crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.324 2013/07/12 00:19:58 djm Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * This file contains functions for generic socket connection forwarding.
   8  * There is also code for initiating connection forwarding for X11 connections,
   9  * arbitrary tcp/ip connections, and the authentication agent connection.
  10  *
  11  * As far as I am concerned, the code I have written for this software
  12  * can be used freely for any purpose.  Any derived versions of this
  13  * software must be clearly marked as such, and if the derived work is
  14  * incompatible with the protocol description in the RFC file, it must be
  15  * called by a name other than "ssh" or "Secure Shell".
  16  *
  17  * SSH2 support added by Markus Friedl.
  18  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  19  * Copyright (c) 1999 Dug Song.  All rights reserved.
  20  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44
  45 #include <sys/types.h>
  46 #include <sys/ioctl.h>
  47 #include <sys/un.h>
  48 #include <sys/socket.h>
  49 #ifdef HAVE_SYS_TIME_H
  50 # include <sys/time.h>
  51 #endif
  52
  53 #include <netinet/in.h>
  54 #include <arpa/inet.h>
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <termios.h>
  63 #include <unistd.h>
  64 #include <stdarg.h>
  65
  66 #include "openbsd-compat/sys-queue.h"
  67 #include "xmalloc.h"
  68 #include "ssh.h"
  69 #include "ssh1.h"
  70 #include "ssh2.h"
  71 #include "packet.h"
  72 #include "log.h"
  73 #include "misc.h"
  74 #include "buffer.h"
  75 #include "channels.h"
  76 #include "compat.h"
  77 #include "canohost.h"
  78 #include "key.h"
  79 #include "authfd.h"
  80 #include "pathnames.h"
  81
  82 /* -- channel core */
  83
  84 /*
  85  * Pointer to an array containing all allocated channels.  The array is
  86  * dynamically extended as needed.
  87  */
  88 static Channel **channels = NULL;
  89
  90 /*
  91  * Size of the channel array.  All slots of the array must always be
  92  * initialized (at least the type field); unused slots set to NULL
  93  */
  94 static u_int channels_alloc = 0;
  95
  96 /*
  97  * Maximum file descriptor value used in any of the channels.  This is
  98  * updated in channel_new.
  99  */
 100 static int channel_max_fd = 0;
 101
 102
 103 /* -- tcp forwarding */
 104
 105 /*
 106  * Data structure for storing which hosts are permitted for forward requests.
 107  * The local sides of any remote forwards are stored in this array to prevent
 108  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 109  * network (which might be behind a firewall).
 110  */
 111 typedef struct {
 112         char *host_to_connect;          /* Connect to 'host'. */
 113         u_short port_to_connect;        /* Connect to 'port'. */
 114         u_short listen_port;            /* Remote side should listen port number. */
 115 } ForwardPermission;
 116
 117 /* List of all permitted host/port pairs to connect by the user. */
 118 static ForwardPermission *permitted_opens = NULL;
 119
 120 /* List of all permitted host/port pairs to connect by the admin. */
 121 static ForwardPermission *permitted_adm_opens = NULL;
 122
 123 /* Number of permitted host/port pairs in the array permitted by the user. */
 124 static int num_permitted_opens = 0;
 125
 126 /* Number of permitted host/port pair in the array permitted by the admin. */
 127 static int num_adm_permitted_opens = 0;
 128
 129 /* special-case port number meaning allow any port */
 130 #define FWD_PERMIT_ANY_PORT     0
 131
 132 /*
 133  * If this is true, all opens are permitted.  This is the case on the server
 134  * on which we have to trust the client anyway, and the user could do
 135  * anything after logging in anyway.
 136  */
 137 static int all_opens_permitted = 0;
 138
 139
 140 /* -- X11 forwarding */
 141
 142 /* Maximum number of fake X11 displays to try. */
 143 #define MAX_DISPLAYS  1000
 144
 145 /* Saved X11 local (client) display. */
 146 static char *x11_saved_display = NULL;
 147
 148 /* Saved X11 authentication protocol name. */
 149 static char *x11_saved_proto = NULL;
 150
 151 /* Saved X11 authentication data.  This is the real data. */
 152 static char *x11_saved_data = NULL;
 153 static u_int x11_saved_data_len = 0;
 154
 155 /*
 156  * Fake X11 authentication data.  This is what the server will be sending us;
 157  * we should replace any occurrences of this by the real data.
 158  */
 159 static u_char *x11_fake_data = NULL;
 160 static u_int x11_fake_data_len;
 161
 162
 163 /* -- agent forwarding */
 164
 165 #define NUM_SOCKS       10
 166
 167 /* AF_UNSPEC or AF_INET or AF_INET6 */
 168 static int IPv4or6 = AF_UNSPEC;
 169
 170 /* helper */
 171 static void port_open_helper(Channel *c, char *rtype);
 172
 173 /* non-blocking connect helpers */
 174 static int connect_next(struct channel_connect *);
 175 static void channel_connect_ctx_free(struct channel_connect *);
 176
 177 /* -- HPN */
 178
 179 static int hpn_disabled = 0;
 180 static u_int buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
 181
 182 /* -- channel core */
 183
 184 Channel *
 185 channel_by_id(int id)
 186 {
 187         Channel *c;
 188
 189         if (id < 0 || (u_int)id >= channels_alloc) {
 190                 logit("channel_by_id: %d: bad id", id);
 191                 return NULL;
 192         }
 193         c = channels[id];
 194         if (c == NULL) {
 195                 logit("channel_by_id: %d: bad id: channel free", id);
 196                 return NULL;
 197         }
 198         return c;
 199 }
 200
 201 /*
 202  * Returns the channel if it is allowed to receive protocol messages.
 203  * Private channels, like listening sockets, may not receive messages.
 204  */
 205 Channel *
 206 channel_lookup(int id)
 207 {
 208         Channel *c;
 209
 210         if ((c = channel_by_id(id)) == NULL)
 211                 return (NULL);
 212
 213         switch (c->type) {
 214         case SSH_CHANNEL_X11_OPEN:
 215         case SSH_CHANNEL_LARVAL:
 216         case SSH_CHANNEL_CONNECTING:
 217         case SSH_CHANNEL_DYNAMIC:
 218         case SSH_CHANNEL_OPENING:
 219         case SSH_CHANNEL_OPEN:
 220         case SSH_CHANNEL_INPUT_DRAINING:
 221         case SSH_CHANNEL_OUTPUT_DRAINING:
 222         case SSH_CHANNEL_ABANDONED:
 223                 return (c);
 224         }
 225         logit("Non-public channel %d, type %d.", id, c->type);
 226         return (NULL);
 227 }
 228
 229 /*
 230  * Register filedescriptors for a channel, used when allocating a channel or
 231  * when the channel consumer/producer is ready, e.g. shell exec'd
 232  */
 233 static void
 234 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 235     int extusage, int nonblock, int is_tty)
 236 {
 237         /* Update the maximum file descriptor value. */
 238         channel_max_fd = MAX(channel_max_fd, rfd);
 239         channel_max_fd = MAX(channel_max_fd, wfd);
 240         channel_max_fd = MAX(channel_max_fd, efd);
 241
 242         if (rfd != -1)
 243                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 244         if (wfd != -1 && wfd != rfd)
 245                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 246         if (efd != -1 && efd != rfd && efd != wfd)
 247                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 248
 249         c->rfd = rfd;
 250         c->wfd = wfd;
 251         c->sock = (rfd == wfd) ? rfd : -1;
 252         c->efd = efd;
 253         c->extended_usage = extusage;
 254
 255         if ((c->isatty = is_tty) != 0)
 256                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 257 #ifdef _AIX
 258         /* XXX: Later AIX versions can't push as much data to tty */
 259         c->wfd_isatty = is_tty || isatty(c->wfd);
 260 #endif
 261
 262         /* enable nonblocking mode */
 263         if (nonblock) {
 264                 if (rfd != -1)
 265                         set_nonblock(rfd);
 266                 if (wfd != -1)
 267                         set_nonblock(wfd);
 268                 if (efd != -1)
 269                         set_nonblock(efd);
 270         }
 271 }
 272
 273 /*
 274  * Allocate a new channel object and set its type and socket. This will cause
 275  * remote_name to be freed.
 276  */
 277 Channel *
 278 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 279     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 280 {
 281         int found;
 282         u_int i;
 283         Channel *c;
 284
 285         /* Do initial allocation if this is the first call. */
 286         if (channels_alloc == 0) {
 287                 channels_alloc = 10;
 288                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 289                 for (i = 0; i < channels_alloc; i++)
 290                         channels[i] = NULL;
 291         }
 292         /* Try to find a free slot where to put the new channel. */
 293         for (found = -1, i = 0; i < channels_alloc; i++)
 294                 if (channels[i] == NULL) {
 295                         /* Found a free slot. */
 296                         found = (int)i;
 297                         break;
 298                 }
 299         if (found < 0) {
 300                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 301                 found = channels_alloc;
 302                 if (channels_alloc > 10000)
 303                         fatal("channel_new: internal error: channels_alloc %d "
 304                             "too big.", channels_alloc);
 305                 channels = xrealloc(channels, channels_alloc + 10,
 306                     sizeof(Channel *));
 307                 channels_alloc += 10;
 308                 debug2("channel: expanding %d", channels_alloc);
 309                 for (i = found; i < channels_alloc; i++)
 310                         channels[i] = NULL;
 311         }
 312         /* Initialize and return new channel. */
 313         c = channels[found] = xcalloc(1, sizeof(Channel));
 314         buffer_init(&c->input);
 315         buffer_init(&c->output);
 316         buffer_init(&c->extended);
 317         c->path = NULL;
 318         c->listening_addr = NULL;
 319         c->listening_port = 0;
 320         c->ostate = CHAN_OUTPUT_OPEN;
 321         c->istate = CHAN_INPUT_OPEN;
 322         c->flags = 0;
 323         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 324         c->notbefore = 0;
 325         c->self = found;
 326         c->type = type;
 327         c->ctype = ctype;
 328         c->dynamic_window = 0;
 329         c->local_window = window;
 330         c->local_window_max = window;
 331         c->local_consumed = 0;
 332         c->local_maxpacket = maxpack;
 333         c->remote_id = -1;
 334         c->remote_name = xstrdup(remote_name);
 335         c->remote_window = 0;
 336         c->remote_maxpacket = 0;
 337         c->force_drain = 0;
 338         c->single_connection = 0;
 339         c->detach_user = NULL;
 340         c->detach_close = 0;
 341         c->open_confirm = NULL;
 342         c->open_confirm_ctx = NULL;
 343         c->input_filter = NULL;
 344         c->output_filter = NULL;
 345         c->filter_ctx = NULL;
 346         c->filter_cleanup = NULL;
 347         c->ctl_chan = -1;
 348         c->mux_rcb = NULL;
 349         c->mux_ctx = NULL;
 350         c->mux_pause = 0;
 351         c->delayed = 1;         /* prevent call to channel_post handler */
 352         TAILQ_INIT(&c->status_confirms);
 353         debug("channel %d: new [%s]", found, remote_name);
 354         return c;
 355 }
 356
 357 static int
 358 channel_find_maxfd(void)
 359 {
 360         u_int i;
 361         int max = 0;
 362         Channel *c;
 363
 364         for (i = 0; i < channels_alloc; i++) {
 365                 c = channels[i];
 366                 if (c != NULL) {
 367                         max = MAX(max, c->rfd);
 368                         max = MAX(max, c->wfd);
 369                         max = MAX(max, c->efd);
 370                 }
 371         }
 372         return max;
 373 }
 374
 375 int
 376 channel_close_fd(int *fdp)
 377 {
 378         int ret = 0, fd = *fdp;
 379
 380         if (fd != -1) {
 381                 ret = close(fd);
 382                 *fdp = -1;
 383                 if (fd == channel_max_fd)
 384                         channel_max_fd = channel_find_maxfd();
 385         }
 386         return ret;
 387 }
 388
 389 /* Close all channel fd/socket. */
 390 static void
 391 channel_close_fds(Channel *c)
 392 {
 393         channel_close_fd(&c->sock);
 394         channel_close_fd(&c->rfd);
 395         channel_close_fd(&c->wfd);
 396         channel_close_fd(&c->efd);
 397 }
 398
 399 /* Free the channel and close its fd/socket. */
 400 void
 401 channel_free(Channel *c)
 402 {
 403         char *s;
 404         u_int i, n;
 405         struct channel_confirm *cc;
 406
 407         for (n = 0, i = 0; i < channels_alloc; i++)
 408                 if (channels[i])
 409                         n++;
 410         debug("channel %d: free: %s, nchannels %u", c->self,
 411             c->remote_name ? c->remote_name : "???", n);
 412
 413         s = channel_open_message();
 414         debug3("channel %d: status: %s", c->self, s);
 415         free(s);
 416
 417         if (c->sock != -1)
 418                 shutdown(c->sock, SHUT_RDWR);
 419         channel_close_fds(c);
 420         buffer_free(&c->input);
 421         buffer_free(&c->output);
 422         buffer_free(&c->extended);
 423         free(c->remote_name);
 424         c->remote_name = NULL;
 425         free(c->path);
 426         c->path = NULL;
 427         free(c->listening_addr);
 428         c->listening_addr = NULL;
 429         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 430                 if (cc->abandon_cb != NULL)
 431                         cc->abandon_cb(c, cc->ctx);
 432                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 433                 bzero(cc, sizeof(*cc));
 434                 free(cc);
 435         }
 436         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 437                 c->filter_cleanup(c->self, c->filter_ctx);
 438         channels[c->self] = NULL;
 439         free(c);
 440 }
 441
 442 void
 443 channel_free_all(void)
 444 {
 445         u_int i;
 446
 447         for (i = 0; i < channels_alloc; i++)
 448                 if (channels[i] != NULL)
 449                         channel_free(channels[i]);
 450 }
 451
 452 /*
 453  * Closes the sockets/fds of all channels.  This is used to close extra file
 454  * descriptors after a fork.
 455  */
 456 void
 457 channel_close_all(void)
 458 {
 459         u_int i;
 460
 461         for (i = 0; i < channels_alloc; i++)
 462                 if (channels[i] != NULL)
 463                         channel_close_fds(channels[i]);
 464 }
 465
 466 /*
 467  * Stop listening to channels.
 468  */
 469 void
 470 channel_stop_listening(void)
 471 {
 472         u_int i;
 473         Channel *c;
 474
 475         for (i = 0; i < channels_alloc; i++) {
 476                 c = channels[i];
 477                 if (c != NULL) {
 478                         switch (c->type) {
 479                         case SSH_CHANNEL_AUTH_SOCKET:
 480                         case SSH_CHANNEL_PORT_LISTENER:
 481                         case SSH_CHANNEL_RPORT_LISTENER:
 482                         case SSH_CHANNEL_X11_LISTENER:
 483                                 channel_close_fd(&c->sock);
 484                                 channel_free(c);
 485                                 break;
 486                         }
 487                 }
 488         }
 489 }
 490
 491 /*
 492  * Returns true if no channel has too much buffered data, and false if one or
 493  * more channel is overfull.
 494  */
 495 int
 496 channel_not_very_much_buffered_data(void)
 497 {
 498         u_int i;
 499         Channel *c;
 500
 501         for (i = 0; i < channels_alloc; i++) {
 502                 c = channels[i];
 503                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 504 #if 0
 505                         if (!compat20 &&
 506                             buffer_len(&c->input) > packet_get_maxsize()) {
 507                                 debug2("channel %d: big input buffer %d",
 508                                     c->self, buffer_len(&c->input));
 509                                 return 0;
 510                         }
 511 #endif
 512                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 513                                 debug2("channel %d: big output buffer %u > %u",
 514                                     c->self, buffer_len(&c->output),
 515                                     packet_get_maxsize());
 516                                 return 0;
 517                         }
 518                 }
 519         }
 520         return 1;
 521 }
 522
 523 /* Returns true if any channel is still open. */
 524 int
 525 channel_still_open(void)
 526 {
 527         u_int i;
 528         Channel *c;
 529
 530         for (i = 0; i < channels_alloc; i++) {
 531                 c = channels[i];
 532                 if (c == NULL)
 533                         continue;
 534                 switch (c->type) {
 535                 case SSH_CHANNEL_X11_LISTENER:
 536                 case SSH_CHANNEL_PORT_LISTENER:
 537                 case SSH_CHANNEL_RPORT_LISTENER:
 538                 case SSH_CHANNEL_MUX_LISTENER:
 539                 case SSH_CHANNEL_CLOSED:
 540                 case SSH_CHANNEL_AUTH_SOCKET:
 541                 case SSH_CHANNEL_DYNAMIC:
 542                 case SSH_CHANNEL_CONNECTING:
 543                 case SSH_CHANNEL_ZOMBIE:
 544                 case SSH_CHANNEL_ABANDONED:
 545                         continue;
 546                 case SSH_CHANNEL_LARVAL:
 547                         if (!compat20)
 548                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 549                         continue;
 550                 case SSH_CHANNEL_OPENING:
 551                 case SSH_CHANNEL_OPEN:
 552                 case SSH_CHANNEL_X11_OPEN:
 553                 case SSH_CHANNEL_MUX_CLIENT:
 554                         return 1;
 555                 case SSH_CHANNEL_INPUT_DRAINING:
 556                 case SSH_CHANNEL_OUTPUT_DRAINING:
 557                         if (!compat13)
 558                                 fatal("cannot happen: OUT_DRAIN");
 559                         return 1;
 560                 default:
 561                         fatal("channel_still_open: bad channel type %d", c->type);
 562                         /* NOTREACHED */
 563                 }
 564         }
 565         return 0;
 566 }
 567
 568 /* Returns the id of an open channel suitable for keepaliving */
 569 int
 570 channel_find_open(void)
 571 {
 572         u_int i;
 573         Channel *c;
 574
 575         for (i = 0; i < channels_alloc; i++) {
 576                 c = channels[i];
 577                 if (c == NULL || c->remote_id < 0)
 578                         continue;
 579                 switch (c->type) {
 580                 case SSH_CHANNEL_CLOSED:
 581                 case SSH_CHANNEL_DYNAMIC:
 582                 case SSH_CHANNEL_X11_LISTENER:
 583                 case SSH_CHANNEL_PORT_LISTENER:
 584                 case SSH_CHANNEL_RPORT_LISTENER:
 585                 case SSH_CHANNEL_MUX_LISTENER:
 586                 case SSH_CHANNEL_MUX_CLIENT:
 587                 case SSH_CHANNEL_OPENING:
 588                 case SSH_CHANNEL_CONNECTING:
 589                 case SSH_CHANNEL_ZOMBIE:
 590                 case SSH_CHANNEL_ABANDONED:
 591                         continue;
 592                 case SSH_CHANNEL_LARVAL:
 593                 case SSH_CHANNEL_AUTH_SOCKET:
 594                 case SSH_CHANNEL_OPEN:
 595                 case SSH_CHANNEL_X11_OPEN:
 596                         return i;
 597                 case SSH_CHANNEL_INPUT_DRAINING:
 598                 case SSH_CHANNEL_OUTPUT_DRAINING:
 599                         if (!compat13)
 600                                 fatal("cannot happen: OUT_DRAIN");
 601                         return i;
 602                 default:
 603                         fatal("channel_find_open: bad channel type %d", c->type);
 604                         /* NOTREACHED */
 605                 }
 606         }
 607         return -1;
 608 }
 609
 610
 611 /*
 612  * Returns a message describing the currently open forwarded connections,
 613  * suitable for sending to the client.  The message contains crlf pairs for
 614  * newlines.
 615  */
 616 char *
 617 channel_open_message(void)
 618 {
 619         Buffer buffer;
 620         Channel *c;
 621         char buf[1024], *cp;
 622         u_int i;
 623
 624         buffer_init(&buffer);
 625         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 626         buffer_append(&buffer, buf, strlen(buf));
 627         for (i = 0; i < channels_alloc; i++) {
 628                 c = channels[i];
 629                 if (c == NULL)
 630                         continue;
 631                 switch (c->type) {
 632                 case SSH_CHANNEL_X11_LISTENER:
 633                 case SSH_CHANNEL_PORT_LISTENER:
 634                 case SSH_CHANNEL_RPORT_LISTENER:
 635                 case SSH_CHANNEL_CLOSED:
 636                 case SSH_CHANNEL_AUTH_SOCKET:
 637                 case SSH_CHANNEL_ZOMBIE:
 638                 case SSH_CHANNEL_ABANDONED:
 639                 case SSH_CHANNEL_MUX_CLIENT:
 640                 case SSH_CHANNEL_MUX_LISTENER:
 641                         continue;
 642                 case SSH_CHANNEL_LARVAL:
 643                 case SSH_CHANNEL_OPENING:
 644                 case SSH_CHANNEL_CONNECTING:
 645                 case SSH_CHANNEL_DYNAMIC:
 646                 case SSH_CHANNEL_OPEN:
 647                 case SSH_CHANNEL_X11_OPEN:
 648                 case SSH_CHANNEL_INPUT_DRAINING:
 649                 case SSH_CHANNEL_OUTPUT_DRAINING:
 650                         snprintf(buf, sizeof buf,
 651                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cc %d)\r\n",
 652                             c->self, c->remote_name,
 653                             c->type, c->remote_id,
 654                             c->istate, buffer_len(&c->input),
 655                             c->ostate, buffer_len(&c->output),
 656                             c->rfd, c->wfd, c->ctl_chan);
 657                         buffer_append(&buffer, buf, strlen(buf));
 658                         continue;
 659                 default:
 660                         fatal("channel_open_message: bad channel type %d", c->type);
 661                         /* NOTREACHED */
 662                 }
 663         }
 664         buffer_append(&buffer, "\0", 1);
 665         cp = xstrdup(buffer_ptr(&buffer));
 666         buffer_free(&buffer);
 667         return cp;
 668 }
 669
 670 void
 671 channel_send_open(int id)
 672 {
 673         Channel *c = channel_lookup(id);
 674
 675         if (c == NULL) {
 676                 logit("channel_send_open: %d: bad id", id);
 677                 return;
 678         }
 679         debug2("channel %d: send open", id);
 680         packet_start(SSH2_MSG_CHANNEL_OPEN);
 681         packet_put_cstring(c->ctype);
 682         packet_put_int(c->self);
 683         packet_put_int(c->local_window);
 684         packet_put_int(c->local_maxpacket);
 685         packet_send();
 686 }
 687
 688 void
 689 channel_request_start(int id, char *service, int wantconfirm)
 690 {
 691         Channel *c = channel_lookup(id);
 692
 693         if (c == NULL) {
 694                 logit("channel_request_start: %d: unknown channel id", id);
 695                 return;
 696         }
 697         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 698         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 699         packet_put_int(c->remote_id);
 700         packet_put_cstring(service);
 701         packet_put_char(wantconfirm);
 702 }
 703
 704 void
 705 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 706     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 707 {
 708         struct channel_confirm *cc;
 709         Channel *c;
 710
 711         if ((c = channel_lookup(id)) == NULL)
 712                 fatal("channel_register_expect: %d: bad id", id);
 713
 714         cc = xmalloc(sizeof(*cc));
 715         cc->cb = cb;
 716         cc->abandon_cb = abandon_cb;
 717         cc->ctx = ctx;
 718         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 719 }
 720
 721 void
 722 channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
 723 {
 724         Channel *c = channel_lookup(id);
 725
 726         if (c == NULL) {
 727                 logit("channel_register_open_confirm: %d: bad id", id);
 728                 return;
 729         }
 730         c->open_confirm = fn;
 731         c->open_confirm_ctx = ctx;
 732 }
 733
 734 void
 735 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 736 {
 737         Channel *c = channel_by_id(id);
 738
 739         if (c == NULL) {
 740                 logit("channel_register_cleanup: %d: bad id", id);
 741                 return;
 742         }
 743         c->detach_user = fn;
 744         c->detach_close = do_close;
 745 }
 746
 747 void
 748 channel_cancel_cleanup(int id)
 749 {
 750         Channel *c = channel_by_id(id);
 751
 752         if (c == NULL) {
 753                 logit("channel_cancel_cleanup: %d: bad id", id);
 754                 return;
 755         }
 756         c->detach_user = NULL;
 757         c->detach_close = 0;
 758 }
 759
 760 void
 761 channel_register_filter(int id, channel_infilter_fn *ifn,
 762     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 763 {
 764         Channel *c = channel_lookup(id);
 765
 766         if (c == NULL) {
 767                 logit("channel_register_filter: %d: bad id", id);
 768                 return;
 769         }
 770         c->input_filter = ifn;
 771         c->output_filter = ofn;
 772         c->filter_ctx = ctx;
 773         c->filter_cleanup = cfn;
 774 }
 775
 776 void
 777 channel_set_fds(int id, int rfd, int wfd, int efd,
 778     int extusage, int nonblock, int is_tty, u_int window_max)
 779 {
 780         Channel *c = channel_lookup(id);
 781
 782         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 783                 fatal("channel_activate for non-larval channel %d.", id);
 784         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 785         c->type = SSH_CHANNEL_OPEN;
 786         c->local_window = c->local_window_max = window_max;
 787         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 788         packet_put_int(c->remote_id);
 789         packet_put_int(c->local_window);
 790         packet_send();
 791 }
 792
 793 /*
 794  * 'channel_pre*' are called just before select() to add any bits relevant to
 795  * channels in the select bitmasks.
 796  */
 797 /*
 798  * 'channel_post*': perform any appropriate operations for channels which
 799  * have events pending.
 800  */
 801 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 802 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 803 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 804
 805 /* ARGSUSED */
 806 static void
 807 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 808 {
 809         FD_SET(c->sock, readset);
 810 }
 811
 812 /* ARGSUSED */
 813 static void
 814 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 815 {
 816         debug3("channel %d: waiting for connection", c->self);
 817         FD_SET(c->sock, writeset);
 818 }
 819
 820 static void
 821 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 822 {
 823         if (buffer_len(&c->input) < packet_get_maxsize())
 824                 FD_SET(c->sock, readset);
 825         if (buffer_len(&c->output) > 0)
 826                 FD_SET(c->sock, writeset);
 827 }
 828
 829 static u_int
 830 channel_tcpwinsz(void)
 831 {
 832         u_int32_t tcpwinsz;
 833         socklen_t optsz;
 834         int ret, sd;
 835         u_int maxlen;
 836
 837         /* If we are not on a socket return 128KB. */
 838         if (!packet_connection_is_on_socket())
 839                 return (128 * 1024);
 840
 841         tcpwinsz = 0;
 842         optsz = sizeof(tcpwinsz);
 843         sd = packet_get_connection_in();
 844         ret = getsockopt(sd, SOL_SOCKET, SO_RCVBUF, &tcpwinsz, &optsz);
 845
 846         /* Return no more than the maximum buffer size. */
 847         maxlen = buffer_get_max_len();
 848         if ((ret == 0) && tcpwinsz > maxlen)
 849                 tcpwinsz = maxlen;
 850         /* In case getsockopt() failed return a minimum. */
 851         if (tcpwinsz == 0)
 852                 tcpwinsz = CHAN_TCP_WINDOW_DEFAULT;
 853         debug2("tcpwinsz: %d for connection: %d", tcpwinsz, sd);
 854         return (tcpwinsz);
 855 }
 856
 857 static void
 858 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 859 {
 860         u_int limit;
 861
 862         /* Check buffer limits. */
 863         if (!c->tcpwinsz || c->dynamic_window > 0)
 864                 c->tcpwinsz = channel_tcpwinsz();
 865
 866         limit = MIN(compat20 ? c->remote_window : packet_get_maxsize(),
 867             2 * c->tcpwinsz);
 868
 869         if (c->istate == CHAN_INPUT_OPEN &&
 870             limit > 0 &&
 871             buffer_len(&c->input) < limit &&
 872             buffer_check_alloc(&c->input, CHAN_RBUF))
 873                 FD_SET(c->rfd, readset);
 874         if (c->ostate == CHAN_OUTPUT_OPEN ||
 875             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 876                 if (buffer_len(&c->output) > 0) {
 877                         FD_SET(c->wfd, writeset);
 878                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 879                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 880                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 881                                     c->self, c->efd, buffer_len(&c->extended));
 882                         else
 883                                 chan_obuf_empty(c);
 884                 }
 885         }
 886         /** XXX check close conditions, too */
 887         if (compat20 && c->efd != -1 &&
 888             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 889                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 890                     buffer_len(&c->extended) > 0)
 891                         FD_SET(c->efd, writeset);
 892                 else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
 893                     (c->extended_usage == CHAN_EXTENDED_READ ||
 894                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
 895                     buffer_len(&c->extended) < c->remote_window)
 896                         FD_SET(c->efd, readset);
 897         }
 898         /* XXX: What about efd? races? */
 899 }
 900
 901 /* ARGSUSED */
 902 static void
 903 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 904 {
 905         if (buffer_len(&c->input) == 0) {
 906                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 907                 packet_put_int(c->remote_id);
 908                 packet_send();
 909                 c->type = SSH_CHANNEL_CLOSED;
 910                 debug2("channel %d: closing after input drain.", c->self);
 911         }
 912 }
 913
 914 /* ARGSUSED */
 915 static void
 916 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 917 {
 918         if (buffer_len(&c->output) == 0)
 919                 chan_mark_dead(c);
 920         else
 921                 FD_SET(c->sock, writeset);
 922 }
 923
 924 /*
 925  * This is a special state for X11 authentication spoofing.  An opened X11
 926  * connection (when authentication spoofing is being done) remains in this
 927  * state until the first packet has been completely read.  The authentication
 928  * data in that packet is then substituted by the real data if it matches the
 929  * fake data, and the channel is put into normal mode.
 930  * XXX All this happens at the client side.
 931  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 932  */
 933 static int
 934 x11_open_helper(Buffer *b)
 935 {
 936         u_char *ucp;
 937         u_int proto_len, data_len;
 938
 939         /* Check if the fixed size part of the packet is in buffer. */
 940         if (buffer_len(b) < 12)
 941                 return 0;
 942
 943         /* Parse the lengths of variable-length fields. */
 944         ucp = buffer_ptr(b);
 945         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 946                 proto_len = 256 * ucp[6] + ucp[7];
 947                 data_len = 256 * ucp[8] + ucp[9];
 948         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 949                 proto_len = ucp[6] + 256 * ucp[7];
 950                 data_len = ucp[8] + 256 * ucp[9];
 951         } else {
 952                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 953                     ucp[0]);
 954                 return -1;
 955         }
 956
 957         /* Check if the whole packet is in buffer. */
 958         if (buffer_len(b) <
 959             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 960                 return 0;
 961
 962         /* Check if authentication protocol matches. */
 963         if (proto_len != strlen(x11_saved_proto) ||
 964             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 965                 debug2("X11 connection uses different authentication protocol.");
 966                 return -1;
 967         }
 968         /* Check if authentication data matches our fake data. */
 969         if (data_len != x11_fake_data_len ||
 970             timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
 971                 x11_fake_data, x11_fake_data_len) != 0) {
 972                 debug2("X11 auth data does not match fake data.");
 973                 return -1;
 974         }
 975         /* Check fake data length */
 976         if (x11_fake_data_len != x11_saved_data_len) {
 977                 error("X11 fake_data_len %d != saved_data_len %d",
 978                     x11_fake_data_len, x11_saved_data_len);
 979                 return -1;
 980         }
 981         /*
 982          * Received authentication protocol and data match
 983          * our fake data. Substitute the fake data with real
 984          * data.
 985          */
 986         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 987             x11_saved_data, x11_saved_data_len);
 988         return 1;
 989 }
 990
 991 static void
 992 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 993 {
 994         int ret = x11_open_helper(&c->output);
 995
 996         if (ret == 1) {
 997                 /* Start normal processing for the channel. */
 998                 c->type = SSH_CHANNEL_OPEN;
 999                 channel_pre_open_13(c, readset, writeset);
1000         } else if (ret == -1) {
1001                 /*
1002                  * We have received an X11 connection that has bad
1003                  * authentication information.
1004                  */
1005                 logit("X11 connection rejected because of wrong authentication.");
1006                 buffer_clear(&c->input);
1007                 buffer_clear(&c->output);
1008                 channel_close_fd(&c->sock);
1009                 c->sock = -1;
1010                 c->type = SSH_CHANNEL_CLOSED;
1011                 packet_start(SSH_MSG_CHANNEL_CLOSE);
1012                 packet_put_int(c->remote_id);
1013                 packet_send();
1014         }
1015 }
1016
1017 static void
1018 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
1019 {
1020         int ret = x11_open_helper(&c->output);
1021
1022         /* c->force_drain = 1; */
1023
1024         if (ret == 1) {
1025                 c->type = SSH_CHANNEL_OPEN;
1026                 channel_pre_open(c, readset, writeset);
1027         } else if (ret == -1) {
1028                 logit("X11 connection rejected because of wrong authentication.");
1029                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
1030                 chan_read_failed(c);
1031                 buffer_clear(&c->input);
1032                 chan_ibuf_empty(c);
1033                 buffer_clear(&c->output);
1034                 /* for proto v1, the peer will send an IEOF */
1035                 if (compat20)
1036                         chan_write_failed(c);
1037                 else
1038                         c->type = SSH_CHANNEL_OPEN;
1039                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
1040         }
1041 }
1042
1043 static void
1044 channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1045 {
1046         if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
1047             buffer_check_alloc(&c->input, CHAN_RBUF))
1048                 FD_SET(c->rfd, readset);
1049         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1050                 /* clear buffer immediately (discard any partial packet) */
1051                 buffer_clear(&c->input);
1052                 chan_ibuf_empty(c);
1053                 /* Start output drain. XXX just kill chan? */
1054                 chan_rcvd_oclose(c);
1055         }
1056         if (c->ostate == CHAN_OUTPUT_OPEN ||
1057             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
1058                 if (buffer_len(&c->output) > 0)
1059                         FD_SET(c->wfd, writeset);
1060                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
1061                         chan_obuf_empty(c);
1062         }
1063 }
1064
1065 /* try to decode a socks4 header */
1066 /* ARGSUSED */
1067 static int
1068 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1069 {
1070         char *p, *host;
1071         u_int len, have, i, found, need;
1072         char username[256];
1073         struct {
1074                 u_int8_t version;
1075                 u_int8_t command;
1076                 u_int16_t dest_port;
1077                 struct in_addr dest_addr;
1078         } s4_req, s4_rsp;
1079
1080         debug2("channel %d: decode socks4", c->self);
1081
1082         have = buffer_len(&c->input);
1083         len = sizeof(s4_req);
1084         if (have < len)
1085                 return 0;
1086         p = buffer_ptr(&c->input);
1087
1088         need = 1;
1089         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1090         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1091                 debug2("channel %d: socks4a request", c->self);
1092                 /* ... and needs an extra string (the hostname) */
1093                 need = 2;
1094         }
1095         /* Check for terminating NUL on the string(s) */
1096         for (found = 0, i = len; i < have; i++) {
1097                 if (p[i] == '\0') {
1098                         found++;
1099                         if (found == need)
1100                                 break;
1101                 }
1102                 if (i > 1024) {
1103                         /* the peer is probably sending garbage */
1104                         debug("channel %d: decode socks4: too long",
1105                             c->self);
1106                         return -1;
1107                 }
1108         }
1109         if (found < need)
1110                 return 0;
1111         buffer_get(&c->input, (char *)&s4_req.version, 1);
1112         buffer_get(&c->input, (char *)&s4_req.command, 1);
1113         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1114         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1115         have = buffer_len(&c->input);
1116         p = buffer_ptr(&c->input);
1117         len = strlen(p);
1118         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1119         len++;                                  /* trailing '\0' */
1120         if (len > have)
1121                 fatal("channel %d: decode socks4: len %d > have %d",
1122                     c->self, len, have);
1123         strlcpy(username, p, sizeof(username));
1124         buffer_consume(&c->input, len);
1125
1126         free(c->path);
1127         c->path = NULL;
1128         if (need == 1) {                        /* SOCKS4: one string */
1129                 host = inet_ntoa(s4_req.dest_addr);
1130                 c->path = xstrdup(host);
1131         } else {                                /* SOCKS4A: two strings */
1132                 have = buffer_len(&c->input);
1133                 p = buffer_ptr(&c->input);
1134                 len = strlen(p);
1135                 debug2("channel %d: decode socks4a: host %s/%d",
1136                     c->self, p, len);
1137                 len++;                          /* trailing '\0' */
1138                 if (len > have)
1139                         fatal("channel %d: decode socks4a: len %d > have %d",
1140                             c->self, len, have);
1141                 if (len > NI_MAXHOST) {
1142                         error("channel %d: hostname \"%.100s\" too long",
1143                             c->self, p);
1144                         return -1;
1145                 }
1146                 c->path = xstrdup(p);
1147                 buffer_consume(&c->input, len);
1148         }
1149         c->host_port = ntohs(s4_req.dest_port);
1150
1151         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1152             c->self, c->path, c->host_port, s4_req.command);
1153
1154         if (s4_req.command != 1) {
1155                 debug("channel %d: cannot handle: %s cn %d",
1156                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1157                 return -1;
1158         }
1159         s4_rsp.version = 0;                     /* vn: 0 for reply */
1160         s4_rsp.command = 90;                    /* cd: req granted */
1161         s4_rsp.dest_port = 0;                   /* ignored */
1162         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1163         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1164         return 1;
1165 }
1166
1167 /* try to decode a socks5 header */
1168 #define SSH_SOCKS5_AUTHDONE     0x1000
1169 #define SSH_SOCKS5_NOAUTH       0x00
1170 #define SSH_SOCKS5_IPV4         0x01
1171 #define SSH_SOCKS5_DOMAIN       0x03
1172 #define SSH_SOCKS5_IPV6         0x04
1173 #define SSH_SOCKS5_CONNECT      0x01
1174 #define SSH_SOCKS5_SUCCESS      0x00
1175
1176 /* ARGSUSED */
1177 static int
1178 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1179 {
1180         struct {
1181                 u_int8_t version;
1182                 u_int8_t command;
1183                 u_int8_t reserved;
1184                 u_int8_t atyp;
1185         } s5_req, s5_rsp;
1186         u_int16_t dest_port;
1187         char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1188         u_char *p;
1189         u_int have, need, i, found, nmethods, addrlen, af;
1190
1191         debug2("channel %d: decode socks5", c->self);
1192         p = buffer_ptr(&c->input);
1193         if (p[0] != 0x05)
1194                 return -1;
1195         have = buffer_len(&c->input);
1196         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1197                 /* format: ver | nmethods | methods */
1198                 if (have < 2)
1199                         return 0;
1200                 nmethods = p[1];
1201                 if (have < nmethods + 2)
1202                         return 0;
1203                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1204                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1205                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1206                                 found = 1;
1207                                 break;
1208                         }
1209                 }
1210                 if (!found) {
1211                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1212                             c->self);
1213                         return -1;
1214                 }
1215                 buffer_consume(&c->input, nmethods + 2);
1216                 buffer_put_char(&c->output, 0x05);              /* version */
1217                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1218                 FD_SET(c->sock, writeset);
1219                 c->flags |= SSH_SOCKS5_AUTHDONE;
1220                 debug2("channel %d: socks5 auth done", c->self);
1221                 return 0;                               /* need more */
1222         }
1223         debug2("channel %d: socks5 post auth", c->self);
1224         if (have < sizeof(s5_req)+1)
1225                 return 0;                       /* need more */
1226         memcpy(&s5_req, p, sizeof(s5_req));
1227         if (s5_req.version != 0x05 ||
1228             s5_req.command != SSH_SOCKS5_CONNECT ||
1229             s5_req.reserved != 0x00) {
1230                 debug2("channel %d: only socks5 connect supported", c->self);
1231                 return -1;
1232         }
1233         switch (s5_req.atyp){
1234         case SSH_SOCKS5_IPV4:
1235                 addrlen = 4;
1236                 af = AF_INET;
1237                 break;
1238         case SSH_SOCKS5_DOMAIN:
1239                 addrlen = p[sizeof(s5_req)];
1240                 af = -1;
1241                 break;
1242         case SSH_SOCKS5_IPV6:
1243                 addrlen = 16;
1244                 af = AF_INET6;
1245                 break;
1246         default:
1247                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1248                 return -1;
1249         }
1250         need = sizeof(s5_req) + addrlen + 2;
1251         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1252                 need++;
1253         if (have < need)
1254                 return 0;
1255         buffer_consume(&c->input, sizeof(s5_req));
1256         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1257                 buffer_consume(&c->input, 1);    /* host string length */
1258         buffer_get(&c->input, &dest_addr, addrlen);
1259         buffer_get(&c->input, (char *)&dest_port, 2);
1260         dest_addr[addrlen] = '\0';
1261         free(c->path);
1262         c->path = NULL;
1263         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1264                 if (addrlen >= NI_MAXHOST) {
1265                         error("channel %d: dynamic request: socks5 hostname "
1266                             "\"%.100s\" too long", c->self, dest_addr);
1267                         return -1;
1268                 }
1269                 c->path = xstrdup(dest_addr);
1270         } else {
1271                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1272                         return -1;
1273                 c->path = xstrdup(ntop);
1274         }
1275         c->host_port = ntohs(dest_port);
1276
1277         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1278             c->self, c->path, c->host_port, s5_req.command);
1279
1280         s5_rsp.version = 0x05;
1281         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1282         s5_rsp.reserved = 0;                    /* ignored */
1283         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1284         dest_port = 0;                          /* ignored */
1285
1286         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1287         buffer_put_int(&c->output, ntohl(INADDR_ANY)); /* bind address */
1288         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1289         return 1;
1290 }
1291
1292 Channel *
1293 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1294     int in, int out)
1295 {
1296         Channel *c;
1297
1298         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1299             port_to_connect);
1300
1301         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1302             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1303             0, "stdio-forward", /*nonblock*/0);
1304
1305         c->path = xstrdup(host_to_connect);
1306         c->host_port = port_to_connect;
1307         c->listening_port = 0;
1308         c->force_drain = 1;
1309
1310         channel_register_fds(c, in, out, -1, 0, 1, 0);
1311         port_open_helper(c, "direct-tcpip");
1312
1313         return c;
1314 }
1315
1316 /* dynamic port forwarding */
1317 static void
1318 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1319 {
1320         u_char *p;
1321         u_int have;
1322         int ret;
1323
1324         have = buffer_len(&c->input);
1325         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1326         /* buffer_dump(&c->input); */
1327         /* check if the fixed size part of the packet is in buffer. */
1328         if (have < 3) {
1329                 /* need more */
1330                 FD_SET(c->sock, readset);
1331                 return;
1332         }
1333         /* try to guess the protocol */
1334         p = buffer_ptr(&c->input);
1335         switch (p[0]) {
1336         case 0x04:
1337                 ret = channel_decode_socks4(c, readset, writeset);
1338                 break;
1339         case 0x05:
1340                 ret = channel_decode_socks5(c, readset, writeset);
1341                 break;
1342         default:
1343                 ret = -1;
1344                 break;
1345         }
1346         if (ret < 0) {
1347                 chan_mark_dead(c);
1348         } else if (ret == 0) {
1349                 debug2("channel %d: pre_dynamic: need more", c->self);
1350                 /* need more */
1351                 FD_SET(c->sock, readset);
1352         } else {
1353                 /* switch to the next state */
1354                 c->type = SSH_CHANNEL_OPENING;
1355                 port_open_helper(c, "direct-tcpip");
1356         }
1357 }
1358
1359 /* This is our fake X11 server socket. */
1360 /* ARGSUSED */
1361 static void
1362 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1363 {
1364         Channel *nc;
1365         struct sockaddr_storage addr;
1366         int newsock, oerrno;
1367         socklen_t addrlen;
1368         char buf[16384], *remote_ipaddr;
1369         int remote_port;
1370
1371         if (FD_ISSET(c->sock, readset)) {
1372                 debug("X11 connection requested.");
1373                 addrlen = sizeof(addr);
1374                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1375                 if (c->single_connection) {
1376                         oerrno = errno;
1377                         debug2("single_connection: closing X11 listener.");
1378                         channel_close_fd(&c->sock);
1379                         chan_mark_dead(c);
1380                         errno = oerrno;
1381                 }
1382                 if (newsock < 0) {
1383                         if (errno != EINTR && errno != EWOULDBLOCK &&
1384                             errno != ECONNABORTED)
1385                                 error("accept: %.100s", strerror(errno));
1386                         if (errno == EMFILE || errno == ENFILE)
1387                                 c->notbefore = monotime() + 1;
1388                         return;
1389                 }
1390                 set_nodelay(newsock);
1391                 remote_ipaddr = get_peer_ipaddr(newsock);
1392                 remote_port = get_peer_port(newsock);
1393                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1394                     remote_ipaddr, remote_port);
1395
1396                 nc = channel_new("accepted x11 socket",
1397                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1398                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1399                 if (compat20) {
1400                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1401                         packet_put_cstring("x11");
1402                         packet_put_int(nc->self);
1403                         packet_put_int(nc->local_window_max);
1404                         packet_put_int(nc->local_maxpacket);
1405                         /* originator ipaddr and port */
1406                         packet_put_cstring(remote_ipaddr);
1407                         if (datafellows & SSH_BUG_X11FWD) {
1408                                 debug2("ssh2 x11 bug compat mode");
1409                         } else {
1410                                 packet_put_int(remote_port);
1411                         }
1412                         packet_send();
1413                 } else {
1414                         packet_start(SSH_SMSG_X11_OPEN);
1415                         packet_put_int(nc->self);
1416                         if (packet_get_protocol_flags() &
1417                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1418                                 packet_put_cstring(buf);
1419                         packet_send();
1420                 }
1421                 free(remote_ipaddr);
1422         }
1423 }
1424
1425 static void
1426 port_open_helper(Channel *c, char *rtype)
1427 {
1428         int direct;
1429         char buf[1024];
1430         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1431         int remote_port = get_peer_port(c->sock);
1432
1433         if (remote_port == -1) {
1434                 /* Fake addr/port to appease peers that validate it (Tectia) */
1435                 free(remote_ipaddr);
1436                 remote_ipaddr = xstrdup("127.0.0.1");
1437                 remote_port = 65535;
1438         }
1439
1440         direct = (strcmp(rtype, "direct-tcpip") == 0);
1441
1442         snprintf(buf, sizeof buf,
1443             "%s: listening port %d for %.100s port %d, "
1444             "connect from %.200s port %d",
1445             rtype, c->listening_port, c->path, c->host_port,
1446             remote_ipaddr, remote_port);
1447
1448         free(c->remote_name);
1449         c->remote_name = xstrdup(buf);
1450
1451         if (compat20) {
1452                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1453                 packet_put_cstring(rtype);
1454                 packet_put_int(c->self);
1455                 packet_put_int(c->local_window_max);
1456                 packet_put_int(c->local_maxpacket);
1457                 if (direct) {
1458                         /* target host, port */
1459                         packet_put_cstring(c->path);
1460                         packet_put_int(c->host_port);
1461                 } else {
1462                         /* listen address, port */
1463                         packet_put_cstring(c->path);
1464                         packet_put_int(c->listening_port);
1465                 }
1466                 /* originator host and port */
1467                 packet_put_cstring(remote_ipaddr);
1468                 packet_put_int((u_int)remote_port);
1469                 packet_send();
1470         } else {
1471                 packet_start(SSH_MSG_PORT_OPEN);
1472                 packet_put_int(c->self);
1473                 packet_put_cstring(c->path);
1474                 packet_put_int(c->host_port);
1475                 if (packet_get_protocol_flags() &
1476                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1477                         packet_put_cstring(c->remote_name);
1478                 packet_send();
1479         }
1480         free(remote_ipaddr);
1481 }
1482
1483 static void
1484 channel_set_reuseaddr(int fd)
1485 {
1486         int on = 1;
1487
1488         /*
1489          * Set socket options.
1490          * Allow local port reuse in TIME_WAIT.
1491          */
1492         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1493                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1494 }
1495
1496 /*
1497  * This socket is listening for connections to a forwarded TCP/IP port.
1498  */
1499 /* ARGSUSED */
1500 static void
1501 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1502 {
1503         Channel *nc;
1504         struct sockaddr_storage addr;
1505         int newsock, nextstate;
1506         socklen_t addrlen;
1507         char *rtype;
1508
1509         if (FD_ISSET(c->sock, readset)) {
1510                 debug("Connection to port %d forwarding "
1511                     "to %.100s port %d requested.",
1512                     c->listening_port, c->path, c->host_port);
1513
1514                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1515                         nextstate = SSH_CHANNEL_OPENING;
1516                         rtype = "forwarded-tcpip";
1517                 } else {
1518                         if (c->host_port == 0) {
1519                                 nextstate = SSH_CHANNEL_DYNAMIC;
1520                                 rtype = "dynamic-tcpip";
1521                         } else {
1522                                 nextstate = SSH_CHANNEL_OPENING;
1523                                 rtype = "direct-tcpip";
1524                         }
1525                 }
1526
1527                 addrlen = sizeof(addr);
1528                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1529                 if (newsock < 0) {
1530                         if (errno != EINTR && errno != EWOULDBLOCK &&
1531                             errno != ECONNABORTED)
1532                                 error("accept: %.100s", strerror(errno));
1533                         if (errno == EMFILE || errno == ENFILE)
1534                                 c->notbefore = monotime() + 1;
1535                         return;
1536                 }
1537                 set_nodelay(newsock);
1538                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1539                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1540                 nc->listening_port = c->listening_port;
1541                 nc->host_port = c->host_port;
1542                 if (c->path != NULL)
1543                         nc->path = xstrdup(c->path);
1544
1545                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1546                         port_open_helper(nc, rtype);
1547         }
1548 }
1549
1550 /*
1551  * This is the authentication agent socket listening for connections from
1552  * clients.
1553  */
1554 /* ARGSUSED */
1555 static void
1556 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1557 {
1558         Channel *nc;
1559         int newsock;
1560         struct sockaddr_storage addr;
1561         socklen_t addrlen;
1562
1563         if (FD_ISSET(c->sock, readset)) {
1564                 addrlen = sizeof(addr);
1565                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1566                 if (newsock < 0) {
1567                         error("accept from auth socket: %.100s",
1568                             strerror(errno));
1569                         if (errno == EMFILE || errno == ENFILE)
1570                                 c->notbefore = monotime() + 1;
1571                         return;
1572                 }
1573                 nc = channel_new("accepted auth socket",
1574                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1575                     c->local_window_max, c->local_maxpacket,
1576                     0, "accepted auth socket", 1);
1577                 if (compat20) {
1578                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1579                         packet_put_cstring("auth-agent@openssh.com");
1580                         packet_put_int(nc->self);
1581                         packet_put_int(c->local_window_max);
1582                         packet_put_int(c->local_maxpacket);
1583                 } else {
1584                         packet_start(SSH_SMSG_AGENT_OPEN);
1585                         packet_put_int(nc->self);
1586                 }
1587                 packet_send();
1588         }
1589 }
1590
1591 /* ARGSUSED */
1592 static void
1593 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1594 {
1595         int err = 0, sock;
1596         socklen_t sz = sizeof(err);
1597
1598         if (FD_ISSET(c->sock, writeset)) {
1599                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1600                         err = errno;
1601                         error("getsockopt SO_ERROR failed");
1602                 }
1603                 if (err == 0) {
1604                         debug("channel %d: connected to %s port %d",
1605                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1606                         channel_connect_ctx_free(&c->connect_ctx);
1607                         c->type = SSH_CHANNEL_OPEN;
1608                         if (compat20) {
1609                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1610                                 packet_put_int(c->remote_id);
1611                                 packet_put_int(c->self);
1612                                 packet_put_int(c->local_window);
1613                                 packet_put_int(c->local_maxpacket);
1614                         } else {
1615                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1616                                 packet_put_int(c->remote_id);
1617                                 packet_put_int(c->self);
1618                         }
1619                 } else {
1620                         debug("channel %d: connection failed: %s",
1621                             c->self, strerror(err));
1622                         /* Try next address, if any */
1623                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1624                                 close(c->sock);
1625                                 c->sock = c->rfd = c->wfd = sock;
1626                                 channel_max_fd = channel_find_maxfd();
1627                                 return;
1628                         }
1629                         /* Exhausted all addresses */
1630                         error("connect_to %.100s port %d: failed.",
1631                             c->connect_ctx.host, c->connect_ctx.port);
1632                         channel_connect_ctx_free(&c->connect_ctx);
1633                         if (compat20) {
1634                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1635                                 packet_put_int(c->remote_id);
1636                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1637                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1638                                         packet_put_cstring(strerror(err));
1639                                         packet_put_cstring("");
1640                                 }
1641                         } else {
1642                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1643                                 packet_put_int(c->remote_id);
1644                         }
1645                         chan_mark_dead(c);
1646                 }
1647                 packet_send();
1648         }
1649 }
1650
1651 /* ARGSUSED */
1652 static int
1653 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1654 {
1655         char buf[CHAN_RBUF];
1656         int len, force;
1657
1658         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1659         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1660                 errno = 0;
1661                 len = read(c->rfd, buf, sizeof(buf));
1662                 if (len < 0 && (errno == EINTR ||
1663                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1664                         return 1;
1665 #ifndef PTY_ZEROREAD
1666                 if (len <= 0) {
1667 #else
1668                 if ((!c->isatty && len <= 0) ||
1669                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1670 #endif
1671                         debug2("channel %d: read<=0 rfd %d len %d",
1672                             c->self, c->rfd, len);
1673                         if (c->type != SSH_CHANNEL_OPEN) {
1674                                 debug2("channel %d: not open", c->self);
1675                                 chan_mark_dead(c);
1676                                 return -1;
1677                         } else if (compat13) {
1678                                 buffer_clear(&c->output);
1679                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1680                                 debug2("channel %d: input draining.", c->self);
1681                         } else {
1682                                 chan_read_failed(c);
1683                         }
1684                         return -1;
1685                 }
1686                 if (c->input_filter != NULL) {
1687                         if (c->input_filter(c, buf, len) == -1) {
1688                                 debug2("channel %d: filter stops", c->self);
1689                                 chan_read_failed(c);
1690                         }
1691                 } else if (c->datagram) {
1692                         buffer_put_string(&c->input, buf, len);
1693                 } else {
1694                         buffer_append(&c->input, buf, len);
1695                 }
1696         }
1697         return 1;
1698 }
1699
1700 /* ARGSUSED */
1701 static int
1702 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1703 {
1704         struct termios tio;
1705         u_char *data = NULL, *buf;
1706         u_int dlen, olen = 0;
1707         int len;
1708
1709         /* Send buffered output data to the socket. */
1710         if (c->wfd != -1 &&
1711             FD_ISSET(c->wfd, writeset) &&
1712             buffer_len(&c->output) > 0) {
1713                 olen = buffer_len(&c->output);
1714                 if (c->output_filter != NULL) {
1715                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1716                                 debug2("channel %d: filter stops", c->self);
1717                                 if (c->type != SSH_CHANNEL_OPEN)
1718                                         chan_mark_dead(c);
1719                                 else
1720                                         chan_write_failed(c);
1721                                 return -1;
1722                         }
1723                 } else if (c->datagram) {
1724                         buf = data = buffer_get_string(&c->output, &dlen);
1725                 } else {
1726                         buf = data = buffer_ptr(&c->output);
1727                         dlen = buffer_len(&c->output);
1728                 }
1729
1730                 if (c->datagram) {
1731                         /* ignore truncated writes, datagrams might get lost */
1732                         len = write(c->wfd, buf, dlen);
1733                         free(data);
1734                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1735                             errno == EWOULDBLOCK))
1736                                 return 1;
1737                         if (len <= 0) {
1738                                 if (c->type != SSH_CHANNEL_OPEN)
1739                                         chan_mark_dead(c);
1740                                 else
1741                                         chan_write_failed(c);
1742                                 return -1;
1743                         }
1744                         goto out;
1745                 }
1746 #ifdef _AIX
1747                 /* XXX: Later AIX versions can't push as much data to tty */
1748                 if (compat20 && c->wfd_isatty)
1749                         dlen = MIN(dlen, 8*1024);
1750 #endif
1751
1752                 len = write(c->wfd, buf, dlen);
1753                 if (len < 0 &&
1754                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1755                         return 1;
1756                 if (len <= 0) {
1757                         if (c->type != SSH_CHANNEL_OPEN) {
1758                                 debug2("channel %d: not open", c->self);
1759                                 chan_mark_dead(c);
1760                                 return -1;
1761                         } else if (compat13) {
1762                                 buffer_clear(&c->output);
1763                                 debug2("channel %d: input draining.", c->self);
1764                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1765                         } else {
1766                                 chan_write_failed(c);
1767                         }
1768                         return -1;
1769                 }
1770 #ifndef BROKEN_TCGETATTR_ICANON
1771                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1772                         if (tcgetattr(c->wfd, &tio) == 0 &&
1773                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1774                                 /*
1775                                  * Simulate echo to reduce the impact of
1776                                  * traffic analysis. We need to match the
1777                                  * size of a SSH2_MSG_CHANNEL_DATA message
1778                                  * (4 byte channel id + buf)
1779                                  */
1780                                 packet_send_ignore(4 + len);
1781                                 packet_send();
1782                         }
1783                 }
1784 #endif
1785                 buffer_consume(&c->output, len);
1786         }
1787  out:
1788         if (compat20 && olen > 0)
1789                 c->local_consumed += olen - buffer_len(&c->output);
1790         return 1;
1791 }
1792
1793 static int
1794 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1795 {
1796         char buf[CHAN_RBUF];
1797         int len;
1798
1799 /** XXX handle drain efd, too */
1800         if (c->efd != -1) {
1801                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1802                     FD_ISSET(c->efd, writeset) &&
1803                     buffer_len(&c->extended) > 0) {
1804                         len = write(c->efd, buffer_ptr(&c->extended),
1805                             buffer_len(&c->extended));
1806                         debug2("channel %d: written %d to efd %d",
1807                             c->self, len, c->efd);
1808                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1809                             errno == EWOULDBLOCK))
1810                                 return 1;
1811                         if (len <= 0) {
1812                                 debug2("channel %d: closing write-efd %d",
1813                                     c->self, c->efd);
1814                                 channel_close_fd(&c->efd);
1815                         } else {
1816                                 buffer_consume(&c->extended, len);
1817                                 c->local_consumed += len;
1818                         }
1819                 } else if (c->efd != -1 &&
1820                     (c->extended_usage == CHAN_EXTENDED_READ ||
1821                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
1822                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1823                         len = read(c->efd, buf, sizeof(buf));
1824                         debug2("channel %d: read %d from efd %d",
1825                             c->self, len, c->efd);
1826                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1827                             errno == EWOULDBLOCK) && !c->detach_close)))
1828                                 return 1;
1829                         if (len <= 0) {
1830                                 debug2("channel %d: closing read-efd %d",
1831                                     c->self, c->efd);
1832                                 channel_close_fd(&c->efd);
1833                         } else {
1834                                 if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
1835                                         debug3("channel %d: discard efd",
1836                                             c->self);
1837                                 } else
1838                                         buffer_append(&c->extended, buf, len);
1839                         }
1840                 }
1841         }
1842         return 1;
1843 }
1844
1845 static int
1846 channel_check_window(Channel *c)
1847 {
1848         if (c->type == SSH_CHANNEL_OPEN &&
1849             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1850             ((c->local_window_max - c->local_window >
1851             c->local_maxpacket*3) ||
1852             c->local_window < c->local_window_max/2) &&
1853             c->local_consumed > 0) {
1854                 u_int addition = 0;
1855
1856                 /* Adjust max window size if we are in a dynamic environment. */
1857                 if (c->dynamic_window && c->tcpwinsz > c->local_window_max) {
1858                         /*
1859                          * Grow the window somewhat aggressively to maintain
1860                          * pressure.
1861                          */
1862                         addition = 1.5 * (c->tcpwinsz - c->local_window_max);
1863                         c->local_window_max += addition;
1864                 }
1865                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1866                 packet_put_int(c->remote_id);
1867                 packet_put_int(c->local_consumed + addition);
1868                 packet_send();
1869                 debug2("channel %d: window %d sent adjust %d",
1870                     c->self, c->local_window,
1871                     c->local_consumed);
1872                 c->local_window += c->local_consumed + addition;
1873                 c->local_consumed = 0;
1874         }
1875         return 1;
1876 }
1877
1878 static void
1879 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1880 {
1881         channel_handle_rfd(c, readset, writeset);
1882         channel_handle_wfd(c, readset, writeset);
1883         if (!compat20)
1884                 return;
1885         channel_handle_efd(c, readset, writeset);
1886         channel_check_window(c);
1887 }
1888
1889 static u_int
1890 read_mux(Channel *c, u_int need)
1891 {
1892         char buf[CHAN_RBUF];
1893         int len;
1894         u_int rlen;
1895
1896         if (buffer_len(&c->input) < need) {
1897                 rlen = need - buffer_len(&c->input);
1898                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1899                 if (len <= 0) {
1900                         if (errno != EINTR && errno != EAGAIN) {
1901                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1902                                     c->self, c->rfd, len);
1903                                 chan_read_failed(c);
1904                                 return 0;
1905                         }
1906                 } else
1907                         buffer_append(&c->input, buf, len);
1908         }
1909         return buffer_len(&c->input);
1910 }
1911
1912 static void
1913 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1914 {
1915         u_int need;
1916         ssize_t len;
1917
1918         if (!compat20)
1919                 fatal("%s: entered with !compat20", __func__);
1920
1921         if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
1922             (c->istate == CHAN_INPUT_OPEN ||
1923             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1924                 /*
1925                  * Don't not read past the precise end of packets to
1926                  * avoid disrupting fd passing.
1927                  */
1928                 if (read_mux(c, 4) < 4) /* read header */
1929                         return;
1930                 need = get_u32(buffer_ptr(&c->input));
1931 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1932                 if (need > CHANNEL_MUX_MAX_PACKET) {
1933                         debug2("channel %d: packet too big %u > %u",
1934                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1935                         chan_rcvd_oclose(c);
1936                         return;
1937                 }
1938                 if (read_mux(c, need + 4) < need + 4) /* read body */
1939                         return;
1940                 if (c->mux_rcb(c) != 0) {
1941                         debug("channel %d: mux_rcb failed", c->self);
1942                         chan_mark_dead(c);
1943                         return;
1944                 }
1945         }
1946
1947         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1948             buffer_len(&c->output) > 0) {
1949                 len = write(c->wfd, buffer_ptr(&c->output),
1950                     buffer_len(&c->output));
1951                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1952                         return;
1953                 if (len <= 0) {
1954                         chan_mark_dead(c);
1955                         return;
1956                 }
1957                 buffer_consume(&c->output, len);
1958         }
1959 }
1960
1961 static void
1962 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1963 {
1964         Channel *nc;
1965         struct sockaddr_storage addr;
1966         socklen_t addrlen;
1967         int newsock;
1968         uid_t euid;
1969         gid_t egid;
1970
1971         if (!FD_ISSET(c->sock, readset))
1972                 return;
1973
1974         debug("multiplexing control connection");
1975
1976         /*
1977          * Accept connection on control socket
1978          */
1979         memset(&addr, 0, sizeof(addr));
1980         addrlen = sizeof(addr);
1981         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1982             &addrlen)) == -1) {
1983                 error("%s accept: %s", __func__, strerror(errno));
1984                 if (errno == EMFILE || errno == ENFILE)
1985                         c->notbefore = monotime() + 1;
1986                 return;
1987         }
1988
1989         if (getpeereid(newsock, &euid, &egid) < 0) {
1990                 error("%s getpeereid failed: %s", __func__,
1991                     strerror(errno));
1992                 close(newsock);
1993                 return;
1994         }
1995         if ((euid != 0) && (getuid() != euid)) {
1996                 error("multiplex uid mismatch: peer euid %u != uid %u",
1997                     (u_int)euid, (u_int)getuid());
1998                 close(newsock);
1999                 return;
2000         }
2001         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
2002             newsock, newsock, -1, c->local_window_max,
2003             c->local_maxpacket, 0, "mux-control", 1);
2004         nc->mux_rcb = c->mux_rcb;
2005         debug3("%s: new mux channel %d fd %d", __func__,
2006             nc->self, nc->sock);
2007         /* establish state */
2008         nc->mux_rcb(nc);
2009         /* mux state transitions must not elicit protocol messages */
2010         nc->flags |= CHAN_LOCAL;
2011 }
2012
2013 /* ARGSUSED */
2014 static void
2015 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
2016 {
2017         int len;
2018
2019         /* Send buffered output data to the socket. */
2020         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
2021                 len = write(c->sock, buffer_ptr(&c->output),
2022                             buffer_len(&c->output));
2023                 if (len <= 0)
2024                         buffer_clear(&c->output);
2025                 else
2026                         buffer_consume(&c->output, len);
2027         }
2028 }
2029
2030 static void
2031 channel_handler_init_20(void)
2032 {
2033         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2034         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2035         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2036         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
2037         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2038         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2039         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2040         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2041         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
2042         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
2043
2044         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2045         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2046         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
2047         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2048         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2049         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2050         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2051         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
2052         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
2053 }
2054
2055 static void
2056 channel_handler_init_13(void)
2057 {
2058         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
2059         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
2060         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2061         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2062         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2063         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
2064         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
2065         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2066         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2067
2068         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2069         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2070         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2071         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2072         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
2073         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2074         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2075 }
2076
2077 static void
2078 channel_handler_init_15(void)
2079 {
2080         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2081         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2082         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2083         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2084         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2085         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2086         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2087
2088         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2089         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2090         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2091         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2092         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2093         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2094 }
2095
2096 static void
2097 channel_handler_init(void)
2098 {
2099         int i;
2100
2101         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2102                 channel_pre[i] = NULL;
2103                 channel_post[i] = NULL;
2104         }
2105         if (compat20)
2106                 channel_handler_init_20();
2107         else if (compat13)
2108                 channel_handler_init_13();
2109         else
2110                 channel_handler_init_15();
2111 }
2112
2113 /* gc dead channels */
2114 static void
2115 channel_garbage_collect(Channel *c)
2116 {
2117         if (c == NULL)
2118                 return;
2119         if (c->detach_user != NULL) {
2120                 if (!chan_is_dead(c, c->detach_close))
2121                         return;
2122                 debug2("channel %d: gc: notify user", c->self);
2123                 c->detach_user(c->self, NULL);
2124                 /* if we still have a callback */
2125                 if (c->detach_user != NULL)
2126                         return;
2127                 debug2("channel %d: gc: user detached", c->self);
2128         }
2129         if (!chan_is_dead(c, 1))
2130                 return;
2131         debug2("channel %d: garbage collecting", c->self);
2132         channel_free(c);
2133 }
2134
2135 static void
2136 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
2137     time_t *unpause_secs)
2138 {
2139         static int did_init = 0;
2140         u_int i, oalloc;
2141         Channel *c;
2142         time_t now;
2143
2144         if (!did_init) {
2145                 channel_handler_init();
2146                 did_init = 1;
2147         }
2148         now = monotime();
2149         if (unpause_secs != NULL)
2150                 *unpause_secs = 0;
2151         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2152                 c = channels[i];
2153                 if (c == NULL)
2154                         continue;
2155                 if (c->delayed) {
2156                         if (ftab == channel_pre)
2157                                 c->delayed = 0;
2158                         else
2159                                 continue;
2160                 }
2161                 if (ftab[c->type] != NULL) {
2162                         /*
2163                          * Run handlers that are not paused.
2164                          */
2165                         if (c->notbefore <= now)
2166                                 (*ftab[c->type])(c, readset, writeset);
2167                         else if (unpause_secs != NULL) {
2168                                 /*
2169                                  * Collect the time that the earliest
2170                                  * channel comes off pause.
2171                                  */
2172                                 debug3("%s: chan %d: skip for %d more seconds",
2173                                     __func__, c->self,
2174                                     (int)(c->notbefore - now));
2175                                 if (*unpause_secs == 0 ||
2176                                     (c->notbefore - now) < *unpause_secs)
2177                                         *unpause_secs = c->notbefore - now;
2178                         }
2179                 }
2180                 channel_garbage_collect(c);
2181         }
2182         if (unpause_secs != NULL && *unpause_secs != 0)
2183                 debug3("%s: first channel unpauses in %d seconds",
2184                     __func__, (int)*unpause_secs);
2185 }
2186
2187 /*
2188  * Allocate/update select bitmasks and add any bits relevant to channels in
2189  * select bitmasks.
2190  */
2191 void
2192 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2193     u_int *nallocp, time_t *minwait_secs, int rekeying)
2194 {
2195         u_int n, sz, nfdset;
2196
2197         n = MAX(*maxfdp, channel_max_fd);
2198
2199         nfdset = howmany(n+1, NFDBITS);
2200         /* Explicitly test here, because xrealloc isn't always called */
2201         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
2202                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2203         sz = nfdset * sizeof(fd_mask);
2204
2205         /* perhaps check sz < nalloc/2 and shrink? */
2206         if (*readsetp == NULL || sz > *nallocp) {
2207                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2208                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2209                 *nallocp = sz;
2210         }
2211         *maxfdp = n;
2212         memset(*readsetp, 0, sz);
2213         memset(*writesetp, 0, sz);
2214
2215         if (!rekeying)
2216                 channel_handler(channel_pre, *readsetp, *writesetp,
2217                     minwait_secs);
2218 }
2219
2220 /*
2221  * After select, perform any appropriate operations for channels which have
2222  * events pending.
2223  */
2224 void
2225 channel_after_select(fd_set *readset, fd_set *writeset)
2226 {
2227         channel_handler(channel_post, readset, writeset, NULL);
2228 }
2229
2230
2231 /* If there is data to send to the connection, enqueue some of it now. */
2232 void
2233 channel_output_poll(void)
2234 {
2235         Channel *c;
2236         u_int i, len;
2237
2238         for (i = 0; i < channels_alloc; i++) {
2239                 c = channels[i];
2240                 if (c == NULL)
2241                         continue;
2242
2243                 /*
2244                  * We are only interested in channels that can have buffered
2245                  * incoming data.
2246                  */
2247                 if (compat13) {
2248                         if (c->type != SSH_CHANNEL_OPEN &&
2249                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2250                                 continue;
2251                 } else {
2252                         if (c->type != SSH_CHANNEL_OPEN)
2253                                 continue;
2254                 }
2255                 if (compat20 &&
2256                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2257                         /* XXX is this true? */
2258                         debug3("channel %d: will not send data after close", c->self);
2259                         continue;
2260                 }
2261
2262                 /* Get the amount of buffered data for this channel. */
2263                 if ((c->istate == CHAN_INPUT_OPEN ||
2264                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2265                     (len = buffer_len(&c->input)) > 0) {
2266                         if (c->datagram) {
2267                                 if (len > 0) {
2268                                         u_char *data;
2269                                         u_int dlen;
2270
2271                                         data = buffer_get_string(&c->input,
2272                                             &dlen);
2273                                         if (dlen > c->remote_window ||
2274                                             dlen > c->remote_maxpacket) {
2275                                                 debug("channel %d: datagram "
2276                                                     "too big for channel",
2277                                                     c->self);
2278                                                 free(data);
2279                                                 continue;
2280                                         }
2281                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2282                                         packet_put_int(c->remote_id);
2283                                         packet_put_string(data, dlen);
2284                                         packet_send();
2285                                         c->remote_window -= dlen + 4;
2286                                         free(data);
2287                                 }
2288                                 continue;
2289                         }
2290                         /*
2291                          * Send some data for the other side over the secure
2292                          * connection.
2293                          */
2294                         if (compat20) {
2295                                 if (len > c->remote_window)
2296                                         len = c->remote_window;
2297                                 if (len > c->remote_maxpacket)
2298                                         len = c->remote_maxpacket;
2299                         } else {
2300                                 if (packet_is_interactive()) {
2301                                         if (len > 1024)
2302                                                 len = 512;
2303                                 } else {
2304                                         /* Keep the packets at reasonable size. */
2305                                         if (len > packet_get_maxsize()/2)
2306                                                 len = packet_get_maxsize()/2;
2307                                 }
2308                         }
2309                         if (len > 0) {
2310                                 packet_start(compat20 ?
2311                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2312                                 packet_put_int(c->remote_id);
2313                                 packet_put_string(buffer_ptr(&c->input), len);
2314                                 packet_send();
2315                                 buffer_consume(&c->input, len);
2316                                 c->remote_window -= len;
2317                         }
2318                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2319                         if (compat13)
2320                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2321                         /*
2322                          * input-buffer is empty and read-socket shutdown:
2323                          * tell peer, that we will not send more data: send IEOF.
2324                          * hack for extended data: delay EOF if EFD still in use.
2325                          */
2326                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2327                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2328                                     c->self, c->efd, buffer_len(&c->extended));
2329                         else
2330                                 chan_ibuf_empty(c);
2331                 }
2332                 /* Send extended data, i.e. stderr */
2333                 if (compat20 &&
2334                     !(c->flags & CHAN_EOF_SENT) &&
2335                     c->remote_window > 0 &&
2336                     (len = buffer_len(&c->extended)) > 0 &&
2337                     c->extended_usage == CHAN_EXTENDED_READ) {
2338                         debug2("channel %d: rwin %u elen %u euse %d",
2339                             c->self, c->remote_window, buffer_len(&c->extended),
2340                             c->extended_usage);
2341                         if (len > c->remote_window)
2342                                 len = c->remote_window;
2343                         if (len > c->remote_maxpacket)
2344                                 len = c->remote_maxpacket;
2345                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2346                         packet_put_int(c->remote_id);
2347                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2348                         packet_put_string(buffer_ptr(&c->extended), len);
2349                         packet_send();
2350                         buffer_consume(&c->extended, len);
2351                         c->remote_window -= len;
2352                         debug2("channel %d: sent ext data %d", c->self, len);
2353                 }
2354         }
2355 }
2356
2357
2358 /* -- protocol input */
2359
2360 /* ARGSUSED */
2361 void
2362 channel_input_data(int type, u_int32_t seq, void *ctxt)
2363 {
2364         int id;
2365         char *data;
2366         u_int data_len, win_len;
2367         Channel *c;
2368
2369         /* Get the channel number and verify it. */
2370         id = packet_get_int();
2371         c = channel_lookup(id);
2372         if (c == NULL)
2373                 packet_disconnect("Received data for nonexistent channel %d.", id);
2374
2375         /* Ignore any data for non-open channels (might happen on close) */
2376         if (c->type != SSH_CHANNEL_OPEN &&
2377             c->type != SSH_CHANNEL_X11_OPEN)
2378                 return;
2379
2380         /* Get the data. */
2381         data = packet_get_string_ptr(&data_len);
2382         win_len = data_len;
2383         if (c->datagram)
2384                 win_len += 4;  /* string length header */
2385
2386         /*
2387          * Ignore data for protocol > 1.3 if output end is no longer open.
2388          * For protocol 2 the sending side is reducing its window as it sends
2389          * data, so we must 'fake' consumption of the data in order to ensure
2390          * that window updates are sent back.  Otherwise the connection might
2391          * deadlock.
2392          */
2393         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2394                 if (compat20) {
2395                         c->local_window -= win_len;
2396                         c->local_consumed += win_len;
2397                 }
2398                 return;
2399         }
2400
2401         if (compat20) {
2402                 if (win_len > c->local_maxpacket) {
2403                         logit("channel %d: rcvd big packet %d, maxpack %d",
2404                             c->self, win_len, c->local_maxpacket);
2405                 }
2406                 if (win_len > c->local_window) {
2407                         logit("channel %d: rcvd too much data %d, win %d",
2408                             c->self, win_len, c->local_window);
2409                         return;
2410                 }
2411                 c->local_window -= win_len;
2412         }
2413         if (c->datagram)
2414                 buffer_put_string(&c->output, data, data_len);
2415         else
2416                 buffer_append(&c->output, data, data_len);
2417         packet_check_eom();
2418 }
2419
2420 /* ARGSUSED */
2421 void
2422 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2423 {
2424         int id;
2425         char *data;
2426         u_int data_len, tcode;
2427         Channel *c;
2428
2429         /* Get the channel number and verify it. */
2430         id = packet_get_int();
2431         c = channel_lookup(id);
2432
2433         if (c == NULL)
2434                 packet_disconnect("Received extended_data for bad channel %d.", id);
2435         if (c->type != SSH_CHANNEL_OPEN) {
2436                 logit("channel %d: ext data for non open", id);
2437                 return;
2438         }
2439         if (c->flags & CHAN_EOF_RCVD) {
2440                 if (datafellows & SSH_BUG_EXTEOF)
2441                         debug("channel %d: accepting ext data after eof", id);
2442                 else
2443                         packet_disconnect("Received extended_data after EOF "
2444                             "on channel %d.", id);
2445         }
2446         tcode = packet_get_int();
2447         if (c->efd == -1 ||
2448             c->extended_usage != CHAN_EXTENDED_WRITE ||
2449             tcode != SSH2_EXTENDED_DATA_STDERR) {
2450                 logit("channel %d: bad ext data", c->self);
2451                 return;
2452         }
2453         data = packet_get_string(&data_len);
2454         packet_check_eom();
2455         if (data_len > c->local_window) {
2456                 logit("channel %d: rcvd too much extended_data %d, win %d",
2457                     c->self, data_len, c->local_window);
2458                 free(data);
2459                 return;
2460         }
2461         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2462         c->local_window -= data_len;
2463         buffer_append(&c->extended, data, data_len);
2464         free(data);
2465 }
2466
2467 /* ARGSUSED */
2468 void
2469 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2470 {
2471         int id;
2472         Channel *c;
2473
2474         id = packet_get_int();
2475         packet_check_eom();
2476         c = channel_lookup(id);
2477         if (c == NULL)
2478                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2479         chan_rcvd_ieof(c);
2480
2481         /* XXX force input close */
2482         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2483                 debug("channel %d: FORCE input drain", c->self);
2484                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2485                 if (buffer_len(&c->input) == 0)
2486                         chan_ibuf_empty(c);
2487         }
2488
2489 }
2490
2491 /* ARGSUSED */
2492 void
2493 channel_input_close(int type, u_int32_t seq, void *ctxt)
2494 {
2495         int id;
2496         Channel *c;
2497
2498         id = packet_get_int();
2499         packet_check_eom();
2500         c = channel_lookup(id);
2501         if (c == NULL)
2502                 packet_disconnect("Received close for nonexistent channel %d.", id);
2503
2504         /*
2505          * Send a confirmation that we have closed the channel and no more
2506          * data is coming for it.
2507          */
2508         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2509         packet_put_int(c->remote_id);
2510         packet_send();
2511
2512         /*
2513          * If the channel is in closed state, we have sent a close request,
2514          * and the other side will eventually respond with a confirmation.
2515          * Thus, we cannot free the channel here, because then there would be
2516          * no-one to receive the confirmation.  The channel gets freed when
2517          * the confirmation arrives.
2518          */
2519         if (c->type != SSH_CHANNEL_CLOSED) {
2520                 /*
2521                  * Not a closed channel - mark it as draining, which will
2522                  * cause it to be freed later.
2523                  */
2524                 buffer_clear(&c->input);
2525                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2526         }
2527 }
2528
2529 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2530 /* ARGSUSED */
2531 void
2532 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2533 {
2534         int id = packet_get_int();
2535         Channel *c = channel_lookup(id);
2536
2537         packet_check_eom();
2538         if (c == NULL)
2539                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2540         chan_rcvd_oclose(c);
2541 }
2542
2543 /* ARGSUSED */
2544 void
2545 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2546 {
2547         int id = packet_get_int();
2548         Channel *c = channel_lookup(id);
2549
2550         packet_check_eom();
2551         if (c == NULL)
2552                 packet_disconnect("Received close confirmation for "
2553                     "out-of-range channel %d.", id);
2554         if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
2555                 packet_disconnect("Received close confirmation for "
2556                     "non-closed channel %d (type %d).", id, c->type);
2557         channel_free(c);
2558 }
2559
2560 /* ARGSUSED */
2561 void
2562 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2563 {
2564         int id, remote_id;
2565         Channel *c;
2566
2567         id = packet_get_int();
2568         c = channel_lookup(id);
2569
2570         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2571                 packet_disconnect("Received open confirmation for "
2572                     "non-opening channel %d.", id);
2573         remote_id = packet_get_int();
2574         /* Record the remote channel number and mark that the channel is now open. */
2575         c->remote_id = remote_id;
2576         c->type = SSH_CHANNEL_OPEN;
2577
2578         if (compat20) {
2579                 c->remote_window = packet_get_int();
2580                 c->remote_maxpacket = packet_get_int();
2581                 if (c->open_confirm) {
2582                         debug2("callback start");
2583                         c->open_confirm(c->self, 1, c->open_confirm_ctx);
2584                         debug2("callback done");
2585                 }
2586                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2587                     c->remote_window, c->remote_maxpacket);
2588         }
2589         packet_check_eom();
2590 }
2591
2592 static char *
2593 reason2txt(int reason)
2594 {
2595         switch (reason) {
2596         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2597                 return "administratively prohibited";
2598         case SSH2_OPEN_CONNECT_FAILED:
2599                 return "connect failed";
2600         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2601                 return "unknown channel type";
2602         case SSH2_OPEN_RESOURCE_SHORTAGE:
2603                 return "resource shortage";
2604         }
2605         return "unknown reason";
2606 }
2607
2608 /* ARGSUSED */
2609 void
2610 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2611 {
2612         int id, reason;
2613         char *msg = NULL, *lang = NULL;
2614         Channel *c;
2615
2616         id = packet_get_int();
2617         c = channel_lookup(id);
2618
2619         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2620                 packet_disconnect("Received open failure for "
2621                     "non-opening channel %d.", id);
2622         if (compat20) {
2623                 reason = packet_get_int();
2624                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2625                         msg  = packet_get_string(NULL);
2626                         lang = packet_get_string(NULL);
2627                 }
2628                 logit("channel %d: open failed: %s%s%s", id,
2629                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2630                 free(msg);
2631                 free(lang);
2632                 if (c->open_confirm) {
2633                         debug2("callback start");
2634                         c->open_confirm(c->self, 0, c->open_confirm_ctx);
2635                         debug2("callback done");
2636                 }
2637         }
2638         packet_check_eom();
2639         /* Schedule the channel for cleanup/deletion. */
2640         chan_mark_dead(c);
2641 }
2642
2643 /* ARGSUSED */
2644 void
2645 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2646 {
2647         Channel *c;
2648         int id;
2649         u_int adjust;
2650
2651         if (!compat20)
2652                 return;
2653
2654         /* Get the channel number and verify it. */
2655         id = packet_get_int();
2656         c = channel_lookup(id);
2657
2658         if (c == NULL) {
2659                 logit("Received window adjust for non-open channel %d.", id);
2660                 return;
2661         }
2662         adjust = packet_get_int();
2663         packet_check_eom();
2664         debug2("channel %d: rcvd adjust %u", id, adjust);
2665         c->remote_window += adjust;
2666 }
2667
2668 /* ARGSUSED */
2669 void
2670 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2671 {
2672         Channel *c = NULL;
2673         u_short host_port;
2674         char *host, *originator_string;
2675         int remote_id;
2676
2677         remote_id = packet_get_int();
2678         host = packet_get_string(NULL);
2679         host_port = packet_get_int();
2680
2681         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2682                 originator_string = packet_get_string(NULL);
2683         } else {
2684                 originator_string = xstrdup("unknown (remote did not supply name)");
2685         }
2686         packet_check_eom();
2687         c = channel_connect_to(host, host_port,
2688             "connected socket", originator_string);
2689         free(originator_string);
2690         free(host);
2691         if (c == NULL) {
2692                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2693                 packet_put_int(remote_id);
2694                 packet_send();
2695         } else
2696                 c->remote_id = remote_id;
2697 }
2698
2699 /* ARGSUSED */
2700 void
2701 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2702 {
2703         Channel *c;
2704         struct channel_confirm *cc;
2705         int id;
2706
2707         /* Reset keepalive timeout */
2708         packet_set_alive_timeouts(0);
2709
2710         id = packet_get_int();
2711         packet_check_eom();
2712
2713         debug2("channel_input_status_confirm: type %d id %d", type, id);
2714
2715         if ((c = channel_lookup(id)) == NULL) {
2716                 logit("channel_input_status_confirm: %d: unknown", id);
2717                 return;
2718         }
2719         ;
2720         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2721                 return;
2722         cc->cb(type, c, cc->ctx);
2723         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2724         bzero(cc, sizeof(*cc));
2725         free(cc);
2726 }
2727
2728 /* -- tcp forwarding */
2729
2730 void
2731 channel_set_af(int af)
2732 {
2733         IPv4or6 = af;
2734 }
2735
2736 void
2737 channel_set_hpn(int disabled, u_int buf_size)
2738 {
2739         hpn_disabled = disabled;
2740         buffer_size = buf_size;
2741         debug("HPN Disabled: %d, HPN Buffer Size: %d",
2742             hpn_disabled, buffer_size);
2743 }
2744
2745 /*
2746  * Determine whether or not a port forward listens to loopback, the
2747  * specified address or wildcard. On the client, a specified bind
2748  * address will always override gateway_ports. On the server, a
2749  * gateway_ports of 1 (``yes'') will override the client's specification
2750  * and force a wildcard bind, whereas a value of 2 (``clientspecified'')
2751  * will bind to whatever address the client asked for.
2752  *
2753  * Special-case listen_addrs are:
2754  *
2755  * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2756  * "" (empty string), "*"  -> wildcard v4/v6
2757  * "localhost"             -> loopback v4/v6
2758  */
2759 static const char *
2760 channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
2761     int is_client, int gateway_ports)
2762 {
2763         const char *addr = NULL;
2764         int wildcard = 0;
2765
2766         if (listen_addr == NULL) {
2767                 /* No address specified: default to gateway_ports setting */
2768                 if (gateway_ports)
2769                         wildcard = 1;
2770         } else if (gateway_ports || is_client) {
2771                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2772                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2773                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2774                     (!is_client && gateway_ports == 1))
2775                         wildcard = 1;
2776                 else if (strcmp(listen_addr, "localhost") != 0)
2777                         addr = listen_addr;
2778         }
2779         if (wildcardp != NULL)
2780                 *wildcardp = wildcard;
2781         return addr;
2782 }
2783
2784 static int
2785 channel_setup_fwd_listener(int type, const char *listen_addr,
2786     u_short listen_port, int *allocated_listen_port,
2787     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2788 {
2789         Channel *c;
2790         int sock, r, success = 0, wildcard = 0, is_client;
2791         struct addrinfo hints, *ai, *aitop;
2792         const char *host, *addr;
2793         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2794         in_port_t *lport_p;
2795
2796         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2797             listen_addr : host_to_connect;
2798         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2799
2800         if (host == NULL) {
2801                 error("No forward host name.");
2802                 return 0;
2803         }
2804         if (strlen(host) >= NI_MAXHOST) {
2805                 error("Forward host name too long.");
2806                 return 0;
2807         }
2808
2809         /* Determine the bind address, cf. channel_fwd_bind_addr() comment */
2810         addr = channel_fwd_bind_addr(listen_addr, &wildcard,
2811             is_client, gateway_ports);
2812         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2813             type, wildcard, (addr == NULL) ? "NULL" : addr);
2814
2815         /*
2816          * getaddrinfo returns a loopback address if the hostname is
2817          * set to NULL and hints.ai_flags is not AI_PASSIVE
2818          */
2819         memset(&hints, 0, sizeof(hints));
2820         hints.ai_family = IPv4or6;
2821         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2822         hints.ai_socktype = SOCK_STREAM;
2823         snprintf(strport, sizeof strport, "%d", listen_port);
2824         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2825                 if (addr == NULL) {
2826                         /* This really shouldn't happen */
2827                         packet_disconnect("getaddrinfo: fatal error: %s",
2828                             ssh_gai_strerror(r));
2829                 } else {
2830                         error("channel_setup_fwd_listener: "
2831                             "getaddrinfo(%.64s): %s", addr,
2832                             ssh_gai_strerror(r));
2833                 }
2834                 return 0;
2835         }
2836         if (allocated_listen_port != NULL)
2837                 *allocated_listen_port = 0;
2838         for (ai = aitop; ai; ai = ai->ai_next) {
2839                 switch (ai->ai_family) {
2840                 case AF_INET:
2841                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2842                             sin_port;
2843                         break;
2844                 case AF_INET6:
2845                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2846                             sin6_port;
2847                         break;
2848                 default:
2849                         continue;
2850                 }
2851                 /*
2852                  * If allocating a port for -R forwards, then use the
2853                  * same port for all address families.
2854                  */
2855                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2856                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2857                         *lport_p = htons(*allocated_listen_port);
2858
2859                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2860                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2861                         error("channel_setup_fwd_listener: getnameinfo failed");
2862                         continue;
2863                 }
2864                 /* Create a port to listen for the host. */
2865                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2866                 if (sock < 0) {
2867                         /* this is no error since kernel may not support ipv6 */
2868                         verbose("socket: %.100s", strerror(errno));
2869                         continue;
2870                 }
2871
2872                 channel_set_reuseaddr(sock);
2873                 if (ai->ai_family == AF_INET6)
2874                         sock_set_v6only(sock);
2875
2876                 debug("Local forwarding listening on %s port %s.",
2877                     ntop, strport);
2878
2879                 /* Bind the socket to the address. */
2880                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2881                         /* address can be in use ipv6 address is already bound */
2882                         if (!ai->ai_next)
2883                                 error("bind: %.100s", strerror(errno));
2884                         else
2885                                 verbose("bind: %.100s", strerror(errno));
2886
2887                         close(sock);
2888                         continue;
2889                 }
2890                 /* Start listening for connections on the socket. */
2891                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2892                         error("listen: %.100s", strerror(errno));
2893                         close(sock);
2894                         continue;
2895                 }
2896
2897                 /*
2898                  * listen_port == 0 requests a dynamically allocated port -
2899                  * record what we got.
2900                  */
2901                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2902                     allocated_listen_port != NULL &&
2903                     *allocated_listen_port == 0) {
2904                         *allocated_listen_port = get_sock_port(sock, 1);
2905                         debug("Allocated listen port %d",
2906                             *allocated_listen_port);
2907                 }
2908
2909                 /*
2910                  * Allocate a channel number for the socket.  Explicitly test
2911                  * for hpn disabled option.  If true use smaller window size.
2912                  */
2913                 if (hpn_disabled)
2914                         c = channel_new("port listener", type, sock, sock, -1,
2915                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2916                             0, "port listener", 1);
2917                 else
2918                         c = channel_new("port listener", type, sock, sock, -1,
2919                             buffer_size, CHAN_TCP_PACKET_DEFAULT,
2920                             0, "port listener", 1);
2921                 c->path = xstrdup(host);
2922                 c->host_port = port_to_connect;
2923                 c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
2924                 if (listen_port == 0 && allocated_listen_port != NULL &&
2925                     !(datafellows & SSH_BUG_DYNAMIC_RPORT))
2926                         c->listening_port = *allocated_listen_port;
2927                 else
2928                         c->listening_port = listen_port;
2929                 success = 1;
2930         }
2931         if (success == 0)
2932                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2933                     listen_port);
2934         freeaddrinfo(aitop);
2935         return success;
2936 }
2937
2938 int
2939 channel_cancel_rport_listener(const char *host, u_short port)
2940 {
2941         u_int i;
2942         int found = 0;
2943
2944         for (i = 0; i < channels_alloc; i++) {
2945                 Channel *c = channels[i];
2946                 if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
2947                         continue;
2948                 if (strcmp(c->path, host) == 0 && c->listening_port == port) {
2949                         debug2("%s: close channel %d", __func__, i);
2950                         channel_free(c);
2951                         found = 1;
2952                 }
2953         }
2954
2955         return (found);
2956 }
2957
2958 int
2959 channel_cancel_lport_listener(const char *lhost, u_short lport,
2960     int cport, int gateway_ports)
2961 {
2962         u_int i;
2963         int found = 0;
2964         const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, gateway_ports);
2965
2966         for (i = 0; i < channels_alloc; i++) {
2967                 Channel *c = channels[i];
2968                 if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
2969                         continue;
2970                 if (c->listening_port != lport)
2971                         continue;
2972                 if (cport == CHANNEL_CANCEL_PORT_STATIC) {
2973                         /* skip dynamic forwardings */
2974                         if (c->host_port == 0)
2975                                 continue;
2976                 } else {
2977                         if (c->host_port != cport)
2978                                 continue;
2979                 }
2980                 if ((c->listening_addr == NULL && addr != NULL) ||
2981                     (c->listening_addr != NULL && addr == NULL))
2982                         continue;
2983                 if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
2984                         debug2("%s: close channel %d", __func__, i);
2985                         channel_free(c);
2986                         found = 1;
2987                 }
2988         }
2989
2990         return (found);
2991 }
2992
2993 /* protocol local port fwd, used by ssh (and sshd in v1) */
2994 int
2995 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2996     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2997 {
2998         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2999             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
3000             gateway_ports);
3001 }
3002
3003 /* protocol v2 remote port fwd, used by sshd */
3004 int
3005 channel_setup_remote_fwd_listener(const char *listen_address,
3006     u_short listen_port, int *allocated_listen_port, int gateway_ports)
3007 {
3008         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
3009             listen_address, listen_port, allocated_listen_port,
3010             NULL, 0, gateway_ports);
3011 }
3012
3013 /*
3014  * Translate the requested rfwd listen host to something usable for
3015  * this server.
3016  */
3017 static const char *
3018 channel_rfwd_bind_host(const char *listen_host)
3019 {
3020         if (listen_host == NULL) {
3021                 if (datafellows & SSH_BUG_RFWD_ADDR)
3022                         return "127.0.0.1";
3023                 else
3024                         return "localhost";
3025         } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
3026                 if (datafellows & SSH_BUG_RFWD_ADDR)
3027                         return "0.0.0.0";
3028                 else
3029                         return "";
3030         } else
3031                 return listen_host;
3032 }
3033
3034 /*
3035  * Initiate forwarding of connections to port "port" on remote host through
3036  * the secure channel to host:port from local side.
3037  * Returns handle (index) for updating the dynamic listen port with
3038  * channel_update_permitted_opens().
3039  */
3040 int
3041 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
3042     const char *host_to_connect, u_short port_to_connect)
3043 {
3044         int type, success = 0, idx = -1;
3045
3046         /* Send the forward request to the remote side. */
3047         if (compat20) {
3048                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
3049                 packet_put_cstring("tcpip-forward");
3050                 packet_put_char(1);             /* boolean: want reply */
3051                 packet_put_cstring(channel_rfwd_bind_host(listen_host));
3052                 packet_put_int(listen_port);
3053                 packet_send();
3054                 packet_write_wait();
3055                 /* Assume that server accepts the request */
3056                 success = 1;
3057         } else {
3058                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
3059                 packet_put_int(listen_port);
3060                 packet_put_cstring(host_to_connect);
3061                 packet_put_int(port_to_connect);
3062                 packet_send();
3063                 packet_write_wait();
3064
3065                 /* Wait for response from the remote side. */
3066                 type = packet_read();
3067                 switch (type) {
3068                 case SSH_SMSG_SUCCESS:
3069                         success = 1;
3070                         break;
3071                 case SSH_SMSG_FAILURE:
3072                         break;
3073                 default:
3074                         /* Unknown packet */
3075                         packet_disconnect("Protocol error for port forward request:"
3076                             "received packet type %d.", type);
3077                 }
3078         }
3079         if (success) {
3080                 /* Record that connection to this host/port is permitted. */
3081                 permitted_opens = xrealloc(permitted_opens,
3082                     num_permitted_opens + 1, sizeof(*permitted_opens));
3083                 idx = num_permitted_opens++;
3084                 permitted_opens[idx].host_to_connect = xstrdup(host_to_connect);
3085                 permitted_opens[idx].port_to_connect = port_to_connect;
3086                 permitted_opens[idx].listen_port = listen_port;
3087         }
3088         return (idx);
3089 }
3090
3091 /*
3092  * Request cancellation of remote forwarding of connection host:port from
3093  * local side.
3094  */
3095 int
3096 channel_request_rforward_cancel(const char *host, u_short port)
3097 {
3098         int i;
3099
3100         if (!compat20)
3101                 return -1;
3102
3103         for (i = 0; i < num_permitted_opens; i++) {
3104                 if (permitted_opens[i].host_to_connect != NULL &&
3105                     permitted_opens[i].listen_port == port)
3106                         break;
3107         }
3108         if (i >= num_permitted_opens) {
3109                 debug("%s: requested forward not found", __func__);
3110                 return -1;
3111         }
3112         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3113         packet_put_cstring("cancel-tcpip-forward");
3114         packet_put_char(0);
3115         packet_put_cstring(channel_rfwd_bind_host(host));
3116         packet_put_int(port);
3117         packet_send();
3118
3119         permitted_opens[i].listen_port = 0;
3120         permitted_opens[i].port_to_connect = 0;
3121         free(permitted_opens[i].host_to_connect);
3122         permitted_opens[i].host_to_connect = NULL;
3123
3124         return 0;
3125 }
3126
3127 /*
3128  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
3129  * listening for the port, and sends back a success reply (or disconnect
3130  * message if there was an error).
3131  */
3132 int
3133 channel_input_port_forward_request(int is_root, int gateway_ports)
3134 {
3135         u_short port, host_port;
3136         int success = 0;
3137         char *hostname;
3138
3139         /* Get arguments from the packet. */
3140         port = packet_get_int();
3141         hostname = packet_get_string(NULL);
3142         host_port = packet_get_int();
3143
3144 #ifndef HAVE_CYGWIN
3145         /*
3146          * Check that an unprivileged user is not trying to forward a
3147          * privileged port.
3148          */
3149         if (port < IPPORT_RESERVED && !is_root)
3150                 packet_disconnect(
3151                     "Requested forwarding of port %d but user is not root.",
3152                     port);
3153         if (host_port == 0)
3154                 packet_disconnect("Dynamic forwarding denied.");
3155 #endif
3156
3157         /* Initiate forwarding */
3158         success = channel_setup_local_fwd_listener(NULL, port, hostname,
3159             host_port, gateway_ports);
3160
3161         /* Free the argument string. */
3162         free(hostname);
3163
3164         return (success ? 0 : -1);
3165 }
3166
3167 /*
3168  * Permits opening to any host/port if permitted_opens[] is empty.  This is
3169  * usually called by the server, because the user could connect to any port
3170  * anyway, and the server has no way to know but to trust the client anyway.
3171  */
3172 void
3173 channel_permit_all_opens(void)
3174 {
3175         if (num_permitted_opens == 0)
3176                 all_opens_permitted = 1;
3177 }
3178
3179 void
3180 channel_add_permitted_opens(char *host, int port)
3181 {
3182         debug("allow port forwarding to host %s port %d", host, port);
3183
3184         permitted_opens = xrealloc(permitted_opens,
3185             num_permitted_opens + 1, sizeof(*permitted_opens));
3186         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
3187         permitted_opens[num_permitted_opens].port_to_connect = port;
3188         num_permitted_opens++;
3189
3190         all_opens_permitted = 0;
3191 }
3192
3193 /*
3194  * Update the listen port for a dynamic remote forward, after
3195  * the actual 'newport' has been allocated. If 'newport' < 0 is
3196  * passed then they entry will be invalidated.
3197  */
3198 void
3199 channel_update_permitted_opens(int idx, int newport)
3200 {
3201         if (idx < 0 || idx >= num_permitted_opens) {
3202                 debug("channel_update_permitted_opens: index out of range:"
3203                     " %d num_permitted_opens %d", idx, num_permitted_opens);
3204                 return;
3205         }
3206         debug("%s allowed port %d for forwarding to host %s port %d",
3207             newport > 0 ? "Updating" : "Removing",
3208             newport,
3209             permitted_opens[idx].host_to_connect,
3210             permitted_opens[idx].port_to_connect);
3211         if (newport >= 0)  {
3212                 permitted_opens[idx].listen_port =
3213                     (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
3214         } else {
3215                 permitted_opens[idx].listen_port = 0;
3216                 permitted_opens[idx].port_to_connect = 0;
3217                 free(permitted_opens[idx].host_to_connect);
3218                 permitted_opens[idx].host_to_connect = NULL;
3219         }
3220 }
3221
3222 int
3223 channel_add_adm_permitted_opens(char *host, int port)
3224 {
3225         debug("config allows port forwarding to host %s port %d", host, port);
3226
3227         permitted_adm_opens = xrealloc(permitted_adm_opens,
3228             num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
3229         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3230              = xstrdup(host);
3231         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3232         return ++num_adm_permitted_opens;
3233 }
3234
3235 void
3236 channel_disable_adm_local_opens(void)
3237 {
3238         channel_clear_adm_permitted_opens();
3239         permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
3240         permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
3241         num_adm_permitted_opens = 1;
3242 }
3243
3244 void
3245 channel_clear_permitted_opens(void)
3246 {
3247         int i;
3248
3249         for (i = 0; i < num_permitted_opens; i++)
3250                 free(permitted_opens[i].host_to_connect);
3251         free(permitted_opens);
3252         permitted_opens = NULL;
3253         num_permitted_opens = 0;
3254 }
3255
3256 void
3257 channel_clear_adm_permitted_opens(void)
3258 {
3259         int i;
3260
3261         for (i = 0; i < num_adm_permitted_opens; i++)
3262                 free(permitted_adm_opens[i].host_to_connect);
3263         free(permitted_adm_opens);
3264         permitted_adm_opens = NULL;
3265         num_adm_permitted_opens = 0;
3266 }
3267
3268 void
3269 channel_print_adm_permitted_opens(void)
3270 {
3271         int i;
3272
3273         printf("permitopen");
3274         if (num_adm_permitted_opens == 0) {
3275                 printf(" any\n");
3276                 return;
3277         }
3278         for (i = 0; i < num_adm_permitted_opens; i++)
3279                 if (permitted_adm_opens[i].host_to_connect == NULL)
3280                         printf(" none");
3281                 else
3282                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3283                             permitted_adm_opens[i].port_to_connect);
3284         printf("\n");
3285 }
3286
3287 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
3288 int
3289 permitopen_port(const char *p)
3290 {
3291         int port;
3292
3293         if (strcmp(p, "*") == 0)
3294                 return FWD_PERMIT_ANY_PORT;
3295         if ((port = a2port(p)) > 0)
3296                 return port;
3297         return -1;
3298 }
3299
3300 static int
3301 port_match(u_short allowedport, u_short requestedport)
3302 {
3303         if (allowedport == FWD_PERMIT_ANY_PORT ||
3304             allowedport == requestedport)
3305                 return 1;
3306         return 0;
3307 }
3308
3309 /* Try to start non-blocking connect to next host in cctx list */
3310 static int
3311 connect_next(struct channel_connect *cctx)
3312 {
3313         int sock, saved_errno;
3314         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
3315
3316         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3317                 if (cctx->ai->ai_family != AF_INET &&
3318                     cctx->ai->ai_family != AF_INET6)
3319                         continue;
3320                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3321                     ntop, sizeof(ntop), strport, sizeof(strport),
3322                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3323                         error("connect_next: getnameinfo failed");
3324                         continue;
3325                 }
3326                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3327                     cctx->ai->ai_protocol)) == -1) {
3328                         if (cctx->ai->ai_next == NULL)
3329                                 error("socket: %.100s", strerror(errno));
3330                         else
3331                                 verbose("socket: %.100s", strerror(errno));
3332                         continue;
3333                 }
3334                 if (set_nonblock(sock) == -1)
3335                         fatal("%s: set_nonblock(%d)", __func__, sock);
3336                 if (connect(sock, cctx->ai->ai_addr,
3337                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3338                         debug("connect_next: host %.100s ([%.100s]:%s): "
3339                             "%.100s", cctx->host, ntop, strport,
3340                             strerror(errno));
3341                         saved_errno = errno;
3342                         close(sock);
3343                         errno = saved_errno;
3344                         continue;       /* fail -- try next */
3345                 }
3346                 debug("connect_next: host %.100s ([%.100s]:%s) "
3347                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3348                 cctx->ai = cctx->ai->ai_next;
3349                 set_nodelay(sock);
3350                 return sock;
3351         }
3352         return -1;
3353 }
3354
3355 static void
3356 channel_connect_ctx_free(struct channel_connect *cctx)
3357 {
3358         free(cctx->host);
3359         if (cctx->aitop)
3360                 freeaddrinfo(cctx->aitop);
3361         bzero(cctx, sizeof(*cctx));
3362         cctx->host = NULL;
3363         cctx->ai = cctx->aitop = NULL;
3364 }
3365
3366 /* Return CONNECTING channel to remote host, port */
3367 static Channel *
3368 connect_to(const char *host, u_short port, char *ctype, char *rname)
3369 {
3370         struct addrinfo hints;
3371         int gaierr;
3372         int sock = -1;
3373         char strport[NI_MAXSERV];
3374         struct channel_connect cctx;
3375         Channel *c;
3376
3377         memset(&cctx, 0, sizeof(cctx));
3378         memset(&hints, 0, sizeof(hints));
3379         hints.ai_family = IPv4or6;
3380         hints.ai_socktype = SOCK_STREAM;
3381         snprintf(strport, sizeof strport, "%d", port);
3382         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
3383                 error("connect_to %.100s: unknown host (%s)", host,
3384                     ssh_gai_strerror(gaierr));
3385                 return NULL;
3386         }
3387
3388         cctx.host = xstrdup(host);
3389         cctx.port = port;
3390         cctx.ai = cctx.aitop;
3391
3392         if ((sock = connect_next(&cctx)) == -1) {
3393                 error("connect to %.100s port %d failed: %s",
3394                     host, port, strerror(errno));
3395                 channel_connect_ctx_free(&cctx);
3396                 return NULL;
3397         }
3398         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3399             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3400         c->connect_ctx = cctx;
3401         return c;
3402 }
3403
3404 Channel *
3405 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3406 {
3407         int i;
3408
3409         for (i = 0; i < num_permitted_opens; i++) {
3410                 if (permitted_opens[i].host_to_connect != NULL &&
3411                     port_match(permitted_opens[i].listen_port, listen_port)) {
3412                         return connect_to(
3413                             permitted_opens[i].host_to_connect,
3414                             permitted_opens[i].port_to_connect, ctype, rname);
3415                 }
3416         }
3417         error("WARNING: Server requests forwarding for unknown listen_port %d",
3418             listen_port);
3419         return NULL;
3420 }
3421
3422 /* Check if connecting to that port is permitted and connect. */
3423 Channel *
3424 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3425 {
3426         int i, permit, permit_adm = 1;
3427
3428         permit = all_opens_permitted;
3429         if (!permit) {
3430                 for (i = 0; i < num_permitted_opens; i++)
3431                         if (permitted_opens[i].host_to_connect != NULL &&
3432                             port_match(permitted_opens[i].port_to_connect, port) &&
3433                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3434                                 permit = 1;
3435         }
3436
3437         if (num_adm_permitted_opens > 0) {
3438                 permit_adm = 0;
3439                 for (i = 0; i < num_adm_permitted_opens; i++)
3440                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3441                             port_match(permitted_adm_opens[i].port_to_connect, port) &&
3442                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3443                             == 0)
3444                                 permit_adm = 1;
3445         }
3446
3447         if (!permit || !permit_adm) {
3448                 logit("Received request to connect to host %.100s port %d, "
3449                     "but the request was denied.", host, port);
3450                 return NULL;
3451         }
3452         return connect_to(host, port, ctype, rname);
3453 }
3454
3455 void
3456 channel_send_window_changes(void)
3457 {
3458         u_int i;
3459         struct winsize ws;
3460
3461         for (i = 0; i < channels_alloc; i++) {
3462                 if (channels[i] == NULL || !channels[i]->client_tty ||
3463                     channels[i]->type != SSH_CHANNEL_OPEN)
3464                         continue;
3465                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3466                         continue;
3467                 channel_request_start(i, "window-change", 0);
3468                 packet_put_int((u_int)ws.ws_col);
3469                 packet_put_int((u_int)ws.ws_row);
3470                 packet_put_int((u_int)ws.ws_xpixel);
3471                 packet_put_int((u_int)ws.ws_ypixel);
3472                 packet_send();
3473         }
3474 }
3475
3476 /* -- X11 forwarding */
3477
3478 /*
3479  * Creates an internet domain socket for listening for X11 connections.
3480  * Returns 0 and a suitable display number for the DISPLAY variable
3481  * stored in display_numberp , or -1 if an error occurs.
3482  */
3483 int
3484 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3485     int single_connection, u_int *display_numberp, int **chanids)
3486 {
3487         Channel *nc = NULL;
3488         int display_number, sock;
3489         u_short port;
3490         struct addrinfo hints, *ai, *aitop;
3491         char strport[NI_MAXSERV];
3492         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3493
3494         if (chanids == NULL)
3495                 return -1;
3496
3497         for (display_number = x11_display_offset;
3498             display_number < MAX_DISPLAYS;
3499             display_number++) {
3500                 port = 6000 + display_number;
3501                 memset(&hints, 0, sizeof(hints));
3502                 hints.ai_family = IPv4or6;
3503                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3504                 hints.ai_socktype = SOCK_STREAM;
3505                 snprintf(strport, sizeof strport, "%d", port);
3506                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3507                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3508                         return -1;
3509                 }
3510                 for (ai = aitop; ai; ai = ai->ai_next) {
3511                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3512                                 continue;
3513                         sock = socket(ai->ai_family, ai->ai_socktype,
3514                             ai->ai_protocol);
3515                         if (sock < 0) {
3516                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
3517 #ifdef EPFNOSUPPORT
3518                                     && (errno != EPFNOSUPPORT)
3519 #endif
3520                                     ) {
3521                                         error("socket: %.100s", strerror(errno));
3522                                         freeaddrinfo(aitop);
3523                                         return -1;
3524                                 } else {
3525                                         debug("x11_create_display_inet: Socket family %d not supported",
3526                                                  ai->ai_family);
3527                                         continue;
3528                                 }
3529                         }
3530                         if (ai->ai_family == AF_INET6)
3531                                 sock_set_v6only(sock);
3532                         if (x11_use_localhost)
3533                                 channel_set_reuseaddr(sock);
3534                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3535                                 debug2("bind port %d: %.100s", port, strerror(errno));
3536                                 close(sock);
3537
3538                                 for (n = 0; n < num_socks; n++) {
3539                                         close(socks[n]);
3540                                 }
3541                                 num_socks = 0;
3542                                 break;
3543                         }
3544                         socks[num_socks++] = sock;
3545                         if (num_socks == NUM_SOCKS)
3546                                 break;
3547                 }
3548                 freeaddrinfo(aitop);
3549                 if (num_socks > 0)
3550                         break;
3551         }
3552         if (display_number >= MAX_DISPLAYS) {
3553                 error("Failed to allocate internet-domain X11 display socket.");
3554                 return -1;
3555         }
3556         /* Start listening for connections on the socket. */
3557         for (n = 0; n < num_socks; n++) {
3558                 sock = socks[n];
3559                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3560                         error("listen: %.100s", strerror(errno));
3561                         close(sock);
3562                         return -1;
3563                 }
3564         }
3565
3566         /* Allocate a channel for each socket. */
3567         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3568         for (n = 0; n < num_socks; n++) {
3569                 sock = socks[n];
3570                 if (hpn_disabled)
3571                         nc = channel_new("x11 listener",
3572                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3573                             CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3574                             0, "X11 inet listener", 1);
3575                 else
3576                         nc = channel_new("x11 listener",
3577                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3578                             buffer_size, CHAN_X11_PACKET_DEFAULT,
3579                             0, "X11 inet listener", 1);
3580                 nc->single_connection = single_connection;
3581                 (*chanids)[n] = nc->self;
3582         }
3583         (*chanids)[n] = -1;
3584
3585         /* Return the display number for the DISPLAY environment variable. */
3586         *display_numberp = display_number;
3587         return (0);
3588 }
3589
3590 static int
3591 connect_local_xsocket_path(const char *pathname)
3592 {
3593         int sock;
3594         struct sockaddr_un addr;
3595
3596         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3597         if (sock < 0)
3598                 error("socket: %.100s", strerror(errno));
3599         memset(&addr, 0, sizeof(addr));
3600         addr.sun_family = AF_UNIX;
3601         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3602         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3603                 return sock;
3604         close(sock);
3605         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3606         return -1;
3607 }
3608
3609 static int
3610 connect_local_xsocket(u_int dnr)
3611 {
3612         char buf[1024];
3613         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3614         return connect_local_xsocket_path(buf);
3615 }
3616
3617 int
3618 x11_connect_display(void)
3619 {
3620         u_int display_number;
3621         const char *display;
3622         char buf[1024], *cp;
3623         struct addrinfo hints, *ai, *aitop;
3624         char strport[NI_MAXSERV];
3625         int gaierr, sock = 0;
3626
3627         /* Try to open a socket for the local X server. */
3628         display = getenv("DISPLAY");
3629         if (!display) {
3630                 error("DISPLAY not set.");
3631                 return -1;
3632         }
3633         /*
3634          * Now we decode the value of the DISPLAY variable and make a
3635          * connection to the real X server.
3636          */
3637
3638         /* Check if the display is from launchd. */
3639 #ifdef __APPLE__
3640         if (strncmp(display, "/tmp/launch", 11) == 0) {
3641                 sock = connect_local_xsocket_path(display);
3642                 if (sock < 0)
3643                         return -1;
3644
3645                 /* OK, we now have a connection to the display. */
3646                 return sock;
3647         }
3648 #endif
3649         /*
3650          * Check if it is a unix domain socket.  Unix domain displays are in
3651          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3652          */
3653         if (strncmp(display, "unix:", 5) == 0 ||
3654             display[0] == ':') {
3655                 /* Connect to the unix domain socket. */
3656                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3657                         error("Could not parse display number from DISPLAY: %.100s",
3658                             display);
3659                         return -1;
3660                 }
3661                 /* Create a socket. */
3662                 sock = connect_local_xsocket(display_number);
3663                 if (sock < 0)
3664                         return -1;
3665
3666                 /* OK, we now have a connection to the display. */
3667                 return sock;
3668         }
3669         /*
3670          * Connect to an inet socket.  The DISPLAY value is supposedly
3671          * hostname:d[.s], where hostname may also be numeric IP address.
3672          */
3673         strlcpy(buf, display, sizeof(buf));
3674         cp = strchr(buf, ':');
3675         if (!cp) {
3676                 error("Could not find ':' in DISPLAY: %.100s", display);
3677                 return -1;
3678         }
3679         *cp = 0;
3680         /* buf now contains the host name.  But first we parse the display number. */
3681         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3682                 error("Could not parse display number from DISPLAY: %.100s",
3683                     display);
3684                 return -1;
3685         }
3686
3687         /* Look up the host address */
3688         memset(&hints, 0, sizeof(hints));
3689         hints.ai_family = IPv4or6;
3690         hints.ai_socktype = SOCK_STREAM;
3691         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3692         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3693                 error("%.100s: unknown host. (%s)", buf,
3694                 ssh_gai_strerror(gaierr));
3695                 return -1;
3696         }
3697         for (ai = aitop; ai; ai = ai->ai_next) {
3698                 /* Create a socket. */
3699                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3700                 if (sock < 0) {
3701                         debug2("socket: %.100s", strerror(errno));
3702                         continue;
3703                 }
3704                 /* Connect it to the display. */
3705                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3706                         debug2("connect %.100s port %u: %.100s", buf,
3707                             6000 + display_number, strerror(errno));
3708                         close(sock);
3709                         continue;
3710                 }
3711                 /* Success */
3712                 break;
3713         }
3714         freeaddrinfo(aitop);
3715         if (!ai) {
3716                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3717                     strerror(errno));
3718                 return -1;
3719         }
3720         set_nodelay(sock);
3721         return sock;
3722 }
3723
3724 /*
3725  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3726  * the remote channel number.  We should do whatever we want, and respond
3727  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3728  */
3729
3730 /* ARGSUSED */
3731 void
3732 x11_input_open(int type, u_int32_t seq, void *ctxt)
3733 {
3734         Channel *c = NULL;
3735         int remote_id, sock = 0;
3736         char *remote_host;
3737
3738         debug("Received X11 open request.");
3739
3740         remote_id = packet_get_int();
3741
3742         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3743                 remote_host = packet_get_string(NULL);
3744         } else {
3745                 remote_host = xstrdup("unknown (remote did not supply name)");
3746         }
3747         packet_check_eom();
3748
3749         /* Obtain a connection to the real X display. */
3750         sock = x11_connect_display();
3751         if (sock != -1) {
3752                 /* Allocate a channel for this connection. */
3753                 c = channel_new("connected x11 socket",
3754                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3755                     remote_host, 1);
3756                 c->remote_id = remote_id;
3757                 c->force_drain = 1;
3758         }
3759         free(remote_host);
3760         if (c == NULL) {
3761                 /* Send refusal to the remote host. */
3762                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3763                 packet_put_int(remote_id);
3764         } else {
3765                 /* Send a confirmation to the remote host. */
3766                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3767                 packet_put_int(remote_id);
3768                 packet_put_int(c->self);
3769         }
3770         packet_send();
3771 }
3772
3773 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3774 /* ARGSUSED */
3775 void
3776 deny_input_open(int type, u_int32_t seq, void *ctxt)
3777 {
3778         int rchan = packet_get_int();
3779
3780         switch (type) {
3781         case SSH_SMSG_AGENT_OPEN:
3782                 error("Warning: ssh server tried agent forwarding.");
3783                 break;
3784         case SSH_SMSG_X11_OPEN:
3785                 error("Warning: ssh server tried X11 forwarding.");
3786                 break;
3787         default:
3788                 error("deny_input_open: type %d", type);
3789                 break;
3790         }
3791         error("Warning: this is probably a break-in attempt by a malicious server.");
3792         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3793         packet_put_int(rchan);
3794         packet_send();
3795 }
3796
3797 /*
3798  * Requests forwarding of X11 connections, generates fake authentication
3799  * data, and enables authentication spoofing.
3800  * This should be called in the client only.
3801  */
3802 void
3803 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3804     const char *proto, const char *data, int want_reply)
3805 {
3806         u_int data_len = (u_int) strlen(data) / 2;
3807         u_int i, value;
3808         char *new_data;
3809         int screen_number;
3810         const char *cp;
3811         u_int32_t rnd = 0;
3812
3813         if (x11_saved_display == NULL)
3814                 x11_saved_display = xstrdup(disp);
3815         else if (strcmp(disp, x11_saved_display) != 0) {
3816                 error("x11_request_forwarding_with_spoofing: different "
3817                     "$DISPLAY already forwarded");
3818                 return;
3819         }
3820
3821         cp = strchr(disp, ':');
3822         if (cp)
3823                 cp = strchr(cp, '.');
3824         if (cp)
3825                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3826         else
3827                 screen_number = 0;
3828
3829         if (x11_saved_proto == NULL) {
3830                 /* Save protocol name. */
3831                 x11_saved_proto = xstrdup(proto);
3832                 /*
3833                  * Extract real authentication data and generate fake data
3834                  * of the same length.
3835                  */
3836                 x11_saved_data = xmalloc(data_len);
3837                 x11_fake_data = xmalloc(data_len);
3838                 for (i = 0; i < data_len; i++) {
3839                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3840                                 fatal("x11_request_forwarding: bad "
3841                                     "authentication data: %.100s", data);
3842                         if (i % 4 == 0)
3843                                 rnd = arc4random();
3844                         x11_saved_data[i] = value;
3845                         x11_fake_data[i] = rnd & 0xff;
3846                         rnd >>= 8;
3847                 }
3848                 x11_saved_data_len = data_len;
3849                 x11_fake_data_len = data_len;
3850         }
3851
3852         /* Convert the fake data into hex. */
3853         new_data = tohex(x11_fake_data, data_len);
3854
3855         /* Send the request packet. */
3856         if (compat20) {
3857                 channel_request_start(client_session_id, "x11-req", want_reply);
3858                 packet_put_char(0);     /* XXX bool single connection */
3859         } else {
3860                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3861         }
3862         packet_put_cstring(proto);
3863         packet_put_cstring(new_data);
3864         packet_put_int(screen_number);
3865         packet_send();
3866         packet_write_wait();
3867         free(new_data);
3868 }
3869
3870
3871 /* -- agent forwarding */
3872
3873 /* Sends a message to the server to request authentication fd forwarding. */
3874
3875 void
3876 auth_request_forwarding(void)
3877 {
3878         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3879         packet_send();
3880         packet_write_wait();
3881 }