channels.c

   1 /* $OpenBSD: channels.c,v 1.250 2006/04/16 00:48:52 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/ioctl.h>
  45 #include <sys/types.h>
  46 #include <sys/un.h>
  47
  48 #include <termios.h>
  49
  50 #include "ssh.h"
  51 #include "ssh1.h"
  52 #include "ssh2.h"
  53 #include "packet.h"
  54 #include "xmalloc.h"
  55 #include "log.h"
  56 #include "misc.h"
  57 #include "channels.h"
  58 #include "compat.h"
  59 #include "canohost.h"
  60 #include "key.h"
  61 #include "authfd.h"
  62 #include "pathnames.h"
  63 #include "bufaux.h"
  64
  65 /* -- channel core */
  66
  67 /*
  68  * Pointer to an array containing all allocated channels.  The array is
  69  * dynamically extended as needed.
  70  */
  71 static Channel **channels = NULL;
  72
  73 /*
  74  * Size of the channel array.  All slots of the array must always be
  75  * initialized (at least the type field); unused slots set to NULL
  76  */
  77 static u_int channels_alloc = 0;
  78
  79 /*
  80  * Maximum file descriptor value used in any of the channels.  This is
  81  * updated in channel_new.
  82  */
  83 static int channel_max_fd = 0;
  84
  85
  86 /* -- tcp forwarding */
  87
  88 /*
  89  * Data structure for storing which hosts are permitted for forward requests.
  90  * The local sides of any remote forwards are stored in this array to prevent
  91  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  92  * network (which might be behind a firewall).
  93  */
  94 typedef struct {
  95         char *host_to_connect;          /* Connect to 'host'. */
  96         u_short port_to_connect;        /* Connect to 'port'. */
  97         u_short listen_port;            /* Remote side should listen port number. */
  98 } ForwardPermission;
  99
 100 /* List of all permitted host/port pairs to connect. */
 101 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 102
 103 /* Number of permitted host/port pairs in the array. */
 104 static int num_permitted_opens = 0;
 105 /*
 106  * If this is true, all opens are permitted.  This is the case on the server
 107  * on which we have to trust the client anyway, and the user could do
 108  * anything after logging in anyway.
 109  */
 110 static int all_opens_permitted = 0;
 111
 112
 113 /* -- X11 forwarding */
 114
 115 /* Maximum number of fake X11 displays to try. */
 116 #define MAX_DISPLAYS  1000
 117
 118 /* Saved X11 local (client) display. */
 119 static char *x11_saved_display = NULL;
 120
 121 /* Saved X11 authentication protocol name. */
 122 static char *x11_saved_proto = NULL;
 123
 124 /* Saved X11 authentication data.  This is the real data. */
 125 static char *x11_saved_data = NULL;
 126 static u_int x11_saved_data_len = 0;
 127
 128 /*
 129  * Fake X11 authentication data.  This is what the server will be sending us;
 130  * we should replace any occurrences of this by the real data.
 131  */
 132 static u_char *x11_fake_data = NULL;
 133 static u_int x11_fake_data_len;
 134
 135
 136 /* -- agent forwarding */
 137
 138 #define NUM_SOCKS       10
 139
 140 /* AF_UNSPEC or AF_INET or AF_INET6 */
 141 static int IPv4or6 = AF_UNSPEC;
 142
 143 /* helper */
 144 static void port_open_helper(Channel *c, char *rtype);
 145
 146 /* -- channel core */
 147
 148 Channel *
 149 channel_by_id(int id)
 150 {
 151         Channel *c;
 152
 153         if (id < 0 || (u_int)id >= channels_alloc) {
 154                 logit("channel_by_id: %d: bad id", id);
 155                 return NULL;
 156         }
 157         c = channels[id];
 158         if (c == NULL) {
 159                 logit("channel_by_id: %d: bad id: channel free", id);
 160                 return NULL;
 161         }
 162         return c;
 163 }
 164
 165 /*
 166  * Returns the channel if it is allowed to receive protocol messages.
 167  * Private channels, like listening sockets, may not receive messages.
 168  */
 169 Channel *
 170 channel_lookup(int id)
 171 {
 172         Channel *c;
 173
 174         if ((c = channel_by_id(id)) == NULL)
 175                 return (NULL);
 176
 177         switch (c->type) {
 178         case SSH_CHANNEL_X11_OPEN:
 179         case SSH_CHANNEL_LARVAL:
 180         case SSH_CHANNEL_CONNECTING:
 181         case SSH_CHANNEL_DYNAMIC:
 182         case SSH_CHANNEL_OPENING:
 183         case SSH_CHANNEL_OPEN:
 184         case SSH_CHANNEL_INPUT_DRAINING:
 185         case SSH_CHANNEL_OUTPUT_DRAINING:
 186                 return (c);
 187         }
 188         logit("Non-public channel %d, type %d.", id, c->type);
 189         return (NULL);
 190 }
 191
 192 /*
 193  * Register filedescriptors for a channel, used when allocating a channel or
 194  * when the channel consumer/producer is ready, e.g. shell exec'd
 195  */
 196 static void
 197 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 198     int extusage, int nonblock)
 199 {
 200         /* Update the maximum file descriptor value. */
 201         channel_max_fd = MAX(channel_max_fd, rfd);
 202         channel_max_fd = MAX(channel_max_fd, wfd);
 203         channel_max_fd = MAX(channel_max_fd, efd);
 204
 205         /* XXX set close-on-exec -markus */
 206
 207         c->rfd = rfd;
 208         c->wfd = wfd;
 209         c->sock = (rfd == wfd) ? rfd : -1;
 210         c->ctl_fd = -1; /* XXX: set elsewhere */
 211         c->efd = efd;
 212         c->extended_usage = extusage;
 213
 214         /* XXX ugly hack: nonblock is only set by the server */
 215         if (nonblock && isatty(c->rfd)) {
 216                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 217                 c->isatty = 1;
 218                 if (!isatty(c->wfd)) {
 219                         error("channel %d: wfd %d is not a tty?",
 220                             c->self, c->wfd);
 221                 }
 222         } else {
 223                 c->isatty = 0;
 224         }
 225         c->wfd_isatty = isatty(c->wfd);
 226
 227         /* enable nonblocking mode */
 228         if (nonblock) {
 229                 if (rfd != -1)
 230                         set_nonblock(rfd);
 231                 if (wfd != -1)
 232                         set_nonblock(wfd);
 233                 if (efd != -1)
 234                         set_nonblock(efd);
 235         }
 236 }
 237
 238 /*
 239  * Allocate a new channel object and set its type and socket. This will cause
 240  * remote_name to be freed.
 241  */
 242 Channel *
 243 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 244     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 245 {
 246         int found;
 247         u_int i;
 248         Channel *c;
 249
 250         /* Do initial allocation if this is the first call. */
 251         if (channels_alloc == 0) {
 252                 channels_alloc = 10;
 253                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 254                 for (i = 0; i < channels_alloc; i++)
 255                         channels[i] = NULL;
 256         }
 257         /* Try to find a free slot where to put the new channel. */
 258         for (found = -1, i = 0; i < channels_alloc; i++)
 259                 if (channels[i] == NULL) {
 260                         /* Found a free slot. */
 261                         found = (int)i;
 262                         break;
 263                 }
 264         if (found < 0) {
 265                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 266                 found = channels_alloc;
 267                 if (channels_alloc > 10000)
 268                         fatal("channel_new: internal error: channels_alloc %d "
 269                             "too big.", channels_alloc);
 270                 channels = xrealloc(channels, channels_alloc + 10,
 271                     sizeof(Channel *));
 272                 channels_alloc += 10;
 273                 debug2("channel: expanding %d", channels_alloc);
 274                 for (i = found; i < channels_alloc; i++)
 275                         channels[i] = NULL;
 276         }
 277         /* Initialize and return new channel. */
 278         c = channels[found] = xcalloc(1, sizeof(Channel));
 279         buffer_init(&c->input);
 280         buffer_init(&c->output);
 281         buffer_init(&c->extended);
 282         c->ostate = CHAN_OUTPUT_OPEN;
 283         c->istate = CHAN_INPUT_OPEN;
 284         c->flags = 0;
 285         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 286         c->self = found;
 287         c->type = type;
 288         c->ctype = ctype;
 289         c->local_window = window;
 290         c->local_window_max = window;
 291         c->local_consumed = 0;
 292         c->local_maxpacket = maxpack;
 293         c->remote_id = -1;
 294         c->remote_name = xstrdup(remote_name);
 295         c->remote_window = 0;
 296         c->remote_maxpacket = 0;
 297         c->force_drain = 0;
 298         c->single_connection = 0;
 299         c->detach_user = NULL;
 300         c->detach_close = 0;
 301         c->confirm = NULL;
 302         c->confirm_ctx = NULL;
 303         c->input_filter = NULL;
 304         c->output_filter = NULL;
 305         debug("channel %d: new [%s]", found, remote_name);
 306         return c;
 307 }
 308
 309 static int
 310 channel_find_maxfd(void)
 311 {
 312         u_int i;
 313         int max = 0;
 314         Channel *c;
 315
 316         for (i = 0; i < channels_alloc; i++) {
 317                 c = channels[i];
 318                 if (c != NULL) {
 319                         max = MAX(max, c->rfd);
 320                         max = MAX(max, c->wfd);
 321                         max = MAX(max, c->efd);
 322                 }
 323         }
 324         return max;
 325 }
 326
 327 int
 328 channel_close_fd(int *fdp)
 329 {
 330         int ret = 0, fd = *fdp;
 331
 332         if (fd != -1) {
 333                 ret = close(fd);
 334                 *fdp = -1;
 335                 if (fd == channel_max_fd)
 336                         channel_max_fd = channel_find_maxfd();
 337         }
 338         return ret;
 339 }
 340
 341 /* Close all channel fd/socket. */
 342 static void
 343 channel_close_fds(Channel *c)
 344 {
 345         debug3("channel %d: close_fds r %d w %d e %d c %d",
 346             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 347
 348         channel_close_fd(&c->sock);
 349         channel_close_fd(&c->ctl_fd);
 350         channel_close_fd(&c->rfd);
 351         channel_close_fd(&c->wfd);
 352         channel_close_fd(&c->efd);
 353 }
 354
 355 /* Free the channel and close its fd/socket. */
 356 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 void
 403 channel_close_all(void)
 404 {
 405         u_int i;
 406
 407         for (i = 0; i < channels_alloc; i++)
 408                 if (channels[i] != NULL)
 409                         channel_close_fds(channels[i]);
 410 }
 411
 412 /*
 413  * Stop listening to channels.
 414  */
 415 void
 416 channel_stop_listening(void)
 417 {
 418         u_int i;
 419         Channel *c;
 420
 421         for (i = 0; i < channels_alloc; i++) {
 422                 c = channels[i];
 423                 if (c != NULL) {
 424                         switch (c->type) {
 425                         case SSH_CHANNEL_AUTH_SOCKET:
 426                         case SSH_CHANNEL_PORT_LISTENER:
 427                         case SSH_CHANNEL_RPORT_LISTENER:
 428                         case SSH_CHANNEL_X11_LISTENER:
 429                                 channel_close_fd(&c->sock);
 430                                 channel_free(c);
 431                                 break;
 432                         }
 433                 }
 434         }
 435 }
 436
 437 /*
 438  * Returns true if no channel has too much buffered data, and false if one or
 439  * more channel is overfull.
 440  */
 441 int
 442 channel_not_very_much_buffered_data(void)
 443 {
 444         u_int i;
 445         Channel *c;
 446
 447         for (i = 0; i < channels_alloc; i++) {
 448                 c = channels[i];
 449                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 450 #if 0
 451                         if (!compat20 &&
 452                             buffer_len(&c->input) > packet_get_maxsize()) {
 453                                 debug2("channel %d: big input buffer %d",
 454                                     c->self, buffer_len(&c->input));
 455                                 return 0;
 456                         }
 457 #endif
 458                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 459                                 debug2("channel %d: big output buffer %u > %u",
 460                                     c->self, buffer_len(&c->output),
 461                                     packet_get_maxsize());
 462                                 return 0;
 463                         }
 464                 }
 465         }
 466         return 1;
 467 }
 468
 469 /* Returns true if any channel is still open. */
 470 int
 471 channel_still_open(void)
 472 {
 473         u_int i;
 474         Channel *c;
 475
 476         for (i = 0; i < channels_alloc; i++) {
 477                 c = channels[i];
 478                 if (c == NULL)
 479                         continue;
 480                 switch (c->type) {
 481                 case SSH_CHANNEL_X11_LISTENER:
 482                 case SSH_CHANNEL_PORT_LISTENER:
 483                 case SSH_CHANNEL_RPORT_LISTENER:
 484                 case SSH_CHANNEL_CLOSED:
 485                 case SSH_CHANNEL_AUTH_SOCKET:
 486                 case SSH_CHANNEL_DYNAMIC:
 487                 case SSH_CHANNEL_CONNECTING:
 488                 case SSH_CHANNEL_ZOMBIE:
 489                         continue;
 490                 case SSH_CHANNEL_LARVAL:
 491                         if (!compat20)
 492                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 493                         continue;
 494                 case SSH_CHANNEL_OPENING:
 495                 case SSH_CHANNEL_OPEN:
 496                 case SSH_CHANNEL_X11_OPEN:
 497                         return 1;
 498                 case SSH_CHANNEL_INPUT_DRAINING:
 499                 case SSH_CHANNEL_OUTPUT_DRAINING:
 500                         if (!compat13)
 501                                 fatal("cannot happen: OUT_DRAIN");
 502                         return 1;
 503                 default:
 504                         fatal("channel_still_open: bad channel type %d", c->type);
 505                         /* NOTREACHED */
 506                 }
 507         }
 508         return 0;
 509 }
 510
 511 /* Returns the id of an open channel suitable for keepaliving */
 512 int
 513 channel_find_open(void)
 514 {
 515         u_int i;
 516         Channel *c;
 517
 518         for (i = 0; i < channels_alloc; i++) {
 519                 c = channels[i];
 520                 if (c == NULL || c->remote_id < 0)
 521                         continue;
 522                 switch (c->type) {
 523                 case SSH_CHANNEL_CLOSED:
 524                 case SSH_CHANNEL_DYNAMIC:
 525                 case SSH_CHANNEL_X11_LISTENER:
 526                 case SSH_CHANNEL_PORT_LISTENER:
 527                 case SSH_CHANNEL_RPORT_LISTENER:
 528                 case SSH_CHANNEL_OPENING:
 529                 case SSH_CHANNEL_CONNECTING:
 530                 case SSH_CHANNEL_ZOMBIE:
 531                         continue;
 532                 case SSH_CHANNEL_LARVAL:
 533                 case SSH_CHANNEL_AUTH_SOCKET:
 534                 case SSH_CHANNEL_OPEN:
 535                 case SSH_CHANNEL_X11_OPEN:
 536                         return i;
 537                 case SSH_CHANNEL_INPUT_DRAINING:
 538                 case SSH_CHANNEL_OUTPUT_DRAINING:
 539                         if (!compat13)
 540                                 fatal("cannot happen: OUT_DRAIN");
 541                         return i;
 542                 default:
 543                         fatal("channel_find_open: bad channel type %d", c->type);
 544                         /* NOTREACHED */
 545                 }
 546         }
 547         return -1;
 548 }
 549
 550
 551 /*
 552  * Returns a message describing the currently open forwarded connections,
 553  * suitable for sending to the client.  The message contains crlf pairs for
 554  * newlines.
 555  */
 556 char *
 557 channel_open_message(void)
 558 {
 559         Buffer buffer;
 560         Channel *c;
 561         char buf[1024], *cp;
 562         u_int i;
 563
 564         buffer_init(&buffer);
 565         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 566         buffer_append(&buffer, buf, strlen(buf));
 567         for (i = 0; i < channels_alloc; i++) {
 568                 c = channels[i];
 569                 if (c == NULL)
 570                         continue;
 571                 switch (c->type) {
 572                 case SSH_CHANNEL_X11_LISTENER:
 573                 case SSH_CHANNEL_PORT_LISTENER:
 574                 case SSH_CHANNEL_RPORT_LISTENER:
 575                 case SSH_CHANNEL_CLOSED:
 576                 case SSH_CHANNEL_AUTH_SOCKET:
 577                 case SSH_CHANNEL_ZOMBIE:
 578                         continue;
 579                 case SSH_CHANNEL_LARVAL:
 580                 case SSH_CHANNEL_OPENING:
 581                 case SSH_CHANNEL_CONNECTING:
 582                 case SSH_CHANNEL_DYNAMIC:
 583                 case SSH_CHANNEL_OPEN:
 584                 case SSH_CHANNEL_X11_OPEN:
 585                 case SSH_CHANNEL_INPUT_DRAINING:
 586                 case SSH_CHANNEL_OUTPUT_DRAINING:
 587                         snprintf(buf, sizeof buf,
 588                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 589                             c->self, c->remote_name,
 590                             c->type, c->remote_id,
 591                             c->istate, buffer_len(&c->input),
 592                             c->ostate, buffer_len(&c->output),
 593                             c->rfd, c->wfd, c->ctl_fd);
 594                         buffer_append(&buffer, buf, strlen(buf));
 595                         continue;
 596                 default:
 597                         fatal("channel_open_message: bad channel type %d", c->type);
 598                         /* NOTREACHED */
 599                 }
 600         }
 601         buffer_append(&buffer, "\0", 1);
 602         cp = xstrdup(buffer_ptr(&buffer));
 603         buffer_free(&buffer);
 604         return cp;
 605 }
 606
 607 void
 608 channel_send_open(int id)
 609 {
 610         Channel *c = channel_lookup(id);
 611
 612         if (c == NULL) {
 613                 logit("channel_send_open: %d: bad id", id);
 614                 return;
 615         }
 616         debug2("channel %d: send open", id);
 617         packet_start(SSH2_MSG_CHANNEL_OPEN);
 618         packet_put_cstring(c->ctype);
 619         packet_put_int(c->self);
 620         packet_put_int(c->local_window);
 621         packet_put_int(c->local_maxpacket);
 622         packet_send();
 623 }
 624
 625 void
 626 channel_request_start(int id, char *service, int wantconfirm)
 627 {
 628         Channel *c = channel_lookup(id);
 629
 630         if (c == NULL) {
 631                 logit("channel_request_start: %d: unknown channel id", id);
 632                 return;
 633         }
 634         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 635         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 636         packet_put_int(c->remote_id);
 637         packet_put_cstring(service);
 638         packet_put_char(wantconfirm);
 639 }
 640
 641 void
 642 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 643 {
 644         Channel *c = channel_lookup(id);
 645
 646         if (c == NULL) {
 647                 logit("channel_register_comfirm: %d: bad id", id);
 648                 return;
 649         }
 650         c->confirm = fn;
 651         c->confirm_ctx = ctx;
 652 }
 653
 654 void
 655 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 656 {
 657         Channel *c = channel_by_id(id);
 658
 659         if (c == NULL) {
 660                 logit("channel_register_cleanup: %d: bad id", id);
 661                 return;
 662         }
 663         c->detach_user = fn;
 664         c->detach_close = do_close;
 665 }
 666
 667 void
 668 channel_cancel_cleanup(int id)
 669 {
 670         Channel *c = channel_by_id(id);
 671
 672         if (c == NULL) {
 673                 logit("channel_cancel_cleanup: %d: bad id", id);
 674                 return;
 675         }
 676         c->detach_user = NULL;
 677         c->detach_close = 0;
 678 }
 679
 680 void
 681 channel_register_filter(int id, channel_infilter_fn *ifn,
 682     channel_outfilter_fn *ofn)
 683 {
 684         Channel *c = channel_lookup(id);
 685
 686         if (c == NULL) {
 687                 logit("channel_register_filter: %d: bad id", id);
 688                 return;
 689         }
 690         c->input_filter = ifn;
 691         c->output_filter = ofn;
 692 }
 693
 694 void
 695 channel_set_fds(int id, int rfd, int wfd, int efd,
 696     int extusage, int nonblock, u_int window_max)
 697 {
 698         Channel *c = channel_lookup(id);
 699
 700         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 701                 fatal("channel_activate for non-larval channel %d.", id);
 702         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 703         c->type = SSH_CHANNEL_OPEN;
 704         c->local_window = c->local_window_max = window_max;
 705         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 706         packet_put_int(c->remote_id);
 707         packet_put_int(c->local_window);
 708         packet_send();
 709 }
 710
 711 /*
 712  * 'channel_pre*' are called just before select() to add any bits relevant to
 713  * channels in the select bitmasks.
 714  */
 715 /*
 716  * 'channel_post*': perform any appropriate operations for channels which
 717  * have events pending.
 718  */
 719 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 720 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 721 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 722
 723 static void
 724 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 725 {
 726         FD_SET(c->sock, readset);
 727 }
 728
 729 static void
 730 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 731 {
 732         debug3("channel %d: waiting for connection", c->self);
 733         FD_SET(c->sock, writeset);
 734 }
 735
 736 static void
 737 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 738 {
 739         if (buffer_len(&c->input) < packet_get_maxsize())
 740                 FD_SET(c->sock, readset);
 741         if (buffer_len(&c->output) > 0)
 742                 FD_SET(c->sock, writeset);
 743 }
 744
 745 static void
 746 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 747 {
 748         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 749
 750         if (c->istate == CHAN_INPUT_OPEN &&
 751             limit > 0 &&
 752             buffer_len(&c->input) < limit &&
 753             buffer_check_alloc(&c->input, CHAN_RBUF))
 754                 FD_SET(c->rfd, readset);
 755         if (c->ostate == CHAN_OUTPUT_OPEN ||
 756             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 757                 if (buffer_len(&c->output) > 0) {
 758                         FD_SET(c->wfd, writeset);
 759                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 760                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 761                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 762                                     c->self, c->efd, buffer_len(&c->extended));
 763                         else
 764                                 chan_obuf_empty(c);
 765                 }
 766         }
 767         /** XXX check close conditions, too */
 768         if (compat20 && c->efd != -1) {
 769                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 770                     buffer_len(&c->extended) > 0)
 771                         FD_SET(c->efd, writeset);
 772                 else if (!(c->flags & CHAN_EOF_SENT) &&
 773                     c->extended_usage == CHAN_EXTENDED_READ &&
 774                     buffer_len(&c->extended) < c->remote_window)
 775                         FD_SET(c->efd, readset);
 776         }
 777         /* XXX: What about efd? races? */
 778         if (compat20 && c->ctl_fd != -1 &&
 779             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 780                 FD_SET(c->ctl_fd, readset);
 781 }
 782
 783 static void
 784 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 785 {
 786         if (buffer_len(&c->input) == 0) {
 787                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 788                 packet_put_int(c->remote_id);
 789                 packet_send();
 790                 c->type = SSH_CHANNEL_CLOSED;
 791                 debug2("channel %d: closing after input drain.", c->self);
 792         }
 793 }
 794
 795 static void
 796 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 797 {
 798         if (buffer_len(&c->output) == 0)
 799                 chan_mark_dead(c);
 800         else
 801                 FD_SET(c->sock, writeset);
 802 }
 803
 804 /*
 805  * This is a special state for X11 authentication spoofing.  An opened X11
 806  * connection (when authentication spoofing is being done) remains in this
 807  * state until the first packet has been completely read.  The authentication
 808  * data in that packet is then substituted by the real data if it matches the
 809  * fake data, and the channel is put into normal mode.
 810  * XXX All this happens at the client side.
 811  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 812  */
 813 static int
 814 x11_open_helper(Buffer *b)
 815 {
 816         u_char *ucp;
 817         u_int proto_len, data_len;
 818
 819         /* Check if the fixed size part of the packet is in buffer. */
 820         if (buffer_len(b) < 12)
 821                 return 0;
 822
 823         /* Parse the lengths of variable-length fields. */
 824         ucp = buffer_ptr(b);
 825         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 826                 proto_len = 256 * ucp[6] + ucp[7];
 827                 data_len = 256 * ucp[8] + ucp[9];
 828         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 829                 proto_len = ucp[6] + 256 * ucp[7];
 830                 data_len = ucp[8] + 256 * ucp[9];
 831         } else {
 832                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 833                     ucp[0]);
 834                 return -1;
 835         }
 836
 837         /* Check if the whole packet is in buffer. */
 838         if (buffer_len(b) <
 839             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 840                 return 0;
 841
 842         /* Check if authentication protocol matches. */
 843         if (proto_len != strlen(x11_saved_proto) ||
 844             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 845                 debug2("X11 connection uses different authentication protocol.");
 846                 return -1;
 847         }
 848         /* Check if authentication data matches our fake data. */
 849         if (data_len != x11_fake_data_len ||
 850             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 851                 x11_fake_data, x11_fake_data_len) != 0) {
 852                 debug2("X11 auth data does not match fake data.");
 853                 return -1;
 854         }
 855         /* Check fake data length */
 856         if (x11_fake_data_len != x11_saved_data_len) {
 857                 error("X11 fake_data_len %d != saved_data_len %d",
 858                     x11_fake_data_len, x11_saved_data_len);
 859                 return -1;
 860         }
 861         /*
 862          * Received authentication protocol and data match
 863          * our fake data. Substitute the fake data with real
 864          * data.
 865          */
 866         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 867             x11_saved_data, x11_saved_data_len);
 868         return 1;
 869 }
 870
 871 static void
 872 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 873 {
 874         int ret = x11_open_helper(&c->output);
 875
 876         if (ret == 1) {
 877                 /* Start normal processing for the channel. */
 878                 c->type = SSH_CHANNEL_OPEN;
 879                 channel_pre_open_13(c, readset, writeset);
 880         } else if (ret == -1) {
 881                 /*
 882                  * We have received an X11 connection that has bad
 883                  * authentication information.
 884                  */
 885                 logit("X11 connection rejected because of wrong authentication.");
 886                 buffer_clear(&c->input);
 887                 buffer_clear(&c->output);
 888                 channel_close_fd(&c->sock);
 889                 c->sock = -1;
 890                 c->type = SSH_CHANNEL_CLOSED;
 891                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 892                 packet_put_int(c->remote_id);
 893                 packet_send();
 894         }
 895 }
 896
 897 static void
 898 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 899 {
 900         int ret = x11_open_helper(&c->output);
 901
 902         /* c->force_drain = 1; */
 903
 904         if (ret == 1) {
 905                 c->type = SSH_CHANNEL_OPEN;
 906                 channel_pre_open(c, readset, writeset);
 907         } else if (ret == -1) {
 908                 logit("X11 connection rejected because of wrong authentication.");
 909                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 910                 chan_read_failed(c);
 911                 buffer_clear(&c->input);
 912                 chan_ibuf_empty(c);
 913                 buffer_clear(&c->output);
 914                 /* for proto v1, the peer will send an IEOF */
 915                 if (compat20)
 916                         chan_write_failed(c);
 917                 else
 918                         c->type = SSH_CHANNEL_OPEN;
 919                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 920         }
 921 }
 922
 923 /* try to decode a socks4 header */
 924 static int
 925 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 926 {
 927         char *p, *host;
 928         u_int len, have, i, found;
 929         char username[256];
 930         struct {
 931                 u_int8_t version;
 932                 u_int8_t command;
 933                 u_int16_t dest_port;
 934                 struct in_addr dest_addr;
 935         } s4_req, s4_rsp;
 936
 937         debug2("channel %d: decode socks4", c->self);
 938
 939         have = buffer_len(&c->input);
 940         len = sizeof(s4_req);
 941         if (have < len)
 942                 return 0;
 943         p = buffer_ptr(&c->input);
 944         for (found = 0, i = len; i < have; i++) {
 945                 if (p[i] == '\0') {
 946                         found = 1;
 947                         break;
 948                 }
 949                 if (i > 1024) {
 950                         /* the peer is probably sending garbage */
 951                         debug("channel %d: decode socks4: too long",
 952                             c->self);
 953                         return -1;
 954                 }
 955         }
 956         if (!found)
 957                 return 0;
 958         buffer_get(&c->input, (char *)&s4_req.version, 1);
 959         buffer_get(&c->input, (char *)&s4_req.command, 1);
 960         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 961         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 962         have = buffer_len(&c->input);
 963         p = buffer_ptr(&c->input);
 964         len = strlen(p);
 965         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 966         if (len > have)
 967                 fatal("channel %d: decode socks4: len %d > have %d",
 968                     c->self, len, have);
 969         strlcpy(username, p, sizeof(username));
 970         buffer_consume(&c->input, len);
 971         buffer_consume(&c->input, 1);           /* trailing '\0' */
 972
 973         host = inet_ntoa(s4_req.dest_addr);
 974         strlcpy(c->path, host, sizeof(c->path));
 975         c->host_port = ntohs(s4_req.dest_port);
 976
 977         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 978             c->self, host, c->host_port, s4_req.command);
 979
 980         if (s4_req.command != 1) {
 981                 debug("channel %d: cannot handle: socks4 cn %d",
 982                     c->self, s4_req.command);
 983                 return -1;
 984         }
 985         s4_rsp.version = 0;                     /* vn: 0 for reply */
 986         s4_rsp.command = 90;                    /* cd: req granted */
 987         s4_rsp.dest_port = 0;                   /* ignored */
 988         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 989         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
 990         return 1;
 991 }
 992
 993 /* try to decode a socks5 header */
 994 #define SSH_SOCKS5_AUTHDONE     0x1000
 995 #define SSH_SOCKS5_NOAUTH       0x00
 996 #define SSH_SOCKS5_IPV4         0x01
 997 #define SSH_SOCKS5_DOMAIN       0x03
 998 #define SSH_SOCKS5_IPV6         0x04
 999 #define SSH_SOCKS5_CONNECT      0x01
1000 #define SSH_SOCKS5_SUCCESS      0x00
1001
1002 static int
1003 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1004 {
1005         struct {
1006                 u_int8_t version;
1007                 u_int8_t command;
1008                 u_int8_t reserved;
1009                 u_int8_t atyp;
1010         } s5_req, s5_rsp;
1011         u_int16_t dest_port;
1012         u_char *p, dest_addr[255+1];
1013         u_int have, i, found, nmethods, addrlen, af;
1014
1015         debug2("channel %d: decode socks5", c->self);
1016         p = buffer_ptr(&c->input);
1017         if (p[0] != 0x05)
1018                 return -1;
1019         have = buffer_len(&c->input);
1020         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1021                 /* format: ver | nmethods | methods */
1022                 if (have < 2)
1023                         return 0;
1024                 nmethods = p[1];
1025                 if (have < nmethods + 2)
1026                         return 0;
1027                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1028                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1029                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
1030                                 found = 1;
1031                                 break;
1032                         }
1033                 }
1034                 if (!found) {
1035                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1036                             c->self);
1037                         return -1;
1038                 }
1039                 buffer_consume(&c->input, nmethods + 2);
1040                 buffer_put_char(&c->output, 0x05);              /* version */
1041                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1042                 FD_SET(c->sock, writeset);
1043                 c->flags |= SSH_SOCKS5_AUTHDONE;
1044                 debug2("channel %d: socks5 auth done", c->self);
1045                 return 0;                               /* need more */
1046         }
1047         debug2("channel %d: socks5 post auth", c->self);
1048         if (have < sizeof(s5_req)+1)
1049                 return 0;                       /* need more */
1050         memcpy(&s5_req, p, sizeof(s5_req));
1051         if (s5_req.version != 0x05 ||
1052             s5_req.command != SSH_SOCKS5_CONNECT ||
1053             s5_req.reserved != 0x00) {
1054                 debug2("channel %d: only socks5 connect supported", c->self);
1055                 return -1;
1056         }
1057         switch (s5_req.atyp){
1058         case SSH_SOCKS5_IPV4:
1059                 addrlen = 4;
1060                 af = AF_INET;
1061                 break;
1062         case SSH_SOCKS5_DOMAIN:
1063                 addrlen = p[sizeof(s5_req)];
1064                 af = -1;
1065                 break;
1066         case SSH_SOCKS5_IPV6:
1067                 addrlen = 16;
1068                 af = AF_INET6;
1069                 break;
1070         default:
1071                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1072                 return -1;
1073         }
1074         if (have < 4 + addrlen + 2)
1075                 return 0;
1076         buffer_consume(&c->input, sizeof(s5_req));
1077         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1078                 buffer_consume(&c->input, 1);    /* host string length */
1079         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1080         buffer_get(&c->input, (char *)&dest_port, 2);
1081         dest_addr[addrlen] = '\0';
1082         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1083                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1084         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1085                 return -1;
1086         c->host_port = ntohs(dest_port);
1087
1088         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1089             c->self, c->path, c->host_port, s5_req.command);
1090
1091         s5_rsp.version = 0x05;
1092         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1093         s5_rsp.reserved = 0;                    /* ignored */
1094         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1095         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1096         dest_port = 0;                          /* ignored */
1097
1098         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1099         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1100         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1101         return 1;
1102 }
1103
1104 /* dynamic port forwarding */
1105 static void
1106 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1107 {
1108         u_char *p;
1109         u_int have;
1110         int ret;
1111
1112         have = buffer_len(&c->input);
1113         c->delayed = 0;
1114         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1115         /* buffer_dump(&c->input); */
1116         /* check if the fixed size part of the packet is in buffer. */
1117         if (have < 3) {
1118                 /* need more */
1119                 FD_SET(c->sock, readset);
1120                 return;
1121         }
1122         /* try to guess the protocol */
1123         p = buffer_ptr(&c->input);
1124         switch (p[0]) {
1125         case 0x04:
1126                 ret = channel_decode_socks4(c, readset, writeset);
1127                 break;
1128         case 0x05:
1129                 ret = channel_decode_socks5(c, readset, writeset);
1130                 break;
1131         default:
1132                 ret = -1;
1133                 break;
1134         }
1135         if (ret < 0) {
1136                 chan_mark_dead(c);
1137         } else if (ret == 0) {
1138                 debug2("channel %d: pre_dynamic: need more", c->self);
1139                 /* need more */
1140                 FD_SET(c->sock, readset);
1141         } else {
1142                 /* switch to the next state */
1143                 c->type = SSH_CHANNEL_OPENING;
1144                 port_open_helper(c, "direct-tcpip");
1145         }
1146 }
1147
1148 /* This is our fake X11 server socket. */
1149 static void
1150 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1151 {
1152         Channel *nc;
1153         struct sockaddr addr;
1154         int newsock;
1155         socklen_t addrlen;
1156         char buf[16384], *remote_ipaddr;
1157         int remote_port;
1158
1159         if (FD_ISSET(c->sock, readset)) {
1160                 debug("X11 connection requested.");
1161                 addrlen = sizeof(addr);
1162                 newsock = accept(c->sock, &addr, &addrlen);
1163                 if (c->single_connection) {
1164                         debug2("single_connection: closing X11 listener.");
1165                         channel_close_fd(&c->sock);
1166                         chan_mark_dead(c);
1167                 }
1168                 if (newsock < 0) {
1169                         error("accept: %.100s", strerror(errno));
1170                         return;
1171                 }
1172                 set_nodelay(newsock);
1173                 remote_ipaddr = get_peer_ipaddr(newsock);
1174                 remote_port = get_peer_port(newsock);
1175                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1176                     remote_ipaddr, remote_port);
1177
1178                 nc = channel_new("accepted x11 socket",
1179                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1180                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1181                 if (compat20) {
1182                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1183                         packet_put_cstring("x11");
1184                         packet_put_int(nc->self);
1185                         packet_put_int(nc->local_window_max);
1186                         packet_put_int(nc->local_maxpacket);
1187                         /* originator ipaddr and port */
1188                         packet_put_cstring(remote_ipaddr);
1189                         if (datafellows & SSH_BUG_X11FWD) {
1190                                 debug2("ssh2 x11 bug compat mode");
1191                         } else {
1192                                 packet_put_int(remote_port);
1193                         }
1194                         packet_send();
1195                 } else {
1196                         packet_start(SSH_SMSG_X11_OPEN);
1197                         packet_put_int(nc->self);
1198                         if (packet_get_protocol_flags() &
1199                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1200                                 packet_put_cstring(buf);
1201                         packet_send();
1202                 }
1203                 xfree(remote_ipaddr);
1204         }
1205 }
1206
1207 static void
1208 port_open_helper(Channel *c, char *rtype)
1209 {
1210         int direct;
1211         char buf[1024];
1212         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1213         int remote_port = get_peer_port(c->sock);
1214
1215         direct = (strcmp(rtype, "direct-tcpip") == 0);
1216
1217         snprintf(buf, sizeof buf,
1218             "%s: listening port %d for %.100s port %d, "
1219             "connect from %.200s port %d",
1220             rtype, c->listening_port, c->path, c->host_port,
1221             remote_ipaddr, remote_port);
1222
1223         xfree(c->remote_name);
1224         c->remote_name = xstrdup(buf);
1225
1226         if (compat20) {
1227                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1228                 packet_put_cstring(rtype);
1229                 packet_put_int(c->self);
1230                 packet_put_int(c->local_window_max);
1231                 packet_put_int(c->local_maxpacket);
1232                 if (direct) {
1233                         /* target host, port */
1234                         packet_put_cstring(c->path);
1235                         packet_put_int(c->host_port);
1236                 } else {
1237                         /* listen address, port */
1238                         packet_put_cstring(c->path);
1239                         packet_put_int(c->listening_port);
1240                 }
1241                 /* originator host and port */
1242                 packet_put_cstring(remote_ipaddr);
1243                 packet_put_int((u_int)remote_port);
1244                 packet_send();
1245         } else {
1246                 packet_start(SSH_MSG_PORT_OPEN);
1247                 packet_put_int(c->self);
1248                 packet_put_cstring(c->path);
1249                 packet_put_int(c->host_port);
1250                 if (packet_get_protocol_flags() &
1251                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1252                         packet_put_cstring(c->remote_name);
1253                 packet_send();
1254         }
1255         xfree(remote_ipaddr);
1256 }
1257
1258 static void
1259 channel_set_reuseaddr(int fd)
1260 {
1261         int on = 1;
1262
1263         /*
1264          * Set socket options.
1265          * Allow local port reuse in TIME_WAIT.
1266          */
1267         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1268                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1269 }
1270
1271 /*
1272  * This socket is listening for connections to a forwarded TCP/IP port.
1273  */
1274 static void
1275 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1276 {
1277         Channel *nc;
1278         struct sockaddr addr;
1279         int newsock, nextstate;
1280         socklen_t addrlen;
1281         char *rtype;
1282
1283         if (FD_ISSET(c->sock, readset)) {
1284                 debug("Connection to port %d forwarding "
1285                     "to %.100s port %d requested.",
1286                     c->listening_port, c->path, c->host_port);
1287
1288                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1289                         nextstate = SSH_CHANNEL_OPENING;
1290                         rtype = "forwarded-tcpip";
1291                 } else {
1292                         if (c->host_port == 0) {
1293                                 nextstate = SSH_CHANNEL_DYNAMIC;
1294                                 rtype = "dynamic-tcpip";
1295                         } else {
1296                                 nextstate = SSH_CHANNEL_OPENING;
1297                                 rtype = "direct-tcpip";
1298                         }
1299                 }
1300
1301                 addrlen = sizeof(addr);
1302                 newsock = accept(c->sock, &addr, &addrlen);
1303                 if (newsock < 0) {
1304                         error("accept: %.100s", strerror(errno));
1305                         return;
1306                 }
1307                 set_nodelay(newsock);
1308                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1309                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1310                 nc->listening_port = c->listening_port;
1311                 nc->host_port = c->host_port;
1312                 strlcpy(nc->path, c->path, sizeof(nc->path));
1313
1314                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1315                         /*
1316                          * do not call the channel_post handler until
1317                          * this flag has been reset by a pre-handler.
1318                          * otherwise the FD_ISSET calls might overflow
1319                          */
1320                         nc->delayed = 1;
1321                 } else {
1322                         port_open_helper(nc, rtype);
1323                 }
1324         }
1325 }
1326
1327 /*
1328  * This is the authentication agent socket listening for connections from
1329  * clients.
1330  */
1331 static void
1332 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1333 {
1334         Channel *nc;
1335         int newsock;
1336         struct sockaddr addr;
1337         socklen_t addrlen;
1338
1339         if (FD_ISSET(c->sock, readset)) {
1340                 addrlen = sizeof(addr);
1341                 newsock = accept(c->sock, &addr, &addrlen);
1342                 if (newsock < 0) {
1343                         error("accept from auth socket: %.100s", strerror(errno));
1344                         return;
1345                 }
1346                 nc = channel_new("accepted auth socket",
1347                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1348                     c->local_window_max, c->local_maxpacket,
1349                     0, "accepted auth socket", 1);
1350                 if (compat20) {
1351                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1352                         packet_put_cstring("auth-agent@openssh.com");
1353                         packet_put_int(nc->self);
1354                         packet_put_int(c->local_window_max);
1355                         packet_put_int(c->local_maxpacket);
1356                 } else {
1357                         packet_start(SSH_SMSG_AGENT_OPEN);
1358                         packet_put_int(nc->self);
1359                 }
1360                 packet_send();
1361         }
1362 }
1363
1364 static void
1365 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1366 {
1367         int err = 0;
1368         socklen_t sz = sizeof(err);
1369
1370         if (FD_ISSET(c->sock, writeset)) {
1371                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1372                         err = errno;
1373                         error("getsockopt SO_ERROR failed");
1374                 }
1375                 if (err == 0) {
1376                         debug("channel %d: connected", c->self);
1377                         c->type = SSH_CHANNEL_OPEN;
1378                         if (compat20) {
1379                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1380                                 packet_put_int(c->remote_id);
1381                                 packet_put_int(c->self);
1382                                 packet_put_int(c->local_window);
1383                                 packet_put_int(c->local_maxpacket);
1384                         } else {
1385                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1386                                 packet_put_int(c->remote_id);
1387                                 packet_put_int(c->self);
1388                         }
1389                 } else {
1390                         debug("channel %d: not connected: %s",
1391                             c->self, strerror(err));
1392                         if (compat20) {
1393                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1394                                 packet_put_int(c->remote_id);
1395                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1396                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1397                                         packet_put_cstring(strerror(err));
1398                                         packet_put_cstring("");
1399                                 }
1400                         } else {
1401                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1402                                 packet_put_int(c->remote_id);
1403                         }
1404                         chan_mark_dead(c);
1405                 }
1406                 packet_send();
1407         }
1408 }
1409
1410 static int
1411 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1412 {
1413         char buf[CHAN_RBUF];
1414         int len;
1415
1416         if (c->rfd != -1 &&
1417             FD_ISSET(c->rfd, readset)) {
1418                 errno = 0;
1419                 len = read(c->rfd, buf, sizeof(buf));
1420                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1421                         return 1;
1422 #ifndef PTY_ZEROREAD
1423                 if (len <= 0) {
1424 #else
1425                 if (len < 0 || (len == 0 && errno != 0)) {
1426 #endif
1427                         debug2("channel %d: read<=0 rfd %d len %d",
1428                             c->self, c->rfd, len);
1429                         if (c->type != SSH_CHANNEL_OPEN) {
1430                                 debug2("channel %d: not open", c->self);
1431                                 chan_mark_dead(c);
1432                                 return -1;
1433                         } else if (compat13) {
1434                                 buffer_clear(&c->output);
1435                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1436                                 debug2("channel %d: input draining.", c->self);
1437                         } else {
1438                                 chan_read_failed(c);
1439                         }
1440                         return -1;
1441                 }
1442                 if (c->input_filter != NULL) {
1443                         if (c->input_filter(c, buf, len) == -1) {
1444                                 debug2("channel %d: filter stops", c->self);
1445                                 chan_read_failed(c);
1446                         }
1447                 } else if (c->datagram) {
1448                         buffer_put_string(&c->input, buf, len);
1449                 } else {
1450                         buffer_append(&c->input, buf, len);
1451                 }
1452         }
1453         return 1;
1454 }
1455
1456 static int
1457 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1458 {
1459         struct termios tio;
1460         u_char *data = NULL, *buf;
1461         u_int dlen;
1462         int len;
1463
1464         /* Send buffered output data to the socket. */
1465         if (c->wfd != -1 &&
1466             FD_ISSET(c->wfd, writeset) &&
1467             buffer_len(&c->output) > 0) {
1468                 if (c->output_filter != NULL) {
1469                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1470                                 debug2("channel %d: filter stops", c->self);
1471                                 if (c->type != SSH_CHANNEL_OPEN)
1472                                         chan_mark_dead(c);
1473                                 else
1474                                         chan_write_failed(c);
1475                                 return -1;
1476                         }
1477                 } else if (c->datagram) {
1478                         buf = data = buffer_get_string(&c->output, &dlen);
1479                 } else {
1480                         buf = data = buffer_ptr(&c->output);
1481                         dlen = buffer_len(&c->output);
1482                 }
1483
1484                 if (c->datagram) {
1485                         /* ignore truncated writes, datagrams might get lost */
1486                         c->local_consumed += dlen + 4;
1487                         len = write(c->wfd, buf, dlen);
1488                         xfree(data);
1489                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1490                                 return 1;
1491                         if (len <= 0) {
1492                                 if (c->type != SSH_CHANNEL_OPEN)
1493                                         chan_mark_dead(c);
1494                                 else
1495                                         chan_write_failed(c);
1496                                 return -1;
1497                         }
1498                         return 1;
1499                 }
1500 #ifdef _AIX
1501                 /* XXX: Later AIX versions can't push as much data to tty */
1502                 if (compat20 && c->wfd_isatty)
1503                         dlen = MIN(dlen, 8*1024);
1504 #endif
1505
1506                 len = write(c->wfd, buf, dlen);
1507                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1508                         return 1;
1509                 if (len <= 0) {
1510                         if (c->type != SSH_CHANNEL_OPEN) {
1511                                 debug2("channel %d: not open", c->self);
1512                                 chan_mark_dead(c);
1513                                 return -1;
1514                         } else if (compat13) {
1515                                 buffer_clear(&c->output);
1516                                 debug2("channel %d: input draining.", c->self);
1517                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1518                         } else {
1519                                 chan_write_failed(c);
1520                         }
1521                         return -1;
1522                 }
1523                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1524                         if (tcgetattr(c->wfd, &tio) == 0 &&
1525                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1526                                 /*
1527                                  * Simulate echo to reduce the impact of
1528                                  * traffic analysis. We need to match the
1529                                  * size of a SSH2_MSG_CHANNEL_DATA message
1530                                  * (4 byte channel id + buf)
1531                                  */
1532                                 packet_send_ignore(4 + len);
1533                                 packet_send();
1534                         }
1535                 }
1536                 buffer_consume(&c->output, len);
1537                 if (compat20 && len > 0) {
1538                         c->local_consumed += len;
1539                 }
1540         }
1541         return 1;
1542 }
1543
1544 static int
1545 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1546 {
1547         char buf[CHAN_RBUF];
1548         int len;
1549
1550 /** XXX handle drain efd, too */
1551         if (c->efd != -1) {
1552                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1553                     FD_ISSET(c->efd, writeset) &&
1554                     buffer_len(&c->extended) > 0) {
1555                         len = write(c->efd, buffer_ptr(&c->extended),
1556                             buffer_len(&c->extended));
1557                         debug2("channel %d: written %d to efd %d",
1558                             c->self, len, c->efd);
1559                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1560                                 return 1;
1561                         if (len <= 0) {
1562                                 debug2("channel %d: closing write-efd %d",
1563                                     c->self, c->efd);
1564                                 channel_close_fd(&c->efd);
1565                         } else {
1566                                 buffer_consume(&c->extended, len);
1567                                 c->local_consumed += len;
1568                         }
1569                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1570                     FD_ISSET(c->efd, readset)) {
1571                         len = read(c->efd, buf, sizeof(buf));
1572                         debug2("channel %d: read %d from efd %d",
1573                             c->self, len, c->efd);
1574                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1575                                 return 1;
1576                         if (len <= 0) {
1577                                 debug2("channel %d: closing read-efd %d",
1578                                     c->self, c->efd);
1579                                 channel_close_fd(&c->efd);
1580                         } else {
1581                                 buffer_append(&c->extended, buf, len);
1582                         }
1583                 }
1584         }
1585         return 1;
1586 }
1587
1588 static int
1589 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1590 {
1591         char buf[16];
1592         int len;
1593
1594         /* Monitor control fd to detect if the slave client exits */
1595         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1596                 len = read(c->ctl_fd, buf, sizeof(buf));
1597                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1598                         return 1;
1599                 if (len <= 0) {
1600                         debug2("channel %d: ctl read<=0", c->self);
1601                         if (c->type != SSH_CHANNEL_OPEN) {
1602                                 debug2("channel %d: not open", c->self);
1603                                 chan_mark_dead(c);
1604                                 return -1;
1605                         } else {
1606                                 chan_read_failed(c);
1607                                 chan_write_failed(c);
1608                         }
1609                         return -1;
1610                 } else
1611                         fatal("%s: unexpected data on ctl fd", __func__);
1612         }
1613         return 1;
1614 }
1615
1616 static int
1617 channel_check_window(Channel *c)
1618 {
1619         if (c->type == SSH_CHANNEL_OPEN &&
1620             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1621             c->local_window < c->local_window_max/2 &&
1622             c->local_consumed > 0) {
1623                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1624                 packet_put_int(c->remote_id);
1625                 packet_put_int(c->local_consumed);
1626                 packet_send();
1627                 debug2("channel %d: window %d sent adjust %d",
1628                     c->self, c->local_window,
1629                     c->local_consumed);
1630                 c->local_window += c->local_consumed;
1631                 c->local_consumed = 0;
1632         }
1633         return 1;
1634 }
1635
1636 static void
1637 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1638 {
1639         if (c->delayed)
1640                 return;
1641         channel_handle_rfd(c, readset, writeset);
1642         channel_handle_wfd(c, readset, writeset);
1643         if (!compat20)
1644                 return;
1645         channel_handle_efd(c, readset, writeset);
1646         channel_handle_ctl(c, readset, writeset);
1647         channel_check_window(c);
1648 }
1649
1650 static void
1651 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1652 {
1653         int len;
1654
1655         /* Send buffered output data to the socket. */
1656         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1657                 len = write(c->sock, buffer_ptr(&c->output),
1658                             buffer_len(&c->output));
1659                 if (len <= 0)
1660                         buffer_clear(&c->output);
1661                 else
1662                         buffer_consume(&c->output, len);
1663         }
1664 }
1665
1666 static void
1667 channel_handler_init_20(void)
1668 {
1669         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1670         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1671         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1672         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1673         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1674         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1675         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1676         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1677
1678         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1679         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1680         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1681         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1682         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1683         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1684         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1685 }
1686
1687 static void
1688 channel_handler_init_13(void)
1689 {
1690         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1691         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1692         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1693         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1694         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1695         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1696         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1697         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1698         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1699
1700         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1701         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1702         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1703         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1704         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1705         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1706         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1707 }
1708
1709 static void
1710 channel_handler_init_15(void)
1711 {
1712         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1713         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1714         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1715         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1716         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1717         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1718         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1719
1720         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1721         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1722         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1723         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1724         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1725         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1726 }
1727
1728 static void
1729 channel_handler_init(void)
1730 {
1731         int i;
1732
1733         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1734                 channel_pre[i] = NULL;
1735                 channel_post[i] = NULL;
1736         }
1737         if (compat20)
1738                 channel_handler_init_20();
1739         else if (compat13)
1740                 channel_handler_init_13();
1741         else
1742                 channel_handler_init_15();
1743 }
1744
1745 /* gc dead channels */
1746 static void
1747 channel_garbage_collect(Channel *c)
1748 {
1749         if (c == NULL)
1750                 return;
1751         if (c->detach_user != NULL) {
1752                 if (!chan_is_dead(c, c->detach_close))
1753                         return;
1754                 debug2("channel %d: gc: notify user", c->self);
1755                 c->detach_user(c->self, NULL);
1756                 /* if we still have a callback */
1757                 if (c->detach_user != NULL)
1758                         return;
1759                 debug2("channel %d: gc: user detached", c->self);
1760         }
1761         if (!chan_is_dead(c, 1))
1762                 return;
1763         debug2("channel %d: garbage collecting", c->self);
1764         channel_free(c);
1765 }
1766
1767 static void
1768 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1769 {
1770         static int did_init = 0;
1771         u_int i;
1772         Channel *c;
1773
1774         if (!did_init) {
1775                 channel_handler_init();
1776                 did_init = 1;
1777         }
1778         for (i = 0; i < channels_alloc; i++) {
1779                 c = channels[i];
1780                 if (c == NULL)
1781                         continue;
1782                 if (ftab[c->type] != NULL)
1783                         (*ftab[c->type])(c, readset, writeset);
1784                 channel_garbage_collect(c);
1785         }
1786 }
1787
1788 /*
1789  * Allocate/update select bitmasks and add any bits relevant to channels in
1790  * select bitmasks.
1791  */
1792 void
1793 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1794     u_int *nallocp, int rekeying)
1795 {
1796         u_int n, sz, nfdset;
1797
1798         n = MAX(*maxfdp, channel_max_fd);
1799
1800         nfdset = howmany(n+1, NFDBITS);
1801         /* Explicitly test here, because xrealloc isn't always called */
1802         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1803                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1804         sz = nfdset * sizeof(fd_mask);
1805
1806         /* perhaps check sz < nalloc/2 and shrink? */
1807         if (*readsetp == NULL || sz > *nallocp) {
1808                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1809                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1810                 *nallocp = sz;
1811         }
1812         *maxfdp = n;
1813         memset(*readsetp, 0, sz);
1814         memset(*writesetp, 0, sz);
1815
1816         if (!rekeying)
1817                 channel_handler(channel_pre, *readsetp, *writesetp);
1818 }
1819
1820 /*
1821  * After select, perform any appropriate operations for channels which have
1822  * events pending.
1823  */
1824 void
1825 channel_after_select(fd_set *readset, fd_set *writeset)
1826 {
1827         channel_handler(channel_post, readset, writeset);
1828 }
1829
1830
1831 /* If there is data to send to the connection, enqueue some of it now. */
1832 void
1833 channel_output_poll(void)
1834 {
1835         Channel *c;
1836         u_int i, len;
1837
1838         for (i = 0; i < channels_alloc; i++) {
1839                 c = channels[i];
1840                 if (c == NULL)
1841                         continue;
1842
1843                 /*
1844                  * We are only interested in channels that can have buffered
1845                  * incoming data.
1846                  */
1847                 if (compat13) {
1848                         if (c->type != SSH_CHANNEL_OPEN &&
1849                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1850                                 continue;
1851                 } else {
1852                         if (c->type != SSH_CHANNEL_OPEN)
1853                                 continue;
1854                 }
1855                 if (compat20 &&
1856                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1857                         /* XXX is this true? */
1858                         debug3("channel %d: will not send data after close", c->self);
1859                         continue;
1860                 }
1861
1862                 /* Get the amount of buffered data for this channel. */
1863                 if ((c->istate == CHAN_INPUT_OPEN ||
1864                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1865                     (len = buffer_len(&c->input)) > 0) {
1866                         if (c->datagram) {
1867                                 if (len > 0) {
1868                                         u_char *data;
1869                                         u_int dlen;
1870
1871                                         data = buffer_get_string(&c->input,
1872                                             &dlen);
1873                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1874                                         packet_put_int(c->remote_id);
1875                                         packet_put_string(data, dlen);
1876                                         packet_send();
1877                                         c->remote_window -= dlen + 4;
1878                                         xfree(data);
1879                                 }
1880                                 continue;
1881                         }
1882                         /*
1883                          * Send some data for the other side over the secure
1884                          * connection.
1885                          */
1886                         if (compat20) {
1887                                 if (len > c->remote_window)
1888                                         len = c->remote_window;
1889                                 if (len > c->remote_maxpacket)
1890                                         len = c->remote_maxpacket;
1891                         } else {
1892                                 if (packet_is_interactive()) {
1893                                         if (len > 1024)
1894                                                 len = 512;
1895                                 } else {
1896                                         /* Keep the packets at reasonable size. */
1897                                         if (len > packet_get_maxsize()/2)
1898                                                 len = packet_get_maxsize()/2;
1899                                 }
1900                         }
1901                         if (len > 0) {
1902                                 packet_start(compat20 ?
1903                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1904                                 packet_put_int(c->remote_id);
1905                                 packet_put_string(buffer_ptr(&c->input), len);
1906                                 packet_send();
1907                                 buffer_consume(&c->input, len);
1908                                 c->remote_window -= len;
1909                         }
1910                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1911                         if (compat13)
1912                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1913                         /*
1914                          * input-buffer is empty and read-socket shutdown:
1915                          * tell peer, that we will not send more data: send IEOF.
1916                          * hack for extended data: delay EOF if EFD still in use.
1917                          */
1918                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1919                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1920                                     c->self, c->efd, buffer_len(&c->extended));
1921                         else
1922                                 chan_ibuf_empty(c);
1923                 }
1924                 /* Send extended data, i.e. stderr */
1925                 if (compat20 &&
1926                     !(c->flags & CHAN_EOF_SENT) &&
1927                     c->remote_window > 0 &&
1928                     (len = buffer_len(&c->extended)) > 0 &&
1929                     c->extended_usage == CHAN_EXTENDED_READ) {
1930                         debug2("channel %d: rwin %u elen %u euse %d",
1931                             c->self, c->remote_window, buffer_len(&c->extended),
1932                             c->extended_usage);
1933                         if (len > c->remote_window)
1934                                 len = c->remote_window;
1935                         if (len > c->remote_maxpacket)
1936                                 len = c->remote_maxpacket;
1937                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1938                         packet_put_int(c->remote_id);
1939                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1940                         packet_put_string(buffer_ptr(&c->extended), len);
1941                         packet_send();
1942                         buffer_consume(&c->extended, len);
1943                         c->remote_window -= len;
1944                         debug2("channel %d: sent ext data %d", c->self, len);
1945                 }
1946         }
1947 }
1948
1949
1950 /* -- protocol input */
1951
1952 /* ARGSUSED */
1953 void
1954 channel_input_data(int type, u_int32_t seq, void *ctxt)
1955 {
1956         int id;
1957         char *data;
1958         u_int data_len;
1959         Channel *c;
1960
1961         /* Get the channel number and verify it. */
1962         id = packet_get_int();
1963         c = channel_lookup(id);
1964         if (c == NULL)
1965                 packet_disconnect("Received data for nonexistent channel %d.", id);
1966
1967         /* Ignore any data for non-open channels (might happen on close) */
1968         if (c->type != SSH_CHANNEL_OPEN &&
1969             c->type != SSH_CHANNEL_X11_OPEN)
1970                 return;
1971
1972         /* Get the data. */
1973         data = packet_get_string(&data_len);
1974
1975         /*
1976          * Ignore data for protocol > 1.3 if output end is no longer open.
1977          * For protocol 2 the sending side is reducing its window as it sends
1978          * data, so we must 'fake' consumption of the data in order to ensure
1979          * that window updates are sent back.  Otherwise the connection might
1980          * deadlock.
1981          */
1982         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1983                 if (compat20) {
1984                         c->local_window -= data_len;
1985                         c->local_consumed += data_len;
1986                 }
1987                 xfree(data);
1988                 return;
1989         }
1990
1991         if (compat20) {
1992                 if (data_len > c->local_maxpacket) {
1993                         logit("channel %d: rcvd big packet %d, maxpack %d",
1994                             c->self, data_len, c->local_maxpacket);
1995                 }
1996                 if (data_len > c->local_window) {
1997                         logit("channel %d: rcvd too much data %d, win %d",
1998                             c->self, data_len, c->local_window);
1999                         xfree(data);
2000                         return;
2001                 }
2002                 c->local_window -= data_len;
2003         }
2004         packet_check_eom();
2005         if (c->datagram)
2006                 buffer_put_string(&c->output, data, data_len);
2007         else
2008                 buffer_append(&c->output, data, data_len);
2009         xfree(data);
2010 }
2011
2012 /* ARGSUSED */
2013 void
2014 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2015 {
2016         int id;
2017         char *data;
2018         u_int data_len, tcode;
2019         Channel *c;
2020
2021         /* Get the channel number and verify it. */
2022         id = packet_get_int();
2023         c = channel_lookup(id);
2024
2025         if (c == NULL)
2026                 packet_disconnect("Received extended_data for bad channel %d.", id);
2027         if (c->type != SSH_CHANNEL_OPEN) {
2028                 logit("channel %d: ext data for non open", id);
2029                 return;
2030         }
2031         if (c->flags & CHAN_EOF_RCVD) {
2032                 if (datafellows & SSH_BUG_EXTEOF)
2033                         debug("channel %d: accepting ext data after eof", id);
2034                 else
2035                         packet_disconnect("Received extended_data after EOF "
2036                             "on channel %d.", id);
2037         }
2038         tcode = packet_get_int();
2039         if (c->efd == -1 ||
2040             c->extended_usage != CHAN_EXTENDED_WRITE ||
2041             tcode != SSH2_EXTENDED_DATA_STDERR) {
2042                 logit("channel %d: bad ext data", c->self);
2043                 return;
2044         }
2045         data = packet_get_string(&data_len);
2046         packet_check_eom();
2047         if (data_len > c->local_window) {
2048                 logit("channel %d: rcvd too much extended_data %d, win %d",
2049                     c->self, data_len, c->local_window);
2050                 xfree(data);
2051                 return;
2052         }
2053         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2054         c->local_window -= data_len;
2055         buffer_append(&c->extended, data, data_len);
2056         xfree(data);
2057 }
2058
2059 /* ARGSUSED */
2060 void
2061 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2062 {
2063         int id;
2064         Channel *c;
2065
2066         id = packet_get_int();
2067         packet_check_eom();
2068         c = channel_lookup(id);
2069         if (c == NULL)
2070                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2071         chan_rcvd_ieof(c);
2072
2073         /* XXX force input close */
2074         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2075                 debug("channel %d: FORCE input drain", c->self);
2076                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2077                 if (buffer_len(&c->input) == 0)
2078                         chan_ibuf_empty(c);
2079         }
2080
2081 }
2082
2083 /* ARGSUSED */
2084 void
2085 channel_input_close(int type, u_int32_t seq, void *ctxt)
2086 {
2087         int id;
2088         Channel *c;
2089
2090         id = packet_get_int();
2091         packet_check_eom();
2092         c = channel_lookup(id);
2093         if (c == NULL)
2094                 packet_disconnect("Received close for nonexistent channel %d.", id);
2095
2096         /*
2097          * Send a confirmation that we have closed the channel and no more
2098          * data is coming for it.
2099          */
2100         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2101         packet_put_int(c->remote_id);
2102         packet_send();
2103
2104         /*
2105          * If the channel is in closed state, we have sent a close request,
2106          * and the other side will eventually respond with a confirmation.
2107          * Thus, we cannot free the channel here, because then there would be
2108          * no-one to receive the confirmation.  The channel gets freed when
2109          * the confirmation arrives.
2110          */
2111         if (c->type != SSH_CHANNEL_CLOSED) {
2112                 /*
2113                  * Not a closed channel - mark it as draining, which will
2114                  * cause it to be freed later.
2115                  */
2116                 buffer_clear(&c->input);
2117                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2118         }
2119 }
2120
2121 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2122 /* ARGSUSED */
2123 void
2124 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2125 {
2126         int id = packet_get_int();
2127         Channel *c = channel_lookup(id);
2128
2129         packet_check_eom();
2130         if (c == NULL)
2131                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2132         chan_rcvd_oclose(c);
2133 }
2134
2135 /* ARGSUSED */
2136 void
2137 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2138 {
2139         int id = packet_get_int();
2140         Channel *c = channel_lookup(id);
2141
2142         packet_check_eom();
2143         if (c == NULL)
2144                 packet_disconnect("Received close confirmation for "
2145                     "out-of-range channel %d.", id);
2146         if (c->type != SSH_CHANNEL_CLOSED)
2147                 packet_disconnect("Received close confirmation for "
2148                     "non-closed channel %d (type %d).", id, c->type);
2149         channel_free(c);
2150 }
2151
2152 /* ARGSUSED */
2153 void
2154 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2155 {
2156         int id, remote_id;
2157         Channel *c;
2158
2159         id = packet_get_int();
2160         c = channel_lookup(id);
2161
2162         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2163                 packet_disconnect("Received open confirmation for "
2164                     "non-opening channel %d.", id);
2165         remote_id = packet_get_int();
2166         /* Record the remote channel number and mark that the channel is now open. */
2167         c->remote_id = remote_id;
2168         c->type = SSH_CHANNEL_OPEN;
2169
2170         if (compat20) {
2171                 c->remote_window = packet_get_int();
2172                 c->remote_maxpacket = packet_get_int();
2173                 if (c->confirm) {
2174                         debug2("callback start");
2175                         c->confirm(c->self, c->confirm_ctx);
2176                         debug2("callback done");
2177                 }
2178                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2179                     c->remote_window, c->remote_maxpacket);
2180         }
2181         packet_check_eom();
2182 }
2183
2184 static char *
2185 reason2txt(int reason)
2186 {
2187         switch (reason) {
2188         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2189                 return "administratively prohibited";
2190         case SSH2_OPEN_CONNECT_FAILED:
2191                 return "connect failed";
2192         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2193                 return "unknown channel type";
2194         case SSH2_OPEN_RESOURCE_SHORTAGE:
2195                 return "resource shortage";
2196         }
2197         return "unknown reason";
2198 }
2199
2200 /* ARGSUSED */
2201 void
2202 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2203 {
2204         int id, reason;
2205         char *msg = NULL, *lang = NULL;
2206         Channel *c;
2207
2208         id = packet_get_int();
2209         c = channel_lookup(id);
2210
2211         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2212                 packet_disconnect("Received open failure for "
2213                     "non-opening channel %d.", id);
2214         if (compat20) {
2215                 reason = packet_get_int();
2216                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2217                         msg  = packet_get_string(NULL);
2218                         lang = packet_get_string(NULL);
2219                 }
2220                 logit("channel %d: open failed: %s%s%s", id,
2221                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2222                 if (msg != NULL)
2223                         xfree(msg);
2224                 if (lang != NULL)
2225                         xfree(lang);
2226         }
2227         packet_check_eom();
2228         /* Free the channel.  This will also close the socket. */
2229         channel_free(c);
2230 }
2231
2232 /* ARGSUSED */
2233 void
2234 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2235 {
2236         Channel *c;
2237         int id;
2238         u_int adjust;
2239
2240         if (!compat20)
2241                 return;
2242
2243         /* Get the channel number and verify it. */
2244         id = packet_get_int();
2245         c = channel_lookup(id);
2246
2247         if (c == NULL) {
2248                 logit("Received window adjust for non-open channel %d.", id);
2249                 return;
2250         }
2251         adjust = packet_get_int();
2252         packet_check_eom();
2253         debug2("channel %d: rcvd adjust %u", id, adjust);
2254         c->remote_window += adjust;
2255 }
2256
2257 /* ARGSUSED */
2258 void
2259 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2260 {
2261         Channel *c = NULL;
2262         u_short host_port;
2263         char *host, *originator_string;
2264         int remote_id, sock = -1;
2265
2266         remote_id = packet_get_int();
2267         host = packet_get_string(NULL);
2268         host_port = packet_get_int();
2269
2270         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2271                 originator_string = packet_get_string(NULL);
2272         } else {
2273                 originator_string = xstrdup("unknown (remote did not supply name)");
2274         }
2275         packet_check_eom();
2276         sock = channel_connect_to(host, host_port);
2277         if (sock != -1) {
2278                 c = channel_new("connected socket",
2279                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2280                     originator_string, 1);
2281                 c->remote_id = remote_id;
2282         }
2283         xfree(originator_string);
2284         if (c == NULL) {
2285                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2286                 packet_put_int(remote_id);
2287                 packet_send();
2288         }
2289         xfree(host);
2290 }
2291
2292
2293 /* -- tcp forwarding */
2294
2295 void
2296 channel_set_af(int af)
2297 {
2298         IPv4or6 = af;
2299 }
2300
2301 static int
2302 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2303     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2304 {
2305         Channel *c;
2306         int sock, r, success = 0, wildcard = 0, is_client;
2307         struct addrinfo hints, *ai, *aitop;
2308         const char *host, *addr;
2309         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2310
2311         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2312             listen_addr : host_to_connect;
2313         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2314
2315         if (host == NULL) {
2316                 error("No forward host name.");
2317                 return 0;
2318         }
2319         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2320                 error("Forward host name too long.");
2321                 return 0;
2322         }
2323
2324         /*
2325          * Determine whether or not a port forward listens to loopback,
2326          * specified address or wildcard. On the client, a specified bind
2327          * address will always override gateway_ports. On the server, a
2328          * gateway_ports of 1 (``yes'') will override the client's
2329          * specification and force a wildcard bind, whereas a value of 2
2330          * (``clientspecified'') will bind to whatever address the client
2331          * asked for.
2332          *
2333          * Special-case listen_addrs are:
2334          *
2335          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2336          * "" (empty string), "*"  -> wildcard v4/v6
2337          * "localhost"             -> loopback v4/v6
2338          */
2339         addr = NULL;
2340         if (listen_addr == NULL) {
2341                 /* No address specified: default to gateway_ports setting */
2342                 if (gateway_ports)
2343                         wildcard = 1;
2344         } else if (gateway_ports || is_client) {
2345                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2346                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2347                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2348                     (!is_client && gateway_ports == 1))
2349                         wildcard = 1;
2350                 else if (strcmp(listen_addr, "localhost") != 0)
2351                         addr = listen_addr;
2352         }
2353
2354         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2355             type, wildcard, (addr == NULL) ? "NULL" : addr);
2356
2357         /*
2358          * getaddrinfo returns a loopback address if the hostname is
2359          * set to NULL and hints.ai_flags is not AI_PASSIVE
2360          */
2361         memset(&hints, 0, sizeof(hints));
2362         hints.ai_family = IPv4or6;
2363         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2364         hints.ai_socktype = SOCK_STREAM;
2365         snprintf(strport, sizeof strport, "%d", listen_port);
2366         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2367                 if (addr == NULL) {
2368                         /* This really shouldn't happen */
2369                         packet_disconnect("getaddrinfo: fatal error: %s",
2370                             gai_strerror(r));
2371                 } else {
2372                         error("channel_setup_fwd_listener: "
2373                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2374                 }
2375                 return 0;
2376         }
2377
2378         for (ai = aitop; ai; ai = ai->ai_next) {
2379                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2380                         continue;
2381                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2382                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2383                         error("channel_setup_fwd_listener: getnameinfo failed");
2384                         continue;
2385                 }
2386                 /* Create a port to listen for the host. */
2387                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2388                 if (sock < 0) {
2389                         /* this is no error since kernel may not support ipv6 */
2390                         verbose("socket: %.100s", strerror(errno));
2391                         continue;
2392                 }
2393
2394                 channel_set_reuseaddr(sock);
2395
2396                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2397
2398                 /* Bind the socket to the address. */
2399                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2400                         /* address can be in use ipv6 address is already bound */
2401                         if (!ai->ai_next)
2402                                 error("bind: %.100s", strerror(errno));
2403                         else
2404                                 verbose("bind: %.100s", strerror(errno));
2405
2406                         close(sock);
2407                         continue;
2408                 }
2409                 /* Start listening for connections on the socket. */
2410                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2411                         error("listen: %.100s", strerror(errno));
2412                         close(sock);
2413                         continue;
2414                 }
2415                 /* Allocate a channel number for the socket. */
2416                 c = channel_new("port listener", type, sock, sock, -1,
2417                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2418                     0, "port listener", 1);
2419                 strlcpy(c->path, host, sizeof(c->path));
2420                 c->host_port = port_to_connect;
2421                 c->listening_port = listen_port;
2422                 success = 1;
2423         }
2424         if (success == 0)
2425                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2426                     listen_port);
2427         freeaddrinfo(aitop);
2428         return success;
2429 }
2430
2431 int
2432 channel_cancel_rport_listener(const char *host, u_short port)
2433 {
2434         u_int i;
2435         int found = 0;
2436
2437         for (i = 0; i < channels_alloc; i++) {
2438                 Channel *c = channels[i];
2439
2440                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2441                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2442                     c->listening_port == port) {
2443                         debug2("%s: close channel %d", __func__, i);
2444                         channel_free(c);
2445                         found = 1;
2446                 }
2447         }
2448
2449         return (found);
2450 }
2451
2452 /* protocol local port fwd, used by ssh (and sshd in v1) */
2453 int
2454 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2455     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2456 {
2457         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2458             listen_host, listen_port, host_to_connect, port_to_connect,
2459             gateway_ports);
2460 }
2461
2462 /* protocol v2 remote port fwd, used by sshd */
2463 int
2464 channel_setup_remote_fwd_listener(const char *listen_address,
2465     u_short listen_port, int gateway_ports)
2466 {
2467         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2468             listen_address, listen_port, NULL, 0, gateway_ports);
2469 }
2470
2471 /*
2472  * Initiate forwarding of connections to port "port" on remote host through
2473  * the secure channel to host:port from local side.
2474  */
2475
2476 void
2477 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2478     const char *host_to_connect, u_short port_to_connect)
2479 {
2480         int type, success = 0;
2481
2482         /* Record locally that connection to this host/port is permitted. */
2483         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2484                 fatal("channel_request_remote_forwarding: too many forwards");
2485
2486         /* Send the forward request to the remote side. */
2487         if (compat20) {
2488                 const char *address_to_bind;
2489                 if (listen_host == NULL)
2490                         address_to_bind = "localhost";
2491                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2492                         address_to_bind = "";
2493                 else
2494                         address_to_bind = listen_host;
2495
2496                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2497                 packet_put_cstring("tcpip-forward");
2498                 packet_put_char(1);                     /* boolean: want reply */
2499                 packet_put_cstring(address_to_bind);
2500                 packet_put_int(listen_port);
2501                 packet_send();
2502                 packet_write_wait();
2503                 /* Assume that server accepts the request */
2504                 success = 1;
2505         } else {
2506                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2507                 packet_put_int(listen_port);
2508                 packet_put_cstring(host_to_connect);
2509                 packet_put_int(port_to_connect);
2510                 packet_send();
2511                 packet_write_wait();
2512
2513                 /* Wait for response from the remote side. */
2514                 type = packet_read();
2515                 switch (type) {
2516                 case SSH_SMSG_SUCCESS:
2517                         success = 1;
2518                         break;
2519                 case SSH_SMSG_FAILURE:
2520                         logit("Warning: Server denied remote port forwarding.");
2521                         break;
2522                 default:
2523                         /* Unknown packet */
2524                         packet_disconnect("Protocol error for port forward request:"
2525                             "received packet type %d.", type);
2526                 }
2527         }
2528         if (success) {
2529                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2530                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2531                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2532                 num_permitted_opens++;
2533         }
2534 }
2535
2536 /*
2537  * Request cancellation of remote forwarding of connection host:port from
2538  * local side.
2539  */
2540 void
2541 channel_request_rforward_cancel(const char *host, u_short port)
2542 {
2543         int i;
2544
2545         if (!compat20)
2546                 return;
2547
2548         for (i = 0; i < num_permitted_opens; i++) {
2549                 if (permitted_opens[i].host_to_connect != NULL &&
2550                     permitted_opens[i].listen_port == port)
2551                         break;
2552         }
2553         if (i >= num_permitted_opens) {
2554                 debug("%s: requested forward not found", __func__);
2555                 return;
2556         }
2557         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2558         packet_put_cstring("cancel-tcpip-forward");
2559         packet_put_char(0);
2560         packet_put_cstring(host == NULL ? "" : host);
2561         packet_put_int(port);
2562         packet_send();
2563
2564         permitted_opens[i].listen_port = 0;
2565         permitted_opens[i].port_to_connect = 0;
2566         xfree(permitted_opens[i].host_to_connect);
2567         permitted_opens[i].host_to_connect = NULL;
2568 }
2569
2570 /*
2571  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2572  * listening for the port, and sends back a success reply (or disconnect
2573  * message if there was an error).  This never returns if there was an error.
2574  */
2575 void
2576 channel_input_port_forward_request(int is_root, int gateway_ports)
2577 {
2578         u_short port, host_port;
2579         char *hostname;
2580
2581         /* Get arguments from the packet. */
2582         port = packet_get_int();
2583         hostname = packet_get_string(NULL);
2584         host_port = packet_get_int();
2585
2586 #ifndef HAVE_CYGWIN
2587         /*
2588          * Check that an unprivileged user is not trying to forward a
2589          * privileged port.
2590          */
2591         if (port < IPPORT_RESERVED && !is_root)
2592                 packet_disconnect(
2593                     "Requested forwarding of port %d but user is not root.",
2594                     port);
2595         if (host_port == 0)
2596                 packet_disconnect("Dynamic forwarding denied.");
2597 #endif
2598
2599         /* Initiate forwarding */
2600         channel_setup_local_fwd_listener(NULL, port, hostname,
2601             host_port, gateway_ports);
2602
2603         /* Free the argument string. */
2604         xfree(hostname);
2605 }
2606
2607 /*
2608  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2609  * usually called by the server, because the user could connect to any port
2610  * anyway, and the server has no way to know but to trust the client anyway.
2611  */
2612 void
2613 channel_permit_all_opens(void)
2614 {
2615         if (num_permitted_opens == 0)
2616                 all_opens_permitted = 1;
2617 }
2618
2619 void
2620 channel_add_permitted_opens(char *host, int port)
2621 {
2622         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2623                 fatal("channel_request_remote_forwarding: too many forwards");
2624         debug("allow port forwarding to host %s port %d", host, port);
2625
2626         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2627         permitted_opens[num_permitted_opens].port_to_connect = port;
2628         num_permitted_opens++;
2629
2630         all_opens_permitted = 0;
2631 }
2632
2633 void
2634 channel_clear_permitted_opens(void)
2635 {
2636         int i;
2637
2638         for (i = 0; i < num_permitted_opens; i++)
2639                 if (permitted_opens[i].host_to_connect != NULL)
2640                         xfree(permitted_opens[i].host_to_connect);
2641         num_permitted_opens = 0;
2642
2643 }
2644
2645 /* return socket to remote host, port */
2646 static int
2647 connect_to(const char *host, u_short port)
2648 {
2649         struct addrinfo hints, *ai, *aitop;
2650         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2651         int gaierr;
2652         int sock = -1;
2653
2654         memset(&hints, 0, sizeof(hints));
2655         hints.ai_family = IPv4or6;
2656         hints.ai_socktype = SOCK_STREAM;
2657         snprintf(strport, sizeof strport, "%d", port);
2658         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2659                 error("connect_to %.100s: unknown host (%s)", host,
2660                     gai_strerror(gaierr));
2661                 return -1;
2662         }
2663         for (ai = aitop; ai; ai = ai->ai_next) {
2664                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2665                         continue;
2666                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2667                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2668                         error("connect_to: getnameinfo failed");
2669                         continue;
2670                 }
2671                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2672                 if (sock < 0) {
2673                         if (ai->ai_next == NULL)
2674                                 error("socket: %.100s", strerror(errno));
2675                         else
2676                                 verbose("socket: %.100s", strerror(errno));
2677                         continue;
2678                 }
2679                 if (set_nonblock(sock) == -1)
2680                         fatal("%s: set_nonblock(%d)", __func__, sock);
2681                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2682                     errno != EINPROGRESS) {
2683                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2684                             strerror(errno));
2685                         close(sock);
2686                         continue;       /* fail -- try next */
2687                 }
2688                 break; /* success */
2689
2690         }
2691         freeaddrinfo(aitop);
2692         if (!ai) {
2693                 error("connect_to %.100s port %d: failed.", host, port);
2694                 return -1;
2695         }
2696         /* success */
2697         set_nodelay(sock);
2698         return sock;
2699 }
2700
2701 int
2702 channel_connect_by_listen_address(u_short listen_port)
2703 {
2704         int i;
2705
2706         for (i = 0; i < num_permitted_opens; i++)
2707                 if (permitted_opens[i].host_to_connect != NULL &&
2708                     permitted_opens[i].listen_port == listen_port)
2709                         return connect_to(
2710                             permitted_opens[i].host_to_connect,
2711                             permitted_opens[i].port_to_connect);
2712         error("WARNING: Server requests forwarding for unknown listen_port %d",
2713             listen_port);
2714         return -1;
2715 }
2716
2717 /* Check if connecting to that port is permitted and connect. */
2718 int
2719 channel_connect_to(const char *host, u_short port)
2720 {
2721         int i, permit;
2722
2723         permit = all_opens_permitted;
2724         if (!permit) {
2725                 for (i = 0; i < num_permitted_opens; i++)
2726                         if (permitted_opens[i].host_to_connect != NULL &&
2727                             permitted_opens[i].port_to_connect == port &&
2728                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2729                                 permit = 1;
2730
2731         }
2732         if (!permit) {
2733                 logit("Received request to connect to host %.100s port %d, "
2734                     "but the request was denied.", host, port);
2735                 return -1;
2736         }
2737         return connect_to(host, port);
2738 }
2739
2740 void
2741 channel_send_window_changes(void)
2742 {
2743         u_int i;
2744         struct winsize ws;
2745
2746         for (i = 0; i < channels_alloc; i++) {
2747                 if (channels[i] == NULL || !channels[i]->client_tty ||
2748                     channels[i]->type != SSH_CHANNEL_OPEN)
2749                         continue;
2750                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2751                         continue;
2752                 channel_request_start(i, "window-change", 0);
2753                 packet_put_int((u_int)ws.ws_col);
2754                 packet_put_int((u_int)ws.ws_row);
2755                 packet_put_int((u_int)ws.ws_xpixel);
2756                 packet_put_int((u_int)ws.ws_ypixel);
2757                 packet_send();
2758         }
2759 }
2760
2761 /* -- X11 forwarding */
2762
2763 /*
2764  * Creates an internet domain socket for listening for X11 connections.
2765  * Returns 0 and a suitable display number for the DISPLAY variable
2766  * stored in display_numberp , or -1 if an error occurs.
2767  */
2768 int
2769 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2770     int single_connection, u_int *display_numberp, int **chanids)
2771 {
2772         Channel *nc = NULL;
2773         int display_number, sock;
2774         u_short port;
2775         struct addrinfo hints, *ai, *aitop;
2776         char strport[NI_MAXSERV];
2777         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2778
2779         if (chanids == NULL)
2780                 return -1;
2781
2782         for (display_number = x11_display_offset;
2783             display_number < MAX_DISPLAYS;
2784             display_number++) {
2785                 port = 6000 + display_number;
2786                 memset(&hints, 0, sizeof(hints));
2787                 hints.ai_family = IPv4or6;
2788                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2789                 hints.ai_socktype = SOCK_STREAM;
2790                 snprintf(strport, sizeof strport, "%d", port);
2791                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2792                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2793                         return -1;
2794                 }
2795                 for (ai = aitop; ai; ai = ai->ai_next) {
2796                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2797                                 continue;
2798                         sock = socket(ai->ai_family, ai->ai_socktype,
2799                             ai->ai_protocol);
2800                         if (sock < 0) {
2801                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2802                                         error("socket: %.100s", strerror(errno));
2803                                         freeaddrinfo(aitop);
2804                                         return -1;
2805                                 } else {
2806                                         debug("x11_create_display_inet: Socket family %d not supported",
2807                                                  ai->ai_family);
2808                                         continue;
2809                                 }
2810                         }
2811 #ifdef IPV6_V6ONLY
2812                         if (ai->ai_family == AF_INET6) {
2813                                 int on = 1;
2814                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2815                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2816                         }
2817 #endif
2818                         channel_set_reuseaddr(sock);
2819                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2820                                 debug2("bind port %d: %.100s", port, strerror(errno));
2821                                 close(sock);
2822
2823                                 if (ai->ai_next)
2824                                         continue;
2825
2826                                 for (n = 0; n < num_socks; n++) {
2827                                         close(socks[n]);
2828                                 }
2829                                 num_socks = 0;
2830                                 break;
2831                         }
2832                         socks[num_socks++] = sock;
2833 #ifndef DONT_TRY_OTHER_AF
2834                         if (num_socks == NUM_SOCKS)
2835                                 break;
2836 #else
2837                         if (x11_use_localhost) {
2838                                 if (num_socks == NUM_SOCKS)
2839                                         break;
2840                         } else {
2841                                 break;
2842                         }
2843 #endif
2844                 }
2845                 freeaddrinfo(aitop);
2846                 if (num_socks > 0)
2847                         break;
2848         }
2849         if (display_number >= MAX_DISPLAYS) {
2850                 error("Failed to allocate internet-domain X11 display socket.");
2851                 return -1;
2852         }
2853         /* Start listening for connections on the socket. */
2854         for (n = 0; n < num_socks; n++) {
2855                 sock = socks[n];
2856                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2857                         error("listen: %.100s", strerror(errno));
2858                         close(sock);
2859                         return -1;
2860                 }
2861         }
2862
2863         /* Allocate a channel for each socket. */
2864         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2865         for (n = 0; n < num_socks; n++) {
2866                 sock = socks[n];
2867                 nc = channel_new("x11 listener",
2868                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2869                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2870                     0, "X11 inet listener", 1);
2871                 nc->single_connection = single_connection;
2872                 (*chanids)[n] = nc->self;
2873         }
2874         (*chanids)[n] = -1;
2875
2876         /* Return the display number for the DISPLAY environment variable. */
2877         *display_numberp = display_number;
2878         return (0);
2879 }
2880
2881 static int
2882 connect_local_xsocket(u_int dnr)
2883 {
2884         int sock;
2885         struct sockaddr_un addr;
2886
2887         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2888         if (sock < 0)
2889                 error("socket: %.100s", strerror(errno));
2890         memset(&addr, 0, sizeof(addr));
2891         addr.sun_family = AF_UNIX;
2892         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2893         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
2894                 return sock;
2895         close(sock);
2896         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2897         return -1;
2898 }
2899
2900 int
2901 x11_connect_display(void)
2902 {
2903         u_int display_number;
2904         const char *display;
2905         char buf[1024], *cp;
2906         struct addrinfo hints, *ai, *aitop;
2907         char strport[NI_MAXSERV];
2908         int gaierr, sock = 0;
2909
2910         /* Try to open a socket for the local X server. */
2911         display = getenv("DISPLAY");
2912         if (!display) {
2913                 error("DISPLAY not set.");
2914                 return -1;
2915         }
2916         /*
2917          * Now we decode the value of the DISPLAY variable and make a
2918          * connection to the real X server.
2919          */
2920
2921         /*
2922          * Check if it is a unix domain socket.  Unix domain displays are in
2923          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2924          */
2925         if (strncmp(display, "unix:", 5) == 0 ||
2926             display[0] == ':') {
2927                 /* Connect to the unix domain socket. */
2928                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
2929                         error("Could not parse display number from DISPLAY: %.100s",
2930                             display);
2931                         return -1;
2932                 }
2933                 /* Create a socket. */
2934                 sock = connect_local_xsocket(display_number);
2935                 if (sock < 0)
2936                         return -1;
2937
2938                 /* OK, we now have a connection to the display. */
2939                 return sock;
2940         }
2941         /*
2942          * Connect to an inet socket.  The DISPLAY value is supposedly
2943          * hostname:d[.s], where hostname may also be numeric IP address.
2944          */
2945         strlcpy(buf, display, sizeof(buf));
2946         cp = strchr(buf, ':');
2947         if (!cp) {
2948                 error("Could not find ':' in DISPLAY: %.100s", display);
2949                 return -1;
2950         }
2951         *cp = 0;
2952         /* buf now contains the host name.  But first we parse the display number. */
2953         if (sscanf(cp + 1, "%u", &display_number) != 1) {
2954                 error("Could not parse display number from DISPLAY: %.100s",
2955                     display);
2956                 return -1;
2957         }
2958
2959         /* Look up the host address */
2960         memset(&hints, 0, sizeof(hints));
2961         hints.ai_family = IPv4or6;
2962         hints.ai_socktype = SOCK_STREAM;
2963         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
2964         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2965                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2966                 return -1;
2967         }
2968         for (ai = aitop; ai; ai = ai->ai_next) {
2969                 /* Create a socket. */
2970                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2971                 if (sock < 0) {
2972                         debug2("socket: %.100s", strerror(errno));
2973                         continue;
2974                 }
2975                 /* Connect it to the display. */
2976                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2977                         debug2("connect %.100s port %u: %.100s", buf,
2978                             6000 + display_number, strerror(errno));
2979                         close(sock);
2980                         continue;
2981                 }
2982                 /* Success */
2983                 break;
2984         }
2985         freeaddrinfo(aitop);
2986         if (!ai) {
2987                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
2988                     strerror(errno));
2989                 return -1;
2990         }
2991         set_nodelay(sock);
2992         return sock;
2993 }
2994
2995 /*
2996  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2997  * the remote channel number.  We should do whatever we want, and respond
2998  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2999  */
3000
3001 void
3002 x11_input_open(int type, u_int32_t seq, void *ctxt)
3003 {
3004         Channel *c = NULL;
3005         int remote_id, sock = 0;
3006         char *remote_host;
3007
3008         debug("Received X11 open request.");
3009
3010         remote_id = packet_get_int();
3011
3012         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3013                 remote_host = packet_get_string(NULL);
3014         } else {
3015                 remote_host = xstrdup("unknown (remote did not supply name)");
3016         }
3017         packet_check_eom();
3018
3019         /* Obtain a connection to the real X display. */
3020         sock = x11_connect_display();
3021         if (sock != -1) {
3022                 /* Allocate a channel for this connection. */
3023                 c = channel_new("connected x11 socket",
3024                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3025                     remote_host, 1);
3026                 c->remote_id = remote_id;
3027                 c->force_drain = 1;
3028         }
3029         xfree(remote_host);
3030         if (c == NULL) {
3031                 /* Send refusal to the remote host. */
3032                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3033                 packet_put_int(remote_id);
3034         } else {
3035                 /* Send a confirmation to the remote host. */
3036                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3037                 packet_put_int(remote_id);
3038                 packet_put_int(c->self);
3039         }
3040         packet_send();
3041 }
3042
3043 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3044 void
3045 deny_input_open(int type, u_int32_t seq, void *ctxt)
3046 {
3047         int rchan = packet_get_int();
3048
3049         switch (type) {
3050         case SSH_SMSG_AGENT_OPEN:
3051                 error("Warning: ssh server tried agent forwarding.");
3052                 break;
3053         case SSH_SMSG_X11_OPEN:
3054                 error("Warning: ssh server tried X11 forwarding.");
3055                 break;
3056         default:
3057                 error("deny_input_open: type %d", type);
3058                 break;
3059         }
3060         error("Warning: this is probably a break-in attempt by a malicious server.");
3061         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3062         packet_put_int(rchan);
3063         packet_send();
3064 }
3065
3066 /*
3067  * Requests forwarding of X11 connections, generates fake authentication
3068  * data, and enables authentication spoofing.
3069  * This should be called in the client only.
3070  */
3071 void
3072 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3073     const char *proto, const char *data)
3074 {
3075         u_int data_len = (u_int) strlen(data) / 2;
3076         u_int i, value;
3077         char *new_data;
3078         int screen_number;
3079         const char *cp;
3080         u_int32_t rnd = 0;
3081
3082         if (x11_saved_display == NULL)
3083                 x11_saved_display = xstrdup(disp);
3084         else if (strcmp(disp, x11_saved_display) != 0) {
3085                 error("x11_request_forwarding_with_spoofing: different "
3086                     "$DISPLAY already forwarded");
3087                 return;
3088         }
3089
3090         cp = disp;
3091         if (disp)
3092                 cp = strchr(disp, ':');
3093         if (cp)
3094                 cp = strchr(cp, '.');
3095         if (cp)
3096                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3097         else
3098                 screen_number = 0;
3099
3100         if (x11_saved_proto == NULL) {
3101                 /* Save protocol name. */
3102                 x11_saved_proto = xstrdup(proto);
3103                 /*
3104                  * Extract real authentication data and generate fake data
3105                  * of the same length.
3106                  */
3107                 x11_saved_data = xmalloc(data_len);
3108                 x11_fake_data = xmalloc(data_len);
3109                 for (i = 0; i < data_len; i++) {
3110                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3111                                 fatal("x11_request_forwarding: bad "
3112                                     "authentication data: %.100s", data);
3113                         if (i % 4 == 0)
3114                                 rnd = arc4random();
3115                         x11_saved_data[i] = value;
3116                         x11_fake_data[i] = rnd & 0xff;
3117                         rnd >>= 8;
3118                 }
3119                 x11_saved_data_len = data_len;
3120                 x11_fake_data_len = data_len;
3121         }
3122
3123         /* Convert the fake data into hex. */
3124         new_data = tohex(x11_fake_data, data_len);
3125
3126         /* Send the request packet. */
3127         if (compat20) {
3128                 channel_request_start(client_session_id, "x11-req", 0);
3129                 packet_put_char(0);     /* XXX bool single connection */
3130         } else {
3131                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3132         }
3133         packet_put_cstring(proto);
3134         packet_put_cstring(new_data);
3135         packet_put_int(screen_number);
3136         packet_send();
3137         packet_write_wait();
3138         xfree(new_data);
3139 }
3140
3141
3142 /* -- agent forwarding */
3143
3144 /* Sends a message to the server to request authentication fd forwarding. */
3145
3146 void
3147 auth_request_forwarding(void)
3148 {
3149         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3150         packet_send();
3151         packet_write_wait();
3152 }