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 1.90 2001/02/08 21:58:28 markus Exp $");
  44
  45 #include <openssl/rsa.h>
  46 #include <openssl/dsa.h>
  47
  48 #include "ssh.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "packet.h"
  52 #include "xmalloc.h"
  53 #include "buffer.h"
  54 #include "uidswap.h"
  55 #include "log.h"
  56 #include "misc.h"
  57 #include "channels.h"
  58 #include "nchan.h"
  59 #include "compat.h"
  60 #include "canohost.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 = 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 /* AF_UNSPEC or AF_INET or AF_INET6 */
 134 extern int IPv4or6;
 135
 136 /* Sets specific protocol options. */
 137
 138 void
 139 channel_set_options(int hostname_in_open)
 140 {
 141         have_hostname_in_open = hostname_in_open;
 142 }
 143
 144 /*
 145  * Permits opening to any host/port in SSH_MSG_PORT_OPEN.  This is usually
 146  * called by the server, because the user could connect to any port anyway,
 147  * and the server has no way to know but to trust the client anyway.
 148  */
 149
 150 void
 151 channel_permit_all_opens()
 152 {
 153         all_opens_permitted = 1;
 154 }
 155
 156 /* lookup channel by id */
 157
 158 Channel *
 159 channel_lookup(int id)
 160 {
 161         Channel *c;
 162         if (id < 0 || id > channels_alloc) {
 163                 log("channel_lookup: %d: bad id", id);
 164                 return NULL;
 165         }
 166         c = &channels[id];
 167         if (c->type == SSH_CHANNEL_FREE) {
 168                 log("channel_lookup: %d: bad id: channel free", id);
 169                 return NULL;
 170         }
 171         return c;
 172 }
 173
 174 /*
 175  * Register filedescriptors for a channel, used when allocating a channel or
 176  * when the channel consumer/producer is ready, e.g. shell exec'd
 177  */
 178
 179 void
 180 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 181     int extusage, int nonblock)
 182 {
 183         /* Update the maximum file descriptor value. */
 184         channel_max_fd = MAX(channel_max_fd, rfd);
 185         channel_max_fd = MAX(channel_max_fd, wfd);
 186         channel_max_fd = MAX(channel_max_fd, efd);
 187
 188         /* XXX set close-on-exec -markus */
 189
 190         c->rfd = rfd;
 191         c->wfd = wfd;
 192         c->sock = (rfd == wfd) ? rfd : -1;
 193         c->efd = efd;
 194         c->extended_usage = extusage;
 195
 196         /* enable nonblocking mode */
 197         if (nonblock) {
 198                 if (rfd != -1)
 199                         set_nonblock(rfd);
 200                 if (wfd != -1)
 201                         set_nonblock(wfd);
 202                 if (efd != -1)
 203                         set_nonblock(efd);
 204         }
 205 }
 206
 207 /*
 208  * Allocate a new channel object and set its type and socket. This will cause
 209  * remote_name to be freed.
 210  */
 211
 212 int
 213 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 214     int window, int maxpack, int extusage, char *remote_name, int nonblock)
 215 {
 216         int i, found;
 217         Channel *c;
 218
 219         /* Do initial allocation if this is the first call. */
 220         if (channels_alloc == 0) {
 221                 chan_init();
 222                 channels_alloc = 10;
 223                 channels = xmalloc(channels_alloc * sizeof(Channel));
 224                 for (i = 0; i < channels_alloc; i++)
 225                         channels[i].type = SSH_CHANNEL_FREE;
 226                 /*
 227                  * Kludge: arrange a call to channel_stop_listening if we
 228                  * terminate with fatal().
 229                  */
 230                 fatal_add_cleanup((void (*) (void *)) channel_stop_listening, NULL);
 231         }
 232         /* Try to find a free slot where to put the new channel. */
 233         for (found = -1, i = 0; i < channels_alloc; i++)
 234                 if (channels[i].type == SSH_CHANNEL_FREE) {
 235                         /* Found a free slot. */
 236                         found = i;
 237                         break;
 238                 }
 239         if (found == -1) {
 240                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 241                 found = channels_alloc;
 242                 channels_alloc += 10;
 243                 debug2("channel: expanding %d", channels_alloc);
 244                 channels = xrealloc(channels, channels_alloc * sizeof(Channel));
 245                 for (i = found; i < channels_alloc; i++)
 246                         channels[i].type = SSH_CHANNEL_FREE;
 247         }
 248         /* Initialize and return new channel number. */
 249         c = &channels[found];
 250         buffer_init(&c->input);
 251         buffer_init(&c->output);
 252         buffer_init(&c->extended);
 253         chan_init_iostates(c);
 254         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 255         c->self = found;
 256         c->type = type;
 257         c->ctype = ctype;
 258         c->local_window = window;
 259         c->local_window_max = window;
 260         c->local_consumed = 0;
 261         c->local_maxpacket = maxpack;
 262         c->remote_id = -1;
 263         c->remote_name = remote_name;
 264         c->remote_window = 0;
 265         c->remote_maxpacket = 0;
 266         c->cb_fn = NULL;
 267         c->cb_arg = NULL;
 268         c->cb_event = 0;
 269         c->dettach_user = NULL;
 270         c->input_filter = NULL;
 271         debug("channel %d: new [%s]", found, remote_name);
 272         return found;
 273 }
 274 /* old interface XXX */
 275 int
 276 channel_allocate(int type, int sock, char *remote_name)
 277 {
 278         return channel_new("", type, sock, sock, -1, 0, 0, 0, remote_name, 1);
 279 }
 280
 281
 282 /* Close all channel fd/socket. */
 283
 284 void
 285 channel_close_fds(Channel *c)
 286 {
 287         if (c->sock != -1) {
 288                 close(c->sock);
 289                 c->sock = -1;
 290         }
 291         if (c->rfd != -1) {
 292                 close(c->rfd);
 293                 c->rfd = -1;
 294         }
 295         if (c->wfd != -1) {
 296                 close(c->wfd);
 297                 c->wfd = -1;
 298         }
 299         if (c->efd != -1) {
 300                 close(c->efd);
 301                 c->efd = -1;
 302         }
 303 }
 304
 305 /* Free the channel and close its fd/socket. */
 306
 307 void
 308 channel_free(int id)
 309 {
 310         Channel *c = channel_lookup(id);
 311         char *s = channel_open_message();
 312
 313         if (c == NULL)
 314                 packet_disconnect("channel free: bad local channel %d", id);
 315         debug("channel_free: channel %d: status: %s", id, s);
 316         xfree(s);
 317
 318         if (c->dettach_user != NULL) {
 319                 debug("channel_free: channel %d: dettaching channel user", id);
 320                 c->dettach_user(c->self, NULL);
 321         }
 322         if (c->sock != -1)
 323                 shutdown(c->sock, SHUT_RDWR);
 324         channel_close_fds(c);
 325         buffer_free(&c->input);
 326         buffer_free(&c->output);
 327         buffer_free(&c->extended);
 328         c->type = SSH_CHANNEL_FREE;
 329         if (c->remote_name) {
 330                 xfree(c->remote_name);
 331                 c->remote_name = NULL;
 332         }
 333 }
 334
 335 /*
 336  * 'channel_pre*' are called just before select() to add any bits relevant to
 337  * channels in the select bitmasks.
 338  */
 339 /*
 340  * 'channel_post*': perform any appropriate operations for channels which
 341  * have events pending.
 342  */
 343 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 344 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 345 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 346
 347 void
 348 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 349 {
 350         FD_SET(c->sock, readset);
 351 }
 352
 353 void
 354 channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 355 {
 356         debug3("channel %d: waiting for connection", c->self);
 357         FD_SET(c->sock, writeset);
 358 }
 359
 360 void
 361 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 362 {
 363         if (buffer_len(&c->input) < packet_get_maxsize())
 364                 FD_SET(c->sock, readset);
 365         if (buffer_len(&c->output) > 0)
 366                 FD_SET(c->sock, writeset);
 367 }
 368
 369 void
 370 channel_pre_open_15(Channel *c, fd_set * readset, fd_set * writeset)
 371 {
 372         /* test whether sockets are 'alive' for read/write */
 373         if (c->istate == CHAN_INPUT_OPEN)
 374                 if (buffer_len(&c->input) < packet_get_maxsize())
 375                         FD_SET(c->sock, readset);
 376         if (c->ostate == CHAN_OUTPUT_OPEN ||
 377             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 378                 if (buffer_len(&c->output) > 0) {
 379                         FD_SET(c->sock, writeset);
 380                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 381                         chan_obuf_empty(c);
 382                 }
 383         }
 384 }
 385
 386 void
 387 channel_pre_open_20(Channel *c, fd_set * readset, fd_set * writeset)
 388 {
 389         if (c->istate == CHAN_INPUT_OPEN &&
 390             c->remote_window > 0 &&
 391             buffer_len(&c->input) < c->remote_window)
 392                 FD_SET(c->rfd, readset);
 393         if (c->ostate == CHAN_OUTPUT_OPEN ||
 394             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 395                 if (buffer_len(&c->output) > 0) {
 396                         FD_SET(c->wfd, writeset);
 397                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 398                         chan_obuf_empty(c);
 399                 }
 400         }
 401         /** XXX check close conditions, too */
 402         if (c->efd != -1) {
 403                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 404                     buffer_len(&c->extended) > 0)
 405                         FD_SET(c->efd, writeset);
 406                 else if (c->extended_usage == CHAN_EXTENDED_READ &&
 407                     buffer_len(&c->extended) < c->remote_window)
 408                         FD_SET(c->efd, readset);
 409         }
 410 }
 411
 412 void
 413 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 414 {
 415         if (buffer_len(&c->input) == 0) {
 416                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 417                 packet_put_int(c->remote_id);
 418                 packet_send();
 419                 c->type = SSH_CHANNEL_CLOSED;
 420                 debug("Closing channel %d after input drain.", c->self);
 421         }
 422 }
 423
 424 void
 425 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 426 {
 427         if (buffer_len(&c->output) == 0)
 428                 channel_free(c->self);
 429         else
 430                 FD_SET(c->sock, writeset);
 431 }
 432
 433 /*
 434  * This is a special state for X11 authentication spoofing.  An opened X11
 435  * connection (when authentication spoofing is being done) remains in this
 436  * state until the first packet has been completely read.  The authentication
 437  * data in that packet is then substituted by the real data if it matches the
 438  * fake data, and the channel is put into normal mode.
 439  * XXX All this happens at the client side.
 440  */
 441 int
 442 x11_open_helper(Channel *c)
 443 {
 444         u_char *ucp;
 445         u_int proto_len, data_len;
 446
 447         /* Check if the fixed size part of the packet is in buffer. */
 448         if (buffer_len(&c->output) < 12)
 449                 return 0;
 450
 451         /* Parse the lengths of variable-length fields. */
 452         ucp = (u_char *) buffer_ptr(&c->output);
 453         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 454                 proto_len = 256 * ucp[6] + ucp[7];
 455                 data_len = 256 * ucp[8] + ucp[9];
 456         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 457                 proto_len = ucp[6] + 256 * ucp[7];
 458                 data_len = ucp[8] + 256 * ucp[9];
 459         } else {
 460                 debug("Initial X11 packet contains bad byte order byte: 0x%x",
 461                       ucp[0]);
 462                 return -1;
 463         }
 464
 465         /* Check if the whole packet is in buffer. */
 466         if (buffer_len(&c->output) <
 467             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 468                 return 0;
 469
 470         /* Check if authentication protocol matches. */
 471         if (proto_len != strlen(x11_saved_proto) ||
 472             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 473                 debug("X11 connection uses different authentication protocol.");
 474                 return -1;
 475         }
 476         /* Check if authentication data matches our fake data. */
 477         if (data_len != x11_fake_data_len ||
 478             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 479                 x11_fake_data, x11_fake_data_len) != 0) {
 480                 debug("X11 auth data does not match fake data.");
 481                 return -1;
 482         }
 483         /* Check fake data length */
 484         if (x11_fake_data_len != x11_saved_data_len) {
 485                 error("X11 fake_data_len %d != saved_data_len %d",
 486                     x11_fake_data_len, x11_saved_data_len);
 487                 return -1;
 488         }
 489         /*
 490          * Received authentication protocol and data match
 491          * our fake data. Substitute the fake data with real
 492          * data.
 493          */
 494         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 495             x11_saved_data, x11_saved_data_len);
 496         return 1;
 497 }
 498
 499 void
 500 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 501 {
 502         int ret = x11_open_helper(c);
 503         if (ret == 1) {
 504                 /* Start normal processing for the channel. */
 505                 c->type = SSH_CHANNEL_OPEN;
 506                 channel_pre_open_13(c, readset, writeset);
 507         } else if (ret == -1) {
 508                 /*
 509                  * We have received an X11 connection that has bad
 510                  * authentication information.
 511                  */
 512                 log("X11 connection rejected because of wrong authentication.\r\n");
 513                 buffer_clear(&c->input);
 514                 buffer_clear(&c->output);
 515                 close(c->sock);
 516                 c->sock = -1;
 517                 c->type = SSH_CHANNEL_CLOSED;
 518                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 519                 packet_put_int(c->remote_id);
 520                 packet_send();
 521         }
 522 }
 523
 524 void
 525 channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
 526 {
 527         int ret = x11_open_helper(c);
 528         if (ret == 1) {
 529                 c->type = SSH_CHANNEL_OPEN;
 530                 if (compat20)
 531                         channel_pre_open_20(c, readset, writeset);
 532                 else
 533                         channel_pre_open_15(c, readset, writeset);
 534         } else if (ret == -1) {
 535                 debug("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 536                 chan_read_failed(c);    /** force close? */
 537                 chan_write_failed(c);
 538                 debug("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 539         }
 540 }
 541
 542 /* This is our fake X11 server socket. */
 543 void
 544 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
 545 {
 546         struct sockaddr addr;
 547         int newsock, newch;
 548         socklen_t addrlen;
 549         char buf[16384], *remote_ipaddr;
 550         int remote_port;
 551
 552         if (FD_ISSET(c->sock, readset)) {
 553                 debug("X11 connection requested.");
 554                 addrlen = sizeof(addr);
 555                 newsock = accept(c->sock, &addr, &addrlen);
 556                 if (newsock < 0) {
 557                         error("accept: %.100s", strerror(errno));
 558                         return;
 559                 }
 560                 remote_ipaddr = get_peer_ipaddr(newsock);
 561                 remote_port = get_peer_port(newsock);
 562                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
 563                     remote_ipaddr, remote_port);
 564
 565                 newch = channel_new("x11",
 566                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
 567                     c->local_window_max, c->local_maxpacket,
 568                     0, xstrdup(buf), 1);
 569                 if (compat20) {
 570                         packet_start(SSH2_MSG_CHANNEL_OPEN);
 571                         packet_put_cstring("x11");
 572                         packet_put_int(newch);
 573                         packet_put_int(c->local_window_max);
 574                         packet_put_int(c->local_maxpacket);
 575                         /* originator ipaddr and port */
 576                         packet_put_cstring(remote_ipaddr);
 577                         if (datafellows & SSH_BUG_X11FWD) {
 578                                 debug("ssh2 x11 bug compat mode");
 579                         } else {
 580                                 packet_put_int(remote_port);
 581                         }
 582                         packet_send();
 583                 } else {
 584                         packet_start(SSH_SMSG_X11_OPEN);
 585                         packet_put_int(newch);
 586                         if (have_hostname_in_open)
 587                                 packet_put_string(buf, strlen(buf));
 588                         packet_send();
 589                 }
 590                 xfree(remote_ipaddr);
 591         }
 592 }
 593
 594 /*
 595  * This socket is listening for connections to a forwarded TCP/IP port.
 596  */
 597 void
 598 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
 599 {
 600         struct sockaddr addr;
 601         int newsock, newch;
 602         socklen_t addrlen;
 603         char buf[1024], *remote_ipaddr, *rtype;
 604         int remote_port;
 605
 606         rtype = (c->type == SSH_CHANNEL_RPORT_LISTENER) ?
 607             "forwarded-tcpip" : "direct-tcpip";
 608
 609         if (FD_ISSET(c->sock, readset)) {
 610                 debug("Connection to port %d forwarding "
 611                     "to %.100s port %d requested.",
 612                     c->listening_port, c->path, c->host_port);
 613                 addrlen = sizeof(addr);
 614                 newsock = accept(c->sock, &addr, &addrlen);
 615                 if (newsock < 0) {
 616                         error("accept: %.100s", strerror(errno));
 617                         return;
 618                 }
 619                 remote_ipaddr = get_peer_ipaddr(newsock);
 620                 remote_port = get_peer_port(newsock);
 621                 snprintf(buf, sizeof buf,
 622                     "listen port %d for %.100s port %d, "
 623                     "connect from %.200s port %d",
 624                     c->listening_port, c->path, c->host_port,
 625                     remote_ipaddr, remote_port);
 626
 627                 newch = channel_new(rtype,
 628                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
 629                     c->local_window_max, c->local_maxpacket,
 630                     0, xstrdup(buf), 1);
 631                 if (compat20) {
 632                         packet_start(SSH2_MSG_CHANNEL_OPEN);
 633                         packet_put_cstring(rtype);
 634                         packet_put_int(newch);
 635                         packet_put_int(c->local_window_max);
 636                         packet_put_int(c->local_maxpacket);
 637                         if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
 638                                 /* listen address, port */
 639                                 packet_put_string(c->path, strlen(c->path));
 640                                 packet_put_int(c->listening_port);
 641                         } else {
 642                                 /* target host, port */
 643                                 packet_put_string(c->path, strlen(c->path));
 644                                 packet_put_int(c->host_port);
 645                         }
 646                         /* originator host and port */
 647                         packet_put_cstring(remote_ipaddr);
 648                         packet_put_int(remote_port);
 649                         packet_send();
 650                 } else {
 651                         packet_start(SSH_MSG_PORT_OPEN);
 652                         packet_put_int(newch);
 653                         packet_put_string(c->path, strlen(c->path));
 654                         packet_put_int(c->host_port);
 655                         if (have_hostname_in_open) {
 656                                 packet_put_string(buf, strlen(buf));
 657                         }
 658                         packet_send();
 659                 }
 660                 xfree(remote_ipaddr);
 661         }
 662 }
 663
 664 /*
 665  * This is the authentication agent socket listening for connections from
 666  * clients.
 667  */
 668 void
 669 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
 670 {
 671         struct sockaddr addr;
 672         int newsock, newch;
 673         socklen_t addrlen;
 674
 675         if (FD_ISSET(c->sock, readset)) {
 676                 addrlen = sizeof(addr);
 677                 newsock = accept(c->sock, &addr, &addrlen);
 678                 if (newsock < 0) {
 679                         error("accept from auth socket: %.100s", strerror(errno));
 680                         return;
 681                 }
 682                 newch = channel_new("accepted auth socket",
 683                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
 684                     c->local_window_max, c->local_maxpacket,
 685                     0, xstrdup("accepted auth socket"), 1);
 686                 if (compat20) {
 687                         packet_start(SSH2_MSG_CHANNEL_OPEN);
 688                         packet_put_cstring("auth-agent@openssh.com");
 689                         packet_put_int(newch);
 690                         packet_put_int(c->local_window_max);
 691                         packet_put_int(c->local_maxpacket);
 692                 } else {
 693                         packet_start(SSH_SMSG_AGENT_OPEN);
 694                         packet_put_int(newch);
 695                 }
 696                 packet_send();
 697         }
 698 }
 699
 700 void
 701 channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
 702 {
 703         if (FD_ISSET(c->sock, writeset)) {
 704                 int err = 0;
 705                 int sz = sizeof(err);
 706                 c->type = SSH_CHANNEL_OPEN;
 707                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, (char *)&err, &sz) < 0) {
 708                         debug("getsockopt SO_ERROR failed");
 709                 } else {
 710                         if (err == 0) {
 711                                 debug("channel %d: connected)", c->self);
 712                         } else {
 713                                 debug("channel %d: not connected: %s",
 714                                     c->self, strerror(err));
 715                                 chan_read_failed(c);
 716                                 chan_write_failed(c);
 717                         }
 718                 }
 719         }
 720 }
 721
 722 int
 723 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
 724 {
 725         char buf[16*1024];
 726         int len;
 727
 728         if (c->rfd != -1 &&
 729             FD_ISSET(c->rfd, readset)) {
 730                 len = read(c->rfd, buf, sizeof(buf));
 731                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
 732                         return 1;
 733                 if (len <= 0) {
 734                         debug("channel %d: read<=0 rfd %d len %d",
 735                             c->self, c->rfd, len);
 736                         if (compat13) {
 737                                 buffer_consume(&c->output, buffer_len(&c->output));
 738                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
 739                                 debug("Channel %d status set to input draining.", c->self);
 740                         } else {
 741                                 chan_read_failed(c);
 742                         }
 743                         return -1;
 744                 }
 745                 if(c->input_filter != NULL) {
 746                         if (c->input_filter(c, buf, len) == -1) {
 747                                 debug("filter stops channel %d", c->self);
 748                                 chan_read_failed(c);
 749                         }
 750                 } else {
 751                         buffer_append(&c->input, buf, len);
 752                 }
 753         }
 754         return 1;
 755 }
 756 int
 757 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
 758 {
 759         int len;
 760
 761         /* Send buffered output data to the socket. */
 762         if (c->wfd != -1 &&
 763             FD_ISSET(c->wfd, writeset) &&
 764             buffer_len(&c->output) > 0) {
 765                 len = write(c->wfd, buffer_ptr(&c->output),
 766                     buffer_len(&c->output));
 767                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
 768                         return 1;
 769                 if (len <= 0) {
 770                         if (compat13) {
 771                                 buffer_consume(&c->output, buffer_len(&c->output));
 772                                 debug("Channel %d status set to input draining.", c->self);
 773                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
 774                         } else {
 775                                 chan_write_failed(c);
 776                         }
 777                         return -1;
 778                 }
 779                 buffer_consume(&c->output, len);
 780                 if (compat20 && len > 0) {
 781                         c->local_consumed += len;
 782                 }
 783         }
 784         return 1;
 785 }
 786 int
 787 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
 788 {
 789         char buf[16*1024];
 790         int len;
 791
 792 /** XXX handle drain efd, too */
 793         if (c->efd != -1) {
 794                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 795                     FD_ISSET(c->efd, writeset) &&
 796                     buffer_len(&c->extended) > 0) {
 797                         len = write(c->efd, buffer_ptr(&c->extended),
 798                             buffer_len(&c->extended));
 799                         debug2("channel %d: written %d to efd %d",
 800                             c->self, len, c->efd);
 801                         if (len > 0) {
 802                                 buffer_consume(&c->extended, len);
 803                                 c->local_consumed += len;
 804                         }
 805                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
 806                     FD_ISSET(c->efd, readset)) {
 807                         len = read(c->efd, buf, sizeof(buf));
 808                         debug2("channel %d: read %d from efd %d",
 809                              c->self, len, c->efd);
 810                         if (len == 0) {
 811                                 debug("channel %d: closing efd %d",
 812                                     c->self, c->efd);
 813                                 close(c->efd);
 814                                 c->efd = -1;
 815                         } else if (len > 0)
 816                                 buffer_append(&c->extended, buf, len);
 817                 }
 818         }
 819         return 1;
 820 }
 821 int
 822 channel_check_window(Channel *c, fd_set * readset, fd_set * writeset)
 823 {
 824         if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
 825             c->local_window < c->local_window_max/2 &&
 826             c->local_consumed > 0) {
 827                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 828                 packet_put_int(c->remote_id);
 829                 packet_put_int(c->local_consumed);
 830                 packet_send();
 831                 debug2("channel %d: window %d sent adjust %d",
 832                     c->self, c->local_window,
 833                     c->local_consumed);
 834                 c->local_window += c->local_consumed;
 835                 c->local_consumed = 0;
 836         }
 837         return 1;
 838 }
 839
 840 void
 841 channel_post_open_1(Channel *c, fd_set * readset, fd_set * writeset)
 842 {
 843         channel_handle_rfd(c, readset, writeset);
 844         channel_handle_wfd(c, readset, writeset);
 845 }
 846
 847 void
 848 channel_post_open_2(Channel *c, fd_set * readset, fd_set * writeset)
 849 {
 850         channel_handle_rfd(c, readset, writeset);
 851         channel_handle_wfd(c, readset, writeset);
 852         channel_handle_efd(c, readset, writeset);
 853         channel_check_window(c, readset, writeset);
 854 }
 855
 856 void
 857 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
 858 {
 859         int len;
 860         /* Send buffered output data to the socket. */
 861         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
 862                 len = write(c->sock, buffer_ptr(&c->output),
 863                             buffer_len(&c->output));
 864                 if (len <= 0)
 865                         buffer_consume(&c->output, buffer_len(&c->output));
 866                 else
 867                         buffer_consume(&c->output, len);
 868         }
 869 }
 870
 871 void
 872 channel_handler_init_20(void)
 873 {
 874         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_20;
 875         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
 876         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 877         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
 878         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
 879         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
 880         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
 881
 882         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_2;
 883         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 884         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
 885         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
 886         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
 887         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
 888 }
 889
 890 void
 891 channel_handler_init_13(void)
 892 {
 893         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
 894         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
 895         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
 896         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 897         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
 898         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
 899         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
 900         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
 901
 902         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_1;
 903         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
 904         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 905         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
 906         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
 907         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
 908 }
 909
 910 void
 911 channel_handler_init_15(void)
 912 {
 913         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_15;
 914         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
 915         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
 916         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 917         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
 918         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
 919
 920         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
 921         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 922         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
 923         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_1;
 924         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
 925 }
 926
 927 void
 928 channel_handler_init(void)
 929 {
 930         int i;
 931         for(i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
 932                 channel_pre[i] = NULL;
 933                 channel_post[i] = NULL;
 934         }
 935         if (compat20)
 936                 channel_handler_init_20();
 937         else if (compat13)
 938                 channel_handler_init_13();
 939         else
 940                 channel_handler_init_15();
 941 }
 942
 943 void
 944 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
 945 {
 946         static int did_init = 0;
 947         int i;
 948         Channel *c;
 949
 950         if (!did_init) {
 951                 channel_handler_init();
 952                 did_init = 1;
 953         }
 954         for (i = 0; i < channels_alloc; i++) {
 955                 c = &channels[i];
 956                 if (c->type == SSH_CHANNEL_FREE)
 957                         continue;
 958                 if (ftab[c->type] == NULL)
 959                         continue;
 960                 (*ftab[c->type])(c, readset, writeset);
 961                 chan_delete_if_full_closed(c);
 962         }
 963 }
 964
 965 void
 966 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp)
 967 {
 968         int n;
 969         u_int sz;
 970
 971         n = MAX(*maxfdp, channel_max_fd);
 972
 973         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 974         if (*readsetp == NULL || n > *maxfdp) {
 975                 if (*readsetp)
 976                         xfree(*readsetp);
 977                 if (*writesetp)
 978                         xfree(*writesetp);
 979                 *readsetp = xmalloc(sz);
 980                 *writesetp = xmalloc(sz);
 981                 *maxfdp = n;
 982         }
 983         memset(*readsetp, 0, sz);
 984         memset(*writesetp, 0, sz);
 985
 986         channel_handler(channel_pre, *readsetp, *writesetp);
 987 }
 988
 989 void
 990 channel_after_select(fd_set * readset, fd_set * writeset)
 991 {
 992         channel_handler(channel_post, readset, writeset);
 993 }
 994
 995 /* If there is data to send to the connection, enqueue some of it now. */
 996
 997 void
 998 channel_output_poll()
 999 {
1000         int len, i;
1001         Channel *c;
1002
1003         for (i = 0; i < channels_alloc; i++) {
1004                 c = &channels[i];
1005
1006                 /* We are only interested in channels that can have buffered incoming data. */
1007                 if (compat13) {
1008                         if (c->type != SSH_CHANNEL_OPEN &&
1009                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1010                                 continue;
1011                 } else {
1012                         if (c->type != SSH_CHANNEL_OPEN)
1013                                 continue;
1014                         if (c->istate != CHAN_INPUT_OPEN &&
1015                             c->istate != CHAN_INPUT_WAIT_DRAIN)
1016                                 continue;
1017                 }
1018                 if (compat20 &&
1019                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1020                         debug("channel: %d: no data after CLOSE", c->self);
1021                         continue;
1022                 }
1023
1024                 /* Get the amount of buffered data for this channel. */
1025                 len = buffer_len(&c->input);
1026                 if (len > 0) {
1027                         /* Send some data for the other side over the secure connection. */
1028                         if (compat20) {
1029                                 if (len > c->remote_window)
1030                                         len = c->remote_window;
1031                                 if (len > c->remote_maxpacket)
1032                                         len = c->remote_maxpacket;
1033                         } else {
1034                                 if (packet_is_interactive()) {
1035                                         if (len > 1024)
1036                                                 len = 512;
1037                                 } else {
1038                                         /* Keep the packets at reasonable size. */
1039                                         if (len > packet_get_maxsize()/2)
1040                                                 len = packet_get_maxsize()/2;
1041                                 }
1042                         }
1043                         if (len > 0) {
1044                                 packet_start(compat20 ?
1045                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1046                                 packet_put_int(c->remote_id);
1047                                 packet_put_string(buffer_ptr(&c->input), len);
1048                                 packet_send();
1049                                 buffer_consume(&c->input, len);
1050                                 c->remote_window -= len;
1051                         }
1052                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1053                         if (compat13)
1054                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1055                         /*
1056                          * input-buffer is empty and read-socket shutdown:
1057                          * tell peer, that we will not send more data: send IEOF
1058                          */
1059                         chan_ibuf_empty(c);
1060                 }
1061                 /* Send extended data, i.e. stderr */
1062                 if (compat20 &&
1063                     c->remote_window > 0 &&
1064                     (len = buffer_len(&c->extended)) > 0 &&
1065                     c->extended_usage == CHAN_EXTENDED_READ) {
1066                         if (len > c->remote_window)
1067                                 len = c->remote_window;
1068                         if (len > c->remote_maxpacket)
1069                                 len = c->remote_maxpacket;
1070                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1071                         packet_put_int(c->remote_id);
1072                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1073                         packet_put_string(buffer_ptr(&c->extended), len);
1074                         packet_send();
1075                         buffer_consume(&c->extended, len);
1076                         c->remote_window -= len;
1077                 }
1078         }
1079 }
1080
1081 /*
1082  * This is called when a packet of type CHANNEL_DATA has just been received.
1083  * The message type has already been consumed, but channel number and data is
1084  * still there.
1085  */
1086
1087 void
1088 channel_input_data(int type, int plen, void *ctxt)
1089 {
1090         int id;
1091         char *data;
1092         u_int data_len;
1093         Channel *c;
1094
1095         /* Get the channel number and verify it. */
1096         id = packet_get_int();
1097         c = channel_lookup(id);
1098         if (c == NULL)
1099                 packet_disconnect("Received data for nonexistent channel %d.", id);
1100
1101         /* Ignore any data for non-open channels (might happen on close) */
1102         if (c->type != SSH_CHANNEL_OPEN &&
1103             c->type != SSH_CHANNEL_X11_OPEN)
1104                 return;
1105
1106         /* same for protocol 1.5 if output end is no longer open */
1107         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN)
1108                 return;
1109
1110         /* Get the data. */
1111         data = packet_get_string(&data_len);
1112         packet_done();
1113
1114         if (compat20){
1115                 if (data_len > c->local_maxpacket) {
1116                         log("channel %d: rcvd big packet %d, maxpack %d",
1117                             c->self, data_len, c->local_maxpacket);
1118                 }
1119                 if (data_len > c->local_window) {
1120                         log("channel %d: rcvd too much data %d, win %d",
1121                             c->self, data_len, c->local_window);
1122                         xfree(data);
1123                         return;
1124                 }
1125                 c->local_window -= data_len;
1126         }else{
1127                 packet_integrity_check(plen, 4 + 4 + data_len, type);
1128         }
1129         buffer_append(&c->output, data, data_len);
1130         xfree(data);
1131 }
1132 void
1133 channel_input_extended_data(int type, int plen, void *ctxt)
1134 {
1135         int id;
1136         int tcode;
1137         char *data;
1138         u_int data_len;
1139         Channel *c;
1140
1141         /* Get the channel number and verify it. */
1142         id = packet_get_int();
1143         c = channel_lookup(id);
1144
1145         if (c == NULL)
1146                 packet_disconnect("Received extended_data for bad channel %d.", id);
1147         if (c->type != SSH_CHANNEL_OPEN) {
1148                 log("channel %d: ext data for non open", id);
1149                 return;
1150         }
1151         tcode = packet_get_int();
1152         if (c->efd == -1 ||
1153             c->extended_usage != CHAN_EXTENDED_WRITE ||
1154             tcode != SSH2_EXTENDED_DATA_STDERR) {
1155                 log("channel %d: bad ext data", c->self);
1156                 return;
1157         }
1158         data = packet_get_string(&data_len);
1159         packet_done();
1160         if (data_len > c->local_window) {
1161                 log("channel %d: rcvd too much extended_data %d, win %d",
1162                     c->self, data_len, c->local_window);
1163                 xfree(data);
1164                 return;
1165         }
1166         debug2("channel %d: rcvd ext data %d", c->self, data_len);
1167         c->local_window -= data_len;
1168         buffer_append(&c->extended, data, data_len);
1169         xfree(data);
1170 }
1171
1172
1173 /*
1174  * Returns true if no channel has too much buffered data, and false if one or
1175  * more channel is overfull.
1176  */
1177
1178 int
1179 channel_not_very_much_buffered_data()
1180 {
1181         u_int i;
1182         Channel *c;
1183
1184         for (i = 0; i < channels_alloc; i++) {
1185                 c = &channels[i];
1186                 if (c->type == SSH_CHANNEL_OPEN) {
1187                         if (!compat20 && buffer_len(&c->input) > packet_get_maxsize()) {
1188                                 debug("channel %d: big input buffer %d",
1189                                     c->self, buffer_len(&c->input));
1190                                 return 0;
1191                         }
1192                         if (buffer_len(&c->output) > packet_get_maxsize()) {
1193                                 debug("channel %d: big output buffer %d",
1194                                     c->self, buffer_len(&c->output));
1195                                 return 0;
1196                         }
1197                 }
1198         }
1199         return 1;
1200 }
1201
1202 void
1203 channel_input_ieof(int type, int plen, void *ctxt)
1204 {
1205         int id;
1206         Channel *c;
1207
1208         packet_integrity_check(plen, 4, type);
1209
1210         id = packet_get_int();
1211         c = channel_lookup(id);
1212         if (c == NULL)
1213                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
1214         chan_rcvd_ieof(c);
1215 }
1216
1217 void
1218 channel_input_close(int type, int plen, void *ctxt)
1219 {
1220         int id;
1221         Channel *c;
1222
1223         packet_integrity_check(plen, 4, type);
1224
1225         id = packet_get_int();
1226         c = channel_lookup(id);
1227         if (c == NULL)
1228                 packet_disconnect("Received close for nonexistent channel %d.", id);
1229
1230         /*
1231          * Send a confirmation that we have closed the channel and no more
1232          * data is coming for it.
1233          */
1234         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
1235         packet_put_int(c->remote_id);
1236         packet_send();
1237
1238         /*
1239          * If the channel is in closed state, we have sent a close request,
1240          * and the other side will eventually respond with a confirmation.
1241          * Thus, we cannot free the channel here, because then there would be
1242          * no-one to receive the confirmation.  The channel gets freed when
1243          * the confirmation arrives.
1244          */
1245         if (c->type != SSH_CHANNEL_CLOSED) {
1246                 /*
1247                  * Not a closed channel - mark it as draining, which will
1248                  * cause it to be freed later.
1249                  */
1250                 buffer_consume(&c->input, buffer_len(&c->input));
1251                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
1252         }
1253 }
1254
1255 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
1256 void
1257 channel_input_oclose(int type, int plen, void *ctxt)
1258 {
1259         int id = packet_get_int();
1260         Channel *c = channel_lookup(id);
1261         packet_integrity_check(plen, 4, type);
1262         if (c == NULL)
1263                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
1264         chan_rcvd_oclose(c);
1265 }
1266
1267 void
1268 channel_input_close_confirmation(int type, int plen, void *ctxt)
1269 {
1270         int id = packet_get_int();
1271         Channel *c = channel_lookup(id);
1272
1273         packet_done();
1274         if (c == NULL)
1275                 packet_disconnect("Received close confirmation for "
1276                     "out-of-range channel %d.", id);
1277         if (c->type != SSH_CHANNEL_CLOSED)
1278                 packet_disconnect("Received close confirmation for "
1279                     "non-closed channel %d (type %d).", id, c->type);
1280         channel_free(c->self);
1281 }
1282
1283 void
1284 channel_input_open_confirmation(int type, int plen, void *ctxt)
1285 {
1286         int id, remote_id;
1287         Channel *c;
1288
1289         if (!compat20)
1290                 packet_integrity_check(plen, 4 + 4, type);
1291
1292         id = packet_get_int();
1293         c = channel_lookup(id);
1294
1295         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
1296                 packet_disconnect("Received open confirmation for "
1297                     "non-opening channel %d.", id);
1298         remote_id = packet_get_int();
1299         /* Record the remote channel number and mark that the channel is now open. */
1300         c->remote_id = remote_id;
1301         c->type = SSH_CHANNEL_OPEN;
1302
1303         if (compat20) {
1304                 c->remote_window = packet_get_int();
1305                 c->remote_maxpacket = packet_get_int();
1306                 packet_done();
1307                 if (c->cb_fn != NULL && c->cb_event == type) {
1308                         debug2("callback start");
1309                         c->cb_fn(c->self, c->cb_arg);
1310                         debug2("callback done");
1311                 }
1312                 debug("channel %d: open confirm rwindow %d rmax %d", c->self,
1313                     c->remote_window, c->remote_maxpacket);
1314         }
1315 }
1316
1317 void
1318 channel_input_open_failure(int type, int plen, void *ctxt)
1319 {
1320         int id, reason;
1321         char *msg = NULL, *lang = NULL;
1322         Channel *c;
1323
1324         if (!compat20)
1325                 packet_integrity_check(plen, 4, type);
1326
1327         id = packet_get_int();
1328         c = channel_lookup(id);
1329
1330         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
1331                 packet_disconnect("Received open failure for "
1332                     "non-opening channel %d.", id);
1333         if (compat20) {
1334                 reason = packet_get_int();
1335                 if (packet_remaining() > 0) {
1336                         msg  = packet_get_string(NULL);
1337                         lang = packet_get_string(NULL);
1338                 }
1339                 packet_done();
1340                 log("channel_open_failure: %d: reason %d %s", id,
1341                     reason, msg ? msg : "<no additional info>");
1342                 if (msg != NULL)
1343                         xfree(msg);
1344                 if (lang != NULL)
1345                         xfree(lang);
1346         }
1347         /* Free the channel.  This will also close the socket. */
1348         channel_free(id);
1349 }
1350
1351 void
1352 channel_input_channel_request(int type, int plen, void *ctxt)
1353 {
1354         int id;
1355         Channel *c;
1356
1357         id = packet_get_int();
1358         c = channel_lookup(id);
1359
1360         if (c == NULL ||
1361             (c->type != SSH_CHANNEL_OPEN && c->type != SSH_CHANNEL_LARVAL))
1362                 packet_disconnect("Received request for "
1363                     "non-open channel %d.", id);
1364         if (c->cb_fn != NULL && c->cb_event == type) {
1365                 debug2("callback start");
1366                 c->cb_fn(c->self, c->cb_arg);
1367                 debug2("callback done");
1368         } else {
1369                 char *service = packet_get_string(NULL);
1370                 debug("channel: %d rcvd request for %s", c->self, service);
1371                 debug("cb_fn %p cb_event %d", c->cb_fn , c->cb_event);
1372                 xfree(service);
1373         }
1374 }
1375
1376 void
1377 channel_input_window_adjust(int type, int plen, void *ctxt)
1378 {
1379         Channel *c;
1380         int id, adjust;
1381
1382         if (!compat20)
1383                 return;
1384
1385         /* Get the channel number and verify it. */
1386         id = packet_get_int();
1387         c = channel_lookup(id);
1388
1389         if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
1390                 log("Received window adjust for "
1391                     "non-open channel %d.", id);
1392                 return;
1393         }
1394         adjust = packet_get_int();
1395         packet_done();
1396         debug2("channel %d: rcvd adjust %d", id, adjust);
1397         c->remote_window += adjust;
1398 }
1399
1400 /*
1401  * Stops listening for channels, and removes any unix domain sockets that we
1402  * might have.
1403  */
1404
1405 void
1406 channel_stop_listening()
1407 {
1408         int i;
1409         for (i = 0; i < channels_alloc; i++) {
1410                 switch (channels[i].type) {
1411                 case SSH_CHANNEL_AUTH_SOCKET:
1412                         close(channels[i].sock);
1413                         unlink(channels[i].path);
1414                         channel_free(i);
1415                         break;
1416                 case SSH_CHANNEL_PORT_LISTENER:
1417                 case SSH_CHANNEL_RPORT_LISTENER:
1418                 case SSH_CHANNEL_X11_LISTENER:
1419                         close(channels[i].sock);
1420                         channel_free(i);
1421                         break;
1422                 default:
1423                         break;
1424                 }
1425         }
1426 }
1427
1428 /*
1429  * Closes the sockets/fds of all channels.  This is used to close extra file
1430  * descriptors after a fork.
1431  */
1432
1433 void
1434 channel_close_all()
1435 {
1436         int i;
1437         for (i = 0; i < channels_alloc; i++)
1438                 if (channels[i].type != SSH_CHANNEL_FREE)
1439                         channel_close_fds(&channels[i]);
1440 }
1441
1442 /* Returns true if any channel is still open. */
1443
1444 int
1445 channel_still_open()
1446 {
1447         u_int i;
1448         for (i = 0; i < channels_alloc; i++)
1449                 switch (channels[i].type) {
1450                 case SSH_CHANNEL_FREE:
1451                 case SSH_CHANNEL_X11_LISTENER:
1452                 case SSH_CHANNEL_PORT_LISTENER:
1453                 case SSH_CHANNEL_RPORT_LISTENER:
1454                 case SSH_CHANNEL_CLOSED:
1455                 case SSH_CHANNEL_AUTH_SOCKET:
1456                 case SSH_CHANNEL_CONNECTING:    /* XXX ??? */
1457                         continue;
1458                 case SSH_CHANNEL_LARVAL:
1459                         if (!compat20)
1460                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
1461                         continue;
1462                 case SSH_CHANNEL_OPENING:
1463                 case SSH_CHANNEL_OPEN:
1464                 case SSH_CHANNEL_X11_OPEN:
1465                         return 1;
1466                 case SSH_CHANNEL_INPUT_DRAINING:
1467                 case SSH_CHANNEL_OUTPUT_DRAINING:
1468                         if (!compat13)
1469                                 fatal("cannot happen: OUT_DRAIN");
1470                         return 1;
1471                 default:
1472                         fatal("channel_still_open: bad channel type %d", channels[i].type);
1473                         /* NOTREACHED */
1474                 }
1475         return 0;
1476 }
1477
1478 /*
1479  * Returns a message describing the currently open forwarded connections,
1480  * suitable for sending to the client.  The message contains crlf pairs for
1481  * newlines.
1482  */
1483
1484 char *
1485 channel_open_message()
1486 {
1487         Buffer buffer;
1488         int i;
1489         char buf[512], *cp;
1490
1491         buffer_init(&buffer);
1492         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
1493         buffer_append(&buffer, buf, strlen(buf));
1494         for (i = 0; i < channels_alloc; i++) {
1495                 Channel *c = &channels[i];
1496                 switch (c->type) {
1497                 case SSH_CHANNEL_FREE:
1498                 case SSH_CHANNEL_X11_LISTENER:
1499                 case SSH_CHANNEL_PORT_LISTENER:
1500                 case SSH_CHANNEL_RPORT_LISTENER:
1501                 case SSH_CHANNEL_CLOSED:
1502                 case SSH_CHANNEL_AUTH_SOCKET:
1503                         continue;
1504                 case SSH_CHANNEL_LARVAL:
1505                 case SSH_CHANNEL_OPENING:
1506                 case SSH_CHANNEL_CONNECTING:
1507                 case SSH_CHANNEL_OPEN:
1508                 case SSH_CHANNEL_X11_OPEN:
1509                 case SSH_CHANNEL_INPUT_DRAINING:
1510                 case SSH_CHANNEL_OUTPUT_DRAINING:
1511                         snprintf(buf, sizeof buf, "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d)\r\n",
1512                             c->self, c->remote_name,
1513                             c->type, c->remote_id,
1514                             c->istate, buffer_len(&c->input),
1515                             c->ostate, buffer_len(&c->output),
1516                             c->rfd, c->wfd);
1517                         buffer_append(&buffer, buf, strlen(buf));
1518                         continue;
1519                 default:
1520                         fatal("channel_open_message: bad channel type %d", c->type);
1521                         /* NOTREACHED */
1522                 }
1523         }
1524         buffer_append(&buffer, "\0", 1);
1525         cp = xstrdup(buffer_ptr(&buffer));
1526         buffer_free(&buffer);
1527         return cp;
1528 }
1529
1530 /*
1531  * Initiate forwarding of connections to local port "port" through the secure
1532  * channel to host:port from remote side.
1533  */
1534 int
1535 channel_request_local_forwarding(u_short listen_port, const char *host_to_connect,
1536     u_short port_to_connect, int gateway_ports)
1537 {
1538         return channel_request_forwarding(
1539             NULL, listen_port,
1540             host_to_connect, port_to_connect,
1541             gateway_ports, /*remote_fwd*/ 0);
1542 }
1543
1544 /*
1545  * If 'remote_fwd' is true we have a '-R style' listener for protocol 2
1546  * (SSH_CHANNEL_RPORT_LISTENER).
1547  */
1548 int
1549 channel_request_forwarding(
1550     const char *listen_address, u_short listen_port,
1551     const char *host_to_connect, u_short port_to_connect,
1552     int gateway_ports, int remote_fwd)
1553 {
1554         int success, ch, sock, on = 1, ctype;
1555         struct addrinfo hints, *ai, *aitop;
1556         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1557         const char *host;
1558         struct linger linger;
1559
1560         success = 0;
1561
1562         if (remote_fwd) {
1563                 host = listen_address;
1564                 ctype = SSH_CHANNEL_RPORT_LISTENER;
1565         } else {
1566                 host = host_to_connect;
1567                 ctype  =SSH_CHANNEL_PORT_LISTENER;
1568         }
1569
1570         if (strlen(host) > sizeof(channels[0].path) - 1) {
1571                 error("Forward host name too long.");
1572                 return success;
1573         }
1574
1575         /* XXX listen_address is currently ignored */
1576         /*
1577          * getaddrinfo returns a loopback address if the hostname is
1578          * set to NULL and hints.ai_flags is not AI_PASSIVE
1579          */
1580         memset(&hints, 0, sizeof(hints));
1581         hints.ai_family = IPv4or6;
1582         hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
1583         hints.ai_socktype = SOCK_STREAM;
1584         snprintf(strport, sizeof strport, "%d", listen_port);
1585         if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
1586                 packet_disconnect("getaddrinfo: fatal error");
1587
1588         for (ai = aitop; ai; ai = ai->ai_next) {
1589                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1590                         continue;
1591                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
1592                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1593                         error("channel_request_forwarding: getnameinfo failed");
1594                         continue;
1595                 }
1596                 /* Create a port to listen for the host. */
1597                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1598                 if (sock < 0) {
1599                         /* this is no error since kernel may not support ipv6 */
1600                         verbose("socket: %.100s", strerror(errno));
1601                         continue;
1602                 }
1603                 /*
1604                  * Set socket options.  We would like the socket to disappear
1605                  * as soon as it has been closed for whatever reason.
1606                  */
1607                 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));
1608                 linger.l_onoff = 1;
1609                 linger.l_linger = 5;
1610                 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
1611                 debug("Local forwarding listening on %s port %s.", ntop, strport);
1612
1613                 /* Bind the socket to the address. */
1614                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1615                         /* address can be in use ipv6 address is already bound */
1616                         if (!ai->ai_next)
1617                                 error("bind: %.100s", strerror(errno));
1618                         else
1619                                 verbose("bind: %.100s", strerror(errno));
1620
1621                         close(sock);
1622                         continue;
1623                 }
1624                 /* Start listening for connections on the socket. */
1625                 if (listen(sock, 5) < 0) {
1626                         error("listen: %.100s", strerror(errno));
1627                         close(sock);
1628                         continue;
1629                 }
1630                 /* Allocate a channel number for the socket. */
1631                 ch = channel_new("port listener", ctype, sock, sock, -1,
1632                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1633                     0, xstrdup("port listener"), 1);
1634                 strlcpy(channels[ch].path, host, sizeof(channels[ch].path));
1635                 channels[ch].host_port = port_to_connect;
1636                 channels[ch].listening_port = listen_port;
1637                 success = 1;
1638         }
1639         if (success == 0)
1640                 error("channel_request_forwarding: cannot listen to port: %d",
1641                     listen_port);
1642         freeaddrinfo(aitop);
1643         return success;
1644 }
1645
1646 /*
1647  * Initiate forwarding of connections to port "port" on remote host through
1648  * the secure channel to host:port from local side.
1649  */
1650
1651 void
1652 channel_request_remote_forwarding(u_short listen_port,
1653     const char *host_to_connect, u_short port_to_connect)
1654 {
1655         int payload_len, type, success = 0;
1656
1657         /* Record locally that connection to this host/port is permitted. */
1658         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
1659                 fatal("channel_request_remote_forwarding: too many forwards");
1660
1661         /* Send the forward request to the remote side. */
1662         if (compat20) {
1663                 const char *address_to_bind = "0.0.0.0";
1664                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1665                 packet_put_cstring("tcpip-forward");
1666                 packet_put_char(0);                     /* boolean: want reply */
1667                 packet_put_cstring(address_to_bind);
1668                 packet_put_int(listen_port);
1669                 packet_send();
1670                 packet_write_wait();
1671                 /* Assume that server accepts the request */
1672                 success = 1;
1673         } else {
1674                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
1675                 packet_put_int(listen_port);
1676                 packet_put_cstring(host_to_connect);
1677                 packet_put_int(port_to_connect);
1678                 packet_send();
1679                 packet_write_wait();
1680
1681                 /* Wait for response from the remote side. */
1682                 type = packet_read(&payload_len);
1683                 switch (type) {
1684                 case SSH_SMSG_SUCCESS:
1685                         success = 1;
1686                         break;
1687                 case SSH_SMSG_FAILURE:
1688                         log("Warning: Server denied remote port forwarding.");
1689                         break;
1690                 default:
1691                         /* Unknown packet */
1692                         packet_disconnect("Protocol error for port forward request:"
1693                             "received packet type %d.", type);
1694                 }
1695         }
1696         if (success) {
1697                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
1698                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
1699                 permitted_opens[num_permitted_opens].listen_port = listen_port;
1700                 num_permitted_opens++;
1701         }
1702 }
1703
1704 /*
1705  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
1706  * listening for the port, and sends back a success reply (or disconnect
1707  * message if there was an error).  This never returns if there was an error.
1708  */
1709
1710 void
1711 channel_input_port_forward_request(int is_root, int gateway_ports)
1712 {
1713         u_short port, host_port;
1714         char *hostname;
1715
1716         /* Get arguments from the packet. */
1717         port = packet_get_int();
1718         hostname = packet_get_string(NULL);
1719         host_port = packet_get_int();
1720
1721 #ifndef HAVE_CYGWIN
1722         /*
1723          * Check that an unprivileged user is not trying to forward a
1724          * privileged port.
1725          */
1726         if (port < IPPORT_RESERVED && !is_root)
1727                 packet_disconnect("Requested forwarding of port %d but user is not root.",
1728                                   port);
1729 #endif
1730         /* Initiate forwarding */
1731         channel_request_local_forwarding(port, hostname, host_port, gateway_ports);
1732
1733         /* Free the argument string. */
1734         xfree(hostname);
1735 }
1736
1737 /* XXX move to aux.c */
1738 int
1739 channel_connect_to(const char *host, u_short host_port)
1740 {
1741         struct addrinfo hints, *ai, *aitop;
1742         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1743         int gaierr;
1744         int sock = -1;
1745
1746         memset(&hints, 0, sizeof(hints));
1747         hints.ai_family = IPv4or6;
1748         hints.ai_socktype = SOCK_STREAM;
1749         snprintf(strport, sizeof strport, "%d", host_port);
1750         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
1751                 error("%.100s: unknown host (%s)", host, gai_strerror(gaierr));
1752                 return -1;
1753         }
1754         for (ai = aitop; ai; ai = ai->ai_next) {
1755                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1756                         continue;
1757                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
1758                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1759                         error("channel_connect_to: getnameinfo failed");
1760                         continue;
1761                 }
1762                 /* Create the socket. */
1763                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1764                 if (sock < 0) {
1765                         error("socket: %.100s", strerror(errno));
1766                         continue;
1767                 }
1768                 if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0)
1769                         fatal("connect_to: F_SETFL: %s", strerror(errno));
1770                 /* Connect to the host/port. */
1771                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
1772                     errno != EINPROGRESS) {
1773                         error("connect %.100s port %s: %.100s", ntop, strport,
1774                             strerror(errno));
1775                         close(sock);
1776                         continue;       /* fail -- try next */
1777                 }
1778                 break; /* success */
1779
1780         }
1781         freeaddrinfo(aitop);
1782         if (!ai) {
1783                 error("connect %.100s port %d: failed.", host, host_port);
1784                 return -1;
1785         }
1786         /* success */
1787         return sock;
1788 }
1789 int
1790 channel_connect_by_listen_adress(u_short listen_port)
1791 {
1792         int i;
1793         for (i = 0; i < num_permitted_opens; i++)
1794                 if (permitted_opens[i].listen_port == listen_port)
1795                         return channel_connect_to(
1796                             permitted_opens[i].host_to_connect,
1797                             permitted_opens[i].port_to_connect);
1798         error("WARNING: Server requests forwarding for unknown listen_port %d",
1799             listen_port);
1800         return -1;
1801 }
1802
1803 /*
1804  * This is called after receiving PORT_OPEN message.  This attempts to
1805  * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
1806  * or CHANNEL_OPEN_FAILURE.
1807  */
1808
1809 void
1810 channel_input_port_open(int type, int plen, void *ctxt)
1811 {
1812         u_short host_port;
1813         char *host, *originator_string;
1814         int remote_channel, sock = -1, newch, i, denied;
1815         u_int host_len, originator_len;
1816
1817         /* Get remote channel number. */
1818         remote_channel = packet_get_int();
1819
1820         /* Get host name to connect to. */
1821         host = packet_get_string(&host_len);
1822
1823         /* Get port to connect to. */
1824         host_port = packet_get_int();
1825
1826         /* Get remote originator name. */
1827         if (have_hostname_in_open) {
1828                 originator_string = packet_get_string(&originator_len);
1829                 originator_len += 4;    /* size of packet_int */
1830         } else {
1831                 originator_string = xstrdup("unknown (remote did not supply name)");
1832                 originator_len = 0;     /* no originator supplied */
1833         }
1834
1835         packet_integrity_check(plen,
1836             4 + 4 + host_len + 4 + originator_len, SSH_MSG_PORT_OPEN);
1837
1838         /* Check if opening that port is permitted. */
1839         denied = 0;
1840         if (!all_opens_permitted) {
1841                 /* Go trough all permitted ports. */
1842                 for (i = 0; i < num_permitted_opens; i++)
1843                         if (permitted_opens[i].port_to_connect == host_port &&
1844                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
1845                                 break;
1846
1847                 /* Check if we found the requested port among those permitted. */
1848                 if (i >= num_permitted_opens) {
1849                         /* The port is not permitted. */
1850                         log("Received request to connect to %.100s:%d, but the request was denied.",
1851                             host, host_port);
1852                         denied = 1;
1853                 }
1854         }
1855         sock = denied ? -1 : channel_connect_to(host, host_port);
1856         if (sock > 0) {
1857                 /* Allocate a channel for this connection. */
1858                 newch = channel_allocate(SSH_CHANNEL_CONNECTING,
1859                     sock, originator_string);
1860 /*XXX delay answer? */
1861                 channels[newch].remote_id = remote_channel;
1862
1863                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1864                 packet_put_int(remote_channel);
1865                 packet_put_int(newch);
1866                 packet_send();
1867         } else {
1868                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1869                 packet_put_int(remote_channel);
1870                 packet_send();
1871         }
1872         xfree(host);
1873 }
1874
1875 /*
1876  * Creates an internet domain socket for listening for X11 connections.
1877  * Returns a suitable value for the DISPLAY variable, or NULL if an error
1878  * occurs.
1879  */
1880
1881 #define NUM_SOCKS       10
1882
1883 char *
1884 x11_create_display_inet(int screen_number, int x11_display_offset)
1885 {
1886         int display_number, sock;
1887         u_short port;
1888         struct addrinfo hints, *ai, *aitop;
1889         char strport[NI_MAXSERV];
1890         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
1891         char display[512];
1892         char hostname[MAXHOSTNAMELEN];
1893
1894         for (display_number = x11_display_offset;
1895              display_number < MAX_DISPLAYS;
1896              display_number++) {
1897                 port = 6000 + display_number;
1898                 memset(&hints, 0, sizeof(hints));
1899                 hints.ai_family = IPv4or6;
1900                 hints.ai_flags = AI_PASSIVE;            /* XXX loopback only ? */
1901                 hints.ai_socktype = SOCK_STREAM;
1902                 snprintf(strport, sizeof strport, "%d", port);
1903                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
1904                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
1905                         return NULL;
1906                 }
1907                 for (ai = aitop; ai; ai = ai->ai_next) {
1908                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1909                                 continue;
1910                         sock = socket(ai->ai_family, SOCK_STREAM, 0);
1911                         if (sock < 0) {
1912                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
1913                                         error("socket: %.100s", strerror(errno));
1914                                         return NULL;
1915                                 } else {
1916                                         debug("x11_create_display_inet: Socket family %d not supported",
1917                                                  ai->ai_family);
1918                                         continue;
1919                                 }
1920                         }
1921                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1922                                 debug("bind port %d: %.100s", port, strerror(errno));
1923                                 shutdown(sock, SHUT_RDWR);
1924                                 close(sock);
1925
1926                                 if (ai->ai_next)
1927                                         continue;
1928
1929                                 for (n = 0; n < num_socks; n++) {
1930                                         shutdown(socks[n], SHUT_RDWR);
1931                                         close(socks[n]);
1932                                 }
1933                                 num_socks = 0;
1934                                 break;
1935                         }
1936                         socks[num_socks++] = sock;
1937 #ifndef DONT_TRY_OTHER_AF
1938                         if (num_socks == NUM_SOCKS)
1939                                 break;
1940 #else
1941                         break;
1942 #endif
1943                 }
1944                 freeaddrinfo(aitop);
1945                 if (num_socks > 0)
1946                         break;
1947         }
1948         if (display_number >= MAX_DISPLAYS) {
1949                 error("Failed to allocate internet-domain X11 display socket.");
1950                 return NULL;
1951         }
1952         /* Start listening for connections on the socket. */
1953         for (n = 0; n < num_socks; n++) {
1954                 sock = socks[n];
1955                 if (listen(sock, 5) < 0) {
1956                         error("listen: %.100s", strerror(errno));
1957                         shutdown(sock, SHUT_RDWR);
1958                         close(sock);
1959                         return NULL;
1960                 }
1961         }
1962
1963         /* Set up a suitable value for the DISPLAY variable. */
1964         if (gethostname(hostname, sizeof(hostname)) < 0)
1965                 fatal("gethostname: %.100s", strerror(errno));
1966
1967 #ifdef IPADDR_IN_DISPLAY
1968         /*
1969          * HPUX detects the local hostname in the DISPLAY variable and tries
1970          * to set up a shared memory connection to the server, which it
1971          * incorrectly supposes to be local.
1972          *
1973          * The workaround - as used in later $$H and other programs - is
1974          * is to set display to the host's IP address.
1975          */
1976         {
1977                 struct hostent *he;
1978                 struct in_addr my_addr;
1979
1980                 he = gethostbyname(hostname);
1981                 if (he == NULL) {
1982                         error("[X11-broken-fwd-hostname-workaround] Could not get "
1983                                 "IP address for hostname %s.", hostname);
1984
1985                         packet_send_debug("[X11-broken-fwd-hostname-workaround]"
1986                                 "Could not get IP address for hostname %s.", hostname);
1987
1988                         shutdown(sock, SHUT_RDWR);
1989                         close(sock);
1990
1991                         return NULL;
1992                 }
1993
1994                 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
1995
1996                 /* Set DISPLAY to <ip address>:screen.display */
1997                 snprintf(display, sizeof(display), "%.50s:%d.%d", inet_ntoa(my_addr),
1998                          display_number, screen_number);
1999         }
2000 #else /* IPADDR_IN_DISPLAY */
2001         /* Just set DISPLAY to hostname:screen.display */
2002         snprintf(display, sizeof display, "%.400s:%d.%d", hostname,
2003                  display_number, screen_number);
2004 #endif /* IPADDR_IN_DISPLAY */
2005
2006         /* Allocate a channel for each socket. */
2007         for (n = 0; n < num_socks; n++) {
2008                 sock = socks[n];
2009                 (void) channel_new("x11 listener",
2010                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2011                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2012                     0, xstrdup("X11 inet listener"), 1);
2013         }
2014
2015         /* Return a suitable value for the DISPLAY environment variable. */
2016         return xstrdup(display);
2017 }
2018
2019 #ifndef X_UNIX_PATH
2020 #define X_UNIX_PATH "/tmp/.X11-unix/X"
2021 #endif
2022
2023 static
2024 int
2025 connect_local_xsocket(u_int dnr)
2026 {
2027         static const char *const x_sockets[] = {
2028                 X_UNIX_PATH "%u",
2029                 "/var/X/.X11-unix/X" "%u",
2030                 "/usr/spool/sockets/X11/" "%u",
2031                 NULL
2032         };
2033         int sock;
2034         struct sockaddr_un addr;
2035         const char *const * path;
2036
2037         for (path = x_sockets; *path; ++path) {
2038                 sock = socket(AF_UNIX, SOCK_STREAM, 0);
2039                 if (sock < 0)
2040                         error("socket: %.100s", strerror(errno));
2041                 memset(&addr, 0, sizeof(addr));
2042                 addr.sun_family = AF_UNIX;
2043                 snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr);
2044                 if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
2045                         return sock;
2046                 close(sock);
2047         }
2048         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2049         return -1;
2050 }
2051
2052 int
2053 x11_connect_display(void)
2054 {
2055         int display_number, sock = 0;
2056         const char *display;
2057         char buf[1024], *cp;
2058         struct addrinfo hints, *ai, *aitop;
2059         char strport[NI_MAXSERV];
2060         int gaierr;
2061
2062         /* Try to open a socket for the local X server. */
2063         display = getenv("DISPLAY");
2064         if (!display) {
2065                 error("DISPLAY not set.");
2066                 return -1;
2067         }
2068         /*
2069          * Now we decode the value of the DISPLAY variable and make a
2070          * connection to the real X server.
2071          */
2072
2073         /*
2074          * Check if it is a unix domain socket.  Unix domain displays are in
2075          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2076          */
2077         if (strncmp(display, "unix:", 5) == 0 ||
2078             display[0] == ':') {
2079                 /* Connect to the unix domain socket. */
2080                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
2081                         error("Could not parse display number from DISPLAY: %.100s",
2082                               display);
2083                         return -1;
2084                 }
2085                 /* Create a socket. */
2086                 sock = connect_local_xsocket(display_number);
2087                 if (sock < 0)
2088                         return -1;
2089
2090                 /* OK, we now have a connection to the display. */
2091                 return sock;
2092         }
2093         /*
2094          * Connect to an inet socket.  The DISPLAY value is supposedly
2095          * hostname:d[.s], where hostname may also be numeric IP address.
2096          */
2097         strncpy(buf, display, sizeof(buf));
2098         buf[sizeof(buf) - 1] = 0;
2099         cp = strchr(buf, ':');
2100         if (!cp) {
2101                 error("Could not find ':' in DISPLAY: %.100s", display);
2102                 return -1;
2103         }
2104         *cp = 0;
2105         /* buf now contains the host name.  But first we parse the display number. */
2106         if (sscanf(cp + 1, "%d", &display_number) != 1) {
2107                 error("Could not parse display number from DISPLAY: %.100s",
2108                       display);
2109                 return -1;
2110         }
2111
2112         /* Look up the host address */
2113         memset(&hints, 0, sizeof(hints));
2114         hints.ai_family = IPv4or6;
2115         hints.ai_socktype = SOCK_STREAM;
2116         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
2117         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2118                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2119                 return -1;
2120         }
2121         for (ai = aitop; ai; ai = ai->ai_next) {
2122                 /* Create a socket. */
2123                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
2124                 if (sock < 0) {
2125                         debug("socket: %.100s", strerror(errno));
2126                         continue;
2127                 }
2128                 /* Connect it to the display. */
2129                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2130                         debug("connect %.100s port %d: %.100s", buf,
2131                             6000 + display_number, strerror(errno));
2132                         close(sock);
2133                         continue;
2134                 }
2135                 /* Success */
2136                 break;
2137         }
2138         freeaddrinfo(aitop);
2139         if (!ai) {
2140                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
2141                     strerror(errno));
2142                 return -1;
2143         }
2144         return sock;
2145 }
2146
2147 /*
2148  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
2149  * the remote channel number.  We should do whatever we want, and respond
2150  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
2151  */
2152
2153 void
2154 x11_input_open(int type, int plen, void *ctxt)
2155 {
2156         int remote_channel, sock = 0, newch;
2157         char *remote_host;
2158         u_int remote_len;
2159
2160         /* Get remote channel number. */
2161         remote_channel = packet_get_int();
2162
2163         /* Get remote originator name. */
2164         if (have_hostname_in_open) {
2165                 remote_host = packet_get_string(&remote_len);
2166                 remote_len += 4;
2167         } else {
2168                 remote_host = xstrdup("unknown (remote did not supply name)");
2169                 remote_len = 0;
2170         }
2171
2172         debug("Received X11 open request.");
2173         packet_integrity_check(plen, 4 + remote_len, SSH_SMSG_X11_OPEN);
2174
2175         /* Obtain a connection to the real X display. */
2176         sock = x11_connect_display();
2177         if (sock == -1) {
2178                 /* Send refusal to the remote host. */
2179                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2180                 packet_put_int(remote_channel);
2181                 packet_send();
2182         } else {
2183                 /* Allocate a channel for this connection. */
2184                 newch = channel_allocate(
2185                      (x11_saved_proto == NULL) ?
2186                      SSH_CHANNEL_OPEN : SSH_CHANNEL_X11_OPEN,
2187                      sock, remote_host);
2188                 channels[newch].remote_id = remote_channel;
2189
2190                 /* Send a confirmation to the remote host. */
2191                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2192                 packet_put_int(remote_channel);
2193                 packet_put_int(newch);
2194                 packet_send();
2195         }
2196 }
2197
2198 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
2199 void
2200 deny_input_open(int type, int plen, void *ctxt)
2201 {
2202         int rchan = packet_get_int();
2203         switch(type){
2204         case SSH_SMSG_AGENT_OPEN:
2205                 error("Warning: ssh server tried agent forwarding.");
2206                 break;
2207         case SSH_SMSG_X11_OPEN:
2208                 error("Warning: ssh server tried X11 forwarding.");
2209                 break;
2210         default:
2211                 error("deny_input_open: type %d plen %d", type, plen);
2212                 break;
2213         }
2214         error("Warning: this is probably a break in attempt by a malicious server.");
2215         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2216         packet_put_int(rchan);
2217         packet_send();
2218 }
2219
2220 /*
2221  * Requests forwarding of X11 connections, generates fake authentication
2222  * data, and enables authentication spoofing.
2223  */
2224
2225 void
2226 x11_request_forwarding_with_spoofing(int client_session_id,
2227     const char *proto, const char *data)
2228 {
2229         u_int data_len = (u_int) strlen(data) / 2;
2230         u_int i, value, len;
2231         char *new_data;
2232         int screen_number;
2233         const char *cp;
2234         u_int32_t rand = 0;
2235
2236         cp = getenv("DISPLAY");
2237         if (cp)
2238                 cp = strchr(cp, ':');
2239         if (cp)
2240                 cp = strchr(cp, '.');
2241         if (cp)
2242                 screen_number = atoi(cp + 1);
2243         else
2244                 screen_number = 0;
2245
2246         /* Save protocol name. */
2247         x11_saved_proto = xstrdup(proto);
2248
2249         /*
2250          * Extract real authentication data and generate fake data of the
2251          * same length.
2252          */
2253         x11_saved_data = xmalloc(data_len);
2254         x11_fake_data = xmalloc(data_len);
2255         for (i = 0; i < data_len; i++) {
2256                 if (sscanf(data + 2 * i, "%2x", &value) != 1)
2257                         fatal("x11_request_forwarding: bad authentication data: %.100s", data);
2258                 if (i % 4 == 0)
2259                         rand = arc4random();
2260                 x11_saved_data[i] = value;
2261                 x11_fake_data[i] = rand & 0xff;
2262                 rand >>= 8;
2263         }
2264         x11_saved_data_len = data_len;
2265         x11_fake_data_len = data_len;
2266
2267         /* Convert the fake data into hex. */
2268         len = 2 * data_len + 1;
2269         new_data = xmalloc(len);
2270         for (i = 0; i < data_len; i++)
2271                 snprintf(new_data + 2 * i, len - 2 * i,
2272                     "%02x", (u_char) x11_fake_data[i]);
2273
2274         /* Send the request packet. */
2275         if (compat20) {
2276                 channel_request_start(client_session_id, "x11-req", 0);
2277                 packet_put_char(0);     /* XXX bool single connection */
2278         } else {
2279                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
2280         }
2281         packet_put_cstring(proto);
2282         packet_put_cstring(new_data);
2283         packet_put_int(screen_number);
2284         packet_send();
2285         packet_write_wait();
2286         xfree(new_data);
2287 }
2288
2289 /* Sends a message to the server to request authentication fd forwarding. */
2290
2291 void
2292 auth_request_forwarding()
2293 {
2294         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
2295         packet_send();
2296         packet_write_wait();
2297 }
2298
2299 /*
2300  * Returns the name of the forwarded authentication socket.  Returns NULL if
2301  * there is no forwarded authentication socket.  The returned value points to
2302  * a static buffer.
2303  */
2304
2305 char *
2306 auth_get_socket_name()
2307 {
2308         return channel_forwarded_auth_socket_name;
2309 }
2310
2311 /* removes the agent forwarding socket */
2312
2313 void
2314 cleanup_socket(void)
2315 {
2316         unlink(channel_forwarded_auth_socket_name);
2317         rmdir(channel_forwarded_auth_socket_dir);
2318 }
2319
2320 /*
2321  * This is called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
2322  * This starts forwarding authentication requests.
2323  */
2324
2325 int
2326 auth_input_request_forwarding(struct passwd * pw)
2327 {
2328         int sock, newch;
2329         struct sockaddr_un sunaddr;
2330
2331         if (auth_get_socket_name() != NULL)
2332                 fatal("Protocol error: authentication forwarding requested twice.");
2333
2334         /* Temporarily drop privileged uid for mkdir/bind. */
2335         temporarily_use_uid(pw->pw_uid);
2336
2337         /* Allocate a buffer for the socket name, and format the name. */
2338         channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
2339         channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME);
2340         strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME);
2341
2342         /* Create private directory for socket */
2343         if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) {
2344                 packet_send_debug("Agent forwarding disabled: mkdtemp() failed: %.100s",
2345                     strerror(errno));
2346                 restore_uid();
2347                 xfree(channel_forwarded_auth_socket_name);
2348                 xfree(channel_forwarded_auth_socket_dir);
2349                 channel_forwarded_auth_socket_name = NULL;
2350                 channel_forwarded_auth_socket_dir = NULL;
2351                 return 0;
2352         }
2353         snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d",
2354                  channel_forwarded_auth_socket_dir, (int) getpid());
2355
2356         if (atexit(cleanup_socket) < 0) {
2357                 int saved = errno;
2358                 cleanup_socket();
2359                 packet_disconnect("socket: %.100s", strerror(saved));
2360         }
2361         /* Create the socket. */
2362         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2363         if (sock < 0)
2364                 packet_disconnect("socket: %.100s", strerror(errno));
2365
2366         /* Bind it to the name. */
2367         memset(&sunaddr, 0, sizeof(sunaddr));
2368         sunaddr.sun_family = AF_UNIX;
2369         strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name,
2370                 sizeof(sunaddr.sun_path));
2371
2372         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
2373                 packet_disconnect("bind: %.100s", strerror(errno));
2374
2375         /* Restore the privileged uid. */
2376         restore_uid();
2377
2378         /* Start listening on the socket. */
2379         if (listen(sock, 5) < 0)
2380                 packet_disconnect("listen: %.100s", strerror(errno));
2381
2382         /* Allocate a channel for the authentication agent socket. */
2383         newch = channel_new("auth socket",
2384             SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
2385             CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2386             0, xstrdup("auth socket"), 1);
2387
2388         strlcpy(channels[newch].path, channel_forwarded_auth_socket_name,
2389             sizeof(channels[newch].path));
2390         return 1;
2391 }
2392
2393 /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
2394
2395 void
2396 auth_input_open_request(int type, int plen, void *ctxt)
2397 {
2398         int remch, sock, newch;
2399         char *dummyname;
2400
2401         packet_integrity_check(plen, 4, type);
2402
2403         /* Read the remote channel number from the message. */
2404         remch = packet_get_int();
2405
2406         /*
2407          * Get a connection to the local authentication agent (this may again
2408          * get forwarded).
2409          */
2410         sock = ssh_get_authentication_socket();
2411
2412         /*
2413          * If we could not connect the agent, send an error message back to
2414          * the server. This should never happen unless the agent dies,
2415          * because authentication forwarding is only enabled if we have an
2416          * agent.
2417          */
2418         if (sock < 0) {
2419                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2420                 packet_put_int(remch);
2421                 packet_send();
2422                 return;
2423         }
2424         debug("Forwarding authentication connection.");
2425
2426         /*
2427          * Dummy host name.  This will be freed when the channel is freed; it
2428          * will still be valid in the packet_put_string below since the
2429          * channel cannot yet be freed at that point.
2430          */
2431         dummyname = xstrdup("authentication agent connection");
2432
2433         newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
2434         channels[newch].remote_id = remch;
2435
2436         /* Send a confirmation to the remote host. */
2437         packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2438         packet_put_int(remch);
2439         packet_put_int(newch);
2440         packet_send();
2441 }
2442
2443 void
2444 channel_start_open(int id)
2445 {
2446         Channel *c = channel_lookup(id);
2447         if (c == NULL) {
2448                 log("channel_open: %d: bad id", id);
2449                 return;
2450         }
2451         debug("send channel open %d", id);
2452         packet_start(SSH2_MSG_CHANNEL_OPEN);
2453         packet_put_cstring(c->ctype);
2454         packet_put_int(c->self);
2455         packet_put_int(c->local_window);
2456         packet_put_int(c->local_maxpacket);
2457 }
2458 void
2459 channel_open(int id)
2460 {
2461         /* XXX REMOVE ME */
2462         channel_start_open(id);
2463         packet_send();
2464 }
2465 void
2466 channel_request(int id, char *service, int wantconfirm)
2467 {
2468         channel_request_start(id, service, wantconfirm);
2469         packet_send();
2470         debug("channel request %d: %s", id, service) ;
2471 }
2472 void
2473 channel_request_start(int id, char *service, int wantconfirm)
2474 {
2475         Channel *c = channel_lookup(id);
2476         if (c == NULL) {
2477                 log("channel_request: %d: bad id", id);
2478                 return;
2479         }
2480         packet_start(SSH2_MSG_CHANNEL_REQUEST);
2481         packet_put_int(c->remote_id);
2482         packet_put_cstring(service);
2483         packet_put_char(wantconfirm);
2484 }
2485 void
2486 channel_register_callback(int id, int mtype, channel_callback_fn *fn, void *arg)
2487 {
2488         Channel *c = channel_lookup(id);
2489         if (c == NULL) {
2490                 log("channel_register_callback: %d: bad id", id);
2491                 return;
2492         }
2493         c->cb_event = mtype;
2494         c->cb_fn = fn;
2495         c->cb_arg = arg;
2496 }
2497 void
2498 channel_register_cleanup(int id, channel_callback_fn *fn)
2499 {
2500         Channel *c = channel_lookup(id);
2501         if (c == NULL) {
2502                 log("channel_register_cleanup: %d: bad id", id);
2503                 return;
2504         }
2505         c->dettach_user = fn;
2506 }
2507 void
2508 channel_cancel_cleanup(int id)
2509 {
2510         Channel *c = channel_lookup(id);
2511         if (c == NULL) {
2512                 log("channel_cancel_cleanup: %d: bad id", id);
2513                 return;
2514         }
2515         c->dettach_user = NULL;
2516 }
2517 void
2518 channel_register_filter(int id, channel_filter_fn *fn)
2519 {
2520         Channel *c = channel_lookup(id);
2521         if (c == NULL) {
2522                 log("channel_register_filter: %d: bad id", id);
2523                 return;
2524         }
2525         c->input_filter = fn;
2526 }
2527
2528 void
2529 channel_set_fds(int id, int rfd, int wfd, int efd,
2530     int extusage, int nonblock)
2531 {
2532         Channel *c = channel_lookup(id);
2533         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
2534                 fatal("channel_activate for non-larval channel %d.", id);
2535         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
2536         c->type = SSH_CHANNEL_OPEN;
2537         /* XXX window size? */
2538         c->local_window = c->local_window_max = c->local_maxpacket * 2;
2539         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
2540         packet_put_int(c->remote_id);
2541         packet_put_int(c->local_window);
2542         packet_send();
2543 }