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