channels.c

   1 /*
   2  *
   3  * channels.c
   4  *
   5  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   6  *
   7  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   8  *                    All rights reserved
   9  *
  10  * Created: Fri Mar 24 16:35:24 1995 ylo
  11  *
  12  * This file contains functions for generic socket connection forwarding.
  13  * There is also code for initiating connection forwarding for X11 connections,
  14  * arbitrary tcp/ip connections, and the authentication agent connection.
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  */
  18
  19 #include "includes.h"
  20 RCSID("$Id$");
  21
  22 #include "ssh.h"
  23 #include "packet.h"
  24 #include "xmalloc.h"
  25 #include "buffer.h"
  26 #include "authfd.h"
  27 #include "uidswap.h"
  28 #include "readconf.h"
  29 #include "servconf.h"
  30
  31 #include "channels.h"
  32 #include "nchan.h"
  33 #include "compat.h"
  34
  35 #include "ssh2.h"
  36
  37 /* Maximum number of fake X11 displays to try. */
  38 #define MAX_DISPLAYS  1000
  39
  40 /* Max len of agent socket */
  41 #define MAX_SOCKET_NAME 100
  42
  43 /* default buffer for tcp-fwd-channel */
  44 #define CHAN_WINDOW_DEFAULT      (8*1024)
  45 #define CHAN_PACKET_DEFAULT      (CHAN_WINDOW_DEFAULT/2)
  46
  47 /*
  48  * Pointer to an array containing all allocated channels.  The array is
  49  * dynamically extended as needed.
  50  */
  51 static Channel *channels = NULL;
  52
  53 /*
  54  * Size of the channel array.  All slots of the array must always be
  55  * initialized (at least the type field); unused slots are marked with type
  56  * SSH_CHANNEL_FREE.
  57  */
  58 static int channels_alloc = 0;
  59
  60 /*
  61  * Maximum file descriptor value used in any of the channels.  This is
  62  * updated in channel_allocate.
  63  */
  64 static int channel_max_fd_value = 0;
  65
  66 /* Name and directory of socket for authentication agent forwarding. */
  67 static char *channel_forwarded_auth_socket_name = NULL;
  68 static char *channel_forwarded_auth_socket_dir = NULL;
  69
  70 /* Saved X11 authentication protocol name. */
  71 char *x11_saved_proto = NULL;
  72
  73 /* Saved X11 authentication data.  This is the real data. */
  74 char *x11_saved_data = NULL;
  75 unsigned int x11_saved_data_len = 0;
  76
  77 /*
  78  * Fake X11 authentication data.  This is what the server will be sending us;
  79  * we should replace any occurrences of this by the real data.
  80  */
  81 char *x11_fake_data = NULL;
  82 unsigned int x11_fake_data_len;
  83
  84 /*
  85  * Data structure for storing which hosts are permitted for forward requests.
  86  * The local sides of any remote forwards are stored in this array to prevent
  87  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  88  * network (which might be behind a firewall).
  89  */
  90 typedef struct {
  91         char *host_to_connect;          /* Connect to 'host'. */
  92         u_short port_to_connect;        /* Connect to 'port'. */
  93         u_short listen_port;            /* Remote side should listen port number. */
  94 } ForwardPermission;
  95
  96 /* List of all permitted host/port pairs to connect. */
  97 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
  98 /* Number of permitted host/port pairs in the array. */
  99 static int num_permitted_opens = 0;
 100 /*
 101  * If this is true, all opens are permitted.  This is the case on the server
 102  * on which we have to trust the client anyway, and the user could do
 103  * anything after logging in anyway.
 104  */
 105 static int all_opens_permitted = 0;
 106
 107 /* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */
 108 static int have_hostname_in_open = 0;
 109
 110 /* Sets specific protocol options. */
 111
 112 void
 113 channel_set_options(int hostname_in_open)
 114 {
 115         have_hostname_in_open = hostname_in_open;
 116 }
 117
 118 /*
 119  * Permits opening to any host/port in SSH_MSG_PORT_OPEN.  This is usually
 120  * called by the server, because the user could connect to any port anyway,
 121  * and the server has no way to know but to trust the client anyway.
 122  */
 123
 124 void
 125 channel_permit_all_opens()
 126 {
 127         all_opens_permitted = 1;
 128 }
 129
 130 /* lookup channel by id */
 131
 132 Channel *
 133 channel_lookup(int id)
 134 {
 135         Channel *c;
 136         if (id < 0 && id > channels_alloc) {
 137                 log("channel_lookup: %d: bad id", id);
 138                 return NULL;
 139         }
 140         c = &channels[id];
 141         if (c->type == SSH_CHANNEL_FREE) {
 142                 log("channel_lookup: %d: bad id: channel free", id);
 143                 return NULL;
 144         }
 145         return c;
 146 }
 147
 148 /*
 149  * Allocate a new channel object and set its type and socket. This will cause
 150  * remote_name to be freed.
 151  */
 152
 153 int
 154 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 155     int window, int maxpack, int extended_usage, char *remote_name)
 156 {
 157         int i, found;
 158         Channel *c;
 159
 160         /* Update the maximum file descriptor value. */
 161         if (rfd > channel_max_fd_value)
 162                 channel_max_fd_value = rfd;
 163         if (wfd > channel_max_fd_value)
 164                 channel_max_fd_value = wfd;
 165         if (efd > channel_max_fd_value)
 166                 channel_max_fd_value = efd;
 167         /* XXX set close-on-exec -markus */
 168
 169         /* Do initial allocation if this is the first call. */
 170         if (channels_alloc == 0) {
 171                 chan_init();
 172                 channels_alloc = 10;
 173                 channels = xmalloc(channels_alloc * sizeof(Channel));
 174                 for (i = 0; i < channels_alloc; i++)
 175                         channels[i].type = SSH_CHANNEL_FREE;
 176                 /*
 177                  * Kludge: arrange a call to channel_stop_listening if we
 178                  * terminate with fatal().
 179                  */
 180                 fatal_add_cleanup((void (*) (void *)) channel_stop_listening, NULL);
 181         }
 182         /* Try to find a free slot where to put the new channel. */
 183         for (found = -1, i = 0; i < channels_alloc; i++)
 184                 if (channels[i].type == SSH_CHANNEL_FREE) {
 185                         /* Found a free slot. */
 186                         found = i;
 187                         break;
 188                 }
 189         if (found == -1) {
 190                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 191                 found = channels_alloc;
 192                 channels_alloc += 10;
 193                 debug("channel: expanding %d", channels_alloc);
 194                 channels = xrealloc(channels, channels_alloc * sizeof(Channel));
 195                 for (i = found; i < channels_alloc; i++)
 196                         channels[i].type = SSH_CHANNEL_FREE;
 197         }
 198         /* Initialize and return new channel number. */
 199         c = &channels[found];
 200         buffer_init(&c->input);
 201         buffer_init(&c->output);
 202         buffer_init(&c->extended);
 203         chan_init_iostates(c);
 204         c->self = found;
 205         c->type = type;
 206         c->ctype = ctype;
 207         c->local_window = window;
 208         c->local_window_max = window;
 209         c->local_consumed = 0;
 210         c->local_maxpacket = maxpack;
 211         c->remote_window = 0;
 212         c->remote_maxpacket = 0;
 213         c->rfd = rfd;
 214         c->wfd = wfd;
 215         c->sock = (rfd == wfd) ? rfd : -1;
 216         c->efd = efd;
 217         c->extended_usage = extended_usage;
 218         c->remote_id = -1;
 219         c->remote_name = remote_name;
 220         c->remote_window = 0;
 221         c->remote_maxpacket = 0;
 222         c->cb_fn = NULL;
 223         c->cb_arg = NULL;
 224         c->cb_event = 0;
 225         c->dettach_user = NULL;
 226         debug("channel %d: new [%s]", found, remote_name);
 227         return found;
 228 }
 229 int
 230 channel_allocate(int type, int sock, char *remote_name)
 231 {
 232         return channel_new("", type, sock, sock, -1, 0, 0, 0, remote_name);
 233 }
 234
 235 /* Free the channel and close its socket. */
 236
 237 void
 238 channel_free(int id)
 239 {
 240         Channel *c = channel_lookup(id);
 241         if (c == NULL)
 242                 packet_disconnect("channel free: bad local channel %d", id);
 243         debug("channel_free: channel %d: status: %s", id, channel_open_message());
 244         if (c->dettach_user != NULL) {
 245                 debug("channel_free: channel %d: dettaching channel user", id);
 246                 c->dettach_user(c->self, NULL);
 247         }
 248         if (c->sock != -1) {
 249                 shutdown(c->sock, SHUT_RDWR);
 250                 close(c->sock);
 251                 c->sock = -1;
 252         }
 253         if (compat20) {
 254                 if (c->rfd != -1) {
 255                         close(c->rfd);
 256                         c->rfd = -1;
 257                 }
 258                 if (c->wfd != -1) {
 259                         close(c->wfd);
 260                         c->wfd = -1;
 261                 }
 262                 if (c->efd != -1) {
 263                         close(c->efd);
 264                         c->efd = -1;
 265                 }
 266         }
 267         buffer_free(&c->input);
 268         buffer_free(&c->output);
 269         buffer_free(&c->extended);
 270         c->type = SSH_CHANNEL_FREE;
 271         if (c->remote_name) {
 272                 xfree(c->remote_name);
 273                 c->remote_name = NULL;
 274         }
 275 }
 276
 277 /*
 278  * 'channel_pre*' are called just before select() to add any bits relevant to
 279  * channels in the select bitmasks.
 280  */
 281 /*
 282  * 'channel_post*': perform any appropriate operations for channels which
 283  * have events pending.
 284  */
 285 typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
 286 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 287 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 288
 289 void
 290 channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
 291 {
 292         FD_SET(c->sock, readset);
 293 }
 294
 295 void
 296 channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 297 {
 298         if (buffer_len(&c->input) < packet_get_maxsize())
 299                 FD_SET(c->sock, readset);
 300         if (buffer_len(&c->output) > 0)
 301                 FD_SET(c->sock, writeset);
 302 }
 303
 304 void
 305 channel_pre_open_15(Channel *c, fd_set * readset, fd_set * writeset)
 306 {
 307         /* test whether sockets are 'alive' for read/write */
 308         if (c->istate == CHAN_INPUT_OPEN)
 309                 if (buffer_len(&c->input) < packet_get_maxsize())
 310                         FD_SET(c->sock, readset);
 311         if (c->ostate == CHAN_OUTPUT_OPEN ||
 312             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 313                 if (buffer_len(&c->output) > 0) {
 314                         FD_SET(c->sock, writeset);
 315                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 316                         chan_obuf_empty(c);
 317                 }
 318         }
 319 }
 320
 321 void
 322 channel_pre_open_20(Channel *c, fd_set * readset, fd_set * writeset)
 323 {
 324         if (c->istate == CHAN_INPUT_OPEN &&
 325             c->remote_window > 0 &&
 326             buffer_len(&c->input) < c->remote_window)
 327                 FD_SET(c->rfd, readset);
 328         if (c->ostate == CHAN_OUTPUT_OPEN ||
 329             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 330                 if (buffer_len(&c->output) > 0) {
 331                         FD_SET(c->wfd, writeset);
 332                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 333                         chan_obuf_empty(c);
 334                 }
 335         }
 336         /** XXX check close conditions, too */
 337         if (c->efd != -1) {
 338                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 339                     buffer_len(&c->extended) > 0)
 340                         FD_SET(c->efd, writeset);
 341                 else if (c->extended_usage == CHAN_EXTENDED_READ &&
 342                     buffer_len(&c->extended) < c->remote_window)
 343                         FD_SET(c->efd, readset);
 344         }
 345 }
 346
 347 void
 348 channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
 349 {
 350         if (buffer_len(&c->input) == 0) {
 351                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 352                 packet_put_int(c->remote_id);
 353                 packet_send();
 354                 c->type = SSH_CHANNEL_CLOSED;
 355                 debug("Closing channel %d after input drain.", c->self);
 356         }
 357 }
 358
 359 void
 360 channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
 361 {
 362         if (buffer_len(&c->output) == 0)
 363                 channel_free(c->self);
 364         else
 365                 FD_SET(c->sock, writeset);
 366 }
 367
 368 /*
 369  * This is a special state for X11 authentication spoofing.  An opened X11
 370  * connection (when authentication spoofing is being done) remains in this
 371  * state until the first packet has been completely read.  The authentication
 372  * data in that packet is then substituted by the real data if it matches the
 373  * fake data, and the channel is put into normal mode.
 374  */
 375 int
 376 x11_open_helper(Channel *c)
 377 {
 378         unsigned char *ucp;
 379         unsigned int proto_len, data_len;
 380
 381         /* Check if the fixed size part of the packet is in buffer. */
 382         if (buffer_len(&c->output) < 12)
 383                 return 0;
 384
 385         /* Parse the lengths of variable-length fields. */
 386         ucp = (unsigned char *) buffer_ptr(&c->output);
 387         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 388                 proto_len = 256 * ucp[6] + ucp[7];
 389                 data_len = 256 * ucp[8] + ucp[9];
 390         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 391                 proto_len = ucp[6] + 256 * ucp[7];
 392                 data_len = ucp[8] + 256 * ucp[9];
 393         } else {
 394                 debug("Initial X11 packet contains bad byte order byte: 0x%x",
 395                       ucp[0]);
 396                 return -1;
 397         }
 398
 399         /* Check if the whole packet is in buffer. */
 400         if (buffer_len(&c->output) <
 401             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 402                 return 0;
 403
 404         /* Check if authentication protocol matches. */
 405         if (proto_len != strlen(x11_saved_proto) ||
 406             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 407                 debug("X11 connection uses different authentication protocol.");
 408                 return -1;
 409         }
 410         /* Check if authentication data matches our fake data. */
 411         if (data_len != x11_fake_data_len ||
 412             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 413                 x11_fake_data, x11_fake_data_len) != 0) {
 414                 debug("X11 auth data does not match fake data.");
 415                 return -1;
 416         }
 417         /* Check fake data length */
 418         if (x11_fake_data_len != x11_saved_data_len) {
 419                 error("X11 fake_data_len %d != saved_data_len %d",
 420                     x11_fake_data_len, x11_saved_data_len);
 421                 return -1;
 422         }
 423         /*
 424          * Received authentication protocol and data match
 425          * our fake data. Substitute the fake data with real
 426          * data.
 427          */
 428         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 429             x11_saved_data, x11_saved_data_len);
 430         return 1;
 431 }
 432
 433 void
 434 channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
 435 {
 436         int ret = x11_open_helper(c);
 437         if (ret == 1) {
 438                 /* Start normal processing for the channel. */
 439                 c->type = SSH_CHANNEL_OPEN;
 440                 channel_pre_open_13(c, readset, writeset);
 441         } else if (ret == -1) {
 442                 /*
 443                  * We have received an X11 connection that has bad
 444                  * authentication information.
 445                  */
 446                 log("X11 connection rejected because of wrong authentication.\r\n");
 447                 buffer_clear(&c->input);
 448                 buffer_clear(&c->output);
 449                 close(c->sock);
 450                 c->sock = -1;
 451                 c->type = SSH_CHANNEL_CLOSED;
 452                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 453                 packet_put_int(c->remote_id);
 454                 packet_send();
 455         }
 456 }
 457
 458 void
 459 channel_pre_x11_open_15(Channel *c, fd_set * readset, fd_set * writeset)
 460 {
 461         int ret = x11_open_helper(c);
 462         if (ret == 1) {
 463                 c->type = SSH_CHANNEL_OPEN;
 464                 channel_pre_open_15(c, readset, writeset);
 465         } else if (ret == -1) {
 466                 debug("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 467                 chan_read_failed(c);
 468                 chan_write_failed(c);
 469                 debug("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 470         }
 471 }
 472
 473 /* This is our fake X11 server socket. */
 474 void
 475 channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
 476 {
 477         struct sockaddr addr;
 478         int newsock, newch;
 479         socklen_t addrlen;
 480         char buf[16384], *remote_hostname;
 481
 482         if (FD_ISSET(c->sock, readset)) {
 483                 debug("X11 connection requested.");
 484                 addrlen = sizeof(addr);
 485                 newsock = accept(c->sock, &addr, &addrlen);
 486                 if (newsock < 0) {
 487                         error("accept: %.100s", strerror(errno));
 488                         return;
 489                 }
 490                 remote_hostname = get_remote_hostname(newsock);
 491                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
 492                 remote_hostname, get_peer_port(newsock));
 493                 xfree(remote_hostname);
 494                 newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
 495                                          xstrdup(buf));
 496                 packet_start(SSH_SMSG_X11_OPEN);
 497                 packet_put_int(newch);
 498                 if (have_hostname_in_open)
 499                         packet_put_string(buf, strlen(buf));
 500                 packet_send();
 501         }
 502 }
 503
 504 /*
 505  * This socket is listening for connections to a forwarded TCP/IP port.
 506  */
 507 void
 508 channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
 509 {
 510         struct sockaddr addr;
 511         int newsock, newch;
 512         socklen_t addrlen;
 513         char buf[1024], *remote_hostname;
 514         int remote_port;
 515
 516         if (FD_ISSET(c->sock, readset)) {
 517                 debug("Connection to port %d forwarding "
 518                     "to %.100s port %d requested.",
 519                     c->listening_port, c->path, c->host_port);
 520                 addrlen = sizeof(addr);
 521                 newsock = accept(c->sock, &addr, &addrlen);
 522                 if (newsock < 0) {
 523                         error("accept: %.100s", strerror(errno));
 524                         return;
 525                 }
 526                 remote_hostname = get_remote_hostname(newsock);
 527                 remote_port = get_peer_port(newsock);
 528                 snprintf(buf, sizeof buf,
 529                     "listen port %d for %.100s port %d, "
 530                     "connect from %.200s port %d",
 531                     c->listening_port, c->path, c->host_port,
 532                     remote_hostname, remote_port);
 533                 newch = channel_new("direct-tcpip",
 534                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
 535                     c->local_window_max, c->local_maxpacket,
 536                     0, xstrdup(buf));
 537                 if (compat20) {
 538                         packet_start(SSH2_MSG_CHANNEL_OPEN);
 539                         packet_put_cstring("direct-tcpip");
 540                         packet_put_int(newch);
 541                         packet_put_int(c->local_window_max);
 542                         packet_put_int(c->local_maxpacket);
 543                         packet_put_string(c->path, strlen(c->path));
 544                         packet_put_int(c->host_port);
 545                         packet_put_cstring(remote_hostname);
 546                         packet_put_int(remote_port);
 547                         packet_send();
 548                 } else {
 549                         packet_start(SSH_MSG_PORT_OPEN);
 550                         packet_put_int(newch);
 551                         packet_put_string(c->path, strlen(c->path));
 552                         packet_put_int(c->host_port);
 553                         if (have_hostname_in_open) {
 554                                 packet_put_string(buf, strlen(buf));
 555                         }
 556                         packet_send();
 557                 }
 558                 xfree(remote_hostname);
 559         }
 560 }
 561
 562 /*
 563  * This is the authentication agent socket listening for connections from
 564  * clients.
 565  */
 566 void
 567 channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
 568 {
 569         struct sockaddr addr;
 570         int newsock, newch;
 571         socklen_t addrlen;
 572
 573         if (FD_ISSET(c->sock, readset)) {
 574                 addrlen = sizeof(addr);
 575                 newsock = accept(c->sock, &addr, &addrlen);
 576                 if (newsock < 0) {
 577                         error("accept from auth socket: %.100s", strerror(errno));
 578                         return;
 579                 }
 580                 newch = channel_allocate(SSH_CHANNEL_OPENING, newsock,
 581                     xstrdup("accepted auth socket"));
 582                 packet_start(SSH_SMSG_AGENT_OPEN);
 583                 packet_put_int(newch);
 584                 packet_send();
 585         }
 586 }
 587
 588 int
 589 channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
 590 {
 591         char buf[16*1024];
 592         int len;
 593
 594         if (c->rfd != -1 &&
 595             FD_ISSET(c->rfd, readset)) {
 596                 len = read(c->rfd, buf, sizeof(buf));
 597                 if (len <= 0) {
 598                         debug("channel %d: read<0 rfd %d len %d",
 599                             c->self, c->rfd, len);
 600                         if (compat13) {
 601                                 buffer_consume(&c->output, buffer_len(&c->output));
 602                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
 603                                 debug("Channel %d status set to input draining.", c->self);
 604                         } else {
 605                                 chan_read_failed(c);
 606                         }
 607                         return -1;
 608                 }
 609                 buffer_append(&c->input, buf, len);
 610         }
 611         return 1;
 612 }
 613 int
 614 channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
 615 {
 616         int len;
 617
 618         /* Send buffered output data to the socket. */
 619         if (c->wfd != -1 &&
 620             FD_ISSET(c->wfd, writeset) &&
 621             buffer_len(&c->output) > 0) {
 622                 len = write(c->wfd, buffer_ptr(&c->output),
 623                             buffer_len(&c->output));
 624                 if (len <= 0) {
 625                         if (compat13) {
 626                                 buffer_consume(&c->output, buffer_len(&c->output));
 627                                 debug("Channel %d status set to input draining.", c->self);
 628                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
 629                         } else {
 630                                 chan_write_failed(c);
 631                         }
 632                         return -1;
 633                 }
 634                 buffer_consume(&c->output, len);
 635                 if (compat20 && len > 0) {
 636                         c->local_consumed += len;
 637                 }
 638         }
 639         return 1;
 640 }
 641 int
 642 channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
 643 {
 644         char buf[16*1024];
 645         int len;
 646
 647 /** XXX handle drain efd, too */
 648         if (c->efd != -1) {
 649                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 650                     FD_ISSET(c->efd, writeset) &&
 651                     buffer_len(&c->extended) > 0) {
 652                         len = write(c->efd, buffer_ptr(&c->extended),
 653                             buffer_len(&c->extended));
 654                         debug("channel %d: written %d to efd %d",
 655                             c->self, len, c->efd);
 656                         if (len > 0) {
 657                                 buffer_consume(&c->extended, len);
 658                                 c->local_consumed += len;
 659                         }
 660                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
 661                     FD_ISSET(c->efd, readset)) {
 662                         len = read(c->efd, buf, sizeof(buf));
 663                         debug("channel %d: read %d from efd %d",
 664                              c->self, len, c->efd);
 665                         if (len == 0) {
 666                                 debug("channel %d: closing efd %d",
 667                                     c->self, c->efd);
 668                                 close(c->efd);
 669                                 c->efd = -1;
 670                         } else if (len > 0)
 671                                 buffer_append(&c->extended, buf, len);
 672                 }
 673         }
 674         return 1;
 675 }
 676 int
 677 channel_check_window(Channel *c, fd_set * readset, fd_set * writeset)
 678 {
 679         if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
 680             c->local_window < c->local_window_max/2 &&
 681             c->local_consumed > 0) {
 682                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 683                 packet_put_int(c->remote_id);
 684                 packet_put_int(c->local_consumed);
 685                 packet_send();
 686                 debug("channel %d: window %d sent adjust %d",
 687                     c->self, c->local_window,
 688                     c->local_consumed);
 689                 c->local_window += c->local_consumed;
 690                 c->local_consumed = 0;
 691         }
 692         return 1;
 693 }
 694
 695 void
 696 channel_post_open_1(Channel *c, fd_set * readset, fd_set * writeset)
 697 {
 698         channel_handle_rfd(c, readset, writeset);
 699         channel_handle_wfd(c, readset, writeset);
 700 }
 701
 702 void
 703 channel_post_open_2(Channel *c, fd_set * readset, fd_set * writeset)
 704 {
 705         channel_handle_rfd(c, readset, writeset);
 706         channel_handle_wfd(c, readset, writeset);
 707         channel_handle_efd(c, readset, writeset);
 708         channel_check_window(c, readset, writeset);
 709 }
 710
 711 void
 712 channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
 713 {
 714         int len;
 715         /* Send buffered output data to the socket. */
 716         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
 717                 len = write(c->sock, buffer_ptr(&c->output),
 718                             buffer_len(&c->output));
 719                 if (len <= 0)
 720                         buffer_consume(&c->output, buffer_len(&c->output));
 721                 else
 722                         buffer_consume(&c->output, len);
 723         }
 724 }
 725
 726 void
 727 channel_handler_init_20(void)
 728 {
 729         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_20;
 730         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 731
 732         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_2;
 733         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 734 }
 735
 736 void
 737 channel_handler_init_13(void)
 738 {
 739         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
 740         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
 741         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
 742         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 743         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
 744         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
 745         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
 746
 747         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_1;
 748         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
 749         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 750         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
 751         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
 752 }
 753
 754 void
 755 channel_handler_init_15(void)
 756 {
 757         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_15;
 758         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_15;
 759         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
 760         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
 761         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
 762
 763         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
 764         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
 765         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
 766         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open_1;
 767 }
 768
 769 void
 770 channel_handler_init(void)
 771 {
 772         int i;
 773         for(i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
 774                 channel_pre[i] = NULL;
 775                 channel_post[i] = NULL;
 776         }
 777         if (compat20)
 778                 channel_handler_init_20();
 779         else if (compat13)
 780                 channel_handler_init_13();
 781         else
 782                 channel_handler_init_15();
 783 }
 784
 785 void
 786 channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
 787 {
 788         static int did_init = 0;
 789         int i;
 790         Channel *c;
 791
 792         if (!did_init) {
 793                 channel_handler_init();
 794                 did_init = 1;
 795         }
 796         for (i = 0; i < channels_alloc; i++) {
 797                 c = &channels[i];
 798                 if (c->type == SSH_CHANNEL_FREE)
 799                         continue;
 800                 if (ftab[c->type] == NULL)
 801                         continue;
 802                 (*ftab[c->type])(c, readset, writeset);
 803                 chan_delete_if_full_closed(c);
 804         }
 805 }
 806
 807 void
 808 channel_prepare_select(fd_set * readset, fd_set * writeset)
 809 {
 810         channel_handler(channel_pre, readset, writeset);
 811 }
 812
 813 void
 814 channel_after_select(fd_set * readset, fd_set * writeset)
 815 {
 816         channel_handler(channel_post, readset, writeset);
 817 }
 818
 819 /* If there is data to send to the connection, send some of it now. */
 820
 821 void
 822 channel_output_poll()
 823 {
 824         int len, i;
 825         Channel *c;
 826
 827         for (i = 0; i < channels_alloc; i++) {
 828                 c = &channels[i];
 829
 830                 /* We are only interested in channels that can have buffered incoming data. */
 831                 if (compat13) {
 832                         if (c->type != SSH_CHANNEL_OPEN &&
 833                             c->type != SSH_CHANNEL_INPUT_DRAINING)
 834                                 continue;
 835                 } else {
 836                         if (c->type != SSH_CHANNEL_OPEN)
 837                                 continue;
 838                         if (c->istate != CHAN_INPUT_OPEN &&
 839                             c->istate != CHAN_INPUT_WAIT_DRAIN)
 840                                 continue;
 841                 }
 842                 if (compat20 &&
 843                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
 844                         debug("channel: %d: no data after CLOSE", c->self);
 845                         continue;
 846                 }
 847
 848                 /* Get the amount of buffered data for this channel. */
 849                 len = buffer_len(&c->input);
 850                 if (len > 0) {
 851                         /* Send some data for the other side over the secure connection. */
 852                         if (compat20) {
 853                                 if (len > c->remote_window)
 854                                         len = c->remote_window;
 855                                 if (len > c->remote_maxpacket)
 856                                         len = c->remote_maxpacket;
 857                         } else {
 858                                 if (packet_is_interactive()) {
 859                                         if (len > 1024)
 860                                                 len = 512;
 861                                 } else {
 862                                         /* Keep the packets at reasonable size. */
 863                                         if (len > packet_get_maxsize()/2)
 864                                                 len = packet_get_maxsize()/2;
 865                                 }
 866                         }
 867                         if (len > 0) {
 868                                 packet_start(compat20 ?
 869                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
 870                                 packet_put_int(c->remote_id);
 871                                 packet_put_string(buffer_ptr(&c->input), len);
 872                                 packet_send();
 873                                 buffer_consume(&c->input, len);
 874                                 c->remote_window -= len;
 875                                 debug("channel %d: send data len %d", c->self, len);
 876                         }
 877                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
 878                         if (compat13)
 879                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
 880                         /*
 881                          * input-buffer is empty and read-socket shutdown:
 882                          * tell peer, that we will not send more data: send IEOF
 883                          */
 884                         chan_ibuf_empty(c);
 885                 }
 886                 /* Send extended data, i.e. stderr */
 887                 if (compat20 &&
 888                     c->remote_window > 0 &&
 889                     (len = buffer_len(&c->extended)) > 0 &&
 890                     c->extended_usage == CHAN_EXTENDED_READ) {
 891                         if (len > c->remote_window)
 892                                 len = c->remote_window;
 893                         if (len > c->remote_maxpacket)
 894                                 len = c->remote_maxpacket;
 895                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
 896                         packet_put_int(c->remote_id);
 897                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
 898                         packet_put_string(buffer_ptr(&c->extended), len);
 899                         packet_send();
 900                         buffer_consume(&c->extended, len);
 901                         c->remote_window -= len;
 902                 }
 903         }
 904 }
 905
 906 /*
 907  * This is called when a packet of type CHANNEL_DATA has just been received.
 908  * The message type has already been consumed, but channel number and data is
 909  * still there.
 910  */
 911
 912 void
 913 channel_input_data(int type, int plen)
 914 {
 915         int id;
 916         char *data;
 917         unsigned int data_len;
 918         Channel *c;
 919
 920         /* Get the channel number and verify it. */
 921         id = packet_get_int();
 922         c = channel_lookup(id);
 923         if (c == NULL)
 924                 packet_disconnect("Received data for nonexistent channel %d.", id);
 925
 926         /* Ignore any data for non-open channels (might happen on close) */
 927         if (c->type != SSH_CHANNEL_OPEN &&
 928             c->type != SSH_CHANNEL_X11_OPEN)
 929                 return;
 930
 931         /* same for protocol 1.5 if output end is no longer open */
 932         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN)
 933                 return;
 934
 935         /* Get the data. */
 936         data = packet_get_string(&data_len);
 937
 938         if (compat20){
 939                 if (data_len > c->local_maxpacket) {
 940                         log("channel %d: rcvd big packet %d, maxpack %d",
 941                             c->self, data_len, c->local_maxpacket);
 942                 }
 943                 if (data_len > c->local_window) {
 944                         log("channel %d: rcvd too much data %d, win %d",
 945                             c->self, data_len, c->local_window);
 946                         xfree(data);
 947                         return;
 948                 }
 949                 c->local_window -= data_len;
 950         }else{
 951                 packet_integrity_check(plen, 4 + 4 + data_len, type);
 952         }
 953         buffer_append(&c->output, data, data_len);
 954         xfree(data);
 955 }
 956 void
 957 channel_input_extended_data(int type, int plen)
 958 {
 959         int id;
 960         int tcode;
 961         char *data;
 962         unsigned int data_len;
 963         Channel *c;
 964
 965         /* Get the channel number and verify it. */
 966         id = packet_get_int();
 967         c = channel_lookup(id);
 968
 969         if (c == NULL)
 970                 packet_disconnect("Received extended_data for bad channel %d.", id);
 971         if (c->type != SSH_CHANNEL_OPEN) {
 972                 log("channel %d: ext data for non open", id);
 973                 return;
 974         }
 975         tcode = packet_get_int();
 976         if (c->efd == -1 ||
 977             c->extended_usage != CHAN_EXTENDED_WRITE ||
 978             tcode != SSH2_EXTENDED_DATA_STDERR) {
 979                 log("channel %d: bad ext data", c->self);
 980                 return;
 981         }
 982         data = packet_get_string(&data_len);
 983         if (data_len > c->local_window) {
 984                 log("channel %d: rcvd too much extended_data %d, win %d",
 985                     c->self, data_len, c->local_window);
 986                 xfree(data);
 987                 return;
 988         }
 989         debug("channel %d: rcvd ext data %d", c->self, data_len);
 990         c->local_window -= data_len;
 991         buffer_append(&c->extended, data, data_len);
 992         xfree(data);
 993 }
 994
 995
 996 /*
 997  * Returns true if no channel has too much buffered data, and false if one or
 998  * more channel is overfull.
 999  */
1000
1001 int
1002 channel_not_very_much_buffered_data()
1003 {
1004         unsigned int i;
1005         Channel *c;
1006
1007         for (i = 0; i < channels_alloc; i++) {
1008                 c = &channels[i];
1009                 if (c->type == SSH_CHANNEL_OPEN) {
1010                         if (!compat20 && buffer_len(&c->input) > packet_get_maxsize()) {
1011                                 debug("channel %d: big input buffer %d",
1012                                     c->self, buffer_len(&c->input));
1013                                 return 0;
1014                         }
1015                         if (buffer_len(&c->output) > packet_get_maxsize()) {
1016                                 debug("channel %d: big output buffer %d",
1017                                     c->self, buffer_len(&c->output));
1018                                 return 0;
1019                         }
1020                 }
1021         }
1022         return 1;
1023 }
1024
1025 void
1026 channel_input_ieof(int type, int plen)
1027 {
1028         int id;
1029         Channel *c;
1030
1031         packet_integrity_check(plen, 4, type);
1032
1033         id = packet_get_int();
1034         c = channel_lookup(id);
1035         if (c == NULL)
1036                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
1037         chan_rcvd_ieof(c);
1038 }
1039
1040 void
1041 channel_input_close(int type, int plen)
1042 {
1043         int id;
1044         Channel *c;
1045
1046         packet_integrity_check(plen, 4, type);
1047
1048         id = packet_get_int();
1049         c = channel_lookup(id);
1050         if (c == NULL)
1051                 packet_disconnect("Received close for nonexistent channel %d.", id);
1052
1053         /*
1054          * Send a confirmation that we have closed the channel and no more
1055          * data is coming for it.
1056          */
1057         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
1058         packet_put_int(c->remote_id);
1059         packet_send();
1060
1061         /*
1062          * If the channel is in closed state, we have sent a close request,
1063          * and the other side will eventually respond with a confirmation.
1064          * Thus, we cannot free the channel here, because then there would be
1065          * no-one to receive the confirmation.  The channel gets freed when
1066          * the confirmation arrives.
1067          */
1068         if (c->type != SSH_CHANNEL_CLOSED) {
1069                 /*
1070                  * Not a closed channel - mark it as draining, which will
1071                  * cause it to be freed later.
1072                  */
1073                 buffer_consume(&c->input, buffer_len(&c->input));
1074                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
1075         }
1076 }
1077
1078 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
1079 void
1080 channel_input_oclose(int type, int plen)
1081 {
1082         int id = packet_get_int();
1083         Channel *c = channel_lookup(id);
1084         packet_integrity_check(plen, 4, type);
1085         if (c == NULL)
1086                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
1087         chan_rcvd_oclose(c);
1088 }
1089
1090 void
1091 channel_input_close_confirmation(int type, int plen)
1092 {
1093         int id = packet_get_int();
1094         Channel *c = channel_lookup(id);
1095
1096         if (c == NULL)
1097                 packet_disconnect("Received close confirmation for "
1098                     "out-of-range channel %d.", id);
1099         if (c->type != SSH_CHANNEL_CLOSED)
1100                 packet_disconnect("Received close confirmation for "
1101                     "non-closed channel %d (type %d).", id, c->type);
1102         channel_free(c->self);
1103 }
1104
1105 void
1106 channel_input_open_confirmation(int type, int plen)
1107 {
1108         int id, remote_id;
1109         Channel *c;
1110
1111         if (!compat20)
1112                 packet_integrity_check(plen, 4 + 4, type);
1113
1114         id = packet_get_int();
1115         c = channel_lookup(id);
1116
1117         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
1118                 packet_disconnect("Received open confirmation for "
1119                     "non-opening channel %d.", id);
1120         remote_id = packet_get_int();
1121         /* Record the remote channel number and mark that the channel is now open. */
1122         c->remote_id = remote_id;
1123         c->type = SSH_CHANNEL_OPEN;
1124
1125         if (compat20) {
1126                 c->remote_window = packet_get_int();
1127                 c->remote_maxpacket = packet_get_int();
1128                 if (c->cb_fn != NULL && c->cb_event == type) {
1129                         debug("callback start");
1130                         c->cb_fn(c->self, c->cb_arg);
1131                         debug("callback done");
1132                 }
1133                 debug("channel %d: open confirm rwindow %d rmax %d", c->self,
1134                     c->remote_window, c->remote_maxpacket);
1135         }
1136 }
1137
1138 void
1139 channel_input_open_failure(int type, int plen)
1140 {
1141         int id;
1142         Channel *c;
1143
1144         if (!compat20)
1145                 packet_integrity_check(plen, 4, type);
1146
1147         id = packet_get_int();
1148         c = channel_lookup(id);
1149
1150         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
1151                 packet_disconnect("Received open failure for "
1152                     "non-opening channel %d.", id);
1153         if (compat20) {
1154                 int reason = packet_get_int();
1155                 char *msg  = packet_get_string(NULL);
1156                 log("channel_open_failure: %d: reason %d: %s", id, reason, msg);
1157                 xfree(msg);
1158         }
1159         /* Free the channel.  This will also close the socket. */
1160         channel_free(id);
1161 }
1162
1163 void
1164 channel_input_channel_request(int type, int plen)
1165 {
1166         int id;
1167         Channel *c;
1168
1169         id = packet_get_int();
1170         c = channel_lookup(id);
1171
1172         if (c == NULL ||
1173             (c->type != SSH_CHANNEL_OPEN && c->type != SSH_CHANNEL_LARVAL))
1174                 packet_disconnect("Received request for "
1175                     "non-open channel %d.", id);
1176         if (c->cb_fn != NULL && c->cb_event == type) {
1177                 debug("callback start");
1178                 c->cb_fn(c->self, c->cb_arg);
1179                 debug("callback done");
1180         } else {
1181                 char *service = packet_get_string(NULL);
1182                 debug("channel: %d rcvd request for %s", c->self, service);
1183 debug("cb_fn %p cb_event %d", c->cb_fn , c->cb_event);
1184                 xfree(service);
1185         }
1186 }
1187
1188 void
1189 channel_input_window_adjust(int type, int plen)
1190 {
1191         Channel *c;
1192         int id, adjust;
1193
1194         if (!compat20)
1195                 return;
1196
1197         /* Get the channel number and verify it. */
1198         id = packet_get_int();
1199         c = channel_lookup(id);
1200
1201         if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
1202                 log("Received window adjust for "
1203                     "non-open channel %d.", id);
1204                 return;
1205         }
1206         adjust = packet_get_int();
1207         debug("channel %d: rcvd adjust %d", id, adjust);
1208         c->remote_window += adjust;
1209 }
1210
1211 /*
1212  * Stops listening for channels, and removes any unix domain sockets that we
1213  * might have.
1214  */
1215
1216 void
1217 channel_stop_listening()
1218 {
1219         int i;
1220         for (i = 0; i < channels_alloc; i++) {
1221                 switch (channels[i].type) {
1222                 case SSH_CHANNEL_AUTH_SOCKET:
1223                         close(channels[i].sock);
1224                         remove(channels[i].path);
1225                         channel_free(i);
1226                         break;
1227                 case SSH_CHANNEL_PORT_LISTENER:
1228                 case SSH_CHANNEL_X11_LISTENER:
1229                         close(channels[i].sock);
1230                         channel_free(i);
1231                         break;
1232                 default:
1233                         break;
1234                 }
1235         }
1236 }
1237
1238 /*
1239  * Closes the sockets of all channels.  This is used to close extra file
1240  * descriptors after a fork.
1241  */
1242
1243 void
1244 channel_close_all()
1245 {
1246         int i;
1247         for (i = 0; i < channels_alloc; i++) {
1248                 if (channels[i].type != SSH_CHANNEL_FREE)
1249                         close(channels[i].sock);
1250         }
1251 }
1252
1253 /* Returns the maximum file descriptor number used by the channels. */
1254
1255 int
1256 channel_max_fd()
1257 {
1258         return channel_max_fd_value;
1259 }
1260
1261 /* Returns true if any channel is still open. */
1262
1263 int
1264 channel_still_open()
1265 {
1266         unsigned int i;
1267         for (i = 0; i < channels_alloc; i++)
1268                 switch (channels[i].type) {
1269                 case SSH_CHANNEL_FREE:
1270                 case SSH_CHANNEL_X11_LISTENER:
1271                 case SSH_CHANNEL_PORT_LISTENER:
1272                 case SSH_CHANNEL_CLOSED:
1273                 case SSH_CHANNEL_AUTH_SOCKET:
1274                         continue;
1275                 case SSH_CHANNEL_LARVAL:
1276                         if (!compat20)
1277                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
1278                         continue;
1279                 case SSH_CHANNEL_OPENING:
1280                 case SSH_CHANNEL_OPEN:
1281                 case SSH_CHANNEL_X11_OPEN:
1282                         return 1;
1283                 case SSH_CHANNEL_INPUT_DRAINING:
1284                 case SSH_CHANNEL_OUTPUT_DRAINING:
1285                         if (!compat13)
1286                                 fatal("cannot happen: OUT_DRAIN");
1287                         return 1;
1288                 default:
1289                         fatal("channel_still_open: bad channel type %d", channels[i].type);
1290                         /* NOTREACHED */
1291                 }
1292         return 0;
1293 }
1294
1295 /*
1296  * Returns a message describing the currently open forwarded connections,
1297  * suitable for sending to the client.  The message contains crlf pairs for
1298  * newlines.
1299  */
1300
1301 char *
1302 channel_open_message()
1303 {
1304         Buffer buffer;
1305         int i;
1306         char buf[512], *cp;
1307
1308         buffer_init(&buffer);
1309         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
1310         buffer_append(&buffer, buf, strlen(buf));
1311         for (i = 0; i < channels_alloc; i++) {
1312                 Channel *c = &channels[i];
1313                 switch (c->type) {
1314                 case SSH_CHANNEL_FREE:
1315                 case SSH_CHANNEL_X11_LISTENER:
1316                 case SSH_CHANNEL_PORT_LISTENER:
1317                 case SSH_CHANNEL_CLOSED:
1318                 case SSH_CHANNEL_AUTH_SOCKET:
1319                         continue;
1320                 case SSH_CHANNEL_LARVAL:
1321                 case SSH_CHANNEL_OPENING:
1322                 case SSH_CHANNEL_OPEN:
1323                 case SSH_CHANNEL_X11_OPEN:
1324                 case SSH_CHANNEL_INPUT_DRAINING:
1325                 case SSH_CHANNEL_OUTPUT_DRAINING:
1326                         snprintf(buf, sizeof buf, "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d)\r\n",
1327                             c->self, c->remote_name,
1328                             c->type, c->remote_id,
1329                             c->istate, buffer_len(&c->input),
1330                             c->ostate, buffer_len(&c->output),
1331                             c->rfd, c->wfd);
1332                         buffer_append(&buffer, buf, strlen(buf));
1333                         continue;
1334                 default:
1335                         fatal("channel_open_message: bad channel type %d", c->type);
1336                         /* NOTREACHED */
1337                 }
1338         }
1339         buffer_append(&buffer, "\0", 1);
1340         cp = xstrdup(buffer_ptr(&buffer));
1341         buffer_free(&buffer);
1342         return cp;
1343 }
1344
1345 /*
1346  * Initiate forwarding of connections to local port "port" through the secure
1347  * channel to host:port from remote side.
1348  */
1349
1350 void
1351 channel_request_local_forwarding(u_short port, const char *host,
1352                                  u_short host_port, int gateway_ports)
1353 {
1354         int success, ch, sock, on = 1;
1355         struct addrinfo hints, *ai, *aitop;
1356         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1357         struct linger linger;
1358
1359         if (strlen(host) > sizeof(channels[0].path) - 1)
1360                 packet_disconnect("Forward host name too long.");
1361
1362         /*
1363          * getaddrinfo returns a loopback address if the hostname is
1364          * set to NULL and hints.ai_flags is not AI_PASSIVE
1365          */
1366         memset(&hints, 0, sizeof(hints));
1367         hints.ai_family = IPv4or6;
1368         hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
1369         hints.ai_socktype = SOCK_STREAM;
1370         snprintf(strport, sizeof strport, "%d", port);
1371         if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
1372                 packet_disconnect("getaddrinfo: fatal error");
1373
1374         success = 0;
1375         for (ai = aitop; ai; ai = ai->ai_next) {
1376                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1377                         continue;
1378                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
1379                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1380                         error("channel_request_local_forwarding: getnameinfo failed");
1381                         continue;
1382                 }
1383                 /* Create a port to listen for the host. */
1384                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1385                 if (sock < 0) {
1386                         /* this is no error since kernel may not support ipv6 */
1387                         verbose("socket: %.100s", strerror(errno));
1388                         continue;
1389                 }
1390                 /*
1391                  * Set socket options.  We would like the socket to disappear
1392                  * as soon as it has been closed for whatever reason.
1393                  */
1394                 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));
1395                 linger.l_onoff = 1;
1396                 linger.l_linger = 5;
1397                 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
1398                 debug("Local forwarding listening on %s port %s.", ntop, strport);
1399
1400                 /* Bind the socket to the address. */
1401                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1402                         /* address can be in use ipv6 address is already bound */
1403                         if (!ai->ai_next)
1404                                 error("bind: %.100s", strerror(errno));
1405                         else
1406                                 verbose("bind: %.100s", strerror(errno));
1407
1408                         close(sock);
1409                         continue;
1410                 }
1411                 /* Start listening for connections on the socket. */
1412                 if (listen(sock, 5) < 0) {
1413                         error("listen: %.100s", strerror(errno));
1414                         close(sock);
1415                         continue;
1416                 }
1417                 /* Allocate a channel number for the socket. */
1418                 ch = channel_new(
1419                     "port listener", SSH_CHANNEL_PORT_LISTENER,
1420                     sock, sock, -1,
1421                     CHAN_WINDOW_DEFAULT, CHAN_PACKET_DEFAULT,
1422                     0, xstrdup("port listener"));
1423                 strlcpy(channels[ch].path, host, sizeof(channels[ch].path));
1424                 channels[ch].host_port = host_port;
1425                 channels[ch].listening_port = port;
1426                 success = 1;
1427         }
1428         if (success == 0)
1429                 packet_disconnect("cannot listen port: %d", port);
1430         freeaddrinfo(aitop);
1431 }
1432
1433 /*
1434  * Initiate forwarding of connections to port "port" on remote host through
1435  * the secure channel to host:port from local side.
1436  */
1437
1438 void
1439 channel_request_remote_forwarding(u_short listen_port, const char *host_to_connect,
1440                                   u_short port_to_connect)
1441 {
1442         int payload_len;
1443         /* Record locally that connection to this host/port is permitted. */
1444         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
1445                 fatal("channel_request_remote_forwarding: too many forwards");
1446
1447         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
1448         permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
1449         permitted_opens[num_permitted_opens].listen_port = listen_port;
1450         num_permitted_opens++;
1451
1452         /* Send the forward request to the remote side. */
1453         if (compat20) {
1454                 const char *address_to_bind = "0.0.0.0";
1455                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1456                 packet_put_cstring("tcpip-forward");
1457                 packet_put_char(0);                     /* boolean: want reply */
1458                 packet_put_cstring(address_to_bind);
1459                 packet_put_int(listen_port);
1460         } else {
1461                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
1462                 packet_put_int(port_to_connect);
1463                 packet_put_cstring(host_to_connect);
1464                 packet_put_int(listen_port);
1465                 packet_send();
1466                 packet_write_wait();
1467                 /*
1468                  * Wait for response from the remote side.  It will send a disconnect
1469                  * message on failure, and we will never see it here.
1470                  */
1471                 packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
1472         }
1473 }
1474
1475 /*
1476  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
1477  * listening for the port, and sends back a success reply (or disconnect
1478  * message if there was an error).  This never returns if there was an error.
1479  */
1480
1481 void
1482 channel_input_port_forward_request(int is_root)
1483 {
1484         u_short port, host_port;
1485         char *hostname;
1486
1487         /* Get arguments from the packet. */
1488         port = packet_get_int();
1489         hostname = packet_get_string(NULL);
1490         host_port = packet_get_int();
1491
1492         /*
1493          * Check that an unprivileged user is not trying to forward a
1494          * privileged port.
1495          */
1496         if (port < IPPORT_RESERVED && !is_root)
1497                 packet_disconnect("Requested forwarding of port %d but user is not root.",
1498                                   port);
1499         /*
1500          * Initiate forwarding,
1501          * bind port to localhost only (gateway ports == 0).
1502          */
1503         channel_request_local_forwarding(port, hostname, host_port, 0);
1504
1505         /* Free the argument string. */
1506         xfree(hostname);
1507 }
1508
1509 /* XXX move to aux.c */
1510 int
1511 channel_connect_to(const char *host, u_short host_port)
1512 {
1513         struct addrinfo hints, *ai, *aitop;
1514         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1515         int gaierr;
1516         int sock = -1;
1517
1518         memset(&hints, 0, sizeof(hints));
1519         hints.ai_family = IPv4or6;
1520         hints.ai_socktype = SOCK_STREAM;
1521         snprintf(strport, sizeof strport, "%d", host_port);
1522         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
1523                 error("%.100s: unknown host (%s)", host, gai_strerror(gaierr));
1524                 return -1;
1525         }
1526         for (ai = aitop; ai; ai = ai->ai_next) {
1527                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1528                         continue;
1529                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
1530                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1531                         error("channel_connect_to: getnameinfo failed");
1532                         continue;
1533                 }
1534                 /* Create the socket. */
1535                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1536                 if (sock < 0) {
1537                         error("socket: %.100s", strerror(errno));
1538                         continue;
1539                 }
1540                 /* Connect to the host/port. */
1541                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1542                         error("connect %.100s port %s: %.100s", ntop, strport,
1543                             strerror(errno));
1544                         close(sock);
1545                         continue;       /* fail -- try next */
1546                 }
1547                 break; /* success */
1548
1549         }
1550         freeaddrinfo(aitop);
1551         if (!ai) {
1552                 error("connect %.100s port %d: failed.", host, host_port);
1553                 return -1;
1554         }
1555         /* success */
1556         return sock;
1557 }
1558
1559 /*
1560  * This is called after receiving PORT_OPEN message.  This attempts to
1561  * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
1562  * or CHANNEL_OPEN_FAILURE.
1563  */
1564
1565 void
1566 channel_input_port_open(int type, int plen)
1567 {
1568         u_short host_port;
1569         char *host, *originator_string;
1570         int remote_channel, sock = -1, newch, i, denied;
1571         unsigned int host_len, originator_len;
1572
1573         /* Get remote channel number. */
1574         remote_channel = packet_get_int();
1575
1576         /* Get host name to connect to. */
1577         host = packet_get_string(&host_len);
1578
1579         /* Get port to connect to. */
1580         host_port = packet_get_int();
1581
1582         /* Get remote originator name. */
1583         if (have_hostname_in_open) {
1584                 originator_string = packet_get_string(&originator_len);
1585                 originator_len += 4;    /* size of packet_int */
1586         } else {
1587                 originator_string = xstrdup("unknown (remote did not supply name)");
1588                 originator_len = 0;     /* no originator supplied */
1589         }
1590
1591         packet_integrity_check(plen,
1592             4 + 4 + host_len + 4 + originator_len, SSH_MSG_PORT_OPEN);
1593
1594         /* Check if opening that port is permitted. */
1595         denied = 0;
1596         if (!all_opens_permitted) {
1597                 /* Go trough all permitted ports. */
1598                 for (i = 0; i < num_permitted_opens; i++)
1599                         if (permitted_opens[i].port_to_connect == host_port &&
1600                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
1601                                 break;
1602
1603                 /* Check if we found the requested port among those permitted. */
1604                 if (i >= num_permitted_opens) {
1605                         /* The port is not permitted. */
1606                         log("Received request to connect to %.100s:%d, but the request was denied.",
1607                             host, host_port);
1608                         denied = 1;
1609                 }
1610         }
1611         sock = denied ? -1 : channel_connect_to(host, host_port);
1612         if (sock > 0) {
1613                 /* Allocate a channel for this connection. */
1614                 newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string);
1615                 channels[newch].remote_id = remote_channel;
1616
1617                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1618                 packet_put_int(remote_channel);
1619                 packet_put_int(newch);
1620                 packet_send();
1621         } else {
1622                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1623                 packet_put_int(remote_channel);
1624                 packet_send();
1625         }
1626         xfree(host);
1627 }
1628
1629 /*
1630  * Creates an internet domain socket for listening for X11 connections.
1631  * Returns a suitable value for the DISPLAY variable, or NULL if an error
1632  * occurs.
1633  */
1634
1635 #define NUM_SOCKS       10
1636
1637 char *
1638 x11_create_display_inet(int screen_number, int x11_display_offset)
1639 {
1640         int display_number, sock;
1641         u_short port;
1642         struct addrinfo hints, *ai, *aitop;
1643         char strport[NI_MAXSERV];
1644         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
1645         char display[512];
1646         char hostname[MAXHOSTNAMELEN];
1647
1648         for (display_number = x11_display_offset;
1649              display_number < MAX_DISPLAYS;
1650              display_number++) {
1651                 port = 6000 + display_number;
1652                 memset(&hints, 0, sizeof(hints));
1653                 hints.ai_family = IPv4or6;
1654                 hints.ai_flags = AI_PASSIVE;            /* XXX loopback only ? */
1655                 hints.ai_socktype = SOCK_STREAM;
1656                 snprintf(strport, sizeof strport, "%d", port);
1657                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
1658                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
1659                         return NULL;
1660                 }
1661                 for (ai = aitop; ai; ai = ai->ai_next) {
1662                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1663                                 continue;
1664                         sock = socket(ai->ai_family, SOCK_STREAM, 0);
1665                         if (sock < 0) {
1666                                 if (errno != EINVAL) {
1667                                         error("socket: %.100s", strerror(errno));
1668                                         return NULL;
1669                                 } else {
1670                                         debug("Socket family %d not supported [X11 disp create]", ai->ai_family);
1671                                         continue;
1672                                 }
1673                         }
1674                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1675                                 debug("bind port %d: %.100s", port, strerror(errno));
1676                                 shutdown(sock, SHUT_RDWR);
1677                                 close(sock);
1678
1679                                 if (ai->ai_next)
1680                                         continue;
1681
1682                                 for (n = 0; n < num_socks; n++) {
1683                                         shutdown(socks[n], SHUT_RDWR);
1684                                         close(socks[n]);
1685                                 }
1686                                 num_socks = 0;
1687                                 break;
1688                         }
1689                         socks[num_socks++] = sock;
1690 #ifndef DONT_TRY_OTHER_AF
1691                         if (num_socks == NUM_SOCKS)
1692                                 break;
1693 #else
1694                         break;
1695 #endif
1696                 }
1697                 if (num_socks > 0)
1698                         break;
1699         }
1700         if (display_number >= MAX_DISPLAYS) {
1701                 error("Failed to allocate internet-domain X11 display socket.");
1702                 return NULL;
1703         }
1704         /* Start listening for connections on the socket. */
1705         for (n = 0; n < num_socks; n++) {
1706                 sock = socks[n];
1707                 if (listen(sock, 5) < 0) {
1708                         error("listen: %.100s", strerror(errno));
1709                         shutdown(sock, SHUT_RDWR);
1710                         close(sock);
1711                         return NULL;
1712                 }
1713         }
1714
1715         /* Set up a suitable value for the DISPLAY variable. */
1716
1717         if (gethostname(hostname, sizeof(hostname)) < 0)
1718                 fatal("gethostname: %.100s", strerror(errno));
1719
1720 #ifdef IPADDR_IN_DISPLAY
1721         /*
1722          * HPUX detects the local hostname in the DISPLAY variable and tries
1723          * to set up a shared memory connection to the server, which it
1724          * incorrectly supposes to be local.
1725          *
1726          * The workaround - as used in later $$H and other programs - is
1727          * is to set display to the host's IP address.
1728          */
1729         {
1730                 struct hostent *he;
1731                 struct in_addr my_addr;
1732
1733                 he = gethostbyname(hostname);
1734                 if (he == NULL) {
1735                         error("[X11-broken-fwd-hostname-workaround] Could not get "
1736                                 "IP address for hostname %s.", hostname);
1737
1738                         packet_send_debug("[X11-broken-fwd-hostname-workaround]"
1739                                 "Could not get IP address for hostname %s.", hostname);
1740
1741                         shutdown(sock, SHUT_RDWR);
1742                         close(sock);
1743
1744                         return NULL;
1745                 }
1746
1747                 memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
1748
1749                 /* Set DISPLAY to <ip address>:screen.display */
1750                 snprintf(display, sizeof(display), "%.50s:%d.%d", inet_ntoa(my_addr),
1751                         display_number, screen_number);
1752         }
1753 #else /* IPADDR_IN_DISPLAY */
1754         /* Just set DISPLAY to hostname:screen.display */
1755         snprintf(display, sizeof display, "%.400s:%d.%d", hostname,
1756                 display_number, screen_number);
1757 #endif /* IPADDR_IN_DISPLAY */
1758
1759         /* Allocate a channel for each socket. */
1760         for (n = 0; n < num_socks; n++) {
1761                 sock = socks[n];
1762                 (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock,
1763                                         xstrdup("X11 inet listener"));
1764         }
1765
1766         /* Return a suitable value for the DISPLAY environment variable. */
1767         return xstrdup(display);
1768 }
1769
1770 #ifndef X_UNIX_PATH
1771 #define X_UNIX_PATH "/tmp/.X11-unix/X"
1772 #endif
1773
1774 static
1775 int
1776 connect_local_xsocket(unsigned int dnr)
1777 {
1778         static const char *const x_sockets[] = {
1779                 X_UNIX_PATH "%u",
1780                 "/var/X/.X11-unix/X" "%u",
1781                 "/usr/spool/sockets/X11/" "%u",
1782                 NULL
1783         };
1784         int sock;
1785         struct sockaddr_un addr;
1786         const char *const * path;
1787
1788         for (path = x_sockets; *path; ++path) {
1789                 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1790                 if (sock < 0)
1791                         error("socket: %.100s", strerror(errno));
1792                 memset(&addr, 0, sizeof(addr));
1793                 addr.sun_family = AF_UNIX;
1794                 snprintf(addr.sun_path, sizeof addr.sun_path, *path, dnr);
1795                 if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
1796                         return sock;
1797                 close(sock);
1798         }
1799         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
1800         return -1;
1801 }
1802
1803
1804 /*
1805  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
1806  * the remote channel number.  We should do whatever we want, and respond
1807  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
1808  */
1809
1810 void
1811 x11_input_open(int type, int plen)
1812 {
1813         int remote_channel, display_number, sock = 0, newch;
1814         const char *display;
1815         char buf[1024], *cp, *remote_host;
1816         unsigned int remote_len;
1817         struct addrinfo hints, *ai, *aitop;
1818         char strport[NI_MAXSERV];
1819         int gaierr;
1820
1821         /* Get remote channel number. */
1822         remote_channel = packet_get_int();
1823
1824         /* Get remote originator name. */
1825         if (have_hostname_in_open) {
1826                 remote_host = packet_get_string(&remote_len);
1827                 remote_len += 4;
1828         } else {
1829                 remote_host = xstrdup("unknown (remote did not supply name)");
1830                 remote_len = 0;
1831         }
1832
1833         debug("Received X11 open request.");
1834         packet_integrity_check(plen, 4 + remote_len, SSH_SMSG_X11_OPEN);
1835
1836         /* Try to open a socket for the local X server. */
1837         display = getenv("DISPLAY");
1838         if (!display) {
1839                 error("DISPLAY not set.");
1840                 goto fail;
1841         }
1842         /*
1843          * Now we decode the value of the DISPLAY variable and make a
1844          * connection to the real X server.
1845          */
1846
1847         /*
1848          * Check if it is a unix domain socket.  Unix domain displays are in
1849          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
1850          */
1851         if (strncmp(display, "unix:", 5) == 0 ||
1852             display[0] == ':') {
1853                 /* Connect to the unix domain socket. */
1854                 if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
1855                         error("Could not parse display number from DISPLAY: %.100s",
1856                               display);
1857                         goto fail;
1858                 }
1859                 /* Create a socket. */
1860                 sock = connect_local_xsocket(display_number);
1861                 if (sock < 0)
1862                         goto fail;
1863
1864                 /* OK, we now have a connection to the display. */
1865                 goto success;
1866         }
1867         /*
1868          * Connect to an inet socket.  The DISPLAY value is supposedly
1869          * hostname:d[.s], where hostname may also be numeric IP address.
1870          */
1871         strncpy(buf, display, sizeof(buf));
1872         buf[sizeof(buf) - 1] = 0;
1873         cp = strchr(buf, ':');
1874         if (!cp) {
1875                 error("Could not find ':' in DISPLAY: %.100s", display);
1876                 goto fail;
1877         }
1878         *cp = 0;
1879         /* buf now contains the host name.  But first we parse the display number. */
1880         if (sscanf(cp + 1, "%d", &display_number) != 1) {
1881                 error("Could not parse display number from DISPLAY: %.100s",
1882                       display);
1883                 goto fail;
1884         }
1885
1886         /* Look up the host address */
1887         memset(&hints, 0, sizeof(hints));
1888         hints.ai_family = IPv4or6;
1889         hints.ai_socktype = SOCK_STREAM;
1890         snprintf(strport, sizeof strport, "%d", 6000 + display_number);
1891         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
1892                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
1893                 goto fail;
1894         }
1895         for (ai = aitop; ai; ai = ai->ai_next) {
1896                 /* Create a socket. */
1897                 sock = socket(ai->ai_family, SOCK_STREAM, 0);
1898                 if (sock < 0) {
1899                         debug("socket: %.100s", strerror(errno));
1900                         continue;
1901                 }
1902                 /* Connect it to the display. */
1903                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1904                         debug("connect %.100s port %d: %.100s", buf,
1905                             6000 + display_number, strerror(errno));
1906                         close(sock);
1907                         continue;
1908                 }
1909                 /* Success */
1910                 break;
1911         }
1912         freeaddrinfo(aitop);
1913         if (!ai) {
1914                 error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
1915                     strerror(errno));
1916                 goto fail;
1917         }
1918 success:
1919         /* We have successfully obtained a connection to the real X display. */
1920
1921         /* Allocate a channel for this connection. */
1922         if (x11_saved_proto == NULL)
1923                 newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host);
1924         else
1925                 newch = channel_allocate(SSH_CHANNEL_X11_OPEN, sock, remote_host);
1926         channels[newch].remote_id = remote_channel;
1927
1928         /* Send a confirmation to the remote host. */
1929         packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1930         packet_put_int(remote_channel);
1931         packet_put_int(newch);
1932         packet_send();
1933
1934         return;
1935
1936 fail:
1937         /* Send refusal to the remote host. */
1938         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1939         packet_put_int(remote_channel);
1940         packet_send();
1941 }
1942
1943 /*
1944  * Requests forwarding of X11 connections, generates fake authentication
1945  * data, and enables authentication spoofing.
1946  */
1947
1948 void
1949 x11_request_forwarding_with_spoofing(const char *proto, const char *data)
1950 {
1951         unsigned int data_len = (unsigned int) strlen(data) / 2;
1952         unsigned int i, value;
1953         char *new_data;
1954         int screen_number;
1955         const char *cp;
1956         u_int32_t rand = 0;
1957
1958         cp = getenv("DISPLAY");
1959         if (cp)
1960                 cp = strchr(cp, ':');
1961         if (cp)
1962                 cp = strchr(cp, '.');
1963         if (cp)
1964                 screen_number = atoi(cp + 1);
1965         else
1966                 screen_number = 0;
1967
1968         /* Save protocol name. */
1969         x11_saved_proto = xstrdup(proto);
1970
1971         /*
1972          * Extract real authentication data and generate fake data of the
1973          * same length.
1974          */
1975         x11_saved_data = xmalloc(data_len);
1976         x11_fake_data = xmalloc(data_len);
1977         for (i = 0; i < data_len; i++) {
1978                 if (sscanf(data + 2 * i, "%2x", &value) != 1)
1979                         fatal("x11_request_forwarding: bad authentication data: %.100s", data);
1980                 if (i % 4 == 0)
1981                         rand = arc4random();
1982                 x11_saved_data[i] = value;
1983                 x11_fake_data[i] = rand & 0xff;
1984                 rand >>= 8;
1985         }
1986         x11_saved_data_len = data_len;
1987         x11_fake_data_len = data_len;
1988
1989         /* Convert the fake data into hex. */
1990         new_data = xmalloc(2 * data_len + 1);
1991         for (i = 0; i < data_len; i++)
1992                 sprintf(new_data + 2 * i, "%02x", (unsigned char) x11_fake_data[i]);
1993
1994         /* Send the request packet. */
1995         packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
1996         packet_put_string(proto, strlen(proto));
1997         packet_put_string(new_data, strlen(new_data));
1998         packet_put_int(screen_number);
1999         packet_send();
2000         packet_write_wait();
2001         xfree(new_data);
2002 }
2003
2004 /* Sends a message to the server to request authentication fd forwarding. */
2005
2006 void
2007 auth_request_forwarding()
2008 {
2009         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
2010         packet_send();
2011         packet_write_wait();
2012 }
2013
2014 /*
2015  * Returns the name of the forwarded authentication socket.  Returns NULL if
2016  * there is no forwarded authentication socket.  The returned value points to
2017  * a static buffer.
2018  */
2019
2020 char *
2021 auth_get_socket_name()
2022 {
2023         return channel_forwarded_auth_socket_name;
2024 }
2025
2026 /* removes the agent forwarding socket */
2027
2028 void
2029 cleanup_socket(void)
2030 {
2031         remove(channel_forwarded_auth_socket_name);
2032         rmdir(channel_forwarded_auth_socket_dir);
2033 }
2034
2035 /*
2036  * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
2037  * This starts forwarding authentication requests.
2038  */
2039
2040 void
2041 auth_input_request_forwarding(struct passwd * pw)
2042 {
2043         int sock, newch;
2044         struct sockaddr_un sunaddr;
2045
2046         if (auth_get_socket_name() != NULL)
2047                 fatal("Protocol error: authentication forwarding requested twice.");
2048
2049         /* Temporarily drop privileged uid for mkdir/bind. */
2050         temporarily_use_uid(pw->pw_uid);
2051
2052         /* Allocate a buffer for the socket name, and format the name. */
2053         channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME);
2054         channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME);
2055         strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME);
2056
2057         /* Create private directory for socket */
2058         if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL)
2059                 packet_disconnect("mkdtemp: %.100s", strerror(errno));
2060         snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d",
2061                  channel_forwarded_auth_socket_dir, (int) getpid());
2062
2063         if (atexit(cleanup_socket) < 0) {
2064                 int saved = errno;
2065                 cleanup_socket();
2066                 packet_disconnect("socket: %.100s", strerror(saved));
2067         }
2068         /* Create the socket. */
2069         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2070         if (sock < 0)
2071                 packet_disconnect("socket: %.100s", strerror(errno));
2072
2073         /* Bind it to the name. */
2074         memset(&sunaddr, 0, sizeof(sunaddr));
2075         sunaddr.sun_family = AF_UNIX;
2076         strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_name,
2077                 sizeof(sunaddr.sun_path));
2078
2079         if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
2080                 packet_disconnect("bind: %.100s", strerror(errno));
2081
2082         /* Restore the privileged uid. */
2083         restore_uid();
2084
2085         /* Start listening on the socket. */
2086         if (listen(sock, 5) < 0)
2087                 packet_disconnect("listen: %.100s", strerror(errno));
2088
2089         /* Allocate a channel for the authentication agent socket. */
2090         newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock,
2091                                  xstrdup("auth socket"));
2092         strlcpy(channels[newch].path, channel_forwarded_auth_socket_name,
2093             sizeof(channels[newch].path));
2094 }
2095
2096 /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
2097
2098 void
2099 auth_input_open_request(int type, int plen)
2100 {
2101         int remch, sock, newch;
2102         char *dummyname;
2103
2104         packet_integrity_check(plen, 4, type);
2105
2106         /* Read the remote channel number from the message. */
2107         remch = packet_get_int();
2108
2109         /*
2110          * Get a connection to the local authentication agent (this may again
2111          * get forwarded).
2112          */
2113         sock = ssh_get_authentication_socket();
2114
2115         /*
2116          * If we could not connect the agent, send an error message back to
2117          * the server. This should never happen unless the agent dies,
2118          * because authentication forwarding is only enabled if we have an
2119          * agent.
2120          */
2121         if (sock < 0) {
2122                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2123                 packet_put_int(remch);
2124                 packet_send();
2125                 return;
2126         }
2127         debug("Forwarding authentication connection.");
2128
2129         /*
2130          * Dummy host name.  This will be freed when the channel is freed; it
2131          * will still be valid in the packet_put_string below since the
2132          * channel cannot yet be freed at that point.
2133          */
2134         dummyname = xstrdup("authentication agent connection");
2135
2136         newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname);
2137         channels[newch].remote_id = remch;
2138
2139         /* Send a confirmation to the remote host. */
2140         packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
2141         packet_put_int(remch);
2142         packet_put_int(newch);
2143         packet_send();
2144 }
2145
2146 void
2147 channel_open(int id)
2148 {
2149         Channel *c = channel_lookup(id);
2150         if (c == NULL) {
2151                 log("channel_open: %d: bad id", id);
2152                 return;
2153         }
2154         packet_start(SSH2_MSG_CHANNEL_OPEN);
2155         packet_put_cstring(c->ctype);
2156         packet_put_int(c->self);
2157         packet_put_int(c->local_window);
2158         packet_put_int(c->local_maxpacket);
2159         packet_send();
2160         debug("channel open %d", id);
2161 }
2162 void
2163 channel_request(int id, char *service, int wantconfirm)
2164 {
2165         channel_request_start(id, service, wantconfirm);
2166         packet_send();
2167         debug("channel request %d: %s", id, service) ;
2168 }
2169 void
2170 channel_request_start(int id, char *service, int wantconfirm)
2171 {
2172         Channel *c = channel_lookup(id);
2173         if (c == NULL) {
2174                 log("channel_request: %d: bad id", id);
2175                 return;
2176         }
2177         packet_start(SSH2_MSG_CHANNEL_REQUEST);
2178         packet_put_int(c->remote_id);
2179         packet_put_cstring(service);
2180         packet_put_char(wantconfirm);
2181 }
2182 void
2183 channel_register_callback(int id, int mtype, channel_callback_fn *fn, void *arg)
2184 {
2185         Channel *c = channel_lookup(id);
2186         if (c == NULL) {
2187                 log("channel_register_callback: %d: bad id", id);
2188                 return;
2189         }
2190         c->cb_event = mtype;
2191         c->cb_fn = fn;
2192         c->cb_arg = arg;
2193 }
2194 void
2195 channel_register_cleanup(int id, channel_callback_fn *fn)
2196 {
2197         Channel *c = channel_lookup(id);
2198         if (c == NULL) {
2199                 log("channel_register_cleanup: %d: bad id", id);
2200                 return;
2201         }
2202         c->dettach_user = fn;
2203 }
2204 void
2205 channel_cancel_cleanup(int id)
2206 {
2207         Channel *c = channel_lookup(id);
2208         if (c == NULL) {
2209                 log("channel_cancel_cleanup: %d: bad id", id);
2210                 return;
2211         }
2212         c->dettach_user = NULL;
2213 }
2214
2215 void
2216 channel_set_fds(int id, int rfd, int wfd, int efd, int extusage)
2217 {
2218         Channel *c = channel_lookup(id);
2219         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
2220                 fatal("channel_activate for non-larval channel %d.", id);
2221         if (rfd > channel_max_fd_value)
2222                 channel_max_fd_value = rfd;
2223         if (wfd > channel_max_fd_value)
2224                 channel_max_fd_value = wfd;
2225         if (efd > channel_max_fd_value)
2226                 channel_max_fd_value = efd;
2227         c->type = SSH_CHANNEL_OPEN;
2228         c->rfd = rfd;
2229         c->wfd = wfd;
2230         c->efd = efd;
2231         c->extended_usage = extusage;
2232         /* XXX window size? */
2233         c->local_window = c->local_window_max = c->local_maxpacket/2;
2234         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
2235         packet_put_int(c->remote_id);
2236         packet_put_int(c->local_window);
2237         packet_send();
2238 }