openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.272 2008/01/19 23:02:40 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <netdb.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <termios.h>
  61 #include <unistd.h>
  62 #include <stdarg.h>
  63
  64 #include "xmalloc.h"
  65 #include "ssh.h"
  66 #include "ssh1.h"
  67 #include "ssh2.h"
  68 #include "packet.h"
  69 #include "log.h"
  70 #include "misc.h"
  71 #include "buffer.h"
  72 #include "channels.h"
  73 #include "compat.h"
  74 #include "canohost.h"
  75 #include "key.h"
  76 #include "authfd.h"
  77 #include "pathnames.h"
  78
  79 /* -- channel core */
  80
  81 /*
  82  * Pointer to an array containing all allocated channels.  The array is
  83  * dynamically extended as needed.
  84  */
  85 static Channel **channels = NULL;
  86
  87 /*
  88  * Size of the channel array.  All slots of the array must always be
  89  * initialized (at least the type field); unused slots set to NULL
  90  */
  91 static u_int channels_alloc = 0;
  92
  93 /*
  94  * Maximum file descriptor value used in any of the channels.  This is
  95  * updated in channel_new.
  96  */
  97 static int channel_max_fd = 0;
  98
  99
 100 /* -- tcp forwarding */
 101
 102 /*
 103  * Data structure for storing which hosts are permitted for forward requests.
 104  * The local sides of any remote forwards are stored in this array to prevent
 105  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 106  * network (which might be behind a firewall).
 107  */
 108 typedef struct {
 109         char *host_to_connect;          /* Connect to 'host'. */
 110         u_short port_to_connect;        /* Connect to 'port'. */
 111         u_short listen_port;            /* Remote side should listen port number. */
 112 } ForwardPermission;
 113
 114 /* List of all permitted host/port pairs to connect by the user. */
 115 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 116
 117 /* List of all permitted host/port pairs to connect by the admin. */
 118 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 119
 120 /* Number of permitted host/port pairs in the array permitted by the user. */
 121 static int num_permitted_opens = 0;
 122
 123 /* Number of permitted host/port pair in the array permitted by the admin. */
 124 static int num_adm_permitted_opens = 0;
 125
 126 /*
 127  * If this is true, all opens are permitted.  This is the case on the server
 128  * on which we have to trust the client anyway, and the user could do
 129  * anything after logging in anyway.
 130  */
 131 static int all_opens_permitted = 0;
 132
 133
 134 /* -- X11 forwarding */
 135
 136 /* Maximum number of fake X11 displays to try. */
 137 #define MAX_DISPLAYS  1000
 138
 139 /* Saved X11 local (client) display. */
 140 static char *x11_saved_display = NULL;
 141
 142 /* Saved X11 authentication protocol name. */
 143 static char *x11_saved_proto = NULL;
 144
 145 /* Saved X11 authentication data.  This is the real data. */
 146 static char *x11_saved_data = NULL;
 147 static u_int x11_saved_data_len = 0;
 148
 149 /*
 150  * Fake X11 authentication data.  This is what the server will be sending us;
 151  * we should replace any occurrences of this by the real data.
 152  */
 153 static u_char *x11_fake_data = NULL;
 154 static u_int x11_fake_data_len;
 155
 156
 157 /* -- agent forwarding */
 158
 159 #define NUM_SOCKS       10
 160
 161 /* AF_UNSPEC or AF_INET or AF_INET6 */
 162 static int IPv4or6 = AF_UNSPEC;
 163
 164 /* helper */
 165 static void port_open_helper(Channel *c, char *rtype);
 166
 167 /* -- channel core */
 168
 169 Channel *
 170 channel_by_id(int id)
 171 {
 172         Channel *c;
 173
 174         if (id < 0 || (u_int)id >= channels_alloc) {
 175                 logit("channel_by_id: %d: bad id", id);
 176                 return NULL;
 177         }
 178         c = channels[id];
 179         if (c == NULL) {
 180                 logit("channel_by_id: %d: bad id: channel free", id);
 181                 return NULL;
 182         }
 183         return c;
 184 }
 185
 186 /*
 187  * Returns the channel if it is allowed to receive protocol messages.
 188  * Private channels, like listening sockets, may not receive messages.
 189  */
 190 Channel *
 191 channel_lookup(int id)
 192 {
 193         Channel *c;
 194
 195         if ((c = channel_by_id(id)) == NULL)
 196                 return (NULL);
 197
 198         switch (c->type) {
 199         case SSH_CHANNEL_X11_OPEN:
 200         case SSH_CHANNEL_LARVAL:
 201         case SSH_CHANNEL_CONNECTING:
 202         case SSH_CHANNEL_DYNAMIC:
 203         case SSH_CHANNEL_OPENING:
 204         case SSH_CHANNEL_OPEN:
 205         case SSH_CHANNEL_INPUT_DRAINING:
 206         case SSH_CHANNEL_OUTPUT_DRAINING:
 207                 return (c);
 208         }
 209         logit("Non-public channel %d, type %d.", id, c->type);
 210         return (NULL);
 211 }
 212
 213 /*
 214  * Register filedescriptors for a channel, used when allocating a channel or
 215  * when the channel consumer/producer is ready, e.g. shell exec'd
 216  */
 217 static void
 218 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 219     int extusage, int nonblock)
 220 {
 221         /* Update the maximum file descriptor value. */
 222         channel_max_fd = MAX(channel_max_fd, rfd);
 223         channel_max_fd = MAX(channel_max_fd, wfd);
 224         channel_max_fd = MAX(channel_max_fd, efd);
 225
 226         /* XXX set close-on-exec -markus */
 227
 228         c->rfd = rfd;
 229         c->wfd = wfd;
 230         c->sock = (rfd == wfd) ? rfd : -1;
 231         c->ctl_fd = -1; /* XXX: set elsewhere */
 232         c->efd = efd;
 233         c->extended_usage = extusage;
 234
 235         /* XXX ugly hack: nonblock is only set by the server */
 236         if (nonblock && isatty(c->rfd)) {
 237                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 238                 c->isatty = 1;
 239                 if (!isatty(c->wfd)) {
 240                         error("channel %d: wfd %d is not a tty?",
 241                             c->self, c->wfd);
 242                 }
 243         } else {
 244                 c->isatty = 0;
 245         }
 246         c->wfd_isatty = isatty(c->wfd);
 247
 248         /* enable nonblocking mode */
 249         if (nonblock) {
 250                 if (rfd != -1)
 251                         set_nonblock(rfd);
 252                 if (wfd != -1)
 253                         set_nonblock(wfd);
 254                 if (efd != -1)
 255                         set_nonblock(efd);
 256         }
 257 }
 258
 259 /*
 260  * Allocate a new channel object and set its type and socket. This will cause
 261  * remote_name to be freed.
 262  */
 263 Channel *
 264 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 265     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 266 {
 267         int found;
 268         u_int i;
 269         Channel *c;
 270
 271         /* Do initial allocation if this is the first call. */
 272         if (channels_alloc == 0) {
 273                 channels_alloc = 10;
 274                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 275                 for (i = 0; i < channels_alloc; i++)
 276                         channels[i] = NULL;
 277         }
 278         /* Try to find a free slot where to put the new channel. */
 279         for (found = -1, i = 0; i < channels_alloc; i++)
 280                 if (channels[i] == NULL) {
 281                         /* Found a free slot. */
 282                         found = (int)i;
 283                         break;
 284                 }
 285         if (found < 0) {
 286                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 287                 found = channels_alloc;
 288                 if (channels_alloc > 10000)
 289                         fatal("channel_new: internal error: channels_alloc %d "
 290                             "too big.", channels_alloc);
 291                 channels = xrealloc(channels, channels_alloc + 10,
 292                     sizeof(Channel *));
 293                 channels_alloc += 10;
 294                 debug2("channel: expanding %d", channels_alloc);
 295                 for (i = found; i < channels_alloc; i++)
 296                         channels[i] = NULL;
 297         }
 298         /* Initialize and return new channel. */
 299         c = channels[found] = xcalloc(1, sizeof(Channel));
 300         buffer_init(&c->input);
 301         buffer_init(&c->output);
 302         buffer_init(&c->extended);
 303         c->ostate = CHAN_OUTPUT_OPEN;
 304         c->istate = CHAN_INPUT_OPEN;
 305         c->flags = 0;
 306         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 307         c->self = found;
 308         c->type = type;
 309         c->ctype = ctype;
 310         c->local_window = window;
 311         c->local_window_max = window;
 312         c->local_consumed = 0;
 313         c->local_maxpacket = maxpack;
 314         c->dynamic_window = 0;
 315         c->remote_id = -1;
 316         c->remote_name = xstrdup(remote_name);
 317         c->remote_window = 0;
 318         c->remote_maxpacket = 0;
 319         c->force_drain = 0;
 320         c->single_connection = 0;
 321         c->detach_user = NULL;
 322         c->detach_close = 0;
 323         c->confirm = NULL;
 324         c->confirm_ctx = NULL;
 325         c->input_filter = NULL;
 326         c->output_filter = NULL;
 327         debug("channel %d: new [%s]", found, remote_name);
 328         return c;
 329 }
 330
 331 static int
 332 channel_find_maxfd(void)
 333 {
 334         u_int i;
 335         int max = 0;
 336         Channel *c;
 337
 338         for (i = 0; i < channels_alloc; i++) {
 339                 c = channels[i];
 340                 if (c != NULL) {
 341                         max = MAX(max, c->rfd);
 342                         max = MAX(max, c->wfd);
 343                         max = MAX(max, c->efd);
 344                 }
 345         }
 346         return max;
 347 }
 348
 349 int
 350 channel_close_fd(int *fdp)
 351 {
 352         int ret = 0, fd = *fdp;
 353
 354         if (fd != -1) {
 355                 ret = close(fd);
 356                 *fdp = -1;
 357                 if (fd == channel_max_fd)
 358                         channel_max_fd = channel_find_maxfd();
 359         }
 360         return ret;
 361 }
 362
 363 /* Close all channel fd/socket. */
 364 static void
 365 channel_close_fds(Channel *c)
 366 {
 367         debug3("channel %d: close_fds r %d w %d e %d c %d",
 368             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 369
 370         channel_close_fd(&c->sock);
 371         channel_close_fd(&c->ctl_fd);
 372         channel_close_fd(&c->rfd);
 373         channel_close_fd(&c->wfd);
 374         channel_close_fd(&c->efd);
 375 }
 376
 377 /* Free the channel and close its fd/socket. */
 378 void
 379 channel_free(Channel *c)
 380 {
 381         char *s;
 382         u_int i, n;
 383
 384         for (n = 0, i = 0; i < channels_alloc; i++)
 385                 if (channels[i])
 386                         n++;
 387         debug("channel %d: free: %s, nchannels %u", c->self,
 388             c->remote_name ? c->remote_name : "???", n);
 389
 390         s = channel_open_message();
 391         debug3("channel %d: status: %s", c->self, s);
 392         xfree(s);
 393
 394         if (c->sock != -1)
 395                 shutdown(c->sock, SHUT_RDWR);
 396         if (c->ctl_fd != -1)
 397                 shutdown(c->ctl_fd, SHUT_RDWR);
 398         channel_close_fds(c);
 399         buffer_free(&c->input);
 400         buffer_free(&c->output);
 401         buffer_free(&c->extended);
 402         if (c->remote_name) {
 403                 xfree(c->remote_name);
 404                 c->remote_name = NULL;
 405         }
 406         channels[c->self] = NULL;
 407         xfree(c);
 408 }
 409
 410 void
 411 channel_free_all(void)
 412 {
 413         u_int i;
 414
 415         for (i = 0; i < channels_alloc; i++)
 416                 if (channels[i] != NULL)
 417                         channel_free(channels[i]);
 418 }
 419
 420 /*
 421  * Closes the sockets/fds of all channels.  This is used to close extra file
 422  * descriptors after a fork.
 423  */
 424 void
 425 channel_close_all(void)
 426 {
 427         u_int i;
 428
 429         for (i = 0; i < channels_alloc; i++)
 430                 if (channels[i] != NULL)
 431                         channel_close_fds(channels[i]);
 432 }
 433
 434 /*
 435  * Stop listening to channels.
 436  */
 437 void
 438 channel_stop_listening(void)
 439 {
 440         u_int i;
 441         Channel *c;
 442
 443         for (i = 0; i < channels_alloc; i++) {
 444                 c = channels[i];
 445                 if (c != NULL) {
 446                         switch (c->type) {
 447                         case SSH_CHANNEL_AUTH_SOCKET:
 448                         case SSH_CHANNEL_PORT_LISTENER:
 449                         case SSH_CHANNEL_RPORT_LISTENER:
 450                         case SSH_CHANNEL_X11_LISTENER:
 451                                 channel_close_fd(&c->sock);
 452                                 channel_free(c);
 453                                 break;
 454                         }
 455                 }
 456         }
 457 }
 458
 459 /*
 460  * Returns true if no channel has too much buffered data, and false if one or
 461  * more channel is overfull.
 462  */
 463 int
 464 channel_not_very_much_buffered_data(void)
 465 {
 466         u_int i;
 467         Channel *c;
 468
 469         for (i = 0; i < channels_alloc; i++) {
 470                 c = channels[i];
 471                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 472 #if 0
 473                         if (!compat20 &&
 474                             buffer_len(&c->input) > packet_get_maxsize()) {
 475                                 debug2("channel %d: big input buffer %d",
 476                                     c->self, buffer_len(&c->input));
 477                                 return 0;
 478                         }
 479 #endif
 480                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 481                                 debug2("channel %d: big output buffer %u > %u",
 482                                     c->self, buffer_len(&c->output),
 483                                     packet_get_maxsize());
 484                                 return 0;
 485                         }
 486                 }
 487         }
 488         return 1;
 489 }
 490
 491 /* Returns true if any channel is still open. */
 492 int
 493 channel_still_open(void)
 494 {
 495         u_int i;
 496         Channel *c;
 497
 498         for (i = 0; i < channels_alloc; i++) {
 499                 c = channels[i];
 500                 if (c == NULL)
 501                         continue;
 502                 switch (c->type) {
 503                 case SSH_CHANNEL_X11_LISTENER:
 504                 case SSH_CHANNEL_PORT_LISTENER:
 505                 case SSH_CHANNEL_RPORT_LISTENER:
 506                 case SSH_CHANNEL_CLOSED:
 507                 case SSH_CHANNEL_AUTH_SOCKET:
 508                 case SSH_CHANNEL_DYNAMIC:
 509                 case SSH_CHANNEL_CONNECTING:
 510                 case SSH_CHANNEL_ZOMBIE:
 511                         continue;
 512                 case SSH_CHANNEL_LARVAL:
 513                         if (!compat20)
 514                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 515                         continue;
 516                 case SSH_CHANNEL_OPENING:
 517                 case SSH_CHANNEL_OPEN:
 518                 case SSH_CHANNEL_X11_OPEN:
 519                         return 1;
 520                 case SSH_CHANNEL_INPUT_DRAINING:
 521                 case SSH_CHANNEL_OUTPUT_DRAINING:
 522                         if (!compat13)
 523                                 fatal("cannot happen: OUT_DRAIN");
 524                         return 1;
 525                 default:
 526                         fatal("channel_still_open: bad channel type %d", c->type);
 527                         /* NOTREACHED */
 528                 }
 529         }
 530         return 0;
 531 }
 532
 533 /* Returns the id of an open channel suitable for keepaliving */
 534 int
 535 channel_find_open(void)
 536 {
 537         u_int i;
 538         Channel *c;
 539
 540         for (i = 0; i < channels_alloc; i++) {
 541                 c = channels[i];
 542                 if (c == NULL || c->remote_id < 0)
 543                         continue;
 544                 switch (c->type) {
 545                 case SSH_CHANNEL_CLOSED:
 546                 case SSH_CHANNEL_DYNAMIC:
 547                 case SSH_CHANNEL_X11_LISTENER:
 548                 case SSH_CHANNEL_PORT_LISTENER:
 549                 case SSH_CHANNEL_RPORT_LISTENER:
 550                 case SSH_CHANNEL_OPENING:
 551                 case SSH_CHANNEL_CONNECTING:
 552                 case SSH_CHANNEL_ZOMBIE:
 553                         continue;
 554                 case SSH_CHANNEL_LARVAL:
 555                 case SSH_CHANNEL_AUTH_SOCKET:
 556                 case SSH_CHANNEL_OPEN:
 557                 case SSH_CHANNEL_X11_OPEN:
 558                         return i;
 559                 case SSH_CHANNEL_INPUT_DRAINING:
 560                 case SSH_CHANNEL_OUTPUT_DRAINING:
 561                         if (!compat13)
 562                                 fatal("cannot happen: OUT_DRAIN");
 563                         return i;
 564                 default:
 565                         fatal("channel_find_open: bad channel type %d", c->type);
 566                         /* NOTREACHED */
 567                 }
 568         }
 569         return -1;
 570 }
 571
 572
 573 /*
 574  * Returns a message describing the currently open forwarded connections,
 575  * suitable for sending to the client.  The message contains crlf pairs for
 576  * newlines.
 577  */
 578 char *
 579 channel_open_message(void)
 580 {
 581         Buffer buffer;
 582         Channel *c;
 583         char buf[1024], *cp;
 584         u_int i;
 585
 586         buffer_init(&buffer);
 587         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 588         buffer_append(&buffer, buf, strlen(buf));
 589         for (i = 0; i < channels_alloc; i++) {
 590                 c = channels[i];
 591                 if (c == NULL)
 592                         continue;
 593                 switch (c->type) {
 594                 case SSH_CHANNEL_X11_LISTENER:
 595                 case SSH_CHANNEL_PORT_LISTENER:
 596                 case SSH_CHANNEL_RPORT_LISTENER:
 597                 case SSH_CHANNEL_CLOSED:
 598                 case SSH_CHANNEL_AUTH_SOCKET:
 599                 case SSH_CHANNEL_ZOMBIE:
 600                         continue;
 601                 case SSH_CHANNEL_LARVAL:
 602                 case SSH_CHANNEL_OPENING:
 603                 case SSH_CHANNEL_CONNECTING:
 604                 case SSH_CHANNEL_DYNAMIC:
 605                 case SSH_CHANNEL_OPEN:
 606                 case SSH_CHANNEL_X11_OPEN:
 607                 case SSH_CHANNEL_INPUT_DRAINING:
 608                 case SSH_CHANNEL_OUTPUT_DRAINING:
 609                         snprintf(buf, sizeof buf,
 610                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 611                             c->self, c->remote_name,
 612                             c->type, c->remote_id,
 613                             c->istate, buffer_len(&c->input),
 614                             c->ostate, buffer_len(&c->output),
 615                             c->rfd, c->wfd, c->ctl_fd);
 616                         buffer_append(&buffer, buf, strlen(buf));
 617                         continue;
 618                 default:
 619                         fatal("channel_open_message: bad channel type %d", c->type);
 620                         /* NOTREACHED */
 621                 }
 622         }
 623         buffer_append(&buffer, "\0", 1);
 624         cp = xstrdup(buffer_ptr(&buffer));
 625         buffer_free(&buffer);
 626         return cp;
 627 }
 628
 629 void
 630 channel_send_open(int id)
 631 {
 632         Channel *c = channel_lookup(id);
 633
 634         if (c == NULL) {
 635                 logit("channel_send_open: %d: bad id", id);
 636                 return;
 637         }
 638         debug2("channel %d: send open", id);
 639         packet_start(SSH2_MSG_CHANNEL_OPEN);
 640         packet_put_cstring(c->ctype);
 641         packet_put_int(c->self);
 642         packet_put_int(c->local_window);
 643         packet_put_int(c->local_maxpacket);
 644         packet_send();
 645 }
 646
 647 void
 648 channel_request_start(int id, char *service, int wantconfirm)
 649 {
 650         Channel *c = channel_lookup(id);
 651
 652         if (c == NULL) {
 653                 logit("channel_request_start: %d: unknown channel id", id);
 654                 return;
 655         }
 656         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 657         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 658         packet_put_int(c->remote_id);
 659         packet_put_cstring(service);
 660         packet_put_char(wantconfirm);
 661 }
 662
 663 void
 664 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 665 {
 666         Channel *c = channel_lookup(id);
 667
 668         if (c == NULL) {
 669                 logit("channel_register_comfirm: %d: bad id", id);
 670                 return;
 671         }
 672         c->confirm = fn;
 673         c->confirm_ctx = ctx;
 674 }
 675
 676 void
 677 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 678 {
 679         Channel *c = channel_by_id(id);
 680
 681         if (c == NULL) {
 682                 logit("channel_register_cleanup: %d: bad id", id);
 683                 return;
 684         }
 685         c->detach_user = fn;
 686         c->detach_close = do_close;
 687 }
 688
 689 void
 690 channel_cancel_cleanup(int id)
 691 {
 692         Channel *c = channel_by_id(id);
 693
 694         if (c == NULL) {
 695                 logit("channel_cancel_cleanup: %d: bad id", id);
 696                 return;
 697         }
 698         c->detach_user = NULL;
 699         c->detach_close = 0;
 700 }
 701
 702 void
 703 channel_register_filter(int id, channel_infilter_fn *ifn,
 704     channel_outfilter_fn *ofn)
 705 {
 706         Channel *c = channel_lookup(id);
 707
 708         if (c == NULL) {
 709                 logit("channel_register_filter: %d: bad id", id);
 710                 return;
 711         }
 712         c->input_filter = ifn;
 713         c->output_filter = ofn;
 714 }
 715
 716 void
 717 channel_set_fds(int id, int rfd, int wfd, int efd,
 718     int extusage, int nonblock, u_int window_max)
 719 {
 720         Channel *c = channel_lookup(id);
 721
 722         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 723                 fatal("channel_activate for non-larval channel %d.", id);
 724         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 725         c->type = SSH_CHANNEL_OPEN;
 726         c->local_window = c->local_window_max = window_max;
 727         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 728         packet_put_int(c->remote_id);
 729         packet_put_int(c->local_window);
 730         packet_send();
 731 }
 732
 733 /*
 734  * 'channel_pre*' are called just before select() to add any bits relevant to
 735  * channels in the select bitmasks.
 736  */
 737 /*
 738  * 'channel_post*': perform any appropriate operations for channels which
 739  * have events pending.
 740  */
 741 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 742 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 743 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 744
 745 /* ARGSUSED */
 746 static void
 747 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 748 {
 749         FD_SET(c->sock, readset);
 750 }
 751
 752 /* ARGSUSED */
 753 static void
 754 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 755 {
 756         debug3("channel %d: waiting for connection", c->self);
 757         FD_SET(c->sock, writeset);
 758 }
 759
 760 static void
 761 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 762 {
 763         if (buffer_len(&c->input) < packet_get_maxsize())
 764                 FD_SET(c->sock, readset);
 765         if (buffer_len(&c->output) > 0)
 766                 FD_SET(c->sock, writeset);
 767 }
 768
 769 int channel_tcpwinsz () {
 770         u_int32_t tcpwinsz = 0;
 771         socklen_t optsz = sizeof(tcpwinsz);
 772         int ret = -1;
 773
 774         /* if we aren't on a socket return 128KB*/
 775         if(!packet_connection_is_on_socket())
 776             return(128*1024);
 777         ret = getsockopt(packet_get_connection_in(),
 778                          SOL_SOCKET, SO_RCVBUF, &tcpwinsz, &optsz);
 779         /* return no more than 64MB */
 780         if ((ret == 0) && tcpwinsz > BUFFER_MAX_LEN_HPN)
 781             tcpwinsz = BUFFER_MAX_LEN_HPN;
 782         debug2("tcpwinsz: %d for connection: %d", tcpwinsz,
 783                packet_get_connection_in());
 784         return(tcpwinsz);
 785 }
 786
 787 static void
 788 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 789 {
 790         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 791
 792         /* check buffer limits */
 793         if ((!c->tcpwinsz) || (c->dynamic_window > 0))
 794             c->tcpwinsz = channel_tcpwinsz();
 795
 796         limit = MIN(limit, 2 * c->tcpwinsz);
 797
 798         if (c->istate == CHAN_INPUT_OPEN &&
 799             limit > 0 &&
 800             buffer_len(&c->input) < limit &&
 801             buffer_check_alloc(&c->input, CHAN_RBUF))
 802                 FD_SET(c->rfd, readset);
 803         if (c->ostate == CHAN_OUTPUT_OPEN ||
 804             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 805                 if (buffer_len(&c->output) > 0) {
 806                         FD_SET(c->wfd, writeset);
 807                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 808                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 809                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 810                                     c->self, c->efd, buffer_len(&c->extended));
 811                         else
 812                                 chan_obuf_empty(c);
 813                 }
 814         }
 815         /** XXX check close conditions, too */
 816         if (compat20 && c->efd != -1) {
 817                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 818                     buffer_len(&c->extended) > 0)
 819                         FD_SET(c->efd, writeset);
 820                 else if (!(c->flags & CHAN_EOF_SENT) &&
 821                     c->extended_usage == CHAN_EXTENDED_READ &&
 822                     buffer_len(&c->extended) < c->remote_window)
 823                         FD_SET(c->efd, readset);
 824         }
 825         /* XXX: What about efd? races? */
 826         if (compat20 && c->ctl_fd != -1 &&
 827             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 828                 FD_SET(c->ctl_fd, readset);
 829 }
 830
 831 /* ARGSUSED */
 832 static void
 833 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 834 {
 835         if (buffer_len(&c->input) == 0) {
 836                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 837                 packet_put_int(c->remote_id);
 838                 packet_send();
 839                 c->type = SSH_CHANNEL_CLOSED;
 840                 debug2("channel %d: closing after input drain.", c->self);
 841         }
 842 }
 843
 844 /* ARGSUSED */
 845 static void
 846 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 847 {
 848         if (buffer_len(&c->output) == 0)
 849                 chan_mark_dead(c);
 850         else
 851                 FD_SET(c->sock, writeset);
 852 }
 853
 854 /*
 855  * This is a special state for X11 authentication spoofing.  An opened X11
 856  * connection (when authentication spoofing is being done) remains in this
 857  * state until the first packet has been completely read.  The authentication
 858  * data in that packet is then substituted by the real data if it matches the
 859  * fake data, and the channel is put into normal mode.
 860  * XXX All this happens at the client side.
 861  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 862  */
 863 static int
 864 x11_open_helper(Buffer *b)
 865 {
 866         u_char *ucp;
 867         u_int proto_len, data_len;
 868
 869         /* Check if the fixed size part of the packet is in buffer. */
 870         if (buffer_len(b) < 12)
 871                 return 0;
 872
 873         /* Parse the lengths of variable-length fields. */
 874         ucp = buffer_ptr(b);
 875         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 876                 proto_len = 256 * ucp[6] + ucp[7];
 877                 data_len = 256 * ucp[8] + ucp[9];
 878         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 879                 proto_len = ucp[6] + 256 * ucp[7];
 880                 data_len = ucp[8] + 256 * ucp[9];
 881         } else {
 882                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 883                     ucp[0]);
 884                 return -1;
 885         }
 886
 887         /* Check if the whole packet is in buffer. */
 888         if (buffer_len(b) <
 889             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 890                 return 0;
 891
 892         /* Check if authentication protocol matches. */
 893         if (proto_len != strlen(x11_saved_proto) ||
 894             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 895                 debug2("X11 connection uses different authentication protocol.");
 896                 return -1;
 897         }
 898         /* Check if authentication data matches our fake data. */
 899         if (data_len != x11_fake_data_len ||
 900             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 901                 x11_fake_data, x11_fake_data_len) != 0) {
 902                 debug2("X11 auth data does not match fake data.");
 903                 return -1;
 904         }
 905         /* Check fake data length */
 906         if (x11_fake_data_len != x11_saved_data_len) {
 907                 error("X11 fake_data_len %d != saved_data_len %d",
 908                     x11_fake_data_len, x11_saved_data_len);
 909                 return -1;
 910         }
 911         /*
 912          * Received authentication protocol and data match
 913          * our fake data. Substitute the fake data with real
 914          * data.
 915          */
 916         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 917             x11_saved_data, x11_saved_data_len);
 918         return 1;
 919 }
 920
 921 static void
 922 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 923 {
 924         int ret = x11_open_helper(&c->output);
 925
 926         if (ret == 1) {
 927                 /* Start normal processing for the channel. */
 928                 c->type = SSH_CHANNEL_OPEN;
 929                 channel_pre_open_13(c, readset, writeset);
 930         } else if (ret == -1) {
 931                 /*
 932                  * We have received an X11 connection that has bad
 933                  * authentication information.
 934                  */
 935                 logit("X11 connection rejected because of wrong authentication.");
 936                 buffer_clear(&c->input);
 937                 buffer_clear(&c->output);
 938                 channel_close_fd(&c->sock);
 939                 c->sock = -1;
 940                 c->type = SSH_CHANNEL_CLOSED;
 941                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 942                 packet_put_int(c->remote_id);
 943                 packet_send();
 944         }
 945 }
 946
 947 static void
 948 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 949 {
 950         int ret = x11_open_helper(&c->output);
 951
 952         /* c->force_drain = 1; */
 953
 954         if (ret == 1) {
 955                 c->type = SSH_CHANNEL_OPEN;
 956                 channel_pre_open(c, readset, writeset);
 957         } else if (ret == -1) {
 958                 logit("X11 connection rejected because of wrong authentication.");
 959                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 960                 chan_read_failed(c);
 961                 buffer_clear(&c->input);
 962                 chan_ibuf_empty(c);
 963                 buffer_clear(&c->output);
 964                 /* for proto v1, the peer will send an IEOF */
 965                 if (compat20)
 966                         chan_write_failed(c);
 967                 else
 968                         c->type = SSH_CHANNEL_OPEN;
 969                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 970         }
 971 }
 972
 973 /* try to decode a socks4 header */
 974 /* ARGSUSED */
 975 static int
 976 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 977 {
 978         char *p, *host;
 979         u_int len, have, i, found;
 980         char username[256];
 981         struct {
 982                 u_int8_t version;
 983                 u_int8_t command;
 984                 u_int16_t dest_port;
 985                 struct in_addr dest_addr;
 986         } s4_req, s4_rsp;
 987
 988         debug2("channel %d: decode socks4", c->self);
 989
 990         have = buffer_len(&c->input);
 991         len = sizeof(s4_req);
 992         if (have < len)
 993                 return 0;
 994         p = buffer_ptr(&c->input);
 995         for (found = 0, i = len; i < have; i++) {
 996                 if (p[i] == '\0') {
 997                         found = 1;
 998                         break;
 999                 }
1000                 if (i > 1024) {
1001                         /* the peer is probably sending garbage */
1002                         debug("channel %d: decode socks4: too long",
1003                             c->self);
1004                         return -1;
1005                 }
1006         }
1007         if (!found)
1008                 return 0;
1009         buffer_get(&c->input, (char *)&s4_req.version, 1);
1010         buffer_get(&c->input, (char *)&s4_req.command, 1);
1011         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1012         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1013         have = buffer_len(&c->input);
1014         p = buffer_ptr(&c->input);
1015         len = strlen(p);
1016         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1017         if (len > have)
1018                 fatal("channel %d: decode socks4: len %d > have %d",
1019                     c->self, len, have);
1020         strlcpy(username, p, sizeof(username));
1021         buffer_consume(&c->input, len);
1022         buffer_consume(&c->input, 1);           /* trailing '\0' */
1023
1024         host = inet_ntoa(s4_req.dest_addr);
1025         strlcpy(c->path, host, sizeof(c->path));
1026         c->host_port = ntohs(s4_req.dest_port);
1027
1028         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1029             c->self, host, c->host_port, s4_req.command);
1030
1031         if (s4_req.command != 1) {
1032                 debug("channel %d: cannot handle: socks4 cn %d",
1033                     c->self, s4_req.command);
1034                 return -1;
1035         }
1036         s4_rsp.version = 0;                     /* vn: 0 for reply */
1037         s4_rsp.command = 90;                    /* cd: req granted */
1038         s4_rsp.dest_port = 0;                   /* ignored */
1039         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1040         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1041         return 1;
1042 }
1043
1044 /* try to decode a socks5 header */
1045 #define SSH_SOCKS5_AUTHDONE     0x1000
1046 #define SSH_SOCKS5_NOAUTH       0x00
1047 #define SSH_SOCKS5_IPV4         0x01
1048 #define SSH_SOCKS5_DOMAIN       0x03
1049 #define SSH_SOCKS5_IPV6         0x04
1050 #define SSH_SOCKS5_CONNECT      0x01
1051 #define SSH_SOCKS5_SUCCESS      0x00
1052
1053 /* ARGSUSED */
1054 static int
1055 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1056 {
1057         struct {
1058                 u_int8_t version;
1059                 u_int8_t command;
1060                 u_int8_t reserved;
1061                 u_int8_t atyp;
1062         } s5_req, s5_rsp;
1063         u_int16_t dest_port;
1064         u_char *p, dest_addr[255+1];
1065         u_int have, need, i, found, nmethods, addrlen, af;
1066
1067         debug2("channel %d: decode socks5", c->self);
1068         p = buffer_ptr(&c->input);
1069         if (p[0] != 0x05)
1070                 return -1;
1071         have = buffer_len(&c->input);
1072         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1073                 /* format: ver | nmethods | methods */
1074                 if (have < 2)
1075                         return 0;
1076                 nmethods = p[1];
1077                 if (have < nmethods + 2)
1078                         return 0;
1079                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1080                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1081                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1082                                 found = 1;
1083                                 break;
1084                         }
1085                 }
1086                 if (!found) {
1087                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1088                             c->self);
1089                         return -1;
1090                 }
1091                 buffer_consume(&c->input, nmethods + 2);
1092                 buffer_put_char(&c->output, 0x05);              /* version */
1093                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1094                 FD_SET(c->sock, writeset);
1095                 c->flags |= SSH_SOCKS5_AUTHDONE;
1096                 debug2("channel %d: socks5 auth done", c->self);
1097                 return 0;                               /* need more */
1098         }
1099         debug2("channel %d: socks5 post auth", c->self);
1100         if (have < sizeof(s5_req)+1)
1101                 return 0;                       /* need more */
1102         memcpy(&s5_req, p, sizeof(s5_req));
1103         if (s5_req.version != 0x05 ||
1104             s5_req.command != SSH_SOCKS5_CONNECT ||
1105             s5_req.reserved != 0x00) {
1106                 debug2("channel %d: only socks5 connect supported", c->self);
1107                 return -1;
1108         }
1109         switch (s5_req.atyp){
1110         case SSH_SOCKS5_IPV4:
1111                 addrlen = 4;
1112                 af = AF_INET;
1113                 break;
1114         case SSH_SOCKS5_DOMAIN:
1115                 addrlen = p[sizeof(s5_req)];
1116                 af = -1;
1117                 break;
1118         case SSH_SOCKS5_IPV6:
1119                 addrlen = 16;
1120                 af = AF_INET6;
1121                 break;
1122         default:
1123                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1124                 return -1;
1125         }
1126         need = sizeof(s5_req) + addrlen + 2;
1127         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1128                 need++;
1129         if (have < need)
1130                 return 0;
1131         buffer_consume(&c->input, sizeof(s5_req));
1132         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1133                 buffer_consume(&c->input, 1);    /* host string length */
1134         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1135         buffer_get(&c->input, (char *)&dest_port, 2);
1136         dest_addr[addrlen] = '\0';
1137         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1138                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1139         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1140                 return -1;
1141         c->host_port = ntohs(dest_port);
1142
1143         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1144             c->self, c->path, c->host_port, s5_req.command);
1145
1146         s5_rsp.version = 0x05;
1147         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1148         s5_rsp.reserved = 0;                    /* ignored */
1149         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1150         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1151         dest_port = 0;                          /* ignored */
1152
1153         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1154         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1155         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1156         return 1;
1157 }
1158
1159 /* dynamic port forwarding */
1160 static void
1161 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1162 {
1163         u_char *p;
1164         u_int have;
1165         int ret;
1166
1167         have = buffer_len(&c->input);
1168         c->delayed = 0;
1169         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1170         /* buffer_dump(&c->input); */
1171         /* check if the fixed size part of the packet is in buffer. */
1172         if (have < 3) {
1173                 /* need more */
1174                 FD_SET(c->sock, readset);
1175                 return;
1176         }
1177         /* try to guess the protocol */
1178         p = buffer_ptr(&c->input);
1179         switch (p[0]) {
1180         case 0x04:
1181                 ret = channel_decode_socks4(c, readset, writeset);
1182                 break;
1183         case 0x05:
1184                 ret = channel_decode_socks5(c, readset, writeset);
1185                 break;
1186         default:
1187                 ret = -1;
1188                 break;
1189         }
1190         if (ret < 0) {
1191                 chan_mark_dead(c);
1192         } else if (ret == 0) {
1193                 debug2("channel %d: pre_dynamic: need more", c->self);
1194                 /* need more */
1195                 FD_SET(c->sock, readset);
1196         } else {
1197                 /* switch to the next state */
1198                 c->type = SSH_CHANNEL_OPENING;
1199                 port_open_helper(c, "direct-tcpip");
1200         }
1201 }
1202
1203 /* This is our fake X11 server socket. */
1204 /* ARGSUSED */
1205 static void
1206 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1207 {
1208         Channel *nc;
1209         struct sockaddr addr;
1210         int newsock;
1211         socklen_t addrlen;
1212         char buf[16384], *remote_ipaddr;
1213         int remote_port;
1214
1215         if (FD_ISSET(c->sock, readset)) {
1216                 debug("X11 connection requested.");
1217                 addrlen = sizeof(addr);
1218                 newsock = accept(c->sock, &addr, &addrlen);
1219                 if (c->single_connection) {
1220                         debug2("single_connection: closing X11 listener.");
1221                         channel_close_fd(&c->sock);
1222                         chan_mark_dead(c);
1223                 }
1224                 if (newsock < 0) {
1225                         error("accept: %.100s", strerror(errno));
1226                         return;
1227                 }
1228                 set_nodelay(newsock);
1229                 remote_ipaddr = get_peer_ipaddr(newsock);
1230                 remote_port = get_peer_port(newsock);
1231                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1232                     remote_ipaddr, remote_port);
1233
1234                 nc = channel_new("accepted x11 socket",
1235                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1236                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1237                 if (compat20) {
1238                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1239                         packet_put_cstring("x11");
1240                         packet_put_int(nc->self);
1241                         packet_put_int(nc->local_window_max);
1242                         packet_put_int(nc->local_maxpacket);
1243                         /* originator ipaddr and port */
1244                         packet_put_cstring(remote_ipaddr);
1245                         if (datafellows & SSH_BUG_X11FWD) {
1246                                 debug2("ssh2 x11 bug compat mode");
1247                         } else {
1248                                 packet_put_int(remote_port);
1249                         }
1250                         packet_send();
1251                 } else {
1252                         packet_start(SSH_SMSG_X11_OPEN);
1253                         packet_put_int(nc->self);
1254                         if (packet_get_protocol_flags() &
1255                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1256                                 packet_put_cstring(buf);
1257                         packet_send();
1258                 }
1259                 xfree(remote_ipaddr);
1260         }
1261 }
1262
1263 static void
1264 port_open_helper(Channel *c, char *rtype)
1265 {
1266         int direct;
1267         char buf[1024];
1268         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1269         int remote_port = get_peer_port(c->sock);
1270
1271         direct = (strcmp(rtype, "direct-tcpip") == 0);
1272
1273         snprintf(buf, sizeof buf,
1274             "%s: listening port %d for %.100s port %d, "
1275             "connect from %.200s port %d",
1276             rtype, c->listening_port, c->path, c->host_port,
1277             remote_ipaddr, remote_port);
1278
1279         xfree(c->remote_name);
1280         c->remote_name = xstrdup(buf);
1281
1282         if (compat20) {
1283                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1284                 packet_put_cstring(rtype);
1285                 packet_put_int(c->self);
1286                 packet_put_int(c->local_window_max);
1287                 packet_put_int(c->local_maxpacket);
1288                 if (direct) {
1289                         /* target host, port */
1290                         packet_put_cstring(c->path);
1291                         packet_put_int(c->host_port);
1292                 } else {
1293                         /* listen address, port */
1294                         packet_put_cstring(c->path);
1295                         packet_put_int(c->listening_port);
1296                 }
1297                 /* originator host and port */
1298                 packet_put_cstring(remote_ipaddr);
1299                 packet_put_int((u_int)remote_port);
1300                 packet_send();
1301         } else {
1302                 packet_start(SSH_MSG_PORT_OPEN);
1303                 packet_put_int(c->self);
1304                 packet_put_cstring(c->path);
1305                 packet_put_int(c->host_port);
1306                 if (packet_get_protocol_flags() &
1307                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1308                         packet_put_cstring(c->remote_name);
1309                 packet_send();
1310         }
1311         xfree(remote_ipaddr);
1312 }
1313
1314 static void
1315 channel_set_reuseaddr(int fd)
1316 {
1317         int on = 1;
1318
1319         /*
1320          * Set socket options.
1321          * Allow local port reuse in TIME_WAIT.
1322          */
1323         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1324                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1325 }
1326
1327 /*
1328  * This socket is listening for connections to a forwarded TCP/IP port.
1329  */
1330 /* ARGSUSED */
1331 static void
1332 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1333 {
1334         Channel *nc;
1335         struct sockaddr addr;
1336         int newsock, nextstate;
1337         socklen_t addrlen;
1338         char *rtype;
1339
1340         if (FD_ISSET(c->sock, readset)) {
1341                 debug("Connection to port %d forwarding "
1342                     "to %.100s port %d requested.",
1343                     c->listening_port, c->path, c->host_port);
1344
1345                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1346                         nextstate = SSH_CHANNEL_OPENING;
1347                         rtype = "forwarded-tcpip";
1348                 } else {
1349                         if (c->host_port == 0) {
1350                                 nextstate = SSH_CHANNEL_DYNAMIC;
1351                                 rtype = "dynamic-tcpip";
1352                         } else {
1353                                 nextstate = SSH_CHANNEL_OPENING;
1354                                 rtype = "direct-tcpip";
1355                         }
1356                 }
1357
1358                 addrlen = sizeof(addr);
1359                 newsock = accept(c->sock, &addr, &addrlen);
1360                 if (newsock < 0) {
1361                         error("accept: %.100s", strerror(errno));
1362                         return;
1363                 }
1364                 set_nodelay(newsock);
1365                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1366                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1367                 nc->listening_port = c->listening_port;
1368                 nc->host_port = c->host_port;
1369                 strlcpy(nc->path, c->path, sizeof(nc->path));
1370
1371                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1372                         /*
1373                          * do not call the channel_post handler until
1374                          * this flag has been reset by a pre-handler.
1375                          * otherwise the FD_ISSET calls might overflow
1376                          */
1377                         nc->delayed = 1;
1378                 } else {
1379                         port_open_helper(nc, rtype);
1380                 }
1381         }
1382 }
1383
1384 /*
1385  * This is the authentication agent socket listening for connections from
1386  * clients.
1387  */
1388 /* ARGSUSED */
1389 static void
1390 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1391 {
1392         Channel *nc;
1393         int newsock;
1394         struct sockaddr addr;
1395         socklen_t addrlen;
1396
1397         if (FD_ISSET(c->sock, readset)) {
1398                 addrlen = sizeof(addr);
1399                 newsock = accept(c->sock, &addr, &addrlen);
1400                 if (newsock < 0) {
1401                         error("accept from auth socket: %.100s", strerror(errno));
1402                         return;
1403                 }
1404                 nc = channel_new("accepted auth socket",
1405                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1406                     c->local_window_max, c->local_maxpacket,
1407                     0, "accepted auth socket", 1);
1408                 if (compat20) {
1409                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1410                         packet_put_cstring("auth-agent@openssh.com");
1411                         packet_put_int(nc->self);
1412                         packet_put_int(c->local_window_max);
1413                         packet_put_int(c->local_maxpacket);
1414                 } else {
1415                         packet_start(SSH_SMSG_AGENT_OPEN);
1416                         packet_put_int(nc->self);
1417                 }
1418                 packet_send();
1419         }
1420 }
1421
1422 /* ARGSUSED */
1423 static void
1424 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1425 {
1426         int err = 0;
1427         socklen_t sz = sizeof(err);
1428
1429         if (FD_ISSET(c->sock, writeset)) {
1430                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1431                         err = errno;
1432                         error("getsockopt SO_ERROR failed");
1433                 }
1434                 if (err == 0) {
1435                         debug("channel %d: connected", c->self);
1436                         c->type = SSH_CHANNEL_OPEN;
1437                         if (compat20) {
1438                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1439                                 packet_put_int(c->remote_id);
1440                                 packet_put_int(c->self);
1441                                 packet_put_int(c->local_window);
1442                                 packet_put_int(c->local_maxpacket);
1443                         } else {
1444                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1445                                 packet_put_int(c->remote_id);
1446                                 packet_put_int(c->self);
1447                         }
1448                 } else {
1449                         debug("channel %d: not connected: %s",
1450                             c->self, strerror(err));
1451                         if (compat20) {
1452                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1453                                 packet_put_int(c->remote_id);
1454                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1455                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1456                                         packet_put_cstring(strerror(err));
1457                                         packet_put_cstring("");
1458                                 }
1459                         } else {
1460                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1461                                 packet_put_int(c->remote_id);
1462                         }
1463                         chan_mark_dead(c);
1464                 }
1465                 packet_send();
1466         }
1467 }
1468
1469 /* ARGSUSED */
1470 static int
1471 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1472 {
1473         char buf[CHAN_RBUF];
1474         int len, force;
1475
1476         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1477         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1478                 errno = 0;
1479                 len = read(c->rfd, buf, sizeof(buf));
1480                 if (len < 0 && (errno == EINTR || (errno == EAGAIN && !force)))
1481                         return 1;
1482 #ifndef PTY_ZEROREAD
1483                 if (len <= 0) {
1484 #else
1485                 if ((!c->isatty && len <= 0) ||
1486                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1487 #endif
1488                         debug2("channel %d: read<=0 rfd %d len %d",
1489                             c->self, c->rfd, len);
1490                         if (c->type != SSH_CHANNEL_OPEN) {
1491                                 debug2("channel %d: not open", c->self);
1492                                 chan_mark_dead(c);
1493                                 return -1;
1494                         } else if (compat13) {
1495                                 buffer_clear(&c->output);
1496                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1497                                 debug2("channel %d: input draining.", c->self);
1498                         } else {
1499                                 chan_read_failed(c);
1500                         }
1501                         return -1;
1502                 }
1503                 if (c->input_filter != NULL) {
1504                         if (c->input_filter(c, buf, len) == -1) {
1505                                 debug2("channel %d: filter stops", c->self);
1506                                 chan_read_failed(c);
1507                         }
1508                 } else if (c->datagram) {
1509                         buffer_put_string(&c->input, buf, len);
1510                 } else {
1511                         buffer_append(&c->input, buf, len);
1512                 }
1513         }
1514         return 1;
1515 }
1516
1517 /* ARGSUSED */
1518 static int
1519 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1520 {
1521         struct termios tio;
1522         u_char *data = NULL, *buf;
1523         u_int dlen;
1524         int len;
1525
1526         /* Send buffered output data to the socket. */
1527         if (c->wfd != -1 &&
1528             FD_ISSET(c->wfd, writeset) &&
1529             buffer_len(&c->output) > 0) {
1530                 if (c->output_filter != NULL) {
1531                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1532                                 debug2("channel %d: filter stops", c->self);
1533                                 if (c->type != SSH_CHANNEL_OPEN)
1534                                         chan_mark_dead(c);
1535                                 else
1536                                         chan_write_failed(c);
1537                                 return -1;
1538                         }
1539                 } else if (c->datagram) {
1540                         buf = data = buffer_get_string(&c->output, &dlen);
1541                 } else {
1542                         buf = data = buffer_ptr(&c->output);
1543                         dlen = buffer_len(&c->output);
1544                 }
1545
1546                 if (c->datagram) {
1547                         /* ignore truncated writes, datagrams might get lost */
1548                         c->local_consumed += dlen + 4;
1549                         len = write(c->wfd, buf, dlen);
1550                         xfree(data);
1551                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1552                                 return 1;
1553                         if (len <= 0) {
1554                                 if (c->type != SSH_CHANNEL_OPEN)
1555                                         chan_mark_dead(c);
1556                                 else
1557                                         chan_write_failed(c);
1558                                 return -1;
1559                         }
1560                         return 1;
1561                 }
1562 #ifdef _AIX
1563                 /* XXX: Later AIX versions can't push as much data to tty */
1564                 if (compat20 && c->wfd_isatty)
1565                         dlen = MIN(dlen, 8*1024);
1566 #endif
1567
1568                 len = write(c->wfd, buf, dlen);
1569                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1570                         return 1;
1571                 if (len <= 0) {
1572                         if (c->type != SSH_CHANNEL_OPEN) {
1573                                 debug2("channel %d: not open", c->self);
1574                                 chan_mark_dead(c);
1575                                 return -1;
1576                         } else if (compat13) {
1577                                 buffer_clear(&c->output);
1578                                 debug2("channel %d: input draining.", c->self);
1579                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1580                         } else {
1581                                 chan_write_failed(c);
1582                         }
1583                         return -1;
1584                 }
1585                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1586                         if (tcgetattr(c->wfd, &tio) == 0 &&
1587                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1588                                 /*
1589                                  * Simulate echo to reduce the impact of
1590                                  * traffic analysis. We need to match the
1591                                  * size of a SSH2_MSG_CHANNEL_DATA message
1592                                  * (4 byte channel id + buf)
1593                                  */
1594                                 packet_send_ignore(4 + len);
1595                                 packet_send();
1596                         }
1597                 }
1598                 buffer_consume(&c->output, len);
1599                 if (compat20 && len > 0) {
1600                         c->local_consumed += len;
1601                 }
1602         }
1603         return 1;
1604 }
1605
1606 static int
1607 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1608 {
1609         char buf[CHAN_RBUF];
1610         int len;
1611
1612 /** XXX handle drain efd, too */
1613         if (c->efd != -1) {
1614                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1615                     FD_ISSET(c->efd, writeset) &&
1616                     buffer_len(&c->extended) > 0) {
1617                         len = write(c->efd, buffer_ptr(&c->extended),
1618                             buffer_len(&c->extended));
1619                         debug2("channel %d: written %d to efd %d",
1620                             c->self, len, c->efd);
1621                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1622                                 return 1;
1623                         if (len <= 0) {
1624                                 debug2("channel %d: closing write-efd %d",
1625                                     c->self, c->efd);
1626                                 channel_close_fd(&c->efd);
1627                         } else {
1628                                 buffer_consume(&c->extended, len);
1629                                 c->local_consumed += len;
1630                         }
1631                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1632                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1633                         len = read(c->efd, buf, sizeof(buf));
1634                         debug2("channel %d: read %d from efd %d",
1635                             c->self, len, c->efd);
1636                         if (len < 0 && (errno == EINTR ||
1637                             (errno == EAGAIN && !c->detach_close)))
1638                                 return 1;
1639                         if (len <= 0) {
1640                                 debug2("channel %d: closing read-efd %d",
1641                                     c->self, c->efd);
1642                                 channel_close_fd(&c->efd);
1643                         } else {
1644                                 buffer_append(&c->extended, buf, len);
1645                         }
1646                 }
1647         }
1648         return 1;
1649 }
1650
1651 /* ARGSUSED */
1652 static int
1653 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1654 {
1655         char buf[16];
1656         int len;
1657
1658         /* Monitor control fd to detect if the slave client exits */
1659         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1660                 len = read(c->ctl_fd, buf, sizeof(buf));
1661                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1662                         return 1;
1663                 if (len <= 0) {
1664                         debug2("channel %d: ctl read<=0", c->self);
1665                         if (c->type != SSH_CHANNEL_OPEN) {
1666                                 debug2("channel %d: not open", c->self);
1667                                 chan_mark_dead(c);
1668                                 return -1;
1669                         } else {
1670                                 chan_read_failed(c);
1671                                 chan_write_failed(c);
1672                         }
1673                         return -1;
1674                 } else
1675                         fatal("%s: unexpected data on ctl fd", __func__);
1676         }
1677         return 1;
1678 }
1679
1680 static int
1681 channel_check_window(Channel *c)
1682 {
1683         if (c->type == SSH_CHANNEL_OPEN &&
1684             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1685             ((c->local_window_max - c->local_window >
1686             c->local_maxpacket*3) ||
1687             c->local_window < c->local_window_max/2) &&
1688             c->local_consumed > 0) {
1689                 u_int addition = 0;
1690                 /* adjust max window size if we are in a dynamic environment */
1691                 if (c->dynamic_window && (c->tcpwinsz > c->local_window_max)) {
1692                         /* grow the window somewhat aggressively to maintain pressure */
1693                         addition = 1.5*(c->tcpwinsz - c->local_window_max);
1694                         c->local_window_max += addition;
1695                 }
1696                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1697                 packet_put_int(c->remote_id);
1698                 packet_put_int(c->local_consumed + addition);
1699                 packet_send();
1700                 debug2("channel %d: window %d sent adjust %d",
1701                     c->self, c->local_window,
1702                     c->local_consumed);
1703                 c->local_window += c->local_consumed + addition;
1704                 c->local_consumed = 0;
1705         }
1706         return 1;
1707 }
1708
1709 static void
1710 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1711 {
1712         if (c->delayed)
1713                 return;
1714         channel_handle_rfd(c, readset, writeset);
1715         channel_handle_wfd(c, readset, writeset);
1716         if (!compat20)
1717                 return;
1718         channel_handle_efd(c, readset, writeset);
1719         channel_handle_ctl(c, readset, writeset);
1720         channel_check_window(c);
1721 }
1722
1723 /* ARGSUSED */
1724 static void
1725 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1726 {
1727         int len;
1728
1729         /* Send buffered output data to the socket. */
1730         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1731                 len = write(c->sock, buffer_ptr(&c->output),
1732                             buffer_len(&c->output));
1733                 if (len <= 0)
1734                         buffer_clear(&c->output);
1735                 else
1736                         buffer_consume(&c->output, len);
1737         }
1738 }
1739
1740 static void
1741 channel_handler_init_20(void)
1742 {
1743         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1744         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1745         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1746         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1747         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1748         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1749         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1750         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1751
1752         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1753         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1754         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1755         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1756         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1757         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1758         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1759 }
1760
1761 static void
1762 channel_handler_init_13(void)
1763 {
1764         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1765         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1766         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1767         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1768         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1769         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1770         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1771         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1772         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1773
1774         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1775         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1776         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1777         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1778         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1779         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1780         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1781 }
1782
1783 static void
1784 channel_handler_init_15(void)
1785 {
1786         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1787         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1788         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1789         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1790         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1791         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1792         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1793
1794         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1795         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1796         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1797         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1798         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1799         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1800 }
1801
1802 static void
1803 channel_handler_init(void)
1804 {
1805         int i;
1806
1807         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1808                 channel_pre[i] = NULL;
1809                 channel_post[i] = NULL;
1810         }
1811         if (compat20)
1812                 channel_handler_init_20();
1813         else if (compat13)
1814                 channel_handler_init_13();
1815         else
1816                 channel_handler_init_15();
1817 }
1818
1819 /* gc dead channels */
1820 static void
1821 channel_garbage_collect(Channel *c)
1822 {
1823         if (c == NULL)
1824                 return;
1825         if (c->detach_user != NULL) {
1826                 if (!chan_is_dead(c, c->detach_close))
1827                         return;
1828                 debug2("channel %d: gc: notify user", c->self);
1829                 c->detach_user(c->self, NULL);
1830                 /* if we still have a callback */
1831                 if (c->detach_user != NULL)
1832                         return;
1833                 debug2("channel %d: gc: user detached", c->self);
1834         }
1835         if (!chan_is_dead(c, 1))
1836                 return;
1837         debug2("channel %d: garbage collecting", c->self);
1838         channel_free(c);
1839 }
1840
1841 static void
1842 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1843 {
1844         static int did_init = 0;
1845         u_int i;
1846         Channel *c;
1847
1848         if (!did_init) {
1849                 channel_handler_init();
1850                 did_init = 1;
1851         }
1852         for (i = 0; i < channels_alloc; i++) {
1853                 c = channels[i];
1854                 if (c == NULL)
1855                         continue;
1856                 if (ftab[c->type] != NULL)
1857                         (*ftab[c->type])(c, readset, writeset);
1858                 channel_garbage_collect(c);
1859         }
1860 }
1861
1862 /*
1863  * Allocate/update select bitmasks and add any bits relevant to channels in
1864  * select bitmasks.
1865  */
1866 void
1867 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1868     u_int *nallocp, int rekeying)
1869 {
1870         u_int n, sz, nfdset;
1871
1872         n = MAX(*maxfdp, channel_max_fd);
1873
1874         nfdset = howmany(n+1, NFDBITS);
1875         /* Explicitly test here, because xrealloc isn't always called */
1876         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1877                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1878         sz = nfdset * sizeof(fd_mask);
1879
1880         /* perhaps check sz < nalloc/2 and shrink? */
1881         if (*readsetp == NULL || sz > *nallocp) {
1882                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1883                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1884                 *nallocp = sz;
1885         }
1886         *maxfdp = n;
1887         memset(*readsetp, 0, sz);
1888         memset(*writesetp, 0, sz);
1889
1890         if (!rekeying)
1891                 channel_handler(channel_pre, *readsetp, *writesetp);
1892 }
1893
1894 /*
1895  * After select, perform any appropriate operations for channels which have
1896  * events pending.
1897  */
1898 void
1899 channel_after_select(fd_set *readset, fd_set *writeset)
1900 {
1901         channel_handler(channel_post, readset, writeset);
1902 }
1903
1904
1905 /* If there is data to send to the connection, enqueue some of it now. */
1906 int
1907 channel_output_poll(void)
1908 {
1909         Channel *c;
1910         u_int i, len;
1911         int packet_length = 0;
1912
1913         for (i = 0; i < channels_alloc; i++) {
1914                 c = channels[i];
1915                 if (c == NULL)
1916                         continue;
1917
1918                 /*
1919                  * We are only interested in channels that can have buffered
1920                  * incoming data.
1921                  */
1922                 if (compat13) {
1923                         if (c->type != SSH_CHANNEL_OPEN &&
1924                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1925                                 continue;
1926                 } else {
1927                         if (c->type != SSH_CHANNEL_OPEN)
1928                                 continue;
1929                 }
1930                 if (compat20 &&
1931                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1932                         /* XXX is this true? */
1933                         debug3("channel %d: will not send data after close", c->self);
1934                         continue;
1935                 }
1936
1937                 /* Get the amount of buffered data for this channel. */
1938                 if ((c->istate == CHAN_INPUT_OPEN ||
1939                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1940                     (len = buffer_len(&c->input)) > 0) {
1941                         if (c->datagram) {
1942                                 if (len > 0) {
1943                                         u_char *data;
1944                                         u_int dlen;
1945
1946                                         data = buffer_get_string(&c->input,
1947                                             &dlen);
1948                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1949                                         packet_put_int(c->remote_id);
1950                                         packet_put_string(data, dlen);
1951                                         packet_length = packet_send();
1952                                         c->remote_window -= dlen + 4;
1953                                         xfree(data);
1954                                 }
1955                                 continue;
1956                         }
1957                         /*
1958                          * Send some data for the other side over the secure
1959                          * connection.
1960                          */
1961                         if (compat20) {
1962                                 if (len > c->remote_window)
1963                                         len = c->remote_window;
1964                                 if (len > c->remote_maxpacket)
1965                                         len = c->remote_maxpacket;
1966                         } else {
1967                                 if (packet_is_interactive()) {
1968                                         if (len > 1024)
1969                                                 len = 512;
1970                                 } else {
1971                                         /* Keep the packets at reasonable size. */
1972                                         if (len > packet_get_maxsize()/2)
1973                                                 len = packet_get_maxsize()/2;
1974                                 }
1975                         }
1976                         if (len > 0) {
1977                                 packet_start(compat20 ?
1978                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1979                                 packet_put_int(c->remote_id);
1980                                 packet_put_string(buffer_ptr(&c->input), len);
1981                                 packet_length = packet_send();
1982                                 buffer_consume(&c->input, len);
1983                                 c->remote_window -= len;
1984                         }
1985                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1986                         if (compat13)
1987                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1988                         /*
1989                          * input-buffer is empty and read-socket shutdown:
1990                          * tell peer, that we will not send more data: send IEOF.
1991                          * hack for extended data: delay EOF if EFD still in use.
1992                          */
1993                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1994                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1995                                     c->self, c->efd, buffer_len(&c->extended));
1996                         else
1997                                 chan_ibuf_empty(c);
1998                 }
1999                 /* Send extended data, i.e. stderr */
2000                 if (compat20 &&
2001                     !(c->flags & CHAN_EOF_SENT) &&
2002                     c->remote_window > 0 &&
2003                     (len = buffer_len(&c->extended)) > 0 &&
2004                     c->extended_usage == CHAN_EXTENDED_READ) {
2005                         debug2("channel %d: rwin %u elen %u euse %d",
2006                             c->self, c->remote_window, buffer_len(&c->extended),
2007                             c->extended_usage);
2008                         if (len > c->remote_window)
2009                                 len = c->remote_window;
2010                         if (len > c->remote_maxpacket)
2011                                 len = c->remote_maxpacket;
2012                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2013                         packet_put_int(c->remote_id);
2014                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2015                         packet_put_string(buffer_ptr(&c->extended), len);
2016                         packet_length = packet_send();
2017                         buffer_consume(&c->extended, len);
2018                         c->remote_window -= len;
2019                         debug2("channel %d: sent ext data %d", c->self, len);
2020                 }
2021         }
2022         return (packet_length);
2023 }
2024
2025
2026 /* -- protocol input */
2027
2028 /* ARGSUSED */
2029 void
2030 channel_input_data(int type, u_int32_t seq, void *ctxt)
2031 {
2032         int id;
2033         char *data;
2034         u_int data_len;
2035         Channel *c;
2036
2037         /* Get the channel number and verify it. */
2038         id = packet_get_int();
2039         c = channel_lookup(id);
2040         if (c == NULL)
2041                 packet_disconnect("Received data for nonexistent channel %d.", id);
2042
2043         /* Ignore any data for non-open channels (might happen on close) */
2044         if (c->type != SSH_CHANNEL_OPEN &&
2045             c->type != SSH_CHANNEL_X11_OPEN)
2046                 return;
2047
2048         /* Get the data. */
2049         data = packet_get_string(&data_len);
2050
2051         /*
2052          * Ignore data for protocol > 1.3 if output end is no longer open.
2053          * For protocol 2 the sending side is reducing its window as it sends
2054          * data, so we must 'fake' consumption of the data in order to ensure
2055          * that window updates are sent back.  Otherwise the connection might
2056          * deadlock.
2057          */
2058         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2059                 if (compat20) {
2060                         c->local_window -= data_len;
2061                         c->local_consumed += data_len;
2062                 }
2063                 xfree(data);
2064                 return;
2065         }
2066
2067         if (compat20) {
2068                 if (data_len > c->local_maxpacket) {
2069                         logit("channel %d: rcvd big packet %d, maxpack %d",
2070                             c->self, data_len, c->local_maxpacket);
2071                 }
2072                 if (data_len > c->local_window) {
2073                         logit("channel %d: rcvd too much data %d, win %d",
2074                             c->self, data_len, c->local_window);
2075                         xfree(data);
2076                         return;
2077                 }
2078                 c->local_window -= data_len;
2079         }
2080         packet_check_eom();
2081         if (c->datagram)
2082                 buffer_put_string(&c->output, data, data_len);
2083         else
2084                 buffer_append(&c->output, data, data_len);
2085         xfree(data);
2086 }
2087
2088 /* ARGSUSED */
2089 void
2090 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2091 {
2092         int id;
2093         char *data;
2094         u_int data_len, tcode;
2095         Channel *c;
2096
2097         /* Get the channel number and verify it. */
2098         id = packet_get_int();
2099         c = channel_lookup(id);
2100
2101         if (c == NULL)
2102                 packet_disconnect("Received extended_data for bad channel %d.", id);
2103         if (c->type != SSH_CHANNEL_OPEN) {
2104                 logit("channel %d: ext data for non open", id);
2105                 return;
2106         }
2107         if (c->flags & CHAN_EOF_RCVD) {
2108                 if (datafellows & SSH_BUG_EXTEOF)
2109                         debug("channel %d: accepting ext data after eof", id);
2110                 else
2111                         packet_disconnect("Received extended_data after EOF "
2112                             "on channel %d.", id);
2113         }
2114         tcode = packet_get_int();
2115         if (c->efd == -1 ||
2116             c->extended_usage != CHAN_EXTENDED_WRITE ||
2117             tcode != SSH2_EXTENDED_DATA_STDERR) {
2118                 logit("channel %d: bad ext data", c->self);
2119                 return;
2120         }
2121         data = packet_get_string(&data_len);
2122         packet_check_eom();
2123         if (data_len > c->local_window) {
2124                 logit("channel %d: rcvd too much extended_data %d, win %d",
2125                     c->self, data_len, c->local_window);
2126                 xfree(data);
2127                 return;
2128         }
2129         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2130         c->local_window -= data_len;
2131         buffer_append(&c->extended, data, data_len);
2132         xfree(data);
2133 }
2134
2135 /* ARGSUSED */
2136 void
2137 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2138 {
2139         int id;
2140         Channel *c;
2141
2142         id = packet_get_int();
2143         packet_check_eom();
2144         c = channel_lookup(id);
2145         if (c == NULL)
2146                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2147         chan_rcvd_ieof(c);
2148
2149         /* XXX force input close */
2150         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2151                 debug("channel %d: FORCE input drain", c->self);
2152                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2153                 if (buffer_len(&c->input) == 0)
2154                         chan_ibuf_empty(c);
2155         }
2156
2157 }
2158
2159 /* ARGSUSED */
2160 void
2161 channel_input_close(int type, u_int32_t seq, void *ctxt)
2162 {
2163         int id;
2164         Channel *c;
2165
2166         id = packet_get_int();
2167         packet_check_eom();
2168         c = channel_lookup(id);
2169         if (c == NULL)
2170                 packet_disconnect("Received close for nonexistent channel %d.", id);
2171
2172         /*
2173          * Send a confirmation that we have closed the channel and no more
2174          * data is coming for it.
2175          */
2176         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2177         packet_put_int(c->remote_id);
2178         packet_send();
2179
2180         /*
2181          * If the channel is in closed state, we have sent a close request,
2182          * and the other side will eventually respond with a confirmation.
2183          * Thus, we cannot free the channel here, because then there would be
2184          * no-one to receive the confirmation.  The channel gets freed when
2185          * the confirmation arrives.
2186          */
2187         if (c->type != SSH_CHANNEL_CLOSED) {
2188                 /*
2189                  * Not a closed channel - mark it as draining, which will
2190                  * cause it to be freed later.
2191                  */
2192                 buffer_clear(&c->input);
2193                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2194         }
2195 }
2196
2197 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2198 /* ARGSUSED */
2199 void
2200 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2201 {
2202         int id = packet_get_int();
2203         Channel *c = channel_lookup(id);
2204
2205         packet_check_eom();
2206         if (c == NULL)
2207                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2208         chan_rcvd_oclose(c);
2209 }
2210
2211 /* ARGSUSED */
2212 void
2213 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2214 {
2215         int id = packet_get_int();
2216         Channel *c = channel_lookup(id);
2217
2218         packet_check_eom();
2219         if (c == NULL)
2220                 packet_disconnect("Received close confirmation for "
2221                     "out-of-range channel %d.", id);
2222         if (c->type != SSH_CHANNEL_CLOSED)
2223                 packet_disconnect("Received close confirmation for "
2224                     "non-closed channel %d (type %d).", id, c->type);
2225         channel_free(c);
2226 }
2227
2228 /* ARGSUSED */
2229 void
2230 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2231 {
2232         int id, remote_id;
2233         Channel *c;
2234
2235         id = packet_get_int();
2236         c = channel_lookup(id);
2237
2238         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2239                 packet_disconnect("Received open confirmation for "
2240                     "non-opening channel %d.", id);
2241         remote_id = packet_get_int();
2242         /* Record the remote channel number and mark that the channel is now open. */
2243         c->remote_id = remote_id;
2244         c->type = SSH_CHANNEL_OPEN;
2245
2246         if (compat20) {
2247                 c->remote_window = packet_get_int();
2248                 c->remote_maxpacket = packet_get_int();
2249                 if (c->confirm) {
2250                         debug2("callback start");
2251                         c->confirm(c->self, c->confirm_ctx);
2252                         debug2("callback done");
2253                 }
2254                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2255                     c->remote_window, c->remote_maxpacket);
2256         }
2257         packet_check_eom();
2258 }
2259
2260 static char *
2261 reason2txt(int reason)
2262 {
2263         switch (reason) {
2264         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2265                 return "administratively prohibited";
2266         case SSH2_OPEN_CONNECT_FAILED:
2267                 return "connect failed";
2268         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2269                 return "unknown channel type";
2270         case SSH2_OPEN_RESOURCE_SHORTAGE:
2271                 return "resource shortage";
2272         }
2273         return "unknown reason";
2274 }
2275
2276 /* ARGSUSED */
2277 void
2278 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2279 {
2280         int id, reason;
2281         char *msg = NULL, *lang = NULL;
2282         Channel *c;
2283
2284         id = packet_get_int();
2285         c = channel_lookup(id);
2286
2287         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2288                 packet_disconnect("Received open failure for "
2289                     "non-opening channel %d.", id);
2290         if (compat20) {
2291                 reason = packet_get_int();
2292                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2293                         msg  = packet_get_string(NULL);
2294                         lang = packet_get_string(NULL);
2295                 }
2296                 logit("channel %d: open failed: %s%s%s", id,
2297                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2298                 if (msg != NULL)
2299                         xfree(msg);
2300                 if (lang != NULL)
2301                         xfree(lang);
2302         }
2303         packet_check_eom();
2304         /* Free the channel.  This will also close the socket. */
2305         channel_free(c);
2306 }
2307
2308 /* ARGSUSED */
2309 void
2310 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2311 {
2312         Channel *c;
2313         int id;
2314         u_int adjust;
2315
2316         if (!compat20)
2317                 return;
2318
2319         /* Get the channel number and verify it. */
2320         id = packet_get_int();
2321         c = channel_lookup(id);
2322
2323         if (c == NULL) {
2324                 logit("Received window adjust for non-open channel %d.", id);
2325                 return;
2326         }
2327         adjust = packet_get_int();
2328         packet_check_eom();
2329         debug2("channel %d: rcvd adjust %u", id, adjust);
2330         c->remote_window += adjust;
2331 }
2332
2333 /* ARGSUSED */
2334 void
2335 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2336 {
2337         Channel *c = NULL;
2338         u_short host_port;
2339         char *host, *originator_string;
2340         int remote_id, sock = -1;
2341
2342         remote_id = packet_get_int();
2343         host = packet_get_string(NULL);
2344         host_port = packet_get_int();
2345
2346         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2347                 originator_string = packet_get_string(NULL);
2348         } else {
2349                 originator_string = xstrdup("unknown (remote did not supply name)");
2350         }
2351         packet_check_eom();
2352         sock = channel_connect_to(host, host_port);
2353         if (sock != -1) {
2354                 c = channel_new("connected socket",
2355                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2356                     originator_string, 1);
2357                 c->remote_id = remote_id;
2358         }
2359         xfree(originator_string);
2360         if (c == NULL) {
2361                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2362                 packet_put_int(remote_id);
2363                 packet_send();
2364         }
2365         xfree(host);
2366 }
2367
2368
2369 /* -- tcp forwarding */
2370
2371 void
2372 channel_set_af(int af)
2373 {
2374         IPv4or6 = af;
2375 }
2376
2377 static int
2378 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2379     const char *host_to_connect, u_short port_to_connect, int gateway_ports,
2380     int hpn_disabled, int hpn_buffer_size)
2381 {
2382         Channel *c;
2383         int sock, r, success = 0, wildcard = 0, is_client;
2384         struct addrinfo hints, *ai, *aitop;
2385         const char *host, *addr;
2386         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2387
2388         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2389             listen_addr : host_to_connect;
2390         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2391
2392         if (host == NULL) {
2393                 error("No forward host name.");
2394                 return 0;
2395         }
2396         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2397                 error("Forward host name too long.");
2398                 return 0;
2399         }
2400
2401         /*
2402          * Determine whether or not a port forward listens to loopback,
2403          * specified address or wildcard. On the client, a specified bind
2404          * address will always override gateway_ports. On the server, a
2405          * gateway_ports of 1 (``yes'') will override the client's
2406          * specification and force a wildcard bind, whereas a value of 2
2407          * (``clientspecified'') will bind to whatever address the client
2408          * asked for.
2409          *
2410          * Special-case listen_addrs are:
2411          *
2412          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2413          * "" (empty string), "*"  -> wildcard v4/v6
2414          * "localhost"             -> loopback v4/v6
2415          */
2416         addr = NULL;
2417         if (listen_addr == NULL) {
2418                 /* No address specified: default to gateway_ports setting */
2419                 if (gateway_ports)
2420                         wildcard = 1;
2421         } else if (gateway_ports || is_client) {
2422                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2423                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2424                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2425                     (!is_client && gateway_ports == 1))
2426                         wildcard = 1;
2427                 else if (strcmp(listen_addr, "localhost") != 0)
2428                         addr = listen_addr;
2429         }
2430
2431         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2432             type, wildcard, (addr == NULL) ? "NULL" : addr);
2433
2434         /*
2435          * getaddrinfo returns a loopback address if the hostname is
2436          * set to NULL and hints.ai_flags is not AI_PASSIVE
2437          */
2438         memset(&hints, 0, sizeof(hints));
2439         hints.ai_family = IPv4or6;
2440         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2441         hints.ai_socktype = SOCK_STREAM;
2442         snprintf(strport, sizeof strport, "%d", listen_port);
2443         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2444                 if (addr == NULL) {
2445                         /* This really shouldn't happen */
2446                         packet_disconnect("getaddrinfo: fatal error: %s",
2447                             ssh_gai_strerror(r));
2448                 } else {
2449                         error("channel_setup_fwd_listener: "
2450                             "getaddrinfo(%.64s): %s", addr,
2451                             ssh_gai_strerror(r));
2452                 }
2453                 return 0;
2454         }
2455
2456         for (ai = aitop; ai; ai = ai->ai_next) {
2457                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2458                         continue;
2459                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2460                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2461                         error("channel_setup_fwd_listener: getnameinfo failed");
2462                         continue;
2463                 }
2464                 /* Create a port to listen for the host. */
2465                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2466                 if (sock < 0) {
2467                         /* this is no error since kernel may not support ipv6 */
2468                         verbose("socket: %.100s", strerror(errno));
2469                         continue;
2470                 }
2471
2472                 channel_set_reuseaddr(sock);
2473
2474                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2475
2476                 /* Bind the socket to the address. */
2477                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2478                         /* address can be in use ipv6 address is already bound */
2479                         if (!ai->ai_next)
2480                                 error("bind: %.100s", strerror(errno));
2481                         else
2482                                 verbose("bind: %.100s", strerror(errno));
2483
2484                         close(sock);
2485                         continue;
2486                 }
2487                 /* Start listening for connections on the socket. */
2488                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2489                         error("listen: %.100s", strerror(errno));
2490                         close(sock);
2491                         continue;
2492                 }
2493                 /* Allocate a channel number for the socket. */
2494                 /* explicitly test for hpn disabled option. if true use smaller window size */
2495                 if (hpn_disabled)
2496                 c = channel_new("port listener", type, sock, sock, -1,
2497                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2498                     0, "port listener", 1);
2499                 else
2500                         c = channel_new("port listener", type, sock, sock, -1,
2501                           hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT,
2502                           0, "port listener", 1);
2503                 strlcpy(c->path, host, sizeof(c->path));
2504                 c->host_port = port_to_connect;
2505                 c->listening_port = listen_port;
2506                 success = 1;
2507         }
2508         if (success == 0)
2509                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2510                     listen_port);
2511         freeaddrinfo(aitop);
2512         return success;
2513 }
2514
2515 int
2516 channel_cancel_rport_listener(const char *host, u_short port)
2517 {
2518         u_int i;
2519         int found = 0;
2520
2521         for (i = 0; i < channels_alloc; i++) {
2522                 Channel *c = channels[i];
2523
2524                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2525                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2526                     c->listening_port == port) {
2527                         debug2("%s: close channel %d", __func__, i);
2528                         channel_free(c);
2529                         found = 1;
2530                 }
2531         }
2532
2533         return (found);
2534 }
2535
2536 /* protocol local port fwd, used by ssh (and sshd in v1) */
2537 int
2538 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2539     const char *host_to_connect, u_short port_to_connect, int gateway_ports,
2540     int hpn_disabled, int hpn_buffer_size)
2541 {
2542         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2543             listen_host, listen_port, host_to_connect, port_to_connect,
2544             gateway_ports, hpn_disabled, hpn_buffer_size);
2545 }
2546
2547 /* protocol v2 remote port fwd, used by sshd */
2548 int
2549 channel_setup_remote_fwd_listener(const char *listen_address,
2550     u_short listen_port, int gateway_ports, int hpn_disabled, int hpn_buffer_size)
2551 {
2552         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2553             listen_address, listen_port, NULL, 0, gateway_ports,
2554             hpn_disabled, hpn_buffer_size);
2555 }
2556
2557 /*
2558  * Initiate forwarding of connections to port "port" on remote host through
2559  * the secure channel to host:port from local side.
2560  */
2561
2562 int
2563 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2564     const char *host_to_connect, u_short port_to_connect)
2565 {
2566         int type, success = 0;
2567
2568         /* Record locally that connection to this host/port is permitted. */
2569         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2570                 fatal("channel_request_remote_forwarding: too many forwards");
2571
2572         /* Send the forward request to the remote side. */
2573         if (compat20) {
2574                 const char *address_to_bind;
2575                 if (listen_host == NULL) {
2576                         if (datafellows & SSH_BUG_RFWD_ADDR)
2577                                 address_to_bind = "127.0.0.1";
2578                         else
2579                                 address_to_bind = "localhost";
2580                 } else if (*listen_host == '\0' ||
2581                            strcmp(listen_host, "*") == 0) {
2582                         if (datafellows & SSH_BUG_RFWD_ADDR)
2583                                 address_to_bind = "0.0.0.0";
2584                         else
2585                                 address_to_bind = "";
2586                 } else
2587                         address_to_bind = listen_host;
2588
2589                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2590                 packet_put_cstring("tcpip-forward");
2591                 packet_put_char(1);                     /* boolean: want reply */
2592                 packet_put_cstring(address_to_bind);
2593                 packet_put_int(listen_port);
2594                 packet_send();
2595                 packet_write_wait();
2596                 /* Assume that server accepts the request */
2597                 success = 1;
2598         } else {
2599                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2600                 packet_put_int(listen_port);
2601                 packet_put_cstring(host_to_connect);
2602                 packet_put_int(port_to_connect);
2603                 packet_send();
2604                 packet_write_wait();
2605
2606                 /* Wait for response from the remote side. */
2607                 type = packet_read();
2608                 switch (type) {
2609                 case SSH_SMSG_SUCCESS:
2610                         success = 1;
2611                         break;
2612                 case SSH_SMSG_FAILURE:
2613                         break;
2614                 default:
2615                         /* Unknown packet */
2616                         packet_disconnect("Protocol error for port forward request:"
2617                             "received packet type %d.", type);
2618                 }
2619         }
2620         if (success) {
2621                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2622                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2623                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2624                 num_permitted_opens++;
2625         }
2626         return (success ? 0 : -1);
2627 }
2628
2629 /*
2630  * Request cancellation of remote forwarding of connection host:port from
2631  * local side.
2632  */
2633 void
2634 channel_request_rforward_cancel(const char *host, u_short port)
2635 {
2636         int i;
2637
2638         if (!compat20)
2639                 return;
2640
2641         for (i = 0; i < num_permitted_opens; i++) {
2642                 if (permitted_opens[i].host_to_connect != NULL &&
2643                     permitted_opens[i].listen_port == port)
2644                         break;
2645         }
2646         if (i >= num_permitted_opens) {
2647                 debug("%s: requested forward not found", __func__);
2648                 return;
2649         }
2650         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2651         packet_put_cstring("cancel-tcpip-forward");
2652         packet_put_char(0);
2653         packet_put_cstring(host == NULL ? "" : host);
2654         packet_put_int(port);
2655         packet_send();
2656
2657         permitted_opens[i].listen_port = 0;
2658         permitted_opens[i].port_to_connect = 0;
2659         xfree(permitted_opens[i].host_to_connect);
2660         permitted_opens[i].host_to_connect = NULL;
2661 }
2662
2663 /*
2664  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2665  * listening for the port, and sends back a success reply (or disconnect
2666  * message if there was an error).
2667  */
2668 int
2669 channel_input_port_forward_request(int is_root, int gateway_ports,
2670                                    int hpn_disabled, int hpn_buffer_size)
2671 {
2672         u_short port, host_port;
2673         int success = 0;
2674         char *hostname;
2675
2676         /* Get arguments from the packet. */
2677         port = packet_get_int();
2678         hostname = packet_get_string(NULL);
2679         host_port = packet_get_int();
2680
2681 #ifndef HAVE_CYGWIN
2682         /*
2683          * Check that an unprivileged user is not trying to forward a
2684          * privileged port.
2685          */
2686         if (port < IPPORT_RESERVED && !is_root)
2687                 packet_disconnect(
2688                     "Requested forwarding of port %d but user is not root.",
2689                     port);
2690         if (host_port == 0)
2691                 packet_disconnect("Dynamic forwarding denied.");
2692 #endif
2693
2694         /* Initiate forwarding */
2695         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2696             host_port, gateway_ports, hpn_disabled, hpn_buffer_size);
2697
2698         /* Free the argument string. */
2699         xfree(hostname);
2700
2701         return (success ? 0 : -1);
2702 }
2703
2704 /*
2705  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2706  * usually called by the server, because the user could connect to any port
2707  * anyway, and the server has no way to know but to trust the client anyway.
2708  */
2709 void
2710 channel_permit_all_opens(void)
2711 {
2712         if (num_permitted_opens == 0)
2713                 all_opens_permitted = 1;
2714 }
2715
2716 void
2717 channel_add_permitted_opens(char *host, int port)
2718 {
2719         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2720                 fatal("channel_add_permitted_opens: too many forwards");
2721         debug("allow port forwarding to host %s port %d", host, port);
2722
2723         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2724         permitted_opens[num_permitted_opens].port_to_connect = port;
2725         num_permitted_opens++;
2726
2727         all_opens_permitted = 0;
2728 }
2729
2730 int
2731 channel_add_adm_permitted_opens(char *host, int port)
2732 {
2733         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2734                 fatal("channel_add_adm_permitted_opens: too many forwards");
2735         debug("config allows port forwarding to host %s port %d", host, port);
2736
2737         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2738              = xstrdup(host);
2739         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2740         return ++num_adm_permitted_opens;
2741 }
2742
2743 void
2744 channel_clear_permitted_opens(void)
2745 {
2746         int i;
2747
2748         for (i = 0; i < num_permitted_opens; i++)
2749                 if (permitted_opens[i].host_to_connect != NULL)
2750                         xfree(permitted_opens[i].host_to_connect);
2751         num_permitted_opens = 0;
2752 }
2753
2754 void
2755 channel_clear_adm_permitted_opens(void)
2756 {
2757         int i;
2758
2759         for (i = 0; i < num_adm_permitted_opens; i++)
2760                 if (permitted_adm_opens[i].host_to_connect != NULL)
2761                         xfree(permitted_adm_opens[i].host_to_connect);
2762         num_adm_permitted_opens = 0;
2763 }
2764
2765 /* return socket to remote host, port */
2766 static int
2767 connect_to(const char *host, u_short port)
2768 {
2769         struct addrinfo hints, *ai, *aitop;
2770         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2771         int gaierr;
2772         int sock = -1;
2773
2774         memset(&hints, 0, sizeof(hints));
2775         hints.ai_family = IPv4or6;
2776         hints.ai_socktype = SOCK_STREAM;
2777         snprintf(strport, sizeof strport, "%d", port);
2778         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2779                 error("connect_to %.100s: unknown host (%s)", host,
2780                     ssh_gai_strerror(gaierr));
2781                 return -1;
2782         }
2783         for (ai = aitop; ai; ai = ai->ai_next) {
2784                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2785                         continue;
2786                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2787                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2788                         error("connect_to: getnameinfo failed");
2789                         continue;
2790                 }
2791                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2792                 if (sock < 0) {
2793                         if (ai->ai_next == NULL)
2794                                 error("socket: %.100s", strerror(errno));
2795                         else
2796                                 verbose("socket: %.100s", strerror(errno));
2797                         continue;
2798                 }
2799                 if (set_nonblock(sock) == -1)
2800                         fatal("%s: set_nonblock(%d)", __func__, sock);
2801                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2802                     errno != EINPROGRESS) {
2803                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2804                             strerror(errno));
2805                         close(sock);
2806                         continue;       /* fail -- try next */
2807                 }
2808                 break; /* success */
2809
2810         }
2811         freeaddrinfo(aitop);
2812         if (!ai) {
2813                 error("connect_to %.100s port %d: failed.", host, port);
2814                 return -1;
2815         }
2816         /* success */
2817         set_nodelay(sock);
2818         return sock;
2819 }
2820
2821 int
2822 channel_connect_by_listen_address(u_short listen_port)
2823 {
2824         int i;
2825
2826         for (i = 0; i < num_permitted_opens; i++)
2827                 if (permitted_opens[i].host_to_connect != NULL &&
2828                     permitted_opens[i].listen_port == listen_port)
2829                         return connect_to(
2830                             permitted_opens[i].host_to_connect,
2831                             permitted_opens[i].port_to_connect);
2832         error("WARNING: Server requests forwarding for unknown listen_port %d",
2833             listen_port);
2834         return -1;
2835 }
2836
2837 /* Check if connecting to that port is permitted and connect. */
2838 int
2839 channel_connect_to(const char *host, u_short port)
2840 {
2841         int i, permit, permit_adm = 1;
2842
2843         permit = all_opens_permitted;
2844         if (!permit) {
2845                 for (i = 0; i < num_permitted_opens; i++)
2846                         if (permitted_opens[i].host_to_connect != NULL &&
2847                             permitted_opens[i].port_to_connect == port &&
2848                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2849                                 permit = 1;
2850         }
2851
2852         if (num_adm_permitted_opens > 0) {
2853                 permit_adm = 0;
2854                 for (i = 0; i < num_adm_permitted_opens; i++)
2855                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2856                             permitted_adm_opens[i].port_to_connect == port &&
2857                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2858                             == 0)
2859                                 permit_adm = 1;
2860         }
2861
2862         if (!permit || !permit_adm) {
2863                 logit("Received request to connect to host %.100s port %d, "
2864                     "but the request was denied.", host, port);
2865                 return -1;
2866         }
2867         return connect_to(host, port);
2868 }
2869
2870 void
2871 channel_send_window_changes(void)
2872 {
2873         u_int i;
2874         struct winsize ws;
2875
2876         for (i = 0; i < channels_alloc; i++) {
2877                 if (channels[i] == NULL || !channels[i]->client_tty ||
2878                     channels[i]->type != SSH_CHANNEL_OPEN)
2879                         continue;
2880                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2881                         continue;
2882                 channel_request_start(i, "window-change", 0);
2883                 packet_put_int((u_int)ws.ws_col);
2884                 packet_put_int((u_int)ws.ws_row);
2885                 packet_put_int((u_int)ws.ws_xpixel);
2886                 packet_put_int((u_int)ws.ws_ypixel);
2887                 packet_send();
2888         }
2889 }
2890
2891 /* -- X11 forwarding */
2892
2893 /*
2894  * Creates an internet domain socket for listening for X11 connections.
2895  * Returns 0 and a suitable display number for the DISPLAY variable
2896  * stored in display_numberp , or -1 if an error occurs.
2897  */
2898 int
2899 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2900     int single_connection, u_int *display_numberp, int **chanids,
2901     int hpn_disabled, int hpn_buffer_size)
2902 {
2903         Channel *nc = NULL;
2904         int display_number, sock;
2905         u_short port;
2906         struct addrinfo hints, *ai, *aitop;
2907         char strport[NI_MAXSERV];
2908         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2909
2910         if (chanids == NULL)
2911                 return -1;
2912
2913         for (display_number = x11_display_offset;
2914             display_number < MAX_DISPLAYS;
2915             display_number++) {
2916                 port = 6000 + display_number;
2917                 memset(&hints, 0, sizeof(hints));
2918                 hints.ai_family = IPv4or6;
2919                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2920                 hints.ai_socktype = SOCK_STREAM;
2921                 snprintf(strport, sizeof strport, "%d", port);
2922                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2923                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
2924                         return -1;
2925                 }
2926                 for (ai = aitop; ai; ai = ai->ai_next) {
2927                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2928                                 continue;
2929                         sock = socket(ai->ai_family, ai->ai_socktype,
2930                             ai->ai_protocol);
2931                         if (sock < 0) {
2932                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2933                                         error("socket: %.100s", strerror(errno));
2934                                         freeaddrinfo(aitop);
2935                                         return -1;
2936                                 } else {
2937                                         debug("x11_create_display_inet: Socket family %d not supported",
2938                                                  ai->ai_family);
2939                                         continue;
2940                                 }
2941                         }
2942 #ifdef IPV6_V6ONLY
2943                         if (ai->ai_family == AF_INET6) {
2944                                 int on = 1;
2945                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2946                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2947                         }
2948 #endif
2949                         channel_set_reuseaddr(sock);
2950                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2951                                 debug2("bind port %d: %.100s", port, strerror(errno));
2952                                 close(sock);
2953
2954                                 if (ai->ai_next)
2955                                         continue;
2956
2957                                 for (n = 0; n < num_socks; n++) {
2958                                         close(socks[n]);
2959                                 }
2960                                 num_socks = 0;
2961                                 break;
2962                         }
2963                         socks[num_socks++] = sock;
2964 #ifndef DONT_TRY_OTHER_AF
2965                         if (num_socks == NUM_SOCKS)
2966                                 break;
2967 #else
2968                         if (x11_use_localhost) {
2969                                 if (num_socks == NUM_SOCKS)
2970                                         break;
2971                         } else {
2972                                 break;
2973                         }
2974 #endif
2975                 }
2976                 freeaddrinfo(aitop);
2977                 if (num_socks > 0)
2978                         break;
2979         }
2980         if (display_number >= MAX_DISPLAYS) {
2981                 error("Failed to allocate internet-domain X11 display socket.");
2982                 return -1;
2983         }
2984         /* Start listening for connections on the socket. */
2985         for (n = 0; n < num_socks; n++) {
2986                 sock = socks[n];
2987                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2988                         error("listen: %.100s", strerror(errno));
2989                         close(sock);
2990                         return -1;
2991                 }
2992         }
2993
2994         /* Allocate a channel for each socket. */
2995         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2996         for (n = 0; n < num_socks; n++) {
2997                 sock = socks[n];
2998                 /* Is this really necassary? */
2999                 if (hpn_disabled)
3000                 nc = channel_new("x11 listener",
3001                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3002                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3003                     0, "X11 inet listener", 1);
3004                 else
3005                         nc = channel_new("x11 listener",
3006                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3007                             hpn_buffer_size, CHAN_X11_PACKET_DEFAULT,
3008                             0, "X11 inet listener", 1);
3009                 nc->single_connection = single_connection;
3010                 (*chanids)[n] = nc->self;
3011         }
3012         (*chanids)[n] = -1;
3013
3014         /* Return the display number for the DISPLAY environment variable. */
3015         *display_numberp = display_number;
3016         return (0);
3017 }
3018
3019 static int
3020 connect_local_xsocket(u_int dnr)
3021 {
3022         int sock;
3023         struct sockaddr_un addr;
3024
3025         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3026         if (sock < 0)
3027                 error("socket: %.100s", strerror(errno));
3028         memset(&addr, 0, sizeof(addr));
3029         addr.sun_family = AF_UNIX;
3030         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
3031         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3032                 return sock;
3033         close(sock);
3034         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3035         return -1;
3036 }
3037
3038 int
3039 x11_connect_display(void)
3040 {
3041         u_int display_number;
3042         const char *display;
3043         char buf[1024], *cp;
3044         struct addrinfo hints, *ai, *aitop;
3045         char strport[NI_MAXSERV];
3046         int gaierr, sock = 0;
3047
3048         /* Try to open a socket for the local X server. */
3049         display = getenv("DISPLAY");
3050         if (!display) {
3051                 error("DISPLAY not set.");
3052                 return -1;
3053         }
3054         /*
3055          * Now we decode the value of the DISPLAY variable and make a
3056          * connection to the real X server.
3057          */
3058
3059         /*
3060          * Check if it is a unix domain socket.  Unix domain displays are in
3061          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3062          */
3063         if (strncmp(display, "unix:", 5) == 0 ||
3064             display[0] == ':') {
3065                 /* Connect to the unix domain socket. */
3066                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3067                         error("Could not parse display number from DISPLAY: %.100s",
3068                             display);
3069                         return -1;
3070                 }
3071                 /* Create a socket. */
3072                 sock = connect_local_xsocket(display_number);
3073                 if (sock < 0)
3074                         return -1;
3075
3076                 /* OK, we now have a connection to the display. */
3077                 return sock;
3078         }
3079         /*
3080          * Connect to an inet socket.  The DISPLAY value is supposedly
3081          * hostname:d[.s], where hostname may also be numeric IP address.
3082          */
3083         strlcpy(buf, display, sizeof(buf));
3084         cp = strchr(buf, ':');
3085         if (!cp) {
3086                 error("Could not find ':' in DISPLAY: %.100s", display);
3087                 return -1;
3088         }
3089         *cp = 0;
3090         /* buf now contains the host name.  But first we parse the display number. */
3091         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3092                 error("Could not parse display number from DISPLAY: %.100s",
3093                     display);
3094                 return -1;
3095         }
3096
3097         /* Look up the host address */
3098         memset(&hints, 0, sizeof(hints));
3099         hints.ai_family = IPv4or6;
3100         hints.ai_socktype = SOCK_STREAM;
3101         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3102         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3103                 error("%.100s: unknown host. (%s)", buf,
3104                 ssh_gai_strerror(gaierr));
3105                 return -1;
3106         }
3107         for (ai = aitop; ai; ai = ai->ai_next) {
3108                 /* Create a socket. */
3109                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3110                 if (sock < 0) {
3111                         debug2("socket: %.100s", strerror(errno));
3112                         continue;
3113                 }
3114                 /* Connect it to the display. */
3115                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3116                         debug2("connect %.100s port %u: %.100s", buf,
3117                             6000 + display_number, strerror(errno));
3118                         close(sock);
3119                         continue;
3120                 }
3121                 /* Success */
3122                 break;
3123         }
3124         freeaddrinfo(aitop);
3125         if (!ai) {
3126                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3127                     strerror(errno));
3128                 return -1;
3129         }
3130         set_nodelay(sock);
3131         return sock;
3132 }
3133
3134 /*
3135  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3136  * the remote channel number.  We should do whatever we want, and respond
3137  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3138  */
3139
3140 /* ARGSUSED */
3141 void
3142 x11_input_open(int type, u_int32_t seq, void *ctxt)
3143 {
3144         Channel *c = NULL;
3145         int remote_id, sock = 0;
3146         char *remote_host;
3147
3148         debug("Received X11 open request.");
3149
3150         remote_id = packet_get_int();
3151
3152         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3153                 remote_host = packet_get_string(NULL);
3154         } else {
3155                 remote_host = xstrdup("unknown (remote did not supply name)");
3156         }
3157         packet_check_eom();
3158
3159         /* Obtain a connection to the real X display. */
3160         sock = x11_connect_display();
3161         if (sock != -1) {
3162                 /* Allocate a channel for this connection. */
3163                 c = channel_new("connected x11 socket",
3164                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3165                     remote_host, 1);
3166                 c->remote_id = remote_id;
3167                 c->force_drain = 1;
3168         }
3169         xfree(remote_host);
3170         if (c == NULL) {
3171                 /* Send refusal to the remote host. */
3172                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3173                 packet_put_int(remote_id);
3174         } else {
3175                 /* Send a confirmation to the remote host. */
3176                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3177                 packet_put_int(remote_id);
3178                 packet_put_int(c->self);
3179         }
3180         packet_send();
3181 }
3182
3183 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3184 /* ARGSUSED */
3185 void
3186 deny_input_open(int type, u_int32_t seq, void *ctxt)
3187 {
3188         int rchan = packet_get_int();
3189
3190         switch (type) {
3191         case SSH_SMSG_AGENT_OPEN:
3192                 error("Warning: ssh server tried agent forwarding.");
3193                 break;
3194         case SSH_SMSG_X11_OPEN:
3195                 error("Warning: ssh server tried X11 forwarding.");
3196                 break;
3197         default:
3198                 error("deny_input_open: type %d", type);
3199                 break;
3200         }
3201         error("Warning: this is probably a break-in attempt by a malicious server.");
3202         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3203         packet_put_int(rchan);
3204         packet_send();
3205 }
3206
3207 /*
3208  * Requests forwarding of X11 connections, generates fake authentication
3209  * data, and enables authentication spoofing.
3210  * This should be called in the client only.
3211  */
3212 void
3213 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3214     const char *proto, const char *data)
3215 {
3216         u_int data_len = (u_int) strlen(data) / 2;
3217         u_int i, value;
3218         char *new_data;
3219         int screen_number;
3220         const char *cp;
3221         u_int32_t rnd = 0;
3222
3223         if (x11_saved_display == NULL)
3224                 x11_saved_display = xstrdup(disp);
3225         else if (strcmp(disp, x11_saved_display) != 0) {
3226                 error("x11_request_forwarding_with_spoofing: different "
3227                     "$DISPLAY already forwarded");
3228                 return;
3229         }
3230
3231         cp = strchr(disp, ':');
3232         if (cp)
3233                 cp = strchr(cp, '.');
3234         if (cp)
3235                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3236         else
3237                 screen_number = 0;
3238
3239         if (x11_saved_proto == NULL) {
3240                 /* Save protocol name. */
3241                 x11_saved_proto = xstrdup(proto);
3242                 /*
3243                  * Extract real authentication data and generate fake data
3244                  * of the same length.
3245                  */
3246                 x11_saved_data = xmalloc(data_len);
3247                 x11_fake_data = xmalloc(data_len);
3248                 for (i = 0; i < data_len; i++) {
3249                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3250                                 fatal("x11_request_forwarding: bad "
3251                                     "authentication data: %.100s", data);
3252                         if (i % 4 == 0)
3253                                 rnd = arc4random();
3254                         x11_saved_data[i] = value;
3255                         x11_fake_data[i] = rnd & 0xff;
3256                         rnd >>= 8;
3257                 }
3258                 x11_saved_data_len = data_len;
3259                 x11_fake_data_len = data_len;
3260         }
3261
3262         /* Convert the fake data into hex. */
3263         new_data = tohex(x11_fake_data, data_len);
3264
3265         /* Send the request packet. */
3266         if (compat20) {
3267                 channel_request_start(client_session_id, "x11-req", 0);
3268                 packet_put_char(0);     /* XXX bool single connection */
3269         } else {
3270                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3271         }
3272         packet_put_cstring(proto);
3273         packet_put_cstring(new_data);
3274         packet_put_int(screen_number);
3275         packet_send();
3276         packet_write_wait();
3277         xfree(new_data);
3278 }
3279
3280
3281 /* -- agent forwarding */
3282
3283 /* Sends a message to the server to request authentication fd forwarding. */
3284
3285 void
3286 auth_request_forwarding(void)
3287 {
3288         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3289         packet_send();
3290         packet_write_wait();
3291 }