channels.c

   1 /* $OpenBSD: channels.c,v 1.255 2006/07/12 22:28:51 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/ioctl.h>
  45 #include <sys/types.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48
  49 #include <netinet/in.h>
  50 #include <arpa/inet.h>
  51
  52 #include <errno.h>
  53 #if defined(HAVE_NETDB_H)
  54 # include <netdb.h>
  55 #endif
  56 #include <termios.h>
  57
  58 #include "ssh.h"
  59 #include "ssh1.h"
  60 #include "ssh2.h"
  61 #include "packet.h"
  62 #include "xmalloc.h"
  63 #include "log.h"
  64 #include "misc.h"
  65 #include "channels.h"
  66 #include "compat.h"
  67 #include "canohost.h"
  68 #include "key.h"
  69 #include "authfd.h"
  70 #include "pathnames.h"
  71 #include "bufaux.h"
  72
  73 /* -- channel core */
  74
  75 /*
  76  * Pointer to an array containing all allocated channels.  The array is
  77  * dynamically extended as needed.
  78  */
  79 static Channel **channels = NULL;
  80
  81 /*
  82  * Size of the channel array.  All slots of the array must always be
  83  * initialized (at least the type field); unused slots set to NULL
  84  */
  85 static u_int channels_alloc = 0;
  86
  87 /*
  88  * Maximum file descriptor value used in any of the channels.  This is
  89  * updated in channel_new.
  90  */
  91 static int channel_max_fd = 0;
  92
  93
  94 /* -- tcp forwarding */
  95
  96 /*
  97  * Data structure for storing which hosts are permitted for forward requests.
  98  * The local sides of any remote forwards are stored in this array to prevent
  99  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 100  * network (which might be behind a firewall).
 101  */
 102 typedef struct {
 103         char *host_to_connect;          /* Connect to 'host'. */
 104         u_short port_to_connect;        /* Connect to 'port'. */
 105         u_short listen_port;            /* Remote side should listen port number. */
 106 } ForwardPermission;
 107
 108 /* List of all permitted host/port pairs to connect. */
 109 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 110
 111 /* Number of permitted host/port pairs in the array. */
 112 static int num_permitted_opens = 0;
 113 /*
 114  * If this is true, all opens are permitted.  This is the case on the server
 115  * on which we have to trust the client anyway, and the user could do
 116  * anything after logging in anyway.
 117  */
 118 static int all_opens_permitted = 0;
 119
 120
 121 /* -- X11 forwarding */
 122
 123 /* Maximum number of fake X11 displays to try. */
 124 #define MAX_DISPLAYS  1000
 125
 126 /* Saved X11 local (client) display. */
 127 static char *x11_saved_display = NULL;
 128
 129 /* Saved X11 authentication protocol name. */
 130 static char *x11_saved_proto = NULL;
 131
 132 /* Saved X11 authentication data.  This is the real data. */
 133 static char *x11_saved_data = NULL;
 134 static u_int x11_saved_data_len = 0;
 135
 136 /*
 137  * Fake X11 authentication data.  This is what the server will be sending us;
 138  * we should replace any occurrences of this by the real data.
 139  */
 140 static u_char *x11_fake_data = NULL;
 141 static u_int x11_fake_data_len;
 142
 143
 144 /* -- agent forwarding */
 145
 146 #define NUM_SOCKS       10
 147
 148 /* AF_UNSPEC or AF_INET or AF_INET6 */
 149 static int IPv4or6 = AF_UNSPEC;
 150
 151 /* helper */
 152 static void port_open_helper(Channel *c, char *rtype);
 153
 154 /* -- channel core */
 155
 156 Channel *
 157 channel_by_id(int id)
 158 {
 159         Channel *c;
 160
 161         if (id < 0 || (u_int)id >= channels_alloc) {
 162                 logit("channel_by_id: %d: bad id", id);
 163                 return NULL;
 164         }
 165         c = channels[id];
 166         if (c == NULL) {
 167                 logit("channel_by_id: %d: bad id: channel free", id);
 168                 return NULL;
 169         }
 170         return c;
 171 }
 172
 173 /*
 174  * Returns the channel if it is allowed to receive protocol messages.
 175  * Private channels, like listening sockets, may not receive messages.
 176  */
 177 Channel *
 178 channel_lookup(int id)
 179 {
 180         Channel *c;
 181
 182         if ((c = channel_by_id(id)) == NULL)
 183                 return (NULL);
 184
 185         switch (c->type) {
 186         case SSH_CHANNEL_X11_OPEN:
 187         case SSH_CHANNEL_LARVAL:
 188         case SSH_CHANNEL_CONNECTING:
 189         case SSH_CHANNEL_DYNAMIC:
 190         case SSH_CHANNEL_OPENING:
 191         case SSH_CHANNEL_OPEN:
 192         case SSH_CHANNEL_INPUT_DRAINING:
 193         case SSH_CHANNEL_OUTPUT_DRAINING:
 194                 return (c);
 195         }
 196         logit("Non-public channel %d, type %d.", id, c->type);
 197         return (NULL);
 198 }
 199
 200 /*
 201  * Register filedescriptors for a channel, used when allocating a channel or
 202  * when the channel consumer/producer is ready, e.g. shell exec'd
 203  */
 204 static void
 205 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 206     int extusage, int nonblock)
 207 {
 208         /* Update the maximum file descriptor value. */
 209         channel_max_fd = MAX(channel_max_fd, rfd);
 210         channel_max_fd = MAX(channel_max_fd, wfd);
 211         channel_max_fd = MAX(channel_max_fd, efd);
 212
 213         /* XXX set close-on-exec -markus */
 214
 215         c->rfd = rfd;
 216         c->wfd = wfd;
 217         c->sock = (rfd == wfd) ? rfd : -1;
 218         c->ctl_fd = -1; /* XXX: set elsewhere */
 219         c->efd = efd;
 220         c->extended_usage = extusage;
 221
 222         /* XXX ugly hack: nonblock is only set by the server */
 223         if (nonblock && isatty(c->rfd)) {
 224                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 225                 c->isatty = 1;
 226                 if (!isatty(c->wfd)) {
 227                         error("channel %d: wfd %d is not a tty?",
 228                             c->self, c->wfd);
 229                 }
 230         } else {
 231                 c->isatty = 0;
 232         }
 233         c->wfd_isatty = isatty(c->wfd);
 234
 235         /* enable nonblocking mode */
 236         if (nonblock) {
 237                 if (rfd != -1)
 238                         set_nonblock(rfd);
 239                 if (wfd != -1)
 240                         set_nonblock(wfd);
 241                 if (efd != -1)
 242                         set_nonblock(efd);
 243         }
 244 }
 245
 246 /*
 247  * Allocate a new channel object and set its type and socket. This will cause
 248  * remote_name to be freed.
 249  */
 250 Channel *
 251 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 252     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 253 {
 254         int found;
 255         u_int i;
 256         Channel *c;
 257
 258         /* Do initial allocation if this is the first call. */
 259         if (channels_alloc == 0) {
 260                 channels_alloc = 10;
 261                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 262                 for (i = 0; i < channels_alloc; i++)
 263                         channels[i] = NULL;
 264         }
 265         /* Try to find a free slot where to put the new channel. */
 266         for (found = -1, i = 0; i < channels_alloc; i++)
 267                 if (channels[i] == NULL) {
 268                         /* Found a free slot. */
 269                         found = (int)i;
 270                         break;
 271                 }
 272         if (found < 0) {
 273                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 274                 found = channels_alloc;
 275                 if (channels_alloc > 10000)
 276                         fatal("channel_new: internal error: channels_alloc %d "
 277                             "too big.", channels_alloc);
 278                 channels = xrealloc(channels, channels_alloc + 10,
 279                     sizeof(Channel *));
 280                 channels_alloc += 10;
 281                 debug2("channel: expanding %d", channels_alloc);
 282                 for (i = found; i < channels_alloc; i++)
 283                         channels[i] = NULL;
 284         }
 285         /* Initialize and return new channel. */
 286         c = channels[found] = xcalloc(1, sizeof(Channel));
 287         buffer_init(&c->input);
 288         buffer_init(&c->output);
 289         buffer_init(&c->extended);
 290         c->ostate = CHAN_OUTPUT_OPEN;
 291         c->istate = CHAN_INPUT_OPEN;
 292         c->flags = 0;
 293         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 294         c->self = found;
 295         c->type = type;
 296         c->ctype = ctype;
 297         c->local_window = window;
 298         c->local_window_max = window;
 299         c->local_consumed = 0;
 300         c->local_maxpacket = maxpack;
 301         c->remote_id = -1;
 302         c->remote_name = xstrdup(remote_name);
 303         c->remote_window = 0;
 304         c->remote_maxpacket = 0;
 305         c->force_drain = 0;
 306         c->single_connection = 0;
 307         c->detach_user = NULL;
 308         c->detach_close = 0;
 309         c->confirm = NULL;
 310         c->confirm_ctx = NULL;
 311         c->input_filter = NULL;
 312         c->output_filter = NULL;
 313         debug("channel %d: new [%s]", found, remote_name);
 314         return c;
 315 }
 316
 317 static int
 318 channel_find_maxfd(void)
 319 {
 320         u_int i;
 321         int max = 0;
 322         Channel *c;
 323
 324         for (i = 0; i < channels_alloc; i++) {
 325                 c = channels[i];
 326                 if (c != NULL) {
 327                         max = MAX(max, c->rfd);
 328                         max = MAX(max, c->wfd);
 329                         max = MAX(max, c->efd);
 330                 }
 331         }
 332         return max;
 333 }
 334
 335 int
 336 channel_close_fd(int *fdp)
 337 {
 338         int ret = 0, fd = *fdp;
 339
 340         if (fd != -1) {
 341                 ret = close(fd);
 342                 *fdp = -1;
 343                 if (fd == channel_max_fd)
 344                         channel_max_fd = channel_find_maxfd();
 345         }
 346         return ret;
 347 }
 348
 349 /* Close all channel fd/socket. */
 350 static void
 351 channel_close_fds(Channel *c)
 352 {
 353         debug3("channel %d: close_fds r %d w %d e %d c %d",
 354             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 355
 356         channel_close_fd(&c->sock);
 357         channel_close_fd(&c->ctl_fd);
 358         channel_close_fd(&c->rfd);
 359         channel_close_fd(&c->wfd);
 360         channel_close_fd(&c->efd);
 361 }
 362
 363 /* Free the channel and close its fd/socket. */
 364 void
 365 channel_free(Channel *c)
 366 {
 367         char *s;
 368         u_int i, n;
 369
 370         for (n = 0, i = 0; i < channels_alloc; i++)
 371                 if (channels[i])
 372                         n++;
 373         debug("channel %d: free: %s, nchannels %u", c->self,
 374             c->remote_name ? c->remote_name : "???", n);
 375
 376         s = channel_open_message();
 377         debug3("channel %d: status: %s", c->self, s);
 378         xfree(s);
 379
 380         if (c->sock != -1)
 381                 shutdown(c->sock, SHUT_RDWR);
 382         if (c->ctl_fd != -1)
 383                 shutdown(c->ctl_fd, SHUT_RDWR);
 384         channel_close_fds(c);
 385         buffer_free(&c->input);
 386         buffer_free(&c->output);
 387         buffer_free(&c->extended);
 388         if (c->remote_name) {
 389                 xfree(c->remote_name);
 390                 c->remote_name = NULL;
 391         }
 392         channels[c->self] = NULL;
 393         xfree(c);
 394 }
 395
 396 void
 397 channel_free_all(void)
 398 {
 399         u_int i;
 400
 401         for (i = 0; i < channels_alloc; i++)
 402                 if (channels[i] != NULL)
 403                         channel_free(channels[i]);
 404 }
 405
 406 /*
 407  * Closes the sockets/fds of all channels.  This is used to close extra file
 408  * descriptors after a fork.
 409  */
 410 void
 411 channel_close_all(void)
 412 {
 413         u_int i;
 414
 415         for (i = 0; i < channels_alloc; i++)
 416                 if (channels[i] != NULL)
 417                         channel_close_fds(channels[i]);
 418 }
 419
 420 /*
 421  * Stop listening to channels.
 422  */
 423 void
 424 channel_stop_listening(void)
 425 {
 426         u_int i;
 427         Channel *c;
 428
 429         for (i = 0; i < channels_alloc; i++) {
 430                 c = channels[i];
 431                 if (c != NULL) {
 432                         switch (c->type) {
 433                         case SSH_CHANNEL_AUTH_SOCKET:
 434                         case SSH_CHANNEL_PORT_LISTENER:
 435                         case SSH_CHANNEL_RPORT_LISTENER:
 436                         case SSH_CHANNEL_X11_LISTENER:
 437                                 channel_close_fd(&c->sock);
 438                                 channel_free(c);
 439                                 break;
 440                         }
 441                 }
 442         }
 443 }
 444
 445 /*
 446  * Returns true if no channel has too much buffered data, and false if one or
 447  * more channel is overfull.
 448  */
 449 int
 450 channel_not_very_much_buffered_data(void)
 451 {
 452         u_int i;
 453         Channel *c;
 454
 455         for (i = 0; i < channels_alloc; i++) {
 456                 c = channels[i];
 457                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 458 #if 0
 459                         if (!compat20 &&
 460                             buffer_len(&c->input) > packet_get_maxsize()) {
 461                                 debug2("channel %d: big input buffer %d",
 462                                     c->self, buffer_len(&c->input));
 463                                 return 0;
 464                         }
 465 #endif
 466                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 467                                 debug2("channel %d: big output buffer %u > %u",
 468                                     c->self, buffer_len(&c->output),
 469                                     packet_get_maxsize());
 470                                 return 0;
 471                         }
 472                 }
 473         }
 474         return 1;
 475 }
 476
 477 /* Returns true if any channel is still open. */
 478 int
 479 channel_still_open(void)
 480 {
 481         u_int i;
 482         Channel *c;
 483
 484         for (i = 0; i < channels_alloc; i++) {
 485                 c = channels[i];
 486                 if (c == NULL)
 487                         continue;
 488                 switch (c->type) {
 489                 case SSH_CHANNEL_X11_LISTENER:
 490                 case SSH_CHANNEL_PORT_LISTENER:
 491                 case SSH_CHANNEL_RPORT_LISTENER:
 492                 case SSH_CHANNEL_CLOSED:
 493                 case SSH_CHANNEL_AUTH_SOCKET:
 494                 case SSH_CHANNEL_DYNAMIC:
 495                 case SSH_CHANNEL_CONNECTING:
 496                 case SSH_CHANNEL_ZOMBIE:
 497                         continue;
 498                 case SSH_CHANNEL_LARVAL:
 499                         if (!compat20)
 500                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 501                         continue;
 502                 case SSH_CHANNEL_OPENING:
 503                 case SSH_CHANNEL_OPEN:
 504                 case SSH_CHANNEL_X11_OPEN:
 505                         return 1;
 506                 case SSH_CHANNEL_INPUT_DRAINING:
 507                 case SSH_CHANNEL_OUTPUT_DRAINING:
 508                         if (!compat13)
 509                                 fatal("cannot happen: OUT_DRAIN");
 510                         return 1;
 511                 default:
 512                         fatal("channel_still_open: bad channel type %d", c->type);
 513                         /* NOTREACHED */
 514                 }
 515         }
 516         return 0;
 517 }
 518
 519 /* Returns the id of an open channel suitable for keepaliving */
 520 int
 521 channel_find_open(void)
 522 {
 523         u_int i;
 524         Channel *c;
 525
 526         for (i = 0; i < channels_alloc; i++) {
 527                 c = channels[i];
 528                 if (c == NULL || c->remote_id < 0)
 529                         continue;
 530                 switch (c->type) {
 531                 case SSH_CHANNEL_CLOSED:
 532                 case SSH_CHANNEL_DYNAMIC:
 533                 case SSH_CHANNEL_X11_LISTENER:
 534                 case SSH_CHANNEL_PORT_LISTENER:
 535                 case SSH_CHANNEL_RPORT_LISTENER:
 536                 case SSH_CHANNEL_OPENING:
 537                 case SSH_CHANNEL_CONNECTING:
 538                 case SSH_CHANNEL_ZOMBIE:
 539                         continue;
 540                 case SSH_CHANNEL_LARVAL:
 541                 case SSH_CHANNEL_AUTH_SOCKET:
 542                 case SSH_CHANNEL_OPEN:
 543                 case SSH_CHANNEL_X11_OPEN:
 544                         return i;
 545                 case SSH_CHANNEL_INPUT_DRAINING:
 546                 case SSH_CHANNEL_OUTPUT_DRAINING:
 547                         if (!compat13)
 548                                 fatal("cannot happen: OUT_DRAIN");
 549                         return i;
 550                 default:
 551                         fatal("channel_find_open: bad channel type %d", c->type);
 552                         /* NOTREACHED */
 553                 }
 554         }
 555         return -1;
 556 }
 557
 558
 559 /*
 560  * Returns a message describing the currently open forwarded connections,
 561  * suitable for sending to the client.  The message contains crlf pairs for
 562  * newlines.
 563  */
 564 char *
 565 channel_open_message(void)
 566 {
 567         Buffer buffer;
 568         Channel *c;
 569         char buf[1024], *cp;
 570         u_int i;
 571
 572         buffer_init(&buffer);
 573         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 574         buffer_append(&buffer, buf, strlen(buf));
 575         for (i = 0; i < channels_alloc; i++) {
 576                 c = channels[i];
 577                 if (c == NULL)
 578                         continue;
 579                 switch (c->type) {
 580                 case SSH_CHANNEL_X11_LISTENER:
 581                 case SSH_CHANNEL_PORT_LISTENER:
 582                 case SSH_CHANNEL_RPORT_LISTENER:
 583                 case SSH_CHANNEL_CLOSED:
 584                 case SSH_CHANNEL_AUTH_SOCKET:
 585                 case SSH_CHANNEL_ZOMBIE:
 586                         continue;
 587                 case SSH_CHANNEL_LARVAL:
 588                 case SSH_CHANNEL_OPENING:
 589                 case SSH_CHANNEL_CONNECTING:
 590                 case SSH_CHANNEL_DYNAMIC:
 591                 case SSH_CHANNEL_OPEN:
 592                 case SSH_CHANNEL_X11_OPEN:
 593                 case SSH_CHANNEL_INPUT_DRAINING:
 594                 case SSH_CHANNEL_OUTPUT_DRAINING:
 595                         snprintf(buf, sizeof buf,
 596                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 597                             c->self, c->remote_name,
 598                             c->type, c->remote_id,
 599                             c->istate, buffer_len(&c->input),
 600                             c->ostate, buffer_len(&c->output),
 601                             c->rfd, c->wfd, c->ctl_fd);
 602                         buffer_append(&buffer, buf, strlen(buf));
 603                         continue;
 604                 default:
 605                         fatal("channel_open_message: bad channel type %d", c->type);
 606                         /* NOTREACHED */
 607                 }
 608         }
 609         buffer_append(&buffer, "\0", 1);
 610         cp = xstrdup(buffer_ptr(&buffer));
 611         buffer_free(&buffer);
 612         return cp;
 613 }
 614
 615 void
 616 channel_send_open(int id)
 617 {
 618         Channel *c = channel_lookup(id);
 619
 620         if (c == NULL) {
 621                 logit("channel_send_open: %d: bad id", id);
 622                 return;
 623         }
 624         debug2("channel %d: send open", id);
 625         packet_start(SSH2_MSG_CHANNEL_OPEN);
 626         packet_put_cstring(c->ctype);
 627         packet_put_int(c->self);
 628         packet_put_int(c->local_window);
 629         packet_put_int(c->local_maxpacket);
 630         packet_send();
 631 }
 632
 633 void
 634 channel_request_start(int id, char *service, int wantconfirm)
 635 {
 636         Channel *c = channel_lookup(id);
 637
 638         if (c == NULL) {
 639                 logit("channel_request_start: %d: unknown channel id", id);
 640                 return;
 641         }
 642         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 643         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 644         packet_put_int(c->remote_id);
 645         packet_put_cstring(service);
 646         packet_put_char(wantconfirm);
 647 }
 648
 649 void
 650 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 651 {
 652         Channel *c = channel_lookup(id);
 653
 654         if (c == NULL) {
 655                 logit("channel_register_comfirm: %d: bad id", id);
 656                 return;
 657         }
 658         c->confirm = fn;
 659         c->confirm_ctx = ctx;
 660 }
 661
 662 void
 663 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 664 {
 665         Channel *c = channel_by_id(id);
 666
 667         if (c == NULL) {
 668                 logit("channel_register_cleanup: %d: bad id", id);
 669                 return;
 670         }
 671         c->detach_user = fn;
 672         c->detach_close = do_close;
 673 }
 674
 675 void
 676 channel_cancel_cleanup(int id)
 677 {
 678         Channel *c = channel_by_id(id);
 679
 680         if (c == NULL) {
 681                 logit("channel_cancel_cleanup: %d: bad id", id);
 682                 return;
 683         }
 684         c->detach_user = NULL;
 685         c->detach_close = 0;
 686 }
 687
 688 void
 689 channel_register_filter(int id, channel_infilter_fn *ifn,
 690     channel_outfilter_fn *ofn)
 691 {
 692         Channel *c = channel_lookup(id);
 693
 694         if (c == NULL) {
 695                 logit("channel_register_filter: %d: bad id", id);
 696                 return;
 697         }
 698         c->input_filter = ifn;
 699         c->output_filter = ofn;
 700 }
 701
 702 void
 703 channel_set_fds(int id, int rfd, int wfd, int efd,
 704     int extusage, int nonblock, u_int window_max)
 705 {
 706         Channel *c = channel_lookup(id);
 707
 708         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 709                 fatal("channel_activate for non-larval channel %d.", id);
 710         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 711         c->type = SSH_CHANNEL_OPEN;
 712         c->local_window = c->local_window_max = window_max;
 713         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 714         packet_put_int(c->remote_id);
 715         packet_put_int(c->local_window);
 716         packet_send();
 717 }
 718
 719 /*
 720  * 'channel_pre*' are called just before select() to add any bits relevant to
 721  * channels in the select bitmasks.
 722  */
 723 /*
 724  * 'channel_post*': perform any appropriate operations for channels which
 725  * have events pending.
 726  */
 727 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 728 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 729 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 730
 731 static void
 732 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 733 {
 734         FD_SET(c->sock, readset);
 735 }
 736
 737 static void
 738 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 739 {
 740         debug3("channel %d: waiting for connection", c->self);
 741         FD_SET(c->sock, writeset);
 742 }
 743
 744 static void
 745 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 746 {
 747         if (buffer_len(&c->input) < packet_get_maxsize())
 748                 FD_SET(c->sock, readset);
 749         if (buffer_len(&c->output) > 0)
 750                 FD_SET(c->sock, writeset);
 751 }
 752
 753 static void
 754 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 755 {
 756         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 757
 758         if (c->istate == CHAN_INPUT_OPEN &&
 759             limit > 0 &&
 760             buffer_len(&c->input) < limit &&
 761             buffer_check_alloc(&c->input, CHAN_RBUF))
 762                 FD_SET(c->rfd, readset);
 763         if (c->ostate == CHAN_OUTPUT_OPEN ||
 764             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 765                 if (buffer_len(&c->output) > 0) {
 766                         FD_SET(c->wfd, writeset);
 767                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 768                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 769                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 770                                     c->self, c->efd, buffer_len(&c->extended));
 771                         else
 772                                 chan_obuf_empty(c);
 773                 }
 774         }
 775         /** XXX check close conditions, too */
 776         if (compat20 && c->efd != -1) {
 777                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 778                     buffer_len(&c->extended) > 0)
 779                         FD_SET(c->efd, writeset);
 780                 else if (!(c->flags & CHAN_EOF_SENT) &&
 781                     c->extended_usage == CHAN_EXTENDED_READ &&
 782                     buffer_len(&c->extended) < c->remote_window)
 783                         FD_SET(c->efd, readset);
 784         }
 785         /* XXX: What about efd? races? */
 786         if (compat20 && c->ctl_fd != -1 &&
 787             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 788                 FD_SET(c->ctl_fd, readset);
 789 }
 790
 791 static void
 792 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 793 {
 794         if (buffer_len(&c->input) == 0) {
 795                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 796                 packet_put_int(c->remote_id);
 797                 packet_send();
 798                 c->type = SSH_CHANNEL_CLOSED;
 799                 debug2("channel %d: closing after input drain.", c->self);
 800         }
 801 }
 802
 803 static void
 804 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 805 {
 806         if (buffer_len(&c->output) == 0)
 807                 chan_mark_dead(c);
 808         else
 809                 FD_SET(c->sock, writeset);
 810 }
 811
 812 /*
 813  * This is a special state for X11 authentication spoofing.  An opened X11
 814  * connection (when authentication spoofing is being done) remains in this
 815  * state until the first packet has been completely read.  The authentication
 816  * data in that packet is then substituted by the real data if it matches the
 817  * fake data, and the channel is put into normal mode.
 818  * XXX All this happens at the client side.
 819  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 820  */
 821 static int
 822 x11_open_helper(Buffer *b)
 823 {
 824         u_char *ucp;
 825         u_int proto_len, data_len;
 826
 827         /* Check if the fixed size part of the packet is in buffer. */
 828         if (buffer_len(b) < 12)
 829                 return 0;
 830
 831         /* Parse the lengths of variable-length fields. */
 832         ucp = buffer_ptr(b);
 833         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 834                 proto_len = 256 * ucp[6] + ucp[7];
 835                 data_len = 256 * ucp[8] + ucp[9];
 836         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 837                 proto_len = ucp[6] + 256 * ucp[7];
 838                 data_len = ucp[8] + 256 * ucp[9];
 839         } else {
 840                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 841                     ucp[0]);
 842                 return -1;
 843         }
 844
 845         /* Check if the whole packet is in buffer. */
 846         if (buffer_len(b) <
 847             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 848                 return 0;
 849
 850         /* Check if authentication protocol matches. */
 851         if (proto_len != strlen(x11_saved_proto) ||
 852             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 853                 debug2("X11 connection uses different authentication protocol.");
 854                 return -1;
 855         }
 856         /* Check if authentication data matches our fake data. */
 857         if (data_len != x11_fake_data_len ||
 858             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 859                 x11_fake_data, x11_fake_data_len) != 0) {
 860                 debug2("X11 auth data does not match fake data.");
 861                 return -1;
 862         }
 863         /* Check fake data length */
 864         if (x11_fake_data_len != x11_saved_data_len) {
 865                 error("X11 fake_data_len %d != saved_data_len %d",
 866                     x11_fake_data_len, x11_saved_data_len);
 867                 return -1;
 868         }
 869         /*
 870          * Received authentication protocol and data match
 871          * our fake data. Substitute the fake data with real
 872          * data.
 873          */
 874         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 875             x11_saved_data, x11_saved_data_len);
 876         return 1;
 877 }
 878
 879 static void
 880 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 881 {
 882         int ret = x11_open_helper(&c->output);
 883
 884         if (ret == 1) {
 885                 /* Start normal processing for the channel. */
 886                 c->type = SSH_CHANNEL_OPEN;
 887                 channel_pre_open_13(c, readset, writeset);
 888         } else if (ret == -1) {
 889                 /*
 890                  * We have received an X11 connection that has bad
 891                  * authentication information.
 892                  */
 893                 logit("X11 connection rejected because of wrong authentication.");
 894                 buffer_clear(&c->input);
 895                 buffer_clear(&c->output);
 896                 channel_close_fd(&c->sock);
 897                 c->sock = -1;
 898                 c->type = SSH_CHANNEL_CLOSED;
 899                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 900                 packet_put_int(c->remote_id);
 901                 packet_send();
 902         }
 903 }
 904
 905 static void
 906 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 907 {
 908         int ret = x11_open_helper(&c->output);
 909
 910         /* c->force_drain = 1; */
 911
 912         if (ret == 1) {
 913                 c->type = SSH_CHANNEL_OPEN;
 914                 channel_pre_open(c, readset, writeset);
 915         } else if (ret == -1) {
 916                 logit("X11 connection rejected because of wrong authentication.");
 917                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 918                 chan_read_failed(c);
 919                 buffer_clear(&c->input);
 920                 chan_ibuf_empty(c);
 921                 buffer_clear(&c->output);
 922                 /* for proto v1, the peer will send an IEOF */
 923                 if (compat20)
 924                         chan_write_failed(c);
 925                 else
 926                         c->type = SSH_CHANNEL_OPEN;
 927                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 928         }
 929 }
 930
 931 /* try to decode a socks4 header */
 932 static int
 933 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 934 {
 935         char *p, *host;
 936         u_int len, have, i, found;
 937         char username[256];
 938         struct {
 939                 u_int8_t version;
 940                 u_int8_t command;
 941                 u_int16_t dest_port;
 942                 struct in_addr dest_addr;
 943         } s4_req, s4_rsp;
 944
 945         debug2("channel %d: decode socks4", c->self);
 946
 947         have = buffer_len(&c->input);
 948         len = sizeof(s4_req);
 949         if (have < len)
 950                 return 0;
 951         p = buffer_ptr(&c->input);
 952         for (found = 0, i = len; i < have; i++) {
 953                 if (p[i] == '\0') {
 954                         found = 1;
 955                         break;
 956                 }
 957                 if (i > 1024) {
 958                         /* the peer is probably sending garbage */
 959                         debug("channel %d: decode socks4: too long",
 960                             c->self);
 961                         return -1;
 962                 }
 963         }
 964         if (!found)
 965                 return 0;
 966         buffer_get(&c->input, (char *)&s4_req.version, 1);
 967         buffer_get(&c->input, (char *)&s4_req.command, 1);
 968         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 969         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 970         have = buffer_len(&c->input);
 971         p = buffer_ptr(&c->input);
 972         len = strlen(p);
 973         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 974         if (len > have)
 975                 fatal("channel %d: decode socks4: len %d > have %d",
 976                     c->self, len, have);
 977         strlcpy(username, p, sizeof(username));
 978         buffer_consume(&c->input, len);
 979         buffer_consume(&c->input, 1);           /* trailing '\0' */
 980
 981         host = inet_ntoa(s4_req.dest_addr);
 982         strlcpy(c->path, host, sizeof(c->path));
 983         c->host_port = ntohs(s4_req.dest_port);
 984
 985         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 986             c->self, host, c->host_port, s4_req.command);
 987
 988         if (s4_req.command != 1) {
 989                 debug("channel %d: cannot handle: socks4 cn %d",
 990                     c->self, s4_req.command);
 991                 return -1;
 992         }
 993         s4_rsp.version = 0;                     /* vn: 0 for reply */
 994         s4_rsp.command = 90;                    /* cd: req granted */
 995         s4_rsp.dest_port = 0;                   /* ignored */
 996         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 997         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
 998         return 1;
 999 }
1000
1001 /* try to decode a socks5 header */
1002 #define SSH_SOCKS5_AUTHDONE     0x1000
1003 #define SSH_SOCKS5_NOAUTH       0x00
1004 #define SSH_SOCKS5_IPV4         0x01
1005 #define SSH_SOCKS5_DOMAIN       0x03
1006 #define SSH_SOCKS5_IPV6         0x04
1007 #define SSH_SOCKS5_CONNECT      0x01
1008 #define SSH_SOCKS5_SUCCESS      0x00
1009
1010 static int
1011 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1012 {
1013         struct {
1014                 u_int8_t version;
1015                 u_int8_t command;
1016                 u_int8_t reserved;
1017                 u_int8_t atyp;
1018         } s5_req, s5_rsp;
1019         u_int16_t dest_port;
1020         u_char *p, dest_addr[255+1];
1021         u_int have, need, i, found, nmethods, addrlen, af;
1022
1023         debug2("channel %d: decode socks5", c->self);
1024         p = buffer_ptr(&c->input);
1025         if (p[0] != 0x05)
1026                 return -1;
1027         have = buffer_len(&c->input);
1028         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1029                 /* format: ver | nmethods | methods */
1030                 if (have < 2)
1031                         return 0;
1032                 nmethods = p[1];
1033                 if (have < nmethods + 2)
1034                         return 0;
1035                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1036                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1037                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
1038                                 found = 1;
1039                                 break;
1040                         }
1041                 }
1042                 if (!found) {
1043                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1044                             c->self);
1045                         return -1;
1046                 }
1047                 buffer_consume(&c->input, nmethods + 2);
1048                 buffer_put_char(&c->output, 0x05);              /* version */
1049                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1050                 FD_SET(c->sock, writeset);
1051                 c->flags |= SSH_SOCKS5_AUTHDONE;
1052                 debug2("channel %d: socks5 auth done", c->self);
1053                 return 0;                               /* need more */
1054         }
1055         debug2("channel %d: socks5 post auth", c->self);
1056         if (have < sizeof(s5_req)+1)
1057                 return 0;                       /* need more */
1058         memcpy(&s5_req, p, sizeof(s5_req));
1059         if (s5_req.version != 0x05 ||
1060             s5_req.command != SSH_SOCKS5_CONNECT ||
1061             s5_req.reserved != 0x00) {
1062                 debug2("channel %d: only socks5 connect supported", c->self);
1063                 return -1;
1064         }
1065         switch (s5_req.atyp){
1066         case SSH_SOCKS5_IPV4:
1067                 addrlen = 4;
1068                 af = AF_INET;
1069                 break;
1070         case SSH_SOCKS5_DOMAIN:
1071                 addrlen = p[sizeof(s5_req)];
1072                 af = -1;
1073                 break;
1074         case SSH_SOCKS5_IPV6:
1075                 addrlen = 16;
1076                 af = AF_INET6;
1077                 break;
1078         default:
1079                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1080                 return -1;
1081         }
1082         need = sizeof(s5_req) + addrlen + 2;
1083         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1084                 need++;
1085         if (have < need)
1086                 return 0;
1087         buffer_consume(&c->input, sizeof(s5_req));
1088         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1089                 buffer_consume(&c->input, 1);    /* host string length */
1090         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1091         buffer_get(&c->input, (char *)&dest_port, 2);
1092         dest_addr[addrlen] = '\0';
1093         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1094                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1095         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1096                 return -1;
1097         c->host_port = ntohs(dest_port);
1098
1099         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1100             c->self, c->path, c->host_port, s5_req.command);
1101
1102         s5_rsp.version = 0x05;
1103         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1104         s5_rsp.reserved = 0;                    /* ignored */
1105         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1106         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1107         dest_port = 0;                          /* ignored */
1108
1109         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1110         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1111         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1112         return 1;
1113 }
1114
1115 /* dynamic port forwarding */
1116 static void
1117 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1118 {
1119         u_char *p;
1120         u_int have;
1121         int ret;
1122
1123         have = buffer_len(&c->input);
1124         c->delayed = 0;
1125         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1126         /* buffer_dump(&c->input); */
1127         /* check if the fixed size part of the packet is in buffer. */
1128         if (have < 3) {
1129                 /* need more */
1130                 FD_SET(c->sock, readset);
1131                 return;
1132         }
1133         /* try to guess the protocol */
1134         p = buffer_ptr(&c->input);
1135         switch (p[0]) {
1136         case 0x04:
1137                 ret = channel_decode_socks4(c, readset, writeset);
1138                 break;
1139         case 0x05:
1140                 ret = channel_decode_socks5(c, readset, writeset);
1141                 break;
1142         default:
1143                 ret = -1;
1144                 break;
1145         }
1146         if (ret < 0) {
1147                 chan_mark_dead(c);
1148         } else if (ret == 0) {
1149                 debug2("channel %d: pre_dynamic: need more", c->self);
1150                 /* need more */
1151                 FD_SET(c->sock, readset);
1152         } else {
1153                 /* switch to the next state */
1154                 c->type = SSH_CHANNEL_OPENING;
1155                 port_open_helper(c, "direct-tcpip");
1156         }
1157 }
1158
1159 /* This is our fake X11 server socket. */
1160 static void
1161 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1162 {
1163         Channel *nc;
1164         struct sockaddr addr;
1165         int newsock;
1166         socklen_t addrlen;
1167         char buf[16384], *remote_ipaddr;
1168         int remote_port;
1169
1170         if (FD_ISSET(c->sock, readset)) {
1171                 debug("X11 connection requested.");
1172                 addrlen = sizeof(addr);
1173                 newsock = accept(c->sock, &addr, &addrlen);
1174                 if (c->single_connection) {
1175                         debug2("single_connection: closing X11 listener.");
1176                         channel_close_fd(&c->sock);
1177                         chan_mark_dead(c);
1178                 }
1179                 if (newsock < 0) {
1180                         error("accept: %.100s", strerror(errno));
1181                         return;
1182                 }
1183                 set_nodelay(newsock);
1184                 remote_ipaddr = get_peer_ipaddr(newsock);
1185                 remote_port = get_peer_port(newsock);
1186                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1187                     remote_ipaddr, remote_port);
1188
1189                 nc = channel_new("accepted x11 socket",
1190                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1191                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1192                 if (compat20) {
1193                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1194                         packet_put_cstring("x11");
1195                         packet_put_int(nc->self);
1196                         packet_put_int(nc->local_window_max);
1197                         packet_put_int(nc->local_maxpacket);
1198                         /* originator ipaddr and port */
1199                         packet_put_cstring(remote_ipaddr);
1200                         if (datafellows & SSH_BUG_X11FWD) {
1201                                 debug2("ssh2 x11 bug compat mode");
1202                         } else {
1203                                 packet_put_int(remote_port);
1204                         }
1205                         packet_send();
1206                 } else {
1207                         packet_start(SSH_SMSG_X11_OPEN);
1208                         packet_put_int(nc->self);
1209                         if (packet_get_protocol_flags() &
1210                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1211                                 packet_put_cstring(buf);
1212                         packet_send();
1213                 }
1214                 xfree(remote_ipaddr);
1215         }
1216 }
1217
1218 static void
1219 port_open_helper(Channel *c, char *rtype)
1220 {
1221         int direct;
1222         char buf[1024];
1223         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1224         int remote_port = get_peer_port(c->sock);
1225
1226         direct = (strcmp(rtype, "direct-tcpip") == 0);
1227
1228         snprintf(buf, sizeof buf,
1229             "%s: listening port %d for %.100s port %d, "
1230             "connect from %.200s port %d",
1231             rtype, c->listening_port, c->path, c->host_port,
1232             remote_ipaddr, remote_port);
1233
1234         xfree(c->remote_name);
1235         c->remote_name = xstrdup(buf);
1236
1237         if (compat20) {
1238                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1239                 packet_put_cstring(rtype);
1240                 packet_put_int(c->self);
1241                 packet_put_int(c->local_window_max);
1242                 packet_put_int(c->local_maxpacket);
1243                 if (direct) {
1244                         /* target host, port */
1245                         packet_put_cstring(c->path);
1246                         packet_put_int(c->host_port);
1247                 } else {
1248                         /* listen address, port */
1249                         packet_put_cstring(c->path);
1250                         packet_put_int(c->listening_port);
1251                 }
1252                 /* originator host and port */
1253                 packet_put_cstring(remote_ipaddr);
1254                 packet_put_int((u_int)remote_port);
1255                 packet_send();
1256         } else {
1257                 packet_start(SSH_MSG_PORT_OPEN);
1258                 packet_put_int(c->self);
1259                 packet_put_cstring(c->path);
1260                 packet_put_int(c->host_port);
1261                 if (packet_get_protocol_flags() &
1262                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1263                         packet_put_cstring(c->remote_name);
1264                 packet_send();
1265         }
1266         xfree(remote_ipaddr);
1267 }
1268
1269 static void
1270 channel_set_reuseaddr(int fd)
1271 {
1272         int on = 1;
1273
1274         /*
1275          * Set socket options.
1276          * Allow local port reuse in TIME_WAIT.
1277          */
1278         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1279                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1280 }
1281
1282 /*
1283  * This socket is listening for connections to a forwarded TCP/IP port.
1284  */
1285 static void
1286 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1287 {
1288         Channel *nc;
1289         struct sockaddr addr;
1290         int newsock, nextstate;
1291         socklen_t addrlen;
1292         char *rtype;
1293
1294         if (FD_ISSET(c->sock, readset)) {
1295                 debug("Connection to port %d forwarding "
1296                     "to %.100s port %d requested.",
1297                     c->listening_port, c->path, c->host_port);
1298
1299                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1300                         nextstate = SSH_CHANNEL_OPENING;
1301                         rtype = "forwarded-tcpip";
1302                 } else {
1303                         if (c->host_port == 0) {
1304                                 nextstate = SSH_CHANNEL_DYNAMIC;
1305                                 rtype = "dynamic-tcpip";
1306                         } else {
1307                                 nextstate = SSH_CHANNEL_OPENING;
1308                                 rtype = "direct-tcpip";
1309                         }
1310                 }
1311
1312                 addrlen = sizeof(addr);
1313                 newsock = accept(c->sock, &addr, &addrlen);
1314                 if (newsock < 0) {
1315                         error("accept: %.100s", strerror(errno));
1316                         return;
1317                 }
1318                 set_nodelay(newsock);
1319                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1320                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1321                 nc->listening_port = c->listening_port;
1322                 nc->host_port = c->host_port;
1323                 strlcpy(nc->path, c->path, sizeof(nc->path));
1324
1325                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1326                         /*
1327                          * do not call the channel_post handler until
1328                          * this flag has been reset by a pre-handler.
1329                          * otherwise the FD_ISSET calls might overflow
1330                          */
1331                         nc->delayed = 1;
1332                 } else {
1333                         port_open_helper(nc, rtype);
1334                 }
1335         }
1336 }
1337
1338 /*
1339  * This is the authentication agent socket listening for connections from
1340  * clients.
1341  */
1342 static void
1343 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1344 {
1345         Channel *nc;
1346         int newsock;
1347         struct sockaddr addr;
1348         socklen_t addrlen;
1349
1350         if (FD_ISSET(c->sock, readset)) {
1351                 addrlen = sizeof(addr);
1352                 newsock = accept(c->sock, &addr, &addrlen);
1353                 if (newsock < 0) {
1354                         error("accept from auth socket: %.100s", strerror(errno));
1355                         return;
1356                 }
1357                 nc = channel_new("accepted auth socket",
1358                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1359                     c->local_window_max, c->local_maxpacket,
1360                     0, "accepted auth socket", 1);
1361                 if (compat20) {
1362                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1363                         packet_put_cstring("auth-agent@openssh.com");
1364                         packet_put_int(nc->self);
1365                         packet_put_int(c->local_window_max);
1366                         packet_put_int(c->local_maxpacket);
1367                 } else {
1368                         packet_start(SSH_SMSG_AGENT_OPEN);
1369                         packet_put_int(nc->self);
1370                 }
1371                 packet_send();
1372         }
1373 }
1374
1375 static void
1376 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1377 {
1378         int err = 0;
1379         socklen_t sz = sizeof(err);
1380
1381         if (FD_ISSET(c->sock, writeset)) {
1382                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1383                         err = errno;
1384                         error("getsockopt SO_ERROR failed");
1385                 }
1386                 if (err == 0) {
1387                         debug("channel %d: connected", c->self);
1388                         c->type = SSH_CHANNEL_OPEN;
1389                         if (compat20) {
1390                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1391                                 packet_put_int(c->remote_id);
1392                                 packet_put_int(c->self);
1393                                 packet_put_int(c->local_window);
1394                                 packet_put_int(c->local_maxpacket);
1395                         } else {
1396                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1397                                 packet_put_int(c->remote_id);
1398                                 packet_put_int(c->self);
1399                         }
1400                 } else {
1401                         debug("channel %d: not connected: %s",
1402                             c->self, strerror(err));
1403                         if (compat20) {
1404                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1405                                 packet_put_int(c->remote_id);
1406                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1407                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1408                                         packet_put_cstring(strerror(err));
1409                                         packet_put_cstring("");
1410                                 }
1411                         } else {
1412                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1413                                 packet_put_int(c->remote_id);
1414                         }
1415                         chan_mark_dead(c);
1416                 }
1417                 packet_send();
1418         }
1419 }
1420
1421 static int
1422 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1423 {
1424         char buf[CHAN_RBUF];
1425         int len;
1426
1427         if (c->rfd != -1 &&
1428             FD_ISSET(c->rfd, readset)) {
1429                 errno = 0;
1430                 len = read(c->rfd, buf, sizeof(buf));
1431                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1432                         return 1;
1433 #ifndef PTY_ZEROREAD
1434                 if (len <= 0) {
1435 #else
1436                 if ((!c->isatty && len <= 0) ||
1437                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1438 #endif
1439                         debug2("channel %d: read<=0 rfd %d len %d",
1440                             c->self, c->rfd, len);
1441                         if (c->type != SSH_CHANNEL_OPEN) {
1442                                 debug2("channel %d: not open", c->self);
1443                                 chan_mark_dead(c);
1444                                 return -1;
1445                         } else if (compat13) {
1446                                 buffer_clear(&c->output);
1447                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1448                                 debug2("channel %d: input draining.", c->self);
1449                         } else {
1450                                 chan_read_failed(c);
1451                         }
1452                         return -1;
1453                 }
1454                 if (c->input_filter != NULL) {
1455                         if (c->input_filter(c, buf, len) == -1) {
1456                                 debug2("channel %d: filter stops", c->self);
1457                                 chan_read_failed(c);
1458                         }
1459                 } else if (c->datagram) {
1460                         buffer_put_string(&c->input, buf, len);
1461                 } else {
1462                         buffer_append(&c->input, buf, len);
1463                 }
1464         }
1465         return 1;
1466 }
1467
1468 static int
1469 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1470 {
1471         struct termios tio;
1472         u_char *data = NULL, *buf;
1473         u_int dlen;
1474         int len;
1475
1476         /* Send buffered output data to the socket. */
1477         if (c->wfd != -1 &&
1478             FD_ISSET(c->wfd, writeset) &&
1479             buffer_len(&c->output) > 0) {
1480                 if (c->output_filter != NULL) {
1481                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1482                                 debug2("channel %d: filter stops", c->self);
1483                                 if (c->type != SSH_CHANNEL_OPEN)
1484                                         chan_mark_dead(c);
1485                                 else
1486                                         chan_write_failed(c);
1487                                 return -1;
1488                         }
1489                 } else if (c->datagram) {
1490                         buf = data = buffer_get_string(&c->output, &dlen);
1491                 } else {
1492                         buf = data = buffer_ptr(&c->output);
1493                         dlen = buffer_len(&c->output);
1494                 }
1495
1496                 if (c->datagram) {
1497                         /* ignore truncated writes, datagrams might get lost */
1498                         c->local_consumed += dlen + 4;
1499                         len = write(c->wfd, buf, dlen);
1500                         xfree(data);
1501                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1502                                 return 1;
1503                         if (len <= 0) {
1504                                 if (c->type != SSH_CHANNEL_OPEN)
1505                                         chan_mark_dead(c);
1506                                 else
1507                                         chan_write_failed(c);
1508                                 return -1;
1509                         }
1510                         return 1;
1511                 }
1512 #ifdef _AIX
1513                 /* XXX: Later AIX versions can't push as much data to tty */
1514                 if (compat20 && c->wfd_isatty)
1515                         dlen = MIN(dlen, 8*1024);
1516 #endif
1517
1518                 len = write(c->wfd, buf, dlen);
1519                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1520                         return 1;
1521                 if (len <= 0) {
1522                         if (c->type != SSH_CHANNEL_OPEN) {
1523                                 debug2("channel %d: not open", c->self);
1524                                 chan_mark_dead(c);
1525                                 return -1;
1526                         } else if (compat13) {
1527                                 buffer_clear(&c->output);
1528                                 debug2("channel %d: input draining.", c->self);
1529                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1530                         } else {
1531                                 chan_write_failed(c);
1532                         }
1533                         return -1;
1534                 }
1535                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1536                         if (tcgetattr(c->wfd, &tio) == 0 &&
1537                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1538                                 /*
1539                                  * Simulate echo to reduce the impact of
1540                                  * traffic analysis. We need to match the
1541                                  * size of a SSH2_MSG_CHANNEL_DATA message
1542                                  * (4 byte channel id + buf)
1543                                  */
1544                                 packet_send_ignore(4 + len);
1545                                 packet_send();
1546                         }
1547                 }
1548                 buffer_consume(&c->output, len);
1549                 if (compat20 && len > 0) {
1550                         c->local_consumed += len;
1551                 }
1552         }
1553         return 1;
1554 }
1555
1556 static int
1557 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1558 {
1559         char buf[CHAN_RBUF];
1560         int len;
1561
1562 /** XXX handle drain efd, too */
1563         if (c->efd != -1) {
1564                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1565                     FD_ISSET(c->efd, writeset) &&
1566                     buffer_len(&c->extended) > 0) {
1567                         len = write(c->efd, buffer_ptr(&c->extended),
1568                             buffer_len(&c->extended));
1569                         debug2("channel %d: written %d to efd %d",
1570                             c->self, len, c->efd);
1571                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1572                                 return 1;
1573                         if (len <= 0) {
1574                                 debug2("channel %d: closing write-efd %d",
1575                                     c->self, c->efd);
1576                                 channel_close_fd(&c->efd);
1577                         } else {
1578                                 buffer_consume(&c->extended, len);
1579                                 c->local_consumed += len;
1580                         }
1581                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1582                     FD_ISSET(c->efd, readset)) {
1583                         len = read(c->efd, buf, sizeof(buf));
1584                         debug2("channel %d: read %d from efd %d",
1585                             c->self, len, c->efd);
1586                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1587                                 return 1;
1588                         if (len <= 0) {
1589                                 debug2("channel %d: closing read-efd %d",
1590                                     c->self, c->efd);
1591                                 channel_close_fd(&c->efd);
1592                         } else {
1593                                 buffer_append(&c->extended, buf, len);
1594                         }
1595                 }
1596         }
1597         return 1;
1598 }
1599
1600 static int
1601 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1602 {
1603         char buf[16];
1604         int len;
1605
1606         /* Monitor control fd to detect if the slave client exits */
1607         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1608                 len = read(c->ctl_fd, buf, sizeof(buf));
1609                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1610                         return 1;
1611                 if (len <= 0) {
1612                         debug2("channel %d: ctl read<=0", c->self);
1613                         if (c->type != SSH_CHANNEL_OPEN) {
1614                                 debug2("channel %d: not open", c->self);
1615                                 chan_mark_dead(c);
1616                                 return -1;
1617                         } else {
1618                                 chan_read_failed(c);
1619                                 chan_write_failed(c);
1620                         }
1621                         return -1;
1622                 } else
1623                         fatal("%s: unexpected data on ctl fd", __func__);
1624         }
1625         return 1;
1626 }
1627
1628 static int
1629 channel_check_window(Channel *c)
1630 {
1631         if (c->type == SSH_CHANNEL_OPEN &&
1632             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1633             c->local_window < c->local_window_max/2 &&
1634             c->local_consumed > 0) {
1635                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1636                 packet_put_int(c->remote_id);
1637                 packet_put_int(c->local_consumed);
1638                 packet_send();
1639                 debug2("channel %d: window %d sent adjust %d",
1640                     c->self, c->local_window,
1641                     c->local_consumed);
1642                 c->local_window += c->local_consumed;
1643                 c->local_consumed = 0;
1644         }
1645         return 1;
1646 }
1647
1648 static void
1649 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1650 {
1651         if (c->delayed)
1652                 return;
1653         channel_handle_rfd(c, readset, writeset);
1654         channel_handle_wfd(c, readset, writeset);
1655         if (!compat20)
1656                 return;
1657         channel_handle_efd(c, readset, writeset);
1658         channel_handle_ctl(c, readset, writeset);
1659         channel_check_window(c);
1660 }
1661
1662 static void
1663 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1664 {
1665         int len;
1666
1667         /* Send buffered output data to the socket. */
1668         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1669                 len = write(c->sock, buffer_ptr(&c->output),
1670                             buffer_len(&c->output));
1671                 if (len <= 0)
1672                         buffer_clear(&c->output);
1673                 else
1674                         buffer_consume(&c->output, len);
1675         }
1676 }
1677
1678 static void
1679 channel_handler_init_20(void)
1680 {
1681         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1682         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1683         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1684         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1685         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1686         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1687         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1688         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1689
1690         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1691         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1692         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1693         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1694         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1695         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1696         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1697 }
1698
1699 static void
1700 channel_handler_init_13(void)
1701 {
1702         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1703         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1704         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1705         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1706         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1707         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1708         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1709         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1710         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1711
1712         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1713         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1714         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1715         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1716         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1717         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1718         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1719 }
1720
1721 static void
1722 channel_handler_init_15(void)
1723 {
1724         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1725         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1726         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1727         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1728         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1729         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1730         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1731
1732         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1733         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1734         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1735         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1736         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1737         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1738 }
1739
1740 static void
1741 channel_handler_init(void)
1742 {
1743         int i;
1744
1745         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1746                 channel_pre[i] = NULL;
1747                 channel_post[i] = NULL;
1748         }
1749         if (compat20)
1750                 channel_handler_init_20();
1751         else if (compat13)
1752                 channel_handler_init_13();
1753         else
1754                 channel_handler_init_15();
1755 }
1756
1757 /* gc dead channels */
1758 static void
1759 channel_garbage_collect(Channel *c)
1760 {
1761         if (c == NULL)
1762                 return;
1763         if (c->detach_user != NULL) {
1764                 if (!chan_is_dead(c, c->detach_close))
1765                         return;
1766                 debug2("channel %d: gc: notify user", c->self);
1767                 c->detach_user(c->self, NULL);
1768                 /* if we still have a callback */
1769                 if (c->detach_user != NULL)
1770                         return;
1771                 debug2("channel %d: gc: user detached", c->self);
1772         }
1773         if (!chan_is_dead(c, 1))
1774                 return;
1775         debug2("channel %d: garbage collecting", c->self);
1776         channel_free(c);
1777 }
1778
1779 static void
1780 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1781 {
1782         static int did_init = 0;
1783         u_int i;
1784         Channel *c;
1785
1786         if (!did_init) {
1787                 channel_handler_init();
1788                 did_init = 1;
1789         }
1790         for (i = 0; i < channels_alloc; i++) {
1791                 c = channels[i];
1792                 if (c == NULL)
1793                         continue;
1794                 if (ftab[c->type] != NULL)
1795                         (*ftab[c->type])(c, readset, writeset);
1796                 channel_garbage_collect(c);
1797         }
1798 }
1799
1800 /*
1801  * Allocate/update select bitmasks and add any bits relevant to channels in
1802  * select bitmasks.
1803  */
1804 void
1805 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1806     u_int *nallocp, int rekeying)
1807 {
1808         u_int n, sz, nfdset;
1809
1810         n = MAX(*maxfdp, channel_max_fd);
1811
1812         nfdset = howmany(n+1, NFDBITS);
1813         /* Explicitly test here, because xrealloc isn't always called */
1814         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1815                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1816         sz = nfdset * sizeof(fd_mask);
1817
1818         /* perhaps check sz < nalloc/2 and shrink? */
1819         if (*readsetp == NULL || sz > *nallocp) {
1820                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1821                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1822                 *nallocp = sz;
1823         }
1824         *maxfdp = n;
1825         memset(*readsetp, 0, sz);
1826         memset(*writesetp, 0, sz);
1827
1828         if (!rekeying)
1829                 channel_handler(channel_pre, *readsetp, *writesetp);
1830 }
1831
1832 /*
1833  * After select, perform any appropriate operations for channels which have
1834  * events pending.
1835  */
1836 void
1837 channel_after_select(fd_set *readset, fd_set *writeset)
1838 {
1839         channel_handler(channel_post, readset, writeset);
1840 }
1841
1842
1843 /* If there is data to send to the connection, enqueue some of it now. */
1844 void
1845 channel_output_poll(void)
1846 {
1847         Channel *c;
1848         u_int i, len;
1849
1850         for (i = 0; i < channels_alloc; i++) {
1851                 c = channels[i];
1852                 if (c == NULL)
1853                         continue;
1854
1855                 /*
1856                  * We are only interested in channels that can have buffered
1857                  * incoming data.
1858                  */
1859                 if (compat13) {
1860                         if (c->type != SSH_CHANNEL_OPEN &&
1861                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1862                                 continue;
1863                 } else {
1864                         if (c->type != SSH_CHANNEL_OPEN)
1865                                 continue;
1866                 }
1867                 if (compat20 &&
1868                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1869                         /* XXX is this true? */
1870                         debug3("channel %d: will not send data after close", c->self);
1871                         continue;
1872                 }
1873
1874                 /* Get the amount of buffered data for this channel. */
1875                 if ((c->istate == CHAN_INPUT_OPEN ||
1876                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1877                     (len = buffer_len(&c->input)) > 0) {
1878                         if (c->datagram) {
1879                                 if (len > 0) {
1880                                         u_char *data;
1881                                         u_int dlen;
1882
1883                                         data = buffer_get_string(&c->input,
1884                                             &dlen);
1885                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1886                                         packet_put_int(c->remote_id);
1887                                         packet_put_string(data, dlen);
1888                                         packet_send();
1889                                         c->remote_window -= dlen + 4;
1890                                         xfree(data);
1891                                 }
1892                                 continue;
1893                         }
1894                         /*
1895                          * Send some data for the other side over the secure
1896                          * connection.
1897                          */
1898                         if (compat20) {
1899                                 if (len > c->remote_window)
1900                                         len = c->remote_window;
1901                                 if (len > c->remote_maxpacket)
1902                                         len = c->remote_maxpacket;
1903                         } else {
1904                                 if (packet_is_interactive()) {
1905                                         if (len > 1024)
1906                                                 len = 512;
1907                                 } else {
1908                                         /* Keep the packets at reasonable size. */
1909                                         if (len > packet_get_maxsize()/2)
1910                                                 len = packet_get_maxsize()/2;
1911                                 }
1912                         }
1913                         if (len > 0) {
1914                                 packet_start(compat20 ?
1915                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1916                                 packet_put_int(c->remote_id);
1917                                 packet_put_string(buffer_ptr(&c->input), len);
1918                                 packet_send();
1919                                 buffer_consume(&c->input, len);
1920                                 c->remote_window -= len;
1921                         }
1922                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1923                         if (compat13)
1924                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1925                         /*
1926                          * input-buffer is empty and read-socket shutdown:
1927                          * tell peer, that we will not send more data: send IEOF.
1928                          * hack for extended data: delay EOF if EFD still in use.
1929                          */
1930                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1931                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1932                                     c->self, c->efd, buffer_len(&c->extended));
1933                         else
1934                                 chan_ibuf_empty(c);
1935                 }
1936                 /* Send extended data, i.e. stderr */
1937                 if (compat20 &&
1938                     !(c->flags & CHAN_EOF_SENT) &&
1939                     c->remote_window > 0 &&
1940                     (len = buffer_len(&c->extended)) > 0 &&
1941                     c->extended_usage == CHAN_EXTENDED_READ) {
1942                         debug2("channel %d: rwin %u elen %u euse %d",
1943                             c->self, c->remote_window, buffer_len(&c->extended),
1944                             c->extended_usage);
1945                         if (len > c->remote_window)
1946                                 len = c->remote_window;
1947                         if (len > c->remote_maxpacket)
1948                                 len = c->remote_maxpacket;
1949                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1950                         packet_put_int(c->remote_id);
1951                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1952                         packet_put_string(buffer_ptr(&c->extended), len);
1953                         packet_send();
1954                         buffer_consume(&c->extended, len);
1955                         c->remote_window -= len;
1956                         debug2("channel %d: sent ext data %d", c->self, len);
1957                 }
1958         }
1959 }
1960
1961
1962 /* -- protocol input */
1963
1964 /* ARGSUSED */
1965 void
1966 channel_input_data(int type, u_int32_t seq, void *ctxt)
1967 {
1968         int id;
1969         char *data;
1970         u_int data_len;
1971         Channel *c;
1972
1973         /* Get the channel number and verify it. */
1974         id = packet_get_int();
1975         c = channel_lookup(id);
1976         if (c == NULL)
1977                 packet_disconnect("Received data for nonexistent channel %d.", id);
1978
1979         /* Ignore any data for non-open channels (might happen on close) */
1980         if (c->type != SSH_CHANNEL_OPEN &&
1981             c->type != SSH_CHANNEL_X11_OPEN)
1982                 return;
1983
1984         /* Get the data. */
1985         data = packet_get_string(&data_len);
1986
1987         /*
1988          * Ignore data for protocol > 1.3 if output end is no longer open.
1989          * For protocol 2 the sending side is reducing its window as it sends
1990          * data, so we must 'fake' consumption of the data in order to ensure
1991          * that window updates are sent back.  Otherwise the connection might
1992          * deadlock.
1993          */
1994         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1995                 if (compat20) {
1996                         c->local_window -= data_len;
1997                         c->local_consumed += data_len;
1998                 }
1999                 xfree(data);
2000                 return;
2001         }
2002
2003         if (compat20) {
2004                 if (data_len > c->local_maxpacket) {
2005                         logit("channel %d: rcvd big packet %d, maxpack %d",
2006                             c->self, data_len, c->local_maxpacket);
2007                 }
2008                 if (data_len > c->local_window) {
2009                         logit("channel %d: rcvd too much data %d, win %d",
2010                             c->self, data_len, c->local_window);
2011                         xfree(data);
2012                         return;
2013                 }
2014                 c->local_window -= data_len;
2015         }
2016         packet_check_eom();
2017         if (c->datagram)
2018                 buffer_put_string(&c->output, data, data_len);
2019         else
2020                 buffer_append(&c->output, data, data_len);
2021         xfree(data);
2022 }
2023
2024 /* ARGSUSED */
2025 void
2026 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2027 {
2028         int id;
2029         char *data;
2030         u_int data_len, tcode;
2031         Channel *c;
2032
2033         /* Get the channel number and verify it. */
2034         id = packet_get_int();
2035         c = channel_lookup(id);
2036
2037         if (c == NULL)
2038                 packet_disconnect("Received extended_data for bad channel %d.", id);
2039         if (c->type != SSH_CHANNEL_OPEN) {
2040                 logit("channel %d: ext data for non open", id);
2041                 return;
2042         }
2043         if (c->flags & CHAN_EOF_RCVD) {
2044                 if (datafellows & SSH_BUG_EXTEOF)
2045                         debug("channel %d: accepting ext data after eof", id);
2046                 else
2047                         packet_disconnect("Received extended_data after EOF "
2048                             "on channel %d.", id);
2049         }
2050         tcode = packet_get_int();
2051         if (c->efd == -1 ||
2052             c->extended_usage != CHAN_EXTENDED_WRITE ||
2053             tcode != SSH2_EXTENDED_DATA_STDERR) {
2054                 logit("channel %d: bad ext data", c->self);
2055                 return;
2056         }
2057         data = packet_get_string(&data_len);
2058         packet_check_eom();
2059         if (data_len > c->local_window) {
2060                 logit("channel %d: rcvd too much extended_data %d, win %d",
2061                     c->self, data_len, c->local_window);
2062                 xfree(data);
2063                 return;
2064         }
2065         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2066         c->local_window -= data_len;
2067         buffer_append(&c->extended, data, data_len);
2068         xfree(data);
2069 }
2070
2071 /* ARGSUSED */
2072 void
2073 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2074 {
2075         int id;
2076         Channel *c;
2077
2078         id = packet_get_int();
2079         packet_check_eom();
2080         c = channel_lookup(id);
2081         if (c == NULL)
2082                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2083         chan_rcvd_ieof(c);
2084
2085         /* XXX force input close */
2086         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2087                 debug("channel %d: FORCE input drain", c->self);
2088                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2089                 if (buffer_len(&c->input) == 0)
2090                         chan_ibuf_empty(c);
2091         }
2092
2093 }
2094
2095 /* ARGSUSED */
2096 void
2097 channel_input_close(int type, u_int32_t seq, void *ctxt)
2098 {
2099         int id;
2100         Channel *c;
2101
2102         id = packet_get_int();
2103         packet_check_eom();
2104         c = channel_lookup(id);
2105         if (c == NULL)
2106                 packet_disconnect("Received close for nonexistent channel %d.", id);
2107
2108         /*
2109          * Send a confirmation that we have closed the channel and no more
2110          * data is coming for it.
2111          */
2112         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2113         packet_put_int(c->remote_id);
2114         packet_send();
2115
2116         /*
2117          * If the channel is in closed state, we have sent a close request,
2118          * and the other side will eventually respond with a confirmation.
2119          * Thus, we cannot free the channel here, because then there would be
2120          * no-one to receive the confirmation.  The channel gets freed when
2121          * the confirmation arrives.
2122          */
2123         if (c->type != SSH_CHANNEL_CLOSED) {
2124                 /*
2125                  * Not a closed channel - mark it as draining, which will
2126                  * cause it to be freed later.
2127                  */
2128                 buffer_clear(&c->input);
2129                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2130         }
2131 }
2132
2133 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2134 /* ARGSUSED */
2135 void
2136 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2137 {
2138         int id = packet_get_int();
2139         Channel *c = channel_lookup(id);
2140
2141         packet_check_eom();
2142         if (c == NULL)
2143                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2144         chan_rcvd_oclose(c);
2145 }
2146
2147 /* ARGSUSED */
2148 void
2149 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2150 {
2151         int id = packet_get_int();
2152         Channel *c = channel_lookup(id);
2153
2154         packet_check_eom();
2155         if (c == NULL)
2156                 packet_disconnect("Received close confirmation for "
2157                     "out-of-range channel %d.", id);
2158         if (c->type != SSH_CHANNEL_CLOSED)
2159                 packet_disconnect("Received close confirmation for "
2160                     "non-closed channel %d (type %d).", id, c->type);
2161         channel_free(c);
2162 }
2163
2164 /* ARGSUSED */
2165 void
2166 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2167 {
2168         int id, remote_id;
2169         Channel *c;
2170
2171         id = packet_get_int();
2172         c = channel_lookup(id);
2173
2174         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2175                 packet_disconnect("Received open confirmation for "
2176                     "non-opening channel %d.", id);
2177         remote_id = packet_get_int();
2178         /* Record the remote channel number and mark that the channel is now open. */
2179         c->remote_id = remote_id;
2180         c->type = SSH_CHANNEL_OPEN;
2181
2182         if (compat20) {
2183                 c->remote_window = packet_get_int();
2184                 c->remote_maxpacket = packet_get_int();
2185                 if (c->confirm) {
2186                         debug2("callback start");
2187                         c->confirm(c->self, c->confirm_ctx);
2188                         debug2("callback done");
2189                 }
2190                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2191                     c->remote_window, c->remote_maxpacket);
2192         }
2193         packet_check_eom();
2194 }
2195
2196 static char *
2197 reason2txt(int reason)
2198 {
2199         switch (reason) {
2200         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2201                 return "administratively prohibited";
2202         case SSH2_OPEN_CONNECT_FAILED:
2203                 return "connect failed";
2204         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2205                 return "unknown channel type";
2206         case SSH2_OPEN_RESOURCE_SHORTAGE:
2207                 return "resource shortage";
2208         }
2209         return "unknown reason";
2210 }
2211
2212 /* ARGSUSED */
2213 void
2214 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2215 {
2216         int id, reason;
2217         char *msg = NULL, *lang = NULL;
2218         Channel *c;
2219
2220         id = packet_get_int();
2221         c = channel_lookup(id);
2222
2223         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2224                 packet_disconnect("Received open failure for "
2225                     "non-opening channel %d.", id);
2226         if (compat20) {
2227                 reason = packet_get_int();
2228                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2229                         msg  = packet_get_string(NULL);
2230                         lang = packet_get_string(NULL);
2231                 }
2232                 logit("channel %d: open failed: %s%s%s", id,
2233                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2234                 if (msg != NULL)
2235                         xfree(msg);
2236                 if (lang != NULL)
2237                         xfree(lang);
2238         }
2239         packet_check_eom();
2240         /* Free the channel.  This will also close the socket. */
2241         channel_free(c);
2242 }
2243
2244 /* ARGSUSED */
2245 void
2246 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2247 {
2248         Channel *c;
2249         int id;
2250         u_int adjust;
2251
2252         if (!compat20)
2253                 return;
2254
2255         /* Get the channel number and verify it. */
2256         id = packet_get_int();
2257         c = channel_lookup(id);
2258
2259         if (c == NULL) {
2260                 logit("Received window adjust for non-open channel %d.", id);
2261                 return;
2262         }
2263         adjust = packet_get_int();
2264         packet_check_eom();
2265         debug2("channel %d: rcvd adjust %u", id, adjust);
2266         c->remote_window += adjust;
2267 }
2268
2269 /* ARGSUSED */
2270 void
2271 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2272 {
2273         Channel *c = NULL;
2274         u_short host_port;
2275         char *host, *originator_string;
2276         int remote_id, sock = -1;
2277
2278         remote_id = packet_get_int();
2279         host = packet_get_string(NULL);
2280         host_port = packet_get_int();
2281
2282         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2283                 originator_string = packet_get_string(NULL);
2284         } else {
2285                 originator_string = xstrdup("unknown (remote did not supply name)");
2286         }
2287         packet_check_eom();
2288         sock = channel_connect_to(host, host_port);
2289         if (sock != -1) {
2290                 c = channel_new("connected socket",
2291                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2292                     originator_string, 1);
2293                 c->remote_id = remote_id;
2294         }
2295         xfree(originator_string);
2296         if (c == NULL) {
2297                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2298                 packet_put_int(remote_id);
2299                 packet_send();
2300         }
2301         xfree(host);
2302 }
2303
2304
2305 /* -- tcp forwarding */
2306
2307 void
2308 channel_set_af(int af)
2309 {
2310         IPv4or6 = af;
2311 }
2312
2313 static int
2314 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2315     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2316 {
2317         Channel *c;
2318         int sock, r, success = 0, wildcard = 0, is_client;
2319         struct addrinfo hints, *ai, *aitop;
2320         const char *host, *addr;
2321         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2322
2323         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2324             listen_addr : host_to_connect;
2325         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2326
2327         if (host == NULL) {
2328                 error("No forward host name.");
2329                 return 0;
2330         }
2331         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2332                 error("Forward host name too long.");
2333                 return 0;
2334         }
2335
2336         /*
2337          * Determine whether or not a port forward listens to loopback,
2338          * specified address or wildcard. On the client, a specified bind
2339          * address will always override gateway_ports. On the server, a
2340          * gateway_ports of 1 (``yes'') will override the client's
2341          * specification and force a wildcard bind, whereas a value of 2
2342          * (``clientspecified'') will bind to whatever address the client
2343          * asked for.
2344          *
2345          * Special-case listen_addrs are:
2346          *
2347          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2348          * "" (empty string), "*"  -> wildcard v4/v6
2349          * "localhost"             -> loopback v4/v6
2350          */
2351         addr = NULL;
2352         if (listen_addr == NULL) {
2353                 /* No address specified: default to gateway_ports setting */
2354                 if (gateway_ports)
2355                         wildcard = 1;
2356         } else if (gateway_ports || is_client) {
2357                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2358                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2359                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2360                     (!is_client && gateway_ports == 1))
2361                         wildcard = 1;
2362                 else if (strcmp(listen_addr, "localhost") != 0)
2363                         addr = listen_addr;
2364         }
2365
2366         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2367             type, wildcard, (addr == NULL) ? "NULL" : addr);
2368
2369         /*
2370          * getaddrinfo returns a loopback address if the hostname is
2371          * set to NULL and hints.ai_flags is not AI_PASSIVE
2372          */
2373         memset(&hints, 0, sizeof(hints));
2374         hints.ai_family = IPv4or6;
2375         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2376         hints.ai_socktype = SOCK_STREAM;
2377         snprintf(strport, sizeof strport, "%d", listen_port);
2378         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2379                 if (addr == NULL) {
2380                         /* This really shouldn't happen */
2381                         packet_disconnect("getaddrinfo: fatal error: %s",
2382                             gai_strerror(r));
2383                 } else {
2384                         error("channel_setup_fwd_listener: "
2385                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2386                 }
2387                 return 0;
2388         }
2389
2390         for (ai = aitop; ai; ai = ai->ai_next) {
2391                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2392                         continue;
2393                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2394                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2395                         error("channel_setup_fwd_listener: getnameinfo failed");
2396                         continue;
2397                 }
2398                 /* Create a port to listen for the host. */
2399                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2400                 if (sock < 0) {
2401                         /* this is no error since kernel may not support ipv6 */
2402                         verbose("socket: %.100s", strerror(errno));
2403                         continue;
2404                 }
2405
2406                 channel_set_reuseaddr(sock);
2407
2408                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2409
2410                 /* Bind the socket to the address. */
2411                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2412                         /* address can be in use ipv6 address is already bound */
2413                         if (!ai->ai_next)
2414                                 error("bind: %.100s", strerror(errno));
2415                         else
2416                                 verbose("bind: %.100s", strerror(errno));
2417
2418                         close(sock);
2419                         continue;
2420                 }
2421                 /* Start listening for connections on the socket. */
2422                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2423                         error("listen: %.100s", strerror(errno));
2424                         close(sock);
2425                         continue;
2426                 }
2427                 /* Allocate a channel number for the socket. */
2428                 c = channel_new("port listener", type, sock, sock, -1,
2429                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2430                     0, "port listener", 1);
2431                 strlcpy(c->path, host, sizeof(c->path));
2432                 c->host_port = port_to_connect;
2433                 c->listening_port = listen_port;
2434                 success = 1;
2435         }
2436         if (success == 0)
2437                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2438                     listen_port);
2439         freeaddrinfo(aitop);
2440         return success;
2441 }
2442
2443 int
2444 channel_cancel_rport_listener(const char *host, u_short port)
2445 {
2446         u_int i;
2447         int found = 0;
2448
2449         for (i = 0; i < channels_alloc; i++) {
2450                 Channel *c = channels[i];
2451
2452                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2453                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2454                     c->listening_port == port) {
2455                         debug2("%s: close channel %d", __func__, i);
2456                         channel_free(c);
2457                         found = 1;
2458                 }
2459         }
2460
2461         return (found);
2462 }
2463
2464 /* protocol local port fwd, used by ssh (and sshd in v1) */
2465 int
2466 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2467     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2468 {
2469         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2470             listen_host, listen_port, host_to_connect, port_to_connect,
2471             gateway_ports);
2472 }
2473
2474 /* protocol v2 remote port fwd, used by sshd */
2475 int
2476 channel_setup_remote_fwd_listener(const char *listen_address,
2477     u_short listen_port, int gateway_ports)
2478 {
2479         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2480             listen_address, listen_port, NULL, 0, gateway_ports);
2481 }
2482
2483 /*
2484  * Initiate forwarding of connections to port "port" on remote host through
2485  * the secure channel to host:port from local side.
2486  */
2487
2488 int
2489 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2490     const char *host_to_connect, u_short port_to_connect)
2491 {
2492         int type, success = 0;
2493
2494         /* Record locally that connection to this host/port is permitted. */
2495         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2496                 fatal("channel_request_remote_forwarding: too many forwards");
2497
2498         /* Send the forward request to the remote side. */
2499         if (compat20) {
2500                 const char *address_to_bind;
2501                 if (listen_host == NULL)
2502                         address_to_bind = "localhost";
2503                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2504                         address_to_bind = "";
2505                 else
2506                         address_to_bind = listen_host;
2507
2508                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2509                 packet_put_cstring("tcpip-forward");
2510                 packet_put_char(1);                     /* boolean: want reply */
2511                 packet_put_cstring(address_to_bind);
2512                 packet_put_int(listen_port);
2513                 packet_send();
2514                 packet_write_wait();
2515                 /* Assume that server accepts the request */
2516                 success = 1;
2517         } else {
2518                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2519                 packet_put_int(listen_port);
2520                 packet_put_cstring(host_to_connect);
2521                 packet_put_int(port_to_connect);
2522                 packet_send();
2523                 packet_write_wait();
2524
2525                 /* Wait for response from the remote side. */
2526                 type = packet_read();
2527                 switch (type) {
2528                 case SSH_SMSG_SUCCESS:
2529                         success = 1;
2530                         break;
2531                 case SSH_SMSG_FAILURE:
2532                         break;
2533                 default:
2534                         /* Unknown packet */
2535                         packet_disconnect("Protocol error for port forward request:"
2536                             "received packet type %d.", type);
2537                 }
2538         }
2539         if (success) {
2540                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2541                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2542                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2543                 num_permitted_opens++;
2544         }
2545         return (success ? 0 : -1);
2546 }
2547
2548 /*
2549  * Request cancellation of remote forwarding of connection host:port from
2550  * local side.
2551  */
2552 void
2553 channel_request_rforward_cancel(const char *host, u_short port)
2554 {
2555         int i;
2556
2557         if (!compat20)
2558                 return;
2559
2560         for (i = 0; i < num_permitted_opens; i++) {
2561                 if (permitted_opens[i].host_to_connect != NULL &&
2562                     permitted_opens[i].listen_port == port)
2563                         break;
2564         }
2565         if (i >= num_permitted_opens) {
2566                 debug("%s: requested forward not found", __func__);
2567                 return;
2568         }
2569         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2570         packet_put_cstring("cancel-tcpip-forward");
2571         packet_put_char(0);
2572         packet_put_cstring(host == NULL ? "" : host);
2573         packet_put_int(port);
2574         packet_send();
2575
2576         permitted_opens[i].listen_port = 0;
2577         permitted_opens[i].port_to_connect = 0;
2578         xfree(permitted_opens[i].host_to_connect);
2579         permitted_opens[i].host_to_connect = NULL;
2580 }
2581
2582 /*
2583  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2584  * listening for the port, and sends back a success reply (or disconnect
2585  * message if there was an error).
2586  */
2587 int
2588 channel_input_port_forward_request(int is_root, int gateway_ports)
2589 {
2590         u_short port, host_port;
2591         int success = 0;
2592         char *hostname;
2593
2594         /* Get arguments from the packet. */
2595         port = packet_get_int();
2596         hostname = packet_get_string(NULL);
2597         host_port = packet_get_int();
2598
2599 #ifndef HAVE_CYGWIN
2600         /*
2601          * Check that an unprivileged user is not trying to forward a
2602          * privileged port.
2603          */
2604         if (port < IPPORT_RESERVED && !is_root)
2605                 packet_disconnect(
2606                     "Requested forwarding of port %d but user is not root.",
2607                     port);
2608         if (host_port == 0)
2609                 packet_disconnect("Dynamic forwarding denied.");
2610 #endif
2611
2612         /* Initiate forwarding */
2613         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2614             host_port, gateway_ports);
2615
2616         /* Free the argument string. */
2617         xfree(hostname);
2618
2619         return (success ? 0 : -1);
2620 }
2621
2622 /*
2623  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2624  * usually called by the server, because the user could connect to any port
2625  * anyway, and the server has no way to know but to trust the client anyway.
2626  */
2627 void
2628 channel_permit_all_opens(void)
2629 {
2630         if (num_permitted_opens == 0)
2631                 all_opens_permitted = 1;
2632 }
2633
2634 void
2635 channel_add_permitted_opens(char *host, int port)
2636 {
2637         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2638                 fatal("channel_add_permitted_opens: too many forwards");
2639         debug("allow port forwarding to host %s port %d", host, port);
2640
2641         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2642         permitted_opens[num_permitted_opens].port_to_connect = port;
2643         num_permitted_opens++;
2644
2645         all_opens_permitted = 0;
2646 }
2647
2648 void
2649 channel_clear_permitted_opens(void)
2650 {
2651         int i;
2652
2653         for (i = 0; i < num_permitted_opens; i++)
2654                 if (permitted_opens[i].host_to_connect != NULL)
2655                         xfree(permitted_opens[i].host_to_connect);
2656         num_permitted_opens = 0;
2657
2658 }
2659
2660 /* return socket to remote host, port */
2661 static int
2662 connect_to(const char *host, u_short port)
2663 {
2664         struct addrinfo hints, *ai, *aitop;
2665         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2666         int gaierr;
2667         int sock = -1;
2668
2669         memset(&hints, 0, sizeof(hints));
2670         hints.ai_family = IPv4or6;
2671         hints.ai_socktype = SOCK_STREAM;
2672         snprintf(strport, sizeof strport, "%d", port);
2673         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2674                 error("connect_to %.100s: unknown host (%s)", host,
2675                     gai_strerror(gaierr));
2676                 return -1;
2677         }
2678         for (ai = aitop; ai; ai = ai->ai_next) {
2679                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2680                         continue;
2681                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2682                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2683                         error("connect_to: getnameinfo failed");
2684                         continue;
2685                 }
2686                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2687                 if (sock < 0) {
2688                         if (ai->ai_next == NULL)
2689                                 error("socket: %.100s", strerror(errno));
2690                         else
2691                                 verbose("socket: %.100s", strerror(errno));
2692                         continue;
2693                 }
2694                 if (set_nonblock(sock) == -1)
2695                         fatal("%s: set_nonblock(%d)", __func__, sock);
2696                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2697                     errno != EINPROGRESS) {
2698                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2699                             strerror(errno));
2700                         close(sock);
2701                         continue;       /* fail -- try next */
2702                 }
2703                 break; /* success */
2704
2705         }
2706         freeaddrinfo(aitop);
2707         if (!ai) {
2708                 error("connect_to %.100s port %d: failed.", host, port);
2709                 return -1;
2710         }
2711         /* success */
2712         set_nodelay(sock);
2713         return sock;
2714 }
2715
2716 int
2717 channel_connect_by_listen_address(u_short listen_port)
2718 {
2719         int i;
2720
2721         for (i = 0; i < num_permitted_opens; i++)
2722                 if (permitted_opens[i].host_to_connect != NULL &&
2723                     permitted_opens[i].listen_port == listen_port)
2724                         return connect_to(
2725                             permitted_opens[i].host_to_connect,
2726                             permitted_opens[i].port_to_connect);
2727         error("WARNING: Server requests forwarding for unknown listen_port %d",
2728             listen_port);
2729         return -1;
2730 }
2731
2732 /* Check if connecting to that port is permitted and connect. */
2733 int
2734 channel_connect_to(const char *host, u_short port)
2735 {
2736         int i, permit;
2737
2738         permit = all_opens_permitted;
2739         if (!permit) {
2740                 for (i = 0; i < num_permitted_opens; i++)
2741                         if (permitted_opens[i].host_to_connect != NULL &&
2742                             permitted_opens[i].port_to_connect == port &&
2743                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2744                                 permit = 1;
2745
2746         }
2747         if (!permit) {
2748                 logit("Received request to connect to host %.100s port %d, "
2749                     "but the request was denied.", host, port);
2750                 return -1;
2751         }
2752         return connect_to(host, port);
2753 }
2754
2755 void
2756 channel_send_window_changes(void)
2757 {
2758         u_int i;
2759         struct winsize ws;
2760
2761         for (i = 0; i < channels_alloc; i++) {
2762                 if (channels[i] == NULL || !channels[i]->client_tty ||
2763                     channels[i]->type != SSH_CHANNEL_OPEN)
2764                         continue;
2765                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2766                         continue;
2767                 channel_request_start(i, "window-change", 0);
2768                 packet_put_int((u_int)ws.ws_col);
2769                 packet_put_int((u_int)ws.ws_row);
2770                 packet_put_int((u_int)ws.ws_xpixel);
2771                 packet_put_int((u_int)ws.ws_ypixel);
2772                 packet_send();
2773         }
2774 }
2775
2776 /* -- X11 forwarding */
2777
2778 /*
2779  * Creates an internet domain socket for listening for X11 connections.
2780  * Returns 0 and a suitable display number for the DISPLAY variable
2781  * stored in display_numberp , or -1 if an error occurs.
2782  */
2783 int
2784 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2785     int single_connection, u_int *display_numberp, int **chanids)
2786 {
2787         Channel *nc = NULL;
2788         int display_number, sock;
2789         u_short port;
2790         struct addrinfo hints, *ai, *aitop;
2791         char strport[NI_MAXSERV];
2792         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2793
2794         if (chanids == NULL)
2795                 return -1;
2796
2797         for (display_number = x11_display_offset;
2798             display_number < MAX_DISPLAYS;
2799             display_number++) {
2800                 port = 6000 + display_number;
2801                 memset(&hints, 0, sizeof(hints));
2802                 hints.ai_family = IPv4or6;
2803                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2804                 hints.ai_socktype = SOCK_STREAM;
2805                 snprintf(strport, sizeof strport, "%d", port);
2806                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2807                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2808                         return -1;
2809                 }
2810                 for (ai = aitop; ai; ai = ai->ai_next) {
2811                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2812                                 continue;
2813                         sock = socket(ai->ai_family, ai->ai_socktype,
2814                             ai->ai_protocol);
2815                         if (sock < 0) {
2816                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2817                                         error("socket: %.100s", strerror(errno));
2818                                         freeaddrinfo(aitop);
2819                                         return -1;
2820                                 } else {
2821                                         debug("x11_create_display_inet: Socket family %d not supported",
2822                                                  ai->ai_family);
2823                                         continue;
2824                                 }
2825                         }
2826 #ifdef IPV6_V6ONLY
2827                         if (ai->ai_family == AF_INET6) {
2828                                 int on = 1;
2829                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2830                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2831                         }
2832 #endif
2833                         channel_set_reuseaddr(sock);
2834                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2835                                 debug2("bind port %d: %.100s", port, strerror(errno));
2836                                 close(sock);
2837
2838                                 if (ai->ai_next)
2839                                         continue;
2840
2841                                 for (n = 0; n < num_socks; n++) {
2842                                         close(socks[n]);
2843                                 }
2844                                 num_socks = 0;
2845                                 break;
2846                         }
2847                         socks[num_socks++] = sock;
2848 #ifndef DONT_TRY_OTHER_AF
2849                         if (num_socks == NUM_SOCKS)
2850                                 break;
2851 #else
2852                         if (x11_use_localhost) {
2853                                 if (num_socks == NUM_SOCKS)
2854                                         break;
2855                         } else {
2856                                 break;
2857                         }
2858 #endif
2859                 }
2860                 freeaddrinfo(aitop);
2861                 if (num_socks > 0)
2862                         break;
2863         }
2864         if (display_number >= MAX_DISPLAYS) {
2865                 error("Failed to allocate internet-domain X11 display socket.");
2866                 return -1;
2867         }
2868         /* Start listening for connections on the socket. */
2869         for (n = 0; n < num_socks; n++) {
2870                 sock = socks[n];
2871                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2872                         error("listen: %.100s", strerror(errno));
2873                         close(sock);
2874                         return -1;
2875                 }
2876         }
2877
2878         /* Allocate a channel for each socket. */
2879         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2880         for (n = 0; n < num_socks; n++) {
2881                 sock = socks[n];
2882                 nc = channel_new("x11 listener",
2883                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2884                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2885                     0, "X11 inet listener", 1);
2886                 nc->single_connection = single_connection;
2887                 (*chanids)[n] = nc->self;
2888         }
2889         (*chanids)[n] = -1;
2890
2891         /* Return the display number for the DISPLAY environment variable. */
2892         *display_numberp = display_number;
2893         return (0);
2894 }
2895
2896 static int
2897 connect_local_xsocket(u_int dnr)
2898 {
2899         int sock;
2900         struct sockaddr_un addr;
2901
2902         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2903         if (sock < 0)
2904                 error("socket: %.100s", strerror(errno));
2905         memset(&addr, 0, sizeof(addr));
2906         addr.sun_family = AF_UNIX;
2907         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2908         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
2909                 return sock;
2910         close(sock);
2911         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2912         return -1;
2913 }
2914
2915 int
2916 x11_connect_display(void)
2917 {
2918         u_int display_number;
2919         const char *display;
2920         char buf[1024], *cp;
2921         struct addrinfo hints, *ai, *aitop;
2922         char strport[NI_MAXSERV];
2923         int gaierr, sock = 0;
2924
2925         /* Try to open a socket for the local X server. */
2926         display = getenv("DISPLAY");
2927         if (!display) {
2928                 error("DISPLAY not set.");
2929                 return -1;
2930         }
2931         /*
2932          * Now we decode the value of the DISPLAY variable and make a
2933          * connection to the real X server.
2934          */
2935
2936         /*
2937          * Check if it is a unix domain socket.  Unix domain displays are in
2938          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2939          */
2940         if (strncmp(display, "unix:", 5) == 0 ||
2941             display[0] == ':') {
2942                 /* Connect to the unix domain socket. */
2943                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
2944                         error("Could not parse display number from DISPLAY: %.100s",
2945                             display);
2946                         return -1;
2947                 }
2948                 /* Create a socket. */
2949                 sock = connect_local_xsocket(display_number);
2950                 if (sock < 0)
2951                         return -1;
2952
2953                 /* OK, we now have a connection to the display. */
2954                 return sock;
2955         }
2956         /*
2957          * Connect to an inet socket.  The DISPLAY value is supposedly
2958          * hostname:d[.s], where hostname may also be numeric IP address.
2959          */
2960         strlcpy(buf, display, sizeof(buf));
2961         cp = strchr(buf, ':');
2962         if (!cp) {
2963                 error("Could not find ':' in DISPLAY: %.100s", display);
2964                 return -1;
2965         }
2966         *cp = 0;
2967         /* buf now contains the host name.  But first we parse the display number. */
2968         if (sscanf(cp + 1, "%u", &display_number) != 1) {
2969                 error("Could not parse display number from DISPLAY: %.100s",
2970                     display);
2971                 return -1;
2972         }
2973
2974         /* Look up the host address */
2975         memset(&hints, 0, sizeof(hints));
2976         hints.ai_family = IPv4or6;
2977         hints.ai_socktype = SOCK_STREAM;
2978         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
2979         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2980                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2981                 return -1;
2982         }
2983         for (ai = aitop; ai; ai = ai->ai_next) {
2984                 /* Create a socket. */
2985                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2986                 if (sock < 0) {
2987                         debug2("socket: %.100s", strerror(errno));
2988                         continue;
2989                 }
2990                 /* Connect it to the display. */
2991                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2992                         debug2("connect %.100s port %u: %.100s", buf,
2993                             6000 + display_number, strerror(errno));
2994                         close(sock);
2995                         continue;
2996                 }
2997                 /* Success */
2998                 break;
2999         }
3000         freeaddrinfo(aitop);
3001         if (!ai) {
3002                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3003                     strerror(errno));
3004                 return -1;
3005         }
3006         set_nodelay(sock);
3007         return sock;
3008 }
3009
3010 /*
3011  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3012  * the remote channel number.  We should do whatever we want, and respond
3013  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3014  */
3015
3016 void
3017 x11_input_open(int type, u_int32_t seq, void *ctxt)
3018 {
3019         Channel *c = NULL;
3020         int remote_id, sock = 0;
3021         char *remote_host;
3022
3023         debug("Received X11 open request.");
3024
3025         remote_id = packet_get_int();
3026
3027         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3028                 remote_host = packet_get_string(NULL);
3029         } else {
3030                 remote_host = xstrdup("unknown (remote did not supply name)");
3031         }
3032         packet_check_eom();
3033
3034         /* Obtain a connection to the real X display. */
3035         sock = x11_connect_display();
3036         if (sock != -1) {
3037                 /* Allocate a channel for this connection. */
3038                 c = channel_new("connected x11 socket",
3039                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3040                     remote_host, 1);
3041                 c->remote_id = remote_id;
3042                 c->force_drain = 1;
3043         }
3044         xfree(remote_host);
3045         if (c == NULL) {
3046                 /* Send refusal to the remote host. */
3047                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3048                 packet_put_int(remote_id);
3049         } else {
3050                 /* Send a confirmation to the remote host. */
3051                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3052                 packet_put_int(remote_id);
3053                 packet_put_int(c->self);
3054         }
3055         packet_send();
3056 }
3057
3058 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3059 void
3060 deny_input_open(int type, u_int32_t seq, void *ctxt)
3061 {
3062         int rchan = packet_get_int();
3063
3064         switch (type) {
3065         case SSH_SMSG_AGENT_OPEN:
3066                 error("Warning: ssh server tried agent forwarding.");
3067                 break;
3068         case SSH_SMSG_X11_OPEN:
3069                 error("Warning: ssh server tried X11 forwarding.");
3070                 break;
3071         default:
3072                 error("deny_input_open: type %d", type);
3073                 break;
3074         }
3075         error("Warning: this is probably a break-in attempt by a malicious server.");
3076         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3077         packet_put_int(rchan);
3078         packet_send();
3079 }
3080
3081 /*
3082  * Requests forwarding of X11 connections, generates fake authentication
3083  * data, and enables authentication spoofing.
3084  * This should be called in the client only.
3085  */
3086 void
3087 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3088     const char *proto, const char *data)
3089 {
3090         u_int data_len = (u_int) strlen(data) / 2;
3091         u_int i, value;
3092         char *new_data;
3093         int screen_number;
3094         const char *cp;
3095         u_int32_t rnd = 0;
3096
3097         if (x11_saved_display == NULL)
3098                 x11_saved_display = xstrdup(disp);
3099         else if (strcmp(disp, x11_saved_display) != 0) {
3100                 error("x11_request_forwarding_with_spoofing: different "
3101                     "$DISPLAY already forwarded");
3102                 return;
3103         }
3104
3105         cp = disp;
3106         if (disp)
3107                 cp = strchr(disp, ':');
3108         if (cp)
3109                 cp = strchr(cp, '.');
3110         if (cp)
3111                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3112         else
3113                 screen_number = 0;
3114
3115         if (x11_saved_proto == NULL) {
3116                 /* Save protocol name. */
3117                 x11_saved_proto = xstrdup(proto);
3118                 /*
3119                  * Extract real authentication data and generate fake data
3120                  * of the same length.
3121                  */
3122                 x11_saved_data = xmalloc(data_len);
3123                 x11_fake_data = xmalloc(data_len);
3124                 for (i = 0; i < data_len; i++) {
3125                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3126                                 fatal("x11_request_forwarding: bad "
3127                                     "authentication data: %.100s", data);
3128                         if (i % 4 == 0)
3129                                 rnd = arc4random();
3130                         x11_saved_data[i] = value;
3131                         x11_fake_data[i] = rnd & 0xff;
3132                         rnd >>= 8;
3133                 }
3134                 x11_saved_data_len = data_len;
3135                 x11_fake_data_len = data_len;
3136         }
3137
3138         /* Convert the fake data into hex. */
3139         new_data = tohex(x11_fake_data, data_len);
3140
3141         /* Send the request packet. */
3142         if (compat20) {
3143                 channel_request_start(client_session_id, "x11-req", 0);
3144                 packet_put_char(0);     /* XXX bool single connection */
3145         } else {
3146                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3147         }
3148         packet_put_cstring(proto);
3149         packet_put_cstring(new_data);
3150         packet_put_int(screen_number);
3151         packet_send();
3152         packet_write_wait();
3153         xfree(new_data);
3154 }
3155
3156
3157 /* -- agent forwarding */
3158
3159 /* Sends a message to the server to request authentication fd forwarding. */
3160
3161 void
3162 auth_request_forwarding(void)
3163 {
3164         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3165         packet_send();
3166         packet_write_wait();
3167 }