crypto/openssh-3.9p1/channels.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * This file contains functions for generic socket connection forwarding.
   6  * There is also code for initiating connection forwarding for X11 connections,
   7  * arbitrary tcp/ip connections, and the authentication agent connection.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * SSH2 support added by Markus Friedl.
  16  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  17  * Copyright (c) 1999 Dug Song.  All rights reserved.
  18  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  19  *
  20  * Redistribution and use in source and binary forms, with or without
  21  * modification, are permitted provided that the following conditions
  22  * are met:
  23  * 1. Redistributions of source code must retain the above copyright
  24  *    notice, this list of conditions and the following disclaimer.
  25  * 2. Redistributions in binary form must reproduce the above copyright
  26  *    notice, this list of conditions and the following disclaimer in the
  27  *    documentation and/or other materials provided with the distribution.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  30  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  31  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  32  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  33  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  34  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  38  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  39  */
  40
  41 #include "includes.h"
  42 RCSID("$OpenBSD: channels.c,v 1.209 2004/08/11 21:43:04 avsm Exp $");
  43
  44 #include "ssh.h"
  45 #include "ssh1.h"
  46 #include "ssh2.h"
  47 #include "packet.h"
  48 #include "xmalloc.h"
  49 #include "log.h"
  50 #include "misc.h"
  51 #include "channels.h"
  52 #include "compat.h"
  53 #include "canohost.h"
  54 #include "key.h"
  55 #include "authfd.h"
  56 #include "pathnames.h"
  57 #include "bufaux.h"
  58
  59 /* -- channel core */
  60
  61 /*
  62  * Pointer to an array containing all allocated channels.  The array is
  63  * dynamically extended as needed.
  64  */
  65 static Channel **channels = NULL;
  66
  67 /*
  68  * Size of the channel array.  All slots of the array must always be
  69  * initialized (at least the type field); unused slots set to NULL
  70  */
  71 static u_int channels_alloc = 0;
  72
  73 /*
  74  * Maximum file descriptor value used in any of the channels.  This is
  75  * updated in channel_new.
  76  */
  77 static int channel_max_fd = 0;
  78
  79
  80 /* -- tcp forwarding */
  81
  82 /*
  83  * Data structure for storing which hosts are permitted for forward requests.
  84  * The local sides of any remote forwards are stored in this array to prevent
  85  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  86  * network (which might be behind a firewall).
  87  */
  88 typedef struct {
  89         char *host_to_connect;          /* Connect to 'host'. */
  90         u_short port_to_connect;        /* Connect to 'port'. */
  91         u_short listen_port;            /* Remote side should listen port number. */
  92 } ForwardPermission;
  93
  94 /* List of all permitted host/port pairs to connect. */
  95 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
  96
  97 /* Number of permitted host/port pairs in the array. */
  98 static int num_permitted_opens = 0;
  99 /*
 100  * If this is true, all opens are permitted.  This is the case on the server
 101  * on which we have to trust the client anyway, and the user could do
 102  * anything after logging in anyway.
 103  */
 104 static int all_opens_permitted = 0;
 105
 106
 107 /* -- X11 forwarding */
 108
 109 /* Maximum number of fake X11 displays to try. */
 110 #define MAX_DISPLAYS  1000
 111
 112 /* Saved X11 authentication protocol name. */
 113 static char *x11_saved_proto = NULL;
 114
 115 /* Saved X11 authentication data.  This is the real data. */
 116 static char *x11_saved_data = NULL;
 117 static u_int x11_saved_data_len = 0;
 118
 119 /*
 120  * Fake X11 authentication data.  This is what the server will be sending us;
 121  * we should replace any occurrences of this by the real data.
 122  */
 123 static char *x11_fake_data = NULL;
 124 static u_int x11_fake_data_len;
 125
 126
 127 /* -- agent forwarding */
 128
 129 #define NUM_SOCKS       10
 130
 131 /* AF_UNSPEC or AF_INET or AF_INET6 */
 132 static int IPv4or6 = AF_UNSPEC;
 133
 134 /* helper */
 135 static void port_open_helper(Channel *c, char *rtype);
 136
 137 /* -- channel core */
 138
 139 Channel *
 140 channel_lookup(int id)
 141 {
 142         Channel *c;
 143
 144         if (id < 0 || (u_int)id >= channels_alloc) {
 145                 logit("channel_lookup: %d: bad id", id);
 146                 return NULL;
 147         }
 148         c = channels[id];
 149         if (c == NULL) {
 150                 logit("channel_lookup: %d: bad id: channel free", id);
 151                 return NULL;
 152         }
 153         return c;
 154 }
 155
 156 /*
 157  * Register filedescriptors for a channel, used when allocating a channel or
 158  * when the channel consumer/producer is ready, e.g. shell exec'd
 159  */
 160
 161 static void
 162 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 163     int extusage, int nonblock)
 164 {
 165         /* Update the maximum file descriptor value. */
 166         channel_max_fd = MAX(channel_max_fd, rfd);
 167         channel_max_fd = MAX(channel_max_fd, wfd);
 168         channel_max_fd = MAX(channel_max_fd, efd);
 169
 170         /* XXX set close-on-exec -markus */
 171
 172         c->rfd = rfd;
 173         c->wfd = wfd;
 174         c->sock = (rfd == wfd) ? rfd : -1;
 175         c->ctl_fd = -1; /* XXX: set elsewhere */
 176         c->efd = efd;
 177         c->extended_usage = extusage;
 178
 179         /* XXX ugly hack: nonblock is only set by the server */
 180         if (nonblock && isatty(c->rfd)) {
 181                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 182                 c->isatty = 1;
 183                 if (!isatty(c->wfd)) {
 184                         error("channel %d: wfd %d is not a tty?",
 185                             c->self, c->wfd);
 186                 }
 187         } else {
 188                 c->isatty = 0;
 189         }
 190         c->wfd_isatty = isatty(c->wfd);
 191
 192         /* enable nonblocking mode */
 193         if (nonblock) {
 194                 if (rfd != -1)
 195                         set_nonblock(rfd);
 196                 if (wfd != -1)
 197                         set_nonblock(wfd);
 198                 if (efd != -1)
 199                         set_nonblock(efd);
 200         }
 201 }
 202
 203 /*
 204  * Allocate a new channel object and set its type and socket. This will cause
 205  * remote_name to be freed.
 206  */
 207
 208 Channel *
 209 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 210     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 211 {
 212         int found;
 213         u_int i;
 214         Channel *c;
 215
 216         /* Do initial allocation if this is the first call. */
 217         if (channels_alloc == 0) {
 218                 channels_alloc = 10;
 219                 channels = xmalloc(channels_alloc * sizeof(Channel *));
 220                 for (i = 0; i < channels_alloc; i++)
 221                         channels[i] = NULL;
 222         }
 223         /* Try to find a free slot where to put the new channel. */
 224         for (found = -1, i = 0; i < channels_alloc; i++)
 225                 if (channels[i] == NULL) {
 226                         /* Found a free slot. */
 227                         found = (int)i;
 228                         break;
 229                 }
 230         if (found < 0) {
 231                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 232                 found = channels_alloc;
 233                 if (channels_alloc > 10000)
 234                         fatal("channel_new: internal error: channels_alloc %d "
 235                             "too big.", channels_alloc);
 236                 channels = xrealloc(channels,
 237                     (channels_alloc + 10) * sizeof(Channel *));
 238                 channels_alloc += 10;
 239                 debug2("channel: expanding %d", channels_alloc);
 240                 for (i = found; i < channels_alloc; i++)
 241                         channels[i] = NULL;
 242         }
 243         /* Initialize and return new channel. */
 244         c = channels[found] = xmalloc(sizeof(Channel));
 245         memset(c, 0, sizeof(Channel));
 246         buffer_init(&c->input);
 247         buffer_init(&c->output);
 248         buffer_init(&c->extended);
 249         c->ostate = CHAN_OUTPUT_OPEN;
 250         c->istate = CHAN_INPUT_OPEN;
 251         c->flags = 0;
 252         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 253         c->self = found;
 254         c->type = type;
 255         c->ctype = ctype;
 256         c->local_window = window;
 257         c->local_window_max = window;
 258         c->local_consumed = 0;
 259         c->local_maxpacket = maxpack;
 260         c->remote_id = -1;
 261         c->remote_name = xstrdup(remote_name);
 262         c->remote_window = 0;
 263         c->remote_maxpacket = 0;
 264         c->force_drain = 0;
 265         c->single_connection = 0;
 266         c->detach_user = NULL;
 267         c->confirm = NULL;
 268         c->confirm_ctx = NULL;
 269         c->input_filter = NULL;
 270         debug("channel %d: new [%s]", found, remote_name);
 271         return c;
 272 }
 273
 274 static int
 275 channel_find_maxfd(void)
 276 {
 277         u_int i;
 278         int max = 0;
 279         Channel *c;
 280
 281         for (i = 0; i < channels_alloc; i++) {
 282                 c = channels[i];
 283                 if (c != NULL) {
 284                         max = MAX(max, c->rfd);
 285                         max = MAX(max, c->wfd);
 286                         max = MAX(max, c->efd);
 287                 }
 288         }
 289         return max;
 290 }
 291
 292 int
 293 channel_close_fd(int *fdp)
 294 {
 295         int ret = 0, fd = *fdp;
 296
 297         if (fd != -1) {
 298                 ret = close(fd);
 299                 *fdp = -1;
 300                 if (fd == channel_max_fd)
 301                         channel_max_fd = channel_find_maxfd();
 302         }
 303         return ret;
 304 }
 305
 306 /* Close all channel fd/socket. */
 307
 308 static void
 309 channel_close_fds(Channel *c)
 310 {
 311         debug3("channel %d: close_fds r %d w %d e %d c %d",
 312             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 313
 314         channel_close_fd(&c->sock);
 315         channel_close_fd(&c->ctl_fd);
 316         channel_close_fd(&c->rfd);
 317         channel_close_fd(&c->wfd);
 318         channel_close_fd(&c->efd);
 319 }
 320
 321 /* Free the channel and close its fd/socket. */
 322
 323 void
 324 channel_free(Channel *c)
 325 {
 326         char *s;
 327         u_int i, n;
 328
 329         for (n = 0, i = 0; i < channels_alloc; i++)
 330                 if (channels[i])
 331                         n++;
 332         debug("channel %d: free: %s, nchannels %u", c->self,
 333             c->remote_name ? c->remote_name : "???", n);
 334
 335         s = channel_open_message();
 336         debug3("channel %d: status: %s", c->self, s);
 337         xfree(s);
 338
 339         if (c->sock != -1)
 340                 shutdown(c->sock, SHUT_RDWR);
 341         if (c->ctl_fd != -1)
 342                 shutdown(c->ctl_fd, SHUT_RDWR);
 343         channel_close_fds(c);
 344         buffer_free(&c->input);
 345         buffer_free(&c->output);
 346         buffer_free(&c->extended);
 347         if (c->remote_name) {
 348                 xfree(c->remote_name);
 349                 c->remote_name = NULL;
 350         }
 351         channels[c->self] = NULL;
 352         xfree(c);
 353 }
 354
 355 void
 356 channel_free_all(void)
 357 {
 358         u_int i;
 359
 360         for (i = 0; i < channels_alloc; i++)
 361                 if (channels[i] != NULL)
 362                         channel_free(channels[i]);
 363 }
 364
 365 /*
 366  * Closes the sockets/fds of all channels.  This is used to close extra file
 367  * descriptors after a fork.
 368  */
 369
 370 void
 371 channel_close_all(void)
 372 {
 373         u_int i;
 374
 375         for (i = 0; i < channels_alloc; i++)
 376                 if (channels[i] != NULL)
 377                         channel_close_fds(channels[i]);
 378 }
 379
 380 /*
 381  * Stop listening to channels.
 382  */
 383
 384 void
 385 channel_stop_listening(void)
 386 {
 387         u_int i;
 388         Channel *c;
 389
 390         for (i = 0; i < channels_alloc; i++) {
 391                 c = channels[i];
 392                 if (c != NULL) {
 393                         switch (c->type) {
 394                         case SSH_CHANNEL_AUTH_SOCKET:
 395                         case SSH_CHANNEL_PORT_LISTENER:
 396                         case SSH_CHANNEL_RPORT_LISTENER:
 397                         case SSH_CHANNEL_X11_LISTENER:
 398                                 channel_close_fd(&c->sock);
 399                                 channel_free(c);
 400                                 break;
 401                         }
 402                 }
 403         }
 404 }
 405
 406 /*
 407  * Returns true if no channel has too much buffered data, and false if one or
 408  * more channel is overfull.
 409  */
 410
 411 int
 412 channel_not_very_much_buffered_data(void)
 413 {
 414         u_int i;
 415         Channel *c;
 416
 417         for (i = 0; i < channels_alloc; i++) {
 418                 c = channels[i];
 419                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 420 #if 0
 421                         if (!compat20 &&
 422                             buffer_len(&c->input) > packet_get_maxsize()) {
 423                                 debug2("channel %d: big input buffer %d",
 424                                     c->self, buffer_len(&c->input));
 425                                 return 0;
 426                         }
 427 #endif
 428                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 429                                 debug2("channel %d: big output buffer %u > %u",
 430                                     c->self, buffer_len(&c->output),
 431                                     packet_get_maxsize());
 432                                 return 0;
 433                         }
 434                 }
 435         }
 436         return 1;
 437 }
 438
 439 /* Returns true if any channel is still open. */
 440
 441 int
 442 channel_still_open(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)
 450                         continue;
 451                 switch (c->type) {
 452                 case SSH_CHANNEL_X11_LISTENER:
 453                 case SSH_CHANNEL_PORT_LISTENER:
 454                 case SSH_CHANNEL_RPORT_LISTENER:
 455                 case SSH_CHANNEL_CLOSED:
 456                 case SSH_CHANNEL_AUTH_SOCKET:
 457                 case SSH_CHANNEL_DYNAMIC:
 458                 case SSH_CHANNEL_CONNECTING:
 459                 case SSH_CHANNEL_ZOMBIE:
 460                         continue;
 461                 case SSH_CHANNEL_LARVAL:
 462                         if (!compat20)
 463                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 464                         continue;
 465                 case SSH_CHANNEL_OPENING:
 466                 case SSH_CHANNEL_OPEN:
 467                 case SSH_CHANNEL_X11_OPEN:
 468                         return 1;
 469                 case SSH_CHANNEL_INPUT_DRAINING:
 470                 case SSH_CHANNEL_OUTPUT_DRAINING:
 471                         if (!compat13)
 472                                 fatal("cannot happen: OUT_DRAIN");
 473                         return 1;
 474                 default:
 475                         fatal("channel_still_open: bad channel type %d", c->type);
 476                         /* NOTREACHED */
 477                 }
 478         }
 479         return 0;
 480 }
 481
 482 /* Returns the id of an open channel suitable for keepaliving */
 483
 484 int
 485 channel_find_open(void)
 486 {
 487         u_int i;
 488         Channel *c;
 489
 490         for (i = 0; i < channels_alloc; i++) {
 491                 c = channels[i];
 492                 if (c == NULL || c->remote_id < 0)
 493                         continue;
 494                 switch (c->type) {
 495                 case SSH_CHANNEL_CLOSED:
 496                 case SSH_CHANNEL_DYNAMIC:
 497                 case SSH_CHANNEL_X11_LISTENER:
 498                 case SSH_CHANNEL_PORT_LISTENER:
 499                 case SSH_CHANNEL_RPORT_LISTENER:
 500                 case SSH_CHANNEL_OPENING:
 501                 case SSH_CHANNEL_CONNECTING:
 502                 case SSH_CHANNEL_ZOMBIE:
 503                         continue;
 504                 case SSH_CHANNEL_LARVAL:
 505                 case SSH_CHANNEL_AUTH_SOCKET:
 506                 case SSH_CHANNEL_OPEN:
 507                 case SSH_CHANNEL_X11_OPEN:
 508                         return i;
 509                 case SSH_CHANNEL_INPUT_DRAINING:
 510                 case SSH_CHANNEL_OUTPUT_DRAINING:
 511                         if (!compat13)
 512                                 fatal("cannot happen: OUT_DRAIN");
 513                         return i;
 514                 default:
 515                         fatal("channel_find_open: bad channel type %d", c->type);
 516                         /* NOTREACHED */
 517                 }
 518         }
 519         return -1;
 520 }
 521
 522
 523 /*
 524  * Returns a message describing the currently open forwarded connections,
 525  * suitable for sending to the client.  The message contains crlf pairs for
 526  * newlines.
 527  */
 528
 529 char *
 530 channel_open_message(void)
 531 {
 532         Buffer buffer;
 533         Channel *c;
 534         char buf[1024], *cp;
 535         u_int i;
 536
 537         buffer_init(&buffer);
 538         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 539         buffer_append(&buffer, buf, strlen(buf));
 540         for (i = 0; i < channels_alloc; i++) {
 541                 c = channels[i];
 542                 if (c == NULL)
 543                         continue;
 544                 switch (c->type) {
 545                 case SSH_CHANNEL_X11_LISTENER:
 546                 case SSH_CHANNEL_PORT_LISTENER:
 547                 case SSH_CHANNEL_RPORT_LISTENER:
 548                 case SSH_CHANNEL_CLOSED:
 549                 case SSH_CHANNEL_AUTH_SOCKET:
 550                 case SSH_CHANNEL_ZOMBIE:
 551                         continue;
 552                 case SSH_CHANNEL_LARVAL:
 553                 case SSH_CHANNEL_OPENING:
 554                 case SSH_CHANNEL_CONNECTING:
 555                 case SSH_CHANNEL_DYNAMIC:
 556                 case SSH_CHANNEL_OPEN:
 557                 case SSH_CHANNEL_X11_OPEN:
 558                 case SSH_CHANNEL_INPUT_DRAINING:
 559                 case SSH_CHANNEL_OUTPUT_DRAINING:
 560                         snprintf(buf, sizeof buf,
 561                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 562                             c->self, c->remote_name,
 563                             c->type, c->remote_id,
 564                             c->istate, buffer_len(&c->input),
 565                             c->ostate, buffer_len(&c->output),
 566                             c->rfd, c->wfd, c->ctl_fd);
 567                         buffer_append(&buffer, buf, strlen(buf));
 568                         continue;
 569                 default:
 570                         fatal("channel_open_message: bad channel type %d", c->type);
 571                         /* NOTREACHED */
 572                 }
 573         }
 574         buffer_append(&buffer, "\0", 1);
 575         cp = xstrdup(buffer_ptr(&buffer));
 576         buffer_free(&buffer);
 577         return cp;
 578 }
 579
 580 void
 581 channel_send_open(int id)
 582 {
 583         Channel *c = channel_lookup(id);
 584
 585         if (c == NULL) {
 586                 logit("channel_send_open: %d: bad id", id);
 587                 return;
 588         }
 589         debug2("channel %d: send open", id);
 590         packet_start(SSH2_MSG_CHANNEL_OPEN);
 591         packet_put_cstring(c->ctype);
 592         packet_put_int(c->self);
 593         packet_put_int(c->local_window);
 594         packet_put_int(c->local_maxpacket);
 595         packet_send();
 596 }
 597
 598 void
 599 channel_request_start(int id, char *service, int wantconfirm)
 600 {
 601         Channel *c = channel_lookup(id);
 602
 603         if (c == NULL) {
 604                 logit("channel_request_start: %d: unknown channel id", id);
 605                 return;
 606         }
 607         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 608         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 609         packet_put_int(c->remote_id);
 610         packet_put_cstring(service);
 611         packet_put_char(wantconfirm);
 612 }
 613 void
 614 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 615 {
 616         Channel *c = channel_lookup(id);
 617
 618         if (c == NULL) {
 619                 logit("channel_register_comfirm: %d: bad id", id);
 620                 return;
 621         }
 622         c->confirm = fn;
 623         c->confirm_ctx = ctx;
 624 }
 625 void
 626 channel_register_cleanup(int id, channel_callback_fn *fn)
 627 {
 628         Channel *c = channel_lookup(id);
 629
 630         if (c == NULL) {
 631                 logit("channel_register_cleanup: %d: bad id", id);
 632                 return;
 633         }
 634         c->detach_user = fn;
 635 }
 636 void
 637 channel_cancel_cleanup(int id)
 638 {
 639         Channel *c = channel_lookup(id);
 640
 641         if (c == NULL) {
 642                 logit("channel_cancel_cleanup: %d: bad id", id);
 643                 return;
 644         }
 645         c->detach_user = NULL;
 646 }
 647 void
 648 channel_register_filter(int id, channel_filter_fn *fn)
 649 {
 650         Channel *c = channel_lookup(id);
 651
 652         if (c == NULL) {
 653                 logit("channel_register_filter: %d: bad id", id);
 654                 return;
 655         }
 656         c->input_filter = fn;
 657 }
 658
 659 void
 660 channel_set_fds(int id, int rfd, int wfd, int efd,
 661     int extusage, int nonblock, u_int window_max)
 662 {
 663         Channel *c = channel_lookup(id);
 664
 665         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 666                 fatal("channel_activate for non-larval channel %d.", id);
 667         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 668         c->type = SSH_CHANNEL_OPEN;
 669         c->local_window = c->local_window_max = window_max;
 670         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 671         packet_put_int(c->remote_id);
 672         packet_put_int(c->local_window);
 673         packet_send();
 674 }
 675
 676 /*
 677  * 'channel_pre*' are called just before select() to add any bits relevant to
 678  * channels in the select bitmasks.
 679  */
 680 /*
 681  * 'channel_post*': perform any appropriate operations for channels which
 682  * have events pending.
 683  */
 684 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 685 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 686 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 687
 688 static void
 689 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 690 {
 691         FD_SET(c->sock, readset);
 692 }
 693
 694 static void
 695 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 696 {
 697         debug3("channel %d: waiting for connection", c->self);
 698         FD_SET(c->sock, writeset);
 699 }
 700
 701 static void
 702 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 703 {
 704         if (buffer_len(&c->input) < packet_get_maxsize())
 705                 FD_SET(c->sock, readset);
 706         if (buffer_len(&c->output) > 0)
 707                 FD_SET(c->sock, writeset);
 708 }
 709
 710 static void
 711 channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
 712 {
 713         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 714
 715         if (c->istate == CHAN_INPUT_OPEN &&
 716             limit > 0 &&
 717             buffer_len(&c->input) < limit)
 718                 FD_SET(c->rfd, readset);
 719         if (c->ostate == CHAN_OUTPUT_OPEN ||
 720             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 721                 if (buffer_len(&c->output) > 0) {
 722                         FD_SET(c->wfd, writeset);
 723                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 724                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 725                                debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 726                                    c->self, c->efd, buffer_len(&c->extended));
 727                         else
 728                                 chan_obuf_empty(c);
 729                 }
 730         }
 731         /** XXX check close conditions, too */
 732         if (compat20 && c->efd != -1) {
 733                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 734                     buffer_len(&c->extended) > 0)
 735                         FD_SET(c->efd, writeset);
 736                 else if (!(c->flags & CHAN_EOF_SENT) &&
 737                     c->extended_usage == CHAN_EXTENDED_READ &&
 738                     buffer_len(&c->extended) < c->remote_window)
 739                         FD_SET(c->efd, readset);
 740         }
 741         /* XXX: What about efd? races? */
 742         if (compat20 && c->ctl_fd != -1 &&
 743             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 744                 FD_SET(c->ctl_fd, readset);
 745 }
 746
 747 static void
 748 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 749 {
 750         if (buffer_len(&c->input) == 0) {
 751                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 752                 packet_put_int(c->remote_id);
 753                 packet_send();
 754                 c->type = SSH_CHANNEL_CLOSED;
 755                 debug2("channel %d: closing after input drain.", c->self);
 756         }
 757 }
 758
 759 static void
 760 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 761 {
 762         if (buffer_len(&c->output) == 0)
 763                 chan_mark_dead(c);
 764         else
 765                 FD_SET(c->sock, writeset);
 766 }
 767
 768 /*
 769  * This is a special state for X11 authentication spoofing.  An opened X11
 770  * connection (when authentication spoofing is being done) remains in this
 771  * state until the first packet has been completely read.  The authentication
 772  * data in that packet is then substituted by the real data if it matches the
 773  * fake data, and the channel is put into normal mode.
 774  * XXX All this happens at the client side.
 775  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 776  */
 777 static int
 778 x11_open_helper(Buffer *b)
 779 {
 780         u_char *ucp;
 781         u_int proto_len, data_len;
 782
 783         /* Check if the fixed size part of the packet is in buffer. */
 784         if (buffer_len(b) < 12)
 785                 return 0;
 786
 787         /* Parse the lengths of variable-length fields. */
 788         ucp = buffer_ptr(b);
 789         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 790                 proto_len = 256 * ucp[6] + ucp[7];
 791                 data_len = 256 * ucp[8] + ucp[9];
 792         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 793                 proto_len = ucp[6] + 256 * ucp[7];
 794                 data_len = ucp[8] + 256 * ucp[9];
 795         } else {
 796                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 797                     ucp[0]);
 798                 return -1;
 799         }
 800
 801         /* Check if the whole packet is in buffer. */
 802         if (buffer_len(b) <
 803             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 804                 return 0;
 805
 806         /* Check if authentication protocol matches. */
 807         if (proto_len != strlen(x11_saved_proto) ||
 808             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 809                 debug2("X11 connection uses different authentication protocol.");
 810                 return -1;
 811         }
 812         /* Check if authentication data matches our fake data. */
 813         if (data_len != x11_fake_data_len ||
 814             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 815                 x11_fake_data, x11_fake_data_len) != 0) {
 816                 debug2("X11 auth data does not match fake data.");
 817                 return -1;
 818         }
 819         /* Check fake data length */
 820         if (x11_fake_data_len != x11_saved_data_len) {
 821                 error("X11 fake_data_len %d != saved_data_len %d",
 822                     x11_fake_data_len, x11_saved_data_len);
 823                 return -1;
 824         }
 825         /*
 826          * Received authentication protocol and data match
 827          * our fake data. Substitute the fake data with real
 828          * data.
 829          */
 830         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 831             x11_saved_data, x11_saved_data_len);
 832         return 1;
 833 }
 834
 835 static void
 836 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 837 {
 838         int ret = x11_open_helper(&c->output);
 839
 840         if (ret == 1) {
 841                 /* Start normal processing for the channel. */
 842                 c->type = SSH_CHANNEL_OPEN;
 843                 channel_pre_open_13(c, readset, writeset);
 844         } else if (ret == -1) {
 845                 /*
 846                  * We have received an X11 connection that has bad
 847                  * authentication information.
 848                  */
 849                 logit("X11 connection rejected because of wrong authentication.");
 850                 buffer_clear(&c->input);
 851                 buffer_clear(&c->output);
 852                 channel_close_fd(&c->sock);
 853                 c->sock = -1;
 854                 c->type = SSH_CHANNEL_CLOSED;
 855                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 856                 packet_put_int(c->remote_id);
 857                 packet_send();
 858         }
 859 }
 860
 861 static void
 862 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
 863 {
 864         int ret = x11_open_helper(&c->output);
 865
 866         /* c->force_drain = 1; */
 867
 868         if (ret == 1) {
 869                 c->type = SSH_CHANNEL_OPEN;
 870                 channel_pre_open(c, readset, writeset);
 871         } else if (ret == -1) {
 872                 logit("X11 connection rejected because of wrong authentication.");
 873                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 874                 chan_read_failed(c);
 875                 buffer_clear(&c->input);
 876                 chan_ibuf_empty(c);
 877                 buffer_clear(&c->output);
 878                 /* for proto v1, the peer will send an IEOF */
 879                 if (compat20)
 880                         chan_write_failed(c);
 881                 else
 882                         c->type = SSH_CHANNEL_OPEN;
 883                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 884         }
 885 }
 886
 887 /* try to decode a socks4 header */
 888 static int
 889 channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
 890 {
 891         char *p, *host;
 892         int len, have, i, found;
 893         char username[256];
 894         struct {
 895                 u_int8_t version;
 896                 u_int8_t command;
 897                 u_int16_t dest_port;
 898                 struct in_addr dest_addr;
 899         } s4_req, s4_rsp;
 900
 901         debug2("channel %d: decode socks4", c->self);
 902
 903         have = buffer_len(&c->input);
 904         len = sizeof(s4_req);
 905         if (have < len)
 906                 return 0;
 907         p = buffer_ptr(&c->input);
 908         for (found = 0, i = len; i < have; i++) {
 909                 if (p[i] == '\0') {
 910                         found = 1;
 911                         break;
 912                 }
 913                 if (i > 1024) {
 914                         /* the peer is probably sending garbage */
 915                         debug("channel %d: decode socks4: too long",
 916                             c->self);
 917                         return -1;
 918                 }
 919         }
 920         if (!found)
 921                 return 0;
 922         buffer_get(&c->input, (char *)&s4_req.version, 1);
 923         buffer_get(&c->input, (char *)&s4_req.command, 1);
 924         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 925         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 926         have = buffer_len(&c->input);
 927         p = buffer_ptr(&c->input);
 928         len = strlen(p);
 929         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 930         if (len > have)
 931                 fatal("channel %d: decode socks4: len %d > have %d",
 932                     c->self, len, have);
 933         strlcpy(username, p, sizeof(username));
 934         buffer_consume(&c->input, len);
 935         buffer_consume(&c->input, 1);           /* trailing '\0' */
 936
 937         host = inet_ntoa(s4_req.dest_addr);
 938         strlcpy(c->path, host, sizeof(c->path));
 939         c->host_port = ntohs(s4_req.dest_port);
 940
 941         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 942             c->self, host, c->host_port, s4_req.command);
 943
 944         if (s4_req.command != 1) {
 945                 debug("channel %d: cannot handle: socks4 cn %d",
 946                     c->self, s4_req.command);
 947                 return -1;
 948         }
 949         s4_rsp.version = 0;                     /* vn: 0 for reply */
 950         s4_rsp.command = 90;                    /* cd: req granted */
 951         s4_rsp.dest_port = 0;                   /* ignored */
 952         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 953         buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
 954         return 1;
 955 }
 956
 957 /* try to decode a socks5 header */
 958 #define SSH_SOCKS5_AUTHDONE     0x1000
 959 #define SSH_SOCKS5_NOAUTH       0x00
 960 #define SSH_SOCKS5_IPV4         0x01
 961 #define SSH_SOCKS5_DOMAIN       0x03
 962 #define SSH_SOCKS5_IPV6         0x04
 963 #define SSH_SOCKS5_CONNECT      0x01
 964 #define SSH_SOCKS5_SUCCESS      0x00
 965
 966 static int
 967 channel_decode_socks5(Channel *c, fd_set * readset, fd_set * writeset)
 968 {
 969         struct {
 970                 u_int8_t version;
 971                 u_int8_t command;
 972                 u_int8_t reserved;
 973                 u_int8_t atyp;
 974         } s5_req, s5_rsp;
 975         u_int16_t dest_port;
 976         u_char *p, dest_addr[255+1];
 977         int i, have, found, nmethods, addrlen, af;
 978
 979         debug2("channel %d: decode socks5", c->self);
 980         p = buffer_ptr(&c->input);
 981         if (p[0] != 0x05)
 982                 return -1;
 983         have = buffer_len(&c->input);
 984         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
 985                 /* format: ver | nmethods | methods */
 986                 if (have < 2)
 987                         return 0;
 988                 nmethods = p[1];
 989                 if (have < nmethods + 2)
 990                         return 0;
 991                 /* look for method: "NO AUTHENTICATION REQUIRED" */
 992                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
 993                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
 994                                 found = 1;
 995                                 break;
 996                         }
 997                 }
 998                 if (!found) {
 999                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1000                             c->self);
1001                         return -1;
1002                 }
1003                 buffer_consume(&c->input, nmethods + 2);
1004                 buffer_put_char(&c->output, 0x05);              /* version */
1005                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1006                 FD_SET(c->sock, writeset);
1007                 c->flags |= SSH_SOCKS5_AUTHDONE;
1008                 debug2("channel %d: socks5 auth done", c->self);
1009                 return 0;                               /* need more */
1010         }
1011         debug2("channel %d: socks5 post auth", c->self);
1012         if (have < sizeof(s5_req)+1)
1013                 return 0;                       /* need more */
1014         memcpy((char *)&s5_req, p, sizeof(s5_req));
1015         if (s5_req.version != 0x05 ||
1016             s5_req.command != SSH_SOCKS5_CONNECT ||
1017             s5_req.reserved != 0x00) {
1018                 debug2("channel %d: only socks5 connect supported", c->self);
1019                 return -1;
1020         }
1021         switch(s5_req.atyp){
1022         case SSH_SOCKS5_IPV4:
1023                 addrlen = 4;
1024                 af = AF_INET;
1025                 break;
1026         case SSH_SOCKS5_DOMAIN:
1027                 addrlen = p[sizeof(s5_req)];
1028                 af = -1;
1029                 break;
1030         case SSH_SOCKS5_IPV6:
1031                 addrlen = 16;
1032                 af = AF_INET6;
1033                 break;
1034         default:
1035                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1036                 return -1;
1037         }
1038         if (have < 4 + addrlen + 2)
1039                 return 0;
1040         buffer_consume(&c->input, sizeof(s5_req));
1041         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1042                 buffer_consume(&c->input, 1);    /* host string length */
1043         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1044         buffer_get(&c->input, (char *)&dest_port, 2);
1045         dest_addr[addrlen] = '\0';
1046         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1047                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1048         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1049                 return -1;
1050         c->host_port = ntohs(dest_port);
1051
1052         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1053             c->self, c->path, c->host_port, s5_req.command);
1054
1055         s5_rsp.version = 0x05;
1056         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1057         s5_rsp.reserved = 0;                    /* ignored */
1058         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1059         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1060         dest_port = 0;                          /* ignored */
1061
1062         buffer_append(&c->output, (char *)&s5_rsp, sizeof(s5_rsp));
1063         buffer_append(&c->output, (char *)&dest_addr, sizeof(struct in_addr));
1064         buffer_append(&c->output, (char *)&dest_port, sizeof(dest_port));
1065         return 1;
1066 }
1067
1068 /* dynamic port forwarding */
1069 static void
1070 channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
1071 {
1072         u_char *p;
1073         int have, ret;
1074
1075         have = buffer_len(&c->input);
1076         c->delayed = 0;
1077         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1078         /* buffer_dump(&c->input); */
1079         /* check if the fixed size part of the packet is in buffer. */
1080         if (have < 3) {
1081                 /* need more */
1082                 FD_SET(c->sock, readset);
1083                 return;
1084         }
1085         /* try to guess the protocol */
1086         p = buffer_ptr(&c->input);
1087         switch (p[0]) {
1088         case 0x04:
1089                 ret = channel_decode_socks4(c, readset, writeset);
1090                 break;
1091         case 0x05:
1092                 ret = channel_decode_socks5(c, readset, writeset);
1093                 break;
1094         default:
1095                 ret = -1;
1096                 break;
1097         }
1098         if (ret < 0) {
1099                 chan_mark_dead(c);
1100         } else if (ret == 0) {
1101                 debug2("channel %d: pre_dynamic: need more", c->self);
1102                 /* need more */
1103                 FD_SET(c->sock, readset);
1104         } else {
1105                 /* switch to the next state */
1106                 c->type = SSH_CHANNEL_OPENING;
1107                 port_open_helper(c, "direct-tcpip");
1108         }
1109 }
1110
1111 /* This is our fake X11 server socket. */
1112 static void
1113 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
1114 {
1115         Channel *nc;
1116         struct sockaddr addr;
1117         int newsock;
1118         socklen_t addrlen;
1119         char buf[16384], *remote_ipaddr;
1120         int remote_port;
1121
1122         if (FD_ISSET(c->sock, readset)) {
1123                 debug("X11 connection requested.");
1124                 addrlen = sizeof(addr);
1125                 newsock = accept(c->sock, &addr, &addrlen);
1126                 if (c->single_connection) {
1127                         debug2("single_connection: closing X11 listener.");
1128                         channel_close_fd(&c->sock);
1129                         chan_mark_dead(c);
1130                 }
1131                 if (newsock < 0) {
1132                         error("accept: %.100s", strerror(errno));
1133                         return;
1134                 }
1135                 set_nodelay(newsock);
1136                 remote_ipaddr = get_peer_ipaddr(newsock);
1137                 remote_port = get_peer_port(newsock);
1138                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1139                     remote_ipaddr, remote_port);
1140
1141                 nc = channel_new("accepted x11 socket",
1142                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1143                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1144                 if (compat20) {
1145                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1146                         packet_put_cstring("x11");
1147                         packet_put_int(nc->self);
1148                         packet_put_int(nc->local_window_max);
1149                         packet_put_int(nc->local_maxpacket);
1150                         /* originator ipaddr and port */
1151                         packet_put_cstring(remote_ipaddr);
1152                         if (datafellows & SSH_BUG_X11FWD) {
1153                                 debug2("ssh2 x11 bug compat mode");
1154                         } else {
1155                                 packet_put_int(remote_port);
1156                         }
1157                         packet_send();
1158                 } else {
1159                         packet_start(SSH_SMSG_X11_OPEN);
1160                         packet_put_int(nc->self);
1161                         if (packet_get_protocol_flags() &
1162                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1163                                 packet_put_cstring(buf);
1164                         packet_send();
1165                 }
1166                 xfree(remote_ipaddr);
1167         }
1168 }
1169
1170 static void
1171 port_open_helper(Channel *c, char *rtype)
1172 {
1173         int direct;
1174         char buf[1024];
1175         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1176         u_short remote_port = get_peer_port(c->sock);
1177
1178         direct = (strcmp(rtype, "direct-tcpip") == 0);
1179
1180         snprintf(buf, sizeof buf,
1181             "%s: listening port %d for %.100s port %d, "
1182             "connect from %.200s port %d",
1183             rtype, c->listening_port, c->path, c->host_port,
1184             remote_ipaddr, remote_port);
1185
1186         xfree(c->remote_name);
1187         c->remote_name = xstrdup(buf);
1188
1189         if (compat20) {
1190                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1191                 packet_put_cstring(rtype);
1192                 packet_put_int(c->self);
1193                 packet_put_int(c->local_window_max);
1194                 packet_put_int(c->local_maxpacket);
1195                 if (direct) {
1196                         /* target host, port */
1197                         packet_put_cstring(c->path);
1198                         packet_put_int(c->host_port);
1199                 } else {
1200                         /* listen address, port */
1201                         packet_put_cstring(c->path);
1202                         packet_put_int(c->listening_port);
1203                 }
1204                 /* originator host and port */
1205                 packet_put_cstring(remote_ipaddr);
1206                 packet_put_int(remote_port);
1207                 packet_send();
1208         } else {
1209                 packet_start(SSH_MSG_PORT_OPEN);
1210                 packet_put_int(c->self);
1211                 packet_put_cstring(c->path);
1212                 packet_put_int(c->host_port);
1213                 if (packet_get_protocol_flags() &
1214                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1215                         packet_put_cstring(c->remote_name);
1216                 packet_send();
1217         }
1218         xfree(remote_ipaddr);
1219 }
1220
1221 /*
1222  * This socket is listening for connections to a forwarded TCP/IP port.
1223  */
1224 static void
1225 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
1226 {
1227         Channel *nc;
1228         struct sockaddr addr;
1229         int newsock, nextstate;
1230         socklen_t addrlen;
1231         char *rtype;
1232
1233         if (FD_ISSET(c->sock, readset)) {
1234                 debug("Connection to port %d forwarding "
1235                     "to %.100s port %d requested.",
1236                     c->listening_port, c->path, c->host_port);
1237
1238                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1239                         nextstate = SSH_CHANNEL_OPENING;
1240                         rtype = "forwarded-tcpip";
1241                 } else {
1242                         if (c->host_port == 0) {
1243                                 nextstate = SSH_CHANNEL_DYNAMIC;
1244                                 rtype = "dynamic-tcpip";
1245                         } else {
1246                                 nextstate = SSH_CHANNEL_OPENING;
1247                                 rtype = "direct-tcpip";
1248                         }
1249                 }
1250
1251                 addrlen = sizeof(addr);
1252                 newsock = accept(c->sock, &addr, &addrlen);
1253                 if (newsock < 0) {
1254                         error("accept: %.100s", strerror(errno));
1255                         return;
1256                 }
1257                 set_nodelay(newsock);
1258                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1259                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1260                 nc->listening_port = c->listening_port;
1261                 nc->host_port = c->host_port;
1262                 strlcpy(nc->path, c->path, sizeof(nc->path));
1263
1264                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1265                         /*
1266                          * do not call the channel_post handler until
1267                          * this flag has been reset by a pre-handler.
1268                          * otherwise the FD_ISSET calls might overflow
1269                          */
1270                         nc->delayed = 1;
1271                 } else {
1272                         port_open_helper(nc, rtype);
1273                 }
1274         }
1275 }
1276
1277 /*
1278  * This is the authentication agent socket listening for connections from
1279  * clients.
1280  */
1281 static void
1282 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
1283 {
1284         Channel *nc;
1285         int newsock;
1286         struct sockaddr addr;
1287         socklen_t addrlen;
1288
1289         if (FD_ISSET(c->sock, readset)) {
1290                 addrlen = sizeof(addr);
1291                 newsock = accept(c->sock, &addr, &addrlen);
1292                 if (newsock < 0) {
1293                         error("accept from auth socket: %.100s", strerror(errno));
1294                         return;
1295                 }
1296                 nc = channel_new("accepted auth socket",
1297                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1298                     c->local_window_max, c->local_maxpacket,
1299                     0, "accepted auth socket", 1);
1300                 if (compat20) {
1301                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1302                         packet_put_cstring("auth-agent@openssh.com");
1303                         packet_put_int(nc->self);
1304                         packet_put_int(c->local_window_max);
1305                         packet_put_int(c->local_maxpacket);
1306                 } else {
1307                         packet_start(SSH_SMSG_AGENT_OPEN);
1308                         packet_put_int(nc->self);
1309                 }
1310                 packet_send();
1311         }
1312 }
1313
1314 static void
1315 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
1316 {
1317         int err = 0;
1318         socklen_t sz = sizeof(err);
1319
1320         if (FD_ISSET(c->sock, writeset)) {
1321                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1322                         err = errno;
1323                         error("getsockopt SO_ERROR failed");
1324                 }
1325                 if (err == 0) {
1326                         debug("channel %d: connected", c->self);
1327                         c->type = SSH_CHANNEL_OPEN;
1328                         if (compat20) {
1329                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1330                                 packet_put_int(c->remote_id);
1331                                 packet_put_int(c->self);
1332                                 packet_put_int(c->local_window);
1333                                 packet_put_int(c->local_maxpacket);
1334                         } else {
1335                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1336                                 packet_put_int(c->remote_id);
1337                                 packet_put_int(c->self);
1338                         }
1339                 } else {
1340                         debug("channel %d: not connected: %s",
1341                             c->self, strerror(err));
1342                         if (compat20) {
1343                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1344                                 packet_put_int(c->remote_id);
1345                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1346                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1347                                         packet_put_cstring(strerror(err));
1348                                         packet_put_cstring("");
1349                                 }
1350                         } else {
1351                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1352                                 packet_put_int(c->remote_id);
1353                         }
1354                         chan_mark_dead(c);
1355                 }
1356                 packet_send();
1357         }
1358 }
1359
1360 static int
1361 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
1362 {
1363         char buf[16*1024];
1364         int len;
1365
1366         if (c->rfd != -1 &&
1367             FD_ISSET(c->rfd, readset)) {
1368                 len = read(c->rfd, buf, sizeof(buf));
1369                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1370                         return 1;
1371                 if (len <= 0) {
1372                         debug2("channel %d: read<=0 rfd %d len %d",
1373                             c->self, c->rfd, len);
1374                         if (c->type != SSH_CHANNEL_OPEN) {
1375                                 debug2("channel %d: not open", c->self);
1376                                 chan_mark_dead(c);
1377                                 return -1;
1378                         } else if (compat13) {
1379                                 buffer_clear(&c->output);
1380                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1381                                 debug2("channel %d: input draining.", c->self);
1382                         } else {
1383                                 chan_read_failed(c);
1384                         }
1385                         return -1;
1386                 }
1387                 if (c->input_filter != NULL) {
1388                         if (c->input_filter(c, buf, len) == -1) {
1389                                 debug2("channel %d: filter stops", c->self);
1390                                 chan_read_failed(c);
1391                         }
1392                 } else {
1393                         buffer_append(&c->input, buf, len);
1394                 }
1395         }
1396         return 1;
1397 }
1398 static int
1399 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
1400 {
1401         struct termios tio;
1402         u_char *data;
1403         u_int dlen;
1404         int len;
1405
1406         /* Send buffered output data to the socket. */
1407         if (c->wfd != -1 &&
1408             FD_ISSET(c->wfd, writeset) &&
1409             buffer_len(&c->output) > 0) {
1410                 data = buffer_ptr(&c->output);
1411                 dlen = buffer_len(&c->output);
1412 #ifdef _AIX
1413                 /* XXX: Later AIX versions can't push as much data to tty */
1414                 if (compat20 && c->wfd_isatty)
1415                         dlen = MIN(dlen, 8*1024);
1416 #endif
1417                 len = write(c->wfd, data, dlen);
1418                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1419                         return 1;
1420                 if (len <= 0) {
1421                         if (c->type != SSH_CHANNEL_OPEN) {
1422                                 debug2("channel %d: not open", c->self);
1423                                 chan_mark_dead(c);
1424                                 return -1;
1425                         } else if (compat13) {
1426                                 buffer_clear(&c->output);
1427                                 debug2("channel %d: input draining.", c->self);
1428                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1429                         } else {
1430                                 chan_write_failed(c);
1431                         }
1432                         return -1;
1433                 }
1434                 if (compat20 && c->isatty && dlen >= 1 && data[0] != '\r') {
1435                         if (tcgetattr(c->wfd, &tio) == 0 &&
1436                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1437                                 /*
1438                                  * Simulate echo to reduce the impact of
1439                                  * traffic analysis. We need to match the
1440                                  * size of a SSH2_MSG_CHANNEL_DATA message
1441                                  * (4 byte channel id + data)
1442                                  */
1443                                 packet_send_ignore(4 + len);
1444                                 packet_send();
1445                         }
1446                 }
1447                 buffer_consume(&c->output, len);
1448                 if (compat20 && len > 0) {
1449                         c->local_consumed += len;
1450                 }
1451         }
1452         return 1;
1453 }
1454 static int
1455 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
1456 {
1457         char buf[16*1024];
1458         int len;
1459
1460 /** XXX handle drain efd, too */
1461         if (c->efd != -1) {
1462                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1463                     FD_ISSET(c->efd, writeset) &&
1464                     buffer_len(&c->extended) > 0) {
1465                         len = write(c->efd, buffer_ptr(&c->extended),
1466                             buffer_len(&c->extended));
1467                         debug2("channel %d: written %d to efd %d",
1468                             c->self, len, c->efd);
1469                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1470                                 return 1;
1471                         if (len <= 0) {
1472                                 debug2("channel %d: closing write-efd %d",
1473                                     c->self, c->efd);
1474                                 channel_close_fd(&c->efd);
1475                         } else {
1476                                 buffer_consume(&c->extended, len);
1477                                 c->local_consumed += len;
1478                         }
1479                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1480                     FD_ISSET(c->efd, readset)) {
1481                         len = read(c->efd, buf, sizeof(buf));
1482                         debug2("channel %d: read %d from efd %d",
1483                             c->self, len, c->efd);
1484                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1485                                 return 1;
1486                         if (len <= 0) {
1487                                 debug2("channel %d: closing read-efd %d",
1488                                     c->self, c->efd);
1489                                 channel_close_fd(&c->efd);
1490                         } else {
1491                                 buffer_append(&c->extended, buf, len);
1492                         }
1493                 }
1494         }
1495         return 1;
1496 }
1497 static int
1498 channel_handle_ctl(Channel *c, fd_set * readset, fd_set * writeset)
1499 {
1500         char buf[16];
1501         int len;
1502
1503         /* Monitor control fd to detect if the slave client exits */
1504         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1505                 len = read(c->ctl_fd, buf, sizeof(buf));
1506                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1507                         return 1;
1508                 if (len <= 0) {
1509                         debug2("channel %d: ctl read<=0", c->self);
1510                         if (c->type != SSH_CHANNEL_OPEN) {
1511                                 debug2("channel %d: not open", c->self);
1512                                 chan_mark_dead(c);
1513                                 return -1;
1514                         } else {
1515                                 chan_read_failed(c);
1516                                 chan_write_failed(c);
1517                         }
1518                         return -1;
1519                 } else
1520                         fatal("%s: unexpected data on ctl fd", __func__);
1521         }
1522         return 1;
1523 }
1524 static int
1525 channel_check_window(Channel *c)
1526 {
1527         if (c->type == SSH_CHANNEL_OPEN &&
1528             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1529             c->local_window < c->local_window_max/2 &&
1530             c->local_consumed > 0) {
1531                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1532                 packet_put_int(c->remote_id);
1533                 packet_put_int(c->local_consumed);
1534                 packet_send();
1535                 debug2("channel %d: window %d sent adjust %d",
1536                     c->self, c->local_window,
1537                     c->local_consumed);
1538                 c->local_window += c->local_consumed;
1539                 c->local_consumed = 0;
1540         }
1541         return 1;
1542 }
1543
1544 static void
1545 channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
1546 {
1547         if (c->delayed)
1548                 return;
1549         channel_handle_rfd(c, readset, writeset);
1550         channel_handle_wfd(c, readset, writeset);
1551         if (!compat20)
1552                 return;
1553         channel_handle_efd(c, readset, writeset);
1554         channel_handle_ctl(c, readset, writeset);
1555         channel_check_window(c);
1556 }
1557
1558 static void
1559 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
1560 {
1561         int len;
1562
1563         /* Send buffered output data to the socket. */
1564         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1565                 len = write(c->sock, buffer_ptr(&c->output),
1566                             buffer_len(&c->output));
1567                 if (len <= 0)
1568                         buffer_clear(&c->output);
1569                 else
1570                         buffer_consume(&c->output, len);
1571         }
1572 }
1573
1574 static void
1575 channel_handler_init_20(void)
1576 {
1577         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1578         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1579         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1580         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1581         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1582         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1583         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1584         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1585
1586         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1587         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1588         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1589         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1590         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1591         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1592         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1593 }
1594
1595 static void
1596 channel_handler_init_13(void)
1597 {
1598         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1599         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1600         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1601         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1602         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1603         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1604         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1605         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1606         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1607
1608         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1609         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1610         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1611         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1612         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1613         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1614         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1615 }
1616
1617 static void
1618 channel_handler_init_15(void)
1619 {
1620         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1621         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1622         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1623         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1624         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1625         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1626         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1627
1628         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1629         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1630         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1631         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1632         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1633         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1634 }
1635
1636 static void
1637 channel_handler_init(void)
1638 {
1639         int i;
1640
1641         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1642                 channel_pre[i] = NULL;
1643                 channel_post[i] = NULL;
1644         }
1645         if (compat20)
1646                 channel_handler_init_20();
1647         else if (compat13)
1648                 channel_handler_init_13();
1649         else
1650                 channel_handler_init_15();
1651 }
1652
1653 /* gc dead channels */
1654 static void
1655 channel_garbage_collect(Channel *c)
1656 {
1657         if (c == NULL)
1658                 return;
1659         if (c->detach_user != NULL) {
1660                 if (!chan_is_dead(c, 0))
1661                         return;
1662                 debug2("channel %d: gc: notify user", c->self);
1663                 c->detach_user(c->self, NULL);
1664                 /* if we still have a callback */
1665                 if (c->detach_user != NULL)
1666                         return;
1667                 debug2("channel %d: gc: user detached", c->self);
1668         }
1669         if (!chan_is_dead(c, 1))
1670                 return;
1671         debug2("channel %d: garbage collecting", c->self);
1672         channel_free(c);
1673 }
1674
1675 static void
1676 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
1677 {
1678         static int did_init = 0;
1679         u_int i;
1680         Channel *c;
1681
1682         if (!did_init) {
1683                 channel_handler_init();
1684                 did_init = 1;
1685         }
1686         for (i = 0; i < channels_alloc; i++) {
1687                 c = channels[i];
1688                 if (c == NULL)
1689                         continue;
1690                 if (ftab[c->type] != NULL)
1691                         (*ftab[c->type])(c, readset, writeset);
1692                 channel_garbage_collect(c);
1693         }
1694 }
1695
1696 /*
1697  * Allocate/update select bitmasks and add any bits relevant to channels in
1698  * select bitmasks.
1699  */
1700 void
1701 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1702     u_int *nallocp, int rekeying)
1703 {
1704         u_int n, sz;
1705
1706         n = MAX(*maxfdp, channel_max_fd);
1707
1708         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
1709         /* perhaps check sz < nalloc/2 and shrink? */
1710         if (*readsetp == NULL || sz > *nallocp) {
1711                 *readsetp = xrealloc(*readsetp, sz);
1712                 *writesetp = xrealloc(*writesetp, sz);
1713                 *nallocp = sz;
1714         }
1715         *maxfdp = n;
1716         memset(*readsetp, 0, sz);
1717         memset(*writesetp, 0, sz);
1718
1719         if (!rekeying)
1720                 channel_handler(channel_pre, *readsetp, *writesetp);
1721 }
1722
1723 /*
1724  * After select, perform any appropriate operations for channels which have
1725  * events pending.
1726  */
1727 void
1728 channel_after_select(fd_set * readset, fd_set * writeset)
1729 {
1730         channel_handler(channel_post, readset, writeset);
1731 }
1732
1733
1734 /* If there is data to send to the connection, enqueue some of it now. */
1735
1736 void
1737 channel_output_poll(void)
1738 {
1739         Channel *c;
1740         u_int i, len;
1741
1742         for (i = 0; i < channels_alloc; i++) {
1743                 c = channels[i];
1744                 if (c == NULL)
1745                         continue;
1746
1747                 /*
1748                  * We are only interested in channels that can have buffered
1749                  * incoming data.
1750                  */
1751                 if (compat13) {
1752                         if (c->type != SSH_CHANNEL_OPEN &&
1753                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1754                                 continue;
1755                 } else {
1756                         if (c->type != SSH_CHANNEL_OPEN)
1757                                 continue;
1758                 }
1759                 if (compat20 &&
1760                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1761                         /* XXX is this true? */
1762                         debug3("channel %d: will not send data after close", c->self);
1763                         continue;
1764                 }
1765
1766                 /* Get the amount of buffered data for this channel. */
1767                 if ((c->istate == CHAN_INPUT_OPEN ||
1768                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1769                     (len = buffer_len(&c->input)) > 0) {
1770                         /*
1771                          * Send some data for the other side over the secure
1772                          * connection.
1773                          */
1774                         if (compat20) {
1775                                 if (len > c->remote_window)
1776                                         len = c->remote_window;
1777                                 if (len > c->remote_maxpacket)
1778                                         len = c->remote_maxpacket;
1779                         } else {
1780                                 if (packet_is_interactive()) {
1781                                         if (len > 1024)
1782                                                 len = 512;
1783                                 } else {
1784                                         /* Keep the packets at reasonable size. */
1785                                         if (len > packet_get_maxsize()/2)
1786                                                 len = packet_get_maxsize()/2;
1787                                 }
1788                         }
1789                         if (len > 0) {
1790                                 packet_start(compat20 ?
1791                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1792                                 packet_put_int(c->remote_id);
1793                                 packet_put_string(buffer_ptr(&c->input), len);
1794                                 packet_send();
1795                                 buffer_consume(&c->input, len);
1796                                 c->remote_window -= len;
1797                         }
1798                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1799                         if (compat13)
1800                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1801                         /*
1802                          * input-buffer is empty and read-socket shutdown:
1803                          * tell peer, that we will not send more data: send IEOF.
1804                          * hack for extended data: delay EOF if EFD still in use.
1805                          */
1806                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1807                                debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1808                                    c->self, c->efd, buffer_len(&c->extended));
1809                         else
1810                                 chan_ibuf_empty(c);
1811                 }
1812                 /* Send extended data, i.e. stderr */
1813                 if (compat20 &&
1814                     !(c->flags & CHAN_EOF_SENT) &&
1815                     c->remote_window > 0 &&
1816                     (len = buffer_len(&c->extended)) > 0 &&
1817                     c->extended_usage == CHAN_EXTENDED_READ) {
1818                         debug2("channel %d: rwin %u elen %u euse %d",
1819                             c->self, c->remote_window, buffer_len(&c->extended),
1820                             c->extended_usage);
1821                         if (len > c->remote_window)
1822                                 len = c->remote_window;
1823                         if (len > c->remote_maxpacket)
1824                                 len = c->remote_maxpacket;
1825                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1826                         packet_put_int(c->remote_id);
1827                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1828                         packet_put_string(buffer_ptr(&c->extended), len);
1829                         packet_send();
1830                         buffer_consume(&c->extended, len);
1831                         c->remote_window -= len;
1832                         debug2("channel %d: sent ext data %d", c->self, len);
1833                 }
1834         }
1835 }
1836
1837
1838 /* -- protocol input */
1839
1840 void
1841 channel_input_data(int type, u_int32_t seq, void *ctxt)
1842 {
1843         int id;
1844         char *data;
1845         u_int data_len;
1846         Channel *c;
1847
1848         /* Get the channel number and verify it. */
1849         id = packet_get_int();
1850         c = channel_lookup(id);
1851         if (c == NULL)
1852                 packet_disconnect("Received data for nonexistent channel %d.", id);
1853
1854         /* Ignore any data for non-open channels (might happen on close) */
1855         if (c->type != SSH_CHANNEL_OPEN &&
1856             c->type != SSH_CHANNEL_X11_OPEN)
1857                 return;
1858
1859         /* Get the data. */
1860         data = packet_get_string(&data_len);
1861
1862         /*
1863          * Ignore data for protocol > 1.3 if output end is no longer open.
1864          * For protocol 2 the sending side is reducing its window as it sends
1865          * data, so we must 'fake' consumption of the data in order to ensure
1866          * that window updates are sent back.  Otherwise the connection might
1867          * deadlock.
1868          */
1869         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1870                 if (compat20) {
1871                         c->local_window -= data_len;
1872                         c->local_consumed += data_len;
1873                 }
1874                 xfree(data);
1875                 return;
1876         }
1877
1878         if (compat20) {
1879                 if (data_len > c->local_maxpacket) {
1880                         logit("channel %d: rcvd big packet %d, maxpack %d",
1881                             c->self, data_len, c->local_maxpacket);
1882                 }
1883                 if (data_len > c->local_window) {
1884                         logit("channel %d: rcvd too much data %d, win %d",
1885                             c->self, data_len, c->local_window);
1886                         xfree(data);
1887                         return;
1888                 }
1889                 c->local_window -= data_len;
1890         }
1891         packet_check_eom();
1892         buffer_append(&c->output, data, data_len);
1893         xfree(data);
1894 }
1895
1896 void
1897 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
1898 {
1899         int id;
1900         char *data;
1901         u_int data_len, tcode;
1902         Channel *c;
1903
1904         /* Get the channel number and verify it. */
1905         id = packet_get_int();
1906         c = channel_lookup(id);
1907
1908         if (c == NULL)
1909                 packet_disconnect("Received extended_data for bad channel %d.", id);
1910         if (c->type != SSH_CHANNEL_OPEN) {
1911                 logit("channel %d: ext data for non open", id);
1912                 return;
1913         }
1914         if (c->flags & CHAN_EOF_RCVD) {
1915                 if (datafellows & SSH_BUG_EXTEOF)
1916                         debug("channel %d: accepting ext data after eof", id);
1917                 else
1918                         packet_disconnect("Received extended_data after EOF "
1919                             "on channel %d.", id);
1920         }
1921         tcode = packet_get_int();
1922         if (c->efd == -1 ||
1923             c->extended_usage != CHAN_EXTENDED_WRITE ||
1924             tcode != SSH2_EXTENDED_DATA_STDERR) {
1925                 logit("channel %d: bad ext data", c->self);
1926                 return;
1927         }
1928         data = packet_get_string(&data_len);
1929         packet_check_eom();
1930         if (data_len > c->local_window) {
1931                 logit("channel %d: rcvd too much extended_data %d, win %d",
1932                     c->self, data_len, c->local_window);
1933                 xfree(data);
1934                 return;
1935         }
1936         debug2("channel %d: rcvd ext data %d", c->self, data_len);
1937         c->local_window -= data_len;
1938         buffer_append(&c->extended, data, data_len);
1939         xfree(data);
1940 }
1941
1942 void
1943 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
1944 {
1945         int id;
1946         Channel *c;
1947
1948         id = packet_get_int();
1949         packet_check_eom();
1950         c = channel_lookup(id);
1951         if (c == NULL)
1952                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
1953         chan_rcvd_ieof(c);
1954
1955         /* XXX force input close */
1956         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
1957                 debug("channel %d: FORCE input drain", c->self);
1958                 c->istate = CHAN_INPUT_WAIT_DRAIN;
1959                 if (buffer_len(&c->input) == 0)
1960                         chan_ibuf_empty(c);
1961         }
1962
1963 }
1964
1965 void
1966 channel_input_close(int type, u_int32_t seq, void *ctxt)
1967 {
1968         int id;
1969         Channel *c;
1970
1971         id = packet_get_int();
1972         packet_check_eom();
1973         c = channel_lookup(id);
1974         if (c == NULL)
1975                 packet_disconnect("Received close for nonexistent channel %d.", id);
1976
1977         /*
1978          * Send a confirmation that we have closed the channel and no more
1979          * data is coming for it.
1980          */
1981         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
1982         packet_put_int(c->remote_id);
1983         packet_send();
1984
1985         /*
1986          * If the channel is in closed state, we have sent a close request,
1987          * and the other side will eventually respond with a confirmation.
1988          * Thus, we cannot free the channel here, because then there would be
1989          * no-one to receive the confirmation.  The channel gets freed when
1990          * the confirmation arrives.
1991          */
1992         if (c->type != SSH_CHANNEL_CLOSED) {
1993                 /*
1994                  * Not a closed channel - mark it as draining, which will
1995                  * cause it to be freed later.
1996                  */
1997                 buffer_clear(&c->input);
1998                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
1999         }
2000 }
2001
2002 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2003 void
2004 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2005 {
2006         int id = packet_get_int();
2007         Channel *c = channel_lookup(id);
2008
2009         packet_check_eom();
2010         if (c == NULL)
2011                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2012         chan_rcvd_oclose(c);
2013 }
2014
2015 void
2016 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2017 {
2018         int id = packet_get_int();
2019         Channel *c = channel_lookup(id);
2020
2021         packet_check_eom();
2022         if (c == NULL)
2023                 packet_disconnect("Received close confirmation for "
2024                     "out-of-range channel %d.", id);
2025         if (c->type != SSH_CHANNEL_CLOSED)
2026                 packet_disconnect("Received close confirmation for "
2027                     "non-closed channel %d (type %d).", id, c->type);
2028         channel_free(c);
2029 }
2030
2031 void
2032 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2033 {
2034         int id, remote_id;
2035         Channel *c;
2036
2037         id = packet_get_int();
2038         c = channel_lookup(id);
2039
2040         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2041                 packet_disconnect("Received open confirmation for "
2042                     "non-opening channel %d.", id);
2043         remote_id = packet_get_int();
2044         /* Record the remote channel number and mark that the channel is now open. */
2045         c->remote_id = remote_id;
2046         c->type = SSH_CHANNEL_OPEN;
2047
2048         if (compat20) {
2049                 c->remote_window = packet_get_int();
2050                 c->remote_maxpacket = packet_get_int();
2051                 if (c->confirm) {
2052                         debug2("callback start");
2053                         c->confirm(c->self, c->confirm_ctx);
2054                         debug2("callback done");
2055                 }
2056                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2057                     c->remote_window, c->remote_maxpacket);
2058         }
2059         packet_check_eom();
2060 }
2061
2062 static char *
2063 reason2txt(int reason)
2064 {
2065         switch (reason) {
2066         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2067                 return "administratively prohibited";
2068         case SSH2_OPEN_CONNECT_FAILED:
2069                 return "connect failed";
2070         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2071                 return "unknown channel type";
2072         case SSH2_OPEN_RESOURCE_SHORTAGE:
2073                 return "resource shortage";
2074         }
2075         return "unknown reason";
2076 }
2077
2078 void
2079 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2080 {
2081         int id, reason;
2082         char *msg = NULL, *lang = NULL;
2083         Channel *c;
2084
2085         id = packet_get_int();
2086         c = channel_lookup(id);
2087
2088         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2089                 packet_disconnect("Received open failure for "
2090                     "non-opening channel %d.", id);
2091         if (compat20) {
2092                 reason = packet_get_int();
2093                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2094                         msg  = packet_get_string(NULL);
2095                         lang = packet_get_string(NULL);
2096                 }
2097                 logit("channel %d: open failed: %s%s%s", id,
2098                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2099                 if (msg != NULL)
2100                         xfree(msg);
2101                 if (lang != NULL)
2102                         xfree(lang);
2103         }
2104         packet_check_eom();
2105         /* Free the channel.  This will also close the socket. */
2106         channel_free(c);
2107 }
2108
2109 void
2110 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2111 {
2112         Channel *c;
2113         int id;
2114         u_int adjust;
2115
2116         if (!compat20)
2117                 return;
2118
2119         /* Get the channel number and verify it. */
2120         id = packet_get_int();
2121         c = channel_lookup(id);
2122
2123         if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
2124                 logit("Received window adjust for "
2125                     "non-open channel %d.", id);
2126                 return;
2127         }
2128         adjust = packet_get_int();
2129         packet_check_eom();
2130         debug2("channel %d: rcvd adjust %u", id, adjust);
2131         c->remote_window += adjust;
2132 }
2133
2134 void
2135 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2136 {
2137         Channel *c = NULL;
2138         u_short host_port;
2139         char *host, *originator_string;
2140         int remote_id, sock = -1;
2141
2142         remote_id = packet_get_int();
2143         host = packet_get_string(NULL);
2144         host_port = packet_get_int();
2145
2146         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2147                 originator_string = packet_get_string(NULL);
2148         } else {
2149                 originator_string = xstrdup("unknown (remote did not supply name)");
2150         }
2151         packet_check_eom();
2152         sock = channel_connect_to(host, host_port);
2153         if (sock != -1) {
2154                 c = channel_new("connected socket",
2155                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2156                     originator_string, 1);
2157                 c->remote_id = remote_id;
2158         }
2159         xfree(originator_string);
2160         if (c == NULL) {
2161                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2162                 packet_put_int(remote_id);
2163                 packet_send();
2164         }
2165         xfree(host);
2166 }
2167
2168
2169 /* -- tcp forwarding */
2170
2171 void
2172 channel_set_af(int af)
2173 {
2174         IPv4or6 = af;
2175 }
2176
2177 static int
2178 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2179     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2180 {
2181         Channel *c;
2182         int success, sock, on = 1;
2183         struct addrinfo hints, *ai, *aitop;
2184         const char *host;
2185         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2186
2187         success = 0;
2188         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2189             listen_addr : host_to_connect;
2190
2191         if (host == NULL) {
2192                 error("No forward host name.");
2193                 return success;
2194         }
2195         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2196                 error("Forward host name too long.");
2197                 return success;
2198         }
2199
2200         /*
2201          * getaddrinfo returns a loopback address if the hostname is
2202          * set to NULL and hints.ai_flags is not AI_PASSIVE
2203          */
2204         memset(&hints, 0, sizeof(hints));
2205         hints.ai_family = IPv4or6;
2206         hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
2207         hints.ai_socktype = SOCK_STREAM;
2208         snprintf(strport, sizeof strport, "%d", listen_port);
2209         if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
2210                 packet_disconnect("getaddrinfo: fatal error");
2211
2212         for (ai = aitop; ai; ai = ai->ai_next) {
2213                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2214                         continue;
2215                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2216                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2217                         error("channel_setup_fwd_listener: getnameinfo failed");
2218                         continue;
2219                 }
2220                 /* Create a port to listen for the host. */
2221                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2222                 if (sock < 0) {
2223                         /* this is no error since kernel may not support ipv6 */
2224                         verbose("socket: %.100s", strerror(errno));
2225                         continue;
2226                 }
2227                 /*
2228                  * Set socket options.
2229                  * Allow local port reuse in TIME_WAIT.
2230                  */
2231                 if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on,
2232                     sizeof(on)) == -1)
2233                         error("setsockopt SO_REUSEADDR: %s", strerror(errno));
2234
2235                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2236
2237                 /* Bind the socket to the address. */
2238                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2239                         /* address can be in use ipv6 address is already bound */
2240                         if (!ai->ai_next)
2241                                 error("bind: %.100s", strerror(errno));
2242                         else
2243                                 verbose("bind: %.100s", strerror(errno));
2244
2245                         close(sock);
2246                         continue;
2247                 }
2248                 /* Start listening for connections on the socket. */
2249                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2250                         error("listen: %.100s", strerror(errno));
2251                         close(sock);
2252                         continue;
2253                 }
2254                 /* Allocate a channel number for the socket. */
2255                 c = channel_new("port listener", type, sock, sock, -1,
2256                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2257                     0, "port listener", 1);
2258                 strlcpy(c->path, host, sizeof(c->path));
2259                 c->host_port = port_to_connect;
2260                 c->listening_port = listen_port;
2261                 success = 1;
2262         }
2263         if (success == 0)
2264                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2265                     listen_port);
2266         freeaddrinfo(aitop);
2267         return success;
2268 }
2269
2270 int
2271 channel_cancel_rport_listener(const char *host, u_short port)
2272 {
2273         u_int i;
2274         int found = 0;
2275
2276         for(i = 0; i < channels_alloc; i++) {
2277                 Channel *c = channels[i];
2278
2279                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2280                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2281                     c->listening_port == port) {
2282                         debug2("%s: close clannel %d", __func__, i);
2283                         channel_free(c);
2284                         found = 1;
2285                 }
2286         }
2287
2288         return (found);
2289 }
2290
2291 /* protocol local port fwd, used by ssh (and sshd in v1) */
2292 int
2293 channel_setup_local_fwd_listener(u_short listen_port,
2294     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2295 {
2296         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2297             NULL, listen_port, host_to_connect, port_to_connect, gateway_ports);
2298 }
2299
2300 /* protocol v2 remote port fwd, used by sshd */
2301 int
2302 channel_setup_remote_fwd_listener(const char *listen_address,
2303     u_short listen_port, int gateway_ports)
2304 {
2305         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2306             listen_address, listen_port, NULL, 0, gateway_ports);
2307 }
2308
2309 /*
2310  * Initiate forwarding of connections to port "port" on remote host through
2311  * the secure channel to host:port from local side.
2312  */
2313
2314 void
2315 channel_request_remote_forwarding(u_short listen_port,
2316     const char *host_to_connect, u_short port_to_connect)
2317 {
2318         int type, success = 0;
2319
2320         /* Record locally that connection to this host/port is permitted. */
2321         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2322                 fatal("channel_request_remote_forwarding: too many forwards");
2323
2324         /* Send the forward request to the remote side. */
2325         if (compat20) {
2326                 const char *address_to_bind = "0.0.0.0";
2327                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2328                 packet_put_cstring("tcpip-forward");
2329                 packet_put_char(1);                     /* boolean: want reply */
2330                 packet_put_cstring(address_to_bind);
2331                 packet_put_int(listen_port);
2332                 packet_send();
2333                 packet_write_wait();
2334                 /* Assume that server accepts the request */
2335                 success = 1;
2336         } else {
2337                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2338                 packet_put_int(listen_port);
2339                 packet_put_cstring(host_to_connect);
2340                 packet_put_int(port_to_connect);
2341                 packet_send();
2342                 packet_write_wait();
2343
2344                 /* Wait for response from the remote side. */
2345                 type = packet_read();
2346                 switch (type) {
2347                 case SSH_SMSG_SUCCESS:
2348                         success = 1;
2349                         break;
2350                 case SSH_SMSG_FAILURE:
2351                         logit("Warning: Server denied remote port forwarding.");
2352                         break;
2353                 default:
2354                         /* Unknown packet */
2355                         packet_disconnect("Protocol error for port forward request:"
2356                             "received packet type %d.", type);
2357                 }
2358         }
2359         if (success) {
2360                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2361                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2362                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2363                 num_permitted_opens++;
2364         }
2365 }
2366
2367 /*
2368  * Request cancellation of remote forwarding of connection host:port from
2369  * local side.
2370  */
2371 void
2372 channel_request_rforward_cancel(u_short port)
2373 {
2374         int i;
2375         const char *address_to_bind = "0.0.0.0";
2376
2377         if (!compat20)
2378                 return;
2379
2380         for (i = 0; i < num_permitted_opens; i++) {
2381                 if (permitted_opens[i].host_to_connect != NULL &&
2382                     permitted_opens[i].listen_port == port)
2383                         break;
2384         }
2385         if (i >= num_permitted_opens) {
2386                 debug("%s: requested forward not found", __func__);
2387                 return;
2388         }
2389         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2390         packet_put_cstring("cancel-tcpip-forward");
2391         packet_put_char(0);
2392         packet_put_cstring(address_to_bind);
2393         packet_put_int(port);
2394         packet_send();
2395
2396         permitted_opens[i].listen_port = 0;
2397         permitted_opens[i].port_to_connect = 0;
2398         free(permitted_opens[i].host_to_connect);
2399         permitted_opens[i].host_to_connect = NULL;
2400 }
2401
2402 /*
2403  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2404  * listening for the port, and sends back a success reply (or disconnect
2405  * message if there was an error).  This never returns if there was an error.
2406  */
2407
2408 void
2409 channel_input_port_forward_request(int is_root, int gateway_ports)
2410 {
2411         u_short port, host_port;
2412         char *hostname;
2413
2414         /* Get arguments from the packet. */
2415         port = packet_get_int();
2416         hostname = packet_get_string(NULL);
2417         host_port = packet_get_int();
2418
2419 #ifndef HAVE_CYGWIN
2420         /*
2421          * Check that an unprivileged user is not trying to forward a
2422          * privileged port.
2423          */
2424         if (port < IPPORT_RESERVED && !is_root)
2425                 packet_disconnect(
2426                     "Requested forwarding of port %d but user is not root.",
2427                     port);
2428         if (host_port == 0)
2429                 packet_disconnect("Dynamic forwarding denied.");
2430 #endif
2431
2432         /* Initiate forwarding */
2433         channel_setup_local_fwd_listener(port, hostname, host_port, gateway_ports);
2434
2435         /* Free the argument string. */
2436         xfree(hostname);
2437 }
2438
2439 /*
2440  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2441  * usually called by the server, because the user could connect to any port
2442  * anyway, and the server has no way to know but to trust the client anyway.
2443  */
2444 void
2445 channel_permit_all_opens(void)
2446 {
2447         if (num_permitted_opens == 0)
2448                 all_opens_permitted = 1;
2449 }
2450
2451 void
2452 channel_add_permitted_opens(char *host, int port)
2453 {
2454         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2455                 fatal("channel_request_remote_forwarding: too many forwards");
2456         debug("allow port forwarding to host %s port %d", host, port);
2457
2458         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2459         permitted_opens[num_permitted_opens].port_to_connect = port;
2460         num_permitted_opens++;
2461
2462         all_opens_permitted = 0;
2463 }
2464
2465 void
2466 channel_clear_permitted_opens(void)
2467 {
2468         int i;
2469
2470         for (i = 0; i < num_permitted_opens; i++)
2471                 if (permitted_opens[i].host_to_connect != NULL)
2472                         xfree(permitted_opens[i].host_to_connect);
2473         num_permitted_opens = 0;
2474
2475 }
2476
2477
2478 /* return socket to remote host, port */
2479 static int
2480 connect_to(const char *host, u_short port)
2481 {
2482         struct addrinfo hints, *ai, *aitop;
2483         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2484         int gaierr;
2485         int sock = -1;
2486
2487         memset(&hints, 0, sizeof(hints));
2488         hints.ai_family = IPv4or6;
2489         hints.ai_socktype = SOCK_STREAM;
2490         snprintf(strport, sizeof strport, "%d", port);
2491         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2492                 error("connect_to %.100s: unknown host (%s)", host,
2493                     gai_strerror(gaierr));
2494                 return -1;
2495         }
2496         for (ai = aitop; ai; ai = ai->ai_next) {
2497                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2498                         continue;
2499                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2500                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2501                         error("connect_to: getnameinfo failed");
2502                         continue;
2503                 }
2504                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2505                 if (sock < 0) {
2506                         if (ai->ai_next == NULL)
2507                                 error("socket: %.100s", strerror(errno));
2508                         else
2509                                 verbose("socket: %.100s", strerror(errno));
2510                         continue;
2511                 }
2512                 if (set_nonblock(sock) == -1)
2513                         fatal("%s: set_nonblock(%d)", __func__, sock);
2514                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2515                     errno != EINPROGRESS) {
2516                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2517                             strerror(errno));
2518                         close(sock);
2519                         continue;       /* fail -- try next */
2520                 }
2521                 break; /* success */
2522
2523         }
2524         freeaddrinfo(aitop);
2525         if (!ai) {
2526                 error("connect_to %.100s port %d: failed.", host, port);
2527                 return -1;
2528         }
2529         /* success */
2530         set_nodelay(sock);
2531         return sock;
2532 }
2533
2534 int
2535 channel_connect_by_listen_address(u_short listen_port)
2536 {
2537         int i;
2538
2539         for (i = 0; i < num_permitted_opens; i++)
2540                 if (permitted_opens[i].host_to_connect != NULL &&
2541                     permitted_opens[i].listen_port == listen_port)
2542                         return connect_to(
2543                             permitted_opens[i].host_to_connect,
2544                             permitted_opens[i].port_to_connect);
2545         error("WARNING: Server requests forwarding for unknown listen_port %d",
2546             listen_port);
2547         return -1;
2548 }
2549
2550 /* Check if connecting to that port is permitted and connect. */
2551 int
2552 channel_connect_to(const char *host, u_short port)
2553 {
2554         int i, permit;
2555
2556         permit = all_opens_permitted;
2557         if (!permit) {
2558                 for (i = 0; i < num_permitted_opens; i++)
2559                         if (permitted_opens[i].host_to_connect != NULL &&
2560                             permitted_opens[i].port_to_connect == port &&
2561                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2562                                 permit = 1;
2563
2564         }
2565         if (!permit) {
2566                 logit("Received request to connect to host %.100s port %d, "
2567                     "but the request was denied.", host, port);
2568                 return -1;
2569         }
2570         return connect_to(host, port);
2571 }
2572
2573 void
2574 channel_send_window_changes(void)
2575 {
2576         u_int i;
2577         struct winsize ws;
2578
2579         for (i = 0; i < channels_alloc; i++) {
2580                 if (channels[i] == NULL ||
2581                     channels[i]->type != SSH_CHANNEL_OPEN)
2582                         continue;
2583                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2584                         continue;
2585                 channel_request_start(i, "window-change", 0);
2586                 packet_put_int(ws.ws_col);
2587                 packet_put_int(ws.ws_row);
2588                 packet_put_int(ws.ws_xpixel);
2589                 packet_put_int(ws.ws_ypixel);
2590                 packet_send();
2591         }
2592 }
2593
2594 /* -- X11 forwarding */
2595
2596 /*
2597  * Creates an internet domain socket for listening for X11 connections.
2598  * Returns 0 and a suitable display number for the DISPLAY variable
2599  * stored in display_numberp , or -1 if an error occurs.
2600  */
2601 int
2602 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2603     int single_connection, u_int *display_numberp)
2604 {
2605         Channel *nc = NULL;
2606         int display_number, sock;
2607         u_short port;
2608         struct addrinfo hints, *ai, *aitop;
2609         char strport[NI_MAXSERV];
2610         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2611
2612         for (display_number = x11_display_offset;
2613             display_number < MAX_DISPLAYS;
2614             display_number++) {
2615                 port = 6000 + display_number;
2616                 memset(&hints, 0, sizeof(hints));
2617                 hints.ai_family = IPv4or6;
2618                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2619                 hints.ai_socktype = SOCK_STREAM;
2620                 snprintf(strport, sizeof strport, "%d", port);
2621                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2622                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2623                         return -1;
2624                 }
2625                 for (ai = aitop; ai; ai = ai->ai_next) {
2626                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2627                                 continue;
2628                         sock = socket(ai->ai_family, ai->ai_socktype,
2629                             ai->ai_protocol);
2630                         if (sock < 0) {
2631                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2632                                         error("socket: %.100s", strerror(errno));
2633                                         freeaddrinfo(aitop);
2634                                         return -1;
2635                                 } else {
2636                                         debug("x11_create_display_inet: Socket family %d not supported",
2637                                                  ai->ai_family);
2638                                         continue;
2639                                 }
2640                         }
2641 #ifdef IPV6_V6ONLY
2642                         if (ai->ai_family == AF_INET6) {
2643                                 int on = 1;
2644                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2645                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2646                         }
2647 #endif
2648                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2649                                 debug2("bind port %d: %.100s", port, strerror(errno));
2650                                 close(sock);
2651
2652                                 if (ai->ai_next)
2653                                         continue;
2654
2655                                 for (n = 0; n < num_socks; n++) {
2656                                         close(socks[n]);
2657                                 }
2658                                 num_socks = 0;
2659                                 break;
2660                         }
2661                         socks[num_socks++] = sock;
2662 #ifndef DONT_TRY_OTHER_AF
2663                         if (num_socks == NUM_SOCKS)
2664                                 break;
2665 #else
2666                         if (x11_use_localhost) {
2667                                 if (num_socks == NUM_SOCKS)
2668                                         break;
2669                         } else {
2670                                 break;
2671                         }
2672 #endif
2673                 }
2674                 freeaddrinfo(aitop);
2675                 if (num_socks > 0)
2676                         break;
2677         }
2678         if (display_number >= MAX_DISPLAYS) {
2679                 error("Failed to allocate internet-domain X11 display socket.");
2680                 return -1;
2681         }
2682         /* Start listening for connections on the socket. */
2683         for (n = 0; n < num_socks; n++) {
2684                 sock = socks[n];
2685                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2686                         error("listen: %.100s", strerror(errno));
2687                         close(sock);
2688                         return -1;
2689                 }
2690         }
2691
2692         /* Allocate a channel for each socket. */
2693         for (n = 0; n < num_socks; n++) {
2694                 sock = socks[n];
2695                 nc = channel_new("x11 listener",
2696                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2697                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2698                     0, "X11 inet listener", 1);
2699                 nc->single_connection = single_connection;
2700         }
2701
2702         /* Return the display number for the DISPLAY environment variable. */
2703         *display_numberp = display_number;
2704         return (0);
2705 }
2706
2707 static int
2708 connect_local_xsocket(u_int dnr)
2709 {
2710         int sock;
2711         struct sockaddr_un addr;
2712
2713         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2714         if (sock < 0)
2715                 error("socket: %.100s", strerror(errno));
2716         memset(&addr, 0, sizeof(addr));
2717         addr.sun_family = AF_UNIX;
2718         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2719         if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2720                 return sock;
2721         close(sock);
2722         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2723         return -1;
2724 }
2725
2726 int
2727 x11_connect_display(void)
2728 {
2729         int display_number, sock = 0;
2730         const char *display;
2731         char buf[1024], *cp;
2732         struct addrinfo hints, *ai, *aitop;
2733         char strport[NI_MAXSERV];
2734         int gaierr;
2735
2736         /* Try to open a socket for the local X server. */
2737         display = getenv("DISPLAY");
2738         if (!display) {
2739                 error("DISPLAY not set.");
2740                 return -1;
2741         }
2742         /*
2743          * Now we decode the value of the DISPLAY variable and make a
2744          * connection to the real X server.
2745          */
2746
2747         /*
2748          * Check if it is a unix domain socket.  Unix domain displays are in
2749          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2750          */
2751         if (strncmp(display, "unix:", 5) == 0 ||
2752             display[0] == ':') {
2753                 /* Connect to the unix domain socket. */
2754                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2755                         error("Could not parse display number from DISPLAY: %.100s",
2756                             display);
2757                         return -1;
2758                 }
2759                 /* Create a socket. */
2760                 sock = connect_local_xsocket(display_number);
2761                 if (sock < 0)
2762                         return -1;
2763
2764                 /* OK, we now have a connection to the display. */
2765                 return sock;
2766         }
2767         /*
2768          * Connect to an inet socket.  The DISPLAY value is supposedly
2769          * hostname:d[.s], where hostname may also be numeric IP address.
2770          */
2771         strlcpy(buf, display, sizeof(buf));
2772         cp = strchr(buf, ':');
2773         if (!cp) {
2774                 error("Could not find ':' in DISPLAY: %.100s", display);
2775                 return -1;
2776         }
2777         *cp = 0;
2778         /* buf now contains the host name.  But first we parse the display number. */
2779         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2780                 error("Could not parse display number from DISPLAY: %.100s",
2781                     display);
2782                 return -1;
2783         }
2784
2785         /* Look up the host address */
2786         memset(&hints, 0, sizeof(hints));
2787         hints.ai_family = IPv4or6;
2788         hints.ai_socktype = SOCK_STREAM;
2789         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2790         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2791                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2792                 return -1;
2793         }
2794         for (ai = aitop; ai; ai = ai->ai_next) {
2795                 /* Create a socket. */
2796                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2797                 if (sock < 0) {
2798                         debug2("socket: %.100s", strerror(errno));
2799                         continue;
2800                 }
2801                 /* Connect it to the display. */
2802                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2803                         debug2("connect %.100s port %d: %.100s", buf,
2804                             6000 + display_number, strerror(errno));
2805                         close(sock);
2806                         continue;
2807                 }
2808                 /* Success */
2809                 break;
2810         }
2811         freeaddrinfo(aitop);
2812         if (!ai) {
2813                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2814                     strerror(errno));
2815                 return -1;
2816         }
2817         set_nodelay(sock);
2818         return sock;
2819 }
2820
2821 /*
2822  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2823  * the remote channel number.  We should do whatever we want, and respond
2824  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2825  */
2826
2827 void
2828 x11_input_open(int type, u_int32_t seq, void *ctxt)
2829 {
2830         Channel *c = NULL;
2831         int remote_id, sock = 0;
2832         char *remote_host;
2833
2834         debug("Received X11 open request.");
2835
2836         remote_id = packet_get_int();
2837
2838         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2839                 remote_host = packet_get_string(NULL);
2840         } else {
2841                 remote_host = xstrdup("unknown (remote did not supply name)");
2842         }
2843         packet_check_eom();
2844
2845         /* Obtain a connection to the real X display. */
2846         sock = x11_connect_display();
2847         if (sock != -1) {
2848                 /* Allocate a channel for this connection. */
2849                 c = channel_new("connected x11 socket",
2850                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
2851                     remote_host, 1);
2852                 c->remote_id = remote_id;
2853                 c->force_drain = 1;
2854         }
2855         xfree(remote_host);
2856         if (c == NULL) {
2857                 /* Send refusal to the remote host. */
2858                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2859                 packet_put_int(remote_id);
2860         } else {
2861                 /* Send a confirmation to the remote host. */
2862                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2863                 packet_put_int(remote_id);
2864                 packet_put_int(c->self);
2865         }
2866         packet_send();
2867 }
2868
2869 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
2870 void
2871 deny_input_open(int type, u_int32_t seq, void *ctxt)
2872 {
2873         int rchan = packet_get_int();
2874
2875         switch (type) {
2876         case SSH_SMSG_AGENT_OPEN:
2877                 error("Warning: ssh server tried agent forwarding.");
2878                 break;
2879         case SSH_SMSG_X11_OPEN:
2880                 error("Warning: ssh server tried X11 forwarding.");
2881                 break;
2882         default:
2883                 error("deny_input_open: type %d", type);
2884                 break;
2885         }
2886         error("Warning: this is probably a break in attempt by a malicious server.");
2887         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2888         packet_put_int(rchan);
2889         packet_send();
2890 }
2891
2892 /*
2893  * Requests forwarding of X11 connections, generates fake authentication
2894  * data, and enables authentication spoofing.
2895  * This should be called in the client only.
2896  */
2897 void
2898 x11_request_forwarding_with_spoofing(int client_session_id,
2899     const char *proto, const char *data)
2900 {
2901         u_int data_len = (u_int) strlen(data) / 2;
2902         u_int i, value, len;
2903         char *new_data;
2904         int screen_number;
2905         const char *cp;
2906         u_int32_t rnd = 0;
2907
2908         cp = getenv("DISPLAY");
2909         if (cp)
2910                 cp = strchr(cp, ':');
2911         if (cp)
2912                 cp = strchr(cp, '.');
2913         if (cp)
2914                 screen_number = atoi(cp + 1);
2915         else
2916                 screen_number = 0;
2917
2918         /* Save protocol name. */
2919         x11_saved_proto = xstrdup(proto);
2920
2921         /*
2922          * Extract real authentication data and generate fake data of the
2923          * same length.
2924          */
2925         x11_saved_data = xmalloc(data_len);
2926         x11_fake_data = xmalloc(data_len);
2927         for (i = 0; i < data_len; i++) {
2928                 if (sscanf(data + 2 * i, "%2x", &value) != 1)
2929                         fatal("x11_request_forwarding: bad authentication data: %.100s", data);
2930                 if (i % 4 == 0)
2931                         rnd = arc4random();
2932                 x11_saved_data[i] = value;
2933                 x11_fake_data[i] = rnd & 0xff;
2934                 rnd >>= 8;
2935         }
2936         x11_saved_data_len = data_len;
2937         x11_fake_data_len = data_len;
2938
2939         /* Convert the fake data into hex. */
2940         len = 2 * data_len + 1;
2941         new_data = xmalloc(len);
2942         for (i = 0; i < data_len; i++)
2943                 snprintf(new_data + 2 * i, len - 2 * i,
2944                     "%02x", (u_char) x11_fake_data[i]);
2945
2946         /* Send the request packet. */
2947         if (compat20) {
2948                 channel_request_start(client_session_id, "x11-req", 0);
2949                 packet_put_char(0);     /* XXX bool single connection */
2950         } else {
2951                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
2952         }
2953         packet_put_cstring(proto);
2954         packet_put_cstring(new_data);
2955         packet_put_int(screen_number);
2956         packet_send();
2957         packet_write_wait();
2958         xfree(new_data);
2959 }
2960
2961
2962 /* -- agent forwarding */
2963
2964 /* Sends a message to the server to request authentication fd forwarding. */
2965
2966 void
2967 auth_request_forwarding(void)
2968 {
2969         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
2970         packet_send();
2971         packet_write_wait();
2972 }