crypto/openssh-3.8.1p1/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 1.200 2004/01/19 09:24:21 markus Exp $");
  43
  44 #include "ssh.h"
  45 #include "ssh1.h"
  46 #include "ssh2.h"
  47 #include "packet.h"
  48 #include "xmalloc.h"
  49 #include "log.h"
  50 #include "misc.h"
  51 #include "channels.h"
  52 #include "compat.h"
  53 #include "canohost.h"
  54 #include "key.h"
  55 #include "authfd.h"
  56 #include "pathnames.h"
  57 #include "bufaux.h"
  58
  59 /* -- channel core */
  60
  61 /*
  62  * Pointer to an array containing all allocated channels.  The array is
  63  * dynamically extended as needed.
  64  */
  65 static Channel **channels = NULL;
  66
  67 /*
  68  * Size of the channel array.  All slots of the array must always be
  69  * initialized (at least the type field); unused slots set to NULL
  70  */
  71 static int channels_alloc = 0;
  72
  73 /*
  74  * Maximum file descriptor value used in any of the channels.  This is
  75  * updated in channel_new.
  76  */
  77 static int channel_max_fd = 0;
  78
  79
  80 /* -- tcp forwarding */
  81
  82 /*
  83  * Data structure for storing which hosts are permitted for forward requests.
  84  * The local sides of any remote forwards are stored in this array to prevent
  85  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  86  * network (which might be behind a firewall).
  87  */
  88 typedef struct {
  89         char *host_to_connect;          /* Connect to 'host'. */
  90         u_short port_to_connect;        /* Connect to 'port'. */
  91         u_short listen_port;            /* Remote side should listen port number. */
  92 } ForwardPermission;
  93
  94 /* List of all permitted host/port pairs to connect. */
  95 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
  96
  97 /* Number of permitted host/port pairs in the array. */
  98 static int num_permitted_opens = 0;
  99 /*
 100  * If this is true, all opens are permitted.  This is the case on the server
 101  * on which we have to trust the client anyway, and the user could do
 102  * anything after logging in anyway.
 103  */
 104 static int all_opens_permitted = 0;
 105
 106
 107 /* -- X11 forwarding */
 108
 109 /* Maximum number of fake X11 displays to try. */
 110 #define MAX_DISPLAYS  1000
 111
 112 /* Saved X11 authentication protocol name. */
 113 static char *x11_saved_proto = NULL;
 114
 115 /* Saved X11 authentication data.  This is the real data. */
 116 static char *x11_saved_data = NULL;
 117 static u_int x11_saved_data_len = 0;
 118
 119 /*
 120  * Fake X11 authentication data.  This is what the server will be sending us;
 121  * we should replace any occurrences of this by the real data.
 122  */
 123 static char *x11_fake_data = NULL;
 124 static u_int x11_fake_data_len;
 125
 126
 127 /* -- agent forwarding */
 128
 129 #define NUM_SOCKS       10
 130
 131 /* AF_UNSPEC or AF_INET or AF_INET6 */
 132 static int IPv4or6 = AF_UNSPEC;
 133
 134 /* helper */
 135 static void port_open_helper(Channel *c, char *rtype);
 136
 137 /* -- channel core */
 138
 139 Channel *
 140 channel_lookup(int id)
 141 {
 142         Channel *c;
 143
 144         if (id < 0 || id >= channels_alloc) {
 145                 logit("channel_lookup: %d: bad id", id);
 146                 return NULL;
 147         }
 148         c = channels[id];
 149         if (c == NULL) {
 150                 logit("channel_lookup: %d: bad id: channel free", id);
 151                 return NULL;
 152         }
 153         return c;
 154 }
 155
 156 /*
 157  * Register filedescriptors for a channel, used when allocating a channel or
 158  * when the channel consumer/producer is ready, e.g. shell exec'd
 159  */
 160
 161 static void
 162 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 163     int extusage, int nonblock)
 164 {
 165         /* Update the maximum file descriptor value. */
 166         channel_max_fd = MAX(channel_max_fd, rfd);
 167         channel_max_fd = MAX(channel_max_fd, wfd);
 168         channel_max_fd = MAX(channel_max_fd, efd);
 169
 170         /* XXX set close-on-exec -markus */
 171
 172         c->rfd = rfd;
 173         c->wfd = wfd;
 174         c->sock = (rfd == wfd) ? rfd : -1;
 175         c->efd = efd;
 176         c->extended_usage = extusage;
 177
 178         /* XXX ugly hack: nonblock is only set by the server */
 179         if (nonblock && isatty(c->rfd)) {
 180                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 181                 c->isatty = 1;
 182                 if (!isatty(c->wfd)) {
 183                         error("channel %d: wfd %d is not a tty?",
 184                             c->self, c->wfd);
 185                 }
 186         } else {
 187                 c->isatty = 0;
 188         }
 189         c->wfd_isatty = isatty(c->wfd);
 190
 191         /* enable nonblocking mode */
 192         if (nonblock) {
 193                 if (rfd != -1)
 194                         set_nonblock(rfd);
 195                 if (wfd != -1)
 196                         set_nonblock(wfd);
 197                 if (efd != -1)
 198                         set_nonblock(efd);
 199         }
 200 }
 201
 202 /*
 203  * Allocate a new channel object and set its type and socket. This will cause
 204  * remote_name to be freed.
 205  */
 206
 207 Channel *
 208 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 209     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 210 {
 211         int i, found;
 212         Channel *c;
 213
 214         /* Do initial allocation if this is the first call. */
 215         if (channels_alloc == 0) {
 216                 channels_alloc = 10;
 217                 channels = xmalloc(channels_alloc * sizeof(Channel *));
 218                 for (i = 0; i < channels_alloc; i++)
 219                         channels[i] = NULL;
 220         }
 221         /* Try to find a free slot where to put the new channel. */
 222         for (found = -1, i = 0; i < channels_alloc; i++)
 223                 if (channels[i] == NULL) {
 224                         /* Found a free slot. */
 225                         found = i;
 226                         break;
 227                 }
 228         if (found == -1) {
 229                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 230                 found = channels_alloc;
 231                 if (channels_alloc > 10000)
 232                         fatal("channel_new: internal error: channels_alloc %d "
 233                             "too big.", channels_alloc);
 234                 channels = xrealloc(channels,
 235                     (channels_alloc + 10) * sizeof(Channel *));
 236                 channels_alloc += 10;
 237                 debug2("channel: expanding %d", channels_alloc);
 238                 for (i = found; i < channels_alloc; i++)
 239                         channels[i] = NULL;
 240         }
 241         /* Initialize and return new channel. */
 242         c = channels[found] = xmalloc(sizeof(Channel));
 243         memset(c, 0, sizeof(Channel));
 244         buffer_init(&c->input);
 245         buffer_init(&c->output);
 246         buffer_init(&c->extended);
 247         c->ostate = CHAN_OUTPUT_OPEN;
 248         c->istate = CHAN_INPUT_OPEN;
 249         c->flags = 0;
 250         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 251         c->self = found;
 252         c->type = type;
 253         c->ctype = ctype;
 254         c->local_window = window;
 255         c->local_window_max = window;
 256         c->local_consumed = 0;
 257         c->local_maxpacket = maxpack;
 258         c->remote_id = -1;
 259         c->remote_name = xstrdup(remote_name);
 260         c->remote_window = 0;
 261         c->remote_maxpacket = 0;
 262         c->force_drain = 0;
 263         c->single_connection = 0;
 264         c->detach_user = NULL;
 265         c->confirm = NULL;
 266         c->input_filter = NULL;
 267         debug("channel %d: new [%s]", found, remote_name);
 268         return c;
 269 }
 270
 271 static int
 272 channel_find_maxfd(void)
 273 {
 274         int i, max = 0;
 275         Channel *c;
 276
 277         for (i = 0; i < channels_alloc; i++) {
 278                 c = channels[i];
 279                 if (c != NULL) {
 280                         max = MAX(max, c->rfd);
 281                         max = MAX(max, c->wfd);
 282                         max = MAX(max, c->efd);
 283                 }
 284         }
 285         return max;
 286 }
 287
 288 int
 289 channel_close_fd(int *fdp)
 290 {
 291         int ret = 0, fd = *fdp;
 292
 293         if (fd != -1) {
 294                 ret = close(fd);
 295                 *fdp = -1;
 296                 if (fd == channel_max_fd)
 297                         channel_max_fd = channel_find_maxfd();
 298         }
 299         return ret;
 300 }
 301
 302 /* Close all channel fd/socket. */
 303
 304 static void
 305 channel_close_fds(Channel *c)
 306 {
 307         debug3("channel %d: close_fds r %d w %d e %d",
 308             c->self, c->rfd, c->wfd, c->efd);
 309
 310         channel_close_fd(&c->sock);
 311         channel_close_fd(&c->rfd);
 312         channel_close_fd(&c->wfd);
 313         channel_close_fd(&c->efd);
 314 }
 315
 316 /* Free the channel and close its fd/socket. */
 317
 318 void
 319 channel_free(Channel *c)
 320 {
 321         char *s;
 322         int i, n;
 323
 324         for (n = 0, i = 0; i < channels_alloc; i++)
 325                 if (channels[i])
 326                         n++;
 327         debug("channel %d: free: %s, nchannels %d", c->self,
 328             c->remote_name ? c->remote_name : "???", n);
 329
 330         s = channel_open_message();
 331         debug3("channel %d: status: %s", c->self, s);
 332         xfree(s);
 333
 334         if (c->sock != -1)
 335                 shutdown(c->sock, SHUT_RDWR);
 336         channel_close_fds(c);
 337         buffer_free(&c->input);
 338         buffer_free(&c->output);
 339         buffer_free(&c->extended);
 340         if (c->remote_name) {
 341                 xfree(c->remote_name);
 342                 c->remote_name = NULL;
 343         }
 344         channels[c->self] = NULL;
 345         xfree(c);
 346 }
 347
 348 void
 349 channel_free_all(void)
 350 {
 351         int i;
 352
 353         for (i = 0; i < channels_alloc; i++)
 354                 if (channels[i] != NULL)
 355                         channel_free(channels[i]);
 356 }
 357
 358 /*
 359  * Closes the sockets/fds of all channels.  This is used to close extra file
 360  * descriptors after a fork.
 361  */
 362
 363 void
 364 channel_close_all(void)
 365 {
 366         int i;
 367
 368         for (i = 0; i < channels_alloc; i++)
 369                 if (channels[i] != NULL)
 370                         channel_close_fds(channels[i]);
 371 }
 372
 373 /*
 374  * Stop listening to channels.
 375  */
 376
 377 void
 378 channel_stop_listening(void)
 379 {
 380         int i;
 381         Channel *c;
 382
 383         for (i = 0; i < channels_alloc; i++) {
 384                 c = channels[i];
 385                 if (c != NULL) {
 386                         switch (c->type) {
 387                         case SSH_CHANNEL_AUTH_SOCKET:
 388                         case SSH_CHANNEL_PORT_LISTENER:
 389                         case SSH_CHANNEL_RPORT_LISTENER:
 390                         case SSH_CHANNEL_X11_LISTENER:
 391                                 channel_close_fd(&c->sock);
 392                                 channel_free(c);
 393                                 break;
 394                         }
 395                 }
 396         }
 397 }
 398
 399 /*
 400  * Returns true if no channel has too much buffered data, and false if one or
 401  * more channel is overfull.
 402  */
 403
 404 int
 405 channel_not_very_much_buffered_data(void)
 406 {
 407         u_int i;
 408         Channel *c;
 409
 410         for (i = 0; i < channels_alloc; i++) {
 411                 c = channels[i];
 412                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 413 #if 0
 414                         if (!compat20 &&
 415                             buffer_len(&c->input) > packet_get_maxsize()) {
 416                                 debug2("channel %d: big input buffer %d",
 417                                     c->self, buffer_len(&c->input));
 418                                 return 0;
 419                         }
 420 #endif
 421                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 422                                 debug2("channel %d: big output buffer %u > %u",
 423                                     c->self, buffer_len(&c->output),
 424                                     packet_get_maxsize());
 425                                 return 0;
 426                         }
 427                 }
 428         }
 429         return 1;
 430 }
 431
 432 /* Returns true if any channel is still open. */
 433
 434 int
 435 channel_still_open(void)
 436 {
 437         int i;
 438         Channel *c;
 439
 440         for (i = 0; i < channels_alloc; i++) {
 441                 c = channels[i];
 442                 if (c == NULL)
 443                         continue;
 444                 switch (c->type) {
 445                 case SSH_CHANNEL_X11_LISTENER:
 446                 case SSH_CHANNEL_PORT_LISTENER:
 447                 case SSH_CHANNEL_RPORT_LISTENER:
 448                 case SSH_CHANNEL_CLOSED:
 449                 case SSH_CHANNEL_AUTH_SOCKET:
 450                 case SSH_CHANNEL_DYNAMIC:
 451                 case SSH_CHANNEL_CONNECTING:
 452                 case SSH_CHANNEL_ZOMBIE:
 453                         continue;
 454                 case SSH_CHANNEL_LARVAL:
 455                         if (!compat20)
 456                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 457                         continue;
 458                 case SSH_CHANNEL_OPENING:
 459                 case SSH_CHANNEL_OPEN:
 460                 case SSH_CHANNEL_X11_OPEN:
 461                         return 1;
 462                 case SSH_CHANNEL_INPUT_DRAINING:
 463                 case SSH_CHANNEL_OUTPUT_DRAINING:
 464                         if (!compat13)
 465                                 fatal("cannot happen: OUT_DRAIN");
 466                         return 1;
 467                 default:
 468                         fatal("channel_still_open: bad channel type %d", c->type);
 469                         /* NOTREACHED */
 470                 }
 471         }
 472         return 0;
 473 }
 474
 475 /* Returns the id of an open channel suitable for keepaliving */
 476
 477 int
 478 channel_find_open(void)
 479 {
 480         int i;
 481         Channel *c;
 482
 483         for (i = 0; i < channels_alloc; i++) {
 484                 c = channels[i];
 485                 if (c == NULL)
 486                         continue;
 487                 switch (c->type) {
 488                 case SSH_CHANNEL_CLOSED:
 489                 case SSH_CHANNEL_DYNAMIC:
 490                 case SSH_CHANNEL_X11_LISTENER:
 491                 case SSH_CHANNEL_PORT_LISTENER:
 492                 case SSH_CHANNEL_RPORT_LISTENER:
 493                 case SSH_CHANNEL_OPENING:
 494                 case SSH_CHANNEL_CONNECTING:
 495                 case SSH_CHANNEL_ZOMBIE:
 496                         continue;
 497                 case SSH_CHANNEL_LARVAL:
 498                 case SSH_CHANNEL_AUTH_SOCKET:
 499                 case SSH_CHANNEL_OPEN:
 500                 case SSH_CHANNEL_X11_OPEN:
 501                         return i;
 502                 case SSH_CHANNEL_INPUT_DRAINING:
 503                 case SSH_CHANNEL_OUTPUT_DRAINING:
 504                         if (!compat13)
 505                                 fatal("cannot happen: OUT_DRAIN");
 506                         return i;
 507                 default:
 508                         fatal("channel_find_open: bad channel type %d", c->type);
 509                         /* NOTREACHED */
 510                 }
 511         }
 512         return -1;
 513 }
 514
 515
 516 /*
 517  * Returns a message describing the currently open forwarded connections,
 518  * suitable for sending to the client.  The message contains crlf pairs for
 519  * newlines.
 520  */
 521
 522 char *
 523 channel_open_message(void)
 524 {
 525         Buffer buffer;
 526         Channel *c;
 527         char buf[1024], *cp;
 528         int i;
 529
 530         buffer_init(&buffer);
 531         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 532         buffer_append(&buffer, buf, strlen(buf));
 533         for (i = 0; i < channels_alloc; i++) {
 534                 c = channels[i];
 535                 if (c == NULL)
 536                         continue;
 537                 switch (c->type) {
 538                 case SSH_CHANNEL_X11_LISTENER:
 539                 case SSH_CHANNEL_PORT_LISTENER:
 540                 case SSH_CHANNEL_RPORT_LISTENER:
 541                 case SSH_CHANNEL_CLOSED:
 542                 case SSH_CHANNEL_AUTH_SOCKET:
 543                 case SSH_CHANNEL_ZOMBIE:
 544                         continue;
 545                 case SSH_CHANNEL_LARVAL:
 546                 case SSH_CHANNEL_OPENING:
 547                 case SSH_CHANNEL_CONNECTING:
 548                 case SSH_CHANNEL_DYNAMIC:
 549                 case SSH_CHANNEL_OPEN:
 550                 case SSH_CHANNEL_X11_OPEN:
 551                 case SSH_CHANNEL_INPUT_DRAINING:
 552                 case SSH_CHANNEL_OUTPUT_DRAINING:
 553                         snprintf(buf, sizeof buf, "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d)\r\n",
 554                             c->self, c->remote_name,
 555                             c->type, c->remote_id,
 556                             c->istate, buffer_len(&c->input),
 557                             c->ostate, buffer_len(&c->output),
 558                             c->rfd, c->wfd);
 559                         buffer_append(&buffer, buf, strlen(buf));
 560                         continue;
 561                 default:
 562                         fatal("channel_open_message: bad channel type %d", c->type);
 563                         /* NOTREACHED */
 564                 }
 565         }
 566         buffer_append(&buffer, "\0", 1);
 567         cp = xstrdup(buffer_ptr(&buffer));
 568         buffer_free(&buffer);
 569         return cp;
 570 }
 571
 572 void
 573 channel_send_open(int id)
 574 {
 575         Channel *c = channel_lookup(id);
 576
 577         if (c == NULL) {
 578                 logit("channel_send_open: %d: bad id", id);
 579                 return;
 580         }
 581         debug2("channel %d: send open", 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 id, char *service, int wantconfirm)
 592 {
 593         Channel *c = channel_lookup(id);
 594
 595         if (c == NULL) {
 596                 logit("channel_request_start: %d: unknown channel id", id);
 597                 return;
 598         }
 599         debug2("channel %d: request %s", id, service) ;
 600         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 601         packet_put_int(c->remote_id);
 602         packet_put_cstring(service);
 603         packet_put_char(wantconfirm);
 604 }
 605 void
 606 channel_register_confirm(int id, channel_callback_fn *fn)
 607 {
 608         Channel *c = channel_lookup(id);
 609
 610         if (c == NULL) {
 611                 logit("channel_register_comfirm: %d: bad id", id);
 612                 return;
 613         }
 614         c->confirm = fn;
 615 }
 616 void
 617 channel_register_cleanup(int id, channel_callback_fn *fn)
 618 {
 619         Channel *c = channel_lookup(id);
 620
 621         if (c == NULL) {
 622                 logit("channel_register_cleanup: %d: bad id", id);
 623                 return;
 624         }
 625         c->detach_user = fn;
 626 }
 627 void
 628 channel_cancel_cleanup(int id)
 629 {
 630         Channel *c = channel_lookup(id);
 631
 632         if (c == NULL) {
 633                 logit("channel_cancel_cleanup: %d: bad id", id);
 634                 return;
 635         }
 636         c->detach_user = NULL;
 637 }
 638 void
 639 channel_register_filter(int id, channel_filter_fn *fn)
 640 {
 641         Channel *c = channel_lookup(id);
 642
 643         if (c == NULL) {
 644                 logit("channel_register_filter: %d: bad id", id);
 645                 return;
 646         }
 647         c->input_filter = fn;
 648 }
 649
 650 void
 651 channel_set_fds(int id, int rfd, int wfd, int efd,
 652     int extusage, int nonblock, u_int window_max)
 653 {
 654         Channel *c = channel_lookup(id);
 655
 656         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 657                 fatal("channel_activate for non-larval channel %d.", id);
 658         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 659         c->type = SSH_CHANNEL_OPEN;
 660         c->local_window = c->local_window_max = window_max;
 661         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 662         packet_put_int(c->remote_id);
 663         packet_put_int(c->local_window);
 664         packet_send();
 665 }
 666
 667 /*
 668  * 'channel_pre*' are called just before select() to add any bits relevant to
 669  * channels in the select bitmasks.
 670  */
 671 /*
 672  * 'channel_post*': perform any appropriate operations for channels which
 673  * have events pending.
 674  */
 675 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 676 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 677 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 678
 679 static void
 680 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 681 {
 682         FD_SET(c->sock, readset);
 683 }
 684
 685 static void
 686 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 687 {
 688         debug3("channel %d: waiting for connection", c->self);
 689         FD_SET(c->sock, writeset);
 690 }
 691
 692 static void
 693 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 694 {
 695         if (buffer_len(&c->input) < packet_get_maxsize())
 696                 FD_SET(c->sock, readset);
 697         if (buffer_len(&c->output) > 0)
 698                 FD_SET(c->sock, writeset);
 699 }
 700
 701 static void
 702 channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
 703 {
 704         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 705
 706         if (c->istate == CHAN_INPUT_OPEN &&
 707             limit > 0 &&
 708             buffer_len(&c->input) < limit)
 709                 FD_SET(c->rfd, readset);
 710         if (c->ostate == CHAN_OUTPUT_OPEN ||
 711             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 712                 if (buffer_len(&c->output) > 0) {
 713                         FD_SET(c->wfd, writeset);
 714                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 715                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 716                                debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 717                                    c->self, c->efd, buffer_len(&c->extended));
 718                         else
 719                                 chan_obuf_empty(c);
 720                 }
 721         }
 722         /** XXX check close conditions, too */
 723         if (compat20 && c->efd != -1) {
 724                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 725                     buffer_len(&c->extended) > 0)
 726                         FD_SET(c->efd, writeset);
 727                 else if (!(c->flags & CHAN_EOF_SENT) &&
 728                     c->extended_usage == CHAN_EXTENDED_READ &&
 729                     buffer_len(&c->extended) < c->remote_window)
 730                         FD_SET(c->efd, readset);
 731         }
 732 }
 733
 734 static void
 735 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 736 {
 737         if (buffer_len(&c->input) == 0) {
 738                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 739                 packet_put_int(c->remote_id);
 740                 packet_send();
 741                 c->type = SSH_CHANNEL_CLOSED;
 742                 debug2("channel %d: closing after input drain.", c->self);
 743         }
 744 }
 745
 746 static void
 747 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 748 {
 749         if (buffer_len(&c->output) == 0)
 750                 chan_mark_dead(c);
 751         else
 752                 FD_SET(c->sock, writeset);
 753 }
 754
 755 /*
 756  * This is a special state for X11 authentication spoofing.  An opened X11
 757  * connection (when authentication spoofing is being done) remains in this
 758  * state until the first packet has been completely read.  The authentication
 759  * data in that packet is then substituted by the real data if it matches the
 760  * fake data, and the channel is put into normal mode.
 761  * XXX All this happens at the client side.
 762  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 763  */
 764 static int
 765 x11_open_helper(Buffer *b)
 766 {
 767         u_char *ucp;
 768         u_int proto_len, data_len;
 769
 770         /* Check if the fixed size part of the packet is in buffer. */
 771         if (buffer_len(b) < 12)
 772                 return 0;
 773
 774         /* Parse the lengths of variable-length fields. */
 775         ucp = buffer_ptr(b);
 776         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 777                 proto_len = 256 * ucp[6] + ucp[7];
 778                 data_len = 256 * ucp[8] + ucp[9];
 779         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 780                 proto_len = ucp[6] + 256 * ucp[7];
 781                 data_len = ucp[8] + 256 * ucp[9];
 782         } else {
 783                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 784                     ucp[0]);
 785                 return -1;
 786         }
 787
 788         /* Check if the whole packet is in buffer. */
 789         if (buffer_len(b) <
 790             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 791                 return 0;
 792
 793         /* Check if authentication protocol matches. */
 794         if (proto_len != strlen(x11_saved_proto) ||
 795             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 796                 debug2("X11 connection uses different authentication protocol.");
 797                 return -1;
 798         }
 799         /* Check if authentication data matches our fake data. */
 800         if (data_len != x11_fake_data_len ||
 801             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 802                 x11_fake_data, x11_fake_data_len) != 0) {
 803                 debug2("X11 auth data does not match fake data.");
 804                 return -1;
 805         }
 806         /* Check fake data length */
 807         if (x11_fake_data_len != x11_saved_data_len) {
 808                 error("X11 fake_data_len %d != saved_data_len %d",
 809                     x11_fake_data_len, x11_saved_data_len);
 810                 return -1;
 811         }
 812         /*
 813          * Received authentication protocol and data match
 814          * our fake data. Substitute the fake data with real
 815          * data.
 816          */
 817         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 818             x11_saved_data, x11_saved_data_len);
 819         return 1;
 820 }
 821
 822 static void
 823 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 824 {
 825         int ret = x11_open_helper(&c->output);
 826
 827         if (ret == 1) {
 828                 /* Start normal processing for the channel. */
 829                 c->type = SSH_CHANNEL_OPEN;
 830                 channel_pre_open_13(c, readset, writeset);
 831         } else if (ret == -1) {
 832                 /*
 833                  * We have received an X11 connection that has bad
 834                  * authentication information.
 835                  */
 836                 logit("X11 connection rejected because of wrong authentication.");
 837                 buffer_clear(&c->input);
 838                 buffer_clear(&c->output);
 839                 channel_close_fd(&c->sock);
 840                 c->sock = -1;
 841                 c->type = SSH_CHANNEL_CLOSED;
 842                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 843                 packet_put_int(c->remote_id);
 844                 packet_send();
 845         }
 846 }
 847
 848 static void
 849 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
 850 {
 851         int ret = x11_open_helper(&c->output);
 852
 853         /* c->force_drain = 1; */
 854
 855         if (ret == 1) {
 856                 c->type = SSH_CHANNEL_OPEN;
 857                 channel_pre_open(c, readset, writeset);
 858         } else if (ret == -1) {
 859                 logit("X11 connection rejected because of wrong authentication.");
 860                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 861                 chan_read_failed(c);
 862                 buffer_clear(&c->input);
 863                 chan_ibuf_empty(c);
 864                 buffer_clear(&c->output);
 865                 /* for proto v1, the peer will send an IEOF */
 866                 if (compat20)
 867                         chan_write_failed(c);
 868                 else
 869                         c->type = SSH_CHANNEL_OPEN;
 870                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 871         }
 872 }
 873
 874 /* try to decode a socks4 header */
 875 static int
 876 channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
 877 {
 878         char *p, *host;
 879         int len, have, i, found;
 880         char username[256];
 881         struct {
 882                 u_int8_t version;
 883                 u_int8_t command;
 884                 u_int16_t dest_port;
 885                 struct in_addr dest_addr;
 886         } s4_req, s4_rsp;
 887
 888         debug2("channel %d: decode socks4", c->self);
 889
 890         have = buffer_len(&c->input);
 891         len = sizeof(s4_req);
 892         if (have < len)
 893                 return 0;
 894         p = buffer_ptr(&c->input);
 895         for (found = 0, i = len; i < have; i++) {
 896                 if (p[i] == '\0') {
 897                         found = 1;
 898                         break;
 899                 }
 900                 if (i > 1024) {
 901                         /* the peer is probably sending garbage */
 902                         debug("channel %d: decode socks4: too long",
 903                             c->self);
 904                         return -1;
 905                 }
 906         }
 907         if (!found)
 908                 return 0;
 909         buffer_get(&c->input, (char *)&s4_req.version, 1);
 910         buffer_get(&c->input, (char *)&s4_req.command, 1);
 911         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 912         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 913         have = buffer_len(&c->input);
 914         p = buffer_ptr(&c->input);
 915         len = strlen(p);
 916         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 917         if (len > have)
 918                 fatal("channel %d: decode socks4: len %d > have %d",
 919                     c->self, len, have);
 920         strlcpy(username, p, sizeof(username));
 921         buffer_consume(&c->input, len);
 922         buffer_consume(&c->input, 1);           /* trailing '\0' */
 923
 924         host = inet_ntoa(s4_req.dest_addr);
 925         strlcpy(c->path, host, sizeof(c->path));
 926         c->host_port = ntohs(s4_req.dest_port);
 927
 928         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 929             c->self, host, c->host_port, s4_req.command);
 930
 931         if (s4_req.command != 1) {
 932                 debug("channel %d: cannot handle: socks4 cn %d",
 933                     c->self, s4_req.command);
 934                 return -1;
 935         }
 936         s4_rsp.version = 0;                     /* vn: 0 for reply */
 937         s4_rsp.command = 90;                    /* cd: req granted */
 938         s4_rsp.dest_port = 0;                   /* ignored */
 939         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 940         buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
 941         return 1;
 942 }
 943
 944 /* try to decode a socks5 header */
 945 #define SSH_SOCKS5_AUTHDONE     0x1000
 946 #define SSH_SOCKS5_NOAUTH       0x00
 947 #define SSH_SOCKS5_IPV4         0x01
 948 #define SSH_SOCKS5_DOMAIN       0x03
 949 #define SSH_SOCKS5_IPV6         0x04
 950 #define SSH_SOCKS5_CONNECT      0x01
 951 #define SSH_SOCKS5_SUCCESS      0x00
 952
 953 static int
 954 channel_decode_socks5(Channel *c, fd_set * readset, fd_set * writeset)
 955 {
 956         struct {
 957                 u_int8_t version;
 958                 u_int8_t command;
 959                 u_int8_t reserved;
 960                 u_int8_t atyp;
 961         } s5_req, s5_rsp;
 962         u_int16_t dest_port;
 963         u_char *p, dest_addr[255+1];
 964         int i, have, found, nmethods, addrlen, af;
 965
 966         debug2("channel %d: decode socks5", c->self);
 967         p = buffer_ptr(&c->input);
 968         if (p[0] != 0x05)
 969                 return -1;
 970         have = buffer_len(&c->input);
 971         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
 972                 /* format: ver | nmethods | methods */
 973                 if (have < 2)
 974                         return 0;
 975                 nmethods = p[1];
 976                 if (have < nmethods + 2)
 977                         return 0;
 978                 /* look for method: "NO AUTHENTICATION REQUIRED" */
 979                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
 980                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
 981                                 found = 1;
 982                                 break;
 983                         }
 984                 }
 985                 if (!found) {
 986                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
 987                             c->self);
 988                         return -1;
 989                 }
 990                 buffer_consume(&c->input, nmethods + 2);
 991                 buffer_put_char(&c->output, 0x05);              /* version */
 992                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
 993                 FD_SET(c->sock, writeset);
 994                 c->flags |= SSH_SOCKS5_AUTHDONE;
 995                 debug2("channel %d: socks5 auth done", c->self);
 996                 return 0;                               /* need more */
 997         }
 998         debug2("channel %d: socks5 post auth", c->self);
 999         if (have < sizeof(s5_req)+1)
1000                 return 0;                       /* need more */
1001         memcpy((char *)&s5_req, p, sizeof(s5_req));
1002         if (s5_req.version != 0x05 ||
1003             s5_req.command != SSH_SOCKS5_CONNECT ||
1004             s5_req.reserved != 0x00) {
1005                 debug2("channel %d: only socks5 connect supported", c->self);
1006                 return -1;
1007         }
1008         switch(s5_req.atyp){
1009         case SSH_SOCKS5_IPV4:
1010                 addrlen = 4;
1011                 af = AF_INET;
1012                 break;
1013         case SSH_SOCKS5_DOMAIN:
1014                 addrlen = p[sizeof(s5_req)];
1015                 af = -1;
1016                 break;
1017         case SSH_SOCKS5_IPV6:
1018                 addrlen = 16;
1019                 af = AF_INET6;
1020                 break;
1021         default:
1022                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1023                 return -1;
1024         }
1025         if (have < 4 + addrlen + 2)
1026                 return 0;
1027         buffer_consume(&c->input, sizeof(s5_req));
1028         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1029                 buffer_consume(&c->input, 1);    /* host string length */
1030         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1031         buffer_get(&c->input, (char *)&dest_port, 2);
1032         dest_addr[addrlen] = '\0';
1033         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1034                 strlcpy(c->path, dest_addr, sizeof(c->path));
1035         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1036                 return -1;
1037         c->host_port = ntohs(dest_port);
1038
1039         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1040             c->self, c->path, c->host_port, s5_req.command);
1041
1042         s5_rsp.version = 0x05;
1043         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1044         s5_rsp.reserved = 0;                    /* ignored */
1045         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1046         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1047         dest_port = 0;                          /* ignored */
1048
1049         buffer_append(&c->output, (char *)&s5_rsp, sizeof(s5_rsp));
1050         buffer_append(&c->output, (char *)&dest_addr, sizeof(struct in_addr));
1051         buffer_append(&c->output, (char *)&dest_port, sizeof(dest_port));
1052         return 1;
1053 }
1054
1055 /* dynamic port forwarding */
1056 static void
1057 channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
1058 {
1059         u_char *p;
1060         int have, ret;
1061
1062         have = buffer_len(&c->input);
1063         c->delayed = 0;
1064         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1065         /* buffer_dump(&c->input); */
1066         /* check if the fixed size part of the packet is in buffer. */
1067         if (have < 3) {
1068                 /* need more */
1069                 FD_SET(c->sock, readset);
1070                 return;
1071         }
1072         /* try to guess the protocol */
1073         p = buffer_ptr(&c->input);
1074         switch (p[0]) {
1075         case 0x04:
1076                 ret = channel_decode_socks4(c, readset, writeset);
1077                 break;
1078         case 0x05:
1079                 ret = channel_decode_socks5(c, readset, writeset);
1080                 break;
1081         default:
1082                 ret = -1;
1083                 break;
1084         }
1085         if (ret < 0) {
1086                 chan_mark_dead(c);
1087         } else if (ret == 0) {
1088                 debug2("channel %d: pre_dynamic: need more", c->self);
1089                 /* need more */
1090                 FD_SET(c->sock, readset);
1091         } else {
1092                 /* switch to the next state */
1093                 c->type = SSH_CHANNEL_OPENING;
1094                 port_open_helper(c, "direct-tcpip");
1095         }
1096 }
1097
1098 /* This is our fake X11 server socket. */
1099 static void
1100 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
1101 {
1102         Channel *nc;
1103         struct sockaddr addr;
1104         int newsock;
1105         socklen_t addrlen;
1106         char buf[16384], *remote_ipaddr;
1107         int remote_port;
1108
1109         if (FD_ISSET(c->sock, readset)) {
1110                 debug("X11 connection requested.");
1111                 addrlen = sizeof(addr);
1112                 newsock = accept(c->sock, &addr, &addrlen);
1113                 if (c->single_connection) {
1114                         debug2("single_connection: closing X11 listener.");
1115                         channel_close_fd(&c->sock);
1116                         chan_mark_dead(c);
1117                 }
1118                 if (newsock < 0) {
1119                         error("accept: %.100s", strerror(errno));
1120                         return;
1121                 }
1122                 set_nodelay(newsock);
1123                 remote_ipaddr = get_peer_ipaddr(newsock);
1124                 remote_port = get_peer_port(newsock);
1125                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1126                     remote_ipaddr, remote_port);
1127
1128                 nc = channel_new("accepted x11 socket",
1129                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1130                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1131                 if (compat20) {
1132                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1133                         packet_put_cstring("x11");
1134                         packet_put_int(nc->self);
1135                         packet_put_int(nc->local_window_max);
1136                         packet_put_int(nc->local_maxpacket);
1137                         /* originator ipaddr and port */
1138                         packet_put_cstring(remote_ipaddr);
1139                         if (datafellows & SSH_BUG_X11FWD) {
1140                                 debug2("ssh2 x11 bug compat mode");
1141                         } else {
1142                                 packet_put_int(remote_port);
1143                         }
1144                         packet_send();
1145                 } else {
1146                         packet_start(SSH_SMSG_X11_OPEN);
1147                         packet_put_int(nc->self);
1148                         if (packet_get_protocol_flags() &
1149                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1150                                 packet_put_cstring(buf);
1151                         packet_send();
1152                 }
1153                 xfree(remote_ipaddr);
1154         }
1155 }
1156
1157 static void
1158 port_open_helper(Channel *c, char *rtype)
1159 {
1160         int direct;
1161         char buf[1024];
1162         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1163         u_short remote_port = get_peer_port(c->sock);
1164
1165         direct = (strcmp(rtype, "direct-tcpip") == 0);
1166
1167         snprintf(buf, sizeof buf,
1168             "%s: listening port %d for %.100s port %d, "
1169             "connect from %.200s port %d",
1170             rtype, c->listening_port, c->path, c->host_port,
1171             remote_ipaddr, remote_port);
1172
1173         xfree(c->remote_name);
1174         c->remote_name = xstrdup(buf);
1175
1176         if (compat20) {
1177                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1178                 packet_put_cstring(rtype);
1179                 packet_put_int(c->self);
1180                 packet_put_int(c->local_window_max);
1181                 packet_put_int(c->local_maxpacket);
1182                 if (direct) {
1183                         /* target host, port */
1184                         packet_put_cstring(c->path);
1185                         packet_put_int(c->host_port);
1186                 } else {
1187                         /* listen address, port */
1188                         packet_put_cstring(c->path);
1189                         packet_put_int(c->listening_port);
1190                 }
1191                 /* originator host and port */
1192                 packet_put_cstring(remote_ipaddr);
1193                 packet_put_int(remote_port);
1194                 packet_send();
1195         } else {
1196                 packet_start(SSH_MSG_PORT_OPEN);
1197                 packet_put_int(c->self);
1198                 packet_put_cstring(c->path);
1199                 packet_put_int(c->host_port);
1200                 if (packet_get_protocol_flags() &
1201                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1202                         packet_put_cstring(c->remote_name);
1203                 packet_send();
1204         }
1205         xfree(remote_ipaddr);
1206 }
1207
1208 /*
1209  * This socket is listening for connections to a forwarded TCP/IP port.
1210  */
1211 static void
1212 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
1213 {
1214         Channel *nc;
1215         struct sockaddr addr;
1216         int newsock, nextstate;
1217         socklen_t addrlen;
1218         char *rtype;
1219
1220         if (FD_ISSET(c->sock, readset)) {
1221                 debug("Connection to port %d forwarding "
1222                     "to %.100s port %d requested.",
1223                     c->listening_port, c->path, c->host_port);
1224
1225                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1226                         nextstate = SSH_CHANNEL_OPENING;
1227                         rtype = "forwarded-tcpip";
1228                 } else {
1229                         if (c->host_port == 0) {
1230                                 nextstate = SSH_CHANNEL_DYNAMIC;
1231                                 rtype = "dynamic-tcpip";
1232                         } else {
1233                                 nextstate = SSH_CHANNEL_OPENING;
1234                                 rtype = "direct-tcpip";
1235                         }
1236                 }
1237
1238                 addrlen = sizeof(addr);
1239                 newsock = accept(c->sock, &addr, &addrlen);
1240                 if (newsock < 0) {
1241                         error("accept: %.100s", strerror(errno));
1242                         return;
1243                 }
1244                 set_nodelay(newsock);
1245                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1246                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1247                 nc->listening_port = c->listening_port;
1248                 nc->host_port = c->host_port;
1249                 strlcpy(nc->path, c->path, sizeof(nc->path));
1250
1251                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1252                         /*
1253                          * do not call the channel_post handler until
1254                          * this flag has been reset by a pre-handler.
1255                          * otherwise the FD_ISSET calls might overflow
1256                          */
1257                         nc->delayed = 1;
1258                 } else {
1259                         port_open_helper(nc, rtype);
1260                 }
1261         }
1262 }
1263
1264 /*
1265  * This is the authentication agent socket listening for connections from
1266  * clients.
1267  */
1268 static void
1269 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
1270 {
1271         Channel *nc;
1272         int newsock;
1273         struct sockaddr addr;
1274         socklen_t addrlen;
1275
1276         if (FD_ISSET(c->sock, readset)) {
1277                 addrlen = sizeof(addr);
1278                 newsock = accept(c->sock, &addr, &addrlen);
1279                 if (newsock < 0) {
1280                         error("accept from auth socket: %.100s", strerror(errno));
1281                         return;
1282                 }
1283                 nc = channel_new("accepted auth socket",
1284                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1285                     c->local_window_max, c->local_maxpacket,
1286                     0, "accepted auth socket", 1);
1287                 if (compat20) {
1288                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1289                         packet_put_cstring("auth-agent@openssh.com");
1290                         packet_put_int(nc->self);
1291                         packet_put_int(c->local_window_max);
1292                         packet_put_int(c->local_maxpacket);
1293                 } else {
1294                         packet_start(SSH_SMSG_AGENT_OPEN);
1295                         packet_put_int(nc->self);
1296                 }
1297                 packet_send();
1298         }
1299 }
1300
1301 static void
1302 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
1303 {
1304         int err = 0;
1305         socklen_t sz = sizeof(err);
1306
1307         if (FD_ISSET(c->sock, writeset)) {
1308                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1309                         err = errno;
1310                         error("getsockopt SO_ERROR failed");
1311                 }
1312                 if (err == 0) {
1313                         debug("channel %d: connected", c->self);
1314                         c->type = SSH_CHANNEL_OPEN;
1315                         if (compat20) {
1316                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1317                                 packet_put_int(c->remote_id);
1318                                 packet_put_int(c->self);
1319                                 packet_put_int(c->local_window);
1320                                 packet_put_int(c->local_maxpacket);
1321                         } else {
1322                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1323                                 packet_put_int(c->remote_id);
1324                                 packet_put_int(c->self);
1325                         }
1326                 } else {
1327                         debug("channel %d: not connected: %s",
1328                             c->self, strerror(err));
1329                         if (compat20) {
1330                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1331                                 packet_put_int(c->remote_id);
1332                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1333                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1334                                         packet_put_cstring(strerror(err));
1335                                         packet_put_cstring("");
1336                                 }
1337                         } else {
1338                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1339                                 packet_put_int(c->remote_id);
1340                         }
1341                         chan_mark_dead(c);
1342                 }
1343                 packet_send();
1344         }
1345 }
1346
1347 static int
1348 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
1349 {
1350         char buf[16*1024];
1351         int len;
1352
1353         if (c->rfd != -1 &&
1354             FD_ISSET(c->rfd, readset)) {
1355                 len = read(c->rfd, buf, sizeof(buf));
1356                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1357                         return 1;
1358                 if (len <= 0) {
1359                         debug2("channel %d: read<=0 rfd %d len %d",
1360                             c->self, c->rfd, len);
1361                         if (c->type != SSH_CHANNEL_OPEN) {
1362                                 debug2("channel %d: not open", c->self);
1363                                 chan_mark_dead(c);
1364                                 return -1;
1365                         } else if (compat13) {
1366                                 buffer_clear(&c->output);
1367                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1368                                 debug2("channel %d: input draining.", c->self);
1369                         } else {
1370                                 chan_read_failed(c);
1371                         }
1372                         return -1;
1373                 }
1374                 if (c->input_filter != NULL) {
1375                         if (c->input_filter(c, buf, len) == -1) {
1376                                 debug2("channel %d: filter stops", c->self);
1377                                 chan_read_failed(c);
1378                         }
1379                 } else {
1380                         buffer_append(&c->input, buf, len);
1381                 }
1382         }
1383         return 1;
1384 }
1385 static int
1386 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
1387 {
1388         struct termios tio;
1389         u_char *data;
1390         u_int dlen;
1391         int len;
1392
1393         /* Send buffered output data to the socket. */
1394         if (c->wfd != -1 &&
1395             FD_ISSET(c->wfd, writeset) &&
1396             buffer_len(&c->output) > 0) {
1397                 data = buffer_ptr(&c->output);
1398                 dlen = buffer_len(&c->output);
1399 #ifdef _AIX
1400                 /* XXX: Later AIX versions can't push as much data to tty */
1401                 if (compat20 && c->wfd_isatty)
1402                         dlen = MIN(dlen, 8*1024);
1403 #endif
1404                 len = write(c->wfd, data, dlen);
1405                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1406                         return 1;
1407                 if (len <= 0) {
1408                         if (c->type != SSH_CHANNEL_OPEN) {
1409                                 debug2("channel %d: not open", c->self);
1410                                 chan_mark_dead(c);
1411                                 return -1;
1412                         } else if (compat13) {
1413                                 buffer_clear(&c->output);
1414                                 debug2("channel %d: input draining.", c->self);
1415                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1416                         } else {
1417                                 chan_write_failed(c);
1418                         }
1419                         return -1;
1420                 }
1421                 if (compat20 && c->isatty && dlen >= 1 && data[0] != '\r') {
1422                         if (tcgetattr(c->wfd, &tio) == 0 &&
1423                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1424                                 /*
1425                                  * Simulate echo to reduce the impact of
1426                                  * traffic analysis. We need to match the
1427                                  * size of a SSH2_MSG_CHANNEL_DATA message
1428                                  * (4 byte channel id + data)
1429                                  */
1430                                 packet_send_ignore(4 + len);
1431                                 packet_send();
1432                         }
1433                 }
1434                 buffer_consume(&c->output, len);
1435                 if (compat20 && len > 0) {
1436                         c->local_consumed += len;
1437                 }
1438         }
1439         return 1;
1440 }
1441 static int
1442 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
1443 {
1444         char buf[16*1024];
1445         int len;
1446
1447 /** XXX handle drain efd, too */
1448         if (c->efd != -1) {
1449                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1450                     FD_ISSET(c->efd, writeset) &&
1451                     buffer_len(&c->extended) > 0) {
1452                         len = write(c->efd, buffer_ptr(&c->extended),
1453                             buffer_len(&c->extended));
1454                         debug2("channel %d: written %d to efd %d",
1455                             c->self, len, c->efd);
1456                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1457                                 return 1;
1458                         if (len <= 0) {
1459                                 debug2("channel %d: closing write-efd %d",
1460                                     c->self, c->efd);
1461                                 channel_close_fd(&c->efd);
1462                         } else {
1463                                 buffer_consume(&c->extended, len);
1464                                 c->local_consumed += len;
1465                         }
1466                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1467                     FD_ISSET(c->efd, readset)) {
1468                         len = read(c->efd, buf, sizeof(buf));
1469                         debug2("channel %d: read %d from efd %d",
1470                             c->self, len, c->efd);
1471                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1472                                 return 1;
1473                         if (len <= 0) {
1474                                 debug2("channel %d: closing read-efd %d",
1475                                     c->self, c->efd);
1476                                 channel_close_fd(&c->efd);
1477                         } else {
1478                                 buffer_append(&c->extended, buf, len);
1479                         }
1480                 }
1481         }
1482         return 1;
1483 }
1484 static int
1485 channel_check_window(Channel *c)
1486 {
1487         if (c->type == SSH_CHANNEL_OPEN &&
1488             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1489             c->local_window < c->local_window_max/2 &&
1490             c->local_consumed > 0) {
1491                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1492                 packet_put_int(c->remote_id);
1493                 packet_put_int(c->local_consumed);
1494                 packet_send();
1495                 debug2("channel %d: window %d sent adjust %d",
1496                     c->self, c->local_window,
1497                     c->local_consumed);
1498                 c->local_window += c->local_consumed;
1499                 c->local_consumed = 0;
1500         }
1501         return 1;
1502 }
1503
1504 static void
1505 channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
1506 {
1507         if (c->delayed)
1508                 return;
1509         channel_handle_rfd(c, readset, writeset);
1510         channel_handle_wfd(c, readset, writeset);
1511         if (!compat20)
1512                 return;
1513         channel_handle_efd(c, readset, writeset);
1514         channel_check_window(c);
1515 }
1516
1517 static void
1518 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
1519 {
1520         int len;
1521
1522         /* Send buffered output data to the socket. */
1523         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1524                 len = write(c->sock, buffer_ptr(&c->output),
1525                             buffer_len(&c->output));
1526                 if (len <= 0)
1527                         buffer_clear(&c->output);
1528                 else
1529                         buffer_consume(&c->output, len);
1530         }
1531 }
1532
1533 static void
1534 channel_handler_init_20(void)
1535 {
1536         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1537         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1538         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1539         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1540         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1541         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1542         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1543         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1544
1545         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1546         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1547         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1548         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1549         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1550         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1551         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1552 }
1553
1554 static void
1555 channel_handler_init_13(void)
1556 {
1557         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1558         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1559         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1560         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1561         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1562         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1563         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1564         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1565         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1566
1567         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1568         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1569         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1570         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1571         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1572         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1573         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1574 }
1575
1576 static void
1577 channel_handler_init_15(void)
1578 {
1579         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1580         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1581         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1582         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1583         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1584         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1585         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1586
1587         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1588         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1589         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1590         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1591         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1592         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1593 }
1594
1595 static void
1596 channel_handler_init(void)
1597 {
1598         int i;
1599
1600         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1601                 channel_pre[i] = NULL;
1602                 channel_post[i] = NULL;
1603         }
1604         if (compat20)
1605                 channel_handler_init_20();
1606         else if (compat13)
1607                 channel_handler_init_13();
1608         else
1609                 channel_handler_init_15();
1610 }
1611
1612 /* gc dead channels */
1613 static void
1614 channel_garbage_collect(Channel *c)
1615 {
1616         if (c == NULL)
1617                 return;
1618         if (c->detach_user != NULL) {
1619                 if (!chan_is_dead(c, 0))
1620                         return;
1621                 debug2("channel %d: gc: notify user", c->self);
1622                 c->detach_user(c->self, NULL);
1623                 /* if we still have a callback */
1624                 if (c->detach_user != NULL)
1625                         return;
1626                 debug2("channel %d: gc: user detached", c->self);
1627         }
1628         if (!chan_is_dead(c, 1))
1629                 return;
1630         debug2("channel %d: garbage collecting", c->self);
1631         channel_free(c);
1632 }
1633
1634 static void
1635 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
1636 {
1637         static int did_init = 0;
1638         int i;
1639         Channel *c;
1640
1641         if (!did_init) {
1642                 channel_handler_init();
1643                 did_init = 1;
1644         }
1645         for (i = 0; i < channels_alloc; i++) {
1646                 c = channels[i];
1647                 if (c == NULL)
1648                         continue;
1649                 if (ftab[c->type] != NULL)
1650                         (*ftab[c->type])(c, readset, writeset);
1651                 channel_garbage_collect(c);
1652         }
1653 }
1654
1655 /*
1656  * Allocate/update select bitmasks and add any bits relevant to channels in
1657  * select bitmasks.
1658  */
1659 void
1660 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1661     int *nallocp, int rekeying)
1662 {
1663         int n;
1664         u_int sz;
1665
1666         n = MAX(*maxfdp, channel_max_fd);
1667
1668         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
1669         /* perhaps check sz < nalloc/2 and shrink? */
1670         if (*readsetp == NULL || sz > *nallocp) {
1671                 *readsetp = xrealloc(*readsetp, sz);
1672                 *writesetp = xrealloc(*writesetp, sz);
1673                 *nallocp = sz;
1674         }
1675         *maxfdp = n;
1676         memset(*readsetp, 0, sz);
1677         memset(*writesetp, 0, sz);
1678
1679         if (!rekeying)
1680                 channel_handler(channel_pre, *readsetp, *writesetp);
1681 }
1682
1683 /*
1684  * After select, perform any appropriate operations for channels which have
1685  * events pending.
1686  */
1687 void
1688 channel_after_select(fd_set * readset, fd_set * writeset)
1689 {
1690         channel_handler(channel_post, readset, writeset);
1691 }
1692
1693
1694 /* If there is data to send to the connection, enqueue some of it now. */
1695
1696 void
1697 channel_output_poll(void)
1698 {
1699         Channel *c;
1700         int i;
1701         u_int len;
1702
1703         for (i = 0; i < channels_alloc; i++) {
1704                 c = channels[i];
1705                 if (c == NULL)
1706                         continue;
1707
1708                 /*
1709                  * We are only interested in channels that can have buffered
1710                  * incoming data.
1711                  */
1712                 if (compat13) {
1713                         if (c->type != SSH_CHANNEL_OPEN &&
1714                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1715                                 continue;
1716                 } else {
1717                         if (c->type != SSH_CHANNEL_OPEN)
1718                                 continue;
1719                 }
1720                 if (compat20 &&
1721                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1722                         /* XXX is this true? */
1723                         debug3("channel %d: will not send data after close", c->self);
1724                         continue;
1725                 }
1726
1727                 /* Get the amount of buffered data for this channel. */
1728                 if ((c->istate == CHAN_INPUT_OPEN ||
1729                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1730                     (len = buffer_len(&c->input)) > 0) {
1731                         /*
1732                          * Send some data for the other side over the secure
1733                          * connection.
1734                          */
1735                         if (compat20) {
1736                                 if (len > c->remote_window)
1737                                         len = c->remote_window;
1738                                 if (len > c->remote_maxpacket)
1739                                         len = c->remote_maxpacket;
1740                         } else {
1741                                 if (packet_is_interactive()) {
1742                                         if (len > 1024)
1743                                                 len = 512;
1744                                 } else {
1745                                         /* Keep the packets at reasonable size. */
1746                                         if (len > packet_get_maxsize()/2)
1747                                                 len = packet_get_maxsize()/2;
1748                                 }
1749                         }
1750                         if (len > 0) {
1751                                 packet_start(compat20 ?
1752                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1753                                 packet_put_int(c->remote_id);
1754                                 packet_put_string(buffer_ptr(&c->input), len);
1755                                 packet_send();
1756                                 buffer_consume(&c->input, len);
1757                                 c->remote_window -= len;
1758                         }
1759                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1760                         if (compat13)
1761                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1762                         /*
1763                          * input-buffer is empty and read-socket shutdown:
1764                          * tell peer, that we will not send more data: send IEOF.
1765                          * hack for extended data: delay EOF if EFD still in use.
1766                          */
1767                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1768                                debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1769                                    c->self, c->efd, buffer_len(&c->extended));
1770                         else
1771                                 chan_ibuf_empty(c);
1772                 }
1773                 /* Send extended data, i.e. stderr */
1774                 if (compat20 &&
1775                     !(c->flags & CHAN_EOF_SENT) &&
1776                     c->remote_window > 0 &&
1777                     (len = buffer_len(&c->extended)) > 0 &&
1778                     c->extended_usage == CHAN_EXTENDED_READ) {
1779                         debug2("channel %d: rwin %u elen %u euse %d",
1780                             c->self, c->remote_window, buffer_len(&c->extended),
1781                             c->extended_usage);
1782                         if (len > c->remote_window)
1783                                 len = c->remote_window;
1784                         if (len > c->remote_maxpacket)
1785                                 len = c->remote_maxpacket;
1786                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1787                         packet_put_int(c->remote_id);
1788                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1789                         packet_put_string(buffer_ptr(&c->extended), len);
1790                         packet_send();
1791                         buffer_consume(&c->extended, len);
1792                         c->remote_window -= len;
1793                         debug2("channel %d: sent ext data %d", c->self, len);
1794                 }
1795         }
1796 }
1797
1798
1799 /* -- protocol input */
1800
1801 void
1802 channel_input_data(int type, u_int32_t seq, void *ctxt)
1803 {
1804         int id;
1805         char *data;
1806         u_int data_len;
1807         Channel *c;
1808
1809         /* Get the channel number and verify it. */
1810         id = packet_get_int();
1811         c = channel_lookup(id);
1812         if (c == NULL)
1813                 packet_disconnect("Received data for nonexistent channel %d.", id);
1814
1815         /* Ignore any data for non-open channels (might happen on close) */
1816         if (c->type != SSH_CHANNEL_OPEN &&
1817             c->type != SSH_CHANNEL_X11_OPEN)
1818                 return;
1819
1820         /* Get the data. */
1821         data = packet_get_string(&data_len);
1822
1823         /*
1824          * Ignore data for protocol > 1.3 if output end is no longer open.
1825          * For protocol 2 the sending side is reducing its window as it sends
1826          * data, so we must 'fake' consumption of the data in order to ensure
1827          * that window updates are sent back.  Otherwise the connection might
1828          * deadlock.
1829          */
1830         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1831                 if (compat20) {
1832                         c->local_window -= data_len;
1833                         c->local_consumed += data_len;
1834                 }
1835                 xfree(data);
1836                 return;
1837         }
1838
1839         if (compat20) {
1840                 if (data_len > c->local_maxpacket) {
1841                         logit("channel %d: rcvd big packet %d, maxpack %d",
1842                             c->self, data_len, c->local_maxpacket);
1843                 }
1844                 if (data_len > c->local_window) {
1845                         logit("channel %d: rcvd too much data %d, win %d",
1846                             c->self, data_len, c->local_window);
1847                         xfree(data);
1848                         return;
1849                 }
1850                 c->local_window -= data_len;
1851         }
1852         packet_check_eom();
1853         buffer_append(&c->output, data, data_len);
1854         xfree(data);
1855 }
1856
1857 void
1858 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
1859 {
1860         int id;
1861         char *data;
1862         u_int data_len, tcode;
1863         Channel *c;
1864
1865         /* Get the channel number and verify it. */
1866         id = packet_get_int();
1867         c = channel_lookup(id);
1868
1869         if (c == NULL)
1870                 packet_disconnect("Received extended_data for bad channel %d.", id);
1871         if (c->type != SSH_CHANNEL_OPEN) {
1872                 logit("channel %d: ext data for non open", id);
1873                 return;
1874         }
1875         if (c->flags & CHAN_EOF_RCVD) {
1876                 if (datafellows & SSH_BUG_EXTEOF)
1877                         debug("channel %d: accepting ext data after eof", id);
1878                 else
1879                         packet_disconnect("Received extended_data after EOF "
1880                             "on channel %d.", id);
1881         }
1882         tcode = packet_get_int();
1883         if (c->efd == -1 ||
1884             c->extended_usage != CHAN_EXTENDED_WRITE ||
1885             tcode != SSH2_EXTENDED_DATA_STDERR) {
1886                 logit("channel %d: bad ext data", c->self);
1887                 return;
1888         }
1889         data = packet_get_string(&data_len);
1890         packet_check_eom();
1891         if (data_len > c->local_window) {
1892                 logit("channel %d: rcvd too much extended_data %d, win %d",
1893                     c->self, data_len, c->local_window);
1894                 xfree(data);
1895                 return;
1896         }
1897         debug2("channel %d: rcvd ext data %d", c->self, data_len);
1898         c->local_window -= data_len;
1899         buffer_append(&c->extended, data, data_len);
1900         xfree(data);
1901 }
1902
1903 void
1904 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
1905 {
1906         int id;
1907         Channel *c;
1908
1909         id = packet_get_int();
1910         packet_check_eom();
1911         c = channel_lookup(id);
1912         if (c == NULL)
1913                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
1914         chan_rcvd_ieof(c);
1915
1916         /* XXX force input close */
1917         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
1918                 debug("channel %d: FORCE input drain", c->self);
1919                 c->istate = CHAN_INPUT_WAIT_DRAIN;
1920                 if (buffer_len(&c->input) == 0)
1921                         chan_ibuf_empty(c);
1922         }
1923
1924 }
1925
1926 void
1927 channel_input_close(int type, u_int32_t seq, void *ctxt)
1928 {
1929         int id;
1930         Channel *c;
1931
1932         id = packet_get_int();
1933         packet_check_eom();
1934         c = channel_lookup(id);
1935         if (c == NULL)
1936                 packet_disconnect("Received close for nonexistent channel %d.", id);
1937
1938         /*
1939          * Send a confirmation that we have closed the channel and no more
1940          * data is coming for it.
1941          */
1942         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
1943         packet_put_int(c->remote_id);
1944         packet_send();
1945
1946         /*
1947          * If the channel is in closed state, we have sent a close request,
1948          * and the other side will eventually respond with a confirmation.
1949          * Thus, we cannot free the channel here, because then there would be
1950          * no-one to receive the confirmation.  The channel gets freed when
1951          * the confirmation arrives.
1952          */
1953         if (c->type != SSH_CHANNEL_CLOSED) {
1954                 /*
1955                  * Not a closed channel - mark it as draining, which will
1956                  * cause it to be freed later.
1957                  */
1958                 buffer_clear(&c->input);
1959                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
1960         }
1961 }
1962
1963 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
1964 void
1965 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
1966 {
1967         int id = packet_get_int();
1968         Channel *c = channel_lookup(id);
1969
1970         packet_check_eom();
1971         if (c == NULL)
1972                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
1973         chan_rcvd_oclose(c);
1974 }
1975
1976 void
1977 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
1978 {
1979         int id = packet_get_int();
1980         Channel *c = channel_lookup(id);
1981
1982         packet_check_eom();
1983         if (c == NULL)
1984                 packet_disconnect("Received close confirmation for "
1985                     "out-of-range channel %d.", id);
1986         if (c->type != SSH_CHANNEL_CLOSED)
1987                 packet_disconnect("Received close confirmation for "
1988                     "non-closed channel %d (type %d).", id, c->type);
1989         channel_free(c);
1990 }
1991
1992 void
1993 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
1994 {
1995         int id, remote_id;
1996         Channel *c;
1997
1998         id = packet_get_int();
1999         c = channel_lookup(id);
2000
2001         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2002                 packet_disconnect("Received open confirmation for "
2003                     "non-opening channel %d.", id);
2004         remote_id = packet_get_int();
2005         /* Record the remote channel number and mark that the channel is now open. */
2006         c->remote_id = remote_id;
2007         c->type = SSH_CHANNEL_OPEN;
2008
2009         if (compat20) {
2010                 c->remote_window = packet_get_int();
2011                 c->remote_maxpacket = packet_get_int();
2012                 if (c->confirm) {
2013                         debug2("callback start");
2014                         c->confirm(c->self, NULL);
2015                         debug2("callback done");
2016                 }
2017                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2018                     c->remote_window, c->remote_maxpacket);
2019         }
2020         packet_check_eom();
2021 }
2022
2023 static char *
2024 reason2txt(int reason)
2025 {
2026         switch (reason) {
2027         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2028                 return "administratively prohibited";
2029         case SSH2_OPEN_CONNECT_FAILED:
2030                 return "connect failed";
2031         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2032                 return "unknown channel type";
2033         case SSH2_OPEN_RESOURCE_SHORTAGE:
2034                 return "resource shortage";
2035         }
2036         return "unknown reason";
2037 }
2038
2039 void
2040 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2041 {
2042         int id, reason;
2043         char *msg = NULL, *lang = NULL;
2044         Channel *c;
2045
2046         id = packet_get_int();
2047         c = channel_lookup(id);
2048
2049         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2050                 packet_disconnect("Received open failure for "
2051                     "non-opening channel %d.", id);
2052         if (compat20) {
2053                 reason = packet_get_int();
2054                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2055                         msg  = packet_get_string(NULL);
2056                         lang = packet_get_string(NULL);
2057                 }
2058                 logit("channel %d: open failed: %s%s%s", id,
2059                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2060                 if (msg != NULL)
2061                         xfree(msg);
2062                 if (lang != NULL)
2063                         xfree(lang);
2064         }
2065         packet_check_eom();
2066         /* Free the channel.  This will also close the socket. */
2067         channel_free(c);
2068 }
2069
2070 void
2071 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2072 {
2073         Channel *c;
2074         int id;
2075         u_int adjust;
2076
2077         if (!compat20)
2078                 return;
2079
2080         /* Get the channel number and verify it. */
2081         id = packet_get_int();
2082         c = channel_lookup(id);
2083
2084         if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
2085                 logit("Received window adjust for "
2086                     "non-open channel %d.", id);
2087                 return;
2088         }
2089         adjust = packet_get_int();
2090         packet_check_eom();
2091         debug2("channel %d: rcvd adjust %u", id, adjust);
2092         c->remote_window += adjust;
2093 }
2094
2095 void
2096 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2097 {
2098         Channel *c = NULL;
2099         u_short host_port;
2100         char *host, *originator_string;
2101         int remote_id, sock = -1;
2102
2103         remote_id = packet_get_int();
2104         host = packet_get_string(NULL);
2105         host_port = packet_get_int();
2106
2107         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2108                 originator_string = packet_get_string(NULL);
2109         } else {
2110                 originator_string = xstrdup("unknown (remote did not supply name)");
2111         }
2112         packet_check_eom();
2113         sock = channel_connect_to(host, host_port);
2114         if (sock != -1) {
2115                 c = channel_new("connected socket",
2116                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2117                     originator_string, 1);
2118                 c->remote_id = remote_id;
2119         }
2120         xfree(originator_string);
2121         if (c == NULL) {
2122                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2123                 packet_put_int(remote_id);
2124                 packet_send();
2125         }
2126         xfree(host);
2127 }
2128
2129
2130 /* -- tcp forwarding */
2131
2132 void
2133 channel_set_af(int af)
2134 {
2135         IPv4or6 = af;
2136 }
2137
2138 static int
2139 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2140     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2141 {
2142         Channel *c;
2143         int success, sock, on = 1;
2144         struct addrinfo hints, *ai, *aitop;
2145         const char *host;
2146         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2147
2148         success = 0;
2149         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2150             listen_addr : host_to_connect;
2151
2152         if (host == NULL) {
2153                 error("No forward host name.");
2154                 return success;
2155         }
2156         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2157                 error("Forward host name too long.");
2158                 return success;
2159         }
2160
2161         /*
2162          * getaddrinfo returns a loopback address if the hostname is
2163          * set to NULL and hints.ai_flags is not AI_PASSIVE
2164          */
2165         memset(&hints, 0, sizeof(hints));
2166         hints.ai_family = IPv4or6;
2167         hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
2168         hints.ai_socktype = SOCK_STREAM;
2169         snprintf(strport, sizeof strport, "%d", listen_port);
2170         if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
2171                 packet_disconnect("getaddrinfo: fatal error");
2172
2173         for (ai = aitop; ai; ai = ai->ai_next) {
2174                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2175                         continue;
2176                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2177                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2178                         error("channel_setup_fwd_listener: getnameinfo failed");
2179                         continue;
2180                 }
2181                 /* Create a port to listen for the host. */
2182                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2183                 if (sock < 0) {
2184                         /* this is no error since kernel may not support ipv6 */
2185                         verbose("socket: %.100s", strerror(errno));
2186                         continue;
2187                 }
2188                 /*
2189                  * Set socket options.
2190                  * Allow local port reuse in TIME_WAIT.
2191                  */
2192                 if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on,
2193                     sizeof(on)) == -1)
2194                         error("setsockopt SO_REUSEADDR: %s", strerror(errno));
2195
2196                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2197
2198                 /* Bind the socket to the address. */
2199                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2200                         /* address can be in use ipv6 address is already bound */
2201                         if (!ai->ai_next)
2202                                 error("bind: %.100s", strerror(errno));
2203                         else
2204                                 verbose("bind: %.100s", strerror(errno));
2205
2206                         close(sock);
2207                         continue;
2208                 }
2209                 /* Start listening for connections on the socket. */
2210                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2211                         error("listen: %.100s", strerror(errno));
2212                         close(sock);
2213                         continue;
2214                 }
2215                 /* Allocate a channel number for the socket. */
2216                 c = channel_new("port listener", type, sock, sock, -1,
2217                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2218                     0, "port listener", 1);
2219                 strlcpy(c->path, host, sizeof(c->path));
2220                 c->host_port = port_to_connect;
2221                 c->listening_port = listen_port;
2222                 success = 1;
2223         }
2224         if (success == 0)
2225                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2226                     listen_port);
2227         freeaddrinfo(aitop);
2228         return success;
2229 }
2230
2231 /* protocol local port fwd, used by ssh (and sshd in v1) */
2232 int
2233 channel_setup_local_fwd_listener(u_short listen_port,
2234     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2235 {
2236         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2237             NULL, listen_port, host_to_connect, port_to_connect, gateway_ports);
2238 }
2239
2240 /* protocol v2 remote port fwd, used by sshd */
2241 int
2242 channel_setup_remote_fwd_listener(const char *listen_address,
2243     u_short listen_port, int gateway_ports)
2244 {
2245         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2246             listen_address, listen_port, NULL, 0, gateway_ports);
2247 }
2248
2249 /*
2250  * Initiate forwarding of connections to port "port" on remote host through
2251  * the secure channel to host:port from local side.
2252  */
2253
2254 void
2255 channel_request_remote_forwarding(u_short listen_port,
2256     const char *host_to_connect, u_short port_to_connect)
2257 {
2258         int type, success = 0;
2259
2260         /* Record locally that connection to this host/port is permitted. */
2261         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2262                 fatal("channel_request_remote_forwarding: too many forwards");
2263
2264         /* Send the forward request to the remote side. */
2265         if (compat20) {
2266                 const char *address_to_bind = "0.0.0.0";
2267                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2268                 packet_put_cstring("tcpip-forward");
2269                 packet_put_char(1);                     /* boolean: want reply */
2270                 packet_put_cstring(address_to_bind);
2271                 packet_put_int(listen_port);
2272                 packet_send();
2273                 packet_write_wait();
2274                 /* Assume that server accepts the request */
2275                 success = 1;
2276         } else {
2277                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2278                 packet_put_int(listen_port);
2279                 packet_put_cstring(host_to_connect);
2280                 packet_put_int(port_to_connect);
2281                 packet_send();
2282                 packet_write_wait();
2283
2284                 /* Wait for response from the remote side. */
2285                 type = packet_read();
2286                 switch (type) {
2287                 case SSH_SMSG_SUCCESS:
2288                         success = 1;
2289                         break;
2290                 case SSH_SMSG_FAILURE:
2291                         logit("Warning: Server denied remote port forwarding.");
2292                         break;
2293                 default:
2294                         /* Unknown packet */
2295                         packet_disconnect("Protocol error for port forward request:"
2296                             "received packet type %d.", type);
2297                 }
2298         }
2299         if (success) {
2300                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2301                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2302                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2303                 num_permitted_opens++;
2304         }
2305 }
2306
2307 /*
2308  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2309  * listening for the port, and sends back a success reply (or disconnect
2310  * message if there was an error).  This never returns if there was an error.
2311  */
2312
2313 void
2314 channel_input_port_forward_request(int is_root, int gateway_ports)
2315 {
2316         u_short port, host_port;
2317         char *hostname;
2318
2319         /* Get arguments from the packet. */
2320         port = packet_get_int();
2321         hostname = packet_get_string(NULL);
2322         host_port = packet_get_int();
2323
2324 #ifndef HAVE_CYGWIN
2325         /*
2326          * Check that an unprivileged user is not trying to forward a
2327          * privileged port.
2328          */
2329         if (port < IPPORT_RESERVED && !is_root)
2330                 packet_disconnect(
2331                     "Requested forwarding of port %d but user is not root.",
2332                     port);
2333         if (host_port == 0)
2334                 packet_disconnect("Dynamic forwarding denied.");
2335 #endif
2336
2337         /* Initiate forwarding */
2338         channel_setup_local_fwd_listener(port, hostname, host_port, gateway_ports);
2339
2340         /* Free the argument string. */
2341         xfree(hostname);
2342 }
2343
2344 /*
2345  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2346  * usually called by the server, because the user could connect to any port
2347  * anyway, and the server has no way to know but to trust the client anyway.
2348  */
2349 void
2350 channel_permit_all_opens(void)
2351 {
2352         if (num_permitted_opens == 0)
2353                 all_opens_permitted = 1;
2354 }
2355
2356 void
2357 channel_add_permitted_opens(char *host, int port)
2358 {
2359         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2360                 fatal("channel_request_remote_forwarding: too many forwards");
2361         debug("allow port forwarding to host %s port %d", host, port);
2362
2363         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2364         permitted_opens[num_permitted_opens].port_to_connect = port;
2365         num_permitted_opens++;
2366
2367         all_opens_permitted = 0;
2368 }
2369
2370 void
2371 channel_clear_permitted_opens(void)
2372 {
2373         int i;
2374
2375         for (i = 0; i < num_permitted_opens; i++)
2376                 xfree(permitted_opens[i].host_to_connect);
2377         num_permitted_opens = 0;
2378
2379 }
2380
2381
2382 /* return socket to remote host, port */
2383 static int
2384 connect_to(const char *host, u_short port)
2385 {
2386         struct addrinfo hints, *ai, *aitop;
2387         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2388         int gaierr;
2389         int sock = -1;
2390
2391         memset(&hints, 0, sizeof(hints));
2392         hints.ai_family = IPv4or6;
2393         hints.ai_socktype = SOCK_STREAM;
2394         snprintf(strport, sizeof strport, "%d", port);
2395         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2396                 error("connect_to %.100s: unknown host (%s)", host,
2397                     gai_strerror(gaierr));
2398                 return -1;
2399         }
2400         for (ai = aitop; ai; ai = ai->ai_next) {
2401                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2402                         continue;
2403                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2404                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2405                         error("connect_to: getnameinfo failed");
2406                         continue;
2407                 }
2408                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2409                 if (sock < 0) {
2410                         if (ai->ai_next == NULL)
2411                                 error("socket: %.100s", strerror(errno));
2412                         else
2413                                 verbose("socket: %.100s", strerror(errno));
2414                         continue;
2415                 }
2416                 if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0)
2417                         fatal("connect_to: F_SETFL: %s", strerror(errno));
2418                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2419                     errno != EINPROGRESS) {
2420                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2421                             strerror(errno));
2422                         close(sock);
2423                         continue;       /* fail -- try next */
2424                 }
2425                 break; /* success */
2426
2427         }
2428         freeaddrinfo(aitop);
2429         if (!ai) {
2430                 error("connect_to %.100s port %d: failed.", host, port);
2431                 return -1;
2432         }
2433         /* success */
2434         set_nodelay(sock);
2435         return sock;
2436 }
2437
2438 int
2439 channel_connect_by_listen_address(u_short listen_port)
2440 {
2441         int i;
2442
2443         for (i = 0; i < num_permitted_opens; i++)
2444                 if (permitted_opens[i].listen_port == listen_port)
2445                         return connect_to(
2446                             permitted_opens[i].host_to_connect,
2447                             permitted_opens[i].port_to_connect);
2448         error("WARNING: Server requests forwarding for unknown listen_port %d",
2449             listen_port);
2450         return -1;
2451 }
2452
2453 /* Check if connecting to that port is permitted and connect. */
2454 int
2455 channel_connect_to(const char *host, u_short port)
2456 {
2457         int i, permit;
2458
2459         permit = all_opens_permitted;
2460         if (!permit) {
2461                 for (i = 0; i < num_permitted_opens; i++)
2462                         if (permitted_opens[i].port_to_connect == port &&
2463                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2464                                 permit = 1;
2465
2466         }
2467         if (!permit) {
2468                 logit("Received request to connect to host %.100s port %d, "
2469                     "but the request was denied.", host, port);
2470                 return -1;
2471         }
2472         return connect_to(host, port);
2473 }
2474
2475 /* -- X11 forwarding */
2476
2477 /*
2478  * Creates an internet domain socket for listening for X11 connections.
2479  * Returns 0 and a suitable display number for the DISPLAY variable
2480  * stored in display_numberp , or -1 if an error occurs.
2481  */
2482 int
2483 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2484     int single_connection, u_int *display_numberp)
2485 {
2486         Channel *nc = NULL;
2487         int display_number, sock;
2488         u_short port;
2489         struct addrinfo hints, *ai, *aitop;
2490         char strport[NI_MAXSERV];
2491         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2492
2493         for (display_number = x11_display_offset;
2494             display_number < MAX_DISPLAYS;
2495             display_number++) {
2496                 port = 6000 + display_number;
2497                 memset(&hints, 0, sizeof(hints));
2498                 hints.ai_family = IPv4or6;
2499                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2500                 hints.ai_socktype = SOCK_STREAM;
2501                 snprintf(strport, sizeof strport, "%d", port);
2502                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2503                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2504                         return -1;
2505                 }
2506                 for (ai = aitop; ai; ai = ai->ai_next) {
2507                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2508                                 continue;
2509                         sock = socket(ai->ai_family, ai->ai_socktype,
2510                             ai->ai_protocol);
2511                         if (sock < 0) {
2512                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2513                                         error("socket: %.100s", strerror(errno));
2514                                         return -1;
2515                                 } else {
2516                                         debug("x11_create_display_inet: Socket family %d not supported",
2517                                                  ai->ai_family);
2518                                         continue;
2519                                 }
2520                         }
2521 #ifdef IPV6_V6ONLY
2522                         if (ai->ai_family == AF_INET6) {
2523                                 int on = 1;
2524                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2525                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2526                         }
2527 #endif
2528                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2529                                 debug2("bind port %d: %.100s", port, strerror(errno));
2530                                 close(sock);
2531
2532                                 if (ai->ai_next)
2533                                         continue;
2534
2535                                 for (n = 0; n < num_socks; n++) {
2536                                         close(socks[n]);
2537                                 }
2538                                 num_socks = 0;
2539                                 break;
2540                         }
2541                         socks[num_socks++] = sock;
2542 #ifndef DONT_TRY_OTHER_AF
2543                         if (num_socks == NUM_SOCKS)
2544                                 break;
2545 #else
2546                         if (x11_use_localhost) {
2547                                 if (num_socks == NUM_SOCKS)
2548                                         break;
2549                         } else {
2550                                 break;
2551                         }
2552 #endif
2553                 }
2554                 freeaddrinfo(aitop);
2555                 if (num_socks > 0)
2556                         break;
2557         }
2558         if (display_number >= MAX_DISPLAYS) {
2559                 error("Failed to allocate internet-domain X11 display socket.");
2560                 return -1;
2561         }
2562         /* Start listening for connections on the socket. */
2563         for (n = 0; n < num_socks; n++) {
2564                 sock = socks[n];
2565                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2566                         error("listen: %.100s", strerror(errno));
2567                         close(sock);
2568                         return -1;
2569                 }
2570         }
2571
2572         /* Allocate a channel for each socket. */
2573         for (n = 0; n < num_socks; n++) {
2574                 sock = socks[n];
2575                 nc = channel_new("x11 listener",
2576                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2577                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2578                     0, "X11 inet listener", 1);
2579                 nc->single_connection = single_connection;
2580         }
2581
2582         /* Return the display number for the DISPLAY environment variable. */
2583         *display_numberp = display_number;
2584         return (0);
2585 }
2586
2587 static int
2588 connect_local_xsocket(u_int dnr)
2589 {
2590         int sock;
2591         struct sockaddr_un addr;
2592
2593         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2594         if (sock < 0)
2595                 error("socket: %.100s", strerror(errno));
2596         memset(&addr, 0, sizeof(addr));
2597         addr.sun_family = AF_UNIX;
2598         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2599         if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2600                 return sock;
2601         close(sock);
2602         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2603         return -1;
2604 }
2605
2606 int
2607 x11_connect_display(void)
2608 {
2609         int display_number, sock = 0;
2610         const char *display;
2611         char buf[1024], *cp;
2612         struct addrinfo hints, *ai, *aitop;
2613         char strport[NI_MAXSERV];
2614         int gaierr;
2615
2616         /* Try to open a socket for the local X server. */
2617         display = getenv("DISPLAY");
2618         if (!display) {
2619                 error("DISPLAY not set.");
2620                 return -1;
2621         }
2622         /*
2623          * Now we decode the value of the DISPLAY variable and make a
2624          * connection to the real X server.
2625          */
2626
2627         /*
2628          * Check if it is a unix domain socket.  Unix domain displays are in
2629          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2630          */
2631         if (strncmp(display, "unix:", 5) == 0 ||
2632             display[0] == ':') {
2633                 /* Connect to the unix domain socket. */
2634                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2635                         error("Could not parse display number from DISPLAY: %.100s",
2636                             display);
2637                         return -1;
2638                 }
2639                 /* Create a socket. */
2640                 sock = connect_local_xsocket(display_number);
2641                 if (sock < 0)
2642                         return -1;
2643
2644                 /* OK, we now have a connection to the display. */
2645                 return sock;
2646         }
2647         /*
2648          * Connect to an inet socket.  The DISPLAY value is supposedly
2649          * hostname:d[.s], where hostname may also be numeric IP address.
2650          */
2651         strlcpy(buf, display, sizeof(buf));
2652         cp = strchr(buf, ':');
2653         if (!cp) {
2654                 error("Could not find ':' in DISPLAY: %.100s", display);
2655                 return -1;
2656         }
2657         *cp = 0;
2658         /* buf now contains the host name.  But first we parse the display number. */
2659         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2660                 error("Could not parse display number from DISPLAY: %.100s",
2661                     display);
2662                 return -1;
2663         }
2664
2665         /* Look up the host address */
2666         memset(&hints, 0, sizeof(hints));
2667         hints.ai_family = IPv4or6;
2668         hints.ai_socktype = SOCK_STREAM;
2669         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2670         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2671                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2672                 return -1;
2673         }
2674         for (ai = aitop; ai; ai = ai->ai_next) {
2675                 /* Create a socket. */
2676                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2677                 if (sock < 0) {
2678                         debug2("socket: %.100s", strerror(errno));
2679                         continue;
2680                 }
2681                 /* Connect it to the display. */
2682                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2683                         debug2("connect %.100s port %d: %.100s", buf,
2684                             6000 + display_number, strerror(errno));
2685                         close(sock);
2686                         continue;
2687                 }
2688                 /* Success */
2689                 break;
2690         }
2691         freeaddrinfo(aitop);
2692         if (!ai) {
2693                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2694                     strerror(errno));
2695                 return -1;
2696         }
2697         set_nodelay(sock);
2698         return sock;
2699 }
2700
2701 /*
2702  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2703  * the remote channel number.  We should do whatever we want, and respond
2704  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2705  */
2706
2707 void
2708 x11_input_open(int type, u_int32_t seq, void *ctxt)
2709 {
2710         Channel *c = NULL;
2711         int remote_id, sock = 0;
2712         char *remote_host;
2713
2714         debug("Received X11 open request.");
2715
2716         remote_id = packet_get_int();
2717
2718         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2719                 remote_host = packet_get_string(NULL);
2720         } else {
2721                 remote_host = xstrdup("unknown (remote did not supply name)");
2722         }
2723         packet_check_eom();
2724
2725         /* Obtain a connection to the real X display. */
2726         sock = x11_connect_display();
2727         if (sock != -1) {
2728                 /* Allocate a channel for this connection. */
2729                 c = channel_new("connected x11 socket",
2730                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
2731                     remote_host, 1);
2732                 c->remote_id = remote_id;
2733                 c->force_drain = 1;
2734         }
2735         xfree(remote_host);
2736         if (c == NULL) {
2737                 /* Send refusal to the remote host. */
2738                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2739                 packet_put_int(remote_id);
2740         } else {
2741                 /* Send a confirmation to the remote host. */
2742                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2743                 packet_put_int(remote_id);
2744                 packet_put_int(c->self);
2745         }
2746         packet_send();
2747 }
2748
2749 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
2750 void
2751 deny_input_open(int type, u_int32_t seq, void *ctxt)
2752 {
2753         int rchan = packet_get_int();
2754
2755         switch (type) {
2756         case SSH_SMSG_AGENT_OPEN:
2757                 error("Warning: ssh server tried agent forwarding.");
2758                 break;
2759         case SSH_SMSG_X11_OPEN:
2760                 error("Warning: ssh server tried X11 forwarding.");
2761                 break;
2762         default:
2763                 error("deny_input_open: type %d", type);
2764                 break;
2765         }
2766         error("Warning: this is probably a break in attempt by a malicious server.");
2767         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2768         packet_put_int(rchan);
2769         packet_send();
2770 }
2771
2772 /*
2773  * Requests forwarding of X11 connections, generates fake authentication
2774  * data, and enables authentication spoofing.
2775  * This should be called in the client only.
2776  */
2777 void
2778 x11_request_forwarding_with_spoofing(int client_session_id,
2779     const char *proto, const char *data)
2780 {
2781         u_int data_len = (u_int) strlen(data) / 2;
2782         u_int i, value, len;
2783         char *new_data;
2784         int screen_number;
2785         const char *cp;
2786         u_int32_t rand = 0;
2787
2788         cp = getenv("DISPLAY");
2789         if (cp)
2790                 cp = strchr(cp, ':');
2791         if (cp)
2792                 cp = strchr(cp, '.');
2793         if (cp)
2794                 screen_number = atoi(cp + 1);
2795         else
2796                 screen_number = 0;
2797
2798         /* Save protocol name. */
2799         x11_saved_proto = xstrdup(proto);
2800
2801         /*
2802          * Extract real authentication data and generate fake data of the
2803          * same length.
2804          */
2805         x11_saved_data = xmalloc(data_len);
2806         x11_fake_data = xmalloc(data_len);
2807         for (i = 0; i < data_len; i++) {
2808                 if (sscanf(data + 2 * i, "%2x", &value) != 1)
2809                         fatal("x11_request_forwarding: bad authentication data: %.100s", data);
2810                 if (i % 4 == 0)
2811                         rand = arc4random();
2812                 x11_saved_data[i] = value;
2813                 x11_fake_data[i] = rand & 0xff;
2814                 rand >>= 8;
2815         }
2816         x11_saved_data_len = data_len;
2817         x11_fake_data_len = data_len;
2818
2819         /* Convert the fake data into hex. */
2820         len = 2 * data_len + 1;
2821         new_data = xmalloc(len);
2822         for (i = 0; i < data_len; i++)
2823                 snprintf(new_data + 2 * i, len - 2 * i,
2824                     "%02x", (u_char) x11_fake_data[i]);
2825
2826         /* Send the request packet. */
2827         if (compat20) {
2828                 channel_request_start(client_session_id, "x11-req", 0);
2829                 packet_put_char(0);     /* XXX bool single connection */
2830         } else {
2831                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
2832         }
2833         packet_put_cstring(proto);
2834         packet_put_cstring(new_data);
2835         packet_put_int(screen_number);
2836         packet_send();
2837         packet_write_wait();
2838         xfree(new_data);
2839 }
2840
2841
2842 /* -- agent forwarding */
2843
2844 /* Sends a message to the server to request authentication fd forwarding. */
2845
2846 void
2847 auth_request_forwarding(void)
2848 {
2849         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
2850         packet_send();
2851         packet_write_wait();
2852 }