openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.270 2007/06/25 08:20:03 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 <netdb.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <termios.h>
  61 #include <unistd.h>
  62 #include <stdarg.h>
  63
  64 #include "xmalloc.h"
  65 #include "ssh.h"
  66 #include "ssh1.h"
  67 #include "ssh2.h"
  68 #include "packet.h"
  69 #include "log.h"
  70 #include "misc.h"
  71 #include "buffer.h"
  72 #include "channels.h"
  73 #include "compat.h"
  74 #include "canohost.h"
  75 #include "key.h"
  76 #include "authfd.h"
  77 #include "pathnames.h"
  78
  79
  80 /* -- channel core */
  81
  82 /*
  83  * Pointer to an array containing all allocated channels.  The array is
  84  * dynamically extended as needed.
  85  */
  86 static Channel **channels = NULL;
  87
  88 /*
  89  * Size of the channel array.  All slots of the array must always be
  90  * initialized (at least the type field); unused slots set to NULL
  91  */
  92 static u_int channels_alloc = 0;
  93
  94 /*
  95  * Maximum file descriptor value used in any of the channels.  This is
  96  * updated in channel_new.
  97  */
  98 static int channel_max_fd = 0;
  99
 100
 101 /* -- tcp forwarding */
 102
 103 /*
 104  * Data structure for storing which hosts are permitted for forward requests.
 105  * The local sides of any remote forwards are stored in this array to prevent
 106  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 107  * network (which might be behind a firewall).
 108  */
 109 typedef struct {
 110         char *host_to_connect;          /* Connect to 'host'. */
 111         u_short port_to_connect;        /* Connect to 'port'. */
 112         u_short listen_port;            /* Remote side should listen port number. */
 113 } ForwardPermission;
 114
 115 /* List of all permitted host/port pairs to connect by the user. */
 116 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 117
 118 /* List of all permitted host/port pairs to connect by the admin. */
 119 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 120
 121 /* Number of permitted host/port pairs in the array permitted by the user. */
 122 static int num_permitted_opens = 0;
 123
 124 /* Number of permitted host/port pair in the array permitted by the admin. */
 125 static int num_adm_permitted_opens = 0;
 126
 127 /*
 128  * If this is true, all opens are permitted.  This is the case on the server
 129  * on which we have to trust the client anyway, and the user could do
 130  * anything after logging in anyway.
 131  */
 132 static int all_opens_permitted = 0;
 133
 134
 135 /* -- X11 forwarding */
 136
 137 /* Maximum number of fake X11 displays to try. */
 138 #define MAX_DISPLAYS  1000
 139
 140 /* Saved X11 local (client) display. */
 141 static char *x11_saved_display = NULL;
 142
 143 /* Saved X11 authentication protocol name. */
 144 static char *x11_saved_proto = NULL;
 145
 146 /* Saved X11 authentication data.  This is the real data. */
 147 static char *x11_saved_data = NULL;
 148 static u_int x11_saved_data_len = 0;
 149
 150 /*
 151  * Fake X11 authentication data.  This is what the server will be sending us;
 152  * we should replace any occurrences of this by the real data.
 153  */
 154 static u_char *x11_fake_data = NULL;
 155 static u_int x11_fake_data_len;
 156
 157
 158 /* -- agent forwarding */
 159
 160 #define NUM_SOCKS       10
 161
 162 /* AF_UNSPEC or AF_INET or AF_INET6 */
 163 static int IPv4or6 = AF_UNSPEC;
 164
 165 /* helper */
 166 static void port_open_helper(Channel *c, char *rtype);
 167
 168 /* -- channel core */
 169
 170 Channel *
 171 channel_by_id(int id)
 172 {
 173         Channel *c;
 174
 175         if (id < 0 || (u_int)id >= channels_alloc) {
 176                 logit("channel_by_id: %d: bad id", id);
 177                 return NULL;
 178         }
 179         c = channels[id];
 180         if (c == NULL) {
 181                 logit("channel_by_id: %d: bad id: channel free", id);
 182                 return NULL;
 183         }
 184         return c;
 185 }
 186
 187 /*
 188  * Returns the channel if it is allowed to receive protocol messages.
 189  * Private channels, like listening sockets, may not receive messages.
 190  */
 191 Channel *
 192 channel_lookup(int id)
 193 {
 194         Channel *c;
 195
 196         if ((c = channel_by_id(id)) == NULL)
 197                 return (NULL);
 198
 199         switch (c->type) {
 200         case SSH_CHANNEL_X11_OPEN:
 201         case SSH_CHANNEL_LARVAL:
 202         case SSH_CHANNEL_CONNECTING:
 203         case SSH_CHANNEL_DYNAMIC:
 204         case SSH_CHANNEL_OPENING:
 205         case SSH_CHANNEL_OPEN:
 206         case SSH_CHANNEL_INPUT_DRAINING:
 207         case SSH_CHANNEL_OUTPUT_DRAINING:
 208                 return (c);
 209         }
 210         logit("Non-public channel %d, type %d.", id, c->type);
 211         return (NULL);
 212 }
 213
 214 /*
 215  * Register filedescriptors for a channel, used when allocating a channel or
 216  * when the channel consumer/producer is ready, e.g. shell exec'd
 217  */
 218 static void
 219 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 220     int extusage, int nonblock)
 221 {
 222         /* Update the maximum file descriptor value. */
 223         channel_max_fd = MAX(channel_max_fd, rfd);
 224         channel_max_fd = MAX(channel_max_fd, wfd);
 225         channel_max_fd = MAX(channel_max_fd, efd);
 226
 227         /* XXX set close-on-exec -markus */
 228
 229         c->rfd = rfd;
 230         c->wfd = wfd;
 231         c->sock = (rfd == wfd) ? rfd : -1;
 232         c->ctl_fd = -1; /* XXX: set elsewhere */
 233         c->efd = efd;
 234         c->extended_usage = extusage;
 235
 236         /* XXX ugly hack: nonblock is only set by the server */
 237         if (nonblock && isatty(c->rfd)) {
 238                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 239                 c->isatty = 1;
 240                 if (!isatty(c->wfd)) {
 241                         error("channel %d: wfd %d is not a tty?",
 242                             c->self, c->wfd);
 243                 }
 244         } else {
 245                 c->isatty = 0;
 246         }
 247         c->wfd_isatty = isatty(c->wfd);
 248
 249         /* enable nonblocking mode */
 250         if (nonblock) {
 251                 if (rfd != -1)
 252                         set_nonblock(rfd);
 253                 if (wfd != -1)
 254                         set_nonblock(wfd);
 255                 if (efd != -1)
 256                         set_nonblock(efd);
 257         }
 258 }
 259
 260 /*
 261  * Allocate a new channel object and set its type and socket. This will cause
 262  * remote_name to be freed.
 263  */
 264 Channel *
 265 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 266     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 267 {
 268         int found;
 269         u_int i;
 270         Channel *c;
 271
 272         /* Do initial allocation if this is the first call. */
 273         if (channels_alloc == 0) {
 274                 channels_alloc = 10;
 275                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 276                 for (i = 0; i < channels_alloc; i++)
 277                         channels[i] = NULL;
 278         }
 279         /* Try to find a free slot where to put the new channel. */
 280         for (found = -1, i = 0; i < channels_alloc; i++)
 281                 if (channels[i] == NULL) {
 282                         /* Found a free slot. */
 283                         found = (int)i;
 284                         break;
 285                 }
 286         if (found < 0) {
 287                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 288                 found = channels_alloc;
 289                 if (channels_alloc > 10000)
 290                         fatal("channel_new: internal error: channels_alloc %d "
 291                             "too big.", channels_alloc);
 292                 channels = xrealloc(channels, channels_alloc + 10,
 293                     sizeof(Channel *));
 294                 channels_alloc += 10;
 295                 debug2("channel: expanding %d", channels_alloc);
 296                 for (i = found; i < channels_alloc; i++)
 297                         channels[i] = NULL;
 298         }
 299         /* Initialize and return new channel. */
 300         c = channels[found] = xcalloc(1, sizeof(Channel));
 301         buffer_init(&c->input);
 302         buffer_init(&c->output);
 303         buffer_init(&c->extended);
 304         c->ostate = CHAN_OUTPUT_OPEN;
 305         c->istate = CHAN_INPUT_OPEN;
 306         c->flags = 0;
 307         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 308         c->self = found;
 309         c->type = type;
 310         c->ctype = ctype;
 311         c->local_window = window;
 312         c->local_window_max = window;
 313         c->local_consumed = 0;
 314         c->local_maxpacket = maxpack;
 315         c->dynamic_window = 0;
 316         c->remote_id = -1;
 317         c->remote_name = xstrdup(remote_name);
 318         c->remote_window = 0;
 319         c->remote_maxpacket = 0;
 320         c->force_drain = 0;
 321         c->single_connection = 0;
 322         c->detach_user = NULL;
 323         c->detach_close = 0;
 324         c->confirm = NULL;
 325         c->confirm_ctx = NULL;
 326         c->input_filter = NULL;
 327         c->output_filter = NULL;
 328         debug("channel %d: new [%s]", found, remote_name);
 329         return c;
 330 }
 331
 332 static int
 333 channel_find_maxfd(void)
 334 {
 335         u_int i;
 336         int max = 0;
 337         Channel *c;
 338
 339         for (i = 0; i < channels_alloc; i++) {
 340                 c = channels[i];
 341                 if (c != NULL) {
 342                         max = MAX(max, c->rfd);
 343                         max = MAX(max, c->wfd);
 344                         max = MAX(max, c->efd);
 345                 }
 346         }
 347         return max;
 348 }
 349
 350 int
 351 channel_close_fd(int *fdp)
 352 {
 353         int ret = 0, fd = *fdp;
 354
 355         if (fd != -1) {
 356                 ret = close(fd);
 357                 *fdp = -1;
 358                 if (fd == channel_max_fd)
 359                         channel_max_fd = channel_find_maxfd();
 360         }
 361         return ret;
 362 }
 363
 364 /* Close all channel fd/socket. */
 365 static void
 366 channel_close_fds(Channel *c)
 367 {
 368         debug3("channel %d: close_fds r %d w %d e %d c %d",
 369             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 370
 371         channel_close_fd(&c->sock);
 372         channel_close_fd(&c->ctl_fd);
 373         channel_close_fd(&c->rfd);
 374         channel_close_fd(&c->wfd);
 375         channel_close_fd(&c->efd);
 376 }
 377
 378 /* Free the channel and close its fd/socket. */
 379 void
 380 channel_free(Channel *c)
 381 {
 382         char *s;
 383         u_int i, n;
 384
 385         for (n = 0, i = 0; i < channels_alloc; i++)
 386                 if (channels[i])
 387                         n++;
 388         debug("channel %d: free: %s, nchannels %u", c->self,
 389             c->remote_name ? c->remote_name : "???", n);
 390
 391         s = channel_open_message();
 392         debug3("channel %d: status: %s", c->self, s);
 393         xfree(s);
 394
 395         if (c->sock != -1)
 396                 shutdown(c->sock, SHUT_RDWR);
 397         if (c->ctl_fd != -1)
 398                 shutdown(c->ctl_fd, SHUT_RDWR);
 399         channel_close_fds(c);
 400         buffer_free(&c->input);
 401         buffer_free(&c->output);
 402         buffer_free(&c->extended);
 403         if (c->remote_name) {
 404                 xfree(c->remote_name);
 405                 c->remote_name = NULL;
 406         }
 407         channels[c->self] = NULL;
 408         xfree(c);
 409 }
 410
 411 void
 412 channel_free_all(void)
 413 {
 414         u_int i;
 415
 416         for (i = 0; i < channels_alloc; i++)
 417                 if (channels[i] != NULL)
 418                         channel_free(channels[i]);
 419 }
 420
 421 /*
 422  * Closes the sockets/fds of all channels.  This is used to close extra file
 423  * descriptors after a fork.
 424  */
 425 void
 426 channel_close_all(void)
 427 {
 428         u_int i;
 429
 430         for (i = 0; i < channels_alloc; i++)
 431                 if (channels[i] != NULL)
 432                         channel_close_fds(channels[i]);
 433 }
 434
 435 /*
 436  * Stop listening to channels.
 437  */
 438 void
 439 channel_stop_listening(void)
 440 {
 441         u_int i;
 442         Channel *c;
 443
 444         for (i = 0; i < channels_alloc; i++) {
 445                 c = channels[i];
 446                 if (c != NULL) {
 447                         switch (c->type) {
 448                         case SSH_CHANNEL_AUTH_SOCKET:
 449                         case SSH_CHANNEL_PORT_LISTENER:
 450                         case SSH_CHANNEL_RPORT_LISTENER:
 451                         case SSH_CHANNEL_X11_LISTENER:
 452                                 channel_close_fd(&c->sock);
 453                                 channel_free(c);
 454                                 break;
 455                         }
 456                 }
 457         }
 458 }
 459
 460 /*
 461  * Returns true if no channel has too much buffered data, and false if one or
 462  * more channel is overfull.
 463  */
 464 int
 465 channel_not_very_much_buffered_data(void)
 466 {
 467         u_int i;
 468         Channel *c;
 469
 470         for (i = 0; i < channels_alloc; i++) {
 471                 c = channels[i];
 472                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 473 #if 0
 474                         if (!compat20 &&
 475                             buffer_len(&c->input) > packet_get_maxsize()) {
 476                                 debug2("channel %d: big input buffer %d",
 477                                     c->self, buffer_len(&c->input));
 478                                 return 0;
 479                         }
 480 #endif
 481                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 482                                 debug2("channel %d: big output buffer %u > %u",
 483                                     c->self, buffer_len(&c->output),
 484                                     packet_get_maxsize());
 485                                 return 0;
 486                         }
 487                 }
 488         }
 489         return 1;
 490 }
 491
 492 /* Returns true if any channel is still open. */
 493 int
 494 channel_still_open(void)
 495 {
 496         u_int i;
 497         Channel *c;
 498
 499         for (i = 0; i < channels_alloc; i++) {
 500                 c = channels[i];
 501                 if (c == NULL)
 502                         continue;
 503                 switch (c->type) {
 504                 case SSH_CHANNEL_X11_LISTENER:
 505                 case SSH_CHANNEL_PORT_LISTENER:
 506                 case SSH_CHANNEL_RPORT_LISTENER:
 507                 case SSH_CHANNEL_CLOSED:
 508                 case SSH_CHANNEL_AUTH_SOCKET:
 509                 case SSH_CHANNEL_DYNAMIC:
 510                 case SSH_CHANNEL_CONNECTING:
 511                 case SSH_CHANNEL_ZOMBIE:
 512                         continue;
 513                 case SSH_CHANNEL_LARVAL:
 514                         if (!compat20)
 515                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 516                         continue;
 517                 case SSH_CHANNEL_OPENING:
 518                 case SSH_CHANNEL_OPEN:
 519                 case SSH_CHANNEL_X11_OPEN:
 520                         return 1;
 521                 case SSH_CHANNEL_INPUT_DRAINING:
 522                 case SSH_CHANNEL_OUTPUT_DRAINING:
 523                         if (!compat13)
 524                                 fatal("cannot happen: OUT_DRAIN");
 525                         return 1;
 526                 default:
 527                         fatal("channel_still_open: bad channel type %d", c->type);
 528                         /* NOTREACHED */
 529                 }
 530         }
 531         return 0;
 532 }
 533
 534 /* Returns the id of an open channel suitable for keepaliving */
 535 int
 536 channel_find_open(void)
 537 {
 538         u_int i;
 539         Channel *c;
 540
 541         for (i = 0; i < channels_alloc; i++) {
 542                 c = channels[i];
 543                 if (c == NULL || c->remote_id < 0)
 544                         continue;
 545                 switch (c->type) {
 546                 case SSH_CHANNEL_CLOSED:
 547                 case SSH_CHANNEL_DYNAMIC:
 548                 case SSH_CHANNEL_X11_LISTENER:
 549                 case SSH_CHANNEL_PORT_LISTENER:
 550                 case SSH_CHANNEL_RPORT_LISTENER:
 551                 case SSH_CHANNEL_OPENING:
 552                 case SSH_CHANNEL_CONNECTING:
 553                 case SSH_CHANNEL_ZOMBIE:
 554                         continue;
 555                 case SSH_CHANNEL_LARVAL:
 556                 case SSH_CHANNEL_AUTH_SOCKET:
 557                 case SSH_CHANNEL_OPEN:
 558                 case SSH_CHANNEL_X11_OPEN:
 559                         return i;
 560                 case SSH_CHANNEL_INPUT_DRAINING:
 561                 case SSH_CHANNEL_OUTPUT_DRAINING:
 562                         if (!compat13)
 563                                 fatal("cannot happen: OUT_DRAIN");
 564                         return i;
 565                 default:
 566                         fatal("channel_find_open: bad channel type %d", c->type);
 567                         /* NOTREACHED */
 568                 }
 569         }
 570         return -1;
 571 }
 572
 573
 574 /*
 575  * Returns a message describing the currently open forwarded connections,
 576  * suitable for sending to the client.  The message contains crlf pairs for
 577  * newlines.
 578  */
 579 char *
 580 channel_open_message(void)
 581 {
 582         Buffer buffer;
 583         Channel *c;
 584         char buf[1024], *cp;
 585         u_int i;
 586
 587         buffer_init(&buffer);
 588         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 589         buffer_append(&buffer, buf, strlen(buf));
 590         for (i = 0; i < channels_alloc; i++) {
 591                 c = channels[i];
 592                 if (c == NULL)
 593                         continue;
 594                 switch (c->type) {
 595                 case SSH_CHANNEL_X11_LISTENER:
 596                 case SSH_CHANNEL_PORT_LISTENER:
 597                 case SSH_CHANNEL_RPORT_LISTENER:
 598                 case SSH_CHANNEL_CLOSED:
 599                 case SSH_CHANNEL_AUTH_SOCKET:
 600                 case SSH_CHANNEL_ZOMBIE:
 601                         continue;
 602                 case SSH_CHANNEL_LARVAL:
 603                 case SSH_CHANNEL_OPENING:
 604                 case SSH_CHANNEL_CONNECTING:
 605                 case SSH_CHANNEL_DYNAMIC:
 606                 case SSH_CHANNEL_OPEN:
 607                 case SSH_CHANNEL_X11_OPEN:
 608                 case SSH_CHANNEL_INPUT_DRAINING:
 609                 case SSH_CHANNEL_OUTPUT_DRAINING:
 610                         snprintf(buf, sizeof buf,
 611                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 612                             c->self, c->remote_name,
 613                             c->type, c->remote_id,
 614                             c->istate, buffer_len(&c->input),
 615                             c->ostate, buffer_len(&c->output),
 616                             c->rfd, c->wfd, c->ctl_fd);
 617                         buffer_append(&buffer, buf, strlen(buf));
 618                         continue;
 619                 default:
 620                         fatal("channel_open_message: bad channel type %d", c->type);
 621                         /* NOTREACHED */
 622                 }
 623         }
 624         buffer_append(&buffer, "\0", 1);
 625         cp = xstrdup(buffer_ptr(&buffer));
 626         buffer_free(&buffer);
 627         return cp;
 628 }
 629
 630 void
 631 channel_send_open(int id)
 632 {
 633         Channel *c = channel_lookup(id);
 634
 635         if (c == NULL) {
 636                 logit("channel_send_open: %d: bad id", id);
 637                 return;
 638         }
 639         debug2("channel %d: send open", id);
 640         packet_start(SSH2_MSG_CHANNEL_OPEN);
 641         packet_put_cstring(c->ctype);
 642         packet_put_int(c->self);
 643         packet_put_int(c->local_window);
 644         packet_put_int(c->local_maxpacket);
 645         packet_send();
 646 }
 647
 648 void
 649 channel_request_start(int id, char *service, int wantconfirm)
 650 {
 651         Channel *c = channel_lookup(id);
 652
 653         if (c == NULL) {
 654                 logit("channel_request_start: %d: unknown channel id", id);
 655                 return;
 656         }
 657         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 658         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 659         packet_put_int(c->remote_id);
 660         packet_put_cstring(service);
 661         packet_put_char(wantconfirm);
 662 }
 663
 664 void
 665 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 666 {
 667         Channel *c = channel_lookup(id);
 668
 669         if (c == NULL) {
 670                 logit("channel_register_comfirm: %d: bad id", id);
 671                 return;
 672         }
 673         c->confirm = fn;
 674         c->confirm_ctx = ctx;
 675 }
 676
 677 void
 678 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 679 {
 680         Channel *c = channel_by_id(id);
 681
 682         if (c == NULL) {
 683                 logit("channel_register_cleanup: %d: bad id", id);
 684                 return;
 685         }
 686         c->detach_user = fn;
 687         c->detach_close = do_close;
 688 }
 689
 690 void
 691 channel_cancel_cleanup(int id)
 692 {
 693         Channel *c = channel_by_id(id);
 694
 695         if (c == NULL) {
 696                 logit("channel_cancel_cleanup: %d: bad id", id);
 697                 return;
 698         }
 699         c->detach_user = NULL;
 700         c->detach_close = 0;
 701 }
 702
 703 void
 704 channel_register_filter(int id, channel_infilter_fn *ifn,
 705     channel_outfilter_fn *ofn)
 706 {
 707         Channel *c = channel_lookup(id);
 708
 709         if (c == NULL) {
 710                 logit("channel_register_filter: %d: bad id", id);
 711                 return;
 712         }
 713         c->input_filter = ifn;
 714         c->output_filter = ofn;
 715 }
 716
 717 void
 718 channel_set_fds(int id, int rfd, int wfd, int efd,
 719     int extusage, int nonblock, u_int window_max)
 720 {
 721         Channel *c = channel_lookup(id);
 722
 723         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 724                 fatal("channel_activate for non-larval channel %d.", id);
 725         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 726         c->type = SSH_CHANNEL_OPEN;
 727         c->local_window = c->local_window_max = window_max;
 728         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 729         packet_put_int(c->remote_id);
 730         packet_put_int(c->local_window);
 731         packet_send();
 732 }
 733
 734 /*
 735  * 'channel_pre*' are called just before select() to add any bits relevant to
 736  * channels in the select bitmasks.
 737  */
 738 /*
 739  * 'channel_post*': perform any appropriate operations for channels which
 740  * have events pending.
 741  */
 742 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 743 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 744 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 745
 746 /* ARGSUSED */
 747 static void
 748 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 749 {
 750         FD_SET(c->sock, readset);
 751 }
 752
 753 /* ARGSUSED */
 754 static void
 755 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 756 {
 757         debug3("channel %d: waiting for connection", c->self);
 758         FD_SET(c->sock, writeset);
 759 }
 760
 761 static void
 762 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 763 {
 764         if (buffer_len(&c->input) < packet_get_maxsize())
 765                 FD_SET(c->sock, readset);
 766         if (buffer_len(&c->output) > 0)
 767                 FD_SET(c->sock, writeset);
 768 }
 769
 770 int channel_tcpwinsz () {
 771         u_int32_t tcpwinsz = 0;
 772         socklen_t optsz = sizeof(tcpwinsz);
 773         int ret = -1;
 774         if(!packet_connection_is_on_socket())
 775             return(131072);
 776         ret = getsockopt(packet_get_connection_in(),
 777                          SOL_SOCKET, SO_RCVBUF, &tcpwinsz, &optsz);
 778         if ((ret == 0) && tcpwinsz > BUFFER_MAX_LEN_HPN)
 779             tcpwinsz = BUFFER_MAX_LEN_HPN;
 780         debug2("tcpwinsz: %d for connection: %d", tcpwinsz,
 781                packet_get_connection_in());
 782         return(tcpwinsz);
 783 }
 784
 785 static void
 786 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 787 {
 788         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 789
 790         /* check buffer limits */
 791         if (!c->tcpwinsz)
 792             c->tcpwinsz = channel_tcpwinsz();
 793         if (c->dynamic_window > 0)
 794             c->tcpwinsz = channel_tcpwinsz();
 795
 796         limit = MIN(limit, 2 * c->tcpwinsz);
 797
 798         if (c->istate == CHAN_INPUT_OPEN &&
 799             limit > 0 &&
 800             buffer_len(&c->input) < limit &&
 801             buffer_check_alloc(&c->input, CHAN_RBUF))
 802                 FD_SET(c->rfd, readset);
 803         if (c->ostate == CHAN_OUTPUT_OPEN ||
 804             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 805                 if (buffer_len(&c->output) > 0) {
 806                         FD_SET(c->wfd, writeset);
 807                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 808                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 809                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 810                                     c->self, c->efd, buffer_len(&c->extended));
 811                         else
 812                                 chan_obuf_empty(c);
 813                 }
 814         }
 815         /** XXX check close conditions, too */
 816         if (compat20 && c->efd != -1) {
 817                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 818                     buffer_len(&c->extended) > 0)
 819                         FD_SET(c->efd, writeset);
 820                 else if (!(c->flags & CHAN_EOF_SENT) &&
 821                     c->extended_usage == CHAN_EXTENDED_READ &&
 822                     buffer_len(&c->extended) < c->remote_window)
 823                         FD_SET(c->efd, readset);
 824         }
 825         /* XXX: What about efd? races? */
 826         if (compat20 && c->ctl_fd != -1 &&
 827             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 828                 FD_SET(c->ctl_fd, readset);
 829 }
 830
 831 /* ARGSUSED */
 832 static void
 833 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 834 {
 835         if (buffer_len(&c->input) == 0) {
 836                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 837                 packet_put_int(c->remote_id);
 838                 packet_send();
 839                 c->type = SSH_CHANNEL_CLOSED;
 840                 debug2("channel %d: closing after input drain.", c->self);
 841         }
 842 }
 843
 844 /* ARGSUSED */
 845 static void
 846 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 847 {
 848         if (buffer_len(&c->output) == 0)
 849                 chan_mark_dead(c);
 850         else
 851                 FD_SET(c->sock, writeset);
 852 }
 853
 854 /*
 855  * This is a special state for X11 authentication spoofing.  An opened X11
 856  * connection (when authentication spoofing is being done) remains in this
 857  * state until the first packet has been completely read.  The authentication
 858  * data in that packet is then substituted by the real data if it matches the
 859  * fake data, and the channel is put into normal mode.
 860  * XXX All this happens at the client side.
 861  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 862  */
 863 static int
 864 x11_open_helper(Buffer *b)
 865 {
 866         u_char *ucp;
 867         u_int proto_len, data_len;
 868
 869         /* Check if the fixed size part of the packet is in buffer. */
 870         if (buffer_len(b) < 12)
 871                 return 0;
 872
 873         /* Parse the lengths of variable-length fields. */
 874         ucp = buffer_ptr(b);
 875         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 876                 proto_len = 256 * ucp[6] + ucp[7];
 877                 data_len = 256 * ucp[8] + ucp[9];
 878         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 879                 proto_len = ucp[6] + 256 * ucp[7];
 880                 data_len = ucp[8] + 256 * ucp[9];
 881         } else {
 882                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 883                     ucp[0]);
 884                 return -1;
 885         }
 886
 887         /* Check if the whole packet is in buffer. */
 888         if (buffer_len(b) <
 889             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 890                 return 0;
 891
 892         /* Check if authentication protocol matches. */
 893         if (proto_len != strlen(x11_saved_proto) ||
 894             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 895                 debug2("X11 connection uses different authentication protocol.");
 896                 return -1;
 897         }
 898         /* Check if authentication data matches our fake data. */
 899         if (data_len != x11_fake_data_len ||
 900             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 901                 x11_fake_data, x11_fake_data_len) != 0) {
 902                 debug2("X11 auth data does not match fake data.");
 903                 return -1;
 904         }
 905         /* Check fake data length */
 906         if (x11_fake_data_len != x11_saved_data_len) {
 907                 error("X11 fake_data_len %d != saved_data_len %d",
 908                     x11_fake_data_len, x11_saved_data_len);
 909                 return -1;
 910         }
 911         /*
 912          * Received authentication protocol and data match
 913          * our fake data. Substitute the fake data with real
 914          * data.
 915          */
 916         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 917             x11_saved_data, x11_saved_data_len);
 918         return 1;
 919 }
 920
 921 static void
 922 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 923 {
 924         int ret = x11_open_helper(&c->output);
 925
 926         if (ret == 1) {
 927                 /* Start normal processing for the channel. */
 928                 c->type = SSH_CHANNEL_OPEN;
 929                 channel_pre_open_13(c, readset, writeset);
 930         } else if (ret == -1) {
 931                 /*
 932                  * We have received an X11 connection that has bad
 933                  * authentication information.
 934                  */
 935                 logit("X11 connection rejected because of wrong authentication.");
 936                 buffer_clear(&c->input);
 937                 buffer_clear(&c->output);
 938                 channel_close_fd(&c->sock);
 939                 c->sock = -1;
 940                 c->type = SSH_CHANNEL_CLOSED;
 941                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 942                 packet_put_int(c->remote_id);
 943                 packet_send();
 944         }
 945 }
 946
 947 static void
 948 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 949 {
 950         int ret = x11_open_helper(&c->output);
 951
 952         /* c->force_drain = 1; */
 953
 954         if (ret == 1) {
 955                 c->type = SSH_CHANNEL_OPEN;
 956                 channel_pre_open(c, readset, writeset);
 957         } else if (ret == -1) {
 958                 logit("X11 connection rejected because of wrong authentication.");
 959                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 960                 chan_read_failed(c);
 961                 buffer_clear(&c->input);
 962                 chan_ibuf_empty(c);
 963                 buffer_clear(&c->output);
 964                 /* for proto v1, the peer will send an IEOF */
 965                 if (compat20)
 966                         chan_write_failed(c);
 967                 else
 968                         c->type = SSH_CHANNEL_OPEN;
 969                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 970         }
 971 }
 972
 973 /* try to decode a socks4 header */
 974 /* ARGSUSED */
 975 static int
 976 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 977 {
 978         char *p, *host;
 979         u_int len, have, i, found;
 980         char username[256];
 981         struct {
 982                 u_int8_t version;
 983                 u_int8_t command;
 984                 u_int16_t dest_port;
 985                 struct in_addr dest_addr;
 986         } s4_req, s4_rsp;
 987
 988         debug2("channel %d: decode socks4", c->self);
 989
 990         have = buffer_len(&c->input);
 991         len = sizeof(s4_req);
 992         if (have < len)
 993                 return 0;
 994         p = buffer_ptr(&c->input);
 995         for (found = 0, i = len; i < have; i++) {
 996                 if (p[i] == '\0') {
 997                         found = 1;
 998                         break;
 999                 }
1000                 if (i > 1024) {
1001                         /* the peer is probably sending garbage */
1002                         debug("channel %d: decode socks4: too long",
1003                             c->self);
1004                         return -1;
1005                 }
1006         }
1007         if (!found)
1008                 return 0;
1009         buffer_get(&c->input, (char *)&s4_req.version, 1);
1010         buffer_get(&c->input, (char *)&s4_req.command, 1);
1011         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1012         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1013         have = buffer_len(&c->input);
1014         p = buffer_ptr(&c->input);
1015         len = strlen(p);
1016         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1017         if (len > have)
1018                 fatal("channel %d: decode socks4: len %d > have %d",
1019                     c->self, len, have);
1020         strlcpy(username, p, sizeof(username));
1021         buffer_consume(&c->input, len);
1022         buffer_consume(&c->input, 1);           /* trailing '\0' */
1023
1024         host = inet_ntoa(s4_req.dest_addr);
1025         strlcpy(c->path, host, sizeof(c->path));
1026         c->host_port = ntohs(s4_req.dest_port);
1027
1028         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1029             c->self, host, c->host_port, s4_req.command);
1030
1031         if (s4_req.command != 1) {
1032                 debug("channel %d: cannot handle: socks4 cn %d",
1033                     c->self, s4_req.command);
1034                 return -1;
1035         }
1036         s4_rsp.version = 0;                     /* vn: 0 for reply */
1037         s4_rsp.command = 90;                    /* cd: req granted */
1038         s4_rsp.dest_port = 0;                   /* ignored */
1039         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1040         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1041         return 1;
1042 }
1043
1044 /* try to decode a socks5 header */
1045 #define SSH_SOCKS5_AUTHDONE     0x1000
1046 #define SSH_SOCKS5_NOAUTH       0x00
1047 #define SSH_SOCKS5_IPV4         0x01
1048 #define SSH_SOCKS5_DOMAIN       0x03
1049 #define SSH_SOCKS5_IPV6         0x04
1050 #define SSH_SOCKS5_CONNECT      0x01
1051 #define SSH_SOCKS5_SUCCESS      0x00
1052
1053 /* ARGSUSED */
1054 static int
1055 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1056 {
1057         struct {
1058                 u_int8_t version;
1059                 u_int8_t command;
1060                 u_int8_t reserved;
1061                 u_int8_t atyp;
1062         } s5_req, s5_rsp;
1063         u_int16_t dest_port;
1064         u_char *p, dest_addr[255+1];
1065         u_int have, need, i, found, nmethods, addrlen, af;
1066
1067         debug2("channel %d: decode socks5", c->self);
1068         p = buffer_ptr(&c->input);
1069         if (p[0] != 0x05)
1070                 return -1;
1071         have = buffer_len(&c->input);
1072         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1073                 /* format: ver | nmethods | methods */
1074                 if (have < 2)
1075                         return 0;
1076                 nmethods = p[1];
1077                 if (have < nmethods + 2)
1078                         return 0;
1079                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1080                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1081                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1082                                 found = 1;
1083                                 break;
1084                         }
1085                 }
1086                 if (!found) {
1087                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1088                             c->self);
1089                         return -1;
1090                 }
1091                 buffer_consume(&c->input, nmethods + 2);
1092                 buffer_put_char(&c->output, 0x05);              /* version */
1093                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1094                 FD_SET(c->sock, writeset);
1095                 c->flags |= SSH_SOCKS5_AUTHDONE;
1096                 debug2("channel %d: socks5 auth done", c->self);
1097                 return 0;                               /* need more */
1098         }
1099         debug2("channel %d: socks5 post auth", c->self);
1100         if (have < sizeof(s5_req)+1)
1101                 return 0;                       /* need more */
1102         memcpy(&s5_req, p, sizeof(s5_req));
1103         if (s5_req.version != 0x05 ||
1104             s5_req.command != SSH_SOCKS5_CONNECT ||
1105             s5_req.reserved != 0x00) {
1106                 debug2("channel %d: only socks5 connect supported", c->self);
1107                 return -1;
1108         }
1109         switch (s5_req.atyp){
1110         case SSH_SOCKS5_IPV4:
1111                 addrlen = 4;
1112                 af = AF_INET;
1113                 break;
1114         case SSH_SOCKS5_DOMAIN:
1115                 addrlen = p[sizeof(s5_req)];
1116                 af = -1;
1117                 break;
1118         case SSH_SOCKS5_IPV6:
1119                 addrlen = 16;
1120                 af = AF_INET6;
1121                 break;
1122         default:
1123                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1124                 return -1;
1125         }
1126         need = sizeof(s5_req) + addrlen + 2;
1127         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1128                 need++;
1129         if (have < need)
1130                 return 0;
1131         buffer_consume(&c->input, sizeof(s5_req));
1132         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1133                 buffer_consume(&c->input, 1);    /* host string length */
1134         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1135         buffer_get(&c->input, (char *)&dest_port, 2);
1136         dest_addr[addrlen] = '\0';
1137         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1138                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1139         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1140                 return -1;
1141         c->host_port = ntohs(dest_port);
1142
1143         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1144             c->self, c->path, c->host_port, s5_req.command);
1145
1146         s5_rsp.version = 0x05;
1147         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1148         s5_rsp.reserved = 0;                    /* ignored */
1149         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1150         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1151         dest_port = 0;                          /* ignored */
1152
1153         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1154         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1155         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1156         return 1;
1157 }
1158
1159 /* dynamic port forwarding */
1160 static void
1161 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1162 {
1163         u_char *p;
1164         u_int have;
1165         int ret;
1166
1167         have = buffer_len(&c->input);
1168         c->delayed = 0;
1169         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1170         /* buffer_dump(&c->input); */
1171         /* check if the fixed size part of the packet is in buffer. */
1172         if (have < 3) {
1173                 /* need more */
1174                 FD_SET(c->sock, readset);
1175                 return;
1176         }
1177         /* try to guess the protocol */
1178         p = buffer_ptr(&c->input);
1179         switch (p[0]) {
1180         case 0x04:
1181                 ret = channel_decode_socks4(c, readset, writeset);
1182                 break;
1183         case 0x05:
1184                 ret = channel_decode_socks5(c, readset, writeset);
1185                 break;
1186         default:
1187                 ret = -1;
1188                 break;
1189         }
1190         if (ret < 0) {
1191                 chan_mark_dead(c);
1192         } else if (ret == 0) {
1193                 debug2("channel %d: pre_dynamic: need more", c->self);
1194                 /* need more */
1195                 FD_SET(c->sock, readset);
1196         } else {
1197                 /* switch to the next state */
1198                 c->type = SSH_CHANNEL_OPENING;
1199                 port_open_helper(c, "direct-tcpip");
1200         }
1201 }
1202
1203 /* This is our fake X11 server socket. */
1204 /* ARGSUSED */
1205 static void
1206 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1207 {
1208         Channel *nc;
1209         struct sockaddr addr;
1210         int newsock;
1211         socklen_t addrlen;
1212         char buf[16384], *remote_ipaddr;
1213         int remote_port;
1214
1215         if (FD_ISSET(c->sock, readset)) {
1216                 debug("X11 connection requested.");
1217                 addrlen = sizeof(addr);
1218                 newsock = accept(c->sock, &addr, &addrlen);
1219                 if (c->single_connection) {
1220                         debug2("single_connection: closing X11 listener.");
1221                         channel_close_fd(&c->sock);
1222                         chan_mark_dead(c);
1223                 }
1224                 if (newsock < 0) {
1225                         error("accept: %.100s", strerror(errno));
1226                         return;
1227                 }
1228                 set_nodelay(newsock);
1229                 remote_ipaddr = get_peer_ipaddr(newsock);
1230                 remote_port = get_peer_port(newsock);
1231                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1232                     remote_ipaddr, remote_port);
1233
1234                 nc = channel_new("accepted x11 socket",
1235                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1236                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1237                 if (compat20) {
1238                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1239                         packet_put_cstring("x11");
1240                         packet_put_int(nc->self);
1241                         packet_put_int(nc->local_window_max);
1242                         packet_put_int(nc->local_maxpacket);
1243                         /* originator ipaddr and port */
1244                         packet_put_cstring(remote_ipaddr);
1245                         if (datafellows & SSH_BUG_X11FWD) {
1246                                 debug2("ssh2 x11 bug compat mode");
1247                         } else {
1248                                 packet_put_int(remote_port);
1249                         }
1250                         packet_send();
1251                 } else {
1252                         packet_start(SSH_SMSG_X11_OPEN);
1253                         packet_put_int(nc->self);
1254                         if (packet_get_protocol_flags() &
1255                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1256                                 packet_put_cstring(buf);
1257                         packet_send();
1258                 }
1259                 xfree(remote_ipaddr);
1260         }
1261 }
1262
1263 static void
1264 port_open_helper(Channel *c, char *rtype)
1265 {
1266         int direct;
1267         char buf[1024];
1268         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1269         int remote_port = get_peer_port(c->sock);
1270
1271         direct = (strcmp(rtype, "direct-tcpip") == 0);
1272
1273         snprintf(buf, sizeof buf,
1274             "%s: listening port %d for %.100s port %d, "
1275             "connect from %.200s port %d",
1276             rtype, c->listening_port, c->path, c->host_port,
1277             remote_ipaddr, remote_port);
1278
1279         xfree(c->remote_name);
1280         c->remote_name = xstrdup(buf);
1281
1282         if (compat20) {
1283                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1284                 packet_put_cstring(rtype);
1285                 packet_put_int(c->self);
1286                 packet_put_int(c->local_window_max);
1287                 packet_put_int(c->local_maxpacket);
1288                 if (direct) {
1289                         /* target host, port */
1290                         packet_put_cstring(c->path);
1291                         packet_put_int(c->host_port);
1292                 } else {
1293                         /* listen address, port */
1294                         packet_put_cstring(c->path);
1295                         packet_put_int(c->listening_port);
1296                 }
1297                 /* originator host and port */
1298                 packet_put_cstring(remote_ipaddr);
1299                 packet_put_int((u_int)remote_port);
1300                 packet_send();
1301         } else {
1302                 packet_start(SSH_MSG_PORT_OPEN);
1303                 packet_put_int(c->self);
1304                 packet_put_cstring(c->path);
1305                 packet_put_int(c->host_port);
1306                 if (packet_get_protocol_flags() &
1307                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1308                         packet_put_cstring(c->remote_name);
1309                 packet_send();
1310         }
1311         xfree(remote_ipaddr);
1312 }
1313
1314 static void
1315 channel_set_reuseaddr(int fd)
1316 {
1317         int on = 1;
1318
1319         /*
1320          * Set socket options.
1321          * Allow local port reuse in TIME_WAIT.
1322          */
1323         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1324                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1325 }
1326
1327 /*
1328  * This socket is listening for connections to a forwarded TCP/IP port.
1329  */
1330 /* ARGSUSED */
1331 static void
1332 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1333 {
1334         Channel *nc;
1335         struct sockaddr addr;
1336         int newsock, nextstate;
1337         socklen_t addrlen;
1338         char *rtype;
1339
1340         if (FD_ISSET(c->sock, readset)) {
1341                 debug("Connection to port %d forwarding "
1342                     "to %.100s port %d requested.",
1343                     c->listening_port, c->path, c->host_port);
1344
1345                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1346                         nextstate = SSH_CHANNEL_OPENING;
1347                         rtype = "forwarded-tcpip";
1348                 } else {
1349                         if (c->host_port == 0) {
1350                                 nextstate = SSH_CHANNEL_DYNAMIC;
1351                                 rtype = "dynamic-tcpip";
1352                         } else {
1353                                 nextstate = SSH_CHANNEL_OPENING;
1354                                 rtype = "direct-tcpip";
1355                         }
1356                 }
1357
1358                 addrlen = sizeof(addr);
1359                 newsock = accept(c->sock, &addr, &addrlen);
1360                 if (newsock < 0) {
1361                         error("accept: %.100s", strerror(errno));
1362                         return;
1363                 }
1364                 set_nodelay(newsock);
1365                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1366                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1367                 nc->listening_port = c->listening_port;
1368                 nc->host_port = c->host_port;
1369                 strlcpy(nc->path, c->path, sizeof(nc->path));
1370
1371                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1372                         /*
1373                          * do not call the channel_post handler until
1374                          * this flag has been reset by a pre-handler.
1375                          * otherwise the FD_ISSET calls might overflow
1376                          */
1377                         nc->delayed = 1;
1378                 } else {
1379                         port_open_helper(nc, rtype);
1380                 }
1381         }
1382 }
1383
1384 /*
1385  * This is the authentication agent socket listening for connections from
1386  * clients.
1387  */
1388 /* ARGSUSED */
1389 static void
1390 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1391 {
1392         Channel *nc;
1393         int newsock;
1394         struct sockaddr addr;
1395         socklen_t addrlen;
1396
1397         if (FD_ISSET(c->sock, readset)) {
1398                 addrlen = sizeof(addr);
1399                 newsock = accept(c->sock, &addr, &addrlen);
1400                 if (newsock < 0) {
1401                         error("accept from auth socket: %.100s", strerror(errno));
1402                         return;
1403                 }
1404                 nc = channel_new("accepted auth socket",
1405                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1406                     c->local_window_max, c->local_maxpacket,
1407                     0, "accepted auth socket", 1);
1408                 if (compat20) {
1409                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1410                         packet_put_cstring("auth-agent@openssh.com");
1411                         packet_put_int(nc->self);
1412                         packet_put_int(c->local_window_max);
1413                         packet_put_int(c->local_maxpacket);
1414                 } else {
1415                         packet_start(SSH_SMSG_AGENT_OPEN);
1416                         packet_put_int(nc->self);
1417                 }
1418                 packet_send();
1419         }
1420 }
1421
1422 /* ARGSUSED */
1423 static void
1424 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1425 {
1426         int err = 0;
1427         socklen_t sz = sizeof(err);
1428
1429         if (FD_ISSET(c->sock, writeset)) {
1430                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1431                         err = errno;
1432                         error("getsockopt SO_ERROR failed");
1433                 }
1434                 if (err == 0) {
1435                         debug("channel %d: connected", c->self);
1436                         c->type = SSH_CHANNEL_OPEN;
1437                         if (compat20) {
1438                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1439                                 packet_put_int(c->remote_id);
1440                                 packet_put_int(c->self);
1441                                 packet_put_int(c->local_window);
1442                                 packet_put_int(c->local_maxpacket);
1443                         } else {
1444                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1445                                 packet_put_int(c->remote_id);
1446                                 packet_put_int(c->self);
1447                         }
1448                 } else {
1449                         debug("channel %d: not connected: %s",
1450                             c->self, strerror(err));
1451                         if (compat20) {
1452                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1453                                 packet_put_int(c->remote_id);
1454                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1455                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1456                                         packet_put_cstring(strerror(err));
1457                                         packet_put_cstring("");
1458                                 }
1459                         } else {
1460                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1461                                 packet_put_int(c->remote_id);
1462                         }
1463                         chan_mark_dead(c);
1464                 }
1465                 packet_send();
1466         }
1467 }
1468
1469 /* ARGSUSED */
1470 static int
1471 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1472 {
1473         char buf[CHAN_RBUF];
1474         int len, force;
1475
1476         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1477         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1478                 errno = 0;
1479                 len = read(c->rfd, buf, sizeof(buf));
1480                 if (len < 0 && (errno == EINTR || (errno == EAGAIN && !force)))
1481                         return 1;
1482 #ifndef PTY_ZEROREAD
1483                 if (len <= 0) {
1484 #else
1485                 if ((!c->isatty && len <= 0) ||
1486                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1487 #endif
1488                         debug2("channel %d: read<=0 rfd %d len %d",
1489                             c->self, c->rfd, len);
1490                         if (c->type != SSH_CHANNEL_OPEN) {
1491                                 debug2("channel %d: not open", c->self);
1492                                 chan_mark_dead(c);
1493                                 return -1;
1494                         } else if (compat13) {
1495                                 buffer_clear(&c->output);
1496                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1497                                 debug2("channel %d: input draining.", c->self);
1498                         } else {
1499                                 chan_read_failed(c);
1500                         }
1501                         return -1;
1502                 }
1503                 if (c->input_filter != NULL) {
1504                         if (c->input_filter(c, buf, len) == -1) {
1505                                 debug2("channel %d: filter stops", c->self);
1506                                 chan_read_failed(c);
1507                         }
1508                 } else if (c->datagram) {
1509                         buffer_put_string(&c->input, buf, len);
1510                 } else {
1511                         buffer_append(&c->input, buf, len);
1512                 }
1513         }
1514         return 1;
1515 }
1516
1517 /* ARGSUSED */
1518 static int
1519 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1520 {
1521         struct termios tio;
1522         u_char *data = NULL, *buf;
1523         u_int dlen;
1524         int len;
1525
1526         /* Send buffered output data to the socket. */
1527         if (c->wfd != -1 &&
1528             FD_ISSET(c->wfd, writeset) &&
1529             buffer_len(&c->output) > 0) {
1530                 if (c->output_filter != NULL) {
1531                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1532                                 debug2("channel %d: filter stops", c->self);
1533                                 if (c->type != SSH_CHANNEL_OPEN)
1534                                         chan_mark_dead(c);
1535                                 else
1536                                         chan_write_failed(c);
1537                                 return -1;
1538                         }
1539                 } else if (c->datagram) {
1540                         buf = data = buffer_get_string(&c->output, &dlen);
1541                 } else {
1542                         buf = data = buffer_ptr(&c->output);
1543                         dlen = buffer_len(&c->output);
1544                 }
1545
1546                 if (c->datagram) {
1547                         /* ignore truncated writes, datagrams might get lost */
1548                         c->local_consumed += dlen + 4;
1549                         len = write(c->wfd, buf, dlen);
1550                         xfree(data);
1551                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1552                                 return 1;
1553                         if (len <= 0) {
1554                                 if (c->type != SSH_CHANNEL_OPEN)
1555                                         chan_mark_dead(c);
1556                                 else
1557                                         chan_write_failed(c);
1558                                 return -1;
1559                         }
1560                         return 1;
1561                 }
1562 #ifdef _AIX
1563                 /* XXX: Later AIX versions can't push as much data to tty */
1564                 if (compat20 && c->wfd_isatty)
1565                         dlen = MIN(dlen, 8*1024);
1566 #endif
1567
1568                 len = write(c->wfd, buf, dlen);
1569                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1570                         return 1;
1571                 if (len <= 0) {
1572                         if (c->type != SSH_CHANNEL_OPEN) {
1573                                 debug2("channel %d: not open", c->self);
1574                                 chan_mark_dead(c);
1575                                 return -1;
1576                         } else if (compat13) {
1577                                 buffer_clear(&c->output);
1578                                 debug2("channel %d: input draining.", c->self);
1579                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1580                         } else {
1581                                 chan_write_failed(c);
1582                         }
1583                         return -1;
1584                 }
1585                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1586                         if (tcgetattr(c->wfd, &tio) == 0 &&
1587                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1588                                 /*
1589                                  * Simulate echo to reduce the impact of
1590                                  * traffic analysis. We need to match the
1591                                  * size of a SSH2_MSG_CHANNEL_DATA message
1592                                  * (4 byte channel id + buf)
1593                                  */
1594                                 packet_send_ignore(4 + len);
1595                                 packet_send();
1596                         }
1597                 }
1598                 buffer_consume(&c->output, len);
1599                 if (compat20 && len > 0) {
1600                         c->local_consumed += len;
1601                 }
1602         }
1603         return 1;
1604 }
1605
1606 static int
1607 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1608 {
1609         char buf[CHAN_RBUF];
1610         int len;
1611
1612 /** XXX handle drain efd, too */
1613         if (c->efd != -1) {
1614                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1615                     FD_ISSET(c->efd, writeset) &&
1616                     buffer_len(&c->extended) > 0) {
1617                         len = write(c->efd, buffer_ptr(&c->extended),
1618                             buffer_len(&c->extended));
1619                         debug2("channel %d: written %d to efd %d",
1620                             c->self, len, c->efd);
1621                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1622                                 return 1;
1623                         if (len <= 0) {
1624                                 debug2("channel %d: closing write-efd %d",
1625                                     c->self, c->efd);
1626                                 channel_close_fd(&c->efd);
1627                         } else {
1628                                 buffer_consume(&c->extended, len);
1629                                 c->local_consumed += len;
1630                         }
1631                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1632                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1633                         len = read(c->efd, buf, sizeof(buf));
1634                         debug2("channel %d: read %d from efd %d",
1635                             c->self, len, c->efd);
1636                         if (len < 0 && (errno == EINTR ||
1637                             (errno == EAGAIN && !c->detach_close)))
1638                                 return 1;
1639                         if (len <= 0) {
1640                                 debug2("channel %d: closing read-efd %d",
1641                                     c->self, c->efd);
1642                                 channel_close_fd(&c->efd);
1643                         } else {
1644                                 buffer_append(&c->extended, buf, len);
1645                         }
1646                 }
1647         }
1648         return 1;
1649 }
1650
1651 /* ARGSUSED */
1652 static int
1653 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1654 {
1655         char buf[16];
1656         int len;
1657
1658         /* Monitor control fd to detect if the slave client exits */
1659         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1660                 len = read(c->ctl_fd, buf, sizeof(buf));
1661                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1662                         return 1;
1663                 if (len <= 0) {
1664                         debug2("channel %d: ctl read<=0", c->self);
1665                         if (c->type != SSH_CHANNEL_OPEN) {
1666                                 debug2("channel %d: not open", c->self);
1667                                 chan_mark_dead(c);
1668                                 return -1;
1669                         } else {
1670                                 chan_read_failed(c);
1671                                 chan_write_failed(c);
1672                         }
1673                         return -1;
1674                 } else
1675                         fatal("%s: unexpected data on ctl fd", __func__);
1676         }
1677         return 1;
1678 }
1679
1680 static int
1681 channel_check_window(Channel *c)
1682 {
1683         if (c->type == SSH_CHANNEL_OPEN &&
1684             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1685             ((c->local_window_max - c->local_window >
1686             c->local_maxpacket*3) ||
1687             c->local_window < c->local_window_max/2) &&
1688             c->local_consumed > 0) {
1689                 u_int addition = 0;
1690                 /* adjust max window size if we are in a dynamic environment */
1691                 if (c->dynamic_window && (c->tcpwinsz > c->local_window_max)) {
1692                         addition = c->tcpwinsz - c->local_window_max;
1693                         c->local_window_max += addition;
1694                 }
1695                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1696                 packet_put_int(c->remote_id);
1697                 packet_put_int(c->local_consumed + addition);
1698                 packet_send();
1699                 debug2("channel %d: window %d sent adjust %d",
1700                     c->self, c->local_window,
1701                     c->local_consumed);
1702                 c->local_window += c->local_consumed + addition;
1703                 c->local_consumed = 0;
1704         }
1705         return 1;
1706 }
1707
1708 static void
1709 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1710 {
1711         if (c->delayed)
1712                 return;
1713         channel_handle_rfd(c, readset, writeset);
1714         channel_handle_wfd(c, readset, writeset);
1715         if (!compat20)
1716                 return;
1717         channel_handle_efd(c, readset, writeset);
1718         channel_handle_ctl(c, readset, writeset);
1719         channel_check_window(c);
1720 }
1721
1722 /* ARGSUSED */
1723 static void
1724 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1725 {
1726         int len;
1727
1728         /* Send buffered output data to the socket. */
1729         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1730                 len = write(c->sock, buffer_ptr(&c->output),
1731                             buffer_len(&c->output));
1732                 if (len <= 0)
1733                         buffer_clear(&c->output);
1734                 else
1735                         buffer_consume(&c->output, len);
1736         }
1737 }
1738
1739 static void
1740 channel_handler_init_20(void)
1741 {
1742         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1743         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1744         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1745         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1746         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1747         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1748         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1749         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1750
1751         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1752         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1753         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1754         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1755         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1756         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1757         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1758 }
1759
1760 static void
1761 channel_handler_init_13(void)
1762 {
1763         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1764         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1765         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1766         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1767         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1768         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1769         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1770         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1771         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1772
1773         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1774         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1775         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1776         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1777         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1778         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1779         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1780 }
1781
1782 static void
1783 channel_handler_init_15(void)
1784 {
1785         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1786         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1787         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1788         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1789         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1790         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1791         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1792
1793         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1794         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1795         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1796         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1797         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1798         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1799 }
1800
1801 static void
1802 channel_handler_init(void)
1803 {
1804         int i;
1805
1806         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1807                 channel_pre[i] = NULL;
1808                 channel_post[i] = NULL;
1809         }
1810         if (compat20)
1811                 channel_handler_init_20();
1812         else if (compat13)
1813                 channel_handler_init_13();
1814         else
1815                 channel_handler_init_15();
1816 }
1817
1818 /* gc dead channels */
1819 static void
1820 channel_garbage_collect(Channel *c)
1821 {
1822         if (c == NULL)
1823                 return;
1824         if (c->detach_user != NULL) {
1825                 if (!chan_is_dead(c, c->detach_close))
1826                         return;
1827                 debug2("channel %d: gc: notify user", c->self);
1828                 c->detach_user(c->self, NULL);
1829                 /* if we still have a callback */
1830                 if (c->detach_user != NULL)
1831                         return;
1832                 debug2("channel %d: gc: user detached", c->self);
1833         }
1834         if (!chan_is_dead(c, 1))
1835                 return;
1836         debug2("channel %d: garbage collecting", c->self);
1837         channel_free(c);
1838 }
1839
1840 static void
1841 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1842 {
1843         static int did_init = 0;
1844         u_int i;
1845         Channel *c;
1846
1847         if (!did_init) {
1848                 channel_handler_init();
1849                 did_init = 1;
1850         }
1851         for (i = 0; i < channels_alloc; i++) {
1852                 c = channels[i];
1853                 if (c == NULL)
1854                         continue;
1855                 if (ftab[c->type] != NULL)
1856                         (*ftab[c->type])(c, readset, writeset);
1857                 channel_garbage_collect(c);
1858         }
1859 }
1860
1861 /*
1862  * Allocate/update select bitmasks and add any bits relevant to channels in
1863  * select bitmasks.
1864  */
1865 void
1866 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1867     u_int *nallocp, int rekeying)
1868 {
1869         u_int n, sz, nfdset;
1870
1871         n = MAX(*maxfdp, channel_max_fd);
1872
1873         nfdset = howmany(n+1, NFDBITS);
1874         /* Explicitly test here, because xrealloc isn't always called */
1875         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1876                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1877         sz = nfdset * sizeof(fd_mask);
1878
1879         /* perhaps check sz < nalloc/2 and shrink? */
1880         if (*readsetp == NULL || sz > *nallocp) {
1881                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1882                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1883                 *nallocp = sz;
1884         }
1885         *maxfdp = n;
1886         memset(*readsetp, 0, sz);
1887         memset(*writesetp, 0, sz);
1888
1889         if (!rekeying)
1890                 channel_handler(channel_pre, *readsetp, *writesetp);
1891 }
1892
1893 /*
1894  * After select, perform any appropriate operations for channels which have
1895  * events pending.
1896  */
1897 void
1898 channel_after_select(fd_set *readset, fd_set *writeset)
1899 {
1900         channel_handler(channel_post, readset, writeset);
1901 }
1902
1903
1904 /* If there is data to send to the connection, enqueue some of it now. */
1905 void
1906 channel_output_poll(void)
1907 {
1908         Channel *c;
1909         u_int i, len;
1910
1911         for (i = 0; i < channels_alloc; i++) {
1912                 c = channels[i];
1913                 if (c == NULL)
1914                         continue;
1915
1916                 /*
1917                  * We are only interested in channels that can have buffered
1918                  * incoming data.
1919                  */
1920                 if (compat13) {
1921                         if (c->type != SSH_CHANNEL_OPEN &&
1922                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1923                                 continue;
1924                 } else {
1925                         if (c->type != SSH_CHANNEL_OPEN)
1926                                 continue;
1927                 }
1928                 if (compat20 &&
1929                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1930                         /* XXX is this true? */
1931                         debug3("channel %d: will not send data after close", c->self);
1932                         continue;
1933                 }
1934
1935                 /* Get the amount of buffered data for this channel. */
1936                 if ((c->istate == CHAN_INPUT_OPEN ||
1937                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1938                     (len = buffer_len(&c->input)) > 0) {
1939                         if (c->datagram) {
1940                                 if (len > 0) {
1941                                         u_char *data;
1942                                         u_int dlen;
1943
1944                                         data = buffer_get_string(&c->input,
1945                                             &dlen);
1946                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1947                                         packet_put_int(c->remote_id);
1948                                         packet_put_string(data, dlen);
1949                                         packet_send();
1950                                         c->remote_window -= dlen + 4;
1951                                         xfree(data);
1952                                 }
1953                                 continue;
1954                         }
1955                         /*
1956                          * Send some data for the other side over the secure
1957                          * connection.
1958                          */
1959                         if (compat20) {
1960                                 if (len > c->remote_window)
1961                                         len = c->remote_window;
1962                                 if (len > c->remote_maxpacket)
1963                                         len = c->remote_maxpacket;
1964                         } else {
1965                                 if (packet_is_interactive()) {
1966                                         if (len > 1024)
1967                                                 len = 512;
1968                                 } else {
1969                                         /* Keep the packets at reasonable size. */
1970                                         if (len > packet_get_maxsize()/2)
1971                                                 len = packet_get_maxsize()/2;
1972                                 }
1973                         }
1974                         if (len > 0) {
1975                                 packet_start(compat20 ?
1976                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1977                                 packet_put_int(c->remote_id);
1978                                 packet_put_string(buffer_ptr(&c->input), len);
1979                                 packet_send();
1980                                 buffer_consume(&c->input, len);
1981                                 c->remote_window -= len;
1982                         }
1983                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1984                         if (compat13)
1985                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1986                         /*
1987                          * input-buffer is empty and read-socket shutdown:
1988                          * tell peer, that we will not send more data: send IEOF.
1989                          * hack for extended data: delay EOF if EFD still in use.
1990                          */
1991                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1992                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1993                                     c->self, c->efd, buffer_len(&c->extended));
1994                         else
1995                                 chan_ibuf_empty(c);
1996                 }
1997                 /* Send extended data, i.e. stderr */
1998                 if (compat20 &&
1999                     !(c->flags & CHAN_EOF_SENT) &&
2000                     c->remote_window > 0 &&
2001                     (len = buffer_len(&c->extended)) > 0 &&
2002                     c->extended_usage == CHAN_EXTENDED_READ) {
2003                         debug2("channel %d: rwin %u elen %u euse %d",
2004                             c->self, c->remote_window, buffer_len(&c->extended),
2005                             c->extended_usage);
2006                         if (len > c->remote_window)
2007                                 len = c->remote_window;
2008                         if (len > c->remote_maxpacket)
2009                                 len = c->remote_maxpacket;
2010                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2011                         packet_put_int(c->remote_id);
2012                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2013                         packet_put_string(buffer_ptr(&c->extended), len);
2014                         packet_send();
2015                         buffer_consume(&c->extended, len);
2016                         c->remote_window -= len;
2017                         debug2("channel %d: sent ext data %d", c->self, len);
2018                 }
2019         }
2020 }
2021
2022
2023 /* -- protocol input */
2024
2025 /* ARGSUSED */
2026 void
2027 channel_input_data(int type, u_int32_t seq, void *ctxt)
2028 {
2029         int id;
2030         char *data;
2031         u_int data_len;
2032         Channel *c;
2033
2034         /* Get the channel number and verify it. */
2035         id = packet_get_int();
2036         c = channel_lookup(id);
2037         if (c == NULL)
2038                 packet_disconnect("Received data for nonexistent channel %d.", id);
2039
2040         /* Ignore any data for non-open channels (might happen on close) */
2041         if (c->type != SSH_CHANNEL_OPEN &&
2042             c->type != SSH_CHANNEL_X11_OPEN)
2043                 return;
2044
2045         /* Get the data. */
2046         data = packet_get_string(&data_len);
2047
2048         /*
2049          * Ignore data for protocol > 1.3 if output end is no longer open.
2050          * For protocol 2 the sending side is reducing its window as it sends
2051          * data, so we must 'fake' consumption of the data in order to ensure
2052          * that window updates are sent back.  Otherwise the connection might
2053          * deadlock.
2054          */
2055         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2056                 if (compat20) {
2057                         c->local_window -= data_len;
2058                         c->local_consumed += data_len;
2059                 }
2060                 xfree(data);
2061                 return;
2062         }
2063
2064         if (compat20) {
2065                 if (data_len > c->local_maxpacket) {
2066                         logit("channel %d: rcvd big packet %d, maxpack %d",
2067                             c->self, data_len, c->local_maxpacket);
2068                 }
2069                 if (data_len > c->local_window) {
2070                         logit("channel %d: rcvd too much data %d, win %d",
2071                             c->self, data_len, c->local_window);
2072                         xfree(data);
2073                         return;
2074                 }
2075                 c->local_window -= data_len;
2076         }
2077         packet_check_eom();
2078         if (c->datagram)
2079                 buffer_put_string(&c->output, data, data_len);
2080         else
2081                 buffer_append(&c->output, data, data_len);
2082         xfree(data);
2083 }
2084
2085 /* ARGSUSED */
2086 void
2087 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2088 {
2089         int id;
2090         char *data;
2091         u_int data_len, tcode;
2092         Channel *c;
2093
2094         /* Get the channel number and verify it. */
2095         id = packet_get_int();
2096         c = channel_lookup(id);
2097
2098         if (c == NULL)
2099                 packet_disconnect("Received extended_data for bad channel %d.", id);
2100         if (c->type != SSH_CHANNEL_OPEN) {
2101                 logit("channel %d: ext data for non open", id);
2102                 return;
2103         }
2104         if (c->flags & CHAN_EOF_RCVD) {
2105                 if (datafellows & SSH_BUG_EXTEOF)
2106                         debug("channel %d: accepting ext data after eof", id);
2107                 else
2108                         packet_disconnect("Received extended_data after EOF "
2109                             "on channel %d.", id);
2110         }
2111         tcode = packet_get_int();
2112         if (c->efd == -1 ||
2113             c->extended_usage != CHAN_EXTENDED_WRITE ||
2114             tcode != SSH2_EXTENDED_DATA_STDERR) {
2115                 logit("channel %d: bad ext data", c->self);
2116                 return;
2117         }
2118         data = packet_get_string(&data_len);
2119         packet_check_eom();
2120         if (data_len > c->local_window) {
2121                 logit("channel %d: rcvd too much extended_data %d, win %d",
2122                     c->self, data_len, c->local_window);
2123                 xfree(data);
2124                 return;
2125         }
2126         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2127         c->local_window -= data_len;
2128         buffer_append(&c->extended, data, data_len);
2129         xfree(data);
2130 }
2131
2132 /* ARGSUSED */
2133 void
2134 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2135 {
2136         int id;
2137         Channel *c;
2138
2139         id = packet_get_int();
2140         packet_check_eom();
2141         c = channel_lookup(id);
2142         if (c == NULL)
2143                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2144         chan_rcvd_ieof(c);
2145
2146         /* XXX force input close */
2147         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2148                 debug("channel %d: FORCE input drain", c->self);
2149                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2150                 if (buffer_len(&c->input) == 0)
2151                         chan_ibuf_empty(c);
2152         }
2153
2154 }
2155
2156 /* ARGSUSED */
2157 void
2158 channel_input_close(int type, u_int32_t seq, void *ctxt)
2159 {
2160         int id;
2161         Channel *c;
2162
2163         id = packet_get_int();
2164         packet_check_eom();
2165         c = channel_lookup(id);
2166         if (c == NULL)
2167                 packet_disconnect("Received close for nonexistent channel %d.", id);
2168
2169         /*
2170          * Send a confirmation that we have closed the channel and no more
2171          * data is coming for it.
2172          */
2173         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2174         packet_put_int(c->remote_id);
2175         packet_send();
2176
2177         /*
2178          * If the channel is in closed state, we have sent a close request,
2179          * and the other side will eventually respond with a confirmation.
2180          * Thus, we cannot free the channel here, because then there would be
2181          * no-one to receive the confirmation.  The channel gets freed when
2182          * the confirmation arrives.
2183          */
2184         if (c->type != SSH_CHANNEL_CLOSED) {
2185                 /*
2186                  * Not a closed channel - mark it as draining, which will
2187                  * cause it to be freed later.
2188                  */
2189                 buffer_clear(&c->input);
2190                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2191         }
2192 }
2193
2194 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2195 /* ARGSUSED */
2196 void
2197 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2198 {
2199         int id = packet_get_int();
2200         Channel *c = channel_lookup(id);
2201
2202         packet_check_eom();
2203         if (c == NULL)
2204                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2205         chan_rcvd_oclose(c);
2206 }
2207
2208 /* ARGSUSED */
2209 void
2210 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2211 {
2212         int id = packet_get_int();
2213         Channel *c = channel_lookup(id);
2214
2215         packet_check_eom();
2216         if (c == NULL)
2217                 packet_disconnect("Received close confirmation for "
2218                     "out-of-range channel %d.", id);
2219         if (c->type != SSH_CHANNEL_CLOSED)
2220                 packet_disconnect("Received close confirmation for "
2221                     "non-closed channel %d (type %d).", id, c->type);
2222         channel_free(c);
2223 }
2224
2225 /* ARGSUSED */
2226 void
2227 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2228 {
2229         int id, remote_id;
2230         Channel *c;
2231
2232         id = packet_get_int();
2233         c = channel_lookup(id);
2234
2235         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2236                 packet_disconnect("Received open confirmation for "
2237                     "non-opening channel %d.", id);
2238         remote_id = packet_get_int();
2239         /* Record the remote channel number and mark that the channel is now open. */
2240         c->remote_id = remote_id;
2241         c->type = SSH_CHANNEL_OPEN;
2242
2243         if (compat20) {
2244                 c->remote_window = packet_get_int();
2245                 c->remote_maxpacket = packet_get_int();
2246                 if (c->confirm) {
2247                         debug2("callback start");
2248                         c->confirm(c->self, c->confirm_ctx);
2249                         debug2("callback done");
2250                 }
2251                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2252                     c->remote_window, c->remote_maxpacket);
2253         }
2254         packet_check_eom();
2255 }
2256
2257 static char *
2258 reason2txt(int reason)
2259 {
2260         switch (reason) {
2261         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2262                 return "administratively prohibited";
2263         case SSH2_OPEN_CONNECT_FAILED:
2264                 return "connect failed";
2265         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2266                 return "unknown channel type";
2267         case SSH2_OPEN_RESOURCE_SHORTAGE:
2268                 return "resource shortage";
2269         }
2270         return "unknown reason";
2271 }
2272
2273 /* ARGSUSED */
2274 void
2275 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2276 {
2277         int id, reason;
2278         char *msg = NULL, *lang = NULL;
2279         Channel *c;
2280
2281         id = packet_get_int();
2282         c = channel_lookup(id);
2283
2284         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2285                 packet_disconnect("Received open failure for "
2286                     "non-opening channel %d.", id);
2287         if (compat20) {
2288                 reason = packet_get_int();
2289                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2290                         msg  = packet_get_string(NULL);
2291                         lang = packet_get_string(NULL);
2292                 }
2293                 logit("channel %d: open failed: %s%s%s", id,
2294                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2295                 if (msg != NULL)
2296                         xfree(msg);
2297                 if (lang != NULL)
2298                         xfree(lang);
2299         }
2300         packet_check_eom();
2301         /* Free the channel.  This will also close the socket. */
2302         channel_free(c);
2303 }
2304
2305 /* ARGSUSED */
2306 void
2307 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2308 {
2309         Channel *c;
2310         int id;
2311         u_int adjust;
2312
2313         if (!compat20)
2314                 return;
2315
2316         /* Get the channel number and verify it. */
2317         id = packet_get_int();
2318         c = channel_lookup(id);
2319
2320         if (c == NULL) {
2321                 logit("Received window adjust for non-open channel %d.", id);
2322                 return;
2323         }
2324         adjust = packet_get_int();
2325         packet_check_eom();
2326         debug2("channel %d: rcvd adjust %u", id, adjust);
2327         c->remote_window += adjust;
2328 }
2329
2330 /* ARGSUSED */
2331 void
2332 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2333 {
2334         Channel *c = NULL;
2335         u_short host_port;
2336         char *host, *originator_string;
2337         int remote_id, sock = -1;
2338
2339         remote_id = packet_get_int();
2340         host = packet_get_string(NULL);
2341         host_port = packet_get_int();
2342
2343         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2344                 originator_string = packet_get_string(NULL);
2345         } else {
2346                 originator_string = xstrdup("unknown (remote did not supply name)");
2347         }
2348         packet_check_eom();
2349         sock = channel_connect_to(host, host_port);
2350         if (sock != -1) {
2351                 c = channel_new("connected socket",
2352                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2353                     originator_string, 1);
2354                 c->remote_id = remote_id;
2355         }
2356         xfree(originator_string);
2357         if (c == NULL) {
2358                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2359                 packet_put_int(remote_id);
2360                 packet_send();
2361         }
2362         xfree(host);
2363 }
2364
2365
2366 /* -- tcp forwarding */
2367
2368 void
2369 channel_set_af(int af)
2370 {
2371         IPv4or6 = af;
2372 }
2373
2374 static int
2375 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2376     const char *host_to_connect, u_short port_to_connect, int gateway_ports,
2377     int hpn_disabled, int hpn_buffer_size)
2378 {
2379         Channel *c;
2380         int sock, r, success = 0, wildcard = 0, is_client;
2381         struct addrinfo hints, *ai, *aitop;
2382         const char *host, *addr;
2383         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2384
2385         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2386             listen_addr : host_to_connect;
2387         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2388
2389         if (host == NULL) {
2390                 error("No forward host name.");
2391                 return 0;
2392         }
2393         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2394                 error("Forward host name too long.");
2395                 return 0;
2396         }
2397
2398         /*
2399          * Determine whether or not a port forward listens to loopback,
2400          * specified address or wildcard. On the client, a specified bind
2401          * address will always override gateway_ports. On the server, a
2402          * gateway_ports of 1 (``yes'') will override the client's
2403          * specification and force a wildcard bind, whereas a value of 2
2404          * (``clientspecified'') will bind to whatever address the client
2405          * asked for.
2406          *
2407          * Special-case listen_addrs are:
2408          *
2409          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2410          * "" (empty string), "*"  -> wildcard v4/v6
2411          * "localhost"             -> loopback v4/v6
2412          */
2413         addr = NULL;
2414         if (listen_addr == NULL) {
2415                 /* No address specified: default to gateway_ports setting */
2416                 if (gateway_ports)
2417                         wildcard = 1;
2418         } else if (gateway_ports || is_client) {
2419                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2420                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2421                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2422                     (!is_client && gateway_ports == 1))
2423                         wildcard = 1;
2424                 else if (strcmp(listen_addr, "localhost") != 0)
2425                         addr = listen_addr;
2426         }
2427
2428         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2429             type, wildcard, (addr == NULL) ? "NULL" : addr);
2430
2431         /*
2432          * getaddrinfo returns a loopback address if the hostname is
2433          * set to NULL and hints.ai_flags is not AI_PASSIVE
2434          */
2435         memset(&hints, 0, sizeof(hints));
2436         hints.ai_family = IPv4or6;
2437         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2438         hints.ai_socktype = SOCK_STREAM;
2439         snprintf(strport, sizeof strport, "%d", listen_port);
2440         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2441                 if (addr == NULL) {
2442                         /* This really shouldn't happen */
2443                         packet_disconnect("getaddrinfo: fatal error: %s",
2444                             gai_strerror(r));
2445                 } else {
2446                         error("channel_setup_fwd_listener: "
2447                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2448                 }
2449                 return 0;
2450         }
2451
2452         for (ai = aitop; ai; ai = ai->ai_next) {
2453                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2454                         continue;
2455                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2456                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2457                         error("channel_setup_fwd_listener: getnameinfo failed");
2458                         continue;
2459                 }
2460                 /* Create a port to listen for the host. */
2461                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2462                 if (sock < 0) {
2463                         /* this is no error since kernel may not support ipv6 */
2464                         verbose("socket: %.100s", strerror(errno));
2465                         continue;
2466                 }
2467
2468                 channel_set_reuseaddr(sock);
2469
2470                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2471
2472                 /* Bind the socket to the address. */
2473                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2474                         /* address can be in use ipv6 address is already bound */
2475                         if (!ai->ai_next)
2476                                 error("bind: %.100s", strerror(errno));
2477                         else
2478                                 verbose("bind: %.100s", strerror(errno));
2479
2480                         close(sock);
2481                         continue;
2482                 }
2483                 /* Start listening for connections on the socket. */
2484                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2485                         error("listen: %.100s", strerror(errno));
2486                         close(sock);
2487                         continue;
2488                 }
2489                 /* Allocate a channel number for the socket. */
2490                 /* explicitly test for hpn disabled option. if true use smaller window size */
2491                 if (hpn_disabled)
2492                         c = channel_new("port listener", type, sock, sock, -1,
2493                           CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2494                           0, "port listener", 1);
2495                 else
2496                         c = channel_new("port listener", type, sock, sock, -1,
2497                           hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT,
2498                           0, "port listener", 1);
2499                 strlcpy(c->path, host, sizeof(c->path));
2500                 c->host_port = port_to_connect;
2501                 c->listening_port = listen_port;
2502                 success = 1;
2503         }
2504         if (success == 0)
2505                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2506                     listen_port);
2507         freeaddrinfo(aitop);
2508         return success;
2509 }
2510
2511 int
2512 channel_cancel_rport_listener(const char *host, u_short port)
2513 {
2514         u_int i;
2515         int found = 0;
2516
2517         for (i = 0; i < channels_alloc; i++) {
2518                 Channel *c = channels[i];
2519
2520                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2521                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2522                     c->listening_port == port) {
2523                         debug2("%s: close channel %d", __func__, i);
2524                         channel_free(c);
2525                         found = 1;
2526                 }
2527         }
2528
2529         return (found);
2530 }
2531
2532 /* protocol local port fwd, used by ssh (and sshd in v1) */
2533 int
2534 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2535     const char *host_to_connect, u_short port_to_connect, int gateway_ports,
2536     int hpn_disabled, int hpn_buffer_size)
2537 {
2538         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2539             listen_host, listen_port, host_to_connect, port_to_connect,
2540             gateway_ports, hpn_disabled, hpn_buffer_size);
2541 }
2542
2543 /* protocol v2 remote port fwd, used by sshd */
2544 int
2545 channel_setup_remote_fwd_listener(const char *listen_address,
2546     u_short listen_port, int gateway_ports, int hpn_disabled, int hpn_buffer_size)
2547 {
2548         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2549             listen_address, listen_port, NULL, 0, gateway_ports,
2550             hpn_disabled, hpn_buffer_size);
2551 }
2552
2553 /*
2554  * Initiate forwarding of connections to port "port" on remote host through
2555  * the secure channel to host:port from local side.
2556  */
2557
2558 int
2559 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2560     const char *host_to_connect, u_short port_to_connect)
2561 {
2562         int type, success = 0;
2563
2564         /* Record locally that connection to this host/port is permitted. */
2565         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2566                 fatal("channel_request_remote_forwarding: too many forwards");
2567
2568         /* Send the forward request to the remote side. */
2569         if (compat20) {
2570                 const char *address_to_bind;
2571                 if (listen_host == NULL) {
2572                         if (datafellows & SSH_BUG_RFWD_ADDR)
2573                                 address_to_bind = "127.0.0.1";
2574                         else
2575                                 address_to_bind = "localhost";
2576                 } else if (*listen_host == '\0' ||
2577                            strcmp(listen_host, "*") == 0) {
2578                         if (datafellows & SSH_BUG_RFWD_ADDR)
2579                                 address_to_bind = "0.0.0.0";
2580                         else
2581                                 address_to_bind = "";
2582                 } else
2583                         address_to_bind = listen_host;
2584
2585                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2586                 packet_put_cstring("tcpip-forward");
2587                 packet_put_char(1);                     /* boolean: want reply */
2588                 packet_put_cstring(address_to_bind);
2589                 packet_put_int(listen_port);
2590                 packet_send();
2591                 packet_write_wait();
2592                 /* Assume that server accepts the request */
2593                 success = 1;
2594         } else {
2595                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2596                 packet_put_int(listen_port);
2597                 packet_put_cstring(host_to_connect);
2598                 packet_put_int(port_to_connect);
2599                 packet_send();
2600                 packet_write_wait();
2601
2602                 /* Wait for response from the remote side. */
2603                 type = packet_read();
2604                 switch (type) {
2605                 case SSH_SMSG_SUCCESS:
2606                         success = 1;
2607                         break;
2608                 case SSH_SMSG_FAILURE:
2609                         break;
2610                 default:
2611                         /* Unknown packet */
2612                         packet_disconnect("Protocol error for port forward request:"
2613                             "received packet type %d.", type);
2614                 }
2615         }
2616         if (success) {
2617                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2618                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2619                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2620                 num_permitted_opens++;
2621         }
2622         return (success ? 0 : -1);
2623 }
2624
2625 /*
2626  * Request cancellation of remote forwarding of connection host:port from
2627  * local side.
2628  */
2629 void
2630 channel_request_rforward_cancel(const char *host, u_short port)
2631 {
2632         int i;
2633
2634         if (!compat20)
2635                 return;
2636
2637         for (i = 0; i < num_permitted_opens; i++) {
2638                 if (permitted_opens[i].host_to_connect != NULL &&
2639                     permitted_opens[i].listen_port == port)
2640                         break;
2641         }
2642         if (i >= num_permitted_opens) {
2643                 debug("%s: requested forward not found", __func__);
2644                 return;
2645         }
2646         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2647         packet_put_cstring("cancel-tcpip-forward");
2648         packet_put_char(0);
2649         packet_put_cstring(host == NULL ? "" : host);
2650         packet_put_int(port);
2651         packet_send();
2652
2653         permitted_opens[i].listen_port = 0;
2654         permitted_opens[i].port_to_connect = 0;
2655         xfree(permitted_opens[i].host_to_connect);
2656         permitted_opens[i].host_to_connect = NULL;
2657 }
2658
2659 /*
2660  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2661  * listening for the port, and sends back a success reply (or disconnect
2662  * message if there was an error).
2663  */
2664 int
2665 channel_input_port_forward_request(int is_root, int gateway_ports,
2666                                    int hpn_disabled, int hpn_buffer_size)
2667 {
2668         u_short port, host_port;
2669         int success = 0;
2670         char *hostname;
2671
2672         /* Get arguments from the packet. */
2673         port = packet_get_int();
2674         hostname = packet_get_string(NULL);
2675         host_port = packet_get_int();
2676
2677 #ifndef HAVE_CYGWIN
2678         /*
2679          * Check that an unprivileged user is not trying to forward a
2680          * privileged port.
2681          */
2682         if (port < IPPORT_RESERVED && !is_root)
2683                 packet_disconnect(
2684                     "Requested forwarding of port %d but user is not root.",
2685                     port);
2686         if (host_port == 0)
2687                 packet_disconnect("Dynamic forwarding denied.");
2688 #endif
2689
2690         /* Initiate forwarding */
2691         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2692             host_port, gateway_ports, hpn_disabled, hpn_buffer_size);
2693
2694         /* Free the argument string. */
2695         xfree(hostname);
2696
2697         return (success ? 0 : -1);
2698 }
2699
2700 /*
2701  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2702  * usually called by the server, because the user could connect to any port
2703  * anyway, and the server has no way to know but to trust the client anyway.
2704  */
2705 void
2706 channel_permit_all_opens(void)
2707 {
2708         if (num_permitted_opens == 0)
2709                 all_opens_permitted = 1;
2710 }
2711
2712 void
2713 channel_add_permitted_opens(char *host, int port)
2714 {
2715         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2716                 fatal("channel_add_permitted_opens: too many forwards");
2717         debug("allow port forwarding to host %s port %d", host, port);
2718
2719         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2720         permitted_opens[num_permitted_opens].port_to_connect = port;
2721         num_permitted_opens++;
2722
2723         all_opens_permitted = 0;
2724 }
2725
2726 int
2727 channel_add_adm_permitted_opens(char *host, int port)
2728 {
2729         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2730                 fatal("channel_add_adm_permitted_opens: too many forwards");
2731         debug("config allows port forwarding to host %s port %d", host, port);
2732
2733         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2734              = xstrdup(host);
2735         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2736         return ++num_adm_permitted_opens;
2737 }
2738
2739 void
2740 channel_clear_permitted_opens(void)
2741 {
2742         int i;
2743
2744         for (i = 0; i < num_permitted_opens; i++)
2745                 if (permitted_opens[i].host_to_connect != NULL)
2746                         xfree(permitted_opens[i].host_to_connect);
2747         num_permitted_opens = 0;
2748 }
2749
2750 void
2751 channel_clear_adm_permitted_opens(void)
2752 {
2753         int i;
2754
2755         for (i = 0; i < num_adm_permitted_opens; i++)
2756                 if (permitted_adm_opens[i].host_to_connect != NULL)
2757                         xfree(permitted_adm_opens[i].host_to_connect);
2758         num_adm_permitted_opens = 0;
2759 }
2760
2761 /* return socket to remote host, port */
2762 static int
2763 connect_to(const char *host, u_short port)
2764 {
2765         struct addrinfo hints, *ai, *aitop;
2766         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2767         int gaierr;
2768         int sock = -1;
2769
2770         memset(&hints, 0, sizeof(hints));
2771         hints.ai_family = IPv4or6;
2772         hints.ai_socktype = SOCK_STREAM;
2773         snprintf(strport, sizeof strport, "%d", port);
2774         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2775                 error("connect_to %.100s: unknown host (%s)", host,
2776                     gai_strerror(gaierr));
2777                 return -1;
2778         }
2779         for (ai = aitop; ai; ai = ai->ai_next) {
2780                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2781                         continue;
2782                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2783                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2784                         error("connect_to: getnameinfo failed");
2785                         continue;
2786                 }
2787                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2788                 if (sock < 0) {
2789                         if (ai->ai_next == NULL)
2790                                 error("socket: %.100s", strerror(errno));
2791                         else
2792                                 verbose("socket: %.100s", strerror(errno));
2793                         continue;
2794                 }
2795                 if (set_nonblock(sock) == -1)
2796                         fatal("%s: set_nonblock(%d)", __func__, sock);
2797                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2798                     errno != EINPROGRESS) {
2799                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2800                             strerror(errno));
2801                         close(sock);
2802                         continue;       /* fail -- try next */
2803                 }
2804                 break; /* success */
2805
2806         }
2807         freeaddrinfo(aitop);
2808         if (!ai) {
2809                 error("connect_to %.100s port %d: failed.", host, port);
2810                 return -1;
2811         }
2812         /* success */
2813         set_nodelay(sock);
2814         return sock;
2815 }
2816
2817 int
2818 channel_connect_by_listen_address(u_short listen_port)
2819 {
2820         int i;
2821
2822         for (i = 0; i < num_permitted_opens; i++)
2823                 if (permitted_opens[i].host_to_connect != NULL &&
2824                     permitted_opens[i].listen_port == listen_port)
2825                         return connect_to(
2826                             permitted_opens[i].host_to_connect,
2827                             permitted_opens[i].port_to_connect);
2828         error("WARNING: Server requests forwarding for unknown listen_port %d",
2829             listen_port);
2830         return -1;
2831 }
2832
2833 /* Check if connecting to that port is permitted and connect. */
2834 int
2835 channel_connect_to(const char *host, u_short port)
2836 {
2837         int i, permit, permit_adm = 1;
2838
2839         permit = all_opens_permitted;
2840         if (!permit) {
2841                 for (i = 0; i < num_permitted_opens; i++)
2842                         if (permitted_opens[i].host_to_connect != NULL &&
2843                             permitted_opens[i].port_to_connect == port &&
2844                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2845                                 permit = 1;
2846         }
2847
2848         if (num_adm_permitted_opens > 0) {
2849                 permit_adm = 0;
2850                 for (i = 0; i < num_adm_permitted_opens; i++)
2851                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2852                             permitted_adm_opens[i].port_to_connect == port &&
2853                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2854                             == 0)
2855                                 permit_adm = 1;
2856         }
2857
2858         if (!permit || !permit_adm) {
2859                 logit("Received request to connect to host %.100s port %d, "
2860                     "but the request was denied.", host, port);
2861                 return -1;
2862         }
2863         return connect_to(host, port);
2864 }
2865
2866 void
2867 channel_send_window_changes(void)
2868 {
2869         u_int i;
2870         struct winsize ws;
2871
2872         for (i = 0; i < channels_alloc; i++) {
2873                 if (channels[i] == NULL || !channels[i]->client_tty ||
2874                     channels[i]->type != SSH_CHANNEL_OPEN)
2875                         continue;
2876                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2877                         continue;
2878                 channel_request_start(i, "window-change", 0);
2879                 packet_put_int((u_int)ws.ws_col);
2880                 packet_put_int((u_int)ws.ws_row);
2881                 packet_put_int((u_int)ws.ws_xpixel);
2882                 packet_put_int((u_int)ws.ws_ypixel);
2883                 packet_send();
2884         }
2885 }
2886
2887 /* -- X11 forwarding */
2888
2889 /*
2890  * Creates an internet domain socket for listening for X11 connections.
2891  * Returns 0 and a suitable display number for the DISPLAY variable
2892  * stored in display_numberp , or -1 if an error occurs.
2893  */
2894 int
2895 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2896     int single_connection, u_int *display_numberp, int **chanids,
2897     int hpn_disabled, int hpn_buffer_size)
2898 {
2899         Channel *nc = NULL;
2900         int display_number, sock;
2901         u_short port;
2902         struct addrinfo hints, *ai, *aitop;
2903         char strport[NI_MAXSERV];
2904         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2905
2906         if (chanids == NULL)
2907                 return -1;
2908
2909         for (display_number = x11_display_offset;
2910             display_number < MAX_DISPLAYS;
2911             display_number++) {
2912                 port = 6000 + display_number;
2913                 memset(&hints, 0, sizeof(hints));
2914                 hints.ai_family = IPv4or6;
2915                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2916                 hints.ai_socktype = SOCK_STREAM;
2917                 snprintf(strport, sizeof strport, "%d", port);
2918                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2919                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2920                         return -1;
2921                 }
2922                 for (ai = aitop; ai; ai = ai->ai_next) {
2923                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2924                                 continue;
2925                         sock = socket(ai->ai_family, ai->ai_socktype,
2926                             ai->ai_protocol);
2927                         if (sock < 0) {
2928                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2929                                         error("socket: %.100s", strerror(errno));
2930                                         freeaddrinfo(aitop);
2931                                         return -1;
2932                                 } else {
2933                                         debug("x11_create_display_inet: Socket family %d not supported",
2934                                                  ai->ai_family);
2935                                         continue;
2936                                 }
2937                         }
2938 #ifdef IPV6_V6ONLY
2939                         if (ai->ai_family == AF_INET6) {
2940                                 int on = 1;
2941                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2942                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2943                         }
2944 #endif
2945                         channel_set_reuseaddr(sock);
2946                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2947                                 debug2("bind port %d: %.100s", port, strerror(errno));
2948                                 close(sock);
2949
2950                                 if (ai->ai_next)
2951                                         continue;
2952
2953                                 for (n = 0; n < num_socks; n++) {
2954                                         close(socks[n]);
2955                                 }
2956                                 num_socks = 0;
2957                                 break;
2958                         }
2959                         socks[num_socks++] = sock;
2960 #ifndef DONT_TRY_OTHER_AF
2961                         if (num_socks == NUM_SOCKS)
2962                                 break;
2963 #else
2964                         if (x11_use_localhost) {
2965                                 if (num_socks == NUM_SOCKS)
2966                                         break;
2967                         } else {
2968                                 break;
2969                         }
2970 #endif
2971                 }
2972                 freeaddrinfo(aitop);
2973                 if (num_socks > 0)
2974                         break;
2975         }
2976         if (display_number >= MAX_DISPLAYS) {
2977                 error("Failed to allocate internet-domain X11 display socket.");
2978                 return -1;
2979         }
2980         /* Start listening for connections on the socket. */
2981         for (n = 0; n < num_socks; n++) {
2982                 sock = socks[n];
2983                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2984                         error("listen: %.100s", strerror(errno));
2985                         close(sock);
2986                         return -1;
2987                 }
2988         }
2989
2990         /* Allocate a channel for each socket. */
2991         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2992         for (n = 0; n < num_socks; n++) {
2993                 sock = socks[n];
2994                 if (hpn_disabled)
2995                         nc = channel_new("x11 listener",
2996                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2997                             CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2998                             0, "X11 inet listener", 1);
2999                 else
3000                         nc = channel_new("x11 listener",
3001                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3002                             hpn_buffer_size, CHAN_X11_PACKET_DEFAULT,
3003                             0, "X11 inet listener", 1);
3004                 nc->single_connection = single_connection;
3005                 (*chanids)[n] = nc->self;
3006         }
3007         (*chanids)[n] = -1;
3008
3009         /* Return the display number for the DISPLAY environment variable. */
3010         *display_numberp = display_number;
3011         return (0);
3012 }
3013
3014 static int
3015 connect_local_xsocket(u_int dnr)
3016 {
3017         int sock;
3018         struct sockaddr_un addr;
3019
3020         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3021         if (sock < 0)
3022                 error("socket: %.100s", strerror(errno));
3023         memset(&addr, 0, sizeof(addr));
3024         addr.sun_family = AF_UNIX;
3025         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
3026         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3027                 return sock;
3028         close(sock);
3029         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3030         return -1;
3031 }
3032
3033 int
3034 x11_connect_display(void)
3035 {
3036         u_int display_number;
3037         const char *display;
3038         char buf[1024], *cp;
3039         struct addrinfo hints, *ai, *aitop;
3040         char strport[NI_MAXSERV];
3041         int gaierr, sock = 0;
3042
3043         /* Try to open a socket for the local X server. */
3044         display = getenv("DISPLAY");
3045         if (!display) {
3046                 error("DISPLAY not set.");
3047                 return -1;
3048         }
3049         /*
3050          * Now we decode the value of the DISPLAY variable and make a
3051          * connection to the real X server.
3052          */
3053
3054         /*
3055          * Check if it is a unix domain socket.  Unix domain displays are in
3056          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3057          */
3058         if (strncmp(display, "unix:", 5) == 0 ||
3059             display[0] == ':') {
3060                 /* Connect to the unix domain socket. */
3061                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3062                         error("Could not parse display number from DISPLAY: %.100s",
3063                             display);
3064                         return -1;
3065                 }
3066                 /* Create a socket. */
3067                 sock = connect_local_xsocket(display_number);
3068                 if (sock < 0)
3069                         return -1;
3070
3071                 /* OK, we now have a connection to the display. */
3072                 return sock;
3073         }
3074         /*
3075          * Connect to an inet socket.  The DISPLAY value is supposedly
3076          * hostname:d[.s], where hostname may also be numeric IP address.
3077          */
3078         strlcpy(buf, display, sizeof(buf));
3079         cp = strchr(buf, ':');
3080         if (!cp) {
3081                 error("Could not find ':' in DISPLAY: %.100s", display);
3082                 return -1;
3083         }
3084         *cp = 0;
3085         /* buf now contains the host name.  But first we parse the display number. */
3086         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3087                 error("Could not parse display number from DISPLAY: %.100s",
3088                     display);
3089                 return -1;
3090         }
3091
3092         /* Look up the host address */
3093         memset(&hints, 0, sizeof(hints));
3094         hints.ai_family = IPv4or6;
3095         hints.ai_socktype = SOCK_STREAM;
3096         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3097         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3098                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
3099                 return -1;
3100         }
3101         for (ai = aitop; ai; ai = ai->ai_next) {
3102                 /* Create a socket. */
3103                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3104                 if (sock < 0) {
3105                         debug2("socket: %.100s", strerror(errno));
3106                         continue;
3107                 }
3108                 /* Connect it to the display. */
3109                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3110                         debug2("connect %.100s port %u: %.100s", buf,
3111                             6000 + display_number, strerror(errno));
3112                         close(sock);
3113                         continue;
3114                 }
3115                 /* Success */
3116                 break;
3117         }
3118         freeaddrinfo(aitop);
3119         if (!ai) {
3120                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3121                     strerror(errno));
3122                 return -1;
3123         }
3124         set_nodelay(sock);
3125         return sock;
3126 }
3127
3128 /*
3129  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3130  * the remote channel number.  We should do whatever we want, and respond
3131  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3132  */
3133
3134 /* ARGSUSED */
3135 void
3136 x11_input_open(int type, u_int32_t seq, void *ctxt)
3137 {
3138         Channel *c = NULL;
3139         int remote_id, sock = 0;
3140         char *remote_host;
3141
3142         debug("Received X11 open request.");
3143
3144         remote_id = packet_get_int();
3145
3146         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3147                 remote_host = packet_get_string(NULL);
3148         } else {
3149                 remote_host = xstrdup("unknown (remote did not supply name)");
3150         }
3151         packet_check_eom();
3152
3153         /* Obtain a connection to the real X display. */
3154         sock = x11_connect_display();
3155         if (sock != -1) {
3156                 /* Allocate a channel for this connection. */
3157                 c = channel_new("connected x11 socket",
3158                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3159                     remote_host, 1);
3160                 c->remote_id = remote_id;
3161                 c->force_drain = 1;
3162         }
3163         xfree(remote_host);
3164         if (c == NULL) {
3165                 /* Send refusal to the remote host. */
3166                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3167                 packet_put_int(remote_id);
3168         } else {
3169                 /* Send a confirmation to the remote host. */
3170                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3171                 packet_put_int(remote_id);
3172                 packet_put_int(c->self);
3173         }
3174         packet_send();
3175 }
3176
3177 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3178 /* ARGSUSED */
3179 void
3180 deny_input_open(int type, u_int32_t seq, void *ctxt)
3181 {
3182         int rchan = packet_get_int();
3183
3184         switch (type) {
3185         case SSH_SMSG_AGENT_OPEN:
3186                 error("Warning: ssh server tried agent forwarding.");
3187                 break;
3188         case SSH_SMSG_X11_OPEN:
3189                 error("Warning: ssh server tried X11 forwarding.");
3190                 break;
3191         default:
3192                 error("deny_input_open: type %d", type);
3193                 break;
3194         }
3195         error("Warning: this is probably a break-in attempt by a malicious server.");
3196         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3197         packet_put_int(rchan);
3198         packet_send();
3199 }
3200
3201 /*
3202  * Requests forwarding of X11 connections, generates fake authentication
3203  * data, and enables authentication spoofing.
3204  * This should be called in the client only.
3205  */
3206 void
3207 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3208     const char *proto, const char *data)
3209 {
3210         u_int data_len = (u_int) strlen(data) / 2;
3211         u_int i, value;
3212         char *new_data;
3213         int screen_number;
3214         const char *cp;
3215         u_int32_t rnd = 0;
3216
3217         if (x11_saved_display == NULL)
3218                 x11_saved_display = xstrdup(disp);
3219         else if (strcmp(disp, x11_saved_display) != 0) {
3220                 error("x11_request_forwarding_with_spoofing: different "
3221                     "$DISPLAY already forwarded");
3222                 return;
3223         }
3224
3225         cp = strchr(disp, ':');
3226         if (cp)
3227                 cp = strchr(cp, '.');
3228         if (cp)
3229                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3230         else
3231                 screen_number = 0;
3232
3233         if (x11_saved_proto == NULL) {
3234                 /* Save protocol name. */
3235                 x11_saved_proto = xstrdup(proto);
3236                 /*
3237                  * Extract real authentication data and generate fake data
3238                  * of the same length.
3239                  */
3240                 x11_saved_data = xmalloc(data_len);
3241                 x11_fake_data = xmalloc(data_len);
3242                 for (i = 0; i < data_len; i++) {
3243                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3244                                 fatal("x11_request_forwarding: bad "
3245                                     "authentication data: %.100s", data);
3246                         if (i % 4 == 0)
3247                                 rnd = arc4random();
3248                         x11_saved_data[i] = value;
3249                         x11_fake_data[i] = rnd & 0xff;
3250                         rnd >>= 8;
3251                 }
3252                 x11_saved_data_len = data_len;
3253                 x11_fake_data_len = data_len;
3254         }
3255
3256         /* Convert the fake data into hex. */
3257         new_data = tohex(x11_fake_data, data_len);
3258
3259         /* Send the request packet. */
3260         if (compat20) {
3261                 channel_request_start(client_session_id, "x11-req", 0);
3262                 packet_put_char(0);     /* XXX bool single connection */
3263         } else {
3264                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3265         }
3266         packet_put_cstring(proto);
3267         packet_put_cstring(new_data);
3268         packet_put_int(screen_number);
3269         packet_send();
3270         packet_write_wait();
3271         xfree(new_data);
3272 }
3273
3274
3275 /* -- agent forwarding */
3276
3277 /* Sends a message to the server to request authentication fd forwarding. */
3278
3279 void
3280 auth_request_forwarding(void)
3281 {
3282         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3283         packet_send();
3284         packet_write_wait();
3285 }