channels.c

   1 /* $OpenBSD: channels.c,v 1.297 2009/10/28 16:38:18 reyk Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <netdb.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <termios.h>
  61 #include <unistd.h>
  62 #include <stdarg.h>
  63
  64 #include "openbsd-compat/sys-queue.h"
  65 #include "xmalloc.h"
  66 #include "ssh.h"
  67 #include "ssh1.h"
  68 #include "ssh2.h"
  69 #include "packet.h"
  70 #include "log.h"
  71 #include "misc.h"
  72 #include "buffer.h"
  73 #include "channels.h"
  74 #include "compat.h"
  75 #include "canohost.h"
  76 #include "key.h"
  77 #include "authfd.h"
  78 #include "pathnames.h"
  79
  80 /* -- channel core */
  81
  82 /*
  83  * Pointer to an array containing all allocated channels.  The array is
  84  * dynamically extended as needed.
  85  */
  86 static Channel **channels = NULL;
  87
  88 /*
  89  * Size of the channel array.  All slots of the array must always be
  90  * initialized (at least the type field); unused slots set to NULL
  91  */
  92 static u_int channels_alloc = 0;
  93
  94 /*
  95  * Maximum file descriptor value used in any of the channels.  This is
  96  * updated in channel_new.
  97  */
  98 static int channel_max_fd = 0;
  99
 100
 101 /* -- tcp forwarding */
 102
 103 /*
 104  * Data structure for storing which hosts are permitted for forward requests.
 105  * The local sides of any remote forwards are stored in this array to prevent
 106  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 107  * network (which might be behind a firewall).
 108  */
 109 typedef struct {
 110         char *host_to_connect;          /* Connect to 'host'. */
 111         u_short port_to_connect;        /* Connect to 'port'. */
 112         u_short listen_port;            /* Remote side should listen port number. */
 113 } ForwardPermission;
 114
 115 /* List of all permitted host/port pairs to connect by the user. */
 116 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 117
 118 /* List of all permitted host/port pairs to connect by the admin. */
 119 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 120
 121 /* Number of permitted host/port pairs in the array permitted by the user. */
 122 static int num_permitted_opens = 0;
 123
 124 /* Number of permitted host/port pair in the array permitted by the admin. */
 125 static int num_adm_permitted_opens = 0;
 126
 127 /*
 128  * If this is true, all opens are permitted.  This is the case on the server
 129  * on which we have to trust the client anyway, and the user could do
 130  * anything after logging in anyway.
 131  */
 132 static int all_opens_permitted = 0;
 133
 134
 135 /* -- X11 forwarding */
 136
 137 /* Maximum number of fake X11 displays to try. */
 138 #define MAX_DISPLAYS  1000
 139
 140 /* Saved X11 local (client) display. */
 141 static char *x11_saved_display = NULL;
 142
 143 /* Saved X11 authentication protocol name. */
 144 static char *x11_saved_proto = NULL;
 145
 146 /* Saved X11 authentication data.  This is the real data. */
 147 static char *x11_saved_data = NULL;
 148 static u_int x11_saved_data_len = 0;
 149
 150 /*
 151  * Fake X11 authentication data.  This is what the server will be sending us;
 152  * we should replace any occurrences of this by the real data.
 153  */
 154 static u_char *x11_fake_data = NULL;
 155 static u_int x11_fake_data_len;
 156
 157
 158 /* -- agent forwarding */
 159
 160 #define NUM_SOCKS       10
 161
 162 /* AF_UNSPEC or AF_INET or AF_INET6 */
 163 static int IPv4or6 = AF_UNSPEC;
 164
 165 /* Set the routing domain a.k.a. VRF */
 166 static int channel_rdomain = -1;
 167
 168 /* helper */
 169 static void port_open_helper(Channel *c, char *rtype);
 170
 171 /* non-blocking connect helpers */
 172 static int connect_next(struct channel_connect *);
 173 static void channel_connect_ctx_free(struct channel_connect *);
 174
 175 /* -- channel core */
 176
 177 Channel *
 178 channel_by_id(int id)
 179 {
 180         Channel *c;
 181
 182         if (id < 0 || (u_int)id >= channels_alloc) {
 183                 logit("channel_by_id: %d: bad id", id);
 184                 return NULL;
 185         }
 186         c = channels[id];
 187         if (c == NULL) {
 188                 logit("channel_by_id: %d: bad id: channel free", id);
 189                 return NULL;
 190         }
 191         return c;
 192 }
 193
 194 /*
 195  * Returns the channel if it is allowed to receive protocol messages.
 196  * Private channels, like listening sockets, may not receive messages.
 197  */
 198 Channel *
 199 channel_lookup(int id)
 200 {
 201         Channel *c;
 202
 203         if ((c = channel_by_id(id)) == NULL)
 204                 return (NULL);
 205
 206         switch (c->type) {
 207         case SSH_CHANNEL_X11_OPEN:
 208         case SSH_CHANNEL_LARVAL:
 209         case SSH_CHANNEL_CONNECTING:
 210         case SSH_CHANNEL_DYNAMIC:
 211         case SSH_CHANNEL_OPENING:
 212         case SSH_CHANNEL_OPEN:
 213         case SSH_CHANNEL_INPUT_DRAINING:
 214         case SSH_CHANNEL_OUTPUT_DRAINING:
 215                 return (c);
 216         }
 217         logit("Non-public channel %d, type %d.", id, c->type);
 218         return (NULL);
 219 }
 220
 221 /*
 222  * Register filedescriptors for a channel, used when allocating a channel or
 223  * when the channel consumer/producer is ready, e.g. shell exec'd
 224  */
 225 static void
 226 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 227     int extusage, int nonblock, int is_tty)
 228 {
 229         /* Update the maximum file descriptor value. */
 230         channel_max_fd = MAX(channel_max_fd, rfd);
 231         channel_max_fd = MAX(channel_max_fd, wfd);
 232         channel_max_fd = MAX(channel_max_fd, efd);
 233
 234         /* XXX set close-on-exec -markus */
 235
 236         c->rfd = rfd;
 237         c->wfd = wfd;
 238         c->sock = (rfd == wfd) ? rfd : -1;
 239         c->ctl_fd = -1; /* XXX: set elsewhere */
 240         c->efd = efd;
 241         c->extended_usage = extusage;
 242
 243         if ((c->isatty = is_tty) != 0)
 244                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 245         c->wfd_isatty = is_tty || isatty(c->wfd);
 246
 247         /* enable nonblocking mode */
 248         if (nonblock) {
 249                 if (rfd != -1)
 250                         set_nonblock(rfd);
 251                 if (wfd != -1)
 252                         set_nonblock(wfd);
 253                 if (efd != -1)
 254                         set_nonblock(efd);
 255         }
 256 }
 257
 258 /*
 259  * Allocate a new channel object and set its type and socket. This will cause
 260  * remote_name to be freed.
 261  */
 262 Channel *
 263 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 264     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 265 {
 266         int found;
 267         u_int i;
 268         Channel *c;
 269
 270         /* Do initial allocation if this is the first call. */
 271         if (channels_alloc == 0) {
 272                 channels_alloc = 10;
 273                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 274                 for (i = 0; i < channels_alloc; i++)
 275                         channels[i] = NULL;
 276         }
 277         /* Try to find a free slot where to put the new channel. */
 278         for (found = -1, i = 0; i < channels_alloc; i++)
 279                 if (channels[i] == NULL) {
 280                         /* Found a free slot. */
 281                         found = (int)i;
 282                         break;
 283                 }
 284         if (found < 0) {
 285                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 286                 found = channels_alloc;
 287                 if (channels_alloc > 10000)
 288                         fatal("channel_new: internal error: channels_alloc %d "
 289                             "too big.", channels_alloc);
 290                 channels = xrealloc(channels, channels_alloc + 10,
 291                     sizeof(Channel *));
 292                 channels_alloc += 10;
 293                 debug2("channel: expanding %d", channels_alloc);
 294                 for (i = found; i < channels_alloc; i++)
 295                         channels[i] = NULL;
 296         }
 297         /* Initialize and return new channel. */
 298         c = channels[found] = xcalloc(1, sizeof(Channel));
 299         buffer_init(&c->input);
 300         buffer_init(&c->output);
 301         buffer_init(&c->extended);
 302         c->path = NULL;
 303         c->ostate = CHAN_OUTPUT_OPEN;
 304         c->istate = CHAN_INPUT_OPEN;
 305         c->flags = 0;
 306         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 307         c->self = found;
 308         c->type = type;
 309         c->ctype = ctype;
 310         c->local_window = window;
 311         c->local_window_max = window;
 312         c->local_consumed = 0;
 313         c->local_maxpacket = maxpack;
 314         c->remote_id = -1;
 315         c->remote_name = xstrdup(remote_name);
 316         c->remote_window = 0;
 317         c->remote_maxpacket = 0;
 318         c->force_drain = 0;
 319         c->single_connection = 0;
 320         c->detach_user = NULL;
 321         c->detach_close = 0;
 322         c->open_confirm = NULL;
 323         c->open_confirm_ctx = NULL;
 324         c->input_filter = NULL;
 325         c->output_filter = NULL;
 326         c->filter_ctx = NULL;
 327         c->filter_cleanup = NULL;
 328         TAILQ_INIT(&c->status_confirms);
 329         debug("channel %d: new [%s]", found, remote_name);
 330         return c;
 331 }
 332
 333 static int
 334 channel_find_maxfd(void)
 335 {
 336         u_int i;
 337         int max = 0;
 338         Channel *c;
 339
 340         for (i = 0; i < channels_alloc; i++) {
 341                 c = channels[i];
 342                 if (c != NULL) {
 343                         max = MAX(max, c->rfd);
 344                         max = MAX(max, c->wfd);
 345                         max = MAX(max, c->efd);
 346                 }
 347         }
 348         return max;
 349 }
 350
 351 int
 352 channel_close_fd(int *fdp)
 353 {
 354         int ret = 0, fd = *fdp;
 355
 356         if (fd != -1) {
 357                 ret = close(fd);
 358                 *fdp = -1;
 359                 if (fd == channel_max_fd)
 360                         channel_max_fd = channel_find_maxfd();
 361         }
 362         return ret;
 363 }
 364
 365 /* Close all channel fd/socket. */
 366 static void
 367 channel_close_fds(Channel *c)
 368 {
 369         debug3("channel %d: close_fds r %d w %d e %d c %d",
 370             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 371
 372         channel_close_fd(&c->sock);
 373         channel_close_fd(&c->ctl_fd);
 374         channel_close_fd(&c->rfd);
 375         channel_close_fd(&c->wfd);
 376         channel_close_fd(&c->efd);
 377 }
 378
 379 /* Free the channel and close its fd/socket. */
 380 void
 381 channel_free(Channel *c)
 382 {
 383         char *s;
 384         u_int i, n;
 385         struct channel_confirm *cc;
 386
 387         for (n = 0, i = 0; i < channels_alloc; i++)
 388                 if (channels[i])
 389                         n++;
 390         debug("channel %d: free: %s, nchannels %u", c->self,
 391             c->remote_name ? c->remote_name : "???", n);
 392
 393         s = channel_open_message();
 394         debug3("channel %d: status: %s", c->self, s);
 395         xfree(s);
 396
 397         if (c->sock != -1)
 398                 shutdown(c->sock, SHUT_RDWR);
 399         if (c->ctl_fd != -1)
 400                 shutdown(c->ctl_fd, SHUT_RDWR);
 401         channel_close_fds(c);
 402         buffer_free(&c->input);
 403         buffer_free(&c->output);
 404         buffer_free(&c->extended);
 405         if (c->remote_name) {
 406                 xfree(c->remote_name);
 407                 c->remote_name = NULL;
 408         }
 409         if (c->path) {
 410                 xfree(c->path);
 411                 c->path = NULL;
 412         }
 413         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 414                 if (cc->abandon_cb != NULL)
 415                         cc->abandon_cb(c, cc->ctx);
 416                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 417                 bzero(cc, sizeof(*cc));
 418                 xfree(cc);
 419         }
 420         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 421                 c->filter_cleanup(c->self, c->filter_ctx);
 422         channels[c->self] = NULL;
 423         xfree(c);
 424 }
 425
 426 void
 427 channel_free_all(void)
 428 {
 429         u_int i;
 430
 431         for (i = 0; i < channels_alloc; i++)
 432                 if (channels[i] != NULL)
 433                         channel_free(channels[i]);
 434 }
 435
 436 /*
 437  * Closes the sockets/fds of all channels.  This is used to close extra file
 438  * descriptors after a fork.
 439  */
 440 void
 441 channel_close_all(void)
 442 {
 443         u_int i;
 444
 445         for (i = 0; i < channels_alloc; i++)
 446                 if (channels[i] != NULL)
 447                         channel_close_fds(channels[i]);
 448 }
 449
 450 /*
 451  * Stop listening to channels.
 452  */
 453 void
 454 channel_stop_listening(void)
 455 {
 456         u_int i;
 457         Channel *c;
 458
 459         for (i = 0; i < channels_alloc; i++) {
 460                 c = channels[i];
 461                 if (c != NULL) {
 462                         switch (c->type) {
 463                         case SSH_CHANNEL_AUTH_SOCKET:
 464                         case SSH_CHANNEL_PORT_LISTENER:
 465                         case SSH_CHANNEL_RPORT_LISTENER:
 466                         case SSH_CHANNEL_X11_LISTENER:
 467                                 channel_close_fd(&c->sock);
 468                                 channel_free(c);
 469                                 break;
 470                         }
 471                 }
 472         }
 473 }
 474
 475 /*
 476  * Returns true if no channel has too much buffered data, and false if one or
 477  * more channel is overfull.
 478  */
 479 int
 480 channel_not_very_much_buffered_data(void)
 481 {
 482         u_int i;
 483         Channel *c;
 484
 485         for (i = 0; i < channels_alloc; i++) {
 486                 c = channels[i];
 487                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 488 #if 0
 489                         if (!compat20 &&
 490                             buffer_len(&c->input) > packet_get_maxsize()) {
 491                                 debug2("channel %d: big input buffer %d",
 492                                     c->self, buffer_len(&c->input));
 493                                 return 0;
 494                         }
 495 #endif
 496                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 497                                 debug2("channel %d: big output buffer %u > %u",
 498                                     c->self, buffer_len(&c->output),
 499                                     packet_get_maxsize());
 500                                 return 0;
 501                         }
 502                 }
 503         }
 504         return 1;
 505 }
 506
 507 /* Returns true if any channel is still open. */
 508 int
 509 channel_still_open(void)
 510 {
 511         u_int i;
 512         Channel *c;
 513
 514         for (i = 0; i < channels_alloc; i++) {
 515                 c = channels[i];
 516                 if (c == NULL)
 517                         continue;
 518                 switch (c->type) {
 519                 case SSH_CHANNEL_X11_LISTENER:
 520                 case SSH_CHANNEL_PORT_LISTENER:
 521                 case SSH_CHANNEL_RPORT_LISTENER:
 522                 case SSH_CHANNEL_CLOSED:
 523                 case SSH_CHANNEL_AUTH_SOCKET:
 524                 case SSH_CHANNEL_DYNAMIC:
 525                 case SSH_CHANNEL_CONNECTING:
 526                 case SSH_CHANNEL_ZOMBIE:
 527                         continue;
 528                 case SSH_CHANNEL_LARVAL:
 529                         if (!compat20)
 530                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 531                         continue;
 532                 case SSH_CHANNEL_OPENING:
 533                 case SSH_CHANNEL_OPEN:
 534                 case SSH_CHANNEL_X11_OPEN:
 535                         return 1;
 536                 case SSH_CHANNEL_INPUT_DRAINING:
 537                 case SSH_CHANNEL_OUTPUT_DRAINING:
 538                         if (!compat13)
 539                                 fatal("cannot happen: OUT_DRAIN");
 540                         return 1;
 541                 default:
 542                         fatal("channel_still_open: bad channel type %d", c->type);
 543                         /* NOTREACHED */
 544                 }
 545         }
 546         return 0;
 547 }
 548
 549 /* Returns the id of an open channel suitable for keepaliving */
 550 int
 551 channel_find_open(void)
 552 {
 553         u_int i;
 554         Channel *c;
 555
 556         for (i = 0; i < channels_alloc; i++) {
 557                 c = channels[i];
 558                 if (c == NULL || c->remote_id < 0)
 559                         continue;
 560                 switch (c->type) {
 561                 case SSH_CHANNEL_CLOSED:
 562                 case SSH_CHANNEL_DYNAMIC:
 563                 case SSH_CHANNEL_X11_LISTENER:
 564                 case SSH_CHANNEL_PORT_LISTENER:
 565                 case SSH_CHANNEL_RPORT_LISTENER:
 566                 case SSH_CHANNEL_OPENING:
 567                 case SSH_CHANNEL_CONNECTING:
 568                 case SSH_CHANNEL_ZOMBIE:
 569                         continue;
 570                 case SSH_CHANNEL_LARVAL:
 571                 case SSH_CHANNEL_AUTH_SOCKET:
 572                 case SSH_CHANNEL_OPEN:
 573                 case SSH_CHANNEL_X11_OPEN:
 574                         return i;
 575                 case SSH_CHANNEL_INPUT_DRAINING:
 576                 case SSH_CHANNEL_OUTPUT_DRAINING:
 577                         if (!compat13)
 578                                 fatal("cannot happen: OUT_DRAIN");
 579                         return i;
 580                 default:
 581                         fatal("channel_find_open: bad channel type %d", c->type);
 582                         /* NOTREACHED */
 583                 }
 584         }
 585         return -1;
 586 }
 587
 588
 589 /*
 590  * Returns a message describing the currently open forwarded connections,
 591  * suitable for sending to the client.  The message contains crlf pairs for
 592  * newlines.
 593  */
 594 char *
 595 channel_open_message(void)
 596 {
 597         Buffer buffer;
 598         Channel *c;
 599         char buf[1024], *cp;
 600         u_int i;
 601
 602         buffer_init(&buffer);
 603         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 604         buffer_append(&buffer, buf, strlen(buf));
 605         for (i = 0; i < channels_alloc; i++) {
 606                 c = channels[i];
 607                 if (c == NULL)
 608                         continue;
 609                 switch (c->type) {
 610                 case SSH_CHANNEL_X11_LISTENER:
 611                 case SSH_CHANNEL_PORT_LISTENER:
 612                 case SSH_CHANNEL_RPORT_LISTENER:
 613                 case SSH_CHANNEL_CLOSED:
 614                 case SSH_CHANNEL_AUTH_SOCKET:
 615                 case SSH_CHANNEL_ZOMBIE:
 616                         continue;
 617                 case SSH_CHANNEL_LARVAL:
 618                 case SSH_CHANNEL_OPENING:
 619                 case SSH_CHANNEL_CONNECTING:
 620                 case SSH_CHANNEL_DYNAMIC:
 621                 case SSH_CHANNEL_OPEN:
 622                 case SSH_CHANNEL_X11_OPEN:
 623                 case SSH_CHANNEL_INPUT_DRAINING:
 624                 case SSH_CHANNEL_OUTPUT_DRAINING:
 625                         snprintf(buf, sizeof buf,
 626                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 627                             c->self, c->remote_name,
 628                             c->type, c->remote_id,
 629                             c->istate, buffer_len(&c->input),
 630                             c->ostate, buffer_len(&c->output),
 631                             c->rfd, c->wfd, c->ctl_fd);
 632                         buffer_append(&buffer, buf, strlen(buf));
 633                         continue;
 634                 default:
 635                         fatal("channel_open_message: bad channel type %d", c->type);
 636                         /* NOTREACHED */
 637                 }
 638         }
 639         buffer_append(&buffer, "\0", 1);
 640         cp = xstrdup(buffer_ptr(&buffer));
 641         buffer_free(&buffer);
 642         return cp;
 643 }
 644
 645 void
 646 channel_send_open(int id)
 647 {
 648         Channel *c = channel_lookup(id);
 649
 650         if (c == NULL) {
 651                 logit("channel_send_open: %d: bad id", id);
 652                 return;
 653         }
 654         debug2("channel %d: send open", id);
 655         packet_start(SSH2_MSG_CHANNEL_OPEN);
 656         packet_put_cstring(c->ctype);
 657         packet_put_int(c->self);
 658         packet_put_int(c->local_window);
 659         packet_put_int(c->local_maxpacket);
 660         packet_send();
 661 }
 662
 663 void
 664 channel_request_start(int id, char *service, int wantconfirm)
 665 {
 666         Channel *c = channel_lookup(id);
 667
 668         if (c == NULL) {
 669                 logit("channel_request_start: %d: unknown channel id", id);
 670                 return;
 671         }
 672         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 673         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 674         packet_put_int(c->remote_id);
 675         packet_put_cstring(service);
 676         packet_put_char(wantconfirm);
 677 }
 678
 679 void
 680 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 681     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 682 {
 683         struct channel_confirm *cc;
 684         Channel *c;
 685
 686         if ((c = channel_lookup(id)) == NULL)
 687                 fatal("channel_register_expect: %d: bad id", id);
 688
 689         cc = xmalloc(sizeof(*cc));
 690         cc->cb = cb;
 691         cc->abandon_cb = abandon_cb;
 692         cc->ctx = ctx;
 693         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 694 }
 695
 696 void
 697 channel_register_open_confirm(int id, channel_callback_fn *fn, void *ctx)
 698 {
 699         Channel *c = channel_lookup(id);
 700
 701         if (c == NULL) {
 702                 logit("channel_register_open_confirm: %d: bad id", id);
 703                 return;
 704         }
 705         c->open_confirm = fn;
 706         c->open_confirm_ctx = ctx;
 707 }
 708
 709 void
 710 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 711 {
 712         Channel *c = channel_by_id(id);
 713
 714         if (c == NULL) {
 715                 logit("channel_register_cleanup: %d: bad id", id);
 716                 return;
 717         }
 718         c->detach_user = fn;
 719         c->detach_close = do_close;
 720 }
 721
 722 void
 723 channel_cancel_cleanup(int id)
 724 {
 725         Channel *c = channel_by_id(id);
 726
 727         if (c == NULL) {
 728                 logit("channel_cancel_cleanup: %d: bad id", id);
 729                 return;
 730         }
 731         c->detach_user = NULL;
 732         c->detach_close = 0;
 733 }
 734
 735 void
 736 channel_register_filter(int id, channel_infilter_fn *ifn,
 737     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 738 {
 739         Channel *c = channel_lookup(id);
 740
 741         if (c == NULL) {
 742                 logit("channel_register_filter: %d: bad id", id);
 743                 return;
 744         }
 745         c->input_filter = ifn;
 746         c->output_filter = ofn;
 747         c->filter_ctx = ctx;
 748         c->filter_cleanup = cfn;
 749 }
 750
 751 void
 752 channel_set_fds(int id, int rfd, int wfd, int efd,
 753     int extusage, int nonblock, int is_tty, u_int window_max)
 754 {
 755         Channel *c = channel_lookup(id);
 756
 757         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 758                 fatal("channel_activate for non-larval channel %d.", id);
 759         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 760         c->type = SSH_CHANNEL_OPEN;
 761         c->local_window = c->local_window_max = window_max;
 762         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 763         packet_put_int(c->remote_id);
 764         packet_put_int(c->local_window);
 765         packet_send();
 766 }
 767
 768 /*
 769  * 'channel_pre*' are called just before select() to add any bits relevant to
 770  * channels in the select bitmasks.
 771  */
 772 /*
 773  * 'channel_post*': perform any appropriate operations for channels which
 774  * have events pending.
 775  */
 776 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 777 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 778 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 779
 780 /* ARGSUSED */
 781 static void
 782 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 783 {
 784         FD_SET(c->sock, readset);
 785 }
 786
 787 /* ARGSUSED */
 788 static void
 789 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 790 {
 791         debug3("channel %d: waiting for connection", c->self);
 792         FD_SET(c->sock, writeset);
 793 }
 794
 795 static void
 796 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 797 {
 798         if (buffer_len(&c->input) < packet_get_maxsize())
 799                 FD_SET(c->sock, readset);
 800         if (buffer_len(&c->output) > 0)
 801                 FD_SET(c->sock, writeset);
 802 }
 803
 804 static void
 805 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 806 {
 807         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 808
 809         if (c->istate == CHAN_INPUT_OPEN &&
 810             limit > 0 &&
 811             buffer_len(&c->input) < limit &&
 812             buffer_check_alloc(&c->input, CHAN_RBUF))
 813                 FD_SET(c->rfd, readset);
 814         if (c->ostate == CHAN_OUTPUT_OPEN ||
 815             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 816                 if (buffer_len(&c->output) > 0) {
 817                         FD_SET(c->wfd, writeset);
 818                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 819                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 820                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 821                                     c->self, c->efd, buffer_len(&c->extended));
 822                         else
 823                                 chan_obuf_empty(c);
 824                 }
 825         }
 826         /** XXX check close conditions, too */
 827         if (compat20 && c->efd != -1 &&
 828             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 829                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 830                     buffer_len(&c->extended) > 0)
 831                         FD_SET(c->efd, writeset);
 832                 else if (!(c->flags & CHAN_EOF_SENT) &&
 833                     c->extended_usage == CHAN_EXTENDED_READ &&
 834                     buffer_len(&c->extended) < c->remote_window)
 835                         FD_SET(c->efd, readset);
 836         }
 837         /* XXX: What about efd? races? */
 838         if (compat20 && c->ctl_fd != -1 &&
 839             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 840                 FD_SET(c->ctl_fd, readset);
 841 }
 842
 843 /* ARGSUSED */
 844 static void
 845 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 846 {
 847         if (buffer_len(&c->input) == 0) {
 848                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 849                 packet_put_int(c->remote_id);
 850                 packet_send();
 851                 c->type = SSH_CHANNEL_CLOSED;
 852                 debug2("channel %d: closing after input drain.", c->self);
 853         }
 854 }
 855
 856 /* ARGSUSED */
 857 static void
 858 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 859 {
 860         if (buffer_len(&c->output) == 0)
 861                 chan_mark_dead(c);
 862         else
 863                 FD_SET(c->sock, writeset);
 864 }
 865
 866 /*
 867  * This is a special state for X11 authentication spoofing.  An opened X11
 868  * connection (when authentication spoofing is being done) remains in this
 869  * state until the first packet has been completely read.  The authentication
 870  * data in that packet is then substituted by the real data if it matches the
 871  * fake data, and the channel is put into normal mode.
 872  * XXX All this happens at the client side.
 873  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 874  */
 875 static int
 876 x11_open_helper(Buffer *b)
 877 {
 878         u_char *ucp;
 879         u_int proto_len, data_len;
 880
 881         /* Check if the fixed size part of the packet is in buffer. */
 882         if (buffer_len(b) < 12)
 883                 return 0;
 884
 885         /* Parse the lengths of variable-length fields. */
 886         ucp = buffer_ptr(b);
 887         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 888                 proto_len = 256 * ucp[6] + ucp[7];
 889                 data_len = 256 * ucp[8] + ucp[9];
 890         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 891                 proto_len = ucp[6] + 256 * ucp[7];
 892                 data_len = ucp[8] + 256 * ucp[9];
 893         } else {
 894                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 895                     ucp[0]);
 896                 return -1;
 897         }
 898
 899         /* Check if the whole packet is in buffer. */
 900         if (buffer_len(b) <
 901             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 902                 return 0;
 903
 904         /* Check if authentication protocol matches. */
 905         if (proto_len != strlen(x11_saved_proto) ||
 906             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 907                 debug2("X11 connection uses different authentication protocol.");
 908                 return -1;
 909         }
 910         /* Check if authentication data matches our fake data. */
 911         if (data_len != x11_fake_data_len ||
 912             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 913                 x11_fake_data, x11_fake_data_len) != 0) {
 914                 debug2("X11 auth data does not match fake data.");
 915                 return -1;
 916         }
 917         /* Check fake data length */
 918         if (x11_fake_data_len != x11_saved_data_len) {
 919                 error("X11 fake_data_len %d != saved_data_len %d",
 920                     x11_fake_data_len, x11_saved_data_len);
 921                 return -1;
 922         }
 923         /*
 924          * Received authentication protocol and data match
 925          * our fake data. Substitute the fake data with real
 926          * data.
 927          */
 928         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 929             x11_saved_data, x11_saved_data_len);
 930         return 1;
 931 }
 932
 933 static void
 934 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 935 {
 936         int ret = x11_open_helper(&c->output);
 937
 938         if (ret == 1) {
 939                 /* Start normal processing for the channel. */
 940                 c->type = SSH_CHANNEL_OPEN;
 941                 channel_pre_open_13(c, readset, writeset);
 942         } else if (ret == -1) {
 943                 /*
 944                  * We have received an X11 connection that has bad
 945                  * authentication information.
 946                  */
 947                 logit("X11 connection rejected because of wrong authentication.");
 948                 buffer_clear(&c->input);
 949                 buffer_clear(&c->output);
 950                 channel_close_fd(&c->sock);
 951                 c->sock = -1;
 952                 c->type = SSH_CHANNEL_CLOSED;
 953                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 954                 packet_put_int(c->remote_id);
 955                 packet_send();
 956         }
 957 }
 958
 959 static void
 960 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 961 {
 962         int ret = x11_open_helper(&c->output);
 963
 964         /* c->force_drain = 1; */
 965
 966         if (ret == 1) {
 967                 c->type = SSH_CHANNEL_OPEN;
 968                 channel_pre_open(c, readset, writeset);
 969         } else if (ret == -1) {
 970                 logit("X11 connection rejected because of wrong authentication.");
 971                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 972                 chan_read_failed(c);
 973                 buffer_clear(&c->input);
 974                 chan_ibuf_empty(c);
 975                 buffer_clear(&c->output);
 976                 /* for proto v1, the peer will send an IEOF */
 977                 if (compat20)
 978                         chan_write_failed(c);
 979                 else
 980                         c->type = SSH_CHANNEL_OPEN;
 981                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 982         }
 983 }
 984
 985 /* try to decode a socks4 header */
 986 /* ARGSUSED */
 987 static int
 988 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 989 {
 990         char *p, *host;
 991         u_int len, have, i, found, need;
 992         char username[256];
 993         struct {
 994                 u_int8_t version;
 995                 u_int8_t command;
 996                 u_int16_t dest_port;
 997                 struct in_addr dest_addr;
 998         } s4_req, s4_rsp;
 999
1000         debug2("channel %d: decode socks4", c->self);
1001
1002         have = buffer_len(&c->input);
1003         len = sizeof(s4_req);
1004         if (have < len)
1005                 return 0;
1006         p = buffer_ptr(&c->input);
1007
1008         need = 1;
1009         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1010         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1011                 debug2("channel %d: socks4a request", c->self);
1012                 /* ... and needs an extra string (the hostname) */
1013                 need = 2;
1014         }
1015         /* Check for terminating NUL on the string(s) */
1016         for (found = 0, i = len; i < have; i++) {
1017                 if (p[i] == '\0') {
1018                         found++;
1019                         if (found == need)
1020                                 break;
1021                 }
1022                 if (i > 1024) {
1023                         /* the peer is probably sending garbage */
1024                         debug("channel %d: decode socks4: too long",
1025                             c->self);
1026                         return -1;
1027                 }
1028         }
1029         if (found < need)
1030                 return 0;
1031         buffer_get(&c->input, (char *)&s4_req.version, 1);
1032         buffer_get(&c->input, (char *)&s4_req.command, 1);
1033         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1034         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1035         have = buffer_len(&c->input);
1036         p = buffer_ptr(&c->input);
1037         len = strlen(p);
1038         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1039         len++;                                  /* trailing '\0' */
1040         if (len > have)
1041                 fatal("channel %d: decode socks4: len %d > have %d",
1042                     c->self, len, have);
1043         strlcpy(username, p, sizeof(username));
1044         buffer_consume(&c->input, len);
1045
1046         if (c->path != NULL) {
1047                 xfree(c->path);
1048                 c->path = NULL;
1049         }
1050         if (need == 1) {                        /* SOCKS4: one string */
1051                 host = inet_ntoa(s4_req.dest_addr);
1052                 c->path = xstrdup(host);
1053         } else {                                /* SOCKS4A: two strings */
1054                 have = buffer_len(&c->input);
1055                 p = buffer_ptr(&c->input);
1056                 len = strlen(p);
1057                 debug2("channel %d: decode socks4a: host %s/%d",
1058                     c->self, p, len);
1059                 len++;                          /* trailing '\0' */
1060                 if (len > have)
1061                         fatal("channel %d: decode socks4a: len %d > have %d",
1062                             c->self, len, have);
1063                 if (len > NI_MAXHOST) {
1064                         error("channel %d: hostname \"%.100s\" too long",
1065                             c->self, p);
1066                         return -1;
1067                 }
1068                 c->path = xstrdup(p);
1069                 buffer_consume(&c->input, len);
1070         }
1071         c->host_port = ntohs(s4_req.dest_port);
1072
1073         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1074             c->self, c->path, c->host_port, s4_req.command);
1075
1076         if (s4_req.command != 1) {
1077                 debug("channel %d: cannot handle: %s cn %d",
1078                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1079                 return -1;
1080         }
1081         s4_rsp.version = 0;                     /* vn: 0 for reply */
1082         s4_rsp.command = 90;                    /* cd: req granted */
1083         s4_rsp.dest_port = 0;                   /* ignored */
1084         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1085         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1086         return 1;
1087 }
1088
1089 /* try to decode a socks5 header */
1090 #define SSH_SOCKS5_AUTHDONE     0x1000
1091 #define SSH_SOCKS5_NOAUTH       0x00
1092 #define SSH_SOCKS5_IPV4         0x01
1093 #define SSH_SOCKS5_DOMAIN       0x03
1094 #define SSH_SOCKS5_IPV6         0x04
1095 #define SSH_SOCKS5_CONNECT      0x01
1096 #define SSH_SOCKS5_SUCCESS      0x00
1097
1098 /* ARGSUSED */
1099 static int
1100 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1101 {
1102         struct {
1103                 u_int8_t version;
1104                 u_int8_t command;
1105                 u_int8_t reserved;
1106                 u_int8_t atyp;
1107         } s5_req, s5_rsp;
1108         u_int16_t dest_port;
1109         u_char *p, dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1110         u_int have, need, i, found, nmethods, addrlen, af;
1111
1112         debug2("channel %d: decode socks5", c->self);
1113         p = buffer_ptr(&c->input);
1114         if (p[0] != 0x05)
1115                 return -1;
1116         have = buffer_len(&c->input);
1117         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1118                 /* format: ver | nmethods | methods */
1119                 if (have < 2)
1120                         return 0;
1121                 nmethods = p[1];
1122                 if (have < nmethods + 2)
1123                         return 0;
1124                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1125                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1126                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1127                                 found = 1;
1128                                 break;
1129                         }
1130                 }
1131                 if (!found) {
1132                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1133                             c->self);
1134                         return -1;
1135                 }
1136                 buffer_consume(&c->input, nmethods + 2);
1137                 buffer_put_char(&c->output, 0x05);              /* version */
1138                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1139                 FD_SET(c->sock, writeset);
1140                 c->flags |= SSH_SOCKS5_AUTHDONE;
1141                 debug2("channel %d: socks5 auth done", c->self);
1142                 return 0;                               /* need more */
1143         }
1144         debug2("channel %d: socks5 post auth", c->self);
1145         if (have < sizeof(s5_req)+1)
1146                 return 0;                       /* need more */
1147         memcpy(&s5_req, p, sizeof(s5_req));
1148         if (s5_req.version != 0x05 ||
1149             s5_req.command != SSH_SOCKS5_CONNECT ||
1150             s5_req.reserved != 0x00) {
1151                 debug2("channel %d: only socks5 connect supported", c->self);
1152                 return -1;
1153         }
1154         switch (s5_req.atyp){
1155         case SSH_SOCKS5_IPV4:
1156                 addrlen = 4;
1157                 af = AF_INET;
1158                 break;
1159         case SSH_SOCKS5_DOMAIN:
1160                 addrlen = p[sizeof(s5_req)];
1161                 af = -1;
1162                 break;
1163         case SSH_SOCKS5_IPV6:
1164                 addrlen = 16;
1165                 af = AF_INET6;
1166                 break;
1167         default:
1168                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1169                 return -1;
1170         }
1171         need = sizeof(s5_req) + addrlen + 2;
1172         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1173                 need++;
1174         if (have < need)
1175                 return 0;
1176         buffer_consume(&c->input, sizeof(s5_req));
1177         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1178                 buffer_consume(&c->input, 1);    /* host string length */
1179         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1180         buffer_get(&c->input, (char *)&dest_port, 2);
1181         dest_addr[addrlen] = '\0';
1182         if (c->path != NULL) {
1183                 xfree(c->path);
1184                 c->path = NULL;
1185         }
1186         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1187                 if (addrlen >= NI_MAXHOST) {
1188                         error("channel %d: dynamic request: socks5 hostname "
1189                             "\"%.100s\" too long", c->self, dest_addr);
1190                         return -1;
1191                 }
1192                 c->path = xstrdup(dest_addr);
1193         } else {
1194                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1195                         return -1;
1196                 c->path = xstrdup(ntop);
1197         }
1198         c->host_port = ntohs(dest_port);
1199
1200         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1201             c->self, c->path, c->host_port, s5_req.command);
1202
1203         s5_rsp.version = 0x05;
1204         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1205         s5_rsp.reserved = 0;                    /* ignored */
1206         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1207         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1208         dest_port = 0;                          /* ignored */
1209
1210         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1211         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1212         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1213         return 1;
1214 }
1215
1216 /* dynamic port forwarding */
1217 static void
1218 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1219 {
1220         u_char *p;
1221         u_int have;
1222         int ret;
1223
1224         have = buffer_len(&c->input);
1225         c->delayed = 0;
1226         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1227         /* buffer_dump(&c->input); */
1228         /* check if the fixed size part of the packet is in buffer. */
1229         if (have < 3) {
1230                 /* need more */
1231                 FD_SET(c->sock, readset);
1232                 return;
1233         }
1234         /* try to guess the protocol */
1235         p = buffer_ptr(&c->input);
1236         switch (p[0]) {
1237         case 0x04:
1238                 ret = channel_decode_socks4(c, readset, writeset);
1239                 break;
1240         case 0x05:
1241                 ret = channel_decode_socks5(c, readset, writeset);
1242                 break;
1243         default:
1244                 ret = -1;
1245                 break;
1246         }
1247         if (ret < 0) {
1248                 chan_mark_dead(c);
1249         } else if (ret == 0) {
1250                 debug2("channel %d: pre_dynamic: need more", c->self);
1251                 /* need more */
1252                 FD_SET(c->sock, readset);
1253         } else {
1254                 /* switch to the next state */
1255                 c->type = SSH_CHANNEL_OPENING;
1256                 port_open_helper(c, "direct-tcpip");
1257         }
1258 }
1259
1260 /* This is our fake X11 server socket. */
1261 /* ARGSUSED */
1262 static void
1263 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1264 {
1265         Channel *nc;
1266         struct sockaddr_storage addr;
1267         int newsock;
1268         socklen_t addrlen;
1269         char buf[16384], *remote_ipaddr;
1270         int remote_port;
1271
1272         if (FD_ISSET(c->sock, readset)) {
1273                 debug("X11 connection requested.");
1274                 addrlen = sizeof(addr);
1275                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1276                 if (c->single_connection) {
1277                         debug2("single_connection: closing X11 listener.");
1278                         channel_close_fd(&c->sock);
1279                         chan_mark_dead(c);
1280                 }
1281                 if (newsock < 0) {
1282                         error("accept: %.100s", strerror(errno));
1283                         return;
1284                 }
1285                 set_nodelay(newsock);
1286                 remote_ipaddr = get_peer_ipaddr(newsock);
1287                 remote_port = get_peer_port(newsock);
1288                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1289                     remote_ipaddr, remote_port);
1290
1291                 nc = channel_new("accepted x11 socket",
1292                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1293                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1294                 if (compat20) {
1295                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1296                         packet_put_cstring("x11");
1297                         packet_put_int(nc->self);
1298                         packet_put_int(nc->local_window_max);
1299                         packet_put_int(nc->local_maxpacket);
1300                         /* originator ipaddr and port */
1301                         packet_put_cstring(remote_ipaddr);
1302                         if (datafellows & SSH_BUG_X11FWD) {
1303                                 debug2("ssh2 x11 bug compat mode");
1304                         } else {
1305                                 packet_put_int(remote_port);
1306                         }
1307                         packet_send();
1308                 } else {
1309                         packet_start(SSH_SMSG_X11_OPEN);
1310                         packet_put_int(nc->self);
1311                         if (packet_get_protocol_flags() &
1312                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1313                                 packet_put_cstring(buf);
1314                         packet_send();
1315                 }
1316                 xfree(remote_ipaddr);
1317         }
1318 }
1319
1320 static void
1321 port_open_helper(Channel *c, char *rtype)
1322 {
1323         int direct;
1324         char buf[1024];
1325         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1326         int remote_port = get_peer_port(c->sock);
1327
1328         direct = (strcmp(rtype, "direct-tcpip") == 0);
1329
1330         snprintf(buf, sizeof buf,
1331             "%s: listening port %d for %.100s port %d, "
1332             "connect from %.200s port %d",
1333             rtype, c->listening_port, c->path, c->host_port,
1334             remote_ipaddr, remote_port);
1335
1336         xfree(c->remote_name);
1337         c->remote_name = xstrdup(buf);
1338
1339         if (compat20) {
1340                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1341                 packet_put_cstring(rtype);
1342                 packet_put_int(c->self);
1343                 packet_put_int(c->local_window_max);
1344                 packet_put_int(c->local_maxpacket);
1345                 if (direct) {
1346                         /* target host, port */
1347                         packet_put_cstring(c->path);
1348                         packet_put_int(c->host_port);
1349                 } else {
1350                         /* listen address, port */
1351                         packet_put_cstring(c->path);
1352                         packet_put_int(c->listening_port);
1353                 }
1354                 /* originator host and port */
1355                 packet_put_cstring(remote_ipaddr);
1356                 packet_put_int((u_int)remote_port);
1357                 packet_send();
1358         } else {
1359                 packet_start(SSH_MSG_PORT_OPEN);
1360                 packet_put_int(c->self);
1361                 packet_put_cstring(c->path);
1362                 packet_put_int(c->host_port);
1363                 if (packet_get_protocol_flags() &
1364                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1365                         packet_put_cstring(c->remote_name);
1366                 packet_send();
1367         }
1368         xfree(remote_ipaddr);
1369 }
1370
1371 static void
1372 channel_set_reuseaddr(int fd)
1373 {
1374         int on = 1;
1375
1376         /*
1377          * Set socket options.
1378          * Allow local port reuse in TIME_WAIT.
1379          */
1380         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1381                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1382 }
1383
1384 /*
1385  * This socket is listening for connections to a forwarded TCP/IP port.
1386  */
1387 /* ARGSUSED */
1388 static void
1389 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1390 {
1391         Channel *nc;
1392         struct sockaddr_storage addr;
1393         int newsock, nextstate;
1394         socklen_t addrlen;
1395         char *rtype;
1396
1397         if (FD_ISSET(c->sock, readset)) {
1398                 debug("Connection to port %d forwarding "
1399                     "to %.100s port %d requested.",
1400                     c->listening_port, c->path, c->host_port);
1401
1402                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1403                         nextstate = SSH_CHANNEL_OPENING;
1404                         rtype = "forwarded-tcpip";
1405                 } else {
1406                         if (c->host_port == 0) {
1407                                 nextstate = SSH_CHANNEL_DYNAMIC;
1408                                 rtype = "dynamic-tcpip";
1409                         } else {
1410                                 nextstate = SSH_CHANNEL_OPENING;
1411                                 rtype = "direct-tcpip";
1412                         }
1413                 }
1414
1415                 addrlen = sizeof(addr);
1416                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1417                 if (newsock < 0) {
1418                         error("accept: %.100s", strerror(errno));
1419                         return;
1420                 }
1421                 set_nodelay(newsock);
1422                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1423                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1424                 nc->listening_port = c->listening_port;
1425                 nc->host_port = c->host_port;
1426                 if (c->path != NULL)
1427                         nc->path = xstrdup(c->path);
1428
1429                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1430                         /*
1431                          * do not call the channel_post handler until
1432                          * this flag has been reset by a pre-handler.
1433                          * otherwise the FD_ISSET calls might overflow
1434                          */
1435                         nc->delayed = 1;
1436                 } else {
1437                         port_open_helper(nc, rtype);
1438                 }
1439         }
1440 }
1441
1442 /*
1443  * This is the authentication agent socket listening for connections from
1444  * clients.
1445  */
1446 /* ARGSUSED */
1447 static void
1448 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1449 {
1450         Channel *nc;
1451         int newsock;
1452         struct sockaddr_storage addr;
1453         socklen_t addrlen;
1454
1455         if (FD_ISSET(c->sock, readset)) {
1456                 addrlen = sizeof(addr);
1457                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1458                 if (newsock < 0) {
1459                         error("accept from auth socket: %.100s", strerror(errno));
1460                         return;
1461                 }
1462                 nc = channel_new("accepted auth socket",
1463                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1464                     c->local_window_max, c->local_maxpacket,
1465                     0, "accepted auth socket", 1);
1466                 if (compat20) {
1467                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1468                         packet_put_cstring("auth-agent@openssh.com");
1469                         packet_put_int(nc->self);
1470                         packet_put_int(c->local_window_max);
1471                         packet_put_int(c->local_maxpacket);
1472                 } else {
1473                         packet_start(SSH_SMSG_AGENT_OPEN);
1474                         packet_put_int(nc->self);
1475                 }
1476                 packet_send();
1477         }
1478 }
1479
1480 /* ARGSUSED */
1481 static void
1482 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1483 {
1484         int err = 0, sock;
1485         socklen_t sz = sizeof(err);
1486
1487         if (FD_ISSET(c->sock, writeset)) {
1488                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1489                         err = errno;
1490                         error("getsockopt SO_ERROR failed");
1491                 }
1492                 if (err == 0) {
1493                         debug("channel %d: connected to %s port %d",
1494                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1495                         channel_connect_ctx_free(&c->connect_ctx);
1496                         c->type = SSH_CHANNEL_OPEN;
1497                         if (compat20) {
1498                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1499                                 packet_put_int(c->remote_id);
1500                                 packet_put_int(c->self);
1501                                 packet_put_int(c->local_window);
1502                                 packet_put_int(c->local_maxpacket);
1503                         } else {
1504                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1505                                 packet_put_int(c->remote_id);
1506                                 packet_put_int(c->self);
1507                         }
1508                 } else {
1509                         debug("channel %d: connection failed: %s",
1510                             c->self, strerror(err));
1511                         /* Try next address, if any */
1512                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1513                                 close(c->sock);
1514                                 c->sock = c->rfd = c->wfd = sock;
1515                                 channel_max_fd = channel_find_maxfd();
1516                                 return;
1517                         }
1518                         /* Exhausted all addresses */
1519                         error("connect_to %.100s port %d: failed.",
1520                             c->connect_ctx.host, c->connect_ctx.port);
1521                         channel_connect_ctx_free(&c->connect_ctx);
1522                         if (compat20) {
1523                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1524                                 packet_put_int(c->remote_id);
1525                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1526                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1527                                         packet_put_cstring(strerror(err));
1528                                         packet_put_cstring("");
1529                                 }
1530                         } else {
1531                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1532                                 packet_put_int(c->remote_id);
1533                         }
1534                         chan_mark_dead(c);
1535                 }
1536                 packet_send();
1537         }
1538 }
1539
1540 /* ARGSUSED */
1541 static int
1542 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1543 {
1544         char buf[CHAN_RBUF];
1545         int len, force;
1546
1547         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1548         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1549                 errno = 0;
1550                 len = read(c->rfd, buf, sizeof(buf));
1551                 if (len < 0 && (errno == EINTR ||
1552                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1553                         return 1;
1554 #ifndef PTY_ZEROREAD
1555                 if (len <= 0) {
1556 #else
1557                 if ((!c->isatty && len <= 0) ||
1558                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1559 #endif
1560                         debug2("channel %d: read<=0 rfd %d len %d",
1561                             c->self, c->rfd, len);
1562                         if (c->type != SSH_CHANNEL_OPEN) {
1563                                 debug2("channel %d: not open", c->self);
1564                                 chan_mark_dead(c);
1565                                 return -1;
1566                         } else if (compat13) {
1567                                 buffer_clear(&c->output);
1568                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1569                                 debug2("channel %d: input draining.", c->self);
1570                         } else {
1571                                 chan_read_failed(c);
1572                         }
1573                         return -1;
1574                 }
1575                 if (c->input_filter != NULL) {
1576                         if (c->input_filter(c, buf, len) == -1) {
1577                                 debug2("channel %d: filter stops", c->self);
1578                                 chan_read_failed(c);
1579                         }
1580                 } else if (c->datagram) {
1581                         buffer_put_string(&c->input, buf, len);
1582                 } else {
1583                         buffer_append(&c->input, buf, len);
1584                 }
1585         }
1586         return 1;
1587 }
1588
1589 /* ARGSUSED */
1590 static int
1591 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1592 {
1593         struct termios tio;
1594         u_char *data = NULL, *buf;
1595         u_int dlen;
1596         int len;
1597
1598         /* Send buffered output data to the socket. */
1599         if (c->wfd != -1 &&
1600             FD_ISSET(c->wfd, writeset) &&
1601             buffer_len(&c->output) > 0) {
1602                 if (c->output_filter != NULL) {
1603                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1604                                 debug2("channel %d: filter stops", c->self);
1605                                 if (c->type != SSH_CHANNEL_OPEN)
1606                                         chan_mark_dead(c);
1607                                 else
1608                                         chan_write_failed(c);
1609                                 return -1;
1610                         }
1611                 } else if (c->datagram) {
1612                         buf = data = buffer_get_string(&c->output, &dlen);
1613                 } else {
1614                         buf = data = buffer_ptr(&c->output);
1615                         dlen = buffer_len(&c->output);
1616                 }
1617
1618                 if (c->datagram) {
1619                         /* ignore truncated writes, datagrams might get lost */
1620                         c->local_consumed += dlen + 4;
1621                         len = write(c->wfd, buf, dlen);
1622                         xfree(data);
1623                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1624                             errno == EWOULDBLOCK))
1625                                 return 1;
1626                         if (len <= 0) {
1627                                 if (c->type != SSH_CHANNEL_OPEN)
1628                                         chan_mark_dead(c);
1629                                 else
1630                                         chan_write_failed(c);
1631                                 return -1;
1632                         }
1633                         return 1;
1634                 }
1635 #ifdef _AIX
1636                 /* XXX: Later AIX versions can't push as much data to tty */
1637                 if (compat20 && c->wfd_isatty)
1638                         dlen = MIN(dlen, 8*1024);
1639 #endif
1640
1641                 len = write(c->wfd, buf, dlen);
1642                 if (len < 0 &&
1643                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1644                         return 1;
1645                 if (len <= 0) {
1646                         if (c->type != SSH_CHANNEL_OPEN) {
1647                                 debug2("channel %d: not open", c->self);
1648                                 chan_mark_dead(c);
1649                                 return -1;
1650                         } else if (compat13) {
1651                                 buffer_clear(&c->output);
1652                                 debug2("channel %d: input draining.", c->self);
1653                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1654                         } else {
1655                                 chan_write_failed(c);
1656                         }
1657                         return -1;
1658                 }
1659 #ifndef BROKEN_TCGETATTR_ICANON
1660                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1661                         if (tcgetattr(c->wfd, &tio) == 0 &&
1662                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1663                                 /*
1664                                  * Simulate echo to reduce the impact of
1665                                  * traffic analysis. We need to match the
1666                                  * size of a SSH2_MSG_CHANNEL_DATA message
1667                                  * (4 byte channel id + buf)
1668                                  */
1669                                 packet_send_ignore(4 + len);
1670                                 packet_send();
1671                         }
1672                 }
1673 #endif
1674                 buffer_consume(&c->output, len);
1675                 if (compat20 && len > 0) {
1676                         c->local_consumed += len;
1677                 }
1678         }
1679         return 1;
1680 }
1681
1682 static int
1683 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1684 {
1685         char buf[CHAN_RBUF];
1686         int len;
1687
1688 /** XXX handle drain efd, too */
1689         if (c->efd != -1) {
1690                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1691                     FD_ISSET(c->efd, writeset) &&
1692                     buffer_len(&c->extended) > 0) {
1693                         len = write(c->efd, buffer_ptr(&c->extended),
1694                             buffer_len(&c->extended));
1695                         debug2("channel %d: written %d to efd %d",
1696                             c->self, len, c->efd);
1697                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1698                             errno == EWOULDBLOCK))
1699                                 return 1;
1700                         if (len <= 0) {
1701                                 debug2("channel %d: closing write-efd %d",
1702                                     c->self, c->efd);
1703                                 channel_close_fd(&c->efd);
1704                         } else {
1705                                 buffer_consume(&c->extended, len);
1706                                 c->local_consumed += len;
1707                         }
1708                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1709                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1710                         len = read(c->efd, buf, sizeof(buf));
1711                         debug2("channel %d: read %d from efd %d",
1712                             c->self, len, c->efd);
1713                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1714                             errno == EWOULDBLOCK) && !c->detach_close)))
1715                                 return 1;
1716                         if (len <= 0) {
1717                                 debug2("channel %d: closing read-efd %d",
1718                                     c->self, c->efd);
1719                                 channel_close_fd(&c->efd);
1720                         } else {
1721                                 buffer_append(&c->extended, buf, len);
1722                         }
1723                 }
1724         }
1725         return 1;
1726 }
1727
1728 /* ARGSUSED */
1729 static int
1730 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1731 {
1732         char buf[16];
1733         int len;
1734
1735         /* Monitor control fd to detect if the slave client exits */
1736         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1737                 len = read(c->ctl_fd, buf, sizeof(buf));
1738                 if (len < 0 &&
1739                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1740                         return 1;
1741                 if (len <= 0) {
1742                         debug2("channel %d: ctl read<=0", c->self);
1743                         if (c->type != SSH_CHANNEL_OPEN) {
1744                                 debug2("channel %d: not open", c->self);
1745                                 chan_mark_dead(c);
1746                                 return -1;
1747                         } else {
1748                                 chan_read_failed(c);
1749                                 chan_write_failed(c);
1750                         }
1751                         return -1;
1752                 } else
1753                         fatal("%s: unexpected data on ctl fd", __func__);
1754         }
1755         return 1;
1756 }
1757
1758 static int
1759 channel_check_window(Channel *c)
1760 {
1761         if (c->type == SSH_CHANNEL_OPEN &&
1762             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1763             ((c->local_window_max - c->local_window >
1764             c->local_maxpacket*3) ||
1765             c->local_window < c->local_window_max/2) &&
1766             c->local_consumed > 0) {
1767                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1768                 packet_put_int(c->remote_id);
1769                 packet_put_int(c->local_consumed);
1770                 packet_send();
1771                 debug2("channel %d: window %d sent adjust %d",
1772                     c->self, c->local_window,
1773                     c->local_consumed);
1774                 c->local_window += c->local_consumed;
1775                 c->local_consumed = 0;
1776         }
1777         return 1;
1778 }
1779
1780 static void
1781 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1782 {
1783         if (c->delayed)
1784                 return;
1785         channel_handle_rfd(c, readset, writeset);
1786         channel_handle_wfd(c, readset, writeset);
1787         if (!compat20)
1788                 return;
1789         channel_handle_efd(c, readset, writeset);
1790         channel_handle_ctl(c, readset, writeset);
1791         channel_check_window(c);
1792 }
1793
1794 /* ARGSUSED */
1795 static void
1796 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1797 {
1798         int len;
1799
1800         /* Send buffered output data to the socket. */
1801         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1802                 len = write(c->sock, buffer_ptr(&c->output),
1803                             buffer_len(&c->output));
1804                 if (len <= 0)
1805                         buffer_clear(&c->output);
1806                 else
1807                         buffer_consume(&c->output, len);
1808         }
1809 }
1810
1811 static void
1812 channel_handler_init_20(void)
1813 {
1814         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1815         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1816         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1817         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1818         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1819         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1820         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1821         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1822
1823         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1824         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1825         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1826         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1827         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1828         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1829         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1830 }
1831
1832 static void
1833 channel_handler_init_13(void)
1834 {
1835         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1836         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1837         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1838         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1839         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1840         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1841         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1842         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1843         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1844
1845         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1846         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1847         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1848         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1849         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1850         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1851         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1852 }
1853
1854 static void
1855 channel_handler_init_15(void)
1856 {
1857         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1858         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1859         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1860         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1861         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1862         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1863         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1864
1865         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1866         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1867         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1868         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1869         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1870         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1871 }
1872
1873 static void
1874 channel_handler_init(void)
1875 {
1876         int i;
1877
1878         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1879                 channel_pre[i] = NULL;
1880                 channel_post[i] = NULL;
1881         }
1882         if (compat20)
1883                 channel_handler_init_20();
1884         else if (compat13)
1885                 channel_handler_init_13();
1886         else
1887                 channel_handler_init_15();
1888 }
1889
1890 /* gc dead channels */
1891 static void
1892 channel_garbage_collect(Channel *c)
1893 {
1894         if (c == NULL)
1895                 return;
1896         if (c->detach_user != NULL) {
1897                 if (!chan_is_dead(c, c->detach_close))
1898                         return;
1899                 debug2("channel %d: gc: notify user", c->self);
1900                 c->detach_user(c->self, NULL);
1901                 /* if we still have a callback */
1902                 if (c->detach_user != NULL)
1903                         return;
1904                 debug2("channel %d: gc: user detached", c->self);
1905         }
1906         if (!chan_is_dead(c, 1))
1907                 return;
1908         debug2("channel %d: garbage collecting", c->self);
1909         channel_free(c);
1910 }
1911
1912 static void
1913 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1914 {
1915         static int did_init = 0;
1916         u_int i;
1917         Channel *c;
1918
1919         if (!did_init) {
1920                 channel_handler_init();
1921                 did_init = 1;
1922         }
1923         for (i = 0; i < channels_alloc; i++) {
1924                 c = channels[i];
1925                 if (c == NULL)
1926                         continue;
1927                 if (ftab[c->type] != NULL)
1928                         (*ftab[c->type])(c, readset, writeset);
1929                 channel_garbage_collect(c);
1930         }
1931 }
1932
1933 /*
1934  * Allocate/update select bitmasks and add any bits relevant to channels in
1935  * select bitmasks.
1936  */
1937 void
1938 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1939     u_int *nallocp, int rekeying)
1940 {
1941         u_int n, sz, nfdset;
1942
1943         n = MAX(*maxfdp, channel_max_fd);
1944
1945         nfdset = howmany(n+1, NFDBITS);
1946         /* Explicitly test here, because xrealloc isn't always called */
1947         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1948                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1949         sz = nfdset * sizeof(fd_mask);
1950
1951         /* perhaps check sz < nalloc/2 and shrink? */
1952         if (*readsetp == NULL || sz > *nallocp) {
1953                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1954                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1955                 *nallocp = sz;
1956         }
1957         *maxfdp = n;
1958         memset(*readsetp, 0, sz);
1959         memset(*writesetp, 0, sz);
1960
1961         if (!rekeying)
1962                 channel_handler(channel_pre, *readsetp, *writesetp);
1963 }
1964
1965 /*
1966  * After select, perform any appropriate operations for channels which have
1967  * events pending.
1968  */
1969 void
1970 channel_after_select(fd_set *readset, fd_set *writeset)
1971 {
1972         channel_handler(channel_post, readset, writeset);
1973 }
1974
1975
1976 /* If there is data to send to the connection, enqueue some of it now. */
1977 void
1978 channel_output_poll(void)
1979 {
1980         Channel *c;
1981         u_int i, len;
1982
1983         for (i = 0; i < channels_alloc; i++) {
1984                 c = channels[i];
1985                 if (c == NULL)
1986                         continue;
1987
1988                 /*
1989                  * We are only interested in channels that can have buffered
1990                  * incoming data.
1991                  */
1992                 if (compat13) {
1993                         if (c->type != SSH_CHANNEL_OPEN &&
1994                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1995                                 continue;
1996                 } else {
1997                         if (c->type != SSH_CHANNEL_OPEN)
1998                                 continue;
1999                 }
2000                 if (compat20 &&
2001                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2002                         /* XXX is this true? */
2003                         debug3("channel %d: will not send data after close", c->self);
2004                         continue;
2005                 }
2006
2007                 /* Get the amount of buffered data for this channel. */
2008                 if ((c->istate == CHAN_INPUT_OPEN ||
2009                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2010                     (len = buffer_len(&c->input)) > 0) {
2011                         if (c->datagram) {
2012                                 if (len > 0) {
2013                                         u_char *data;
2014                                         u_int dlen;
2015
2016                                         data = buffer_get_string(&c->input,
2017                                             &dlen);
2018                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2019                                         packet_put_int(c->remote_id);
2020                                         packet_put_string(data, dlen);
2021                                         packet_send();
2022                                         c->remote_window -= dlen + 4;
2023                                         xfree(data);
2024                                 }
2025                                 continue;
2026                         }
2027                         /*
2028                          * Send some data for the other side over the secure
2029                          * connection.
2030                          */
2031                         if (compat20) {
2032                                 if (len > c->remote_window)
2033                                         len = c->remote_window;
2034                                 if (len > c->remote_maxpacket)
2035                                         len = c->remote_maxpacket;
2036                         } else {
2037                                 if (packet_is_interactive()) {
2038                                         if (len > 1024)
2039                                                 len = 512;
2040                                 } else {
2041                                         /* Keep the packets at reasonable size. */
2042                                         if (len > packet_get_maxsize()/2)
2043                                                 len = packet_get_maxsize()/2;
2044                                 }
2045                         }
2046                         if (len > 0) {
2047                                 packet_start(compat20 ?
2048                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2049                                 packet_put_int(c->remote_id);
2050                                 packet_put_string(buffer_ptr(&c->input), len);
2051                                 packet_send();
2052                                 buffer_consume(&c->input, len);
2053                                 c->remote_window -= len;
2054                         }
2055                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2056                         if (compat13)
2057                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2058                         /*
2059                          * input-buffer is empty and read-socket shutdown:
2060                          * tell peer, that we will not send more data: send IEOF.
2061                          * hack for extended data: delay EOF if EFD still in use.
2062                          */
2063                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2064                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2065                                     c->self, c->efd, buffer_len(&c->extended));
2066                         else
2067                                 chan_ibuf_empty(c);
2068                 }
2069                 /* Send extended data, i.e. stderr */
2070                 if (compat20 &&
2071                     !(c->flags & CHAN_EOF_SENT) &&
2072                     c->remote_window > 0 &&
2073                     (len = buffer_len(&c->extended)) > 0 &&
2074                     c->extended_usage == CHAN_EXTENDED_READ) {
2075                         debug2("channel %d: rwin %u elen %u euse %d",
2076                             c->self, c->remote_window, buffer_len(&c->extended),
2077                             c->extended_usage);
2078                         if (len > c->remote_window)
2079                                 len = c->remote_window;
2080                         if (len > c->remote_maxpacket)
2081                                 len = c->remote_maxpacket;
2082                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2083                         packet_put_int(c->remote_id);
2084                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2085                         packet_put_string(buffer_ptr(&c->extended), len);
2086                         packet_send();
2087                         buffer_consume(&c->extended, len);
2088                         c->remote_window -= len;
2089                         debug2("channel %d: sent ext data %d", c->self, len);
2090                 }
2091         }
2092 }
2093
2094
2095 /* -- protocol input */
2096
2097 /* ARGSUSED */
2098 void
2099 channel_input_data(int type, u_int32_t seq, void *ctxt)
2100 {
2101         int id;
2102         char *data;
2103         u_int data_len;
2104         Channel *c;
2105
2106         /* Get the channel number and verify it. */
2107         id = packet_get_int();
2108         c = channel_lookup(id);
2109         if (c == NULL)
2110                 packet_disconnect("Received data for nonexistent channel %d.", id);
2111
2112         /* Ignore any data for non-open channels (might happen on close) */
2113         if (c->type != SSH_CHANNEL_OPEN &&
2114             c->type != SSH_CHANNEL_X11_OPEN)
2115                 return;
2116
2117         /* Get the data. */
2118         data = packet_get_string_ptr(&data_len);
2119
2120         /*
2121          * Ignore data for protocol > 1.3 if output end is no longer open.
2122          * For protocol 2 the sending side is reducing its window as it sends
2123          * data, so we must 'fake' consumption of the data in order to ensure
2124          * that window updates are sent back.  Otherwise the connection might
2125          * deadlock.
2126          */
2127         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2128                 if (compat20) {
2129                         c->local_window -= data_len;
2130                         c->local_consumed += data_len;
2131                 }
2132                 return;
2133         }
2134
2135         if (compat20) {
2136                 if (data_len > c->local_maxpacket) {
2137                         logit("channel %d: rcvd big packet %d, maxpack %d",
2138                             c->self, data_len, c->local_maxpacket);
2139                 }
2140                 if (data_len > c->local_window) {
2141                         logit("channel %d: rcvd too much data %d, win %d",
2142                             c->self, data_len, c->local_window);
2143                         return;
2144                 }
2145                 c->local_window -= data_len;
2146         }
2147         if (c->datagram)
2148                 buffer_put_string(&c->output, data, data_len);
2149         else
2150                 buffer_append(&c->output, data, data_len);
2151         packet_check_eom();
2152 }
2153
2154 /* ARGSUSED */
2155 void
2156 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2157 {
2158         int id;
2159         char *data;
2160         u_int data_len, tcode;
2161         Channel *c;
2162
2163         /* Get the channel number and verify it. */
2164         id = packet_get_int();
2165         c = channel_lookup(id);
2166
2167         if (c == NULL)
2168                 packet_disconnect("Received extended_data for bad channel %d.", id);
2169         if (c->type != SSH_CHANNEL_OPEN) {
2170                 logit("channel %d: ext data for non open", id);
2171                 return;
2172         }
2173         if (c->flags & CHAN_EOF_RCVD) {
2174                 if (datafellows & SSH_BUG_EXTEOF)
2175                         debug("channel %d: accepting ext data after eof", id);
2176                 else
2177                         packet_disconnect("Received extended_data after EOF "
2178                             "on channel %d.", id);
2179         }
2180         tcode = packet_get_int();
2181         if (c->efd == -1 ||
2182             c->extended_usage != CHAN_EXTENDED_WRITE ||
2183             tcode != SSH2_EXTENDED_DATA_STDERR) {
2184                 logit("channel %d: bad ext data", c->self);
2185                 return;
2186         }
2187         data = packet_get_string(&data_len);
2188         packet_check_eom();
2189         if (data_len > c->local_window) {
2190                 logit("channel %d: rcvd too much extended_data %d, win %d",
2191                     c->self, data_len, c->local_window);
2192                 xfree(data);
2193                 return;
2194         }
2195         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2196         c->local_window -= data_len;
2197         buffer_append(&c->extended, data, data_len);
2198         xfree(data);
2199 }
2200
2201 /* ARGSUSED */
2202 void
2203 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2204 {
2205         int id;
2206         Channel *c;
2207
2208         id = packet_get_int();
2209         packet_check_eom();
2210         c = channel_lookup(id);
2211         if (c == NULL)
2212                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2213         chan_rcvd_ieof(c);
2214
2215         /* XXX force input close */
2216         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2217                 debug("channel %d: FORCE input drain", c->self);
2218                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2219                 if (buffer_len(&c->input) == 0)
2220                         chan_ibuf_empty(c);
2221         }
2222
2223 }
2224
2225 /* ARGSUSED */
2226 void
2227 channel_input_close(int type, u_int32_t seq, void *ctxt)
2228 {
2229         int id;
2230         Channel *c;
2231
2232         id = packet_get_int();
2233         packet_check_eom();
2234         c = channel_lookup(id);
2235         if (c == NULL)
2236                 packet_disconnect("Received close for nonexistent channel %d.", id);
2237
2238         /*
2239          * Send a confirmation that we have closed the channel and no more
2240          * data is coming for it.
2241          */
2242         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2243         packet_put_int(c->remote_id);
2244         packet_send();
2245
2246         /*
2247          * If the channel is in closed state, we have sent a close request,
2248          * and the other side will eventually respond with a confirmation.
2249          * Thus, we cannot free the channel here, because then there would be
2250          * no-one to receive the confirmation.  The channel gets freed when
2251          * the confirmation arrives.
2252          */
2253         if (c->type != SSH_CHANNEL_CLOSED) {
2254                 /*
2255                  * Not a closed channel - mark it as draining, which will
2256                  * cause it to be freed later.
2257                  */
2258                 buffer_clear(&c->input);
2259                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2260         }
2261 }
2262
2263 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2264 /* ARGSUSED */
2265 void
2266 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2267 {
2268         int id = packet_get_int();
2269         Channel *c = channel_lookup(id);
2270
2271         packet_check_eom();
2272         if (c == NULL)
2273                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2274         chan_rcvd_oclose(c);
2275 }
2276
2277 /* ARGSUSED */
2278 void
2279 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2280 {
2281         int id = packet_get_int();
2282         Channel *c = channel_lookup(id);
2283
2284         packet_check_eom();
2285         if (c == NULL)
2286                 packet_disconnect("Received close confirmation for "
2287                     "out-of-range channel %d.", id);
2288         if (c->type != SSH_CHANNEL_CLOSED)
2289                 packet_disconnect("Received close confirmation for "
2290                     "non-closed channel %d (type %d).", id, c->type);
2291         channel_free(c);
2292 }
2293
2294 /* ARGSUSED */
2295 void
2296 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2297 {
2298         int id, remote_id;
2299         Channel *c;
2300
2301         id = packet_get_int();
2302         c = channel_lookup(id);
2303
2304         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2305                 packet_disconnect("Received open confirmation for "
2306                     "non-opening channel %d.", id);
2307         remote_id = packet_get_int();
2308         /* Record the remote channel number and mark that the channel is now open. */
2309         c->remote_id = remote_id;
2310         c->type = SSH_CHANNEL_OPEN;
2311
2312         if (compat20) {
2313                 c->remote_window = packet_get_int();
2314                 c->remote_maxpacket = packet_get_int();
2315                 if (c->open_confirm) {
2316                         debug2("callback start");
2317                         c->open_confirm(c->self, c->open_confirm_ctx);
2318                         debug2("callback done");
2319                 }
2320                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2321                     c->remote_window, c->remote_maxpacket);
2322         }
2323         packet_check_eom();
2324 }
2325
2326 static char *
2327 reason2txt(int reason)
2328 {
2329         switch (reason) {
2330         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2331                 return "administratively prohibited";
2332         case SSH2_OPEN_CONNECT_FAILED:
2333                 return "connect failed";
2334         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2335                 return "unknown channel type";
2336         case SSH2_OPEN_RESOURCE_SHORTAGE:
2337                 return "resource shortage";
2338         }
2339         return "unknown reason";
2340 }
2341
2342 /* ARGSUSED */
2343 void
2344 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2345 {
2346         int id, reason;
2347         char *msg = NULL, *lang = NULL;
2348         Channel *c;
2349
2350         id = packet_get_int();
2351         c = channel_lookup(id);
2352
2353         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2354                 packet_disconnect("Received open failure for "
2355                     "non-opening channel %d.", id);
2356         if (compat20) {
2357                 reason = packet_get_int();
2358                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2359                         msg  = packet_get_string(NULL);
2360                         lang = packet_get_string(NULL);
2361                 }
2362                 logit("channel %d: open failed: %s%s%s", id,
2363                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2364                 if (msg != NULL)
2365                         xfree(msg);
2366                 if (lang != NULL)
2367                         xfree(lang);
2368         }
2369         packet_check_eom();
2370         /* Schedule the channel for cleanup/deletion. */
2371         chan_mark_dead(c);
2372 }
2373
2374 /* ARGSUSED */
2375 void
2376 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2377 {
2378         Channel *c;
2379         int id;
2380         u_int adjust;
2381
2382         if (!compat20)
2383                 return;
2384
2385         /* Get the channel number and verify it. */
2386         id = packet_get_int();
2387         c = channel_lookup(id);
2388
2389         if (c == NULL) {
2390                 logit("Received window adjust for non-open channel %d.", id);
2391                 return;
2392         }
2393         adjust = packet_get_int();
2394         packet_check_eom();
2395         debug2("channel %d: rcvd adjust %u", id, adjust);
2396         c->remote_window += adjust;
2397 }
2398
2399 /* ARGSUSED */
2400 void
2401 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2402 {
2403         Channel *c = NULL;
2404         u_short host_port;
2405         char *host, *originator_string;
2406         int remote_id;
2407
2408         remote_id = packet_get_int();
2409         host = packet_get_string(NULL);
2410         host_port = packet_get_int();
2411
2412         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2413                 originator_string = packet_get_string(NULL);
2414         } else {
2415                 originator_string = xstrdup("unknown (remote did not supply name)");
2416         }
2417         packet_check_eom();
2418         c = channel_connect_to(host, host_port,
2419             "connected socket", originator_string);
2420         xfree(originator_string);
2421         xfree(host);
2422         if (c == NULL) {
2423                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2424                 packet_put_int(remote_id);
2425                 packet_send();
2426         } else
2427                 c->remote_id = remote_id;
2428 }
2429
2430 /* ARGSUSED */
2431 void
2432 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2433 {
2434         Channel *c;
2435         struct channel_confirm *cc;
2436         int id;
2437
2438         /* Reset keepalive timeout */
2439         packet_set_alive_timeouts(0);
2440
2441         id = packet_get_int();
2442         packet_check_eom();
2443
2444         debug2("channel_input_status_confirm: type %d id %d", type, id);
2445
2446         if ((c = channel_lookup(id)) == NULL) {
2447                 logit("channel_input_status_confirm: %d: unknown", id);
2448                 return;
2449         }
2450         ;
2451         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2452                 return;
2453         cc->cb(type, c, cc->ctx);
2454         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2455         bzero(cc, sizeof(*cc));
2456         xfree(cc);
2457 }
2458
2459 /* -- tcp forwarding */
2460
2461 void
2462 channel_set_af(int af)
2463 {
2464         IPv4or6 = af;
2465 }
2466
2467 void
2468 channel_set_rdomain(int rdomain)
2469 {
2470         channel_rdomain = rdomain;
2471 }
2472
2473 static int
2474 channel_setup_fwd_listener(int type, const char *listen_addr,
2475     u_short listen_port, int *allocated_listen_port,
2476     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2477 {
2478         Channel *c;
2479         int sock, r, success = 0, wildcard = 0, is_client;
2480         struct addrinfo hints, *ai, *aitop;
2481         const char *host, *addr;
2482         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2483         in_port_t *lport_p;
2484
2485         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2486             listen_addr : host_to_connect;
2487         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2488
2489         if (host == NULL) {
2490                 error("No forward host name.");
2491                 return 0;
2492         }
2493         if (strlen(host) >= NI_MAXHOST) {
2494                 error("Forward host name too long.");
2495                 return 0;
2496         }
2497
2498         /*
2499          * Determine whether or not a port forward listens to loopback,
2500          * specified address or wildcard. On the client, a specified bind
2501          * address will always override gateway_ports. On the server, a
2502          * gateway_ports of 1 (``yes'') will override the client's
2503          * specification and force a wildcard bind, whereas a value of 2
2504          * (``clientspecified'') will bind to whatever address the client
2505          * asked for.
2506          *
2507          * Special-case listen_addrs are:
2508          *
2509          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2510          * "" (empty string), "*"  -> wildcard v4/v6
2511          * "localhost"             -> loopback v4/v6
2512          */
2513         addr = NULL;
2514         if (listen_addr == NULL) {
2515                 /* No address specified: default to gateway_ports setting */
2516                 if (gateway_ports)
2517                         wildcard = 1;
2518         } else if (gateway_ports || is_client) {
2519                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2520                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2521                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2522                     (!is_client && gateway_ports == 1))
2523                         wildcard = 1;
2524                 else if (strcmp(listen_addr, "localhost") != 0)
2525                         addr = listen_addr;
2526         }
2527
2528         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2529             type, wildcard, (addr == NULL) ? "NULL" : addr);
2530
2531         /*
2532          * getaddrinfo returns a loopback address if the hostname is
2533          * set to NULL and hints.ai_flags is not AI_PASSIVE
2534          */
2535         memset(&hints, 0, sizeof(hints));
2536         hints.ai_family = IPv4or6;
2537         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2538         hints.ai_socktype = SOCK_STREAM;
2539         snprintf(strport, sizeof strport, "%d", listen_port);
2540         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2541                 if (addr == NULL) {
2542                         /* This really shouldn't happen */
2543                         packet_disconnect("getaddrinfo: fatal error: %s",
2544                             ssh_gai_strerror(r));
2545                 } else {
2546                         error("channel_setup_fwd_listener: "
2547                             "getaddrinfo(%.64s): %s", addr,
2548                             ssh_gai_strerror(r));
2549                 }
2550                 return 0;
2551         }
2552         if (allocated_listen_port != NULL)
2553                 *allocated_listen_port = 0;
2554         for (ai = aitop; ai; ai = ai->ai_next) {
2555                 switch (ai->ai_family) {
2556                 case AF_INET:
2557                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2558                             sin_port;
2559                         break;
2560                 case AF_INET6:
2561                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2562                             sin6_port;
2563                         break;
2564                 default:
2565                         continue;
2566                 }
2567                 /*
2568                  * If allocating a port for -R forwards, then use the
2569                  * same port for all address families.
2570                  */
2571                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2572                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2573                         *lport_p = htons(*allocated_listen_port);
2574
2575                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2576                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2577                         error("channel_setup_fwd_listener: getnameinfo failed");
2578                         continue;
2579                 }
2580                 /* Create a port to listen for the host. */
2581                 sock = socket_rdomain(ai->ai_family, ai->ai_socktype,
2582                     ai->ai_protocol, channel_rdomain);
2583                 if (sock < 0) {
2584                         /* this is no error since kernel may not support ipv6 */
2585                         verbose("socket: %.100s", strerror(errno));
2586                         continue;
2587                 }
2588
2589                 channel_set_reuseaddr(sock);
2590                 if (ai->ai_family == AF_INET6)
2591                         sock_set_v6only(sock);
2592
2593                 debug("Local forwarding listening on %s port %s.",
2594                     ntop, strport);
2595
2596                 /* Bind the socket to the address. */
2597                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2598                         /* address can be in use ipv6 address is already bound */
2599                         if (!ai->ai_next)
2600                                 error("bind: %.100s", strerror(errno));
2601                         else
2602                                 verbose("bind: %.100s", strerror(errno));
2603
2604                         close(sock);
2605                         continue;
2606                 }
2607                 /* Start listening for connections on the socket. */
2608                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2609                         error("listen: %.100s", strerror(errno));
2610                         close(sock);
2611                         continue;
2612                 }
2613
2614                 /*
2615                  * listen_port == 0 requests a dynamically allocated port -
2616                  * record what we got.
2617                  */
2618                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2619                     allocated_listen_port != NULL &&
2620                     *allocated_listen_port == 0) {
2621                         *allocated_listen_port = get_sock_port(sock, 1);
2622                         debug("Allocated listen port %d",
2623                             *allocated_listen_port);
2624                 }
2625
2626                 /* Allocate a channel number for the socket. */
2627                 c = channel_new("port listener", type, sock, sock, -1,
2628                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2629                     0, "port listener", 1);
2630                 c->path = xstrdup(host);
2631                 c->host_port = port_to_connect;
2632                 c->listening_port = listen_port;
2633                 success = 1;
2634         }
2635         if (success == 0)
2636                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2637                     listen_port);
2638         freeaddrinfo(aitop);
2639         return success;
2640 }
2641
2642 int
2643 channel_cancel_rport_listener(const char *host, u_short port)
2644 {
2645         u_int i;
2646         int found = 0;
2647
2648         for (i = 0; i < channels_alloc; i++) {
2649                 Channel *c = channels[i];
2650
2651                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2652                     strcmp(c->path, host) == 0 && c->listening_port == port) {
2653                         debug2("%s: close channel %d", __func__, i);
2654                         channel_free(c);
2655                         found = 1;
2656                 }
2657         }
2658
2659         return (found);
2660 }
2661
2662 /* protocol local port fwd, used by ssh (and sshd in v1) */
2663 int
2664 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2665     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2666 {
2667         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2668             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2669             gateway_ports);
2670 }
2671
2672 /* protocol v2 remote port fwd, used by sshd */
2673 int
2674 channel_setup_remote_fwd_listener(const char *listen_address,
2675     u_short listen_port, int *allocated_listen_port, int gateway_ports)
2676 {
2677         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2678             listen_address, listen_port, allocated_listen_port,
2679             NULL, 0, gateway_ports);
2680 }
2681
2682 /*
2683  * Initiate forwarding of connections to port "port" on remote host through
2684  * the secure channel to host:port from local side.
2685  */
2686
2687 int
2688 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2689     const char *host_to_connect, u_short port_to_connect)
2690 {
2691         int type, success = 0;
2692
2693         /* Record locally that connection to this host/port is permitted. */
2694         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2695                 fatal("channel_request_remote_forwarding: too many forwards");
2696
2697         /* Send the forward request to the remote side. */
2698         if (compat20) {
2699                 const char *address_to_bind;
2700                 if (listen_host == NULL) {
2701                         if (datafellows & SSH_BUG_RFWD_ADDR)
2702                                 address_to_bind = "127.0.0.1";
2703                         else
2704                                 address_to_bind = "localhost";
2705                 } else if (*listen_host == '\0' ||
2706                            strcmp(listen_host, "*") == 0) {
2707                         if (datafellows & SSH_BUG_RFWD_ADDR)
2708                                 address_to_bind = "0.0.0.0";
2709                         else
2710                                 address_to_bind = "";
2711                 } else
2712                         address_to_bind = listen_host;
2713
2714                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2715                 packet_put_cstring("tcpip-forward");
2716                 packet_put_char(1);                     /* boolean: want reply */
2717                 packet_put_cstring(address_to_bind);
2718                 packet_put_int(listen_port);
2719                 packet_send();
2720                 packet_write_wait();
2721                 /* Assume that server accepts the request */
2722                 success = 1;
2723         } else {
2724                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2725                 packet_put_int(listen_port);
2726                 packet_put_cstring(host_to_connect);
2727                 packet_put_int(port_to_connect);
2728                 packet_send();
2729                 packet_write_wait();
2730
2731                 /* Wait for response from the remote side. */
2732                 type = packet_read();
2733                 switch (type) {
2734                 case SSH_SMSG_SUCCESS:
2735                         success = 1;
2736                         break;
2737                 case SSH_SMSG_FAILURE:
2738                         break;
2739                 default:
2740                         /* Unknown packet */
2741                         packet_disconnect("Protocol error for port forward request:"
2742                             "received packet type %d.", type);
2743                 }
2744         }
2745         if (success) {
2746                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2747                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2748                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2749                 num_permitted_opens++;
2750         }
2751         return (success ? 0 : -1);
2752 }
2753
2754 /*
2755  * Request cancellation of remote forwarding of connection host:port from
2756  * local side.
2757  */
2758 void
2759 channel_request_rforward_cancel(const char *host, u_short port)
2760 {
2761         int i;
2762
2763         if (!compat20)
2764                 return;
2765
2766         for (i = 0; i < num_permitted_opens; i++) {
2767                 if (permitted_opens[i].host_to_connect != NULL &&
2768                     permitted_opens[i].listen_port == port)
2769                         break;
2770         }
2771         if (i >= num_permitted_opens) {
2772                 debug("%s: requested forward not found", __func__);
2773                 return;
2774         }
2775         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2776         packet_put_cstring("cancel-tcpip-forward");
2777         packet_put_char(0);
2778         packet_put_cstring(host == NULL ? "" : host);
2779         packet_put_int(port);
2780         packet_send();
2781
2782         permitted_opens[i].listen_port = 0;
2783         permitted_opens[i].port_to_connect = 0;
2784         xfree(permitted_opens[i].host_to_connect);
2785         permitted_opens[i].host_to_connect = NULL;
2786 }
2787
2788 /*
2789  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2790  * listening for the port, and sends back a success reply (or disconnect
2791  * message if there was an error).
2792  */
2793 int
2794 channel_input_port_forward_request(int is_root, int gateway_ports)
2795 {
2796         u_short port, host_port;
2797         int success = 0;
2798         char *hostname;
2799
2800         /* Get arguments from the packet. */
2801         port = packet_get_int();
2802         hostname = packet_get_string(NULL);
2803         host_port = packet_get_int();
2804
2805 #ifndef HAVE_CYGWIN
2806         /*
2807          * Check that an unprivileged user is not trying to forward a
2808          * privileged port.
2809          */
2810         if (port < IPPORT_RESERVED && !is_root)
2811                 packet_disconnect(
2812                     "Requested forwarding of port %d but user is not root.",
2813                     port);
2814         if (host_port == 0)
2815                 packet_disconnect("Dynamic forwarding denied.");
2816 #endif
2817
2818         /* Initiate forwarding */
2819         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2820             host_port, gateway_ports);
2821
2822         /* Free the argument string. */
2823         xfree(hostname);
2824
2825         return (success ? 0 : -1);
2826 }
2827
2828 /*
2829  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2830  * usually called by the server, because the user could connect to any port
2831  * anyway, and the server has no way to know but to trust the client anyway.
2832  */
2833 void
2834 channel_permit_all_opens(void)
2835 {
2836         if (num_permitted_opens == 0)
2837                 all_opens_permitted = 1;
2838 }
2839
2840 void
2841 channel_add_permitted_opens(char *host, int port)
2842 {
2843         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2844                 fatal("channel_add_permitted_opens: too many forwards");
2845         debug("allow port forwarding to host %s port %d", host, port);
2846
2847         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2848         permitted_opens[num_permitted_opens].port_to_connect = port;
2849         num_permitted_opens++;
2850
2851         all_opens_permitted = 0;
2852 }
2853
2854 int
2855 channel_add_adm_permitted_opens(char *host, int port)
2856 {
2857         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2858                 fatal("channel_add_adm_permitted_opens: too many forwards");
2859         debug("config allows port forwarding to host %s port %d", host, port);
2860
2861         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2862              = xstrdup(host);
2863         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2864         return ++num_adm_permitted_opens;
2865 }
2866
2867 void
2868 channel_clear_permitted_opens(void)
2869 {
2870         int i;
2871
2872         for (i = 0; i < num_permitted_opens; i++)
2873                 if (permitted_opens[i].host_to_connect != NULL)
2874                         xfree(permitted_opens[i].host_to_connect);
2875         num_permitted_opens = 0;
2876 }
2877
2878 void
2879 channel_clear_adm_permitted_opens(void)
2880 {
2881         int i;
2882
2883         for (i = 0; i < num_adm_permitted_opens; i++)
2884                 if (permitted_adm_opens[i].host_to_connect != NULL)
2885                         xfree(permitted_adm_opens[i].host_to_connect);
2886         num_adm_permitted_opens = 0;
2887 }
2888
2889 void
2890 channel_print_adm_permitted_opens(void)
2891 {
2892         int i;
2893
2894         printf("permitopen");
2895         if (num_adm_permitted_opens == 0) {
2896                 printf(" any\n");
2897                 return;
2898         }
2899         for (i = 0; i < num_adm_permitted_opens; i++)
2900                 if (permitted_adm_opens[i].host_to_connect != NULL)
2901                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
2902                             permitted_adm_opens[i].port_to_connect);
2903         printf("\n");
2904 }
2905
2906 /* Try to start non-blocking connect to next host in cctx list */
2907 static int
2908 connect_next(struct channel_connect *cctx)
2909 {
2910         int sock, saved_errno;
2911         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2912
2913         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
2914                 if (cctx->ai->ai_family != AF_INET &&
2915                     cctx->ai->ai_family != AF_INET6)
2916                         continue;
2917                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
2918                     ntop, sizeof(ntop), strport, sizeof(strport),
2919                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2920                         error("connect_next: getnameinfo failed");
2921                         continue;
2922                 }
2923                 if ((sock = socket_rdomain(cctx->ai->ai_family,
2924                     cctx->ai->ai_socktype, cctx->ai->ai_protocol,
2925                     channel_rdomain)) == -1) {
2926                         if (cctx->ai->ai_next == NULL)
2927                                 error("socket: %.100s", strerror(errno));
2928                         else
2929                                 verbose("socket: %.100s", strerror(errno));
2930                         continue;
2931                 }
2932                 if (set_nonblock(sock) == -1)
2933                         fatal("%s: set_nonblock(%d)", __func__, sock);
2934                 if (connect(sock, cctx->ai->ai_addr,
2935                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
2936                         debug("connect_next: host %.100s ([%.100s]:%s): "
2937                             "%.100s", cctx->host, ntop, strport,
2938                             strerror(errno));
2939                         saved_errno = errno;
2940                         close(sock);
2941                         errno = saved_errno;
2942                         continue;       /* fail -- try next */
2943                 }
2944                 debug("connect_next: host %.100s ([%.100s]:%s) "
2945                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
2946                 cctx->ai = cctx->ai->ai_next;
2947                 set_nodelay(sock);
2948                 return sock;
2949         }
2950         return -1;
2951 }
2952
2953 static void
2954 channel_connect_ctx_free(struct channel_connect *cctx)
2955 {
2956         xfree(cctx->host);
2957         if (cctx->aitop)
2958                 freeaddrinfo(cctx->aitop);
2959         bzero(cctx, sizeof(*cctx));
2960         cctx->host = NULL;
2961         cctx->ai = cctx->aitop = NULL;
2962 }
2963
2964 /* Return CONNECTING channel to remote host, port */
2965 static Channel *
2966 connect_to(const char *host, u_short port, char *ctype, char *rname)
2967 {
2968         struct addrinfo hints;
2969         int gaierr;
2970         int sock = -1;
2971         char strport[NI_MAXSERV];
2972         struct channel_connect cctx;
2973         Channel *c;
2974
2975         memset(&cctx, 0, sizeof(cctx));
2976         memset(&hints, 0, sizeof(hints));
2977         hints.ai_family = IPv4or6;
2978         hints.ai_socktype = SOCK_STREAM;
2979         snprintf(strport, sizeof strport, "%d", port);
2980         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
2981                 error("connect_to %.100s: unknown host (%s)", host,
2982                     ssh_gai_strerror(gaierr));
2983                 return NULL;
2984         }
2985
2986         cctx.host = xstrdup(host);
2987         cctx.port = port;
2988         cctx.ai = cctx.aitop;
2989
2990         if ((sock = connect_next(&cctx)) == -1) {
2991                 error("connect to %.100s port %d failed: %s",
2992                     host, port, strerror(errno));
2993                 channel_connect_ctx_free(&cctx);
2994                 return NULL;
2995         }
2996         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
2997             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
2998         c->connect_ctx = cctx;
2999         return c;
3000 }
3001
3002 Channel *
3003 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3004 {
3005         int i;
3006
3007         for (i = 0; i < num_permitted_opens; i++) {
3008                 if (permitted_opens[i].host_to_connect != NULL &&
3009                     permitted_opens[i].listen_port == listen_port) {
3010                         return connect_to(
3011                             permitted_opens[i].host_to_connect,
3012                             permitted_opens[i].port_to_connect, ctype, rname);
3013                 }
3014         }
3015         error("WARNING: Server requests forwarding for unknown listen_port %d",
3016             listen_port);
3017         return NULL;
3018 }
3019
3020 /* Check if connecting to that port is permitted and connect. */
3021 Channel *
3022 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3023 {
3024         int i, permit, permit_adm = 1;
3025
3026         permit = all_opens_permitted;
3027         if (!permit) {
3028                 for (i = 0; i < num_permitted_opens; i++)
3029                         if (permitted_opens[i].host_to_connect != NULL &&
3030                             permitted_opens[i].port_to_connect == port &&
3031                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3032                                 permit = 1;
3033         }
3034
3035         if (num_adm_permitted_opens > 0) {
3036                 permit_adm = 0;
3037                 for (i = 0; i < num_adm_permitted_opens; i++)
3038                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3039                             permitted_adm_opens[i].port_to_connect == port &&
3040                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3041                             == 0)
3042                                 permit_adm = 1;
3043         }
3044
3045         if (!permit || !permit_adm) {
3046                 logit("Received request to connect to host %.100s port %d, "
3047                     "but the request was denied.", host, port);
3048                 return NULL;
3049         }
3050         return connect_to(host, port, ctype, rname);
3051 }
3052
3053 void
3054 channel_send_window_changes(void)
3055 {
3056         u_int i;
3057         struct winsize ws;
3058
3059         for (i = 0; i < channels_alloc; i++) {
3060                 if (channels[i] == NULL || !channels[i]->client_tty ||
3061                     channels[i]->type != SSH_CHANNEL_OPEN)
3062                         continue;
3063                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3064                         continue;
3065                 channel_request_start(i, "window-change", 0);
3066                 packet_put_int((u_int)ws.ws_col);
3067                 packet_put_int((u_int)ws.ws_row);
3068                 packet_put_int((u_int)ws.ws_xpixel);
3069                 packet_put_int((u_int)ws.ws_ypixel);
3070                 packet_send();
3071         }
3072 }
3073
3074 /* -- X11 forwarding */
3075
3076 /*
3077  * Creates an internet domain socket for listening for X11 connections.
3078  * Returns 0 and a suitable display number for the DISPLAY variable
3079  * stored in display_numberp , or -1 if an error occurs.
3080  */
3081 int
3082 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3083     int single_connection, u_int *display_numberp, int **chanids)
3084 {
3085         Channel *nc = NULL;
3086         int display_number, sock;
3087         u_short port;
3088         struct addrinfo hints, *ai, *aitop;
3089         char strport[NI_MAXSERV];
3090         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3091
3092         if (chanids == NULL)
3093                 return -1;
3094
3095         for (display_number = x11_display_offset;
3096             display_number < MAX_DISPLAYS;
3097             display_number++) {
3098                 port = 6000 + display_number;
3099                 memset(&hints, 0, sizeof(hints));
3100                 hints.ai_family = IPv4or6;
3101                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3102                 hints.ai_socktype = SOCK_STREAM;
3103                 snprintf(strport, sizeof strport, "%d", port);
3104                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3105                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3106                         return -1;
3107                 }
3108                 for (ai = aitop; ai; ai = ai->ai_next) {
3109                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3110                                 continue;
3111                         sock = socket_rdomain(ai->ai_family, ai->ai_socktype,
3112                             ai->ai_protocol, channel_rdomain);
3113                         if (sock < 0) {
3114                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3115                                         error("socket: %.100s", strerror(errno));
3116                                         freeaddrinfo(aitop);
3117                                         return -1;
3118                                 } else {
3119                                         debug("x11_create_display_inet: Socket family %d not supported",
3120                                                  ai->ai_family);
3121                                         continue;
3122                                 }
3123                         }
3124                         if (ai->ai_family == AF_INET6)
3125                                 sock_set_v6only(sock);
3126                         if (x11_use_localhost)
3127                                 channel_set_reuseaddr(sock);
3128                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3129                                 debug2("bind port %d: %.100s", port, strerror(errno));
3130                                 close(sock);
3131
3132                                 for (n = 0; n < num_socks; n++) {
3133                                         close(socks[n]);
3134                                 }
3135                                 num_socks = 0;
3136                                 break;
3137                         }
3138                         socks[num_socks++] = sock;
3139                         if (num_socks == NUM_SOCKS)
3140                                 break;
3141                 }
3142                 freeaddrinfo(aitop);
3143                 if (num_socks > 0)
3144                         break;
3145         }
3146         if (display_number >= MAX_DISPLAYS) {
3147                 error("Failed to allocate internet-domain X11 display socket.");
3148                 return -1;
3149         }
3150         /* Start listening for connections on the socket. */
3151         for (n = 0; n < num_socks; n++) {
3152                 sock = socks[n];
3153                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3154                         error("listen: %.100s", strerror(errno));
3155                         close(sock);
3156                         return -1;
3157                 }
3158         }
3159
3160         /* Allocate a channel for each socket. */
3161         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3162         for (n = 0; n < num_socks; n++) {
3163                 sock = socks[n];
3164                 nc = channel_new("x11 listener",
3165                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3166                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3167                     0, "X11 inet listener", 1);
3168                 nc->single_connection = single_connection;
3169                 (*chanids)[n] = nc->self;
3170         }
3171         (*chanids)[n] = -1;
3172
3173         /* Return the display number for the DISPLAY environment variable. */
3174         *display_numberp = display_number;
3175         return (0);
3176 }
3177
3178 static int
3179 connect_local_xsocket_path(const char *pathname)
3180 {
3181         int sock;
3182         struct sockaddr_un addr;
3183
3184         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3185         if (sock < 0)
3186                 error("socket: %.100s", strerror(errno));
3187         memset(&addr, 0, sizeof(addr));
3188         addr.sun_family = AF_UNIX;
3189         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3190         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3191                 return sock;
3192         close(sock);
3193         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3194         return -1;
3195 }
3196
3197 static int
3198 connect_local_xsocket(u_int dnr)
3199 {
3200         char buf[1024];
3201         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3202         return connect_local_xsocket_path(buf);
3203 }
3204
3205 int
3206 x11_connect_display(void)
3207 {
3208         u_int display_number;
3209         const char *display;
3210         char buf[1024], *cp;
3211         struct addrinfo hints, *ai, *aitop;
3212         char strport[NI_MAXSERV];
3213         int gaierr, sock = 0;
3214
3215         /* Try to open a socket for the local X server. */
3216         display = getenv("DISPLAY");
3217         if (!display) {
3218                 error("DISPLAY not set.");
3219                 return -1;
3220         }
3221         /*
3222          * Now we decode the value of the DISPLAY variable and make a
3223          * connection to the real X server.
3224          */
3225
3226         /* Check if the display is from launchd. */
3227 #ifdef __APPLE__
3228         if (strncmp(display, "/tmp/launch", 11) == 0) {
3229                 sock = connect_local_xsocket_path(display);
3230                 if (sock < 0)
3231                         return -1;
3232
3233                 /* OK, we now have a connection to the display. */
3234                 return sock;
3235         }
3236 #endif
3237         /*
3238          * Check if it is a unix domain socket.  Unix domain displays are in
3239          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3240          */
3241         if (strncmp(display, "unix:", 5) == 0 ||
3242             display[0] == ':') {
3243                 /* Connect to the unix domain socket. */
3244                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3245                         error("Could not parse display number from DISPLAY: %.100s",
3246                             display);
3247                         return -1;
3248                 }
3249                 /* Create a socket. */
3250                 sock = connect_local_xsocket(display_number);
3251                 if (sock < 0)
3252                         return -1;
3253
3254                 /* OK, we now have a connection to the display. */
3255                 return sock;
3256         }
3257         /*
3258          * Connect to an inet socket.  The DISPLAY value is supposedly
3259          * hostname:d[.s], where hostname may also be numeric IP address.
3260          */
3261         strlcpy(buf, display, sizeof(buf));
3262         cp = strchr(buf, ':');
3263         if (!cp) {
3264                 error("Could not find ':' in DISPLAY: %.100s", display);
3265                 return -1;
3266         }
3267         *cp = 0;
3268         /* buf now contains the host name.  But first we parse the display number. */
3269         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3270                 error("Could not parse display number from DISPLAY: %.100s",
3271                     display);
3272                 return -1;
3273         }
3274
3275         /* Look up the host address */
3276         memset(&hints, 0, sizeof(hints));
3277         hints.ai_family = IPv4or6;
3278         hints.ai_socktype = SOCK_STREAM;
3279         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3280         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3281                 error("%.100s: unknown host. (%s)", buf,
3282                 ssh_gai_strerror(gaierr));
3283                 return -1;
3284         }
3285         for (ai = aitop; ai; ai = ai->ai_next) {
3286                 /* Create a socket. */
3287                 sock = socket_rdomain(ai->ai_family, ai->ai_socktype,
3288                     ai->ai_protocol, channel_rdomain);
3289                 if (sock < 0) {
3290                         debug2("socket: %.100s", strerror(errno));
3291                         continue;
3292                 }
3293                 /* Connect it to the display. */
3294                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3295                         debug2("connect %.100s port %u: %.100s", buf,
3296                             6000 + display_number, strerror(errno));
3297                         close(sock);
3298                         continue;
3299                 }
3300                 /* Success */
3301                 break;
3302         }
3303         freeaddrinfo(aitop);
3304         if (!ai) {
3305                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3306                     strerror(errno));
3307                 return -1;
3308         }
3309         set_nodelay(sock);
3310         return sock;
3311 }
3312
3313 /*
3314  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3315  * the remote channel number.  We should do whatever we want, and respond
3316  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3317  */
3318
3319 /* ARGSUSED */
3320 void
3321 x11_input_open(int type, u_int32_t seq, void *ctxt)
3322 {
3323         Channel *c = NULL;
3324         int remote_id, sock = 0;
3325         char *remote_host;
3326
3327         debug("Received X11 open request.");
3328
3329         remote_id = packet_get_int();
3330
3331         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3332                 remote_host = packet_get_string(NULL);
3333         } else {
3334                 remote_host = xstrdup("unknown (remote did not supply name)");
3335         }
3336         packet_check_eom();
3337
3338         /* Obtain a connection to the real X display. */
3339         sock = x11_connect_display();
3340         if (sock != -1) {
3341                 /* Allocate a channel for this connection. */
3342                 c = channel_new("connected x11 socket",
3343                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3344                     remote_host, 1);
3345                 c->remote_id = remote_id;
3346                 c->force_drain = 1;
3347         }
3348         xfree(remote_host);
3349         if (c == NULL) {
3350                 /* Send refusal to the remote host. */
3351                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3352                 packet_put_int(remote_id);
3353         } else {
3354                 /* Send a confirmation to the remote host. */
3355                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3356                 packet_put_int(remote_id);
3357                 packet_put_int(c->self);
3358         }
3359         packet_send();
3360 }
3361
3362 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3363 /* ARGSUSED */
3364 void
3365 deny_input_open(int type, u_int32_t seq, void *ctxt)
3366 {
3367         int rchan = packet_get_int();
3368
3369         switch (type) {
3370         case SSH_SMSG_AGENT_OPEN:
3371                 error("Warning: ssh server tried agent forwarding.");
3372                 break;
3373         case SSH_SMSG_X11_OPEN:
3374                 error("Warning: ssh server tried X11 forwarding.");
3375                 break;
3376         default:
3377                 error("deny_input_open: type %d", type);
3378                 break;
3379         }
3380         error("Warning: this is probably a break-in attempt by a malicious server.");
3381         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3382         packet_put_int(rchan);
3383         packet_send();
3384 }
3385
3386 /*
3387  * Requests forwarding of X11 connections, generates fake authentication
3388  * data, and enables authentication spoofing.
3389  * This should be called in the client only.
3390  */
3391 void
3392 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3393     const char *proto, const char *data)
3394 {
3395         u_int data_len = (u_int) strlen(data) / 2;
3396         u_int i, value;
3397         char *new_data;
3398         int screen_number;
3399         const char *cp;
3400         u_int32_t rnd = 0;
3401
3402         if (x11_saved_display == NULL)
3403                 x11_saved_display = xstrdup(disp);
3404         else if (strcmp(disp, x11_saved_display) != 0) {
3405                 error("x11_request_forwarding_with_spoofing: different "
3406                     "$DISPLAY already forwarded");
3407                 return;
3408         }
3409
3410         cp = strchr(disp, ':');
3411         if (cp)
3412                 cp = strchr(cp, '.');
3413         if (cp)
3414                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3415         else
3416                 screen_number = 0;
3417
3418         if (x11_saved_proto == NULL) {
3419                 /* Save protocol name. */
3420                 x11_saved_proto = xstrdup(proto);
3421                 /*
3422                  * Extract real authentication data and generate fake data
3423                  * of the same length.
3424                  */
3425                 x11_saved_data = xmalloc(data_len);
3426                 x11_fake_data = xmalloc(data_len);
3427                 for (i = 0; i < data_len; i++) {
3428                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3429                                 fatal("x11_request_forwarding: bad "
3430                                     "authentication data: %.100s", data);
3431                         if (i % 4 == 0)
3432                                 rnd = arc4random();
3433                         x11_saved_data[i] = value;
3434                         x11_fake_data[i] = rnd & 0xff;
3435                         rnd >>= 8;
3436                 }
3437                 x11_saved_data_len = data_len;
3438                 x11_fake_data_len = data_len;
3439         }
3440
3441         /* Convert the fake data into hex. */
3442         new_data = tohex(x11_fake_data, data_len);
3443
3444         /* Send the request packet. */
3445         if (compat20) {
3446                 channel_request_start(client_session_id, "x11-req", 0);
3447                 packet_put_char(0);     /* XXX bool single connection */
3448         } else {
3449                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3450         }
3451         packet_put_cstring(proto);
3452         packet_put_cstring(new_data);
3453         packet_put_int(screen_number);
3454         packet_send();
3455         packet_write_wait();
3456         xfree(new_data);
3457 }
3458
3459
3460 /* -- agent forwarding */
3461
3462 /* Sends a message to the server to request authentication fd forwarding. */
3463
3464 void
3465 auth_request_forwarding(void)
3466 {
3467         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3468         packet_send();
3469         packet_write_wait();
3470 }