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