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