channels.c

   1 /* $OpenBSD: channels.c,v 1.301 2010/01/11 01:39:46 dtucker Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <netdb.h>
  58 #include <stdio.h>
  59 #include <stdlib.h>
  60 #include <string.h>
  61 #include <termios.h>
  62 #include <unistd.h>
  63 #include <stdarg.h>
  64
  65 #include "openbsd-compat/sys-queue.h"
  66 #include "xmalloc.h"
  67 #include "ssh.h"
  68 #include "ssh1.h"
  69 #include "ssh2.h"
  70 #include "packet.h"
  71 #include "log.h"
  72 #include "misc.h"
  73 #include "buffer.h"
  74 #include "channels.h"
  75 #include "compat.h"
  76 #include "canohost.h"
  77 #include "key.h"
  78 #include "authfd.h"
  79 #include "pathnames.h"
  80
  81 /* -- channel core */
  82
  83 /*
  84  * Pointer to an array containing all allocated channels.  The array is
  85  * dynamically extended as needed.
  86  */
  87 static Channel **channels = NULL;
  88
  89 /*
  90  * Size of the channel array.  All slots of the array must always be
  91  * initialized (at least the type field); unused slots set to NULL
  92  */
  93 static u_int channels_alloc = 0;
  94
  95 /*
  96  * Maximum file descriptor value used in any of the channels.  This is
  97  * updated in channel_new.
  98  */
  99 static int channel_max_fd = 0;
 100
 101
 102 /* -- tcp forwarding */
 103
 104 /*
 105  * Data structure for storing which hosts are permitted for forward requests.
 106  * The local sides of any remote forwards are stored in this array to prevent
 107  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 108  * network (which might be behind a firewall).
 109  */
 110 typedef struct {
 111         char *host_to_connect;          /* Connect to 'host'. */
 112         u_short port_to_connect;        /* Connect to 'port'. */
 113         u_short listen_port;            /* Remote side should listen port number. */
 114 } ForwardPermission;
 115
 116 /* List of all permitted host/port pairs to connect by the user. */
 117 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 118
 119 /* List of all permitted host/port pairs to connect by the admin. */
 120 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 121
 122 /* Number of permitted host/port pairs in the array permitted by the user. */
 123 static int num_permitted_opens = 0;
 124
 125 /* Number of permitted host/port pair in the array permitted by the admin. */
 126 static int num_adm_permitted_opens = 0;
 127
 128 /*
 129  * If this is true, all opens are permitted.  This is the case on the server
 130  * on which we have to trust the client anyway, and the user could do
 131  * anything after logging in anyway.
 132  */
 133 static int all_opens_permitted = 0;
 134
 135
 136 /* -- X11 forwarding */
 137
 138 /* Maximum number of fake X11 displays to try. */
 139 #define MAX_DISPLAYS  1000
 140
 141 /* Saved X11 local (client) display. */
 142 static char *x11_saved_display = NULL;
 143
 144 /* Saved X11 authentication protocol name. */
 145 static char *x11_saved_proto = NULL;
 146
 147 /* Saved X11 authentication data.  This is the real data. */
 148 static char *x11_saved_data = NULL;
 149 static u_int x11_saved_data_len = 0;
 150
 151 /*
 152  * Fake X11 authentication data.  This is what the server will be sending us;
 153  * we should replace any occurrences of this by the real data.
 154  */
 155 static u_char *x11_fake_data = NULL;
 156 static u_int x11_fake_data_len;
 157
 158
 159 /* -- agent forwarding */
 160
 161 #define NUM_SOCKS       10
 162
 163 /* AF_UNSPEC or AF_INET or AF_INET6 */
 164 static int IPv4or6 = AF_UNSPEC;
 165
 166 /* helper */
 167 static void port_open_helper(Channel *c, char *rtype);
 168
 169 /* non-blocking connect helpers */
 170 static int connect_next(struct channel_connect *);
 171 static void channel_connect_ctx_free(struct channel_connect *);
 172
 173 /* -- channel core */
 174
 175 Channel *
 176 channel_by_id(int id)
 177 {
 178         Channel *c;
 179
 180         if (id < 0 || (u_int)id >= channels_alloc) {
 181                 logit("channel_by_id: %d: bad id", id);
 182                 return NULL;
 183         }
 184         c = channels[id];
 185         if (c == NULL) {
 186                 logit("channel_by_id: %d: bad id: channel free", id);
 187                 return NULL;
 188         }
 189         return c;
 190 }
 191
 192 /*
 193  * Returns the channel if it is allowed to receive protocol messages.
 194  * Private channels, like listening sockets, may not receive messages.
 195  */
 196 Channel *
 197 channel_lookup(int id)
 198 {
 199         Channel *c;
 200
 201         if ((c = channel_by_id(id)) == NULL)
 202                 return (NULL);
 203
 204         switch (c->type) {
 205         case SSH_CHANNEL_X11_OPEN:
 206         case SSH_CHANNEL_LARVAL:
 207         case SSH_CHANNEL_CONNECTING:
 208         case SSH_CHANNEL_DYNAMIC:
 209         case SSH_CHANNEL_OPENING:
 210         case SSH_CHANNEL_OPEN:
 211         case SSH_CHANNEL_INPUT_DRAINING:
 212         case SSH_CHANNEL_OUTPUT_DRAINING:
 213                 return (c);
 214         }
 215         logit("Non-public channel %d, type %d.", id, c->type);
 216         return (NULL);
 217 }
 218
 219 /*
 220  * Register filedescriptors for a channel, used when allocating a channel or
 221  * when the channel consumer/producer is ready, e.g. shell exec'd
 222  */
 223 static void
 224 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 225     int extusage, int nonblock, int is_tty)
 226 {
 227         /* Update the maximum file descriptor value. */
 228         channel_max_fd = MAX(channel_max_fd, rfd);
 229         channel_max_fd = MAX(channel_max_fd, wfd);
 230         channel_max_fd = MAX(channel_max_fd, efd);
 231
 232         if (rfd != -1)
 233                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 234         if (wfd != -1 && wfd != rfd)
 235                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 236         if (efd != -1 && efd != rfd && efd != wfd)
 237                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 238
 239         c->rfd = rfd;
 240         c->wfd = wfd;
 241         c->sock = (rfd == wfd) ? rfd : -1;
 242         c->ctl_fd = -1; /* XXX: set elsewhere */
 243         c->efd = efd;
 244         c->extended_usage = extusage;
 245
 246         if ((c->isatty = is_tty) != 0)
 247                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 248         c->wfd_isatty = is_tty || isatty(c->wfd);
 249
 250         /* enable nonblocking mode */
 251         if (nonblock) {
 252                 if (rfd != -1)
 253                         set_nonblock(rfd);
 254                 if (wfd != -1)
 255                         set_nonblock(wfd);
 256                 if (efd != -1)
 257                         set_nonblock(efd);
 258         }
 259 }
 260
 261 /*
 262  * Allocate a new channel object and set its type and socket. This will cause
 263  * remote_name to be freed.
 264  */
 265 Channel *
 266 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 267     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 268 {
 269         int found;
 270         u_int i;
 271         Channel *c;
 272
 273         /* Do initial allocation if this is the first call. */
 274         if (channels_alloc == 0) {
 275                 channels_alloc = 10;
 276                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 277                 for (i = 0; i < channels_alloc; i++)
 278                         channels[i] = NULL;
 279         }
 280         /* Try to find a free slot where to put the new channel. */
 281         for (found = -1, i = 0; i < channels_alloc; i++)
 282                 if (channels[i] == NULL) {
 283                         /* Found a free slot. */
 284                         found = (int)i;
 285                         break;
 286                 }
 287         if (found < 0) {
 288                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 289                 found = channels_alloc;
 290                 if (channels_alloc > 10000)
 291                         fatal("channel_new: internal error: channels_alloc %d "
 292                             "too big.", channels_alloc);
 293                 channels = xrealloc(channels, channels_alloc + 10,
 294                     sizeof(Channel *));
 295                 channels_alloc += 10;
 296                 debug2("channel: expanding %d", channels_alloc);
 297                 for (i = found; i < channels_alloc; i++)
 298                         channels[i] = NULL;
 299         }
 300         /* Initialize and return new channel. */
 301         c = channels[found] = xcalloc(1, sizeof(Channel));
 302         buffer_init(&c->input);
 303         buffer_init(&c->output);
 304         buffer_init(&c->extended);
 305         c->path = NULL;
 306         c->ostate = CHAN_OUTPUT_OPEN;
 307         c->istate = CHAN_INPUT_OPEN;
 308         c->flags = 0;
 309         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 310         c->self = found;
 311         c->type = type;
 312         c->ctype = ctype;
 313         c->local_window = window;
 314         c->local_window_max = window;
 315         c->local_consumed = 0;
 316         c->local_maxpacket = maxpack;
 317         c->remote_id = -1;
 318         c->remote_name = xstrdup(remote_name);
 319         c->remote_window = 0;
 320         c->remote_maxpacket = 0;
 321         c->force_drain = 0;
 322         c->single_connection = 0;
 323         c->detach_user = NULL;
 324         c->detach_close = 0;
 325         c->open_confirm = NULL;
 326         c->open_confirm_ctx = NULL;
 327         c->input_filter = NULL;
 328         c->output_filter = NULL;
 329         c->filter_ctx = NULL;
 330         c->filter_cleanup = NULL;
 331         c->delayed = 1;         /* prevent call to channel_post handler */
 332         TAILQ_INIT(&c->status_confirms);
 333         debug("channel %d: new [%s]", found, remote_name);
 334         return c;
 335 }
 336
 337 static int
 338 channel_find_maxfd(void)
 339 {
 340         u_int i;
 341         int max = 0;
 342         Channel *c;
 343
 344         for (i = 0; i < channels_alloc; i++) {
 345                 c = channels[i];
 346                 if (c != NULL) {
 347                         max = MAX(max, c->rfd);
 348                         max = MAX(max, c->wfd);
 349                         max = MAX(max, c->efd);
 350                 }
 351         }
 352         return max;
 353 }
 354
 355 int
 356 channel_close_fd(int *fdp)
 357 {
 358         int ret = 0, fd = *fdp;
 359
 360         if (fd != -1) {
 361                 ret = close(fd);
 362                 *fdp = -1;
 363                 if (fd == channel_max_fd)
 364                         channel_max_fd = channel_find_maxfd();
 365         }
 366         return ret;
 367 }
 368
 369 /* Close all channel fd/socket. */
 370 static void
 371 channel_close_fds(Channel *c)
 372 {
 373         debug3("channel %d: close_fds r %d w %d e %d c %d",
 374             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 375
 376         channel_close_fd(&c->sock);
 377         channel_close_fd(&c->ctl_fd);
 378         channel_close_fd(&c->rfd);
 379         channel_close_fd(&c->wfd);
 380         channel_close_fd(&c->efd);
 381 }
 382
 383 /* Free the channel and close its fd/socket. */
 384 void
 385 channel_free(Channel *c)
 386 {
 387         char *s;
 388         u_int i, n;
 389         struct channel_confirm *cc;
 390
 391         for (n = 0, i = 0; i < channels_alloc; i++)
 392                 if (channels[i])
 393                         n++;
 394         debug("channel %d: free: %s, nchannels %u", c->self,
 395             c->remote_name ? c->remote_name : "???", n);
 396
 397         s = channel_open_message();
 398         debug3("channel %d: status: %s", c->self, s);
 399         xfree(s);
 400
 401         if (c->sock != -1)
 402                 shutdown(c->sock, SHUT_RDWR);
 403         if (c->ctl_fd != -1)
 404                 shutdown(c->ctl_fd, SHUT_RDWR);
 405         channel_close_fds(c);
 406         buffer_free(&c->input);
 407         buffer_free(&c->output);
 408         buffer_free(&c->extended);
 409         if (c->remote_name) {
 410                 xfree(c->remote_name);
 411                 c->remote_name = NULL;
 412         }
 413         if (c->path) {
 414                 xfree(c->path);
 415                 c->path = NULL;
 416         }
 417         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 418                 if (cc->abandon_cb != NULL)
 419                         cc->abandon_cb(c, cc->ctx);
 420                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 421                 bzero(cc, sizeof(*cc));
 422                 xfree(cc);
 423         }
 424         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 425                 c->filter_cleanup(c->self, c->filter_ctx);
 426         channels[c->self] = NULL;
 427         xfree(c);
 428 }
 429
 430 void
 431 channel_free_all(void)
 432 {
 433         u_int i;
 434
 435         for (i = 0; i < channels_alloc; i++)
 436                 if (channels[i] != NULL)
 437                         channel_free(channels[i]);
 438 }
 439
 440 /*
 441  * Closes the sockets/fds of all channels.  This is used to close extra file
 442  * descriptors after a fork.
 443  */
 444 void
 445 channel_close_all(void)
 446 {
 447         u_int i;
 448
 449         for (i = 0; i < channels_alloc; i++)
 450                 if (channels[i] != NULL)
 451                         channel_close_fds(channels[i]);
 452 }
 453
 454 /*
 455  * Stop listening to channels.
 456  */
 457 void
 458 channel_stop_listening(void)
 459 {
 460         u_int i;
 461         Channel *c;
 462
 463         for (i = 0; i < channels_alloc; i++) {
 464                 c = channels[i];
 465                 if (c != NULL) {
 466                         switch (c->type) {
 467                         case SSH_CHANNEL_AUTH_SOCKET:
 468                         case SSH_CHANNEL_PORT_LISTENER:
 469                         case SSH_CHANNEL_RPORT_LISTENER:
 470                         case SSH_CHANNEL_X11_LISTENER:
 471                                 channel_close_fd(&c->sock);
 472                                 channel_free(c);
 473                                 break;
 474                         }
 475                 }
 476         }
 477 }
 478
 479 /*
 480  * Returns true if no channel has too much buffered data, and false if one or
 481  * more channel is overfull.
 482  */
 483 int
 484 channel_not_very_much_buffered_data(void)
 485 {
 486         u_int i;
 487         Channel *c;
 488
 489         for (i = 0; i < channels_alloc; i++) {
 490                 c = channels[i];
 491                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 492 #if 0
 493                         if (!compat20 &&
 494                             buffer_len(&c->input) > packet_get_maxsize()) {
 495                                 debug2("channel %d: big input buffer %d",
 496                                     c->self, buffer_len(&c->input));
 497                                 return 0;
 498                         }
 499 #endif
 500                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 501                                 debug2("channel %d: big output buffer %u > %u",
 502                                     c->self, buffer_len(&c->output),
 503                                     packet_get_maxsize());
 504                                 return 0;
 505                         }
 506                 }
 507         }
 508         return 1;
 509 }
 510
 511 /* Returns true if any channel is still open. */
 512 int
 513 channel_still_open(void)
 514 {
 515         u_int i;
 516         Channel *c;
 517
 518         for (i = 0; i < channels_alloc; i++) {
 519                 c = channels[i];
 520                 if (c == NULL)
 521                         continue;
 522                 switch (c->type) {
 523                 case SSH_CHANNEL_X11_LISTENER:
 524                 case SSH_CHANNEL_PORT_LISTENER:
 525                 case SSH_CHANNEL_RPORT_LISTENER:
 526                 case SSH_CHANNEL_CLOSED:
 527                 case SSH_CHANNEL_AUTH_SOCKET:
 528                 case SSH_CHANNEL_DYNAMIC:
 529                 case SSH_CHANNEL_CONNECTING:
 530                 case SSH_CHANNEL_ZOMBIE:
 531                         continue;
 532                 case SSH_CHANNEL_LARVAL:
 533                         if (!compat20)
 534                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 535                         continue;
 536                 case SSH_CHANNEL_OPENING:
 537                 case SSH_CHANNEL_OPEN:
 538                 case SSH_CHANNEL_X11_OPEN:
 539                         return 1;
 540                 case SSH_CHANNEL_INPUT_DRAINING:
 541                 case SSH_CHANNEL_OUTPUT_DRAINING:
 542                         if (!compat13)
 543                                 fatal("cannot happen: OUT_DRAIN");
 544                         return 1;
 545                 default:
 546                         fatal("channel_still_open: bad channel type %d", c->type);
 547                         /* NOTREACHED */
 548                 }
 549         }
 550         return 0;
 551 }
 552
 553 /* Returns the id of an open channel suitable for keepaliving */
 554 int
 555 channel_find_open(void)
 556 {
 557         u_int i;
 558         Channel *c;
 559
 560         for (i = 0; i < channels_alloc; i++) {
 561                 c = channels[i];
 562                 if (c == NULL || c->remote_id < 0)
 563                         continue;
 564                 switch (c->type) {
 565                 case SSH_CHANNEL_CLOSED:
 566                 case SSH_CHANNEL_DYNAMIC:
 567                 case SSH_CHANNEL_X11_LISTENER:
 568                 case SSH_CHANNEL_PORT_LISTENER:
 569                 case SSH_CHANNEL_RPORT_LISTENER:
 570                 case SSH_CHANNEL_OPENING:
 571                 case SSH_CHANNEL_CONNECTING:
 572                 case SSH_CHANNEL_ZOMBIE:
 573                         continue;
 574                 case SSH_CHANNEL_LARVAL:
 575                 case SSH_CHANNEL_AUTH_SOCKET:
 576                 case SSH_CHANNEL_OPEN:
 577                 case SSH_CHANNEL_X11_OPEN:
 578                         return i;
 579                 case SSH_CHANNEL_INPUT_DRAINING:
 580                 case SSH_CHANNEL_OUTPUT_DRAINING:
 581                         if (!compat13)
 582                                 fatal("cannot happen: OUT_DRAIN");
 583                         return i;
 584                 default:
 585                         fatal("channel_find_open: bad channel type %d", c->type);
 586                         /* NOTREACHED */
 587                 }
 588         }
 589         return -1;
 590 }
 591
 592
 593 /*
 594  * Returns a message describing the currently open forwarded connections,
 595  * suitable for sending to the client.  The message contains crlf pairs for
 596  * newlines.
 597  */
 598 char *
 599 channel_open_message(void)
 600 {
 601         Buffer buffer;
 602         Channel *c;
 603         char buf[1024], *cp;
 604         u_int i;
 605
 606         buffer_init(&buffer);
 607         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 608         buffer_append(&buffer, buf, strlen(buf));
 609         for (i = 0; i < channels_alloc; i++) {
 610                 c = channels[i];
 611                 if (c == NULL)
 612                         continue;
 613                 switch (c->type) {
 614                 case SSH_CHANNEL_X11_LISTENER:
 615                 case SSH_CHANNEL_PORT_LISTENER:
 616                 case SSH_CHANNEL_RPORT_LISTENER:
 617                 case SSH_CHANNEL_CLOSED:
 618                 case SSH_CHANNEL_AUTH_SOCKET:
 619                 case SSH_CHANNEL_ZOMBIE:
 620                         continue;
 621                 case SSH_CHANNEL_LARVAL:
 622                 case SSH_CHANNEL_OPENING:
 623                 case SSH_CHANNEL_CONNECTING:
 624                 case SSH_CHANNEL_DYNAMIC:
 625                 case SSH_CHANNEL_OPEN:
 626                 case SSH_CHANNEL_X11_OPEN:
 627                 case SSH_CHANNEL_INPUT_DRAINING:
 628                 case SSH_CHANNEL_OUTPUT_DRAINING:
 629                         snprintf(buf, sizeof buf,
 630                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 631                             c->self, c->remote_name,
 632                             c->type, c->remote_id,
 633                             c->istate, buffer_len(&c->input),
 634                             c->ostate, buffer_len(&c->output),
 635                             c->rfd, c->wfd, c->ctl_fd);
 636                         buffer_append(&buffer, buf, strlen(buf));
 637                         continue;
 638                 default:
 639                         fatal("channel_open_message: bad channel type %d", c->type);
 640                         /* NOTREACHED */
 641                 }
 642         }
 643         buffer_append(&buffer, "\0", 1);
 644         cp = xstrdup(buffer_ptr(&buffer));
 645         buffer_free(&buffer);
 646         return cp;
 647 }
 648
 649 void
 650 channel_send_open(int id)
 651 {
 652         Channel *c = channel_lookup(id);
 653
 654         if (c == NULL) {
 655                 logit("channel_send_open: %d: bad id", id);
 656                 return;
 657         }
 658         debug2("channel %d: send open", id);
 659         packet_start(SSH2_MSG_CHANNEL_OPEN);
 660         packet_put_cstring(c->ctype);
 661         packet_put_int(c->self);
 662         packet_put_int(c->local_window);
 663         packet_put_int(c->local_maxpacket);
 664         packet_send();
 665 }
 666
 667 void
 668 channel_request_start(int id, char *service, int wantconfirm)
 669 {
 670         Channel *c = channel_lookup(id);
 671
 672         if (c == NULL) {
 673                 logit("channel_request_start: %d: unknown channel id", id);
 674                 return;
 675         }
 676         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 677         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 678         packet_put_int(c->remote_id);
 679         packet_put_cstring(service);
 680         packet_put_char(wantconfirm);
 681 }
 682
 683 void
 684 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 685     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 686 {
 687         struct channel_confirm *cc;
 688         Channel *c;
 689
 690         if ((c = channel_lookup(id)) == NULL)
 691                 fatal("channel_register_expect: %d: bad id", id);
 692
 693         cc = xmalloc(sizeof(*cc));
 694         cc->cb = cb;
 695         cc->abandon_cb = abandon_cb;
 696         cc->ctx = ctx;
 697         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 698 }
 699
 700 void
 701 channel_register_open_confirm(int id, channel_callback_fn *fn, void *ctx)
 702 {
 703         Channel *c = channel_lookup(id);
 704
 705         if (c == NULL) {
 706                 logit("channel_register_open_confirm: %d: bad id", id);
 707                 return;
 708         }
 709         c->open_confirm = fn;
 710         c->open_confirm_ctx = ctx;
 711 }
 712
 713 void
 714 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 715 {
 716         Channel *c = channel_by_id(id);
 717
 718         if (c == NULL) {
 719                 logit("channel_register_cleanup: %d: bad id", id);
 720                 return;
 721         }
 722         c->detach_user = fn;
 723         c->detach_close = do_close;
 724 }
 725
 726 void
 727 channel_cancel_cleanup(int id)
 728 {
 729         Channel *c = channel_by_id(id);
 730
 731         if (c == NULL) {
 732                 logit("channel_cancel_cleanup: %d: bad id", id);
 733                 return;
 734         }
 735         c->detach_user = NULL;
 736         c->detach_close = 0;
 737 }
 738
 739 void
 740 channel_register_filter(int id, channel_infilter_fn *ifn,
 741     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 742 {
 743         Channel *c = channel_lookup(id);
 744
 745         if (c == NULL) {
 746                 logit("channel_register_filter: %d: bad id", id);
 747                 return;
 748         }
 749         c->input_filter = ifn;
 750         c->output_filter = ofn;
 751         c->filter_ctx = ctx;
 752         c->filter_cleanup = cfn;
 753 }
 754
 755 void
 756 channel_set_fds(int id, int rfd, int wfd, int efd,
 757     int extusage, int nonblock, int is_tty, u_int window_max)
 758 {
 759         Channel *c = channel_lookup(id);
 760
 761         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 762                 fatal("channel_activate for non-larval channel %d.", id);
 763         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 764         c->type = SSH_CHANNEL_OPEN;
 765         c->local_window = c->local_window_max = window_max;
 766         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 767         packet_put_int(c->remote_id);
 768         packet_put_int(c->local_window);
 769         packet_send();
 770 }
 771
 772 /*
 773  * 'channel_pre*' are called just before select() to add any bits relevant to
 774  * channels in the select bitmasks.
 775  */
 776 /*
 777  * 'channel_post*': perform any appropriate operations for channels which
 778  * have events pending.
 779  */
 780 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 781 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 782 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 783
 784 /* ARGSUSED */
 785 static void
 786 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 787 {
 788         FD_SET(c->sock, readset);
 789 }
 790
 791 /* ARGSUSED */
 792 static void
 793 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 794 {
 795         debug3("channel %d: waiting for connection", c->self);
 796         FD_SET(c->sock, writeset);
 797 }
 798
 799 static void
 800 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 801 {
 802         if (buffer_len(&c->input) < packet_get_maxsize())
 803                 FD_SET(c->sock, readset);
 804         if (buffer_len(&c->output) > 0)
 805                 FD_SET(c->sock, writeset);
 806 }
 807
 808 static void
 809 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 810 {
 811         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 812
 813         if (c->istate == CHAN_INPUT_OPEN &&
 814             limit > 0 &&
 815             buffer_len(&c->input) < limit &&
 816             buffer_check_alloc(&c->input, CHAN_RBUF))
 817                 FD_SET(c->rfd, readset);
 818         if (c->ostate == CHAN_OUTPUT_OPEN ||
 819             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 820                 if (buffer_len(&c->output) > 0) {
 821                         FD_SET(c->wfd, writeset);
 822                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 823                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 824                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 825                                     c->self, c->efd, buffer_len(&c->extended));
 826                         else
 827                                 chan_obuf_empty(c);
 828                 }
 829         }
 830         /** XXX check close conditions, too */
 831         if (compat20 && c->efd != -1 &&
 832             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 833                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 834                     buffer_len(&c->extended) > 0)
 835                         FD_SET(c->efd, writeset);
 836                 else if (!(c->flags & CHAN_EOF_SENT) &&
 837                     c->extended_usage == CHAN_EXTENDED_READ &&
 838                     buffer_len(&c->extended) < c->remote_window)
 839                         FD_SET(c->efd, readset);
 840         }
 841         /* XXX: What about efd? races? */
 842         if (compat20 && c->ctl_fd != -1 &&
 843             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 844                 FD_SET(c->ctl_fd, readset);
 845 }
 846
 847 /* ARGSUSED */
 848 static void
 849 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 850 {
 851         if (buffer_len(&c->input) == 0) {
 852                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 853                 packet_put_int(c->remote_id);
 854                 packet_send();
 855                 c->type = SSH_CHANNEL_CLOSED;
 856                 debug2("channel %d: closing after input drain.", c->self);
 857         }
 858 }
 859
 860 /* ARGSUSED */
 861 static void
 862 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 863 {
 864         if (buffer_len(&c->output) == 0)
 865                 chan_mark_dead(c);
 866         else
 867                 FD_SET(c->sock, writeset);
 868 }
 869
 870 /*
 871  * This is a special state for X11 authentication spoofing.  An opened X11
 872  * connection (when authentication spoofing is being done) remains in this
 873  * state until the first packet has been completely read.  The authentication
 874  * data in that packet is then substituted by the real data if it matches the
 875  * fake data, and the channel is put into normal mode.
 876  * XXX All this happens at the client side.
 877  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 878  */
 879 static int
 880 x11_open_helper(Buffer *b)
 881 {
 882         u_char *ucp;
 883         u_int proto_len, data_len;
 884
 885         /* Check if the fixed size part of the packet is in buffer. */
 886         if (buffer_len(b) < 12)
 887                 return 0;
 888
 889         /* Parse the lengths of variable-length fields. */
 890         ucp = buffer_ptr(b);
 891         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 892                 proto_len = 256 * ucp[6] + ucp[7];
 893                 data_len = 256 * ucp[8] + ucp[9];
 894         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 895                 proto_len = ucp[6] + 256 * ucp[7];
 896                 data_len = ucp[8] + 256 * ucp[9];
 897         } else {
 898                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 899                     ucp[0]);
 900                 return -1;
 901         }
 902
 903         /* Check if the whole packet is in buffer. */
 904         if (buffer_len(b) <
 905             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 906                 return 0;
 907
 908         /* Check if authentication protocol matches. */
 909         if (proto_len != strlen(x11_saved_proto) ||
 910             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 911                 debug2("X11 connection uses different authentication protocol.");
 912                 return -1;
 913         }
 914         /* Check if authentication data matches our fake data. */
 915         if (data_len != x11_fake_data_len ||
 916             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 917                 x11_fake_data, x11_fake_data_len) != 0) {
 918                 debug2("X11 auth data does not match fake data.");
 919                 return -1;
 920         }
 921         /* Check fake data length */
 922         if (x11_fake_data_len != x11_saved_data_len) {
 923                 error("X11 fake_data_len %d != saved_data_len %d",
 924                     x11_fake_data_len, x11_saved_data_len);
 925                 return -1;
 926         }
 927         /*
 928          * Received authentication protocol and data match
 929          * our fake data. Substitute the fake data with real
 930          * data.
 931          */
 932         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 933             x11_saved_data, x11_saved_data_len);
 934         return 1;
 935 }
 936
 937 static void
 938 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 939 {
 940         int ret = x11_open_helper(&c->output);
 941
 942         if (ret == 1) {
 943                 /* Start normal processing for the channel. */
 944                 c->type = SSH_CHANNEL_OPEN;
 945                 channel_pre_open_13(c, readset, writeset);
 946         } else if (ret == -1) {
 947                 /*
 948                  * We have received an X11 connection that has bad
 949                  * authentication information.
 950                  */
 951                 logit("X11 connection rejected because of wrong authentication.");
 952                 buffer_clear(&c->input);
 953                 buffer_clear(&c->output);
 954                 channel_close_fd(&c->sock);
 955                 c->sock = -1;
 956                 c->type = SSH_CHANNEL_CLOSED;
 957                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 958                 packet_put_int(c->remote_id);
 959                 packet_send();
 960         }
 961 }
 962
 963 static void
 964 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 965 {
 966         int ret = x11_open_helper(&c->output);
 967
 968         /* c->force_drain = 1; */
 969
 970         if (ret == 1) {
 971                 c->type = SSH_CHANNEL_OPEN;
 972                 channel_pre_open(c, readset, writeset);
 973         } else if (ret == -1) {
 974                 logit("X11 connection rejected because of wrong authentication.");
 975                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 976                 chan_read_failed(c);
 977                 buffer_clear(&c->input);
 978                 chan_ibuf_empty(c);
 979                 buffer_clear(&c->output);
 980                 /* for proto v1, the peer will send an IEOF */
 981                 if (compat20)
 982                         chan_write_failed(c);
 983                 else
 984                         c->type = SSH_CHANNEL_OPEN;
 985                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 986         }
 987 }
 988
 989 /* try to decode a socks4 header */
 990 /* ARGSUSED */
 991 static int
 992 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 993 {
 994         char *p, *host;
 995         u_int len, have, i, found, need;
 996         char username[256];
 997         struct {
 998                 u_int8_t version;
 999                 u_int8_t command;
1000                 u_int16_t dest_port;
1001                 struct in_addr dest_addr;
1002         } s4_req, s4_rsp;
1003
1004         debug2("channel %d: decode socks4", c->self);
1005
1006         have = buffer_len(&c->input);
1007         len = sizeof(s4_req);
1008         if (have < len)
1009                 return 0;
1010         p = buffer_ptr(&c->input);
1011
1012         need = 1;
1013         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1014         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1015                 debug2("channel %d: socks4a request", c->self);
1016                 /* ... and needs an extra string (the hostname) */
1017                 need = 2;
1018         }
1019         /* Check for terminating NUL on the string(s) */
1020         for (found = 0, i = len; i < have; i++) {
1021                 if (p[i] == '\0') {
1022                         found++;
1023                         if (found == need)
1024                                 break;
1025                 }
1026                 if (i > 1024) {
1027                         /* the peer is probably sending garbage */
1028                         debug("channel %d: decode socks4: too long",
1029                             c->self);
1030                         return -1;
1031                 }
1032         }
1033         if (found < need)
1034                 return 0;
1035         buffer_get(&c->input, (char *)&s4_req.version, 1);
1036         buffer_get(&c->input, (char *)&s4_req.command, 1);
1037         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1038         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1039         have = buffer_len(&c->input);
1040         p = buffer_ptr(&c->input);
1041         len = strlen(p);
1042         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1043         len++;                                  /* trailing '\0' */
1044         if (len > have)
1045                 fatal("channel %d: decode socks4: len %d > have %d",
1046                     c->self, len, have);
1047         strlcpy(username, p, sizeof(username));
1048         buffer_consume(&c->input, len);
1049
1050         if (c->path != NULL) {
1051                 xfree(c->path);
1052                 c->path = NULL;
1053         }
1054         if (need == 1) {                        /* SOCKS4: one string */
1055                 host = inet_ntoa(s4_req.dest_addr);
1056                 c->path = xstrdup(host);
1057         } else {                                /* SOCKS4A: two strings */
1058                 have = buffer_len(&c->input);
1059                 p = buffer_ptr(&c->input);
1060                 len = strlen(p);
1061                 debug2("channel %d: decode socks4a: host %s/%d",
1062                     c->self, p, len);
1063                 len++;                          /* trailing '\0' */
1064                 if (len > have)
1065                         fatal("channel %d: decode socks4a: len %d > have %d",
1066                             c->self, len, have);
1067                 if (len > NI_MAXHOST) {
1068                         error("channel %d: hostname \"%.100s\" too long",
1069                             c->self, p);
1070                         return -1;
1071                 }
1072                 c->path = xstrdup(p);
1073                 buffer_consume(&c->input, len);
1074         }
1075         c->host_port = ntohs(s4_req.dest_port);
1076
1077         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1078             c->self, c->path, c->host_port, s4_req.command);
1079
1080         if (s4_req.command != 1) {
1081                 debug("channel %d: cannot handle: %s cn %d",
1082                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1083                 return -1;
1084         }
1085         s4_rsp.version = 0;                     /* vn: 0 for reply */
1086         s4_rsp.command = 90;                    /* cd: req granted */
1087         s4_rsp.dest_port = 0;                   /* ignored */
1088         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1089         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1090         return 1;
1091 }
1092
1093 /* try to decode a socks5 header */
1094 #define SSH_SOCKS5_AUTHDONE     0x1000
1095 #define SSH_SOCKS5_NOAUTH       0x00
1096 #define SSH_SOCKS5_IPV4         0x01
1097 #define SSH_SOCKS5_DOMAIN       0x03
1098 #define SSH_SOCKS5_IPV6         0x04
1099 #define SSH_SOCKS5_CONNECT      0x01
1100 #define SSH_SOCKS5_SUCCESS      0x00
1101
1102 /* ARGSUSED */
1103 static int
1104 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1105 {
1106         struct {
1107                 u_int8_t version;
1108                 u_int8_t command;
1109                 u_int8_t reserved;
1110                 u_int8_t atyp;
1111         } s5_req, s5_rsp;
1112         u_int16_t dest_port;
1113         u_char *p, dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1114         u_int have, need, i, found, nmethods, addrlen, af;
1115
1116         debug2("channel %d: decode socks5", c->self);
1117         p = buffer_ptr(&c->input);
1118         if (p[0] != 0x05)
1119                 return -1;
1120         have = buffer_len(&c->input);
1121         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1122                 /* format: ver | nmethods | methods */
1123                 if (have < 2)
1124                         return 0;
1125                 nmethods = p[1];
1126                 if (have < nmethods + 2)
1127                         return 0;
1128                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1129                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1130                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1131                                 found = 1;
1132                                 break;
1133                         }
1134                 }
1135                 if (!found) {
1136                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1137                             c->self);
1138                         return -1;
1139                 }
1140                 buffer_consume(&c->input, nmethods + 2);
1141                 buffer_put_char(&c->output, 0x05);              /* version */
1142                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1143                 FD_SET(c->sock, writeset);
1144                 c->flags |= SSH_SOCKS5_AUTHDONE;
1145                 debug2("channel %d: socks5 auth done", c->self);
1146                 return 0;                               /* need more */
1147         }
1148         debug2("channel %d: socks5 post auth", c->self);
1149         if (have < sizeof(s5_req)+1)
1150                 return 0;                       /* need more */
1151         memcpy(&s5_req, p, sizeof(s5_req));
1152         if (s5_req.version != 0x05 ||
1153             s5_req.command != SSH_SOCKS5_CONNECT ||
1154             s5_req.reserved != 0x00) {
1155                 debug2("channel %d: only socks5 connect supported", c->self);
1156                 return -1;
1157         }
1158         switch (s5_req.atyp){
1159         case SSH_SOCKS5_IPV4:
1160                 addrlen = 4;
1161                 af = AF_INET;
1162                 break;
1163         case SSH_SOCKS5_DOMAIN:
1164                 addrlen = p[sizeof(s5_req)];
1165                 af = -1;
1166                 break;
1167         case SSH_SOCKS5_IPV6:
1168                 addrlen = 16;
1169                 af = AF_INET6;
1170                 break;
1171         default:
1172                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1173                 return -1;
1174         }
1175         need = sizeof(s5_req) + addrlen + 2;
1176         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1177                 need++;
1178         if (have < need)
1179                 return 0;
1180         buffer_consume(&c->input, sizeof(s5_req));
1181         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1182                 buffer_consume(&c->input, 1);    /* host string length */
1183         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1184         buffer_get(&c->input, (char *)&dest_port, 2);
1185         dest_addr[addrlen] = '\0';
1186         if (c->path != NULL) {
1187                 xfree(c->path);
1188                 c->path = NULL;
1189         }
1190         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1191                 if (addrlen >= NI_MAXHOST) {
1192                         error("channel %d: dynamic request: socks5 hostname "
1193                             "\"%.100s\" too long", c->self, dest_addr);
1194                         return -1;
1195                 }
1196                 c->path = xstrdup(dest_addr);
1197         } else {
1198                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1199                         return -1;
1200                 c->path = xstrdup(ntop);
1201         }
1202         c->host_port = ntohs(dest_port);
1203
1204         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1205             c->self, c->path, c->host_port, s5_req.command);
1206
1207         s5_rsp.version = 0x05;
1208         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1209         s5_rsp.reserved = 0;                    /* ignored */
1210         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1211         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1212         dest_port = 0;                          /* ignored */
1213
1214         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1215         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1216         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1217         return 1;
1218 }
1219
1220 Channel *
1221 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect)
1222 {
1223         Channel *c;
1224         int in, out;
1225
1226         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1227             port_to_connect);
1228
1229         in = dup(STDIN_FILENO);
1230         out = dup(STDOUT_FILENO);
1231         if (in < 0 || out < 0)
1232                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1233
1234         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1235             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1236             0, "stdio-forward", /*nonblock*/0);
1237
1238         c->path = xstrdup(host_to_connect);
1239         c->host_port = port_to_connect;
1240         c->listening_port = 0;
1241         c->force_drain = 1;
1242
1243         channel_register_fds(c, in, out, -1, 0, 1, 0);
1244         port_open_helper(c, "direct-tcpip");
1245
1246         return c;
1247 }
1248
1249 /* dynamic port forwarding */
1250 static void
1251 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1252 {
1253         u_char *p;
1254         u_int have;
1255         int ret;
1256
1257         have = buffer_len(&c->input);
1258         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1259         /* buffer_dump(&c->input); */
1260         /* check if the fixed size part of the packet is in buffer. */
1261         if (have < 3) {
1262                 /* need more */
1263                 FD_SET(c->sock, readset);
1264                 return;
1265         }
1266         /* try to guess the protocol */
1267         p = buffer_ptr(&c->input);
1268         switch (p[0]) {
1269         case 0x04:
1270                 ret = channel_decode_socks4(c, readset, writeset);
1271                 break;
1272         case 0x05:
1273                 ret = channel_decode_socks5(c, readset, writeset);
1274                 break;
1275         default:
1276                 ret = -1;
1277                 break;
1278         }
1279         if (ret < 0) {
1280                 chan_mark_dead(c);
1281         } else if (ret == 0) {
1282                 debug2("channel %d: pre_dynamic: need more", c->self);
1283                 /* need more */
1284                 FD_SET(c->sock, readset);
1285         } else {
1286                 /* switch to the next state */
1287                 c->type = SSH_CHANNEL_OPENING;
1288                 port_open_helper(c, "direct-tcpip");
1289         }
1290 }
1291
1292 /* This is our fake X11 server socket. */
1293 /* ARGSUSED */
1294 static void
1295 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1296 {
1297         Channel *nc;
1298         struct sockaddr_storage addr;
1299         int newsock;
1300         socklen_t addrlen;
1301         char buf[16384], *remote_ipaddr;
1302         int remote_port;
1303
1304         if (FD_ISSET(c->sock, readset)) {
1305                 debug("X11 connection requested.");
1306                 addrlen = sizeof(addr);
1307                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1308                 if (c->single_connection) {
1309                         debug2("single_connection: closing X11 listener.");
1310                         channel_close_fd(&c->sock);
1311                         chan_mark_dead(c);
1312                 }
1313                 if (newsock < 0) {
1314                         error("accept: %.100s", strerror(errno));
1315                         return;
1316                 }
1317                 set_nodelay(newsock);
1318                 remote_ipaddr = get_peer_ipaddr(newsock);
1319                 remote_port = get_peer_port(newsock);
1320                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1321                     remote_ipaddr, remote_port);
1322
1323                 nc = channel_new("accepted x11 socket",
1324                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1325                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1326                 if (compat20) {
1327                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1328                         packet_put_cstring("x11");
1329                         packet_put_int(nc->self);
1330                         packet_put_int(nc->local_window_max);
1331                         packet_put_int(nc->local_maxpacket);
1332                         /* originator ipaddr and port */
1333                         packet_put_cstring(remote_ipaddr);
1334                         if (datafellows & SSH_BUG_X11FWD) {
1335                                 debug2("ssh2 x11 bug compat mode");
1336                         } else {
1337                                 packet_put_int(remote_port);
1338                         }
1339                         packet_send();
1340                 } else {
1341                         packet_start(SSH_SMSG_X11_OPEN);
1342                         packet_put_int(nc->self);
1343                         if (packet_get_protocol_flags() &
1344                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1345                                 packet_put_cstring(buf);
1346                         packet_send();
1347                 }
1348                 xfree(remote_ipaddr);
1349         }
1350 }
1351
1352 static void
1353 port_open_helper(Channel *c, char *rtype)
1354 {
1355         int direct;
1356         char buf[1024];
1357         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1358         int remote_port = get_peer_port(c->sock);
1359
1360         direct = (strcmp(rtype, "direct-tcpip") == 0);
1361
1362         snprintf(buf, sizeof buf,
1363             "%s: listening port %d for %.100s port %d, "
1364             "connect from %.200s port %d",
1365             rtype, c->listening_port, c->path, c->host_port,
1366             remote_ipaddr, remote_port);
1367
1368         xfree(c->remote_name);
1369         c->remote_name = xstrdup(buf);
1370
1371         if (compat20) {
1372                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1373                 packet_put_cstring(rtype);
1374                 packet_put_int(c->self);
1375                 packet_put_int(c->local_window_max);
1376                 packet_put_int(c->local_maxpacket);
1377                 if (direct) {
1378                         /* target host, port */
1379                         packet_put_cstring(c->path);
1380                         packet_put_int(c->host_port);
1381                 } else {
1382                         /* listen address, port */
1383                         packet_put_cstring(c->path);
1384                         packet_put_int(c->listening_port);
1385                 }
1386                 /* originator host and port */
1387                 packet_put_cstring(remote_ipaddr);
1388                 packet_put_int((u_int)remote_port);
1389                 packet_send();
1390         } else {
1391                 packet_start(SSH_MSG_PORT_OPEN);
1392                 packet_put_int(c->self);
1393                 packet_put_cstring(c->path);
1394                 packet_put_int(c->host_port);
1395                 if (packet_get_protocol_flags() &
1396                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1397                         packet_put_cstring(c->remote_name);
1398                 packet_send();
1399         }
1400         xfree(remote_ipaddr);
1401 }
1402
1403 static void
1404 channel_set_reuseaddr(int fd)
1405 {
1406         int on = 1;
1407
1408         /*
1409          * Set socket options.
1410          * Allow local port reuse in TIME_WAIT.
1411          */
1412         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1413                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1414 }
1415
1416 /*
1417  * This socket is listening for connections to a forwarded TCP/IP port.
1418  */
1419 /* ARGSUSED */
1420 static void
1421 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1422 {
1423         Channel *nc;
1424         struct sockaddr_storage addr;
1425         int newsock, nextstate;
1426         socklen_t addrlen;
1427         char *rtype;
1428
1429         if (FD_ISSET(c->sock, readset)) {
1430                 debug("Connection to port %d forwarding "
1431                     "to %.100s port %d requested.",
1432                     c->listening_port, c->path, c->host_port);
1433
1434                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1435                         nextstate = SSH_CHANNEL_OPENING;
1436                         rtype = "forwarded-tcpip";
1437                 } else {
1438                         if (c->host_port == 0) {
1439                                 nextstate = SSH_CHANNEL_DYNAMIC;
1440                                 rtype = "dynamic-tcpip";
1441                         } else {
1442                                 nextstate = SSH_CHANNEL_OPENING;
1443                                 rtype = "direct-tcpip";
1444                         }
1445                 }
1446
1447                 addrlen = sizeof(addr);
1448                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1449                 if (newsock < 0) {
1450                         error("accept: %.100s", strerror(errno));
1451                         return;
1452                 }
1453                 set_nodelay(newsock);
1454                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1455                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1456                 nc->listening_port = c->listening_port;
1457                 nc->host_port = c->host_port;
1458                 if (c->path != NULL)
1459                         nc->path = xstrdup(c->path);
1460
1461                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1462                         port_open_helper(nc, rtype);
1463         }
1464 }
1465
1466 /*
1467  * This is the authentication agent socket listening for connections from
1468  * clients.
1469  */
1470 /* ARGSUSED */
1471 static void
1472 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1473 {
1474         Channel *nc;
1475         int newsock;
1476         struct sockaddr_storage addr;
1477         socklen_t addrlen;
1478
1479         if (FD_ISSET(c->sock, readset)) {
1480                 addrlen = sizeof(addr);
1481                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1482                 if (newsock < 0) {
1483                         error("accept from auth socket: %.100s", strerror(errno));
1484                         return;
1485                 }
1486                 nc = channel_new("accepted auth socket",
1487                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1488                     c->local_window_max, c->local_maxpacket,
1489                     0, "accepted auth socket", 1);
1490                 if (compat20) {
1491                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1492                         packet_put_cstring("auth-agent@openssh.com");
1493                         packet_put_int(nc->self);
1494                         packet_put_int(c->local_window_max);
1495                         packet_put_int(c->local_maxpacket);
1496                 } else {
1497                         packet_start(SSH_SMSG_AGENT_OPEN);
1498                         packet_put_int(nc->self);
1499                 }
1500                 packet_send();
1501         }
1502 }
1503
1504 /* ARGSUSED */
1505 static void
1506 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1507 {
1508         int err = 0, sock;
1509         socklen_t sz = sizeof(err);
1510
1511         if (FD_ISSET(c->sock, writeset)) {
1512                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1513                         err = errno;
1514                         error("getsockopt SO_ERROR failed");
1515                 }
1516                 if (err == 0) {
1517                         debug("channel %d: connected to %s port %d",
1518                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1519                         channel_connect_ctx_free(&c->connect_ctx);
1520                         c->type = SSH_CHANNEL_OPEN;
1521                         if (compat20) {
1522                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1523                                 packet_put_int(c->remote_id);
1524                                 packet_put_int(c->self);
1525                                 packet_put_int(c->local_window);
1526                                 packet_put_int(c->local_maxpacket);
1527                         } else {
1528                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1529                                 packet_put_int(c->remote_id);
1530                                 packet_put_int(c->self);
1531                         }
1532                 } else {
1533                         debug("channel %d: connection failed: %s",
1534                             c->self, strerror(err));
1535                         /* Try next address, if any */
1536                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1537                                 close(c->sock);
1538                                 c->sock = c->rfd = c->wfd = sock;
1539                                 channel_max_fd = channel_find_maxfd();
1540                                 return;
1541                         }
1542                         /* Exhausted all addresses */
1543                         error("connect_to %.100s port %d: failed.",
1544                             c->connect_ctx.host, c->connect_ctx.port);
1545                         channel_connect_ctx_free(&c->connect_ctx);
1546                         if (compat20) {
1547                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1548                                 packet_put_int(c->remote_id);
1549                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1550                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1551                                         packet_put_cstring(strerror(err));
1552                                         packet_put_cstring("");
1553                                 }
1554                         } else {
1555                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1556                                 packet_put_int(c->remote_id);
1557                         }
1558                         chan_mark_dead(c);
1559                 }
1560                 packet_send();
1561         }
1562 }
1563
1564 /* ARGSUSED */
1565 static int
1566 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1567 {
1568         char buf[CHAN_RBUF];
1569         int len, force;
1570
1571         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1572         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1573                 errno = 0;
1574                 len = read(c->rfd, buf, sizeof(buf));
1575                 if (len < 0 && (errno == EINTR ||
1576                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1577                         return 1;
1578 #ifndef PTY_ZEROREAD
1579                 if (len <= 0) {
1580 #else
1581                 if ((!c->isatty && len <= 0) ||
1582                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1583 #endif
1584                         debug2("channel %d: read<=0 rfd %d len %d",
1585                             c->self, c->rfd, len);
1586                         if (c->type != SSH_CHANNEL_OPEN) {
1587                                 debug2("channel %d: not open", c->self);
1588                                 chan_mark_dead(c);
1589                                 return -1;
1590                         } else if (compat13) {
1591                                 buffer_clear(&c->output);
1592                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1593                                 debug2("channel %d: input draining.", c->self);
1594                         } else {
1595                                 chan_read_failed(c);
1596                         }
1597                         return -1;
1598                 }
1599                 if (c->input_filter != NULL) {
1600                         if (c->input_filter(c, buf, len) == -1) {
1601                                 debug2("channel %d: filter stops", c->self);
1602                                 chan_read_failed(c);
1603                         }
1604                 } else if (c->datagram) {
1605                         buffer_put_string(&c->input, buf, len);
1606                 } else {
1607                         buffer_append(&c->input, buf, len);
1608                 }
1609         }
1610         return 1;
1611 }
1612
1613 /* ARGSUSED */
1614 static int
1615 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1616 {
1617         struct termios tio;
1618         u_char *data = NULL, *buf;
1619         u_int dlen;
1620         int len;
1621
1622         /* Send buffered output data to the socket. */
1623         if (c->wfd != -1 &&
1624             FD_ISSET(c->wfd, writeset) &&
1625             buffer_len(&c->output) > 0) {
1626                 if (c->output_filter != NULL) {
1627                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1628                                 debug2("channel %d: filter stops", c->self);
1629                                 if (c->type != SSH_CHANNEL_OPEN)
1630                                         chan_mark_dead(c);
1631                                 else
1632                                         chan_write_failed(c);
1633                                 return -1;
1634                         }
1635                 } else if (c->datagram) {
1636                         buf = data = buffer_get_string(&c->output, &dlen);
1637                 } else {
1638                         buf = data = buffer_ptr(&c->output);
1639                         dlen = buffer_len(&c->output);
1640                 }
1641
1642                 if (c->datagram) {
1643                         /* ignore truncated writes, datagrams might get lost */
1644                         c->local_consumed += dlen + 4;
1645                         len = write(c->wfd, buf, dlen);
1646                         xfree(data);
1647                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1648                             errno == EWOULDBLOCK))
1649                                 return 1;
1650                         if (len <= 0) {
1651                                 if (c->type != SSH_CHANNEL_OPEN)
1652                                         chan_mark_dead(c);
1653                                 else
1654                                         chan_write_failed(c);
1655                                 return -1;
1656                         }
1657                         return 1;
1658                 }
1659 #ifdef _AIX
1660                 /* XXX: Later AIX versions can't push as much data to tty */
1661                 if (compat20 && c->wfd_isatty)
1662                         dlen = MIN(dlen, 8*1024);
1663 #endif
1664
1665                 len = write(c->wfd, buf, dlen);
1666                 if (len < 0 &&
1667                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1668                         return 1;
1669                 if (len <= 0) {
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                                 debug2("channel %d: input draining.", c->self);
1677                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1678                         } else {
1679                                 chan_write_failed(c);
1680                         }
1681                         return -1;
1682                 }
1683 #ifndef BROKEN_TCGETATTR_ICANON
1684                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1685                         if (tcgetattr(c->wfd, &tio) == 0 &&
1686                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1687                                 /*
1688                                  * Simulate echo to reduce the impact of
1689                                  * traffic analysis. We need to match the
1690                                  * size of a SSH2_MSG_CHANNEL_DATA message
1691                                  * (4 byte channel id + buf)
1692                                  */
1693                                 packet_send_ignore(4 + len);
1694                                 packet_send();
1695                         }
1696                 }
1697 #endif
1698                 buffer_consume(&c->output, len);
1699                 if (compat20 && len > 0) {
1700                         c->local_consumed += len;
1701                 }
1702         }
1703         return 1;
1704 }
1705
1706 static int
1707 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1708 {
1709         char buf[CHAN_RBUF];
1710         int len;
1711
1712 /** XXX handle drain efd, too */
1713         if (c->efd != -1) {
1714                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1715                     FD_ISSET(c->efd, writeset) &&
1716                     buffer_len(&c->extended) > 0) {
1717                         len = write(c->efd, buffer_ptr(&c->extended),
1718                             buffer_len(&c->extended));
1719                         debug2("channel %d: written %d to efd %d",
1720                             c->self, len, c->efd);
1721                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1722                             errno == EWOULDBLOCK))
1723                                 return 1;
1724                         if (len <= 0) {
1725                                 debug2("channel %d: closing write-efd %d",
1726                                     c->self, c->efd);
1727                                 channel_close_fd(&c->efd);
1728                         } else {
1729                                 buffer_consume(&c->extended, len);
1730                                 c->local_consumed += len;
1731                         }
1732                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1733                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1734                         len = read(c->efd, buf, sizeof(buf));
1735                         debug2("channel %d: read %d from efd %d",
1736                             c->self, len, c->efd);
1737                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1738                             errno == EWOULDBLOCK) && !c->detach_close)))
1739                                 return 1;
1740                         if (len <= 0) {
1741                                 debug2("channel %d: closing read-efd %d",
1742                                     c->self, c->efd);
1743                                 channel_close_fd(&c->efd);
1744                         } else {
1745                                 buffer_append(&c->extended, buf, len);
1746                         }
1747                 }
1748         }
1749         return 1;
1750 }
1751
1752 /* ARGSUSED */
1753 static int
1754 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1755 {
1756         char buf[16];
1757         int len;
1758
1759         /* Monitor control fd to detect if the slave client exits */
1760         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1761                 len = read(c->ctl_fd, buf, sizeof(buf));
1762                 if (len < 0 &&
1763                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1764                         return 1;
1765                 if (len <= 0) {
1766                         debug2("channel %d: ctl read<=0", c->self);
1767                         if (c->type != SSH_CHANNEL_OPEN) {
1768                                 debug2("channel %d: not open", c->self);
1769                                 chan_mark_dead(c);
1770                                 return -1;
1771                         } else {
1772                                 chan_read_failed(c);
1773                                 chan_write_failed(c);
1774                         }
1775                         return -1;
1776                 } else
1777                         fatal("%s: unexpected data on ctl fd", __func__);
1778         }
1779         return 1;
1780 }
1781
1782 static int
1783 channel_check_window(Channel *c)
1784 {
1785         if (c->type == SSH_CHANNEL_OPEN &&
1786             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1787             ((c->local_window_max - c->local_window >
1788             c->local_maxpacket*3) ||
1789             c->local_window < c->local_window_max/2) &&
1790             c->local_consumed > 0) {
1791                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1792                 packet_put_int(c->remote_id);
1793                 packet_put_int(c->local_consumed);
1794                 packet_send();
1795                 debug2("channel %d: window %d sent adjust %d",
1796                     c->self, c->local_window,
1797                     c->local_consumed);
1798                 c->local_window += c->local_consumed;
1799                 c->local_consumed = 0;
1800         }
1801         return 1;
1802 }
1803
1804 static void
1805 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1806 {
1807         channel_handle_rfd(c, readset, writeset);
1808         channel_handle_wfd(c, readset, writeset);
1809         if (!compat20)
1810                 return;
1811         channel_handle_efd(c, readset, writeset);
1812         channel_handle_ctl(c, readset, writeset);
1813         channel_check_window(c);
1814 }
1815
1816 /* ARGSUSED */
1817 static void
1818 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1819 {
1820         int len;
1821
1822         /* Send buffered output data to the socket. */
1823         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1824                 len = write(c->sock, buffer_ptr(&c->output),
1825                             buffer_len(&c->output));
1826                 if (len <= 0)
1827                         buffer_clear(&c->output);
1828                 else
1829                         buffer_consume(&c->output, len);
1830         }
1831 }
1832
1833 static void
1834 channel_handler_init_20(void)
1835 {
1836         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1837         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1838         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1839         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1840         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1841         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1842         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1843         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1844
1845         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1846         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1847         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1848         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1849         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1850         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1851         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1852 }
1853
1854 static void
1855 channel_handler_init_13(void)
1856 {
1857         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1858         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1859         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1860         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1861         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1862         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1863         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1864         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1865         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1866
1867         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1868         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1869         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1870         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1871         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1872         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1873         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1874 }
1875
1876 static void
1877 channel_handler_init_15(void)
1878 {
1879         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1880         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1881         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1882         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1883         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1884         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1885         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1886
1887         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1888         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1889         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1890         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1891         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1892         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1893 }
1894
1895 static void
1896 channel_handler_init(void)
1897 {
1898         int i;
1899
1900         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1901                 channel_pre[i] = NULL;
1902                 channel_post[i] = NULL;
1903         }
1904         if (compat20)
1905                 channel_handler_init_20();
1906         else if (compat13)
1907                 channel_handler_init_13();
1908         else
1909                 channel_handler_init_15();
1910 }
1911
1912 /* gc dead channels */
1913 static void
1914 channel_garbage_collect(Channel *c)
1915 {
1916         if (c == NULL)
1917                 return;
1918         if (c->detach_user != NULL) {
1919                 if (!chan_is_dead(c, c->detach_close))
1920                         return;
1921                 debug2("channel %d: gc: notify user", c->self);
1922                 c->detach_user(c->self, NULL);
1923                 /* if we still have a callback */
1924                 if (c->detach_user != NULL)
1925                         return;
1926                 debug2("channel %d: gc: user detached", c->self);
1927         }
1928         if (!chan_is_dead(c, 1))
1929                 return;
1930         debug2("channel %d: garbage collecting", c->self);
1931         channel_free(c);
1932 }
1933
1934 static void
1935 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1936 {
1937         static int did_init = 0;
1938         u_int i, oalloc;
1939         Channel *c;
1940
1941         if (!did_init) {
1942                 channel_handler_init();
1943                 did_init = 1;
1944         }
1945         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
1946                 c = channels[i];
1947                 if (c == NULL)
1948                         continue;
1949                 if (c->delayed) {
1950                         if (ftab == channel_pre)
1951                                 c->delayed = 0;
1952                         else
1953                                 continue;
1954                 }
1955                 if (ftab[c->type] != NULL)
1956                         (*ftab[c->type])(c, readset, writeset);
1957                 channel_garbage_collect(c);
1958         }
1959 }
1960
1961 /*
1962  * Allocate/update select bitmasks and add any bits relevant to channels in
1963  * select bitmasks.
1964  */
1965 void
1966 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1967     u_int *nallocp, int rekeying)
1968 {
1969         u_int n, sz, nfdset;
1970
1971         n = MAX(*maxfdp, channel_max_fd);
1972
1973         nfdset = howmany(n+1, NFDBITS);
1974         /* Explicitly test here, because xrealloc isn't always called */
1975         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1976                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1977         sz = nfdset * sizeof(fd_mask);
1978
1979         /* perhaps check sz < nalloc/2 and shrink? */
1980         if (*readsetp == NULL || sz > *nallocp) {
1981                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1982                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1983                 *nallocp = sz;
1984         }
1985         *maxfdp = n;
1986         memset(*readsetp, 0, sz);
1987         memset(*writesetp, 0, sz);
1988
1989         if (!rekeying)
1990                 channel_handler(channel_pre, *readsetp, *writesetp);
1991 }
1992
1993 /*
1994  * After select, perform any appropriate operations for channels which have
1995  * events pending.
1996  */
1997 void
1998 channel_after_select(fd_set *readset, fd_set *writeset)
1999 {
2000         channel_handler(channel_post, readset, writeset);
2001 }
2002
2003
2004 /* If there is data to send to the connection, enqueue some of it now. */
2005 void
2006 channel_output_poll(void)
2007 {
2008         Channel *c;
2009         u_int i, len;
2010
2011         for (i = 0; i < channels_alloc; i++) {
2012                 c = channels[i];
2013                 if (c == NULL)
2014                         continue;
2015
2016                 /*
2017                  * We are only interested in channels that can have buffered
2018                  * incoming data.
2019                  */
2020                 if (compat13) {
2021                         if (c->type != SSH_CHANNEL_OPEN &&
2022                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2023                                 continue;
2024                 } else {
2025                         if (c->type != SSH_CHANNEL_OPEN)
2026                                 continue;
2027                 }
2028                 if (compat20 &&
2029                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2030                         /* XXX is this true? */
2031                         debug3("channel %d: will not send data after close", c->self);
2032                         continue;
2033                 }
2034
2035                 /* Get the amount of buffered data for this channel. */
2036                 if ((c->istate == CHAN_INPUT_OPEN ||
2037                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2038                     (len = buffer_len(&c->input)) > 0) {
2039                         if (c->datagram) {
2040                                 if (len > 0) {
2041                                         u_char *data;
2042                                         u_int dlen;
2043
2044                                         data = buffer_get_string(&c->input,
2045                                             &dlen);
2046                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2047                                         packet_put_int(c->remote_id);
2048                                         packet_put_string(data, dlen);
2049                                         packet_send();
2050                                         c->remote_window -= dlen + 4;
2051                                         xfree(data);
2052                                 }
2053                                 continue;
2054                         }
2055                         /*
2056                          * Send some data for the other side over the secure
2057                          * connection.
2058                          */
2059                         if (compat20) {
2060                                 if (len > c->remote_window)
2061                                         len = c->remote_window;
2062                                 if (len > c->remote_maxpacket)
2063                                         len = c->remote_maxpacket;
2064                         } else {
2065                                 if (packet_is_interactive()) {
2066                                         if (len > 1024)
2067                                                 len = 512;
2068                                 } else {
2069                                         /* Keep the packets at reasonable size. */
2070                                         if (len > packet_get_maxsize()/2)
2071                                                 len = packet_get_maxsize()/2;
2072                                 }
2073                         }
2074                         if (len > 0) {
2075                                 packet_start(compat20 ?
2076                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2077                                 packet_put_int(c->remote_id);
2078                                 packet_put_string(buffer_ptr(&c->input), len);
2079                                 packet_send();
2080                                 buffer_consume(&c->input, len);
2081                                 c->remote_window -= len;
2082                         }
2083                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2084                         if (compat13)
2085                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2086                         /*
2087                          * input-buffer is empty and read-socket shutdown:
2088                          * tell peer, that we will not send more data: send IEOF.
2089                          * hack for extended data: delay EOF if EFD still in use.
2090                          */
2091                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2092                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2093                                     c->self, c->efd, buffer_len(&c->extended));
2094                         else
2095                                 chan_ibuf_empty(c);
2096                 }
2097                 /* Send extended data, i.e. stderr */
2098                 if (compat20 &&
2099                     !(c->flags & CHAN_EOF_SENT) &&
2100                     c->remote_window > 0 &&
2101                     (len = buffer_len(&c->extended)) > 0 &&
2102                     c->extended_usage == CHAN_EXTENDED_READ) {
2103                         debug2("channel %d: rwin %u elen %u euse %d",
2104                             c->self, c->remote_window, buffer_len(&c->extended),
2105                             c->extended_usage);
2106                         if (len > c->remote_window)
2107                                 len = c->remote_window;
2108                         if (len > c->remote_maxpacket)
2109                                 len = c->remote_maxpacket;
2110                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2111                         packet_put_int(c->remote_id);
2112                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2113                         packet_put_string(buffer_ptr(&c->extended), len);
2114                         packet_send();
2115                         buffer_consume(&c->extended, len);
2116                         c->remote_window -= len;
2117                         debug2("channel %d: sent ext data %d", c->self, len);
2118                 }
2119         }
2120 }
2121
2122
2123 /* -- protocol input */
2124
2125 /* ARGSUSED */
2126 void
2127 channel_input_data(int type, u_int32_t seq, void *ctxt)
2128 {
2129         int id;
2130         char *data;
2131         u_int data_len;
2132         Channel *c;
2133
2134         /* Get the channel number and verify it. */
2135         id = packet_get_int();
2136         c = channel_lookup(id);
2137         if (c == NULL)
2138                 packet_disconnect("Received data for nonexistent channel %d.", id);
2139
2140         /* Ignore any data for non-open channels (might happen on close) */
2141         if (c->type != SSH_CHANNEL_OPEN &&
2142             c->type != SSH_CHANNEL_X11_OPEN)
2143                 return;
2144
2145         /* Get the data. */
2146         data = packet_get_string_ptr(&data_len);
2147
2148         /*
2149          * Ignore data for protocol > 1.3 if output end is no longer open.
2150          * For protocol 2 the sending side is reducing its window as it sends
2151          * data, so we must 'fake' consumption of the data in order to ensure
2152          * that window updates are sent back.  Otherwise the connection might
2153          * deadlock.
2154          */
2155         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2156                 if (compat20) {
2157                         c->local_window -= data_len;
2158                         c->local_consumed += data_len;
2159                 }
2160                 return;
2161         }
2162
2163         if (compat20) {
2164                 if (data_len > c->local_maxpacket) {
2165                         logit("channel %d: rcvd big packet %d, maxpack %d",
2166                             c->self, data_len, c->local_maxpacket);
2167                 }
2168                 if (data_len > c->local_window) {
2169                         logit("channel %d: rcvd too much data %d, win %d",
2170                             c->self, data_len, c->local_window);
2171                         return;
2172                 }
2173                 c->local_window -= data_len;
2174         }
2175         if (c->datagram)
2176                 buffer_put_string(&c->output, data, data_len);
2177         else
2178                 buffer_append(&c->output, data, data_len);
2179         packet_check_eom();
2180 }
2181
2182 /* ARGSUSED */
2183 void
2184 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2185 {
2186         int id;
2187         char *data;
2188         u_int data_len, tcode;
2189         Channel *c;
2190
2191         /* Get the channel number and verify it. */
2192         id = packet_get_int();
2193         c = channel_lookup(id);
2194
2195         if (c == NULL)
2196                 packet_disconnect("Received extended_data for bad channel %d.", id);
2197         if (c->type != SSH_CHANNEL_OPEN) {
2198                 logit("channel %d: ext data for non open", id);
2199                 return;
2200         }
2201         if (c->flags & CHAN_EOF_RCVD) {
2202                 if (datafellows & SSH_BUG_EXTEOF)
2203                         debug("channel %d: accepting ext data after eof", id);
2204                 else
2205                         packet_disconnect("Received extended_data after EOF "
2206                             "on channel %d.", id);
2207         }
2208         tcode = packet_get_int();
2209         if (c->efd == -1 ||
2210             c->extended_usage != CHAN_EXTENDED_WRITE ||
2211             tcode != SSH2_EXTENDED_DATA_STDERR) {
2212                 logit("channel %d: bad ext data", c->self);
2213                 return;
2214         }
2215         data = packet_get_string(&data_len);
2216         packet_check_eom();
2217         if (data_len > c->local_window) {
2218                 logit("channel %d: rcvd too much extended_data %d, win %d",
2219                     c->self, data_len, c->local_window);
2220                 xfree(data);
2221                 return;
2222         }
2223         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2224         c->local_window -= data_len;
2225         buffer_append(&c->extended, data, data_len);
2226         xfree(data);
2227 }
2228
2229 /* ARGSUSED */
2230 void
2231 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2232 {
2233         int id;
2234         Channel *c;
2235
2236         id = packet_get_int();
2237         packet_check_eom();
2238         c = channel_lookup(id);
2239         if (c == NULL)
2240                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2241         chan_rcvd_ieof(c);
2242
2243         /* XXX force input close */
2244         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2245                 debug("channel %d: FORCE input drain", c->self);
2246                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2247                 if (buffer_len(&c->input) == 0)
2248                         chan_ibuf_empty(c);
2249         }
2250
2251 }
2252
2253 /* ARGSUSED */
2254 void
2255 channel_input_close(int type, u_int32_t seq, void *ctxt)
2256 {
2257         int id;
2258         Channel *c;
2259
2260         id = packet_get_int();
2261         packet_check_eom();
2262         c = channel_lookup(id);
2263         if (c == NULL)
2264                 packet_disconnect("Received close for nonexistent channel %d.", id);
2265
2266         /*
2267          * Send a confirmation that we have closed the channel and no more
2268          * data is coming for it.
2269          */
2270         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2271         packet_put_int(c->remote_id);
2272         packet_send();
2273
2274         /*
2275          * If the channel is in closed state, we have sent a close request,
2276          * and the other side will eventually respond with a confirmation.
2277          * Thus, we cannot free the channel here, because then there would be
2278          * no-one to receive the confirmation.  The channel gets freed when
2279          * the confirmation arrives.
2280          */
2281         if (c->type != SSH_CHANNEL_CLOSED) {
2282                 /*
2283                  * Not a closed channel - mark it as draining, which will
2284                  * cause it to be freed later.
2285                  */
2286                 buffer_clear(&c->input);
2287                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2288         }
2289 }
2290
2291 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2292 /* ARGSUSED */
2293 void
2294 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2295 {
2296         int id = packet_get_int();
2297         Channel *c = channel_lookup(id);
2298
2299         packet_check_eom();
2300         if (c == NULL)
2301                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2302         chan_rcvd_oclose(c);
2303 }
2304
2305 /* ARGSUSED */
2306 void
2307 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2308 {
2309         int id = packet_get_int();
2310         Channel *c = channel_lookup(id);
2311
2312         packet_check_eom();
2313         if (c == NULL)
2314                 packet_disconnect("Received close confirmation for "
2315                     "out-of-range channel %d.", id);
2316         if (c->type != SSH_CHANNEL_CLOSED)
2317                 packet_disconnect("Received close confirmation for "
2318                     "non-closed channel %d (type %d).", id, c->type);
2319         channel_free(c);
2320 }
2321
2322 /* ARGSUSED */
2323 void
2324 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2325 {
2326         int id, remote_id;
2327         Channel *c;
2328
2329         id = packet_get_int();
2330         c = channel_lookup(id);
2331
2332         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2333                 packet_disconnect("Received open confirmation for "
2334                     "non-opening channel %d.", id);
2335         remote_id = packet_get_int();
2336         /* Record the remote channel number and mark that the channel is now open. */
2337         c->remote_id = remote_id;
2338         c->type = SSH_CHANNEL_OPEN;
2339
2340         if (compat20) {
2341                 c->remote_window = packet_get_int();
2342                 c->remote_maxpacket = packet_get_int();
2343                 if (c->open_confirm) {
2344                         debug2("callback start");
2345                         c->open_confirm(c->self, c->open_confirm_ctx);
2346                         debug2("callback done");
2347                 }
2348                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2349                     c->remote_window, c->remote_maxpacket);
2350         }
2351         packet_check_eom();
2352 }
2353
2354 static char *
2355 reason2txt(int reason)
2356 {
2357         switch (reason) {
2358         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2359                 return "administratively prohibited";
2360         case SSH2_OPEN_CONNECT_FAILED:
2361                 return "connect failed";
2362         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2363                 return "unknown channel type";
2364         case SSH2_OPEN_RESOURCE_SHORTAGE:
2365                 return "resource shortage";
2366         }
2367         return "unknown reason";
2368 }
2369
2370 /* ARGSUSED */
2371 void
2372 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2373 {
2374         int id, reason;
2375         char *msg = NULL, *lang = NULL;
2376         Channel *c;
2377
2378         id = packet_get_int();
2379         c = channel_lookup(id);
2380
2381         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2382                 packet_disconnect("Received open failure for "
2383                     "non-opening channel %d.", id);
2384         if (compat20) {
2385                 reason = packet_get_int();
2386                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2387                         msg  = packet_get_string(NULL);
2388                         lang = packet_get_string(NULL);
2389                 }
2390                 logit("channel %d: open failed: %s%s%s", id,
2391                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2392                 if (msg != NULL)
2393                         xfree(msg);
2394                 if (lang != NULL)
2395                         xfree(lang);
2396         }
2397         packet_check_eom();
2398         /* Schedule the channel for cleanup/deletion. */
2399         chan_mark_dead(c);
2400 }
2401
2402 /* ARGSUSED */
2403 void
2404 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2405 {
2406         Channel *c;
2407         int id;
2408         u_int adjust;
2409
2410         if (!compat20)
2411                 return;
2412
2413         /* Get the channel number and verify it. */
2414         id = packet_get_int();
2415         c = channel_lookup(id);
2416
2417         if (c == NULL) {
2418                 logit("Received window adjust for non-open channel %d.", id);
2419                 return;
2420         }
2421         adjust = packet_get_int();
2422         packet_check_eom();
2423         debug2("channel %d: rcvd adjust %u", id, adjust);
2424         c->remote_window += adjust;
2425 }
2426
2427 /* ARGSUSED */
2428 void
2429 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2430 {
2431         Channel *c = NULL;
2432         u_short host_port;
2433         char *host, *originator_string;
2434         int remote_id;
2435
2436         remote_id = packet_get_int();
2437         host = packet_get_string(NULL);
2438         host_port = packet_get_int();
2439
2440         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2441                 originator_string = packet_get_string(NULL);
2442         } else {
2443                 originator_string = xstrdup("unknown (remote did not supply name)");
2444         }
2445         packet_check_eom();
2446         c = channel_connect_to(host, host_port,
2447             "connected socket", originator_string);
2448         xfree(originator_string);
2449         xfree(host);
2450         if (c == NULL) {
2451                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2452                 packet_put_int(remote_id);
2453                 packet_send();
2454         } else
2455                 c->remote_id = remote_id;
2456 }
2457
2458 /* ARGSUSED */
2459 void
2460 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2461 {
2462         Channel *c;
2463         struct channel_confirm *cc;
2464         int id;
2465
2466         /* Reset keepalive timeout */
2467         packet_set_alive_timeouts(0);
2468
2469         id = packet_get_int();
2470         packet_check_eom();
2471
2472         debug2("channel_input_status_confirm: type %d id %d", type, id);
2473
2474         if ((c = channel_lookup(id)) == NULL) {
2475                 logit("channel_input_status_confirm: %d: unknown", id);
2476                 return;
2477         }
2478         ;
2479         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2480                 return;
2481         cc->cb(type, c, cc->ctx);
2482         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2483         bzero(cc, sizeof(*cc));
2484         xfree(cc);
2485 }
2486
2487 /* -- tcp forwarding */
2488
2489 void
2490 channel_set_af(int af)
2491 {
2492         IPv4or6 = af;
2493 }
2494
2495 static int
2496 channel_setup_fwd_listener(int type, const char *listen_addr,
2497     u_short listen_port, int *allocated_listen_port,
2498     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2499 {
2500         Channel *c;
2501         int sock, r, success = 0, wildcard = 0, is_client;
2502         struct addrinfo hints, *ai, *aitop;
2503         const char *host, *addr;
2504         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2505         in_port_t *lport_p;
2506
2507         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2508             listen_addr : host_to_connect;
2509         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2510
2511         if (host == NULL) {
2512                 error("No forward host name.");
2513                 return 0;
2514         }
2515         if (strlen(host) >= NI_MAXHOST) {
2516                 error("Forward host name too long.");
2517                 return 0;
2518         }
2519
2520         /*
2521          * Determine whether or not a port forward listens to loopback,
2522          * specified address or wildcard. On the client, a specified bind
2523          * address will always override gateway_ports. On the server, a
2524          * gateway_ports of 1 (``yes'') will override the client's
2525          * specification and force a wildcard bind, whereas a value of 2
2526          * (``clientspecified'') will bind to whatever address the client
2527          * asked for.
2528          *
2529          * Special-case listen_addrs are:
2530          *
2531          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2532          * "" (empty string), "*"  -> wildcard v4/v6
2533          * "localhost"             -> loopback v4/v6
2534          */
2535         addr = NULL;
2536         if (listen_addr == NULL) {
2537                 /* No address specified: default to gateway_ports setting */
2538                 if (gateway_ports)
2539                         wildcard = 1;
2540         } else if (gateway_ports || is_client) {
2541                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2542                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2543                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2544                     (!is_client && gateway_ports == 1))
2545                         wildcard = 1;
2546                 else if (strcmp(listen_addr, "localhost") != 0)
2547                         addr = listen_addr;
2548         }
2549
2550         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2551             type, wildcard, (addr == NULL) ? "NULL" : addr);
2552
2553         /*
2554          * getaddrinfo returns a loopback address if the hostname is
2555          * set to NULL and hints.ai_flags is not AI_PASSIVE
2556          */
2557         memset(&hints, 0, sizeof(hints));
2558         hints.ai_family = IPv4or6;
2559         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2560         hints.ai_socktype = SOCK_STREAM;
2561         snprintf(strport, sizeof strport, "%d", listen_port);
2562         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2563                 if (addr == NULL) {
2564                         /* This really shouldn't happen */
2565                         packet_disconnect("getaddrinfo: fatal error: %s",
2566                             ssh_gai_strerror(r));
2567                 } else {
2568                         error("channel_setup_fwd_listener: "
2569                             "getaddrinfo(%.64s): %s", addr,
2570                             ssh_gai_strerror(r));
2571                 }
2572                 return 0;
2573         }
2574         if (allocated_listen_port != NULL)
2575                 *allocated_listen_port = 0;
2576         for (ai = aitop; ai; ai = ai->ai_next) {
2577                 switch (ai->ai_family) {
2578                 case AF_INET:
2579                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2580                             sin_port;
2581                         break;
2582                 case AF_INET6:
2583                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2584                             sin6_port;
2585                         break;
2586                 default:
2587                         continue;
2588                 }
2589                 /*
2590                  * If allocating a port for -R forwards, then use the
2591                  * same port for all address families.
2592                  */
2593                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2594                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2595                         *lport_p = htons(*allocated_listen_port);
2596
2597                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2598                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2599                         error("channel_setup_fwd_listener: getnameinfo failed");
2600                         continue;
2601                 }
2602                 /* Create a port to listen for the host. */
2603                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2604                 if (sock < 0) {
2605                         /* this is no error since kernel may not support ipv6 */
2606                         verbose("socket: %.100s", strerror(errno));
2607                         continue;
2608                 }
2609
2610                 channel_set_reuseaddr(sock);
2611                 if (ai->ai_family == AF_INET6)
2612                         sock_set_v6only(sock);
2613
2614                 debug("Local forwarding listening on %s port %s.",
2615                     ntop, strport);
2616
2617                 /* Bind the socket to the address. */
2618                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2619                         /* address can be in use ipv6 address is already bound */
2620                         if (!ai->ai_next)
2621                                 error("bind: %.100s", strerror(errno));
2622                         else
2623                                 verbose("bind: %.100s", strerror(errno));
2624
2625                         close(sock);
2626                         continue;
2627                 }
2628                 /* Start listening for connections on the socket. */
2629                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2630                         error("listen: %.100s", strerror(errno));
2631                         close(sock);
2632                         continue;
2633                 }
2634
2635                 /*
2636                  * listen_port == 0 requests a dynamically allocated port -
2637                  * record what we got.
2638                  */
2639                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2640                     allocated_listen_port != NULL &&
2641                     *allocated_listen_port == 0) {
2642                         *allocated_listen_port = get_sock_port(sock, 1);
2643                         debug("Allocated listen port %d",
2644                             *allocated_listen_port);
2645                 }
2646
2647                 /* Allocate a channel number for the socket. */
2648                 c = channel_new("port listener", type, sock, sock, -1,
2649                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2650                     0, "port listener", 1);
2651                 c->path = xstrdup(host);
2652                 c->host_port = port_to_connect;
2653                 c->listening_port = listen_port;
2654                 success = 1;
2655         }
2656         if (success == 0)
2657                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2658                     listen_port);
2659         freeaddrinfo(aitop);
2660         return success;
2661 }
2662
2663 int
2664 channel_cancel_rport_listener(const char *host, u_short port)
2665 {
2666         u_int i;
2667         int found = 0;
2668
2669         for (i = 0; i < channels_alloc; i++) {
2670                 Channel *c = channels[i];
2671
2672                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2673                     strcmp(c->path, host) == 0 && c->listening_port == port) {
2674                         debug2("%s: close channel %d", __func__, i);
2675                         channel_free(c);
2676                         found = 1;
2677                 }
2678         }
2679
2680         return (found);
2681 }
2682
2683 /* protocol local port fwd, used by ssh (and sshd in v1) */
2684 int
2685 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2686     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2687 {
2688         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2689             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2690             gateway_ports);
2691 }
2692
2693 /* protocol v2 remote port fwd, used by sshd */
2694 int
2695 channel_setup_remote_fwd_listener(const char *listen_address,
2696     u_short listen_port, int *allocated_listen_port, int gateway_ports)
2697 {
2698         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2699             listen_address, listen_port, allocated_listen_port,
2700             NULL, 0, gateway_ports);
2701 }
2702
2703 /*
2704  * Initiate forwarding of connections to port "port" on remote host through
2705  * the secure channel to host:port from local side.
2706  */
2707
2708 int
2709 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2710     const char *host_to_connect, u_short port_to_connect)
2711 {
2712         int type, success = 0;
2713
2714         /* Record locally that connection to this host/port is permitted. */
2715         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2716                 fatal("channel_request_remote_forwarding: too many forwards");
2717
2718         /* Send the forward request to the remote side. */
2719         if (compat20) {
2720                 const char *address_to_bind;
2721                 if (listen_host == NULL) {
2722                         if (datafellows & SSH_BUG_RFWD_ADDR)
2723                                 address_to_bind = "127.0.0.1";
2724                         else
2725                                 address_to_bind = "localhost";
2726                 } else if (*listen_host == '\0' ||
2727                            strcmp(listen_host, "*") == 0) {
2728                         if (datafellows & SSH_BUG_RFWD_ADDR)
2729                                 address_to_bind = "0.0.0.0";
2730                         else
2731                                 address_to_bind = "";
2732                 } else
2733                         address_to_bind = listen_host;
2734
2735                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2736                 packet_put_cstring("tcpip-forward");
2737                 packet_put_char(1);                     /* boolean: want reply */
2738                 packet_put_cstring(address_to_bind);
2739                 packet_put_int(listen_port);
2740                 packet_send();
2741                 packet_write_wait();
2742                 /* Assume that server accepts the request */
2743                 success = 1;
2744         } else {
2745                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2746                 packet_put_int(listen_port);
2747                 packet_put_cstring(host_to_connect);
2748                 packet_put_int(port_to_connect);
2749                 packet_send();
2750                 packet_write_wait();
2751
2752                 /* Wait for response from the remote side. */
2753                 type = packet_read();
2754                 switch (type) {
2755                 case SSH_SMSG_SUCCESS:
2756                         success = 1;
2757                         break;
2758                 case SSH_SMSG_FAILURE:
2759                         break;
2760                 default:
2761                         /* Unknown packet */
2762                         packet_disconnect("Protocol error for port forward request:"
2763                             "received packet type %d.", type);
2764                 }
2765         }
2766         if (success) {
2767                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2768                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2769                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2770                 num_permitted_opens++;
2771         }
2772         return (success ? 0 : -1);
2773 }
2774
2775 /*
2776  * Request cancellation of remote forwarding of connection host:port from
2777  * local side.
2778  */
2779 void
2780 channel_request_rforward_cancel(const char *host, u_short port)
2781 {
2782         int i;
2783
2784         if (!compat20)
2785                 return;
2786
2787         for (i = 0; i < num_permitted_opens; i++) {
2788                 if (permitted_opens[i].host_to_connect != NULL &&
2789                     permitted_opens[i].listen_port == port)
2790                         break;
2791         }
2792         if (i >= num_permitted_opens) {
2793                 debug("%s: requested forward not found", __func__);
2794                 return;
2795         }
2796         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2797         packet_put_cstring("cancel-tcpip-forward");
2798         packet_put_char(0);
2799         packet_put_cstring(host == NULL ? "" : host);
2800         packet_put_int(port);
2801         packet_send();
2802
2803         permitted_opens[i].listen_port = 0;
2804         permitted_opens[i].port_to_connect = 0;
2805         xfree(permitted_opens[i].host_to_connect);
2806         permitted_opens[i].host_to_connect = NULL;
2807 }
2808
2809 /*
2810  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2811  * listening for the port, and sends back a success reply (or disconnect
2812  * message if there was an error).
2813  */
2814 int
2815 channel_input_port_forward_request(int is_root, int gateway_ports)
2816 {
2817         u_short port, host_port;
2818         int success = 0;
2819         char *hostname;
2820
2821         /* Get arguments from the packet. */
2822         port = packet_get_int();
2823         hostname = packet_get_string(NULL);
2824         host_port = packet_get_int();
2825
2826 #ifndef HAVE_CYGWIN
2827         /*
2828          * Check that an unprivileged user is not trying to forward a
2829          * privileged port.
2830          */
2831         if (port < IPPORT_RESERVED && !is_root)
2832                 packet_disconnect(
2833                     "Requested forwarding of port %d but user is not root.",
2834                     port);
2835         if (host_port == 0)
2836                 packet_disconnect("Dynamic forwarding denied.");
2837 #endif
2838
2839         /* Initiate forwarding */
2840         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2841             host_port, gateway_ports);
2842
2843         /* Free the argument string. */
2844         xfree(hostname);
2845
2846         return (success ? 0 : -1);
2847 }
2848
2849 /*
2850  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2851  * usually called by the server, because the user could connect to any port
2852  * anyway, and the server has no way to know but to trust the client anyway.
2853  */
2854 void
2855 channel_permit_all_opens(void)
2856 {
2857         if (num_permitted_opens == 0)
2858                 all_opens_permitted = 1;
2859 }
2860
2861 void
2862 channel_add_permitted_opens(char *host, int port)
2863 {
2864         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2865                 fatal("channel_add_permitted_opens: too many forwards");
2866         debug("allow port forwarding to host %s port %d", host, port);
2867
2868         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2869         permitted_opens[num_permitted_opens].port_to_connect = port;
2870         num_permitted_opens++;
2871
2872         all_opens_permitted = 0;
2873 }
2874
2875 int
2876 channel_add_adm_permitted_opens(char *host, int port)
2877 {
2878         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2879                 fatal("channel_add_adm_permitted_opens: too many forwards");
2880         debug("config allows port forwarding to host %s port %d", host, port);
2881
2882         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2883              = xstrdup(host);
2884         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2885         return ++num_adm_permitted_opens;
2886 }
2887
2888 void
2889 channel_clear_permitted_opens(void)
2890 {
2891         int i;
2892
2893         for (i = 0; i < num_permitted_opens; i++)
2894                 if (permitted_opens[i].host_to_connect != NULL)
2895                         xfree(permitted_opens[i].host_to_connect);
2896         num_permitted_opens = 0;
2897 }
2898
2899 void
2900 channel_clear_adm_permitted_opens(void)
2901 {
2902         int i;
2903
2904         for (i = 0; i < num_adm_permitted_opens; i++)
2905                 if (permitted_adm_opens[i].host_to_connect != NULL)
2906                         xfree(permitted_adm_opens[i].host_to_connect);
2907         num_adm_permitted_opens = 0;
2908 }
2909
2910 void
2911 channel_print_adm_permitted_opens(void)
2912 {
2913         int i;
2914
2915         printf("permitopen");
2916         if (num_adm_permitted_opens == 0) {
2917                 printf(" any\n");
2918                 return;
2919         }
2920         for (i = 0; i < num_adm_permitted_opens; i++)
2921                 if (permitted_adm_opens[i].host_to_connect != NULL)
2922                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
2923                             permitted_adm_opens[i].port_to_connect);
2924         printf("\n");
2925 }
2926
2927 /* Try to start non-blocking connect to next host in cctx list */
2928 static int
2929 connect_next(struct channel_connect *cctx)
2930 {
2931         int sock, saved_errno;
2932         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2933
2934         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
2935                 if (cctx->ai->ai_family != AF_INET &&
2936                     cctx->ai->ai_family != AF_INET6)
2937                         continue;
2938                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
2939                     ntop, sizeof(ntop), strport, sizeof(strport),
2940                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2941                         error("connect_next: getnameinfo failed");
2942                         continue;
2943                 }
2944                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
2945                     cctx->ai->ai_protocol)) == -1) {
2946                         if (cctx->ai->ai_next == NULL)
2947                                 error("socket: %.100s", strerror(errno));
2948                         else
2949                                 verbose("socket: %.100s", strerror(errno));
2950                         continue;
2951                 }
2952                 if (set_nonblock(sock) == -1)
2953                         fatal("%s: set_nonblock(%d)", __func__, sock);
2954                 if (connect(sock, cctx->ai->ai_addr,
2955                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
2956                         debug("connect_next: host %.100s ([%.100s]:%s): "
2957                             "%.100s", cctx->host, ntop, strport,
2958                             strerror(errno));
2959                         saved_errno = errno;
2960                         close(sock);
2961                         errno = saved_errno;
2962                         continue;       /* fail -- try next */
2963                 }
2964                 debug("connect_next: host %.100s ([%.100s]:%s) "
2965                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
2966                 cctx->ai = cctx->ai->ai_next;
2967                 set_nodelay(sock);
2968                 return sock;
2969         }
2970         return -1;
2971 }
2972
2973 static void
2974 channel_connect_ctx_free(struct channel_connect *cctx)
2975 {
2976         xfree(cctx->host);
2977         if (cctx->aitop)
2978                 freeaddrinfo(cctx->aitop);
2979         bzero(cctx, sizeof(*cctx));
2980         cctx->host = NULL;
2981         cctx->ai = cctx->aitop = NULL;
2982 }
2983
2984 /* Return CONNECTING channel to remote host, port */
2985 static Channel *
2986 connect_to(const char *host, u_short port, char *ctype, char *rname)
2987 {
2988         struct addrinfo hints;
2989         int gaierr;
2990         int sock = -1;
2991         char strport[NI_MAXSERV];
2992         struct channel_connect cctx;
2993         Channel *c;
2994
2995         memset(&cctx, 0, sizeof(cctx));
2996         memset(&hints, 0, sizeof(hints));
2997         hints.ai_family = IPv4or6;
2998         hints.ai_socktype = SOCK_STREAM;
2999         snprintf(strport, sizeof strport, "%d", port);
3000         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
3001                 error("connect_to %.100s: unknown host (%s)", host,
3002                     ssh_gai_strerror(gaierr));
3003                 return NULL;
3004         }
3005
3006         cctx.host = xstrdup(host);
3007         cctx.port = port;
3008         cctx.ai = cctx.aitop;
3009
3010         if ((sock = connect_next(&cctx)) == -1) {
3011                 error("connect to %.100s port %d failed: %s",
3012                     host, port, strerror(errno));
3013                 channel_connect_ctx_free(&cctx);
3014                 return NULL;
3015         }
3016         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3017             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3018         c->connect_ctx = cctx;
3019         return c;
3020 }
3021
3022 Channel *
3023 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3024 {
3025         int i;
3026
3027         for (i = 0; i < num_permitted_opens; i++) {
3028                 if (permitted_opens[i].host_to_connect != NULL &&
3029                     permitted_opens[i].listen_port == listen_port) {
3030                         return connect_to(
3031                             permitted_opens[i].host_to_connect,
3032                             permitted_opens[i].port_to_connect, ctype, rname);
3033                 }
3034         }
3035         error("WARNING: Server requests forwarding for unknown listen_port %d",
3036             listen_port);
3037         return NULL;
3038 }
3039
3040 /* Check if connecting to that port is permitted and connect. */
3041 Channel *
3042 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3043 {
3044         int i, permit, permit_adm = 1;
3045
3046         permit = all_opens_permitted;
3047         if (!permit) {
3048                 for (i = 0; i < num_permitted_opens; i++)
3049                         if (permitted_opens[i].host_to_connect != NULL &&
3050                             permitted_opens[i].port_to_connect == port &&
3051                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3052                                 permit = 1;
3053         }
3054
3055         if (num_adm_permitted_opens > 0) {
3056                 permit_adm = 0;
3057                 for (i = 0; i < num_adm_permitted_opens; i++)
3058                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3059                             permitted_adm_opens[i].port_to_connect == port &&
3060                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3061                             == 0)
3062                                 permit_adm = 1;
3063         }
3064
3065         if (!permit || !permit_adm) {
3066                 logit("Received request to connect to host %.100s port %d, "
3067                     "but the request was denied.", host, port);
3068                 return NULL;
3069         }
3070         return connect_to(host, port, ctype, rname);
3071 }
3072
3073 void
3074 channel_send_window_changes(void)
3075 {
3076         u_int i;
3077         struct winsize ws;
3078
3079         for (i = 0; i < channels_alloc; i++) {
3080                 if (channels[i] == NULL || !channels[i]->client_tty ||
3081                     channels[i]->type != SSH_CHANNEL_OPEN)
3082                         continue;
3083                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3084                         continue;
3085                 channel_request_start(i, "window-change", 0);
3086                 packet_put_int((u_int)ws.ws_col);
3087                 packet_put_int((u_int)ws.ws_row);
3088                 packet_put_int((u_int)ws.ws_xpixel);
3089                 packet_put_int((u_int)ws.ws_ypixel);
3090                 packet_send();
3091         }
3092 }
3093
3094 /* -- X11 forwarding */
3095
3096 /*
3097  * Creates an internet domain socket for listening for X11 connections.
3098  * Returns 0 and a suitable display number for the DISPLAY variable
3099  * stored in display_numberp , or -1 if an error occurs.
3100  */
3101 int
3102 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3103     int single_connection, u_int *display_numberp, int **chanids)
3104 {
3105         Channel *nc = NULL;
3106         int display_number, sock;
3107         u_short port;
3108         struct addrinfo hints, *ai, *aitop;
3109         char strport[NI_MAXSERV];
3110         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3111
3112         if (chanids == NULL)
3113                 return -1;
3114
3115         for (display_number = x11_display_offset;
3116             display_number < MAX_DISPLAYS;
3117             display_number++) {
3118                 port = 6000 + display_number;
3119                 memset(&hints, 0, sizeof(hints));
3120                 hints.ai_family = IPv4or6;
3121                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3122                 hints.ai_socktype = SOCK_STREAM;
3123                 snprintf(strport, sizeof strport, "%d", port);
3124                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3125                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3126                         return -1;
3127                 }
3128                 for (ai = aitop; ai; ai = ai->ai_next) {
3129                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3130                                 continue;
3131                         sock = socket(ai->ai_family, ai->ai_socktype,
3132                             ai->ai_protocol);
3133                         if (sock < 0) {
3134                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3135                                         error("socket: %.100s", strerror(errno));
3136                                         freeaddrinfo(aitop);
3137                                         return -1;
3138                                 } else {
3139                                         debug("x11_create_display_inet: Socket family %d not supported",
3140                                                  ai->ai_family);
3141                                         continue;
3142                                 }
3143                         }
3144                         if (ai->ai_family == AF_INET6)
3145                                 sock_set_v6only(sock);
3146                         if (x11_use_localhost)
3147                                 channel_set_reuseaddr(sock);
3148                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3149                                 debug2("bind port %d: %.100s", port, strerror(errno));
3150                                 close(sock);
3151
3152                                 for (n = 0; n < num_socks; n++) {
3153                                         close(socks[n]);
3154                                 }
3155                                 num_socks = 0;
3156                                 break;
3157                         }
3158                         socks[num_socks++] = sock;
3159                         if (num_socks == NUM_SOCKS)
3160                                 break;
3161                 }
3162                 freeaddrinfo(aitop);
3163                 if (num_socks > 0)
3164                         break;
3165         }
3166         if (display_number >= MAX_DISPLAYS) {
3167                 error("Failed to allocate internet-domain X11 display socket.");
3168                 return -1;
3169         }
3170         /* Start listening for connections on the socket. */
3171         for (n = 0; n < num_socks; n++) {
3172                 sock = socks[n];
3173                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3174                         error("listen: %.100s", strerror(errno));
3175                         close(sock);
3176                         return -1;
3177                 }
3178         }
3179
3180         /* Allocate a channel for each socket. */
3181         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3182         for (n = 0; n < num_socks; n++) {
3183                 sock = socks[n];
3184                 nc = channel_new("x11 listener",
3185                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3186                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3187                     0, "X11 inet listener", 1);
3188                 nc->single_connection = single_connection;
3189                 (*chanids)[n] = nc->self;
3190         }
3191         (*chanids)[n] = -1;
3192
3193         /* Return the display number for the DISPLAY environment variable. */
3194         *display_numberp = display_number;
3195         return (0);
3196 }
3197
3198 static int
3199 connect_local_xsocket_path(const char *pathname)
3200 {
3201         int sock;
3202         struct sockaddr_un addr;
3203
3204         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3205         if (sock < 0)
3206                 error("socket: %.100s", strerror(errno));
3207         memset(&addr, 0, sizeof(addr));
3208         addr.sun_family = AF_UNIX;
3209         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3210         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3211                 return sock;
3212         close(sock);
3213         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3214         return -1;
3215 }
3216
3217 static int
3218 connect_local_xsocket(u_int dnr)
3219 {
3220         char buf[1024];
3221         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3222         return connect_local_xsocket_path(buf);
3223 }
3224
3225 int
3226 x11_connect_display(void)
3227 {
3228         u_int display_number;
3229         const char *display;
3230         char buf[1024], *cp;
3231         struct addrinfo hints, *ai, *aitop;
3232         char strport[NI_MAXSERV];
3233         int gaierr, sock = 0;
3234
3235         /* Try to open a socket for the local X server. */
3236         display = getenv("DISPLAY");
3237         if (!display) {
3238                 error("DISPLAY not set.");
3239                 return -1;
3240         }
3241         /*
3242          * Now we decode the value of the DISPLAY variable and make a
3243          * connection to the real X server.
3244          */
3245
3246         /* Check if the display is from launchd. */
3247 #ifdef __APPLE__
3248         if (strncmp(display, "/tmp/launch", 11) == 0) {
3249                 sock = connect_local_xsocket_path(display);
3250                 if (sock < 0)
3251                         return -1;
3252
3253                 /* OK, we now have a connection to the display. */
3254                 return sock;
3255         }
3256 #endif
3257         /*
3258          * Check if it is a unix domain socket.  Unix domain displays are in
3259          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3260          */
3261         if (strncmp(display, "unix:", 5) == 0 ||
3262             display[0] == ':') {
3263                 /* Connect to the unix domain socket. */
3264                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3265                         error("Could not parse display number from DISPLAY: %.100s",
3266                             display);
3267                         return -1;
3268                 }
3269                 /* Create a socket. */
3270                 sock = connect_local_xsocket(display_number);
3271                 if (sock < 0)
3272                         return -1;
3273
3274                 /* OK, we now have a connection to the display. */
3275                 return sock;
3276         }
3277         /*
3278          * Connect to an inet socket.  The DISPLAY value is supposedly
3279          * hostname:d[.s], where hostname may also be numeric IP address.
3280          */
3281         strlcpy(buf, display, sizeof(buf));
3282         cp = strchr(buf, ':');
3283         if (!cp) {
3284                 error("Could not find ':' in DISPLAY: %.100s", display);
3285                 return -1;
3286         }
3287         *cp = 0;
3288         /* buf now contains the host name.  But first we parse the display number. */
3289         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3290                 error("Could not parse display number from DISPLAY: %.100s",
3291                     display);
3292                 return -1;
3293         }
3294
3295         /* Look up the host address */
3296         memset(&hints, 0, sizeof(hints));
3297         hints.ai_family = IPv4or6;
3298         hints.ai_socktype = SOCK_STREAM;
3299         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3300         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3301                 error("%.100s: unknown host. (%s)", buf,
3302                 ssh_gai_strerror(gaierr));
3303                 return -1;
3304         }
3305         for (ai = aitop; ai; ai = ai->ai_next) {
3306                 /* Create a socket. */
3307                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3308                 if (sock < 0) {
3309                         debug2("socket: %.100s", strerror(errno));
3310                         continue;
3311                 }
3312                 /* Connect it to the display. */
3313                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3314                         debug2("connect %.100s port %u: %.100s", buf,
3315                             6000 + display_number, strerror(errno));
3316                         close(sock);
3317                         continue;
3318                 }
3319                 /* Success */
3320                 break;
3321         }
3322         freeaddrinfo(aitop);
3323         if (!ai) {
3324                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3325                     strerror(errno));
3326                 return -1;
3327         }
3328         set_nodelay(sock);
3329         return sock;
3330 }
3331
3332 /*
3333  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3334  * the remote channel number.  We should do whatever we want, and respond
3335  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3336  */
3337
3338 /* ARGSUSED */
3339 void
3340 x11_input_open(int type, u_int32_t seq, void *ctxt)
3341 {
3342         Channel *c = NULL;
3343         int remote_id, sock = 0;
3344         char *remote_host;
3345
3346         debug("Received X11 open request.");
3347
3348         remote_id = packet_get_int();
3349
3350         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3351                 remote_host = packet_get_string(NULL);
3352         } else {
3353                 remote_host = xstrdup("unknown (remote did not supply name)");
3354         }
3355         packet_check_eom();
3356
3357         /* Obtain a connection to the real X display. */
3358         sock = x11_connect_display();
3359         if (sock != -1) {
3360                 /* Allocate a channel for this connection. */
3361                 c = channel_new("connected x11 socket",
3362                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3363                     remote_host, 1);
3364                 c->remote_id = remote_id;
3365                 c->force_drain = 1;
3366         }
3367         xfree(remote_host);
3368         if (c == NULL) {
3369                 /* Send refusal to the remote host. */
3370                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3371                 packet_put_int(remote_id);
3372         } else {
3373                 /* Send a confirmation to the remote host. */
3374                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3375                 packet_put_int(remote_id);
3376                 packet_put_int(c->self);
3377         }
3378         packet_send();
3379 }
3380
3381 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3382 /* ARGSUSED */
3383 void
3384 deny_input_open(int type, u_int32_t seq, void *ctxt)
3385 {
3386         int rchan = packet_get_int();
3387
3388         switch (type) {
3389         case SSH_SMSG_AGENT_OPEN:
3390                 error("Warning: ssh server tried agent forwarding.");
3391                 break;
3392         case SSH_SMSG_X11_OPEN:
3393                 error("Warning: ssh server tried X11 forwarding.");
3394                 break;
3395         default:
3396                 error("deny_input_open: type %d", type);
3397                 break;
3398         }
3399         error("Warning: this is probably a break-in attempt by a malicious server.");
3400         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3401         packet_put_int(rchan);
3402         packet_send();
3403 }
3404
3405 /*
3406  * Requests forwarding of X11 connections, generates fake authentication
3407  * data, and enables authentication spoofing.
3408  * This should be called in the client only.
3409  */
3410 void
3411 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3412     const char *proto, const char *data)
3413 {
3414         u_int data_len = (u_int) strlen(data) / 2;
3415         u_int i, value;
3416         char *new_data;
3417         int screen_number;
3418         const char *cp;
3419         u_int32_t rnd = 0;
3420
3421         if (x11_saved_display == NULL)
3422                 x11_saved_display = xstrdup(disp);
3423         else if (strcmp(disp, x11_saved_display) != 0) {
3424                 error("x11_request_forwarding_with_spoofing: different "
3425                     "$DISPLAY already forwarded");
3426                 return;
3427         }
3428
3429         cp = strchr(disp, ':');
3430         if (cp)
3431                 cp = strchr(cp, '.');
3432         if (cp)
3433                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3434         else
3435                 screen_number = 0;
3436
3437         if (x11_saved_proto == NULL) {
3438                 /* Save protocol name. */
3439                 x11_saved_proto = xstrdup(proto);
3440                 /*
3441                  * Extract real authentication data and generate fake data
3442                  * of the same length.
3443                  */
3444                 x11_saved_data = xmalloc(data_len);
3445                 x11_fake_data = xmalloc(data_len);
3446                 for (i = 0; i < data_len; i++) {
3447                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3448                                 fatal("x11_request_forwarding: bad "
3449                                     "authentication data: %.100s", data);
3450                         if (i % 4 == 0)
3451                                 rnd = arc4random();
3452                         x11_saved_data[i] = value;
3453                         x11_fake_data[i] = rnd & 0xff;
3454                         rnd >>= 8;
3455                 }
3456                 x11_saved_data_len = data_len;
3457                 x11_fake_data_len = data_len;
3458         }
3459
3460         /* Convert the fake data into hex. */
3461         new_data = tohex(x11_fake_data, data_len);
3462
3463         /* Send the request packet. */
3464         if (compat20) {
3465                 channel_request_start(client_session_id, "x11-req", 0);
3466                 packet_put_char(0);     /* XXX bool single connection */
3467         } else {
3468                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3469         }
3470         packet_put_cstring(proto);
3471         packet_put_cstring(new_data);
3472         packet_put_int(screen_number);
3473         packet_send();
3474         packet_write_wait();
3475         xfree(new_data);
3476 }
3477
3478
3479 /* -- agent forwarding */
3480
3481 /* Sends a message to the server to request authentication fd forwarding. */
3482
3483 void
3484 auth_request_forwarding(void)
3485 {
3486         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3487         packet_send();
3488         packet_write_wait();
3489 }