channels.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * This file contains functions for generic socket connection forwarding.
   6  * There is also code for initiating connection forwarding for X11 connections,
   7  * arbitrary tcp/ip connections, and the authentication agent connection.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999,2000 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 RCSID("$OpenBSD: channels.c,v 1.80 2001/01/08 22:03:23 markus Exp $");
  44
  45 #include "ssh.h"
  46 #include "packet.h"
  47 #include "xmalloc.h"
  48 #include "buffer.h"
  49 #include "uidswap.h"
  50 #include "readconf.h"
  51 #include "servconf.h"
  52
  53 #include "channels.h"
  54 #include "nchan.h"
  55 #include "compat.h"
  56
  57 #include "ssh2.h"
  58
  59 #include <openssl/rsa.h>
  60 #include <openssl/dsa.h>
  61 #include "key.h"
  62 #include "authfd.h"
  63
  64 /* Maximum number of fake X11 displays to try. */
  65 #define MAX_DISPLAYS  1000
  66
  67 /* Max len of agent socket */
  68 #define MAX_SOCKET_NAME 100
  69
  70 /*
  71  * Pointer to an array containing all allocated channels.  The array is
  72  * dynamically extended as needed.
  73  */
  74 static Channel *channels = NULL;
  75
  76 /*
  77  * Size of the channel array.  All slots of the array must always be
  78  * initialized (at least the type field); unused slots are marked with type
  79  * SSH_CHANNEL_FREE.
  80  */
  81 static int channels_alloc = 0;
  82
  83 /*
  84  * Maximum file descriptor value used in any of the channels.  This is
  85  * updated in channel_allocate.
  86  */
  87 static int channel_max_fd_value = 0;
  88
  89 /* Name and directory of socket for authentication agent forwarding. */
  90 static char *channel_forwarded_auth_socket_name = NULL;
  91 static char *channel_forwarded_auth_socket_dir = NULL;
  92
  93 /* Saved X11 authentication protocol name. */
  94 char *x11_saved_proto = NULL;
  95
  96 /* Saved X11 authentication data.  This is the real data. */
  97 char *x11_saved_data = NULL;
  98 u_int x11_saved_data_len = 0;
  99
 100 /*
 101  * Fake X11 authentication data.  This is what the server will be sending us;
 102  * we should replace any occurrences of this by the real data.
 103  */
 104 char *x11_fake_data = NULL;
 105 u_int x11_fake_data_len;
 106
 107 /*
 108  * Data structure for storing which hosts are permitted for forward requests.
 109  * The local sides of any remote forwards are stored in this array to prevent
 110  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 111  * network (which might be behind a firewall).
 112  */
 113 typedef struct {
 114         char *host_to_connect;          /* Connect to 'host'. */
 115         u_short port_to_connect;        /* Connect to 'port'. */
 116         u_short listen_port;            /* Remote side should listen port number. */
 117 } ForwardPermission;
 118
 119 /* List of all permitted host/port pairs to connect. */
 120 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 121 /* Number of permitted host/port pairs in the array. */
 122 static int num_permitted_opens = 0;
 123 /*
 124  * If this is true, all opens are permitted.  This is the case on the server
 125  * on which we have to trust the client anyway, and the user could do
 126  * anything after logging in anyway.
 127  */
 128 static int all_opens_permitted = 0;
 129
 130 /* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */
 131 static int have_hostname_in_open = 0;
 132
 133 /* Sets specific protocol options. */
 134
 135 void
 136 channel_set_options(int hostname_in_open)
 137 {
 138         have_hostname_in_open = hostname_in_open;
 139 }
 140
 141 /*
 142  * Permits opening to any host/port in SSH_MSG_PORT_OPEN.  This is usually
 143  * called by the server, because the user could connect to any port anyway,
 144  * and the server has no way to know but to trust the client anyway.
 145  */
 146
 147 void
 148 channel_permit_all_opens()
 149 {
 150         all_opens_permitted = 1;
 151 }
 152
 153 /* lookup channel by id */
 154
 155 Channel *
 156 channel_lookup(int id)
 157 {
 158         Channel *c;
 159         if (id < 0 || id > channels_alloc) {
 160                 log("channel_lookup: %d: bad id", id);
 161                 return NULL;
 162         }
 163         c = &channels[id];
 164         if (c->type == SSH_CHANNEL_FREE) {
 165                 log("channel_lookup: %d: bad id: channel free", id);
 166                 return NULL;
 167         }
 168         return c;
 169 }
 170
 171 /*
 172  * Register filedescriptors for a channel, used when allocating a channel or
 173  * when the channel consumer/producer is ready, e.g. shell exec'd
 174  */
 175
 176 void
 177 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 178     int extusage, int nonblock)
 179 {
 180         /* Update the maximum file descriptor value. */
 181         if (rfd > channel_max_fd_value)
 182                 channel_max_fd_value = rfd;
 183         if (wfd > channel_max_fd_value)
 184                 channel_max_fd_value = wfd;
 185         if (efd > channel_max_fd_value)
 186                 channel_max_fd_value = efd;
 187         /* XXX set close-on-exec -markus */
 188
 189         c->rfd = rfd;
 190         c->wfd = wfd;
 191         c->sock = (rfd == wfd) ? rfd : -1;
 192         c->efd = efd;
 193         c->extended_usage = extusage;
 194
 195         /* enable nonblocking mode */
 196         if (nonblock) {
 197                 if (rfd != -1)
 198                         set_nonblock(rfd);
 199                 if (wfd != -1)
 200                         set_nonblock(wfd);
 201                 if (efd != -1)
 202                         set_nonblock(efd);
 203         }
 204 }
 205
 206 /*
 207  * Allocate a new channel object and set its type and socket. This will cause
 208  * remote_name to be freed.
 209  */
 210
 211 int
 212 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 213     int window, int maxpack, int extusage, char *remote_name, int nonblock)
 214 {
 215         int i, found;
 216         Channel *c;
 217
 218         /* Do initial allocation if this is the first call. */
 219         if (channels_alloc == 0) {
 220                 chan_init();
 221                 channels_alloc = 10;
 222                 channels = xmalloc(channels_alloc * sizeof(Channel));
 223                 for (i = 0; i < channels_alloc; i++)
 224                         channels[i].type = SSH_CHANNEL_FREE;
 225                 /*
 226                  * Kludge: arrange a call to channel_stop_listening if we
 227                  * terminate with fatal().
 228                  */
 229                 fatal_add_cleanup((void (*) (void *)) channel_stop_listening, NULL);
 230         }
 231         /* Try to find a free slot where to put the new channel. */
 232         for (found = -1, i = 0; i < channels_alloc; i++)
 233                 if (channels[i].type == SSH_CHANNEL_FREE) {
 234                         /* Found a free slot. */
 235                         found = i;
 236                         break;
 237                 }
 238         if (found == -1) {
 239                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 240                 found = channels_alloc;
 241                 channels_alloc += 10;
 242                 debug2("channel: expanding %d", channels_alloc);
 243                 channels = xrealloc(channels, channels_alloc * sizeof(Channel));
 244                 for (i = found; i < channels_alloc; i++)
 245                         channels[i].type = SSH_CHANNEL_FREE;
 246         }
 247         /* Initialize and return new channel number. */
 248         c = &channels[found];
 249         buffer_init(&c->input);
 250         buffer_init(&c->output);
 251         buffer_init(&c->extended);
 252         chan_init_iostates(c);
 253         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 254         c->self = found;
 255         c->type = type;
 256         c->ctype = ctype;
 257         c->local_window = window;
 258         c->local_window_max = window;
 259         c->local_consumed = 0;
 260         c->local_maxpacket = maxpack;
 261         c->remote_id = -1;
 262         c->remote_name = remote_name;
 263         c->remote_window = 0;
 264         c->remote_maxpacket = 0;
 265         c->cb_fn = NULL;
 266         c->cb_arg = NULL;
 267         c->cb_event = 0;
 268         c->dettach_user = NULL;
 269         c->input_filter = NULL;
 270         debug("channel %d: new [%s]", found, remote_name);
 271         return found;
 272 }
 273 /* old interface XXX */
 274 int
 275 channel_allocate(int type, int sock, char *remote_name)
 276 {
 277         return channel_new("", type, sock, sock, -1, 0, 0, 0, remote_name, 1);
 278 }
 279
 280
 281 /* Close all channel fd/socket. */
 282
 283 void
 284 channel_close_fds(Channel *c)
 285 {
 286         if (c->sock != -1) {
 287                 close(c->sock);
 288                 c->sock = -1;
 289         }
 290         if (c->rfd != -1) {
 291                 close(c->rfd);
 292                 c->rfd = -1;
 293         }
 294         if (c->wfd != -1) {
 295                 close(c->wfd);
 296                 c->wfd = -1;
 297         }
 298         if (c->efd != -1) {
 299                 close(c->efd);
 300                 c->efd = -1;
 301         }
 302 }
 303
 304 /* Free the channel and close its fd/socket. */
 305
 306 void
 307 channel_free(int id)
 308 {
 309         Channel *c = channel_lookup(id);
 310         char *s = channel_open_message();
 311
 312         if (c == NULL)
 313                 packet_disconnect("channel free: bad local channel %d", id);
 314         debug("channel_free: channel %d: status: %s", id, s);
 315         xfree(s);
 316
 317         if (c->dettach_user != NULL) {
 318                 debug("channel_free: channel %d: dettaching channel user", id);
 319                 c->dettach_user(c->self, NULL);
 320         }
 321         if (c->sock != -1)
 322                 shutdown(c->sock, SHUT_RDWR);
 323         channel_close_fds(c);
 324         buffer_free(&c->input);
 325         buffer_free(&c->output);
 326         buffer_free(&c->extended);
 327         c->type = SSH_CHANNEL_FREE;
 328         if (c->remote_name) {
 329                 xfree(c->remote_name);
 330                 c->remote_name = NULL;
 331         }
 332 }
 333
 334 /*
 335  * 'channel_pre*' are called just before select() to add any bits relevant to
 336  * channels in the select bitmasks.
 337  */
 338 /*
 339  * 'channel_post*': perform any appropriate operations for channels which
 340  * have events pending.
 341  */
 342 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 343 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 344 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 345
 346 void
 347 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 348 {
 349         FD_SET(c->sock, readset);
 350 }
 351
 352 void
 353 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 354 {
 355         debug3("channel %d: waiting for connection", c->self);
 356         FD_SET(c->sock, writeset);
 357 }
 358
 359 void
 360 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 361 {
 362         if (buffer_len(&c->input) < packet_get_maxsize())
 363                 FD_SET(c->sock, readset);
 364         if (buffer_len(&c->output) > 0)
 365                 FD_SET(c->sock, writeset);
 366 }
 367
 368 void
 369 channel_pre_open_15(Channel *c, fd_set * readset, fd_set * writeset)
 370 {
 371         /* test whether sockets are 'alive' for read/write */
 372         if (c->istate == CHAN_INPUT_OPEN)
 373                 if (buffer_len(&c->input) < packet_get_maxsize())
 374                         FD_SET(c->sock, readset);
 375         if (c->ostate == CHAN_OUTPUT_OPEN ||
 376             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 377                 if (buffer_len(&c->output) > 0) {
 378                         FD_SET(c->sock, writeset);
 379                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 380                         chan_obuf_empty(c);
 381                 }
 382         }
 383 }
 384
 385 void
 386 channel_pre_open_20(Channel *c, fd_set * readset, fd_set * writeset)
 387 {
 388         if (c->istate == CHAN_INPUT_OPEN &&
 389             c->remote_window > 0 &&
 390             buffer_len(&c->input) < c->remote_window)
 391                 FD_SET(c->rfd, readset);
 392         if (c->ostate == CHAN_OUTPUT_OPEN ||
 393             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 394                 if (buffer_len(&c->output) > 0) {
 395                         FD_SET(c->wfd, writeset);
 396                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 397                         chan_obuf_empty(c);
 398                 }
 399         }
 400         /** XXX check close conditions, too */
 401         if (c->efd != -1) {
 402                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 403                     buffer_len(&c->extended) > 0)
 404                         FD_SET(c->efd, writeset);
 405                 else if (c->extended_usage == CHAN_EXTENDED_READ &&
 406                     buffer_len(&c->extended) < c->remote_window)
 407                         FD_SET(c->efd, readset);
 408         }
 409 }
 410
 411 void
 412 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 413 {
 414         if (buffer_len(&c->input) == 0) {
 415                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 416                 packet_put_int(c->remote_id);
 417                 packet_send();
 418                 c->type = SSH_CHANNEL_CLOSED;
 419                 debug("Closing channel %d after input drain.", c->self);
 420         }
 421 }
 422
 423 void
 424 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 425 {
 426         if (buffer_len(&c->output) == 0)
 427                 channel_free(c->self);
 428         else
 429                 FD_SET(c->sock, writeset);
 430 }
 431
 432 /*
 433  * This is a special state for X11 authentication spoofing.  An opened X11
 434  * connection (when authentication spoofing is being done) remains in this
 435  * state until the first packet has been completely read.  The authentication
 436  * data in that packet is then substituted by the real data if it matches the
 437  * fake data, and the channel is put into normal mode.
 438  * XXX All this happens at the client side.
 439  */
 440 int
 441 x11_open_helper(Channel *c)
 442 {
 443         u_char *ucp;
 444         u_int proto_len, data_len;
 445
 446         /* Check if the fixed size part of the packet is in buffer. */
 447         if (buffer_len(&c->output) < 12)
 448                 return 0;
 449
 450         /* Parse the lengths of variable-length fields. */
 451         ucp = (u_char *) buffer_ptr(&c->output);
 452         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 453                 proto_len = 256 * ucp[6] + ucp[7];
 454                 data_len = 256 * ucp[8] + ucp[9];
 455         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 456                 proto_len = ucp[6] + 256 * ucp[7];
 457                 data_len = ucp[8] + 256 * ucp[9];
 458         } else {
 459                 debug("Initial X11 packet contains bad byte order byte: 0x%x",
 460                       ucp[0]);
 461                 return -1;
 462         }
 463
 464         /* Check if the whole packet is in buffer. */
 465         if (buffer_len(&c->output) <
 466             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 467                 return 0;
 468
 469         /* Check if authentication protocol matches. */
 470         if (proto_len != strlen(x11_saved_proto) ||
 471             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 472                 debug("X11 connection uses different authentication protocol.");
 473                 return -1;
 474         }
 475         /* Check if authentication data matches our fake data. */
 476         if (data_len != x11_fake_data_len ||
 477             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 478                 x11_fake_data, x11_fake_data_len) != 0) {
 479                 debug("X11 auth data does not match fake data.");
 480                 return -1;
 481         }
 482         /* Check fake data length */
 483         if (x11_fake_data_len != x11_saved_data_len) {
 484                 error("X11 fake_data_len %d != saved_data_len %d",
 485                     x11_fake_data_len, x11_saved_data_len);
 486                 return -1;
 487         }
 488         /*
 489          * Received authentication protocol and data match
 490          * our fake data. Substitute the fake data with real
 491          * data.
 492          */
 493         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 494             x11_saved_data, x11_saved_data_len);
 495         return 1;
 496 }
 497
 498 void
 499 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 500 {
 501         int ret = x11_open_helper(c);
 502         if (ret == 1) {
 503                 /* Start normal processing for the channel. */
 504                 c->type = SSH_CHANNEL_OPEN;
 505                 channel_pre_open_13(c, readset, writeset);
 506         } else if (ret == -1) {
 507                 /*
 508                  * We have received an X11 connection that has bad
 509                  * authentication information.
 510                  */
 511                 log("X11 connection rejected because of wrong authentication.\r\n");
 512                 buffer_clear(&c->input);
 513                 buffer_clear(&c->output);
 514                 close(c->sock);
 515                 c->sock = -1;
 516                 c->type = SSH_CHANNEL_CLOSED;
 517                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 518                 packet_put_int(c->remote_id);
 519                 packet_send();
 520         }
 521 }
 522
 523 void
 524 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
 525 {
 526         int ret = x11_open_helper(c);
 527         if (ret == 1) {
 528                 c->type = SSH_CHANNEL_OPEN;
 529                 if (compat20)
 530                         channel_pre_open_20(c, readset, writeset);
 531                 else
 532                         channel_pre_open_15(c, readset, writeset);
 533         } else if (ret == -1) {
 534                 debug("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 535                 chan_read_failed(c);    /** force close? */
 536                 chan_write_failed(c);
 537                 debug("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 538         }
 539 }
 540
 541 /* This is our fake X11 server socket. */
 542 void
 543 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
 544 {
 545         struct sockaddr addr;
 546         int newsock, newch;
 547         socklen_t addrlen;
 548         char buf[16384], *remote_hostname;
 549         int remote_port;
 550
 551         if (FD_ISSET(c->sock, readset)) {
 552                 debug("X11 connection requested.");
 553                 addrlen = sizeof(addr);
 554                 newsock = accept(c->sock, &addr, &addrlen);
 555                 if (newsock < 0) {
 556                         error("accept: %.100s", strerror(errno));
 557                         return;
 558                 }
 559                 remote_hostname = get_remote_hostname(newsock);
 560                 remote_port = get_peer_port(newsock);
 561                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
 562                     remote_hostname, remote_port);
 563
 564                 newch = channel_new("x11",
 565                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
 566                     c->local_window_max, c->local_maxpacket,
 567                     0, xstrdup(buf), 1);
 568                 if (compat20) {
 569                         packet_start(SSH2_MSG_CHANNEL_OPEN);
 570                         packet_put_cstring("x11");
 571                         packet_put_int(newch);
 572                         packet_put_int(c->local_window_max);
 573                         packet_put_int(c->local_maxpacket);
 574                         /* originator host and port */
 575                         packet_put_cstring(remote_hostname);
 576                         if (datafellows & SSH_BUG_X11FWD) {
 577                                 debug("ssh2 x11 bug compat mode");
 578                         } else {
 579                                 packet_put_int(remote_port);
 580                         }
 581                         packet_send();
 582                 } else {
 583                         packet_start(SSH_SMSG_X11_OPEN);
 584                         packet_put_int(newch);
 585                         if (have_hostname_in_open)
 586                                 packet_put_string(buf, strlen(buf));
 587                         packet_send();
 588                 }
 589                 xfree(remote_hostname);
 590         }
 591 }
 592
 593 /*
 594  * This socket is listening for connections to a forwarded TCP/IP port.
 595  */
 596 void
 597 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
 598 {
 599         struct sockaddr addr;
 600         int newsock, newch;
 601         socklen_t addrlen;
 602         char buf[1024], *remote_hostname, *rtype;
 603         int remote_port;
 604
 605         rtype = (c->type == SSH_CHANNEL_RPORT_LISTENER) ?
 606             "forwarded-tcpip" : "direct-tcpip";
 607
 608         if (FD_ISSET(c->sock, readset)) {
 609                 debug("Connection to port %d forwarding "
 610                     "to %.100s port %d requested.",
 611                     c->listening_port, c->path, c->host_port);
 612                 addrlen = sizeof(addr);
 613                 newsock = accept(c->sock, &addr, &addrlen);
 614                 if (newsock < 0) {
 615                         error("accept: %.100s", strerror(errno));
 616                         return;
 617                 }
 618                 remote_hostname = get_remote_hostname(newsock);
 619                 remote_port = get_peer_port(newsock);
 620                 snprintf(buf, sizeof buf,
 621                     "listen port %d for %.100s port %d, "
 622                     "connect from %.200s port %d",
 623                     c->listening_port, c->path, c->host_port,
 624                     remote_hostname, remote_port);
 625
 626                 newch = channel_new(rtype,
 627                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
 628                     c->local_window_max, c->local_maxpacket,
 629                     0, xstrdup(buf), 1);
 630                 if (compat20) {
 631                         packet_start(SSH2_MSG_CHANNEL_OPEN);
 632                         packet_put_cstring(rtype);
 633                         packet_put_int(newch);
 634                         packet_put_int(c->local_window_max);
 635                         packet_put_int(c->local_maxpacket);
 636                         if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
 637                                 /* listen address, port */
 638                                 packet_put_string(c->path, strlen(c->path));
 639                                 packet_put_int(c->listening_port);
 640                         } else {
 641                                 /* target host, port */
 642                                 packet_put_string(c->path, strlen(c->path));
 643                                 packet_put_int(c->host_port);
 644                         }
 645                         /* originator host and port */
 646                         packet_put_cstring(remote_hostname);
 647                         packet_put_int(remote_port);
 648                         packet_send();
 649                 } else {
 650                         packet_start(SSH_MSG_PORT_OPEN);
 651                         packet_put_int(newch);
 652                         packet_put_string(c->path, strlen(c->path));
 653                         packet_put_int(c->host_port);
 654                         if (have_hostname_in_open) {
 655                                 packet_put_string(buf, strlen(buf));
 656                         }
 657                         packet_send();
 658                 }
 659                 xfree(remote_hostname);
 660         }
 661 }
 662
 663 /*
 664  * This is the authentication agent socket listening for connections from
 665  * clients.
 666  */
 667 void
 668 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
 669 {
 670         struct sockaddr addr;
 671         int newsock, newch;
 672         socklen_t addrlen;
 673
 674         if (FD_ISSET(c->sock, readset)) {
 675                 addrlen = sizeof(addr);
 676                 newsock = accept(c->sock, &addr, &addrlen);
 677                 if (newsock < 0) {
 678                         error("accept from auth socket: %.100s", strerror(errno));
 679                         return;
 680                 }
 681                 newch = channel_new("accepted auth socket",
 682                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
 683                     c->local_window_max, c->local_maxpacket,
 684                     0, xstrdup("accepted auth socket"), 1);
 685                 if (compat20) {
 686                         packet_start(SSH2_MSG_CHANNEL_OPEN);
 687                         packet_put_cstring("auth-agent@openssh.com");
 688                         packet_put_int(newch);
 689                         packet_put_int(c->local_window_max);
 690                         packet_put_int(c->local_maxpacket);
 691                 } else {
 692                         packet_start(SSH_SMSG_AGENT_OPEN);
 693                         packet_put_int(newch);
 694                 }
 695                 packet_send();
 696         }
 697 }
 698
 699 void
 700 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 701 {
 702         if (FD_ISSET(c->sock, writeset)) {
 703                 int err = 0;
 704                 int sz = sizeof(err);
 705                 c->type = SSH_CHANNEL_OPEN;
 706                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, (char *)&err, &sz) < 0) {
 707                         debug("getsockopt SO_ERROR failed");
 708                 } else {
 709                         if (err == 0) {
 710                                 debug("channel %d: connected)", c->self);
 711                         } else {
 712                                 debug("channel %d: not connected: %s",
 713                                     c->self, strerror(err));
 714                                 chan_read_failed(c);
 715                                 chan_write_failed(c);
 716                         }
 717                 }
 718         }
 719 }
 720
 721 int
 722 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
 723 {
 724         char buf[16*1024];
 725         int len;
 726
 727         if (c->rfd != -1 &&
 728             FD_ISSET(c->rfd, readset)) {
 729                 len = read(c->rfd, buf, sizeof(buf));
 730                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
 731                         return 1;
 732                 if (len <= 0) {
 733                         debug("channel %d: read<=0 rfd %d len %d",
 734                             c->self, c->rfd, len);
 735                         if (compat13) {
 736                                 buffer_consume(&c->output, buffer_len(&c->output));
 737                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
 738                                 debug("Channel %d status set to input draining.", c->self);
 739                         } else {
 740                                 chan_read_failed(c);
 741                         }
 742                         return -1;
 743                 }
 744                 if(c->input_filter != NULL) {
 745                         if (c->input_filter(c, buf, len) == -1) {
 746                                 debug("filter stops channel %d", c->self);
 747                                 chan_read_failed(c);
 748                         }
 749                 } else {
 750                         buffer_append(&c->input, buf, len);
 751                 }
 752         }
 753         return 1;
 754 }
 755 int
 756 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
 757 {
 758         int len;
 759
 760         /* Send buffered output data to the socket. */
 761         if (c->wfd != -1 &&
 762             FD_ISSET(c->wfd, writeset) &&
 763             buffer_len(&c->output) > 0) {
 764                 len = write(c->wfd, buffer_ptr(&c->output),
 765                     buffer_len(&c->output));
 766                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
 767                         return 1;
 768                 if (len <= 0) {
 769                         if (compat13) {
 770                                 buffer_consume(&c->output, buffer_len(&c->output));
 771                                 debug("Channel %d status set to input draining.", c->self);
 772                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
 773                         } else {
 774                                 chan_write_failed(c);
 775                         }
 776                         return -1;
 777                 }
 778                 buffer_consume(&c->output, len);
 779                 if (compat20 && len > 0) {
 780                         c->local_consumed += len;
 781                 }
 782         }
 783         return 1;
 784 }
 785 int
 786 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
 787 {
 788         char buf[16*1024];
 789         int len;
 790
 791 /** XXX handle drain efd, too */
 792         if (c->efd != -1) {
 793                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 794                     FD_ISSET(c->efd, writeset) &&
 795                     buffer_len(&c->extended) > 0) {
 796                         len = write(c->efd, buffer_ptr(&c->extended),
 797                             buffer_len(&c->extended));
 798                         debug2("channel %d: written %d to efd %d",
 799                             c->self, len, c->efd);
 800                         if (len > 0) {
 801                                 buffer_consume(&c->extended, len);
 802                                 c->local_consumed += len;
 803                         }
 804                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
 805                     FD_ISSET(c->efd, readset)) {
 806                         len = read(c->efd, buf, sizeof(buf));
 807                         debug2("channel %d: read %d from efd %d",
 808                              c->self, len, c->efd);
 809                         if (len == 0) {
 810                                 debug("channel %d: closing efd %d",
 811                                     c->self, c->efd);
 812                                 close(c->efd);
 813                                 c->efd = -1;
 814                         } else if (len > 0)
 815                                 buffer_append(&c->extended, buf, len);
 816                 }
 817         }
 818         return 1;
 819 }
 820 int
 821 channel_check_window(Channel *c, fd_set * readset, fd_set * writeset)
 822 {
 823         if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
 824             c->local_window < c->local_window_max/2 &&
 825             c->local_consumed > 0) {
 826                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 827                 packet_put_int(c->remote_id);
 828                 packet_put_int(c->local_consumed);
 829                 packet_send();
 830                 debug2("channel %d: window %d sent adjust %d",
 831                     c->self, c->local_window,
 832                     c->local_consumed);
 833                 c->local_window += c->local_consumed;
 834                 c->local_consumed = 0;
 835         }
 836         return 1;
 837 }
 838
 839 void
 840 channel_post_open_1(Channel *c, fd_set * readset, fd_set * writeset)
 841 {
 842         channel_handle_rfd(c, readset, writeset);
 843         channel_handle_wfd(c, readset, writeset);
 844 }
 845
 846 void
 847 channel_post_open_2(Channel *c, fd_set * readset, fd_set * writeset)
 848 {
 849         channel_handle_rfd(c, readset, writeset);
 850         channel_handle_wfd(c, readset, writeset);
 851         channel_handle_efd(c, readset, writeset);
 852         channel_check_window(c, readset, writeset);
 853 }
 854
 855 void
 856 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
 857 {
 858         int len;
 859         /* Send buffered output data to the socket. */
 860         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
 861                 len = write(c->sock, buffer_ptr(&c->output),
 862                             buffer_len(&c->output));
 863                 if (len <= 0)
 864                         buffer_consume(&c->output, buffer_len(&c->output));
 865                 else
 866                         buffer_consume(&c->output, len);
 867         }
 868 }
 869
 870 void
 871 channel_handler_init_20(void)
 872 {
 873         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_20;
 874         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
 875         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 876         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
 877         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
 878         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
 879         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
 880
 881         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_2;
 882         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 883         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
 884         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
 885         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
 886         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
 887 }
 888
 889 void
 890 channel_handler_init_13(void)
 891 {
 892         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
 893         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
 894         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
 895         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 896         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
 897         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
 898         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
 899         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
 900
 901         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_1;
 902         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
 903         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 904         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
 905         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
 906         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
 907 }
 908
 909 void
 910 channel_handler_init_15(void)
 911 {
 912         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_15;
 913         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
 914         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
 915         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 916         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
 917         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
 918
 919         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
 920         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 921         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
 922         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_1;
 923         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
 924 }
 925
 926 void
 927 channel_handler_init(void)
 928 {
 929         int i;
 930         for(i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
 931                 channel_pre[i] = NULL;
 932                 channel_post[i] = NULL;
 933         }
 934         if (compat20)
 935                 channel_handler_init_20();
 936         else if (compat13)
 937                 channel_handler_init_13();
 938         else
 939                 channel_handler_init_15();
 940 }
 941
 942 void
 943 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
 944 {
 945         static int did_init = 0;
 946         int i;
 947         Channel *c;
 948
 949         if (!did_init) {
 950                 channel_handler_init();
 951                 did_init = 1;
 952         }
 953         for (i = 0; i < channels_alloc; i++) {
 954                 c = &channels[i];
 955                 if (c->type == SSH_CHANNEL_FREE)
 956                         continue;
 957                 if (ftab[c->type] == NULL)
 958                         continue;
 959                 (*ftab[c->type])(c, readset, writeset);
 960                 chan_delete_if_full_closed(c);
 961         }
 962 }
 963
 964 void
 965 channel_prepare_select(fd_set * readset, fd_set * writeset)
 966 {
 967         channel_handler(channel_pre, readset, writeset);
 968 }
 969
 970 void
 971 channel_after_select(fd_set * readset, fd_set * writeset)
 972 {
 973         channel_handler(channel_post, readset, writeset);
 974 }
 975
 976 /* If there is data to send to the connection, send some of it now. */
 977
 978 void
 979 channel_output_poll()
 980 {
 981         int len, i;
 982         Channel *c;
 983
 984         for (i = 0; i < channels_alloc; i++) {
 985                 c = &channels[i];
 986
 987                 /* We are only interested in channels that can have buffered incoming data. */
 988                 if (compat13) {
 989                         if (c->type != SSH_CHANNEL_OPEN &&
 990                             c->type != SSH_CHANNEL_INPUT_DRAINING)
 991                                 continue;
 992                 } else {
 993                         if (c->type != SSH_CHANNEL_OPEN)
 994                                 continue;
 995                         if (c->istate != CHAN_INPUT_OPEN &&
 996                             c->istate != CHAN_INPUT_WAIT_DRAIN)
 997                                 continue;
 998                 }
 999                 if (compat20 &&
1000                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1001                         debug("channel: %d: no data after CLOSE", c->self);
1002                         continue;
1003                 }
1004
1005                 /* Get the amount of buffered data for this channel. */
1006                 len = buffer_len(&c->input);
1007                 if (len > 0) {
1008                         /* Send some data for the other side over the secure connection. */
1009                         if (compat20) {
1010                                 if (len > c->remote_window)
1011                                         len = c->remote_window;
1012                                 if (len > c->remote_maxpacket)
1013                                         len = c->remote_maxpacket;
1014                         } else {
1015                                 if (packet_is_interactive()) {
1016                                         if (len > 1024)
1017                                                 len = 512;
1018                                 } else {
1019                                         /* Keep the packets at reasonable size. */
1020                                         if (len > packet_get_maxsize()/2)
1021                                                 len = packet_get_maxsize()/2;
1022                                 }
1023                         }
1024                         if (len > 0) {
1025                                 packet_start(compat20 ?
1026                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1027                                 packet_put_int(c->remote_id);
1028                                 packet_put_string(buffer_ptr(&c->input), len);
1029                                 packet_send();
1030                                 buffer_consume(&c->input, len);
1031                                 c->remote_window -= len;
1032                         }
1033                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1034                         if (compat13)
1035                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1036                         /*
1037                          * input-buffer is empty and read-socket shutdown:
1038                          * tell peer, that we will not send more data: send IEOF
1039                          */
1040                         chan_ibuf_empty(c);
1041                 }
1042                 /* Send extended data, i.e. stderr */
1043                 if (compat20 &&
1044                     c->remote_window > 0 &&
1045                     (len = buffer_len(&c->extended)) > 0 &&
1046                     c->extended_usage == CHAN_EXTENDED_READ) {
1047                         if (len > c->remote_window)
1048                                 len = c->remote_window;
1049                         if (len > c->remote_maxpacket)
1050                                 len = c->remote_maxpacket;
1051                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1052                         packet_put_int(c->remote_id);
1053                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1054                         packet_put_string(buffer_ptr(&c->extended), len);
1055                         packet_send();
1056                         buffer_consume(&c->extended, len);
1057                         c->remote_window -= len;
1058                 }
1059         }
1060 }
1061
1062 /*
1063  * This is called when a packet of type CHANNEL_DATA has just been received.
1064  * The message type has already been consumed, but channel number and data is
1065  * still there.
1066  */
1067
1068 void
1069 channel_input_data(int type, int plen, void *ctxt)
1070 {
1071         int id;
1072         char *data;
1073         u_int data_len;
1074         Channel *c;
1075
1076         /* Get the channel number and verify it. */
1077         id = packet_get_int();
1078         c = channel_lookup(id);
1079         if (c == NULL)
1080                 packet_disconnect("Received data for nonexistent channel %d.", id);
1081
1082         /* Ignore any data for non-open channels (might happen on close) */
1083         if (c->type != SSH_CHANNEL_OPEN &&
1084             c->type != SSH_CHANNEL_X11_OPEN)
1085                 return;
1086
1087         /* same for protocol 1.5 if output end is no longer open */
1088         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN)
1089                 return;
1090
1091         /* Get the data. */
1092         data = packet_get_string(&data_len);
1093         packet_done();
1094
1095         if (compat20){
1096                 if (data_len > c->local_maxpacket) {
1097                         log("channel %d: rcvd big packet %d, maxpack %d",
1098                             c->self, data_len, c->local_maxpacket);
1099                 }
1100                 if (data_len > c->local_window) {
1101                         log("channel %d: rcvd too much data %d, win %d",
1102                             c->self, data_len, c->local_window);
1103                         xfree(data);
1104                         return;
1105                 }
1106                 c->local_window -= data_len;
1107         }else{
1108                 packet_integrity_check(plen, 4 + 4 + data_len, type);
1109         }
1110         buffer_append(&c->output, data, data_len);
1111         xfree(data);
1112 }
1113 void
1114 channel_input_extended_data(int type, int plen, void *ctxt)
1115 {
1116         int id;
1117         int tcode;
1118         char *data;
1119         u_int data_len;
1120         Channel *c;
1121
1122         /* Get the channel number and verify it. */
1123         id = packet_get_int();
1124         c = channel_lookup(id);
1125
1126         if (c == NULL)
1127                 packet_disconnect("Received extended_data for bad channel %d.", id);
1128         if (c->type != SSH_CHANNEL_OPEN) {
1129                 log("channel %d: ext data for non open", id);
1130                 return;
1131         }
1132         tcode = packet_get_int();
1133         if (c->efd == -1 ||
1134             c->extended_usage != CHAN_EXTENDED_WRITE ||
1135             tcode != SSH2_EXTENDED_DATA_STDERR) {
1136                 log("channel %d: bad ext data", c->self);
1137                 return;
1138         }
1139         data = packet_get_string(&data_len);
1140         packet_done();
1141         if (data_len > c->local_window) {
1142                 log("channel %d: rcvd too much extended_data %d, win %d",
1143                     c->self, data_len, c->local_window);
1144                 xfree(data);
1145                 return;
1146         }
1147         debug2("channel %d: rcvd ext data %d", c->self, data_len);
1148         c->local_window -= data_len;
1149         buffer_append(&c->extended, data, data_len);
1150         xfree(data);
1151 }
1152
1153
1154 /*
1155  * Returns true if no channel has too much buffered data, and false if one or
1156  * more channel is overfull.
1157  */
1158
1159 int
1160 channel_not_very_much_buffered_data()
1161 {
1162         u_int i;
1163         Channel *c;
1164
1165         for (i = 0; i < channels_alloc; i++) {
1166                 c = &channels[i];
1167                 if (c->type == SSH_CHANNEL_OPEN) {
1168                         if (!compat20 && buffer_len(&c->input) > packet_get_maxsize()) {
1169                                 debug("channel %d: big input buffer %d",
1170                                     c->self, buffer_len(&c->input));
1171                                 return 0;
1172                         }
1173                         if (buffer_len(&c->output) > packet_get_maxsize()) {
1174                                 debug("channel %d: big output buffer %d",
1175                                     c->self, buffer_len(&c->output));
1176                                 return 0;
1177                         }
1178                 }
1179         }
1180         return 1;
1181 }
1182
1183 void
1184 channel_input_ieof(int type, int plen, void *ctxt)
1185 {
1186         int id;
1187         Channel *c;
1188
1189         packet_integrity_check(plen, 4, type);
1190
1191         id = packet_get_int();
1192         c = channel_lookup(id);
1193         if (c == NULL)
1194                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
1195         chan_rcvd_ieof(c);
1196 }
1197
1198 void
1199 channel_input_close(int type, int plen, void *ctxt)
1200 {
1201         int id;
1202         Channel *c;
1203
1204         packet_integrity_check(plen, 4, type);
1205
1206         id = packet_get_int();
1207         c = channel_lookup(id);
1208         if (c == NULL)
1209                 packet_disconnect("Received close for nonexistent channel %d.", id);
1210
1211         /*
1212          * Send a confirmation that we have closed the channel and no more
1213          * data is coming for it.
1214          */
1215         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
1216         packet_put_int(c->remote_id);
1217         packet_send();
1218
1219         /*
1220          * If the channel is in closed state, we have sent a close request,
1221          * and the other side will eventually respond with a confirmation.
1222          * Thus, we cannot free the channel here, because then there would be
1223          * no-one to receive the confirmation.  The channel gets freed when
1224          * the confirmation arrives.
1225          */
1226         if (c->type != SSH_CHANNEL_CLOSED) {
1227                 /*
1228                  * Not a closed channel - mark it as draining, which will
1229                  * cause it to be freed later.
1230                  */
1231                 buffer_consume(&c->input, buffer_len(&c->input));
1232                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
1233         }
1234 }
1235
1236 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
1237 void
1238 channel_input_oclose(int type, int plen, void *ctxt)
1239 {
1240         int id = packet_get_int();
1241         Channel *c = channel_lookup(id);
1242         packet_integrity_check(plen, 4, type);
1243         if (c == NULL)
1244                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
1245         chan_rcvd_oclose(c);
1246 }
1247
1248 void
1249 channel_input_close_confirmation(int type, int plen, void *ctxt)
1250 {
1251         int id = packet_get_int();
1252         Channel *c = channel_lookup(id);
1253
1254         packet_done();
1255         if (c == NULL)
1256                 packet_disconnect("Received close confirmation for "
1257                     "out-of-range channel %d.", id);
1258         if (c->type != SSH_CHANNEL_CLOSED)
1259                 packet_disconnect("Received close confirmation for "
1260                     "non-closed channel %d (type %d).", id, c->type);
1261         channel_free(c->self);
1262 }
1263
1264 void
1265 channel_input_open_confirmation(int type, int plen, void *ctxt)
1266 {
1267         int id, remote_id;
1268         Channel *c;
1269
1270         if (!compat20)
1271                 packet_integrity_check(plen, 4 + 4, type);
1272
1273         id = packet_get_int();
1274         c = channel_lookup(id);
1275
1276         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
1277                 packet_disconnect("Received open confirmation for "
1278                     "non-opening channel %d.", id);
1279         remote_id = packet_get_int();
1280         /* Record the remote channel number and mark that the channel is now open. */
1281         c->remote_id = remote_id;
1282         c->type = SSH_CHANNEL_OPEN;
1283
1284         if (compat20) {
1285                 c->remote_window = packet_get_int();
1286                 c->remote_maxpacket = packet_get_int();
1287                 packet_done();
1288                 if (c->cb_fn != NULL && c->cb_event == type) {
1289                         debug2("callback start");
1290                         c->cb_fn(c->self, c->cb_arg);
1291                         debug2("callback done");
1292                 }
1293                 debug("channel %d: open confirm rwindow %d rmax %d", c->self,
1294                     c->remote_window, c->remote_maxpacket);
1295         }
1296 }
1297
1298 void
1299 channel_input_open_failure(int type, int plen, void *ctxt)
1300 {
1301         int id;
1302         Channel *c;
1303
1304         if (!compat20)
1305                 packet_integrity_check(plen, 4, type);
1306
1307         id = packet_get_int();
1308         c = channel_lookup(id);
1309
1310         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
1311                 packet_disconnect("Received open failure for "
1312                     "non-opening channel %d.", id);
1313         if (compat20) {
1314                 int reason = packet_get_int();
1315                 char *msg  = packet_get_string(NULL);
1316                 char *lang  = packet_get_string(NULL);
1317                 log("channel_open_failure: %d: reason %d: %s", id, reason, msg);
1318                 packet_done();
1319                 xfree(msg);
1320                 xfree(lang);
1321         }
1322         /* Free the channel.  This will also close the socket. */
1323         channel_free(id);
1324 }
1325
1326 void
1327 channel_input_channel_request(int type, int plen, void *ctxt)
1328 {
1329         int id;
1330         Channel *c;
1331
1332         id = packet_get_int();
1333         c = channel_lookup(id);
1334
1335         if (c == NULL ||
1336             (c->type != SSH_CHANNEL_OPEN && c->type != SSH_CHANNEL_LARVAL))
1337                 packet_disconnect("Received request for "
1338                     "non-open channel %d.", id);
1339         if (c->cb_fn != NULL && c->cb_event == type) {
1340                 debug2("callback start");
1341                 c->cb_fn(c->self, c->cb_arg);
1342                 debug2("callback done");
1343         } else {
1344                 char *service = packet_get_string(NULL);
1345                 debug("channel: %d rcvd request for %s", c->self, service);
1346                 debug("cb_fn %p cb_event %d", c->cb_fn , c->cb_event);
1347                 xfree(service);
1348         }
1349 }
1350
1351 void
1352 channel_input_window_adjust(int type, int plen, void *ctxt)
1353 {
1354         Channel *c;
1355         int id, adjust;
1356
1357         if (!compat20)
1358                 return;
1359
1360         /* Get the channel number and verify it. */
1361         id = packet_get_int();
1362         c = channel_lookup(id);
1363
1364         if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
1365                 log("Received window adjust for "
1366                     "non-open channel %d.", id);
1367                 return;
1368         }
1369         adjust = packet_get_int();
1370         packet_done();
1371         debug2("channel %d: rcvd adjust %d", id, adjust);
1372         c->remote_window += adjust;
1373 }
1374
1375 /*
1376  * Stops listening for channels, and removes any unix domain sockets that we
1377  * might have.
1378  */
1379
1380 void
1381 channel_stop_listening()
1382 {
1383         int i;
1384         for (i = 0; i < channels_alloc; i++) {
1385                 switch (channels[i].type) {
1386                 case SSH_CHANNEL_AUTH_SOCKET:
1387                         close(channels[i].sock);
1388                         unlink(channels[i].path);
1389                         channel_free(i);
1390                         break;
1391                 case SSH_CHANNEL_PORT_LISTENER:
1392                 case SSH_CHANNEL_RPORT_LISTENER:
1393                 case SSH_CHANNEL_X11_LISTENER:
1394                         close(channels[i].sock);
1395                         channel_free(i);
1396                         break;
1397                 default:
1398                         break;
1399                 }
1400         }
1401 }
1402
1403 /*
1404  * Closes the sockets/fds of all channels.  This is used to close extra file
1405  * descriptors after a fork.
1406  */
1407
1408 void
1409 channel_close_all()
1410 {
1411         int i;
1412         for (i = 0; i < channels_alloc; i++)
1413                 if (channels[i].type != SSH_CHANNEL_FREE)
1414                         channel_close_fds(&channels[i]);
1415 }
1416
1417 /* Returns the maximum file descriptor number used by the channels. */
1418
1419 int
1420 channel_max_fd()
1421 {
1422         return channel_max_fd_value;
1423 }
1424
1425 /* Returns true if any channel is still open. */
1426
1427 int
1428 channel_still_open()
1429 {
1430         u_int i;
1431         for (i = 0; i < channels_alloc; i++)
1432                 switch (channels[i].type) {
1433                 case SSH_CHANNEL_FREE:
1434                 case SSH_CHANNEL_X11_LISTENER:
1435                 case SSH_CHANNEL_PORT_LISTENER:
1436                 case SSH_CHANNEL_RPORT_LISTENER:
1437                 case SSH_CHANNEL_CLOSED:
1438                 case SSH_CHANNEL_AUTH_SOCKET:
1439                 case SSH_CHANNEL_CONNECTING:    /* XXX ??? */
1440                         continue;
1441                 case SSH_CHANNEL_LARVAL:
1442                         if (!compat20)
1443                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
1444                         continue;
1445                 case SSH_CHANNEL_OPENING:
1446                 case SSH_CHANNEL_OPEN:
1447                 case SSH_CHANNEL_X11_OPEN:
1448                         return 1;
1449                 case SSH_CHANNEL_INPUT_DRAINING:
1450                 case SSH_CHANNEL_OUTPUT_DRAINING:
1451                         if (!compat13)
1452                                 fatal("cannot happen: OUT_DRAIN");
1453                         return 1;
1454                 default:
1455                         fatal("channel_still_open: bad channel type %d", channels[i].type);
1456                         /* NOTREACHED */
1457                 }
1458         return 0;
1459 }
1460
1461 /*
1462  * Returns a message describing the currently open forwarded connections,
1463  * suitable for sending to the client.  The message contains crlf pairs for
1464  * newlines.
1465  */
1466
1467 char *
1468 channel_open_message()
1469 {
1470         Buffer buffer;
1471         int i;
1472         char buf[512], *cp;
1473
1474         buffer_init(&buffer);
1475         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
1476         buffer_append(&buffer, buf, strlen(buf));
1477         for (i = 0; i < channels_alloc; i++) {
1478                 Channel *c = &channels[i];
1479                 switch (c->type) {
1480                 case SSH_CHANNEL_FREE:
1481                 case SSH_CHANNEL_X11_LISTENER:
1482                 case SSH_CHANNEL_PORT_LISTENER:
1483                 case SSH_CHANNEL_RPORT_LISTENER:
1484                 case SSH_CHANNEL_CLOSED:
1485                 case SSH_CHANNEL_AUTH_SOCKET:
1486                         continue;
1487                 case SSH_CHANNEL_LARVAL:
1488                 case SSH_CHANNEL_OPENING:
1489                 case SSH_CHANNEL_CONNECTING:
1490                 case SSH_CHANNEL_OPEN:
1491                 case SSH_CHANNEL_X11_OPEN:
1492                 case SSH_CHANNEL_INPUT_DRAINING:
1493                 case SSH_CHANNEL_OUTPUT_DRAINING:
1494                         snprintf(buf, sizeof buf, "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d)\r\n",
1495                             c->self, c->remote_name,
1496                             c->type, c->remote_id,
1497                             c->istate, buffer_len(&c->input),
1498                             c->ostate, buffer_len(&c->output),
1499                             c->rfd, c->wfd);
1500                         buffer_append(&buffer, buf, strlen(buf));
1501                         continue;
1502                 default:
1503                         fatal("channel_open_message: bad channel type %d", c->type);
1504                         /* NOTREACHED */
1505                 }
1506         }
1507         buffer_append(&buffer, "\0", 1);
1508         cp = xstrdup(buffer_ptr(&buffer));
1509         buffer_free(&buffer);
1510         return cp;
1511 }
1512
1513 /*
1514  * Initiate forwarding of connections to local port "port" through the secure
1515  * channel to host:port from remote side.
1516  */
1517 void
1518 channel_request_local_forwarding(u_short listen_port, const char *host_to_connect,
1519     u_short port_to_connect, int gateway_ports)
1520 {
1521         channel_request_forwarding(
1522             NULL, listen_port,
1523             host_to_connect, port_to_connect,
1524             gateway_ports, /*remote_fwd*/ 0);
1525 }
1526
1527 /*
1528  * If 'remote_fwd' is true we have a '-R style' listener for protocol 2
1529  * (SSH_CHANNEL_RPORT_LISTENER).
1530  */
1531 void
1532 channel_request_forwarding(
1533     const char *listen_address, u_short listen_port,
1534     const char *host_to_connect, u_short port_to_connect,
1535     int gateway_ports, int remote_fwd)
1536 {
1537         int success, ch, sock, on = 1, ctype;
1538         struct addrinfo hints, *ai, *aitop;
1539         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1540         const char *host;
1541         struct linger linger;
1542
1543         if (remote_fwd) {
1544                 host = listen_address;
1545                 ctype = SSH_CHANNEL_RPORT_LISTENER;
1546         } else {
1547                 host = host_to_connect;
1548                 ctype  =SSH_CHANNEL_PORT_LISTENER;
1549         }
1550
1551         if (strlen(host) > sizeof(channels[0].path) - 1)
1552                 packet_disconnect("Forward host name too long.");
1553
1554         /* XXX listen_address is currently ignored */
1555         /*
1556          * getaddrinfo returns a loopback address if the hostname is
1557          * set to NULL and hints.ai_flags is not AI_PASSIVE
1558          */
1559         memset(&hints, 0, sizeof(hints));
1560         hints.ai_family = IPv4or6;
1561         hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
1562         hints.ai_socktype = SOCK_STREAM;
1563         snprintf(strport, sizeof strport, "%d", listen_port);
1564         if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
1565                 packet_disconnect("getaddrinfo: fatal error");
1566
1567         success = 0;
1568         for (ai = aitop; ai; ai = ai->ai_next) {
1569                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1570                         continue;
1571                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
1572                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1573                         error("channel_request_forwarding: getnameinfo failed");
1574                         continue;
1575                 }
1576                 /* Create a port to listen for the host. */
1577                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1578                 if (sock < 0) {
1579                         /* this is no error since kernel may not support ipv6 */
1580                         verbose("socket: %.100s", strerror(errno));
1581                         continue;
1582                 }
1583                 /*
1584                  * Set socket options.  We would like the socket to disappear
1585                  * as soon as it has been closed for whatever reason.
1586                  */
1587                 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));
1588                 linger.l_onoff = 1;
1589                 linger.l_linger = 5;
1590                 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
1591                 debug("Local forwarding listening on %s port %s.", ntop, strport);
1592
1593                 /* Bind the socket to the address. */
1594                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1595                         /* address can be in use ipv6 address is already bound */
1596                         if (!ai->ai_next)
1597                                 error("bind: %.100s", strerror(errno));
1598                         else
1599                                 verbose("bind: %.100s", strerror(errno));
1600
1601                         close(sock);
1602                         continue;
1603                 }
1604                 /* Start listening for connections on the socket. */
1605                 if (listen(sock, 5) < 0) {
1606                         error("listen: %.100s", strerror(errno));
1607                         close(sock);
1608                         continue;
1609                 }
1610                 /* Allocate a channel number for the socket. */
1611                 ch = channel_new("port listener", ctype, sock, sock, -1,
1612                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1613                     0, xstrdup("port listener"), 1);
1614                 strlcpy(channels[ch].path, host, sizeof(channels[ch].path));
1615                 channels[ch].host_port = port_to_connect;
1616                 channels[ch].listening_port = listen_port;
1617                 success = 1;
1618         }
1619         if (success == 0)
1620                 packet_disconnect("cannot listen port: %d", listen_port);       /*XXX ?disconnect? */
1621         freeaddrinfo(aitop);
1622 }
1623
1624 /*
1625  * Initiate forwarding of connections to port "port" on remote host through
1626  * the secure channel to host:port from local side.
1627  */
1628
1629 void
1630 channel_request_remote_forwarding(u_short listen_port,
1631     const char *host_to_connect, u_short port_to_connect)
1632 {
1633         int payload_len, type, success = 0;
1634
1635         /* Record locally that connection to this host/port is permitted. */
1636         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
1637                 fatal("channel_request_remote_forwarding: too many forwards");
1638
1639         /* Send the forward request to the remote side. */
1640         if (compat20) {
1641                 const char *address_to_bind = "0.0.0.0";
1642                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1643                 packet_put_cstring("tcpip-forward");
1644                 packet_put_char(0);                     /* boolean: want reply */
1645                 packet_put_cstring(address_to_bind);
1646                 packet_put_int(listen_port);
1647                 packet_send();
1648                 packet_write_wait();
1649                 /* Assume that server accepts the request */
1650                 success = 1;
1651         } else {
1652                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
1653                 packet_put_int(listen_port);
1654                 packet_put_cstring(host_to_connect);
1655                 packet_put_int(port_to_connect);
1656                 packet_send();
1657                 packet_write_wait();
1658
1659                 /* Wait for response from the remote side. */
1660                 type = packet_read(&payload_len);
1661                 switch (type) {
1662                 case SSH_SMSG_SUCCESS:
1663                         success = 1;
1664                         break;
1665                 case SSH_SMSG_FAILURE:
1666                         log("Warning: Server denied remote port forwarding.");
1667                         break;
1668                 default:
1669                         /* Unknown packet */
1670                         packet_disconnect("Protocol error for port forward request:"
1671                             "received packet type %d.", type);
1672                 }
1673         }
1674         if (success) {
1675                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
1676                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
1677                 permitted_opens[num_permitted_opens].listen_port = listen_port;
1678                 num_permitted_opens++;
1679         }
1680 }
1681
1682 /*
1683  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
1684  * listening for the port, and sends back a success reply (or disconnect
1685  * message if there was an error).  This never returns if there was an error.
1686  */
1687
1688 void
1689 channel_input_port_forward_request(int is_root, int gateway_ports)
1690 {
1691         u_short port, host_port;
1692         char *hostname;
1693
1694         /* Get arguments from the packet. */
1695         port = packet_get_int();
1696         hostname = packet_get_string(NULL);
1697         host_port = packet_get_int();
1698
1699 #ifndef HAVE_CYGWIN
1700         /*
1701          * Check that an unprivileged user is not trying to forward a
1702          * privileged port.
1703          */
1704         if (port < IPPORT_RESERVED && !is_root)
1705                 packet_disconnect("Requested forwarding of port %d but user is not root.",
1706                                   port);
1707 #endif
1708         /* Initiate forwarding */
1709         channel_request_local_forwarding(port, hostname, host_port, gateway_ports);
1710
1711         /* Free the argument string. */
1712         xfree(hostname);
1713 }
1714
1715 /* XXX move to aux.c */
1716 int
1717 channel_connect_to(const char *host, u_short host_port)
1718 {
1719         struct addrinfo hints, *ai, *aitop;
1720         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1721         int gaierr;
1722         int sock = -1;
1723
1724         memset(&hints, 0, sizeof(hints));
1725         hints.ai_family = IPv4or6;
1726         hints.ai_socktype = SOCK_STREAM;
1727         snprintf(strport, sizeof strport, "%d", host_port);
1728         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
1729                 error("%.100s: unknown host (%s)", host, gai_strerror(gaierr));
1730                 return -1;
1731         }
1732         for (ai = aitop; ai; ai = ai->ai_next) {
1733                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1734                         continue;
1735                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
1736                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1737                         error("channel_connect_to: getnameinfo failed");
1738                         continue;
1739                 }
1740                 /* Create the socket. */
1741                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1742                 if (sock < 0) {
1743                         error("socket: %.100s", strerror(errno));
1744                         continue;
1745                 }
1746                 if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0)
1747                         fatal("connect_to: F_SETFL: %s", strerror(errno));
1748                 /* Connect to the host/port. */
1749                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
1750                     errno != EINPROGRESS) {
1751                         error("connect %.100s port %s: %.100s", ntop, strport,
1752                             strerror(errno));
1753                         close(sock);
1754                         continue;       /* fail -- try next */
1755                 }
1756                 break; /* success */
1757
1758         }
1759         freeaddrinfo(aitop);
1760         if (!ai) {
1761                 error("connect %.100s port %d: failed.", host, host_port);
1762                 return -1;
1763         }
1764         /* success */
1765         return sock;
1766 }
1767 int
1768 channel_connect_by_listen_adress(u_short listen_port)
1769 {
1770         int i;
1771         for (i = 0; i < num_permitted_opens; i++)
1772                 if (permitted_opens[i].listen_port == listen_port)
1773                         return channel_connect_to(
1774                             permitted_opens[i].host_to_connect,
1775                             permitted_opens[i].port_to_connect);
1776         error("WARNING: Server requests forwarding for unknown listen_port %d",
1777             listen_port);
1778         return -1;
1779 }
1780
1781 /*
1782  * This is called after receiving PORT_OPEN message.  This attempts to
1783  * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
1784  * or CHANNEL_OPEN_FAILURE.
1785  */
1786
1787 void
1788 channel_input_port_open(int type, int plen, void *ctxt)
1789 {
1790         u_short host_port;
1791         char *host, *originator_string;
1792         int remote_channel, sock = -1, newch, i, denied;
1793         u_int host_len, originator_len;
1794
1795         /* Get remote channel number. */
1796         remote_channel = packet_get_int();
1797
1798         /* Get host name to connect to. */
1799         host = packet_get_string(&host_len);
1800
1801         /* Get port to connect to. */
1802         host_port = packet_get_int();
1803
1804         /* Get remote originator name. */
1805         if (have_hostname_in_open) {
1806                 originator_string = packet_get_string(&originator_len);
1807                 originator_len += 4;    /* size of packet_int */
1808         } else {
1809                 originator_string = xstrdup("unknown (remote did not supply name)");
1810                 originator_len = 0;     /* no originator supplied */
1811         }
1812
1813         packet_integrity_check(plen,
1814             4 + 4 + host_len + 4 + originator_len, SSH_MSG_PORT_OPEN);
1815
1816         /* Check if opening that port is permitted. */
1817         denied = 0;
1818         if (!all_opens_permitted) {
1819                 /* Go trough all permitted ports. */
1820                 for (i = 0; i < num_permitted_opens; i++)
1821                         if (permitted_opens[i].port_to_connect == host_port &&
1822                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
1823                                 break;
1824
1825                 /* Check if we found the requested port among those permitted. */
1826                 if (i >= num_permitted_opens) {
1827                         /* The port is not permitted. */
1828                         log("Received request to connect to %.100s:%d, but the request was denied.",
1829                             host, host_port);
1830                         denied = 1;
1831                 }
1832         }
1833         sock = denied ? -1 : channel_connect_to(host, host_port);
1834         if (sock > 0) {
1835                 /* Allocate a channel for this connection. */
1836                 newch = channel_allocate(SSH_CHANNEL_CONNECTING,
1837                     sock, originator_string);
1838 /*XXX delay answer? */
1839                 channels[newch].remote_id = remote_channel;
1840
1841                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1842                 packet_put_int(remote_channel);
1843                 packet_put_int(newch);
1844                 packet_send();
1845         } else {
1846                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1847                 packet_put_int(remote_channel);
1848                 packet_send();
1849         }
1850         xfree(host);
1851 }
1852
1853 /*
1854  * Creates an internet domain socket for listening for X11 connections.
1855  * Returns a suitable value for the DISPLAY variable, or NULL if an error
1856  * occurs.
1857  */
1858
1859 #define NUM_SOCKS       10
1860
1861 char *
1862 x11_create_display_inet(int screen_number, int x11_display_offset)
1863 {
1864         int display_number, sock;
1865         u_short port;
1866         struct addrinfo hints, *ai, *aitop;
1867         char strport[NI_MAXSERV];
1868         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
1869         char display[512];
1870         char hostname[MAXHOSTNAMELEN];
1871
1872         for (display_number = x11_display_offset;
1873              display_number < MAX_DISPLAYS;
1874              display_number++) {
1875                 port = 6000 + display_number;
1876                 memset(&hints, 0, sizeof(hints));
1877                 hints.ai_family = IPv4or6;
1878                 hints.ai_flags = AI_PASSIVE;            /* XXX loopback only ? */
1879                 hints.ai_socktype = SOCK_STREAM;
1880                 snprintf(strport, sizeof strport, "%d", port);
1881                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
1882                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
1883                         return NULL;
1884                 }
1885                 for (ai = aitop; ai; ai = ai->ai_next) {
1886                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1887                                 continue;
1888                         sock = socket(ai->ai_family, SOCK_STREAM, 0);
1889                         if (sock < 0) {
1890                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
1891                                         error("socket: %.100s", strerror(errno));
1892                                         return NULL;
1893                                 } else {
1894                                         debug("x11_create_display_inet: Socket family %d not supported",
1895                                                  ai->ai_family);
1896                                         continue;
1897                                 }
1898                         }
1899                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1900                                 debug("bind port %d: %.100s", port, strerror(errno));
1901                                 shutdown(sock, SHUT_RDWR);
1902                                 close(sock);
1903
1904                                 if (ai->ai_next)
1905                                         continue;
1906
1907                                 for (n = 0; n < num_socks; n++) {
1908                                         shutdown(socks[n], SHUT_RDWR);
1909                                         close(socks[n]);
1910                                 }
1911                                 num_socks = 0;
1912                                 break;
1913                         }
1914                         socks[num_socks++] = sock;
1915 #ifndef DONT_TRY_OTHER_AF
1916                         if (num_socks == NUM_SOCKS)
1917                                 break;
1918 #else
1919                         break;
1920 #endif
1921                 }
1922                 if (num_socks > 0)
1923                         break;
1924         }
1925         if (display_number >= MAX_DISPLAYS) {
1926                 error("Failed to allocate internet-domain X11 display socket.");
1927                 return NULL;
1928         }
1929         /* Start listening for connections on the socket. */
1930         for (n = 0; n < num_socks; n++) {
1931                 sock = socks[n];
1932                 if (listen(sock, 5) < 0) {
1933                         error("listen: %.100s", strerror(errno));
1934                         shutdown(sock, SHUT_RDWR);
1935                         close(sock);
1936                         return NULL;
1937                 }
1938         }
1939
1940         /* Set up a suitable value for the DISPLAY variable. */
1941         if (gethostname(hostname, sizeof(hostname)) < 0)
1942                 fatal("gethostname: %.100s", strerror(errno));
1943
1944 #ifdef IPADDR_IN_DISPLAY
1945         /*
1946          * HPUX detects the local hostname in the DISPLAY variable and tries
1947          * to set up a shared memory connection to the server, which it
1948          * incorrectly supposes to be local.
1949          *
1950          * The workaround - as used in later $$H and other programs - is
1951          * is to set display to the host's IP address.
1952          */
1953         {
1954                 struct hostent *he;
1955                 struct in_addr my_addr;
1956
1957                 he = gethostbyname(hostname);
1958                 if (he == NULL) {
1959                         error("[X11-broken-fwd-hostname-workaround] Could not get "
1960                                 "IP address for hostname %s.", hostname);
1961
1962                         packet_send_debug("[X11-broken-fwd-hostname-workaround]"
1963                                 "Could not get IP address for hostname %s.", hostname);
1964
1965                         shutdown(sock, SHUT_RDWR);
1966                         close(sock);
1967
1968                         return NULL;
1969                 }
1970
1971                 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
1972
1973                 /* Set DISPLAY to <ip address>:screen.display */
1974                 snprintf(display, sizeof(display), "%.50s:%d.%d", inet_ntoa(my_addr),
1975                          display_number, screen_number);
1976         }
1977 #else /* IPADDR_IN_DISPLAY */
1978         /* Just set DISPLAY to hostname:screen.display */
1979         snprintf(display, sizeof display, "%.400s:%d.%d", hostname,
1980                  display_number, screen_number);
1981 #endif /* IPADDR_IN_DISPLAY */
1982
1983         /* Allocate a channel for each socket. */
1984         for (n = 0; n < num_socks; n++) {
1985                 sock = socks[n];
1986                 (void) channel_new("x11 listener",
1987                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
1988                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
1989                     0, xstrdup("X11 inet listener"), 1);
1990         }
1991
1992         /* Return a suitable value for the DISPLAY environment variable. */
1993         return xstrdup(display);
1994 }
1995
1996 #ifndef X_UNIX_PATH
1997 #define X_UNIX_PATH "/tmp/.X11-unix/X"
1998 #endif
1999
2000 static
2001 int
2002 connect_local_xsocket(u_int dnr)
2003 {
2004         static const char *const x_sockets[] = {
2005                 X_UNIX_PATH "%u",
2006                 "/var/X/.X11-unix/X" "%u",
2007                 "/usr/spool/sockets/X11/" "%u",
2008                 NULL
2009         };
2010         int sock;
2011         struct sockaddr_un addr;
2012         const char *const * path;
2013
2014         for (path = x_sockets; *path; ++path) {
2015                 sock = socket(AF_UNIX, SOCK_STREAM, 0);
2016                 if (sock < 0)
2017                         error("socket: %.100s", strerror(errno));
2018                 memset(&addr, 0, sizeof(addr));
2019                 addr.sun_family = AF_UNIX;
2020                 snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr);
2021                 if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2022                         return sock;
2023                 close(sock);
2024         }
2025         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2026         return -1;
2027 }
2028
2029 int
2030 x11_connect_display(void)
2031 {
2032         int display_number, sock = 0;
2033         const char *display;
2034         char buf[1024], *cp;
2035         struct addrinfo hints, *ai, *aitop;
2036         char strport[NI_MAXSERV];
2037         int gaierr;
2038
2039         /* Try to open a socket for the local X server. */
2040         display = getenv("DISPLAY");
2041         if (!display) {
2042                 error("DISPLAY not set.");
2043                 return -1;
2044         }
2045         /*
2046          * Now we decode the value of the DISPLAY variable and make a
2047          * connection to the real X server.
2048          */
2049
2050         /*
2051          * Check if it is a unix domain socket.  Unix domain displays are in
2052          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2053          */
2054         if (strncmp(display, "unix:", 5) == 0 ||
2055             display[0] == ':') {
2056                 /* Connect to the unix domain socket. */
2057                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2058                         error("Could not parse display number from DISPLAY: %.100s",
2059                               display);
2060                         return -1;
2061                 }
2062                 /* Create a socket. */
2063                 sock = connect_local_xsocket(display_number);
2064                 if (sock < 0)
2065                         return -1;
2066
2067                 /* OK, we now have a connection to the display. */
2068                 return sock;
2069         }
2070         /*
2071          * Connect to an inet socket.  The DISPLAY value is supposedly
2072          * hostname:d[.s], where hostname may also be numeric IP address.
2073          */
2074         strncpy(buf, display, sizeof(buf));
2075         buf[sizeof(buf) - 1] = 0;
2076         cp = strchr(buf, ':');
2077         if (!cp) {
2078                 error("Could not find ':' in DISPLAY: %.100s", display);
2079                 return -1;
2080         }
2081         *cp = 0;
2082         /* buf now contains the host name.  But first we parse the display number. */
2083         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2084                 error("Could not parse display number from DISPLAY: %.100s",
2085                       display);
2086                 return -1;
2087         }
2088
2089         /* Look up the host address */
2090         memset(&hints, 0, sizeof(hints));
2091         hints.ai_family = IPv4or6;
2092         hints.ai_socktype = SOCK_STREAM;
2093         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2094         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2095                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2096                 return -1;
2097         }
2098         for (ai = aitop; ai; ai = ai->ai_next) {
2099                 /* Create a socket. */
2100                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
2101                 if (sock < 0) {
2102                         debug("socket: %.100s", strerror(errno));
2103                         continue;
2104                 }
2105                 /* Connect it to the display. */
2106                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2107                         debug("connect %.100s port %d: %.100s", buf,
2108                             6000 + display_number, strerror(errno));
2109                         close(sock);
2110                         continue;
2111                 }
2112                 /* Success */
2113                 break;
2114         }
2115         freeaddrinfo(aitop);
2116         if (!ai) {
2117                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2118                     strerror(errno));
2119                 return -1;
2120         }
2121         return sock;
2122 }
2123
2124 /*
2125  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2126  * the remote channel number.  We should do whatever we want, and respond
2127  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2128  */
2129
2130 void
2131 x11_input_open(int type, int plen, void *ctxt)
2132 {
2133         int remote_channel, sock = 0, newch;
2134         char *remote_host;
2135         u_int remote_len;
2136
2137         /* Get remote channel number. */
2138         remote_channel = packet_get_int();
2139
2140         /* Get remote originator name. */
2141         if (have_hostname_in_open) {
2142                 remote_host = packet_get_string(&remote_len);
2143                 remote_len += 4;
2144         } else {
2145                 remote_host = xstrdup("unknown (remote did not supply name)");
2146                 remote_len = 0;
2147         }
2148
2149         debug("Received X11 open request.");
2150         packet_integrity_check(plen, 4 + remote_len, SSH_SMSG_X11_OPEN);
2151
2152         /* Obtain a connection to the real X display. */
2153         sock = x11_connect_display();
2154         if (sock == -1) {
2155                 /* Send refusal to the remote host. */
2156                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2157                 packet_put_int(remote_channel);
2158                 packet_send();
2159         } else {
2160                 /* Allocate a channel for this connection. */
2161                 newch = channel_allocate(
2162                      (x11_saved_proto == NULL) ?
2163                      SSH_CHANNEL_OPEN : SSH_CHANNEL_X11_OPEN,
2164                      sock, remote_host);
2165                 channels[newch].remote_id = remote_channel;
2166
2167                 /* Send a confirmation to the remote host. */
2168                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2169                 packet_put_int(remote_channel);
2170                 packet_put_int(newch);
2171                 packet_send();
2172         }
2173 }
2174
2175 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
2176 void
2177 deny_input_open(int type, int plen, void *ctxt)
2178 {
2179         int rchan = packet_get_int();
2180         switch(type){
2181         case SSH_SMSG_AGENT_OPEN:
2182                 error("Warning: ssh server tried agent forwarding.");
2183                 break;
2184         case SSH_SMSG_X11_OPEN:
2185                 error("Warning: ssh server tried X11 forwarding.");
2186                 break;
2187         default:
2188                 error("deny_input_open: type %d plen %d", type, plen);
2189                 break;
2190         }
2191         error("Warning: this is probably a break in attempt by a malicious server.");
2192         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2193         packet_put_int(rchan);
2194         packet_send();
2195 }
2196
2197 /*
2198  * Requests forwarding of X11 connections, generates fake authentication
2199  * data, and enables authentication spoofing.
2200  */
2201
2202 void
2203 x11_request_forwarding_with_spoofing(int client_session_id,
2204     const char *proto, const char *data)
2205 {
2206         u_int data_len = (u_int) strlen(data) / 2;
2207         u_int i, value;
2208         char *new_data;
2209         int screen_number;
2210         const char *cp;
2211         u_int32_t rand = 0;
2212
2213         cp = getenv("DISPLAY");
2214         if (cp)
2215                 cp = strchr(cp, ':');
2216         if (cp)
2217                 cp = strchr(cp, '.');
2218         if (cp)
2219                 screen_number = atoi(cp + 1);
2220         else
2221                 screen_number = 0;
2222
2223         /* Save protocol name. */
2224         x11_saved_proto = xstrdup(proto);
2225
2226         /*
2227          * Extract real authentication data and generate fake data of the
2228          * same length.
2229          */
2230         x11_saved_data = xmalloc(data_len);
2231         x11_fake_data = xmalloc(data_len);
2232         for (i = 0; i < data_len; i++) {
2233                 if (sscanf(data + 2 * i, "%2x", &value) != 1)
2234                         fatal("x11_request_forwarding: bad authentication data: %.100s", data);
2235                 if (i % 4 == 0)
2236                         rand = arc4random();
2237                 x11_saved_data[i] = value;
2238                 x11_fake_data[i] = rand & 0xff;
2239                 rand >>= 8;
2240         }
2241         x11_saved_data_len = data_len;
2242         x11_fake_data_len = data_len;
2243
2244         /* Convert the fake data into hex. */
2245         new_data = xmalloc(2 * data_len + 1);
2246         for (i = 0; i < data_len; i++)
2247                 sprintf(new_data + 2 * i, "%02x", (u_char) x11_fake_data[i]);
2248
2249         /* Send the request packet. */
2250         if (compat20) {
2251                 channel_request_start(client_session_id, "x11-req", 0);
2252                 packet_put_char(0);     /* XXX bool single connection */
2253         } else {
2254                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
2255         }
2256         packet_put_cstring(proto);
2257         packet_put_cstring(new_data);
2258         packet_put_int(screen_number);
2259         packet_send();
2260         packet_write_wait();
2261         xfree(new_data);
2262 }
2263
2264 /* Sends a message to the server to request authentication fd forwarding. */
2265
2266 void
2267 auth_request_forwarding()
2268 {
2269         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
2270         packet_send();
2271         packet_write_wait();
2272 }
2273
2274 /*
2275  * Returns the name of the forwarded authentication socket.  Returns NULL if
2276  * there is no forwarded authentication socket.  The returned value points to
2277  * a static buffer.
2278  */
2279
2280 char *
2281 auth_get_socket_name()
2282 {
2283         return channel_forwarded_auth_socket_name;
2284 }
2285
2286 /* removes the agent forwarding socket */
2287
2288 void
2289 cleanup_socket(void)
2290 {
2291         unlink(channel_forwarded_auth_socket_name);
2292         rmdir(channel_forwarded_auth_socket_dir);
2293 }
2294
2295 /*
2296  * This is called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
2297  * This starts forwarding authentication requests.
2298  */
2299
2300 int
2301 auth_input_request_forwarding(struct passwd * pw)
2302 {
2303         int sock, newch;
2304         struct sockaddr_un sunaddr;
2305
2306         if (auth_get_socket_name() != NULL)
2307                 fatal("Protocol error: authentication forwarding requested twice.");
2308
2309         /* Temporarily drop privileged uid for mkdir/bind. */
2310         temporarily_use_uid(pw->pw_uid);
2311
2312         /* Allocate a buffer for the socket name, and format the name. */
2313         channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
2314         channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME);
2315         strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME);
2316
2317         /* Create private directory for socket */
2318         if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) {
2319                 packet_send_debug("Agent forwarding disabled: mkdtemp() failed: %.100s",
2320                     strerror(errno));
2321                 restore_uid();
2322                 xfree(channel_forwarded_auth_socket_name);
2323                 xfree(channel_forwarded_auth_socket_dir);
2324                 channel_forwarded_auth_socket_name = NULL;
2325                 channel_forwarded_auth_socket_dir = NULL;
2326                 return 0;
2327         }
2328         snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d",
2329                  channel_forwarded_auth_socket_dir, (int) getpid());
2330
2331         if (atexit(cleanup_socket) < 0) {
2332                 int saved = errno;
2333                 cleanup_socket();
2334                 packet_disconnect("socket: %.100s", strerror(saved));
2335         }
2336         /* Create the socket. */
2337         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2338         if (sock < 0)
2339                 packet_disconnect("socket: %.100s", strerror(errno));
2340
2341         /* Bind it to the name. */
2342         memset(&sunaddr, 0, sizeof(sunaddr));
2343         sunaddr.sun_family = AF_UNIX;
2344         strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name,
2345                 sizeof(sunaddr.sun_path));
2346
2347         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
2348                 packet_disconnect("bind: %.100s", strerror(errno));
2349
2350         /* Restore the privileged uid. */
2351         restore_uid();
2352
2353         /* Start listening on the socket. */
2354         if (listen(sock, 5) < 0)
2355                 packet_disconnect("listen: %.100s", strerror(errno));
2356
2357         /* Allocate a channel for the authentication agent socket. */
2358         newch = channel_new("auth socket",
2359             SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
2360             CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2361             0, xstrdup("auth socket"), 1);
2362
2363         strlcpy(channels[newch].path, channel_forwarded_auth_socket_name,
2364             sizeof(channels[newch].path));
2365         return 1;
2366 }
2367
2368 /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
2369
2370 void
2371 auth_input_open_request(int type, int plen, void *ctxt)
2372 {
2373         int remch, sock, newch;
2374         char *dummyname;
2375
2376         packet_integrity_check(plen, 4, type);
2377
2378         /* Read the remote channel number from the message. */
2379         remch = packet_get_int();
2380
2381         /*
2382          * Get a connection to the local authentication agent (this may again
2383          * get forwarded).
2384          */
2385         sock = ssh_get_authentication_socket();
2386
2387         /*
2388          * If we could not connect the agent, send an error message back to
2389          * the server. This should never happen unless the agent dies,
2390          * because authentication forwarding is only enabled if we have an
2391          * agent.
2392          */
2393         if (sock < 0) {
2394                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2395                 packet_put_int(remch);
2396                 packet_send();
2397                 return;
2398         }
2399         debug("Forwarding authentication connection.");
2400
2401         /*
2402          * Dummy host name.  This will be freed when the channel is freed; it
2403          * will still be valid in the packet_put_string below since the
2404          * channel cannot yet be freed at that point.
2405          */
2406         dummyname = xstrdup("authentication agent connection");
2407
2408         newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
2409         channels[newch].remote_id = remch;
2410
2411         /* Send a confirmation to the remote host. */
2412         packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2413         packet_put_int(remch);
2414         packet_put_int(newch);
2415         packet_send();
2416 }
2417
2418 void
2419 channel_start_open(int id)
2420 {
2421         Channel *c = channel_lookup(id);
2422         if (c == NULL) {
2423                 log("channel_open: %d: bad id", id);
2424                 return;
2425         }
2426         debug("send channel open %d", id);
2427         packet_start(SSH2_MSG_CHANNEL_OPEN);
2428         packet_put_cstring(c->ctype);
2429         packet_put_int(c->self);
2430         packet_put_int(c->local_window);
2431         packet_put_int(c->local_maxpacket);
2432 }
2433 void
2434 channel_open(int id)
2435 {
2436         /* XXX REMOVE ME */
2437         channel_start_open(id);
2438         packet_send();
2439 }
2440 void
2441 channel_request(int id, char *service, int wantconfirm)
2442 {
2443         channel_request_start(id, service, wantconfirm);
2444         packet_send();
2445         debug("channel request %d: %s", id, service) ;
2446 }
2447 void
2448 channel_request_start(int id, char *service, int wantconfirm)
2449 {
2450         Channel *c = channel_lookup(id);
2451         if (c == NULL) {
2452                 log("channel_request: %d: bad id", id);
2453                 return;
2454         }
2455         packet_start(SSH2_MSG_CHANNEL_REQUEST);
2456         packet_put_int(c->remote_id);
2457         packet_put_cstring(service);
2458         packet_put_char(wantconfirm);
2459 }
2460 void
2461 channel_register_callback(int id, int mtype, channel_callback_fn *fn, void *arg)
2462 {
2463         Channel *c = channel_lookup(id);
2464         if (c == NULL) {
2465                 log("channel_register_callback: %d: bad id", id);
2466                 return;
2467         }
2468         c->cb_event = mtype;
2469         c->cb_fn = fn;
2470         c->cb_arg = arg;
2471 }
2472 void
2473 channel_register_cleanup(int id, channel_callback_fn *fn)
2474 {
2475         Channel *c = channel_lookup(id);
2476         if (c == NULL) {
2477                 log("channel_register_cleanup: %d: bad id", id);
2478                 return;
2479         }
2480         c->dettach_user = fn;
2481 }
2482 void
2483 channel_cancel_cleanup(int id)
2484 {
2485         Channel *c = channel_lookup(id);
2486         if (c == NULL) {
2487                 log("channel_cancel_cleanup: %d: bad id", id);
2488                 return;
2489         }
2490         c->dettach_user = NULL;
2491 }
2492 void
2493 channel_register_filter(int id, channel_filter_fn *fn)
2494 {
2495         Channel *c = channel_lookup(id);
2496         if (c == NULL) {
2497                 log("channel_register_filter: %d: bad id", id);
2498                 return;
2499         }
2500         c->input_filter = fn;
2501 }
2502
2503 void
2504 channel_set_fds(int id, int rfd, int wfd, int efd,
2505     int extusage, int nonblock)
2506 {
2507         Channel *c = channel_lookup(id);
2508         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
2509                 fatal("channel_activate for non-larval channel %d.", id);
2510         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
2511         c->type = SSH_CHANNEL_OPEN;
2512         /* XXX window size? */
2513         c->local_window = c->local_window_max = c->local_maxpacket * 2;
2514         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
2515         packet_put_int(c->remote_id);
2516         packet_put_int(c->local_window);
2517         packet_send();
2518 }