crypto/openssh-4/channels.c

   1 /* $OpenBSD: channels.c,v 1.268 2007/01/03 03:01:40 stevesk 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 /* -- channel core */
  80
  81 /*
  82  * Pointer to an array containing all allocated channels.  The array is
  83  * dynamically extended as needed.
  84  */
  85 static Channel **channels = NULL;
  86
  87 /*
  88  * Size of the channel array.  All slots of the array must always be
  89  * initialized (at least the type field); unused slots set to NULL
  90  */
  91 static u_int channels_alloc = 0;
  92
  93 /*
  94  * Maximum file descriptor value used in any of the channels.  This is
  95  * updated in channel_new.
  96  */
  97 static int channel_max_fd = 0;
  98
  99
 100 /* -- tcp forwarding */
 101
 102 /*
 103  * Data structure for storing which hosts are permitted for forward requests.
 104  * The local sides of any remote forwards are stored in this array to prevent
 105  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 106  * network (which might be behind a firewall).
 107  */
 108 typedef struct {
 109         char *host_to_connect;          /* Connect to 'host'. */
 110         u_short port_to_connect;        /* Connect to 'port'. */
 111         u_short listen_port;            /* Remote side should listen port number. */
 112 } ForwardPermission;
 113
 114 /* List of all permitted host/port pairs to connect by the user. */
 115 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 116
 117 /* List of all permitted host/port pairs to connect by the admin. */
 118 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 119
 120 /* Number of permitted host/port pairs in the array permitted by the user. */
 121 static int num_permitted_opens = 0;
 122
 123 /* Number of permitted host/port pair in the array permitted by the admin. */
 124 static int num_adm_permitted_opens = 0;
 125
 126 /*
 127  * If this is true, all opens are permitted.  This is the case on the server
 128  * on which we have to trust the client anyway, and the user could do
 129  * anything after logging in anyway.
 130  */
 131 static int all_opens_permitted = 0;
 132
 133
 134 /* -- X11 forwarding */
 135
 136 /* Maximum number of fake X11 displays to try. */
 137 #define MAX_DISPLAYS  1000
 138
 139 /* Saved X11 local (client) display. */
 140 static char *x11_saved_display = NULL;
 141
 142 /* Saved X11 authentication protocol name. */
 143 static char *x11_saved_proto = NULL;
 144
 145 /* Saved X11 authentication data.  This is the real data. */
 146 static char *x11_saved_data = NULL;
 147 static u_int x11_saved_data_len = 0;
 148
 149 /*
 150  * Fake X11 authentication data.  This is what the server will be sending us;
 151  * we should replace any occurrences of this by the real data.
 152  */
 153 static u_char *x11_fake_data = NULL;
 154 static u_int x11_fake_data_len;
 155
 156
 157 /* -- agent forwarding */
 158
 159 #define NUM_SOCKS       10
 160
 161 /* AF_UNSPEC or AF_INET or AF_INET6 */
 162 static int IPv4or6 = AF_UNSPEC;
 163
 164 /* helper */
 165 static void port_open_helper(Channel *c, char *rtype);
 166
 167 /* -- channel core */
 168
 169 Channel *
 170 channel_by_id(int id)
 171 {
 172         Channel *c;
 173
 174         if (id < 0 || (u_int)id >= channels_alloc) {
 175                 logit("channel_by_id: %d: bad id", id);
 176                 return NULL;
 177         }
 178         c = channels[id];
 179         if (c == NULL) {
 180                 logit("channel_by_id: %d: bad id: channel free", id);
 181                 return NULL;
 182         }
 183         return c;
 184 }
 185
 186 /*
 187  * Returns the channel if it is allowed to receive protocol messages.
 188  * Private channels, like listening sockets, may not receive messages.
 189  */
 190 Channel *
 191 channel_lookup(int id)
 192 {
 193         Channel *c;
 194
 195         if ((c = channel_by_id(id)) == NULL)
 196                 return (NULL);
 197
 198         switch (c->type) {
 199         case SSH_CHANNEL_X11_OPEN:
 200         case SSH_CHANNEL_LARVAL:
 201         case SSH_CHANNEL_CONNECTING:
 202         case SSH_CHANNEL_DYNAMIC:
 203         case SSH_CHANNEL_OPENING:
 204         case SSH_CHANNEL_OPEN:
 205         case SSH_CHANNEL_INPUT_DRAINING:
 206         case SSH_CHANNEL_OUTPUT_DRAINING:
 207                 return (c);
 208         }
 209         logit("Non-public channel %d, type %d.", id, c->type);
 210         return (NULL);
 211 }
 212
 213 /*
 214  * Register filedescriptors for a channel, used when allocating a channel or
 215  * when the channel consumer/producer is ready, e.g. shell exec'd
 216  */
 217 static void
 218 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 219     int extusage, int nonblock)
 220 {
 221         /* Update the maximum file descriptor value. */
 222         channel_max_fd = MAX(channel_max_fd, rfd);
 223         channel_max_fd = MAX(channel_max_fd, wfd);
 224         channel_max_fd = MAX(channel_max_fd, efd);
 225
 226         /* XXX set close-on-exec -markus */
 227
 228         c->rfd = rfd;
 229         c->wfd = wfd;
 230         c->sock = (rfd == wfd) ? rfd : -1;
 231         c->ctl_fd = -1; /* XXX: set elsewhere */
 232         c->efd = efd;
 233         c->extended_usage = extusage;
 234
 235         /* XXX ugly hack: nonblock is only set by the server */
 236         if (nonblock && isatty(c->rfd)) {
 237                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 238                 c->isatty = 1;
 239                 if (!isatty(c->wfd)) {
 240                         error("channel %d: wfd %d is not a tty?",
 241                             c->self, c->wfd);
 242                 }
 243         } else {
 244                 c->isatty = 0;
 245         }
 246         c->wfd_isatty = isatty(c->wfd);
 247
 248         /* enable nonblocking mode */
 249         if (nonblock) {
 250                 if (rfd != -1)
 251                         set_nonblock(rfd);
 252                 if (wfd != -1)
 253                         set_nonblock(wfd);
 254                 if (efd != -1)
 255                         set_nonblock(efd);
 256         }
 257 }
 258
 259 /*
 260  * Allocate a new channel object and set its type and socket. This will cause
 261  * remote_name to be freed.
 262  */
 263 Channel *
 264 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 265     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 266 {
 267         int found;
 268         u_int i;
 269         Channel *c;
 270
 271         /* Do initial allocation if this is the first call. */
 272         if (channels_alloc == 0) {
 273                 channels_alloc = 10;
 274                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 275                 for (i = 0; i < channels_alloc; i++)
 276                         channels[i] = NULL;
 277         }
 278         /* Try to find a free slot where to put the new channel. */
 279         for (found = -1, i = 0; i < channels_alloc; i++)
 280                 if (channels[i] == NULL) {
 281                         /* Found a free slot. */
 282                         found = (int)i;
 283                         break;
 284                 }
 285         if (found < 0) {
 286                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 287                 found = channels_alloc;
 288                 if (channels_alloc > 10000)
 289                         fatal("channel_new: internal error: channels_alloc %d "
 290                             "too big.", channels_alloc);
 291                 channels = xrealloc(channels, channels_alloc + 10,
 292                     sizeof(Channel *));
 293                 channels_alloc += 10;
 294                 debug2("channel: expanding %d", channels_alloc);
 295                 for (i = found; i < channels_alloc; i++)
 296                         channels[i] = NULL;
 297         }
 298         /* Initialize and return new channel. */
 299         c = channels[found] = xcalloc(1, sizeof(Channel));
 300         buffer_init(&c->input);
 301         buffer_init(&c->output);
 302         buffer_init(&c->extended);
 303         c->ostate = CHAN_OUTPUT_OPEN;
 304         c->istate = CHAN_INPUT_OPEN;
 305         c->flags = 0;
 306         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 307         c->self = found;
 308         c->type = type;
 309         c->ctype = ctype;
 310         c->local_window = window;
 311         c->local_window_max = window;
 312         c->local_consumed = 0;
 313         c->local_maxpacket = maxpack;
 314         c->remote_id = -1;
 315         c->remote_name = xstrdup(remote_name);
 316         c->remote_window = 0;
 317         c->remote_maxpacket = 0;
 318         c->force_drain = 0;
 319         c->single_connection = 0;
 320         c->detach_user = NULL;
 321         c->detach_close = 0;
 322         c->confirm = NULL;
 323         c->confirm_ctx = NULL;
 324         c->input_filter = NULL;
 325         c->output_filter = NULL;
 326         debug("channel %d: new [%s]", found, remote_name);
 327         return c;
 328 }
 329
 330 static int
 331 channel_find_maxfd(void)
 332 {
 333         u_int i;
 334         int max = 0;
 335         Channel *c;
 336
 337         for (i = 0; i < channels_alloc; i++) {
 338                 c = channels[i];
 339                 if (c != NULL) {
 340                         max = MAX(max, c->rfd);
 341                         max = MAX(max, c->wfd);
 342                         max = MAX(max, c->efd);
 343                 }
 344         }
 345         return max;
 346 }
 347
 348 int
 349 channel_close_fd(int *fdp)
 350 {
 351         int ret = 0, fd = *fdp;
 352
 353         if (fd != -1) {
 354                 ret = close(fd);
 355                 *fdp = -1;
 356                 if (fd == channel_max_fd)
 357                         channel_max_fd = channel_find_maxfd();
 358         }
 359         return ret;
 360 }
 361
 362 /* Close all channel fd/socket. */
 363 static void
 364 channel_close_fds(Channel *c)
 365 {
 366         debug3("channel %d: close_fds r %d w %d e %d c %d",
 367             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 368
 369         channel_close_fd(&c->sock);
 370         channel_close_fd(&c->ctl_fd);
 371         channel_close_fd(&c->rfd);
 372         channel_close_fd(&c->wfd);
 373         channel_close_fd(&c->efd);
 374 }
 375
 376 /* Free the channel and close its fd/socket. */
 377 void
 378 channel_free(Channel *c)
 379 {
 380         char *s;
 381         u_int i, n;
 382
 383         for (n = 0, i = 0; i < channels_alloc; i++)
 384                 if (channels[i])
 385                         n++;
 386         debug("channel %d: free: %s, nchannels %u", c->self,
 387             c->remote_name ? c->remote_name : "???", n);
 388
 389         s = channel_open_message();
 390         debug3("channel %d: status: %s", c->self, s);
 391         xfree(s);
 392
 393         if (c->sock != -1)
 394                 shutdown(c->sock, SHUT_RDWR);
 395         if (c->ctl_fd != -1)
 396                 shutdown(c->ctl_fd, SHUT_RDWR);
 397         channel_close_fds(c);
 398         buffer_free(&c->input);
 399         buffer_free(&c->output);
 400         buffer_free(&c->extended);
 401         if (c->remote_name) {
 402                 xfree(c->remote_name);
 403                 c->remote_name = NULL;
 404         }
 405         channels[c->self] = NULL;
 406         xfree(c);
 407 }
 408
 409 void
 410 channel_free_all(void)
 411 {
 412         u_int i;
 413
 414         for (i = 0; i < channels_alloc; i++)
 415                 if (channels[i] != NULL)
 416                         channel_free(channels[i]);
 417 }
 418
 419 /*
 420  * Closes the sockets/fds of all channels.  This is used to close extra file
 421  * descriptors after a fork.
 422  */
 423 void
 424 channel_close_all(void)
 425 {
 426         u_int i;
 427
 428         for (i = 0; i < channels_alloc; i++)
 429                 if (channels[i] != NULL)
 430                         channel_close_fds(channels[i]);
 431 }
 432
 433 /*
 434  * Stop listening to channels.
 435  */
 436 void
 437 channel_stop_listening(void)
 438 {
 439         u_int i;
 440         Channel *c;
 441
 442         for (i = 0; i < channels_alloc; i++) {
 443                 c = channels[i];
 444                 if (c != NULL) {
 445                         switch (c->type) {
 446                         case SSH_CHANNEL_AUTH_SOCKET:
 447                         case SSH_CHANNEL_PORT_LISTENER:
 448                         case SSH_CHANNEL_RPORT_LISTENER:
 449                         case SSH_CHANNEL_X11_LISTENER:
 450                                 channel_close_fd(&c->sock);
 451                                 channel_free(c);
 452                                 break;
 453                         }
 454                 }
 455         }
 456 }
 457
 458 /*
 459  * Returns true if no channel has too much buffered data, and false if one or
 460  * more channel is overfull.
 461  */
 462 int
 463 channel_not_very_much_buffered_data(void)
 464 {
 465         u_int i;
 466         Channel *c;
 467
 468         for (i = 0; i < channels_alloc; i++) {
 469                 c = channels[i];
 470                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 471 #if 0
 472                         if (!compat20 &&
 473                             buffer_len(&c->input) > packet_get_maxsize()) {
 474                                 debug2("channel %d: big input buffer %d",
 475                                     c->self, buffer_len(&c->input));
 476                                 return 0;
 477                         }
 478 #endif
 479                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 480                                 debug2("channel %d: big output buffer %u > %u",
 481                                     c->self, buffer_len(&c->output),
 482                                     packet_get_maxsize());
 483                                 return 0;
 484                         }
 485                 }
 486         }
 487         return 1;
 488 }
 489
 490 /* Returns true if any channel is still open. */
 491 int
 492 channel_still_open(void)
 493 {
 494         u_int i;
 495         Channel *c;
 496
 497         for (i = 0; i < channels_alloc; i++) {
 498                 c = channels[i];
 499                 if (c == NULL)
 500                         continue;
 501                 switch (c->type) {
 502                 case SSH_CHANNEL_X11_LISTENER:
 503                 case SSH_CHANNEL_PORT_LISTENER:
 504                 case SSH_CHANNEL_RPORT_LISTENER:
 505                 case SSH_CHANNEL_CLOSED:
 506                 case SSH_CHANNEL_AUTH_SOCKET:
 507                 case SSH_CHANNEL_DYNAMIC:
 508                 case SSH_CHANNEL_CONNECTING:
 509                 case SSH_CHANNEL_ZOMBIE:
 510                         continue;
 511                 case SSH_CHANNEL_LARVAL:
 512                         if (!compat20)
 513                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 514                         continue;
 515                 case SSH_CHANNEL_OPENING:
 516                 case SSH_CHANNEL_OPEN:
 517                 case SSH_CHANNEL_X11_OPEN:
 518                         return 1;
 519                 case SSH_CHANNEL_INPUT_DRAINING:
 520                 case SSH_CHANNEL_OUTPUT_DRAINING:
 521                         if (!compat13)
 522                                 fatal("cannot happen: OUT_DRAIN");
 523                         return 1;
 524                 default:
 525                         fatal("channel_still_open: bad channel type %d", c->type);
 526                         /* NOTREACHED */
 527                 }
 528         }
 529         return 0;
 530 }
 531
 532 /* Returns the id of an open channel suitable for keepaliving */
 533 int
 534 channel_find_open(void)
 535 {
 536         u_int i;
 537         Channel *c;
 538
 539         for (i = 0; i < channels_alloc; i++) {
 540                 c = channels[i];
 541                 if (c == NULL || c->remote_id < 0)
 542                         continue;
 543                 switch (c->type) {
 544                 case SSH_CHANNEL_CLOSED:
 545                 case SSH_CHANNEL_DYNAMIC:
 546                 case SSH_CHANNEL_X11_LISTENER:
 547                 case SSH_CHANNEL_PORT_LISTENER:
 548                 case SSH_CHANNEL_RPORT_LISTENER:
 549                 case SSH_CHANNEL_OPENING:
 550                 case SSH_CHANNEL_CONNECTING:
 551                 case SSH_CHANNEL_ZOMBIE:
 552                         continue;
 553                 case SSH_CHANNEL_LARVAL:
 554                 case SSH_CHANNEL_AUTH_SOCKET:
 555                 case SSH_CHANNEL_OPEN:
 556                 case SSH_CHANNEL_X11_OPEN:
 557                         return i;
 558                 case SSH_CHANNEL_INPUT_DRAINING:
 559                 case SSH_CHANNEL_OUTPUT_DRAINING:
 560                         if (!compat13)
 561                                 fatal("cannot happen: OUT_DRAIN");
 562                         return i;
 563                 default:
 564                         fatal("channel_find_open: bad channel type %d", c->type);
 565                         /* NOTREACHED */
 566                 }
 567         }
 568         return -1;
 569 }
 570
 571
 572 /*
 573  * Returns a message describing the currently open forwarded connections,
 574  * suitable for sending to the client.  The message contains crlf pairs for
 575  * newlines.
 576  */
 577 char *
 578 channel_open_message(void)
 579 {
 580         Buffer buffer;
 581         Channel *c;
 582         char buf[1024], *cp;
 583         u_int i;
 584
 585         buffer_init(&buffer);
 586         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 587         buffer_append(&buffer, buf, strlen(buf));
 588         for (i = 0; i < channels_alloc; i++) {
 589                 c = channels[i];
 590                 if (c == NULL)
 591                         continue;
 592                 switch (c->type) {
 593                 case SSH_CHANNEL_X11_LISTENER:
 594                 case SSH_CHANNEL_PORT_LISTENER:
 595                 case SSH_CHANNEL_RPORT_LISTENER:
 596                 case SSH_CHANNEL_CLOSED:
 597                 case SSH_CHANNEL_AUTH_SOCKET:
 598                 case SSH_CHANNEL_ZOMBIE:
 599                         continue;
 600                 case SSH_CHANNEL_LARVAL:
 601                 case SSH_CHANNEL_OPENING:
 602                 case SSH_CHANNEL_CONNECTING:
 603                 case SSH_CHANNEL_DYNAMIC:
 604                 case SSH_CHANNEL_OPEN:
 605                 case SSH_CHANNEL_X11_OPEN:
 606                 case SSH_CHANNEL_INPUT_DRAINING:
 607                 case SSH_CHANNEL_OUTPUT_DRAINING:
 608                         snprintf(buf, sizeof buf,
 609                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 610                             c->self, c->remote_name,
 611                             c->type, c->remote_id,
 612                             c->istate, buffer_len(&c->input),
 613                             c->ostate, buffer_len(&c->output),
 614                             c->rfd, c->wfd, c->ctl_fd);
 615                         buffer_append(&buffer, buf, strlen(buf));
 616                         continue;
 617                 default:
 618                         fatal("channel_open_message: bad channel type %d", c->type);
 619                         /* NOTREACHED */
 620                 }
 621         }
 622         buffer_append(&buffer, "\0", 1);
 623         cp = xstrdup(buffer_ptr(&buffer));
 624         buffer_free(&buffer);
 625         return cp;
 626 }
 627
 628 void
 629 channel_send_open(int id)
 630 {
 631         Channel *c = channel_lookup(id);
 632
 633         if (c == NULL) {
 634                 logit("channel_send_open: %d: bad id", id);
 635                 return;
 636         }
 637         debug2("channel %d: send open", id);
 638         packet_start(SSH2_MSG_CHANNEL_OPEN);
 639         packet_put_cstring(c->ctype);
 640         packet_put_int(c->self);
 641         packet_put_int(c->local_window);
 642         packet_put_int(c->local_maxpacket);
 643         packet_send();
 644 }
 645
 646 void
 647 channel_request_start(int id, char *service, int wantconfirm)
 648 {
 649         Channel *c = channel_lookup(id);
 650
 651         if (c == NULL) {
 652                 logit("channel_request_start: %d: unknown channel id", id);
 653                 return;
 654         }
 655         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 656         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 657         packet_put_int(c->remote_id);
 658         packet_put_cstring(service);
 659         packet_put_char(wantconfirm);
 660 }
 661
 662 void
 663 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 664 {
 665         Channel *c = channel_lookup(id);
 666
 667         if (c == NULL) {
 668                 logit("channel_register_comfirm: %d: bad id", id);
 669                 return;
 670         }
 671         c->confirm = fn;
 672         c->confirm_ctx = ctx;
 673 }
 674
 675 void
 676 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 677 {
 678         Channel *c = channel_by_id(id);
 679
 680         if (c == NULL) {
 681                 logit("channel_register_cleanup: %d: bad id", id);
 682                 return;
 683         }
 684         c->detach_user = fn;
 685         c->detach_close = do_close;
 686 }
 687
 688 void
 689 channel_cancel_cleanup(int id)
 690 {
 691         Channel *c = channel_by_id(id);
 692
 693         if (c == NULL) {
 694                 logit("channel_cancel_cleanup: %d: bad id", id);
 695                 return;
 696         }
 697         c->detach_user = NULL;
 698         c->detach_close = 0;
 699 }
 700
 701 void
 702 channel_register_filter(int id, channel_infilter_fn *ifn,
 703     channel_outfilter_fn *ofn)
 704 {
 705         Channel *c = channel_lookup(id);
 706
 707         if (c == NULL) {
 708                 logit("channel_register_filter: %d: bad id", id);
 709                 return;
 710         }
 711         c->input_filter = ifn;
 712         c->output_filter = ofn;
 713 }
 714
 715 void
 716 channel_set_fds(int id, int rfd, int wfd, int efd,
 717     int extusage, int nonblock, u_int window_max)
 718 {
 719         Channel *c = channel_lookup(id);
 720
 721         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 722                 fatal("channel_activate for non-larval channel %d.", id);
 723         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 724         c->type = SSH_CHANNEL_OPEN;
 725         c->local_window = c->local_window_max = window_max;
 726         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 727         packet_put_int(c->remote_id);
 728         packet_put_int(c->local_window);
 729         packet_send();
 730 }
 731
 732 /*
 733  * 'channel_pre*' are called just before select() to add any bits relevant to
 734  * channels in the select bitmasks.
 735  */
 736 /*
 737  * 'channel_post*': perform any appropriate operations for channels which
 738  * have events pending.
 739  */
 740 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 741 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 742 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 743
 744 /* ARGSUSED */
 745 static void
 746 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 747 {
 748         FD_SET(c->sock, readset);
 749 }
 750
 751 /* ARGSUSED */
 752 static void
 753 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 754 {
 755         debug3("channel %d: waiting for connection", c->self);
 756         FD_SET(c->sock, writeset);
 757 }
 758
 759 static void
 760 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 761 {
 762         if (buffer_len(&c->input) < packet_get_maxsize())
 763                 FD_SET(c->sock, readset);
 764         if (buffer_len(&c->output) > 0)
 765                 FD_SET(c->sock, writeset);
 766 }
 767
 768 static void
 769 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 770 {
 771         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 772
 773         if (c->istate == CHAN_INPUT_OPEN &&
 774             limit > 0 &&
 775             buffer_len(&c->input) < limit &&
 776             buffer_check_alloc(&c->input, CHAN_RBUF))
 777                 FD_SET(c->rfd, readset);
 778         if (c->ostate == CHAN_OUTPUT_OPEN ||
 779             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 780                 if (buffer_len(&c->output) > 0) {
 781                         FD_SET(c->wfd, writeset);
 782                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 783                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 784                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 785                                     c->self, c->efd, buffer_len(&c->extended));
 786                         else
 787                                 chan_obuf_empty(c);
 788                 }
 789         }
 790         /** XXX check close conditions, too */
 791         if (compat20 && c->efd != -1) {
 792                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 793                     buffer_len(&c->extended) > 0)
 794                         FD_SET(c->efd, writeset);
 795                 else if (!(c->flags & CHAN_EOF_SENT) &&
 796                     c->extended_usage == CHAN_EXTENDED_READ &&
 797                     buffer_len(&c->extended) < c->remote_window)
 798                         FD_SET(c->efd, readset);
 799         }
 800         /* XXX: What about efd? races? */
 801         if (compat20 && c->ctl_fd != -1 &&
 802             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 803                 FD_SET(c->ctl_fd, readset);
 804 }
 805
 806 /* ARGSUSED */
 807 static void
 808 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 809 {
 810         if (buffer_len(&c->input) == 0) {
 811                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 812                 packet_put_int(c->remote_id);
 813                 packet_send();
 814                 c->type = SSH_CHANNEL_CLOSED;
 815                 debug2("channel %d: closing after input drain.", c->self);
 816         }
 817 }
 818
 819 /* ARGSUSED */
 820 static void
 821 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 822 {
 823         if (buffer_len(&c->output) == 0)
 824                 chan_mark_dead(c);
 825         else
 826                 FD_SET(c->sock, writeset);
 827 }
 828
 829 /*
 830  * This is a special state for X11 authentication spoofing.  An opened X11
 831  * connection (when authentication spoofing is being done) remains in this
 832  * state until the first packet has been completely read.  The authentication
 833  * data in that packet is then substituted by the real data if it matches the
 834  * fake data, and the channel is put into normal mode.
 835  * XXX All this happens at the client side.
 836  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 837  */
 838 static int
 839 x11_open_helper(Buffer *b)
 840 {
 841         u_char *ucp;
 842         u_int proto_len, data_len;
 843
 844         /* Check if the fixed size part of the packet is in buffer. */
 845         if (buffer_len(b) < 12)
 846                 return 0;
 847
 848         /* Parse the lengths of variable-length fields. */
 849         ucp = buffer_ptr(b);
 850         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 851                 proto_len = 256 * ucp[6] + ucp[7];
 852                 data_len = 256 * ucp[8] + ucp[9];
 853         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 854                 proto_len = ucp[6] + 256 * ucp[7];
 855                 data_len = ucp[8] + 256 * ucp[9];
 856         } else {
 857                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 858                     ucp[0]);
 859                 return -1;
 860         }
 861
 862         /* Check if the whole packet is in buffer. */
 863         if (buffer_len(b) <
 864             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 865                 return 0;
 866
 867         /* Check if authentication protocol matches. */
 868         if (proto_len != strlen(x11_saved_proto) ||
 869             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 870                 debug2("X11 connection uses different authentication protocol.");
 871                 return -1;
 872         }
 873         /* Check if authentication data matches our fake data. */
 874         if (data_len != x11_fake_data_len ||
 875             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 876                 x11_fake_data, x11_fake_data_len) != 0) {
 877                 debug2("X11 auth data does not match fake data.");
 878                 return -1;
 879         }
 880         /* Check fake data length */
 881         if (x11_fake_data_len != x11_saved_data_len) {
 882                 error("X11 fake_data_len %d != saved_data_len %d",
 883                     x11_fake_data_len, x11_saved_data_len);
 884                 return -1;
 885         }
 886         /*
 887          * Received authentication protocol and data match
 888          * our fake data. Substitute the fake data with real
 889          * data.
 890          */
 891         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 892             x11_saved_data, x11_saved_data_len);
 893         return 1;
 894 }
 895
 896 static void
 897 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 898 {
 899         int ret = x11_open_helper(&c->output);
 900
 901         if (ret == 1) {
 902                 /* Start normal processing for the channel. */
 903                 c->type = SSH_CHANNEL_OPEN;
 904                 channel_pre_open_13(c, readset, writeset);
 905         } else if (ret == -1) {
 906                 /*
 907                  * We have received an X11 connection that has bad
 908                  * authentication information.
 909                  */
 910                 logit("X11 connection rejected because of wrong authentication.");
 911                 buffer_clear(&c->input);
 912                 buffer_clear(&c->output);
 913                 channel_close_fd(&c->sock);
 914                 c->sock = -1;
 915                 c->type = SSH_CHANNEL_CLOSED;
 916                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 917                 packet_put_int(c->remote_id);
 918                 packet_send();
 919         }
 920 }
 921
 922 static void
 923 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 924 {
 925         int ret = x11_open_helper(&c->output);
 926
 927         /* c->force_drain = 1; */
 928
 929         if (ret == 1) {
 930                 c->type = SSH_CHANNEL_OPEN;
 931                 channel_pre_open(c, readset, writeset);
 932         } else if (ret == -1) {
 933                 logit("X11 connection rejected because of wrong authentication.");
 934                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 935                 chan_read_failed(c);
 936                 buffer_clear(&c->input);
 937                 chan_ibuf_empty(c);
 938                 buffer_clear(&c->output);
 939                 /* for proto v1, the peer will send an IEOF */
 940                 if (compat20)
 941                         chan_write_failed(c);
 942                 else
 943                         c->type = SSH_CHANNEL_OPEN;
 944                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 945         }
 946 }
 947
 948 /* try to decode a socks4 header */
 949 /* ARGSUSED */
 950 static int
 951 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 952 {
 953         char *p, *host;
 954         u_int len, have, i, found;
 955         char username[256];
 956         struct {
 957                 u_int8_t version;
 958                 u_int8_t command;
 959                 u_int16_t dest_port;
 960                 struct in_addr dest_addr;
 961         } s4_req, s4_rsp;
 962
 963         debug2("channel %d: decode socks4", c->self);
 964
 965         have = buffer_len(&c->input);
 966         len = sizeof(s4_req);
 967         if (have < len)
 968                 return 0;
 969         p = buffer_ptr(&c->input);
 970         for (found = 0, i = len; i < have; i++) {
 971                 if (p[i] == '\0') {
 972                         found = 1;
 973                         break;
 974                 }
 975                 if (i > 1024) {
 976                         /* the peer is probably sending garbage */
 977                         debug("channel %d: decode socks4: too long",
 978                             c->self);
 979                         return -1;
 980                 }
 981         }
 982         if (!found)
 983                 return 0;
 984         buffer_get(&c->input, (char *)&s4_req.version, 1);
 985         buffer_get(&c->input, (char *)&s4_req.command, 1);
 986         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 987         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 988         have = buffer_len(&c->input);
 989         p = buffer_ptr(&c->input);
 990         len = strlen(p);
 991         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 992         if (len > have)
 993                 fatal("channel %d: decode socks4: len %d > have %d",
 994                     c->self, len, have);
 995         strlcpy(username, p, sizeof(username));
 996         buffer_consume(&c->input, len);
 997         buffer_consume(&c->input, 1);           /* trailing '\0' */
 998
 999         host = inet_ntoa(s4_req.dest_addr);
1000         strlcpy(c->path, host, sizeof(c->path));
1001         c->host_port = ntohs(s4_req.dest_port);
1002
1003         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1004             c->self, host, c->host_port, s4_req.command);
1005
1006         if (s4_req.command != 1) {
1007                 debug("channel %d: cannot handle: socks4 cn %d",
1008                     c->self, s4_req.command);
1009                 return -1;
1010         }
1011         s4_rsp.version = 0;                     /* vn: 0 for reply */
1012         s4_rsp.command = 90;                    /* cd: req granted */
1013         s4_rsp.dest_port = 0;                   /* ignored */
1014         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1015         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1016         return 1;
1017 }
1018
1019 /* try to decode a socks5 header */
1020 #define SSH_SOCKS5_AUTHDONE     0x1000
1021 #define SSH_SOCKS5_NOAUTH       0x00
1022 #define SSH_SOCKS5_IPV4         0x01
1023 #define SSH_SOCKS5_DOMAIN       0x03
1024 #define SSH_SOCKS5_IPV6         0x04
1025 #define SSH_SOCKS5_CONNECT      0x01
1026 #define SSH_SOCKS5_SUCCESS      0x00
1027
1028 /* ARGSUSED */
1029 static int
1030 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1031 {
1032         struct {
1033                 u_int8_t version;
1034                 u_int8_t command;
1035                 u_int8_t reserved;
1036                 u_int8_t atyp;
1037         } s5_req, s5_rsp;
1038         u_int16_t dest_port;
1039         u_char *p, dest_addr[255+1];
1040         u_int have, need, i, found, nmethods, addrlen, af;
1041
1042         debug2("channel %d: decode socks5", c->self);
1043         p = buffer_ptr(&c->input);
1044         if (p[0] != 0x05)
1045                 return -1;
1046         have = buffer_len(&c->input);
1047         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1048                 /* format: ver | nmethods | methods */
1049                 if (have < 2)
1050                         return 0;
1051                 nmethods = p[1];
1052                 if (have < nmethods + 2)
1053                         return 0;
1054                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1055                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1056                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1057                                 found = 1;
1058                                 break;
1059                         }
1060                 }
1061                 if (!found) {
1062                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1063                             c->self);
1064                         return -1;
1065                 }
1066                 buffer_consume(&c->input, nmethods + 2);
1067                 buffer_put_char(&c->output, 0x05);              /* version */
1068                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1069                 FD_SET(c->sock, writeset);
1070                 c->flags |= SSH_SOCKS5_AUTHDONE;
1071                 debug2("channel %d: socks5 auth done", c->self);
1072                 return 0;                               /* need more */
1073         }
1074         debug2("channel %d: socks5 post auth", c->self);
1075         if (have < sizeof(s5_req)+1)
1076                 return 0;                       /* need more */
1077         memcpy(&s5_req, p, sizeof(s5_req));
1078         if (s5_req.version != 0x05 ||
1079             s5_req.command != SSH_SOCKS5_CONNECT ||
1080             s5_req.reserved != 0x00) {
1081                 debug2("channel %d: only socks5 connect supported", c->self);
1082                 return -1;
1083         }
1084         switch (s5_req.atyp){
1085         case SSH_SOCKS5_IPV4:
1086                 addrlen = 4;
1087                 af = AF_INET;
1088                 break;
1089         case SSH_SOCKS5_DOMAIN:
1090                 addrlen = p[sizeof(s5_req)];
1091                 af = -1;
1092                 break;
1093         case SSH_SOCKS5_IPV6:
1094                 addrlen = 16;
1095                 af = AF_INET6;
1096                 break;
1097         default:
1098                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1099                 return -1;
1100         }
1101         need = sizeof(s5_req) + addrlen + 2;
1102         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1103                 need++;
1104         if (have < need)
1105                 return 0;
1106         buffer_consume(&c->input, sizeof(s5_req));
1107         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1108                 buffer_consume(&c->input, 1);    /* host string length */
1109         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1110         buffer_get(&c->input, (char *)&dest_port, 2);
1111         dest_addr[addrlen] = '\0';
1112         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1113                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1114         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1115                 return -1;
1116         c->host_port = ntohs(dest_port);
1117
1118         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1119             c->self, c->path, c->host_port, s5_req.command);
1120
1121         s5_rsp.version = 0x05;
1122         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1123         s5_rsp.reserved = 0;                    /* ignored */
1124         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1125         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1126         dest_port = 0;                          /* ignored */
1127
1128         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1129         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1130         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1131         return 1;
1132 }
1133
1134 /* dynamic port forwarding */
1135 static void
1136 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1137 {
1138         u_char *p;
1139         u_int have;
1140         int ret;
1141
1142         have = buffer_len(&c->input);
1143         c->delayed = 0;
1144         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1145         /* buffer_dump(&c->input); */
1146         /* check if the fixed size part of the packet is in buffer. */
1147         if (have < 3) {
1148                 /* need more */
1149                 FD_SET(c->sock, readset);
1150                 return;
1151         }
1152         /* try to guess the protocol */
1153         p = buffer_ptr(&c->input);
1154         switch (p[0]) {
1155         case 0x04:
1156                 ret = channel_decode_socks4(c, readset, writeset);
1157                 break;
1158         case 0x05:
1159                 ret = channel_decode_socks5(c, readset, writeset);
1160                 break;
1161         default:
1162                 ret = -1;
1163                 break;
1164         }
1165         if (ret < 0) {
1166                 chan_mark_dead(c);
1167         } else if (ret == 0) {
1168                 debug2("channel %d: pre_dynamic: need more", c->self);
1169                 /* need more */
1170                 FD_SET(c->sock, readset);
1171         } else {
1172                 /* switch to the next state */
1173                 c->type = SSH_CHANNEL_OPENING;
1174                 port_open_helper(c, "direct-tcpip");
1175         }
1176 }
1177
1178 /* This is our fake X11 server socket. */
1179 /* ARGSUSED */
1180 static void
1181 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1182 {
1183         Channel *nc;
1184         struct sockaddr addr;
1185         int newsock;
1186         socklen_t addrlen;
1187         char buf[16384], *remote_ipaddr;
1188         int remote_port;
1189
1190         if (FD_ISSET(c->sock, readset)) {
1191                 debug("X11 connection requested.");
1192                 addrlen = sizeof(addr);
1193                 newsock = accept(c->sock, &addr, &addrlen);
1194                 if (c->single_connection) {
1195                         debug2("single_connection: closing X11 listener.");
1196                         channel_close_fd(&c->sock);
1197                         chan_mark_dead(c);
1198                 }
1199                 if (newsock < 0) {
1200                         error("accept: %.100s", strerror(errno));
1201                         return;
1202                 }
1203                 set_nodelay(newsock);
1204                 remote_ipaddr = get_peer_ipaddr(newsock);
1205                 remote_port = get_peer_port(newsock);
1206                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1207                     remote_ipaddr, remote_port);
1208
1209                 nc = channel_new("accepted x11 socket",
1210                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1211                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1212                 if (compat20) {
1213                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1214                         packet_put_cstring("x11");
1215                         packet_put_int(nc->self);
1216                         packet_put_int(nc->local_window_max);
1217                         packet_put_int(nc->local_maxpacket);
1218                         /* originator ipaddr and port */
1219                         packet_put_cstring(remote_ipaddr);
1220                         if (datafellows & SSH_BUG_X11FWD) {
1221                                 debug2("ssh2 x11 bug compat mode");
1222                         } else {
1223                                 packet_put_int(remote_port);
1224                         }
1225                         packet_send();
1226                 } else {
1227                         packet_start(SSH_SMSG_X11_OPEN);
1228                         packet_put_int(nc->self);
1229                         if (packet_get_protocol_flags() &
1230                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1231                                 packet_put_cstring(buf);
1232                         packet_send();
1233                 }
1234                 xfree(remote_ipaddr);
1235         }
1236 }
1237
1238 static void
1239 port_open_helper(Channel *c, char *rtype)
1240 {
1241         int direct;
1242         char buf[1024];
1243         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1244         int remote_port = get_peer_port(c->sock);
1245
1246         direct = (strcmp(rtype, "direct-tcpip") == 0);
1247
1248         snprintf(buf, sizeof buf,
1249             "%s: listening port %d for %.100s port %d, "
1250             "connect from %.200s port %d",
1251             rtype, c->listening_port, c->path, c->host_port,
1252             remote_ipaddr, remote_port);
1253
1254         xfree(c->remote_name);
1255         c->remote_name = xstrdup(buf);
1256
1257         if (compat20) {
1258                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1259                 packet_put_cstring(rtype);
1260                 packet_put_int(c->self);
1261                 packet_put_int(c->local_window_max);
1262                 packet_put_int(c->local_maxpacket);
1263                 if (direct) {
1264                         /* target host, port */
1265                         packet_put_cstring(c->path);
1266                         packet_put_int(c->host_port);
1267                 } else {
1268                         /* listen address, port */
1269                         packet_put_cstring(c->path);
1270                         packet_put_int(c->listening_port);
1271                 }
1272                 /* originator host and port */
1273                 packet_put_cstring(remote_ipaddr);
1274                 packet_put_int((u_int)remote_port);
1275                 packet_send();
1276         } else {
1277                 packet_start(SSH_MSG_PORT_OPEN);
1278                 packet_put_int(c->self);
1279                 packet_put_cstring(c->path);
1280                 packet_put_int(c->host_port);
1281                 if (packet_get_protocol_flags() &
1282                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1283                         packet_put_cstring(c->remote_name);
1284                 packet_send();
1285         }
1286         xfree(remote_ipaddr);
1287 }
1288
1289 static void
1290 channel_set_reuseaddr(int fd)
1291 {
1292         int on = 1;
1293
1294         /*
1295          * Set socket options.
1296          * Allow local port reuse in TIME_WAIT.
1297          */
1298         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1299                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1300 }
1301
1302 /*
1303  * This socket is listening for connections to a forwarded TCP/IP port.
1304  */
1305 /* ARGSUSED */
1306 static void
1307 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1308 {
1309         Channel *nc;
1310         struct sockaddr addr;
1311         int newsock, nextstate;
1312         socklen_t addrlen;
1313         char *rtype;
1314
1315         if (FD_ISSET(c->sock, readset)) {
1316                 debug("Connection to port %d forwarding "
1317                     "to %.100s port %d requested.",
1318                     c->listening_port, c->path, c->host_port);
1319
1320                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1321                         nextstate = SSH_CHANNEL_OPENING;
1322                         rtype = "forwarded-tcpip";
1323                 } else {
1324                         if (c->host_port == 0) {
1325                                 nextstate = SSH_CHANNEL_DYNAMIC;
1326                                 rtype = "dynamic-tcpip";
1327                         } else {
1328                                 nextstate = SSH_CHANNEL_OPENING;
1329                                 rtype = "direct-tcpip";
1330                         }
1331                 }
1332
1333                 addrlen = sizeof(addr);
1334                 newsock = accept(c->sock, &addr, &addrlen);
1335                 if (newsock < 0) {
1336                         error("accept: %.100s", strerror(errno));
1337                         return;
1338                 }
1339                 set_nodelay(newsock);
1340                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1341                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1342                 nc->listening_port = c->listening_port;
1343                 nc->host_port = c->host_port;
1344                 strlcpy(nc->path, c->path, sizeof(nc->path));
1345
1346                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1347                         /*
1348                          * do not call the channel_post handler until
1349                          * this flag has been reset by a pre-handler.
1350                          * otherwise the FD_ISSET calls might overflow
1351                          */
1352                         nc->delayed = 1;
1353                 } else {
1354                         port_open_helper(nc, rtype);
1355                 }
1356         }
1357 }
1358
1359 /*
1360  * This is the authentication agent socket listening for connections from
1361  * clients.
1362  */
1363 /* ARGSUSED */
1364 static void
1365 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1366 {
1367         Channel *nc;
1368         int newsock;
1369         struct sockaddr addr;
1370         socklen_t addrlen;
1371
1372         if (FD_ISSET(c->sock, readset)) {
1373                 addrlen = sizeof(addr);
1374                 newsock = accept(c->sock, &addr, &addrlen);
1375                 if (newsock < 0) {
1376                         error("accept from auth socket: %.100s", strerror(errno));
1377                         return;
1378                 }
1379                 nc = channel_new("accepted auth socket",
1380                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1381                     c->local_window_max, c->local_maxpacket,
1382                     0, "accepted auth socket", 1);
1383                 if (compat20) {
1384                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1385                         packet_put_cstring("auth-agent@openssh.com");
1386                         packet_put_int(nc->self);
1387                         packet_put_int(c->local_window_max);
1388                         packet_put_int(c->local_maxpacket);
1389                 } else {
1390                         packet_start(SSH_SMSG_AGENT_OPEN);
1391                         packet_put_int(nc->self);
1392                 }
1393                 packet_send();
1394         }
1395 }
1396
1397 /* ARGSUSED */
1398 static void
1399 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1400 {
1401         int err = 0;
1402         socklen_t sz = sizeof(err);
1403
1404         if (FD_ISSET(c->sock, writeset)) {
1405                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1406                         err = errno;
1407                         error("getsockopt SO_ERROR failed");
1408                 }
1409                 if (err == 0) {
1410                         debug("channel %d: connected", c->self);
1411                         c->type = SSH_CHANNEL_OPEN;
1412                         if (compat20) {
1413                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1414                                 packet_put_int(c->remote_id);
1415                                 packet_put_int(c->self);
1416                                 packet_put_int(c->local_window);
1417                                 packet_put_int(c->local_maxpacket);
1418                         } else {
1419                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1420                                 packet_put_int(c->remote_id);
1421                                 packet_put_int(c->self);
1422                         }
1423                 } else {
1424                         debug("channel %d: not connected: %s",
1425                             c->self, strerror(err));
1426                         if (compat20) {
1427                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1428                                 packet_put_int(c->remote_id);
1429                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1430                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1431                                         packet_put_cstring(strerror(err));
1432                                         packet_put_cstring("");
1433                                 }
1434                         } else {
1435                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1436                                 packet_put_int(c->remote_id);
1437                         }
1438                         chan_mark_dead(c);
1439                 }
1440                 packet_send();
1441         }
1442 }
1443
1444 /* ARGSUSED */
1445 static int
1446 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1447 {
1448         char buf[CHAN_RBUF];
1449         int len;
1450
1451         if (c->rfd != -1 &&
1452             (c->detach_close || FD_ISSET(c->rfd, readset))) {
1453                 errno = 0;
1454                 len = read(c->rfd, buf, sizeof(buf));
1455                 if (len < 0 && (errno == EINTR ||
1456                     (errno == EAGAIN && !(c->isatty && c->detach_close))))
1457                         return 1;
1458 #ifndef PTY_ZEROREAD
1459                 if (len <= 0) {
1460 #else
1461                 if ((!c->isatty && len <= 0) ||
1462                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1463 #endif
1464                         debug2("channel %d: read<=0 rfd %d len %d",
1465                             c->self, c->rfd, len);
1466                         if (c->type != SSH_CHANNEL_OPEN) {
1467                                 debug2("channel %d: not open", c->self);
1468                                 chan_mark_dead(c);
1469                                 return -1;
1470                         } else if (compat13) {
1471                                 buffer_clear(&c->output);
1472                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1473                                 debug2("channel %d: input draining.", c->self);
1474                         } else {
1475                                 chan_read_failed(c);
1476                         }
1477                         return -1;
1478                 }
1479                 if (c->input_filter != NULL) {
1480                         if (c->input_filter(c, buf, len) == -1) {
1481                                 debug2("channel %d: filter stops", c->self);
1482                                 chan_read_failed(c);
1483                         }
1484                 } else if (c->datagram) {
1485                         buffer_put_string(&c->input, buf, len);
1486                 } else {
1487                         buffer_append(&c->input, buf, len);
1488                 }
1489         }
1490         return 1;
1491 }
1492
1493 /* ARGSUSED */
1494 static int
1495 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1496 {
1497         struct termios tio;
1498         u_char *data = NULL, *buf;
1499         u_int dlen;
1500         int len;
1501
1502         /* Send buffered output data to the socket. */
1503         if (c->wfd != -1 &&
1504             FD_ISSET(c->wfd, writeset) &&
1505             buffer_len(&c->output) > 0) {
1506                 if (c->output_filter != NULL) {
1507                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1508                                 debug2("channel %d: filter stops", c->self);
1509                                 if (c->type != SSH_CHANNEL_OPEN)
1510                                         chan_mark_dead(c);
1511                                 else
1512                                         chan_write_failed(c);
1513                                 return -1;
1514                         }
1515                 } else if (c->datagram) {
1516                         buf = data = buffer_get_string(&c->output, &dlen);
1517                 } else {
1518                         buf = data = buffer_ptr(&c->output);
1519                         dlen = buffer_len(&c->output);
1520                 }
1521
1522                 if (c->datagram) {
1523                         /* ignore truncated writes, datagrams might get lost */
1524                         c->local_consumed += dlen + 4;
1525                         len = write(c->wfd, buf, dlen);
1526                         xfree(data);
1527                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1528                                 return 1;
1529                         if (len <= 0) {
1530                                 if (c->type != SSH_CHANNEL_OPEN)
1531                                         chan_mark_dead(c);
1532                                 else
1533                                         chan_write_failed(c);
1534                                 return -1;
1535                         }
1536                         return 1;
1537                 }
1538 #ifdef _AIX
1539                 /* XXX: Later AIX versions can't push as much data to tty */
1540                 if (compat20 && c->wfd_isatty)
1541                         dlen = MIN(dlen, 8*1024);
1542 #endif
1543
1544                 len = write(c->wfd, buf, dlen);
1545                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1546                         return 1;
1547                 if (len <= 0) {
1548                         if (c->type != SSH_CHANNEL_OPEN) {
1549                                 debug2("channel %d: not open", c->self);
1550                                 chan_mark_dead(c);
1551                                 return -1;
1552                         } else if (compat13) {
1553                                 buffer_clear(&c->output);
1554                                 debug2("channel %d: input draining.", c->self);
1555                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1556                         } else {
1557                                 chan_write_failed(c);
1558                         }
1559                         return -1;
1560                 }
1561                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1562                         if (tcgetattr(c->wfd, &tio) == 0 &&
1563                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1564                                 /*
1565                                  * Simulate echo to reduce the impact of
1566                                  * traffic analysis. We need to match the
1567                                  * size of a SSH2_MSG_CHANNEL_DATA message
1568                                  * (4 byte channel id + buf)
1569                                  */
1570                                 packet_send_ignore(4 + len);
1571                                 packet_send();
1572                         }
1573                 }
1574                 buffer_consume(&c->output, len);
1575                 if (compat20 && len > 0) {
1576                         c->local_consumed += len;
1577                 }
1578         }
1579         return 1;
1580 }
1581
1582 static int
1583 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1584 {
1585         char buf[CHAN_RBUF];
1586         int len;
1587
1588 /** XXX handle drain efd, too */
1589         if (c->efd != -1) {
1590                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1591                     FD_ISSET(c->efd, writeset) &&
1592                     buffer_len(&c->extended) > 0) {
1593                         len = write(c->efd, buffer_ptr(&c->extended),
1594                             buffer_len(&c->extended));
1595                         debug2("channel %d: written %d to efd %d",
1596                             c->self, len, c->efd);
1597                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1598                                 return 1;
1599                         if (len <= 0) {
1600                                 debug2("channel %d: closing write-efd %d",
1601                                     c->self, c->efd);
1602                                 channel_close_fd(&c->efd);
1603                         } else {
1604                                 buffer_consume(&c->extended, len);
1605                                 c->local_consumed += len;
1606                         }
1607                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1608                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1609                         len = read(c->efd, buf, sizeof(buf));
1610                         debug2("channel %d: read %d from efd %d",
1611                             c->self, len, c->efd);
1612                         if (len < 0 && (errno == EINTR ||
1613                             (errno == EAGAIN && !c->detach_close)))
1614                                 return 1;
1615                         if (len <= 0) {
1616                                 debug2("channel %d: closing read-efd %d",
1617                                     c->self, c->efd);
1618                                 channel_close_fd(&c->efd);
1619                         } else {
1620                                 buffer_append(&c->extended, buf, len);
1621                         }
1622                 }
1623         }
1624         return 1;
1625 }
1626
1627 /* ARGSUSED */
1628 static int
1629 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1630 {
1631         char buf[16];
1632         int len;
1633
1634         /* Monitor control fd to detect if the slave client exits */
1635         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1636                 len = read(c->ctl_fd, buf, sizeof(buf));
1637                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1638                         return 1;
1639                 if (len <= 0) {
1640                         debug2("channel %d: ctl read<=0", c->self);
1641                         if (c->type != SSH_CHANNEL_OPEN) {
1642                                 debug2("channel %d: not open", c->self);
1643                                 chan_mark_dead(c);
1644                                 return -1;
1645                         } else {
1646                                 chan_read_failed(c);
1647                                 chan_write_failed(c);
1648                         }
1649                         return -1;
1650                 } else
1651                         fatal("%s: unexpected data on ctl fd", __func__);
1652         }
1653         return 1;
1654 }
1655
1656 static int
1657 channel_check_window(Channel *c)
1658 {
1659         if (c->type == SSH_CHANNEL_OPEN &&
1660             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1661             c->local_window < c->local_window_max/2 &&
1662             c->local_consumed > 0) {
1663                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1664                 packet_put_int(c->remote_id);
1665                 packet_put_int(c->local_consumed);
1666                 packet_send();
1667                 debug2("channel %d: window %d sent adjust %d",
1668                     c->self, c->local_window,
1669                     c->local_consumed);
1670                 c->local_window += c->local_consumed;
1671                 c->local_consumed = 0;
1672         }
1673         return 1;
1674 }
1675
1676 static void
1677 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1678 {
1679         if (c->delayed)
1680                 return;
1681         channel_handle_rfd(c, readset, writeset);
1682         channel_handle_wfd(c, readset, writeset);
1683         if (!compat20)
1684                 return;
1685         channel_handle_efd(c, readset, writeset);
1686         channel_handle_ctl(c, readset, writeset);
1687         channel_check_window(c);
1688 }
1689
1690 /* ARGSUSED */
1691 static void
1692 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1693 {
1694         int len;
1695
1696         /* Send buffered output data to the socket. */
1697         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1698                 len = write(c->sock, buffer_ptr(&c->output),
1699                             buffer_len(&c->output));
1700                 if (len <= 0)
1701                         buffer_clear(&c->output);
1702                 else
1703                         buffer_consume(&c->output, len);
1704         }
1705 }
1706
1707 static void
1708 channel_handler_init_20(void)
1709 {
1710         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1711         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1712         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1713         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1714         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1715         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1716         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1717         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1718
1719         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1720         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1721         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1722         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1723         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1724         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1725         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1726 }
1727
1728 static void
1729 channel_handler_init_13(void)
1730 {
1731         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1732         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1733         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1734         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1735         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1736         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1737         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1738         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1739         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1740
1741         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1742         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1743         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1744         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1745         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1746         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1747         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1748 }
1749
1750 static void
1751 channel_handler_init_15(void)
1752 {
1753         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1754         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1755         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1756         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1757         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1758         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1759         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1760
1761         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1762         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1763         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1764         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1765         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1766         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1767 }
1768
1769 static void
1770 channel_handler_init(void)
1771 {
1772         int i;
1773
1774         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1775                 channel_pre[i] = NULL;
1776                 channel_post[i] = NULL;
1777         }
1778         if (compat20)
1779                 channel_handler_init_20();
1780         else if (compat13)
1781                 channel_handler_init_13();
1782         else
1783                 channel_handler_init_15();
1784 }
1785
1786 /* gc dead channels */
1787 static void
1788 channel_garbage_collect(Channel *c)
1789 {
1790         if (c == NULL)
1791                 return;
1792         if (c->detach_user != NULL) {
1793                 if (!chan_is_dead(c, c->detach_close))
1794                         return;
1795                 debug2("channel %d: gc: notify user", c->self);
1796                 c->detach_user(c->self, NULL);
1797                 /* if we still have a callback */
1798                 if (c->detach_user != NULL)
1799                         return;
1800                 debug2("channel %d: gc: user detached", c->self);
1801         }
1802         if (!chan_is_dead(c, 1))
1803                 return;
1804         debug2("channel %d: garbage collecting", c->self);
1805         channel_free(c);
1806 }
1807
1808 static void
1809 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1810 {
1811         static int did_init = 0;
1812         u_int i;
1813         Channel *c;
1814
1815         if (!did_init) {
1816                 channel_handler_init();
1817                 did_init = 1;
1818         }
1819         for (i = 0; i < channels_alloc; i++) {
1820                 c = channels[i];
1821                 if (c == NULL)
1822                         continue;
1823                 if (ftab[c->type] != NULL)
1824                         (*ftab[c->type])(c, readset, writeset);
1825                 channel_garbage_collect(c);
1826         }
1827 }
1828
1829 /*
1830  * Allocate/update select bitmasks and add any bits relevant to channels in
1831  * select bitmasks.
1832  */
1833 void
1834 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1835     u_int *nallocp, int rekeying)
1836 {
1837         u_int n, sz, nfdset;
1838
1839         n = MAX(*maxfdp, channel_max_fd);
1840
1841         nfdset = howmany(n+1, NFDBITS);
1842         /* Explicitly test here, because xrealloc isn't always called */
1843         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1844                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1845         sz = nfdset * sizeof(fd_mask);
1846
1847         /* perhaps check sz < nalloc/2 and shrink? */
1848         if (*readsetp == NULL || sz > *nallocp) {
1849                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1850                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1851                 *nallocp = sz;
1852         }
1853         *maxfdp = n;
1854         memset(*readsetp, 0, sz);
1855         memset(*writesetp, 0, sz);
1856
1857         if (!rekeying)
1858                 channel_handler(channel_pre, *readsetp, *writesetp);
1859 }
1860
1861 /*
1862  * After select, perform any appropriate operations for channels which have
1863  * events pending.
1864  */
1865 void
1866 channel_after_select(fd_set *readset, fd_set *writeset)
1867 {
1868         channel_handler(channel_post, readset, writeset);
1869 }
1870
1871
1872 /* If there is data to send to the connection, enqueue some of it now. */
1873 void
1874 channel_output_poll(void)
1875 {
1876         Channel *c;
1877         u_int i, len;
1878
1879         for (i = 0; i < channels_alloc; i++) {
1880                 c = channels[i];
1881                 if (c == NULL)
1882                         continue;
1883
1884                 /*
1885                  * We are only interested in channels that can have buffered
1886                  * incoming data.
1887                  */
1888                 if (compat13) {
1889                         if (c->type != SSH_CHANNEL_OPEN &&
1890                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1891                                 continue;
1892                 } else {
1893                         if (c->type != SSH_CHANNEL_OPEN)
1894                                 continue;
1895                 }
1896                 if (compat20 &&
1897                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1898                         /* XXX is this true? */
1899                         debug3("channel %d: will not send data after close", c->self);
1900                         continue;
1901                 }
1902
1903                 /* Get the amount of buffered data for this channel. */
1904                 if ((c->istate == CHAN_INPUT_OPEN ||
1905                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1906                     (len = buffer_len(&c->input)) > 0) {
1907                         if (c->datagram) {
1908                                 if (len > 0) {
1909                                         u_char *data;
1910                                         u_int dlen;
1911
1912                                         data = buffer_get_string(&c->input,
1913                                             &dlen);
1914                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1915                                         packet_put_int(c->remote_id);
1916                                         packet_put_string(data, dlen);
1917                                         packet_send();
1918                                         c->remote_window -= dlen + 4;
1919                                         xfree(data);
1920                                 }
1921                                 continue;
1922                         }
1923                         /*
1924                          * Send some data for the other side over the secure
1925                          * connection.
1926                          */
1927                         if (compat20) {
1928                                 if (len > c->remote_window)
1929                                         len = c->remote_window;
1930                                 if (len > c->remote_maxpacket)
1931                                         len = c->remote_maxpacket;
1932                         } else {
1933                                 if (packet_is_interactive()) {
1934                                         if (len > 1024)
1935                                                 len = 512;
1936                                 } else {
1937                                         /* Keep the packets at reasonable size. */
1938                                         if (len > packet_get_maxsize()/2)
1939                                                 len = packet_get_maxsize()/2;
1940                                 }
1941                         }
1942                         if (len > 0) {
1943                                 packet_start(compat20 ?
1944                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1945                                 packet_put_int(c->remote_id);
1946                                 packet_put_string(buffer_ptr(&c->input), len);
1947                                 packet_send();
1948                                 buffer_consume(&c->input, len);
1949                                 c->remote_window -= len;
1950                         }
1951                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1952                         if (compat13)
1953                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1954                         /*
1955                          * input-buffer is empty and read-socket shutdown:
1956                          * tell peer, that we will not send more data: send IEOF.
1957                          * hack for extended data: delay EOF if EFD still in use.
1958                          */
1959                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1960                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1961                                     c->self, c->efd, buffer_len(&c->extended));
1962                         else
1963                                 chan_ibuf_empty(c);
1964                 }
1965                 /* Send extended data, i.e. stderr */
1966                 if (compat20 &&
1967                     !(c->flags & CHAN_EOF_SENT) &&
1968                     c->remote_window > 0 &&
1969                     (len = buffer_len(&c->extended)) > 0 &&
1970                     c->extended_usage == CHAN_EXTENDED_READ) {
1971                         debug2("channel %d: rwin %u elen %u euse %d",
1972                             c->self, c->remote_window, buffer_len(&c->extended),
1973                             c->extended_usage);
1974                         if (len > c->remote_window)
1975                                 len = c->remote_window;
1976                         if (len > c->remote_maxpacket)
1977                                 len = c->remote_maxpacket;
1978                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1979                         packet_put_int(c->remote_id);
1980                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1981                         packet_put_string(buffer_ptr(&c->extended), len);
1982                         packet_send();
1983                         buffer_consume(&c->extended, len);
1984                         c->remote_window -= len;
1985                         debug2("channel %d: sent ext data %d", c->self, len);
1986                 }
1987         }
1988 }
1989
1990
1991 /* -- protocol input */
1992
1993 /* ARGSUSED */
1994 void
1995 channel_input_data(int type, u_int32_t seq, void *ctxt)
1996 {
1997         int id;
1998         char *data;
1999         u_int data_len;
2000         Channel *c;
2001
2002         /* Get the channel number and verify it. */
2003         id = packet_get_int();
2004         c = channel_lookup(id);
2005         if (c == NULL)
2006                 packet_disconnect("Received data for nonexistent channel %d.", id);
2007
2008         /* Ignore any data for non-open channels (might happen on close) */
2009         if (c->type != SSH_CHANNEL_OPEN &&
2010             c->type != SSH_CHANNEL_X11_OPEN)
2011                 return;
2012
2013         /* Get the data. */
2014         data = packet_get_string(&data_len);
2015
2016         /*
2017          * Ignore data for protocol > 1.3 if output end is no longer open.
2018          * For protocol 2 the sending side is reducing its window as it sends
2019          * data, so we must 'fake' consumption of the data in order to ensure
2020          * that window updates are sent back.  Otherwise the connection might
2021          * deadlock.
2022          */
2023         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2024                 if (compat20) {
2025                         c->local_window -= data_len;
2026                         c->local_consumed += data_len;
2027                 }
2028                 xfree(data);
2029                 return;
2030         }
2031
2032         if (compat20) {
2033                 if (data_len > c->local_maxpacket) {
2034                         logit("channel %d: rcvd big packet %d, maxpack %d",
2035                             c->self, data_len, c->local_maxpacket);
2036                 }
2037                 if (data_len > c->local_window) {
2038                         logit("channel %d: rcvd too much data %d, win %d",
2039                             c->self, data_len, c->local_window);
2040                         xfree(data);
2041                         return;
2042                 }
2043                 c->local_window -= data_len;
2044         }
2045         packet_check_eom();
2046         if (c->datagram)
2047                 buffer_put_string(&c->output, data, data_len);
2048         else
2049                 buffer_append(&c->output, data, data_len);
2050         xfree(data);
2051 }
2052
2053 /* ARGSUSED */
2054 void
2055 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2056 {
2057         int id;
2058         char *data;
2059         u_int data_len, tcode;
2060         Channel *c;
2061
2062         /* Get the channel number and verify it. */
2063         id = packet_get_int();
2064         c = channel_lookup(id);
2065
2066         if (c == NULL)
2067                 packet_disconnect("Received extended_data for bad channel %d.", id);
2068         if (c->type != SSH_CHANNEL_OPEN) {
2069                 logit("channel %d: ext data for non open", id);
2070                 return;
2071         }
2072         if (c->flags & CHAN_EOF_RCVD) {
2073                 if (datafellows & SSH_BUG_EXTEOF)
2074                         debug("channel %d: accepting ext data after eof", id);
2075                 else
2076                         packet_disconnect("Received extended_data after EOF "
2077                             "on channel %d.", id);
2078         }
2079         tcode = packet_get_int();
2080         if (c->efd == -1 ||
2081             c->extended_usage != CHAN_EXTENDED_WRITE ||
2082             tcode != SSH2_EXTENDED_DATA_STDERR) {
2083                 logit("channel %d: bad ext data", c->self);
2084                 return;
2085         }
2086         data = packet_get_string(&data_len);
2087         packet_check_eom();
2088         if (data_len > c->local_window) {
2089                 logit("channel %d: rcvd too much extended_data %d, win %d",
2090                     c->self, data_len, c->local_window);
2091                 xfree(data);
2092                 return;
2093         }
2094         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2095         c->local_window -= data_len;
2096         buffer_append(&c->extended, data, data_len);
2097         xfree(data);
2098 }
2099
2100 /* ARGSUSED */
2101 void
2102 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2103 {
2104         int id;
2105         Channel *c;
2106
2107         id = packet_get_int();
2108         packet_check_eom();
2109         c = channel_lookup(id);
2110         if (c == NULL)
2111                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2112         chan_rcvd_ieof(c);
2113
2114         /* XXX force input close */
2115         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2116                 debug("channel %d: FORCE input drain", c->self);
2117                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2118                 if (buffer_len(&c->input) == 0)
2119                         chan_ibuf_empty(c);
2120         }
2121
2122 }
2123
2124 /* ARGSUSED */
2125 void
2126 channel_input_close(int type, u_int32_t seq, void *ctxt)
2127 {
2128         int id;
2129         Channel *c;
2130
2131         id = packet_get_int();
2132         packet_check_eom();
2133         c = channel_lookup(id);
2134         if (c == NULL)
2135                 packet_disconnect("Received close for nonexistent channel %d.", id);
2136
2137         /*
2138          * Send a confirmation that we have closed the channel and no more
2139          * data is coming for it.
2140          */
2141         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2142         packet_put_int(c->remote_id);
2143         packet_send();
2144
2145         /*
2146          * If the channel is in closed state, we have sent a close request,
2147          * and the other side will eventually respond with a confirmation.
2148          * Thus, we cannot free the channel here, because then there would be
2149          * no-one to receive the confirmation.  The channel gets freed when
2150          * the confirmation arrives.
2151          */
2152         if (c->type != SSH_CHANNEL_CLOSED) {
2153                 /*
2154                  * Not a closed channel - mark it as draining, which will
2155                  * cause it to be freed later.
2156                  */
2157                 buffer_clear(&c->input);
2158                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2159         }
2160 }
2161
2162 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2163 /* ARGSUSED */
2164 void
2165 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2166 {
2167         int id = packet_get_int();
2168         Channel *c = channel_lookup(id);
2169
2170         packet_check_eom();
2171         if (c == NULL)
2172                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2173         chan_rcvd_oclose(c);
2174 }
2175
2176 /* ARGSUSED */
2177 void
2178 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2179 {
2180         int id = packet_get_int();
2181         Channel *c = channel_lookup(id);
2182
2183         packet_check_eom();
2184         if (c == NULL)
2185                 packet_disconnect("Received close confirmation for "
2186                     "out-of-range channel %d.", id);
2187         if (c->type != SSH_CHANNEL_CLOSED)
2188                 packet_disconnect("Received close confirmation for "
2189                     "non-closed channel %d (type %d).", id, c->type);
2190         channel_free(c);
2191 }
2192
2193 /* ARGSUSED */
2194 void
2195 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2196 {
2197         int id, remote_id;
2198         Channel *c;
2199
2200         id = packet_get_int();
2201         c = channel_lookup(id);
2202
2203         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2204                 packet_disconnect("Received open confirmation for "
2205                     "non-opening channel %d.", id);
2206         remote_id = packet_get_int();
2207         /* Record the remote channel number and mark that the channel is now open. */
2208         c->remote_id = remote_id;
2209         c->type = SSH_CHANNEL_OPEN;
2210
2211         if (compat20) {
2212                 c->remote_window = packet_get_int();
2213                 c->remote_maxpacket = packet_get_int();
2214                 if (c->confirm) {
2215                         debug2("callback start");
2216                         c->confirm(c->self, c->confirm_ctx);
2217                         debug2("callback done");
2218                 }
2219                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2220                     c->remote_window, c->remote_maxpacket);
2221         }
2222         packet_check_eom();
2223 }
2224
2225 static char *
2226 reason2txt(int reason)
2227 {
2228         switch (reason) {
2229         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2230                 return "administratively prohibited";
2231         case SSH2_OPEN_CONNECT_FAILED:
2232                 return "connect failed";
2233         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2234                 return "unknown channel type";
2235         case SSH2_OPEN_RESOURCE_SHORTAGE:
2236                 return "resource shortage";
2237         }
2238         return "unknown reason";
2239 }
2240
2241 /* ARGSUSED */
2242 void
2243 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2244 {
2245         int id, reason;
2246         char *msg = NULL, *lang = NULL;
2247         Channel *c;
2248
2249         id = packet_get_int();
2250         c = channel_lookup(id);
2251
2252         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2253                 packet_disconnect("Received open failure for "
2254                     "non-opening channel %d.", id);
2255         if (compat20) {
2256                 reason = packet_get_int();
2257                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2258                         msg  = packet_get_string(NULL);
2259                         lang = packet_get_string(NULL);
2260                 }
2261                 logit("channel %d: open failed: %s%s%s", id,
2262                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2263                 if (msg != NULL)
2264                         xfree(msg);
2265                 if (lang != NULL)
2266                         xfree(lang);
2267         }
2268         packet_check_eom();
2269         /* Free the channel.  This will also close the socket. */
2270         channel_free(c);
2271 }
2272
2273 /* ARGSUSED */
2274 void
2275 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2276 {
2277         Channel *c;
2278         int id;
2279         u_int adjust;
2280
2281         if (!compat20)
2282                 return;
2283
2284         /* Get the channel number and verify it. */
2285         id = packet_get_int();
2286         c = channel_lookup(id);
2287
2288         if (c == NULL) {
2289                 logit("Received window adjust for non-open channel %d.", id);
2290                 return;
2291         }
2292         adjust = packet_get_int();
2293         packet_check_eom();
2294         debug2("channel %d: rcvd adjust %u", id, adjust);
2295         c->remote_window += adjust;
2296 }
2297
2298 /* ARGSUSED */
2299 void
2300 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2301 {
2302         Channel *c = NULL;
2303         u_short host_port;
2304         char *host, *originator_string;
2305         int remote_id, sock = -1;
2306
2307         remote_id = packet_get_int();
2308         host = packet_get_string(NULL);
2309         host_port = packet_get_int();
2310
2311         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2312                 originator_string = packet_get_string(NULL);
2313         } else {
2314                 originator_string = xstrdup("unknown (remote did not supply name)");
2315         }
2316         packet_check_eom();
2317         sock = channel_connect_to(host, host_port);
2318         if (sock != -1) {
2319                 c = channel_new("connected socket",
2320                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2321                     originator_string, 1);
2322                 c->remote_id = remote_id;
2323         }
2324         xfree(originator_string);
2325         if (c == NULL) {
2326                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2327                 packet_put_int(remote_id);
2328                 packet_send();
2329         }
2330         xfree(host);
2331 }
2332
2333
2334 /* -- tcp forwarding */
2335
2336 void
2337 channel_set_af(int af)
2338 {
2339         IPv4or6 = af;
2340 }
2341
2342 static int
2343 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2344     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2345 {
2346         Channel *c;
2347         int sock, r, success = 0, wildcard = 0, is_client;
2348         struct addrinfo hints, *ai, *aitop;
2349         const char *host, *addr;
2350         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2351
2352         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2353             listen_addr : host_to_connect;
2354         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2355
2356         if (host == NULL) {
2357                 error("No forward host name.");
2358                 return 0;
2359         }
2360         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2361                 error("Forward host name too long.");
2362                 return 0;
2363         }
2364
2365         /*
2366          * Determine whether or not a port forward listens to loopback,
2367          * specified address or wildcard. On the client, a specified bind
2368          * address will always override gateway_ports. On the server, a
2369          * gateway_ports of 1 (``yes'') will override the client's
2370          * specification and force a wildcard bind, whereas a value of 2
2371          * (``clientspecified'') will bind to whatever address the client
2372          * asked for.
2373          *
2374          * Special-case listen_addrs are:
2375          *
2376          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2377          * "" (empty string), "*"  -> wildcard v4/v6
2378          * "localhost"             -> loopback v4/v6
2379          */
2380         addr = NULL;
2381         if (listen_addr == NULL) {
2382                 /* No address specified: default to gateway_ports setting */
2383                 if (gateway_ports)
2384                         wildcard = 1;
2385         } else if (gateway_ports || is_client) {
2386                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2387                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2388                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2389                     (!is_client && gateway_ports == 1))
2390                         wildcard = 1;
2391                 else if (strcmp(listen_addr, "localhost") != 0)
2392                         addr = listen_addr;
2393         }
2394
2395         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2396             type, wildcard, (addr == NULL) ? "NULL" : addr);
2397
2398         /*
2399          * getaddrinfo returns a loopback address if the hostname is
2400          * set to NULL and hints.ai_flags is not AI_PASSIVE
2401          */
2402         memset(&hints, 0, sizeof(hints));
2403         hints.ai_family = IPv4or6;
2404         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2405         hints.ai_socktype = SOCK_STREAM;
2406         snprintf(strport, sizeof strport, "%d", listen_port);
2407         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2408                 if (addr == NULL) {
2409                         /* This really shouldn't happen */
2410                         packet_disconnect("getaddrinfo: fatal error: %s",
2411                             gai_strerror(r));
2412                 } else {
2413                         error("channel_setup_fwd_listener: "
2414                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2415                 }
2416                 return 0;
2417         }
2418
2419         for (ai = aitop; ai; ai = ai->ai_next) {
2420                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2421                         continue;
2422                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2423                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2424                         error("channel_setup_fwd_listener: getnameinfo failed");
2425                         continue;
2426                 }
2427                 /* Create a port to listen for the host. */
2428                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2429                 if (sock < 0) {
2430                         /* this is no error since kernel may not support ipv6 */
2431                         verbose("socket: %.100s", strerror(errno));
2432                         continue;
2433                 }
2434
2435                 channel_set_reuseaddr(sock);
2436
2437                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2438
2439                 /* Bind the socket to the address. */
2440                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2441                         /* address can be in use ipv6 address is already bound */
2442                         if (!ai->ai_next)
2443                                 error("bind: %.100s", strerror(errno));
2444                         else
2445                                 verbose("bind: %.100s", strerror(errno));
2446
2447                         close(sock);
2448                         continue;
2449                 }
2450                 /* Start listening for connections on the socket. */
2451                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2452                         error("listen: %.100s", strerror(errno));
2453                         close(sock);
2454                         continue;
2455                 }
2456                 /* Allocate a channel number for the socket. */
2457                 c = channel_new("port listener", type, sock, sock, -1,
2458                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2459                     0, "port listener", 1);
2460                 strlcpy(c->path, host, sizeof(c->path));
2461                 c->host_port = port_to_connect;
2462                 c->listening_port = listen_port;
2463                 success = 1;
2464         }
2465         if (success == 0)
2466                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2467                     listen_port);
2468         freeaddrinfo(aitop);
2469         return success;
2470 }
2471
2472 int
2473 channel_cancel_rport_listener(const char *host, u_short port)
2474 {
2475         u_int i;
2476         int found = 0;
2477
2478         for (i = 0; i < channels_alloc; i++) {
2479                 Channel *c = channels[i];
2480
2481                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2482                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2483                     c->listening_port == port) {
2484                         debug2("%s: close channel %d", __func__, i);
2485                         channel_free(c);
2486                         found = 1;
2487                 }
2488         }
2489
2490         return (found);
2491 }
2492
2493 /* protocol local port fwd, used by ssh (and sshd in v1) */
2494 int
2495 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2496     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2497 {
2498         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2499             listen_host, listen_port, host_to_connect, port_to_connect,
2500             gateway_ports);
2501 }
2502
2503 /* protocol v2 remote port fwd, used by sshd */
2504 int
2505 channel_setup_remote_fwd_listener(const char *listen_address,
2506     u_short listen_port, int gateway_ports)
2507 {
2508         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2509             listen_address, listen_port, NULL, 0, gateway_ports);
2510 }
2511
2512 /*
2513  * Initiate forwarding of connections to port "port" on remote host through
2514  * the secure channel to host:port from local side.
2515  */
2516
2517 int
2518 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2519     const char *host_to_connect, u_short port_to_connect)
2520 {
2521         int type, success = 0;
2522
2523         /* Record locally that connection to this host/port is permitted. */
2524         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2525                 fatal("channel_request_remote_forwarding: too many forwards");
2526
2527         /* Send the forward request to the remote side. */
2528         if (compat20) {
2529                 const char *address_to_bind;
2530                 if (listen_host == NULL) {
2531                         if (datafellows & SSH_BUG_RFWD_ADDR)
2532                                 address_to_bind = "127.0.0.1";
2533                         else
2534                                 address_to_bind = "localhost";
2535                 } else if (*listen_host == '\0' ||
2536                            strcmp(listen_host, "*") == 0) {
2537                         if (datafellows & SSH_BUG_RFWD_ADDR)
2538                                 address_to_bind = "0.0.0.0";
2539                         else
2540                                 address_to_bind = "";
2541                 } else
2542                         address_to_bind = listen_host;
2543
2544                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2545                 packet_put_cstring("tcpip-forward");
2546                 packet_put_char(1);                     /* boolean: want reply */
2547                 packet_put_cstring(address_to_bind);
2548                 packet_put_int(listen_port);
2549                 packet_send();
2550                 packet_write_wait();
2551                 /* Assume that server accepts the request */
2552                 success = 1;
2553         } else {
2554                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2555                 packet_put_int(listen_port);
2556                 packet_put_cstring(host_to_connect);
2557                 packet_put_int(port_to_connect);
2558                 packet_send();
2559                 packet_write_wait();
2560
2561                 /* Wait for response from the remote side. */
2562                 type = packet_read();
2563                 switch (type) {
2564                 case SSH_SMSG_SUCCESS:
2565                         success = 1;
2566                         break;
2567                 case SSH_SMSG_FAILURE:
2568                         break;
2569                 default:
2570                         /* Unknown packet */
2571                         packet_disconnect("Protocol error for port forward request:"
2572                             "received packet type %d.", type);
2573                 }
2574         }
2575         if (success) {
2576                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2577                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2578                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2579                 num_permitted_opens++;
2580         }
2581         return (success ? 0 : -1);
2582 }
2583
2584 /*
2585  * Request cancellation of remote forwarding of connection host:port from
2586  * local side.
2587  */
2588 void
2589 channel_request_rforward_cancel(const char *host, u_short port)
2590 {
2591         int i;
2592
2593         if (!compat20)
2594                 return;
2595
2596         for (i = 0; i < num_permitted_opens; i++) {
2597                 if (permitted_opens[i].host_to_connect != NULL &&
2598                     permitted_opens[i].listen_port == port)
2599                         break;
2600         }
2601         if (i >= num_permitted_opens) {
2602                 debug("%s: requested forward not found", __func__);
2603                 return;
2604         }
2605         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2606         packet_put_cstring("cancel-tcpip-forward");
2607         packet_put_char(0);
2608         packet_put_cstring(host == NULL ? "" : host);
2609         packet_put_int(port);
2610         packet_send();
2611
2612         permitted_opens[i].listen_port = 0;
2613         permitted_opens[i].port_to_connect = 0;
2614         xfree(permitted_opens[i].host_to_connect);
2615         permitted_opens[i].host_to_connect = NULL;
2616 }
2617
2618 /*
2619  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2620  * listening for the port, and sends back a success reply (or disconnect
2621  * message if there was an error).
2622  */
2623 int
2624 channel_input_port_forward_request(int is_root, int gateway_ports)
2625 {
2626         u_short port, host_port;
2627         int success = 0;
2628         char *hostname;
2629
2630         /* Get arguments from the packet. */
2631         port = packet_get_int();
2632         hostname = packet_get_string(NULL);
2633         host_port = packet_get_int();
2634
2635 #ifndef HAVE_CYGWIN
2636         /*
2637          * Check that an unprivileged user is not trying to forward a
2638          * privileged port.
2639          */
2640         if (port < IPPORT_RESERVED && !is_root)
2641                 packet_disconnect(
2642                     "Requested forwarding of port %d but user is not root.",
2643                     port);
2644         if (host_port == 0)
2645                 packet_disconnect("Dynamic forwarding denied.");
2646 #endif
2647
2648         /* Initiate forwarding */
2649         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2650             host_port, gateway_ports);
2651
2652         /* Free the argument string. */
2653         xfree(hostname);
2654
2655         return (success ? 0 : -1);
2656 }
2657
2658 /*
2659  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2660  * usually called by the server, because the user could connect to any port
2661  * anyway, and the server has no way to know but to trust the client anyway.
2662  */
2663 void
2664 channel_permit_all_opens(void)
2665 {
2666         if (num_permitted_opens == 0)
2667                 all_opens_permitted = 1;
2668 }
2669
2670 void
2671 channel_add_permitted_opens(char *host, int port)
2672 {
2673         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2674                 fatal("channel_add_permitted_opens: too many forwards");
2675         debug("allow port forwarding to host %s port %d", host, port);
2676
2677         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2678         permitted_opens[num_permitted_opens].port_to_connect = port;
2679         num_permitted_opens++;
2680
2681         all_opens_permitted = 0;
2682 }
2683
2684 int
2685 channel_add_adm_permitted_opens(char *host, int port)
2686 {
2687         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2688                 fatal("channel_add_adm_permitted_opens: too many forwards");
2689         debug("config allows port forwarding to host %s port %d", host, port);
2690
2691         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2692              = xstrdup(host);
2693         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2694         return ++num_adm_permitted_opens;
2695 }
2696
2697 void
2698 channel_clear_permitted_opens(void)
2699 {
2700         int i;
2701
2702         for (i = 0; i < num_permitted_opens; i++)
2703                 if (permitted_opens[i].host_to_connect != NULL)
2704                         xfree(permitted_opens[i].host_to_connect);
2705         num_permitted_opens = 0;
2706 }
2707
2708 void
2709 channel_clear_adm_permitted_opens(void)
2710 {
2711         int i;
2712
2713         for (i = 0; i < num_adm_permitted_opens; i++)
2714                 if (permitted_adm_opens[i].host_to_connect != NULL)
2715                         xfree(permitted_adm_opens[i].host_to_connect);
2716         num_adm_permitted_opens = 0;
2717 }
2718
2719 /* return socket to remote host, port */
2720 static int
2721 connect_to(const char *host, u_short port)
2722 {
2723         struct addrinfo hints, *ai, *aitop;
2724         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2725         int gaierr;
2726         int sock = -1;
2727
2728         memset(&hints, 0, sizeof(hints));
2729         hints.ai_family = IPv4or6;
2730         hints.ai_socktype = SOCK_STREAM;
2731         snprintf(strport, sizeof strport, "%d", port);
2732         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2733                 error("connect_to %.100s: unknown host (%s)", host,
2734                     gai_strerror(gaierr));
2735                 return -1;
2736         }
2737         for (ai = aitop; ai; ai = ai->ai_next) {
2738                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2739                         continue;
2740                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2741                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2742                         error("connect_to: getnameinfo failed");
2743                         continue;
2744                 }
2745                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2746                 if (sock < 0) {
2747                         if (ai->ai_next == NULL)
2748                                 error("socket: %.100s", strerror(errno));
2749                         else
2750                                 verbose("socket: %.100s", strerror(errno));
2751                         continue;
2752                 }
2753                 if (set_nonblock(sock) == -1)
2754                         fatal("%s: set_nonblock(%d)", __func__, sock);
2755                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2756                     errno != EINPROGRESS) {
2757                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2758                             strerror(errno));
2759                         close(sock);
2760                         continue;       /* fail -- try next */
2761                 }
2762                 break; /* success */
2763
2764         }
2765         freeaddrinfo(aitop);
2766         if (!ai) {
2767                 error("connect_to %.100s port %d: failed.", host, port);
2768                 return -1;
2769         }
2770         /* success */
2771         set_nodelay(sock);
2772         return sock;
2773 }
2774
2775 int
2776 channel_connect_by_listen_address(u_short listen_port)
2777 {
2778         int i;
2779
2780         for (i = 0; i < num_permitted_opens; i++)
2781                 if (permitted_opens[i].host_to_connect != NULL &&
2782                     permitted_opens[i].listen_port == listen_port)
2783                         return connect_to(
2784                             permitted_opens[i].host_to_connect,
2785                             permitted_opens[i].port_to_connect);
2786         error("WARNING: Server requests forwarding for unknown listen_port %d",
2787             listen_port);
2788         return -1;
2789 }
2790
2791 /* Check if connecting to that port is permitted and connect. */
2792 int
2793 channel_connect_to(const char *host, u_short port)
2794 {
2795         int i, permit, permit_adm = 1;
2796
2797         permit = all_opens_permitted;
2798         if (!permit) {
2799                 for (i = 0; i < num_permitted_opens; i++)
2800                         if (permitted_opens[i].host_to_connect != NULL &&
2801                             permitted_opens[i].port_to_connect == port &&
2802                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2803                                 permit = 1;
2804         }
2805
2806         if (num_adm_permitted_opens > 0) {
2807                 permit_adm = 0;
2808                 for (i = 0; i < num_adm_permitted_opens; i++)
2809                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2810                             permitted_adm_opens[i].port_to_connect == port &&
2811                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2812                             == 0)
2813                                 permit_adm = 1;
2814         }
2815
2816         if (!permit || !permit_adm) {
2817                 logit("Received request to connect to host %.100s port %d, "
2818                     "but the request was denied.", host, port);
2819                 return -1;
2820         }
2821         return connect_to(host, port);
2822 }
2823
2824 void
2825 channel_send_window_changes(void)
2826 {
2827         u_int i;
2828         struct winsize ws;
2829
2830         for (i = 0; i < channels_alloc; i++) {
2831                 if (channels[i] == NULL || !channels[i]->client_tty ||
2832                     channels[i]->type != SSH_CHANNEL_OPEN)
2833                         continue;
2834                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2835                         continue;
2836                 channel_request_start(i, "window-change", 0);
2837                 packet_put_int((u_int)ws.ws_col);
2838                 packet_put_int((u_int)ws.ws_row);
2839                 packet_put_int((u_int)ws.ws_xpixel);
2840                 packet_put_int((u_int)ws.ws_ypixel);
2841                 packet_send();
2842         }
2843 }
2844
2845 /* -- X11 forwarding */
2846
2847 /*
2848  * Creates an internet domain socket for listening for X11 connections.
2849  * Returns 0 and a suitable display number for the DISPLAY variable
2850  * stored in display_numberp , or -1 if an error occurs.
2851  */
2852 int
2853 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2854     int single_connection, u_int *display_numberp, int **chanids)
2855 {
2856         Channel *nc = NULL;
2857         int display_number, sock;
2858         u_short port;
2859         struct addrinfo hints, *ai, *aitop;
2860         char strport[NI_MAXSERV];
2861         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2862
2863         if (chanids == NULL)
2864                 return -1;
2865
2866         for (display_number = x11_display_offset;
2867             display_number < MAX_DISPLAYS;
2868             display_number++) {
2869                 port = 6000 + display_number;
2870                 memset(&hints, 0, sizeof(hints));
2871                 hints.ai_family = IPv4or6;
2872                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2873                 hints.ai_socktype = SOCK_STREAM;
2874                 snprintf(strport, sizeof strport, "%d", port);
2875                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2876                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2877                         return -1;
2878                 }
2879                 for (ai = aitop; ai; ai = ai->ai_next) {
2880                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2881                                 continue;
2882                         sock = socket(ai->ai_family, ai->ai_socktype,
2883                             ai->ai_protocol);
2884                         if (sock < 0) {
2885                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2886                                         error("socket: %.100s", strerror(errno));
2887                                         freeaddrinfo(aitop);
2888                                         return -1;
2889                                 } else {
2890                                         debug("x11_create_display_inet: Socket family %d not supported",
2891                                                  ai->ai_family);
2892                                         continue;
2893                                 }
2894                         }
2895 #ifdef IPV6_V6ONLY
2896                         if (ai->ai_family == AF_INET6) {
2897                                 int on = 1;
2898                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2899                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2900                         }
2901 #endif
2902                         channel_set_reuseaddr(sock);
2903                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2904                                 debug2("bind port %d: %.100s", port, strerror(errno));
2905                                 close(sock);
2906
2907                                 if (ai->ai_next)
2908                                         continue;
2909
2910                                 for (n = 0; n < num_socks; n++) {
2911                                         close(socks[n]);
2912                                 }
2913                                 num_socks = 0;
2914                                 break;
2915                         }
2916                         socks[num_socks++] = sock;
2917 #ifndef DONT_TRY_OTHER_AF
2918                         if (num_socks == NUM_SOCKS)
2919                                 break;
2920 #else
2921                         if (x11_use_localhost) {
2922                                 if (num_socks == NUM_SOCKS)
2923                                         break;
2924                         } else {
2925                                 break;
2926                         }
2927 #endif
2928                 }
2929                 freeaddrinfo(aitop);
2930                 if (num_socks > 0)
2931                         break;
2932         }
2933         if (display_number >= MAX_DISPLAYS) {
2934                 error("Failed to allocate internet-domain X11 display socket.");
2935                 return -1;
2936         }
2937         /* Start listening for connections on the socket. */
2938         for (n = 0; n < num_socks; n++) {
2939                 sock = socks[n];
2940                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2941                         error("listen: %.100s", strerror(errno));
2942                         close(sock);
2943                         return -1;
2944                 }
2945         }
2946
2947         /* Allocate a channel for each socket. */
2948         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2949         for (n = 0; n < num_socks; n++) {
2950                 sock = socks[n];
2951                 nc = channel_new("x11 listener",
2952                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2953                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2954                     0, "X11 inet listener", 1);
2955                 nc->single_connection = single_connection;
2956                 (*chanids)[n] = nc->self;
2957         }
2958         (*chanids)[n] = -1;
2959
2960         /* Return the display number for the DISPLAY environment variable. */
2961         *display_numberp = display_number;
2962         return (0);
2963 }
2964
2965 static int
2966 connect_local_xsocket(u_int dnr)
2967 {
2968         int sock;
2969         struct sockaddr_un addr;
2970
2971         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2972         if (sock < 0)
2973                 error("socket: %.100s", strerror(errno));
2974         memset(&addr, 0, sizeof(addr));
2975         addr.sun_family = AF_UNIX;
2976         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2977         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
2978                 return sock;
2979         close(sock);
2980         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2981         return -1;
2982 }
2983
2984 int
2985 x11_connect_display(void)
2986 {
2987         u_int display_number;
2988         const char *display;
2989         char buf[1024], *cp;
2990         struct addrinfo hints, *ai, *aitop;
2991         char strport[NI_MAXSERV];
2992         int gaierr, sock = 0;
2993
2994         /* Try to open a socket for the local X server. */
2995         display = getenv("DISPLAY");
2996         if (!display) {
2997                 error("DISPLAY not set.");
2998                 return -1;
2999         }
3000         /*
3001          * Now we decode the value of the DISPLAY variable and make a
3002          * connection to the real X server.
3003          */
3004
3005         /*
3006          * Check if it is a unix domain socket.  Unix domain displays are in
3007          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3008          */
3009         if (strncmp(display, "unix:", 5) == 0 ||
3010             display[0] == ':') {
3011                 /* Connect to the unix domain socket. */
3012                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3013                         error("Could not parse display number from DISPLAY: %.100s",
3014                             display);
3015                         return -1;
3016                 }
3017                 /* Create a socket. */
3018                 sock = connect_local_xsocket(display_number);
3019                 if (sock < 0)
3020                         return -1;
3021
3022                 /* OK, we now have a connection to the display. */
3023                 return sock;
3024         }
3025         /*
3026          * Connect to an inet socket.  The DISPLAY value is supposedly
3027          * hostname:d[.s], where hostname may also be numeric IP address.
3028          */
3029         strlcpy(buf, display, sizeof(buf));
3030         cp = strchr(buf, ':');
3031         if (!cp) {
3032                 error("Could not find ':' in DISPLAY: %.100s", display);
3033                 return -1;
3034         }
3035         *cp = 0;
3036         /* buf now contains the host name.  But first we parse the display number. */
3037         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3038                 error("Could not parse display number from DISPLAY: %.100s",
3039                     display);
3040                 return -1;
3041         }
3042
3043         /* Look up the host address */
3044         memset(&hints, 0, sizeof(hints));
3045         hints.ai_family = IPv4or6;
3046         hints.ai_socktype = SOCK_STREAM;
3047         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3048         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3049                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
3050                 return -1;
3051         }
3052         for (ai = aitop; ai; ai = ai->ai_next) {
3053                 /* Create a socket. */
3054                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3055                 if (sock < 0) {
3056                         debug2("socket: %.100s", strerror(errno));
3057                         continue;
3058                 }
3059                 /* Connect it to the display. */
3060                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3061                         debug2("connect %.100s port %u: %.100s", buf,
3062                             6000 + display_number, strerror(errno));
3063                         close(sock);
3064                         continue;
3065                 }
3066                 /* Success */
3067                 break;
3068         }
3069         freeaddrinfo(aitop);
3070         if (!ai) {
3071                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3072                     strerror(errno));
3073                 return -1;
3074         }
3075         set_nodelay(sock);
3076         return sock;
3077 }
3078
3079 /*
3080  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3081  * the remote channel number.  We should do whatever we want, and respond
3082  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3083  */
3084
3085 /* ARGSUSED */
3086 void
3087 x11_input_open(int type, u_int32_t seq, void *ctxt)
3088 {
3089         Channel *c = NULL;
3090         int remote_id, sock = 0;
3091         char *remote_host;
3092
3093         debug("Received X11 open request.");
3094
3095         remote_id = packet_get_int();
3096
3097         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3098                 remote_host = packet_get_string(NULL);
3099         } else {
3100                 remote_host = xstrdup("unknown (remote did not supply name)");
3101         }
3102         packet_check_eom();
3103
3104         /* Obtain a connection to the real X display. */
3105         sock = x11_connect_display();
3106         if (sock != -1) {
3107                 /* Allocate a channel for this connection. */
3108                 c = channel_new("connected x11 socket",
3109                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3110                     remote_host, 1);
3111                 c->remote_id = remote_id;
3112                 c->force_drain = 1;
3113         }
3114         xfree(remote_host);
3115         if (c == NULL) {
3116                 /* Send refusal to the remote host. */
3117                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3118                 packet_put_int(remote_id);
3119         } else {
3120                 /* Send a confirmation to the remote host. */
3121                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3122                 packet_put_int(remote_id);
3123                 packet_put_int(c->self);
3124         }
3125         packet_send();
3126 }
3127
3128 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3129 /* ARGSUSED */
3130 void
3131 deny_input_open(int type, u_int32_t seq, void *ctxt)
3132 {
3133         int rchan = packet_get_int();
3134
3135         switch (type) {
3136         case SSH_SMSG_AGENT_OPEN:
3137                 error("Warning: ssh server tried agent forwarding.");
3138                 break;
3139         case SSH_SMSG_X11_OPEN:
3140                 error("Warning: ssh server tried X11 forwarding.");
3141                 break;
3142         default:
3143                 error("deny_input_open: type %d", type);
3144                 break;
3145         }
3146         error("Warning: this is probably a break-in attempt by a malicious server.");
3147         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3148         packet_put_int(rchan);
3149         packet_send();
3150 }
3151
3152 /*
3153  * Requests forwarding of X11 connections, generates fake authentication
3154  * data, and enables authentication spoofing.
3155  * This should be called in the client only.
3156  */
3157 void
3158 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3159     const char *proto, const char *data)
3160 {
3161         u_int data_len = (u_int) strlen(data) / 2;
3162         u_int i, value;
3163         char *new_data;
3164         int screen_number;
3165         const char *cp;
3166         u_int32_t rnd = 0;
3167
3168         if (x11_saved_display == NULL)
3169                 x11_saved_display = xstrdup(disp);
3170         else if (strcmp(disp, x11_saved_display) != 0) {
3171                 error("x11_request_forwarding_with_spoofing: different "
3172                     "$DISPLAY already forwarded");
3173                 return;
3174         }
3175
3176         cp = strchr(disp, ':');
3177         if (cp)
3178                 cp = strchr(cp, '.');
3179         if (cp)
3180                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3181         else
3182                 screen_number = 0;
3183
3184         if (x11_saved_proto == NULL) {
3185                 /* Save protocol name. */
3186                 x11_saved_proto = xstrdup(proto);
3187                 /*
3188                  * Extract real authentication data and generate fake data
3189                  * of the same length.
3190                  */
3191                 x11_saved_data = xmalloc(data_len);
3192                 x11_fake_data = xmalloc(data_len);
3193                 for (i = 0; i < data_len; i++) {
3194                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3195                                 fatal("x11_request_forwarding: bad "
3196                                     "authentication data: %.100s", data);
3197                         if (i % 4 == 0)
3198                                 rnd = arc4random();
3199                         x11_saved_data[i] = value;
3200                         x11_fake_data[i] = rnd & 0xff;
3201                         rnd >>= 8;
3202                 }
3203                 x11_saved_data_len = data_len;
3204                 x11_fake_data_len = data_len;
3205         }
3206
3207         /* Convert the fake data into hex. */
3208         new_data = tohex(x11_fake_data, data_len);
3209
3210         /* Send the request packet. */
3211         if (compat20) {
3212                 channel_request_start(client_session_id, "x11-req", 0);
3213                 packet_put_char(0);     /* XXX bool single connection */
3214         } else {
3215                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3216         }
3217         packet_put_cstring(proto);
3218         packet_put_cstring(new_data);
3219         packet_put_int(screen_number);
3220         packet_send();
3221         packet_write_wait();
3222         xfree(new_data);
3223 }
3224
3225
3226 /* -- agent forwarding */
3227
3228 /* Sends a message to the server to request authentication fd forwarding. */
3229
3230 void
3231 auth_request_forwarding(void)
3232 {
3233         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3234         packet_send();
3235         packet_write_wait();
3236 }