crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.331 2014/02/26 20:29:29 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                 explicit_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 = xcalloc(1, 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         if (memchr(p, '\0', have) == NULL)
1118                 fatal("channel %d: decode socks4: user not nul terminated",
1119                     c->self);
1120         len = strlen(p);
1121         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1122         len++;                                  /* trailing '\0' */
1123         if (len > have)
1124                 fatal("channel %d: decode socks4: len %d > have %d",
1125                     c->self, len, have);
1126         strlcpy(username, p, sizeof(username));
1127         buffer_consume(&c->input, len);
1128
1129         free(c->path);
1130         c->path = NULL;
1131         if (need == 1) {                        /* SOCKS4: one string */
1132                 host = inet_ntoa(s4_req.dest_addr);
1133                 c->path = xstrdup(host);
1134         } else {                                /* SOCKS4A: two strings */
1135                 have = buffer_len(&c->input);
1136                 p = buffer_ptr(&c->input);
1137                 len = strlen(p);
1138                 debug2("channel %d: decode socks4a: host %s/%d",
1139                     c->self, p, len);
1140                 len++;                          /* trailing '\0' */
1141                 if (len > have)
1142                         fatal("channel %d: decode socks4a: len %d > have %d",
1143                             c->self, len, have);
1144                 if (len > NI_MAXHOST) {
1145                         error("channel %d: hostname \"%.100s\" too long",
1146                             c->self, p);
1147                         return -1;
1148                 }
1149                 c->path = xstrdup(p);
1150                 buffer_consume(&c->input, len);
1151         }
1152         c->host_port = ntohs(s4_req.dest_port);
1153
1154         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1155             c->self, c->path, c->host_port, s4_req.command);
1156
1157         if (s4_req.command != 1) {
1158                 debug("channel %d: cannot handle: %s cn %d",
1159                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1160                 return -1;
1161         }
1162         s4_rsp.version = 0;                     /* vn: 0 for reply */
1163         s4_rsp.command = 90;                    /* cd: req granted */
1164         s4_rsp.dest_port = 0;                   /* ignored */
1165         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1166         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1167         return 1;
1168 }
1169
1170 /* try to decode a socks5 header */
1171 #define SSH_SOCKS5_AUTHDONE     0x1000
1172 #define SSH_SOCKS5_NOAUTH       0x00
1173 #define SSH_SOCKS5_IPV4         0x01
1174 #define SSH_SOCKS5_DOMAIN       0x03
1175 #define SSH_SOCKS5_IPV6         0x04
1176 #define SSH_SOCKS5_CONNECT      0x01
1177 #define SSH_SOCKS5_SUCCESS      0x00
1178
1179 /* ARGSUSED */
1180 static int
1181 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1182 {
1183         struct {
1184                 u_int8_t version;
1185                 u_int8_t command;
1186                 u_int8_t reserved;
1187                 u_int8_t atyp;
1188         } s5_req, s5_rsp;
1189         u_int16_t dest_port;
1190         char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1191         u_char *p;
1192         u_int have, need, i, found, nmethods, addrlen, af;
1193
1194         debug2("channel %d: decode socks5", c->self);
1195         p = buffer_ptr(&c->input);
1196         if (p[0] != 0x05)
1197                 return -1;
1198         have = buffer_len(&c->input);
1199         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1200                 /* format: ver | nmethods | methods */
1201                 if (have < 2)
1202                         return 0;
1203                 nmethods = p[1];
1204                 if (have < nmethods + 2)
1205                         return 0;
1206                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1207                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1208                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1209                                 found = 1;
1210                                 break;
1211                         }
1212                 }
1213                 if (!found) {
1214                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1215                             c->self);
1216                         return -1;
1217                 }
1218                 buffer_consume(&c->input, nmethods + 2);
1219                 buffer_put_char(&c->output, 0x05);              /* version */
1220                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1221                 FD_SET(c->sock, writeset);
1222                 c->flags |= SSH_SOCKS5_AUTHDONE;
1223                 debug2("channel %d: socks5 auth done", c->self);
1224                 return 0;                               /* need more */
1225         }
1226         debug2("channel %d: socks5 post auth", c->self);
1227         if (have < sizeof(s5_req)+1)
1228                 return 0;                       /* need more */
1229         memcpy(&s5_req, p, sizeof(s5_req));
1230         if (s5_req.version != 0x05 ||
1231             s5_req.command != SSH_SOCKS5_CONNECT ||
1232             s5_req.reserved != 0x00) {
1233                 debug2("channel %d: only socks5 connect supported", c->self);
1234                 return -1;
1235         }
1236         switch (s5_req.atyp){
1237         case SSH_SOCKS5_IPV4:
1238                 addrlen = 4;
1239                 af = AF_INET;
1240                 break;
1241         case SSH_SOCKS5_DOMAIN:
1242                 addrlen = p[sizeof(s5_req)];
1243                 af = -1;
1244                 break;
1245         case SSH_SOCKS5_IPV6:
1246                 addrlen = 16;
1247                 af = AF_INET6;
1248                 break;
1249         default:
1250                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1251                 return -1;
1252         }
1253         need = sizeof(s5_req) + addrlen + 2;
1254         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1255                 need++;
1256         if (have < need)
1257                 return 0;
1258         buffer_consume(&c->input, sizeof(s5_req));
1259         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1260                 buffer_consume(&c->input, 1);    /* host string length */
1261         buffer_get(&c->input, &dest_addr, addrlen);
1262         buffer_get(&c->input, (char *)&dest_port, 2);
1263         dest_addr[addrlen] = '\0';
1264         free(c->path);
1265         c->path = NULL;
1266         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1267                 if (addrlen >= NI_MAXHOST) {
1268                         error("channel %d: dynamic request: socks5 hostname "
1269                             "\"%.100s\" too long", c->self, dest_addr);
1270                         return -1;
1271                 }
1272                 c->path = xstrdup(dest_addr);
1273         } else {
1274                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1275                         return -1;
1276                 c->path = xstrdup(ntop);
1277         }
1278         c->host_port = ntohs(dest_port);
1279
1280         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1281             c->self, c->path, c->host_port, s5_req.command);
1282
1283         s5_rsp.version = 0x05;
1284         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1285         s5_rsp.reserved = 0;                    /* ignored */
1286         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1287         dest_port = 0;                          /* ignored */
1288
1289         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1290         buffer_put_int(&c->output, ntohl(INADDR_ANY)); /* bind address */
1291         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1292         return 1;
1293 }
1294
1295 Channel *
1296 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1297     int in, int out)
1298 {
1299         Channel *c;
1300
1301         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1302             port_to_connect);
1303
1304         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1305             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1306             0, "stdio-forward", /*nonblock*/0);
1307
1308         c->path = xstrdup(host_to_connect);
1309         c->host_port = port_to_connect;
1310         c->listening_port = 0;
1311         c->force_drain = 1;
1312
1313         channel_register_fds(c, in, out, -1, 0, 1, 0);
1314         port_open_helper(c, "direct-tcpip");
1315
1316         return c;
1317 }
1318
1319 /* dynamic port forwarding */
1320 static void
1321 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1322 {
1323         u_char *p;
1324         u_int have;
1325         int ret;
1326
1327         have = buffer_len(&c->input);
1328         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1329         /* buffer_dump(&c->input); */
1330         /* check if the fixed size part of the packet is in buffer. */
1331         if (have < 3) {
1332                 /* need more */
1333                 FD_SET(c->sock, readset);
1334                 return;
1335         }
1336         /* try to guess the protocol */
1337         p = buffer_ptr(&c->input);
1338         switch (p[0]) {
1339         case 0x04:
1340                 ret = channel_decode_socks4(c, readset, writeset);
1341                 break;
1342         case 0x05:
1343                 ret = channel_decode_socks5(c, readset, writeset);
1344                 break;
1345         default:
1346                 ret = -1;
1347                 break;
1348         }
1349         if (ret < 0) {
1350                 chan_mark_dead(c);
1351         } else if (ret == 0) {
1352                 debug2("channel %d: pre_dynamic: need more", c->self);
1353                 /* need more */
1354                 FD_SET(c->sock, readset);
1355         } else {
1356                 /* switch to the next state */
1357                 c->type = SSH_CHANNEL_OPENING;
1358                 port_open_helper(c, "direct-tcpip");
1359         }
1360 }
1361
1362 /* This is our fake X11 server socket. */
1363 /* ARGSUSED */
1364 static void
1365 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1366 {
1367         Channel *nc;
1368         struct sockaddr_storage addr;
1369         int newsock, oerrno;
1370         socklen_t addrlen;
1371         char buf[16384], *remote_ipaddr;
1372         int remote_port;
1373
1374         if (FD_ISSET(c->sock, readset)) {
1375                 debug("X11 connection requested.");
1376                 addrlen = sizeof(addr);
1377                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1378                 if (c->single_connection) {
1379                         oerrno = errno;
1380                         debug2("single_connection: closing X11 listener.");
1381                         channel_close_fd(&c->sock);
1382                         chan_mark_dead(c);
1383                         errno = oerrno;
1384                 }
1385                 if (newsock < 0) {
1386                         if (errno != EINTR && errno != EWOULDBLOCK &&
1387                             errno != ECONNABORTED)
1388                                 error("accept: %.100s", strerror(errno));
1389                         if (errno == EMFILE || errno == ENFILE)
1390                                 c->notbefore = monotime() + 1;
1391                         return;
1392                 }
1393                 set_nodelay(newsock);
1394                 remote_ipaddr = get_peer_ipaddr(newsock);
1395                 remote_port = get_peer_port(newsock);
1396                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1397                     remote_ipaddr, remote_port);
1398
1399                 nc = channel_new("accepted x11 socket",
1400                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1401                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1402                 if (compat20) {
1403                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1404                         packet_put_cstring("x11");
1405                         packet_put_int(nc->self);
1406                         packet_put_int(nc->local_window_max);
1407                         packet_put_int(nc->local_maxpacket);
1408                         /* originator ipaddr and port */
1409                         packet_put_cstring(remote_ipaddr);
1410                         if (datafellows & SSH_BUG_X11FWD) {
1411                                 debug2("ssh2 x11 bug compat mode");
1412                         } else {
1413                                 packet_put_int(remote_port);
1414                         }
1415                         packet_send();
1416                 } else {
1417                         packet_start(SSH_SMSG_X11_OPEN);
1418                         packet_put_int(nc->self);
1419                         if (packet_get_protocol_flags() &
1420                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1421                                 packet_put_cstring(buf);
1422                         packet_send();
1423                 }
1424                 free(remote_ipaddr);
1425         }
1426 }
1427
1428 static void
1429 port_open_helper(Channel *c, char *rtype)
1430 {
1431         int direct;
1432         char buf[1024];
1433         char *local_ipaddr = get_local_ipaddr(c->sock);
1434         int local_port = c->sock == -1 ? 65536 : get_sock_port(c->sock, 1);
1435         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1436         int remote_port = get_peer_port(c->sock);
1437
1438         if (remote_port == -1) {
1439                 /* Fake addr/port to appease peers that validate it (Tectia) */
1440                 free(remote_ipaddr);
1441                 remote_ipaddr = xstrdup("127.0.0.1");
1442                 remote_port = 65535;
1443         }
1444
1445         direct = (strcmp(rtype, "direct-tcpip") == 0);
1446
1447         snprintf(buf, sizeof buf,
1448             "%s: listening port %d for %.100s port %d, "
1449             "connect from %.200s port %d to %.100s port %d",
1450             rtype, c->listening_port, c->path, c->host_port,
1451             remote_ipaddr, remote_port, local_ipaddr, local_port);
1452
1453         free(c->remote_name);
1454         c->remote_name = xstrdup(buf);
1455
1456         if (compat20) {
1457                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1458                 packet_put_cstring(rtype);
1459                 packet_put_int(c->self);
1460                 packet_put_int(c->local_window_max);
1461                 packet_put_int(c->local_maxpacket);
1462                 if (direct) {
1463                         /* target host, port */
1464                         packet_put_cstring(c->path);
1465                         packet_put_int(c->host_port);
1466                 } else {
1467                         /* listen address, port */
1468                         packet_put_cstring(c->path);
1469                         packet_put_int(local_port);
1470                 }
1471                 /* originator host and port */
1472                 packet_put_cstring(remote_ipaddr);
1473                 packet_put_int((u_int)remote_port);
1474                 packet_send();
1475         } else {
1476                 packet_start(SSH_MSG_PORT_OPEN);
1477                 packet_put_int(c->self);
1478                 packet_put_cstring(c->path);
1479                 packet_put_int(c->host_port);
1480                 if (packet_get_protocol_flags() &
1481                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1482                         packet_put_cstring(c->remote_name);
1483                 packet_send();
1484         }
1485         free(remote_ipaddr);
1486         free(local_ipaddr);
1487 }
1488
1489 static void
1490 channel_set_reuseaddr(int fd)
1491 {
1492         int on = 1;
1493
1494         /*
1495          * Set socket options.
1496          * Allow local port reuse in TIME_WAIT.
1497          */
1498         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1499                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1500 }
1501
1502 /*
1503  * This socket is listening for connections to a forwarded TCP/IP port.
1504  */
1505 /* ARGSUSED */
1506 static void
1507 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1508 {
1509         Channel *nc;
1510         struct sockaddr_storage addr;
1511         int newsock, nextstate;
1512         socklen_t addrlen;
1513         char *rtype;
1514
1515         if (FD_ISSET(c->sock, readset)) {
1516                 debug("Connection to port %d forwarding "
1517                     "to %.100s port %d requested.",
1518                     c->listening_port, c->path, c->host_port);
1519
1520                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1521                         nextstate = SSH_CHANNEL_OPENING;
1522                         rtype = "forwarded-tcpip";
1523                 } else {
1524                         if (c->host_port == 0) {
1525                                 nextstate = SSH_CHANNEL_DYNAMIC;
1526                                 rtype = "dynamic-tcpip";
1527                         } else {
1528                                 nextstate = SSH_CHANNEL_OPENING;
1529                                 rtype = "direct-tcpip";
1530                         }
1531                 }
1532
1533                 addrlen = sizeof(addr);
1534                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1535                 if (newsock < 0) {
1536                         if (errno != EINTR && errno != EWOULDBLOCK &&
1537                             errno != ECONNABORTED)
1538                                 error("accept: %.100s", strerror(errno));
1539                         if (errno == EMFILE || errno == ENFILE)
1540                                 c->notbefore = monotime() + 1;
1541                         return;
1542                 }
1543                 set_nodelay(newsock);
1544                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1545                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1546                 nc->listening_port = c->listening_port;
1547                 nc->host_port = c->host_port;
1548                 if (c->path != NULL)
1549                         nc->path = xstrdup(c->path);
1550
1551                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1552                         port_open_helper(nc, rtype);
1553         }
1554 }
1555
1556 /*
1557  * This is the authentication agent socket listening for connections from
1558  * clients.
1559  */
1560 /* ARGSUSED */
1561 static void
1562 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1563 {
1564         Channel *nc;
1565         int newsock;
1566         struct sockaddr_storage addr;
1567         socklen_t addrlen;
1568
1569         if (FD_ISSET(c->sock, readset)) {
1570                 addrlen = sizeof(addr);
1571                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1572                 if (newsock < 0) {
1573                         error("accept from auth socket: %.100s",
1574                             strerror(errno));
1575                         if (errno == EMFILE || errno == ENFILE)
1576                                 c->notbefore = monotime() + 1;
1577                         return;
1578                 }
1579                 nc = channel_new("accepted auth socket",
1580                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1581                     c->local_window_max, c->local_maxpacket,
1582                     0, "accepted auth socket", 1);
1583                 if (compat20) {
1584                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1585                         packet_put_cstring("auth-agent@openssh.com");
1586                         packet_put_int(nc->self);
1587                         packet_put_int(c->local_window_max);
1588                         packet_put_int(c->local_maxpacket);
1589                 } else {
1590                         packet_start(SSH_SMSG_AGENT_OPEN);
1591                         packet_put_int(nc->self);
1592                 }
1593                 packet_send();
1594         }
1595 }
1596
1597 /* ARGSUSED */
1598 static void
1599 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1600 {
1601         int err = 0, sock;
1602         socklen_t sz = sizeof(err);
1603
1604         if (FD_ISSET(c->sock, writeset)) {
1605                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1606                         err = errno;
1607                         error("getsockopt SO_ERROR failed");
1608                 }
1609                 if (err == 0) {
1610                         debug("channel %d: connected to %s port %d",
1611                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1612                         channel_connect_ctx_free(&c->connect_ctx);
1613                         c->type = SSH_CHANNEL_OPEN;
1614                         if (compat20) {
1615                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1616                                 packet_put_int(c->remote_id);
1617                                 packet_put_int(c->self);
1618                                 packet_put_int(c->local_window);
1619                                 packet_put_int(c->local_maxpacket);
1620                         } else {
1621                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1622                                 packet_put_int(c->remote_id);
1623                                 packet_put_int(c->self);
1624                         }
1625                 } else {
1626                         debug("channel %d: connection failed: %s",
1627                             c->self, strerror(err));
1628                         /* Try next address, if any */
1629                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1630                                 close(c->sock);
1631                                 c->sock = c->rfd = c->wfd = sock;
1632                                 channel_max_fd = channel_find_maxfd();
1633                                 return;
1634                         }
1635                         /* Exhausted all addresses */
1636                         error("connect_to %.100s port %d: failed.",
1637                             c->connect_ctx.host, c->connect_ctx.port);
1638                         channel_connect_ctx_free(&c->connect_ctx);
1639                         if (compat20) {
1640                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1641                                 packet_put_int(c->remote_id);
1642                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1643                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1644                                         packet_put_cstring(strerror(err));
1645                                         packet_put_cstring("");
1646                                 }
1647                         } else {
1648                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1649                                 packet_put_int(c->remote_id);
1650                         }
1651                         chan_mark_dead(c);
1652                 }
1653                 packet_send();
1654         }
1655 }
1656
1657 /* ARGSUSED */
1658 static int
1659 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1660 {
1661         char buf[CHAN_RBUF];
1662         int len, force;
1663
1664         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1665         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1666                 errno = 0;
1667                 len = read(c->rfd, buf, sizeof(buf));
1668                 if (len < 0 && (errno == EINTR ||
1669                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1670                         return 1;
1671 #ifndef PTY_ZEROREAD
1672                 if (len <= 0) {
1673 #else
1674                 if ((!c->isatty && len <= 0) ||
1675                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1676 #endif
1677                         debug2("channel %d: read<=0 rfd %d len %d",
1678                             c->self, c->rfd, len);
1679                         if (c->type != SSH_CHANNEL_OPEN) {
1680                                 debug2("channel %d: not open", c->self);
1681                                 chan_mark_dead(c);
1682                                 return -1;
1683                         } else if (compat13) {
1684                                 buffer_clear(&c->output);
1685                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1686                                 debug2("channel %d: input draining.", c->self);
1687                         } else {
1688                                 chan_read_failed(c);
1689                         }
1690                         return -1;
1691                 }
1692                 if (c->input_filter != NULL) {
1693                         if (c->input_filter(c, buf, len) == -1) {
1694                                 debug2("channel %d: filter stops", c->self);
1695                                 chan_read_failed(c);
1696                         }
1697                 } else if (c->datagram) {
1698                         buffer_put_string(&c->input, buf, len);
1699                 } else {
1700                         buffer_append(&c->input, buf, len);
1701                 }
1702         }
1703         return 1;
1704 }
1705
1706 /* ARGSUSED */
1707 static int
1708 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1709 {
1710         struct termios tio;
1711         u_char *data = NULL, *buf;
1712         u_int dlen, olen = 0;
1713         int len;
1714
1715         /* Send buffered output data to the socket. */
1716         if (c->wfd != -1 &&
1717             FD_ISSET(c->wfd, writeset) &&
1718             buffer_len(&c->output) > 0) {
1719                 olen = buffer_len(&c->output);
1720                 if (c->output_filter != NULL) {
1721                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1722                                 debug2("channel %d: filter stops", c->self);
1723                                 if (c->type != SSH_CHANNEL_OPEN)
1724                                         chan_mark_dead(c);
1725                                 else
1726                                         chan_write_failed(c);
1727                                 return -1;
1728                         }
1729                 } else if (c->datagram) {
1730                         buf = data = buffer_get_string(&c->output, &dlen);
1731                 } else {
1732                         buf = data = buffer_ptr(&c->output);
1733                         dlen = buffer_len(&c->output);
1734                 }
1735
1736                 if (c->datagram) {
1737                         /* ignore truncated writes, datagrams might get lost */
1738                         len = write(c->wfd, buf, dlen);
1739                         free(data);
1740                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1741                             errno == EWOULDBLOCK))
1742                                 return 1;
1743                         if (len <= 0) {
1744                                 if (c->type != SSH_CHANNEL_OPEN)
1745                                         chan_mark_dead(c);
1746                                 else
1747                                         chan_write_failed(c);
1748                                 return -1;
1749                         }
1750                         goto out;
1751                 }
1752 #ifdef _AIX
1753                 /* XXX: Later AIX versions can't push as much data to tty */
1754                 if (compat20 && c->wfd_isatty)
1755                         dlen = MIN(dlen, 8*1024);
1756 #endif
1757
1758                 len = write(c->wfd, buf, dlen);
1759                 if (len < 0 &&
1760                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1761                         return 1;
1762                 if (len <= 0) {
1763                         if (c->type != SSH_CHANNEL_OPEN) {
1764                                 debug2("channel %d: not open", c->self);
1765                                 chan_mark_dead(c);
1766                                 return -1;
1767                         } else if (compat13) {
1768                                 buffer_clear(&c->output);
1769                                 debug2("channel %d: input draining.", c->self);
1770                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1771                         } else {
1772                                 chan_write_failed(c);
1773                         }
1774                         return -1;
1775                 }
1776 #ifndef BROKEN_TCGETATTR_ICANON
1777                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1778                         if (tcgetattr(c->wfd, &tio) == 0 &&
1779                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1780                                 /*
1781                                  * Simulate echo to reduce the impact of
1782                                  * traffic analysis. We need to match the
1783                                  * size of a SSH2_MSG_CHANNEL_DATA message
1784                                  * (4 byte channel id + buf)
1785                                  */
1786                                 packet_send_ignore(4 + len);
1787                                 packet_send();
1788                         }
1789                 }
1790 #endif
1791                 buffer_consume(&c->output, len);
1792         }
1793  out:
1794         if (compat20 && olen > 0)
1795                 c->local_consumed += olen - buffer_len(&c->output);
1796         return 1;
1797 }
1798
1799 static int
1800 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1801 {
1802         char buf[CHAN_RBUF];
1803         int len;
1804
1805 /** XXX handle drain efd, too */
1806         if (c->efd != -1) {
1807                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1808                     FD_ISSET(c->efd, writeset) &&
1809                     buffer_len(&c->extended) > 0) {
1810                         len = write(c->efd, buffer_ptr(&c->extended),
1811                             buffer_len(&c->extended));
1812                         debug2("channel %d: written %d to efd %d",
1813                             c->self, len, c->efd);
1814                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1815                             errno == EWOULDBLOCK))
1816                                 return 1;
1817                         if (len <= 0) {
1818                                 debug2("channel %d: closing write-efd %d",
1819                                     c->self, c->efd);
1820                                 channel_close_fd(&c->efd);
1821                         } else {
1822                                 buffer_consume(&c->extended, len);
1823                                 c->local_consumed += len;
1824                         }
1825                 } else if (c->efd != -1 &&
1826                     (c->extended_usage == CHAN_EXTENDED_READ ||
1827                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
1828                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1829                         len = read(c->efd, buf, sizeof(buf));
1830                         debug2("channel %d: read %d from efd %d",
1831                             c->self, len, c->efd);
1832                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1833                             errno == EWOULDBLOCK) && !c->detach_close)))
1834                                 return 1;
1835                         if (len <= 0) {
1836                                 debug2("channel %d: closing read-efd %d",
1837                                     c->self, c->efd);
1838                                 channel_close_fd(&c->efd);
1839                         } else {
1840                                 if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
1841                                         debug3("channel %d: discard efd",
1842                                             c->self);
1843                                 } else
1844                                         buffer_append(&c->extended, buf, len);
1845                         }
1846                 }
1847         }
1848         return 1;
1849 }
1850
1851 static int
1852 channel_check_window(Channel *c)
1853 {
1854         if (c->type == SSH_CHANNEL_OPEN &&
1855             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1856             ((c->local_window_max - c->local_window >
1857             c->local_maxpacket*3) ||
1858             c->local_window < c->local_window_max/2) &&
1859             c->local_consumed > 0) {
1860                 u_int addition = 0;
1861
1862                 /* Adjust max window size if we are in a dynamic environment. */
1863                 if (c->dynamic_window && c->tcpwinsz > c->local_window_max) {
1864                         /*
1865                          * Grow the window somewhat aggressively to maintain
1866                          * pressure.
1867                          */
1868                         addition = 1.5 * (c->tcpwinsz - c->local_window_max);
1869                         c->local_window_max += addition;
1870                 }
1871                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1872                 packet_put_int(c->remote_id);
1873                 packet_put_int(c->local_consumed + addition);
1874                 packet_send();
1875                 debug2("channel %d: window %d sent adjust %d",
1876                     c->self, c->local_window,
1877                     c->local_consumed);
1878                 c->local_window += c->local_consumed + addition;
1879                 c->local_consumed = 0;
1880         }
1881         return 1;
1882 }
1883
1884 static void
1885 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1886 {
1887         channel_handle_rfd(c, readset, writeset);
1888         channel_handle_wfd(c, readset, writeset);
1889         if (!compat20)
1890                 return;
1891         channel_handle_efd(c, readset, writeset);
1892         channel_check_window(c);
1893 }
1894
1895 static u_int
1896 read_mux(Channel *c, u_int need)
1897 {
1898         char buf[CHAN_RBUF];
1899         int len;
1900         u_int rlen;
1901
1902         if (buffer_len(&c->input) < need) {
1903                 rlen = need - buffer_len(&c->input);
1904                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1905                 if (len <= 0) {
1906                         if (errno != EINTR && errno != EAGAIN) {
1907                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1908                                     c->self, c->rfd, len);
1909                                 chan_read_failed(c);
1910                                 return 0;
1911                         }
1912                 } else
1913                         buffer_append(&c->input, buf, len);
1914         }
1915         return buffer_len(&c->input);
1916 }
1917
1918 static void
1919 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1920 {
1921         u_int need;
1922         ssize_t len;
1923
1924         if (!compat20)
1925                 fatal("%s: entered with !compat20", __func__);
1926
1927         if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
1928             (c->istate == CHAN_INPUT_OPEN ||
1929             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1930                 /*
1931                  * Don't not read past the precise end of packets to
1932                  * avoid disrupting fd passing.
1933                  */
1934                 if (read_mux(c, 4) < 4) /* read header */
1935                         return;
1936                 need = get_u32(buffer_ptr(&c->input));
1937 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1938                 if (need > CHANNEL_MUX_MAX_PACKET) {
1939                         debug2("channel %d: packet too big %u > %u",
1940                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1941                         chan_rcvd_oclose(c);
1942                         return;
1943                 }
1944                 if (read_mux(c, need + 4) < need + 4) /* read body */
1945                         return;
1946                 if (c->mux_rcb(c) != 0) {
1947                         debug("channel %d: mux_rcb failed", c->self);
1948                         chan_mark_dead(c);
1949                         return;
1950                 }
1951         }
1952
1953         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1954             buffer_len(&c->output) > 0) {
1955                 len = write(c->wfd, buffer_ptr(&c->output),
1956                     buffer_len(&c->output));
1957                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1958                         return;
1959                 if (len <= 0) {
1960                         chan_mark_dead(c);
1961                         return;
1962                 }
1963                 buffer_consume(&c->output, len);
1964         }
1965 }
1966
1967 static void
1968 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1969 {
1970         Channel *nc;
1971         struct sockaddr_storage addr;
1972         socklen_t addrlen;
1973         int newsock;
1974         uid_t euid;
1975         gid_t egid;
1976
1977         if (!FD_ISSET(c->sock, readset))
1978                 return;
1979
1980         debug("multiplexing control connection");
1981
1982         /*
1983          * Accept connection on control socket
1984          */
1985         memset(&addr, 0, sizeof(addr));
1986         addrlen = sizeof(addr);
1987         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1988             &addrlen)) == -1) {
1989                 error("%s accept: %s", __func__, strerror(errno));
1990                 if (errno == EMFILE || errno == ENFILE)
1991                         c->notbefore = monotime() + 1;
1992                 return;
1993         }
1994
1995         if (getpeereid(newsock, &euid, &egid) < 0) {
1996                 error("%s getpeereid failed: %s", __func__,
1997                     strerror(errno));
1998                 close(newsock);
1999                 return;
2000         }
2001         if ((euid != 0) && (getuid() != euid)) {
2002                 error("multiplex uid mismatch: peer euid %u != uid %u",
2003                     (u_int)euid, (u_int)getuid());
2004                 close(newsock);
2005                 return;
2006         }
2007         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
2008             newsock, newsock, -1, c->local_window_max,
2009             c->local_maxpacket, 0, "mux-control", 1);
2010         nc->mux_rcb = c->mux_rcb;
2011         debug3("%s: new mux channel %d fd %d", __func__,
2012             nc->self, nc->sock);
2013         /* establish state */
2014         nc->mux_rcb(nc);
2015         /* mux state transitions must not elicit protocol messages */
2016         nc->flags |= CHAN_LOCAL;
2017 }
2018
2019 /* ARGSUSED */
2020 static void
2021 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
2022 {
2023         int len;
2024
2025         /* Send buffered output data to the socket. */
2026         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
2027                 len = write(c->sock, buffer_ptr(&c->output),
2028                             buffer_len(&c->output));
2029                 if (len <= 0)
2030                         buffer_clear(&c->output);
2031                 else
2032                         buffer_consume(&c->output, len);
2033         }
2034 }
2035
2036 static void
2037 channel_handler_init_20(void)
2038 {
2039         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2040         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2041         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2042         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
2043         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2044         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2045         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2046         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2047         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
2048         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
2049
2050         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2051         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2052         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
2053         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2054         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2055         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2056         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2057         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
2058         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
2059 }
2060
2061 static void
2062 channel_handler_init_13(void)
2063 {
2064         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
2065         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
2066         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2067         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2068         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2069         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
2070         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
2071         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2072         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2073
2074         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2075         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2076         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2077         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2078         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
2079         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2080         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2081 }
2082
2083 static void
2084 channel_handler_init_15(void)
2085 {
2086         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2087         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2088         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2089         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2090         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2091         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2092         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2093
2094         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2095         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2096         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2097         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2098         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2099         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2100 }
2101
2102 static void
2103 channel_handler_init(void)
2104 {
2105         int i;
2106
2107         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2108                 channel_pre[i] = NULL;
2109                 channel_post[i] = NULL;
2110         }
2111         if (compat20)
2112                 channel_handler_init_20();
2113         else if (compat13)
2114                 channel_handler_init_13();
2115         else
2116                 channel_handler_init_15();
2117 }
2118
2119 /* gc dead channels */
2120 static void
2121 channel_garbage_collect(Channel *c)
2122 {
2123         if (c == NULL)
2124                 return;
2125         if (c->detach_user != NULL) {
2126                 if (!chan_is_dead(c, c->detach_close))
2127                         return;
2128                 debug2("channel %d: gc: notify user", c->self);
2129                 c->detach_user(c->self, NULL);
2130                 /* if we still have a callback */
2131                 if (c->detach_user != NULL)
2132                         return;
2133                 debug2("channel %d: gc: user detached", c->self);
2134         }
2135         if (!chan_is_dead(c, 1))
2136                 return;
2137         debug2("channel %d: garbage collecting", c->self);
2138         channel_free(c);
2139 }
2140
2141 static void
2142 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
2143     time_t *unpause_secs)
2144 {
2145         static int did_init = 0;
2146         u_int i, oalloc;
2147         Channel *c;
2148         time_t now;
2149
2150         if (!did_init) {
2151                 channel_handler_init();
2152                 did_init = 1;
2153         }
2154         now = monotime();
2155         if (unpause_secs != NULL)
2156                 *unpause_secs = 0;
2157         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2158                 c = channels[i];
2159                 if (c == NULL)
2160                         continue;
2161                 if (c->delayed) {
2162                         if (ftab == channel_pre)
2163                                 c->delayed = 0;
2164                         else
2165                                 continue;
2166                 }
2167                 if (ftab[c->type] != NULL) {
2168                         /*
2169                          * Run handlers that are not paused.
2170                          */
2171                         if (c->notbefore <= now)
2172                                 (*ftab[c->type])(c, readset, writeset);
2173                         else if (unpause_secs != NULL) {
2174                                 /*
2175                                  * Collect the time that the earliest
2176                                  * channel comes off pause.
2177                                  */
2178                                 debug3("%s: chan %d: skip for %d more seconds",
2179                                     __func__, c->self,
2180                                     (int)(c->notbefore - now));
2181                                 if (*unpause_secs == 0 ||
2182                                     (c->notbefore - now) < *unpause_secs)
2183                                         *unpause_secs = c->notbefore - now;
2184                         }
2185                 }
2186                 channel_garbage_collect(c);
2187         }
2188         if (unpause_secs != NULL && *unpause_secs != 0)
2189                 debug3("%s: first channel unpauses in %d seconds",
2190                     __func__, (int)*unpause_secs);
2191 }
2192
2193 /*
2194  * Allocate/update select bitmasks and add any bits relevant to channels in
2195  * select bitmasks.
2196  */
2197 void
2198 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2199     u_int *nallocp, time_t *minwait_secs, int rekeying)
2200 {
2201         u_int n, sz, nfdset;
2202
2203         n = MAX(*maxfdp, channel_max_fd);
2204
2205         nfdset = howmany(n+1, NFDBITS);
2206         /* Explicitly test here, because xrealloc isn't always called */
2207         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
2208                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2209         sz = nfdset * sizeof(fd_mask);
2210
2211         /* perhaps check sz < nalloc/2 and shrink? */
2212         if (*readsetp == NULL || sz > *nallocp) {
2213                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2214                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2215                 *nallocp = sz;
2216         }
2217         *maxfdp = n;
2218         memset(*readsetp, 0, sz);
2219         memset(*writesetp, 0, sz);
2220
2221         if (!rekeying)
2222                 channel_handler(channel_pre, *readsetp, *writesetp,
2223                     minwait_secs);
2224 }
2225
2226 /*
2227  * After select, perform any appropriate operations for channels which have
2228  * events pending.
2229  */
2230 void
2231 channel_after_select(fd_set *readset, fd_set *writeset)
2232 {
2233         channel_handler(channel_post, readset, writeset, NULL);
2234 }
2235
2236
2237 /* If there is data to send to the connection, enqueue some of it now. */
2238 void
2239 channel_output_poll(void)
2240 {
2241         Channel *c;
2242         u_int i, len;
2243
2244         for (i = 0; i < channels_alloc; i++) {
2245                 c = channels[i];
2246                 if (c == NULL)
2247                         continue;
2248
2249                 /*
2250                  * We are only interested in channels that can have buffered
2251                  * incoming data.
2252                  */
2253                 if (compat13) {
2254                         if (c->type != SSH_CHANNEL_OPEN &&
2255                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2256                                 continue;
2257                 } else {
2258                         if (c->type != SSH_CHANNEL_OPEN)
2259                                 continue;
2260                 }
2261                 if (compat20 &&
2262                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2263                         /* XXX is this true? */
2264                         debug3("channel %d: will not send data after close", c->self);
2265                         continue;
2266                 }
2267
2268                 /* Get the amount of buffered data for this channel. */
2269                 if ((c->istate == CHAN_INPUT_OPEN ||
2270                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2271                     (len = buffer_len(&c->input)) > 0) {
2272                         if (c->datagram) {
2273                                 if (len > 0) {
2274                                         u_char *data;
2275                                         u_int dlen;
2276
2277                                         data = buffer_get_string(&c->input,
2278                                             &dlen);
2279                                         if (dlen > c->remote_window ||
2280                                             dlen > c->remote_maxpacket) {
2281                                                 debug("channel %d: datagram "
2282                                                     "too big for channel",
2283                                                     c->self);
2284                                                 free(data);
2285                                                 continue;
2286                                         }
2287                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2288                                         packet_put_int(c->remote_id);
2289                                         packet_put_string(data, dlen);
2290                                         packet_send();
2291                                         c->remote_window -= dlen + 4;
2292                                         free(data);
2293                                 }
2294                                 continue;
2295                         }
2296                         /*
2297                          * Send some data for the other side over the secure
2298                          * connection.
2299                          */
2300                         if (compat20) {
2301                                 if (len > c->remote_window)
2302                                         len = c->remote_window;
2303                                 if (len > c->remote_maxpacket)
2304                                         len = c->remote_maxpacket;
2305                         } else {
2306                                 if (packet_is_interactive()) {
2307                                         if (len > 1024)
2308                                                 len = 512;
2309                                 } else {
2310                                         /* Keep the packets at reasonable size. */
2311                                         if (len > packet_get_maxsize()/2)
2312                                                 len = packet_get_maxsize()/2;
2313                                 }
2314                         }
2315                         if (len > 0) {
2316                                 packet_start(compat20 ?
2317                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2318                                 packet_put_int(c->remote_id);
2319                                 packet_put_string(buffer_ptr(&c->input), len);
2320                                 packet_send();
2321                                 buffer_consume(&c->input, len);
2322                                 c->remote_window -= len;
2323                         }
2324                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2325                         if (compat13)
2326                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2327                         /*
2328                          * input-buffer is empty and read-socket shutdown:
2329                          * tell peer, that we will not send more data: send IEOF.
2330                          * hack for extended data: delay EOF if EFD still in use.
2331                          */
2332                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2333                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2334                                     c->self, c->efd, buffer_len(&c->extended));
2335                         else
2336                                 chan_ibuf_empty(c);
2337                 }
2338                 /* Send extended data, i.e. stderr */
2339                 if (compat20 &&
2340                     !(c->flags & CHAN_EOF_SENT) &&
2341                     c->remote_window > 0 &&
2342                     (len = buffer_len(&c->extended)) > 0 &&
2343                     c->extended_usage == CHAN_EXTENDED_READ) {
2344                         debug2("channel %d: rwin %u elen %u euse %d",
2345                             c->self, c->remote_window, buffer_len(&c->extended),
2346                             c->extended_usage);
2347                         if (len > c->remote_window)
2348                                 len = c->remote_window;
2349                         if (len > c->remote_maxpacket)
2350                                 len = c->remote_maxpacket;
2351                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2352                         packet_put_int(c->remote_id);
2353                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2354                         packet_put_string(buffer_ptr(&c->extended), len);
2355                         packet_send();
2356                         buffer_consume(&c->extended, len);
2357                         c->remote_window -= len;
2358                         debug2("channel %d: sent ext data %d", c->self, len);
2359                 }
2360         }
2361 }
2362
2363
2364 /* -- protocol input */
2365
2366 /* ARGSUSED */
2367 void
2368 channel_input_data(int type, u_int32_t seq, void *ctxt)
2369 {
2370         int id;
2371         char *data;
2372         u_int data_len, win_len;
2373         Channel *c;
2374
2375         /* Get the channel number and verify it. */
2376         id = packet_get_int();
2377         c = channel_lookup(id);
2378         if (c == NULL)
2379                 packet_disconnect("Received data for nonexistent channel %d.", id);
2380
2381         /* Ignore any data for non-open channels (might happen on close) */
2382         if (c->type != SSH_CHANNEL_OPEN &&
2383             c->type != SSH_CHANNEL_X11_OPEN)
2384                 return;
2385
2386         /* Get the data. */
2387         data = packet_get_string_ptr(&data_len);
2388         win_len = data_len;
2389         if (c->datagram)
2390                 win_len += 4;  /* string length header */
2391
2392         /*
2393          * Ignore data for protocol > 1.3 if output end is no longer open.
2394          * For protocol 2 the sending side is reducing its window as it sends
2395          * data, so we must 'fake' consumption of the data in order to ensure
2396          * that window updates are sent back.  Otherwise the connection might
2397          * deadlock.
2398          */
2399         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2400                 if (compat20) {
2401                         c->local_window -= win_len;
2402                         c->local_consumed += win_len;
2403                 }
2404                 return;
2405         }
2406
2407         if (compat20) {
2408                 if (win_len > c->local_maxpacket) {
2409                         logit("channel %d: rcvd big packet %d, maxpack %d",
2410                             c->self, win_len, c->local_maxpacket);
2411                 }
2412                 if (win_len > c->local_window) {
2413                         logit("channel %d: rcvd too much data %d, win %d",
2414                             c->self, win_len, c->local_window);
2415                         return;
2416                 }
2417                 c->local_window -= win_len;
2418         }
2419         if (c->datagram)
2420                 buffer_put_string(&c->output, data, data_len);
2421         else
2422                 buffer_append(&c->output, data, data_len);
2423         packet_check_eom();
2424 }
2425
2426 /* ARGSUSED */
2427 void
2428 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2429 {
2430         int id;
2431         char *data;
2432         u_int data_len, tcode;
2433         Channel *c;
2434
2435         /* Get the channel number and verify it. */
2436         id = packet_get_int();
2437         c = channel_lookup(id);
2438
2439         if (c == NULL)
2440                 packet_disconnect("Received extended_data for bad channel %d.", id);
2441         if (c->type != SSH_CHANNEL_OPEN) {
2442                 logit("channel %d: ext data for non open", id);
2443                 return;
2444         }
2445         if (c->flags & CHAN_EOF_RCVD) {
2446                 if (datafellows & SSH_BUG_EXTEOF)
2447                         debug("channel %d: accepting ext data after eof", id);
2448                 else
2449                         packet_disconnect("Received extended_data after EOF "
2450                             "on channel %d.", id);
2451         }
2452         tcode = packet_get_int();
2453         if (c->efd == -1 ||
2454             c->extended_usage != CHAN_EXTENDED_WRITE ||
2455             tcode != SSH2_EXTENDED_DATA_STDERR) {
2456                 logit("channel %d: bad ext data", c->self);
2457                 return;
2458         }
2459         data = packet_get_string(&data_len);
2460         packet_check_eom();
2461         if (data_len > c->local_window) {
2462                 logit("channel %d: rcvd too much extended_data %d, win %d",
2463                     c->self, data_len, c->local_window);
2464                 free(data);
2465                 return;
2466         }
2467         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2468         c->local_window -= data_len;
2469         buffer_append(&c->extended, data, data_len);
2470         free(data);
2471 }
2472
2473 /* ARGSUSED */
2474 void
2475 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2476 {
2477         int id;
2478         Channel *c;
2479
2480         id = packet_get_int();
2481         packet_check_eom();
2482         c = channel_lookup(id);
2483         if (c == NULL)
2484                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2485         chan_rcvd_ieof(c);
2486
2487         /* XXX force input close */
2488         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2489                 debug("channel %d: FORCE input drain", c->self);
2490                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2491                 if (buffer_len(&c->input) == 0)
2492                         chan_ibuf_empty(c);
2493         }
2494
2495 }
2496
2497 /* ARGSUSED */
2498 void
2499 channel_input_close(int type, u_int32_t seq, void *ctxt)
2500 {
2501         int id;
2502         Channel *c;
2503
2504         id = packet_get_int();
2505         packet_check_eom();
2506         c = channel_lookup(id);
2507         if (c == NULL)
2508                 packet_disconnect("Received close for nonexistent channel %d.", id);
2509
2510         /*
2511          * Send a confirmation that we have closed the channel and no more
2512          * data is coming for it.
2513          */
2514         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2515         packet_put_int(c->remote_id);
2516         packet_send();
2517
2518         /*
2519          * If the channel is in closed state, we have sent a close request,
2520          * and the other side will eventually respond with a confirmation.
2521          * Thus, we cannot free the channel here, because then there would be
2522          * no-one to receive the confirmation.  The channel gets freed when
2523          * the confirmation arrives.
2524          */
2525         if (c->type != SSH_CHANNEL_CLOSED) {
2526                 /*
2527                  * Not a closed channel - mark it as draining, which will
2528                  * cause it to be freed later.
2529                  */
2530                 buffer_clear(&c->input);
2531                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2532         }
2533 }
2534
2535 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2536 /* ARGSUSED */
2537 void
2538 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2539 {
2540         int id = packet_get_int();
2541         Channel *c = channel_lookup(id);
2542
2543         packet_check_eom();
2544         if (c == NULL)
2545                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2546         chan_rcvd_oclose(c);
2547 }
2548
2549 /* ARGSUSED */
2550 void
2551 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2552 {
2553         int id = packet_get_int();
2554         Channel *c = channel_lookup(id);
2555
2556         packet_check_eom();
2557         if (c == NULL)
2558                 packet_disconnect("Received close confirmation for "
2559                     "out-of-range channel %d.", id);
2560         if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
2561                 packet_disconnect("Received close confirmation for "
2562                     "non-closed channel %d (type %d).", id, c->type);
2563         channel_free(c);
2564 }
2565
2566 /* ARGSUSED */
2567 void
2568 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2569 {
2570         int id, remote_id;
2571         Channel *c;
2572
2573         id = packet_get_int();
2574         c = channel_lookup(id);
2575
2576         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2577                 packet_disconnect("Received open confirmation for "
2578                     "non-opening channel %d.", id);
2579         remote_id = packet_get_int();
2580         /* Record the remote channel number and mark that the channel is now open. */
2581         c->remote_id = remote_id;
2582         c->type = SSH_CHANNEL_OPEN;
2583
2584         if (compat20) {
2585                 c->remote_window = packet_get_int();
2586                 c->remote_maxpacket = packet_get_int();
2587                 if (c->open_confirm) {
2588                         debug2("callback start");
2589                         c->open_confirm(c->self, 1, c->open_confirm_ctx);
2590                         debug2("callback done");
2591                 }
2592                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2593                     c->remote_window, c->remote_maxpacket);
2594         }
2595         packet_check_eom();
2596 }
2597
2598 static char *
2599 reason2txt(int reason)
2600 {
2601         switch (reason) {
2602         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2603                 return "administratively prohibited";
2604         case SSH2_OPEN_CONNECT_FAILED:
2605                 return "connect failed";
2606         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2607                 return "unknown channel type";
2608         case SSH2_OPEN_RESOURCE_SHORTAGE:
2609                 return "resource shortage";
2610         }
2611         return "unknown reason";
2612 }
2613
2614 /* ARGSUSED */
2615 void
2616 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2617 {
2618         int id, reason;
2619         char *msg = NULL, *lang = NULL;
2620         Channel *c;
2621
2622         id = packet_get_int();
2623         c = channel_lookup(id);
2624
2625         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2626                 packet_disconnect("Received open failure for "
2627                     "non-opening channel %d.", id);
2628         if (compat20) {
2629                 reason = packet_get_int();
2630                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2631                         msg  = packet_get_string(NULL);
2632                         lang = packet_get_string(NULL);
2633                 }
2634                 logit("channel %d: open failed: %s%s%s", id,
2635                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2636                 free(msg);
2637                 free(lang);
2638                 if (c->open_confirm) {
2639                         debug2("callback start");
2640                         c->open_confirm(c->self, 0, c->open_confirm_ctx);
2641                         debug2("callback done");
2642                 }
2643         }
2644         packet_check_eom();
2645         /* Schedule the channel for cleanup/deletion. */
2646         chan_mark_dead(c);
2647 }
2648
2649 /* ARGSUSED */
2650 void
2651 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2652 {
2653         Channel *c;
2654         int id;
2655         u_int adjust;
2656
2657         if (!compat20)
2658                 return;
2659
2660         /* Get the channel number and verify it. */
2661         id = packet_get_int();
2662         c = channel_lookup(id);
2663
2664         if (c == NULL) {
2665                 logit("Received window adjust for non-open channel %d.", id);
2666                 return;
2667         }
2668         adjust = packet_get_int();
2669         packet_check_eom();
2670         debug2("channel %d: rcvd adjust %u", id, adjust);
2671         c->remote_window += adjust;
2672 }
2673
2674 /* ARGSUSED */
2675 void
2676 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2677 {
2678         Channel *c = NULL;
2679         u_short host_port;
2680         char *host, *originator_string;
2681         int remote_id;
2682
2683         remote_id = packet_get_int();
2684         host = packet_get_string(NULL);
2685         host_port = packet_get_int();
2686
2687         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2688                 originator_string = packet_get_string(NULL);
2689         } else {
2690                 originator_string = xstrdup("unknown (remote did not supply name)");
2691         }
2692         packet_check_eom();
2693         c = channel_connect_to(host, host_port,
2694             "connected socket", originator_string);
2695         free(originator_string);
2696         free(host);
2697         if (c == NULL) {
2698                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2699                 packet_put_int(remote_id);
2700                 packet_send();
2701         } else
2702                 c->remote_id = remote_id;
2703 }
2704
2705 /* ARGSUSED */
2706 void
2707 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2708 {
2709         Channel *c;
2710         struct channel_confirm *cc;
2711         int id;
2712
2713         /* Reset keepalive timeout */
2714         packet_set_alive_timeouts(0);
2715
2716         id = packet_get_int();
2717         packet_check_eom();
2718
2719         debug2("channel_input_status_confirm: type %d id %d", type, id);
2720
2721         if ((c = channel_lookup(id)) == NULL) {
2722                 logit("channel_input_status_confirm: %d: unknown", id);
2723                 return;
2724         }
2725         ;
2726         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2727                 return;
2728         cc->cb(type, c, cc->ctx);
2729         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2730         explicit_bzero(cc, sizeof(*cc));
2731         free(cc);
2732 }
2733
2734 /* -- tcp forwarding */
2735
2736 void
2737 channel_set_af(int af)
2738 {
2739         IPv4or6 = af;
2740 }
2741
2742 void
2743 channel_set_hpn(int disabled, u_int buf_size)
2744 {
2745         hpn_disabled = disabled;
2746         buffer_size = buf_size;
2747         debug("HPN Disabled: %d, HPN Buffer Size: %d",
2748             hpn_disabled, buffer_size);
2749 }
2750
2751 /*
2752  * Determine whether or not a port forward listens to loopback, the
2753  * specified address or wildcard. On the client, a specified bind
2754  * address will always override gateway_ports. On the server, a
2755  * gateway_ports of 1 (``yes'') will override the client's specification
2756  * and force a wildcard bind, whereas a value of 2 (``clientspecified'')
2757  * will bind to whatever address the client asked for.
2758  *
2759  * Special-case listen_addrs are:
2760  *
2761  * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2762  * "" (empty string), "*"  -> wildcard v4/v6
2763  * "localhost"             -> loopback v4/v6
2764  */
2765 static const char *
2766 channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
2767     int is_client, int gateway_ports)
2768 {
2769         const char *addr = NULL;
2770         int wildcard = 0;
2771
2772         if (listen_addr == NULL) {
2773                 /* No address specified: default to gateway_ports setting */
2774                 if (gateway_ports)
2775                         wildcard = 1;
2776         } else if (gateway_ports || is_client) {
2777                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2778                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2779                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2780                     (!is_client && gateway_ports == 1)) {
2781                         wildcard = 1;
2782                         /*
2783                          * Notify client if they requested a specific listen
2784                          * address and it was overridden.
2785                          */
2786                         if (*listen_addr != '\0' &&
2787                             strcmp(listen_addr, "0.0.0.0") != 0 &&
2788                             strcmp(listen_addr, "*") != 0) {
2789                                 packet_send_debug("Forwarding listen address "
2790                                     "\"%s\" overridden by server "
2791                                     "GatewayPorts", listen_addr);
2792                         }
2793                 }
2794                 else if (strcmp(listen_addr, "localhost") != 0)
2795                         addr = listen_addr;
2796         }
2797         if (wildcardp != NULL)
2798                 *wildcardp = wildcard;
2799         return addr;
2800 }
2801
2802 static int
2803 channel_setup_fwd_listener(int type, const char *listen_addr,
2804     u_short listen_port, int *allocated_listen_port,
2805     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2806 {
2807         Channel *c;
2808         int sock, r, success = 0, wildcard = 0, is_client;
2809         struct addrinfo hints, *ai, *aitop;
2810         const char *host, *addr;
2811         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2812         in_port_t *lport_p;
2813
2814         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2815             listen_addr : host_to_connect;
2816         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2817
2818         if (host == NULL) {
2819                 error("No forward host name.");
2820                 return 0;
2821         }
2822         if (strlen(host) >= NI_MAXHOST) {
2823                 error("Forward host name too long.");
2824                 return 0;
2825         }
2826
2827         /* Determine the bind address, cf. channel_fwd_bind_addr() comment */
2828         addr = channel_fwd_bind_addr(listen_addr, &wildcard,
2829             is_client, gateway_ports);
2830         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2831             type, wildcard, (addr == NULL) ? "NULL" : addr);
2832
2833         /*
2834          * getaddrinfo returns a loopback address if the hostname is
2835          * set to NULL and hints.ai_flags is not AI_PASSIVE
2836          */
2837         memset(&hints, 0, sizeof(hints));
2838         hints.ai_family = IPv4or6;
2839         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2840         hints.ai_socktype = SOCK_STREAM;
2841         snprintf(strport, sizeof strport, "%d", listen_port);
2842         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2843                 if (addr == NULL) {
2844                         /* This really shouldn't happen */
2845                         packet_disconnect("getaddrinfo: fatal error: %s",
2846                             ssh_gai_strerror(r));
2847                 } else {
2848                         error("channel_setup_fwd_listener: "
2849                             "getaddrinfo(%.64s): %s", addr,
2850                             ssh_gai_strerror(r));
2851                 }
2852                 return 0;
2853         }
2854         if (allocated_listen_port != NULL)
2855                 *allocated_listen_port = 0;
2856         for (ai = aitop; ai; ai = ai->ai_next) {
2857                 switch (ai->ai_family) {
2858                 case AF_INET:
2859                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2860                             sin_port;
2861                         break;
2862                 case AF_INET6:
2863                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2864                             sin6_port;
2865                         break;
2866                 default:
2867                         continue;
2868                 }
2869                 /*
2870                  * If allocating a port for -R forwards, then use the
2871                  * same port for all address families.
2872                  */
2873                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2874                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2875                         *lport_p = htons(*allocated_listen_port);
2876
2877                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2878                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2879                         error("channel_setup_fwd_listener: getnameinfo failed");
2880                         continue;
2881                 }
2882                 /* Create a port to listen for the host. */
2883                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2884                 if (sock < 0) {
2885                         /* this is no error since kernel may not support ipv6 */
2886                         verbose("socket: %.100s", strerror(errno));
2887                         continue;
2888                 }
2889
2890                 channel_set_reuseaddr(sock);
2891                 if (ai->ai_family == AF_INET6)
2892                         sock_set_v6only(sock);
2893
2894                 debug("Local forwarding listening on %s port %s.",
2895                     ntop, strport);
2896
2897                 /* Bind the socket to the address. */
2898                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2899                         /* address can be in use ipv6 address is already bound */
2900                         if (!ai->ai_next)
2901                                 error("bind: %.100s", strerror(errno));
2902                         else
2903                                 verbose("bind: %.100s", strerror(errno));
2904
2905                         close(sock);
2906                         continue;
2907                 }
2908                 /* Start listening for connections on the socket. */
2909                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2910                         error("listen: %.100s", strerror(errno));
2911                         close(sock);
2912                         continue;
2913                 }
2914
2915                 /*
2916                  * listen_port == 0 requests a dynamically allocated port -
2917                  * record what we got.
2918                  */
2919                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2920                     allocated_listen_port != NULL &&
2921                     *allocated_listen_port == 0) {
2922                         *allocated_listen_port = get_sock_port(sock, 1);
2923                         debug("Allocated listen port %d",
2924                             *allocated_listen_port);
2925                 }
2926
2927                 /*
2928                  * Allocate a channel number for the socket.  Explicitly test
2929                  * for hpn disabled option.  If true use smaller window size.
2930                  */
2931                 if (hpn_disabled)
2932                         c = channel_new("port listener", type, sock, sock, -1,
2933                             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2934                             0, "port listener", 1);
2935                 else
2936                         c = channel_new("port listener", type, sock, sock, -1,
2937                             buffer_size, CHAN_TCP_PACKET_DEFAULT,
2938                             0, "port listener", 1);
2939                 c->path = xstrdup(host);
2940                 c->host_port = port_to_connect;
2941                 c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
2942                 if (listen_port == 0 && allocated_listen_port != NULL &&
2943                     !(datafellows & SSH_BUG_DYNAMIC_RPORT))
2944                         c->listening_port = *allocated_listen_port;
2945                 else
2946                         c->listening_port = listen_port;
2947                 success = 1;
2948         }
2949         if (success == 0)
2950                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2951                     listen_port);
2952         freeaddrinfo(aitop);
2953         return success;
2954 }
2955
2956 int
2957 channel_cancel_rport_listener(const char *host, u_short port)
2958 {
2959         u_int i;
2960         int found = 0;
2961
2962         for (i = 0; i < channels_alloc; i++) {
2963                 Channel *c = channels[i];
2964                 if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
2965                         continue;
2966                 if (strcmp(c->path, host) == 0 && c->listening_port == port) {
2967                         debug2("%s: close channel %d", __func__, i);
2968                         channel_free(c);
2969                         found = 1;
2970                 }
2971         }
2972
2973         return (found);
2974 }
2975
2976 int
2977 channel_cancel_lport_listener(const char *lhost, u_short lport,
2978     int cport, int gateway_ports)
2979 {
2980         u_int i;
2981         int found = 0;
2982         const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, gateway_ports);
2983
2984         for (i = 0; i < channels_alloc; i++) {
2985                 Channel *c = channels[i];
2986                 if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
2987                         continue;
2988                 if (c->listening_port != lport)
2989                         continue;
2990                 if (cport == CHANNEL_CANCEL_PORT_STATIC) {
2991                         /* skip dynamic forwardings */
2992                         if (c->host_port == 0)
2993                                 continue;
2994                 } else {
2995                         if (c->host_port != cport)
2996                                 continue;
2997                 }
2998                 if ((c->listening_addr == NULL && addr != NULL) ||
2999                     (c->listening_addr != NULL && addr == NULL))
3000                         continue;
3001                 if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
3002                         debug2("%s: close channel %d", __func__, i);
3003                         channel_free(c);
3004                         found = 1;
3005                 }
3006         }
3007
3008         return (found);
3009 }
3010
3011 /* protocol local port fwd, used by ssh (and sshd in v1) */
3012 int
3013 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
3014     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
3015 {
3016         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
3017             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
3018             gateway_ports);
3019 }
3020
3021 /* protocol v2 remote port fwd, used by sshd */
3022 int
3023 channel_setup_remote_fwd_listener(const char *listen_address,
3024     u_short listen_port, int *allocated_listen_port, int gateway_ports)
3025 {
3026         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
3027             listen_address, listen_port, allocated_listen_port,
3028             NULL, 0, gateway_ports);
3029 }
3030
3031 /*
3032  * Translate the requested rfwd listen host to something usable for
3033  * this server.
3034  */
3035 static const char *
3036 channel_rfwd_bind_host(const char *listen_host)
3037 {
3038         if (listen_host == NULL) {
3039                 if (datafellows & SSH_BUG_RFWD_ADDR)
3040                         return "127.0.0.1";
3041                 else
3042                         return "localhost";
3043         } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
3044                 if (datafellows & SSH_BUG_RFWD_ADDR)
3045                         return "0.0.0.0";
3046                 else
3047                         return "";
3048         } else
3049                 return listen_host;
3050 }
3051
3052 /*
3053  * Initiate forwarding of connections to port "port" on remote host through
3054  * the secure channel to host:port from local side.
3055  * Returns handle (index) for updating the dynamic listen port with
3056  * channel_update_permitted_opens().
3057  */
3058 int
3059 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
3060     const char *host_to_connect, u_short port_to_connect)
3061 {
3062         int type, success = 0, idx = -1;
3063
3064         /* Send the forward request to the remote side. */
3065         if (compat20) {
3066                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
3067                 packet_put_cstring("tcpip-forward");
3068                 packet_put_char(1);             /* boolean: want reply */
3069                 packet_put_cstring(channel_rfwd_bind_host(listen_host));
3070                 packet_put_int(listen_port);
3071                 packet_send();
3072                 packet_write_wait();
3073                 /* Assume that server accepts the request */
3074                 success = 1;
3075         } else {
3076                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
3077                 packet_put_int(listen_port);
3078                 packet_put_cstring(host_to_connect);
3079                 packet_put_int(port_to_connect);
3080                 packet_send();
3081                 packet_write_wait();
3082
3083                 /* Wait for response from the remote side. */
3084                 type = packet_read();
3085                 switch (type) {
3086                 case SSH_SMSG_SUCCESS:
3087                         success = 1;
3088                         break;
3089                 case SSH_SMSG_FAILURE:
3090                         break;
3091                 default:
3092                         /* Unknown packet */
3093                         packet_disconnect("Protocol error for port forward request:"
3094                             "received packet type %d.", type);
3095                 }
3096         }
3097         if (success) {
3098                 /* Record that connection to this host/port is permitted. */
3099                 permitted_opens = xrealloc(permitted_opens,
3100                     num_permitted_opens + 1, sizeof(*permitted_opens));
3101                 idx = num_permitted_opens++;
3102                 permitted_opens[idx].host_to_connect = xstrdup(host_to_connect);
3103                 permitted_opens[idx].port_to_connect = port_to_connect;
3104                 permitted_opens[idx].listen_port = listen_port;
3105         }
3106         return (idx);
3107 }
3108
3109 /*
3110  * Request cancellation of remote forwarding of connection host:port from
3111  * local side.
3112  */
3113 int
3114 channel_request_rforward_cancel(const char *host, u_short port)
3115 {
3116         int i;
3117
3118         if (!compat20)
3119                 return -1;
3120
3121         for (i = 0; i < num_permitted_opens; i++) {
3122                 if (permitted_opens[i].host_to_connect != NULL &&
3123                     permitted_opens[i].listen_port == port)
3124                         break;
3125         }
3126         if (i >= num_permitted_opens) {
3127                 debug("%s: requested forward not found", __func__);
3128                 return -1;
3129         }
3130         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3131         packet_put_cstring("cancel-tcpip-forward");
3132         packet_put_char(0);
3133         packet_put_cstring(channel_rfwd_bind_host(host));
3134         packet_put_int(port);
3135         packet_send();
3136
3137         permitted_opens[i].listen_port = 0;
3138         permitted_opens[i].port_to_connect = 0;
3139         free(permitted_opens[i].host_to_connect);
3140         permitted_opens[i].host_to_connect = NULL;
3141
3142         return 0;
3143 }
3144
3145 /*
3146  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
3147  * listening for the port, and sends back a success reply (or disconnect
3148  * message if there was an error).
3149  */
3150 int
3151 channel_input_port_forward_request(int is_root, int gateway_ports)
3152 {
3153         u_short port, host_port;
3154         int success = 0;
3155         char *hostname;
3156
3157         /* Get arguments from the packet. */
3158         port = packet_get_int();
3159         hostname = packet_get_string(NULL);
3160         host_port = packet_get_int();
3161
3162 #ifndef HAVE_CYGWIN
3163         /*
3164          * Check that an unprivileged user is not trying to forward a
3165          * privileged port.
3166          */
3167         if (port < IPPORT_RESERVED && !is_root)
3168                 packet_disconnect(
3169                     "Requested forwarding of port %d but user is not root.",
3170                     port);
3171         if (host_port == 0)
3172                 packet_disconnect("Dynamic forwarding denied.");
3173 #endif
3174
3175         /* Initiate forwarding */
3176         success = channel_setup_local_fwd_listener(NULL, port, hostname,
3177             host_port, gateway_ports);
3178
3179         /* Free the argument string. */
3180         free(hostname);
3181
3182         return (success ? 0 : -1);
3183 }
3184
3185 /*
3186  * Permits opening to any host/port if permitted_opens[] is empty.  This is
3187  * usually called by the server, because the user could connect to any port
3188  * anyway, and the server has no way to know but to trust the client anyway.
3189  */
3190 void
3191 channel_permit_all_opens(void)
3192 {
3193         if (num_permitted_opens == 0)
3194                 all_opens_permitted = 1;
3195 }
3196
3197 void
3198 channel_add_permitted_opens(char *host, int port)
3199 {
3200         debug("allow port forwarding to host %s port %d", host, port);
3201
3202         permitted_opens = xrealloc(permitted_opens,
3203             num_permitted_opens + 1, sizeof(*permitted_opens));
3204         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
3205         permitted_opens[num_permitted_opens].port_to_connect = port;
3206         num_permitted_opens++;
3207
3208         all_opens_permitted = 0;
3209 }
3210
3211 /*
3212  * Update the listen port for a dynamic remote forward, after
3213  * the actual 'newport' has been allocated. If 'newport' < 0 is
3214  * passed then they entry will be invalidated.
3215  */
3216 void
3217 channel_update_permitted_opens(int idx, int newport)
3218 {
3219         if (idx < 0 || idx >= num_permitted_opens) {
3220                 debug("channel_update_permitted_opens: index out of range:"
3221                     " %d num_permitted_opens %d", idx, num_permitted_opens);
3222                 return;
3223         }
3224         debug("%s allowed port %d for forwarding to host %s port %d",
3225             newport > 0 ? "Updating" : "Removing",
3226             newport,
3227             permitted_opens[idx].host_to_connect,
3228             permitted_opens[idx].port_to_connect);
3229         if (newport >= 0)  {
3230                 permitted_opens[idx].listen_port =
3231                     (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
3232         } else {
3233                 permitted_opens[idx].listen_port = 0;
3234                 permitted_opens[idx].port_to_connect = 0;
3235                 free(permitted_opens[idx].host_to_connect);
3236                 permitted_opens[idx].host_to_connect = NULL;
3237         }
3238 }
3239
3240 int
3241 channel_add_adm_permitted_opens(char *host, int port)
3242 {
3243         debug("config allows port forwarding to host %s port %d", host, port);
3244
3245         permitted_adm_opens = xrealloc(permitted_adm_opens,
3246             num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
3247         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3248              = xstrdup(host);
3249         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3250         return ++num_adm_permitted_opens;
3251 }
3252
3253 void
3254 channel_disable_adm_local_opens(void)
3255 {
3256         channel_clear_adm_permitted_opens();
3257         permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
3258         permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
3259         num_adm_permitted_opens = 1;
3260 }
3261
3262 void
3263 channel_clear_permitted_opens(void)
3264 {
3265         int i;
3266
3267         for (i = 0; i < num_permitted_opens; i++)
3268                 free(permitted_opens[i].host_to_connect);
3269         free(permitted_opens);
3270         permitted_opens = NULL;
3271         num_permitted_opens = 0;
3272 }
3273
3274 void
3275 channel_clear_adm_permitted_opens(void)
3276 {
3277         int i;
3278
3279         for (i = 0; i < num_adm_permitted_opens; i++)
3280                 free(permitted_adm_opens[i].host_to_connect);
3281         free(permitted_adm_opens);
3282         permitted_adm_opens = NULL;
3283         num_adm_permitted_opens = 0;
3284 }
3285
3286 void
3287 channel_print_adm_permitted_opens(void)
3288 {
3289         int i;
3290
3291         printf("permitopen");
3292         if (num_adm_permitted_opens == 0) {
3293                 printf(" any\n");
3294                 return;
3295         }
3296         for (i = 0; i < num_adm_permitted_opens; i++)
3297                 if (permitted_adm_opens[i].host_to_connect == NULL)
3298                         printf(" none");
3299                 else
3300                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3301                             permitted_adm_opens[i].port_to_connect);
3302         printf("\n");
3303 }
3304
3305 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
3306 int
3307 permitopen_port(const char *p)
3308 {
3309         int port;
3310
3311         if (strcmp(p, "*") == 0)
3312                 return FWD_PERMIT_ANY_PORT;
3313         if ((port = a2port(p)) > 0)
3314                 return port;
3315         return -1;
3316 }
3317
3318 static int
3319 port_match(u_short allowedport, u_short requestedport)
3320 {
3321         if (allowedport == FWD_PERMIT_ANY_PORT ||
3322             allowedport == requestedport)
3323                 return 1;
3324         return 0;
3325 }
3326
3327 /* Try to start non-blocking connect to next host in cctx list */
3328 static int
3329 connect_next(struct channel_connect *cctx)
3330 {
3331         int sock, saved_errno;
3332         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
3333
3334         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3335                 if (cctx->ai->ai_family != AF_INET &&
3336                     cctx->ai->ai_family != AF_INET6)
3337                         continue;
3338                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3339                     ntop, sizeof(ntop), strport, sizeof(strport),
3340                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3341                         error("connect_next: getnameinfo failed");
3342                         continue;
3343                 }
3344                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3345                     cctx->ai->ai_protocol)) == -1) {
3346                         if (cctx->ai->ai_next == NULL)
3347                                 error("socket: %.100s", strerror(errno));
3348                         else
3349                                 verbose("socket: %.100s", strerror(errno));
3350                         continue;
3351                 }
3352                 if (set_nonblock(sock) == -1)
3353                         fatal("%s: set_nonblock(%d)", __func__, sock);
3354                 if (connect(sock, cctx->ai->ai_addr,
3355                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3356                         debug("connect_next: host %.100s ([%.100s]:%s): "
3357                             "%.100s", cctx->host, ntop, strport,
3358                             strerror(errno));
3359                         saved_errno = errno;
3360                         close(sock);
3361                         errno = saved_errno;
3362                         continue;       /* fail -- try next */
3363                 }
3364                 debug("connect_next: host %.100s ([%.100s]:%s) "
3365                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3366                 cctx->ai = cctx->ai->ai_next;
3367                 set_nodelay(sock);
3368                 return sock;
3369         }
3370         return -1;
3371 }
3372
3373 static void
3374 channel_connect_ctx_free(struct channel_connect *cctx)
3375 {
3376         free(cctx->host);
3377         if (cctx->aitop)
3378                 freeaddrinfo(cctx->aitop);
3379         memset(cctx, 0, sizeof(*cctx));
3380 }
3381
3382 /* Return CONNECTING channel to remote host, port */
3383 static Channel *
3384 connect_to(const char *host, u_short port, char *ctype, char *rname)
3385 {
3386         struct addrinfo hints;
3387         int gaierr;
3388         int sock = -1;
3389         char strport[NI_MAXSERV];
3390         struct channel_connect cctx;
3391         Channel *c;
3392
3393         memset(&cctx, 0, sizeof(cctx));
3394         memset(&hints, 0, sizeof(hints));
3395         hints.ai_family = IPv4or6;
3396         hints.ai_socktype = SOCK_STREAM;
3397         snprintf(strport, sizeof strport, "%d", port);
3398         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
3399                 error("connect_to %.100s: unknown host (%s)", host,
3400                     ssh_gai_strerror(gaierr));
3401                 return NULL;
3402         }
3403
3404         cctx.host = xstrdup(host);
3405         cctx.port = port;
3406         cctx.ai = cctx.aitop;
3407
3408         if ((sock = connect_next(&cctx)) == -1) {
3409                 error("connect to %.100s port %d failed: %s",
3410                     host, port, strerror(errno));
3411                 channel_connect_ctx_free(&cctx);
3412                 return NULL;
3413         }
3414         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3415             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3416         c->connect_ctx = cctx;
3417         return c;
3418 }
3419
3420 Channel *
3421 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3422 {
3423         int i;
3424
3425         for (i = 0; i < num_permitted_opens; i++) {
3426                 if (permitted_opens[i].host_to_connect != NULL &&
3427                     port_match(permitted_opens[i].listen_port, listen_port)) {
3428                         return connect_to(
3429                             permitted_opens[i].host_to_connect,
3430                             permitted_opens[i].port_to_connect, ctype, rname);
3431                 }
3432         }
3433         error("WARNING: Server requests forwarding for unknown listen_port %d",
3434             listen_port);
3435         return NULL;
3436 }
3437
3438 /* Check if connecting to that port is permitted and connect. */
3439 Channel *
3440 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3441 {
3442         int i, permit, permit_adm = 1;
3443
3444         permit = all_opens_permitted;
3445         if (!permit) {
3446                 for (i = 0; i < num_permitted_opens; i++)
3447                         if (permitted_opens[i].host_to_connect != NULL &&
3448                             port_match(permitted_opens[i].port_to_connect, port) &&
3449                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3450                                 permit = 1;
3451         }
3452
3453         if (num_adm_permitted_opens > 0) {
3454                 permit_adm = 0;
3455                 for (i = 0; i < num_adm_permitted_opens; i++)
3456                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3457                             port_match(permitted_adm_opens[i].port_to_connect, port) &&
3458                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3459                             == 0)
3460                                 permit_adm = 1;
3461         }
3462
3463         if (!permit || !permit_adm) {
3464                 logit("Received request to connect to host %.100s port %d, "
3465                     "but the request was denied.", host, port);
3466                 return NULL;
3467         }
3468         return connect_to(host, port, ctype, rname);
3469 }
3470
3471 void
3472 channel_send_window_changes(void)
3473 {
3474         u_int i;
3475         struct winsize ws;
3476
3477         for (i = 0; i < channels_alloc; i++) {
3478                 if (channels[i] == NULL || !channels[i]->client_tty ||
3479                     channels[i]->type != SSH_CHANNEL_OPEN)
3480                         continue;
3481                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3482                         continue;
3483                 channel_request_start(i, "window-change", 0);
3484                 packet_put_int((u_int)ws.ws_col);
3485                 packet_put_int((u_int)ws.ws_row);
3486                 packet_put_int((u_int)ws.ws_xpixel);
3487                 packet_put_int((u_int)ws.ws_ypixel);
3488                 packet_send();
3489         }
3490 }
3491
3492 /* -- X11 forwarding */
3493
3494 /*
3495  * Creates an internet domain socket for listening for X11 connections.
3496  * Returns 0 and a suitable display number for the DISPLAY variable
3497  * stored in display_numberp , or -1 if an error occurs.
3498  */
3499 int
3500 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3501     int single_connection, u_int *display_numberp, int **chanids)
3502 {
3503         Channel *nc = NULL;
3504         int display_number, sock;
3505         u_short port;
3506         struct addrinfo hints, *ai, *aitop;
3507         char strport[NI_MAXSERV];
3508         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3509
3510         if (chanids == NULL)
3511                 return -1;
3512
3513         for (display_number = x11_display_offset;
3514             display_number < MAX_DISPLAYS;
3515             display_number++) {
3516                 port = 6000 + display_number;
3517                 memset(&hints, 0, sizeof(hints));
3518                 hints.ai_family = IPv4or6;
3519                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3520                 hints.ai_socktype = SOCK_STREAM;
3521                 snprintf(strport, sizeof strport, "%d", port);
3522                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3523                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3524                         return -1;
3525                 }
3526                 for (ai = aitop; ai; ai = ai->ai_next) {
3527                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3528                                 continue;
3529                         sock = socket(ai->ai_family, ai->ai_socktype,
3530                             ai->ai_protocol);
3531                         if (sock < 0) {
3532                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
3533 #ifdef EPFNOSUPPORT
3534                                     && (errno != EPFNOSUPPORT)
3535 #endif
3536                                     ) {
3537                                         error("socket: %.100s", strerror(errno));
3538                                         freeaddrinfo(aitop);
3539                                         return -1;
3540                                 } else {
3541                                         debug("x11_create_display_inet: Socket family %d not supported",
3542                                                  ai->ai_family);
3543                                         continue;
3544                                 }
3545                         }
3546                         if (ai->ai_family == AF_INET6)
3547                                 sock_set_v6only(sock);
3548                         if (x11_use_localhost)
3549                                 channel_set_reuseaddr(sock);
3550                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3551                                 debug2("bind port %d: %.100s", port, strerror(errno));
3552                                 close(sock);
3553
3554                                 for (n = 0; n < num_socks; n++) {
3555                                         close(socks[n]);
3556                                 }
3557                                 num_socks = 0;
3558                                 break;
3559                         }
3560                         socks[num_socks++] = sock;
3561                         if (num_socks == NUM_SOCKS)
3562                                 break;
3563                 }
3564                 freeaddrinfo(aitop);
3565                 if (num_socks > 0)
3566                         break;
3567         }
3568         if (display_number >= MAX_DISPLAYS) {
3569                 error("Failed to allocate internet-domain X11 display socket.");
3570                 return -1;
3571         }
3572         /* Start listening for connections on the socket. */
3573         for (n = 0; n < num_socks; n++) {
3574                 sock = socks[n];
3575                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3576                         error("listen: %.100s", strerror(errno));
3577                         close(sock);
3578                         return -1;
3579                 }
3580         }
3581
3582         /* Allocate a channel for each socket. */
3583         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3584         for (n = 0; n < num_socks; n++) {
3585                 sock = socks[n];
3586                 if (hpn_disabled)
3587                         nc = channel_new("x11 listener",
3588                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3589                             CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3590                             0, "X11 inet listener", 1);
3591                 else
3592                         nc = channel_new("x11 listener",
3593                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3594                             buffer_size, CHAN_X11_PACKET_DEFAULT,
3595                             0, "X11 inet listener", 1);
3596                 nc->single_connection = single_connection;
3597                 (*chanids)[n] = nc->self;
3598         }
3599         (*chanids)[n] = -1;
3600
3601         /* Return the display number for the DISPLAY environment variable. */
3602         *display_numberp = display_number;
3603         return (0);
3604 }
3605
3606 static int
3607 connect_local_xsocket_path(const char *pathname)
3608 {
3609         int sock;
3610         struct sockaddr_un addr;
3611
3612         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3613         if (sock < 0)
3614                 error("socket: %.100s", strerror(errno));
3615         memset(&addr, 0, sizeof(addr));
3616         addr.sun_family = AF_UNIX;
3617         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3618         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3619                 return sock;
3620         close(sock);
3621         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3622         return -1;
3623 }
3624
3625 static int
3626 connect_local_xsocket(u_int dnr)
3627 {
3628         char buf[1024];
3629         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3630         return connect_local_xsocket_path(buf);
3631 }
3632
3633 int
3634 x11_connect_display(void)
3635 {
3636         u_int display_number;
3637         const char *display;
3638         char buf[1024], *cp;
3639         struct addrinfo hints, *ai, *aitop;
3640         char strport[NI_MAXSERV];
3641         int gaierr, sock = 0;
3642
3643         /* Try to open a socket for the local X server. */
3644         display = getenv("DISPLAY");
3645         if (!display) {
3646                 error("DISPLAY not set.");
3647                 return -1;
3648         }
3649         /*
3650          * Now we decode the value of the DISPLAY variable and make a
3651          * connection to the real X server.
3652          */
3653
3654         /* Check if the display is from launchd. */
3655 #ifdef __APPLE__
3656         if (strncmp(display, "/tmp/launch", 11) == 0) {
3657                 sock = connect_local_xsocket_path(display);
3658                 if (sock < 0)
3659                         return -1;
3660
3661                 /* OK, we now have a connection to the display. */
3662                 return sock;
3663         }
3664 #endif
3665         /*
3666          * Check if it is a unix domain socket.  Unix domain displays are in
3667          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3668          */
3669         if (strncmp(display, "unix:", 5) == 0 ||
3670             display[0] == ':') {
3671                 /* Connect to the unix domain socket. */
3672                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3673                         error("Could not parse display number from DISPLAY: %.100s",
3674                             display);
3675                         return -1;
3676                 }
3677                 /* Create a socket. */
3678                 sock = connect_local_xsocket(display_number);
3679                 if (sock < 0)
3680                         return -1;
3681
3682                 /* OK, we now have a connection to the display. */
3683                 return sock;
3684         }
3685         /*
3686          * Connect to an inet socket.  The DISPLAY value is supposedly
3687          * hostname:d[.s], where hostname may also be numeric IP address.
3688          */
3689         strlcpy(buf, display, sizeof(buf));
3690         cp = strchr(buf, ':');
3691         if (!cp) {
3692                 error("Could not find ':' in DISPLAY: %.100s", display);
3693                 return -1;
3694         }
3695         *cp = 0;
3696         /* buf now contains the host name.  But first we parse the display number. */
3697         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3698                 error("Could not parse display number from DISPLAY: %.100s",
3699                     display);
3700                 return -1;
3701         }
3702
3703         /* Look up the host address */
3704         memset(&hints, 0, sizeof(hints));
3705         hints.ai_family = IPv4or6;
3706         hints.ai_socktype = SOCK_STREAM;
3707         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3708         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3709                 error("%.100s: unknown host. (%s)", buf,
3710                 ssh_gai_strerror(gaierr));
3711                 return -1;
3712         }
3713         for (ai = aitop; ai; ai = ai->ai_next) {
3714                 /* Create a socket. */
3715                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3716                 if (sock < 0) {
3717                         debug2("socket: %.100s", strerror(errno));
3718                         continue;
3719                 }
3720                 /* Connect it to the display. */
3721                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3722                         debug2("connect %.100s port %u: %.100s", buf,
3723                             6000 + display_number, strerror(errno));
3724                         close(sock);
3725                         continue;
3726                 }
3727                 /* Success */
3728                 break;
3729         }
3730         freeaddrinfo(aitop);
3731         if (!ai) {
3732                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3733                     strerror(errno));
3734                 return -1;
3735         }
3736         set_nodelay(sock);
3737         return sock;
3738 }
3739
3740 /*
3741  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3742  * the remote channel number.  We should do whatever we want, and respond
3743  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3744  */
3745
3746 /* ARGSUSED */
3747 void
3748 x11_input_open(int type, u_int32_t seq, void *ctxt)
3749 {
3750         Channel *c = NULL;
3751         int remote_id, sock = 0;
3752         char *remote_host;
3753
3754         debug("Received X11 open request.");
3755
3756         remote_id = packet_get_int();
3757
3758         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3759                 remote_host = packet_get_string(NULL);
3760         } else {
3761                 remote_host = xstrdup("unknown (remote did not supply name)");
3762         }
3763         packet_check_eom();
3764
3765         /* Obtain a connection to the real X display. */
3766         sock = x11_connect_display();
3767         if (sock != -1) {
3768                 /* Allocate a channel for this connection. */
3769                 c = channel_new("connected x11 socket",
3770                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3771                     remote_host, 1);
3772                 c->remote_id = remote_id;
3773                 c->force_drain = 1;
3774         }
3775         free(remote_host);
3776         if (c == NULL) {
3777                 /* Send refusal to the remote host. */
3778                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3779                 packet_put_int(remote_id);
3780         } else {
3781                 /* Send a confirmation to the remote host. */
3782                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3783                 packet_put_int(remote_id);
3784                 packet_put_int(c->self);
3785         }
3786         packet_send();
3787 }
3788
3789 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3790 /* ARGSUSED */
3791 void
3792 deny_input_open(int type, u_int32_t seq, void *ctxt)
3793 {
3794         int rchan = packet_get_int();
3795
3796         switch (type) {
3797         case SSH_SMSG_AGENT_OPEN:
3798                 error("Warning: ssh server tried agent forwarding.");
3799                 break;
3800         case SSH_SMSG_X11_OPEN:
3801                 error("Warning: ssh server tried X11 forwarding.");
3802                 break;
3803         default:
3804                 error("deny_input_open: type %d", type);
3805                 break;
3806         }
3807         error("Warning: this is probably a break-in attempt by a malicious server.");
3808         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3809         packet_put_int(rchan);
3810         packet_send();
3811 }
3812
3813 /*
3814  * Requests forwarding of X11 connections, generates fake authentication
3815  * data, and enables authentication spoofing.
3816  * This should be called in the client only.
3817  */
3818 void
3819 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3820     const char *proto, const char *data, int want_reply)
3821 {
3822         u_int data_len = (u_int) strlen(data) / 2;
3823         u_int i, value;
3824         char *new_data;
3825         int screen_number;
3826         const char *cp;
3827         u_int32_t rnd = 0;
3828
3829         if (x11_saved_display == NULL)
3830                 x11_saved_display = xstrdup(disp);
3831         else if (strcmp(disp, x11_saved_display) != 0) {
3832                 error("x11_request_forwarding_with_spoofing: different "
3833                     "$DISPLAY already forwarded");
3834                 return;
3835         }
3836
3837         cp = strchr(disp, ':');
3838         if (cp)
3839                 cp = strchr(cp, '.');
3840         if (cp)
3841                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3842         else
3843                 screen_number = 0;
3844
3845         if (x11_saved_proto == NULL) {
3846                 /* Save protocol name. */
3847                 x11_saved_proto = xstrdup(proto);
3848                 /*
3849                  * Extract real authentication data and generate fake data
3850                  * of the same length.
3851                  */
3852                 x11_saved_data = xmalloc(data_len);
3853                 x11_fake_data = xmalloc(data_len);
3854                 for (i = 0; i < data_len; i++) {
3855                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3856                                 fatal("x11_request_forwarding: bad "
3857                                     "authentication data: %.100s", data);
3858                         if (i % 4 == 0)
3859                                 rnd = arc4random();
3860                         x11_saved_data[i] = value;
3861                         x11_fake_data[i] = rnd & 0xff;
3862                         rnd >>= 8;
3863                 }
3864                 x11_saved_data_len = data_len;
3865                 x11_fake_data_len = data_len;
3866         }
3867
3868         /* Convert the fake data into hex. */
3869         new_data = tohex(x11_fake_data, data_len);
3870
3871         /* Send the request packet. */
3872         if (compat20) {
3873                 channel_request_start(client_session_id, "x11-req", want_reply);
3874                 packet_put_char(0);     /* XXX bool single connection */
3875         } else {
3876                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3877         }
3878         packet_put_cstring(proto);
3879         packet_put_cstring(new_data);
3880         packet_put_int(screen_number);
3881         packet_send();
3882         packet_write_wait();
3883         free(new_data);
3884 }
3885
3886
3887 /* -- agent forwarding */
3888
3889 /* Sends a message to the server to request authentication fd forwarding. */
3890
3891 void
3892 auth_request_forwarding(void)
3893 {
3894         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3895         packet_send();
3896         packet_write_wait();
3897 }