crypto/openssh-4/channels.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * This file contains functions for generic socket connection forwarding.
   6  * There is also code for initiating connection forwarding for X11 connections,
   7  * arbitrary tcp/ip connections, and the authentication agent connection.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * SSH2 support added by Markus Friedl.
  16  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  17  * Copyright (c) 1999 Dug Song.  All rights reserved.
  18  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  19  *
  20  * Redistribution and use in source and binary forms, with or without
  21  * modification, are permitted provided that the following conditions
  22  * are met:
  23  * 1. Redistributions of source code must retain the above copyright
  24  *    notice, this list of conditions and the following disclaimer.
  25  * 2. Redistributions in binary form must reproduce the above copyright
  26  *    notice, this list of conditions and the following disclaimer in the
  27  *    documentation and/or other materials provided with the distribution.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  30  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  31  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  32  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  33  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  34  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  38  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  39  */
  40
  41 #include "includes.h"
  42 RCSID("$OpenBSD: channels.c,v 1.214 2005/03/14 11:46:56 markus 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 #define CHAN_RBUF       16*1024
  62
  63 /*
  64  * Pointer to an array containing all allocated channels.  The array is
  65  * dynamically extended as needed.
  66  */
  67 static Channel **channels = NULL;
  68
  69 /*
  70  * Size of the channel array.  All slots of the array must always be
  71  * initialized (at least the type field); unused slots set to NULL
  72  */
  73 static u_int channels_alloc = 0;
  74
  75 /*
  76  * Maximum file descriptor value used in any of the channels.  This is
  77  * updated in channel_new.
  78  */
  79 static int channel_max_fd = 0;
  80
  81
  82 /* -- tcp forwarding */
  83
  84 /*
  85  * Data structure for storing which hosts are permitted for forward requests.
  86  * The local sides of any remote forwards are stored in this array to prevent
  87  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  88  * network (which might be behind a firewall).
  89  */
  90 typedef struct {
  91         char *host_to_connect;          /* Connect to 'host'. */
  92         u_short port_to_connect;        /* Connect to 'port'. */
  93         u_short listen_port;            /* Remote side should listen port number. */
  94 } ForwardPermission;
  95
  96 /* List of all permitted host/port pairs to connect. */
  97 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
  98
  99 /* Number of permitted host/port pairs in the array. */
 100 static int num_permitted_opens = 0;
 101 /*
 102  * If this is true, all opens are permitted.  This is the case on the server
 103  * on which we have to trust the client anyway, and the user could do
 104  * anything after logging in anyway.
 105  */
 106 static int all_opens_permitted = 0;
 107
 108
 109 /* -- X11 forwarding */
 110
 111 /* Maximum number of fake X11 displays to try. */
 112 #define MAX_DISPLAYS  1000
 113
 114 /* Saved X11 authentication protocol name. */
 115 static char *x11_saved_proto = NULL;
 116
 117 /* Saved X11 authentication data.  This is the real data. */
 118 static char *x11_saved_data = NULL;
 119 static u_int x11_saved_data_len = 0;
 120
 121 /*
 122  * Fake X11 authentication data.  This is what the server will be sending us;
 123  * we should replace any occurrences of this by the real data.
 124  */
 125 static char *x11_fake_data = NULL;
 126 static u_int x11_fake_data_len;
 127
 128
 129 /* -- agent forwarding */
 130
 131 #define NUM_SOCKS       10
 132
 133 /* AF_UNSPEC or AF_INET or AF_INET6 */
 134 static int IPv4or6 = AF_UNSPEC;
 135
 136 /* helper */
 137 static void port_open_helper(Channel *c, char *rtype);
 138
 139 /* -- channel core */
 140
 141 Channel *
 142 channel_lookup(int id)
 143 {
 144         Channel *c;
 145
 146         if (id < 0 || (u_int)id >= channels_alloc) {
 147                 logit("channel_lookup: %d: bad id", id);
 148                 return NULL;
 149         }
 150         c = channels[id];
 151         if (c == NULL) {
 152                 logit("channel_lookup: %d: bad id: channel free", id);
 153                 return NULL;
 154         }
 155         return c;
 156 }
 157
 158 /*
 159  * Register filedescriptors for a channel, used when allocating a channel or
 160  * when the channel consumer/producer is ready, e.g. shell exec'd
 161  */
 162
 163 static void
 164 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 165     int extusage, int nonblock)
 166 {
 167         /* Update the maximum file descriptor value. */
 168         channel_max_fd = MAX(channel_max_fd, rfd);
 169         channel_max_fd = MAX(channel_max_fd, wfd);
 170         channel_max_fd = MAX(channel_max_fd, efd);
 171
 172         /* XXX set close-on-exec -markus */
 173
 174         c->rfd = rfd;
 175         c->wfd = wfd;
 176         c->sock = (rfd == wfd) ? rfd : -1;
 177         c->ctl_fd = -1; /* XXX: set elsewhere */
 178         c->efd = efd;
 179         c->extended_usage = extusage;
 180
 181         /* XXX ugly hack: nonblock is only set by the server */
 182         if (nonblock && isatty(c->rfd)) {
 183                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 184                 c->isatty = 1;
 185                 if (!isatty(c->wfd)) {
 186                         error("channel %d: wfd %d is not a tty?",
 187                             c->self, c->wfd);
 188                 }
 189         } else {
 190                 c->isatty = 0;
 191         }
 192         c->wfd_isatty = isatty(c->wfd);
 193
 194         /* enable nonblocking mode */
 195         if (nonblock) {
 196                 if (rfd != -1)
 197                         set_nonblock(rfd);
 198                 if (wfd != -1)
 199                         set_nonblock(wfd);
 200                 if (efd != -1)
 201                         set_nonblock(efd);
 202         }
 203 }
 204
 205 /*
 206  * Allocate a new channel object and set its type and socket. This will cause
 207  * remote_name to be freed.
 208  */
 209
 210 Channel *
 211 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 212     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 213 {
 214         int found;
 215         u_int i;
 216         Channel *c;
 217
 218         /* Do initial allocation if this is the first call. */
 219         if (channels_alloc == 0) {
 220                 channels_alloc = 10;
 221                 channels = xmalloc(channels_alloc * sizeof(Channel *));
 222                 for (i = 0; i < channels_alloc; i++)
 223                         channels[i] = NULL;
 224         }
 225         /* Try to find a free slot where to put the new channel. */
 226         for (found = -1, i = 0; i < channels_alloc; i++)
 227                 if (channels[i] == NULL) {
 228                         /* Found a free slot. */
 229                         found = (int)i;
 230                         break;
 231                 }
 232         if (found < 0) {
 233                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 234                 found = channels_alloc;
 235                 if (channels_alloc > 10000)
 236                         fatal("channel_new: internal error: channels_alloc %d "
 237                             "too big.", channels_alloc);
 238                 channels = xrealloc(channels,
 239                     (channels_alloc + 10) * sizeof(Channel *));
 240                 channels_alloc += 10;
 241                 debug2("channel: expanding %d", channels_alloc);
 242                 for (i = found; i < channels_alloc; i++)
 243                         channels[i] = NULL;
 244         }
 245         /* Initialize and return new channel. */
 246         c = channels[found] = xmalloc(sizeof(Channel));
 247         memset(c, 0, sizeof(Channel));
 248         buffer_init(&c->input);
 249         buffer_init(&c->output);
 250         buffer_init(&c->extended);
 251         c->ostate = CHAN_OUTPUT_OPEN;
 252         c->istate = CHAN_INPUT_OPEN;
 253         c->flags = 0;
 254         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 255         c->self = found;
 256         c->type = type;
 257         c->ctype = ctype;
 258         c->local_window = window;
 259         c->local_window_max = window;
 260         c->local_consumed = 0;
 261         c->local_maxpacket = maxpack;
 262         c->remote_id = -1;
 263         c->remote_name = xstrdup(remote_name);
 264         c->remote_window = 0;
 265         c->remote_maxpacket = 0;
 266         c->force_drain = 0;
 267         c->single_connection = 0;
 268         c->detach_user = NULL;
 269         c->confirm = NULL;
 270         c->confirm_ctx = NULL;
 271         c->input_filter = NULL;
 272         debug("channel %d: new [%s]", found, remote_name);
 273         return c;
 274 }
 275
 276 static int
 277 channel_find_maxfd(void)
 278 {
 279         u_int i;
 280         int max = 0;
 281         Channel *c;
 282
 283         for (i = 0; i < channels_alloc; i++) {
 284                 c = channels[i];
 285                 if (c != NULL) {
 286                         max = MAX(max, c->rfd);
 287                         max = MAX(max, c->wfd);
 288                         max = MAX(max, c->efd);
 289                 }
 290         }
 291         return max;
 292 }
 293
 294 int
 295 channel_close_fd(int *fdp)
 296 {
 297         int ret = 0, fd = *fdp;
 298
 299         if (fd != -1) {
 300                 ret = close(fd);
 301                 *fdp = -1;
 302                 if (fd == channel_max_fd)
 303                         channel_max_fd = channel_find_maxfd();
 304         }
 305         return ret;
 306 }
 307
 308 /* Close all channel fd/socket. */
 309
 310 static void
 311 channel_close_fds(Channel *c)
 312 {
 313         debug3("channel %d: close_fds r %d w %d e %d c %d",
 314             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 315
 316         channel_close_fd(&c->sock);
 317         channel_close_fd(&c->ctl_fd);
 318         channel_close_fd(&c->rfd);
 319         channel_close_fd(&c->wfd);
 320         channel_close_fd(&c->efd);
 321 }
 322
 323 /* Free the channel and close its fd/socket. */
 324
 325 void
 326 channel_free(Channel *c)
 327 {
 328         char *s;
 329         u_int i, n;
 330
 331         for (n = 0, i = 0; i < channels_alloc; i++)
 332                 if (channels[i])
 333                         n++;
 334         debug("channel %d: free: %s, nchannels %u", c->self,
 335             c->remote_name ? c->remote_name : "???", n);
 336
 337         s = channel_open_message();
 338         debug3("channel %d: status: %s", c->self, s);
 339         xfree(s);
 340
 341         if (c->sock != -1)
 342                 shutdown(c->sock, SHUT_RDWR);
 343         if (c->ctl_fd != -1)
 344                 shutdown(c->ctl_fd, SHUT_RDWR);
 345         channel_close_fds(c);
 346         buffer_free(&c->input);
 347         buffer_free(&c->output);
 348         buffer_free(&c->extended);
 349         if (c->remote_name) {
 350                 xfree(c->remote_name);
 351                 c->remote_name = NULL;
 352         }
 353         channels[c->self] = NULL;
 354         xfree(c);
 355 }
 356
 357 void
 358 channel_free_all(void)
 359 {
 360         u_int i;
 361
 362         for (i = 0; i < channels_alloc; i++)
 363                 if (channels[i] != NULL)
 364                         channel_free(channels[i]);
 365 }
 366
 367 /*
 368  * Closes the sockets/fds of all channels.  This is used to close extra file
 369  * descriptors after a fork.
 370  */
 371
 372 void
 373 channel_close_all(void)
 374 {
 375         u_int i;
 376
 377         for (i = 0; i < channels_alloc; i++)
 378                 if (channels[i] != NULL)
 379                         channel_close_fds(channels[i]);
 380 }
 381
 382 /*
 383  * Stop listening to channels.
 384  */
 385
 386 void
 387 channel_stop_listening(void)
 388 {
 389         u_int i;
 390         Channel *c;
 391
 392         for (i = 0; i < channels_alloc; i++) {
 393                 c = channels[i];
 394                 if (c != NULL) {
 395                         switch (c->type) {
 396                         case SSH_CHANNEL_AUTH_SOCKET:
 397                         case SSH_CHANNEL_PORT_LISTENER:
 398                         case SSH_CHANNEL_RPORT_LISTENER:
 399                         case SSH_CHANNEL_X11_LISTENER:
 400                                 channel_close_fd(&c->sock);
 401                                 channel_free(c);
 402                                 break;
 403                         }
 404                 }
 405         }
 406 }
 407
 408 /*
 409  * Returns true if no channel has too much buffered data, and false if one or
 410  * more channel is overfull.
 411  */
 412
 413 int
 414 channel_not_very_much_buffered_data(void)
 415 {
 416         u_int i;
 417         Channel *c;
 418
 419         for (i = 0; i < channels_alloc; i++) {
 420                 c = channels[i];
 421                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 422 #if 0
 423                         if (!compat20 &&
 424                             buffer_len(&c->input) > packet_get_maxsize()) {
 425                                 debug2("channel %d: big input buffer %d",
 426                                     c->self, buffer_len(&c->input));
 427                                 return 0;
 428                         }
 429 #endif
 430                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 431                                 debug2("channel %d: big output buffer %u > %u",
 432                                     c->self, buffer_len(&c->output),
 433                                     packet_get_maxsize());
 434                                 return 0;
 435                         }
 436                 }
 437         }
 438         return 1;
 439 }
 440
 441 /* Returns true if any channel is still open. */
 442
 443 int
 444 channel_still_open(void)
 445 {
 446         u_int i;
 447         Channel *c;
 448
 449         for (i = 0; i < channels_alloc; i++) {
 450                 c = channels[i];
 451                 if (c == NULL)
 452                         continue;
 453                 switch (c->type) {
 454                 case SSH_CHANNEL_X11_LISTENER:
 455                 case SSH_CHANNEL_PORT_LISTENER:
 456                 case SSH_CHANNEL_RPORT_LISTENER:
 457                 case SSH_CHANNEL_CLOSED:
 458                 case SSH_CHANNEL_AUTH_SOCKET:
 459                 case SSH_CHANNEL_DYNAMIC:
 460                 case SSH_CHANNEL_CONNECTING:
 461                 case SSH_CHANNEL_ZOMBIE:
 462                         continue;
 463                 case SSH_CHANNEL_LARVAL:
 464                         if (!compat20)
 465                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 466                         continue;
 467                 case SSH_CHANNEL_OPENING:
 468                 case SSH_CHANNEL_OPEN:
 469                 case SSH_CHANNEL_X11_OPEN:
 470                         return 1;
 471                 case SSH_CHANNEL_INPUT_DRAINING:
 472                 case SSH_CHANNEL_OUTPUT_DRAINING:
 473                         if (!compat13)
 474                                 fatal("cannot happen: OUT_DRAIN");
 475                         return 1;
 476                 default:
 477                         fatal("channel_still_open: bad channel type %d", c->type);
 478                         /* NOTREACHED */
 479                 }
 480         }
 481         return 0;
 482 }
 483
 484 /* Returns the id of an open channel suitable for keepaliving */
 485
 486 int
 487 channel_find_open(void)
 488 {
 489         u_int i;
 490         Channel *c;
 491
 492         for (i = 0; i < channels_alloc; i++) {
 493                 c = channels[i];
 494                 if (c == NULL || c->remote_id < 0)
 495                         continue;
 496                 switch (c->type) {
 497                 case SSH_CHANNEL_CLOSED:
 498                 case SSH_CHANNEL_DYNAMIC:
 499                 case SSH_CHANNEL_X11_LISTENER:
 500                 case SSH_CHANNEL_PORT_LISTENER:
 501                 case SSH_CHANNEL_RPORT_LISTENER:
 502                 case SSH_CHANNEL_OPENING:
 503                 case SSH_CHANNEL_CONNECTING:
 504                 case SSH_CHANNEL_ZOMBIE:
 505                         continue;
 506                 case SSH_CHANNEL_LARVAL:
 507                 case SSH_CHANNEL_AUTH_SOCKET:
 508                 case SSH_CHANNEL_OPEN:
 509                 case SSH_CHANNEL_X11_OPEN:
 510                         return i;
 511                 case SSH_CHANNEL_INPUT_DRAINING:
 512                 case SSH_CHANNEL_OUTPUT_DRAINING:
 513                         if (!compat13)
 514                                 fatal("cannot happen: OUT_DRAIN");
 515                         return i;
 516                 default:
 517                         fatal("channel_find_open: bad channel type %d", c->type);
 518                         /* NOTREACHED */
 519                 }
 520         }
 521         return -1;
 522 }
 523
 524
 525 /*
 526  * Returns a message describing the currently open forwarded connections,
 527  * suitable for sending to the client.  The message contains crlf pairs for
 528  * newlines.
 529  */
 530
 531 char *
 532 channel_open_message(void)
 533 {
 534         Buffer buffer;
 535         Channel *c;
 536         char buf[1024], *cp;
 537         u_int i;
 538
 539         buffer_init(&buffer);
 540         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 541         buffer_append(&buffer, buf, strlen(buf));
 542         for (i = 0; i < channels_alloc; i++) {
 543                 c = channels[i];
 544                 if (c == NULL)
 545                         continue;
 546                 switch (c->type) {
 547                 case SSH_CHANNEL_X11_LISTENER:
 548                 case SSH_CHANNEL_PORT_LISTENER:
 549                 case SSH_CHANNEL_RPORT_LISTENER:
 550                 case SSH_CHANNEL_CLOSED:
 551                 case SSH_CHANNEL_AUTH_SOCKET:
 552                 case SSH_CHANNEL_ZOMBIE:
 553                         continue;
 554                 case SSH_CHANNEL_LARVAL:
 555                 case SSH_CHANNEL_OPENING:
 556                 case SSH_CHANNEL_CONNECTING:
 557                 case SSH_CHANNEL_DYNAMIC:
 558                 case SSH_CHANNEL_OPEN:
 559                 case SSH_CHANNEL_X11_OPEN:
 560                 case SSH_CHANNEL_INPUT_DRAINING:
 561                 case SSH_CHANNEL_OUTPUT_DRAINING:
 562                         snprintf(buf, sizeof buf,
 563                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 564                             c->self, c->remote_name,
 565                             c->type, c->remote_id,
 566                             c->istate, buffer_len(&c->input),
 567                             c->ostate, buffer_len(&c->output),
 568                             c->rfd, c->wfd, c->ctl_fd);
 569                         buffer_append(&buffer, buf, strlen(buf));
 570                         continue;
 571                 default:
 572                         fatal("channel_open_message: bad channel type %d", c->type);
 573                         /* NOTREACHED */
 574                 }
 575         }
 576         buffer_append(&buffer, "\0", 1);
 577         cp = xstrdup(buffer_ptr(&buffer));
 578         buffer_free(&buffer);
 579         return cp;
 580 }
 581
 582 void
 583 channel_send_open(int id)
 584 {
 585         Channel *c = channel_lookup(id);
 586
 587         if (c == NULL) {
 588                 logit("channel_send_open: %d: bad id", id);
 589                 return;
 590         }
 591         debug2("channel %d: send open", id);
 592         packet_start(SSH2_MSG_CHANNEL_OPEN);
 593         packet_put_cstring(c->ctype);
 594         packet_put_int(c->self);
 595         packet_put_int(c->local_window);
 596         packet_put_int(c->local_maxpacket);
 597         packet_send();
 598 }
 599
 600 void
 601 channel_request_start(int id, char *service, int wantconfirm)
 602 {
 603         Channel *c = channel_lookup(id);
 604
 605         if (c == NULL) {
 606                 logit("channel_request_start: %d: unknown channel id", id);
 607                 return;
 608         }
 609         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 610         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 611         packet_put_int(c->remote_id);
 612         packet_put_cstring(service);
 613         packet_put_char(wantconfirm);
 614 }
 615 void
 616 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 617 {
 618         Channel *c = channel_lookup(id);
 619
 620         if (c == NULL) {
 621                 logit("channel_register_comfirm: %d: bad id", id);
 622                 return;
 623         }
 624         c->confirm = fn;
 625         c->confirm_ctx = ctx;
 626 }
 627 void
 628 channel_register_cleanup(int id, channel_callback_fn *fn)
 629 {
 630         Channel *c = channel_lookup(id);
 631
 632         if (c == NULL) {
 633                 logit("channel_register_cleanup: %d: bad id", id);
 634                 return;
 635         }
 636         c->detach_user = fn;
 637 }
 638 void
 639 channel_cancel_cleanup(int id)
 640 {
 641         Channel *c = channel_lookup(id);
 642
 643         if (c == NULL) {
 644                 logit("channel_cancel_cleanup: %d: bad id", id);
 645                 return;
 646         }
 647         c->detach_user = NULL;
 648 }
 649 void
 650 channel_register_filter(int id, channel_filter_fn *fn)
 651 {
 652         Channel *c = channel_lookup(id);
 653
 654         if (c == NULL) {
 655                 logit("channel_register_filter: %d: bad id", id);
 656                 return;
 657         }
 658         c->input_filter = fn;
 659 }
 660
 661 void
 662 channel_set_fds(int id, int rfd, int wfd, int efd,
 663     int extusage, int nonblock, u_int window_max)
 664 {
 665         Channel *c = channel_lookup(id);
 666
 667         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 668                 fatal("channel_activate for non-larval channel %d.", id);
 669         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 670         c->type = SSH_CHANNEL_OPEN;
 671         c->local_window = c->local_window_max = window_max;
 672         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 673         packet_put_int(c->remote_id);
 674         packet_put_int(c->local_window);
 675         packet_send();
 676 }
 677
 678 /*
 679  * 'channel_pre*' are called just before select() to add any bits relevant to
 680  * channels in the select bitmasks.
 681  */
 682 /*
 683  * 'channel_post*': perform any appropriate operations for channels which
 684  * have events pending.
 685  */
 686 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 687 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 688 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 689
 690 static void
 691 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 692 {
 693         FD_SET(c->sock, readset);
 694 }
 695
 696 static void
 697 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 698 {
 699         debug3("channel %d: waiting for connection", c->self);
 700         FD_SET(c->sock, writeset);
 701 }
 702
 703 static void
 704 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 705 {
 706         if (buffer_len(&c->input) < packet_get_maxsize())
 707                 FD_SET(c->sock, readset);
 708         if (buffer_len(&c->output) > 0)
 709                 FD_SET(c->sock, writeset);
 710 }
 711
 712 static void
 713 channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
 714 {
 715         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 716
 717         /* check buffer limits */
 718         limit = MIN(limit, (BUFFER_MAX_LEN - BUFFER_MAX_CHUNK - CHAN_RBUF));
 719
 720         if (c->istate == CHAN_INPUT_OPEN &&
 721             limit > 0 &&
 722             buffer_len(&c->input) < limit)
 723                 FD_SET(c->rfd, readset);
 724         if (c->ostate == CHAN_OUTPUT_OPEN ||
 725             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 726                 if (buffer_len(&c->output) > 0) {
 727                         FD_SET(c->wfd, writeset);
 728                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 729                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 730                                debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 731                                    c->self, c->efd, buffer_len(&c->extended));
 732                         else
 733                                 chan_obuf_empty(c);
 734                 }
 735         }
 736         /** XXX check close conditions, too */
 737         if (compat20 && c->efd != -1) {
 738                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 739                     buffer_len(&c->extended) > 0)
 740                         FD_SET(c->efd, writeset);
 741                 else if (!(c->flags & CHAN_EOF_SENT) &&
 742                     c->extended_usage == CHAN_EXTENDED_READ &&
 743                     buffer_len(&c->extended) < c->remote_window)
 744                         FD_SET(c->efd, readset);
 745         }
 746         /* XXX: What about efd? races? */
 747         if (compat20 && c->ctl_fd != -1 &&
 748             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 749                 FD_SET(c->ctl_fd, readset);
 750 }
 751
 752 static void
 753 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 754 {
 755         if (buffer_len(&c->input) == 0) {
 756                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 757                 packet_put_int(c->remote_id);
 758                 packet_send();
 759                 c->type = SSH_CHANNEL_CLOSED;
 760                 debug2("channel %d: closing after input drain.", c->self);
 761         }
 762 }
 763
 764 static void
 765 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 766 {
 767         if (buffer_len(&c->output) == 0)
 768                 chan_mark_dead(c);
 769         else
 770                 FD_SET(c->sock, writeset);
 771 }
 772
 773 /*
 774  * This is a special state for X11 authentication spoofing.  An opened X11
 775  * connection (when authentication spoofing is being done) remains in this
 776  * state until the first packet has been completely read.  The authentication
 777  * data in that packet is then substituted by the real data if it matches the
 778  * fake data, and the channel is put into normal mode.
 779  * XXX All this happens at the client side.
 780  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 781  */
 782 static int
 783 x11_open_helper(Buffer *b)
 784 {
 785         u_char *ucp;
 786         u_int proto_len, data_len;
 787
 788         /* Check if the fixed size part of the packet is in buffer. */
 789         if (buffer_len(b) < 12)
 790                 return 0;
 791
 792         /* Parse the lengths of variable-length fields. */
 793         ucp = buffer_ptr(b);
 794         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 795                 proto_len = 256 * ucp[6] + ucp[7];
 796                 data_len = 256 * ucp[8] + ucp[9];
 797         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 798                 proto_len = ucp[6] + 256 * ucp[7];
 799                 data_len = ucp[8] + 256 * ucp[9];
 800         } else {
 801                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 802                     ucp[0]);
 803                 return -1;
 804         }
 805
 806         /* Check if the whole packet is in buffer. */
 807         if (buffer_len(b) <
 808             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 809                 return 0;
 810
 811         /* Check if authentication protocol matches. */
 812         if (proto_len != strlen(x11_saved_proto) ||
 813             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 814                 debug2("X11 connection uses different authentication protocol.");
 815                 return -1;
 816         }
 817         /* Check if authentication data matches our fake data. */
 818         if (data_len != x11_fake_data_len ||
 819             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 820                 x11_fake_data, x11_fake_data_len) != 0) {
 821                 debug2("X11 auth data does not match fake data.");
 822                 return -1;
 823         }
 824         /* Check fake data length */
 825         if (x11_fake_data_len != x11_saved_data_len) {
 826                 error("X11 fake_data_len %d != saved_data_len %d",
 827                     x11_fake_data_len, x11_saved_data_len);
 828                 return -1;
 829         }
 830         /*
 831          * Received authentication protocol and data match
 832          * our fake data. Substitute the fake data with real
 833          * data.
 834          */
 835         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 836             x11_saved_data, x11_saved_data_len);
 837         return 1;
 838 }
 839
 840 static void
 841 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 842 {
 843         int ret = x11_open_helper(&c->output);
 844
 845         if (ret == 1) {
 846                 /* Start normal processing for the channel. */
 847                 c->type = SSH_CHANNEL_OPEN;
 848                 channel_pre_open_13(c, readset, writeset);
 849         } else if (ret == -1) {
 850                 /*
 851                  * We have received an X11 connection that has bad
 852                  * authentication information.
 853                  */
 854                 logit("X11 connection rejected because of wrong authentication.");
 855                 buffer_clear(&c->input);
 856                 buffer_clear(&c->output);
 857                 channel_close_fd(&c->sock);
 858                 c->sock = -1;
 859                 c->type = SSH_CHANNEL_CLOSED;
 860                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 861                 packet_put_int(c->remote_id);
 862                 packet_send();
 863         }
 864 }
 865
 866 static void
 867 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
 868 {
 869         int ret = x11_open_helper(&c->output);
 870
 871         /* c->force_drain = 1; */
 872
 873         if (ret == 1) {
 874                 c->type = SSH_CHANNEL_OPEN;
 875                 channel_pre_open(c, readset, writeset);
 876         } else if (ret == -1) {
 877                 logit("X11 connection rejected because of wrong authentication.");
 878                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 879                 chan_read_failed(c);
 880                 buffer_clear(&c->input);
 881                 chan_ibuf_empty(c);
 882                 buffer_clear(&c->output);
 883                 /* for proto v1, the peer will send an IEOF */
 884                 if (compat20)
 885                         chan_write_failed(c);
 886                 else
 887                         c->type = SSH_CHANNEL_OPEN;
 888                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 889         }
 890 }
 891
 892 /* try to decode a socks4 header */
 893 static int
 894 channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
 895 {
 896         char *p, *host;
 897         int len, have, i, found;
 898         char username[256];
 899         struct {
 900                 u_int8_t version;
 901                 u_int8_t command;
 902                 u_int16_t dest_port;
 903                 struct in_addr dest_addr;
 904         } s4_req, s4_rsp;
 905
 906         debug2("channel %d: decode socks4", c->self);
 907
 908         have = buffer_len(&c->input);
 909         len = sizeof(s4_req);
 910         if (have < len)
 911                 return 0;
 912         p = buffer_ptr(&c->input);
 913         for (found = 0, i = len; i < have; i++) {
 914                 if (p[i] == '\0') {
 915                         found = 1;
 916                         break;
 917                 }
 918                 if (i > 1024) {
 919                         /* the peer is probably sending garbage */
 920                         debug("channel %d: decode socks4: too long",
 921                             c->self);
 922                         return -1;
 923                 }
 924         }
 925         if (!found)
 926                 return 0;
 927         buffer_get(&c->input, (char *)&s4_req.version, 1);
 928         buffer_get(&c->input, (char *)&s4_req.command, 1);
 929         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 930         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 931         have = buffer_len(&c->input);
 932         p = buffer_ptr(&c->input);
 933         len = strlen(p);
 934         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 935         if (len > have)
 936                 fatal("channel %d: decode socks4: len %d > have %d",
 937                     c->self, len, have);
 938         strlcpy(username, p, sizeof(username));
 939         buffer_consume(&c->input, len);
 940         buffer_consume(&c->input, 1);           /* trailing '\0' */
 941
 942         host = inet_ntoa(s4_req.dest_addr);
 943         strlcpy(c->path, host, sizeof(c->path));
 944         c->host_port = ntohs(s4_req.dest_port);
 945
 946         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 947             c->self, host, c->host_port, s4_req.command);
 948
 949         if (s4_req.command != 1) {
 950                 debug("channel %d: cannot handle: socks4 cn %d",
 951                     c->self, s4_req.command);
 952                 return -1;
 953         }
 954         s4_rsp.version = 0;                     /* vn: 0 for reply */
 955         s4_rsp.command = 90;                    /* cd: req granted */
 956         s4_rsp.dest_port = 0;                   /* ignored */
 957         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 958         buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
 959         return 1;
 960 }
 961
 962 /* try to decode a socks5 header */
 963 #define SSH_SOCKS5_AUTHDONE     0x1000
 964 #define SSH_SOCKS5_NOAUTH       0x00
 965 #define SSH_SOCKS5_IPV4         0x01
 966 #define SSH_SOCKS5_DOMAIN       0x03
 967 #define SSH_SOCKS5_IPV6         0x04
 968 #define SSH_SOCKS5_CONNECT      0x01
 969 #define SSH_SOCKS5_SUCCESS      0x00
 970
 971 static int
 972 channel_decode_socks5(Channel *c, fd_set * readset, fd_set * writeset)
 973 {
 974         struct {
 975                 u_int8_t version;
 976                 u_int8_t command;
 977                 u_int8_t reserved;
 978                 u_int8_t atyp;
 979         } s5_req, s5_rsp;
 980         u_int16_t dest_port;
 981         u_char *p, dest_addr[255+1];
 982         int i, have, found, nmethods, addrlen, af;
 983
 984         debug2("channel %d: decode socks5", c->self);
 985         p = buffer_ptr(&c->input);
 986         if (p[0] != 0x05)
 987                 return -1;
 988         have = buffer_len(&c->input);
 989         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
 990                 /* format: ver | nmethods | methods */
 991                 if (have < 2)
 992                         return 0;
 993                 nmethods = p[1];
 994                 if (have < nmethods + 2)
 995                         return 0;
 996                 /* look for method: "NO AUTHENTICATION REQUIRED" */
 997                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
 998                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
 999                                 found = 1;
1000                                 break;
1001                         }
1002                 }
1003                 if (!found) {
1004                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1005                             c->self);
1006                         return -1;
1007                 }
1008                 buffer_consume(&c->input, nmethods + 2);
1009                 buffer_put_char(&c->output, 0x05);              /* version */
1010                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1011                 FD_SET(c->sock, writeset);
1012                 c->flags |= SSH_SOCKS5_AUTHDONE;
1013                 debug2("channel %d: socks5 auth done", c->self);
1014                 return 0;                               /* need more */
1015         }
1016         debug2("channel %d: socks5 post auth", c->self);
1017         if (have < sizeof(s5_req)+1)
1018                 return 0;                       /* need more */
1019         memcpy((char *)&s5_req, p, sizeof(s5_req));
1020         if (s5_req.version != 0x05 ||
1021             s5_req.command != SSH_SOCKS5_CONNECT ||
1022             s5_req.reserved != 0x00) {
1023                 debug2("channel %d: only socks5 connect supported", c->self);
1024                 return -1;
1025         }
1026         switch (s5_req.atyp){
1027         case SSH_SOCKS5_IPV4:
1028                 addrlen = 4;
1029                 af = AF_INET;
1030                 break;
1031         case SSH_SOCKS5_DOMAIN:
1032                 addrlen = p[sizeof(s5_req)];
1033                 af = -1;
1034                 break;
1035         case SSH_SOCKS5_IPV6:
1036                 addrlen = 16;
1037                 af = AF_INET6;
1038                 break;
1039         default:
1040                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1041                 return -1;
1042         }
1043         if (have < 4 + addrlen + 2)
1044                 return 0;
1045         buffer_consume(&c->input, sizeof(s5_req));
1046         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1047                 buffer_consume(&c->input, 1);    /* host string length */
1048         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1049         buffer_get(&c->input, (char *)&dest_port, 2);
1050         dest_addr[addrlen] = '\0';
1051         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1052                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1053         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1054                 return -1;
1055         c->host_port = ntohs(dest_port);
1056
1057         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1058             c->self, c->path, c->host_port, s5_req.command);
1059
1060         s5_rsp.version = 0x05;
1061         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1062         s5_rsp.reserved = 0;                    /* ignored */
1063         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1064         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1065         dest_port = 0;                          /* ignored */
1066
1067         buffer_append(&c->output, (char *)&s5_rsp, sizeof(s5_rsp));
1068         buffer_append(&c->output, (char *)&dest_addr, sizeof(struct in_addr));
1069         buffer_append(&c->output, (char *)&dest_port, sizeof(dest_port));
1070         return 1;
1071 }
1072
1073 /* dynamic port forwarding */
1074 static void
1075 channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
1076 {
1077         u_char *p;
1078         int have, ret;
1079
1080         have = buffer_len(&c->input);
1081         c->delayed = 0;
1082         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1083         /* buffer_dump(&c->input); */
1084         /* check if the fixed size part of the packet is in buffer. */
1085         if (have < 3) {
1086                 /* need more */
1087                 FD_SET(c->sock, readset);
1088                 return;
1089         }
1090         /* try to guess the protocol */
1091         p = buffer_ptr(&c->input);
1092         switch (p[0]) {
1093         case 0x04:
1094                 ret = channel_decode_socks4(c, readset, writeset);
1095                 break;
1096         case 0x05:
1097                 ret = channel_decode_socks5(c, readset, writeset);
1098                 break;
1099         default:
1100                 ret = -1;
1101                 break;
1102         }
1103         if (ret < 0) {
1104                 chan_mark_dead(c);
1105         } else if (ret == 0) {
1106                 debug2("channel %d: pre_dynamic: need more", c->self);
1107                 /* need more */
1108                 FD_SET(c->sock, readset);
1109         } else {
1110                 /* switch to the next state */
1111                 c->type = SSH_CHANNEL_OPENING;
1112                 port_open_helper(c, "direct-tcpip");
1113         }
1114 }
1115
1116 /* This is our fake X11 server socket. */
1117 static void
1118 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
1119 {
1120         Channel *nc;
1121         struct sockaddr addr;
1122         int newsock;
1123         socklen_t addrlen;
1124         char buf[16384], *remote_ipaddr;
1125         int remote_port;
1126
1127         if (FD_ISSET(c->sock, readset)) {
1128                 debug("X11 connection requested.");
1129                 addrlen = sizeof(addr);
1130                 newsock = accept(c->sock, &addr, &addrlen);
1131                 if (c->single_connection) {
1132                         debug2("single_connection: closing X11 listener.");
1133                         channel_close_fd(&c->sock);
1134                         chan_mark_dead(c);
1135                 }
1136                 if (newsock < 0) {
1137                         error("accept: %.100s", strerror(errno));
1138                         return;
1139                 }
1140                 set_nodelay(newsock);
1141                 remote_ipaddr = get_peer_ipaddr(newsock);
1142                 remote_port = get_peer_port(newsock);
1143                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1144                     remote_ipaddr, remote_port);
1145
1146                 nc = channel_new("accepted x11 socket",
1147                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1148                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1149                 if (compat20) {
1150                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1151                         packet_put_cstring("x11");
1152                         packet_put_int(nc->self);
1153                         packet_put_int(nc->local_window_max);
1154                         packet_put_int(nc->local_maxpacket);
1155                         /* originator ipaddr and port */
1156                         packet_put_cstring(remote_ipaddr);
1157                         if (datafellows & SSH_BUG_X11FWD) {
1158                                 debug2("ssh2 x11 bug compat mode");
1159                         } else {
1160                                 packet_put_int(remote_port);
1161                         }
1162                         packet_send();
1163                 } else {
1164                         packet_start(SSH_SMSG_X11_OPEN);
1165                         packet_put_int(nc->self);
1166                         if (packet_get_protocol_flags() &
1167                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1168                                 packet_put_cstring(buf);
1169                         packet_send();
1170                 }
1171                 xfree(remote_ipaddr);
1172         }
1173 }
1174
1175 static void
1176 port_open_helper(Channel *c, char *rtype)
1177 {
1178         int direct;
1179         char buf[1024];
1180         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1181         u_short remote_port = get_peer_port(c->sock);
1182
1183         direct = (strcmp(rtype, "direct-tcpip") == 0);
1184
1185         snprintf(buf, sizeof buf,
1186             "%s: listening port %d for %.100s port %d, "
1187             "connect from %.200s port %d",
1188             rtype, c->listening_port, c->path, c->host_port,
1189             remote_ipaddr, remote_port);
1190
1191         xfree(c->remote_name);
1192         c->remote_name = xstrdup(buf);
1193
1194         if (compat20) {
1195                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1196                 packet_put_cstring(rtype);
1197                 packet_put_int(c->self);
1198                 packet_put_int(c->local_window_max);
1199                 packet_put_int(c->local_maxpacket);
1200                 if (direct) {
1201                         /* target host, port */
1202                         packet_put_cstring(c->path);
1203                         packet_put_int(c->host_port);
1204                 } else {
1205                         /* listen address, port */
1206                         packet_put_cstring(c->path);
1207                         packet_put_int(c->listening_port);
1208                 }
1209                 /* originator host and port */
1210                 packet_put_cstring(remote_ipaddr);
1211                 packet_put_int(remote_port);
1212                 packet_send();
1213         } else {
1214                 packet_start(SSH_MSG_PORT_OPEN);
1215                 packet_put_int(c->self);
1216                 packet_put_cstring(c->path);
1217                 packet_put_int(c->host_port);
1218                 if (packet_get_protocol_flags() &
1219                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1220                         packet_put_cstring(c->remote_name);
1221                 packet_send();
1222         }
1223         xfree(remote_ipaddr);
1224 }
1225
1226 /*
1227  * This socket is listening for connections to a forwarded TCP/IP port.
1228  */
1229 static void
1230 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
1231 {
1232         Channel *nc;
1233         struct sockaddr addr;
1234         int newsock, nextstate;
1235         socklen_t addrlen;
1236         char *rtype;
1237
1238         if (FD_ISSET(c->sock, readset)) {
1239                 debug("Connection to port %d forwarding "
1240                     "to %.100s port %d requested.",
1241                     c->listening_port, c->path, c->host_port);
1242
1243                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1244                         nextstate = SSH_CHANNEL_OPENING;
1245                         rtype = "forwarded-tcpip";
1246                 } else {
1247                         if (c->host_port == 0) {
1248                                 nextstate = SSH_CHANNEL_DYNAMIC;
1249                                 rtype = "dynamic-tcpip";
1250                         } else {
1251                                 nextstate = SSH_CHANNEL_OPENING;
1252                                 rtype = "direct-tcpip";
1253                         }
1254                 }
1255
1256                 addrlen = sizeof(addr);
1257                 newsock = accept(c->sock, &addr, &addrlen);
1258                 if (newsock < 0) {
1259                         error("accept: %.100s", strerror(errno));
1260                         return;
1261                 }
1262                 set_nodelay(newsock);
1263                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1264                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1265                 nc->listening_port = c->listening_port;
1266                 nc->host_port = c->host_port;
1267                 strlcpy(nc->path, c->path, sizeof(nc->path));
1268
1269                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1270                         /*
1271                          * do not call the channel_post handler until
1272                          * this flag has been reset by a pre-handler.
1273                          * otherwise the FD_ISSET calls might overflow
1274                          */
1275                         nc->delayed = 1;
1276                 } else {
1277                         port_open_helper(nc, rtype);
1278                 }
1279         }
1280 }
1281
1282 /*
1283  * This is the authentication agent socket listening for connections from
1284  * clients.
1285  */
1286 static void
1287 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
1288 {
1289         Channel *nc;
1290         int newsock;
1291         struct sockaddr addr;
1292         socklen_t addrlen;
1293
1294         if (FD_ISSET(c->sock, readset)) {
1295                 addrlen = sizeof(addr);
1296                 newsock = accept(c->sock, &addr, &addrlen);
1297                 if (newsock < 0) {
1298                         error("accept from auth socket: %.100s", strerror(errno));
1299                         return;
1300                 }
1301                 nc = channel_new("accepted auth socket",
1302                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1303                     c->local_window_max, c->local_maxpacket,
1304                     0, "accepted auth socket", 1);
1305                 if (compat20) {
1306                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1307                         packet_put_cstring("auth-agent@openssh.com");
1308                         packet_put_int(nc->self);
1309                         packet_put_int(c->local_window_max);
1310                         packet_put_int(c->local_maxpacket);
1311                 } else {
1312                         packet_start(SSH_SMSG_AGENT_OPEN);
1313                         packet_put_int(nc->self);
1314                 }
1315                 packet_send();
1316         }
1317 }
1318
1319 static void
1320 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
1321 {
1322         int err = 0;
1323         socklen_t sz = sizeof(err);
1324
1325         if (FD_ISSET(c->sock, writeset)) {
1326                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1327                         err = errno;
1328                         error("getsockopt SO_ERROR failed");
1329                 }
1330                 if (err == 0) {
1331                         debug("channel %d: connected", c->self);
1332                         c->type = SSH_CHANNEL_OPEN;
1333                         if (compat20) {
1334                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1335                                 packet_put_int(c->remote_id);
1336                                 packet_put_int(c->self);
1337                                 packet_put_int(c->local_window);
1338                                 packet_put_int(c->local_maxpacket);
1339                         } else {
1340                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1341                                 packet_put_int(c->remote_id);
1342                                 packet_put_int(c->self);
1343                         }
1344                 } else {
1345                         debug("channel %d: not connected: %s",
1346                             c->self, strerror(err));
1347                         if (compat20) {
1348                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1349                                 packet_put_int(c->remote_id);
1350                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1351                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1352                                         packet_put_cstring(strerror(err));
1353                                         packet_put_cstring("");
1354                                 }
1355                         } else {
1356                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1357                                 packet_put_int(c->remote_id);
1358                         }
1359                         chan_mark_dead(c);
1360                 }
1361                 packet_send();
1362         }
1363 }
1364
1365 static int
1366 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
1367 {
1368         char buf[CHAN_RBUF];
1369         int len;
1370
1371         if (c->rfd != -1 &&
1372             FD_ISSET(c->rfd, readset)) {
1373                 len = read(c->rfd, buf, sizeof(buf));
1374                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1375                         return 1;
1376                 if (len <= 0) {
1377                         debug2("channel %d: read<=0 rfd %d len %d",
1378                             c->self, c->rfd, len);
1379                         if (c->type != SSH_CHANNEL_OPEN) {
1380                                 debug2("channel %d: not open", c->self);
1381                                 chan_mark_dead(c);
1382                                 return -1;
1383                         } else if (compat13) {
1384                                 buffer_clear(&c->output);
1385                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1386                                 debug2("channel %d: input draining.", c->self);
1387                         } else {
1388                                 chan_read_failed(c);
1389                         }
1390                         return -1;
1391                 }
1392                 if (c->input_filter != NULL) {
1393                         if (c->input_filter(c, buf, len) == -1) {
1394                                 debug2("channel %d: filter stops", c->self);
1395                                 chan_read_failed(c);
1396                         }
1397                 } else {
1398                         buffer_append(&c->input, buf, len);
1399                 }
1400         }
1401         return 1;
1402 }
1403 static int
1404 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
1405 {
1406         struct termios tio;
1407         u_char *data;
1408         u_int dlen;
1409         int len;
1410
1411         /* Send buffered output data to the socket. */
1412         if (c->wfd != -1 &&
1413             FD_ISSET(c->wfd, writeset) &&
1414             buffer_len(&c->output) > 0) {
1415                 data = buffer_ptr(&c->output);
1416                 dlen = buffer_len(&c->output);
1417 #ifdef _AIX
1418                 /* XXX: Later AIX versions can't push as much data to tty */
1419                 if (compat20 && c->wfd_isatty)
1420                         dlen = MIN(dlen, 8*1024);
1421 #endif
1422                 len = write(c->wfd, data, dlen);
1423                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1424                         return 1;
1425                 if (len <= 0) {
1426                         if (c->type != SSH_CHANNEL_OPEN) {
1427                                 debug2("channel %d: not open", c->self);
1428                                 chan_mark_dead(c);
1429                                 return -1;
1430                         } else if (compat13) {
1431                                 buffer_clear(&c->output);
1432                                 debug2("channel %d: input draining.", c->self);
1433                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1434                         } else {
1435                                 chan_write_failed(c);
1436                         }
1437                         return -1;
1438                 }
1439                 if (compat20 && c->isatty && dlen >= 1 && data[0] != '\r') {
1440                         if (tcgetattr(c->wfd, &tio) == 0 &&
1441                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1442                                 /*
1443                                  * Simulate echo to reduce the impact of
1444                                  * traffic analysis. We need to match the
1445                                  * size of a SSH2_MSG_CHANNEL_DATA message
1446                                  * (4 byte channel id + data)
1447                                  */
1448                                 packet_send_ignore(4 + len);
1449                                 packet_send();
1450                         }
1451                 }
1452                 buffer_consume(&c->output, len);
1453                 if (compat20 && len > 0) {
1454                         c->local_consumed += len;
1455                 }
1456         }
1457         return 1;
1458 }
1459 static int
1460 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
1461 {
1462         char buf[CHAN_RBUF];
1463         int len;
1464
1465 /** XXX handle drain efd, too */
1466         if (c->efd != -1) {
1467                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1468                     FD_ISSET(c->efd, writeset) &&
1469                     buffer_len(&c->extended) > 0) {
1470                         len = write(c->efd, buffer_ptr(&c->extended),
1471                             buffer_len(&c->extended));
1472                         debug2("channel %d: written %d to efd %d",
1473                             c->self, len, c->efd);
1474                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1475                                 return 1;
1476                         if (len <= 0) {
1477                                 debug2("channel %d: closing write-efd %d",
1478                                     c->self, c->efd);
1479                                 channel_close_fd(&c->efd);
1480                         } else {
1481                                 buffer_consume(&c->extended, len);
1482                                 c->local_consumed += len;
1483                         }
1484                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1485                     FD_ISSET(c->efd, readset)) {
1486                         len = read(c->efd, buf, sizeof(buf));
1487                         debug2("channel %d: read %d from efd %d",
1488                             c->self, len, c->efd);
1489                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1490                                 return 1;
1491                         if (len <= 0) {
1492                                 debug2("channel %d: closing read-efd %d",
1493                                     c->self, c->efd);
1494                                 channel_close_fd(&c->efd);
1495                         } else {
1496                                 buffer_append(&c->extended, buf, len);
1497                         }
1498                 }
1499         }
1500         return 1;
1501 }
1502 static int
1503 channel_handle_ctl(Channel *c, fd_set * readset, fd_set * writeset)
1504 {
1505         char buf[16];
1506         int len;
1507
1508         /* Monitor control fd to detect if the slave client exits */
1509         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1510                 len = read(c->ctl_fd, buf, sizeof(buf));
1511                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1512                         return 1;
1513                 if (len <= 0) {
1514                         debug2("channel %d: ctl read<=0", c->self);
1515                         if (c->type != SSH_CHANNEL_OPEN) {
1516                                 debug2("channel %d: not open", c->self);
1517                                 chan_mark_dead(c);
1518                                 return -1;
1519                         } else {
1520                                 chan_read_failed(c);
1521                                 chan_write_failed(c);
1522                         }
1523                         return -1;
1524                 } else
1525                         fatal("%s: unexpected data on ctl fd", __func__);
1526         }
1527         return 1;
1528 }
1529 static int
1530 channel_check_window(Channel *c)
1531 {
1532         if (c->type == SSH_CHANNEL_OPEN &&
1533             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1534             c->local_window < c->local_window_max/2 &&
1535             c->local_consumed > 0) {
1536                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1537                 packet_put_int(c->remote_id);
1538                 packet_put_int(c->local_consumed);
1539                 packet_send();
1540                 debug2("channel %d: window %d sent adjust %d",
1541                     c->self, c->local_window,
1542                     c->local_consumed);
1543                 c->local_window += c->local_consumed;
1544                 c->local_consumed = 0;
1545         }
1546         return 1;
1547 }
1548
1549 static void
1550 channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
1551 {
1552         if (c->delayed)
1553                 return;
1554         channel_handle_rfd(c, readset, writeset);
1555         channel_handle_wfd(c, readset, writeset);
1556         if (!compat20)
1557                 return;
1558         channel_handle_efd(c, readset, writeset);
1559         channel_handle_ctl(c, readset, writeset);
1560         channel_check_window(c);
1561 }
1562
1563 static void
1564 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
1565 {
1566         int len;
1567
1568         /* Send buffered output data to the socket. */
1569         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1570                 len = write(c->sock, buffer_ptr(&c->output),
1571                             buffer_len(&c->output));
1572                 if (len <= 0)
1573                         buffer_clear(&c->output);
1574                 else
1575                         buffer_consume(&c->output, len);
1576         }
1577 }
1578
1579 static void
1580 channel_handler_init_20(void)
1581 {
1582         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1583         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1584         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1585         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1586         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1587         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1588         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1589         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1590
1591         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1592         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1593         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1594         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1595         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1596         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1597         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1598 }
1599
1600 static void
1601 channel_handler_init_13(void)
1602 {
1603         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1604         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1605         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1606         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1607         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1608         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1609         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1610         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1611         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1612
1613         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1614         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1615         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1616         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1617         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1618         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1619         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1620 }
1621
1622 static void
1623 channel_handler_init_15(void)
1624 {
1625         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1626         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1627         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1628         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1629         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1630         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1631         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1632
1633         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1634         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1635         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1636         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1637         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1638         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1639 }
1640
1641 static void
1642 channel_handler_init(void)
1643 {
1644         int i;
1645
1646         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1647                 channel_pre[i] = NULL;
1648                 channel_post[i] = NULL;
1649         }
1650         if (compat20)
1651                 channel_handler_init_20();
1652         else if (compat13)
1653                 channel_handler_init_13();
1654         else
1655                 channel_handler_init_15();
1656 }
1657
1658 /* gc dead channels */
1659 static void
1660 channel_garbage_collect(Channel *c)
1661 {
1662         if (c == NULL)
1663                 return;
1664         if (c->detach_user != NULL) {
1665                 if (!chan_is_dead(c, 0))
1666                         return;
1667                 debug2("channel %d: gc: notify user", c->self);
1668                 c->detach_user(c->self, NULL);
1669                 /* if we still have a callback */
1670                 if (c->detach_user != NULL)
1671                         return;
1672                 debug2("channel %d: gc: user detached", c->self);
1673         }
1674         if (!chan_is_dead(c, 1))
1675                 return;
1676         debug2("channel %d: garbage collecting", c->self);
1677         channel_free(c);
1678 }
1679
1680 static void
1681 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
1682 {
1683         static int did_init = 0;
1684         u_int i;
1685         Channel *c;
1686
1687         if (!did_init) {
1688                 channel_handler_init();
1689                 did_init = 1;
1690         }
1691         for (i = 0; i < channels_alloc; i++) {
1692                 c = channels[i];
1693                 if (c == NULL)
1694                         continue;
1695                 if (ftab[c->type] != NULL)
1696                         (*ftab[c->type])(c, readset, writeset);
1697                 channel_garbage_collect(c);
1698         }
1699 }
1700
1701 /*
1702  * Allocate/update select bitmasks and add any bits relevant to channels in
1703  * select bitmasks.
1704  */
1705 void
1706 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1707     u_int *nallocp, int rekeying)
1708 {
1709         u_int n, sz;
1710
1711         n = MAX(*maxfdp, channel_max_fd);
1712
1713         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
1714         /* perhaps check sz < nalloc/2 and shrink? */
1715         if (*readsetp == NULL || sz > *nallocp) {
1716                 *readsetp = xrealloc(*readsetp, sz);
1717                 *writesetp = xrealloc(*writesetp, sz);
1718                 *nallocp = sz;
1719         }
1720         *maxfdp = n;
1721         memset(*readsetp, 0, sz);
1722         memset(*writesetp, 0, sz);
1723
1724         if (!rekeying)
1725                 channel_handler(channel_pre, *readsetp, *writesetp);
1726 }
1727
1728 /*
1729  * After select, perform any appropriate operations for channels which have
1730  * events pending.
1731  */
1732 void
1733 channel_after_select(fd_set * readset, fd_set * writeset)
1734 {
1735         channel_handler(channel_post, readset, writeset);
1736 }
1737
1738
1739 /* If there is data to send to the connection, enqueue some of it now. */
1740
1741 void
1742 channel_output_poll(void)
1743 {
1744         Channel *c;
1745         u_int i, len;
1746
1747         for (i = 0; i < channels_alloc; i++) {
1748                 c = channels[i];
1749                 if (c == NULL)
1750                         continue;
1751
1752                 /*
1753                  * We are only interested in channels that can have buffered
1754                  * incoming data.
1755                  */
1756                 if (compat13) {
1757                         if (c->type != SSH_CHANNEL_OPEN &&
1758                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1759                                 continue;
1760                 } else {
1761                         if (c->type != SSH_CHANNEL_OPEN)
1762                                 continue;
1763                 }
1764                 if (compat20 &&
1765                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1766                         /* XXX is this true? */
1767                         debug3("channel %d: will not send data after close", c->self);
1768                         continue;
1769                 }
1770
1771                 /* Get the amount of buffered data for this channel. */
1772                 if ((c->istate == CHAN_INPUT_OPEN ||
1773                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1774                     (len = buffer_len(&c->input)) > 0) {
1775                         /*
1776                          * Send some data for the other side over the secure
1777                          * connection.
1778                          */
1779                         if (compat20) {
1780                                 if (len > c->remote_window)
1781                                         len = c->remote_window;
1782                                 if (len > c->remote_maxpacket)
1783                                         len = c->remote_maxpacket;
1784                         } else {
1785                                 if (packet_is_interactive()) {
1786                                         if (len > 1024)
1787                                                 len = 512;
1788                                 } else {
1789                                         /* Keep the packets at reasonable size. */
1790                                         if (len > packet_get_maxsize()/2)
1791                                                 len = packet_get_maxsize()/2;
1792                                 }
1793                         }
1794                         if (len > 0) {
1795                                 packet_start(compat20 ?
1796                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1797                                 packet_put_int(c->remote_id);
1798                                 packet_put_string(buffer_ptr(&c->input), len);
1799                                 packet_send();
1800                                 buffer_consume(&c->input, len);
1801                                 c->remote_window -= len;
1802                         }
1803                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1804                         if (compat13)
1805                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1806                         /*
1807                          * input-buffer is empty and read-socket shutdown:
1808                          * tell peer, that we will not send more data: send IEOF.
1809                          * hack for extended data: delay EOF if EFD still in use.
1810                          */
1811                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1812                                debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1813                                    c->self, c->efd, buffer_len(&c->extended));
1814                         else
1815                                 chan_ibuf_empty(c);
1816                 }
1817                 /* Send extended data, i.e. stderr */
1818                 if (compat20 &&
1819                     !(c->flags & CHAN_EOF_SENT) &&
1820                     c->remote_window > 0 &&
1821                     (len = buffer_len(&c->extended)) > 0 &&
1822                     c->extended_usage == CHAN_EXTENDED_READ) {
1823                         debug2("channel %d: rwin %u elen %u euse %d",
1824                             c->self, c->remote_window, buffer_len(&c->extended),
1825                             c->extended_usage);
1826                         if (len > c->remote_window)
1827                                 len = c->remote_window;
1828                         if (len > c->remote_maxpacket)
1829                                 len = c->remote_maxpacket;
1830                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1831                         packet_put_int(c->remote_id);
1832                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1833                         packet_put_string(buffer_ptr(&c->extended), len);
1834                         packet_send();
1835                         buffer_consume(&c->extended, len);
1836                         c->remote_window -= len;
1837                         debug2("channel %d: sent ext data %d", c->self, len);
1838                 }
1839         }
1840 }
1841
1842
1843 /* -- protocol input */
1844
1845 void
1846 channel_input_data(int type, u_int32_t seq, void *ctxt)
1847 {
1848         int id;
1849         char *data;
1850         u_int data_len;
1851         Channel *c;
1852
1853         /* Get the channel number and verify it. */
1854         id = packet_get_int();
1855         c = channel_lookup(id);
1856         if (c == NULL)
1857                 packet_disconnect("Received data for nonexistent channel %d.", id);
1858
1859         /* Ignore any data for non-open channels (might happen on close) */
1860         if (c->type != SSH_CHANNEL_OPEN &&
1861             c->type != SSH_CHANNEL_X11_OPEN)
1862                 return;
1863
1864         /* Get the data. */
1865         data = packet_get_string(&data_len);
1866
1867         /*
1868          * Ignore data for protocol > 1.3 if output end is no longer open.
1869          * For protocol 2 the sending side is reducing its window as it sends
1870          * data, so we must 'fake' consumption of the data in order to ensure
1871          * that window updates are sent back.  Otherwise the connection might
1872          * deadlock.
1873          */
1874         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1875                 if (compat20) {
1876                         c->local_window -= data_len;
1877                         c->local_consumed += data_len;
1878                 }
1879                 xfree(data);
1880                 return;
1881         }
1882
1883         if (compat20) {
1884                 if (data_len > c->local_maxpacket) {
1885                         logit("channel %d: rcvd big packet %d, maxpack %d",
1886                             c->self, data_len, c->local_maxpacket);
1887                 }
1888                 if (data_len > c->local_window) {
1889                         logit("channel %d: rcvd too much data %d, win %d",
1890                             c->self, data_len, c->local_window);
1891                         xfree(data);
1892                         return;
1893                 }
1894                 c->local_window -= data_len;
1895         }
1896         packet_check_eom();
1897         buffer_append(&c->output, data, data_len);
1898         xfree(data);
1899 }
1900
1901 void
1902 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
1903 {
1904         int id;
1905         char *data;
1906         u_int data_len, tcode;
1907         Channel *c;
1908
1909         /* Get the channel number and verify it. */
1910         id = packet_get_int();
1911         c = channel_lookup(id);
1912
1913         if (c == NULL)
1914                 packet_disconnect("Received extended_data for bad channel %d.", id);
1915         if (c->type != SSH_CHANNEL_OPEN) {
1916                 logit("channel %d: ext data for non open", id);
1917                 return;
1918         }
1919         if (c->flags & CHAN_EOF_RCVD) {
1920                 if (datafellows & SSH_BUG_EXTEOF)
1921                         debug("channel %d: accepting ext data after eof", id);
1922                 else
1923                         packet_disconnect("Received extended_data after EOF "
1924                             "on channel %d.", id);
1925         }
1926         tcode = packet_get_int();
1927         if (c->efd == -1 ||
1928             c->extended_usage != CHAN_EXTENDED_WRITE ||
1929             tcode != SSH2_EXTENDED_DATA_STDERR) {
1930                 logit("channel %d: bad ext data", c->self);
1931                 return;
1932         }
1933         data = packet_get_string(&data_len);
1934         packet_check_eom();
1935         if (data_len > c->local_window) {
1936                 logit("channel %d: rcvd too much extended_data %d, win %d",
1937                     c->self, data_len, c->local_window);
1938                 xfree(data);
1939                 return;
1940         }
1941         debug2("channel %d: rcvd ext data %d", c->self, data_len);
1942         c->local_window -= data_len;
1943         buffer_append(&c->extended, data, data_len);
1944         xfree(data);
1945 }
1946
1947 void
1948 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
1949 {
1950         int id;
1951         Channel *c;
1952
1953         id = packet_get_int();
1954         packet_check_eom();
1955         c = channel_lookup(id);
1956         if (c == NULL)
1957                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
1958         chan_rcvd_ieof(c);
1959
1960         /* XXX force input close */
1961         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
1962                 debug("channel %d: FORCE input drain", c->self);
1963                 c->istate = CHAN_INPUT_WAIT_DRAIN;
1964                 if (buffer_len(&c->input) == 0)
1965                         chan_ibuf_empty(c);
1966         }
1967
1968 }
1969
1970 void
1971 channel_input_close(int type, u_int32_t seq, void *ctxt)
1972 {
1973         int id;
1974         Channel *c;
1975
1976         id = packet_get_int();
1977         packet_check_eom();
1978         c = channel_lookup(id);
1979         if (c == NULL)
1980                 packet_disconnect("Received close for nonexistent channel %d.", id);
1981
1982         /*
1983          * Send a confirmation that we have closed the channel and no more
1984          * data is coming for it.
1985          */
1986         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
1987         packet_put_int(c->remote_id);
1988         packet_send();
1989
1990         /*
1991          * If the channel is in closed state, we have sent a close request,
1992          * and the other side will eventually respond with a confirmation.
1993          * Thus, we cannot free the channel here, because then there would be
1994          * no-one to receive the confirmation.  The channel gets freed when
1995          * the confirmation arrives.
1996          */
1997         if (c->type != SSH_CHANNEL_CLOSED) {
1998                 /*
1999                  * Not a closed channel - mark it as draining, which will
2000                  * cause it to be freed later.
2001                  */
2002                 buffer_clear(&c->input);
2003                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2004         }
2005 }
2006
2007 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2008 void
2009 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2010 {
2011         int id = packet_get_int();
2012         Channel *c = channel_lookup(id);
2013
2014         packet_check_eom();
2015         if (c == NULL)
2016                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2017         chan_rcvd_oclose(c);
2018 }
2019
2020 void
2021 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2022 {
2023         int id = packet_get_int();
2024         Channel *c = channel_lookup(id);
2025
2026         packet_check_eom();
2027         if (c == NULL)
2028                 packet_disconnect("Received close confirmation for "
2029                     "out-of-range channel %d.", id);
2030         if (c->type != SSH_CHANNEL_CLOSED)
2031                 packet_disconnect("Received close confirmation for "
2032                     "non-closed channel %d (type %d).", id, c->type);
2033         channel_free(c);
2034 }
2035
2036 void
2037 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2038 {
2039         int id, remote_id;
2040         Channel *c;
2041
2042         id = packet_get_int();
2043         c = channel_lookup(id);
2044
2045         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2046                 packet_disconnect("Received open confirmation for "
2047                     "non-opening channel %d.", id);
2048         remote_id = packet_get_int();
2049         /* Record the remote channel number and mark that the channel is now open. */
2050         c->remote_id = remote_id;
2051         c->type = SSH_CHANNEL_OPEN;
2052
2053         if (compat20) {
2054                 c->remote_window = packet_get_int();
2055                 c->remote_maxpacket = packet_get_int();
2056                 if (c->confirm) {
2057                         debug2("callback start");
2058                         c->confirm(c->self, c->confirm_ctx);
2059                         debug2("callback done");
2060                 }
2061                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2062                     c->remote_window, c->remote_maxpacket);
2063         }
2064         packet_check_eom();
2065 }
2066
2067 static char *
2068 reason2txt(int reason)
2069 {
2070         switch (reason) {
2071         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2072                 return "administratively prohibited";
2073         case SSH2_OPEN_CONNECT_FAILED:
2074                 return "connect failed";
2075         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2076                 return "unknown channel type";
2077         case SSH2_OPEN_RESOURCE_SHORTAGE:
2078                 return "resource shortage";
2079         }
2080         return "unknown reason";
2081 }
2082
2083 void
2084 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2085 {
2086         int id, reason;
2087         char *msg = NULL, *lang = NULL;
2088         Channel *c;
2089
2090         id = packet_get_int();
2091         c = channel_lookup(id);
2092
2093         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2094                 packet_disconnect("Received open failure for "
2095                     "non-opening channel %d.", id);
2096         if (compat20) {
2097                 reason = packet_get_int();
2098                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2099                         msg  = packet_get_string(NULL);
2100                         lang = packet_get_string(NULL);
2101                 }
2102                 logit("channel %d: open failed: %s%s%s", id,
2103                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2104                 if (msg != NULL)
2105                         xfree(msg);
2106                 if (lang != NULL)
2107                         xfree(lang);
2108         }
2109         packet_check_eom();
2110         /* Free the channel.  This will also close the socket. */
2111         channel_free(c);
2112 }
2113
2114 void
2115 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2116 {
2117         Channel *c;
2118         int id;
2119         u_int adjust;
2120
2121         if (!compat20)
2122                 return;
2123
2124         /* Get the channel number and verify it. */
2125         id = packet_get_int();
2126         c = channel_lookup(id);
2127
2128         if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
2129                 logit("Received window adjust for "
2130                     "non-open channel %d.", id);
2131                 return;
2132         }
2133         adjust = packet_get_int();
2134         packet_check_eom();
2135         debug2("channel %d: rcvd adjust %u", id, adjust);
2136         c->remote_window += adjust;
2137 }
2138
2139 void
2140 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2141 {
2142         Channel *c = NULL;
2143         u_short host_port;
2144         char *host, *originator_string;
2145         int remote_id, sock = -1;
2146
2147         remote_id = packet_get_int();
2148         host = packet_get_string(NULL);
2149         host_port = packet_get_int();
2150
2151         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2152                 originator_string = packet_get_string(NULL);
2153         } else {
2154                 originator_string = xstrdup("unknown (remote did not supply name)");
2155         }
2156         packet_check_eom();
2157         sock = channel_connect_to(host, host_port);
2158         if (sock != -1) {
2159                 c = channel_new("connected socket",
2160                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2161                     originator_string, 1);
2162                 c->remote_id = remote_id;
2163         }
2164         xfree(originator_string);
2165         if (c == NULL) {
2166                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2167                 packet_put_int(remote_id);
2168                 packet_send();
2169         }
2170         xfree(host);
2171 }
2172
2173
2174 /* -- tcp forwarding */
2175
2176 void
2177 channel_set_af(int af)
2178 {
2179         IPv4or6 = af;
2180 }
2181
2182 static int
2183 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2184     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2185 {
2186         Channel *c;
2187         int sock, r, success = 0, on = 1, wildcard = 0, is_client;
2188         struct addrinfo hints, *ai, *aitop;
2189         const char *host, *addr;
2190         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2191
2192         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2193             listen_addr : host_to_connect;
2194         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2195
2196         if (host == NULL) {
2197                 error("No forward host name.");
2198                 return success;
2199         }
2200         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2201                 error("Forward host name too long.");
2202                 return success;
2203         }
2204
2205         /*
2206          * Determine whether or not a port forward listens to loopback,
2207          * specified address or wildcard. On the client, a specified bind
2208          * address will always override gateway_ports. On the server, a
2209          * gateway_ports of 1 (``yes'') will override the client's
2210          * specification and force a wildcard bind, whereas a value of 2
2211          * (``clientspecified'') will bind to whatever address the client
2212          * asked for.
2213          *
2214          * Special-case listen_addrs are:
2215          *
2216          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2217          * "" (empty string), "*"  -> wildcard v4/v6
2218          * "localhost"             -> loopback v4/v6
2219          */
2220         addr = NULL;
2221         if (listen_addr == NULL) {
2222                 /* No address specified: default to gateway_ports setting */
2223                 if (gateway_ports)
2224                         wildcard = 1;
2225         } else if (gateway_ports || is_client) {
2226                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2227                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2228                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2229                     (!is_client && gateway_ports == 1))
2230                         wildcard = 1;
2231                 else if (strcmp(listen_addr, "localhost") != 0)
2232                         addr = listen_addr;
2233         }
2234
2235         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2236             type, wildcard, (addr == NULL) ? "NULL" : addr);
2237
2238         /*
2239          * getaddrinfo returns a loopback address if the hostname is
2240          * set to NULL and hints.ai_flags is not AI_PASSIVE
2241          */
2242         memset(&hints, 0, sizeof(hints));
2243         hints.ai_family = IPv4or6;
2244         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2245         hints.ai_socktype = SOCK_STREAM;
2246         snprintf(strport, sizeof strport, "%d", listen_port);
2247         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2248                 if (addr == NULL) {
2249                         /* This really shouldn't happen */
2250                         packet_disconnect("getaddrinfo: fatal error: %s",
2251                             gai_strerror(r));
2252                 } else {
2253                         verbose("channel_setup_fwd_listener: "
2254                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2255                         packet_send_debug("channel_setup_fwd_listener: "
2256                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2257                 }
2258                 aitop = NULL;
2259         }
2260
2261         for (ai = aitop; ai; ai = ai->ai_next) {
2262                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2263                         continue;
2264                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2265                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2266                         error("channel_setup_fwd_listener: getnameinfo failed");
2267                         continue;
2268                 }
2269                 /* Create a port to listen for the host. */
2270                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2271                 if (sock < 0) {
2272                         /* this is no error since kernel may not support ipv6 */
2273                         verbose("socket: %.100s", strerror(errno));
2274                         continue;
2275                 }
2276                 /*
2277                  * Set socket options.
2278                  * Allow local port reuse in TIME_WAIT.
2279                  */
2280                 if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on,
2281                     sizeof(on)) == -1)
2282                         error("setsockopt SO_REUSEADDR: %s", strerror(errno));
2283
2284                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2285
2286                 /* Bind the socket to the address. */
2287                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2288                         /* address can be in use ipv6 address is already bound */
2289                         if (!ai->ai_next)
2290                                 error("bind: %.100s", strerror(errno));
2291                         else
2292                                 verbose("bind: %.100s", strerror(errno));
2293
2294                         close(sock);
2295                         continue;
2296                 }
2297                 /* Start listening for connections on the socket. */
2298                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2299                         error("listen: %.100s", strerror(errno));
2300                         close(sock);
2301                         continue;
2302                 }
2303                 /* Allocate a channel number for the socket. */
2304                 c = channel_new("port listener", type, sock, sock, -1,
2305                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2306                     0, "port listener", 1);
2307                 strlcpy(c->path, host, sizeof(c->path));
2308                 c->host_port = port_to_connect;
2309                 c->listening_port = listen_port;
2310                 success = 1;
2311         }
2312         if (success == 0)
2313                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2314                     listen_port);
2315         freeaddrinfo(aitop);
2316         return success;
2317 }
2318
2319 int
2320 channel_cancel_rport_listener(const char *host, u_short port)
2321 {
2322         u_int i;
2323         int found = 0;
2324
2325         for (i = 0; i < channels_alloc; i++) {
2326                 Channel *c = channels[i];
2327
2328                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2329                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2330                     c->listening_port == port) {
2331                         debug2("%s: close channel %d", __func__, i);
2332                         channel_free(c);
2333                         found = 1;
2334                 }
2335         }
2336
2337         return (found);
2338 }
2339
2340 /* protocol local port fwd, used by ssh (and sshd in v1) */
2341 int
2342 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2343     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2344 {
2345         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2346             listen_host, listen_port, host_to_connect, port_to_connect,
2347             gateway_ports);
2348 }
2349
2350 /* protocol v2 remote port fwd, used by sshd */
2351 int
2352 channel_setup_remote_fwd_listener(const char *listen_address,
2353     u_short listen_port, int gateway_ports)
2354 {
2355         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2356             listen_address, listen_port, NULL, 0, gateway_ports);
2357 }
2358
2359 /*
2360  * Initiate forwarding of connections to port "port" on remote host through
2361  * the secure channel to host:port from local side.
2362  */
2363
2364 void
2365 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2366     const char *host_to_connect, u_short port_to_connect)
2367 {
2368         int type, success = 0;
2369
2370         /* Record locally that connection to this host/port is permitted. */
2371         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2372                 fatal("channel_request_remote_forwarding: too many forwards");
2373
2374         /* Send the forward request to the remote side. */
2375         if (compat20) {
2376                 const char *address_to_bind;
2377                 if (listen_host == NULL)
2378                         address_to_bind = "localhost";
2379                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2380                         address_to_bind = "";
2381                 else
2382                         address_to_bind = listen_host;
2383
2384                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2385                 packet_put_cstring("tcpip-forward");
2386                 packet_put_char(1);                     /* boolean: want reply */
2387                 packet_put_cstring(address_to_bind);
2388                 packet_put_int(listen_port);
2389                 packet_send();
2390                 packet_write_wait();
2391                 /* Assume that server accepts the request */
2392                 success = 1;
2393         } else {
2394                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2395                 packet_put_int(listen_port);
2396                 packet_put_cstring(host_to_connect);
2397                 packet_put_int(port_to_connect);
2398                 packet_send();
2399                 packet_write_wait();
2400
2401                 /* Wait for response from the remote side. */
2402                 type = packet_read();
2403                 switch (type) {
2404                 case SSH_SMSG_SUCCESS:
2405                         success = 1;
2406                         break;
2407                 case SSH_SMSG_FAILURE:
2408                         logit("Warning: Server denied remote port forwarding.");
2409                         break;
2410                 default:
2411                         /* Unknown packet */
2412                         packet_disconnect("Protocol error for port forward request:"
2413                             "received packet type %d.", type);
2414                 }
2415         }
2416         if (success) {
2417                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2418                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2419                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2420                 num_permitted_opens++;
2421         }
2422 }
2423
2424 /*
2425  * Request cancellation of remote forwarding of connection host:port from
2426  * local side.
2427  */
2428 void
2429 channel_request_rforward_cancel(const char *host, u_short port)
2430 {
2431         int i;
2432
2433         if (!compat20)
2434                 return;
2435
2436         for (i = 0; i < num_permitted_opens; i++) {
2437                 if (permitted_opens[i].host_to_connect != NULL &&
2438                     permitted_opens[i].listen_port == port)
2439                         break;
2440         }
2441         if (i >= num_permitted_opens) {
2442                 debug("%s: requested forward not found", __func__);
2443                 return;
2444         }
2445         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2446         packet_put_cstring("cancel-tcpip-forward");
2447         packet_put_char(0);
2448         packet_put_cstring(host == NULL ? "" : host);
2449         packet_put_int(port);
2450         packet_send();
2451
2452         permitted_opens[i].listen_port = 0;
2453         permitted_opens[i].port_to_connect = 0;
2454         free(permitted_opens[i].host_to_connect);
2455         permitted_opens[i].host_to_connect = NULL;
2456 }
2457
2458 /*
2459  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2460  * listening for the port, and sends back a success reply (or disconnect
2461  * message if there was an error).  This never returns if there was an error.
2462  */
2463
2464 void
2465 channel_input_port_forward_request(int is_root, int gateway_ports)
2466 {
2467         u_short port, host_port;
2468         char *hostname;
2469
2470         /* Get arguments from the packet. */
2471         port = packet_get_int();
2472         hostname = packet_get_string(NULL);
2473         host_port = packet_get_int();
2474
2475 #ifndef HAVE_CYGWIN
2476         /*
2477          * Check that an unprivileged user is not trying to forward a
2478          * privileged port.
2479          */
2480         if (port < IPPORT_RESERVED && !is_root)
2481                 packet_disconnect(
2482                     "Requested forwarding of port %d but user is not root.",
2483                     port);
2484         if (host_port == 0)
2485                 packet_disconnect("Dynamic forwarding denied.");
2486 #endif
2487
2488         /* Initiate forwarding */
2489         channel_setup_local_fwd_listener(NULL, port, hostname,
2490             host_port, gateway_ports);
2491
2492         /* Free the argument string. */
2493         xfree(hostname);
2494 }
2495
2496 /*
2497  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2498  * usually called by the server, because the user could connect to any port
2499  * anyway, and the server has no way to know but to trust the client anyway.
2500  */
2501 void
2502 channel_permit_all_opens(void)
2503 {
2504         if (num_permitted_opens == 0)
2505                 all_opens_permitted = 1;
2506 }
2507
2508 void
2509 channel_add_permitted_opens(char *host, int port)
2510 {
2511         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2512                 fatal("channel_request_remote_forwarding: too many forwards");
2513         debug("allow port forwarding to host %s port %d", host, port);
2514
2515         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2516         permitted_opens[num_permitted_opens].port_to_connect = port;
2517         num_permitted_opens++;
2518
2519         all_opens_permitted = 0;
2520 }
2521
2522 void
2523 channel_clear_permitted_opens(void)
2524 {
2525         int i;
2526
2527         for (i = 0; i < num_permitted_opens; i++)
2528                 if (permitted_opens[i].host_to_connect != NULL)
2529                         xfree(permitted_opens[i].host_to_connect);
2530         num_permitted_opens = 0;
2531
2532 }
2533
2534
2535 /* return socket to remote host, port */
2536 static int
2537 connect_to(const char *host, u_short port)
2538 {
2539         struct addrinfo hints, *ai, *aitop;
2540         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2541         int gaierr;
2542         int sock = -1;
2543
2544         memset(&hints, 0, sizeof(hints));
2545         hints.ai_family = IPv4or6;
2546         hints.ai_socktype = SOCK_STREAM;
2547         snprintf(strport, sizeof strport, "%d", port);
2548         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2549                 error("connect_to %.100s: unknown host (%s)", host,
2550                     gai_strerror(gaierr));
2551                 return -1;
2552         }
2553         for (ai = aitop; ai; ai = ai->ai_next) {
2554                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2555                         continue;
2556                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2557                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2558                         error("connect_to: getnameinfo failed");
2559                         continue;
2560                 }
2561                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2562                 if (sock < 0) {
2563                         if (ai->ai_next == NULL)
2564                                 error("socket: %.100s", strerror(errno));
2565                         else
2566                                 verbose("socket: %.100s", strerror(errno));
2567                         continue;
2568                 }
2569                 if (set_nonblock(sock) == -1)
2570                         fatal("%s: set_nonblock(%d)", __func__, sock);
2571                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2572                     errno != EINPROGRESS) {
2573                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2574                             strerror(errno));
2575                         close(sock);
2576                         continue;       /* fail -- try next */
2577                 }
2578                 break; /* success */
2579
2580         }
2581         freeaddrinfo(aitop);
2582         if (!ai) {
2583                 error("connect_to %.100s port %d: failed.", host, port);
2584                 return -1;
2585         }
2586         /* success */
2587         set_nodelay(sock);
2588         return sock;
2589 }
2590
2591 int
2592 channel_connect_by_listen_address(u_short listen_port)
2593 {
2594         int i;
2595
2596         for (i = 0; i < num_permitted_opens; i++)
2597                 if (permitted_opens[i].host_to_connect != NULL &&
2598                     permitted_opens[i].listen_port == listen_port)
2599                         return connect_to(
2600                             permitted_opens[i].host_to_connect,
2601                             permitted_opens[i].port_to_connect);
2602         error("WARNING: Server requests forwarding for unknown listen_port %d",
2603             listen_port);
2604         return -1;
2605 }
2606
2607 /* Check if connecting to that port is permitted and connect. */
2608 int
2609 channel_connect_to(const char *host, u_short port)
2610 {
2611         int i, permit;
2612
2613         permit = all_opens_permitted;
2614         if (!permit) {
2615                 for (i = 0; i < num_permitted_opens; i++)
2616                         if (permitted_opens[i].host_to_connect != NULL &&
2617                             permitted_opens[i].port_to_connect == port &&
2618                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2619                                 permit = 1;
2620
2621         }
2622         if (!permit) {
2623                 logit("Received request to connect to host %.100s port %d, "
2624                     "but the request was denied.", host, port);
2625                 return -1;
2626         }
2627         return connect_to(host, port);
2628 }
2629
2630 void
2631 channel_send_window_changes(void)
2632 {
2633         u_int i;
2634         struct winsize ws;
2635
2636         for (i = 0; i < channels_alloc; i++) {
2637                 if (channels[i] == NULL || !channels[i]->client_tty ||
2638                     channels[i]->type != SSH_CHANNEL_OPEN)
2639                         continue;
2640                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2641                         continue;
2642                 channel_request_start(i, "window-change", 0);
2643                 packet_put_int(ws.ws_col);
2644                 packet_put_int(ws.ws_row);
2645                 packet_put_int(ws.ws_xpixel);
2646                 packet_put_int(ws.ws_ypixel);
2647                 packet_send();
2648         }
2649 }
2650
2651 /* -- X11 forwarding */
2652
2653 /*
2654  * Creates an internet domain socket for listening for X11 connections.
2655  * Returns 0 and a suitable display number for the DISPLAY variable
2656  * stored in display_numberp , or -1 if an error occurs.
2657  */
2658 int
2659 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2660     int single_connection, u_int *display_numberp)
2661 {
2662         Channel *nc = NULL;
2663         int display_number, sock;
2664         u_short port;
2665         struct addrinfo hints, *ai, *aitop;
2666         char strport[NI_MAXSERV];
2667         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2668
2669         for (display_number = x11_display_offset;
2670             display_number < MAX_DISPLAYS;
2671             display_number++) {
2672                 port = 6000 + display_number;
2673                 memset(&hints, 0, sizeof(hints));
2674                 hints.ai_family = IPv4or6;
2675                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2676                 hints.ai_socktype = SOCK_STREAM;
2677                 snprintf(strport, sizeof strport, "%d", port);
2678                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2679                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2680                         return -1;
2681                 }
2682                 for (ai = aitop; ai; ai = ai->ai_next) {
2683                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2684                                 continue;
2685                         sock = socket(ai->ai_family, ai->ai_socktype,
2686                             ai->ai_protocol);
2687                         if (sock < 0) {
2688                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2689                                         error("socket: %.100s", strerror(errno));
2690                                         freeaddrinfo(aitop);
2691                                         return -1;
2692                                 } else {
2693                                         debug("x11_create_display_inet: Socket family %d not supported",
2694                                                  ai->ai_family);
2695                                         continue;
2696                                 }
2697                         }
2698 #ifdef IPV6_V6ONLY
2699                         if (ai->ai_family == AF_INET6) {
2700                                 int on = 1;
2701                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2702                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2703                         }
2704 #endif
2705                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2706                                 debug2("bind port %d: %.100s", port, strerror(errno));
2707                                 close(sock);
2708
2709                                 if (ai->ai_next)
2710                                         continue;
2711
2712                                 for (n = 0; n < num_socks; n++) {
2713                                         close(socks[n]);
2714                                 }
2715                                 num_socks = 0;
2716                                 break;
2717                         }
2718                         socks[num_socks++] = sock;
2719 #ifndef DONT_TRY_OTHER_AF
2720                         if (num_socks == NUM_SOCKS)
2721                                 break;
2722 #else
2723                         if (x11_use_localhost) {
2724                                 if (num_socks == NUM_SOCKS)
2725                                         break;
2726                         } else {
2727                                 break;
2728                         }
2729 #endif
2730                 }
2731                 freeaddrinfo(aitop);
2732                 if (num_socks > 0)
2733                         break;
2734         }
2735         if (display_number >= MAX_DISPLAYS) {
2736                 error("Failed to allocate internet-domain X11 display socket.");
2737                 return -1;
2738         }
2739         /* Start listening for connections on the socket. */
2740         for (n = 0; n < num_socks; n++) {
2741                 sock = socks[n];
2742                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2743                         error("listen: %.100s", strerror(errno));
2744                         close(sock);
2745                         return -1;
2746                 }
2747         }
2748
2749         /* Allocate a channel for each socket. */
2750         for (n = 0; n < num_socks; n++) {
2751                 sock = socks[n];
2752                 nc = channel_new("x11 listener",
2753                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2754                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2755                     0, "X11 inet listener", 1);
2756                 nc->single_connection = single_connection;
2757         }
2758
2759         /* Return the display number for the DISPLAY environment variable. */
2760         *display_numberp = display_number;
2761         return (0);
2762 }
2763
2764 static int
2765 connect_local_xsocket(u_int dnr)
2766 {
2767         int sock;
2768         struct sockaddr_un addr;
2769
2770         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2771         if (sock < 0)
2772                 error("socket: %.100s", strerror(errno));
2773         memset(&addr, 0, sizeof(addr));
2774         addr.sun_family = AF_UNIX;
2775         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2776         if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2777                 return sock;
2778         close(sock);
2779         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2780         return -1;
2781 }
2782
2783 int
2784 x11_connect_display(void)
2785 {
2786         int display_number, sock = 0;
2787         const char *display;
2788         char buf[1024], *cp;
2789         struct addrinfo hints, *ai, *aitop;
2790         char strport[NI_MAXSERV];
2791         int gaierr;
2792
2793         /* Try to open a socket for the local X server. */
2794         display = getenv("DISPLAY");
2795         if (!display) {
2796                 error("DISPLAY not set.");
2797                 return -1;
2798         }
2799         /*
2800          * Now we decode the value of the DISPLAY variable and make a
2801          * connection to the real X server.
2802          */
2803
2804         /*
2805          * Check if it is a unix domain socket.  Unix domain displays are in
2806          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2807          */
2808         if (strncmp(display, "unix:", 5) == 0 ||
2809             display[0] == ':') {
2810                 /* Connect to the unix domain socket. */
2811                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2812                         error("Could not parse display number from DISPLAY: %.100s",
2813                             display);
2814                         return -1;
2815                 }
2816                 /* Create a socket. */
2817                 sock = connect_local_xsocket(display_number);
2818                 if (sock < 0)
2819                         return -1;
2820
2821                 /* OK, we now have a connection to the display. */
2822                 return sock;
2823         }
2824         /*
2825          * Connect to an inet socket.  The DISPLAY value is supposedly
2826          * hostname:d[.s], where hostname may also be numeric IP address.
2827          */
2828         strlcpy(buf, display, sizeof(buf));
2829         cp = strchr(buf, ':');
2830         if (!cp) {
2831                 error("Could not find ':' in DISPLAY: %.100s", display);
2832                 return -1;
2833         }
2834         *cp = 0;
2835         /* buf now contains the host name.  But first we parse the display number. */
2836         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2837                 error("Could not parse display number from DISPLAY: %.100s",
2838                     display);
2839                 return -1;
2840         }
2841
2842         /* Look up the host address */
2843         memset(&hints, 0, sizeof(hints));
2844         hints.ai_family = IPv4or6;
2845         hints.ai_socktype = SOCK_STREAM;
2846         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2847         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2848                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2849                 return -1;
2850         }
2851         for (ai = aitop; ai; ai = ai->ai_next) {
2852                 /* Create a socket. */
2853                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2854                 if (sock < 0) {
2855                         debug2("socket: %.100s", strerror(errno));
2856                         continue;
2857                 }
2858                 /* Connect it to the display. */
2859                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2860                         debug2("connect %.100s port %d: %.100s", buf,
2861                             6000 + display_number, strerror(errno));
2862                         close(sock);
2863                         continue;
2864                 }
2865                 /* Success */
2866                 break;
2867         }
2868         freeaddrinfo(aitop);
2869         if (!ai) {
2870                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2871                     strerror(errno));
2872                 return -1;
2873         }
2874         set_nodelay(sock);
2875         return sock;
2876 }
2877
2878 /*
2879  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2880  * the remote channel number.  We should do whatever we want, and respond
2881  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2882  */
2883
2884 void
2885 x11_input_open(int type, u_int32_t seq, void *ctxt)
2886 {
2887         Channel *c = NULL;
2888         int remote_id, sock = 0;
2889         char *remote_host;
2890
2891         debug("Received X11 open request.");
2892
2893         remote_id = packet_get_int();
2894
2895         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2896                 remote_host = packet_get_string(NULL);
2897         } else {
2898                 remote_host = xstrdup("unknown (remote did not supply name)");
2899         }
2900         packet_check_eom();
2901
2902         /* Obtain a connection to the real X display. */
2903         sock = x11_connect_display();
2904         if (sock != -1) {
2905                 /* Allocate a channel for this connection. */
2906                 c = channel_new("connected x11 socket",
2907                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
2908                     remote_host, 1);
2909                 c->remote_id = remote_id;
2910                 c->force_drain = 1;
2911         }
2912         xfree(remote_host);
2913         if (c == NULL) {
2914                 /* Send refusal to the remote host. */
2915                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2916                 packet_put_int(remote_id);
2917         } else {
2918                 /* Send a confirmation to the remote host. */
2919                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2920                 packet_put_int(remote_id);
2921                 packet_put_int(c->self);
2922         }
2923         packet_send();
2924 }
2925
2926 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
2927 void
2928 deny_input_open(int type, u_int32_t seq, void *ctxt)
2929 {
2930         int rchan = packet_get_int();
2931
2932         switch (type) {
2933         case SSH_SMSG_AGENT_OPEN:
2934                 error("Warning: ssh server tried agent forwarding.");
2935                 break;
2936         case SSH_SMSG_X11_OPEN:
2937                 error("Warning: ssh server tried X11 forwarding.");
2938                 break;
2939         default:
2940                 error("deny_input_open: type %d", type);
2941                 break;
2942         }
2943         error("Warning: this is probably a break in attempt by a malicious server.");
2944         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2945         packet_put_int(rchan);
2946         packet_send();
2947 }
2948
2949 /*
2950  * Requests forwarding of X11 connections, generates fake authentication
2951  * data, and enables authentication spoofing.
2952  * This should be called in the client only.
2953  */
2954 void
2955 x11_request_forwarding_with_spoofing(int client_session_id,
2956     const char *proto, const char *data)
2957 {
2958         u_int data_len = (u_int) strlen(data) / 2;
2959         u_int i, value, len;
2960         char *new_data;
2961         int screen_number;
2962         const char *cp;
2963         u_int32_t rnd = 0;
2964
2965         cp = getenv("DISPLAY");
2966         if (cp)
2967                 cp = strchr(cp, ':');
2968         if (cp)
2969                 cp = strchr(cp, '.');
2970         if (cp)
2971                 screen_number = atoi(cp + 1);
2972         else
2973                 screen_number = 0;
2974
2975         /* Save protocol name. */
2976         x11_saved_proto = xstrdup(proto);
2977
2978         /*
2979          * Extract real authentication data and generate fake data of the
2980          * same length.
2981          */
2982         x11_saved_data = xmalloc(data_len);
2983         x11_fake_data = xmalloc(data_len);
2984         for (i = 0; i < data_len; i++) {
2985                 if (sscanf(data + 2 * i, "%2x", &value) != 1)
2986                         fatal("x11_request_forwarding: bad authentication data: %.100s", data);
2987                 if (i % 4 == 0)
2988                         rnd = arc4random();
2989                 x11_saved_data[i] = value;
2990                 x11_fake_data[i] = rnd & 0xff;
2991                 rnd >>= 8;
2992         }
2993         x11_saved_data_len = data_len;
2994         x11_fake_data_len = data_len;
2995
2996         /* Convert the fake data into hex. */
2997         len = 2 * data_len + 1;
2998         new_data = xmalloc(len);
2999         for (i = 0; i < data_len; i++)
3000                 snprintf(new_data + 2 * i, len - 2 * i,
3001                     "%02x", (u_char) x11_fake_data[i]);
3002
3003         /* Send the request packet. */
3004         if (compat20) {
3005                 channel_request_start(client_session_id, "x11-req", 0);
3006                 packet_put_char(0);     /* XXX bool single connection */
3007         } else {
3008                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3009         }
3010         packet_put_cstring(proto);
3011         packet_put_cstring(new_data);
3012         packet_put_int(screen_number);
3013         packet_send();
3014         packet_write_wait();
3015         xfree(new_data);
3016 }
3017
3018
3019 /* -- agent forwarding */
3020
3021 /* Sends a message to the server to request authentication fd forwarding. */
3022
3023 void
3024 auth_request_forwarding(void)
3025 {
3026         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3027         packet_send();
3028         packet_write_wait();
3029 }