->remote_window)
2293                                         len = c->remote_window;
2294                                 if (len > c->remote_maxpacket)
2295                                         len = c->remote_maxpacket;
2296                         } else {
2297                                 if (packet_is_interactive()) {
2298                                         if (len > 1024)
2299                                                 len = 512;
2300                                 } else {
2301                                         /* Keep the packets at reasonable size. */
2302                                         if (len > packet_get_maxsize()/2)
2303                                                 len = packet_get_maxsize()/2;
2304                                 }
2305                         }
2306                         if (len > 0) {
2307                                 packet_start(compat20 ?
2308                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2309                                 packet_put_int(c->remote_id);
2310                                 packet_put_string(buffer_ptr(&c->input), len);
2311                                 packet_send();
2312                                 buffer_consume(&c->input, len);
2313                                 c->remote_window -= len;
2314                         }
2315                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2316                         if (compat13)
2317                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2318                         /*
2319                          * input-buffer is empty and read-socket shutdown:
2320                          * tell peer, that we will not send more data: send IEOF.
2321                          * hack for extended data: delay EOF if EFD still in use.
2322                          */
2323                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2324                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2325                                     c->self, c->efd, buffer_len(&c->extended));
2326                         else
2327                                 chan_ibuf_empty(c);
2328                 }
2329                 /* Send extended data, i.e. stderr */
2330                 if (compat20 &&
2331                     !(c->flags & CHAN_EOF_SENT) &&
2332                     c->remote_window > 0 &&
2333                     (len = buffer_len(&c->extended)) > 0 &&
2334                     c->extended_usage == CHAN_EXTENDED_READ) {
2335                         debug2("channel %d: rwin %u elen %u euse %d",
2336                             c->self, c->remote_window, buffer_len(&c->extended),
2337                             c->extended_usage);
2338                         if (len > c->remote_window)
2339                                 len = c->remote_window;
2340                         if (len > c->remote_maxpacket)
2341                                 len = c->remote_maxpacket;
2342                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2343                         packet_put_int(c->remote_id);
2344                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2345                         packet_put_string(buffer_ptr(&c->extended), len);
2346                         packet_send();
2347                         buffer_consume(&c->extended, len);
2348                         c->remote_window -= len;
2349                         debug2("channel %d: sent ext data %d", c->self, len);
2350                 }
2351         }
2352 }
2353
2354
2355 /* -- protocol input */
2356
2357 /* ARGSUSED */
2358 void
2359 channel_input_data(int type, u_int32_t seq, void *ctxt)
2360 {
2361         int id;
2362         char *data;
2363         u_int data_len, win_len;
2364         Channel *c;
2365
2366         /* Get the channel number and verify it. */
2367         id = packet_get_int();
2368         c = channel_lookup(id);
2369         if (c == NULL)
2370                 packet_disconnect("Received data for nonexistent channel %d.", id);
2371
2372         /* Ignore any data for non-open channels (might happen on close) */
2373         if (c->type != SSH_CHANNEL_OPEN &&
2374             c->type != SSH_CHANNEL_X11_OPEN)
2375                 return;
2376
2377         /* Get the data. */
2378         data = packet_get_string_ptr(&data_len);
2379         win_len = data_len;
2380         if (c->datagram)
2381                 win_len += 4;  /* string length header */
2382
2383         /*
2384          * Ignore data for protocol > 1.3 if output end is no longer open.
2385          * For protocol 2 the sending side is reducing its window as it sends
2386          * data, so we must 'fake' consumption of the data in order to ensure
2387          * that window updates are sent back.  Otherwise the connection might
2388          * deadlock.
2389          */
2390         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2391                 if (compat20) {
2392                         c->local_window -= win_len;
2393                         c->local_consumed += win_len;
2394                 }
2395                 return;
2396         }
2397
2398         if (compat20) {
2399                 if (win_len > c->local_maxpacket) {
2400                         logit("channel %d: rcvd big packet %d, maxpack %d",
2401                             c->self, win_len, c->local_maxpacket);
2402                 }
2403                 if (win_len > c->local_window) {
2404                         logit("channel %d: rcvd too much data %d, win %d",
2405                             c->self, win_len, c->local_window);
2406                         return;
2407                 }
2408                 c->local_window -= win_len;
2409         }
2410         if (c->datagram)
2411                 buffer_put_string(&c->output, data, data_len);
2412         else
2413                 buffer_append(&c->output, data, data_len);
2414         packet_check_eom();
2415 }
2416
2417 /* ARGSUSED */
2418 void
2419 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2420 {
2421         int id;
2422         char *data;
2423         u_int data_len, tcode;
2424         Channel *c;
2425
2426         /* Get the channel number and verify it. */
2427         id = packet_get_int();
2428         c = channel_lookup(id);
2429
2430         if (c == NULL)
2431                 packet_disconnect("Received extended_data for bad channel %d.", id);
2432         if (c->type != SSH_CHANNEL_OPEN) {
2433                 logit("channel %d: ext data for non open", id);
2434                 return;
2435         }
2436         if (c->flags & CHAN_EOF_RCVD) {
2437                 if (datafellows & SSH_BUG_EXTEOF)
2438                         debug("channel %d: accepting ext data after eof", id);
2439                 else
2440                         packet_disconnect("Received extended_data after EOF "
2441                             "on channel %d.", id);
2442         }
2443         tcode = packet_get_int();
2444         if (c->efd == -1 ||
2445             c->extended_usage != CHAN_EXTENDED_WRITE ||
2446             tcode != SSH2_EXTENDED_DATA_STDERR) {
2447                 logit("channel %d: bad ext data", c->self);
2448                 return;
2449         }
2450         data = packet_get_string(&data_len);
2451         packet_check_eom();
2452         if (data_len > c->local_window) {
2453                 logit("channel %d: rcvd too much extended_data %d, win %d",
2454                     c->self, data_len, c->local_window);
2455                 xfree(data);
2456                 return;
2457         }
2458         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2459         c->local_window -= data_len;
2460         buffer_append(&c->extended, data, data_len);
2461         xfree(data);
2462 }
2463
2464 /* ARGSUSED */
2465 void
2466 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2467 {
2468         int id;
2469         Channel *c;
2470
2471         id = packet_get_int();
2472         packet_check_eom();
2473         c = channel_lookup(id);
2474         if (c == NULL)
2475                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2476         chan_rcvd_ieof(c);
2477
2478         /* XXX force input close */
2479         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2480                 debug("channel %d: FORCE input drain", c->self);
2481                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2482                 if (buffer_len(&c->input) == 0)
2483                         chan_ibuf_empty(c);
2484         }
2485
2486 }
2487
2488 /* ARGSUSED */
2489 void
2490 channel_input_close(int type, u_int32_t seq, void *ctxt)
2491 {
2492         int id;
2493         Channel *c;
2494
2495         id = packet_get_int();
2496         packet_check_eom();
2497         c = channel_lookup(id);
2498         if (c == NULL)
2499                 packet_disconnect("Received close for nonexistent channel %d.", id);
2500
2501         /*
2502          * Send a confirmation that we have closed the channel and no more
2503          * data is coming for it.
2504          */
2505         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2506         packet_put_int(c->remote_id);
2507         packet_send();
2508
2509         /*
2510          * If the channel is in closed state, we have sent a close request,
2511          * and the other side will eventually respond with a confirmation.
2512          * Thus, we cannot free the channel here, because then there would be
2513          * no-one to receive the confirmation.  The channel gets freed when
2514          * the confirmation arrives.
2515          */
2516         if (c->type != SSH_CHANNEL_CLOSED) {
2517                 /*
2518                  * Not a closed channel - mark it as draining, which will
2519                  * cause it to be freed later.
2520                  */
2521                 buffer_clear(&c->input);
2522                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2523         }
2524 }
2525
2526 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2527 /* ARGSUSED */
2528 void
2529 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2530 {
2531         int id = packet_get_int();
2532         Channel *c = channel_lookup(id);
2533
2534         packet_check_eom();
2535         if (c == NULL)
2536                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2537         chan_rcvd_oclose(c);
2538 }
2539
2540 /* ARGSUSED */
2541 void
2542 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2543 {
2544         int id = packet_get_int();
2545         Channel *c = channel_lookup(id);
2546
2547         packet_check_eom();
2548         if (c == NULL)
2549                 packet_disconnect("Received close confirmation for "
2550                     "out-of-range channel %d.", id);
2551         if (c->type != SSH_CHANNEL_CLOSED)
2552                 packet_disconnect("Received close confirmation for "
2553                     "non-closed channel %d (type %d).", id, c->type);
2554         channel_free(c);
2555 }
2556
2557 /* ARGSUSED */
2558 void
2559 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2560 {
2561         int id, remote_id;
2562         Channel *c;
2563
2564         id = packet_get_int();
2565         c = channel_lookup(id);
2566
2567         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2568                 packet_disconnect("Received open confirmation for "
2569                     "non-opening channel %d.", id);
2570         remote_id = packet_get_int();
2571         /* Record the remote channel number and mark that the channel is now open. */
2572         c->remote_id = remote_id;
2573         c->type = SSH_CHANNEL_OPEN;
2574
2575         if (compat20) {
2576                 c->remote_window = packet_get_int();
2577                 c->remote_maxpacket = packet_get_int();
2578                 if (c->open_confirm) {
2579                         debug2("callback start");
2580                         c->open_confirm(c->self, 1, c->open_confirm_ctx);
2581                         debug2("callback done");
2582                 }
2583                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2584                     c->remote_window, c->remote_maxpacket);
2585         }
2586         packet_check_eom();
2587 }
2588
2589 static char *
2590 reason2txt(int reason)
2591 {
2592         switch (reason) {
2593         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2594                 return "administratively prohibited";
2595         case SSH2_OPEN_CONNECT_FAILED:
2596                 return "connect failed";
2597         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2598                 return "unknown channel type";
2599         case SSH2_OPEN_RESOURCE_SHORTAGE:
2600                 return "resource shortage";
2601         }
2602         return "unknown reason";
2603 }
2604
2605 /* ARGSUSED */
2606 void
2607 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2608 {
2609         int id, reason;
2610         char *msg = NULL, *lang = NULL;
2611         Channel *c;
2612
2613         id = packet_get_int();
2614         c = channel_lookup(id);
2615
2616         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2617                 packet_disconnect("Received open failure for "
2618                     "non-opening channel %d.", id);
2619         if (compat20) {
2620                 reason = packet_get_int();
2621                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2622                         msg  = packet_get_string(NULL);
2623                         lang = packet_get_string(NULL);
2624                 }
2625                 logit("channel %d: open failed: %s%s%s", id,
2626                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2627                 if (msg != NULL)
2628                         xfree(msg);
2629                 if (lang != NULL)
2630                         xfree(lang);
2631                 if (c->open_confirm) {
2632                         debug2("callback start");
2633                         c->open_confirm(c->self, 0, c->open_confirm_ctx);
2634                         debug2("callback done");
2635                 }
2636         }
2637         packet_check_eom();
2638         /* Schedule the channel for cleanup/deletion. */
2639         chan_mark_dead(c);
2640 }
2641
2642 /* ARGSUSED */
2643 void
2644 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2645 {
2646         Channel *c;
2647         int id;
2648         u_int adjust;
2649
2650         if (!compat20)
2651                 return;
2652
2653         /* Get the channel number and verify it. */
2654         id = packet_get_int();
2655         c = channel_lookup(id);
2656
2657         if (c == NULL) {
2658                 logit("Received window adjust for non-open channel %d.", id);
2659                 return;
2660         }
2661         adjust = packet_get_int();
2662         packet_check_eom();
2663         debug2("channel %d: rcvd adjust %u", id, adjust);
2664         c->remote_window += adjust;
2665 }
2666
2667 /* ARGSUSED */
2668 void
2669 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2670 {
2671         Channel *c = NULL;
2672         u_short host_port;
2673         char *host, *originator_string;
2674         int remote_id;
2675
2676         remote_id = packet_get_int();
2677         host = packet_get_string(NULL);
2678         host_port = packet_get_int();
2679
2680         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2681                 originator_string = packet_get_string(NULL);
2682         } else {
2683                 originator_string = xstrdup("unknown (remote did not supply name)");
2684         }
2685         packet_check_eom();
2686         c = channel_connect_to(host, host_port,
2687             "connected socket", originator_string);
2688         xfree(originator_string);
2689         xfree(host);
2690         if (c == NULL) {
2691                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2692                 packet_put_int(remote_id);
2693                 packet_send();
2694         } else
2695                 c->remote_id = remote_id;
2696 }
2697
2698 /* ARGSUSED */
2699 void
2700 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2701 {
2702         Channel *c;
2703         struct channel_confirm *cc;
2704         int id;
2705
2706         /* Reset keepalive timeout */
2707         packet_set_alive_timeouts(0);
2708
2709         id = packet_get_int();
2710         packet_check_eom();
2711
2712         debug2("channel_input_status_confirm: type %d id %d", type, id);
2713
2714         if ((c = channel_lookup(id)) == NULL) {
2715                 logit("channel_input_status_confirm: %d: unknown", id);
2716                 return;
2717         }
2718         ;
2719         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2720                 return;
2721         cc->cb(type, c, cc->ctx);
2722         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2723         bzero(cc, sizeof(*cc));
2724         xfree(cc);
2725 }
2726
2727 /* -- tcp forwarding */
2728
2729 void
2730 channel_set_af(int af)
2731 {
2732         IPv4or6 = af;
2733 }
2734
2735 void
2736 channel_set_hpn(int disabled, u_int buf_size)
2737 {
2738         hpn_disabled = disabled;
2739         buffer_size = buf_size;
2740         debug("HPN Disabled: %d, HPN Buffer Size: %d",
2741             hpn_disabled, buffer_size);
2742 }
2743
2744 /*
2745  * Determine whether or not a port forward listens to loopback, the
2746  * specified address or wildcard. On the client, a specified bind
2747  * address will always override gateway_ports. On the server, a
2748  * gateway_ports of 1 (``yes'') will override the client's specification
2749  * and force a wildcard bind, whereas a value of 2 (``clientspecified'')
2750  * will bind to whatever address the client asked for.
2751  *
2752  * Special-case listen_addrs are:
2753  *
2754  * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2755  * "" (empty string), "*"  -> wildcard v4/v6
2756  * "localhost"             -> loopback v4/v6
2757  */
2758 static const char *
2759 channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
2760     int is_client, int gateway_ports)
2761 {
2762         const char *addr = NULL;
2763         int wildcard = 0;
2764
2765         if (listen_addr == NULL) {
2766                 /* No address specified: default to gateway_ports setting */
2767                 if (gateway_ports)
2768                         wildcard = 1;
2769         } else if (gateway_ports || is_client) {
2770                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2771                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2772                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2773                     (!is_client && gateway_ports == 1))
2774                         wildcard = 1;
2775                 else if (strcmp(listen_addr, "localhost") != 0)
2776                         addr = listen_addr;
2777         }
2778         if (wildcardp != NULL)
2779                 *wildcardp = wildcard;
2780         return addr;
2781 }
2782
2783 static int
2784 channel_setup_fwd_listener(int type, const char *listen_addr,
2785     u_short listen_port, int *allocated_listen_port,
2786     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2787 {
2788         Channel *c;
2789         int sock, r, success = 0, wildcard = 0, is_client;
2790         struct addrinfo hints, *ai, *aitop;
2791         const char *host, *addr;
2792         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2793         in_port_t *lport_p;
2794
2795         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2796             listen_addr : host_to_connect;
2797         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2798
2799         if (host == NULL) {
2800                 error("No forward host name.");
2801                 return 0;
2802         }
2803         if (strlen(host) >= NI_MAXHOST) {
2804                 error("Forward host name too long.");
2805                 return 0;
2806         }
2807
2808         /* Determine the bind address, cf. channel_fwd_bind_addr() comment */
2809         addr = channel_fwd_bind_addr(listen_addr, &wildcard,
2810             is_client, gateway_ports);
2811         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2812             type, wildcard, (addr == NULL) ? "NULL" : addr);
2813
2814         /*
2815          * getaddrinfo returns a loopback address if the hostname is
2816          * set to NULL and hints.ai_flags is not AI_PASSIVE
2817          */
2818         memset(&hints, 0, sizeof(hints));
2819         hints.ai_family = IPv4or6;
2820         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2821         hints.ai_socktype = SOCK_STREAM;
2822         snprintf(strport, sizeof strport, "%d", listen_port);
2823         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2824                 if (addr == NULL) {
2825                         /* This really shouldn't happen */
2826                         packet_disconnect("getaddrinfo: fatal error: %s",
2827                             ssh_gai_strerror(r));
2828                 } else {
2829                         error("channel_setup_fwd_listener: "
2830                             "getaddrinfo(%.64s): %s", addr,
2831                             ssh_gai_strerror(r));
2832                 }
2833                 return 0;
2834         }
2835         if (allocated_listen_port != NULL)
2836                 *allocated_listen_port = 0;
2837         for (ai = aitop; ai; ai = ai->ai_next) {
2838                 switch (ai->ai_family) {
2839                 case AF_INET:
2840                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2841                             sin_port;
2842                         break;
2843                 case AF_INET6:
2844                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2845                             sin6_port;
2846                         break;
2847                 default:
2848                         continue;
2849                 }
2850                 /*
2851                  * If allocating a port for -R forwards, then use the
2852                  * same port for all address families.
2853                  */
2854                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2855                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2856                         *lport_p = htons(*allocated_listen_port);
2857
2858                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2859                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2860                         error("channel_setup_fwd_listener: getnameinfo failed");
2861                         continue;
2862                 }
2863                 /* Create a port to listen for the host. */
2864                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2865                 if (sock < 0) {
2866                         /* this is no error since kernel may not support ipv6 */
2867                         verbose("socket: %.100s", strerror(errno));
2868                         continue;
2869                 }
2870
2871                 channel_set_reuseaddr(sock);
2872                 if (ai->ai_family == AF_INET6)
2873                         sock_set_v6only(sock);
2874
2875                 debug("Local forwarding listening on %s port %s.",
2876                     ntop, strport);
2877
2878                 /* Bind the socket to the address. */
2879                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2880                         /* address can be in use ipv6 address is already bound */
2881                         if (!ai->ai_next)
2882                                 error("bind: %.100s", strerror(errno));
2883                         else
2884                                 verbose("bind: %.100s", strerror(errno));
2885
2886                         close(sock);
2887                         continue;
2888                 }
2889                 /* Start listening for connections on the socket. */
2890                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2891                         error("listen: %.100s", strerror(errno));
2892                         close(sock);
2893                         continue;
2894                 }
2895
2896                 /*
2897                  * listen_port == 0 requests a dynamically allocated port -
2898                  * record what we got.
2899                  */
2900                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2901                     allocated_listen_port != NULL &&
2902                     *allocated_listen_port == 0) {
2903                         *allocated_listen_port = get_sock_port(sock, 1);
2904                         debug("Allocated listen port %d",
2905                             *allocated_listen_port);
2906                 }
2907
2908                 /*
2909                  * Allocate a channel number for the socket.  Explicitly test
2910                  * for hpn disabled option.  If true use smaller window size.
2911                  */
2912                 if (hpn_disabled)
2913                         c = channel_new("port listener", type, sock, sock, -1,
2914                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2915                             0, "port listener", 1);
2916                 else
2917                         c = channel_new("port listener", type, sock, sock, -1,
2918                             buffer_size, CHAN_TCP_PACKET_DEFAULT,
2919                             0, "port listener", 1);
2920                 c->path = xstrdup(host);
2921                 c->host_port = port_to_connect;
2922                 c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
2923                 if (listen_port == 0 && allocated_listen_port != NULL &&
2924                     !(datafellows & SSH_BUG_DYNAMIC_RPORT))
2925                         c->listening_port = *allocated_listen_port;
2926                 else
2927                         c->listening_port = listen_port;
2928                 success = 1;
2929         }
2930         if (success == 0)
2931                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2932                     listen_port);
2933         freeaddrinfo(aitop);
2934         return success;
2935 }
2936
2937 int
2938 channel_cancel_rport_listener(const char *host, u_short port)
2939 {
2940         u_int i;
2941         int found = 0;
2942
2943         for (i = 0; i < channels_alloc; i++) {
2944                 Channel *c = channels[i];
2945                 if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
2946                         continue;
2947                 if (strcmp(c->path, host) == 0 && c->listening_port == port) {
2948                         debug2("%s: close channel %d", __func__, i);
2949                         channel_free(c);
2950                         found = 1;
2951                 }
2952         }
2953
2954         return (found);
2955 }
2956
2957 int
2958 channel_cancel_lport_listener(const char *lhost, u_short lport,
2959     int cport, int gateway_ports)
2960 {
2961         u_int i;
2962         int found = 0;
2963         const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, gateway_ports);
2964
2965         for (i = 0; i < channels_alloc; i++) {
2966                 Channel *c = channels[i];
2967                 if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
2968                         continue;
2969                 if (c->listening_port != lport)
2970                         continue;
2971                 if (cport == CHANNEL_CANCEL_PORT_STATIC) {
2972                         /* skip dynamic forwardings */
2973                         if (c->host_port == 0)
2974                                 continue;
2975                 } else {
2976                         if (c->host_port != cport)
2977                                 continue;
2978                 }
2979                 if ((c->listening_addr == NULL && addr != NULL) ||
2980                     (c->listening_addr != NULL && addr == NULL))
2981                         continue;
2982                 if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
2983                         debug2("%s: close channel %d", __func__, i);
2984                         channel_free(c);
2985                         found = 1;
2986                 }
2987         }
2988
2989         return (found);
2990 }
2991
2992 /* protocol local port fwd, used by ssh (and sshd in v1) */
2993 int
2994 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2995     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2996 {
2997         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2998             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2999             gateway_ports);
3000 }
3001
3002 /* protocol v2 remote port fwd, used by sshd */
3003 int
3004 channel_setup_remote_fwd_listener(const char *listen_address,
3005     u_short listen_port, int *allocated_listen_port, int gateway_ports)
3006 {
3007         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
3008             listen_address, listen_port, allocated_listen_port,
3009             NULL, 0, gateway_ports);
3010 }
3011
3012 /*
3013  * Translate the requested rfwd listen host to something usable for
3014  * this server.
3015  */
3016 static const char *
3017 channel_rfwd_bind_host(const char *listen_host)
3018 {
3019         if (listen_host == NULL) {
3020                 if (datafellows & SSH_BUG_RFWD_ADDR)
3021                         return "127.0.0.1";
3022                 else
3023                         return "localhost";
3024         } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
3025                 if (datafellows & SSH_BUG_RFWD_ADDR)
3026                         return "0.0.0.0";
3027                 else
3028                         return "";
3029         } else
3030                 return listen_host;
3031 }
3032
3033 /*
3034  * Initiate forwarding of connections to port "port" on remote host through
3035  * the secure channel to host:port from local side.
3036  * Returns handle (index) for updating the dynamic listen port with
3037  * channel_update_permitted_opens().
3038  */
3039 int
3040 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
3041     const char *host_to_connect, u_short port_to_connect)
3042 {
3043         int type, success = 0, idx = -1;
3044
3045         /* Send the forward request to the remote side. */
3046         if (compat20) {
3047                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
3048                 packet_put_cstring("tcpip-forward");
3049                 packet_put_char(1);             /* boolean: want reply */
3050                 packet_put_cstring(channel_rfwd_bind_host(listen_host));
3051                 packet_put_int(listen_port);
3052                 packet_send();
3053                 packet_write_wait();
3054                 /* Assume that server accepts the request */
3055                 success = 1;
3056         } else {
3057                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
3058                 packet_put_int(listen_port);
3059                 packet_put_cstring(host_to_connect);
3060                 packet_put_int(port_to_connect);
3061                 packet_send();
3062                 packet_write_wait();
3063
3064                 /* Wait for response from the remote side. */
3065                 type = packet_read();
3066                 switch (type) {
3067                 case SSH_SMSG_SUCCESS:
3068                         success = 1;
3069                         break;
3070                 case SSH_SMSG_FAILURE:
3071                         break;
3072                 default:
3073                         /* Unknown packet */
3074                         packet_disconnect("Protocol error for port forward request:"
3075                             "received packet type %d.", type);
3076                 }
3077         }
3078         if (success) {
3079                 /* Record that connection to this host/port is permitted. */
3080                 permitted_opens = xrealloc(permitted_opens,
3081                     num_permitted_opens + 1, sizeof(*permitted_opens));
3082                 idx = num_permitted_opens++;
3083                 permitted_opens[idx].host_to_connect = xstrdup(host_to_connect);
3084                 permitted_opens[idx].port_to_connect = port_to_connect;
3085                 permitted_opens[idx].listen_port = listen_port;
3086         }
3087         return (idx);
3088 }
3089
3090 /*
3091  * Request cancellation of remote forwarding of connection host:port from
3092  * local side.
3093  */
3094 int
3095 channel_request_rforward_cancel(const char *host, u_short port)
3096 {
3097         int i;
3098
3099         if (!compat20)
3100                 return -1;
3101
3102         for (i = 0; i < num_permitted_opens; i++) {
3103                 if (permitted_opens[i].host_to_connect != NULL &&
3104                     permitted_opens[i].listen_port == port)
3105                         break;
3106         }
3107         if (i >= num_permitted_opens) {
3108                 debug("%s: requested forward not found", __func__);
3109                 return -1;
3110         }
3111         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3112         packet_put_cstring("cancel-tcpip-forward");
3113         packet_put_char(0);
3114         packet_put_cstring(channel_rfwd_bind_host(host));
3115         packet_put_int(port);
3116         packet_send();
3117
3118         permitted_opens[i].listen_port = 0;
3119         permitted_opens[i].port_to_connect = 0;
3120         xfree(permitted_opens[i].host_to_connect);
3121         permitted_opens[i].host_to_connect = NULL;
3122
3123         return 0;
3124 }
3125
3126 /*
3127  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
3128  * listening for the port, and sends back a success reply (or disconnect
3129  * message if there was an error).
3130  */
3131 int
3132 channel_input_port_forward_request(int is_root, int gateway_ports)
3133 {
3134         u_short port, host_port;
3135         int success = 0;
3136         char *hostname;
3137
3138         /* Get arguments from the packet. */
3139         port = packet_get_int();
3140         hostname = packet_get_string(NULL);
3141         host_port = packet_get_int();
3142
3143 #ifndef HAVE_CYGWIN
3144         /*
3145          * Check that an unprivileged user is not trying to forward a
3146          * privileged port.
3147          */
3148         if (port < IPPORT_RESERVED && !is_root)
3149                 packet_disconnect(
3150                     "Requested forwarding of port %d but user is not root.",
3151                     port);
3152         if (host_port == 0)
3153                 packet_disconnect("Dynamic forwarding denied.");
3154 #endif
3155
3156         /* Initiate forwarding */
3157         success = channel_setup_local_fwd_listener(NULL, port, hostname,
3158             host_port, gateway_ports);
3159
3160         /* Free the argument string. */
3161         xfree(hostname);
3162
3163         return (success ? 0 : -1);
3164 }
3165
3166 /*
3167  * Permits opening to any host/port if permitted_opens[] is empty.  This is
3168  * usually called by the server, because the user could connect to any port
3169  * anyway, and the server has no way to know but to trust the client anyway.
3170  */
3171 void
3172 channel_permit_all_opens(void)
3173 {
3174         if (num_permitted_opens == 0)
3175                 all_opens_permitted = 1;
3176 }
3177
3178 void
3179 channel_add_permitted_opens(char *host, int port)
3180 {
3181         debug("allow port forwarding to host %s port %d", host, port);
3182
3183         permitted_opens = xrealloc(permitted_opens,
3184             num_permitted_opens + 1, sizeof(*permitted_opens));
3185         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
3186         permitted_opens[num_permitted_opens].port_to_connect = port;
3187         num_permitted_opens++;
3188
3189         all_opens_permitted = 0;
3190 }
3191
3192 /*
3193  * Update the listen port for a dynamic remote forward, after
3194  * the actual 'newport' has been allocated. If 'newport' < 0 is
3195  * passed then they entry will be invalidated.
3196  */
3197 void
3198 channel_update_permitted_opens(int idx, int newport)
3199 {
3200         if (idx < 0 || idx >= num_permitted_opens) {
3201                 debug("channel_update_permitted_opens: index out of range:"
3202                     " %d num_permitted_opens %d", idx, num_permitted_opens);
3203                 return;
3204         }
3205         debug("%s allowed port %d for forwarding to host %s port %d",
3206             newport > 0 ? "Updating" : "Removing",
3207             newport,
3208             permitted_opens[idx].host_to_connect,
3209             permitted_opens[idx].port_to_connect);
3210         if (newport >= 0)  {
3211                 permitted_opens[idx].listen_port =
3212                     (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
3213         } else {
3214                 permitted_opens[idx].listen_port = 0;
3215                 permitted_opens[idx].port_to_connect = 0;
3216                 xfree(permitted_opens[idx].host_to_connect);
3217                 permitted_opens[idx].host_to_connect = NULL;
3218         }
3219 }
3220
3221 int
3222 channel_add_adm_permitted_opens(char *host, int port)
3223 {
3224         debug("config allows port forwarding to host %s port %d", host, port);
3225
3226         permitted_adm_opens = xrealloc(permitted_adm_opens,
3227             num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
3228         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3229              = xstrdup(host);
3230         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3231         return ++num_adm_permitted_opens;
3232 }
3233
3234 void
3235 channel_disable_adm_local_opens(void)
3236 {
3237         channel_clear_adm_permitted_opens();
3238         permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
3239         permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
3240         num_adm_permitted_opens = 1;
3241 }
3242
3243 void
3244 channel_clear_permitted_opens(void)
3245 {
3246         int i;
3247
3248         for (i = 0; i < num_permitted_opens; i++)
3249                 if (permitted_opens[i].host_to_connect != NULL)
3250                         xfree(permitted_opens[i].host_to_connect);
3251         if (num_permitted_opens > 0) {
3252                 xfree(permitted_opens);
3253                 permitted_opens = NULL;
3254         }
3255         num_permitted_opens = 0;
3256 }
3257
3258 void
3259 channel_clear_adm_permitted_opens(void)
3260 {
3261         int i;
3262
3263         for (i = 0; i < num_adm_permitted_opens; i++)
3264                 if (permitted_adm_opens[i].host_to_connect != NULL)
3265                         xfree(permitted_adm_opens[i].host_to_connect);
3266         if (num_adm_permitted_opens > 0) {
3267                 xfree(permitted_adm_opens);
3268                 permitted_adm_opens = NULL;
3269         }
3270         num_adm_permitted_opens = 0;
3271 }
3272
3273 void
3274 channel_print_adm_permitted_opens(void)
3275 {
3276         int i;
3277
3278         printf("permitopen");
3279         if (num_adm_permitted_opens == 0) {
3280                 printf(" any\n");
3281                 return;
3282         }
3283         for (i = 0; i < num_adm_permitted_opens; i++)
3284                 if (permitted_adm_opens[i].host_to_connect == NULL)
3285                         printf(" none");
3286                 else
3287                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3288                             permitted_adm_opens[i].port_to_connect);
3289         printf("\n");
3290 }
3291
3292 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
3293 int
3294 permitopen_port(const char *p)
3295 {
3296         int port;
3297
3298         if (strcmp(p, "*") == 0)
3299                 return FWD_PERMIT_ANY_PORT;
3300         if ((port = a2port(p)) > 0)
3301                 return port;
3302         return -1;
3303 }
3304
3305 static int
3306 port_match(u_short allowedport, u_short requestedport)
3307 {
3308         if (allowedport == FWD_PERMIT_ANY_PORT ||
3309             allowedport == requestedport)
3310                 return 1;
3311         return 0;
3312 }
3313
3314 /* Try to start non-blocking connect to next host in cctx list */
3315 static int
3316 connect_next(struct channel_connect *cctx)
3317 {
3318         int sock, saved_errno;
3319         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
3320
3321         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3322                 if (cctx->ai->ai_family != AF_INET &&
3323                     cctx->ai->ai_family != AF_INET6)
3324                         continue;
3325                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3326                     ntop, sizeof(ntop), strport, sizeof(strport),
3327                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3328                         error("connect_next: getnameinfo failed");
3329                         continue;
3330                 }
3331                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3332                     cctx->ai->ai_protocol)) == -1) {
3333                         if (cctx->ai->ai_next == NULL)
3334                                 error("socket: %.100s", strerror(errno));
3335                         else
3336                                 verbose("socket: %.100s", strerror(errno));
3337                         continue;
3338                 }
3339                 if (set_nonblock(sock) == -1)
3340                         fatal("%s: set_nonblock(%d)", __func__, sock);
3341                 if (connect(sock, cctx->ai->ai_addr,
3342                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3343                         debug("connect_next: host %.100s ([%.100s]:%s): "
3344                             "%.100s", cctx->host, ntop, strport,
3345                             strerror(errno));
3346                         saved_errno = errno;
3347                         close(sock);
3348                         errno = saved_errno;
3349                         continue;       /* fail -- try next */
3350                 }
3351                 debug("connect_next: host %.100s ([%.100s]:%s) "
3352                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3353                 cctx->ai = cctx->ai->ai_next;
3354                 set_nodelay(sock);
3355                 return sock;
3356         }
3357         return -1;
3358 }
3359
3360 static void
3361 channel_connect_ctx_free(struct channel_connect *cctx)
3362 {
3363         xfree(cctx->host);
3364         if (cctx->aitop)
3365                 freeaddrinfo(cctx->aitop);
3366         bzero(cctx, sizeof(*cctx));
3367         cctx->host = NULL;
3368         cctx->ai = cctx->aitop = NULL;
3369 }
3370
3371 /* Return CONNECTING channel to remote host, port */
3372 static Channel *
3373 connect_to(const char *host, u_short port, char *ctype, char *rname)
3374 {
3375         struct addrinfo hints;
3376         int gaierr;
3377         int sock = -1;
3378         char strport[NI_MAXSERV];
3379         struct channel_connect cctx;
3380         Channel *c;
3381
3382         memset(&cctx, 0, sizeof(cctx));
3383         memset(&hints, 0, sizeof(hints));
3384         hints.ai_family = IPv4or6;
3385         hints.ai_socktype = SOCK_STREAM;
3386         snprintf(strport, sizeof strport, "%d", port);
3387         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
3388                 error("connect_to %.100s: unknown host (%s)", host,
3389                     ssh_gai_strerror(gaierr));
3390                 return NULL;
3391         }
3392
3393         cctx.host = xstrdup(host);
3394         cctx.port = port;
3395         cctx.ai = cctx.aitop;
3396
3397         if ((sock = connect_next(&cctx)) == -1) {
3398                 error("connect to %.100s port %d failed: %s",
3399                     host, port, strerror(errno));
3400                 channel_connect_ctx_free(&cctx);
3401                 return NULL;
3402         }
3403         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3404             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3405         c->connect_ctx = cctx;
3406         return c;
3407 }
3408
3409 Channel *
3410 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3411 {
3412         int i;
3413
3414         for (i = 0; i < num_permitted_opens; i++) {
3415                 if (permitted_opens[i].host_to_connect != NULL &&
3416                     port_match(permitted_opens[i].listen_port, listen_port)) {
3417                         return connect_to(
3418                             permitted_opens[i].host_to_connect,
3419                             permitted_opens[i].port_to_connect, ctype, rname);
3420                 }
3421         }
3422         error("WARNING: Server requests forwarding for unknown listen_port %d",
3423             listen_port);
3424         return NULL;
3425 }
3426
3427 /* Check if connecting to that port is permitted and connect. */
3428 Channel *
3429 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3430 {
3431         int i, permit, permit_adm = 1;
3432
3433         permit = all_opens_permitted;
3434         if (!permit) {
3435                 for (i = 0; i < num_permitted_opens; i++)
3436                         if (permitted_opens[i].host_to_connect != NULL &&
3437                             port_match(permitted_opens[i].port_to_connect, port) &&
3438                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3439                                 permit = 1;
3440         }
3441
3442         if (num_adm_permitted_opens > 0) {
3443                 permit_adm = 0;
3444                 for (i = 0; i < num_adm_permitted_opens; i++)
3445                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3446                             port_match(permitted_adm_opens[i].port_to_connect, port) &&
3447                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3448                             == 0)
3449                                 permit_adm = 1;
3450         }
3451
3452         if (!permit || !permit_adm) {
3453                 logit("Received request to connect to host %.100s port %d, "
3454                     "but the request was denied.", host, port);
3455                 return NULL;
3456         }
3457         return connect_to(host, port, ctype, rname);
3458 }
3459
3460 void
3461 channel_send_window_changes(void)
3462 {
3463         u_int i;
3464         struct winsize ws;
3465
3466         for (i = 0; i < channels_alloc; i++) {
3467                 if (channels[i] == NULL || !channels[i]->client_tty ||
3468                     channels[i]->type != SSH_CHANNEL_OPEN)
3469                         continue;
3470                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3471                         continue;
3472                 channel_request_start(i, "window-change", 0);
3473                 packet_put_int((u_int)ws.ws_col);
3474                 packet_put_int((u_int)ws.ws_row);
3475                 packet_put_int((u_int)ws.ws_xpixel);
3476                 packet_put_int((u_int)ws.ws_ypixel);
3477                 packet_send();
3478         }
3479 }
3480
3481 /* -- X11 forwarding */
3482
3483 /*
3484  * Creates an internet domain socket for listening for X11 connections.
3485  * Returns 0 and a suitable display number for the DISPLAY variable
3486  * stored in display_numberp , or -1 if an error occurs.
3487  */
3488 int
3489 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3490     int single_connection, u_int *display_numberp, int **chanids)
3491 {
3492         Channel *nc = NULL;
3493         int display_number, sock;
3494         u_short port;
3495         struct addrinfo hints, *ai, *aitop;
3496         char strport[NI_MAXSERV];
3497         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3498
3499         if (chanids == NULL)
3500                 return -1;
3501
3502         for (display_number = x11_display_offset;
3503             display_number < MAX_DISPLAYS;
3504             display_number++) {
3505                 port = 6000 + display_number;
3506                 memset(&hints, 0, sizeof(hints));
3507                 hints.ai_family = IPv4or6;
3508                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3509                 hints.ai_socktype = SOCK_STREAM;
3510                 snprintf(strport, sizeof strport, "%d", port);
3511                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3512                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3513                         return -1;
3514                 }
3515                 for (ai = aitop; ai; ai = ai->ai_next) {
3516                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3517                                 continue;
3518                         sock = socket(ai->ai_family, ai->ai_socktype,
3519                             ai->ai_protocol);
3520                         if (sock < 0) {
3521                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
3522 #ifdef EPFNOSUPPORT
3523                                     && (errno != EPFNOSUPPORT)
3524 #endif
3525                                     ) {
3526                                         error("socket: %.100s", strerror(errno));
3527                                         freeaddrinfo(aitop);
3528                                         return -1;
3529                                 } else {
3530                                         debug("x11_create_display_inet: Socket family %d not supported",
3531                                                  ai->ai_family);
3532                                         continue;
3533                                 }
3534                         }
3535                         if (ai->ai_family == AF_INET6)
3536                                 sock_set_v6only(sock);
3537                         if (x11_use_localhost)
3538                                 channel_set_reuseaddr(sock);
3539                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3540                                 debug2("bind port %d: %.100s", port, strerror(errno));
3541                                 close(sock);
3542
3543                                 for (n = 0; n < num_socks; n++) {
3544                                         close(socks[n]);
3545                                 }
3546                                 num_socks = 0;
3547                                 break;
3548                         }
3549                         socks[num_socks++] = sock;
3550                         if (num_socks == NUM_SOCKS)
3551                                 break;
3552                 }
3553                 freeaddrinfo(aitop);
3554                 if (num_socks > 0)
3555                         break;
3556         }
3557         if (display_number >= MAX_DISPLAYS) {
3558                 error("Failed to allocate internet-domain X11 display socket.");
3559                 return -1;
3560         }
3561         /* Start listening for connections on the socket. */
3562         for (n = 0; n < num_socks; n++) {
3563                 sock = socks[n];
3564                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3565                         error("listen: %.100s", strerror(errno));
3566                         close(sock);
3567                         return -1;
3568                 }
3569         }
3570
3571         /* Allocate a channel for each socket. */
3572         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3573         for (n = 0; n < num_socks; n++) {
3574                 sock = socks[n];
3575                 if (hpn_disabled)
3576                         nc = channel_new("x11 listener",
3577                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3578                             CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3579                             0, "X11 inet listener", 1);
3580                 else
3581                         nc = channel_new("x11 listener",
3582                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3583                             buffer_size, CHAN_X11_PACKET_DEFAULT,
3584                             0, "X11 inet listener", 1);
3585                 nc->single_connection = single_connection;
3586                 (*chanids)[n] = nc->self;
3587         }
3588         (*chanids)[n] = -1;
3589
3590         /* Return the display number for the DISPLAY environment variable. */
3591         *display_numberp = display_number;
3592         return (0);
3593 }
3594
3595 static int
3596 connect_local_xsocket_path(const char *pathname)
3597 {
3598         int sock;
3599         struct sockaddr_un addr;
3600
3601         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3602         if (sock < 0)
3603                 error("socket: %.100s", strerror(errno));
3604         memset(&addr, 0, sizeof(addr));
3605         addr.sun_family = AF_UNIX;
3606         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3607         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3608                 return sock;
3609         close(sock);
3610         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3611         return -1;
3612 }
3613
3614 static int
3615 connect_local_xsocket(u_int dnr)
3616 {
3617         char buf[1024];
3618         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3619         return connect_local_xsocket_path(buf);
3620 }
3621
3622 int
3623 x11_connect_display(void)
3624 {
3625         u_int display_number;
3626         const char *display;
3627         char buf[1024], *cp;
3628         struct addrinfo hints, *ai, *aitop;
3629         char strport[NI_MAXSERV];
3630         int gaierr, sock = 0;
3631
3632         /* Try to open a socket for the local X server. */
3633         display = getenv("DISPLAY");
3634         if (!display) {
3635                 error("DISPLAY not set.");
3636                 return -1;
3637         }
3638         /*
3639          * Now we decode the value of the DISPLAY variable and make a
3640          * connection to the real X server.
3641          */
3642
3643         /* Check if the display is from launchd. */
3644 #ifdef __APPLE__
3645         if (strncmp(display, "/tmp/launch", 11) == 0) {
3646                 sock = connect_local_xsocket_path(display);
3647                 if (sock < 0)
3648                         return -1;
3649
3650                 /* OK, we now have a connection to the display. */
3651                 return sock;
3652         }
3653 #endif
3654         /*
3655          * Check if it is a unix domain socket.  Unix domain displays are in
3656          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3657          */
3658         if (strncmp(display, "unix:", 5) == 0 ||
3659             display[0] == ':') {
3660                 /* Connect to the unix domain socket. */
3661                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3662                         error("Could not parse display number from DISPLAY: %.100s",
3663                             display);
3664                         return -1;
3665                 }
3666                 /* Create a socket. */
3667                 sock = connect_local_xsocket(display_number);
3668                 if (sock < 0)
3669                         return -1;
3670
3671                 /* OK, we now have a connection to the display. */
3672                 return sock;
3673         }
3674         /*
3675          * Connect to an inet socket.  The DISPLAY value is supposedly
3676          * hostname:d[.s], where hostname may also be numeric IP address.
3677          */
3678         strlcpy(buf, display, sizeof(buf));
3679         cp = strchr(buf, ':');
3680         if (!cp) {
3681                 error("Could not find ':' in DISPLAY: %.100s", display);
3682                 return -1;
3683         }
3684         *cp = 0;
3685         /* buf now contains the host name.  But first we parse the display number. */
3686         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3687                 error("Could not parse display number from DISPLAY: %.100s",
3688                     display);
3689                 return -1;
3690         }
3691
3692         /* Look up the host address */
3693         memset(&hints, 0, sizeof(hints));
3694         hints.ai_family = IPv4or6;
3695         hints.ai_socktype = SOCK_STREAM;
3696         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3697         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3698                 error("%.100s: unknown host. (%s)", buf,
3699                 ssh_gai_strerror(gaierr));
3700                 return -1;
3701         }
3702         for (ai = aitop; ai; ai = ai->ai_next) {
3703                 /* Create a socket. */
3704                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3705                 if (sock < 0) {
3706                         debug2("socket: %.100s", strerror(errno));
3707                         continue;
3708                 }
3709                 /* Connect it to the display. */
3710                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3711                         debug2("connect %.100s port %u: %.100s", buf,
3712                             6000 + display_number, strerror(errno));
3713                         close(sock);
3714                         continue;
3715                 }
3716                 /* Success */
3717                 break;
3718         }
3719         freeaddrinfo(aitop);
3720         if (!ai) {
3721                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3722                     strerror(errno));
3723                 return -1;
3724         }
3725         set_nodelay(sock);
3726         return sock;
3727 }
3728
3729 /*
3730  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3731  * the remote channel number.  We should do whatever we want, and respond
3732  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3733  */
3734
3735 /* ARGSUSED */
3736 void
3737 x11_input_open(int type, u_int32_t seq, void *ctxt)
3738 {
3739         Channel *c = NULL;
3740         int remote_id, sock = 0;
3741         char *remote_host;
3742
3743         debug("Received X11 open request.");
3744
3745         remote_id = packet_get_int();
3746
3747         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3748                 remote_host = packet_get_string(NULL);
3749         } else {
3750                 remote_host = xstrdup("unknown (remote did not supply name)");
3751         }
3752         packet_check_eom();
3753
3754         /* Obtain a connection to the real X display. */
3755         sock = x11_connect_display();
3756         if (sock != -1) {
3757                 /* Allocate a channel for this connection. */
3758                 c = channel_new("connected x11 socket",
3759                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3760                     remote_host, 1);
3761                 c->remote_id = remote_id;
3762                 c->force_drain = 1;
3763         }
3764         xfree(remote_host);
3765         if (c == NULL) {
3766                 /* Send refusal to the remote host. */
3767                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3768                 packet_put_int(remote_id);
3769         } else {
3770                 /* Send a confirmation to the remote host. */
3771                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3772                 packet_put_int(remote_id);
3773                 packet_put_int(c->self);
3774         }
3775         packet_send();
3776 }
3777
3778 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3779 /* ARGSUSED */
3780 void
3781 deny_input_open(int type, u_int32_t seq, void *ctxt)
3782 {
3783         int rchan = packet_get_int();
3784
3785         switch (type) {
3786         case SSH_SMSG_AGENT_OPEN:
3787                 error("Warning: ssh server tried agent forwarding.");
3788                 break;
3789         case SSH_SMSG_X11_OPEN:
3790                 error("Warning: ssh server tried X11 forwarding.");
3791                 break;
3792         default:
3793                 error("deny_input_open: type %d", type);
3794                 break;
3795         }
3796         error("Warning: this is probably a break-in attempt by a malicious server.");
3797         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3798         packet_put_int(rchan);
3799         packet_send();
3800 }
3801
3802 /*
3803  * Requests forwarding of X11 connections, generates fake authentication
3804  * data, and enables authentication spoofing.
3805  * This should be called in the client only.
3806  */
3807 void
3808 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3809     const char *proto, const char *data, int want_reply)
3810 {
3811         u_int data_len = (u_int) strlen(data) / 2;
3812         u_int i, value;
3813         char *new_data;
3814         int screen_number;
3815         const char *cp;
3816         u_int32_t rnd = 0;
3817
3818         if (x11_saved_display == NULL)
3819                 x11_saved_display = xstrdup(disp);
3820         else if (strcmp(disp, x11_saved_display) != 0) {
3821                 error("x11_request_forwarding_with_spoofing: different "
3822                     "$DISPLAY already forwarded");
3823                 return;
3824         }
3825
3826         cp = strchr(disp, ':');
3827         if (cp)
3828                 cp = strchr(cp, '.');
3829         if (cp)
3830                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3831         else
3832                 screen_number = 0;
3833
3834         if (x11_saved_proto == NULL) {
3835                 /* Save protocol name. */
3836                 x11_saved_proto = xstrdup(proto);
3837                 /*
3838                  * Extract real authentication data and generate fake data
3839                  * of the same length.
3840                  */
3841                 x11_saved_data = xmalloc(data_len);
3842                 x11_fake_data = xmalloc(data_len);
3843                 for (i = 0; i < data_len; i++) {
3844                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3845                                 fatal("x11_request_forwarding: bad "
3846                                     "authentication data: %.100s", data);
3847                         if (i % 4 == 0)
3848                                 rnd = arc4random();
3849                         x11_saved_data[i] = value;
3850                         x11_fake_data[i] = rnd & 0xff;
3851                         rnd >>= 8;
3852                 }
3853                 x11_saved_data_len = data_len;
3854                 x11_fake_data_len = data_len;
3855         }
3856
3857         /* Convert the fake data into hex. */
3858         new_data = tohex(x11_fake_data, data_len);
3859
3860         /* Send the request packet. */
3861         if (compat20) {
3862                 channel_request_start(client_session_id, "x11-req", want_reply);
3863                 packet_put_char(0);     /* XXX bool single connection */
3864         } else {
3865                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3866         }
3867         packet_put_cstring(proto);
3868         packet_put_cstring(new_data);
3869         packet_put_int(screen_number);
3870         packet_send();
3871         packet_write_wait();
3872         xfree(new_data);
3873 }
3874
3875
3876 /* -- agent forwarding */
3877
3878 /* Sends a message to the server to request authentication fd forwarding. */
3879
3880 void
3881 auth_request_forwarding(void)
3882 {
3883         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3884         packet_send();
3885         packet_write_wait();
3886 }