openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.286 2008/07/16 11:52:19 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <netdb.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <termios.h>
  61 #include <unistd.h>
  62 #include <stdarg.h>
  63
  64 #include "openbsd-compat/sys-queue.h"
  65 #include "xmalloc.h"
  66 #include "ssh.h"
  67 #include "ssh1.h"
  68 #include "ssh2.h"
  69 #include "packet.h"
  70 #include "log.h"
  71 #include "misc.h"
  72 #include "buffer.h"
  73 #include "channels.h"
  74 #include "compat.h"
  75 #include "canohost.h"
  76 #include "key.h"
  77 #include "authfd.h"
  78 #include "pathnames.h"
  79
  80 /* -- channel core */
  81
  82 /*
  83  * Pointer to an array containing all allocated channels.  The array is
  84  * dynamically extended as needed.
  85  */
  86 static Channel **channels = NULL;
  87
  88 /*
  89  * Size of the channel array.  All slots of the array must always be
  90  * initialized (at least the type field); unused slots set to NULL
  91  */
  92 static u_int channels_alloc = 0;
  93
  94 /*
  95  * Maximum file descriptor value used in any of the channels.  This is
  96  * updated in channel_new.
  97  */
  98 static int channel_max_fd = 0;
  99
 100
 101 /* -- tcp forwarding */
 102
 103 /*
 104  * Data structure for storing which hosts are permitted for forward requests.
 105  * The local sides of any remote forwards are stored in this array to prevent
 106  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 107  * network (which might be behind a firewall).
 108  */
 109 typedef struct {
 110         char *host_to_connect;          /* Connect to 'host'. */
 111         u_short port_to_connect;        /* Connect to 'port'. */
 112         u_short listen_port;            /* Remote side should listen port number. */
 113 } ForwardPermission;
 114
 115 /* List of all permitted host/port pairs to connect by the user. */
 116 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 117
 118 /* List of all permitted host/port pairs to connect by the admin. */
 119 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 120
 121 /* Number of permitted host/port pairs in the array permitted by the user. */
 122 static int num_permitted_opens = 0;
 123
 124 /* Number of permitted host/port pair in the array permitted by the admin. */
 125 static int num_adm_permitted_opens = 0;
 126
 127 /*
 128  * If this is true, all opens are permitted.  This is the case on the server
 129  * on which we have to trust the client anyway, and the user could do
 130  * anything after logging in anyway.
 131  */
 132 static int all_opens_permitted = 0;
 133
 134
 135 /* -- X11 forwarding */
 136
 137 /* Maximum number of fake X11 displays to try. */
 138 #define MAX_DISPLAYS  1000
 139
 140 /* Saved X11 local (client) display. */
 141 static char *x11_saved_display = NULL;
 142
 143 /* Saved X11 authentication protocol name. */
 144 static char *x11_saved_proto = NULL;
 145
 146 /* Saved X11 authentication data.  This is the real data. */
 147 static char *x11_saved_data = NULL;
 148 static u_int x11_saved_data_len = 0;
 149
 150 /*
 151  * Fake X11 authentication data.  This is what the server will be sending us;
 152  * we should replace any occurrences of this by the real data.
 153  */
 154 static u_char *x11_fake_data = NULL;
 155 static u_int x11_fake_data_len;
 156
 157
 158 /* -- agent forwarding */
 159
 160 #define NUM_SOCKS       10
 161
 162 /* AF_UNSPEC or AF_INET or AF_INET6 */
 163 static int IPv4or6 = AF_UNSPEC;
 164
 165 /* helper */
 166 static void port_open_helper(Channel *c, char *rtype);
 167
 168 /* non-blocking connect helpers */
 169 static int connect_next(struct channel_connect *);
 170 static void channel_connect_ctx_free(struct channel_connect *);
 171
 172
 173 static int hpn_disabled = 0;
 174 static int hpn_buffer_size = 2 * 1024 * 1024;
 175
 176 /* -- channel core */
 177
 178
 179
 180 Channel *
 181 channel_by_id(int id)
 182 {
 183         Channel *c;
 184
 185         if (id < 0 || (u_int)id >= channels_alloc) {
 186                 logit("channel_by_id: %d: bad id", id);
 187                 return NULL;
 188         }
 189         c = channels[id];
 190         if (c == NULL) {
 191                 logit("channel_by_id: %d: bad id: channel free", id);
 192                 return NULL;
 193         }
 194         return c;
 195 }
 196
 197 /*
 198  * Returns the channel if it is allowed to receive protocol messages.
 199  * Private channels, like listening sockets, may not receive messages.
 200  */
 201 Channel *
 202 channel_lookup(int id)
 203 {
 204         Channel *c;
 205
 206         if ((c = channel_by_id(id)) == NULL)
 207                 return (NULL);
 208
 209         switch (c->type) {
 210         case SSH_CHANNEL_X11_OPEN:
 211         case SSH_CHANNEL_LARVAL:
 212         case SSH_CHANNEL_CONNECTING:
 213         case SSH_CHANNEL_DYNAMIC:
 214         case SSH_CHANNEL_OPENING:
 215         case SSH_CHANNEL_OPEN:
 216         case SSH_CHANNEL_INPUT_DRAINING:
 217         case SSH_CHANNEL_OUTPUT_DRAINING:
 218                 return (c);
 219         }
 220         logit("Non-public channel %d, type %d.", id, c->type);
 221         return (NULL);
 222 }
 223
 224 /*
 225  * Register filedescriptors for a channel, used when allocating a channel or
 226  * when the channel consumer/producer is ready, e.g. shell exec'd
 227  */
 228 static void
 229 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 230     int extusage, int nonblock, int is_tty)
 231 {
 232         /* Update the maximum file descriptor value. */
 233         channel_max_fd = MAX(channel_max_fd, rfd);
 234         channel_max_fd = MAX(channel_max_fd, wfd);
 235         channel_max_fd = MAX(channel_max_fd, efd);
 236
 237         /* XXX set close-on-exec -markus */
 238
 239         c->rfd = rfd;
 240         c->wfd = wfd;
 241         c->sock = (rfd == wfd) ? rfd : -1;
 242         c->ctl_fd = -1; /* XXX: set elsewhere */
 243         c->efd = efd;
 244         c->extended_usage = extusage;
 245
 246         if ((c->isatty = is_tty) != 0)
 247                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 248         c->wfd_isatty = is_tty || isatty(c->wfd);
 249
 250         /* enable nonblocking mode */
 251         if (nonblock) {
 252                 if (rfd != -1)
 253                         set_nonblock(rfd);
 254                 if (wfd != -1)
 255                         set_nonblock(wfd);
 256                 if (efd != -1)
 257                         set_nonblock(efd);
 258         }
 259 }
 260
 261 /*
 262  * Allocate a new channel object and set its type and socket. This will cause
 263  * remote_name to be freed.
 264  */
 265 Channel *
 266 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 267     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 268 {
 269         int found;
 270         u_int i;
 271         Channel *c;
 272
 273         /* Do initial allocation if this is the first call. */
 274         if (channels_alloc == 0) {
 275                 channels_alloc = 10;
 276                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 277                 for (i = 0; i < channels_alloc; i++)
 278                         channels[i] = NULL;
 279         }
 280         /* Try to find a free slot where to put the new channel. */
 281         for (found = -1, i = 0; i < channels_alloc; i++)
 282                 if (channels[i] == NULL) {
 283                         /* Found a free slot. */
 284                         found = (int)i;
 285                         break;
 286                 }
 287         if (found < 0) {
 288                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 289                 found = channels_alloc;
 290                 if (channels_alloc > 10000)
 291                         fatal("channel_new: internal error: channels_alloc %d "
 292                             "too big.", channels_alloc);
 293                 channels = xrealloc(channels, channels_alloc + 10,
 294                     sizeof(Channel *));
 295                 channels_alloc += 10;
 296                 debug2("channel: expanding %d", channels_alloc);
 297                 for (i = found; i < channels_alloc; i++)
 298                         channels[i] = NULL;
 299         }
 300         /* Initialize and return new channel. */
 301         c = channels[found] = xcalloc(1, sizeof(Channel));
 302         buffer_init(&c->input);
 303         buffer_init(&c->output);
 304         buffer_init(&c->extended);
 305         c->ostate = CHAN_OUTPUT_OPEN;
 306         c->istate = CHAN_INPUT_OPEN;
 307         c->flags = 0;
 308         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 309         c->self = found;
 310         c->type = type;
 311         c->ctype = ctype;
 312         c->local_window = window;
 313         c->local_window_max = window;
 314         c->local_consumed = 0;
 315         c->local_maxpacket = maxpack;
 316         c->dynamic_window = 0;
 317         c->remote_id = -1;
 318         c->remote_name = xstrdup(remote_name);
 319         c->remote_window = 0;
 320         c->remote_maxpacket = 0;
 321         c->force_drain = 0;
 322         c->single_connection = 0;
 323         c->detach_user = NULL;
 324         c->detach_close = 0;
 325         c->open_confirm = NULL;
 326         c->open_confirm_ctx = NULL;
 327         c->input_filter = NULL;
 328         c->output_filter = NULL;
 329         c->filter_ctx = NULL;
 330         c->filter_cleanup = NULL;
 331         TAILQ_INIT(&c->status_confirms);
 332         debug("channel %d: new [%s]", found, remote_name);
 333         return c;
 334 }
 335
 336 static int
 337 channel_find_maxfd(void)
 338 {
 339         u_int i;
 340         int max = 0;
 341         Channel *c;
 342
 343         for (i = 0; i < channels_alloc; i++) {
 344                 c = channels[i];
 345                 if (c != NULL) {
 346                         max = MAX(max, c->rfd);
 347                         max = MAX(max, c->wfd);
 348                         max = MAX(max, c->efd);
 349                 }
 350         }
 351         return max;
 352 }
 353
 354 int
 355 channel_close_fd(int *fdp)
 356 {
 357         int ret = 0, fd = *fdp;
 358
 359         if (fd != -1) {
 360                 ret = close(fd);
 361                 *fdp = -1;
 362                 if (fd == channel_max_fd)
 363                         channel_max_fd = channel_find_maxfd();
 364         }
 365         return ret;
 366 }
 367
 368 /* Close all channel fd/socket. */
 369 static void
 370 channel_close_fds(Channel *c)
 371 {
 372         debug3("channel %d: close_fds r %d w %d e %d c %d",
 373             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 374
 375         channel_close_fd(&c->sock);
 376         channel_close_fd(&c->ctl_fd);
 377         channel_close_fd(&c->rfd);
 378         channel_close_fd(&c->wfd);
 379         channel_close_fd(&c->efd);
 380 }
 381
 382 /* Free the channel and close its fd/socket. */
 383 void
 384 channel_free(Channel *c)
 385 {
 386         char *s;
 387         u_int i, n;
 388         struct channel_confirm *cc;
 389
 390         for (n = 0, i = 0; i < channels_alloc; i++)
 391                 if (channels[i])
 392                         n++;
 393         debug("channel %d: free: %s, nchannels %u", c->self,
 394             c->remote_name ? c->remote_name : "???", n);
 395
 396         s = channel_open_message();
 397         debug3("channel %d: status: %s", c->self, s);
 398         xfree(s);
 399
 400         if (c->sock != -1)
 401                 shutdown(c->sock, SHUT_RDWR);
 402         if (c->ctl_fd != -1)
 403                 shutdown(c->ctl_fd, SHUT_RDWR);
 404         channel_close_fds(c);
 405         buffer_free(&c->input);
 406         buffer_free(&c->output);
 407         buffer_free(&c->extended);
 408         if (c->remote_name) {
 409                 xfree(c->remote_name);
 410                 c->remote_name = NULL;
 411         }
 412         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 413                 if (cc->abandon_cb != NULL)
 414                         cc->abandon_cb(c, cc->ctx);
 415                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 416                 bzero(cc, sizeof(*cc));
 417                 xfree(cc);
 418         }
 419         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 420                 c->filter_cleanup(c->self, c->filter_ctx);
 421         channels[c->self] = NULL;
 422         xfree(c);
 423 }
 424
 425 void
 426 channel_free_all(void)
 427 {
 428         u_int i;
 429
 430         for (i = 0; i < channels_alloc; i++)
 431                 if (channels[i] != NULL)
 432                         channel_free(channels[i]);
 433 }
 434
 435 /*
 436  * Closes the sockets/fds of all channels.  This is used to close extra file
 437  * descriptors after a fork.
 438  */
 439 void
 440 channel_close_all(void)
 441 {
 442         u_int i;
 443
 444         for (i = 0; i < channels_alloc; i++)
 445                 if (channels[i] != NULL)
 446                         channel_close_fds(channels[i]);
 447 }
 448
 449 /*
 450  * Stop listening to channels.
 451  */
 452 void
 453 channel_stop_listening(void)
 454 {
 455         u_int i;
 456         Channel *c;
 457
 458         for (i = 0; i < channels_alloc; i++) {
 459                 c = channels[i];
 460                 if (c != NULL) {
 461                         switch (c->type) {
 462                         case SSH_CHANNEL_AUTH_SOCKET:
 463                         case SSH_CHANNEL_PORT_LISTENER:
 464                         case SSH_CHANNEL_RPORT_LISTENER:
 465                         case SSH_CHANNEL_X11_LISTENER:
 466                                 channel_close_fd(&c->sock);
 467                                 channel_free(c);
 468                                 break;
 469                         }
 470                 }
 471         }
 472 }
 473
 474 /*
 475  * Returns true if no channel has too much buffered data, and false if one or
 476  * more channel is overfull.
 477  */
 478 int
 479 channel_not_very_much_buffered_data(void)
 480 {
 481         u_int i;
 482         Channel *c;
 483
 484         for (i = 0; i < channels_alloc; i++) {
 485                 c = channels[i];
 486                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 487 #if 0
 488                         if (!compat20 &&
 489                             buffer_len(&c->input) > packet_get_maxsize()) {
 490                                 debug2("channel %d: big input buffer %d",
 491                                     c->self, buffer_len(&c->input));
 492                                 return 0;
 493                         }
 494 #endif
 495                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 496                                 debug2("channel %d: big output buffer %u > %u",
 497                                     c->self, buffer_len(&c->output),
 498                                     packet_get_maxsize());
 499                                 return 0;
 500                         }
 501                 }
 502         }
 503         return 1;
 504 }
 505
 506 /* Returns true if any channel is still open. */
 507 int
 508 channel_still_open(void)
 509 {
 510         u_int i;
 511         Channel *c;
 512
 513         for (i = 0; i < channels_alloc; i++) {
 514                 c = channels[i];
 515                 if (c == NULL)
 516                         continue;
 517                 switch (c->type) {
 518                 case SSH_CHANNEL_X11_LISTENER:
 519                 case SSH_CHANNEL_PORT_LISTENER:
 520                 case SSH_CHANNEL_RPORT_LISTENER:
 521                 case SSH_CHANNEL_CLOSED:
 522                 case SSH_CHANNEL_AUTH_SOCKET:
 523                 case SSH_CHANNEL_DYNAMIC:
 524                 case SSH_CHANNEL_CONNECTING:
 525                 case SSH_CHANNEL_ZOMBIE:
 526                         continue;
 527                 case SSH_CHANNEL_LARVAL:
 528                         if (!compat20)
 529                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 530                         continue;
 531                 case SSH_CHANNEL_OPENING:
 532                 case SSH_CHANNEL_OPEN:
 533                 case SSH_CHANNEL_X11_OPEN:
 534                         return 1;
 535                 case SSH_CHANNEL_INPUT_DRAINING:
 536                 case SSH_CHANNEL_OUTPUT_DRAINING:
 537                         if (!compat13)
 538                                 fatal("cannot happen: OUT_DRAIN");
 539                         return 1;
 540                 default:
 541                         fatal("channel_still_open: bad channel type %d", c->type);
 542                         /* NOTREACHED */
 543                 }
 544         }
 545         return 0;
 546 }
 547
 548 /* Returns the id of an open channel suitable for keepaliving */
 549 int
 550 channel_find_open(void)
 551 {
 552         u_int i;
 553         Channel *c;
 554
 555         for (i = 0; i < channels_alloc; i++) {
 556                 c = channels[i];
 557                 if (c == NULL || c->remote_id < 0)
 558                         continue;
 559                 switch (c->type) {
 560                 case SSH_CHANNEL_CLOSED:
 561                 case SSH_CHANNEL_DYNAMIC:
 562                 case SSH_CHANNEL_X11_LISTENER:
 563                 case SSH_CHANNEL_PORT_LISTENER:
 564                 case SSH_CHANNEL_RPORT_LISTENER:
 565                 case SSH_CHANNEL_OPENING:
 566                 case SSH_CHANNEL_CONNECTING:
 567                 case SSH_CHANNEL_ZOMBIE:
 568                         continue;
 569                 case SSH_CHANNEL_LARVAL:
 570                 case SSH_CHANNEL_AUTH_SOCKET:
 571                 case SSH_CHANNEL_OPEN:
 572                 case SSH_CHANNEL_X11_OPEN:
 573                         return i;
 574                 case SSH_CHANNEL_INPUT_DRAINING:
 575                 case SSH_CHANNEL_OUTPUT_DRAINING:
 576                         if (!compat13)
 577                                 fatal("cannot happen: OUT_DRAIN");
 578                         return i;
 579                 default:
 580                         fatal("channel_find_open: bad channel type %d", c->type);
 581                         /* NOTREACHED */
 582                 }
 583         }
 584         return -1;
 585 }
 586
 587
 588 /*
 589  * Returns a message describing the currently open forwarded connections,
 590  * suitable for sending to the client.  The message contains crlf pairs for
 591  * newlines.
 592  */
 593 char *
 594 channel_open_message(void)
 595 {
 596         Buffer buffer;
 597         Channel *c;
 598         char buf[1024], *cp;
 599         u_int i;
 600
 601         buffer_init(&buffer);
 602         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 603         buffer_append(&buffer, buf, strlen(buf));
 604         for (i = 0; i < channels_alloc; i++) {
 605                 c = channels[i];
 606                 if (c == NULL)
 607                         continue;
 608                 switch (c->type) {
 609                 case SSH_CHANNEL_X11_LISTENER:
 610                 case SSH_CHANNEL_PORT_LISTENER:
 611                 case SSH_CHANNEL_RPORT_LISTENER:
 612                 case SSH_CHANNEL_CLOSED:
 613                 case SSH_CHANNEL_AUTH_SOCKET:
 614                 case SSH_CHANNEL_ZOMBIE:
 615                         continue;
 616                 case SSH_CHANNEL_LARVAL:
 617                 case SSH_CHANNEL_OPENING:
 618                 case SSH_CHANNEL_CONNECTING:
 619                 case SSH_CHANNEL_DYNAMIC:
 620                 case SSH_CHANNEL_OPEN:
 621                 case SSH_CHANNEL_X11_OPEN:
 622                 case SSH_CHANNEL_INPUT_DRAINING:
 623                 case SSH_CHANNEL_OUTPUT_DRAINING:
 624                         snprintf(buf, sizeof buf,
 625                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 626                             c->self, c->remote_name,
 627                             c->type, c->remote_id,
 628                             c->istate, buffer_len(&c->input),
 629                             c->ostate, buffer_len(&c->output),
 630                             c->rfd, c->wfd, c->ctl_fd);
 631                         buffer_append(&buffer, buf, strlen(buf));
 632                         continue;
 633                 default:
 634                         fatal("channel_open_message: bad channel type %d", c->type);
 635                         /* NOTREACHED */
 636                 }
 637         }
 638         buffer_append(&buffer, "\0", 1);
 639         cp = xstrdup(buffer_ptr(&buffer));
 640         buffer_free(&buffer);
 641         return cp;
 642 }
 643
 644 void
 645 channel_send_open(int id)
 646 {
 647         Channel *c = channel_lookup(id);
 648
 649         if (c == NULL) {
 650                 logit("channel_send_open: %d: bad id", id);
 651                 return;
 652         }
 653         debug2("channel %d: send open", id);
 654         packet_start(SSH2_MSG_CHANNEL_OPEN);
 655         packet_put_cstring(c->ctype);
 656         packet_put_int(c->self);
 657         packet_put_int(c->local_window);
 658         packet_put_int(c->local_maxpacket);
 659         packet_send();
 660 }
 661
 662 void
 663 channel_request_start(int id, char *service, int wantconfirm)
 664 {
 665         Channel *c = channel_lookup(id);
 666
 667         if (c == NULL) {
 668                 logit("channel_request_start: %d: unknown channel id", id);
 669                 return;
 670         }
 671         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 672         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 673         packet_put_int(c->remote_id);
 674         packet_put_cstring(service);
 675         packet_put_char(wantconfirm);
 676 }
 677
 678 void
 679 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 680     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 681 {
 682         struct channel_confirm *cc;
 683         Channel *c;
 684
 685         if ((c = channel_lookup(id)) == NULL)
 686                 fatal("channel_register_expect: %d: bad id", id);
 687
 688         cc = xmalloc(sizeof(*cc));
 689         cc->cb = cb;
 690         cc->abandon_cb = abandon_cb;
 691         cc->ctx = ctx;
 692         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 693 }
 694
 695 void
 696 channel_register_open_confirm(int id, channel_callback_fn *fn, void *ctx)
 697 {
 698         Channel *c = channel_lookup(id);
 699
 700         if (c == NULL) {
 701                 logit("channel_register_open_comfirm: %d: bad id", id);
 702                 return;
 703         }
 704         c->open_confirm = fn;
 705         c->open_confirm_ctx = ctx;
 706 }
 707
 708 void
 709 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 710 {
 711         Channel *c = channel_by_id(id);
 712
 713         if (c == NULL) {
 714                 logit("channel_register_cleanup: %d: bad id", id);
 715                 return;
 716         }
 717         c->detach_user = fn;
 718         c->detach_close = do_close;
 719 }
 720
 721 void
 722 channel_cancel_cleanup(int id)
 723 {
 724         Channel *c = channel_by_id(id);
 725
 726         if (c == NULL) {
 727                 logit("channel_cancel_cleanup: %d: bad id", id);
 728                 return;
 729         }
 730         c->detach_user = NULL;
 731         c->detach_close = 0;
 732 }
 733
 734 void
 735 channel_register_filter(int id, channel_infilter_fn *ifn,
 736     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 737 {
 738         Channel *c = channel_lookup(id);
 739
 740         if (c == NULL) {
 741                 logit("channel_register_filter: %d: bad id", id);
 742                 return;
 743         }
 744         c->input_filter = ifn;
 745         c->output_filter = ofn;
 746         c->filter_ctx = ctx;
 747         c->filter_cleanup = cfn;
 748 }
 749
 750 void
 751 channel_set_fds(int id, int rfd, int wfd, int efd,
 752     int extusage, int nonblock, int is_tty, u_int window_max)
 753 {
 754         Channel *c = channel_lookup(id);
 755
 756         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 757                 fatal("channel_activate for non-larval channel %d.", id);
 758         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 759         c->type = SSH_CHANNEL_OPEN;
 760         c->local_window = c->local_window_max = window_max;
 761         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 762         packet_put_int(c->remote_id);
 763         packet_put_int(c->local_window);
 764         packet_send();
 765 }
 766
 767 /*
 768  * 'channel_pre*' are called just before select() to add any bits relevant to
 769  * channels in the select bitmasks.
 770  */
 771 /*
 772  * 'channel_post*': perform any appropriate operations for channels which
 773  * have events pending.
 774  */
 775 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 776 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 777 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 778
 779 /* ARGSUSED */
 780 static void
 781 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 782 {
 783         FD_SET(c->sock, readset);
 784 }
 785
 786 /* ARGSUSED */
 787 static void
 788 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 789 {
 790         debug3("channel %d: waiting for connection", c->self);
 791         FD_SET(c->sock, writeset);
 792 }
 793
 794 static void
 795 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 796 {
 797         if (buffer_len(&c->input) < packet_get_maxsize())
 798                 FD_SET(c->sock, readset);
 799         if (buffer_len(&c->output) > 0)
 800                 FD_SET(c->sock, writeset);
 801 }
 802
 803 int channel_tcpwinsz () {
 804         u_int32_t tcpwinsz = 0;
 805         socklen_t optsz = sizeof(tcpwinsz);
 806         int ret = -1;
 807
 808         /* if we aren't on a socket return 128KB*/
 809         if(!packet_connection_is_on_socket())
 810             return(128*1024);
 811         ret = getsockopt(packet_get_connection_in(),
 812                          SOL_SOCKET, SO_RCVBUF, &tcpwinsz, &optsz);
 813         /* return no more than 64MB */
 814         if ((ret == 0) && tcpwinsz > BUFFER_MAX_LEN_HPN)
 815             tcpwinsz = BUFFER_MAX_LEN_HPN;
 816         debug2("tcpwinsz: %d for connection: %d", tcpwinsz,
 817                packet_get_connection_in());
 818         return(tcpwinsz);
 819 }
 820
 821 static void
 822 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 823 {
 824         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 825
 826         /* check buffer limits */
 827         if ((!c->tcpwinsz) || (c->dynamic_window > 0))
 828             c->tcpwinsz = channel_tcpwinsz();
 829
 830         limit = MIN(limit, 2 * c->tcpwinsz);
 831
 832         if (c->istate == CHAN_INPUT_OPEN &&
 833             limit > 0 &&
 834             buffer_len(&c->input) < limit &&
 835             buffer_check_alloc(&c->input, CHAN_RBUF))
 836                 FD_SET(c->rfd, readset);
 837         if (c->ostate == CHAN_OUTPUT_OPEN ||
 838             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 839                 if (buffer_len(&c->output) > 0) {
 840                         FD_SET(c->wfd, writeset);
 841                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 842                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 843                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 844                                     c->self, c->efd, buffer_len(&c->extended));
 845                         else
 846                                 chan_obuf_empty(c);
 847                 }
 848         }
 849         /** XXX check close conditions, too */
 850         if (compat20 && c->efd != -1 &&
 851             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 852                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 853                     buffer_len(&c->extended) > 0)
 854                         FD_SET(c->efd, writeset);
 855                 else if (!(c->flags & CHAN_EOF_SENT) &&
 856                     c->extended_usage == CHAN_EXTENDED_READ &&
 857                     buffer_len(&c->extended) < c->remote_window)
 858                         FD_SET(c->efd, readset);
 859         }
 860         /* XXX: What about efd? races? */
 861         if (compat20 && c->ctl_fd != -1 &&
 862             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 863                 FD_SET(c->ctl_fd, readset);
 864 }
 865
 866 /* ARGSUSED */
 867 static void
 868 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 869 {
 870         if (buffer_len(&c->input) == 0) {
 871                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 872                 packet_put_int(c->remote_id);
 873                 packet_send();
 874                 c->type = SSH_CHANNEL_CLOSED;
 875                 debug2("channel %d: closing after input drain.", c->self);
 876         }
 877 }
 878
 879 /* ARGSUSED */
 880 static void
 881 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 882 {
 883         if (buffer_len(&c->output) == 0)
 884                 chan_mark_dead(c);
 885         else
 886                 FD_SET(c->sock, writeset);
 887 }
 888
 889 /*
 890  * This is a special state for X11 authentication spoofing.  An opened X11
 891  * connection (when authentication spoofing is being done) remains in this
 892  * state until the first packet has been completely read.  The authentication
 893  * data in that packet is then substituted by the real data if it matches the
 894  * fake data, and the channel is put into normal mode.
 895  * XXX All this happens at the client side.
 896  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 897  */
 898 static int
 899 x11_open_helper(Buffer *b)
 900 {
 901         u_char *ucp;
 902         u_int proto_len, data_len;
 903
 904         /* Check if the fixed size part of the packet is in buffer. */
 905         if (buffer_len(b) < 12)
 906                 return 0;
 907
 908         /* Parse the lengths of variable-length fields. */
 909         ucp = buffer_ptr(b);
 910         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 911                 proto_len = 256 * ucp[6] + ucp[7];
 912                 data_len = 256 * ucp[8] + ucp[9];
 913         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 914                 proto_len = ucp[6] + 256 * ucp[7];
 915                 data_len = ucp[8] + 256 * ucp[9];
 916         } else {
 917                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 918                     ucp[0]);
 919                 return -1;
 920         }
 921
 922         /* Check if the whole packet is in buffer. */
 923         if (buffer_len(b) <
 924             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 925                 return 0;
 926
 927         /* Check if authentication protocol matches. */
 928         if (proto_len != strlen(x11_saved_proto) ||
 929             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 930                 debug2("X11 connection uses different authentication protocol.");
 931                 return -1;
 932         }
 933         /* Check if authentication data matches our fake data. */
 934         if (data_len != x11_fake_data_len ||
 935             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 936                 x11_fake_data, x11_fake_data_len) != 0) {
 937                 debug2("X11 auth data does not match fake data.");
 938                 return -1;
 939         }
 940         /* Check fake data length */
 941         if (x11_fake_data_len != x11_saved_data_len) {
 942                 error("X11 fake_data_len %d != saved_data_len %d",
 943                     x11_fake_data_len, x11_saved_data_len);
 944                 return -1;
 945         }
 946         /*
 947          * Received authentication protocol and data match
 948          * our fake data. Substitute the fake data with real
 949          * data.
 950          */
 951         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 952             x11_saved_data, x11_saved_data_len);
 953         return 1;
 954 }
 955
 956 static void
 957 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 958 {
 959         int ret = x11_open_helper(&c->output);
 960
 961         if (ret == 1) {
 962                 /* Start normal processing for the channel. */
 963                 c->type = SSH_CHANNEL_OPEN;
 964                 channel_pre_open_13(c, readset, writeset);
 965         } else if (ret == -1) {
 966                 /*
 967                  * We have received an X11 connection that has bad
 968                  * authentication information.
 969                  */
 970                 logit("X11 connection rejected because of wrong authentication.");
 971                 buffer_clear(&c->input);
 972                 buffer_clear(&c->output);
 973                 channel_close_fd(&c->sock);
 974                 c->sock = -1;
 975                 c->type = SSH_CHANNEL_CLOSED;
 976                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 977                 packet_put_int(c->remote_id);
 978                 packet_send();
 979         }
 980 }
 981
 982 static void
 983 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 984 {
 985         int ret = x11_open_helper(&c->output);
 986
 987         /* c->force_drain = 1; */
 988
 989         if (ret == 1) {
 990                 c->type = SSH_CHANNEL_OPEN;
 991                 channel_pre_open(c, readset, writeset);
 992         } else if (ret == -1) {
 993                 logit("X11 connection rejected because of wrong authentication.");
 994                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 995                 chan_read_failed(c);
 996                 buffer_clear(&c->input);
 997                 chan_ibuf_empty(c);
 998                 buffer_clear(&c->output);
 999                 /* for proto v1, the peer will send an IEOF */
1000                 if (compat20)
1001                         chan_write_failed(c);
1002                 else
1003                         c->type = SSH_CHANNEL_OPEN;
1004                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
1005         }
1006 }
1007
1008 /* try to decode a socks4 header */
1009 /* ARGSUSED */
1010 static int
1011 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1012 {
1013         char *p, *host;
1014         u_int len, have, i, found;
1015         char username[256];
1016         struct {
1017                 u_int8_t version;
1018                 u_int8_t command;
1019                 u_int16_t dest_port;
1020                 struct in_addr dest_addr;
1021         } s4_req, s4_rsp;
1022
1023         debug2("channel %d: decode socks4", c->self);
1024
1025         have = buffer_len(&c->input);
1026         len = sizeof(s4_req);
1027         if (have < len)
1028                 return 0;
1029         p = buffer_ptr(&c->input);
1030         for (found = 0, i = len; i < have; i++) {
1031                 if (p[i] == '\0') {
1032                         found = 1;
1033                         break;
1034                 }
1035                 if (i > 1024) {
1036                         /* the peer is probably sending garbage */
1037                         debug("channel %d: decode socks4: too long",
1038                             c->self);
1039                         return -1;
1040                 }
1041         }
1042         if (!found)
1043                 return 0;
1044         buffer_get(&c->input, (char *)&s4_req.version, 1);
1045         buffer_get(&c->input, (char *)&s4_req.command, 1);
1046         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1047         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1048         have = buffer_len(&c->input);
1049         p = buffer_ptr(&c->input);
1050         len = strlen(p);
1051         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1052         if (len > have)
1053                 fatal("channel %d: decode socks4: len %d > have %d",
1054                     c->self, len, have);
1055         strlcpy(username, p, sizeof(username));
1056         buffer_consume(&c->input, len);
1057         buffer_consume(&c->input, 1);           /* trailing '\0' */
1058
1059         host = inet_ntoa(s4_req.dest_addr);
1060         strlcpy(c->path, host, sizeof(c->path));
1061         c->host_port = ntohs(s4_req.dest_port);
1062
1063         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1064             c->self, host, c->host_port, s4_req.command);
1065
1066         if (s4_req.command != 1) {
1067                 debug("channel %d: cannot handle: socks4 cn %d",
1068                     c->self, s4_req.command);
1069                 return -1;
1070         }
1071         s4_rsp.version = 0;                     /* vn: 0 for reply */
1072         s4_rsp.command = 90;                    /* cd: req granted */
1073         s4_rsp.dest_port = 0;                   /* ignored */
1074         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1075         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1076         return 1;
1077 }
1078
1079 /* try to decode a socks5 header */
1080 #define SSH_SOCKS5_AUTHDONE     0x1000
1081 #define SSH_SOCKS5_NOAUTH       0x00
1082 #define SSH_SOCKS5_IPV4         0x01
1083 #define SSH_SOCKS5_DOMAIN       0x03
1084 #define SSH_SOCKS5_IPV6         0x04
1085 #define SSH_SOCKS5_CONNECT      0x01
1086 #define SSH_SOCKS5_SUCCESS      0x00
1087
1088 /* ARGSUSED */
1089 static int
1090 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1091 {
1092         struct {
1093                 u_int8_t version;
1094                 u_int8_t command;
1095                 u_int8_t reserved;
1096                 u_int8_t atyp;
1097         } s5_req, s5_rsp;
1098         u_int16_t dest_port;
1099         u_char *p, dest_addr[255+1];
1100         u_int have, need, i, found, nmethods, addrlen, af;
1101
1102         debug2("channel %d: decode socks5", c->self);
1103         p = buffer_ptr(&c->input);
1104         if (p[0] != 0x05)
1105                 return -1;
1106         have = buffer_len(&c->input);
1107         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1108                 /* format: ver | nmethods | methods */
1109                 if (have < 2)
1110                         return 0;
1111                 nmethods = p[1];
1112                 if (have < nmethods + 2)
1113                         return 0;
1114                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1115                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1116                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1117                                 found = 1;
1118                                 break;
1119                         }
1120                 }
1121                 if (!found) {
1122                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1123                             c->self);
1124                         return -1;
1125                 }
1126                 buffer_consume(&c->input, nmethods + 2);
1127                 buffer_put_char(&c->output, 0x05);              /* version */
1128                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1129                 FD_SET(c->sock, writeset);
1130                 c->flags |= SSH_SOCKS5_AUTHDONE;
1131                 debug2("channel %d: socks5 auth done", c->self);
1132                 return 0;                               /* need more */
1133         }
1134         debug2("channel %d: socks5 post auth", c->self);
1135         if (have < sizeof(s5_req)+1)
1136                 return 0;                       /* need more */
1137         memcpy(&s5_req, p, sizeof(s5_req));
1138         if (s5_req.version != 0x05 ||
1139             s5_req.command != SSH_SOCKS5_CONNECT ||
1140             s5_req.reserved != 0x00) {
1141                 debug2("channel %d: only socks5 connect supported", c->self);
1142                 return -1;
1143         }
1144         switch (s5_req.atyp){
1145         case SSH_SOCKS5_IPV4:
1146                 addrlen = 4;
1147                 af = AF_INET;
1148                 break;
1149         case SSH_SOCKS5_DOMAIN:
1150                 addrlen = p[sizeof(s5_req)];
1151                 af = -1;
1152                 break;
1153         case SSH_SOCKS5_IPV6:
1154                 addrlen = 16;
1155                 af = AF_INET6;
1156                 break;
1157         default:
1158                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1159                 return -1;
1160         }
1161         need = sizeof(s5_req) + addrlen + 2;
1162         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1163                 need++;
1164         if (have < need)
1165                 return 0;
1166         buffer_consume(&c->input, sizeof(s5_req));
1167         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1168                 buffer_consume(&c->input, 1);    /* host string length */
1169         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1170         buffer_get(&c->input, (char *)&dest_port, 2);
1171         dest_addr[addrlen] = '\0';
1172         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1173                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1174         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1175                 return -1;
1176         c->host_port = ntohs(dest_port);
1177
1178         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1179             c->self, c->path, c->host_port, s5_req.command);
1180
1181         s5_rsp.version = 0x05;
1182         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1183         s5_rsp.reserved = 0;                    /* ignored */
1184         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1185         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1186         dest_port = 0;                          /* ignored */
1187
1188         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1189         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1190         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1191         return 1;
1192 }
1193
1194 /* dynamic port forwarding */
1195 static void
1196 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1197 {
1198         u_char *p;
1199         u_int have;
1200         int ret;
1201
1202         have = buffer_len(&c->input);
1203         c->delayed = 0;
1204         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1205         /* buffer_dump(&c->input); */
1206         /* check if the fixed size part of the packet is in buffer. */
1207         if (have < 3) {
1208                 /* need more */
1209                 FD_SET(c->sock, readset);
1210                 return;
1211         }
1212         /* try to guess the protocol */
1213         p = buffer_ptr(&c->input);
1214         switch (p[0]) {
1215         case 0x04:
1216                 ret = channel_decode_socks4(c, readset, writeset);
1217                 break;
1218         case 0x05:
1219                 ret = channel_decode_socks5(c, readset, writeset);
1220                 break;
1221         default:
1222                 ret = -1;
1223                 break;
1224         }
1225         if (ret < 0) {
1226                 chan_mark_dead(c);
1227         } else if (ret == 0) {
1228                 debug2("channel %d: pre_dynamic: need more", c->self);
1229                 /* need more */
1230                 FD_SET(c->sock, readset);
1231         } else {
1232                 /* switch to the next state */
1233                 c->type = SSH_CHANNEL_OPENING;
1234                 port_open_helper(c, "direct-tcpip");
1235         }
1236 }
1237
1238 /* This is our fake X11 server socket. */
1239 /* ARGSUSED */
1240 static void
1241 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1242 {
1243         Channel *nc;
1244         struct sockaddr_storage addr;
1245         int newsock;
1246         socklen_t addrlen;
1247         char buf[16384], *remote_ipaddr;
1248         int remote_port;
1249
1250         if (FD_ISSET(c->sock, readset)) {
1251                 debug("X11 connection requested.");
1252                 addrlen = sizeof(addr);
1253                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1254                 if (c->single_connection) {
1255                         debug2("single_connection: closing X11 listener.");
1256                         channel_close_fd(&c->sock);
1257                         chan_mark_dead(c);
1258                 }
1259                 if (newsock < 0) {
1260                         error("accept: %.100s", strerror(errno));
1261                         return;
1262                 }
1263                 set_nodelay(newsock);
1264                 remote_ipaddr = get_peer_ipaddr(newsock);
1265                 remote_port = get_peer_port(newsock);
1266                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1267                     remote_ipaddr, remote_port);
1268
1269                 nc = channel_new("accepted x11 socket",
1270                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1271                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1272                 if (compat20) {
1273                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1274                         packet_put_cstring("x11");
1275                         packet_put_int(nc->self);
1276                         packet_put_int(nc->local_window_max);
1277                         packet_put_int(nc->local_maxpacket);
1278                         /* originator ipaddr and port */
1279                         packet_put_cstring(remote_ipaddr);
1280                         if (datafellows & SSH_BUG_X11FWD) {
1281                                 debug2("ssh2 x11 bug compat mode");
1282                         } else {
1283                                 packet_put_int(remote_port);
1284                         }
1285                         packet_send();
1286                 } else {
1287                         packet_start(SSH_SMSG_X11_OPEN);
1288                         packet_put_int(nc->self);
1289                         if (packet_get_protocol_flags() &
1290                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1291                                 packet_put_cstring(buf);
1292                         packet_send();
1293                 }
1294                 xfree(remote_ipaddr);
1295         }
1296 }
1297
1298 static void
1299 port_open_helper(Channel *c, char *rtype)
1300 {
1301         int direct;
1302         char buf[1024];
1303         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1304         int remote_port = get_peer_port(c->sock);
1305
1306         direct = (strcmp(rtype, "direct-tcpip") == 0);
1307
1308         snprintf(buf, sizeof buf,
1309             "%s: listening port %d for %.100s port %d, "
1310             "connect from %.200s port %d",
1311             rtype, c->listening_port, c->path, c->host_port,
1312             remote_ipaddr, remote_port);
1313
1314         xfree(c->remote_name);
1315         c->remote_name = xstrdup(buf);
1316
1317         if (compat20) {
1318                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1319                 packet_put_cstring(rtype);
1320                 packet_put_int(c->self);
1321                 packet_put_int(c->local_window_max);
1322                 packet_put_int(c->local_maxpacket);
1323                 if (direct) {
1324                         /* target host, port */
1325                         packet_put_cstring(c->path);
1326                         packet_put_int(c->host_port);
1327                 } else {
1328                         /* listen address, port */
1329                         packet_put_cstring(c->path);
1330                         packet_put_int(c->listening_port);
1331                 }
1332                 /* originator host and port */
1333                 packet_put_cstring(remote_ipaddr);
1334                 packet_put_int((u_int)remote_port);
1335                 packet_send();
1336         } else {
1337                 packet_start(SSH_MSG_PORT_OPEN);
1338                 packet_put_int(c->self);
1339                 packet_put_cstring(c->path);
1340                 packet_put_int(c->host_port);
1341                 if (packet_get_protocol_flags() &
1342                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1343                         packet_put_cstring(c->remote_name);
1344                 packet_send();
1345         }
1346         xfree(remote_ipaddr);
1347 }
1348
1349 static void
1350 channel_set_reuseaddr(int fd)
1351 {
1352         int on = 1;
1353
1354         /*
1355          * Set socket options.
1356          * Allow local port reuse in TIME_WAIT.
1357          */
1358         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1359                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1360 }
1361
1362 /*
1363  * This socket is listening for connections to a forwarded TCP/IP port.
1364  */
1365 /* ARGSUSED */
1366 static void
1367 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1368 {
1369         Channel *nc;
1370         struct sockaddr_storage addr;
1371         int newsock, nextstate;
1372         socklen_t addrlen;
1373         char *rtype;
1374
1375         if (FD_ISSET(c->sock, readset)) {
1376                 debug("Connection to port %d forwarding "
1377                     "to %.100s port %d requested.",
1378                     c->listening_port, c->path, c->host_port);
1379
1380                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1381                         nextstate = SSH_CHANNEL_OPENING;
1382                         rtype = "forwarded-tcpip";
1383                 } else {
1384                         if (c->host_port == 0) {
1385                                 nextstate = SSH_CHANNEL_DYNAMIC;
1386                                 rtype = "dynamic-tcpip";
1387                         } else {
1388                                 nextstate = SSH_CHANNEL_OPENING;
1389                                 rtype = "direct-tcpip";
1390                         }
1391                 }
1392
1393                 addrlen = sizeof(addr);
1394                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1395                 if (newsock < 0) {
1396                         error("accept: %.100s", strerror(errno));
1397                         return;
1398                 }
1399                 set_nodelay(newsock);
1400                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1401                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1402                 nc->listening_port = c->listening_port;
1403                 nc->host_port = c->host_port;
1404                 strlcpy(nc->path, c->path, sizeof(nc->path));
1405
1406                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1407                         /*
1408                          * do not call the channel_post handler until
1409                          * this flag has been reset by a pre-handler.
1410                          * otherwise the FD_ISSET calls might overflow
1411                          */
1412                         nc->delayed = 1;
1413                 } else {
1414                         port_open_helper(nc, rtype);
1415                 }
1416         }
1417 }
1418
1419 /*
1420  * This is the authentication agent socket listening for connections from
1421  * clients.
1422  */
1423 /* ARGSUSED */
1424 static void
1425 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1426 {
1427         Channel *nc;
1428         int newsock;
1429         struct sockaddr_storage addr;
1430         socklen_t addrlen;
1431
1432         if (FD_ISSET(c->sock, readset)) {
1433                 addrlen = sizeof(addr);
1434                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1435                 if (newsock < 0) {
1436                         error("accept from auth socket: %.100s", strerror(errno));
1437                         return;
1438                 }
1439                 nc = channel_new("accepted auth socket",
1440                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1441                     c->local_window_max, c->local_maxpacket,
1442                     0, "accepted auth socket", 1);
1443                 if (compat20) {
1444                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1445                         packet_put_cstring("auth-agent@openssh.com");
1446                         packet_put_int(nc->self);
1447                         packet_put_int(c->local_window_max);
1448                         packet_put_int(c->local_maxpacket);
1449                 } else {
1450                         packet_start(SSH_SMSG_AGENT_OPEN);
1451                         packet_put_int(nc->self);
1452                 }
1453                 packet_send();
1454         }
1455 }
1456
1457 /* ARGSUSED */
1458 static void
1459 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1460 {
1461         int err = 0, sock;
1462         socklen_t sz = sizeof(err);
1463
1464         if (FD_ISSET(c->sock, writeset)) {
1465                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1466                         err = errno;
1467                         error("getsockopt SO_ERROR failed");
1468                 }
1469                 if (err == 0) {
1470                         debug("channel %d: connected to %s port %d",
1471                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1472                         channel_connect_ctx_free(&c->connect_ctx);
1473                         c->type = SSH_CHANNEL_OPEN;
1474                         if (compat20) {
1475                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1476                                 packet_put_int(c->remote_id);
1477                                 packet_put_int(c->self);
1478                                 packet_put_int(c->local_window);
1479                                 packet_put_int(c->local_maxpacket);
1480                         } else {
1481                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1482                                 packet_put_int(c->remote_id);
1483                                 packet_put_int(c->self);
1484                         }
1485                 } else {
1486                         debug("channel %d: connection failed: %s",
1487                             c->self, strerror(err));
1488                         /* Try next address, if any */
1489                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1490                                 close(c->sock);
1491                                 c->sock = c->rfd = c->wfd = sock;
1492                                 channel_max_fd = channel_find_maxfd();
1493                                 return;
1494                         }
1495                         /* Exhausted all addresses */
1496                         error("connect_to %.100s port %d: failed.",
1497                             c->connect_ctx.host, c->connect_ctx.port);
1498                         channel_connect_ctx_free(&c->connect_ctx);
1499                         if (compat20) {
1500                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1501                                 packet_put_int(c->remote_id);
1502                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1503                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1504                                         packet_put_cstring(strerror(err));
1505                                         packet_put_cstring("");
1506                                 }
1507                         } else {
1508                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1509                                 packet_put_int(c->remote_id);
1510                         }
1511                         chan_mark_dead(c);
1512                 }
1513                 packet_send();
1514         }
1515 }
1516
1517 /* ARGSUSED */
1518 static int
1519 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1520 {
1521         char buf[CHAN_RBUF];
1522         int len, force;
1523
1524         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1525         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1526                 errno = 0;
1527                 len = read(c->rfd, buf, sizeof(buf));
1528                 if (len < 0 && (errno == EINTR ||
1529                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1530                         return 1;
1531 #ifndef PTY_ZEROREAD
1532                 if (len <= 0) {
1533 #else
1534                 if ((!c->isatty && len <= 0) ||
1535                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1536 #endif
1537                         debug2("channel %d: read<=0 rfd %d len %d",
1538                             c->self, c->rfd, len);
1539                         if (c->type != SSH_CHANNEL_OPEN) {
1540                                 debug2("channel %d: not open", c->self);
1541                                 chan_mark_dead(c);
1542                                 return -1;
1543                         } else if (compat13) {
1544                                 buffer_clear(&c->output);
1545                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1546                                 debug2("channel %d: input draining.", c->self);
1547                         } else {
1548                                 chan_read_failed(c);
1549                         }
1550                         return -1;
1551                 }
1552                 if (c->input_filter != NULL) {
1553                         if (c->input_filter(c, buf, len) == -1) {
1554                                 debug2("channel %d: filter stops", c->self);
1555                                 chan_read_failed(c);
1556                         }
1557                 } else if (c->datagram) {
1558                         buffer_put_string(&c->input, buf, len);
1559                 } else {
1560                         buffer_append(&c->input, buf, len);
1561                 }
1562         }
1563         return 1;
1564 }
1565
1566 /* ARGSUSED */
1567 static int
1568 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1569 {
1570         struct termios tio;
1571         u_char *data = NULL, *buf;
1572         u_int dlen;
1573         int len;
1574
1575         /* Send buffered output data to the socket. */
1576         if (c->wfd != -1 &&
1577             FD_ISSET(c->wfd, writeset) &&
1578             buffer_len(&c->output) > 0) {
1579                 if (c->output_filter != NULL) {
1580                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1581                                 debug2("channel %d: filter stops", c->self);
1582                                 if (c->type != SSH_CHANNEL_OPEN)
1583                                         chan_mark_dead(c);
1584                                 else
1585                                         chan_write_failed(c);
1586                                 return -1;
1587                         }
1588                 } else if (c->datagram) {
1589                         buf = data = buffer_get_string(&c->output, &dlen);
1590                 } else {
1591                         buf = data = buffer_ptr(&c->output);
1592                         dlen = buffer_len(&c->output);
1593                 }
1594
1595                 if (c->datagram) {
1596                         /* ignore truncated writes, datagrams might get lost */
1597                         c->local_consumed += dlen + 4;
1598                         len = write(c->wfd, buf, dlen);
1599                         xfree(data);
1600                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1601                             errno == EWOULDBLOCK))
1602                                 return 1;
1603                         if (len <= 0) {
1604                                 if (c->type != SSH_CHANNEL_OPEN)
1605                                         chan_mark_dead(c);
1606                                 else
1607                                         chan_write_failed(c);
1608                                 return -1;
1609                         }
1610                         return 1;
1611                 }
1612 #ifdef _AIX
1613                 /* XXX: Later AIX versions can't push as much data to tty */
1614                 if (compat20 && c->wfd_isatty)
1615                         dlen = MIN(dlen, 8*1024);
1616 #endif
1617
1618                 len = write(c->wfd, buf, dlen);
1619                 if (len < 0 &&
1620                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1621                         return 1;
1622                 if (len <= 0) {
1623                         if (c->type != SSH_CHANNEL_OPEN) {
1624                                 debug2("channel %d: not open", c->self);
1625                                 chan_mark_dead(c);
1626                                 return -1;
1627                         } else if (compat13) {
1628                                 buffer_clear(&c->output);
1629                                 debug2("channel %d: input draining.", c->self);
1630                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1631                         } else {
1632                                 chan_write_failed(c);
1633                         }
1634                         return -1;
1635                 }
1636                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1637                         if (tcgetattr(c->wfd, &tio) == 0 &&
1638                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1639                                 /*
1640                                  * Simulate echo to reduce the impact of
1641                                  * traffic analysis. We need to match the
1642                                  * size of a SSH2_MSG_CHANNEL_DATA message
1643                                  * (4 byte channel id + buf)
1644                                  */
1645                                 packet_send_ignore(4 + len);
1646                                 packet_send();
1647                         }
1648                 }
1649                 buffer_consume(&c->output, len);
1650                 if (compat20 && len > 0) {
1651                         c->local_consumed += len;
1652                 }
1653         }
1654         return 1;
1655 }
1656
1657 static int
1658 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1659 {
1660         char buf[CHAN_RBUF];
1661         int len;
1662
1663 /** XXX handle drain efd, too */
1664         if (c->efd != -1) {
1665                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1666                     FD_ISSET(c->efd, writeset) &&
1667                     buffer_len(&c->extended) > 0) {
1668                         len = write(c->efd, buffer_ptr(&c->extended),
1669                             buffer_len(&c->extended));
1670                         debug2("channel %d: written %d to efd %d",
1671                             c->self, len, c->efd);
1672                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1673                             errno == EWOULDBLOCK))
1674                                 return 1;
1675                         if (len <= 0) {
1676                                 debug2("channel %d: closing write-efd %d",
1677                                     c->self, c->efd);
1678                                 channel_close_fd(&c->efd);
1679                         } else {
1680                                 buffer_consume(&c->extended, len);
1681                                 c->local_consumed += len;
1682                         }
1683                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1684                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1685                         len = read(c->efd, buf, sizeof(buf));
1686                         debug2("channel %d: read %d from efd %d",
1687                             c->self, len, c->efd);
1688                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1689                             errno == EWOULDBLOCK) && !c->detach_close)))
1690                                 return 1;
1691                         if (len <= 0) {
1692                                 debug2("channel %d: closing read-efd %d",
1693                                     c->self, c->efd);
1694                                 channel_close_fd(&c->efd);
1695                         } else {
1696                                 buffer_append(&c->extended, buf, len);
1697                         }
1698                 }
1699         }
1700         return 1;
1701 }
1702
1703 /* ARGSUSED */
1704 static int
1705 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1706 {
1707         char buf[16];
1708         int len;
1709
1710         /* Monitor control fd to detect if the slave client exits */
1711         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1712                 len = read(c->ctl_fd, buf, sizeof(buf));
1713                 if (len < 0 &&
1714                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1715                         return 1;
1716                 if (len <= 0) {
1717                         debug2("channel %d: ctl read<=0", c->self);
1718                         if (c->type != SSH_CHANNEL_OPEN) {
1719                                 debug2("channel %d: not open", c->self);
1720                                 chan_mark_dead(c);
1721                                 return -1;
1722                         } else {
1723                                 chan_read_failed(c);
1724                                 chan_write_failed(c);
1725                         }
1726                         return -1;
1727                 } else
1728                         fatal("%s: unexpected data on ctl fd", __func__);
1729         }
1730         return 1;
1731 }
1732
1733 static int
1734 channel_check_window(Channel *c)
1735 {
1736         if (c->type == SSH_CHANNEL_OPEN &&
1737             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1738             ((c->local_window_max - c->local_window >
1739             c->local_maxpacket*3) ||
1740             c->local_window < c->local_window_max/2) &&
1741             c->local_consumed > 0) {
1742                 u_int addition = 0;
1743                 /* adjust max window size if we are in a dynamic environment */
1744                 if (c->dynamic_window && (c->tcpwinsz > c->local_window_max)) {
1745                         /* grow the window somewhat aggressively to maintain pressure */
1746                         addition = 1.5*(c->tcpwinsz - c->local_window_max);
1747                         c->local_window_max += addition;
1748                 }
1749                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1750                 packet_put_int(c->remote_id);
1751                 packet_put_int(c->local_consumed + addition);
1752                 packet_send();
1753                 debug2("channel %d: window %d sent adjust %d",
1754                     c->self, c->local_window,
1755                     c->local_consumed);
1756                 c->local_window += c->local_consumed + addition;
1757                 c->local_consumed = 0;
1758         }
1759         return 1;
1760 }
1761
1762 static void
1763 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1764 {
1765         if (c->delayed)
1766                 return;
1767         channel_handle_rfd(c, readset, writeset);
1768         channel_handle_wfd(c, readset, writeset);
1769         if (!compat20)
1770                 return;
1771         channel_handle_efd(c, readset, writeset);
1772         channel_handle_ctl(c, readset, writeset);
1773         channel_check_window(c);
1774 }
1775
1776 /* ARGSUSED */
1777 static void
1778 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1779 {
1780         int len;
1781
1782         /* Send buffered output data to the socket. */
1783         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1784                 len = write(c->sock, buffer_ptr(&c->output),
1785                             buffer_len(&c->output));
1786                 if (len <= 0)
1787                         buffer_clear(&c->output);
1788                 else
1789                         buffer_consume(&c->output, len);
1790         }
1791 }
1792
1793 static void
1794 channel_handler_init_20(void)
1795 {
1796         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1797         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1798         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1799         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1800         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1801         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1802         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1803         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1804
1805         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1806         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1807         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1808         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1809         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1810         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1811         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1812 }
1813
1814 static void
1815 channel_handler_init_13(void)
1816 {
1817         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1818         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1819         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1820         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1821         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1822         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1823         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1824         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1825         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1826
1827         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1828         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1829         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1830         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1831         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1832         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1833         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1834 }
1835
1836 static void
1837 channel_handler_init_15(void)
1838 {
1839         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1840         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1841         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1842         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1843         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1844         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1845         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1846
1847         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1848         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1849         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1850         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1851         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1852         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1853 }
1854
1855 static void
1856 channel_handler_init(void)
1857 {
1858         int i;
1859
1860         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1861                 channel_pre[i] = NULL;
1862                 channel_post[i] = NULL;
1863         }
1864         if (compat20)
1865                 channel_handler_init_20();
1866         else if (compat13)
1867                 channel_handler_init_13();
1868         else
1869                 channel_handler_init_15();
1870 }
1871
1872 /* gc dead channels */
1873 static void
1874 channel_garbage_collect(Channel *c)
1875 {
1876         if (c == NULL)
1877                 return;
1878         if (c->detach_user != NULL) {
1879                 if (!chan_is_dead(c, c->detach_close))
1880                         return;
1881                 debug2("channel %d: gc: notify user", c->self);
1882                 c->detach_user(c->self, NULL);
1883                 /* if we still have a callback */
1884                 if (c->detach_user != NULL)
1885                         return;
1886                 debug2("channel %d: gc: user detached", c->self);
1887         }
1888         if (!chan_is_dead(c, 1))
1889                 return;
1890         debug2("channel %d: garbage collecting", c->self);
1891         channel_free(c);
1892 }
1893
1894 static void
1895 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1896 {
1897         static int did_init = 0;
1898         u_int i;
1899         Channel *c;
1900
1901         if (!did_init) {
1902                 channel_handler_init();
1903                 did_init = 1;
1904         }
1905         for (i = 0; i < channels_alloc; i++) {
1906                 c = channels[i];
1907                 if (c == NULL)
1908                         continue;
1909                 if (ftab[c->type] != NULL)
1910                         (*ftab[c->type])(c, readset, writeset);
1911                 channel_garbage_collect(c);
1912         }
1913 }
1914
1915 /*
1916  * Allocate/update select bitmasks and add any bits relevant to channels in
1917  * select bitmasks.
1918  */
1919 void
1920 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1921     u_int *nallocp, int rekeying)
1922 {
1923         u_int n, sz, nfdset;
1924
1925         n = MAX(*maxfdp, channel_max_fd);
1926
1927         nfdset = howmany(n+1, NFDBITS);
1928         /* Explicitly test here, because xrealloc isn't always called */
1929         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1930                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1931         sz = nfdset * sizeof(fd_mask);
1932
1933         /* perhaps check sz < nalloc/2 and shrink? */
1934         if (*readsetp == NULL || sz > *nallocp) {
1935                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1936                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1937                 *nallocp = sz;
1938         }
1939         *maxfdp = n;
1940         memset(*readsetp, 0, sz);
1941         memset(*writesetp, 0, sz);
1942
1943         if (!rekeying)
1944                 channel_handler(channel_pre, *readsetp, *writesetp);
1945 }
1946
1947 /*
1948  * After select, perform any appropriate operations for channels which have
1949  * events pending.
1950  */
1951 void
1952 channel_after_select(fd_set *readset, fd_set *writeset)
1953 {
1954         channel_handler(channel_post, readset, writeset);
1955 }
1956
1957
1958 /* If there is data to send to the connection, enqueue some of it now. */
1959 int
1960 channel_output_poll(void)
1961 {
1962         Channel *c;
1963         u_int i, len;
1964         int packet_length = 0;
1965
1966         for (i = 0; i < channels_alloc; i++) {
1967                 c = channels[i];
1968                 if (c == NULL)
1969                         continue;
1970
1971                 /*
1972                  * We are only interested in channels that can have buffered
1973                  * incoming data.
1974                  */
1975                 if (compat13) {
1976                         if (c->type != SSH_CHANNEL_OPEN &&
1977                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1978                                 continue;
1979                 } else {
1980                         if (c->type != SSH_CHANNEL_OPEN)
1981                                 continue;
1982                 }
1983                 if (compat20 &&
1984                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1985                         /* XXX is this true? */
1986                         debug3("channel %d: will not send data after close", c->self);
1987                         continue;
1988                 }
1989
1990                 /* Get the amount of buffered data for this channel. */
1991                 if ((c->istate == CHAN_INPUT_OPEN ||
1992                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1993                     (len = buffer_len(&c->input)) > 0) {
1994                         if (c->datagram) {
1995                                 if (len > 0) {
1996                                         u_char *data;
1997                                         u_int dlen;
1998
1999                                         data = buffer_get_string(&c->input,
2000                                             &dlen);
2001                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2002                                         packet_put_int(c->remote_id);
2003                                         packet_put_string(data, dlen);
2004                                         packet_length = packet_send();
2005                                         c->remote_window -= dlen + 4;
2006                                         xfree(data);
2007                                 }
2008                                 continue;
2009                         }
2010                         /*
2011                          * Send some data for the other side over the secure
2012                          * connection.
2013                          */
2014                         if (compat20) {
2015                                 if (len > c->remote_window)
2016                                         len = c->remote_window;
2017                                 if (len > c->remote_maxpacket)
2018                                         len = c->remote_maxpacket;
2019                         } else {
2020                                 if (packet_is_interactive()) {
2021                                         if (len > 1024)
2022                                                 len = 512;
2023                                 } else {
2024                                         /* Keep the packets at reasonable size. */
2025                                         if (len > packet_get_maxsize()/2)
2026                                                 len = packet_get_maxsize()/2;
2027                                 }
2028                         }
2029                         if (len > 0) {
2030                                 packet_start(compat20 ?
2031                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2032                                 packet_put_int(c->remote_id);
2033                                 packet_put_string(buffer_ptr(&c->input), len);
2034                                 packet_length = packet_send();
2035                                 buffer_consume(&c->input, len);
2036                                 c->remote_window -= len;
2037                         }
2038                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2039                         if (compat13)
2040                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2041                         /*
2042                          * input-buffer is empty and read-socket shutdown:
2043                          * tell peer, that we will not send more data: send IEOF.
2044                          * hack for extended data: delay EOF if EFD still in use.
2045                          */
2046                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2047                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2048                                     c->self, c->efd, buffer_len(&c->extended));
2049                         else
2050                                 chan_ibuf_empty(c);
2051                 }
2052                 /* Send extended data, i.e. stderr */
2053                 if (compat20 &&
2054                     !(c->flags & CHAN_EOF_SENT) &&
2055                     c->remote_window > 0 &&
2056                     (len = buffer_len(&c->extended)) > 0 &&
2057                     c->extended_usage == CHAN_EXTENDED_READ) {
2058                         debug2("channel %d: rwin %u elen %u euse %d",
2059                             c->self, c->remote_window, buffer_len(&c->extended),
2060                             c->extended_usage);
2061                         if (len > c->remote_window)
2062                                 len = c->remote_window;
2063                         if (len > c->remote_maxpacket)
2064                                 len = c->remote_maxpacket;
2065                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2066                         packet_put_int(c->remote_id);
2067                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2068                         packet_put_string(buffer_ptr(&c->extended), len);
2069                         packet_length = packet_send();
2070                         buffer_consume(&c->extended, len);
2071                         c->remote_window -= len;
2072                         debug2("channel %d: sent ext data %d", c->self, len);
2073                 }
2074         }
2075         return (packet_length);
2076 }
2077
2078
2079 /* -- protocol input */
2080
2081 /* ARGSUSED */
2082 void
2083 channel_input_data(int type, u_int32_t seq, void *ctxt)
2084 {
2085         int id;
2086         char *data;
2087         u_int data_len;
2088         Channel *c;
2089
2090         /* Get the channel number and verify it. */
2091         id = packet_get_int();
2092         c = channel_lookup(id);
2093         if (c == NULL)
2094                 packet_disconnect("Received data for nonexistent channel %d.", id);
2095
2096         /* Ignore any data for non-open channels (might happen on close) */
2097         if (c->type != SSH_CHANNEL_OPEN &&
2098             c->type != SSH_CHANNEL_X11_OPEN)
2099                 return;
2100
2101         /* Get the data. */
2102         data = packet_get_string_ptr(&data_len);
2103
2104         /*
2105          * Ignore data for protocol > 1.3 if output end is no longer open.
2106          * For protocol 2 the sending side is reducing its window as it sends
2107          * data, so we must 'fake' consumption of the data in order to ensure
2108          * that window updates are sent back.  Otherwise the connection might
2109          * deadlock.
2110          */
2111         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2112                 if (compat20) {
2113                         c->local_window -= data_len;
2114                         c->local_consumed += data_len;
2115                 }
2116                 return;
2117         }
2118
2119         if (compat20) {
2120                 if (data_len > c->local_maxpacket) {
2121                         logit("channel %d: rcvd big packet %d, maxpack %d",
2122                             c->self, data_len, c->local_maxpacket);
2123                 }
2124                 if (data_len > c->local_window) {
2125                         logit("channel %d: rcvd too much data %d, win %d",
2126                             c->self, data_len, c->local_window);
2127                         return;
2128                 }
2129                 c->local_window -= data_len;
2130         }
2131         if (c->datagram)
2132                 buffer_put_string(&c->output, data, data_len);
2133         else
2134                 buffer_append(&c->output, data, data_len);
2135         packet_check_eom();
2136 }
2137
2138 /* ARGSUSED */
2139 void
2140 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2141 {
2142         int id;
2143         char *data;
2144         u_int data_len, tcode;
2145         Channel *c;
2146
2147         /* Get the channel number and verify it. */
2148         id = packet_get_int();
2149         c = channel_lookup(id);
2150
2151         if (c == NULL)
2152                 packet_disconnect("Received extended_data for bad channel %d.", id);
2153         if (c->type != SSH_CHANNEL_OPEN) {
2154                 logit("channel %d: ext data for non open", id);
2155                 return;
2156         }
2157         if (c->flags & CHAN_EOF_RCVD) {
2158                 if (datafellows & SSH_BUG_EXTEOF)
2159                         debug("channel %d: accepting ext data after eof", id);
2160                 else
2161                         packet_disconnect("Received extended_data after EOF "
2162                             "on channel %d.", id);
2163         }
2164         tcode = packet_get_int();
2165         if (c->efd == -1 ||
2166             c->extended_usage != CHAN_EXTENDED_WRITE ||
2167             tcode != SSH2_EXTENDED_DATA_STDERR) {
2168                 logit("channel %d: bad ext data", c->self);
2169                 return;
2170         }
2171         data = packet_get_string(&data_len);
2172         packet_check_eom();
2173         if (data_len > c->local_window) {
2174                 logit("channel %d: rcvd too much extended_data %d, win %d",
2175                     c->self, data_len, c->local_window);
2176                 xfree(data);
2177                 return;
2178         }
2179         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2180         c->local_window -= data_len;
2181         buffer_append(&c->extended, data, data_len);
2182         xfree(data);
2183 }
2184
2185 /* ARGSUSED */
2186 void
2187 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2188 {
2189         int id;
2190         Channel *c;
2191
2192         id = packet_get_int();
2193         packet_check_eom();
2194         c = channel_lookup(id);
2195         if (c == NULL)
2196                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2197         chan_rcvd_ieof(c);
2198
2199         /* XXX force input close */
2200         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2201                 debug("channel %d: FORCE input drain", c->self);
2202                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2203                 if (buffer_len(&c->input) == 0)
2204                         chan_ibuf_empty(c);
2205         }
2206
2207 }
2208
2209 /* ARGSUSED */
2210 void
2211 channel_input_close(int type, u_int32_t seq, void *ctxt)
2212 {
2213         int id;
2214         Channel *c;
2215
2216         id = packet_get_int();
2217         packet_check_eom();
2218         c = channel_lookup(id);
2219         if (c == NULL)
2220                 packet_disconnect("Received close for nonexistent channel %d.", id);
2221
2222         /*
2223          * Send a confirmation that we have closed the channel and no more
2224          * data is coming for it.
2225          */
2226         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2227         packet_put_int(c->remote_id);
2228         packet_send();
2229
2230         /*
2231          * If the channel is in closed state, we have sent a close request,
2232          * and the other side will eventually respond with a confirmation.
2233          * Thus, we cannot free the channel here, because then there would be
2234          * no-one to receive the confirmation.  The channel gets freed when
2235          * the confirmation arrives.
2236          */
2237         if (c->type != SSH_CHANNEL_CLOSED) {
2238                 /*
2239                  * Not a closed channel - mark it as draining, which will
2240                  * cause it to be freed later.
2241                  */
2242                 buffer_clear(&c->input);
2243                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2244         }
2245 }
2246
2247 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2248 /* ARGSUSED */
2249 void
2250 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2251 {
2252         int id = packet_get_int();
2253         Channel *c = channel_lookup(id);
2254
2255         packet_check_eom();
2256         if (c == NULL)
2257                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2258         chan_rcvd_oclose(c);
2259 }
2260
2261 /* ARGSUSED */
2262 void
2263 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2264 {
2265         int id = packet_get_int();
2266         Channel *c = channel_lookup(id);
2267
2268         packet_check_eom();
2269         if (c == NULL)
2270                 packet_disconnect("Received close confirmation for "
2271                     "out-of-range channel %d.", id);
2272         if (c->type != SSH_CHANNEL_CLOSED)
2273                 packet_disconnect("Received close confirmation for "
2274                     "non-closed channel %d (type %d).", id, c->type);
2275         channel_free(c);
2276 }
2277
2278 /* ARGSUSED */
2279 void
2280 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2281 {
2282         int id, remote_id;
2283         Channel *c;
2284
2285         id = packet_get_int();
2286         c = channel_lookup(id);
2287
2288         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2289                 packet_disconnect("Received open confirmation for "
2290                     "non-opening channel %d.", id);
2291         remote_id = packet_get_int();
2292         /* Record the remote channel number and mark that the channel is now open. */
2293         c->remote_id = remote_id;
2294         c->type = SSH_CHANNEL_OPEN;
2295
2296         if (compat20) {
2297                 c->remote_window = packet_get_int();
2298                 c->remote_maxpacket = packet_get_int();
2299                 if (c->open_confirm) {
2300                         debug2("callback start");
2301                         c->open_confirm(c->self, c->open_confirm_ctx);
2302                         debug2("callback done");
2303                 }
2304                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2305                     c->remote_window, c->remote_maxpacket);
2306         }
2307         packet_check_eom();
2308 }
2309
2310 static char *
2311 reason2txt(int reason)
2312 {
2313         switch (reason) {
2314         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2315                 return "administratively prohibited";
2316         case SSH2_OPEN_CONNECT_FAILED:
2317                 return "connect failed";
2318         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2319                 return "unknown channel type";
2320         case SSH2_OPEN_RESOURCE_SHORTAGE:
2321                 return "resource shortage";
2322         }
2323         return "unknown reason";
2324 }
2325
2326 /* ARGSUSED */
2327 void
2328 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2329 {
2330         int id, reason;
2331         char *msg = NULL, *lang = NULL;
2332         Channel *c;
2333
2334         id = packet_get_int();
2335         c = channel_lookup(id);
2336
2337         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2338                 packet_disconnect("Received open failure for "
2339                     "non-opening channel %d.", id);
2340         if (compat20) {
2341                 reason = packet_get_int();
2342                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2343                         msg  = packet_get_string(NULL);
2344                         lang = packet_get_string(NULL);
2345                 }
2346                 logit("channel %d: open failed: %s%s%s", id,
2347                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2348                 if (msg != NULL)
2349                         xfree(msg);
2350                 if (lang != NULL)
2351                         xfree(lang);
2352         }
2353         packet_check_eom();
2354         /* Free the channel.  This will also close the socket. */
2355         channel_free(c);
2356 }
2357
2358 /* ARGSUSED */
2359 void
2360 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2361 {
2362         Channel *c;
2363         int id;
2364         u_int adjust;
2365
2366         if (!compat20)
2367                 return;
2368
2369         /* Get the channel number and verify it. */
2370         id = packet_get_int();
2371         c = channel_lookup(id);
2372
2373         if (c == NULL) {
2374                 logit("Received window adjust for non-open channel %d.", id);
2375                 return;
2376         }
2377         adjust = packet_get_int();
2378         packet_check_eom();
2379         debug2("channel %d: rcvd adjust %u", id, adjust);
2380         c->remote_window += adjust;
2381 }
2382
2383 /* ARGSUSED */
2384 void
2385 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2386 {
2387         Channel *c = NULL;
2388         u_short host_port;
2389         char *host, *originator_string;
2390         int remote_id;
2391
2392         remote_id = packet_get_int();
2393         host = packet_get_string(NULL);
2394         host_port = packet_get_int();
2395
2396         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2397                 originator_string = packet_get_string(NULL);
2398         } else {
2399                 originator_string = xstrdup("unknown (remote did not supply name)");
2400         }
2401         packet_check_eom();
2402         c = channel_connect_to(host, host_port,
2403             "connected socket", originator_string);
2404         xfree(originator_string);
2405         xfree(host);
2406         if (c == NULL) {
2407                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2408                 packet_put_int(remote_id);
2409                 packet_send();
2410         } else
2411                 c->remote_id = remote_id;
2412 }
2413
2414 /* ARGSUSED */
2415 void
2416 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2417 {
2418         Channel *c;
2419         struct channel_confirm *cc;
2420         int remote_id;
2421
2422         /* Reset keepalive timeout */
2423         keep_alive_timeouts = 0;
2424
2425         remote_id = packet_get_int();
2426         packet_check_eom();
2427
2428         debug2("channel_input_confirm: type %d id %d", type, remote_id);
2429
2430         if ((c = channel_lookup(remote_id)) == NULL) {
2431                 logit("channel_input_success_failure: %d: unknown", remote_id);
2432                 return;
2433         }
2434         ;
2435         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2436                 return;
2437         cc->cb(type, c, cc->ctx);
2438         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2439         bzero(cc, sizeof(*cc));
2440         xfree(cc);
2441 }
2442
2443 /* -- tcp forwarding */
2444
2445 void
2446 channel_set_af(int af)
2447 {
2448         IPv4or6 = af;
2449 }
2450
2451
2452 void
2453 channel_set_hpn(int external_hpn_disabled, int external_hpn_buffer_size)
2454 {
2455         hpn_disabled = external_hpn_disabled;
2456         hpn_buffer_size = external_hpn_buffer_size;
2457         debug("HPN Disabled: %d, HPN Buffer Size: %d", hpn_disabled, hpn_buffer_size);
2458 }
2459
2460 static int
2461 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2462     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2463 {
2464         Channel *c;
2465         int sock, r, success = 0, wildcard = 0, is_client;
2466         struct addrinfo hints, *ai, *aitop;
2467         const char *host, *addr;
2468         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2469
2470         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2471             listen_addr : host_to_connect;
2472         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2473
2474         if (host == NULL) {
2475                 error("No forward host name.");
2476                 return 0;
2477         }
2478         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2479                 error("Forward host name too long.");
2480                 return 0;
2481         }
2482
2483         /*
2484          * Determine whether or not a port forward listens to loopback,
2485          * specified address or wildcard. On the client, a specified bind
2486          * address will always override gateway_ports. On the server, a
2487          * gateway_ports of 1 (``yes'') will override the client's
2488          * specification and force a wildcard bind, whereas a value of 2
2489          * (``clientspecified'') will bind to whatever address the client
2490          * asked for.
2491          *
2492          * Special-case listen_addrs are:
2493          *
2494          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2495          * "" (empty string), "*"  -> wildcard v4/v6
2496          * "localhost"             -> loopback v4/v6
2497          */
2498         addr = NULL;
2499         if (listen_addr == NULL) {
2500                 /* No address specified: default to gateway_ports setting */
2501                 if (gateway_ports)
2502                         wildcard = 1;
2503         } else if (gateway_ports || is_client) {
2504                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2505                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2506                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2507                     (!is_client && gateway_ports == 1))
2508                         wildcard = 1;
2509                 else if (strcmp(listen_addr, "localhost") != 0)
2510                         addr = listen_addr;
2511         }
2512
2513         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2514             type, wildcard, (addr == NULL) ? "NULL" : addr);
2515
2516         /*
2517          * getaddrinfo returns a loopback address if the hostname is
2518          * set to NULL and hints.ai_flags is not AI_PASSIVE
2519          */
2520         memset(&hints, 0, sizeof(hints));
2521         hints.ai_family = IPv4or6;
2522         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2523         hints.ai_socktype = SOCK_STREAM;
2524         snprintf(strport, sizeof strport, "%d", listen_port);
2525         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2526                 if (addr == NULL) {
2527                         /* This really shouldn't happen */
2528                         packet_disconnect("getaddrinfo: fatal error: %s",
2529                             ssh_gai_strerror(r));
2530                 } else {
2531                         error("channel_setup_fwd_listener: "
2532                             "getaddrinfo(%.64s): %s", addr,
2533                             ssh_gai_strerror(r));
2534                 }
2535                 return 0;
2536         }
2537
2538         for (ai = aitop; ai; ai = ai->ai_next) {
2539                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2540                         continue;
2541                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2542                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2543                         error("channel_setup_fwd_listener: getnameinfo failed");
2544                         continue;
2545                 }
2546                 /* Create a port to listen for the host. */
2547                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2548                 if (sock < 0) {
2549                         /* this is no error since kernel may not support ipv6 */
2550                         verbose("socket: %.100s", strerror(errno));
2551                         continue;
2552                 }
2553
2554                 channel_set_reuseaddr(sock);
2555
2556                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2557
2558                 /* Bind the socket to the address. */
2559                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2560                         /* address can be in use ipv6 address is already bound */
2561                         if (!ai->ai_next)
2562                                 error("bind: %.100s", strerror(errno));
2563                         else
2564                                 verbose("bind: %.100s", strerror(errno));
2565
2566                         close(sock);
2567                         continue;
2568                 }
2569                 /* Start listening for connections on the socket. */
2570                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2571                         error("listen: %.100s", strerror(errno));
2572                         close(sock);
2573                         continue;
2574                 }
2575                 /* Allocate a channel number for the socket. */
2576                 /* explicitly test for hpn disabled option. if true use smaller window size */
2577                 if (hpn_disabled)
2578                 c = channel_new("port listener", type, sock, sock, -1,
2579                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2580                     0, "port listener", 1);
2581                 else
2582                         c = channel_new("port listener", type, sock, sock, -1,
2583                           hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT,
2584                           0, "port listener", 1);
2585                 strlcpy(c->path, host, sizeof(c->path));
2586                 c->host_port = port_to_connect;
2587                 c->listening_port = listen_port;
2588                 success = 1;
2589         }
2590         if (success == 0)
2591                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2592                     listen_port);
2593         freeaddrinfo(aitop);
2594         return success;
2595 }
2596
2597 int
2598 channel_cancel_rport_listener(const char *host, u_short port)
2599 {
2600         u_int i;
2601         int found = 0;
2602
2603         for (i = 0; i < channels_alloc; i++) {
2604                 Channel *c = channels[i];
2605
2606                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2607                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2608                     c->listening_port == port) {
2609                         debug2("%s: close channel %d", __func__, i);
2610                         channel_free(c);
2611                         found = 1;
2612                 }
2613         }
2614
2615         return (found);
2616 }
2617
2618 /* protocol local port fwd, used by ssh (and sshd in v1) */
2619 int
2620 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2621     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2622 {
2623         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2624             listen_host, listen_port, host_to_connect, port_to_connect,
2625             gateway_ports);
2626 }
2627
2628 /* protocol v2 remote port fwd, used by sshd */
2629 int
2630 channel_setup_remote_fwd_listener(const char *listen_address,
2631     u_short listen_port, int gateway_ports)
2632 {
2633         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2634             listen_address, listen_port, NULL, 0, gateway_ports);
2635 }
2636
2637 /*
2638  * Initiate forwarding of connections to port "port" on remote host through
2639  * the secure channel to host:port from local side.
2640  */
2641
2642 int
2643 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2644     const char *host_to_connect, u_short port_to_connect)
2645 {
2646         int type, success = 0;
2647
2648         /* Record locally that connection to this host/port is permitted. */
2649         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2650                 fatal("channel_request_remote_forwarding: too many forwards");
2651
2652         /* Send the forward request to the remote side. */
2653         if (compat20) {
2654                 const char *address_to_bind;
2655                 if (listen_host == NULL) {
2656                         if (datafellows & SSH_BUG_RFWD_ADDR)
2657                                 address_to_bind = "127.0.0.1";
2658                         else
2659                                 address_to_bind = "localhost";
2660                 } else if (*listen_host == '\0' ||
2661                            strcmp(listen_host, "*") == 0) {
2662                         if (datafellows & SSH_BUG_RFWD_ADDR)
2663                                 address_to_bind = "0.0.0.0";
2664                         else
2665                                 address_to_bind = "";
2666                 } else
2667                         address_to_bind = listen_host;
2668
2669                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2670                 packet_put_cstring("tcpip-forward");
2671                 packet_put_char(1);                     /* boolean: want reply */
2672                 packet_put_cstring(address_to_bind);
2673                 packet_put_int(listen_port);
2674                 packet_send();
2675                 packet_write_wait();
2676                 /* Assume that server accepts the request */
2677                 success = 1;
2678         } else {
2679                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2680                 packet_put_int(listen_port);
2681                 packet_put_cstring(host_to_connect);
2682                 packet_put_int(port_to_connect);
2683                 packet_send();
2684                 packet_write_wait();
2685
2686                 /* Wait for response from the remote side. */
2687                 type = packet_read();
2688                 switch (type) {
2689                 case SSH_SMSG_SUCCESS:
2690                         success = 1;
2691                         break;
2692                 case SSH_SMSG_FAILURE:
2693                         break;
2694                 default:
2695                         /* Unknown packet */
2696                         packet_disconnect("Protocol error for port forward request:"
2697                             "received packet type %d.", type);
2698                 }
2699         }
2700         if (success) {
2701                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2702                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2703                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2704                 num_permitted_opens++;
2705         }
2706         return (success ? 0 : -1);
2707 }
2708
2709 /*
2710  * Request cancellation of remote forwarding of connection host:port from
2711  * local side.
2712  */
2713 void
2714 channel_request_rforward_cancel(const char *host, u_short port)
2715 {
2716         int i;
2717
2718         if (!compat20)
2719                 return;
2720
2721         for (i = 0; i < num_permitted_opens; i++) {
2722                 if (permitted_opens[i].host_to_connect != NULL &&
2723                     permitted_opens[i].listen_port == port)
2724                         break;
2725         }
2726         if (i >= num_permitted_opens) {
2727                 debug("%s: requested forward not found", __func__);
2728                 return;
2729         }
2730         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2731         packet_put_cstring("cancel-tcpip-forward");
2732         packet_put_char(0);
2733         packet_put_cstring(host == NULL ? "" : host);
2734         packet_put_int(port);
2735         packet_send();
2736
2737         permitted_opens[i].listen_port = 0;
2738         permitted_opens[i].port_to_connect = 0;
2739         xfree(permitted_opens[i].host_to_connect);
2740         permitted_opens[i].host_to_connect = NULL;
2741 }
2742
2743 /*
2744  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2745  * listening for the port, and sends back a success reply (or disconnect
2746  * message if there was an error).
2747  */
2748 int
2749 channel_input_port_forward_request(int is_root, int gateway_ports)
2750 {
2751         u_short port, host_port;
2752         int success = 0;
2753         char *hostname;
2754
2755         /* Get arguments from the packet. */
2756         port = packet_get_int();
2757         hostname = packet_get_string(NULL);
2758         host_port = packet_get_int();
2759
2760 #ifndef HAVE_CYGWIN
2761         /*
2762          * Check that an unprivileged user is not trying to forward a
2763          * privileged port.
2764          */
2765         if (port < IPPORT_RESERVED && !is_root)
2766                 packet_disconnect(
2767                     "Requested forwarding of port %d but user is not root.",
2768                     port);
2769         if (host_port == 0)
2770                 packet_disconnect("Dynamic forwarding denied.");
2771 #endif
2772
2773         /* Initiate forwarding */
2774         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2775             host_port, gateway_ports);
2776
2777         /* Free the argument string. */
2778         xfree(hostname);
2779
2780         return (success ? 0 : -1);
2781 }
2782
2783 /*
2784  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2785  * usually called by the server, because the user could connect to any port
2786  * anyway, and the server has no way to know but to trust the client anyway.
2787  */
2788 void
2789 channel_permit_all_opens(void)
2790 {
2791         if (num_permitted_opens == 0)
2792                 all_opens_permitted = 1;
2793 }
2794
2795 void
2796 channel_add_permitted_opens(char *host, int port)
2797 {
2798         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2799                 fatal("channel_add_permitted_opens: too many forwards");
2800         debug("allow port forwarding to host %s port %d", host, port);
2801
2802         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2803         permitted_opens[num_permitted_opens].port_to_connect = port;
2804         num_permitted_opens++;
2805
2806         all_opens_permitted = 0;
2807 }
2808
2809 int
2810 channel_add_adm_permitted_opens(char *host, int port)
2811 {
2812         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2813                 fatal("channel_add_adm_permitted_opens: too many forwards");
2814         debug("config allows port forwarding to host %s port %d", host, port);
2815
2816         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2817              = xstrdup(host);
2818         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2819         return ++num_adm_permitted_opens;
2820 }
2821
2822 void
2823 channel_clear_permitted_opens(void)
2824 {
2825         int i;
2826
2827         for (i = 0; i < num_permitted_opens; i++)
2828                 if (permitted_opens[i].host_to_connect != NULL)
2829                         xfree(permitted_opens[i].host_to_connect);
2830         num_permitted_opens = 0;
2831 }
2832
2833 void
2834 channel_clear_adm_permitted_opens(void)
2835 {
2836         int i;
2837
2838         for (i = 0; i < num_adm_permitted_opens; i++)
2839                 if (permitted_adm_opens[i].host_to_connect != NULL)
2840                         xfree(permitted_adm_opens[i].host_to_connect);
2841         num_adm_permitted_opens = 0;
2842 }
2843
2844 void
2845 channel_print_adm_permitted_opens(void)
2846 {
2847         int i;
2848
2849         for (i = 0; i < num_adm_permitted_opens; i++)
2850                 if (permitted_adm_opens[i].host_to_connect != NULL)
2851                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
2852                             permitted_adm_opens[i].port_to_connect);
2853 }
2854
2855 /* Try to start non-blocking connect to next host in cctx list */
2856 static int
2857 connect_next(struct channel_connect *cctx)
2858 {
2859         int sock, saved_errno;
2860         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2861
2862         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
2863                 if (cctx->ai->ai_family != AF_INET &&
2864                     cctx->ai->ai_family != AF_INET6)
2865                         continue;
2866                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
2867                     ntop, sizeof(ntop), strport, sizeof(strport),
2868                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2869                         error("connect_next: getnameinfo failed");
2870                         continue;
2871                 }
2872                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
2873                     cctx->ai->ai_protocol)) == -1) {
2874                         if (cctx->ai->ai_next == NULL)
2875                                 error("socket: %.100s", strerror(errno));
2876                         else
2877                                 verbose("socket: %.100s", strerror(errno));
2878                         continue;
2879                 }
2880                 if (set_nonblock(sock) == -1)
2881                         fatal("%s: set_nonblock(%d)", __func__, sock);
2882                 if (connect(sock, cctx->ai->ai_addr,
2883                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
2884                         debug("connect_next: host %.100s ([%.100s]:%s): "
2885                             "%.100s", cctx->host, ntop, strport,
2886                             strerror(errno));
2887                         saved_errno = errno;
2888                         close(sock);
2889                         errno = saved_errno;
2890                         continue;       /* fail -- try next */
2891                 }
2892                 debug("connect_next: host %.100s ([%.100s]:%s) "
2893                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
2894                 cctx->ai = cctx->ai->ai_next;
2895                 set_nodelay(sock);
2896                 return sock;
2897         }
2898         return -1;
2899 }
2900
2901 static void
2902 channel_connect_ctx_free(struct channel_connect *cctx)
2903 {
2904         xfree(cctx->host);
2905         if (cctx->aitop)
2906                 freeaddrinfo(cctx->aitop);
2907         bzero(cctx, sizeof(*cctx));
2908         cctx->host = NULL;
2909         cctx->ai = cctx->aitop = NULL;
2910 }
2911
2912 /* Return CONNECTING channel to remote host, port */
2913 static Channel *
2914 connect_to(const char *host, u_short port, char *ctype, char *rname)
2915 {
2916         struct addrinfo hints;
2917         int gaierr;
2918         int sock = -1;
2919         char strport[NI_MAXSERV];
2920         struct channel_connect cctx;
2921         Channel *c;
2922
2923         memset(&cctx, 0, sizeof(cctx));
2924         memset(&hints, 0, sizeof(hints));
2925         hints.ai_family = IPv4or6;
2926         hints.ai_socktype = SOCK_STREAM;
2927         snprintf(strport, sizeof strport, "%d", port);
2928         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
2929                 error("connect_to %.100s: unknown host (%s)", host,
2930                     ssh_gai_strerror(gaierr));
2931                 return NULL;
2932         }
2933
2934         cctx.host = xstrdup(host);
2935         cctx.port = port;
2936         cctx.ai = cctx.aitop;
2937
2938         if ((sock = connect_next(&cctx)) == -1) {
2939                 error("connect to %.100s port %d failed: %s",
2940                     host, port, strerror(errno));
2941                 channel_connect_ctx_free(&cctx);
2942                 return NULL;
2943         }
2944         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
2945             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
2946         c->connect_ctx = cctx;
2947         return c;
2948 }
2949
2950 Channel *
2951 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
2952 {
2953         int i;
2954
2955         for (i = 0; i < num_permitted_opens; i++) {
2956                 if (permitted_opens[i].host_to_connect != NULL &&
2957                     permitted_opens[i].listen_port == listen_port) {
2958                         return connect_to(
2959                             permitted_opens[i].host_to_connect,
2960                             permitted_opens[i].port_to_connect, ctype, rname);
2961                 }
2962         }
2963         error("WARNING: Server requests forwarding for unknown listen_port %d",
2964             listen_port);
2965         return NULL;
2966 }
2967
2968 /* Check if connecting to that port is permitted and connect. */
2969 Channel *
2970 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
2971 {
2972         int i, permit, permit_adm = 1;
2973
2974         permit = all_opens_permitted;
2975         if (!permit) {
2976                 for (i = 0; i < num_permitted_opens; i++)
2977                         if (permitted_opens[i].host_to_connect != NULL &&
2978                             permitted_opens[i].port_to_connect == port &&
2979                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2980                                 permit = 1;
2981         }
2982
2983         if (num_adm_permitted_opens > 0) {
2984                 permit_adm = 0;
2985                 for (i = 0; i < num_adm_permitted_opens; i++)
2986                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2987                             permitted_adm_opens[i].port_to_connect == port &&
2988                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2989                             == 0)
2990                                 permit_adm = 1;
2991         }
2992
2993         if (!permit || !permit_adm) {
2994                 logit("Received request to connect to host %.100s port %d, "
2995                     "but the request was denied.", host, port);
2996                 return NULL;
2997         }
2998         return connect_to(host, port, ctype, rname);
2999 }
3000
3001 void
3002 channel_send_window_changes(void)
3003 {
3004         u_int i;
3005         struct winsize ws;
3006
3007         for (i = 0; i < channels_alloc; i++) {
3008                 if (channels[i] == NULL || !channels[i]->client_tty ||
3009                     channels[i]->type != SSH_CHANNEL_OPEN)
3010                         continue;
3011                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3012                         continue;
3013                 channel_request_start(i, "window-change", 0);
3014                 packet_put_int((u_int)ws.ws_col);
3015                 packet_put_int((u_int)ws.ws_row);
3016                 packet_put_int((u_int)ws.ws_xpixel);
3017                 packet_put_int((u_int)ws.ws_ypixel);
3018                 packet_send();
3019         }
3020 }
3021
3022 /* -- X11 forwarding */
3023
3024 /*
3025  * Creates an internet domain socket for listening for X11 connections.
3026  * Returns 0 and a suitable display number for the DISPLAY variable
3027  * stored in display_numberp , or -1 if an error occurs.
3028  */
3029 int
3030 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3031     int single_connection, u_int *display_numberp, int **chanids)
3032 {
3033         Channel *nc = NULL;
3034         int display_number, sock;
3035         u_short port;
3036         struct addrinfo hints, *ai, *aitop;
3037         char strport[NI_MAXSERV];
3038         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3039
3040         if (chanids == NULL)
3041                 return -1;
3042
3043         for (display_number = x11_display_offset;
3044             display_number < MAX_DISPLAYS;
3045             display_number++) {
3046                 port = 6000 + display_number;
3047                 memset(&hints, 0, sizeof(hints));
3048                 hints.ai_family = IPv4or6;
3049                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3050                 hints.ai_socktype = SOCK_STREAM;
3051                 snprintf(strport, sizeof strport, "%d", port);
3052                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3053                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3054                         return -1;
3055                 }
3056                 for (ai = aitop; ai; ai = ai->ai_next) {
3057                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3058                                 continue;
3059                         sock = socket(ai->ai_family, ai->ai_socktype,
3060                             ai->ai_protocol);
3061                         if (sock < 0) {
3062                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3063                                         error("socket: %.100s", strerror(errno));
3064                                         freeaddrinfo(aitop);
3065                                         return -1;
3066                                 } else {
3067                                         debug("x11_create_display_inet: Socket family %d not supported",
3068                                                  ai->ai_family);
3069                                         continue;
3070                                 }
3071                         }
3072 #ifdef IPV6_V6ONLY
3073                         if (ai->ai_family == AF_INET6) {
3074                                 int on = 1;
3075                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
3076                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
3077                         }
3078 #endif
3079                         if (x11_use_localhost)
3080                                 channel_set_reuseaddr(sock);
3081                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3082                                 debug2("bind port %d: %.100s", port, strerror(errno));
3083                                 close(sock);
3084
3085                                 for (n = 0; n < num_socks; n++) {
3086                                         close(socks[n]);
3087                                 }
3088                                 num_socks = 0;
3089                                 break;
3090                         }
3091                         socks[num_socks++] = sock;
3092                         if (num_socks == NUM_SOCKS)
3093                                 break;
3094                 }
3095                 freeaddrinfo(aitop);
3096                 if (num_socks > 0)
3097                         break;
3098         }
3099         if (display_number >= MAX_DISPLAYS) {
3100                 error("Failed to allocate internet-domain X11 display socket.");
3101                 return -1;
3102         }
3103         /* Start listening for connections on the socket. */
3104         for (n = 0; n < num_socks; n++) {
3105                 sock = socks[n];
3106                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3107                         error("listen: %.100s", strerror(errno));
3108                         close(sock);
3109                         return -1;
3110                 }
3111         }
3112
3113         /* Allocate a channel for each socket. */
3114         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3115         for (n = 0; n < num_socks; n++) {
3116                 sock = socks[n];
3117                 /* Is this really necassary? */
3118                 if (hpn_disabled)
3119                 nc = channel_new("x11 listener",
3120                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3121                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3122                     0, "X11 inet listener", 1);
3123                 else
3124                         nc = channel_new("x11 listener",
3125                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3126                             hpn_buffer_size, CHAN_X11_PACKET_DEFAULT,
3127                             0, "X11 inet listener", 1);
3128                 nc->single_connection = single_connection;
3129                 (*chanids)[n] = nc->self;
3130         }
3131         (*chanids)[n] = -1;
3132
3133         /* Return the display number for the DISPLAY environment variable. */
3134         *display_numberp = display_number;
3135         return (0);
3136 }
3137
3138 static int
3139 connect_local_xsocket(u_int dnr)
3140 {
3141         int sock;
3142         struct sockaddr_un addr;
3143
3144         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3145         if (sock < 0)
3146                 error("socket: %.100s", strerror(errno));
3147         memset(&addr, 0, sizeof(addr));
3148         addr.sun_family = AF_UNIX;
3149         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
3150         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3151                 return sock;
3152         close(sock);
3153         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3154         return -1;
3155 }
3156
3157 int
3158 x11_connect_display(void)
3159 {
3160         u_int display_number;
3161         const char *display;
3162         char buf[1024], *cp;
3163         struct addrinfo hints, *ai, *aitop;
3164         char strport[NI_MAXSERV];
3165         int gaierr, sock = 0;
3166
3167         /* Try to open a socket for the local X server. */
3168         display = getenv("DISPLAY");
3169         if (!display) {
3170                 error("DISPLAY not set.");
3171                 return -1;
3172         }
3173         /*
3174          * Now we decode the value of the DISPLAY variable and make a
3175          * connection to the real X server.
3176          */
3177
3178         /*
3179          * Check if it is a unix domain socket.  Unix domain displays are in
3180          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3181          */
3182         if (strncmp(display, "unix:", 5) == 0 ||
3183             display[0] == ':') {
3184                 /* Connect to the unix domain socket. */
3185                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3186                         error("Could not parse display number from DISPLAY: %.100s",
3187                             display);
3188                         return -1;
3189                 }
3190                 /* Create a socket. */
3191                 sock = connect_local_xsocket(display_number);
3192                 if (sock < 0)
3193                         return -1;
3194
3195                 /* OK, we now have a connection to the display. */
3196                 return sock;
3197         }
3198         /*
3199          * Connect to an inet socket.  The DISPLAY value is supposedly
3200          * hostname:d[.s], where hostname may also be numeric IP address.
3201          */
3202         strlcpy(buf, display, sizeof(buf));
3203         cp = strchr(buf, ':');
3204         if (!cp) {
3205                 error("Could not find ':' in DISPLAY: %.100s", display);
3206                 return -1;
3207         }
3208         *cp = 0;
3209         /* buf now contains the host name.  But first we parse the display number. */
3210         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3211                 error("Could not parse display number from DISPLAY: %.100s",
3212                     display);
3213                 return -1;
3214         }
3215
3216         /* Look up the host address */
3217         memset(&hints, 0, sizeof(hints));
3218         hints.ai_family = IPv4or6;
3219         hints.ai_socktype = SOCK_STREAM;
3220         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3221         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3222                 error("%.100s: unknown host. (%s)", buf,
3223                 ssh_gai_strerror(gaierr));
3224                 return -1;
3225         }
3226         for (ai = aitop; ai; ai = ai->ai_next) {
3227                 /* Create a socket. */
3228                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3229                 if (sock < 0) {
3230                         debug2("socket: %.100s", strerror(errno));
3231                         continue;
3232                 }
3233                 /* Connect it to the display. */
3234                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3235                         debug2("connect %.100s port %u: %.100s", buf,
3236                             6000 + display_number, strerror(errno));
3237                         close(sock);
3238                         continue;
3239                 }
3240                 /* Success */
3241                 break;
3242         }
3243         freeaddrinfo(aitop);
3244         if (!ai) {
3245                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3246                     strerror(errno));
3247                 return -1;
3248         }
3249         set_nodelay(sock);
3250         return sock;
3251 }
3252
3253 /*
3254  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3255  * the remote channel number.  We should do whatever we want, and respond
3256  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3257  */
3258
3259 /* ARGSUSED */
3260 void
3261 x11_input_open(int type, u_int32_t seq, void *ctxt)
3262 {
3263         Channel *c = NULL;
3264         int remote_id, sock = 0;
3265         char *remote_host;
3266
3267         debug("Received X11 open request.");
3268
3269         remote_id = packet_get_int();
3270
3271         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3272                 remote_host = packet_get_string(NULL);
3273         } else {
3274                 remote_host = xstrdup("unknown (remote did not supply name)");
3275         }
3276         packet_check_eom();
3277
3278         /* Obtain a connection to the real X display. */
3279         sock = x11_connect_display();
3280         if (sock != -1) {
3281                 /* Allocate a channel for this connection. */
3282                 c = channel_new("connected x11 socket",
3283                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3284                     remote_host, 1);
3285                 c->remote_id = remote_id;
3286                 c->force_drain = 1;
3287         }
3288         xfree(remote_host);
3289         if (c == NULL) {
3290                 /* Send refusal to the remote host. */
3291                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3292                 packet_put_int(remote_id);
3293         } else {
3294                 /* Send a confirmation to the remote host. */
3295                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3296                 packet_put_int(remote_id);
3297                 packet_put_int(c->self);
3298         }
3299         packet_send();
3300 }
3301
3302 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3303 /* ARGSUSED */
3304 void
3305 deny_input_open(int type, u_int32_t seq, void *ctxt)
3306 {
3307         int rchan = packet_get_int();
3308
3309         switch (type) {
3310         case SSH_SMSG_AGENT_OPEN:
3311                 error("Warning: ssh server tried agent forwarding.");
3312                 break;
3313         case SSH_SMSG_X11_OPEN:
3314                 error("Warning: ssh server tried X11 forwarding.");
3315                 break;
3316         default:
3317                 error("deny_input_open: type %d", type);
3318                 break;
3319         }
3320         error("Warning: this is probably a break-in attempt by a malicious server.");
3321         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3322         packet_put_int(rchan);
3323         packet_send();
3324 }
3325
3326 /*
3327  * Requests forwarding of X11 connections, generates fake authentication
3328  * data, and enables authentication spoofing.
3329  * This should be called in the client only.
3330  */
3331 void
3332 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3333     const char *proto, const char *data)
3334 {
3335         u_int data_len = (u_int) strlen(data) / 2;
3336         u_int i, value;
3337         char *new_data;
3338         int screen_number;
3339         const char *cp;
3340         u_int32_t rnd = 0;
3341
3342         if (x11_saved_display == NULL)
3343                 x11_saved_display = xstrdup(disp);
3344         else if (strcmp(disp, x11_saved_display) != 0) {
3345                 error("x11_request_forwarding_with_spoofing: different "
3346                     "$DISPLAY already forwarded");
3347                 return;
3348         }
3349
3350         cp = strchr(disp, ':');
3351         if (cp)
3352                 cp = strchr(cp, '.');
3353         if (cp)
3354                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3355         else
3356                 screen_number = 0;
3357
3358         if (x11_saved_proto == NULL) {
3359                 /* Save protocol name. */
3360                 x11_saved_proto = xstrdup(proto);
3361                 /*
3362                  * Extract real authentication data and generate fake data
3363                  * of the same length.
3364                  */
3365                 x11_saved_data = xmalloc(data_len);
3366                 x11_fake_data = xmalloc(data_len);
3367                 for (i = 0; i < data_len; i++) {
3368                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3369                                 fatal("x11_request_forwarding: bad "
3370                                     "authentication data: %.100s", data);
3371                         if (i % 4 == 0)
3372                                 rnd = arc4random();
3373                         x11_saved_data[i] = value;
3374                         x11_fake_data[i] = rnd & 0xff;
3375                         rnd >>= 8;
3376                 }
3377                 x11_saved_data_len = data_len;
3378                 x11_fake_data_len = data_len;
3379         }
3380
3381         /* Convert the fake data into hex. */
3382         new_data = tohex(x11_fake_data, data_len);
3383
3384         /* Send the request packet. */
3385         if (compat20) {
3386                 channel_request_start(client_session_id, "x11-req", 0);
3387                 packet_put_char(0);     /* XXX bool single connection */
3388         } else {
3389                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3390         }
3391         packet_put_cstring(proto);
3392         packet_put_cstring(new_data);
3393         packet_put_int(screen_number);
3394         packet_send();
3395         packet_write_wait();
3396         xfree(new_data);
3397 }
3398
3399
3400 /* -- agent forwarding */
3401
3402 /* Sends a message to the server to request authentication fd forwarding. */
3403
3404 void
3405 auth_request_forwarding(void)
3406 {
3407         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3408         packet_send();
3409         packet_write_wait();
3410 }