channels.c

   1 /* $OpenBSD: channels.c,v 1.244 2006/03/25 13:17:01 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         /* check buffer limits */
 751         limit = MIN(limit, (BUFFER_MAX_LEN - BUFFER_MAX_CHUNK - CHAN_RBUF));
 752
 753         if (c->istate == CHAN_INPUT_OPEN &&
 754             limit > 0 &&
 755             buffer_len(&c->input) < limit)
 756                 FD_SET(c->rfd, readset);
 757         if (c->ostate == CHAN_OUTPUT_OPEN ||
 758             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 759                 if (buffer_len(&c->output) > 0) {
 760                         FD_SET(c->wfd, writeset);
 761                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 762                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 763                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 764                                     c->self, c->efd, buffer_len(&c->extended));
 765                         else
 766                                 chan_obuf_empty(c);
 767                 }
 768         }
 769         /** XXX check close conditions, too */
 770         if (compat20 && c->efd != -1) {
 771                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 772                     buffer_len(&c->extended) > 0)
 773                         FD_SET(c->efd, writeset);
 774                 else if (!(c->flags & CHAN_EOF_SENT) &&
 775                     c->extended_usage == CHAN_EXTENDED_READ &&
 776                     buffer_len(&c->extended) < c->remote_window)
 777                         FD_SET(c->efd, readset);
 778         }
 779         /* XXX: What about efd? races? */
 780         if (compat20 && c->ctl_fd != -1 &&
 781             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 782                 FD_SET(c->ctl_fd, readset);
 783 }
 784
 785 static void
 786 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 787 {
 788         if (buffer_len(&c->input) == 0) {
 789                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 790                 packet_put_int(c->remote_id);
 791                 packet_send();
 792                 c->type = SSH_CHANNEL_CLOSED;
 793                 debug2("channel %d: closing after input drain.", c->self);
 794         }
 795 }
 796
 797 static void
 798 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 799 {
 800         if (buffer_len(&c->output) == 0)
 801                 chan_mark_dead(c);
 802         else
 803                 FD_SET(c->sock, writeset);
 804 }
 805
 806 /*
 807  * This is a special state for X11 authentication spoofing.  An opened X11
 808  * connection (when authentication spoofing is being done) remains in this
 809  * state until the first packet has been completely read.  The authentication
 810  * data in that packet is then substituted by the real data if it matches the
 811  * fake data, and the channel is put into normal mode.
 812  * XXX All this happens at the client side.
 813  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 814  */
 815 static int
 816 x11_open_helper(Buffer *b)
 817 {
 818         u_char *ucp;
 819         u_int proto_len, data_len;
 820
 821         /* Check if the fixed size part of the packet is in buffer. */
 822         if (buffer_len(b) < 12)
 823                 return 0;
 824
 825         /* Parse the lengths of variable-length fields. */
 826         ucp = buffer_ptr(b);
 827         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 828                 proto_len = 256 * ucp[6] + ucp[7];
 829                 data_len = 256 * ucp[8] + ucp[9];
 830         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 831                 proto_len = ucp[6] + 256 * ucp[7];
 832                 data_len = ucp[8] + 256 * ucp[9];
 833         } else {
 834                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 835                     ucp[0]);
 836                 return -1;
 837         }
 838
 839         /* Check if the whole packet is in buffer. */
 840         if (buffer_len(b) <
 841             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 842                 return 0;
 843
 844         /* Check if authentication protocol matches. */
 845         if (proto_len != strlen(x11_saved_proto) ||
 846             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 847                 debug2("X11 connection uses different authentication protocol.");
 848                 return -1;
 849         }
 850         /* Check if authentication data matches our fake data. */
 851         if (data_len != x11_fake_data_len ||
 852             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 853                 x11_fake_data, x11_fake_data_len) != 0) {
 854                 debug2("X11 auth data does not match fake data.");
 855                 return -1;
 856         }
 857         /* Check fake data length */
 858         if (x11_fake_data_len != x11_saved_data_len) {
 859                 error("X11 fake_data_len %d != saved_data_len %d",
 860                     x11_fake_data_len, x11_saved_data_len);
 861                 return -1;
 862         }
 863         /*
 864          * Received authentication protocol and data match
 865          * our fake data. Substitute the fake data with real
 866          * data.
 867          */
 868         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 869             x11_saved_data, x11_saved_data_len);
 870         return 1;
 871 }
 872
 873 static void
 874 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 875 {
 876         int ret = x11_open_helper(&c->output);
 877
 878         if (ret == 1) {
 879                 /* Start normal processing for the channel. */
 880                 c->type = SSH_CHANNEL_OPEN;
 881                 channel_pre_open_13(c, readset, writeset);
 882         } else if (ret == -1) {
 883                 /*
 884                  * We have received an X11 connection that has bad
 885                  * authentication information.
 886                  */
 887                 logit("X11 connection rejected because of wrong authentication.");
 888                 buffer_clear(&c->input);
 889                 buffer_clear(&c->output);
 890                 channel_close_fd(&c->sock);
 891                 c->sock = -1;
 892                 c->type = SSH_CHANNEL_CLOSED;
 893                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 894                 packet_put_int(c->remote_id);
 895                 packet_send();
 896         }
 897 }
 898
 899 static void
 900 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 901 {
 902         int ret = x11_open_helper(&c->output);
 903
 904         /* c->force_drain = 1; */
 905
 906         if (ret == 1) {
 907                 c->type = SSH_CHANNEL_OPEN;
 908                 channel_pre_open(c, readset, writeset);
 909         } else if (ret == -1) {
 910                 logit("X11 connection rejected because of wrong authentication.");
 911                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 912                 chan_read_failed(c);
 913                 buffer_clear(&c->input);
 914                 chan_ibuf_empty(c);
 915                 buffer_clear(&c->output);
 916                 /* for proto v1, the peer will send an IEOF */
 917                 if (compat20)
 918                         chan_write_failed(c);
 919                 else
 920                         c->type = SSH_CHANNEL_OPEN;
 921                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 922         }
 923 }
 924
 925 /* try to decode a socks4 header */
 926 static int
 927 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 928 {
 929         char *p, *host;
 930         u_int len, have, i, found;
 931         char username[256];
 932         struct {
 933                 u_int8_t version;
 934                 u_int8_t command;
 935                 u_int16_t dest_port;
 936                 struct in_addr dest_addr;
 937         } s4_req, s4_rsp;
 938
 939         debug2("channel %d: decode socks4", c->self);
 940
 941         have = buffer_len(&c->input);
 942         len = sizeof(s4_req);
 943         if (have < len)
 944                 return 0;
 945         p = buffer_ptr(&c->input);
 946         for (found = 0, i = len; i < have; i++) {
 947                 if (p[i] == '\0') {
 948                         found = 1;
 949                         break;
 950                 }
 951                 if (i > 1024) {
 952                         /* the peer is probably sending garbage */
 953                         debug("channel %d: decode socks4: too long",
 954                             c->self);
 955                         return -1;
 956                 }
 957         }
 958         if (!found)
 959                 return 0;
 960         buffer_get(&c->input, (char *)&s4_req.version, 1);
 961         buffer_get(&c->input, (char *)&s4_req.command, 1);
 962         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 963         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 964         have = buffer_len(&c->input);
 965         p = buffer_ptr(&c->input);
 966         len = strlen(p);
 967         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 968         if (len > have)
 969                 fatal("channel %d: decode socks4: len %d > have %d",
 970                     c->self, len, have);
 971         strlcpy(username, p, sizeof(username));
 972         buffer_consume(&c->input, len);
 973         buffer_consume(&c->input, 1);           /* trailing '\0' */
 974
 975         host = inet_ntoa(s4_req.dest_addr);
 976         strlcpy(c->path, host, sizeof(c->path));
 977         c->host_port = ntohs(s4_req.dest_port);
 978
 979         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 980             c->self, host, c->host_port, s4_req.command);
 981
 982         if (s4_req.command != 1) {
 983                 debug("channel %d: cannot handle: socks4 cn %d",
 984                     c->self, s4_req.command);
 985                 return -1;
 986         }
 987         s4_rsp.version = 0;                     /* vn: 0 for reply */
 988         s4_rsp.command = 90;                    /* cd: req granted */
 989         s4_rsp.dest_port = 0;                   /* ignored */
 990         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 991         buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
 992         return 1;
 993 }
 994
 995 /* try to decode a socks5 header */
 996 #define SSH_SOCKS5_AUTHDONE     0x1000
 997 #define SSH_SOCKS5_NOAUTH       0x00
 998 #define SSH_SOCKS5_IPV4         0x01
 999 #define SSH_SOCKS5_DOMAIN       0x03
1000 #define SSH_SOCKS5_IPV6         0x04
1001 #define SSH_SOCKS5_CONNECT      0x01
1002 #define SSH_SOCKS5_SUCCESS      0x00
1003
1004 static int
1005 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1006 {
1007         struct {
1008                 u_int8_t version;
1009                 u_int8_t command;
1010                 u_int8_t reserved;
1011                 u_int8_t atyp;
1012         } s5_req, s5_rsp;
1013         u_int16_t dest_port;
1014         u_char *p, dest_addr[255+1];
1015         u_int have, i, found, nmethods, addrlen, af;
1016
1017         debug2("channel %d: decode socks5", c->self);
1018         p = buffer_ptr(&c->input);
1019         if (p[0] != 0x05)
1020                 return -1;
1021         have = buffer_len(&c->input);
1022         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1023                 /* format: ver | nmethods | methods */
1024                 if (have < 2)
1025                         return 0;
1026                 nmethods = p[1];
1027                 if (have < nmethods + 2)
1028                         return 0;
1029                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1030                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1031                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
1032                                 found = 1;
1033                                 break;
1034                         }
1035                 }
1036                 if (!found) {
1037                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1038                             c->self);
1039                         return -1;
1040                 }
1041                 buffer_consume(&c->input, nmethods + 2);
1042                 buffer_put_char(&c->output, 0x05);              /* version */
1043                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1044                 FD_SET(c->sock, writeset);
1045                 c->flags |= SSH_SOCKS5_AUTHDONE;
1046                 debug2("channel %d: socks5 auth done", c->self);
1047                 return 0;                               /* need more */
1048         }
1049         debug2("channel %d: socks5 post auth", c->self);
1050         if (have < sizeof(s5_req)+1)
1051                 return 0;                       /* need more */
1052         memcpy((char *)&s5_req, p, sizeof(s5_req));
1053         if (s5_req.version != 0x05 ||
1054             s5_req.command != SSH_SOCKS5_CONNECT ||
1055             s5_req.reserved != 0x00) {
1056                 debug2("channel %d: only socks5 connect supported", c->self);
1057                 return -1;
1058         }
1059         switch (s5_req.atyp){
1060         case SSH_SOCKS5_IPV4:
1061                 addrlen = 4;
1062                 af = AF_INET;
1063                 break;
1064         case SSH_SOCKS5_DOMAIN:
1065                 addrlen = p[sizeof(s5_req)];
1066                 af = -1;
1067                 break;
1068         case SSH_SOCKS5_IPV6:
1069                 addrlen = 16;
1070                 af = AF_INET6;
1071                 break;
1072         default:
1073                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1074                 return -1;
1075         }
1076         if (have < 4 + addrlen + 2)
1077                 return 0;
1078         buffer_consume(&c->input, sizeof(s5_req));
1079         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1080                 buffer_consume(&c->input, 1);    /* host string length */
1081         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1082         buffer_get(&c->input, (char *)&dest_port, 2);
1083         dest_addr[addrlen] = '\0';
1084         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1085                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1086         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1087                 return -1;
1088         c->host_port = ntohs(dest_port);
1089
1090         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1091             c->self, c->path, c->host_port, s5_req.command);
1092
1093         s5_rsp.version = 0x05;
1094         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1095         s5_rsp.reserved = 0;                    /* ignored */
1096         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1097         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1098         dest_port = 0;                          /* ignored */
1099
1100         buffer_append(&c->output, (char *)&s5_rsp, sizeof(s5_rsp));
1101         buffer_append(&c->output, (char *)&dest_addr, sizeof(struct in_addr));
1102         buffer_append(&c->output, (char *)&dest_port, sizeof(dest_port));
1103         return 1;
1104 }
1105
1106 /* dynamic port forwarding */
1107 static void
1108 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1109 {
1110         u_char *p;
1111         u_int have;
1112         int ret;
1113
1114         have = buffer_len(&c->input);
1115         c->delayed = 0;
1116         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1117         /* buffer_dump(&c->input); */
1118         /* check if the fixed size part of the packet is in buffer. */
1119         if (have < 3) {
1120                 /* need more */
1121                 FD_SET(c->sock, readset);
1122                 return;
1123         }
1124         /* try to guess the protocol */
1125         p = buffer_ptr(&c->input);
1126         switch (p[0]) {
1127         case 0x04:
1128                 ret = channel_decode_socks4(c, readset, writeset);
1129                 break;
1130         case 0x05:
1131                 ret = channel_decode_socks5(c, readset, writeset);
1132                 break;
1133         default:
1134                 ret = -1;
1135                 break;
1136         }
1137         if (ret < 0) {
1138                 chan_mark_dead(c);
1139         } else if (ret == 0) {
1140                 debug2("channel %d: pre_dynamic: need more", c->self);
1141                 /* need more */
1142                 FD_SET(c->sock, readset);
1143         } else {
1144                 /* switch to the next state */
1145                 c->type = SSH_CHANNEL_OPENING;
1146                 port_open_helper(c, "direct-tcpip");
1147         }
1148 }
1149
1150 /* This is our fake X11 server socket. */
1151 static void
1152 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1153 {
1154         Channel *nc;
1155         struct sockaddr addr;
1156         int newsock;
1157         socklen_t addrlen;
1158         char buf[16384], *remote_ipaddr;
1159         int remote_port;
1160
1161         if (FD_ISSET(c->sock, readset)) {
1162                 debug("X11 connection requested.");
1163                 addrlen = sizeof(addr);
1164                 newsock = accept(c->sock, &addr, &addrlen);
1165                 if (c->single_connection) {
1166                         debug2("single_connection: closing X11 listener.");
1167                         channel_close_fd(&c->sock);
1168                         chan_mark_dead(c);
1169                 }
1170                 if (newsock < 0) {
1171                         error("accept: %.100s", strerror(errno));
1172                         return;
1173                 }
1174                 set_nodelay(newsock);
1175                 remote_ipaddr = get_peer_ipaddr(newsock);
1176                 remote_port = get_peer_port(newsock);
1177                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1178                     remote_ipaddr, remote_port);
1179
1180                 nc = channel_new("accepted x11 socket",
1181                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1182                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1183                 if (compat20) {
1184                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1185                         packet_put_cstring("x11");
1186                         packet_put_int(nc->self);
1187                         packet_put_int(nc->local_window_max);
1188                         packet_put_int(nc->local_maxpacket);
1189                         /* originator ipaddr and port */
1190                         packet_put_cstring(remote_ipaddr);
1191                         if (datafellows & SSH_BUG_X11FWD) {
1192                                 debug2("ssh2 x11 bug compat mode");
1193                         } else {
1194                                 packet_put_int(remote_port);
1195                         }
1196                         packet_send();
1197                 } else {
1198                         packet_start(SSH_SMSG_X11_OPEN);
1199                         packet_put_int(nc->self);
1200                         if (packet_get_protocol_flags() &
1201                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1202                                 packet_put_cstring(buf);
1203                         packet_send();
1204                 }
1205                 xfree(remote_ipaddr);
1206         }
1207 }
1208
1209 static void
1210 port_open_helper(Channel *c, char *rtype)
1211 {
1212         int direct;
1213         char buf[1024];
1214         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1215         int remote_port = get_peer_port(c->sock);
1216
1217         direct = (strcmp(rtype, "direct-tcpip") == 0);
1218
1219         snprintf(buf, sizeof buf,
1220             "%s: listening port %d for %.100s port %d, "
1221             "connect from %.200s port %d",
1222             rtype, c->listening_port, c->path, c->host_port,
1223             remote_ipaddr, remote_port);
1224
1225         xfree(c->remote_name);
1226         c->remote_name = xstrdup(buf);
1227
1228         if (compat20) {
1229                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1230                 packet_put_cstring(rtype);
1231                 packet_put_int(c->self);
1232                 packet_put_int(c->local_window_max);
1233                 packet_put_int(c->local_maxpacket);
1234                 if (direct) {
1235                         /* target host, port */
1236                         packet_put_cstring(c->path);
1237                         packet_put_int(c->host_port);
1238                 } else {
1239                         /* listen address, port */
1240                         packet_put_cstring(c->path);
1241                         packet_put_int(c->listening_port);
1242                 }
1243                 /* originator host and port */
1244                 packet_put_cstring(remote_ipaddr);
1245                 packet_put_int((u_int)remote_port);
1246                 packet_send();
1247         } else {
1248                 packet_start(SSH_MSG_PORT_OPEN);
1249                 packet_put_int(c->self);
1250                 packet_put_cstring(c->path);
1251                 packet_put_int(c->host_port);
1252                 if (packet_get_protocol_flags() &
1253                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1254                         packet_put_cstring(c->remote_name);
1255                 packet_send();
1256         }
1257         xfree(remote_ipaddr);
1258 }
1259
1260 static void
1261 channel_set_reuseaddr(int fd)
1262 {
1263         int on = 1;
1264
1265         /*
1266          * Set socket options.
1267          * Allow local port reuse in TIME_WAIT.
1268          */
1269         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1270                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1271 }
1272
1273 /*
1274  * This socket is listening for connections to a forwarded TCP/IP port.
1275  */
1276 static void
1277 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1278 {
1279         Channel *nc;
1280         struct sockaddr addr;
1281         int newsock, nextstate;
1282         socklen_t addrlen;
1283         char *rtype;
1284
1285         if (FD_ISSET(c->sock, readset)) {
1286                 debug("Connection to port %d forwarding "
1287                     "to %.100s port %d requested.",
1288                     c->listening_port, c->path, c->host_port);
1289
1290                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1291                         nextstate = SSH_CHANNEL_OPENING;
1292                         rtype = "forwarded-tcpip";
1293                 } else {
1294                         if (c->host_port == 0) {
1295                                 nextstate = SSH_CHANNEL_DYNAMIC;
1296                                 rtype = "dynamic-tcpip";
1297                         } else {
1298                                 nextstate = SSH_CHANNEL_OPENING;
1299                                 rtype = "direct-tcpip";
1300                         }
1301                 }
1302
1303                 addrlen = sizeof(addr);
1304                 newsock = accept(c->sock, &addr, &addrlen);
1305                 if (newsock < 0) {
1306                         error("accept: %.100s", strerror(errno));
1307                         return;
1308                 }
1309                 set_nodelay(newsock);
1310                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1311                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1312                 nc->listening_port = c->listening_port;
1313                 nc->host_port = c->host_port;
1314                 strlcpy(nc->path, c->path, sizeof(nc->path));
1315
1316                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1317                         /*
1318                          * do not call the channel_post handler until
1319                          * this flag has been reset by a pre-handler.
1320                          * otherwise the FD_ISSET calls might overflow
1321                          */
1322                         nc->delayed = 1;
1323                 } else {
1324                         port_open_helper(nc, rtype);
1325                 }
1326         }
1327 }
1328
1329 /*
1330  * This is the authentication agent socket listening for connections from
1331  * clients.
1332  */
1333 static void
1334 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1335 {
1336         Channel *nc;
1337         int newsock;
1338         struct sockaddr addr;
1339         socklen_t addrlen;
1340
1341         if (FD_ISSET(c->sock, readset)) {
1342                 addrlen = sizeof(addr);
1343                 newsock = accept(c->sock, &addr, &addrlen);
1344                 if (newsock < 0) {
1345                         error("accept from auth socket: %.100s", strerror(errno));
1346                         return;
1347                 }
1348                 nc = channel_new("accepted auth socket",
1349                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1350                     c->local_window_max, c->local_maxpacket,
1351                     0, "accepted auth socket", 1);
1352                 if (compat20) {
1353                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1354                         packet_put_cstring("auth-agent@openssh.com");
1355                         packet_put_int(nc->self);
1356                         packet_put_int(c->local_window_max);
1357                         packet_put_int(c->local_maxpacket);
1358                 } else {
1359                         packet_start(SSH_SMSG_AGENT_OPEN);
1360                         packet_put_int(nc->self);
1361                 }
1362                 packet_send();
1363         }
1364 }
1365
1366 static void
1367 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1368 {
1369         int err = 0;
1370         socklen_t sz = sizeof(err);
1371
1372         if (FD_ISSET(c->sock, writeset)) {
1373                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1374                         err = errno;
1375                         error("getsockopt SO_ERROR failed");
1376                 }
1377                 if (err == 0) {
1378                         debug("channel %d: connected", c->self);
1379                         c->type = SSH_CHANNEL_OPEN;
1380                         if (compat20) {
1381                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1382                                 packet_put_int(c->remote_id);
1383                                 packet_put_int(c->self);
1384                                 packet_put_int(c->local_window);
1385                                 packet_put_int(c->local_maxpacket);
1386                         } else {
1387                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1388                                 packet_put_int(c->remote_id);
1389                                 packet_put_int(c->self);
1390                         }
1391                 } else {
1392                         debug("channel %d: not connected: %s",
1393                             c->self, strerror(err));
1394                         if (compat20) {
1395                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1396                                 packet_put_int(c->remote_id);
1397                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1398                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1399                                         packet_put_cstring(strerror(err));
1400                                         packet_put_cstring("");
1401                                 }
1402                         } else {
1403                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1404                                 packet_put_int(c->remote_id);
1405                         }
1406                         chan_mark_dead(c);
1407                 }
1408                 packet_send();
1409         }
1410 }
1411
1412 static int
1413 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1414 {
1415         char buf[CHAN_RBUF];
1416         int len;
1417
1418         if (c->rfd != -1 &&
1419             FD_ISSET(c->rfd, readset)) {
1420                 len = read(c->rfd, buf, sizeof(buf));
1421                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1422                         return 1;
1423                 if (len <= 0) {
1424                         debug2("channel %d: read<=0 rfd %d len %d",
1425                             c->self, c->rfd, len);
1426                         if (c->type != SSH_CHANNEL_OPEN) {
1427                                 debug2("channel %d: not open", c->self);
1428                                 chan_mark_dead(c);
1429                                 return -1;
1430                         } else if (compat13) {
1431                                 buffer_clear(&c->output);
1432                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1433                                 debug2("channel %d: input draining.", c->self);
1434                         } else {
1435                                 chan_read_failed(c);
1436                         }
1437                         return -1;
1438                 }
1439                 if (c->input_filter != NULL) {
1440                         if (c->input_filter(c, buf, len) == -1) {
1441                                 debug2("channel %d: filter stops", c->self);
1442                                 chan_read_failed(c);
1443                         }
1444                 } else if (c->datagram) {
1445                         buffer_put_string(&c->input, buf, len);
1446                 } else {
1447                         buffer_append(&c->input, buf, len);
1448                 }
1449         }
1450         return 1;
1451 }
1452
1453 static int
1454 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1455 {
1456         struct termios tio;
1457         u_char *data = NULL, *buf;
1458         u_int dlen;
1459         int len;
1460
1461         /* Send buffered output data to the socket. */
1462         if (c->wfd != -1 &&
1463             FD_ISSET(c->wfd, writeset) &&
1464             buffer_len(&c->output) > 0) {
1465                 if (c->output_filter != NULL) {
1466                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1467                                 debug2("channel %d: filter stops", c->self);
1468                                 if (c->type != SSH_CHANNEL_OPEN)
1469                                         chan_mark_dead(c);
1470                                 else
1471                                         chan_write_failed(c);
1472                                 return -1;
1473                         }
1474                 } else if (c->datagram) {
1475                         buf = data = buffer_get_string(&c->output, &dlen);
1476                 } else {
1477                         buf = data = buffer_ptr(&c->output);
1478                         dlen = buffer_len(&c->output);
1479                 }
1480
1481                 if (c->datagram) {
1482                         /* ignore truncated writes, datagrams might get lost */
1483                         c->local_consumed += dlen + 4;
1484                         len = write(c->wfd, buf, dlen);
1485                         xfree(data);
1486                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1487                                 return 1;
1488                         if (len <= 0) {
1489                                 if (c->type != SSH_CHANNEL_OPEN)
1490                                         chan_mark_dead(c);
1491                                 else
1492                                         chan_write_failed(c);
1493                                 return -1;
1494                         }
1495                         return 1;
1496                 }
1497 #ifdef _AIX
1498                 /* XXX: Later AIX versions can't push as much data to tty */
1499                 if (compat20 && c->wfd_isatty)
1500                         dlen = MIN(dlen, 8*1024);
1501 #endif
1502
1503                 len = write(c->wfd, buf, dlen);
1504                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1505                         return 1;
1506                 if (len <= 0) {
1507                         if (c->type != SSH_CHANNEL_OPEN) {
1508                                 debug2("channel %d: not open", c->self);
1509                                 chan_mark_dead(c);
1510                                 return -1;
1511                         } else if (compat13) {
1512                                 buffer_clear(&c->output);
1513                                 debug2("channel %d: input draining.", c->self);
1514                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1515                         } else {
1516                                 chan_write_failed(c);
1517                         }
1518                         return -1;
1519                 }
1520                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1521                         if (tcgetattr(c->wfd, &tio) == 0 &&
1522                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1523                                 /*
1524                                  * Simulate echo to reduce the impact of
1525                                  * traffic analysis. We need to match the
1526                                  * size of a SSH2_MSG_CHANNEL_DATA message
1527                                  * (4 byte channel id + buf)
1528                                  */
1529                                 packet_send_ignore(4 + len);
1530                                 packet_send();
1531                         }
1532                 }
1533                 buffer_consume(&c->output, len);
1534                 if (compat20 && len > 0) {
1535                         c->local_consumed += len;
1536                 }
1537         }
1538         return 1;
1539 }
1540
1541 static int
1542 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1543 {
1544         char buf[CHAN_RBUF];
1545         int len;
1546
1547 /** XXX handle drain efd, too */
1548         if (c->efd != -1) {
1549                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1550                     FD_ISSET(c->efd, writeset) &&
1551                     buffer_len(&c->extended) > 0) {
1552                         len = write(c->efd, buffer_ptr(&c->extended),
1553                             buffer_len(&c->extended));
1554                         debug2("channel %d: written %d to efd %d",
1555                             c->self, len, c->efd);
1556                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1557                                 return 1;
1558                         if (len <= 0) {
1559                                 debug2("channel %d: closing write-efd %d",
1560                                     c->self, c->efd);
1561                                 channel_close_fd(&c->efd);
1562                         } else {
1563                                 buffer_consume(&c->extended, len);
1564                                 c->local_consumed += len;
1565                         }
1566                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1567                     FD_ISSET(c->efd, readset)) {
1568                         len = read(c->efd, buf, sizeof(buf));
1569                         debug2("channel %d: read %d from efd %d",
1570                             c->self, len, c->efd);
1571                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1572                                 return 1;
1573                         if (len <= 0) {
1574                                 debug2("channel %d: closing read-efd %d",
1575                                     c->self, c->efd);
1576                                 channel_close_fd(&c->efd);
1577                         } else {
1578                                 buffer_append(&c->extended, buf, len);
1579                         }
1580                 }
1581         }
1582         return 1;
1583 }
1584
1585 static int
1586 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1587 {
1588         char buf[16];
1589         int len;
1590
1591         /* Monitor control fd to detect if the slave client exits */
1592         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1593                 len = read(c->ctl_fd, buf, sizeof(buf));
1594                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1595                         return 1;
1596                 if (len <= 0) {
1597                         debug2("channel %d: ctl read<=0", c->self);
1598                         if (c->type != SSH_CHANNEL_OPEN) {
1599                                 debug2("channel %d: not open", c->self);
1600                                 chan_mark_dead(c);
1601                                 return -1;
1602                         } else {
1603                                 chan_read_failed(c);
1604                                 chan_write_failed(c);
1605                         }
1606                         return -1;
1607                 } else
1608                         fatal("%s: unexpected data on ctl fd", __func__);
1609         }
1610         return 1;
1611 }
1612
1613 static int
1614 channel_check_window(Channel *c)
1615 {
1616         if (c->type == SSH_CHANNEL_OPEN &&
1617             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1618             c->local_window < c->local_window_max/2 &&
1619             c->local_consumed > 0) {
1620                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1621                 packet_put_int(c->remote_id);
1622                 packet_put_int(c->local_consumed);
1623                 packet_send();
1624                 debug2("channel %d: window %d sent adjust %d",
1625                     c->self, c->local_window,
1626                     c->local_consumed);
1627                 c->local_window += c->local_consumed;
1628                 c->local_consumed = 0;
1629         }
1630         return 1;
1631 }
1632
1633 static void
1634 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1635 {
1636         if (c->delayed)
1637                 return;
1638         channel_handle_rfd(c, readset, writeset);
1639         channel_handle_wfd(c, readset, writeset);
1640         if (!compat20)
1641                 return;
1642         channel_handle_efd(c, readset, writeset);
1643         channel_handle_ctl(c, readset, writeset);
1644         channel_check_window(c);
1645 }
1646
1647 static void
1648 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1649 {
1650         int len;
1651
1652         /* Send buffered output data to the socket. */
1653         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1654                 len = write(c->sock, buffer_ptr(&c->output),
1655                             buffer_len(&c->output));
1656                 if (len <= 0)
1657                         buffer_clear(&c->output);
1658                 else
1659                         buffer_consume(&c->output, len);
1660         }
1661 }
1662
1663 static void
1664 channel_handler_init_20(void)
1665 {
1666         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1667         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1668         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1669         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1670         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1671         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1672         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1673         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1674
1675         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1676         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1677         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1678         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1679         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1680         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1681         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1682 }
1683
1684 static void
1685 channel_handler_init_13(void)
1686 {
1687         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1688         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1689         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1690         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1691         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1692         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1693         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1694         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1695         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1696
1697         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1698         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1699         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1700         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1701         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1702         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1703         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1704 }
1705
1706 static void
1707 channel_handler_init_15(void)
1708 {
1709         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1710         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1711         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1712         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1713         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1714         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1715         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1716
1717         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1718         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1719         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1720         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1721         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1722         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1723 }
1724
1725 static void
1726 channel_handler_init(void)
1727 {
1728         int i;
1729
1730         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1731                 channel_pre[i] = NULL;
1732                 channel_post[i] = NULL;
1733         }
1734         if (compat20)
1735                 channel_handler_init_20();
1736         else if (compat13)
1737                 channel_handler_init_13();
1738         else
1739                 channel_handler_init_15();
1740 }
1741
1742 /* gc dead channels */
1743 static void
1744 channel_garbage_collect(Channel *c)
1745 {
1746         if (c == NULL)
1747                 return;
1748         if (c->detach_user != NULL) {
1749                 if (!chan_is_dead(c, c->detach_close))
1750                         return;
1751                 debug2("channel %d: gc: notify user", c->self);
1752                 c->detach_user(c->self, NULL);
1753                 /* if we still have a callback */
1754                 if (c->detach_user != NULL)
1755                         return;
1756                 debug2("channel %d: gc: user detached", c->self);
1757         }
1758         if (!chan_is_dead(c, 1))
1759                 return;
1760         debug2("channel %d: garbage collecting", c->self);
1761         channel_free(c);
1762 }
1763
1764 static void
1765 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1766 {
1767         static int did_init = 0;
1768         u_int i;
1769         Channel *c;
1770
1771         if (!did_init) {
1772                 channel_handler_init();
1773                 did_init = 1;
1774         }
1775         for (i = 0; i < channels_alloc; i++) {
1776                 c = channels[i];
1777                 if (c == NULL)
1778                         continue;
1779                 if (ftab[c->type] != NULL)
1780                         (*ftab[c->type])(c, readset, writeset);
1781                 channel_garbage_collect(c);
1782         }
1783 }
1784
1785 /*
1786  * Allocate/update select bitmasks and add any bits relevant to channels in
1787  * select bitmasks.
1788  */
1789 void
1790 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1791     u_int *nallocp, int rekeying)
1792 {
1793         u_int n, sz, nfdset;
1794
1795         n = MAX(*maxfdp, channel_max_fd);
1796
1797         nfdset = howmany(n+1, NFDBITS);
1798         /* Explicitly test here, because xrealloc isn't always called */
1799         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1800                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1801         sz = nfdset * sizeof(fd_mask);
1802
1803         /* perhaps check sz < nalloc/2 and shrink? */
1804         if (*readsetp == NULL || sz > *nallocp) {
1805                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1806                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1807                 *nallocp = sz;
1808         }
1809         *maxfdp = n;
1810         memset(*readsetp, 0, sz);
1811         memset(*writesetp, 0, sz);
1812
1813         if (!rekeying)
1814                 channel_handler(channel_pre, *readsetp, *writesetp);
1815 }
1816
1817 /*
1818  * After select, perform any appropriate operations for channels which have
1819  * events pending.
1820  */
1821 void
1822 channel_after_select(fd_set *readset, fd_set *writeset)
1823 {
1824         channel_handler(channel_post, readset, writeset);
1825 }
1826
1827
1828 /* If there is data to send to the connection, enqueue some of it now. */
1829 void
1830 channel_output_poll(void)
1831 {
1832         Channel *c;
1833         u_int i, len;
1834
1835         for (i = 0; i < channels_alloc; i++) {
1836                 c = channels[i];
1837                 if (c == NULL)
1838                         continue;
1839
1840                 /*
1841                  * We are only interested in channels that can have buffered
1842                  * incoming data.
1843                  */
1844                 if (compat13) {
1845                         if (c->type != SSH_CHANNEL_OPEN &&
1846                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1847                                 continue;
1848                 } else {
1849                         if (c->type != SSH_CHANNEL_OPEN)
1850                                 continue;
1851                 }
1852                 if (compat20 &&
1853                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1854                         /* XXX is this true? */
1855                         debug3("channel %d: will not send data after close", c->self);
1856                         continue;
1857                 }
1858
1859                 /* Get the amount of buffered data for this channel. */
1860                 if ((c->istate == CHAN_INPUT_OPEN ||
1861                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1862                     (len = buffer_len(&c->input)) > 0) {
1863                         if (c->datagram) {
1864                                 if (len > 0) {
1865                                         u_char *data;
1866                                         u_int dlen;
1867
1868                                         data = buffer_get_string(&c->input,
1869                                             &dlen);
1870                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1871                                         packet_put_int(c->remote_id);
1872                                         packet_put_string(data, dlen);
1873                                         packet_send();
1874                                         c->remote_window -= dlen + 4;
1875                                         xfree(data);
1876                                 }
1877                                 continue;
1878                         }
1879                         /*
1880                          * Send some data for the other side over the secure
1881                          * connection.
1882                          */
1883                         if (compat20) {
1884                                 if (len > c->remote_window)
1885                                         len = c->remote_window;
1886                                 if (len > c->remote_maxpacket)
1887                                         len = c->remote_maxpacket;
1888                         } else {
1889                                 if (packet_is_interactive()) {
1890                                         if (len > 1024)
1891                                                 len = 512;
1892                                 } else {
1893                                         /* Keep the packets at reasonable size. */
1894                                         if (len > packet_get_maxsize()/2)
1895                                                 len = packet_get_maxsize()/2;
1896                                 }
1897                         }
1898                         if (len > 0) {
1899                                 packet_start(compat20 ?
1900                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1901                                 packet_put_int(c->remote_id);
1902                                 packet_put_string(buffer_ptr(&c->input), len);
1903                                 packet_send();
1904                                 buffer_consume(&c->input, len);
1905                                 c->remote_window -= len;
1906                         }
1907                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1908                         if (compat13)
1909                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1910                         /*
1911                          * input-buffer is empty and read-socket shutdown:
1912                          * tell peer, that we will not send more data: send IEOF.
1913                          * hack for extended data: delay EOF if EFD still in use.
1914                          */
1915                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1916                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1917                                     c->self, c->efd, buffer_len(&c->extended));
1918                         else
1919                                 chan_ibuf_empty(c);
1920                 }
1921                 /* Send extended data, i.e. stderr */
1922                 if (compat20 &&
1923                     !(c->flags & CHAN_EOF_SENT) &&
1924                     c->remote_window > 0 &&
1925                     (len = buffer_len(&c->extended)) > 0 &&
1926                     c->extended_usage == CHAN_EXTENDED_READ) {
1927                         debug2("channel %d: rwin %u elen %u euse %d",
1928                             c->self, c->remote_window, buffer_len(&c->extended),
1929                             c->extended_usage);
1930                         if (len > c->remote_window)
1931                                 len = c->remote_window;
1932                         if (len > c->remote_maxpacket)
1933                                 len = c->remote_maxpacket;
1934                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1935                         packet_put_int(c->remote_id);
1936                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1937                         packet_put_string(buffer_ptr(&c->extended), len);
1938                         packet_send();
1939                         buffer_consume(&c->extended, len);
1940                         c->remote_window -= len;
1941                         debug2("channel %d: sent ext data %d", c->self, len);
1942                 }
1943         }
1944 }
1945
1946
1947 /* -- protocol input */
1948 void
1949 channel_input_data(int type, u_int32_t seq, void *ctxt)
1950 {
1951         int id;
1952         char *data;
1953         u_int data_len;
1954         Channel *c;
1955
1956         /* Get the channel number and verify it. */
1957         id = packet_get_int();
1958         c = channel_lookup(id);
1959         if (c == NULL)
1960                 packet_disconnect("Received data for nonexistent channel %d.", id);
1961
1962         /* Ignore any data for non-open channels (might happen on close) */
1963         if (c->type != SSH_CHANNEL_OPEN &&
1964             c->type != SSH_CHANNEL_X11_OPEN)
1965                 return;
1966
1967         /* Get the data. */
1968         data = packet_get_string(&data_len);
1969
1970         /*
1971          * Ignore data for protocol > 1.3 if output end is no longer open.
1972          * For protocol 2 the sending side is reducing its window as it sends
1973          * data, so we must 'fake' consumption of the data in order to ensure
1974          * that window updates are sent back.  Otherwise the connection might
1975          * deadlock.
1976          */
1977         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1978                 if (compat20) {
1979                         c->local_window -= data_len;
1980                         c->local_consumed += data_len;
1981                 }
1982                 xfree(data);
1983                 return;
1984         }
1985
1986         if (compat20) {
1987                 if (data_len > c->local_maxpacket) {
1988                         logit("channel %d: rcvd big packet %d, maxpack %d",
1989                             c->self, data_len, c->local_maxpacket);
1990                 }
1991                 if (data_len > c->local_window) {
1992                         logit("channel %d: rcvd too much data %d, win %d",
1993                             c->self, data_len, c->local_window);
1994                         xfree(data);
1995                         return;
1996                 }
1997                 c->local_window -= data_len;
1998         }
1999         packet_check_eom();
2000         if (c->datagram)
2001                 buffer_put_string(&c->output, data, data_len);
2002         else
2003                 buffer_append(&c->output, data, data_len);
2004         xfree(data);
2005 }
2006
2007 void
2008 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2009 {
2010         int id;
2011         char *data;
2012         u_int data_len, tcode;
2013         Channel *c;
2014
2015         /* Get the channel number and verify it. */
2016         id = packet_get_int();
2017         c = channel_lookup(id);
2018
2019         if (c == NULL)
2020                 packet_disconnect("Received extended_data for bad channel %d.", id);
2021         if (c->type != SSH_CHANNEL_OPEN) {
2022                 logit("channel %d: ext data for non open", id);
2023                 return;
2024         }
2025         if (c->flags & CHAN_EOF_RCVD) {
2026                 if (datafellows & SSH_BUG_EXTEOF)
2027                         debug("channel %d: accepting ext data after eof", id);
2028                 else
2029                         packet_disconnect("Received extended_data after EOF "
2030                             "on channel %d.", id);
2031         }
2032         tcode = packet_get_int();
2033         if (c->efd == -1 ||
2034             c->extended_usage != CHAN_EXTENDED_WRITE ||
2035             tcode != SSH2_EXTENDED_DATA_STDERR) {
2036                 logit("channel %d: bad ext data", c->self);
2037                 return;
2038         }
2039         data = packet_get_string(&data_len);
2040         packet_check_eom();
2041         if (data_len > c->local_window) {
2042                 logit("channel %d: rcvd too much extended_data %d, win %d",
2043                     c->self, data_len, c->local_window);
2044                 xfree(data);
2045                 return;
2046         }
2047         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2048         c->local_window -= data_len;
2049         buffer_append(&c->extended, data, data_len);
2050         xfree(data);
2051 }
2052
2053 void
2054 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2055 {
2056         int id;
2057         Channel *c;
2058
2059         id = packet_get_int();
2060         packet_check_eom();
2061         c = channel_lookup(id);
2062         if (c == NULL)
2063                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2064         chan_rcvd_ieof(c);
2065
2066         /* XXX force input close */
2067         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2068                 debug("channel %d: FORCE input drain", c->self);
2069                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2070                 if (buffer_len(&c->input) == 0)
2071                         chan_ibuf_empty(c);
2072         }
2073
2074 }
2075
2076 void
2077 channel_input_close(int type, u_int32_t seq, void *ctxt)
2078 {
2079         int id;
2080         Channel *c;
2081
2082         id = packet_get_int();
2083         packet_check_eom();
2084         c = channel_lookup(id);
2085         if (c == NULL)
2086                 packet_disconnect("Received close for nonexistent channel %d.", id);
2087
2088         /*
2089          * Send a confirmation that we have closed the channel and no more
2090          * data is coming for it.
2091          */
2092         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2093         packet_put_int(c->remote_id);
2094         packet_send();
2095
2096         /*
2097          * If the channel is in closed state, we have sent a close request,
2098          * and the other side will eventually respond with a confirmation.
2099          * Thus, we cannot free the channel here, because then there would be
2100          * no-one to receive the confirmation.  The channel gets freed when
2101          * the confirmation arrives.
2102          */
2103         if (c->type != SSH_CHANNEL_CLOSED) {
2104                 /*
2105                  * Not a closed channel - mark it as draining, which will
2106                  * cause it to be freed later.
2107                  */
2108                 buffer_clear(&c->input);
2109                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2110         }
2111 }
2112
2113 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2114 void
2115 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2116 {
2117         int id = packet_get_int();
2118         Channel *c = channel_lookup(id);
2119
2120         packet_check_eom();
2121         if (c == NULL)
2122                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2123         chan_rcvd_oclose(c);
2124 }
2125
2126 void
2127 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2128 {
2129         int id = packet_get_int();
2130         Channel *c = channel_lookup(id);
2131
2132         packet_check_eom();
2133         if (c == NULL)
2134                 packet_disconnect("Received close confirmation for "
2135                     "out-of-range channel %d.", id);
2136         if (c->type != SSH_CHANNEL_CLOSED)
2137                 packet_disconnect("Received close confirmation for "
2138                     "non-closed channel %d (type %d).", id, c->type);
2139         channel_free(c);
2140 }
2141
2142 void
2143 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2144 {
2145         int id, remote_id;
2146         Channel *c;
2147
2148         id = packet_get_int();
2149         c = channel_lookup(id);
2150
2151         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2152                 packet_disconnect("Received open confirmation for "
2153                     "non-opening channel %d.", id);
2154         remote_id = packet_get_int();
2155         /* Record the remote channel number and mark that the channel is now open. */
2156         c->remote_id = remote_id;
2157         c->type = SSH_CHANNEL_OPEN;
2158
2159         if (compat20) {
2160                 c->remote_window = packet_get_int();
2161                 c->remote_maxpacket = packet_get_int();
2162                 if (c->confirm) {
2163                         debug2("callback start");
2164                         c->confirm(c->self, c->confirm_ctx);
2165                         debug2("callback done");
2166                 }
2167                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2168                     c->remote_window, c->remote_maxpacket);
2169         }
2170         packet_check_eom();
2171 }
2172
2173 static char *
2174 reason2txt(int reason)
2175 {
2176         switch (reason) {
2177         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2178                 return "administratively prohibited";
2179         case SSH2_OPEN_CONNECT_FAILED:
2180                 return "connect failed";
2181         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2182                 return "unknown channel type";
2183         case SSH2_OPEN_RESOURCE_SHORTAGE:
2184                 return "resource shortage";
2185         }
2186         return "unknown reason";
2187 }
2188
2189 void
2190 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2191 {
2192         int id, reason;
2193         char *msg = NULL, *lang = NULL;
2194         Channel *c;
2195
2196         id = packet_get_int();
2197         c = channel_lookup(id);
2198
2199         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2200                 packet_disconnect("Received open failure for "
2201                     "non-opening channel %d.", id);
2202         if (compat20) {
2203                 reason = packet_get_int();
2204                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2205                         msg  = packet_get_string(NULL);
2206                         lang = packet_get_string(NULL);
2207                 }
2208                 logit("channel %d: open failed: %s%s%s", id,
2209                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2210                 if (msg != NULL)
2211                         xfree(msg);
2212                 if (lang != NULL)
2213                         xfree(lang);
2214         }
2215         packet_check_eom();
2216         /* Free the channel.  This will also close the socket. */
2217         channel_free(c);
2218 }
2219
2220 void
2221 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2222 {
2223         Channel *c;
2224         int id;
2225         u_int adjust;
2226
2227         if (!compat20)
2228                 return;
2229
2230         /* Get the channel number and verify it. */
2231         id = packet_get_int();
2232         c = channel_lookup(id);
2233
2234         if (c == NULL) {
2235                 logit("Received window adjust for non-open channel %d.", id);
2236                 return;
2237         }
2238         adjust = packet_get_int();
2239         packet_check_eom();
2240         debug2("channel %d: rcvd adjust %u", id, adjust);
2241         c->remote_window += adjust;
2242 }
2243
2244 void
2245 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2246 {
2247         Channel *c = NULL;
2248         u_short host_port;
2249         char *host, *originator_string;
2250         int remote_id, sock = -1;
2251
2252         remote_id = packet_get_int();
2253         host = packet_get_string(NULL);
2254         host_port = packet_get_int();
2255
2256         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2257                 originator_string = packet_get_string(NULL);
2258         } else {
2259                 originator_string = xstrdup("unknown (remote did not supply name)");
2260         }
2261         packet_check_eom();
2262         sock = channel_connect_to(host, host_port);
2263         if (sock != -1) {
2264                 c = channel_new("connected socket",
2265                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2266                     originator_string, 1);
2267                 c->remote_id = remote_id;
2268         }
2269         xfree(originator_string);
2270         if (c == NULL) {
2271                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2272                 packet_put_int(remote_id);
2273                 packet_send();
2274         }
2275         xfree(host);
2276 }
2277
2278
2279 /* -- tcp forwarding */
2280
2281 void
2282 channel_set_af(int af)
2283 {
2284         IPv4or6 = af;
2285 }
2286
2287 static int
2288 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2289     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2290 {
2291         Channel *c;
2292         int sock, r, success = 0, wildcard = 0, is_client;
2293         struct addrinfo hints, *ai, *aitop;
2294         const char *host, *addr;
2295         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2296
2297         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2298             listen_addr : host_to_connect;
2299         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2300
2301         if (host == NULL) {
2302                 error("No forward host name.");
2303                 return 0;
2304         }
2305         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2306                 error("Forward host name too long.");
2307                 return 0;
2308         }
2309
2310         /*
2311          * Determine whether or not a port forward listens to loopback,
2312          * specified address or wildcard. On the client, a specified bind
2313          * address will always override gateway_ports. On the server, a
2314          * gateway_ports of 1 (``yes'') will override the client's
2315          * specification and force a wildcard bind, whereas a value of 2
2316          * (``clientspecified'') will bind to whatever address the client
2317          * asked for.
2318          *
2319          * Special-case listen_addrs are:
2320          *
2321          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2322          * "" (empty string), "*"  -> wildcard v4/v6
2323          * "localhost"             -> loopback v4/v6
2324          */
2325         addr = NULL;
2326         if (listen_addr == NULL) {
2327                 /* No address specified: default to gateway_ports setting */
2328                 if (gateway_ports)
2329                         wildcard = 1;
2330         } else if (gateway_ports || is_client) {
2331                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2332                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2333                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2334                     (!is_client && gateway_ports == 1))
2335                         wildcard = 1;
2336                 else if (strcmp(listen_addr, "localhost") != 0)
2337                         addr = listen_addr;
2338         }
2339
2340         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2341             type, wildcard, (addr == NULL) ? "NULL" : addr);
2342
2343         /*
2344          * getaddrinfo returns a loopback address if the hostname is
2345          * set to NULL and hints.ai_flags is not AI_PASSIVE
2346          */
2347         memset(&hints, 0, sizeof(hints));
2348         hints.ai_family = IPv4or6;
2349         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2350         hints.ai_socktype = SOCK_STREAM;
2351         snprintf(strport, sizeof strport, "%d", listen_port);
2352         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2353                 if (addr == NULL) {
2354                         /* This really shouldn't happen */
2355                         packet_disconnect("getaddrinfo: fatal error: %s",
2356                             gai_strerror(r));
2357                 } else {
2358                         error("channel_setup_fwd_listener: "
2359                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2360                 }
2361                 return 0;
2362         }
2363
2364         for (ai = aitop; ai; ai = ai->ai_next) {
2365                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2366                         continue;
2367                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2368                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2369                         error("channel_setup_fwd_listener: getnameinfo failed");
2370                         continue;
2371                 }
2372                 /* Create a port to listen for the host. */
2373                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2374                 if (sock < 0) {
2375                         /* this is no error since kernel may not support ipv6 */
2376                         verbose("socket: %.100s", strerror(errno));
2377                         continue;
2378                 }
2379
2380                 channel_set_reuseaddr(sock);
2381
2382                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2383
2384                 /* Bind the socket to the address. */
2385                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2386                         /* address can be in use ipv6 address is already bound */
2387                         if (!ai->ai_next)
2388                                 error("bind: %.100s", strerror(errno));
2389                         else
2390                                 verbose("bind: %.100s", strerror(errno));
2391
2392                         close(sock);
2393                         continue;
2394                 }
2395                 /* Start listening for connections on the socket. */
2396                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2397                         error("listen: %.100s", strerror(errno));
2398                         close(sock);
2399                         continue;
2400                 }
2401                 /* Allocate a channel number for the socket. */
2402                 c = channel_new("port listener", type, sock, sock, -1,
2403                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2404                     0, "port listener", 1);
2405                 strlcpy(c->path, host, sizeof(c->path));
2406                 c->host_port = port_to_connect;
2407                 c->listening_port = listen_port;
2408                 success = 1;
2409         }
2410         if (success == 0)
2411                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2412                     listen_port);
2413         freeaddrinfo(aitop);
2414         return success;
2415 }
2416
2417 int
2418 channel_cancel_rport_listener(const char *host, u_short port)
2419 {
2420         u_int i;
2421         int found = 0;
2422
2423         for (i = 0; i < channels_alloc; i++) {
2424                 Channel *c = channels[i];
2425
2426                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2427                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2428                     c->listening_port == port) {
2429                         debug2("%s: close channel %d", __func__, i);
2430                         channel_free(c);
2431                         found = 1;
2432                 }
2433         }
2434
2435         return (found);
2436 }
2437
2438 /* protocol local port fwd, used by ssh (and sshd in v1) */
2439 int
2440 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2441     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2442 {
2443         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2444             listen_host, listen_port, host_to_connect, port_to_connect,
2445             gateway_ports);
2446 }
2447
2448 /* protocol v2 remote port fwd, used by sshd */
2449 int
2450 channel_setup_remote_fwd_listener(const char *listen_address,
2451     u_short listen_port, int gateway_ports)
2452 {
2453         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2454             listen_address, listen_port, NULL, 0, gateway_ports);
2455 }
2456
2457 /*
2458  * Initiate forwarding of connections to port "port" on remote host through
2459  * the secure channel to host:port from local side.
2460  */
2461
2462 void
2463 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2464     const char *host_to_connect, u_short port_to_connect)
2465 {
2466         int type, success = 0;
2467
2468         /* Record locally that connection to this host/port is permitted. */
2469         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2470                 fatal("channel_request_remote_forwarding: too many forwards");
2471
2472         /* Send the forward request to the remote side. */
2473         if (compat20) {
2474                 const char *address_to_bind;
2475                 if (listen_host == NULL)
2476                         address_to_bind = "localhost";
2477                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2478                         address_to_bind = "";
2479                 else
2480                         address_to_bind = listen_host;
2481
2482                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2483                 packet_put_cstring("tcpip-forward");
2484                 packet_put_char(1);                     /* boolean: want reply */
2485                 packet_put_cstring(address_to_bind);
2486                 packet_put_int(listen_port);
2487                 packet_send();
2488                 packet_write_wait();
2489                 /* Assume that server accepts the request */
2490                 success = 1;
2491         } else {
2492                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2493                 packet_put_int(listen_port);
2494                 packet_put_cstring(host_to_connect);
2495                 packet_put_int(port_to_connect);
2496                 packet_send();
2497                 packet_write_wait();
2498
2499                 /* Wait for response from the remote side. */
2500                 type = packet_read();
2501                 switch (type) {
2502                 case SSH_SMSG_SUCCESS:
2503                         success = 1;
2504                         break;
2505                 case SSH_SMSG_FAILURE:
2506                         logit("Warning: Server denied remote port forwarding.");
2507                         break;
2508                 default:
2509                         /* Unknown packet */
2510                         packet_disconnect("Protocol error for port forward request:"
2511                             "received packet type %d.", type);
2512                 }
2513         }
2514         if (success) {
2515                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2516                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2517                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2518                 num_permitted_opens++;
2519         }
2520 }
2521
2522 /*
2523  * Request cancellation of remote forwarding of connection host:port from
2524  * local side.
2525  */
2526 void
2527 channel_request_rforward_cancel(const char *host, u_short port)
2528 {
2529         int i;
2530
2531         if (!compat20)
2532                 return;
2533
2534         for (i = 0; i < num_permitted_opens; i++) {
2535                 if (permitted_opens[i].host_to_connect != NULL &&
2536                     permitted_opens[i].listen_port == port)
2537                         break;
2538         }
2539         if (i >= num_permitted_opens) {
2540                 debug("%s: requested forward not found", __func__);
2541                 return;
2542         }
2543         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2544         packet_put_cstring("cancel-tcpip-forward");
2545         packet_put_char(0);
2546         packet_put_cstring(host == NULL ? "" : host);
2547         packet_put_int(port);
2548         packet_send();
2549
2550         permitted_opens[i].listen_port = 0;
2551         permitted_opens[i].port_to_connect = 0;
2552         xfree(permitted_opens[i].host_to_connect);
2553         permitted_opens[i].host_to_connect = NULL;
2554 }
2555
2556 /*
2557  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2558  * listening for the port, and sends back a success reply (or disconnect
2559  * message if there was an error).  This never returns if there was an error.
2560  */
2561 void
2562 channel_input_port_forward_request(int is_root, int gateway_ports)
2563 {
2564         u_short port, host_port;
2565         char *hostname;
2566
2567         /* Get arguments from the packet. */
2568         port = packet_get_int();
2569         hostname = packet_get_string(NULL);
2570         host_port = packet_get_int();
2571
2572 #ifndef HAVE_CYGWIN
2573         /*
2574          * Check that an unprivileged user is not trying to forward a
2575          * privileged port.
2576          */
2577         if (port < IPPORT_RESERVED && !is_root)
2578                 packet_disconnect(
2579                     "Requested forwarding of port %d but user is not root.",
2580                     port);
2581         if (host_port == 0)
2582                 packet_disconnect("Dynamic forwarding denied.");
2583 #endif
2584
2585         /* Initiate forwarding */
2586         channel_setup_local_fwd_listener(NULL, port, hostname,
2587             host_port, gateway_ports);
2588
2589         /* Free the argument string. */
2590         xfree(hostname);
2591 }
2592
2593 /*
2594  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2595  * usually called by the server, because the user could connect to any port
2596  * anyway, and the server has no way to know but to trust the client anyway.
2597  */
2598 void
2599 channel_permit_all_opens(void)
2600 {
2601         if (num_permitted_opens == 0)
2602                 all_opens_permitted = 1;
2603 }
2604
2605 void
2606 channel_add_permitted_opens(char *host, int port)
2607 {
2608         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2609                 fatal("channel_request_remote_forwarding: too many forwards");
2610         debug("allow port forwarding to host %s port %d", host, port);
2611
2612         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2613         permitted_opens[num_permitted_opens].port_to_connect = port;
2614         num_permitted_opens++;
2615
2616         all_opens_permitted = 0;
2617 }
2618
2619 void
2620 channel_clear_permitted_opens(void)
2621 {
2622         int i;
2623
2624         for (i = 0; i < num_permitted_opens; i++)
2625                 if (permitted_opens[i].host_to_connect != NULL)
2626                         xfree(permitted_opens[i].host_to_connect);
2627         num_permitted_opens = 0;
2628
2629 }
2630
2631 /* return socket to remote host, port */
2632 static int
2633 connect_to(const char *host, u_short port)
2634 {
2635         struct addrinfo hints, *ai, *aitop;
2636         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2637         int gaierr;
2638         int sock = -1;
2639
2640         memset(&hints, 0, sizeof(hints));
2641         hints.ai_family = IPv4or6;
2642         hints.ai_socktype = SOCK_STREAM;
2643         snprintf(strport, sizeof strport, "%d", port);
2644         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2645                 error("connect_to %.100s: unknown host (%s)", host,
2646                     gai_strerror(gaierr));
2647                 return -1;
2648         }
2649         for (ai = aitop; ai; ai = ai->ai_next) {
2650                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2651                         continue;
2652                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2653                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2654                         error("connect_to: getnameinfo failed");
2655                         continue;
2656                 }
2657                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2658                 if (sock < 0) {
2659                         if (ai->ai_next == NULL)
2660                                 error("socket: %.100s", strerror(errno));
2661                         else
2662                                 verbose("socket: %.100s", strerror(errno));
2663                         continue;
2664                 }
2665                 if (set_nonblock(sock) == -1)
2666                         fatal("%s: set_nonblock(%d)", __func__, sock);
2667                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2668                     errno != EINPROGRESS) {
2669                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2670                             strerror(errno));
2671                         close(sock);
2672                         continue;       /* fail -- try next */
2673                 }
2674                 break; /* success */
2675
2676         }
2677         freeaddrinfo(aitop);
2678         if (!ai) {
2679                 error("connect_to %.100s port %d: failed.", host, port);
2680                 return -1;
2681         }
2682         /* success */
2683         set_nodelay(sock);
2684         return sock;
2685 }
2686
2687 int
2688 channel_connect_by_listen_address(u_short listen_port)
2689 {
2690         int i;
2691
2692         for (i = 0; i < num_permitted_opens; i++)
2693                 if (permitted_opens[i].host_to_connect != NULL &&
2694                     permitted_opens[i].listen_port == listen_port)
2695                         return connect_to(
2696                             permitted_opens[i].host_to_connect,
2697                             permitted_opens[i].port_to_connect);
2698         error("WARNING: Server requests forwarding for unknown listen_port %d",
2699             listen_port);
2700         return -1;
2701 }
2702
2703 /* Check if connecting to that port is permitted and connect. */
2704 int
2705 channel_connect_to(const char *host, u_short port)
2706 {
2707         int i, permit;
2708
2709         permit = all_opens_permitted;
2710         if (!permit) {
2711                 for (i = 0; i < num_permitted_opens; i++)
2712                         if (permitted_opens[i].host_to_connect != NULL &&
2713                             permitted_opens[i].port_to_connect == port &&
2714                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2715                                 permit = 1;
2716
2717         }
2718         if (!permit) {
2719                 logit("Received request to connect to host %.100s port %d, "
2720                     "but the request was denied.", host, port);
2721                 return -1;
2722         }
2723         return connect_to(host, port);
2724 }
2725
2726 void
2727 channel_send_window_changes(void)
2728 {
2729         u_int i;
2730         struct winsize ws;
2731
2732         for (i = 0; i < channels_alloc; i++) {
2733                 if (channels[i] == NULL || !channels[i]->client_tty ||
2734                     channels[i]->type != SSH_CHANNEL_OPEN)
2735                         continue;
2736                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2737                         continue;
2738                 channel_request_start(i, "window-change", 0);
2739                 packet_put_int((u_int)ws.ws_col);
2740                 packet_put_int((u_int)ws.ws_row);
2741                 packet_put_int((u_int)ws.ws_xpixel);
2742                 packet_put_int((u_int)ws.ws_ypixel);
2743                 packet_send();
2744         }
2745 }
2746
2747 /* -- X11 forwarding */
2748
2749 /*
2750  * Creates an internet domain socket for listening for X11 connections.
2751  * Returns 0 and a suitable display number for the DISPLAY variable
2752  * stored in display_numberp , or -1 if an error occurs.
2753  */
2754 int
2755 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2756     int single_connection, u_int *display_numberp, int **chanids)
2757 {
2758         Channel *nc = NULL;
2759         int display_number, sock;
2760         u_short port;
2761         struct addrinfo hints, *ai, *aitop;
2762         char strport[NI_MAXSERV];
2763         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2764
2765         if (chanids == NULL)
2766                 return -1;
2767
2768         for (display_number = x11_display_offset;
2769             display_number < MAX_DISPLAYS;
2770             display_number++) {
2771                 port = 6000 + display_number;
2772                 memset(&hints, 0, sizeof(hints));
2773                 hints.ai_family = IPv4or6;
2774                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2775                 hints.ai_socktype = SOCK_STREAM;
2776                 snprintf(strport, sizeof strport, "%d", port);
2777                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2778                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2779                         return -1;
2780                 }
2781                 for (ai = aitop; ai; ai = ai->ai_next) {
2782                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2783                                 continue;
2784                         sock = socket(ai->ai_family, ai->ai_socktype,
2785                             ai->ai_protocol);
2786                         if (sock < 0) {
2787                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2788                                         error("socket: %.100s", strerror(errno));
2789                                         freeaddrinfo(aitop);
2790                                         return -1;
2791                                 } else {
2792                                         debug("x11_create_display_inet: Socket family %d not supported",
2793                                                  ai->ai_family);
2794                                         continue;
2795                                 }
2796                         }
2797 #ifdef IPV6_V6ONLY
2798                         if (ai->ai_family == AF_INET6) {
2799                                 int on = 1;
2800                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2801                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2802                         }
2803 #endif
2804                         channel_set_reuseaddr(sock);
2805                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2806                                 debug2("bind port %d: %.100s", port, strerror(errno));
2807                                 close(sock);
2808
2809                                 if (ai->ai_next)
2810                                         continue;
2811
2812                                 for (n = 0; n < num_socks; n++) {
2813                                         close(socks[n]);
2814                                 }
2815                                 num_socks = 0;
2816                                 break;
2817                         }
2818                         socks[num_socks++] = sock;
2819 #ifndef DONT_TRY_OTHER_AF
2820                         if (num_socks == NUM_SOCKS)
2821                                 break;
2822 #else
2823                         if (x11_use_localhost) {
2824                                 if (num_socks == NUM_SOCKS)
2825                                         break;
2826                         } else {
2827                                 break;
2828                         }
2829 #endif
2830                 }
2831                 freeaddrinfo(aitop);
2832                 if (num_socks > 0)
2833                         break;
2834         }
2835         if (display_number >= MAX_DISPLAYS) {
2836                 error("Failed to allocate internet-domain X11 display socket.");
2837                 return -1;
2838         }
2839         /* Start listening for connections on the socket. */
2840         for (n = 0; n < num_socks; n++) {
2841                 sock = socks[n];
2842                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2843                         error("listen: %.100s", strerror(errno));
2844                         close(sock);
2845                         return -1;
2846                 }
2847         }
2848
2849         /* Allocate a channel for each socket. */
2850         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2851         for (n = 0; n < num_socks; n++) {
2852                 sock = socks[n];
2853                 nc = channel_new("x11 listener",
2854                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2855                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2856                     0, "X11 inet listener", 1);
2857                 nc->single_connection = single_connection;
2858                 (*chanids)[n] = nc->self;
2859         }
2860         (*chanids)[n] = -1;
2861
2862         /* Return the display number for the DISPLAY environment variable. */
2863         *display_numberp = display_number;
2864         return (0);
2865 }
2866
2867 static int
2868 connect_local_xsocket(u_int dnr)
2869 {
2870         int sock;
2871         struct sockaddr_un addr;
2872
2873         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2874         if (sock < 0)
2875                 error("socket: %.100s", strerror(errno));
2876         memset(&addr, 0, sizeof(addr));
2877         addr.sun_family = AF_UNIX;
2878         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2879         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
2880                 return sock;
2881         close(sock);
2882         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2883         return -1;
2884 }
2885
2886 int
2887 x11_connect_display(void)
2888 {
2889         int display_number, sock = 0;
2890         const char *display;
2891         char buf[1024], *cp;
2892         struct addrinfo hints, *ai, *aitop;
2893         char strport[NI_MAXSERV];
2894         int gaierr;
2895
2896         /* Try to open a socket for the local X server. */
2897         display = getenv("DISPLAY");
2898         if (!display) {
2899                 error("DISPLAY not set.");
2900                 return -1;
2901         }
2902         /*
2903          * Now we decode the value of the DISPLAY variable and make a
2904          * connection to the real X server.
2905          */
2906
2907         /*
2908          * Check if it is a unix domain socket.  Unix domain displays are in
2909          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2910          */
2911         if (strncmp(display, "unix:", 5) == 0 ||
2912             display[0] == ':') {
2913                 /* Connect to the unix domain socket. */
2914                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2915                         error("Could not parse display number from DISPLAY: %.100s",
2916                             display);
2917                         return -1;
2918                 }
2919                 /* Create a socket. */
2920                 sock = connect_local_xsocket(display_number);
2921                 if (sock < 0)
2922                         return -1;
2923
2924                 /* OK, we now have a connection to the display. */
2925                 return sock;
2926         }
2927         /*
2928          * Connect to an inet socket.  The DISPLAY value is supposedly
2929          * hostname:d[.s], where hostname may also be numeric IP address.
2930          */
2931         strlcpy(buf, display, sizeof(buf));
2932         cp = strchr(buf, ':');
2933         if (!cp) {
2934                 error("Could not find ':' in DISPLAY: %.100s", display);
2935                 return -1;
2936         }
2937         *cp = 0;
2938         /* buf now contains the host name.  But first we parse the display number. */
2939         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2940                 error("Could not parse display number from DISPLAY: %.100s",
2941                     display);
2942                 return -1;
2943         }
2944
2945         /* Look up the host address */
2946         memset(&hints, 0, sizeof(hints));
2947         hints.ai_family = IPv4or6;
2948         hints.ai_socktype = SOCK_STREAM;
2949         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2950         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2951                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2952                 return -1;
2953         }
2954         for (ai = aitop; ai; ai = ai->ai_next) {
2955                 /* Create a socket. */
2956                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2957                 if (sock < 0) {
2958                         debug2("socket: %.100s", strerror(errno));
2959                         continue;
2960                 }
2961                 /* Connect it to the display. */
2962                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2963                         debug2("connect %.100s port %d: %.100s", buf,
2964                             6000 + display_number, strerror(errno));
2965                         close(sock);
2966                         continue;
2967                 }
2968                 /* Success */
2969                 break;
2970         }
2971         freeaddrinfo(aitop);
2972         if (!ai) {
2973                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2974                     strerror(errno));
2975                 return -1;
2976         }
2977         set_nodelay(sock);
2978         return sock;
2979 }
2980
2981 /*
2982  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2983  * the remote channel number.  We should do whatever we want, and respond
2984  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2985  */
2986
2987 void
2988 x11_input_open(int type, u_int32_t seq, void *ctxt)
2989 {
2990         Channel *c = NULL;
2991         int remote_id, sock = 0;
2992         char *remote_host;
2993
2994         debug("Received X11 open request.");
2995
2996         remote_id = packet_get_int();
2997
2998         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2999                 remote_host = packet_get_string(NULL);
3000         } else {
3001                 remote_host = xstrdup("unknown (remote did not supply name)");
3002         }
3003         packet_check_eom();
3004
3005         /* Obtain a connection to the real X display. */
3006         sock = x11_connect_display();
3007         if (sock != -1) {
3008                 /* Allocate a channel for this connection. */
3009                 c = channel_new("connected x11 socket",
3010                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3011                     remote_host, 1);
3012                 c->remote_id = remote_id;
3013                 c->force_drain = 1;
3014         }
3015         xfree(remote_host);
3016         if (c == NULL) {
3017                 /* Send refusal to the remote host. */
3018                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3019                 packet_put_int(remote_id);
3020         } else {
3021                 /* Send a confirmation to the remote host. */
3022                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3023                 packet_put_int(remote_id);
3024                 packet_put_int(c->self);
3025         }
3026         packet_send();
3027 }
3028
3029 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3030 void
3031 deny_input_open(int type, u_int32_t seq, void *ctxt)
3032 {
3033         int rchan = packet_get_int();
3034
3035         switch (type) {
3036         case SSH_SMSG_AGENT_OPEN:
3037                 error("Warning: ssh server tried agent forwarding.");
3038                 break;
3039         case SSH_SMSG_X11_OPEN:
3040                 error("Warning: ssh server tried X11 forwarding.");
3041                 break;
3042         default:
3043                 error("deny_input_open: type %d", type);
3044                 break;
3045         }
3046         error("Warning: this is probably a break-in attempt by a malicious server.");
3047         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3048         packet_put_int(rchan);
3049         packet_send();
3050 }
3051
3052 /*
3053  * Requests forwarding of X11 connections, generates fake authentication
3054  * data, and enables authentication spoofing.
3055  * This should be called in the client only.
3056  */
3057 void
3058 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3059     const char *proto, const char *data)
3060 {
3061         u_int data_len = (u_int) strlen(data) / 2;
3062         u_int i, value;
3063         char *new_data;
3064         int screen_number;
3065         const char *cp;
3066         u_int32_t rnd = 0;
3067
3068         if (x11_saved_display == NULL)
3069                 x11_saved_display = xstrdup(disp);
3070         else if (strcmp(disp, x11_saved_display) != 0) {
3071                 error("x11_request_forwarding_with_spoofing: different "
3072                     "$DISPLAY already forwarded");
3073                 return;
3074         }
3075
3076         cp = disp;
3077         if (disp)
3078                 cp = strchr(disp, ':');
3079         if (cp)
3080                 cp = strchr(cp, '.');
3081         if (cp)
3082                 screen_number = atoi(cp + 1);
3083         else
3084                 screen_number = 0;
3085
3086         if (x11_saved_proto == NULL) {
3087                 /* Save protocol name. */
3088                 x11_saved_proto = xstrdup(proto);
3089                 /*
3090                  * Extract real authentication data and generate fake data
3091                  * of the same length.
3092                  */
3093                 x11_saved_data = xmalloc(data_len);
3094                 x11_fake_data = xmalloc(data_len);
3095                 for (i = 0; i < data_len; i++) {
3096                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3097                                 fatal("x11_request_forwarding: bad "
3098                                     "authentication data: %.100s", data);
3099                         if (i % 4 == 0)
3100                                 rnd = arc4random();
3101                         x11_saved_data[i] = value;
3102                         x11_fake_data[i] = rnd & 0xff;
3103                         rnd >>= 8;
3104                 }
3105                 x11_saved_data_len = data_len;
3106                 x11_fake_data_len = data_len;
3107         }
3108
3109         /* Convert the fake data into hex. */
3110         new_data = tohex(x11_fake_data, data_len);
3111
3112         /* Send the request packet. */
3113         if (compat20) {
3114                 channel_request_start(client_session_id, "x11-req", 0);
3115                 packet_put_char(0);     /* XXX bool single connection */
3116         } else {
3117                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3118         }
3119         packet_put_cstring(proto);
3120         packet_put_cstring(new_data);
3121         packet_put_int(screen_number);
3122         packet_send();
3123         packet_write_wait();
3124         xfree(new_data);
3125 }
3126
3127
3128 /* -- agent forwarding */
3129
3130 /* Sends a message to the server to request authentication fd forwarding. */
3131
3132 void
3133 auth_request_forwarding(void)
3134 {
3135         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3136         packet_send();
3137         packet_write_wait();
3138 }