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 1.167 2002/02/06 14:55:15 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 "uidswap.h"
  50 #include "log.h"
  51 #include "misc.h"
  52 #include "channels.h"
  53 #include "compat.h"
  54 #include "canohost.h"
  55 #include "key.h"
  56 #include "authfd.h"
  57 #include "pathnames.h"
  58
  59
  60 /* -- channel core */
  61
  62 /*
  63  * Pointer to an array containing all allocated channels.  The array is
  64  * dynamically extended as needed.
  65  */
  66 static Channel **channels = NULL;
  67
  68 /*
  69  * Size of the channel array.  All slots of the array must always be
  70  * initialized (at least the type field); unused slots set to NULL
  71  */
  72 static int channels_alloc = 0;
  73
  74 /*
  75  * Maximum file descriptor value used in any of the channels.  This is
  76  * updated in channel_new.
  77  */
  78 static int channel_max_fd = 0;
  79
  80
  81 /* -- tcp forwarding */
  82
  83 /*
  84  * Data structure for storing which hosts are permitted for forward requests.
  85  * The local sides of any remote forwards are stored in this array to prevent
  86  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  87  * network (which might be behind a firewall).
  88  */
  89 typedef struct {
  90         char *host_to_connect;          /* Connect to 'host'. */
  91         u_short port_to_connect;        /* Connect to 'port'. */
  92         u_short listen_port;            /* Remote side should listen port number. */
  93 } ForwardPermission;
  94
  95 /* List of all permitted host/port pairs to connect. */
  96 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
  97
  98 /* Number of permitted host/port pairs in the array. */
  99 static int num_permitted_opens = 0;
 100 /*
 101  * If this is true, all opens are permitted.  This is the case on the server
 102  * on which we have to trust the client anyway, and the user could do
 103  * anything after logging in anyway.
 104  */
 105 static int all_opens_permitted = 0;
 106
 107
 108 /* -- X11 forwarding */
 109
 110 /* Maximum number of fake X11 displays to try. */
 111 #define MAX_DISPLAYS  1000
 112
 113 /* Saved X11 authentication protocol name. */
 114 static char *x11_saved_proto = NULL;
 115
 116 /* Saved X11 authentication data.  This is the real data. */
 117 static char *x11_saved_data = NULL;
 118 static u_int x11_saved_data_len = 0;
 119
 120 /*
 121  * Fake X11 authentication data.  This is what the server will be sending us;
 122  * we should replace any occurrences of this by the real data.
 123  */
 124 static char *x11_fake_data = NULL;
 125 static u_int x11_fake_data_len;
 126
 127
 128 /* -- agent forwarding */
 129
 130 #define NUM_SOCKS       10
 131
 132 /* Name and directory of socket for authentication agent forwarding. */
 133 static char *auth_sock_name = NULL;
 134 static char *auth_sock_dir = NULL;
 135
 136 /* AF_UNSPEC or AF_INET or AF_INET6 */
 137 static int IPv4or6 = AF_UNSPEC;
 138
 139 /* helper */
 140 static void port_open_helper(Channel *c, char *rtype);
 141
 142 /* -- channel core */
 143
 144 Channel *
 145 channel_lookup(int id)
 146 {
 147         Channel *c;
 148
 149         if (id < 0 || id > channels_alloc) {
 150                 log("channel_lookup: %d: bad id", id);
 151                 return NULL;
 152         }
 153         c = channels[id];
 154         if (c == NULL) {
 155                 log("channel_lookup: %d: bad id: channel free", id);
 156                 return NULL;
 157         }
 158         return c;
 159 }
 160
 161 /*
 162  * Register filedescriptors for a channel, used when allocating a channel or
 163  * when the channel consumer/producer is ready, e.g. shell exec'd
 164  */
 165
 166 static void
 167 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 168     int extusage, int nonblock)
 169 {
 170         /* Update the maximum file descriptor value. */
 171         channel_max_fd = MAX(channel_max_fd, rfd);
 172         channel_max_fd = MAX(channel_max_fd, wfd);
 173         channel_max_fd = MAX(channel_max_fd, efd);
 174
 175         /* XXX set close-on-exec -markus */
 176
 177         c->rfd = rfd;
 178         c->wfd = wfd;
 179         c->sock = (rfd == wfd) ? rfd : -1;
 180         c->efd = efd;
 181         c->extended_usage = extusage;
 182
 183         /* XXX ugly hack: nonblock is only set by the server */
 184         if (nonblock && isatty(c->rfd)) {
 185                 debug("channel %d: rfd %d isatty", c->self, c->rfd);
 186                 c->isatty = 1;
 187                 if (!isatty(c->wfd)) {
 188                         error("channel %d: wfd %d is not a tty?",
 189                             c->self, c->wfd);
 190                 }
 191         } else {
 192                 c->isatty = 0;
 193         }
 194
 195         /* enable nonblocking mode */
 196         if (nonblock) {
 197                 if (rfd != -1)
 198                         set_nonblock(rfd);
 199                 if (wfd != -1)
 200                         set_nonblock(wfd);
 201                 if (efd != -1)
 202                         set_nonblock(efd);
 203         }
 204 }
 205
 206 /*
 207  * Allocate a new channel object and set its type and socket. This will cause
 208  * remote_name to be freed.
 209  */
 210
 211 Channel *
 212 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 213     int window, int maxpack, int extusage, char *remote_name, int nonblock)
 214 {
 215         int i, found;
 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                 fatal_add_cleanup((void (*) (void *)) channel_free_all, NULL);
 225         }
 226         /* Try to find a free slot where to put the new channel. */
 227         for (found = -1, i = 0; i < channels_alloc; i++)
 228                 if (channels[i] == NULL) {
 229                         /* Found a free slot. */
 230                         found = i;
 231                         break;
 232                 }
 233         if (found == -1) {
 234                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 235                 found = channels_alloc;
 236                 channels_alloc += 10;
 237                 debug2("channel: expanding %d", channels_alloc);
 238                 channels = xrealloc(channels, channels_alloc * sizeof(Channel *));
 239                 for (i = found; i < channels_alloc; i++)
 240                         channels[i] = NULL;
 241         }
 242         /* Initialize and return new channel. */
 243         c = channels[found] = xmalloc(sizeof(Channel));
 244         memset(c, 0, sizeof(Channel));
 245         buffer_init(&c->input);
 246         buffer_init(&c->output);
 247         buffer_init(&c->extended);
 248         c->ostate = CHAN_OUTPUT_OPEN;
 249         c->istate = CHAN_INPUT_OPEN;
 250         c->flags = 0;
 251         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 252         c->self = found;
 253         c->type = type;
 254         c->ctype = ctype;
 255         c->local_window = window;
 256         c->local_window_max = window;
 257         c->local_consumed = 0;
 258         c->local_maxpacket = maxpack;
 259         c->remote_id = -1;
 260         c->remote_name = remote_name;
 261         c->remote_window = 0;
 262         c->remote_maxpacket = 0;
 263         c->force_drain = 0;
 264         c->single_connection = 0;
 265         c->detach_user = NULL;
 266         c->confirm = NULL;
 267         c->input_filter = NULL;
 268         debug("channel %d: new [%s]", found, remote_name);
 269         return c;
 270 }
 271
 272 static int
 273 channel_find_maxfd(void)
 274 {
 275         int i, max = 0;
 276         Channel *c;
 277
 278         for (i = 0; i < channels_alloc; i++) {
 279                 c = channels[i];
 280                 if (c != NULL) {
 281                         max = MAX(max, c->rfd);
 282                         max = MAX(max, c->wfd);
 283                         max = MAX(max, c->efd);
 284                 }
 285         }
 286         return max;
 287 }
 288
 289 int
 290 channel_close_fd(int *fdp)
 291 {
 292         int ret = 0, fd = *fdp;
 293
 294         if (fd != -1) {
 295                 ret = close(fd);
 296                 *fdp = -1;
 297                 if (fd == channel_max_fd)
 298                         channel_max_fd = channel_find_maxfd();
 299         }
 300         return ret;
 301 }
 302
 303 /* Close all channel fd/socket. */
 304
 305 static void
 306 channel_close_fds(Channel *c)
 307 {
 308         debug3("channel_close_fds: channel %d: r %d w %d e %d",
 309             c->self, c->rfd, c->wfd, c->efd);
 310
 311         channel_close_fd(&c->sock);
 312         channel_close_fd(&c->rfd);
 313         channel_close_fd(&c->wfd);
 314         channel_close_fd(&c->efd);
 315 }
 316
 317 /* Free the channel and close its fd/socket. */
 318
 319 void
 320 channel_free(Channel *c)
 321 {
 322         char *s;
 323         int i, n;
 324
 325         for (n = 0, i = 0; i < channels_alloc; i++)
 326                 if (channels[i])
 327                         n++;
 328         debug("channel_free: channel %d: %s, nchannels %d", c->self,
 329             c->remote_name ? c->remote_name : "???", n);
 330
 331         s = channel_open_message();
 332         debug3("channel_free: status: %s", s);
 333         xfree(s);
 334
 335         if (c->sock != -1)
 336                 shutdown(c->sock, SHUT_RDWR);
 337         channel_close_fds(c);
 338         buffer_free(&c->input);
 339         buffer_free(&c->output);
 340         buffer_free(&c->extended);
 341         if (c->remote_name) {
 342                 xfree(c->remote_name);
 343                 c->remote_name = NULL;
 344         }
 345         channels[c->self] = NULL;
 346         xfree(c);
 347 }
 348
 349 void
 350 channel_free_all(void)
 351 {
 352         int i;
 353
 354         for (i = 0; i < channels_alloc; i++)
 355                 if (channels[i] != NULL)
 356                         channel_free(channels[i]);
 357 }
 358
 359 /*
 360  * Closes the sockets/fds of all channels.  This is used to close extra file
 361  * descriptors after a fork.
 362  */
 363
 364 void
 365 channel_close_all(void)
 366 {
 367         int i;
 368
 369         for (i = 0; i < channels_alloc; i++)
 370                 if (channels[i] != NULL)
 371                         channel_close_fds(channels[i]);
 372 }
 373
 374 /*
 375  * Stop listening to channels.
 376  */
 377
 378 void
 379 channel_stop_listening(void)
 380 {
 381         int i;
 382         Channel *c;
 383
 384         for (i = 0; i < channels_alloc; i++) {
 385                 c = channels[i];
 386                 if (c != NULL) {
 387                         switch (c->type) {
 388                         case SSH_CHANNEL_AUTH_SOCKET:
 389                         case SSH_CHANNEL_PORT_LISTENER:
 390                         case SSH_CHANNEL_RPORT_LISTENER:
 391                         case SSH_CHANNEL_X11_LISTENER:
 392                                 channel_close_fd(&c->sock);
 393                                 channel_free(c);
 394                                 break;
 395                         }
 396                 }
 397         }
 398 }
 399
 400 /*
 401  * Returns true if no channel has too much buffered data, and false if one or
 402  * more channel is overfull.
 403  */
 404
 405 int
 406 channel_not_very_much_buffered_data(void)
 407 {
 408         u_int i;
 409         Channel *c;
 410
 411         for (i = 0; i < channels_alloc; i++) {
 412                 c = channels[i];
 413                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 414 #if 0
 415                         if (!compat20 &&
 416                             buffer_len(&c->input) > packet_get_maxsize()) {
 417                                 debug("channel %d: big input buffer %d",
 418                                     c->self, buffer_len(&c->input));
 419                                 return 0;
 420                         }
 421 #endif
 422                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 423                                 debug("channel %d: big output buffer %d > %d",
 424                                     c->self, buffer_len(&c->output),
 425                                     packet_get_maxsize());
 426                                 return 0;
 427                         }
 428                 }
 429         }
 430         return 1;
 431 }
 432
 433 /* Returns true if any channel is still open. */
 434
 435 int
 436 channel_still_open(void)
 437 {
 438         int i;
 439         Channel *c;
 440
 441         for (i = 0; i < channels_alloc; i++) {
 442                 c = channels[i];
 443                 if (c == NULL)
 444                         continue;
 445                 switch (c->type) {
 446                 case SSH_CHANNEL_X11_LISTENER:
 447                 case SSH_CHANNEL_PORT_LISTENER:
 448                 case SSH_CHANNEL_RPORT_LISTENER:
 449                 case SSH_CHANNEL_CLOSED:
 450                 case SSH_CHANNEL_AUTH_SOCKET:
 451                 case SSH_CHANNEL_DYNAMIC:
 452                 case SSH_CHANNEL_CONNECTING:
 453                 case SSH_CHANNEL_ZOMBIE:
 454                         continue;
 455                 case SSH_CHANNEL_LARVAL:
 456                         if (!compat20)
 457                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 458                         continue;
 459                 case SSH_CHANNEL_OPENING:
 460                 case SSH_CHANNEL_OPEN:
 461                 case SSH_CHANNEL_X11_OPEN:
 462                         return 1;
 463                 case SSH_CHANNEL_INPUT_DRAINING:
 464                 case SSH_CHANNEL_OUTPUT_DRAINING:
 465                         if (!compat13)
 466                                 fatal("cannot happen: OUT_DRAIN");
 467                         return 1;
 468                 default:
 469                         fatal("channel_still_open: bad channel type %d", c->type);
 470                         /* NOTREACHED */
 471                 }
 472         }
 473         return 0;
 474 }
 475
 476 /* Returns the id of an open channel suitable for keepaliving */
 477
 478 int
 479 channel_find_open(void)
 480 {
 481         int i;
 482         Channel *c;
 483
 484         for (i = 0; i < channels_alloc; i++) {
 485                 c = channels[i];
 486                 if (c == NULL)
 487                         continue;
 488                 switch (c->type) {
 489                 case SSH_CHANNEL_CLOSED:
 490                 case SSH_CHANNEL_DYNAMIC:
 491                 case SSH_CHANNEL_X11_LISTENER:
 492                 case SSH_CHANNEL_PORT_LISTENER:
 493                 case SSH_CHANNEL_RPORT_LISTENER:
 494                 case SSH_CHANNEL_OPENING:
 495                 case SSH_CHANNEL_CONNECTING:
 496                 case SSH_CHANNEL_ZOMBIE:
 497                         continue;
 498                 case SSH_CHANNEL_LARVAL:
 499                 case SSH_CHANNEL_AUTH_SOCKET:
 500                 case SSH_CHANNEL_OPEN:
 501                 case SSH_CHANNEL_X11_OPEN:
 502                         return i;
 503                 case SSH_CHANNEL_INPUT_DRAINING:
 504                 case SSH_CHANNEL_OUTPUT_DRAINING:
 505                         if (!compat13)
 506                                 fatal("cannot happen: OUT_DRAIN");
 507                         return i;
 508                 default:
 509                         fatal("channel_find_open: bad channel type %d", c->type);
 510                         /* NOTREACHED */
 511                 }
 512         }
 513         return -1;
 514 }
 515
 516
 517 /*
 518  * Returns a message describing the currently open forwarded connections,
 519  * suitable for sending to the client.  The message contains crlf pairs for
 520  * newlines.
 521  */
 522
 523 char *
 524 channel_open_message(void)
 525 {
 526         Buffer buffer;
 527         Channel *c;
 528         char buf[1024], *cp;
 529         int i;
 530
 531         buffer_init(&buffer);
 532         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 533         buffer_append(&buffer, buf, strlen(buf));
 534         for (i = 0; i < channels_alloc; i++) {
 535                 c = channels[i];
 536                 if (c == NULL)
 537                         continue;
 538                 switch (c->type) {
 539                 case SSH_CHANNEL_X11_LISTENER:
 540                 case SSH_CHANNEL_PORT_LISTENER:
 541                 case SSH_CHANNEL_RPORT_LISTENER:
 542                 case SSH_CHANNEL_CLOSED:
 543                 case SSH_CHANNEL_AUTH_SOCKET:
 544                 case SSH_CHANNEL_ZOMBIE:
 545                         continue;
 546                 case SSH_CHANNEL_LARVAL:
 547                 case SSH_CHANNEL_OPENING:
 548                 case SSH_CHANNEL_CONNECTING:
 549                 case SSH_CHANNEL_DYNAMIC:
 550                 case SSH_CHANNEL_OPEN:
 551                 case SSH_CHANNEL_X11_OPEN:
 552                 case SSH_CHANNEL_INPUT_DRAINING:
 553                 case SSH_CHANNEL_OUTPUT_DRAINING:
 554                         snprintf(buf, sizeof buf, "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d)\r\n",
 555                             c->self, c->remote_name,
 556                             c->type, c->remote_id,
 557                             c->istate, buffer_len(&c->input),
 558                             c->ostate, buffer_len(&c->output),
 559                             c->rfd, c->wfd);
 560                         buffer_append(&buffer, buf, strlen(buf));
 561                         continue;
 562                 default:
 563                         fatal("channel_open_message: bad channel type %d", c->type);
 564                         /* NOTREACHED */
 565                 }
 566         }
 567         buffer_append(&buffer, "\0", 1);
 568         cp = xstrdup(buffer_ptr(&buffer));
 569         buffer_free(&buffer);
 570         return cp;
 571 }
 572
 573 void
 574 channel_send_open(int id)
 575 {
 576         Channel *c = channel_lookup(id);
 577         if (c == NULL) {
 578                 log("channel_send_open: %d: bad id", id);
 579                 return;
 580         }
 581         debug("send channel open %d", id);
 582         packet_start(SSH2_MSG_CHANNEL_OPEN);
 583         packet_put_cstring(c->ctype);
 584         packet_put_int(c->self);
 585         packet_put_int(c->local_window);
 586         packet_put_int(c->local_maxpacket);
 587         packet_send();
 588 }
 589
 590 void
 591 channel_request_start(int local_id, char *service, int wantconfirm)
 592 {
 593         Channel *c = channel_lookup(local_id);
 594         if (c == NULL) {
 595                 log("channel_request_start: %d: unknown channel id", local_id);
 596                 return;
 597         }
 598         debug("channel request %d: %s", local_id, service) ;
 599         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 600         packet_put_int(c->remote_id);
 601         packet_put_cstring(service);
 602         packet_put_char(wantconfirm);
 603 }
 604 void
 605 channel_register_confirm(int id, channel_callback_fn *fn)
 606 {
 607         Channel *c = channel_lookup(id);
 608         if (c == NULL) {
 609                 log("channel_register_comfirm: %d: bad id", id);
 610                 return;
 611         }
 612         c->confirm = fn;
 613 }
 614 void
 615 channel_register_cleanup(int id, channel_callback_fn *fn)
 616 {
 617         Channel *c = channel_lookup(id);
 618         if (c == NULL) {
 619                 log("channel_register_cleanup: %d: bad id", id);
 620                 return;
 621         }
 622         c->detach_user = fn;
 623 }
 624 void
 625 channel_cancel_cleanup(int id)
 626 {
 627         Channel *c = channel_lookup(id);
 628         if (c == NULL) {
 629                 log("channel_cancel_cleanup: %d: bad id", id);
 630                 return;
 631         }
 632         c->detach_user = NULL;
 633 }
 634 void
 635 channel_register_filter(int id, channel_filter_fn *fn)
 636 {
 637         Channel *c = channel_lookup(id);
 638         if (c == NULL) {
 639                 log("channel_register_filter: %d: bad id", id);
 640                 return;
 641         }
 642         c->input_filter = fn;
 643 }
 644
 645 void
 646 channel_set_fds(int id, int rfd, int wfd, int efd,
 647     int extusage, int nonblock)
 648 {
 649         Channel *c = channel_lookup(id);
 650         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 651                 fatal("channel_activate for non-larval channel %d.", id);
 652         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 653         c->type = SSH_CHANNEL_OPEN;
 654         /* XXX window size? */
 655         c->local_window = c->local_window_max = c->local_maxpacket * 2;
 656         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 657         packet_put_int(c->remote_id);
 658         packet_put_int(c->local_window);
 659         packet_send();
 660 }
 661
 662 /*
 663  * 'channel_pre*' are called just before select() to add any bits relevant to
 664  * channels in the select bitmasks.
 665  */
 666 /*
 667  * 'channel_post*': perform any appropriate operations for channels which
 668  * have events pending.
 669  */
 670 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 671 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 672 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 673
 674 static void
 675 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 676 {
 677         FD_SET(c->sock, readset);
 678 }
 679
 680 static void
 681 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 682 {
 683         debug3("channel %d: waiting for connection", c->self);
 684         FD_SET(c->sock, writeset);
 685 }
 686
 687 static void
 688 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 689 {
 690         if (buffer_len(&c->input) < packet_get_maxsize())
 691                 FD_SET(c->sock, readset);
 692         if (buffer_len(&c->output) > 0)
 693                 FD_SET(c->sock, writeset);
 694 }
 695
 696 static void
 697 channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
 698 {
 699         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 700
 701         if (c->istate == CHAN_INPUT_OPEN &&
 702             limit > 0 &&
 703             buffer_len(&c->input) < limit)
 704                 FD_SET(c->rfd, readset);
 705         if (c->ostate == CHAN_OUTPUT_OPEN ||
 706             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 707                 if (buffer_len(&c->output) > 0) {
 708                         FD_SET(c->wfd, writeset);
 709                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 710                         chan_obuf_empty(c);
 711                 }
 712         }
 713         /** XXX check close conditions, too */
 714         if (compat20 && c->efd != -1) {
 715                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 716                     buffer_len(&c->extended) > 0)
 717                         FD_SET(c->efd, writeset);
 718                 else if (c->extended_usage == CHAN_EXTENDED_READ &&
 719                     buffer_len(&c->extended) < c->remote_window)
 720                         FD_SET(c->efd, readset);
 721         }
 722 }
 723
 724 static void
 725 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 726 {
 727         if (buffer_len(&c->input) == 0) {
 728                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 729                 packet_put_int(c->remote_id);
 730                 packet_send();
 731                 c->type = SSH_CHANNEL_CLOSED;
 732                 debug("channel %d: closing after input drain.", c->self);
 733         }
 734 }
 735
 736 static void
 737 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 738 {
 739         if (buffer_len(&c->output) == 0)
 740                 chan_mark_dead(c);
 741         else
 742                 FD_SET(c->sock, writeset);
 743 }
 744
 745 /*
 746  * This is a special state for X11 authentication spoofing.  An opened X11
 747  * connection (when authentication spoofing is being done) remains in this
 748  * state until the first packet has been completely read.  The authentication
 749  * data in that packet is then substituted by the real data if it matches the
 750  * fake data, and the channel is put into normal mode.
 751  * XXX All this happens at the client side.
 752  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 753  */
 754 static int
 755 x11_open_helper(Buffer *b)
 756 {
 757         u_char *ucp;
 758         u_int proto_len, data_len;
 759
 760         /* Check if the fixed size part of the packet is in buffer. */
 761         if (buffer_len(b) < 12)
 762                 return 0;
 763
 764         /* Parse the lengths of variable-length fields. */
 765         ucp = buffer_ptr(b);
 766         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 767                 proto_len = 256 * ucp[6] + ucp[7];
 768                 data_len = 256 * ucp[8] + ucp[9];
 769         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 770                 proto_len = ucp[6] + 256 * ucp[7];
 771                 data_len = ucp[8] + 256 * ucp[9];
 772         } else {
 773                 debug("Initial X11 packet contains bad byte order byte: 0x%x",
 774                     ucp[0]);
 775                 return -1;
 776         }
 777
 778         /* Check if the whole packet is in buffer. */
 779         if (buffer_len(b) <
 780             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 781                 return 0;
 782
 783         /* Check if authentication protocol matches. */
 784         if (proto_len != strlen(x11_saved_proto) ||
 785             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 786                 debug("X11 connection uses different authentication protocol.");
 787                 return -1;
 788         }
 789         /* Check if authentication data matches our fake data. */
 790         if (data_len != x11_fake_data_len ||
 791             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 792                 x11_fake_data, x11_fake_data_len) != 0) {
 793                 debug("X11 auth data does not match fake data.");
 794                 return -1;
 795         }
 796         /* Check fake data length */
 797         if (x11_fake_data_len != x11_saved_data_len) {
 798                 error("X11 fake_data_len %d != saved_data_len %d",
 799                     x11_fake_data_len, x11_saved_data_len);
 800                 return -1;
 801         }
 802         /*
 803          * Received authentication protocol and data match
 804          * our fake data. Substitute the fake data with real
 805          * data.
 806          */
 807         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 808             x11_saved_data, x11_saved_data_len);
 809         return 1;
 810 }
 811
 812 static void
 813 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 814 {
 815         int ret = x11_open_helper(&c->output);
 816         if (ret == 1) {
 817                 /* Start normal processing for the channel. */
 818                 c->type = SSH_CHANNEL_OPEN;
 819                 channel_pre_open_13(c, readset, writeset);
 820         } else if (ret == -1) {
 821                 /*
 822                  * We have received an X11 connection that has bad
 823                  * authentication information.
 824                  */
 825                 log("X11 connection rejected because of wrong authentication.");
 826                 buffer_clear(&c->input);
 827                 buffer_clear(&c->output);
 828                 channel_close_fd(&c->sock);
 829                 c->sock = -1;
 830                 c->type = SSH_CHANNEL_CLOSED;
 831                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 832                 packet_put_int(c->remote_id);
 833                 packet_send();
 834         }
 835 }
 836
 837 static void
 838 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
 839 {
 840         int ret = x11_open_helper(&c->output);
 841
 842         /* c->force_drain = 1; */
 843
 844         if (ret == 1) {
 845                 c->type = SSH_CHANNEL_OPEN;
 846                 channel_pre_open(c, readset, writeset);
 847         } else if (ret == -1) {
 848                 log("X11 connection rejected because of wrong authentication.");
 849                 debug("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 850                 chan_read_failed(c);
 851                 buffer_clear(&c->input);
 852                 chan_ibuf_empty(c);
 853                 buffer_clear(&c->output);
 854                 /* for proto v1, the peer will send an IEOF */
 855                 if (compat20)
 856                         chan_write_failed(c);
 857                 else
 858                         c->type = SSH_CHANNEL_OPEN;
 859                 debug("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 860         }
 861 }
 862
 863 /* try to decode a socks4 header */
 864 static int
 865 channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
 866 {
 867         u_char *p, *host;
 868         int len, have, i, found;
 869         char username[256];
 870         struct {
 871                 u_int8_t version;
 872                 u_int8_t command;
 873                 u_int16_t dest_port;
 874                 struct in_addr dest_addr;
 875         } s4_req, s4_rsp;
 876
 877         debug2("channel %d: decode socks4", c->self);
 878
 879         have = buffer_len(&c->input);
 880         len = sizeof(s4_req);
 881         if (have < len)
 882                 return 0;
 883         p = buffer_ptr(&c->input);
 884         for (found = 0, i = len; i < have; i++) {
 885                 if (p[i] == '\0') {
 886                         found = 1;
 887                         break;
 888                 }
 889                 if (i > 1024) {
 890                         /* the peer is probably sending garbage */
 891                         debug("channel %d: decode socks4: too long",
 892                             c->self);
 893                         return -1;
 894                 }
 895         }
 896         if (!found)
 897                 return 0;
 898         buffer_get(&c->input, (char *)&s4_req.version, 1);
 899         buffer_get(&c->input, (char *)&s4_req.command, 1);
 900         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 901         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 902         have = buffer_len(&c->input);
 903         p = buffer_ptr(&c->input);
 904         len = strlen(p);
 905         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 906         if (len > have)
 907                 fatal("channel %d: decode socks4: len %d > have %d",
 908                     c->self, len, have);
 909         strlcpy(username, p, sizeof(username));
 910         buffer_consume(&c->input, len);
 911         buffer_consume(&c->input, 1);           /* trailing '\0' */
 912
 913         host = inet_ntoa(s4_req.dest_addr);
 914         strlcpy(c->path, host, sizeof(c->path));
 915         c->host_port = ntohs(s4_req.dest_port);
 916
 917         debug("channel %d: dynamic request: socks4 host %s port %u command %u",
 918             c->self, host, c->host_port, s4_req.command);
 919
 920         if (s4_req.command != 1) {
 921                 debug("channel %d: cannot handle: socks4 cn %d",
 922                     c->self, s4_req.command);
 923                 return -1;
 924         }
 925         s4_rsp.version = 0;                     /* vn: 0 for reply */
 926         s4_rsp.command = 90;                    /* cd: req granted */
 927         s4_rsp.dest_port = 0;                   /* ignored */
 928         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 929         buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
 930         return 1;
 931 }
 932
 933 /* dynamic port forwarding */
 934 static void
 935 channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
 936 {
 937         u_char *p;
 938         int have, ret;
 939
 940         have = buffer_len(&c->input);
 941         c->delayed = 0;
 942         debug2("channel %d: pre_dynamic: have %d", c->self, have);
 943         /* buffer_dump(&c->input); */
 944         /* check if the fixed size part of the packet is in buffer. */
 945         if (have < 4) {
 946                 /* need more */
 947                 FD_SET(c->sock, readset);
 948                 return;
 949         }
 950         /* try to guess the protocol */
 951         p = buffer_ptr(&c->input);
 952         switch (p[0]) {
 953         case 0x04:
 954                 ret = channel_decode_socks4(c, readset, writeset);
 955                 break;
 956         default:
 957                 ret = -1;
 958                 break;
 959         }
 960         if (ret < 0) {
 961                 chan_mark_dead(c);
 962         } else if (ret == 0) {
 963                 debug2("channel %d: pre_dynamic: need more", c->self);
 964                 /* need more */
 965                 FD_SET(c->sock, readset);
 966         } else {
 967                 /* switch to the next state */
 968                 c->type = SSH_CHANNEL_OPENING;
 969                 port_open_helper(c, "direct-tcpip");
 970         }
 971 }
 972
 973 /* This is our fake X11 server socket. */
 974 static void
 975 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
 976 {
 977         Channel *nc;
 978         struct sockaddr addr;
 979         int newsock;
 980         socklen_t addrlen;
 981         char buf[16384], *remote_ipaddr;
 982         int remote_port;
 983
 984         if (FD_ISSET(c->sock, readset)) {
 985                 debug("X11 connection requested.");
 986                 addrlen = sizeof(addr);
 987                 newsock = accept(c->sock, &addr, &addrlen);
 988                 if (c->single_connection) {
 989                         debug("single_connection: closing X11 listener.");
 990                         channel_close_fd(&c->sock);
 991                         chan_mark_dead(c);
 992                 }
 993                 if (newsock < 0) {
 994                         error("accept: %.100s", strerror(errno));
 995                         return;
 996                 }
 997                 set_nodelay(newsock);
 998                 remote_ipaddr = get_peer_ipaddr(newsock);
 999                 remote_port = get_peer_port(newsock);
1000                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1001                     remote_ipaddr, remote_port);
1002
1003                 nc = channel_new("accepted x11 socket",
1004                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1005                     c->local_window_max, c->local_maxpacket,
1006                     0, xstrdup(buf), 1);
1007                 if (compat20) {
1008                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1009                         packet_put_cstring("x11");
1010                         packet_put_int(nc->self);
1011                         packet_put_int(nc->local_window_max);
1012                         packet_put_int(nc->local_maxpacket);
1013                         /* originator ipaddr and port */
1014                         packet_put_cstring(remote_ipaddr);
1015                         if (datafellows & SSH_BUG_X11FWD) {
1016                                 debug("ssh2 x11 bug compat mode");
1017                         } else {
1018                                 packet_put_int(remote_port);
1019                         }
1020                         packet_send();
1021                 } else {
1022                         packet_start(SSH_SMSG_X11_OPEN);
1023                         packet_put_int(nc->self);
1024                         if (packet_get_protocol_flags() &
1025                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1026                                 packet_put_cstring(buf);
1027                         packet_send();
1028                 }
1029                 xfree(remote_ipaddr);
1030         }
1031 }
1032
1033 static void
1034 port_open_helper(Channel *c, char *rtype)
1035 {
1036         int direct;
1037         char buf[1024];
1038         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1039         u_short remote_port = get_peer_port(c->sock);
1040
1041         direct = (strcmp(rtype, "direct-tcpip") == 0);
1042
1043         snprintf(buf, sizeof buf,
1044             "%s: listening port %d for %.100s port %d, "
1045             "connect from %.200s port %d",
1046             rtype, c->listening_port, c->path, c->host_port,
1047             remote_ipaddr, remote_port);
1048
1049         xfree(c->remote_name);
1050         c->remote_name = xstrdup(buf);
1051
1052         if (compat20) {
1053                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1054                 packet_put_cstring(rtype);
1055                 packet_put_int(c->self);
1056                 packet_put_int(c->local_window_max);
1057                 packet_put_int(c->local_maxpacket);
1058                 if (direct) {
1059                         /* target host, port */
1060                         packet_put_cstring(c->path);
1061                         packet_put_int(c->host_port);
1062                 } else {
1063                         /* listen address, port */
1064                         packet_put_cstring(c->path);
1065                         packet_put_int(c->listening_port);
1066                 }
1067                 /* originator host and port */
1068                 packet_put_cstring(remote_ipaddr);
1069                 packet_put_int(remote_port);
1070                 packet_send();
1071         } else {
1072                 packet_start(SSH_MSG_PORT_OPEN);
1073                 packet_put_int(c->self);
1074                 packet_put_cstring(c->path);
1075                 packet_put_int(c->host_port);
1076                 if (packet_get_protocol_flags() &
1077                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1078                         packet_put_cstring(c->remote_name);
1079                 packet_send();
1080         }
1081         xfree(remote_ipaddr);
1082 }
1083
1084 /*
1085  * This socket is listening for connections to a forwarded TCP/IP port.
1086  */
1087 static void
1088 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
1089 {
1090         Channel *nc;
1091         struct sockaddr addr;
1092         int newsock, nextstate;
1093         socklen_t addrlen;
1094         char *rtype;
1095
1096         if (FD_ISSET(c->sock, readset)) {
1097                 debug("Connection to port %d forwarding "
1098                     "to %.100s port %d requested.",
1099                     c->listening_port, c->path, c->host_port);
1100
1101                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1102                         nextstate = SSH_CHANNEL_OPENING;
1103                         rtype = "forwarded-tcpip";
1104                 } else {
1105                         if (c->host_port == 0) {
1106                                 nextstate = SSH_CHANNEL_DYNAMIC;
1107                                 rtype = "dynamic-tcpip";
1108                         } else {
1109                                 nextstate = SSH_CHANNEL_OPENING;
1110                                 rtype = "direct-tcpip";
1111                         }
1112                 }
1113
1114                 addrlen = sizeof(addr);
1115                 newsock = accept(c->sock, &addr, &addrlen);
1116                 if (newsock < 0) {
1117                         error("accept: %.100s", strerror(errno));
1118                         return;
1119                 }
1120                 nc = channel_new(rtype,
1121                     nextstate, newsock, newsock, -1,
1122                     c->local_window_max, c->local_maxpacket,
1123                     0, xstrdup(rtype), 1);
1124                 nc->listening_port = c->listening_port;
1125                 nc->host_port = c->host_port;
1126                 strlcpy(nc->path, c->path, sizeof(nc->path));
1127
1128                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1129                         /*
1130                          * do not call the channel_post handler until
1131                          * this flag has been reset by a pre-handler.
1132                          * otherwise the FD_ISSET calls might overflow
1133                          */
1134                         nc->delayed = 1;
1135                 } else {
1136                         port_open_helper(nc, rtype);
1137                 }
1138         }
1139 }
1140
1141 /*
1142  * This is the authentication agent socket listening for connections from
1143  * clients.
1144  */
1145 static void
1146 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
1147 {
1148         Channel *nc;
1149         char *name;
1150         int newsock;
1151         struct sockaddr addr;
1152         socklen_t addrlen;
1153
1154         if (FD_ISSET(c->sock, readset)) {
1155                 addrlen = sizeof(addr);
1156                 newsock = accept(c->sock, &addr, &addrlen);
1157                 if (newsock < 0) {
1158                         error("accept from auth socket: %.100s", strerror(errno));
1159                         return;
1160                 }
1161                 name = xstrdup("accepted auth socket");
1162                 nc = channel_new("accepted auth socket",
1163                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1164                     c->local_window_max, c->local_maxpacket,
1165                     0, name, 1);
1166                 if (compat20) {
1167                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1168                         packet_put_cstring("auth-agent@openssh.com");
1169                         packet_put_int(nc->self);
1170                         packet_put_int(c->local_window_max);
1171                         packet_put_int(c->local_maxpacket);
1172                 } else {
1173                         packet_start(SSH_SMSG_AGENT_OPEN);
1174                         packet_put_int(nc->self);
1175                 }
1176                 packet_send();
1177         }
1178 }
1179
1180 static void
1181 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
1182 {
1183         int err = 0;
1184         socklen_t sz = sizeof(err);
1185
1186         if (FD_ISSET(c->sock, writeset)) {
1187                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, (char *)&err,
1188                     &sz) < 0) {
1189                         err = errno;
1190                         error("getsockopt SO_ERROR failed");
1191                 }
1192                 if (err == 0) {
1193                         debug("channel %d: connected", c->self);
1194                         c->type = SSH_CHANNEL_OPEN;
1195                         if (compat20) {
1196                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1197                                 packet_put_int(c->remote_id);
1198                                 packet_put_int(c->self);
1199                                 packet_put_int(c->local_window);
1200                                 packet_put_int(c->local_maxpacket);
1201                         } else {
1202                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1203                                 packet_put_int(c->remote_id);
1204                                 packet_put_int(c->self);
1205                         }
1206                 } else {
1207                         debug("channel %d: not connected: %s",
1208                             c->self, strerror(err));
1209                         if (compat20) {
1210                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1211                                 packet_put_int(c->remote_id);
1212                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1213                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1214                                         packet_put_cstring(strerror(err));
1215                                         packet_put_cstring("");
1216                                 }
1217                         } else {
1218                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1219                                 packet_put_int(c->remote_id);
1220                         }
1221                         chan_mark_dead(c);
1222                 }
1223                 packet_send();
1224         }
1225 }
1226
1227 static int
1228 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
1229 {
1230         char buf[16*1024];
1231         int len;
1232
1233         if (c->rfd != -1 &&
1234             FD_ISSET(c->rfd, readset)) {
1235                 len = read(c->rfd, buf, sizeof(buf));
1236                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1237                         return 1;
1238                 if (len <= 0) {
1239                         debug("channel %d: read<=0 rfd %d len %d",
1240                             c->self, c->rfd, len);
1241                         if (c->type != SSH_CHANNEL_OPEN) {
1242                                 debug("channel %d: not open", c->self);
1243                                 chan_mark_dead(c);
1244                                 return -1;
1245                         } else if (compat13) {
1246                                 buffer_clear(&c->output);
1247                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1248                                 debug("channel %d: input draining.", c->self);
1249                         } else {
1250                                 chan_read_failed(c);
1251                         }
1252                         return -1;
1253                 }
1254                 if (c->input_filter != NULL) {
1255                         if (c->input_filter(c, buf, len) == -1) {
1256                                 debug("channel %d: filter stops", c->self);
1257                                 chan_read_failed(c);
1258                         }
1259                 } else {
1260                         buffer_append(&c->input, buf, len);
1261                 }
1262         }
1263         return 1;
1264 }
1265 static int
1266 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
1267 {
1268         struct termios tio;
1269         u_char *data;
1270         u_int dlen;
1271         int len;
1272
1273         /* Send buffered output data to the socket. */
1274         if (c->wfd != -1 &&
1275             FD_ISSET(c->wfd, writeset) &&
1276             buffer_len(&c->output) > 0) {
1277                 data = buffer_ptr(&c->output);
1278                 dlen = buffer_len(&c->output);
1279                 len = write(c->wfd, data, dlen);
1280                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1281                         return 1;
1282                 if (len <= 0) {
1283                         if (c->type != SSH_CHANNEL_OPEN) {
1284                                 debug("channel %d: not open", c->self);
1285                                 chan_mark_dead(c);
1286                                 return -1;
1287                         } else if (compat13) {
1288                                 buffer_clear(&c->output);
1289                                 debug("channel %d: input draining.", c->self);
1290                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1291                         } else {
1292                                 chan_write_failed(c);
1293                         }
1294                         return -1;
1295                 }
1296                 if (compat20 && c->isatty && dlen >= 1 && data[0] != '\r') {
1297                         if (tcgetattr(c->wfd, &tio) == 0 &&
1298                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1299                                 /*
1300                                  * Simulate echo to reduce the impact of
1301                                  * traffic analysis. We need to match the
1302                                  * size of a SSH2_MSG_CHANNEL_DATA message
1303                                  * (4 byte channel id + data)
1304                                  */
1305                                 packet_send_ignore(4 + len);
1306                                 packet_send();
1307                         }
1308                 }
1309                 buffer_consume(&c->output, len);
1310                 if (compat20 && len > 0) {
1311                         c->local_consumed += len;
1312                 }
1313         }
1314         return 1;
1315 }
1316 static int
1317 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
1318 {
1319         char buf[16*1024];
1320         int len;
1321
1322 /** XXX handle drain efd, too */
1323         if (c->efd != -1) {
1324                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1325                     FD_ISSET(c->efd, writeset) &&
1326                     buffer_len(&c->extended) > 0) {
1327                         len = write(c->efd, buffer_ptr(&c->extended),
1328                             buffer_len(&c->extended));
1329                         debug2("channel %d: written %d to efd %d",
1330                             c->self, len, c->efd);
1331                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1332                                 return 1;
1333                         if (len <= 0) {
1334                                 debug2("channel %d: closing write-efd %d",
1335                                     c->self, c->efd);
1336                                 channel_close_fd(&c->efd);
1337                         } else {
1338                                 buffer_consume(&c->extended, len);
1339                                 c->local_consumed += len;
1340                         }
1341                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1342                     FD_ISSET(c->efd, readset)) {
1343                         len = read(c->efd, buf, sizeof(buf));
1344                         debug2("channel %d: read %d from efd %d",
1345                             c->self, len, c->efd);
1346                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1347                                 return 1;
1348                         if (len <= 0) {
1349                                 debug2("channel %d: closing read-efd %d",
1350                                     c->self, c->efd);
1351                                 channel_close_fd(&c->efd);
1352                         } else {
1353                                 buffer_append(&c->extended, buf, len);
1354                         }
1355                 }
1356         }
1357         return 1;
1358 }
1359 static int
1360 channel_check_window(Channel *c)
1361 {
1362         if (c->type == SSH_CHANNEL_OPEN &&
1363             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1364             c->local_window < c->local_window_max/2 &&
1365             c->local_consumed > 0) {
1366                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1367                 packet_put_int(c->remote_id);
1368                 packet_put_int(c->local_consumed);
1369                 packet_send();
1370                 debug2("channel %d: window %d sent adjust %d",
1371                     c->self, c->local_window,
1372                     c->local_consumed);
1373                 c->local_window += c->local_consumed;
1374                 c->local_consumed = 0;
1375         }
1376         return 1;
1377 }
1378
1379 static void
1380 channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
1381 {
1382         if (c->delayed)
1383                 return;
1384         channel_handle_rfd(c, readset, writeset);
1385         channel_handle_wfd(c, readset, writeset);
1386         if (!compat20)
1387                 return;
1388         channel_handle_efd(c, readset, writeset);
1389         channel_check_window(c);
1390 }
1391
1392 static void
1393 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
1394 {
1395         int len;
1396         /* Send buffered output data to the socket. */
1397         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1398                 len = write(c->sock, buffer_ptr(&c->output),
1399                             buffer_len(&c->output));
1400                 if (len <= 0)
1401                         buffer_clear(&c->output);
1402                 else
1403                         buffer_consume(&c->output, len);
1404         }
1405 }
1406
1407 static void
1408 channel_handler_init_20(void)
1409 {
1410         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1411         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1412         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1413         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1414         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1415         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1416         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1417         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1418
1419         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1420         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1421         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1422         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1423         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1424         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1425         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1426 }
1427
1428 static void
1429 channel_handler_init_13(void)
1430 {
1431         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1432         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1433         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1434         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1435         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1436         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1437         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1438         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1439         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1440
1441         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1442         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1443         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1444         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1445         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1446         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1447         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1448 }
1449
1450 static void
1451 channel_handler_init_15(void)
1452 {
1453         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1454         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1455         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1456         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1457         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1458         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1459         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1460
1461         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1462         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1463         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1464         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1465         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1466         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1467 }
1468
1469 static void
1470 channel_handler_init(void)
1471 {
1472         int i;
1473         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1474                 channel_pre[i] = NULL;
1475                 channel_post[i] = NULL;
1476         }
1477         if (compat20)
1478                 channel_handler_init_20();
1479         else if (compat13)
1480                 channel_handler_init_13();
1481         else
1482                 channel_handler_init_15();
1483 }
1484
1485 /* gc dead channels */
1486 static void
1487 channel_garbage_collect(Channel *c)
1488 {
1489         if (c == NULL)
1490                 return;
1491         if (c->detach_user != NULL) {
1492                 if (!chan_is_dead(c, 0))
1493                         return;
1494                 debug("channel %d: gc: notify user", c->self);
1495                 c->detach_user(c->self, NULL);
1496                 /* if we still have a callback */
1497                 if (c->detach_user != NULL)
1498                         return;
1499                 debug("channel %d: gc: user detached", c->self);
1500         }
1501         if (!chan_is_dead(c, 1))
1502                 return;
1503         debug("channel %d: garbage collecting", c->self);
1504         channel_free(c);
1505 }
1506
1507 static void
1508 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
1509 {
1510         static int did_init = 0;
1511         int i;
1512         Channel *c;
1513
1514         if (!did_init) {
1515                 channel_handler_init();
1516                 did_init = 1;
1517         }
1518         for (i = 0; i < channels_alloc; i++) {
1519                 c = channels[i];
1520                 if (c == NULL)
1521                         continue;
1522                 if (ftab[c->type] != NULL)
1523                         (*ftab[c->type])(c, readset, writeset);
1524                 channel_garbage_collect(c);
1525         }
1526 }
1527
1528 /*
1529  * Allocate/update select bitmasks and add any bits relevant to channels in
1530  * select bitmasks.
1531  */
1532 void
1533 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1534     int *nallocp, int rekeying)
1535 {
1536         int n;
1537         u_int sz;
1538
1539         n = MAX(*maxfdp, channel_max_fd);
1540
1541         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
1542         /* perhaps check sz < nalloc/2 and shrink? */
1543         if (*readsetp == NULL || sz > *nallocp) {
1544                 *readsetp = xrealloc(*readsetp, sz);
1545                 *writesetp = xrealloc(*writesetp, sz);
1546                 *nallocp = sz;
1547         }
1548         *maxfdp = n;
1549         memset(*readsetp, 0, sz);
1550         memset(*writesetp, 0, sz);
1551
1552         if (!rekeying)
1553                 channel_handler(channel_pre, *readsetp, *writesetp);
1554 }
1555
1556 /*
1557  * After select, perform any appropriate operations for channels which have
1558  * events pending.
1559  */
1560 void
1561 channel_after_select(fd_set * readset, fd_set * writeset)
1562 {
1563         channel_handler(channel_post, readset, writeset);
1564 }
1565
1566
1567 /* If there is data to send to the connection, enqueue some of it now. */
1568
1569 void
1570 channel_output_poll(void)
1571 {
1572         int len, i;
1573         Channel *c;
1574
1575         for (i = 0; i < channels_alloc; i++) {
1576                 c = channels[i];
1577                 if (c == NULL)
1578                         continue;
1579
1580                 /*
1581                  * We are only interested in channels that can have buffered
1582                  * incoming data.
1583                  */
1584                 if (compat13) {
1585                         if (c->type != SSH_CHANNEL_OPEN &&
1586                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1587                                 continue;
1588                 } else {
1589                         if (c->type != SSH_CHANNEL_OPEN)
1590                                 continue;
1591                 }
1592                 if (compat20 &&
1593                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1594                         /* XXX is this true? */
1595                         debug3("channel %d: will not send data after close", c->self);
1596                         continue;
1597                 }
1598
1599                 /* Get the amount of buffered data for this channel. */
1600                 if ((c->istate == CHAN_INPUT_OPEN ||
1601                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1602                     (len = buffer_len(&c->input)) > 0) {
1603                         /*
1604                          * Send some data for the other side over the secure
1605                          * connection.
1606                          */
1607                         if (compat20) {
1608                                 if (len > c->remote_window)
1609                                         len = c->remote_window;
1610                                 if (len > c->remote_maxpacket)
1611                                         len = c->remote_maxpacket;
1612                         } else {
1613                                 if (packet_is_interactive()) {
1614                                         if (len > 1024)
1615                                                 len = 512;
1616                                 } else {
1617                                         /* Keep the packets at reasonable size. */
1618                                         if (len > packet_get_maxsize()/2)
1619                                                 len = packet_get_maxsize()/2;
1620                                 }
1621                         }
1622                         if (len > 0) {
1623                                 packet_start(compat20 ?
1624                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1625                                 packet_put_int(c->remote_id);
1626                                 packet_put_string(buffer_ptr(&c->input), len);
1627                                 packet_send();
1628                                 buffer_consume(&c->input, len);
1629                                 c->remote_window -= len;
1630                         }
1631                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1632                         if (compat13)
1633                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1634                         /*
1635                          * input-buffer is empty and read-socket shutdown:
1636                          * tell peer, that we will not send more data: send IEOF
1637                          */
1638                         chan_ibuf_empty(c);
1639                 }
1640                 /* Send extended data, i.e. stderr */
1641                 if (compat20 &&
1642                     c->remote_window > 0 &&
1643                     (len = buffer_len(&c->extended)) > 0 &&
1644                     c->extended_usage == CHAN_EXTENDED_READ) {
1645                         debug2("channel %d: rwin %d elen %d euse %d",
1646                             c->self, c->remote_window, buffer_len(&c->extended),
1647                             c->extended_usage);
1648                         if (len > c->remote_window)
1649                                 len = c->remote_window;
1650                         if (len > c->remote_maxpacket)
1651                                 len = c->remote_maxpacket;
1652                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1653                         packet_put_int(c->remote_id);
1654                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1655                         packet_put_string(buffer_ptr(&c->extended), len);
1656                         packet_send();
1657                         buffer_consume(&c->extended, len);
1658                         c->remote_window -= len;
1659                         debug2("channel %d: sent ext data %d", c->self, len);
1660                 }
1661         }
1662 }
1663
1664
1665 /* -- protocol input */
1666
1667 void
1668 channel_input_data(int type, u_int32_t seq, void *ctxt)
1669 {
1670         int id;
1671         char *data;
1672         u_int data_len;
1673         Channel *c;
1674
1675         /* Get the channel number and verify it. */
1676         id = packet_get_int();
1677         c = channel_lookup(id);
1678         if (c == NULL)
1679                 packet_disconnect("Received data for nonexistent channel %d.", id);
1680
1681         /* Ignore any data for non-open channels (might happen on close) */
1682         if (c->type != SSH_CHANNEL_OPEN &&
1683             c->type != SSH_CHANNEL_X11_OPEN)
1684                 return;
1685
1686         /* same for protocol 1.5 if output end is no longer open */
1687         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN)
1688                 return;
1689
1690         /* Get the data. */
1691         data = packet_get_string(&data_len);
1692
1693         if (compat20) {
1694                 if (data_len > c->local_maxpacket) {
1695                         log("channel %d: rcvd big packet %d, maxpack %d",
1696                             c->self, data_len, c->local_maxpacket);
1697                 }
1698                 if (data_len > c->local_window) {
1699                         log("channel %d: rcvd too much data %d, win %d",
1700                             c->self, data_len, c->local_window);
1701                         xfree(data);
1702                         return;
1703                 }
1704                 c->local_window -= data_len;
1705         }
1706         packet_check_eom();
1707         buffer_append(&c->output, data, data_len);
1708         xfree(data);
1709 }
1710
1711 void
1712 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
1713 {
1714         int id;
1715         int tcode;
1716         char *data;
1717         u_int data_len;
1718         Channel *c;
1719
1720         /* Get the channel number and verify it. */
1721         id = packet_get_int();
1722         c = channel_lookup(id);
1723
1724         if (c == NULL)
1725                 packet_disconnect("Received extended_data for bad channel %d.", id);
1726         if (c->type != SSH_CHANNEL_OPEN) {
1727                 log("channel %d: ext data for non open", id);
1728                 return;
1729         }
1730         tcode = packet_get_int();
1731         if (c->efd == -1 ||
1732             c->extended_usage != CHAN_EXTENDED_WRITE ||
1733             tcode != SSH2_EXTENDED_DATA_STDERR) {
1734                 log("channel %d: bad ext data", c->self);
1735                 return;
1736         }
1737         data = packet_get_string(&data_len);
1738         packet_check_eom();
1739         if (data_len > c->local_window) {
1740                 log("channel %d: rcvd too much extended_data %d, win %d",
1741                     c->self, data_len, c->local_window);
1742                 xfree(data);
1743                 return;
1744         }
1745         debug2("channel %d: rcvd ext data %d", c->self, data_len);
1746         c->local_window -= data_len;
1747         buffer_append(&c->extended, data, data_len);
1748         xfree(data);
1749 }
1750
1751 void
1752 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
1753 {
1754         int id;
1755         Channel *c;
1756
1757         id = packet_get_int();
1758         packet_check_eom();
1759         c = channel_lookup(id);
1760         if (c == NULL)
1761                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
1762         chan_rcvd_ieof(c);
1763
1764         /* XXX force input close */
1765         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
1766                 debug("channel %d: FORCE input drain", c->self);
1767                 c->istate = CHAN_INPUT_WAIT_DRAIN;
1768                 if (buffer_len(&c->input) == 0)
1769                         chan_ibuf_empty(c);
1770         }
1771
1772 }
1773
1774 void
1775 channel_input_close(int type, u_int32_t seq, void *ctxt)
1776 {
1777         int id;
1778         Channel *c;
1779
1780         id = packet_get_int();
1781         packet_check_eom();
1782         c = channel_lookup(id);
1783         if (c == NULL)
1784                 packet_disconnect("Received close for nonexistent channel %d.", id);
1785
1786         /*
1787          * Send a confirmation that we have closed the channel and no more
1788          * data is coming for it.
1789          */
1790         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
1791         packet_put_int(c->remote_id);
1792         packet_send();
1793
1794         /*
1795          * If the channel is in closed state, we have sent a close request,
1796          * and the other side will eventually respond with a confirmation.
1797          * Thus, we cannot free the channel here, because then there would be
1798          * no-one to receive the confirmation.  The channel gets freed when
1799          * the confirmation arrives.
1800          */
1801         if (c->type != SSH_CHANNEL_CLOSED) {
1802                 /*
1803                  * Not a closed channel - mark it as draining, which will
1804                  * cause it to be freed later.
1805                  */
1806                 buffer_clear(&c->input);
1807                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
1808         }
1809 }
1810
1811 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
1812 void
1813 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
1814 {
1815         int id = packet_get_int();
1816         Channel *c = channel_lookup(id);
1817
1818         packet_check_eom();
1819         if (c == NULL)
1820                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
1821         chan_rcvd_oclose(c);
1822 }
1823
1824 void
1825 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
1826 {
1827         int id = packet_get_int();
1828         Channel *c = channel_lookup(id);
1829
1830         packet_check_eom();
1831         if (c == NULL)
1832                 packet_disconnect("Received close confirmation for "
1833                     "out-of-range channel %d.", id);
1834         if (c->type != SSH_CHANNEL_CLOSED)
1835                 packet_disconnect("Received close confirmation for "
1836                     "non-closed channel %d (type %d).", id, c->type);
1837         channel_free(c);
1838 }
1839
1840 void
1841 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
1842 {
1843         int id, remote_id;
1844         Channel *c;
1845
1846         id = packet_get_int();
1847         c = channel_lookup(id);
1848
1849         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
1850                 packet_disconnect("Received open confirmation for "
1851                     "non-opening channel %d.", id);
1852         remote_id = packet_get_int();
1853         /* Record the remote channel number and mark that the channel is now open. */
1854         c->remote_id = remote_id;
1855         c->type = SSH_CHANNEL_OPEN;
1856
1857         if (compat20) {
1858                 c->remote_window = packet_get_int();
1859                 c->remote_maxpacket = packet_get_int();
1860                 if (c->confirm) {
1861                         debug2("callback start");
1862                         c->confirm(c->self, NULL);
1863                         debug2("callback done");
1864                 }
1865                 debug("channel %d: open confirm rwindow %d rmax %d", c->self,
1866                     c->remote_window, c->remote_maxpacket);
1867         }
1868         packet_check_eom();
1869 }
1870
1871 static char *
1872 reason2txt(int reason)
1873 {
1874         switch (reason) {
1875         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
1876                 return "administratively prohibited";
1877         case SSH2_OPEN_CONNECT_FAILED:
1878                 return "connect failed";
1879         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
1880                 return "unknown channel type";
1881         case SSH2_OPEN_RESOURCE_SHORTAGE:
1882                 return "resource shortage";
1883         }
1884         return "unknown reason";
1885 }
1886
1887 void
1888 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
1889 {
1890         int id, reason;
1891         char *msg = NULL, *lang = NULL;
1892         Channel *c;
1893
1894         id = packet_get_int();
1895         c = channel_lookup(id);
1896
1897         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
1898                 packet_disconnect("Received open failure for "
1899                     "non-opening channel %d.", id);
1900         if (compat20) {
1901                 reason = packet_get_int();
1902                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1903                         msg  = packet_get_string(NULL);
1904                         lang = packet_get_string(NULL);
1905                 }
1906                 log("channel %d: open failed: %s%s%s", id,
1907                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
1908                 if (msg != NULL)
1909                         xfree(msg);
1910                 if (lang != NULL)
1911                         xfree(lang);
1912         }
1913         packet_check_eom();
1914         /* Free the channel.  This will also close the socket. */
1915         channel_free(c);
1916 }
1917
1918 void
1919 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
1920 {
1921         Channel *c;
1922         int id, adjust;
1923
1924         if (!compat20)
1925                 return;
1926
1927         /* Get the channel number and verify it. */
1928         id = packet_get_int();
1929         c = channel_lookup(id);
1930
1931         if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
1932                 log("Received window adjust for "
1933                     "non-open channel %d.", id);
1934                 return;
1935         }
1936         adjust = packet_get_int();
1937         packet_check_eom();
1938         debug2("channel %d: rcvd adjust %d", id, adjust);
1939         c->remote_window += adjust;
1940 }
1941
1942 void
1943 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
1944 {
1945         Channel *c = NULL;
1946         u_short host_port;
1947         char *host, *originator_string;
1948         int remote_id, sock = -1;
1949
1950         remote_id = packet_get_int();
1951         host = packet_get_string(NULL);
1952         host_port = packet_get_int();
1953
1954         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
1955                 originator_string = packet_get_string(NULL);
1956         } else {
1957                 originator_string = xstrdup("unknown (remote did not supply name)");
1958         }
1959         packet_check_eom();
1960         sock = channel_connect_to(host, host_port);
1961         if (sock != -1) {
1962                 c = channel_new("connected socket",
1963                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
1964                     originator_string, 1);
1965                 c->remote_id = remote_id;
1966         }
1967         if (c == NULL) {
1968                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1969                 packet_put_int(remote_id);
1970                 packet_send();
1971         }
1972         xfree(host);
1973 }
1974
1975
1976 /* -- tcp forwarding */
1977
1978 void
1979 channel_set_af(int af)
1980 {
1981         IPv4or6 = af;
1982 }
1983
1984 static int
1985 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
1986     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
1987 {
1988         Channel *c;
1989         int success, sock, on = 1;
1990         struct addrinfo hints, *ai, *aitop;
1991         const char *host;
1992         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1993         struct linger linger;
1994
1995         success = 0;
1996         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
1997             listen_addr : host_to_connect;
1998
1999         if (host == NULL) {
2000                 error("No forward host name.");
2001                 return success;
2002         }
2003         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2004                 error("Forward host name too long.");
2005                 return success;
2006         }
2007
2008         /*
2009          * getaddrinfo returns a loopback address if the hostname is
2010          * set to NULL and hints.ai_flags is not AI_PASSIVE
2011          */
2012         memset(&hints, 0, sizeof(hints));
2013         hints.ai_family = IPv4or6;
2014         hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
2015         hints.ai_socktype = SOCK_STREAM;
2016         snprintf(strport, sizeof strport, "%d", listen_port);
2017         if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
2018                 packet_disconnect("getaddrinfo: fatal error");
2019
2020         for (ai = aitop; ai; ai = ai->ai_next) {
2021                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2022                         continue;
2023                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2024                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2025                         error("channel_setup_fwd_listener: getnameinfo failed");
2026                         continue;
2027                 }
2028                 /* Create a port to listen for the host. */
2029                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
2030                 if (sock < 0) {
2031                         /* this is no error since kernel may not support ipv6 */
2032                         verbose("socket: %.100s", strerror(errno));
2033                         continue;
2034                 }
2035                 /*
2036                  * Set socket options.  We would like the socket to disappear
2037                  * as soon as it has been closed for whatever reason.
2038                  */
2039                 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));
2040                 linger.l_onoff = 1;
2041                 linger.l_linger = 5;
2042                 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
2043                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2044
2045                 /* Bind the socket to the address. */
2046                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2047                         /* address can be in use ipv6 address is already bound */
2048                         if (!ai->ai_next)
2049                                 error("bind: %.100s", strerror(errno));
2050                         else
2051                                 verbose("bind: %.100s", strerror(errno));
2052
2053                         close(sock);
2054                         continue;
2055                 }
2056                 /* Start listening for connections on the socket. */
2057                 if (listen(sock, 5) < 0) {
2058                         error("listen: %.100s", strerror(errno));
2059                         close(sock);
2060                         continue;
2061                 }
2062                 /* Allocate a channel number for the socket. */
2063                 c = channel_new("port listener", type, sock, sock, -1,
2064                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2065                     0, xstrdup("port listener"), 1);
2066                 strlcpy(c->path, host, sizeof(c->path));
2067                 c->host_port = port_to_connect;
2068                 c->listening_port = listen_port;
2069                 success = 1;
2070         }
2071         if (success == 0)
2072                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2073                     listen_port);
2074         freeaddrinfo(aitop);
2075         return success;
2076 }
2077
2078 /* protocol local port fwd, used by ssh (and sshd in v1) */
2079 int
2080 channel_setup_local_fwd_listener(u_short listen_port,
2081     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2082 {
2083         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2084             NULL, listen_port, host_to_connect, port_to_connect, gateway_ports);
2085 }
2086
2087 /* protocol v2 remote port fwd, used by sshd */
2088 int
2089 channel_setup_remote_fwd_listener(const char *listen_address,
2090     u_short listen_port, int gateway_ports)
2091 {
2092         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2093             listen_address, listen_port, NULL, 0, gateway_ports);
2094 }
2095
2096 /*
2097  * Initiate forwarding of connections to port "port" on remote host through
2098  * the secure channel to host:port from local side.
2099  */
2100
2101 void
2102 channel_request_remote_forwarding(u_short listen_port,
2103     const char *host_to_connect, u_short port_to_connect)
2104 {
2105         int type, success = 0;
2106
2107         /* Record locally that connection to this host/port is permitted. */
2108         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2109                 fatal("channel_request_remote_forwarding: too many forwards");
2110
2111         /* Send the forward request to the remote side. */
2112         if (compat20) {
2113                 const char *address_to_bind = "0.0.0.0";
2114                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2115                 packet_put_cstring("tcpip-forward");
2116                 packet_put_char(0);                     /* boolean: want reply */
2117                 packet_put_cstring(address_to_bind);
2118                 packet_put_int(listen_port);
2119                 packet_send();
2120                 packet_write_wait();
2121                 /* Assume that server accepts the request */
2122                 success = 1;
2123         } else {
2124                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2125                 packet_put_int(listen_port);
2126                 packet_put_cstring(host_to_connect);
2127                 packet_put_int(port_to_connect);
2128                 packet_send();
2129                 packet_write_wait();
2130
2131                 /* Wait for response from the remote side. */
2132                 type = packet_read();
2133                 switch (type) {
2134                 case SSH_SMSG_SUCCESS:
2135                         success = 1;
2136                         break;
2137                 case SSH_SMSG_FAILURE:
2138                         log("Warning: Server denied remote port forwarding.");
2139                         break;
2140                 default:
2141                         /* Unknown packet */
2142                         packet_disconnect("Protocol error for port forward request:"
2143                             "received packet type %d.", type);
2144                 }
2145         }
2146         if (success) {
2147                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2148                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2149                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2150                 num_permitted_opens++;
2151         }
2152 }
2153
2154 /*
2155  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2156  * listening for the port, and sends back a success reply (or disconnect
2157  * message if there was an error).  This never returns if there was an error.
2158  */
2159
2160 void
2161 channel_input_port_forward_request(int is_root, int gateway_ports)
2162 {
2163         u_short port, host_port;
2164         char *hostname;
2165
2166         /* Get arguments from the packet. */
2167         port = packet_get_int();
2168         hostname = packet_get_string(NULL);
2169         host_port = packet_get_int();
2170
2171 #ifndef HAVE_CYGWIN
2172         /*
2173          * Check that an unprivileged user is not trying to forward a
2174          * privileged port.
2175          */
2176         if (port < IPPORT_RESERVED && !is_root)
2177                 packet_disconnect("Requested forwarding of port %d but user is not root.",
2178                                   port);
2179 #endif
2180         /* Initiate forwarding */
2181         channel_setup_local_fwd_listener(port, hostname, host_port, gateway_ports);
2182
2183         /* Free the argument string. */
2184         xfree(hostname);
2185 }
2186
2187 /*
2188  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2189  * usually called by the server, because the user could connect to any port
2190  * anyway, and the server has no way to know but to trust the client anyway.
2191  */
2192 void
2193 channel_permit_all_opens(void)
2194 {
2195         if (num_permitted_opens == 0)
2196                 all_opens_permitted = 1;
2197 }
2198
2199 void
2200 channel_add_permitted_opens(char *host, int port)
2201 {
2202         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2203                 fatal("channel_request_remote_forwarding: too many forwards");
2204         debug("allow port forwarding to host %s port %d", host, port);
2205
2206         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2207         permitted_opens[num_permitted_opens].port_to_connect = port;
2208         num_permitted_opens++;
2209
2210         all_opens_permitted = 0;
2211 }
2212
2213 void
2214 channel_clear_permitted_opens(void)
2215 {
2216         int i;
2217
2218         for (i = 0; i < num_permitted_opens; i++)
2219                 xfree(permitted_opens[i].host_to_connect);
2220         num_permitted_opens = 0;
2221
2222 }
2223
2224
2225 /* return socket to remote host, port */
2226 static int
2227 connect_to(const char *host, u_short port)
2228 {
2229         struct addrinfo hints, *ai, *aitop;
2230         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2231         int gaierr;
2232         int sock = -1;
2233
2234         memset(&hints, 0, sizeof(hints));
2235         hints.ai_family = IPv4or6;
2236         hints.ai_socktype = SOCK_STREAM;
2237         snprintf(strport, sizeof strport, "%d", port);
2238         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2239                 error("connect_to %.100s: unknown host (%s)", host,
2240                     gai_strerror(gaierr));
2241                 return -1;
2242         }
2243         for (ai = aitop; ai; ai = ai->ai_next) {
2244                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2245                         continue;
2246                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2247                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2248                         error("connect_to: getnameinfo failed");
2249                         continue;
2250                 }
2251                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
2252                 if (sock < 0) {
2253                         error("socket: %.100s", strerror(errno));
2254                         continue;
2255                 }
2256                 if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0)
2257                         fatal("connect_to: F_SETFL: %s", strerror(errno));
2258                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2259                     errno != EINPROGRESS) {
2260                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2261                             strerror(errno));
2262                         close(sock);
2263                         continue;       /* fail -- try next */
2264                 }
2265                 break; /* success */
2266
2267         }
2268         freeaddrinfo(aitop);
2269         if (!ai) {
2270                 error("connect_to %.100s port %d: failed.", host, port);
2271                 return -1;
2272         }
2273         /* success */
2274         return sock;
2275 }
2276
2277 int
2278 channel_connect_by_listen_address(u_short listen_port)
2279 {
2280         int i;
2281
2282         for (i = 0; i < num_permitted_opens; i++)
2283                 if (permitted_opens[i].listen_port == listen_port)
2284                         return connect_to(
2285                             permitted_opens[i].host_to_connect,
2286                             permitted_opens[i].port_to_connect);
2287         error("WARNING: Server requests forwarding for unknown listen_port %d",
2288             listen_port);
2289         return -1;
2290 }
2291
2292 /* Check if connecting to that port is permitted and connect. */
2293 int
2294 channel_connect_to(const char *host, u_short port)
2295 {
2296         int i, permit;
2297
2298         permit = all_opens_permitted;
2299         if (!permit) {
2300                 for (i = 0; i < num_permitted_opens; i++)
2301                         if (permitted_opens[i].port_to_connect == port &&
2302                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2303                                 permit = 1;
2304
2305         }
2306         if (!permit) {
2307                 log("Received request to connect to host %.100s port %d, "
2308                     "but the request was denied.", host, port);
2309                 return -1;
2310         }
2311         return connect_to(host, port);
2312 }
2313
2314 /* -- X11 forwarding */
2315
2316 /*
2317  * Creates an internet domain socket for listening for X11 connections.
2318  * Returns a suitable display number for the DISPLAY variable, or -1 if
2319  * an error occurs.
2320  */
2321 int
2322 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2323     int single_connection)
2324 {
2325         Channel *nc = NULL;
2326         int display_number, sock;
2327         u_short port;
2328         struct addrinfo hints, *ai, *aitop;
2329         char strport[NI_MAXSERV];
2330         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2331
2332         for (display_number = x11_display_offset;
2333             display_number < MAX_DISPLAYS;
2334             display_number++) {
2335                 port = 6000 + display_number;
2336                 memset(&hints, 0, sizeof(hints));
2337                 hints.ai_family = IPv4or6;
2338                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2339                 hints.ai_socktype = SOCK_STREAM;
2340                 snprintf(strport, sizeof strport, "%d", port);
2341                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2342                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2343                         return -1;
2344                 }
2345                 for (ai = aitop; ai; ai = ai->ai_next) {
2346                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2347                                 continue;
2348                         sock = socket(ai->ai_family, SOCK_STREAM, 0);
2349                         if (sock < 0) {
2350                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2351                                         error("socket: %.100s", strerror(errno));
2352                                         return -1;
2353                                 } else {
2354                                         debug("x11_create_display_inet: Socket family %d not supported",
2355                                                  ai->ai_family);
2356                                         continue;
2357                                 }
2358                         }
2359                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2360                                 debug("bind port %d: %.100s", port, strerror(errno));
2361                                 close(sock);
2362
2363                                 if (ai->ai_next)
2364                                         continue;
2365
2366                                 for (n = 0; n < num_socks; n++) {
2367                                         close(socks[n]);
2368                                 }
2369                                 num_socks = 0;
2370                                 break;
2371                         }
2372                         socks[num_socks++] = sock;
2373 #ifndef DONT_TRY_OTHER_AF
2374                         if (num_socks == NUM_SOCKS)
2375                                 break;
2376 #else
2377                         break;
2378 #endif
2379                 }
2380                 freeaddrinfo(aitop);
2381                 if (num_socks > 0)
2382                         break;
2383         }
2384         if (display_number >= MAX_DISPLAYS) {
2385                 error("Failed to allocate internet-domain X11 display socket.");
2386                 return -1;
2387         }
2388         /* Start listening for connections on the socket. */
2389         for (n = 0; n < num_socks; n++) {
2390                 sock = socks[n];
2391                 if (listen(sock, 5) < 0) {
2392                         error("listen: %.100s", strerror(errno));
2393                         close(sock);
2394                         return -1;
2395                 }
2396         }
2397
2398         /* Allocate a channel for each socket. */
2399         for (n = 0; n < num_socks; n++) {
2400                 sock = socks[n];
2401                 nc = channel_new("x11 listener",
2402                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2403                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2404                     0, xstrdup("X11 inet listener"), 1);
2405                 nc->single_connection = single_connection;
2406         }
2407
2408         /* Return the display number for the DISPLAY environment variable. */
2409         return display_number;
2410 }
2411
2412 static int
2413 connect_local_xsocket(u_int dnr)
2414 {
2415         int sock;
2416         struct sockaddr_un addr;
2417
2418         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2419         if (sock < 0)
2420                 error("socket: %.100s", strerror(errno));
2421         memset(&addr, 0, sizeof(addr));
2422         addr.sun_family = AF_UNIX;
2423         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2424         if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2425                 return sock;
2426         close(sock);
2427         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2428         return -1;
2429 }
2430
2431 int
2432 x11_connect_display(void)
2433 {
2434         int display_number, sock = 0;
2435         const char *display;
2436         char buf[1024], *cp;
2437         struct addrinfo hints, *ai, *aitop;
2438         char strport[NI_MAXSERV];
2439         int gaierr;
2440
2441         /* Try to open a socket for the local X server. */
2442         display = getenv("DISPLAY");
2443         if (!display) {
2444                 error("DISPLAY not set.");
2445                 return -1;
2446         }
2447         /*
2448          * Now we decode the value of the DISPLAY variable and make a
2449          * connection to the real X server.
2450          */
2451
2452         /*
2453          * Check if it is a unix domain socket.  Unix domain displays are in
2454          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2455          */
2456         if (strncmp(display, "unix:", 5) == 0 ||
2457             display[0] == ':') {
2458                 /* Connect to the unix domain socket. */
2459                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2460                         error("Could not parse display number from DISPLAY: %.100s",
2461                             display);
2462                         return -1;
2463                 }
2464                 /* Create a socket. */
2465                 sock = connect_local_xsocket(display_number);
2466                 if (sock < 0)
2467                         return -1;
2468
2469                 /* OK, we now have a connection to the display. */
2470                 return sock;
2471         }
2472         /*
2473          * Connect to an inet socket.  The DISPLAY value is supposedly
2474          * hostname:d[.s], where hostname may also be numeric IP address.
2475          */
2476         strlcpy(buf, display, sizeof(buf));
2477         cp = strchr(buf, ':');
2478         if (!cp) {
2479                 error("Could not find ':' in DISPLAY: %.100s", display);
2480                 return -1;
2481         }
2482         *cp = 0;
2483         /* buf now contains the host name.  But first we parse the display number. */
2484         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2485                 error("Could not parse display number from DISPLAY: %.100s",
2486                     display);
2487                 return -1;
2488         }
2489
2490         /* Look up the host address */
2491         memset(&hints, 0, sizeof(hints));
2492         hints.ai_family = IPv4or6;
2493         hints.ai_socktype = SOCK_STREAM;
2494         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2495         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2496                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2497                 return -1;
2498         }
2499         for (ai = aitop; ai; ai = ai->ai_next) {
2500                 /* Create a socket. */
2501                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
2502                 if (sock < 0) {
2503                         debug("socket: %.100s", strerror(errno));
2504                         continue;
2505                 }
2506                 /* Connect it to the display. */
2507                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2508                         debug("connect %.100s port %d: %.100s", buf,
2509                             6000 + display_number, strerror(errno));
2510                         close(sock);
2511                         continue;
2512                 }
2513                 /* Success */
2514                 break;
2515         }
2516         freeaddrinfo(aitop);
2517         if (!ai) {
2518                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2519                     strerror(errno));
2520                 return -1;
2521         }
2522         set_nodelay(sock);
2523         return sock;
2524 }
2525
2526 /*
2527  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2528  * the remote channel number.  We should do whatever we want, and respond
2529  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2530  */
2531
2532 void
2533 x11_input_open(int type, u_int32_t seq, void *ctxt)
2534 {
2535         Channel *c = NULL;
2536         int remote_id, sock = 0;
2537         char *remote_host;
2538
2539         debug("Received X11 open request.");
2540
2541         remote_id = packet_get_int();
2542
2543         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2544                 remote_host = packet_get_string(NULL);
2545         } else {
2546                 remote_host = xstrdup("unknown (remote did not supply name)");
2547         }
2548         packet_check_eom();
2549
2550         /* Obtain a connection to the real X display. */
2551         sock = x11_connect_display();
2552         if (sock != -1) {
2553                 /* Allocate a channel for this connection. */
2554                 c = channel_new("connected x11 socket",
2555                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
2556                     remote_host, 1);
2557                 c->remote_id = remote_id;
2558                 c->force_drain = 1;
2559         }
2560         if (c == NULL) {
2561                 /* Send refusal to the remote host. */
2562                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2563                 packet_put_int(remote_id);
2564         } else {
2565                 /* Send a confirmation to the remote host. */
2566                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2567                 packet_put_int(remote_id);
2568                 packet_put_int(c->self);
2569         }
2570         packet_send();
2571 }
2572
2573 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
2574 void
2575 deny_input_open(int type, u_int32_t seq, void *ctxt)
2576 {
2577         int rchan = packet_get_int();
2578         switch (type) {
2579         case SSH_SMSG_AGENT_OPEN:
2580                 error("Warning: ssh server tried agent forwarding.");
2581                 break;
2582         case SSH_SMSG_X11_OPEN:
2583                 error("Warning: ssh server tried X11 forwarding.");
2584                 break;
2585         default:
2586                 error("deny_input_open: type %d", type);
2587                 break;
2588         }
2589         error("Warning: this is probably a break in attempt by a malicious server.");
2590         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2591         packet_put_int(rchan);
2592         packet_send();
2593 }
2594
2595 /*
2596  * Requests forwarding of X11 connections, generates fake authentication
2597  * data, and enables authentication spoofing.
2598  * This should be called in the client only.
2599  */
2600 void
2601 x11_request_forwarding_with_spoofing(int client_session_id,
2602     const char *proto, const char *data)
2603 {
2604         u_int data_len = (u_int) strlen(data) / 2;
2605         u_int i, value, len;
2606         char *new_data;
2607         int screen_number;
2608         const char *cp;
2609         u_int32_t rand = 0;
2610
2611         cp = getenv("DISPLAY");
2612         if (cp)
2613                 cp = strchr(cp, ':');
2614         if (cp)
2615                 cp = strchr(cp, '.');
2616         if (cp)
2617                 screen_number = atoi(cp + 1);
2618         else
2619                 screen_number = 0;
2620
2621         /* Save protocol name. */
2622         x11_saved_proto = xstrdup(proto);
2623
2624         /*
2625          * Extract real authentication data and generate fake data of the
2626          * same length.
2627          */
2628         x11_saved_data = xmalloc(data_len);
2629         x11_fake_data = xmalloc(data_len);
2630         for (i = 0; i < data_len; i++) {
2631                 if (sscanf(data + 2 * i, "%2x", &value) != 1)
2632                         fatal("x11_request_forwarding: bad authentication data: %.100s", data);
2633                 if (i % 4 == 0)
2634                         rand = arc4random();
2635                 x11_saved_data[i] = value;
2636                 x11_fake_data[i] = rand & 0xff;
2637                 rand >>= 8;
2638         }
2639         x11_saved_data_len = data_len;
2640         x11_fake_data_len = data_len;
2641
2642         /* Convert the fake data into hex. */
2643         len = 2 * data_len + 1;
2644         new_data = xmalloc(len);
2645         for (i = 0; i < data_len; i++)
2646                 snprintf(new_data + 2 * i, len - 2 * i,
2647                     "%02x", (u_char) x11_fake_data[i]);
2648
2649         /* Send the request packet. */
2650         if (compat20) {
2651                 channel_request_start(client_session_id, "x11-req", 0);
2652                 packet_put_char(0);     /* XXX bool single connection */
2653         } else {
2654                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
2655         }
2656         packet_put_cstring(proto);
2657         packet_put_cstring(new_data);
2658         packet_put_int(screen_number);
2659         packet_send();
2660         packet_write_wait();
2661         xfree(new_data);
2662 }
2663
2664
2665 /* -- agent forwarding */
2666
2667 /* Sends a message to the server to request authentication fd forwarding. */
2668
2669 void
2670 auth_request_forwarding(void)
2671 {
2672         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
2673         packet_send();
2674         packet_write_wait();
2675 }
2676
2677 /*
2678  * Returns the name of the forwarded authentication socket.  Returns NULL if
2679  * there is no forwarded authentication socket.  The returned value points to
2680  * a static buffer.
2681  */
2682
2683 char *
2684 auth_get_socket_name(void)
2685 {
2686         return auth_sock_name;
2687 }
2688
2689 /* removes the agent forwarding socket */
2690
2691 void
2692 auth_sock_cleanup_proc(void *_pw)
2693 {
2694         struct passwd *pw = _pw;
2695
2696         if (auth_sock_name) {
2697                 temporarily_use_uid(pw);
2698                 unlink(auth_sock_name);
2699                 rmdir(auth_sock_dir);
2700                 auth_sock_name = NULL;
2701                 restore_uid();
2702         }
2703 }
2704
2705 /*
2706  * This is called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
2707  * This starts forwarding authentication requests.
2708  */
2709
2710 int
2711 auth_input_request_forwarding(struct passwd * pw)
2712 {
2713         Channel *nc;
2714         int sock;
2715         struct sockaddr_un sunaddr;
2716
2717         if (auth_get_socket_name() != NULL) {
2718                 error("authentication forwarding requested twice.");
2719                 return 0;
2720         }
2721
2722         /* Temporarily drop privileged uid for mkdir/bind. */
2723         temporarily_use_uid(pw);
2724
2725         /* Allocate a buffer for the socket name, and format the name. */
2726         auth_sock_name = xmalloc(MAXPATHLEN);
2727         auth_sock_dir = xmalloc(MAXPATHLEN);
2728         strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
2729
2730         /* Create private directory for socket */
2731         if (mkdtemp(auth_sock_dir) == NULL) {
2732                 packet_send_debug("Agent forwarding disabled: "
2733                     "mkdtemp() failed: %.100s", strerror(errno));
2734                 restore_uid();
2735                 xfree(auth_sock_name);
2736                 xfree(auth_sock_dir);
2737                 auth_sock_name = NULL;
2738                 auth_sock_dir = NULL;
2739                 return 0;
2740         }
2741         snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%d",
2742                  auth_sock_dir, (int) getpid());
2743
2744         /* delete agent socket on fatal() */
2745         fatal_add_cleanup(auth_sock_cleanup_proc, pw);
2746
2747         /* Create the socket. */
2748         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2749         if (sock < 0)
2750                 packet_disconnect("socket: %.100s", strerror(errno));
2751
2752         /* Bind it to the name. */
2753         memset(&sunaddr, 0, sizeof(sunaddr));
2754         sunaddr.sun_family = AF_UNIX;
2755         strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path));
2756
2757         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
2758                 packet_disconnect("bind: %.100s", strerror(errno));
2759
2760         /* Restore the privileged uid. */
2761         restore_uid();
2762
2763         /* Start listening on the socket. */
2764         if (listen(sock, 5) < 0)
2765                 packet_disconnect("listen: %.100s", strerror(errno));
2766
2767         /* Allocate a channel for the authentication agent socket. */
2768         nc = channel_new("auth socket",
2769             SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
2770             CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2771             0, xstrdup("auth socket"), 1);
2772         strlcpy(nc->path, auth_sock_name, sizeof(nc->path));
2773         return 1;
2774 }
2775
2776 /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
2777
2778 void
2779 auth_input_open_request(int type, u_int32_t seq, void *ctxt)
2780 {
2781         Channel *c = NULL;
2782         int remote_id, sock;
2783         char *name;
2784
2785         /* Read the remote channel number from the message. */
2786         remote_id = packet_get_int();
2787         packet_check_eom();
2788
2789         /*
2790          * Get a connection to the local authentication agent (this may again
2791          * get forwarded).
2792          */
2793         sock = ssh_get_authentication_socket();
2794
2795         /*
2796          * If we could not connect the agent, send an error message back to
2797          * the server. This should never happen unless the agent dies,
2798          * because authentication forwarding is only enabled if we have an
2799          * agent.
2800          */
2801         if (sock >= 0) {
2802                 name = xstrdup("authentication agent connection");
2803                 c = channel_new("", SSH_CHANNEL_OPEN, sock, sock,
2804                     -1, 0, 0, 0, name, 1);
2805                 c->remote_id = remote_id;
2806                 c->force_drain = 1;
2807         }
2808         if (c == NULL) {
2809                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2810                 packet_put_int(remote_id);
2811         } else {
2812                 /* Send a confirmation to the remote host. */
2813                 debug("Forwarding authentication connection.");
2814                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2815                 packet_put_int(remote_id);
2816                 packet_put_int(c->self);
2817         }
2818         packet_send();
2819 }