openssh/channels.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * This file contains functions for generic socket connection forwarding.
   6  * There is also code for initiating connection forwarding for X11 connections,
   7  * arbitrary tcp/ip connections, and the authentication agent connection.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * SSH2 support added by Markus Friedl.
  16  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  17  * Copyright (c) 1999 Dug Song.  All rights reserved.
  18  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  19  *
  20  * Redistribution and use in source and binary forms, with or without
  21  * modification, are permitted provided that the following conditions
  22  * are met:
  23  * 1. Redistributions of source code must retain the above copyright
  24  *    notice, this list of conditions and the following disclaimer.
  25  * 2. Redistributions in binary form must reproduce the above copyright
  26  *    notice, this list of conditions and the following disclaimer in the
  27  *    documentation and/or other materials provided with the distribution.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  30  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  31  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  32  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  33  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  34  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  38  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  39  */
  40
  41 #include "includes.h"
  42 RCSID("$OpenBSD: channels.c,v 1.232 2006/01/30 12:22:22 reyk Exp $");
  43
  44 #include "ssh.h"
  45 #include "ssh1.h"
  46 #include "ssh2.h"
  47 #include "packet.h"
  48 #include "xmalloc.h"
  49 #include "log.h"
  50 #include "misc.h"
  51 #include "channels.h"
  52 #include "compat.h"
  53 #include "canohost.h"
  54 #include "key.h"
  55 #include "authfd.h"
  56 #include "pathnames.h"
  57 #include "bufaux.h"
  58
  59 /* -- channel core */
  60
  61 /*
  62  * Pointer to an array containing all allocated channels.  The array is
  63  * dynamically extended as needed.
  64  */
  65 static Channel **channels = NULL;
  66
  67 /*
  68  * Size of the channel array.  All slots of the array must always be
  69  * initialized (at least the type field); unused slots set to NULL
  70  */
  71 static u_int channels_alloc = 0;
  72
  73 /*
  74  * Maximum file descriptor value used in any of the channels.  This is
  75  * updated in channel_new.
  76  */
  77 static int channel_max_fd = 0;
  78
  79
  80 /* -- tcp forwarding */
  81
  82 /*
  83  * Data structure for storing which hosts are permitted for forward requests.
  84  * The local sides of any remote forwards are stored in this array to prevent
  85  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  86  * network (which might be behind a firewall).
  87  */
  88 typedef struct {
  89         char *host_to_connect;          /* Connect to 'host'. */
  90         u_short port_to_connect;        /* Connect to 'port'. */
  91         u_short listen_port;            /* Remote side should listen port number. */
  92 } ForwardPermission;
  93
  94 /* List of all permitted host/port pairs to connect. */
  95 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
  96
  97 /* Number of permitted host/port pairs in the array. */
  98 static int num_permitted_opens = 0;
  99 /*
 100  * If this is true, all opens are permitted.  This is the case on the server
 101  * on which we have to trust the client anyway, and the user could do
 102  * anything after logging in anyway.
 103  */
 104 static int all_opens_permitted = 0;
 105
 106
 107 /* -- X11 forwarding */
 108
 109 /* Maximum number of fake X11 displays to try. */
 110 #define MAX_DISPLAYS  1000
 111
 112 /* Saved X11 local (client) display. */
 113 static char *x11_saved_display = NULL;
 114
 115 /* Saved X11 authentication protocol name. */
 116 static char *x11_saved_proto = NULL;
 117
 118 /* Saved X11 authentication data.  This is the real data. */
 119 static char *x11_saved_data = NULL;
 120 static u_int x11_saved_data_len = 0;
 121
 122 /*
 123  * Fake X11 authentication data.  This is what the server will be sending us;
 124  * we should replace any occurrences of this by the real data.
 125  */
 126 static char *x11_fake_data = NULL;
 127 static u_int x11_fake_data_len;
 128
 129
 130 /* -- agent forwarding */
 131
 132 #define NUM_SOCKS       10
 133
 134 /* AF_UNSPEC or AF_INET or AF_INET6 */
 135 static int IPv4or6 = AF_UNSPEC;
 136
 137 /* helper */
 138 static void port_open_helper(Channel *c, char *rtype);
 139
 140 /* -- channel core */
 141
 142 Channel *
 143 channel_by_id(int id)
 144 {
 145         Channel *c;
 146
 147         if (id < 0 || (u_int)id >= channels_alloc) {
 148                 logit("channel_by_id: %d: bad id", id);
 149                 return NULL;
 150         }
 151         c = channels[id];
 152         if (c == NULL) {
 153                 logit("channel_by_id: %d: bad id: channel free", id);
 154                 return NULL;
 155         }
 156         return c;
 157 }
 158
 159 /*
 160  * Returns the channel if it is allowed to receive protocol messages.
 161  * Private channels, like listening sockets, may not receive messages.
 162  */
 163 Channel *
 164 channel_lookup(int id)
 165 {
 166         Channel *c;
 167
 168         if ((c = channel_by_id(id)) == NULL)
 169                 return (NULL);
 170
 171         switch(c->type) {
 172         case SSH_CHANNEL_X11_OPEN:
 173         case SSH_CHANNEL_LARVAL:
 174         case SSH_CHANNEL_CONNECTING:
 175         case SSH_CHANNEL_DYNAMIC:
 176         case SSH_CHANNEL_OPENING:
 177         case SSH_CHANNEL_OPEN:
 178         case SSH_CHANNEL_INPUT_DRAINING:
 179         case SSH_CHANNEL_OUTPUT_DRAINING:
 180                 return (c);
 181                 break;
 182         }
 183         logit("Non-public channel %d, type %d.", id, c->type);
 184         return (NULL);
 185 }
 186
 187 /*
 188  * Register filedescriptors for a channel, used when allocating a channel or
 189  * when the channel consumer/producer is ready, e.g. shell exec'd
 190  */
 191
 192 static void
 193 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 194     int extusage, int nonblock)
 195 {
 196         /* Update the maximum file descriptor value. */
 197         channel_max_fd = MAX(channel_max_fd, rfd);
 198         channel_max_fd = MAX(channel_max_fd, wfd);
 199         channel_max_fd = MAX(channel_max_fd, efd);
 200
 201         /* XXX set close-on-exec -markus */
 202
 203         c->rfd = rfd;
 204         c->wfd = wfd;
 205         c->sock = (rfd == wfd) ? rfd : -1;
 206         c->ctl_fd = -1; /* XXX: set elsewhere */
 207         c->efd = efd;
 208         c->extended_usage = extusage;
 209
 210         /* XXX ugly hack: nonblock is only set by the server */
 211         if (nonblock && isatty(c->rfd)) {
 212                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 213                 c->isatty = 1;
 214                 if (!isatty(c->wfd)) {
 215                         error("channel %d: wfd %d is not a tty?",
 216                             c->self, c->wfd);
 217                 }
 218         } else {
 219                 c->isatty = 0;
 220         }
 221         c->wfd_isatty = isatty(c->wfd);
 222
 223         /* enable nonblocking mode */
 224         if (nonblock) {
 225                 if (rfd != -1)
 226                         set_nonblock(rfd);
 227                 if (wfd != -1)
 228                         set_nonblock(wfd);
 229                 if (efd != -1)
 230                         set_nonblock(efd);
 231         }
 232 }
 233
 234 /*
 235  * Allocate a new channel object and set its type and socket. This will cause
 236  * remote_name to be freed.
 237  */
 238
 239 Channel *
 240 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 241     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 242 {
 243         int found;
 244         u_int i;
 245         Channel *c;
 246
 247         /* Do initial allocation if this is the first call. */
 248         if (channels_alloc == 0) {
 249                 channels_alloc = 10;
 250                 channels = xmalloc(channels_alloc * sizeof(Channel *));
 251                 for (i = 0; i < channels_alloc; i++)
 252                         channels[i] = NULL;
 253         }
 254         /* Try to find a free slot where to put the new channel. */
 255         for (found = -1, i = 0; i < channels_alloc; i++)
 256                 if (channels[i] == NULL) {
 257                         /* Found a free slot. */
 258                         found = (int)i;
 259                         break;
 260                 }
 261         if (found < 0) {
 262                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 263                 found = channels_alloc;
 264                 if (channels_alloc > 10000)
 265                         fatal("channel_new: internal error: channels_alloc %d "
 266                             "too big.", channels_alloc);
 267                 channels = xrealloc(channels,
 268                     (channels_alloc + 10) * sizeof(Channel *));
 269                 channels_alloc += 10;
 270                 debug2("channel: expanding %d", channels_alloc);
 271                 for (i = found; i < channels_alloc; i++)
 272                         channels[i] = NULL;
 273         }
 274         /* Initialize and return new channel. */
 275         c = channels[found] = xmalloc(sizeof(Channel));
 276         memset(c, 0, sizeof(Channel));
 277         buffer_init(&c->input);
 278         buffer_init(&c->output);
 279         buffer_init(&c->extended);
 280         c->ostate = CHAN_OUTPUT_OPEN;
 281         c->istate = CHAN_INPUT_OPEN;
 282         c->flags = 0;
 283         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 284         c->self = found;
 285         c->type = type;
 286         c->ctype = ctype;
 287         c->local_window = window;
 288         c->local_window_max = window;
 289         c->local_consumed = 0;
 290         c->local_maxpacket = maxpack;
 291         c->dynamic_window = 0;
 292         c->remote_id = -1;
 293         c->remote_name = xstrdup(remote_name);
 294         c->remote_window = 0;
 295         c->remote_maxpacket = 0;
 296         c->force_drain = 0;
 297         c->single_connection = 0;
 298         c->detach_user = NULL;
 299         c->detach_close = 0;
 300         c->confirm = NULL;
 301         c->confirm_ctx = NULL;
 302         c->input_filter = NULL;
 303         c->output_filter = NULL;
 304         debug("channel %d: new [%s]", found, remote_name);
 305         return c;
 306 }
 307
 308 static int
 309 channel_find_maxfd(void)
 310 {
 311         u_int i;
 312         int max = 0;
 313         Channel *c;
 314
 315         for (i = 0; i < channels_alloc; i++) {
 316                 c = channels[i];
 317                 if (c != NULL) {
 318                         max = MAX(max, c->rfd);
 319                         max = MAX(max, c->wfd);
 320                         max = MAX(max, c->efd);
 321                 }
 322         }
 323         return max;
 324 }
 325
 326 int
 327 channel_close_fd(int *fdp)
 328 {
 329         int ret = 0, fd = *fdp;
 330
 331         if (fd != -1) {
 332                 ret = close(fd);
 333                 *fdp = -1;
 334                 if (fd == channel_max_fd)
 335                         channel_max_fd = channel_find_maxfd();
 336         }
 337         return ret;
 338 }
 339
 340 /* Close all channel fd/socket. */
 341
 342 static void
 343 channel_close_fds(Channel *c)
 344 {
 345         debug3("channel %d: close_fds r %d w %d e %d c %d",
 346             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 347
 348         channel_close_fd(&c->sock);
 349         channel_close_fd(&c->ctl_fd);
 350         channel_close_fd(&c->rfd);
 351         channel_close_fd(&c->wfd);
 352         channel_close_fd(&c->efd);
 353 }
 354
 355 /* Free the channel and close its fd/socket. */
 356
 357 void
 358 channel_free(Channel *c)
 359 {
 360         char *s;
 361         u_int i, n;
 362
 363         for (n = 0, i = 0; i < channels_alloc; i++)
 364                 if (channels[i])
 365                         n++;
 366         debug("channel %d: free: %s, nchannels %u", c->self,
 367             c->remote_name ? c->remote_name : "???", n);
 368
 369         s = channel_open_message();
 370         debug3("channel %d: status: %s", c->self, s);
 371         xfree(s);
 372
 373         if (c->sock != -1)
 374                 shutdown(c->sock, SHUT_RDWR);
 375         if (c->ctl_fd != -1)
 376                 shutdown(c->ctl_fd, SHUT_RDWR);
 377         channel_close_fds(c);
 378         buffer_free(&c->input);
 379         buffer_free(&c->output);
 380         buffer_free(&c->extended);
 381         if (c->remote_name) {
 382                 xfree(c->remote_name);
 383                 c->remote_name = NULL;
 384         }
 385         channels[c->self] = NULL;
 386         xfree(c);
 387 }
 388
 389 void
 390 channel_free_all(void)
 391 {
 392         u_int i;
 393
 394         for (i = 0; i < channels_alloc; i++)
 395                 if (channels[i] != NULL)
 396                         channel_free(channels[i]);
 397 }
 398
 399 /*
 400  * Closes the sockets/fds of all channels.  This is used to close extra file
 401  * descriptors after a fork.
 402  */
 403
 404 void
 405 channel_close_all(void)
 406 {
 407         u_int i;
 408
 409         for (i = 0; i < channels_alloc; i++)
 410                 if (channels[i] != NULL)
 411                         channel_close_fds(channels[i]);
 412 }
 413
 414 /*
 415  * Stop listening to channels.
 416  */
 417
 418 void
 419 channel_stop_listening(void)
 420 {
 421         u_int i;
 422         Channel *c;
 423
 424         for (i = 0; i < channels_alloc; i++) {
 425                 c = channels[i];
 426                 if (c != NULL) {
 427                         switch (c->type) {
 428                         case SSH_CHANNEL_AUTH_SOCKET:
 429                         case SSH_CHANNEL_PORT_LISTENER:
 430                         case SSH_CHANNEL_RPORT_LISTENER:
 431                         case SSH_CHANNEL_X11_LISTENER:
 432                                 channel_close_fd(&c->sock);
 433                                 channel_free(c);
 434                                 break;
 435                         }
 436                 }
 437         }
 438 }
 439
 440 /*
 441  * Returns true if no channel has too much buffered data, and false if one or
 442  * more channel is overfull.
 443  */
 444
 445 int
 446 channel_not_very_much_buffered_data(void)
 447 {
 448         u_int i;
 449         Channel *c;
 450
 451         for (i = 0; i < channels_alloc; i++) {
 452                 c = channels[i];
 453                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 454 #if 0
 455                         if (!compat20 &&
 456                             buffer_len(&c->input) > packet_get_maxsize()) {
 457                                 debug2("channel %d: big input buffer %d",
 458                                     c->self, buffer_len(&c->input));
 459                                 return 0;
 460                         }
 461 #endif
 462                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 463                                 debug2("channel %d: big output buffer %u > %u",
 464                                     c->self, buffer_len(&c->output),
 465                                     packet_get_maxsize());
 466                                 return 0;
 467                         }
 468                 }
 469         }
 470         return 1;
 471 }
 472
 473 /* Returns true if any channel is still open. */
 474
 475 int
 476 channel_still_open(void)
 477 {
 478         u_int i;
 479         Channel *c;
 480
 481         for (i = 0; i < channels_alloc; i++) {
 482                 c = channels[i];
 483                 if (c == NULL)
 484                         continue;
 485                 switch (c->type) {
 486                 case SSH_CHANNEL_X11_LISTENER:
 487                 case SSH_CHANNEL_PORT_LISTENER:
 488                 case SSH_CHANNEL_RPORT_LISTENER:
 489                 case SSH_CHANNEL_CLOSED:
 490                 case SSH_CHANNEL_AUTH_SOCKET:
 491                 case SSH_CHANNEL_DYNAMIC:
 492                 case SSH_CHANNEL_CONNECTING:
 493                 case SSH_CHANNEL_ZOMBIE:
 494                         continue;
 495                 case SSH_CHANNEL_LARVAL:
 496                         if (!compat20)
 497                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 498                         continue;
 499                 case SSH_CHANNEL_OPENING:
 500                 case SSH_CHANNEL_OPEN:
 501                 case SSH_CHANNEL_X11_OPEN:
 502                         return 1;
 503                 case SSH_CHANNEL_INPUT_DRAINING:
 504                 case SSH_CHANNEL_OUTPUT_DRAINING:
 505                         if (!compat13)
 506                                 fatal("cannot happen: OUT_DRAIN");
 507                         return 1;
 508                 default:
 509                         fatal("channel_still_open: bad channel type %d", c->type);
 510                         /* NOTREACHED */
 511                 }
 512         }
 513         return 0;
 514 }
 515
 516 /* Returns the id of an open channel suitable for keepaliving */
 517
 518 int
 519 channel_find_open(void)
 520 {
 521         u_int i;
 522         Channel *c;
 523
 524         for (i = 0; i < channels_alloc; i++) {
 525                 c = channels[i];
 526                 if (c == NULL || c->remote_id < 0)
 527                         continue;
 528                 switch (c->type) {
 529                 case SSH_CHANNEL_CLOSED:
 530                 case SSH_CHANNEL_DYNAMIC:
 531                 case SSH_CHANNEL_X11_LISTENER:
 532                 case SSH_CHANNEL_PORT_LISTENER:
 533                 case SSH_CHANNEL_RPORT_LISTENER:
 534                 case SSH_CHANNEL_OPENING:
 535                 case SSH_CHANNEL_CONNECTING:
 536                 case SSH_CHANNEL_ZOMBIE:
 537                         continue;
 538                 case SSH_CHANNEL_LARVAL:
 539                 case SSH_CHANNEL_AUTH_SOCKET:
 540                 case SSH_CHANNEL_OPEN:
 541                 case SSH_CHANNEL_X11_OPEN:
 542                         return i;
 543                 case SSH_CHANNEL_INPUT_DRAINING:
 544                 case SSH_CHANNEL_OUTPUT_DRAINING:
 545                         if (!compat13)
 546                                 fatal("cannot happen: OUT_DRAIN");
 547                         return i;
 548                 default:
 549                         fatal("channel_find_open: bad channel type %d", c->type);
 550                         /* NOTREACHED */
 551                 }
 552         }
 553         return -1;
 554 }
 555
 556
 557 /*
 558  * Returns a message describing the currently open forwarded connections,
 559  * suitable for sending to the client.  The message contains crlf pairs for
 560  * newlines.
 561  */
 562
 563 char *
 564 channel_open_message(void)
 565 {
 566         Buffer buffer;
 567         Channel *c;
 568         char buf[1024], *cp;
 569         u_int i;
 570
 571         buffer_init(&buffer);
 572         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 573         buffer_append(&buffer, buf, strlen(buf));
 574         for (i = 0; i < channels_alloc; i++) {
 575                 c = channels[i];
 576                 if (c == NULL)
 577                         continue;
 578                 switch (c->type) {
 579                 case SSH_CHANNEL_X11_LISTENER:
 580                 case SSH_CHANNEL_PORT_LISTENER:
 581                 case SSH_CHANNEL_RPORT_LISTENER:
 582                 case SSH_CHANNEL_CLOSED:
 583                 case SSH_CHANNEL_AUTH_SOCKET:
 584                 case SSH_CHANNEL_ZOMBIE:
 585                         continue;
 586                 case SSH_CHANNEL_LARVAL:
 587                 case SSH_CHANNEL_OPENING:
 588                 case SSH_CHANNEL_CONNECTING:
 589                 case SSH_CHANNEL_DYNAMIC:
 590                 case SSH_CHANNEL_OPEN:
 591                 case SSH_CHANNEL_X11_OPEN:
 592                 case SSH_CHANNEL_INPUT_DRAINING:
 593                 case SSH_CHANNEL_OUTPUT_DRAINING:
 594                         snprintf(buf, sizeof buf,
 595                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 596                             c->self, c->remote_name,
 597                             c->type, c->remote_id,
 598                             c->istate, buffer_len(&c->input),
 599                             c->ostate, buffer_len(&c->output),
 600                             c->rfd, c->wfd, c->ctl_fd);
 601                         buffer_append(&buffer, buf, strlen(buf));
 602                         continue;
 603                 default:
 604                         fatal("channel_open_message: bad channel type %d", c->type);
 605                         /* NOTREACHED */
 606                 }
 607         }
 608         buffer_append(&buffer, "\0", 1);
 609         cp = xstrdup(buffer_ptr(&buffer));
 610         buffer_free(&buffer);
 611         return cp;
 612 }
 613
 614 void
 615 channel_send_open(int id)
 616 {
 617         Channel *c = channel_lookup(id);
 618
 619         if (c == NULL) {
 620                 logit("channel_send_open: %d: bad id", id);
 621                 return;
 622         }
 623         debug2("channel %d: send open", id);
 624         packet_start(SSH2_MSG_CHANNEL_OPEN);
 625         packet_put_cstring(c->ctype);
 626         packet_put_int(c->self);
 627         packet_put_int(c->local_window);
 628         packet_put_int(c->local_maxpacket);
 629         packet_send();
 630 }
 631
 632 void
 633 channel_request_start(int id, char *service, int wantconfirm)
 634 {
 635         Channel *c = channel_lookup(id);
 636
 637         if (c == NULL) {
 638                 logit("channel_request_start: %d: unknown channel id", id);
 639                 return;
 640         }
 641         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 642         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 643         packet_put_int(c->remote_id);
 644         packet_put_cstring(service);
 645         packet_put_char(wantconfirm);
 646 }
 647 void
 648 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 649 {
 650         Channel *c = channel_lookup(id);
 651
 652         if (c == NULL) {
 653                 logit("channel_register_comfirm: %d: bad id", id);
 654                 return;
 655         }
 656         c->confirm = fn;
 657         c->confirm_ctx = ctx;
 658 }
 659 void
 660 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 661 {
 662         Channel *c = channel_by_id(id);
 663
 664         if (c == NULL) {
 665                 logit("channel_register_cleanup: %d: bad id", id);
 666                 return;
 667         }
 668         c->detach_user = fn;
 669         c->detach_close = do_close;
 670 }
 671 void
 672 channel_cancel_cleanup(int id)
 673 {
 674         Channel *c = channel_by_id(id);
 675
 676         if (c == NULL) {
 677                 logit("channel_cancel_cleanup: %d: bad id", id);
 678                 return;
 679         }
 680         c->detach_user = NULL;
 681         c->detach_close = 0;
 682 }
 683 void
 684 channel_register_filter(int id, channel_infilter_fn *ifn,
 685     channel_outfilter_fn *ofn)
 686 {
 687         Channel *c = channel_lookup(id);
 688
 689         if (c == NULL) {
 690                 logit("channel_register_filter: %d: bad id", id);
 691                 return;
 692         }
 693         c->input_filter = ifn;
 694         c->output_filter = ofn;
 695 }
 696
 697 void
 698 channel_set_fds(int id, int rfd, int wfd, int efd,
 699     int extusage, int nonblock, u_int window_max)
 700 {
 701         Channel *c = channel_lookup(id);
 702
 703         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 704                 fatal("channel_activate for non-larval channel %d.", id);
 705         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 706         c->type = SSH_CHANNEL_OPEN;
 707         c->local_window = c->local_window_max = window_max;
 708         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 709         packet_put_int(c->remote_id);
 710         packet_put_int(c->local_window);
 711         packet_send();
 712 }
 713
 714 /*
 715  * 'channel_pre*' are called just before select() to add any bits relevant to
 716  * channels in the select bitmasks.
 717  */
 718 /*
 719  * 'channel_post*': perform any appropriate operations for channels which
 720  * have events pending.
 721  */
 722 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 723 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 724 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 725
 726 static void
 727 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 728 {
 729         FD_SET(c->sock, readset);
 730 }
 731
 732 static void
 733 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 734 {
 735         debug3("channel %d: waiting for connection", c->self);
 736         FD_SET(c->sock, writeset);
 737 }
 738
 739 static void
 740 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 741 {
 742         if (buffer_len(&c->input) < packet_get_maxsize())
 743                 FD_SET(c->sock, readset);
 744         if (buffer_len(&c->output) > 0)
 745                 FD_SET(c->sock, writeset);
 746 }
 747
 748 static void
 749 channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
 750 {
 751         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 752
 753         /* check buffer limits */
 754         limit = MIN(limit, (BUFFER_MAX_HPN_LEN - BUFFER_MAX_CHUNK - CHAN_RBUF));
 755
 756         if (c->istate == CHAN_INPUT_OPEN &&
 757             limit > 0 &&
 758             buffer_len(&c->input) < limit)
 759                 FD_SET(c->rfd, readset);
 760         if (c->ostate == CHAN_OUTPUT_OPEN ||
 761             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 762                 if (buffer_len(&c->output) > 0) {
 763                         FD_SET(c->wfd, writeset);
 764                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 765                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 766                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 767                                     c->self, c->efd, buffer_len(&c->extended));
 768                         else
 769                                 chan_obuf_empty(c);
 770                 }
 771         }
 772         /** XXX check close conditions, too */
 773         if (compat20 && c->efd != -1) {
 774                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 775                     buffer_len(&c->extended) > 0)
 776                         FD_SET(c->efd, writeset);
 777                 else if (!(c->flags & CHAN_EOF_SENT) &&
 778                     c->extended_usage == CHAN_EXTENDED_READ &&
 779                     buffer_len(&c->extended) < c->remote_window)
 780                         FD_SET(c->efd, readset);
 781         }
 782         /* XXX: What about efd? races? */
 783         if (compat20 && c->ctl_fd != -1 &&
 784             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 785                 FD_SET(c->ctl_fd, readset);
 786 }
 787
 788 static void
 789 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 790 {
 791         if (buffer_len(&c->input) == 0) {
 792                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 793                 packet_put_int(c->remote_id);
 794                 packet_send();
 795                 c->type = SSH_CHANNEL_CLOSED;
 796                 debug2("channel %d: closing after input drain.", c->self);
 797         }
 798 }
 799
 800 static void
 801 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 802 {
 803         if (buffer_len(&c->output) == 0)
 804                 chan_mark_dead(c);
 805         else
 806                 FD_SET(c->sock, writeset);
 807 }
 808
 809 /*
 810  * This is a special state for X11 authentication spoofing.  An opened X11
 811  * connection (when authentication spoofing is being done) remains in this
 812  * state until the first packet has been completely read.  The authentication
 813  * data in that packet is then substituted by the real data if it matches the
 814  * fake data, and the channel is put into normal mode.
 815  * XXX All this happens at the client side.
 816  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 817  */
 818 static int
 819 x11_open_helper(Buffer *b)
 820 {
 821         u_char *ucp;
 822         u_int proto_len, data_len;
 823
 824         /* Check if the fixed size part of the packet is in buffer. */
 825         if (buffer_len(b) < 12)
 826                 return 0;
 827
 828         /* Parse the lengths of variable-length fields. */
 829         ucp = buffer_ptr(b);
 830         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 831                 proto_len = 256 * ucp[6] + ucp[7];
 832                 data_len = 256 * ucp[8] + ucp[9];
 833         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 834                 proto_len = ucp[6] + 256 * ucp[7];
 835                 data_len = ucp[8] + 256 * ucp[9];
 836         } else {
 837                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 838                     ucp[0]);
 839                 return -1;
 840         }
 841
 842         /* Check if the whole packet is in buffer. */
 843         if (buffer_len(b) <
 844             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 845                 return 0;
 846
 847         /* Check if authentication protocol matches. */
 848         if (proto_len != strlen(x11_saved_proto) ||
 849             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 850                 debug2("X11 connection uses different authentication protocol.");
 851                 return -1;
 852         }
 853         /* Check if authentication data matches our fake data. */
 854         if (data_len != x11_fake_data_len ||
 855             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 856                 x11_fake_data, x11_fake_data_len) != 0) {
 857                 debug2("X11 auth data does not match fake data.");
 858                 return -1;
 859         }
 860         /* Check fake data length */
 861         if (x11_fake_data_len != x11_saved_data_len) {
 862                 error("X11 fake_data_len %d != saved_data_len %d",
 863                     x11_fake_data_len, x11_saved_data_len);
 864                 return -1;
 865         }
 866         /*
 867          * Received authentication protocol and data match
 868          * our fake data. Substitute the fake data with real
 869          * data.
 870          */
 871         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 872             x11_saved_data, x11_saved_data_len);
 873         return 1;
 874 }
 875
 876 static void
 877 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 878 {
 879         int ret = x11_open_helper(&c->output);
 880
 881         if (ret == 1) {
 882                 /* Start normal processing for the channel. */
 883                 c->type = SSH_CHANNEL_OPEN;
 884                 channel_pre_open_13(c, readset, writeset);
 885         } else if (ret == -1) {
 886                 /*
 887                  * We have received an X11 connection that has bad
 888                  * authentication information.
 889                  */
 890                 logit("X11 connection rejected because of wrong authentication.");
 891                 buffer_clear(&c->input);
 892                 buffer_clear(&c->output);
 893                 channel_close_fd(&c->sock);
 894                 c->sock = -1;
 895                 c->type = SSH_CHANNEL_CLOSED;
 896                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 897                 packet_put_int(c->remote_id);
 898                 packet_send();
 899         }
 900 }
 901
 902 static void
 903 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
 904 {
 905         int ret = x11_open_helper(&c->output);
 906
 907         /* c->force_drain = 1; */
 908
 909         if (ret == 1) {
 910                 c->type = SSH_CHANNEL_OPEN;
 911                 channel_pre_open(c, readset, writeset);
 912         } else if (ret == -1) {
 913                 logit("X11 connection rejected because of wrong authentication.");
 914                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 915                 chan_read_failed(c);
 916                 buffer_clear(&c->input);
 917                 chan_ibuf_empty(c);
 918                 buffer_clear(&c->output);
 919                 /* for proto v1, the peer will send an IEOF */
 920                 if (compat20)
 921                         chan_write_failed(c);
 922                 else
 923                         c->type = SSH_CHANNEL_OPEN;
 924                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 925         }
 926 }
 927
 928 /* try to decode a socks4 header */
 929 static int
 930 channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
 931 {
 932         char *p, *host;
 933         u_int len, have, i, found;
 934         char username[256];
 935         struct {
 936                 u_int8_t version;
 937                 u_int8_t command;
 938                 u_int16_t dest_port;
 939                 struct in_addr dest_addr;
 940         } s4_req, s4_rsp;
 941
 942         debug2("channel %d: decode socks4", c->self);
 943
 944         have = buffer_len(&c->input);
 945         len = sizeof(s4_req);
 946         if (have < len)
 947                 return 0;
 948         p = buffer_ptr(&c->input);
 949         for (found = 0, i = len; i < have; i++) {
 950                 if (p[i] == '\0') {
 951                         found = 1;
 952                         break;
 953                 }
 954                 if (i > 1024) {
 955                         /* the peer is probably sending garbage */
 956                         debug("channel %d: decode socks4: too long",
 957                             c->self);
 958                         return -1;
 959                 }
 960         }
 961         if (!found)
 962                 return 0;
 963         buffer_get(&c->input, (char *)&s4_req.version, 1);
 964         buffer_get(&c->input, (char *)&s4_req.command, 1);
 965         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 966         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 967         have = buffer_len(&c->input);
 968         p = buffer_ptr(&c->input);
 969         len = strlen(p);
 970         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 971         if (len > have)
 972                 fatal("channel %d: decode socks4: len %d > have %d",
 973                     c->self, len, have);
 974         strlcpy(username, p, sizeof(username));
 975         buffer_consume(&c->input, len);
 976         buffer_consume(&c->input, 1);           /* trailing '\0' */
 977
 978         host = inet_ntoa(s4_req.dest_addr);
 979         strlcpy(c->path, host, sizeof(c->path));
 980         c->host_port = ntohs(s4_req.dest_port);
 981
 982         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 983             c->self, host, c->host_port, s4_req.command);
 984
 985         if (s4_req.command != 1) {
 986                 debug("channel %d: cannot handle: socks4 cn %d",
 987                     c->self, s4_req.command);
 988                 return -1;
 989         }
 990         s4_rsp.version = 0;                     /* vn: 0 for reply */
 991         s4_rsp.command = 90;                    /* cd: req granted */
 992         s4_rsp.dest_port = 0;                   /* ignored */
 993         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 994         buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
 995         return 1;
 996 }
 997
 998 /* try to decode a socks5 header */
 999 #define SSH_SOCKS5_AUTHDONE     0x1000
1000 #define SSH_SOCKS5_NOAUTH       0x00
1001 #define SSH_SOCKS5_IPV4         0x01
1002 #define SSH_SOCKS5_DOMAIN       0x03
1003 #define SSH_SOCKS5_IPV6         0x04
1004 #define SSH_SOCKS5_CONNECT      0x01
1005 #define SSH_SOCKS5_SUCCESS      0x00
1006
1007 static int
1008 channel_decode_socks5(Channel *c, fd_set * readset, fd_set * writeset)
1009 {
1010         struct {
1011                 u_int8_t version;
1012                 u_int8_t command;
1013                 u_int8_t reserved;
1014                 u_int8_t atyp;
1015         } s5_req, s5_rsp;
1016         u_int16_t dest_port;
1017         u_char *p, dest_addr[255+1];
1018         u_int have, i, found, nmethods, addrlen, af;
1019
1020         debug2("channel %d: decode socks5", c->self);
1021         p = buffer_ptr(&c->input);
1022         if (p[0] != 0x05)
1023                 return -1;
1024         have = buffer_len(&c->input);
1025         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1026                 /* format: ver | nmethods | methods */
1027                 if (have < 2)
1028                         return 0;
1029                 nmethods = p[1];
1030                 if (have < nmethods + 2)
1031                         return 0;
1032                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1033                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1034                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
1035                                 found = 1;
1036                                 break;
1037                         }
1038                 }
1039                 if (!found) {
1040                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1041                             c->self);
1042                         return -1;
1043                 }
1044                 buffer_consume(&c->input, nmethods + 2);
1045                 buffer_put_char(&c->output, 0x05);              /* version */
1046                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1047                 FD_SET(c->sock, writeset);
1048                 c->flags |= SSH_SOCKS5_AUTHDONE;
1049                 debug2("channel %d: socks5 auth done", c->self);
1050                 return 0;                               /* need more */
1051         }
1052         debug2("channel %d: socks5 post auth", c->self);
1053         if (have < sizeof(s5_req)+1)
1054                 return 0;                       /* need more */
1055         memcpy((char *)&s5_req, p, sizeof(s5_req));
1056         if (s5_req.version != 0x05 ||
1057             s5_req.command != SSH_SOCKS5_CONNECT ||
1058             s5_req.reserved != 0x00) {
1059                 debug2("channel %d: only socks5 connect supported", c->self);
1060                 return -1;
1061         }
1062         switch (s5_req.atyp){
1063         case SSH_SOCKS5_IPV4:
1064                 addrlen = 4;
1065                 af = AF_INET;
1066                 break;
1067         case SSH_SOCKS5_DOMAIN:
1068                 addrlen = p[sizeof(s5_req)];
1069                 af = -1;
1070                 break;
1071         case SSH_SOCKS5_IPV6:
1072                 addrlen = 16;
1073                 af = AF_INET6;
1074                 break;
1075         default:
1076                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1077                 return -1;
1078         }
1079         if (have < 4 + addrlen + 2)
1080                 return 0;
1081         buffer_consume(&c->input, sizeof(s5_req));
1082         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1083                 buffer_consume(&c->input, 1);    /* host string length */
1084         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1085         buffer_get(&c->input, (char *)&dest_port, 2);
1086         dest_addr[addrlen] = '\0';
1087         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1088                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1089         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1090                 return -1;
1091         c->host_port = ntohs(dest_port);
1092
1093         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1094             c->self, c->path, c->host_port, s5_req.command);
1095
1096         s5_rsp.version = 0x05;
1097         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1098         s5_rsp.reserved = 0;                    /* ignored */
1099         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1100         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1101         dest_port = 0;                          /* ignored */
1102
1103         buffer_append(&c->output, (char *)&s5_rsp, sizeof(s5_rsp));
1104         buffer_append(&c->output, (char *)&dest_addr, sizeof(struct in_addr));
1105         buffer_append(&c->output, (char *)&dest_port, sizeof(dest_port));
1106         return 1;
1107 }
1108
1109 /* dynamic port forwarding */
1110 static void
1111 channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
1112 {
1113         u_char *p;
1114         u_int have;
1115         int ret;
1116
1117         have = buffer_len(&c->input);
1118         c->delayed = 0;
1119         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1120         /* buffer_dump(&c->input); */
1121         /* check if the fixed size part of the packet is in buffer. */
1122         if (have < 3) {
1123                 /* need more */
1124                 FD_SET(c->sock, readset);
1125                 return;
1126         }
1127         /* try to guess the protocol */
1128         p = buffer_ptr(&c->input);
1129         switch (p[0]) {
1130         case 0x04:
1131                 ret = channel_decode_socks4(c, readset, writeset);
1132                 break;
1133         case 0x05:
1134                 ret = channel_decode_socks5(c, readset, writeset);
1135                 break;
1136         default:
1137                 ret = -1;
1138                 break;
1139         }
1140         if (ret < 0) {
1141                 chan_mark_dead(c);
1142         } else if (ret == 0) {
1143                 debug2("channel %d: pre_dynamic: need more", c->self);
1144                 /* need more */
1145                 FD_SET(c->sock, readset);
1146         } else {
1147                 /* switch to the next state */
1148                 c->type = SSH_CHANNEL_OPENING;
1149                 port_open_helper(c, "direct-tcpip");
1150         }
1151 }
1152
1153 /* This is our fake X11 server socket. */
1154 static void
1155 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
1156 {
1157         Channel *nc;
1158         struct sockaddr addr;
1159         int newsock;
1160         socklen_t addrlen;
1161         char buf[16384], *remote_ipaddr;
1162         int remote_port;
1163
1164         if (FD_ISSET(c->sock, readset)) {
1165                 debug("X11 connection requested.");
1166                 addrlen = sizeof(addr);
1167                 newsock = accept(c->sock, &addr, &addrlen);
1168                 if (c->single_connection) {
1169                         debug2("single_connection: closing X11 listener.");
1170                         channel_close_fd(&c->sock);
1171                         chan_mark_dead(c);
1172                 }
1173                 if (newsock < 0) {
1174                         error("accept: %.100s", strerror(errno));
1175                         return;
1176                 }
1177                 set_nodelay(newsock);
1178                 remote_ipaddr = get_peer_ipaddr(newsock);
1179                 remote_port = get_peer_port(newsock);
1180                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1181                     remote_ipaddr, remote_port);
1182
1183                 nc = channel_new("accepted x11 socket",
1184                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1185                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1186                 if (compat20) {
1187                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1188                         packet_put_cstring("x11");
1189                         packet_put_int(nc->self);
1190                         packet_put_int(nc->local_window_max);
1191                         packet_put_int(nc->local_maxpacket);
1192                         /* originator ipaddr and port */
1193                         packet_put_cstring(remote_ipaddr);
1194                         if (datafellows & SSH_BUG_X11FWD) {
1195                                 debug2("ssh2 x11 bug compat mode");
1196                         } else {
1197                                 packet_put_int(remote_port);
1198                         }
1199                         packet_send();
1200                 } else {
1201                         packet_start(SSH_SMSG_X11_OPEN);
1202                         packet_put_int(nc->self);
1203                         if (packet_get_protocol_flags() &
1204                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1205                                 packet_put_cstring(buf);
1206                         packet_send();
1207                 }
1208                 xfree(remote_ipaddr);
1209         }
1210 }
1211
1212 static void
1213 port_open_helper(Channel *c, char *rtype)
1214 {
1215         int direct;
1216         char buf[1024];
1217         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1218         int remote_port = get_peer_port(c->sock);
1219
1220         direct = (strcmp(rtype, "direct-tcpip") == 0);
1221
1222         snprintf(buf, sizeof buf,
1223             "%s: listening port %d for %.100s port %d, "
1224             "connect from %.200s port %d",
1225             rtype, c->listening_port, c->path, c->host_port,
1226             remote_ipaddr, remote_port);
1227
1228         xfree(c->remote_name);
1229         c->remote_name = xstrdup(buf);
1230
1231         if (compat20) {
1232                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1233                 packet_put_cstring(rtype);
1234                 packet_put_int(c->self);
1235                 packet_put_int(c->local_window_max);
1236                 packet_put_int(c->local_maxpacket);
1237                 if (direct) {
1238                         /* target host, port */
1239                         packet_put_cstring(c->path);
1240                         packet_put_int(c->host_port);
1241                 } else {
1242                         /* listen address, port */
1243                         packet_put_cstring(c->path);
1244                         packet_put_int(c->listening_port);
1245                 }
1246                 /* originator host and port */
1247                 packet_put_cstring(remote_ipaddr);
1248                 packet_put_int((u_int)remote_port);
1249                 packet_send();
1250         } else {
1251                 packet_start(SSH_MSG_PORT_OPEN);
1252                 packet_put_int(c->self);
1253                 packet_put_cstring(c->path);
1254                 packet_put_int(c->host_port);
1255                 if (packet_get_protocol_flags() &
1256                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1257                         packet_put_cstring(c->remote_name);
1258                 packet_send();
1259         }
1260         xfree(remote_ipaddr);
1261 }
1262
1263 static void
1264 channel_set_reuseaddr(int fd)
1265 {
1266         int on = 1;
1267
1268         /*
1269          * Set socket options.
1270          * Allow local port reuse in TIME_WAIT.
1271          */
1272         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1273                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1274 }
1275
1276 /*
1277  * This socket is listening for connections to a forwarded TCP/IP port.
1278  */
1279 static void
1280 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
1281 {
1282         Channel *nc;
1283         struct sockaddr addr;
1284         int newsock, nextstate;
1285         socklen_t addrlen;
1286         char *rtype;
1287
1288         if (FD_ISSET(c->sock, readset)) {
1289                 debug("Connection to port %d forwarding "
1290                     "to %.100s port %d requested.",
1291                     c->listening_port, c->path, c->host_port);
1292
1293                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1294                         nextstate = SSH_CHANNEL_OPENING;
1295                         rtype = "forwarded-tcpip";
1296                 } else {
1297                         if (c->host_port == 0) {
1298                                 nextstate = SSH_CHANNEL_DYNAMIC;
1299                                 rtype = "dynamic-tcpip";
1300                         } else {
1301                                 nextstate = SSH_CHANNEL_OPENING;
1302                                 rtype = "direct-tcpip";
1303                         }
1304                 }
1305
1306                 addrlen = sizeof(addr);
1307                 newsock = accept(c->sock, &addr, &addrlen);
1308                 if (newsock < 0) {
1309                         error("accept: %.100s", strerror(errno));
1310                         return;
1311                 }
1312                 set_nodelay(newsock);
1313                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1314                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1315                 nc->listening_port = c->listening_port;
1316                 nc->host_port = c->host_port;
1317                 strlcpy(nc->path, c->path, sizeof(nc->path));
1318
1319                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1320                         /*
1321                          * do not call the channel_post handler until
1322                          * this flag has been reset by a pre-handler.
1323                          * otherwise the FD_ISSET calls might overflow
1324                          */
1325                         nc->delayed = 1;
1326                 } else {
1327                         port_open_helper(nc, rtype);
1328                 }
1329         }
1330 }
1331
1332 /*
1333  * This is the authentication agent socket listening for connections from
1334  * clients.
1335  */
1336 static void
1337 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
1338 {
1339         Channel *nc;
1340         int newsock;
1341         struct sockaddr addr;
1342         socklen_t addrlen;
1343
1344         if (FD_ISSET(c->sock, readset)) {
1345                 addrlen = sizeof(addr);
1346                 newsock = accept(c->sock, &addr, &addrlen);
1347                 if (newsock < 0) {
1348                         error("accept from auth socket: %.100s", strerror(errno));
1349                         return;
1350                 }
1351                 nc = channel_new("accepted auth socket",
1352                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1353                     c->local_window_max, c->local_maxpacket,
1354                     0, "accepted auth socket", 1);
1355                 if (compat20) {
1356                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1357                         packet_put_cstring("auth-agent@openssh.com");
1358                         packet_put_int(nc->self);
1359                         packet_put_int(c->local_window_max);
1360                         packet_put_int(c->local_maxpacket);
1361                 } else {
1362                         packet_start(SSH_SMSG_AGENT_OPEN);
1363                         packet_put_int(nc->self);
1364                 }
1365                 packet_send();
1366         }
1367 }
1368
1369 static void
1370 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
1371 {
1372         int err = 0;
1373         socklen_t sz = sizeof(err);
1374
1375         if (FD_ISSET(c->sock, writeset)) {
1376                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1377                         err = errno;
1378                         error("getsockopt SO_ERROR failed");
1379                 }
1380                 if (err == 0) {
1381                         debug("channel %d: connected", c->self);
1382                         c->type = SSH_CHANNEL_OPEN;
1383                         if (compat20) {
1384                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1385                                 packet_put_int(c->remote_id);
1386                                 packet_put_int(c->self);
1387                                 packet_put_int(c->local_window);
1388                                 packet_put_int(c->local_maxpacket);
1389                         } else {
1390                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1391                                 packet_put_int(c->remote_id);
1392                                 packet_put_int(c->self);
1393                         }
1394                 } else {
1395                         debug("channel %d: not connected: %s",
1396                             c->self, strerror(err));
1397                         if (compat20) {
1398                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1399                                 packet_put_int(c->remote_id);
1400                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1401                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1402                                         packet_put_cstring(strerror(err));
1403                                         packet_put_cstring("");
1404                                 }
1405                         } else {
1406                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1407                                 packet_put_int(c->remote_id);
1408                         }
1409                         chan_mark_dead(c);
1410                 }
1411                 packet_send();
1412         }
1413 }
1414
1415 static int
1416 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
1417 {
1418         char buf[CHAN_RBUF];
1419         int len;
1420
1421         if (c->rfd != -1 &&
1422             FD_ISSET(c->rfd, readset)) {
1423                 len = read(c->rfd, buf, sizeof(buf));
1424                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1425                         return 1;
1426                 if (len <= 0) {
1427                         debug2("channel %d: read<=0 rfd %d len %d",
1428                             c->self, c->rfd, len);
1429                         if (c->type != SSH_CHANNEL_OPEN) {
1430                                 debug2("channel %d: not open", c->self);
1431                                 chan_mark_dead(c);
1432                                 return -1;
1433                         } else if (compat13) {
1434                                 buffer_clear(&c->output);
1435                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1436                                 debug2("channel %d: input draining.", c->self);
1437                         } else {
1438                                 chan_read_failed(c);
1439                         }
1440                         return -1;
1441                 }
1442                 if (c->input_filter != NULL) {
1443                         if (c->input_filter(c, buf, len) == -1) {
1444                                 debug2("channel %d: filter stops", c->self);
1445                                 chan_read_failed(c);
1446                         }
1447                 } else if (c->datagram) {
1448                         buffer_put_string(&c->input, buf, len);
1449                 } else {
1450                         buffer_append(&c->input, buf, len);
1451                 }
1452         }
1453         return 1;
1454 }
1455 static int
1456 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
1457 {
1458         struct termios tio;
1459         u_char *data = NULL, *buf;
1460         u_int dlen;
1461         int len;
1462
1463         /* Send buffered output data to the socket. */
1464         if (c->wfd != -1 &&
1465             FD_ISSET(c->wfd, writeset) &&
1466             buffer_len(&c->output) > 0) {
1467                 if (c->output_filter != NULL) {
1468                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1469                                 debug2("channel %d: filter stops", c->self);
1470                                 if (c->type != SSH_CHANNEL_OPEN)
1471                                         chan_mark_dead(c);
1472                                 else
1473                                         chan_write_failed(c);
1474                                 return -1;
1475                         }
1476                 } else if (c->datagram) {
1477                         buf = data = buffer_get_string(&c->output, &dlen);
1478                 } else {
1479                         buf = data = buffer_ptr(&c->output);
1480                         dlen = buffer_len(&c->output);
1481                 }
1482
1483                 if (c->datagram) {
1484                         /* ignore truncated writes, datagrams might get lost */
1485                         c->local_consumed += dlen + 4;
1486                         len = write(c->wfd, buf, dlen);
1487                         xfree(data);
1488                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1489                                 return 1;
1490                         if (len <= 0) {
1491                                 if (c->type != SSH_CHANNEL_OPEN)
1492                                         chan_mark_dead(c);
1493                                 else
1494                                         chan_write_failed(c);
1495                                 return -1;
1496                         }
1497                         return 1;
1498                 }
1499 #ifdef _AIX
1500                 /* XXX: Later AIX versions can't push as much data to tty */
1501                 if (compat20 && c->wfd_isatty)
1502                         dlen = MIN(dlen, 8*1024);
1503 #endif
1504
1505                 len = write(c->wfd, buf, dlen);
1506                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1507                         return 1;
1508                 if (len <= 0) {
1509                         if (c->type != SSH_CHANNEL_OPEN) {
1510                                 debug2("channel %d: not open", c->self);
1511                                 chan_mark_dead(c);
1512                                 return -1;
1513                         } else if (compat13) {
1514                                 buffer_clear(&c->output);
1515                                 debug2("channel %d: input draining.", c->self);
1516                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1517                         } else {
1518                                 chan_write_failed(c);
1519                         }
1520                         return -1;
1521                 }
1522                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1523                         if (tcgetattr(c->wfd, &tio) == 0 &&
1524                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1525                                 /*
1526                                  * Simulate echo to reduce the impact of
1527                                  * traffic analysis. We need to match the
1528                                  * size of a SSH2_MSG_CHANNEL_DATA message
1529                                  * (4 byte channel id + buf)
1530                                  */
1531                                 packet_send_ignore(4 + len);
1532                                 packet_send();
1533                         }
1534                 }
1535                 buffer_consume(&c->output, len);
1536                 if (compat20 && len > 0) {
1537                         c->local_consumed += len;
1538                 }
1539         }
1540         return 1;
1541 }
1542 static int
1543 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
1544 {
1545         char buf[CHAN_RBUF];
1546         int len;
1547
1548 /** XXX handle drain efd, too */
1549         if (c->efd != -1) {
1550                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1551                     FD_ISSET(c->efd, writeset) &&
1552                     buffer_len(&c->extended) > 0) {
1553                         len = write(c->efd, buffer_ptr(&c->extended),
1554                             buffer_len(&c->extended));
1555                         debug2("channel %d: written %d to efd %d",
1556                             c->self, len, c->efd);
1557                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1558                                 return 1;
1559                         if (len <= 0) {
1560                                 debug2("channel %d: closing write-efd %d",
1561                                     c->self, c->efd);
1562                                 channel_close_fd(&c->efd);
1563                         } else {
1564                                 buffer_consume(&c->extended, len);
1565                                 c->local_consumed += len;
1566                         }
1567                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1568                     FD_ISSET(c->efd, readset)) {
1569                         len = read(c->efd, buf, sizeof(buf));
1570                         debug2("channel %d: read %d from efd %d",
1571                             c->self, len, c->efd);
1572                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1573                                 return 1;
1574                         if (len <= 0) {
1575                                 debug2("channel %d: closing read-efd %d",
1576                                     c->self, c->efd);
1577                                 channel_close_fd(&c->efd);
1578                         } else {
1579                                 buffer_append(&c->extended, buf, len);
1580                         }
1581                 }
1582         }
1583         return 1;
1584 }
1585 static int
1586 channel_handle_ctl(Channel *c, fd_set * readset, fd_set * writeset)
1587 {
1588         char buf[16];
1589         int len;
1590
1591         /* Monitor control fd to detect if the slave client exits */
1592         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1593                 len = read(c->ctl_fd, buf, sizeof(buf));
1594                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1595                         return 1;
1596                 if (len <= 0) {
1597                         debug2("channel %d: ctl read<=0", c->self);
1598                         if (c->type != SSH_CHANNEL_OPEN) {
1599                                 debug2("channel %d: not open", c->self);
1600                                 chan_mark_dead(c);
1601                                 return -1;
1602                         } else {
1603                                 chan_read_failed(c);
1604                                 chan_write_failed(c);
1605                         }
1606                         return -1;
1607                 } else
1608                         fatal("%s: unexpected data on ctl fd", __func__);
1609         }
1610         return 1;
1611 }
1612 static int
1613 channel_check_window(Channel *c)
1614 {
1615         if (c->type == SSH_CHANNEL_OPEN &&
1616             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1617             c->local_window < c->local_window_max/2 &&
1618             c->local_consumed > 0) {
1619                 u_int32_t tcpwinsz = 0;
1620                 socklen_t optsz = sizeof(tcpwinsz);
1621                 int ret = -1;
1622                 u_int32_t addition = 0;
1623                 if (c->dynamic_window) {
1624                         ret = getsockopt(packet_get_connection_in(),
1625                                 SOL_SOCKET, SO_RCVBUF, &tcpwinsz, &optsz);
1626                         if ((ret == 0) && tcpwinsz > BUFFER_MAX_HPN_LEN)
1627                                 tcpwinsz = BUFFER_MAX_HPN_LEN;
1628                 }
1629                 if (c->dynamic_window && (ret == 0) &&
1630                     (tcpwinsz > c->local_window_max)) {
1631                         addition = tcpwinsz - c->local_window_max;
1632                         c->local_window_max += addition;
1633                 }
1634                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1635                 packet_put_int(c->remote_id);
1636                 packet_put_int(c->local_consumed + addition);
1637                 packet_send();
1638                 debug2("channel %d: window %d sent adjust %d",
1639                     c->self, c->local_window,
1640                     c->local_consumed);
1641                 c->local_window += c->local_consumed + addition;
1642                 c->local_consumed = 0;
1643         }
1644         return 1;
1645 }
1646
1647 static void
1648 channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
1649 {
1650         if (c->delayed)
1651                 return;
1652         channel_handle_rfd(c, readset, writeset);
1653         channel_handle_wfd(c, readset, writeset);
1654         if (!compat20)
1655                 return;
1656         channel_handle_efd(c, readset, writeset);
1657         channel_handle_ctl(c, readset, writeset);
1658         channel_check_window(c);
1659 }
1660
1661 static void
1662 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
1663 {
1664         int len;
1665
1666         /* Send buffered output data to the socket. */
1667         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1668                 len = write(c->sock, buffer_ptr(&c->output),
1669                             buffer_len(&c->output));
1670                 if (len <= 0)
1671                         buffer_clear(&c->output);
1672                 else
1673                         buffer_consume(&c->output, len);
1674         }
1675 }
1676
1677 static void
1678 channel_handler_init_20(void)
1679 {
1680         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1681         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1682         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1683         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1684         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1685         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1686         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1687         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1688
1689         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1690         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1691         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1692         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1693         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1694         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1695         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1696 }
1697
1698 static void
1699 channel_handler_init_13(void)
1700 {
1701         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1702         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1703         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1704         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1705         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1706         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1707         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1708         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1709         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1710
1711         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1712         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1713         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1714         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1715         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1716         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1717         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1718 }
1719
1720 static void
1721 channel_handler_init_15(void)
1722 {
1723         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1724         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1725         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1726         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1727         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1728         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1729         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1730
1731         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1732         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1733         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1734         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1735         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1736         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1737 }
1738
1739 static void
1740 channel_handler_init(void)
1741 {
1742         int i;
1743
1744         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1745                 channel_pre[i] = NULL;
1746                 channel_post[i] = NULL;
1747         }
1748         if (compat20)
1749                 channel_handler_init_20();
1750         else if (compat13)
1751                 channel_handler_init_13();
1752         else
1753                 channel_handler_init_15();
1754 }
1755
1756 /* gc dead channels */
1757 static void
1758 channel_garbage_collect(Channel *c)
1759 {
1760         if (c == NULL)
1761                 return;
1762         if (c->detach_user != NULL) {
1763                 if (!chan_is_dead(c, c->detach_close))
1764                         return;
1765                 debug2("channel %d: gc: notify user", c->self);
1766                 c->detach_user(c->self, NULL);
1767                 /* if we still have a callback */
1768                 if (c->detach_user != NULL)
1769                         return;
1770                 debug2("channel %d: gc: user detached", c->self);
1771         }
1772         if (!chan_is_dead(c, 1))
1773                 return;
1774         debug2("channel %d: garbage collecting", c->self);
1775         channel_free(c);
1776 }
1777
1778 static void
1779 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
1780 {
1781         static int did_init = 0;
1782         u_int i;
1783         Channel *c;
1784
1785         if (!did_init) {
1786                 channel_handler_init();
1787                 did_init = 1;
1788         }
1789         for (i = 0; i < channels_alloc; i++) {
1790                 c = channels[i];
1791                 if (c == NULL)
1792                         continue;
1793                 if (ftab[c->type] != NULL)
1794                         (*ftab[c->type])(c, readset, writeset);
1795                 channel_garbage_collect(c);
1796         }
1797 }
1798
1799 /*
1800  * Allocate/update select bitmasks and add any bits relevant to channels in
1801  * select bitmasks.
1802  */
1803 void
1804 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1805     u_int *nallocp, int rekeying)
1806 {
1807         u_int n, sz;
1808
1809         n = MAX(*maxfdp, channel_max_fd);
1810
1811         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
1812         /* perhaps check sz < nalloc/2 and shrink? */
1813         if (*readsetp == NULL || sz > *nallocp) {
1814                 *readsetp = xrealloc(*readsetp, sz);
1815                 *writesetp = xrealloc(*writesetp, sz);
1816                 *nallocp = sz;
1817         }
1818         *maxfdp = n;
1819         memset(*readsetp, 0, sz);
1820         memset(*writesetp, 0, sz);
1821
1822         if (!rekeying)
1823                 channel_handler(channel_pre, *readsetp, *writesetp);
1824 }
1825
1826 /*
1827  * After select, perform any appropriate operations for channels which have
1828  * events pending.
1829  */
1830 void
1831 channel_after_select(fd_set * readset, fd_set * writeset)
1832 {
1833         channel_handler(channel_post, readset, writeset);
1834 }
1835
1836
1837 /* If there is data to send to the connection, enqueue some of it now. */
1838
1839 void
1840 channel_output_poll(void)
1841 {
1842         Channel *c;
1843         u_int i, len;
1844
1845         for (i = 0; i < channels_alloc; i++) {
1846                 c = channels[i];
1847                 if (c == NULL)
1848                         continue;
1849
1850                 /*
1851                  * We are only interested in channels that can have buffered
1852                  * incoming data.
1853                  */
1854                 if (compat13) {
1855                         if (c->type != SSH_CHANNEL_OPEN &&
1856                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1857                                 continue;
1858                 } else {
1859                         if (c->type != SSH_CHANNEL_OPEN)
1860                                 continue;
1861                 }
1862                 if (compat20 &&
1863                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1864                         /* XXX is this true? */
1865                         debug3("channel %d: will not send data after close", c->self);
1866                         continue;
1867                 }
1868
1869                 /* Get the amount of buffered data for this channel. */
1870                 if ((c->istate == CHAN_INPUT_OPEN ||
1871                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1872                     (len = buffer_len(&c->input)) > 0) {
1873                         if (c->datagram) {
1874                                 if (len > 0) {
1875                                         u_char *data;
1876                                         u_int dlen;
1877
1878                                         data = buffer_get_string(&c->input,
1879                                             &dlen);
1880                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1881                                         packet_put_int(c->remote_id);
1882                                         packet_put_string(data, dlen);
1883                                         packet_send();
1884                                         c->remote_window -= dlen + 4;
1885                                         xfree(data);
1886                                 }
1887                                 continue;
1888                         }
1889                         /*
1890                          * Send some data for the other side over the secure
1891                          * connection.
1892                          */
1893                         if (compat20) {
1894                                 if (len > c->remote_window)
1895                                         len = c->remote_window;
1896                                 if (len > c->remote_maxpacket)
1897                                         len = c->remote_maxpacket;
1898                         } else {
1899                                 if (packet_is_interactive()) {
1900                                         if (len > 1024)
1901                                                 len = 512;
1902                                 } else {
1903                                         /* Keep the packets at reasonable size. */
1904                                         if (len > packet_get_maxsize()/2)
1905                                                 len = packet_get_maxsize()/2;
1906                                 }
1907                         }
1908                         if (len > 0) {
1909                                 packet_start(compat20 ?
1910                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1911                                 packet_put_int(c->remote_id);
1912                                 packet_put_string(buffer_ptr(&c->input), len);
1913                                 packet_send();
1914                                 buffer_consume(&c->input, len);
1915                                 c->remote_window -= len;
1916                         }
1917                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1918                         if (compat13)
1919                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1920                         /*
1921                          * input-buffer is empty and read-socket shutdown:
1922                          * tell peer, that we will not send more data: send IEOF.
1923                          * hack for extended data: delay EOF if EFD still in use.
1924                          */
1925                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1926                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1927                                     c->self, c->efd, buffer_len(&c->extended));
1928                         else
1929                                 chan_ibuf_empty(c);
1930                 }
1931                 /* Send extended data, i.e. stderr */
1932                 if (compat20 &&
1933                     !(c->flags & CHAN_EOF_SENT) &&
1934                     c->remote_window > 0 &&
1935                     (len = buffer_len(&c->extended)) > 0 &&
1936                     c->extended_usage == CHAN_EXTENDED_READ) {
1937                         debug2("channel %d: rwin %u elen %u euse %d",
1938                             c->self, c->remote_window, buffer_len(&c->extended),
1939                             c->extended_usage);
1940                         if (len > c->remote_window)
1941                                 len = c->remote_window;
1942                         if (len > c->remote_maxpacket)
1943                                 len = c->remote_maxpacket;
1944                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1945                         packet_put_int(c->remote_id);
1946                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1947                         packet_put_string(buffer_ptr(&c->extended), len);
1948                         packet_send();
1949                         buffer_consume(&c->extended, len);
1950                         c->remote_window -= len;
1951                         debug2("channel %d: sent ext data %d", c->self, len);
1952                 }
1953         }
1954 }
1955
1956
1957 /* -- protocol input */
1958
1959 void
1960 channel_input_data(int type, u_int32_t seq, void *ctxt)
1961 {
1962         int id;
1963         char *data;
1964         u_int data_len;
1965         Channel *c;
1966
1967         /* Get the channel number and verify it. */
1968         id = packet_get_int();
1969         c = channel_lookup(id);
1970         if (c == NULL)
1971                 packet_disconnect("Received data for nonexistent channel %d.", id);
1972
1973         /* Ignore any data for non-open channels (might happen on close) */
1974         if (c->type != SSH_CHANNEL_OPEN &&
1975             c->type != SSH_CHANNEL_X11_OPEN)
1976                 return;
1977
1978         /* Get the data. */
1979         data = packet_get_string(&data_len);
1980
1981         /*
1982          * Ignore data for protocol > 1.3 if output end is no longer open.
1983          * For protocol 2 the sending side is reducing its window as it sends
1984          * data, so we must 'fake' consumption of the data in order to ensure
1985          * that window updates are sent back.  Otherwise the connection might
1986          * deadlock.
1987          */
1988         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1989                 if (compat20) {
1990                         c->local_window -= data_len;
1991                         c->local_consumed += data_len;
1992                 }
1993                 xfree(data);
1994                 return;
1995         }
1996
1997         if (compat20) {
1998                 if (data_len > c->local_maxpacket) {
1999                         logit("channel %d: rcvd big packet %d, maxpack %d",
2000                             c->self, data_len, c->local_maxpacket);
2001                 }
2002                 if (data_len > c->local_window) {
2003                         logit("channel %d: rcvd too much data %d, win %d",
2004                             c->self, data_len, c->local_window);
2005                         xfree(data);
2006                         return;
2007                 }
2008                 c->local_window -= data_len;
2009         }
2010         packet_check_eom();
2011         if (c->datagram)
2012                 buffer_put_string(&c->output, data, data_len);
2013         else
2014                 buffer_append(&c->output, data, data_len);
2015         xfree(data);
2016 }
2017
2018 void
2019 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2020 {
2021         int id;
2022         char *data;
2023         u_int data_len, tcode;
2024         Channel *c;
2025
2026         /* Get the channel number and verify it. */
2027         id = packet_get_int();
2028         c = channel_lookup(id);
2029
2030         if (c == NULL)
2031                 packet_disconnect("Received extended_data for bad channel %d.", id);
2032         if (c->type != SSH_CHANNEL_OPEN) {
2033                 logit("channel %d: ext data for non open", id);
2034                 return;
2035         }
2036         if (c->flags & CHAN_EOF_RCVD) {
2037                 if (datafellows & SSH_BUG_EXTEOF)
2038                         debug("channel %d: accepting ext data after eof", id);
2039                 else
2040                         packet_disconnect("Received extended_data after EOF "
2041                             "on channel %d.", id);
2042         }
2043         tcode = packet_get_int();
2044         if (c->efd == -1 ||
2045             c->extended_usage != CHAN_EXTENDED_WRITE ||
2046             tcode != SSH2_EXTENDED_DATA_STDERR) {
2047                 logit("channel %d: bad ext data", c->self);
2048                 return;
2049         }
2050         data = packet_get_string(&data_len);
2051         packet_check_eom();
2052         if (data_len > c->local_window) {
2053                 logit("channel %d: rcvd too much extended_data %d, win %d",
2054                     c->self, data_len, c->local_window);
2055                 xfree(data);
2056                 return;
2057         }
2058         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2059         c->local_window -= data_len;
2060         buffer_append(&c->extended, data, data_len);
2061         xfree(data);
2062 }
2063
2064 void
2065 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2066 {
2067         int id;
2068         Channel *c;
2069
2070         id = packet_get_int();
2071         packet_check_eom();
2072         c = channel_lookup(id);
2073         if (c == NULL)
2074                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2075         chan_rcvd_ieof(c);
2076
2077         /* XXX force input close */
2078         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2079                 debug("channel %d: FORCE input drain", c->self);
2080                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2081                 if (buffer_len(&c->input) == 0)
2082                         chan_ibuf_empty(c);
2083         }
2084
2085 }
2086
2087 void
2088 channel_input_close(int type, u_int32_t seq, void *ctxt)
2089 {
2090         int id;
2091         Channel *c;
2092
2093         id = packet_get_int();
2094         packet_check_eom();
2095         c = channel_lookup(id);
2096         if (c == NULL)
2097                 packet_disconnect("Received close for nonexistent channel %d.", id);
2098
2099         /*
2100          * Send a confirmation that we have closed the channel and no more
2101          * data is coming for it.
2102          */
2103         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2104         packet_put_int(c->remote_id);
2105         packet_send();
2106
2107         /*
2108          * If the channel is in closed state, we have sent a close request,
2109          * and the other side will eventually respond with a confirmation.
2110          * Thus, we cannot free the channel here, because then there would be
2111          * no-one to receive the confirmation.  The channel gets freed when
2112          * the confirmation arrives.
2113          */
2114         if (c->type != SSH_CHANNEL_CLOSED) {
2115                 /*
2116                  * Not a closed channel - mark it as draining, which will
2117                  * cause it to be freed later.
2118                  */
2119                 buffer_clear(&c->input);
2120                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2121         }
2122 }
2123
2124 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2125 void
2126 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2127 {
2128         int id = packet_get_int();
2129         Channel *c = channel_lookup(id);
2130
2131         packet_check_eom();
2132         if (c == NULL)
2133                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2134         chan_rcvd_oclose(c);
2135 }
2136
2137 void
2138 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2139 {
2140         int id = packet_get_int();
2141         Channel *c = channel_lookup(id);
2142
2143         packet_check_eom();
2144         if (c == NULL)
2145                 packet_disconnect("Received close confirmation for "
2146                     "out-of-range channel %d.", id);
2147         if (c->type != SSH_CHANNEL_CLOSED)
2148                 packet_disconnect("Received close confirmation for "
2149                     "non-closed channel %d (type %d).", id, c->type);
2150         channel_free(c);
2151 }
2152
2153 void
2154 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2155 {
2156         int id, remote_id;
2157         Channel *c;
2158
2159         id = packet_get_int();
2160         c = channel_lookup(id);
2161
2162         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2163                 packet_disconnect("Received open confirmation for "
2164                     "non-opening channel %d.", id);
2165         remote_id = packet_get_int();
2166         /* Record the remote channel number and mark that the channel is now open. */
2167         c->remote_id = remote_id;
2168         c->type = SSH_CHANNEL_OPEN;
2169
2170         if (compat20) {
2171                 c->remote_window = packet_get_int();
2172                 c->remote_maxpacket = packet_get_int();
2173                 if (c->confirm) {
2174                         debug2("callback start");
2175                         c->confirm(c->self, c->confirm_ctx);
2176                         debug2("callback done");
2177                 }
2178                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2179                     c->remote_window, c->remote_maxpacket);
2180         }
2181         packet_check_eom();
2182 }
2183
2184 static char *
2185 reason2txt(int reason)
2186 {
2187         switch (reason) {
2188         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2189                 return "administratively prohibited";
2190         case SSH2_OPEN_CONNECT_FAILED:
2191                 return "connect failed";
2192         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2193                 return "unknown channel type";
2194         case SSH2_OPEN_RESOURCE_SHORTAGE:
2195                 return "resource shortage";
2196         }
2197         return "unknown reason";
2198 }
2199
2200 void
2201 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2202 {
2203         int id, reason;
2204         char *msg = NULL, *lang = NULL;
2205         Channel *c;
2206
2207         id = packet_get_int();
2208         c = channel_lookup(id);
2209
2210         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2211                 packet_disconnect("Received open failure for "
2212                     "non-opening channel %d.", id);
2213         if (compat20) {
2214                 reason = packet_get_int();
2215                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2216                         msg  = packet_get_string(NULL);
2217                         lang = packet_get_string(NULL);
2218                 }
2219                 logit("channel %d: open failed: %s%s%s", id,
2220                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2221                 if (msg != NULL)
2222                         xfree(msg);
2223                 if (lang != NULL)
2224                         xfree(lang);
2225         }
2226         packet_check_eom();
2227         /* Free the channel.  This will also close the socket. */
2228         channel_free(c);
2229 }
2230
2231 void
2232 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2233 {
2234         Channel *c;
2235         int id;
2236         u_int adjust;
2237
2238         if (!compat20)
2239                 return;
2240
2241         /* Get the channel number and verify it. */
2242         id = packet_get_int();
2243         c = channel_lookup(id);
2244
2245         if (c == NULL) {
2246                 logit("Received window adjust for non-open channel %d.", id);
2247                 return;
2248         }
2249         adjust = packet_get_int();
2250         packet_check_eom();
2251         debug2("channel %d: rcvd adjust %u", id, adjust);
2252         c->remote_window += adjust;
2253 }
2254
2255 void
2256 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2257 {
2258         Channel *c = NULL;
2259         u_short host_port;
2260         char *host, *originator_string;
2261         int remote_id, sock = -1;
2262
2263         remote_id = packet_get_int();
2264         host = packet_get_string(NULL);
2265         host_port = packet_get_int();
2266
2267         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2268                 originator_string = packet_get_string(NULL);
2269         } else {
2270                 originator_string = xstrdup("unknown (remote did not supply name)");
2271         }
2272         packet_check_eom();
2273         sock = channel_connect_to(host, host_port);
2274         if (sock != -1) {
2275                 c = channel_new("connected socket",
2276                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2277                     originator_string, 1);
2278                 c->remote_id = remote_id;
2279         }
2280         xfree(originator_string);
2281         if (c == NULL) {
2282                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2283                 packet_put_int(remote_id);
2284                 packet_send();
2285         }
2286         xfree(host);
2287 }
2288
2289
2290 /* -- tcp forwarding */
2291
2292 void
2293 channel_set_af(int af)
2294 {
2295         IPv4or6 = af;
2296 }
2297
2298 static int
2299 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2300     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2301 {
2302         Channel *c;
2303         int sock, r, success = 0, wildcard = 0, is_client;
2304         struct addrinfo hints, *ai, *aitop;
2305         const char *host, *addr;
2306         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2307
2308         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2309             listen_addr : host_to_connect;
2310         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2311
2312         if (host == NULL) {
2313                 error("No forward host name.");
2314                 return 0;
2315         }
2316         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2317                 error("Forward host name too long.");
2318                 return 0;
2319         }
2320
2321         /*
2322          * Determine whether or not a port forward listens to loopback,
2323          * specified address or wildcard. On the client, a specified bind
2324          * address will always override gateway_ports. On the server, a
2325          * gateway_ports of 1 (``yes'') will override the client's
2326          * specification and force a wildcard bind, whereas a value of 2
2327          * (``clientspecified'') will bind to whatever address the client
2328          * asked for.
2329          *
2330          * Special-case listen_addrs are:
2331          *
2332          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2333          * "" (empty string), "*"  -> wildcard v4/v6
2334          * "localhost"             -> loopback v4/v6
2335          */
2336         addr = NULL;
2337         if (listen_addr == NULL) {
2338                 /* No address specified: default to gateway_ports setting */
2339                 if (gateway_ports)
2340                         wildcard = 1;
2341         } else if (gateway_ports || is_client) {
2342                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2343                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2344                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2345                     (!is_client && gateway_ports == 1))
2346                         wildcard = 1;
2347                 else if (strcmp(listen_addr, "localhost") != 0)
2348                         addr = listen_addr;
2349         }
2350
2351         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2352             type, wildcard, (addr == NULL) ? "NULL" : addr);
2353
2354         /*
2355          * getaddrinfo returns a loopback address if the hostname is
2356          * set to NULL and hints.ai_flags is not AI_PASSIVE
2357          */
2358         memset(&hints, 0, sizeof(hints));
2359         hints.ai_family = IPv4or6;
2360         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2361         hints.ai_socktype = SOCK_STREAM;
2362         snprintf(strport, sizeof strport, "%d", listen_port);
2363         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2364                 if (addr == NULL) {
2365                         /* This really shouldn't happen */
2366                         packet_disconnect("getaddrinfo: fatal error: %s",
2367                             gai_strerror(r));
2368                 } else {
2369                         error("channel_setup_fwd_listener: "
2370                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2371                 }
2372                 return 0;
2373         }
2374
2375         for (ai = aitop; ai; ai = ai->ai_next) {
2376                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2377                         continue;
2378                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2379                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2380                         error("channel_setup_fwd_listener: getnameinfo failed");
2381                         continue;
2382                 }
2383                 /* Create a port to listen for the host. */
2384                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2385                 if (sock < 0) {
2386                         /* this is no error since kernel may not support ipv6 */
2387                         verbose("socket: %.100s", strerror(errno));
2388                         continue;
2389                 }
2390
2391                 channel_set_reuseaddr(sock);
2392
2393                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2394
2395                 /* Bind the socket to the address. */
2396                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2397                         /* address can be in use ipv6 address is already bound */
2398                         if (!ai->ai_next)
2399                                 error("bind: %.100s", strerror(errno));
2400                         else
2401                                 verbose("bind: %.100s", strerror(errno));
2402
2403                         close(sock);
2404                         continue;
2405                 }
2406                 /* Start listening for connections on the socket. */
2407                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2408                         error("listen: %.100s", strerror(errno));
2409                         close(sock);
2410                         continue;
2411                 }
2412                 /* Allocate a channel number for the socket. */
2413                 c = channel_new("port listener", type, sock, sock, -1,
2414                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2415                     0, "port listener", 1);
2416                 strlcpy(c->path, host, sizeof(c->path));
2417                 c->host_port = port_to_connect;
2418                 c->listening_port = listen_port;
2419                 success = 1;
2420         }
2421         if (success == 0)
2422                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2423                     listen_port);
2424         freeaddrinfo(aitop);
2425         return success;
2426 }
2427
2428 int
2429 channel_cancel_rport_listener(const char *host, u_short port)
2430 {
2431         u_int i;
2432         int found = 0;
2433
2434         for (i = 0; i < channels_alloc; i++) {
2435                 Channel *c = channels[i];
2436
2437                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2438                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2439                     c->listening_port == port) {
2440                         debug2("%s: close channel %d", __func__, i);
2441                         channel_free(c);
2442                         found = 1;
2443                 }
2444         }
2445
2446         return (found);
2447 }
2448
2449 /* protocol local port fwd, used by ssh (and sshd in v1) */
2450 int
2451 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2452     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2453 {
2454         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2455             listen_host, listen_port, host_to_connect, port_to_connect,
2456             gateway_ports);
2457 }
2458
2459 /* protocol v2 remote port fwd, used by sshd */
2460 int
2461 channel_setup_remote_fwd_listener(const char *listen_address,
2462     u_short listen_port, int gateway_ports)
2463 {
2464         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2465             listen_address, listen_port, NULL, 0, gateway_ports);
2466 }
2467
2468 /*
2469  * Initiate forwarding of connections to port "port" on remote host through
2470  * the secure channel to host:port from local side.
2471  */
2472
2473 void
2474 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2475     const char *host_to_connect, u_short port_to_connect)
2476 {
2477         int type, success = 0;
2478
2479         /* Record locally that connection to this host/port is permitted. */
2480         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2481                 fatal("channel_request_remote_forwarding: too many forwards");
2482
2483         /* Send the forward request to the remote side. */
2484         if (compat20) {
2485                 const char *address_to_bind;
2486                 if (listen_host == NULL)
2487                         address_to_bind = "localhost";
2488                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2489                         address_to_bind = "";
2490                 else
2491                         address_to_bind = listen_host;
2492
2493                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2494                 packet_put_cstring("tcpip-forward");
2495                 packet_put_char(1);                     /* boolean: want reply */
2496                 packet_put_cstring(address_to_bind);
2497                 packet_put_int(listen_port);
2498                 packet_send();
2499                 packet_write_wait();
2500                 /* Assume that server accepts the request */
2501                 success = 1;
2502         } else {
2503                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2504                 packet_put_int(listen_port);
2505                 packet_put_cstring(host_to_connect);
2506                 packet_put_int(port_to_connect);
2507                 packet_send();
2508                 packet_write_wait();
2509
2510                 /* Wait for response from the remote side. */
2511                 type = packet_read();
2512                 switch (type) {
2513                 case SSH_SMSG_SUCCESS:
2514                         success = 1;
2515                         break;
2516                 case SSH_SMSG_FAILURE:
2517                         logit("Warning: Server denied remote port forwarding.");
2518                         break;
2519                 default:
2520                         /* Unknown packet */
2521                         packet_disconnect("Protocol error for port forward request:"
2522                             "received packet type %d.", type);
2523                 }
2524         }
2525         if (success) {
2526                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2527                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2528                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2529                 num_permitted_opens++;
2530         }
2531 }
2532
2533 /*
2534  * Request cancellation of remote forwarding of connection host:port from
2535  * local side.
2536  */
2537 void
2538 channel_request_rforward_cancel(const char *host, u_short port)
2539 {
2540         int i;
2541
2542         if (!compat20)
2543                 return;
2544
2545         for (i = 0; i < num_permitted_opens; i++) {
2546                 if (permitted_opens[i].host_to_connect != NULL &&
2547                     permitted_opens[i].listen_port == port)
2548                         break;
2549         }
2550         if (i >= num_permitted_opens) {
2551                 debug("%s: requested forward not found", __func__);
2552                 return;
2553         }
2554         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2555         packet_put_cstring("cancel-tcpip-forward");
2556         packet_put_char(0);
2557         packet_put_cstring(host == NULL ? "" : host);
2558         packet_put_int(port);
2559         packet_send();
2560
2561         permitted_opens[i].listen_port = 0;
2562         permitted_opens[i].port_to_connect = 0;
2563         xfree(permitted_opens[i].host_to_connect);
2564         permitted_opens[i].host_to_connect = NULL;
2565 }
2566
2567 /*
2568  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2569  * listening for the port, and sends back a success reply (or disconnect
2570  * message if there was an error).  This never returns if there was an error.
2571  */
2572
2573 void
2574 channel_input_port_forward_request(int is_root, int gateway_ports)
2575 {
2576         u_short port, host_port;
2577         char *hostname;
2578
2579         /* Get arguments from the packet. */
2580         port = packet_get_int();
2581         hostname = packet_get_string(NULL);
2582         host_port = packet_get_int();
2583
2584 #ifndef HAVE_CYGWIN
2585         /*
2586          * Check that an unprivileged user is not trying to forward a
2587          * privileged port.
2588          */
2589         if (port < IPPORT_RESERVED && !is_root)
2590                 packet_disconnect(
2591                     "Requested forwarding of port %d but user is not root.",
2592                     port);
2593         if (host_port == 0)
2594                 packet_disconnect("Dynamic forwarding denied.");
2595 #endif
2596
2597         /* Initiate forwarding */
2598         channel_setup_local_fwd_listener(NULL, port, hostname,
2599             host_port, gateway_ports);
2600
2601         /* Free the argument string. */
2602         xfree(hostname);
2603 }
2604
2605 /*
2606  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2607  * usually called by the server, because the user could connect to any port
2608  * anyway, and the server has no way to know but to trust the client anyway.
2609  */
2610 void
2611 channel_permit_all_opens(void)
2612 {
2613         if (num_permitted_opens == 0)
2614                 all_opens_permitted = 1;
2615 }
2616
2617 void
2618 channel_add_permitted_opens(char *host, int port)
2619 {
2620         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2621                 fatal("channel_request_remote_forwarding: too many forwards");
2622         debug("allow port forwarding to host %s port %d", host, port);
2623
2624         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2625         permitted_opens[num_permitted_opens].port_to_connect = port;
2626         num_permitted_opens++;
2627
2628         all_opens_permitted = 0;
2629 }
2630
2631 void
2632 channel_clear_permitted_opens(void)
2633 {
2634         int i;
2635
2636         for (i = 0; i < num_permitted_opens; i++)
2637                 if (permitted_opens[i].host_to_connect != NULL)
2638                         xfree(permitted_opens[i].host_to_connect);
2639         num_permitted_opens = 0;
2640
2641 }
2642
2643
2644 /* return socket to remote host, port */
2645 static int
2646 connect_to(const char *host, u_short port)
2647 {
2648         struct addrinfo hints, *ai, *aitop;
2649         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2650         int gaierr;
2651         int sock = -1;
2652
2653         memset(&hints, 0, sizeof(hints));
2654         hints.ai_family = IPv4or6;
2655         hints.ai_socktype = SOCK_STREAM;
2656         snprintf(strport, sizeof strport, "%d", port);
2657         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2658                 error("connect_to %.100s: unknown host (%s)", host,
2659                     gai_strerror(gaierr));
2660                 return -1;
2661         }
2662         for (ai = aitop; ai; ai = ai->ai_next) {
2663                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2664                         continue;
2665                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2666                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2667                         error("connect_to: getnameinfo failed");
2668                         continue;
2669                 }
2670                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2671                 if (sock < 0) {
2672                         if (ai->ai_next == NULL)
2673                                 error("socket: %.100s", strerror(errno));
2674                         else
2675                                 verbose("socket: %.100s", strerror(errno));
2676                         continue;
2677                 }
2678                 if (set_nonblock(sock) == -1)
2679                         fatal("%s: set_nonblock(%d)", __func__, sock);
2680                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2681                     errno != EINPROGRESS) {
2682                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2683                             strerror(errno));
2684                         close(sock);
2685                         continue;       /* fail -- try next */
2686                 }
2687                 break; /* success */
2688
2689         }
2690         freeaddrinfo(aitop);
2691         if (!ai) {
2692                 error("connect_to %.100s port %d: failed.", host, port);
2693                 return -1;
2694         }
2695         /* success */
2696         set_nodelay(sock);
2697         return sock;
2698 }
2699
2700 int
2701 channel_connect_by_listen_address(u_short listen_port)
2702 {
2703         int i;
2704
2705         for (i = 0; i < num_permitted_opens; i++)
2706                 if (permitted_opens[i].host_to_connect != NULL &&
2707                     permitted_opens[i].listen_port == listen_port)
2708                         return connect_to(
2709                             permitted_opens[i].host_to_connect,
2710                             permitted_opens[i].port_to_connect);
2711         error("WARNING: Server requests forwarding for unknown listen_port %d",
2712             listen_port);
2713         return -1;
2714 }
2715
2716 /* Check if connecting to that port is permitted and connect. */
2717 int
2718 channel_connect_to(const char *host, u_short port)
2719 {
2720         int i, permit;
2721
2722         permit = all_opens_permitted;
2723         if (!permit) {
2724                 for (i = 0; i < num_permitted_opens; i++)
2725                         if (permitted_opens[i].host_to_connect != NULL &&
2726                             permitted_opens[i].port_to_connect == port &&
2727                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2728                                 permit = 1;
2729
2730         }
2731         if (!permit) {
2732                 logit("Received request to connect to host %.100s port %d, "
2733                     "but the request was denied.", host, port);
2734                 return -1;
2735         }
2736         return connect_to(host, port);
2737 }
2738
2739 void
2740 channel_send_window_changes(void)
2741 {
2742         u_int i;
2743         struct winsize ws;
2744
2745         for (i = 0; i < channels_alloc; i++) {
2746                 if (channels[i] == NULL || !channels[i]->client_tty ||
2747                     channels[i]->type != SSH_CHANNEL_OPEN)
2748                         continue;
2749                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2750                         continue;
2751                 channel_request_start(i, "window-change", 0);
2752                 packet_put_int(ws.ws_col);
2753                 packet_put_int(ws.ws_row);
2754                 packet_put_int(ws.ws_xpixel);
2755                 packet_put_int(ws.ws_ypixel);
2756                 packet_send();
2757         }
2758 }
2759
2760 /* -- X11 forwarding */
2761
2762 /*
2763  * Creates an internet domain socket for listening for X11 connections.
2764  * Returns 0 and a suitable display number for the DISPLAY variable
2765  * stored in display_numberp , or -1 if an error occurs.
2766  */
2767 int
2768 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2769     int single_connection, u_int *display_numberp, int **chanids)
2770 {
2771         Channel *nc = NULL;
2772         int display_number, sock;
2773         u_short port;
2774         struct addrinfo hints, *ai, *aitop;
2775         char strport[NI_MAXSERV];
2776         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2777
2778         if (chanids == NULL)
2779                 return -1;
2780
2781         for (display_number = x11_display_offset;
2782             display_number < MAX_DISPLAYS;
2783             display_number++) {
2784                 port = 6000 + display_number;
2785                 memset(&hints, 0, sizeof(hints));
2786                 hints.ai_family = IPv4or6;
2787                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2788                 hints.ai_socktype = SOCK_STREAM;
2789                 snprintf(strport, sizeof strport, "%d", port);
2790                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2791                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2792                         return -1;
2793                 }
2794                 for (ai = aitop; ai; ai = ai->ai_next) {
2795                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2796                                 continue;
2797                         sock = socket(ai->ai_family, ai->ai_socktype,
2798                             ai->ai_protocol);
2799                         if (sock < 0) {
2800                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2801                                         error("socket: %.100s", strerror(errno));
2802                                         freeaddrinfo(aitop);
2803                                         return -1;
2804                                 } else {
2805                                         debug("x11_create_display_inet: Socket family %d not supported",
2806                                                  ai->ai_family);
2807                                         continue;
2808                                 }
2809                         }
2810 #ifdef IPV6_V6ONLY
2811                         if (ai->ai_family == AF_INET6) {
2812                                 int on = 1;
2813                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2814                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2815                         }
2816 #endif
2817                         channel_set_reuseaddr(sock);
2818                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2819                                 debug2("bind port %d: %.100s", port, strerror(errno));
2820                                 close(sock);
2821
2822                                 if (ai->ai_next)
2823                                         continue;
2824
2825                                 for (n = 0; n < num_socks; n++) {
2826                                         close(socks[n]);
2827                                 }
2828                                 num_socks = 0;
2829                                 break;
2830                         }
2831                         socks[num_socks++] = sock;
2832 #ifndef DONT_TRY_OTHER_AF
2833                         if (num_socks == NUM_SOCKS)
2834                                 break;
2835 #else
2836                         if (x11_use_localhost) {
2837                                 if (num_socks == NUM_SOCKS)
2838                                         break;
2839                         } else {
2840                                 break;
2841                         }
2842 #endif
2843                 }
2844                 freeaddrinfo(aitop);
2845                 if (num_socks > 0)
2846                         break;
2847         }
2848         if (display_number >= MAX_DISPLAYS) {
2849                 error("Failed to allocate internet-domain X11 display socket.");
2850                 return -1;
2851         }
2852         /* Start listening for connections on the socket. */
2853         for (n = 0; n < num_socks; n++) {
2854                 sock = socks[n];
2855                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2856                         error("listen: %.100s", strerror(errno));
2857                         close(sock);
2858                         return -1;
2859                 }
2860         }
2861
2862         /* Allocate a channel for each socket. */
2863         *chanids = xmalloc(sizeof(**chanids) * (num_socks + 1));
2864         for (n = 0; n < num_socks; n++) {
2865                 sock = socks[n];
2866                 nc = channel_new("x11 listener",
2867                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2868                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2869                     0, "X11 inet listener", 1);
2870                 nc->single_connection = single_connection;
2871                 (*chanids)[n] = nc->self;
2872         }
2873         (*chanids)[n] = -1;
2874
2875         /* Return the display number for the DISPLAY environment variable. */
2876         *display_numberp = display_number;
2877         return (0);
2878 }
2879
2880 static int
2881 connect_local_xsocket(u_int dnr)
2882 {
2883         int sock;
2884         struct sockaddr_un addr;
2885
2886         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2887         if (sock < 0)
2888                 error("socket: %.100s", strerror(errno));
2889         memset(&addr, 0, sizeof(addr));
2890         addr.sun_family = AF_UNIX;
2891         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2892         if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2893                 return sock;
2894         close(sock);
2895         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2896         return -1;
2897 }
2898
2899 int
2900 x11_connect_display(void)
2901 {
2902         int display_number, sock = 0;
2903         const char *display;
2904         char buf[1024], *cp;
2905         struct addrinfo hints, *ai, *aitop;
2906         char strport[NI_MAXSERV];
2907         int gaierr;
2908
2909         /* Try to open a socket for the local X server. */
2910         display = getenv("DISPLAY");
2911         if (!display) {
2912                 error("DISPLAY not set.");
2913                 return -1;
2914         }
2915         /*
2916          * Now we decode the value of the DISPLAY variable and make a
2917          * connection to the real X server.
2918          */
2919
2920         /*
2921          * Check if it is a unix domain socket.  Unix domain displays are in
2922          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2923          */
2924         if (strncmp(display, "unix:", 5) == 0 ||
2925             display[0] == ':') {
2926                 /* Connect to the unix domain socket. */
2927                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2928                         error("Could not parse display number from DISPLAY: %.100s",
2929                             display);
2930                         return -1;
2931                 }
2932                 /* Create a socket. */
2933                 sock = connect_local_xsocket(display_number);
2934                 if (sock < 0)
2935                         return -1;
2936
2937                 /* OK, we now have a connection to the display. */
2938                 return sock;
2939         }
2940         /*
2941          * Connect to an inet socket.  The DISPLAY value is supposedly
2942          * hostname:d[.s], where hostname may also be numeric IP address.
2943          */
2944         strlcpy(buf, display, sizeof(buf));
2945         cp = strchr(buf, ':');
2946         if (!cp) {
2947                 error("Could not find ':' in DISPLAY: %.100s", display);
2948                 return -1;
2949         }
2950         *cp = 0;
2951         /* buf now contains the host name.  But first we parse the display number. */
2952         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2953                 error("Could not parse display number from DISPLAY: %.100s",
2954                     display);
2955                 return -1;
2956         }
2957
2958         /* Look up the host address */
2959         memset(&hints, 0, sizeof(hints));
2960         hints.ai_family = IPv4or6;
2961         hints.ai_socktype = SOCK_STREAM;
2962         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2963         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2964                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2965                 return -1;
2966         }
2967         for (ai = aitop; ai; ai = ai->ai_next) {
2968                 /* Create a socket. */
2969                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2970                 if (sock < 0) {
2971                         debug2("socket: %.100s", strerror(errno));
2972                         continue;
2973                 }
2974                 /* Connect it to the display. */
2975                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2976                         debug2("connect %.100s port %d: %.100s", buf,
2977                             6000 + display_number, strerror(errno));
2978                         close(sock);
2979                         continue;
2980                 }
2981                 /* Success */
2982                 break;
2983         }
2984         freeaddrinfo(aitop);
2985         if (!ai) {
2986                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2987                     strerror(errno));
2988                 return -1;
2989         }
2990         set_nodelay(sock);
2991         return sock;
2992 }
2993
2994 /*
2995  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2996  * the remote channel number.  We should do whatever we want, and respond
2997  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2998  */
2999
3000 void
3001 x11_input_open(int type, u_int32_t seq, void *ctxt)
3002 {
3003         Channel *c = NULL;
3004         int remote_id, sock = 0;
3005         char *remote_host;
3006
3007         debug("Received X11 open request.");
3008
3009         remote_id = packet_get_int();
3010
3011         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3012                 remote_host = packet_get_string(NULL);
3013         } else {
3014                 remote_host = xstrdup("unknown (remote did not supply name)");
3015         }
3016         packet_check_eom();
3017
3018         /* Obtain a connection to the real X display. */
3019         sock = x11_connect_display();
3020         if (sock != -1) {
3021                 /* Allocate a channel for this connection. */
3022                 c = channel_new("connected x11 socket",
3023                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3024                     remote_host, 1);
3025                 c->remote_id = remote_id;
3026                 c->force_drain = 1;
3027         }
3028         xfree(remote_host);
3029         if (c == NULL) {
3030                 /* Send refusal to the remote host. */
3031                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3032                 packet_put_int(remote_id);
3033         } else {
3034                 /* Send a confirmation to the remote host. */
3035                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3036                 packet_put_int(remote_id);
3037                 packet_put_int(c->self);
3038         }
3039         packet_send();
3040 }
3041
3042 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3043 void
3044 deny_input_open(int type, u_int32_t seq, void *ctxt)
3045 {
3046         int rchan = packet_get_int();
3047
3048         switch (type) {
3049         case SSH_SMSG_AGENT_OPEN:
3050                 error("Warning: ssh server tried agent forwarding.");
3051                 break;
3052         case SSH_SMSG_X11_OPEN:
3053                 error("Warning: ssh server tried X11 forwarding.");
3054                 break;
3055         default:
3056                 error("deny_input_open: type %d", type);
3057                 break;
3058         }
3059         error("Warning: this is probably a break-in attempt by a malicious server.");
3060         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3061         packet_put_int(rchan);
3062         packet_send();
3063 }
3064
3065 /*
3066  * Requests forwarding of X11 connections, generates fake authentication
3067  * data, and enables authentication spoofing.
3068  * This should be called in the client only.
3069  */
3070 void
3071 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3072     const char *proto, const char *data)
3073 {
3074         u_int data_len = (u_int) strlen(data) / 2;
3075         u_int i, value;
3076         char *new_data;
3077         int screen_number;
3078         const char *cp;
3079         u_int32_t rnd = 0;
3080
3081         if (x11_saved_display == NULL)
3082                 x11_saved_display = xstrdup(disp);
3083         else if (strcmp(disp, x11_saved_display) != 0) {
3084                 error("x11_request_forwarding_with_spoofing: different "
3085                     "$DISPLAY already forwarded");
3086                 return;
3087         }
3088
3089         cp = disp;
3090         if (disp)
3091                 cp = strchr(disp, ':');
3092         if (cp)
3093                 cp = strchr(cp, '.');
3094         if (cp)
3095                 screen_number = atoi(cp + 1);
3096         else
3097                 screen_number = 0;
3098
3099         if (x11_saved_proto == NULL) {
3100                 /* Save protocol name. */
3101                 x11_saved_proto = xstrdup(proto);
3102                 /*
3103                  * Extract real authentication data and generate fake data
3104                  * of the same length.
3105                  */
3106                 x11_saved_data = xmalloc(data_len);
3107                 x11_fake_data = xmalloc(data_len);
3108                 for (i = 0; i < data_len; i++) {
3109                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3110                                 fatal("x11_request_forwarding: bad "
3111                                     "authentication data: %.100s", data);
3112                         if (i % 4 == 0)
3113                                 rnd = arc4random();
3114                         x11_saved_data[i] = value;
3115                         x11_fake_data[i] = rnd & 0xff;
3116                         rnd >>= 8;
3117                 }
3118                 x11_saved_data_len = data_len;
3119                 x11_fake_data_len = data_len;
3120         }
3121
3122         /* Convert the fake data into hex. */
3123         new_data = tohex(x11_fake_data, data_len);
3124
3125         /* Send the request packet. */
3126         if (compat20) {
3127                 channel_request_start(client_session_id, "x11-req", 0);
3128                 packet_put_char(0);     /* XXX bool single connection */
3129         } else {
3130                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3131         }
3132         packet_put_cstring(proto);
3133         packet_put_cstring(new_data);
3134         packet_put_int(screen_number);
3135         packet_send();
3136         packet_write_wait();
3137         xfree(new_data);
3138 }
3139
3140
3141 /* -- agent forwarding */
3142
3143 /* Sends a message to the server to request authentication fd forwarding. */
3144
3145 void
3146 auth_request_forwarding(void)
3147 {
3148         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3149         packet_send();
3150         packet_write_wait();
3151 }