openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.266 2006/08/29 10:40:18 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         if(!packet_connection_is_on_socket())
 774             return(131072);
 775         ret = getsockopt(packet_get_connection_in(),
 776                          SOL_SOCKET, SO_RCVBUF, &tcpwinsz, &optsz);
 777         if ((ret == 0) && tcpwinsz > BUFFER_MAX_LEN_HPN)
 778             tcpwinsz = BUFFER_MAX_LEN_HPN;
 779         debug2("tcpwinsz: %d for connection: %d", tcpwinsz,
 780                packet_get_connection_in());
 781         return(tcpwinsz);
 782 }
 783
 784 static void
 785 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 786 {
 787         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 788
 789         /* check buffer limits */
 790         if (!c->tcpwinsz)
 791             c->tcpwinsz = channel_tcpwinsz();
 792         if (c->dynamic_window > 0)
 793             c->tcpwinsz = channel_tcpwinsz();
 794
 795         limit = MIN(limit, 2 * c->tcpwinsz);
 796
 797         if (c->istate == CHAN_INPUT_OPEN &&
 798             limit > 0 &&
 799             buffer_len(&c->input) < limit &&
 800             buffer_check_alloc(&c->input, CHAN_RBUF))
 801                 FD_SET(c->rfd, readset);
 802         if (c->ostate == CHAN_OUTPUT_OPEN ||
 803             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 804                 if (buffer_len(&c->output) > 0) {
 805                         FD_SET(c->wfd, writeset);
 806                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 807                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 808                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 809                                     c->self, c->efd, buffer_len(&c->extended));
 810                         else
 811                                 chan_obuf_empty(c);
 812                 }
 813         }
 814         /** XXX check close conditions, too */
 815         if (compat20 && c->efd != -1) {
 816                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 817                     buffer_len(&c->extended) > 0)
 818                         FD_SET(c->efd, writeset);
 819                 else if (!(c->flags & CHAN_EOF_SENT) &&
 820                     c->extended_usage == CHAN_EXTENDED_READ &&
 821                     buffer_len(&c->extended) < c->remote_window)
 822                         FD_SET(c->efd, readset);
 823         }
 824         /* XXX: What about efd? races? */
 825         if (compat20 && c->ctl_fd != -1 &&
 826             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 827                 FD_SET(c->ctl_fd, readset);
 828 }
 829
 830 /* ARGSUSED */
 831 static void
 832 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 833 {
 834         if (buffer_len(&c->input) == 0) {
 835                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 836                 packet_put_int(c->remote_id);
 837                 packet_send();
 838                 c->type = SSH_CHANNEL_CLOSED;
 839                 debug2("channel %d: closing after input drain.", c->self);
 840         }
 841 }
 842
 843 /* ARGSUSED */
 844 static void
 845 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 846 {
 847         if (buffer_len(&c->output) == 0)
 848                 chan_mark_dead(c);
 849         else
 850                 FD_SET(c->sock, writeset);
 851 }
 852
 853 /*
 854  * This is a special state for X11 authentication spoofing.  An opened X11
 855  * connection (when authentication spoofing is being done) remains in this
 856  * state until the first packet has been completely read.  The authentication
 857  * data in that packet is then substituted by the real data if it matches the
 858  * fake data, and the channel is put into normal mode.
 859  * XXX All this happens at the client side.
 860  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 861  */
 862 static int
 863 x11_open_helper(Buffer *b)
 864 {
 865         u_char *ucp;
 866         u_int proto_len, data_len;
 867
 868         /* Check if the fixed size part of the packet is in buffer. */
 869         if (buffer_len(b) < 12)
 870                 return 0;
 871
 872         /* Parse the lengths of variable-length fields. */
 873         ucp = buffer_ptr(b);
 874         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 875                 proto_len = 256 * ucp[6] + ucp[7];
 876                 data_len = 256 * ucp[8] + ucp[9];
 877         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 878                 proto_len = ucp[6] + 256 * ucp[7];
 879                 data_len = ucp[8] + 256 * ucp[9];
 880         } else {
 881                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 882                     ucp[0]);
 883                 return -1;
 884         }
 885
 886         /* Check if the whole packet is in buffer. */
 887         if (buffer_len(b) <
 888             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 889                 return 0;
 890
 891         /* Check if authentication protocol matches. */
 892         if (proto_len != strlen(x11_saved_proto) ||
 893             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 894                 debug2("X11 connection uses different authentication protocol.");
 895                 return -1;
 896         }
 897         /* Check if authentication data matches our fake data. */
 898         if (data_len != x11_fake_data_len ||
 899             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 900                 x11_fake_data, x11_fake_data_len) != 0) {
 901                 debug2("X11 auth data does not match fake data.");
 902                 return -1;
 903         }
 904         /* Check fake data length */
 905         if (x11_fake_data_len != x11_saved_data_len) {
 906                 error("X11 fake_data_len %d != saved_data_len %d",
 907                     x11_fake_data_len, x11_saved_data_len);
 908                 return -1;
 909         }
 910         /*
 911          * Received authentication protocol and data match
 912          * our fake data. Substitute the fake data with real
 913          * data.
 914          */
 915         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 916             x11_saved_data, x11_saved_data_len);
 917         return 1;
 918 }
 919
 920 static void
 921 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 922 {
 923         int ret = x11_open_helper(&c->output);
 924
 925         if (ret == 1) {
 926                 /* Start normal processing for the channel. */
 927                 c->type = SSH_CHANNEL_OPEN;
 928                 channel_pre_open_13(c, readset, writeset);
 929         } else if (ret == -1) {
 930                 /*
 931                  * We have received an X11 connection that has bad
 932                  * authentication information.
 933                  */
 934                 logit("X11 connection rejected because of wrong authentication.");
 935                 buffer_clear(&c->input);
 936                 buffer_clear(&c->output);
 937                 channel_close_fd(&c->sock);
 938                 c->sock = -1;
 939                 c->type = SSH_CHANNEL_CLOSED;
 940                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 941                 packet_put_int(c->remote_id);
 942                 packet_send();
 943         }
 944 }
 945
 946 static void
 947 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 948 {
 949         int ret = x11_open_helper(&c->output);
 950
 951         /* c->force_drain = 1; */
 952
 953         if (ret == 1) {
 954                 c->type = SSH_CHANNEL_OPEN;
 955                 channel_pre_open(c, readset, writeset);
 956         } else if (ret == -1) {
 957                 logit("X11 connection rejected because of wrong authentication.");
 958                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 959                 chan_read_failed(c);
 960                 buffer_clear(&c->input);
 961                 chan_ibuf_empty(c);
 962                 buffer_clear(&c->output);
 963                 /* for proto v1, the peer will send an IEOF */
 964                 if (compat20)
 965                         chan_write_failed(c);
 966                 else
 967                         c->type = SSH_CHANNEL_OPEN;
 968                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 969         }
 970 }
 971
 972 /* try to decode a socks4 header */
 973 /* ARGSUSED */
 974 static int
 975 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 976 {
 977         char *p, *host;
 978         u_int len, have, i, found;
 979         char username[256];
 980         struct {
 981                 u_int8_t version;
 982                 u_int8_t command;
 983                 u_int16_t dest_port;
 984                 struct in_addr dest_addr;
 985         } s4_req, s4_rsp;
 986
 987         debug2("channel %d: decode socks4", c->self);
 988
 989         have = buffer_len(&c->input);
 990         len = sizeof(s4_req);
 991         if (have < len)
 992                 return 0;
 993         p = buffer_ptr(&c->input);
 994         for (found = 0, i = len; i < have; i++) {
 995                 if (p[i] == '\0') {
 996                         found = 1;
 997                         break;
 998                 }
 999                 if (i > 1024) {
1000                         /* the peer is probably sending garbage */
1001                         debug("channel %d: decode socks4: too long",
1002                             c->self);
1003                         return -1;
1004                 }
1005         }
1006         if (!found)
1007                 return 0;
1008         buffer_get(&c->input, (char *)&s4_req.version, 1);
1009         buffer_get(&c->input, (char *)&s4_req.command, 1);
1010         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1011         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1012         have = buffer_len(&c->input);
1013         p = buffer_ptr(&c->input);
1014         len = strlen(p);
1015         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1016         if (len > have)
1017                 fatal("channel %d: decode socks4: len %d > have %d",
1018                     c->self, len, have);
1019         strlcpy(username, p, sizeof(username));
1020         buffer_consume(&c->input, len);
1021         buffer_consume(&c->input, 1);           /* trailing '\0' */
1022
1023         host = inet_ntoa(s4_req.dest_addr);
1024         strlcpy(c->path, host, sizeof(c->path));
1025         c->host_port = ntohs(s4_req.dest_port);
1026
1027         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1028             c->self, host, c->host_port, s4_req.command);
1029
1030         if (s4_req.command != 1) {
1031                 debug("channel %d: cannot handle: socks4 cn %d",
1032                     c->self, s4_req.command);
1033                 return -1;
1034         }
1035         s4_rsp.version = 0;                     /* vn: 0 for reply */
1036         s4_rsp.command = 90;                    /* cd: req granted */
1037         s4_rsp.dest_port = 0;                   /* ignored */
1038         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1039         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1040         return 1;
1041 }
1042
1043 /* try to decode a socks5 header */
1044 #define SSH_SOCKS5_AUTHDONE     0x1000
1045 #define SSH_SOCKS5_NOAUTH       0x00
1046 #define SSH_SOCKS5_IPV4         0x01
1047 #define SSH_SOCKS5_DOMAIN       0x03
1048 #define SSH_SOCKS5_IPV6         0x04
1049 #define SSH_SOCKS5_CONNECT      0x01
1050 #define SSH_SOCKS5_SUCCESS      0x00
1051
1052 /* ARGSUSED */
1053 static int
1054 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1055 {
1056         struct {
1057                 u_int8_t version;
1058                 u_int8_t command;
1059                 u_int8_t reserved;
1060                 u_int8_t atyp;
1061         } s5_req, s5_rsp;
1062         u_int16_t dest_port;
1063         u_char *p, dest_addr[255+1];
1064         u_int have, need, i, found, nmethods, addrlen, af;
1065
1066         debug2("channel %d: decode socks5", c->self);
1067         p = buffer_ptr(&c->input);
1068         if (p[0] != 0x05)
1069                 return -1;
1070         have = buffer_len(&c->input);
1071         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1072                 /* format: ver | nmethods | methods */
1073                 if (have < 2)
1074                         return 0;
1075                 nmethods = p[1];
1076                 if (have < nmethods + 2)
1077                         return 0;
1078                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1079                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1080                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1081                                 found = 1;
1082                                 break;
1083                         }
1084                 }
1085                 if (!found) {
1086                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1087                             c->self);
1088                         return -1;
1089                 }
1090                 buffer_consume(&c->input, nmethods + 2);
1091                 buffer_put_char(&c->output, 0x05);              /* version */
1092                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1093                 FD_SET(c->sock, writeset);
1094                 c->flags |= SSH_SOCKS5_AUTHDONE;
1095                 debug2("channel %d: socks5 auth done", c->self);
1096                 return 0;                               /* need more */
1097         }
1098         debug2("channel %d: socks5 post auth", c->self);
1099         if (have < sizeof(s5_req)+1)
1100                 return 0;                       /* need more */
1101         memcpy(&s5_req, p, sizeof(s5_req));
1102         if (s5_req.version != 0x05 ||
1103             s5_req.command != SSH_SOCKS5_CONNECT ||
1104             s5_req.reserved != 0x00) {
1105                 debug2("channel %d: only socks5 connect supported", c->self);
1106                 return -1;
1107         }
1108         switch (s5_req.atyp){
1109         case SSH_SOCKS5_IPV4:
1110                 addrlen = 4;
1111                 af = AF_INET;
1112                 break;
1113         case SSH_SOCKS5_DOMAIN:
1114                 addrlen = p[sizeof(s5_req)];
1115                 af = -1;
1116                 break;
1117         case SSH_SOCKS5_IPV6:
1118                 addrlen = 16;
1119                 af = AF_INET6;
1120                 break;
1121         default:
1122                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1123                 return -1;
1124         }
1125         need = sizeof(s5_req) + addrlen + 2;
1126         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1127                 need++;
1128         if (have < need)
1129                 return 0;
1130         buffer_consume(&c->input, sizeof(s5_req));
1131         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1132                 buffer_consume(&c->input, 1);    /* host string length */
1133         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1134         buffer_get(&c->input, (char *)&dest_port, 2);
1135         dest_addr[addrlen] = '\0';
1136         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1137                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1138         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1139                 return -1;
1140         c->host_port = ntohs(dest_port);
1141
1142         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1143             c->self, c->path, c->host_port, s5_req.command);
1144
1145         s5_rsp.version = 0x05;
1146         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1147         s5_rsp.reserved = 0;                    /* ignored */
1148         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1149         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1150         dest_port = 0;                          /* ignored */
1151
1152         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1153         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1154         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1155         return 1;
1156 }
1157
1158 /* dynamic port forwarding */
1159 static void
1160 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1161 {
1162         u_char *p;
1163         u_int have;
1164         int ret;
1165
1166         have = buffer_len(&c->input);
1167         c->delayed = 0;
1168         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1169         /* buffer_dump(&c->input); */
1170         /* check if the fixed size part of the packet is in buffer. */
1171         if (have < 3) {
1172                 /* need more */
1173                 FD_SET(c->sock, readset);
1174                 return;
1175         }
1176         /* try to guess the protocol */
1177         p = buffer_ptr(&c->input);
1178         switch (p[0]) {
1179         case 0x04:
1180                 ret = channel_decode_socks4(c, readset, writeset);
1181                 break;
1182         case 0x05:
1183                 ret = channel_decode_socks5(c, readset, writeset);
1184                 break;
1185         default:
1186                 ret = -1;
1187                 break;
1188         }
1189         if (ret < 0) {
1190                 chan_mark_dead(c);
1191         } else if (ret == 0) {
1192                 debug2("channel %d: pre_dynamic: need more", c->self);
1193                 /* need more */
1194                 FD_SET(c->sock, readset);
1195         } else {
1196                 /* switch to the next state */
1197                 c->type = SSH_CHANNEL_OPENING;
1198                 port_open_helper(c, "direct-tcpip");
1199         }
1200 }
1201
1202 /* This is our fake X11 server socket. */
1203 /* ARGSUSED */
1204 static void
1205 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1206 {
1207         Channel *nc;
1208         struct sockaddr addr;
1209         int newsock;
1210         socklen_t addrlen;
1211         char buf[16384], *remote_ipaddr;
1212         int remote_port;
1213
1214         if (FD_ISSET(c->sock, readset)) {
1215                 debug("X11 connection requested.");
1216                 addrlen = sizeof(addr);
1217                 newsock = accept(c->sock, &addr, &addrlen);
1218                 if (c->single_connection) {
1219                         debug2("single_connection: closing X11 listener.");
1220                         channel_close_fd(&c->sock);
1221                         chan_mark_dead(c);
1222                 }
1223                 if (newsock < 0) {
1224                         error("accept: %.100s", strerror(errno));
1225                         return;
1226                 }
1227                 set_nodelay(newsock);
1228                 remote_ipaddr = get_peer_ipaddr(newsock);
1229                 remote_port = get_peer_port(newsock);
1230                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1231                     remote_ipaddr, remote_port);
1232
1233                 nc = channel_new("accepted x11 socket",
1234                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1235                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1236                 if (compat20) {
1237                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1238                         packet_put_cstring("x11");
1239                         packet_put_int(nc->self);
1240                         packet_put_int(nc->local_window_max);
1241                         packet_put_int(nc->local_maxpacket);
1242                         /* originator ipaddr and port */
1243                         packet_put_cstring(remote_ipaddr);
1244                         if (datafellows & SSH_BUG_X11FWD) {
1245                                 debug2("ssh2 x11 bug compat mode");
1246                         } else {
1247                                 packet_put_int(remote_port);
1248                         }
1249                         packet_send();
1250                 } else {
1251                         packet_start(SSH_SMSG_X11_OPEN);
1252                         packet_put_int(nc->self);
1253                         if (packet_get_protocol_flags() &
1254                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1255                                 packet_put_cstring(buf);
1256                         packet_send();
1257                 }
1258                 xfree(remote_ipaddr);
1259         }
1260 }
1261
1262 static void
1263 port_open_helper(Channel *c, char *rtype)
1264 {
1265         int direct;
1266         char buf[1024];
1267         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1268         int remote_port = get_peer_port(c->sock);
1269
1270         direct = (strcmp(rtype, "direct-tcpip") == 0);
1271
1272         snprintf(buf, sizeof buf,
1273             "%s: listening port %d for %.100s port %d, "
1274             "connect from %.200s port %d",
1275             rtype, c->listening_port, c->path, c->host_port,
1276             remote_ipaddr, remote_port);
1277
1278         xfree(c->remote_name);
1279         c->remote_name = xstrdup(buf);
1280
1281         if (compat20) {
1282                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1283                 packet_put_cstring(rtype);
1284                 packet_put_int(c->self);
1285                 packet_put_int(c->local_window_max);
1286                 packet_put_int(c->local_maxpacket);
1287                 if (direct) {
1288                         /* target host, port */
1289                         packet_put_cstring(c->path);
1290                         packet_put_int(c->host_port);
1291                 } else {
1292                         /* listen address, port */
1293                         packet_put_cstring(c->path);
1294                         packet_put_int(c->listening_port);
1295                 }
1296                 /* originator host and port */
1297                 packet_put_cstring(remote_ipaddr);
1298                 packet_put_int((u_int)remote_port);
1299                 packet_send();
1300         } else {
1301                 packet_start(SSH_MSG_PORT_OPEN);
1302                 packet_put_int(c->self);
1303                 packet_put_cstring(c->path);
1304                 packet_put_int(c->host_port);
1305                 if (packet_get_protocol_flags() &
1306                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1307                         packet_put_cstring(c->remote_name);
1308                 packet_send();
1309         }
1310         xfree(remote_ipaddr);
1311 }
1312
1313 static void
1314 channel_set_reuseaddr(int fd)
1315 {
1316         int on = 1;
1317
1318         /*
1319          * Set socket options.
1320          * Allow local port reuse in TIME_WAIT.
1321          */
1322         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1323                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1324 }
1325
1326 /*
1327  * This socket is listening for connections to a forwarded TCP/IP port.
1328  */
1329 /* ARGSUSED */
1330 static void
1331 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1332 {
1333         Channel *nc;
1334         struct sockaddr addr;
1335         int newsock, nextstate;
1336         socklen_t addrlen;
1337         char *rtype;
1338
1339         if (FD_ISSET(c->sock, readset)) {
1340                 debug("Connection to port %d forwarding "
1341                     "to %.100s port %d requested.",
1342                     c->listening_port, c->path, c->host_port);
1343
1344                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1345                         nextstate = SSH_CHANNEL_OPENING;
1346                         rtype = "forwarded-tcpip";
1347                 } else {
1348                         if (c->host_port == 0) {
1349                                 nextstate = SSH_CHANNEL_DYNAMIC;
1350                                 rtype = "dynamic-tcpip";
1351                         } else {
1352                                 nextstate = SSH_CHANNEL_OPENING;
1353                                 rtype = "direct-tcpip";
1354                         }
1355                 }
1356
1357                 addrlen = sizeof(addr);
1358                 newsock = accept(c->sock, &addr, &addrlen);
1359                 if (newsock < 0) {
1360                         error("accept: %.100s", strerror(errno));
1361                         return;
1362                 }
1363                 set_nodelay(newsock);
1364                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1365                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1366                 nc->listening_port = c->listening_port;
1367                 nc->host_port = c->host_port;
1368                 strlcpy(nc->path, c->path, sizeof(nc->path));
1369
1370                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1371                         /*
1372                          * do not call the channel_post handler until
1373                          * this flag has been reset by a pre-handler.
1374                          * otherwise the FD_ISSET calls might overflow
1375                          */
1376                         nc->delayed = 1;
1377                 } else {
1378                         port_open_helper(nc, rtype);
1379                 }
1380         }
1381 }
1382
1383 /*
1384  * This is the authentication agent socket listening for connections from
1385  * clients.
1386  */
1387 /* ARGSUSED */
1388 static void
1389 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1390 {
1391         Channel *nc;
1392         int newsock;
1393         struct sockaddr addr;
1394         socklen_t addrlen;
1395
1396         if (FD_ISSET(c->sock, readset)) {
1397                 addrlen = sizeof(addr);
1398                 newsock = accept(c->sock, &addr, &addrlen);
1399                 if (newsock < 0) {
1400                         error("accept from auth socket: %.100s", strerror(errno));
1401                         return;
1402                 }
1403                 nc = channel_new("accepted auth socket",
1404                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1405                     c->local_window_max, c->local_maxpacket,
1406                     0, "accepted auth socket", 1);
1407                 if (compat20) {
1408                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1409                         packet_put_cstring("auth-agent@openssh.com");
1410                         packet_put_int(nc->self);
1411                         packet_put_int(c->local_window_max);
1412                         packet_put_int(c->local_maxpacket);
1413                 } else {
1414                         packet_start(SSH_SMSG_AGENT_OPEN);
1415                         packet_put_int(nc->self);
1416                 }
1417                 packet_send();
1418         }
1419 }
1420
1421 /* ARGSUSED */
1422 static void
1423 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1424 {
1425         int err = 0;
1426         socklen_t sz = sizeof(err);
1427
1428         if (FD_ISSET(c->sock, writeset)) {
1429                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1430                         err = errno;
1431                         error("getsockopt SO_ERROR failed");
1432                 }
1433                 if (err == 0) {
1434                         debug("channel %d: connected", c->self);
1435                         c->type = SSH_CHANNEL_OPEN;
1436                         if (compat20) {
1437                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1438                                 packet_put_int(c->remote_id);
1439                                 packet_put_int(c->self);
1440                                 packet_put_int(c->local_window);
1441                                 packet_put_int(c->local_maxpacket);
1442                         } else {
1443                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1444                                 packet_put_int(c->remote_id);
1445                                 packet_put_int(c->self);
1446                         }
1447                 } else {
1448                         debug("channel %d: not connected: %s",
1449                             c->self, strerror(err));
1450                         if (compat20) {
1451                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1452                                 packet_put_int(c->remote_id);
1453                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1454                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1455                                         packet_put_cstring(strerror(err));
1456                                         packet_put_cstring("");
1457                                 }
1458                         } else {
1459                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1460                                 packet_put_int(c->remote_id);
1461                         }
1462                         chan_mark_dead(c);
1463                 }
1464                 packet_send();
1465         }
1466 }
1467
1468 /* ARGSUSED */
1469 static int
1470 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1471 {
1472         char buf[CHAN_RBUF];
1473         int len;
1474
1475         if (c->rfd != -1 &&
1476             FD_ISSET(c->rfd, readset)) {
1477                 errno = 0;
1478                 len = read(c->rfd, buf, sizeof(buf));
1479                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1480                         return 1;
1481 #ifndef PTY_ZEROREAD
1482                 if (len <= 0) {
1483 #else
1484                 if ((!c->isatty && len <= 0) ||
1485                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1486 #endif
1487                         debug2("channel %d: read<=0 rfd %d len %d",
1488                             c->self, c->rfd, len);
1489                         if (c->type != SSH_CHANNEL_OPEN) {
1490                                 debug2("channel %d: not open", c->self);
1491                                 chan_mark_dead(c);
1492                                 return -1;
1493                         } else if (compat13) {
1494                                 buffer_clear(&c->output);
1495                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1496                                 debug2("channel %d: input draining.", c->self);
1497                         } else {
1498                                 chan_read_failed(c);
1499                         }
1500                         return -1;
1501                 }
1502                 if (c->input_filter != NULL) {
1503                         if (c->input_filter(c, buf, len) == -1) {
1504                                 debug2("channel %d: filter stops", c->self);
1505                                 chan_read_failed(c);
1506                         }
1507                 } else if (c->datagram) {
1508                         buffer_put_string(&c->input, buf, len);
1509                 } else {
1510                         buffer_append(&c->input, buf, len);
1511                 }
1512         }
1513         return 1;
1514 }
1515
1516 /* ARGSUSED */
1517 static int
1518 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1519 {
1520         struct termios tio;
1521         u_char *data = NULL, *buf;
1522         u_int dlen;
1523         int len;
1524
1525         /* Send buffered output data to the socket. */
1526         if (c->wfd != -1 &&
1527             FD_ISSET(c->wfd, writeset) &&
1528             buffer_len(&c->output) > 0) {
1529                 if (c->output_filter != NULL) {
1530                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1531                                 debug2("channel %d: filter stops", c->self);
1532                                 if (c->type != SSH_CHANNEL_OPEN)
1533                                         chan_mark_dead(c);
1534                                 else
1535                                         chan_write_failed(c);
1536                                 return -1;
1537                         }
1538                 } else if (c->datagram) {
1539                         buf = data = buffer_get_string(&c->output, &dlen);
1540                 } else {
1541                         buf = data = buffer_ptr(&c->output);
1542                         dlen = buffer_len(&c->output);
1543                 }
1544
1545                 if (c->datagram) {
1546                         /* ignore truncated writes, datagrams might get lost */
1547                         c->local_consumed += dlen + 4;
1548                         len = write(c->wfd, buf, dlen);
1549                         xfree(data);
1550                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1551                                 return 1;
1552                         if (len <= 0) {
1553                                 if (c->type != SSH_CHANNEL_OPEN)
1554                                         chan_mark_dead(c);
1555                                 else
1556                                         chan_write_failed(c);
1557                                 return -1;
1558                         }
1559                         return 1;
1560                 }
1561 #ifdef _AIX
1562                 /* XXX: Later AIX versions can't push as much data to tty */
1563                 if (compat20 && c->wfd_isatty)
1564                         dlen = MIN(dlen, 8*1024);
1565 #endif
1566
1567                 len = write(c->wfd, buf, dlen);
1568                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1569                         return 1;
1570                 if (len <= 0) {
1571                         if (c->type != SSH_CHANNEL_OPEN) {
1572                                 debug2("channel %d: not open", c->self);
1573                                 chan_mark_dead(c);
1574                                 return -1;
1575                         } else if (compat13) {
1576                                 buffer_clear(&c->output);
1577                                 debug2("channel %d: input draining.", c->self);
1578                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1579                         } else {
1580                                 chan_write_failed(c);
1581                         }
1582                         return -1;
1583                 }
1584                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1585                         if (tcgetattr(c->wfd, &tio) == 0 &&
1586                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1587                                 /*
1588                                  * Simulate echo to reduce the impact of
1589                                  * traffic analysis. We need to match the
1590                                  * size of a SSH2_MSG_CHANNEL_DATA message
1591                                  * (4 byte channel id + buf)
1592                                  */
1593                                 packet_send_ignore(4 + len);
1594                                 packet_send();
1595                         }
1596                 }
1597                 buffer_consume(&c->output, len);
1598                 if (compat20 && len > 0) {
1599                         c->local_consumed += len;
1600                 }
1601         }
1602         return 1;
1603 }
1604
1605 static int
1606 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1607 {
1608         char buf[CHAN_RBUF];
1609         int len;
1610
1611 /** XXX handle drain efd, too */
1612         if (c->efd != -1) {
1613                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1614                     FD_ISSET(c->efd, writeset) &&
1615                     buffer_len(&c->extended) > 0) {
1616                         len = write(c->efd, buffer_ptr(&c->extended),
1617                             buffer_len(&c->extended));
1618                         debug2("channel %d: written %d to efd %d",
1619                             c->self, len, c->efd);
1620                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1621                                 return 1;
1622                         if (len <= 0) {
1623                                 debug2("channel %d: closing write-efd %d",
1624                                     c->self, c->efd);
1625                                 channel_close_fd(&c->efd);
1626                         } else {
1627                                 buffer_consume(&c->extended, len);
1628                                 c->local_consumed += len;
1629                         }
1630                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1631                     FD_ISSET(c->efd, readset)) {
1632                         len = read(c->efd, buf, sizeof(buf));
1633                         debug2("channel %d: read %d from efd %d",
1634                             c->self, len, c->efd);
1635                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1636                                 return 1;
1637                         if (len <= 0) {
1638                                 debug2("channel %d: closing read-efd %d",
1639                                     c->self, c->efd);
1640                                 channel_close_fd(&c->efd);
1641                         } else {
1642                                 buffer_append(&c->extended, buf, len);
1643                         }
1644                 }
1645         }
1646         return 1;
1647 }
1648
1649 /* ARGSUSED */
1650 static int
1651 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1652 {
1653         char buf[16];
1654         int len;
1655
1656         /* Monitor control fd to detect if the slave client exits */
1657         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1658                 len = read(c->ctl_fd, buf, sizeof(buf));
1659                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1660                         return 1;
1661                 if (len <= 0) {
1662                         debug2("channel %d: ctl read<=0", c->self);
1663                         if (c->type != SSH_CHANNEL_OPEN) {
1664                                 debug2("channel %d: not open", c->self);
1665                                 chan_mark_dead(c);
1666                                 return -1;
1667                         } else {
1668                                 chan_read_failed(c);
1669                                 chan_write_failed(c);
1670                         }
1671                         return -1;
1672                 } else
1673                         fatal("%s: unexpected data on ctl fd", __func__);
1674         }
1675         return 1;
1676 }
1677
1678 static int
1679 channel_check_window(Channel *c)
1680 {
1681         if (c->type == SSH_CHANNEL_OPEN &&
1682             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1683             c->local_window < c->local_window_max/2 &&
1684             c->local_consumed > 0) {
1685                 u_int addition = 0;
1686                 /* adjust max window size if we are in a dynamic environment */
1687                 if (c->dynamic_window && (c->tcpwinsz > c->local_window_max)) {
1688                         addition = c->tcpwinsz - c->local_window_max;
1689                         c->local_window_max += addition;
1690                 }
1691                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1692                 packet_put_int(c->remote_id);
1693                 packet_put_int(c->local_consumed + addition);
1694                 packet_send();
1695                 debug2("channel %d: window %d sent adjust %d",
1696                     c->self, c->local_window,
1697                     c->local_consumed);
1698                 c->local_window += c->local_consumed + addition;
1699                 c->local_consumed = 0;
1700         }
1701         return 1;
1702 }
1703
1704 static void
1705 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1706 {
1707         if (c->delayed)
1708                 return;
1709         channel_handle_rfd(c, readset, writeset);
1710         channel_handle_wfd(c, readset, writeset);
1711         if (!compat20)
1712                 return;
1713         channel_handle_efd(c, readset, writeset);
1714         channel_handle_ctl(c, readset, writeset);
1715         channel_check_window(c);
1716 }
1717
1718 /* ARGSUSED */
1719 static void
1720 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1721 {
1722         int len;
1723
1724         /* Send buffered output data to the socket. */
1725         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1726                 len = write(c->sock, buffer_ptr(&c->output),
1727                             buffer_len(&c->output));
1728                 if (len <= 0)
1729                         buffer_clear(&c->output);
1730                 else
1731                         buffer_consume(&c->output, len);
1732         }
1733 }
1734
1735 static void
1736 channel_handler_init_20(void)
1737 {
1738         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1739         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1740         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1741         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1742         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1743         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1744         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1745         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1746
1747         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1748         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1749         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1750         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1751         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1752         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1753         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1754 }
1755
1756 static void
1757 channel_handler_init_13(void)
1758 {
1759         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1760         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1761         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1762         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1763         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1764         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1765         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1766         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1767         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1768
1769         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1770         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1771         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1772         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1773         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1774         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1775         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1776 }
1777
1778 static void
1779 channel_handler_init_15(void)
1780 {
1781         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1782         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1783         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1784         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1785         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1786         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1787         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1788
1789         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1790         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1791         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1792         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1793         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1794         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1795 }
1796
1797 static void
1798 channel_handler_init(void)
1799 {
1800         int i;
1801
1802         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1803                 channel_pre[i] = NULL;
1804                 channel_post[i] = NULL;
1805         }
1806         if (compat20)
1807                 channel_handler_init_20();
1808         else if (compat13)
1809                 channel_handler_init_13();
1810         else
1811                 channel_handler_init_15();
1812 }
1813
1814 /* gc dead channels */
1815 static void
1816 channel_garbage_collect(Channel *c)
1817 {
1818         if (c == NULL)
1819                 return;
1820         if (c->detach_user != NULL) {
1821                 if (!chan_is_dead(c, c->detach_close))
1822                         return;
1823                 debug2("channel %d: gc: notify user", c->self);
1824                 c->detach_user(c->self, NULL);
1825                 /* if we still have a callback */
1826                 if (c->detach_user != NULL)
1827                         return;
1828                 debug2("channel %d: gc: user detached", c->self);
1829         }
1830         if (!chan_is_dead(c, 1))
1831                 return;
1832         debug2("channel %d: garbage collecting", c->self);
1833         channel_free(c);
1834 }
1835
1836 static void
1837 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1838 {
1839         static int did_init = 0;
1840         u_int i;
1841         Channel *c;
1842
1843         if (!did_init) {
1844                 channel_handler_init();
1845                 did_init = 1;
1846         }
1847         for (i = 0; i < channels_alloc; i++) {
1848                 c = channels[i];
1849                 if (c == NULL)
1850                         continue;
1851                 if (ftab[c->type] != NULL)
1852                         (*ftab[c->type])(c, readset, writeset);
1853                 channel_garbage_collect(c);
1854         }
1855 }
1856
1857 /*
1858  * Allocate/update select bitmasks and add any bits relevant to channels in
1859  * select bitmasks.
1860  */
1861 void
1862 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1863     u_int *nallocp, int rekeying)
1864 {
1865         u_int n, sz, nfdset;
1866
1867         n = MAX(*maxfdp, channel_max_fd);
1868
1869         nfdset = howmany(n+1, NFDBITS);
1870         /* Explicitly test here, because xrealloc isn't always called */
1871         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1872                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1873         sz = nfdset * sizeof(fd_mask);
1874
1875         /* perhaps check sz < nalloc/2 and shrink? */
1876         if (*readsetp == NULL || sz > *nallocp) {
1877                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1878                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1879                 *nallocp = sz;
1880         }
1881         *maxfdp = n;
1882         memset(*readsetp, 0, sz);
1883         memset(*writesetp, 0, sz);
1884
1885         if (!rekeying)
1886                 channel_handler(channel_pre, *readsetp, *writesetp);
1887 }
1888
1889 /*
1890  * After select, perform any appropriate operations for channels which have
1891  * events pending.
1892  */
1893 void
1894 channel_after_select(fd_set *readset, fd_set *writeset)
1895 {
1896         channel_handler(channel_post, readset, writeset);
1897 }
1898
1899
1900 /* If there is data to send to the connection, enqueue some of it now. */
1901 void
1902 channel_output_poll(void)
1903 {
1904         Channel *c;
1905         u_int i, len;
1906
1907         for (i = 0; i < channels_alloc; i++) {
1908                 c = channels[i];
1909                 if (c == NULL)
1910                         continue;
1911
1912                 /*
1913                  * We are only interested in channels that can have buffered
1914                  * incoming data.
1915                  */
1916                 if (compat13) {
1917                         if (c->type != SSH_CHANNEL_OPEN &&
1918                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1919                                 continue;
1920                 } else {
1921                         if (c->type != SSH_CHANNEL_OPEN)
1922                                 continue;
1923                 }
1924                 if (compat20 &&
1925                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1926                         /* XXX is this true? */
1927                         debug3("channel %d: will not send data after close", c->self);
1928                         continue;
1929                 }
1930
1931                 /* Get the amount of buffered data for this channel. */
1932                 if ((c->istate == CHAN_INPUT_OPEN ||
1933                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1934                     (len = buffer_len(&c->input)) > 0) {
1935                         if (c->datagram) {
1936                                 if (len > 0) {
1937                                         u_char *data;
1938                                         u_int dlen;
1939
1940                                         data = buffer_get_string(&c->input,
1941                                             &dlen);
1942                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1943                                         packet_put_int(c->remote_id);
1944                                         packet_put_string(data, dlen);
1945                                         packet_send();
1946                                         c->remote_window -= dlen + 4;
1947                                         xfree(data);
1948                                 }
1949                                 continue;
1950                         }
1951                         /*
1952                          * Send some data for the other side over the secure
1953                          * connection.
1954                          */
1955                         if (compat20) {
1956                                 if (len > c->remote_window)
1957                                         len = c->remote_window;
1958                                 if (len > c->remote_maxpacket)
1959                                         len = c->remote_maxpacket;
1960                         } else {
1961                                 if (packet_is_interactive()) {
1962                                         if (len > 1024)
1963                                                 len = 512;
1964                                 } else {
1965                                         /* Keep the packets at reasonable size. */
1966                                         if (len > packet_get_maxsize()/2)
1967                                                 len = packet_get_maxsize()/2;
1968                                 }
1969                         }
1970                         if (len > 0) {
1971                                 packet_start(compat20 ?
1972                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1973                                 packet_put_int(c->remote_id);
1974                                 packet_put_string(buffer_ptr(&c->input), len);
1975                                 packet_send();
1976                                 buffer_consume(&c->input, len);
1977                                 c->remote_window -= len;
1978                         }
1979                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1980                         if (compat13)
1981                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1982                         /*
1983                          * input-buffer is empty and read-socket shutdown:
1984                          * tell peer, that we will not send more data: send IEOF.
1985                          * hack for extended data: delay EOF if EFD still in use.
1986                          */
1987                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1988                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1989                                     c->self, c->efd, buffer_len(&c->extended));
1990                         else
1991                                 chan_ibuf_empty(c);
1992                 }
1993                 /* Send extended data, i.e. stderr */
1994                 if (compat20 &&
1995                     !(c->flags & CHAN_EOF_SENT) &&
1996                     c->remote_window > 0 &&
1997                     (len = buffer_len(&c->extended)) > 0 &&
1998                     c->extended_usage == CHAN_EXTENDED_READ) {
1999                         debug2("channel %d: rwin %u elen %u euse %d",
2000                             c->self, c->remote_window, buffer_len(&c->extended),
2001                             c->extended_usage);
2002                         if (len > c->remote_window)
2003                                 len = c->remote_window;
2004                         if (len > c->remote_maxpacket)
2005                                 len = c->remote_maxpacket;
2006                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2007                         packet_put_int(c->remote_id);
2008                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2009                         packet_put_string(buffer_ptr(&c->extended), len);
2010                         packet_send();
2011                         buffer_consume(&c->extended, len);
2012                         c->remote_window -= len;
2013                         debug2("channel %d: sent ext data %d", c->self, len);
2014                 }
2015         }
2016 }
2017
2018
2019 /* -- protocol input */
2020
2021 /* ARGSUSED */
2022 void
2023 channel_input_data(int type, u_int32_t seq, void *ctxt)
2024 {
2025         int id;
2026         char *data;
2027         u_int data_len;
2028         Channel *c;
2029
2030         /* Get the channel number and verify it. */
2031         id = packet_get_int();
2032         c = channel_lookup(id);
2033         if (c == NULL)
2034                 packet_disconnect("Received data for nonexistent channel %d.", id);
2035
2036         /* Ignore any data for non-open channels (might happen on close) */
2037         if (c->type != SSH_CHANNEL_OPEN &&
2038             c->type != SSH_CHANNEL_X11_OPEN)
2039                 return;
2040
2041         /* Get the data. */
2042         data = packet_get_string(&data_len);
2043
2044         /*
2045          * Ignore data for protocol > 1.3 if output end is no longer open.
2046          * For protocol 2 the sending side is reducing its window as it sends
2047          * data, so we must 'fake' consumption of the data in order to ensure
2048          * that window updates are sent back.  Otherwise the connection might
2049          * deadlock.
2050          */
2051         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2052                 if (compat20) {
2053                         c->local_window -= data_len;
2054                         c->local_consumed += data_len;
2055                 }
2056                 xfree(data);
2057                 return;
2058         }
2059
2060         if (compat20) {
2061                 if (data_len > c->local_maxpacket) {
2062                         logit("channel %d: rcvd big packet %d, maxpack %d",
2063                             c->self, data_len, c->local_maxpacket);
2064                 }
2065                 if (data_len > c->local_window) {
2066                         logit("channel %d: rcvd too much data %d, win %d",
2067                             c->self, data_len, c->local_window);
2068                         xfree(data);
2069                         return;
2070                 }
2071                 c->local_window -= data_len;
2072         }
2073         packet_check_eom();
2074         if (c->datagram)
2075                 buffer_put_string(&c->output, data, data_len);
2076         else
2077                 buffer_append(&c->output, data, data_len);
2078         xfree(data);
2079 }
2080
2081 /* ARGSUSED */
2082 void
2083 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2084 {
2085         int id;
2086         char *data;
2087         u_int data_len, tcode;
2088         Channel *c;
2089
2090         /* Get the channel number and verify it. */
2091         id = packet_get_int();
2092         c = channel_lookup(id);
2093
2094         if (c == NULL)
2095                 packet_disconnect("Received extended_data for bad channel %d.", id);
2096         if (c->type != SSH_CHANNEL_OPEN) {
2097                 logit("channel %d: ext data for non open", id);
2098                 return;
2099         }
2100         if (c->flags & CHAN_EOF_RCVD) {
2101                 if (datafellows & SSH_BUG_EXTEOF)
2102                         debug("channel %d: accepting ext data after eof", id);
2103                 else
2104                         packet_disconnect("Received extended_data after EOF "
2105                             "on channel %d.", id);
2106         }
2107         tcode = packet_get_int();
2108         if (c->efd == -1 ||
2109             c->extended_usage != CHAN_EXTENDED_WRITE ||
2110             tcode != SSH2_EXTENDED_DATA_STDERR) {
2111                 logit("channel %d: bad ext data", c->self);
2112                 return;
2113         }
2114         data = packet_get_string(&data_len);
2115         packet_check_eom();
2116         if (data_len > c->local_window) {
2117                 logit("channel %d: rcvd too much extended_data %d, win %d",
2118                     c->self, data_len, c->local_window);
2119                 xfree(data);
2120                 return;
2121         }
2122         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2123         c->local_window -= data_len;
2124         buffer_append(&c->extended, data, data_len);
2125         xfree(data);
2126 }
2127
2128 /* ARGSUSED */
2129 void
2130 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2131 {
2132         int id;
2133         Channel *c;
2134
2135         id = packet_get_int();
2136         packet_check_eom();
2137         c = channel_lookup(id);
2138         if (c == NULL)
2139                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2140         chan_rcvd_ieof(c);
2141
2142         /* XXX force input close */
2143         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2144                 debug("channel %d: FORCE input drain", c->self);
2145                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2146                 if (buffer_len(&c->input) == 0)
2147                         chan_ibuf_empty(c);
2148         }
2149
2150 }
2151
2152 /* ARGSUSED */
2153 void
2154 channel_input_close(int type, u_int32_t seq, void *ctxt)
2155 {
2156         int id;
2157         Channel *c;
2158
2159         id = packet_get_int();
2160         packet_check_eom();
2161         c = channel_lookup(id);
2162         if (c == NULL)
2163                 packet_disconnect("Received close for nonexistent channel %d.", id);
2164
2165         /*
2166          * Send a confirmation that we have closed the channel and no more
2167          * data is coming for it.
2168          */
2169         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2170         packet_put_int(c->remote_id);
2171         packet_send();
2172
2173         /*
2174          * If the channel is in closed state, we have sent a close request,
2175          * and the other side will eventually respond with a confirmation.
2176          * Thus, we cannot free the channel here, because then there would be
2177          * no-one to receive the confirmation.  The channel gets freed when
2178          * the confirmation arrives.
2179          */
2180         if (c->type != SSH_CHANNEL_CLOSED) {
2181                 /*
2182                  * Not a closed channel - mark it as draining, which will
2183                  * cause it to be freed later.
2184                  */
2185                 buffer_clear(&c->input);
2186                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2187         }
2188 }
2189
2190 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2191 /* ARGSUSED */
2192 void
2193 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2194 {
2195         int id = packet_get_int();
2196         Channel *c = channel_lookup(id);
2197
2198         packet_check_eom();
2199         if (c == NULL)
2200                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2201         chan_rcvd_oclose(c);
2202 }
2203
2204 /* ARGSUSED */
2205 void
2206 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2207 {
2208         int id = packet_get_int();
2209         Channel *c = channel_lookup(id);
2210
2211         packet_check_eom();
2212         if (c == NULL)
2213                 packet_disconnect("Received close confirmation for "
2214                     "out-of-range channel %d.", id);
2215         if (c->type != SSH_CHANNEL_CLOSED)
2216                 packet_disconnect("Received close confirmation for "
2217                     "non-closed channel %d (type %d).", id, c->type);
2218         channel_free(c);
2219 }
2220
2221 /* ARGSUSED */
2222 void
2223 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2224 {
2225         int id, remote_id;
2226         Channel *c;
2227
2228         id = packet_get_int();
2229         c = channel_lookup(id);
2230
2231         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2232                 packet_disconnect("Received open confirmation for "
2233                     "non-opening channel %d.", id);
2234         remote_id = packet_get_int();
2235         /* Record the remote channel number and mark that the channel is now open. */
2236         c->remote_id = remote_id;
2237         c->type = SSH_CHANNEL_OPEN;
2238
2239         if (compat20) {
2240                 c->remote_window = packet_get_int();
2241                 c->remote_maxpacket = packet_get_int();
2242                 if (c->confirm) {
2243                         debug2("callback start");
2244                         c->confirm(c->self, c->confirm_ctx);
2245                         debug2("callback done");
2246                 }
2247                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2248                     c->remote_window, c->remote_maxpacket);
2249         }
2250         packet_check_eom();
2251 }
2252
2253 static char *
2254 reason2txt(int reason)
2255 {
2256         switch (reason) {
2257         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2258                 return "administratively prohibited";
2259         case SSH2_OPEN_CONNECT_FAILED:
2260                 return "connect failed";
2261         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2262                 return "unknown channel type";
2263         case SSH2_OPEN_RESOURCE_SHORTAGE:
2264                 return "resource shortage";
2265         }
2266         return "unknown reason";
2267 }
2268
2269 /* ARGSUSED */
2270 void
2271 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2272 {
2273         int id, reason;
2274         char *msg = NULL, *lang = NULL;
2275         Channel *c;
2276
2277         id = packet_get_int();
2278         c = channel_lookup(id);
2279
2280         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2281                 packet_disconnect("Received open failure for "
2282                     "non-opening channel %d.", id);
2283         if (compat20) {
2284                 reason = packet_get_int();
2285                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2286                         msg  = packet_get_string(NULL);
2287                         lang = packet_get_string(NULL);
2288                 }
2289                 logit("channel %d: open failed: %s%s%s", id,
2290                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2291                 if (msg != NULL)
2292                         xfree(msg);
2293                 if (lang != NULL)
2294                         xfree(lang);
2295         }
2296         packet_check_eom();
2297         /* Free the channel.  This will also close the socket. */
2298         channel_free(c);
2299 }
2300
2301 /* ARGSUSED */
2302 void
2303 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2304 {
2305         Channel *c;
2306         int id;
2307         u_int adjust;
2308
2309         if (!compat20)
2310                 return;
2311
2312         /* Get the channel number and verify it. */
2313         id = packet_get_int();
2314         c = channel_lookup(id);
2315
2316         if (c == NULL) {
2317                 logit("Received window adjust for non-open channel %d.", id);
2318                 return;
2319         }
2320         adjust = packet_get_int();
2321         packet_check_eom();
2322         debug2("channel %d: rcvd adjust %u", id, adjust);
2323         c->remote_window += adjust;
2324 }
2325
2326 /* ARGSUSED */
2327 void
2328 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2329 {
2330         Channel *c = NULL;
2331         u_short host_port;
2332         char *host, *originator_string;
2333         int remote_id, sock = -1;
2334
2335         remote_id = packet_get_int();
2336         host = packet_get_string(NULL);
2337         host_port = packet_get_int();
2338
2339         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2340                 originator_string = packet_get_string(NULL);
2341         } else {
2342                 originator_string = xstrdup("unknown (remote did not supply name)");
2343         }
2344         packet_check_eom();
2345         sock = channel_connect_to(host, host_port);
2346         if (sock != -1) {
2347                 c = channel_new("connected socket",
2348                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2349                     originator_string, 1);
2350                 c->remote_id = remote_id;
2351         }
2352         xfree(originator_string);
2353         if (c == NULL) {
2354                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2355                 packet_put_int(remote_id);
2356                 packet_send();
2357         }
2358         xfree(host);
2359 }
2360
2361
2362 /* -- tcp forwarding */
2363
2364 void
2365 channel_set_af(int af)
2366 {
2367         IPv4or6 = af;
2368 }
2369
2370 static int
2371 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2372     const char *host_to_connect, u_short port_to_connect, int gateway_ports,
2373     int hpn_disabled, int hpn_buffer_size)
2374 {
2375         Channel *c;
2376         int sock, r, success = 0, wildcard = 0, is_client;
2377         struct addrinfo hints, *ai, *aitop;
2378         const char *host, *addr;
2379         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2380
2381         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2382             listen_addr : host_to_connect;
2383         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2384
2385         if (host == NULL) {
2386                 error("No forward host name.");
2387                 return 0;
2388         }
2389         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2390                 error("Forward host name too long.");
2391                 return 0;
2392         }
2393
2394         /*
2395          * Determine whether or not a port forward listens to loopback,
2396          * specified address or wildcard. On the client, a specified bind
2397          * address will always override gateway_ports. On the server, a
2398          * gateway_ports of 1 (``yes'') will override the client's
2399          * specification and force a wildcard bind, whereas a value of 2
2400          * (``clientspecified'') will bind to whatever address the client
2401          * asked for.
2402          *
2403          * Special-case listen_addrs are:
2404          *
2405          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2406          * "" (empty string), "*"  -> wildcard v4/v6
2407          * "localhost"             -> loopback v4/v6
2408          */
2409         addr = NULL;
2410         if (listen_addr == NULL) {
2411                 /* No address specified: default to gateway_ports setting */
2412                 if (gateway_ports)
2413                         wildcard = 1;
2414         } else if (gateway_ports || is_client) {
2415                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2416                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2417                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2418                     (!is_client && gateway_ports == 1))
2419                         wildcard = 1;
2420                 else if (strcmp(listen_addr, "localhost") != 0)
2421                         addr = listen_addr;
2422         }
2423
2424         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2425             type, wildcard, (addr == NULL) ? "NULL" : addr);
2426
2427         /*
2428          * getaddrinfo returns a loopback address if the hostname is
2429          * set to NULL and hints.ai_flags is not AI_PASSIVE
2430          */
2431         memset(&hints, 0, sizeof(hints));
2432         hints.ai_family = IPv4or6;
2433         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2434         hints.ai_socktype = SOCK_STREAM;
2435         snprintf(strport, sizeof strport, "%d", listen_port);
2436         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2437                 if (addr == NULL) {
2438                         /* This really shouldn't happen */
2439                         packet_disconnect("getaddrinfo: fatal error: %s",
2440                             gai_strerror(r));
2441                 } else {
2442                         error("channel_setup_fwd_listener: "
2443                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2444                 }
2445                 return 0;
2446         }
2447
2448         for (ai = aitop; ai; ai = ai->ai_next) {
2449                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2450                         continue;
2451                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2452                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2453                         error("channel_setup_fwd_listener: getnameinfo failed");
2454                         continue;
2455                 }
2456                 /* Create a port to listen for the host. */
2457                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2458                 if (sock < 0) {
2459                         /* this is no error since kernel may not support ipv6 */
2460                         verbose("socket: %.100s", strerror(errno));
2461                         continue;
2462                 }
2463
2464                 channel_set_reuseaddr(sock);
2465
2466                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2467
2468                 /* Bind the socket to the address. */
2469                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2470                         /* address can be in use ipv6 address is already bound */
2471                         if (!ai->ai_next)
2472                                 error("bind: %.100s", strerror(errno));
2473                         else
2474                                 verbose("bind: %.100s", strerror(errno));
2475
2476                         close(sock);
2477                         continue;
2478                 }
2479                 /* Start listening for connections on the socket. */
2480                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2481                         error("listen: %.100s", strerror(errno));
2482                         close(sock);
2483                         continue;
2484                 }
2485                 /* Allocate a channel number for the socket. */
2486                 /* explicitly test for hpn disabled option. if true use smaller window size */
2487                 if (hpn_disabled)
2488                         c = channel_new("port listener", type, sock, sock, -1,
2489                           CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2490                           0, "port listener", 1);
2491                 else
2492                         c = channel_new("port listener", type, sock, sock, -1,
2493                           hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT,
2494                           0, "port listener", 1);
2495                 strlcpy(c->path, host, sizeof(c->path));
2496                 c->host_port = port_to_connect;
2497                 c->listening_port = listen_port;
2498                 success = 1;
2499         }
2500         if (success == 0)
2501                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2502                     listen_port);
2503         freeaddrinfo(aitop);
2504         return success;
2505 }
2506
2507 int
2508 channel_cancel_rport_listener(const char *host, u_short port)
2509 {
2510         u_int i;
2511         int found = 0;
2512
2513         for (i = 0; i < channels_alloc; i++) {
2514                 Channel *c = channels[i];
2515
2516                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2517                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2518                     c->listening_port == port) {
2519                         debug2("%s: close channel %d", __func__, i);
2520                         channel_free(c);
2521                         found = 1;
2522                 }
2523         }
2524
2525         return (found);
2526 }
2527
2528 /* protocol local port fwd, used by ssh (and sshd in v1) */
2529 int
2530 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2531     const char *host_to_connect, u_short port_to_connect, int gateway_ports,
2532     int hpn_disabled, int hpn_buffer_size)
2533 {
2534         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2535             listen_host, listen_port, host_to_connect, port_to_connect,
2536             gateway_ports, hpn_disabled, hpn_buffer_size);
2537 }
2538
2539 /* protocol v2 remote port fwd, used by sshd */
2540 int
2541 channel_setup_remote_fwd_listener(const char *listen_address,
2542     u_short listen_port, int gateway_ports, int hpn_disabled, int hpn_buffer_size)
2543 {
2544         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2545             listen_address, listen_port, NULL, 0, gateway_ports,
2546             hpn_disabled, hpn_buffer_size);
2547 }
2548
2549 /*
2550  * Initiate forwarding of connections to port "port" on remote host through
2551  * the secure channel to host:port from local side.
2552  */
2553
2554 int
2555 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2556     const char *host_to_connect, u_short port_to_connect)
2557 {
2558         int type, success = 0;
2559
2560         /* Record locally that connection to this host/port is permitted. */
2561         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2562                 fatal("channel_request_remote_forwarding: too many forwards");
2563
2564         /* Send the forward request to the remote side. */
2565         if (compat20) {
2566                 const char *address_to_bind;
2567                 if (listen_host == NULL)
2568                         address_to_bind = "localhost";
2569                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2570                         address_to_bind = "";
2571                 else
2572                         address_to_bind = listen_host;
2573
2574                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2575                 packet_put_cstring("tcpip-forward");
2576                 packet_put_char(1);                     /* boolean: want reply */
2577                 packet_put_cstring(address_to_bind);
2578                 packet_put_int(listen_port);
2579                 packet_send();
2580                 packet_write_wait();
2581                 /* Assume that server accepts the request */
2582                 success = 1;
2583         } else {
2584                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2585                 packet_put_int(listen_port);
2586                 packet_put_cstring(host_to_connect);
2587                 packet_put_int(port_to_connect);
2588                 packet_send();
2589                 packet_write_wait();
2590
2591                 /* Wait for response from the remote side. */
2592                 type = packet_read();
2593                 switch (type) {
2594                 case SSH_SMSG_SUCCESS:
2595                         success = 1;
2596                         break;
2597                 case SSH_SMSG_FAILURE:
2598                         break;
2599                 default:
2600                         /* Unknown packet */
2601                         packet_disconnect("Protocol error for port forward request:"
2602                             "received packet type %d.", type);
2603                 }
2604         }
2605         if (success) {
2606                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2607                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2608                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2609                 num_permitted_opens++;
2610         }
2611         return (success ? 0 : -1);
2612 }
2613
2614 /*
2615  * Request cancellation of remote forwarding of connection host:port from
2616  * local side.
2617  */
2618 void
2619 channel_request_rforward_cancel(const char *host, u_short port)
2620 {
2621         int i;
2622
2623         if (!compat20)
2624                 return;
2625
2626         for (i = 0; i < num_permitted_opens; i++) {
2627                 if (permitted_opens[i].host_to_connect != NULL &&
2628                     permitted_opens[i].listen_port == port)
2629                         break;
2630         }
2631         if (i >= num_permitted_opens) {
2632                 debug("%s: requested forward not found", __func__);
2633                 return;
2634         }
2635         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2636         packet_put_cstring("cancel-tcpip-forward");
2637         packet_put_char(0);
2638         packet_put_cstring(host == NULL ? "" : host);
2639         packet_put_int(port);
2640         packet_send();
2641
2642         permitted_opens[i].listen_port = 0;
2643         permitted_opens[i].port_to_connect = 0;
2644         xfree(permitted_opens[i].host_to_connect);
2645         permitted_opens[i].host_to_connect = NULL;
2646 }
2647
2648 /*
2649  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2650  * listening for the port, and sends back a success reply (or disconnect
2651  * message if there was an error).
2652  */
2653 int
2654 channel_input_port_forward_request(int is_root, int gateway_ports,
2655                                    int hpn_disabled, int hpn_buffer_size)
2656 {
2657         u_short port, host_port;
2658         int success = 0;
2659         char *hostname;
2660
2661         /* Get arguments from the packet. */
2662         port = packet_get_int();
2663         hostname = packet_get_string(NULL);
2664         host_port = packet_get_int();
2665
2666 #ifndef HAVE_CYGWIN
2667         /*
2668          * Check that an unprivileged user is not trying to forward a
2669          * privileged port.
2670          */
2671         if (port < IPPORT_RESERVED && !is_root)
2672                 packet_disconnect(
2673                     "Requested forwarding of port %d but user is not root.",
2674                     port);
2675         if (host_port == 0)
2676                 packet_disconnect("Dynamic forwarding denied.");
2677 #endif
2678
2679         /* Initiate forwarding */
2680         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2681             host_port, gateway_ports, hpn_disabled, hpn_buffer_size);
2682
2683         /* Free the argument string. */
2684         xfree(hostname);
2685
2686         return (success ? 0 : -1);
2687 }
2688
2689 /*
2690  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2691  * usually called by the server, because the user could connect to any port
2692  * anyway, and the server has no way to know but to trust the client anyway.
2693  */
2694 void
2695 channel_permit_all_opens(void)
2696 {
2697         if (num_permitted_opens == 0)
2698                 all_opens_permitted = 1;
2699 }
2700
2701 void
2702 channel_add_permitted_opens(char *host, int port)
2703 {
2704         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2705                 fatal("channel_add_permitted_opens: too many forwards");
2706         debug("allow port forwarding to host %s port %d", host, port);
2707
2708         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2709         permitted_opens[num_permitted_opens].port_to_connect = port;
2710         num_permitted_opens++;
2711
2712         all_opens_permitted = 0;
2713 }
2714
2715 int
2716 channel_add_adm_permitted_opens(char *host, int port)
2717 {
2718         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2719                 fatal("channel_add_adm_permitted_opens: too many forwards");
2720         debug("config allows port forwarding to host %s port %d", host, port);
2721
2722         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2723              = xstrdup(host);
2724         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2725         return ++num_adm_permitted_opens;
2726 }
2727
2728 void
2729 channel_clear_permitted_opens(void)
2730 {
2731         int i;
2732
2733         for (i = 0; i < num_permitted_opens; i++)
2734                 if (permitted_opens[i].host_to_connect != NULL)
2735                         xfree(permitted_opens[i].host_to_connect);
2736         num_permitted_opens = 0;
2737 }
2738
2739 void
2740 channel_clear_adm_permitted_opens(void)
2741 {
2742         int i;
2743
2744         for (i = 0; i < num_adm_permitted_opens; i++)
2745                 if (permitted_adm_opens[i].host_to_connect != NULL)
2746                         xfree(permitted_adm_opens[i].host_to_connect);
2747         num_adm_permitted_opens = 0;
2748 }
2749
2750 /* return socket to remote host, port */
2751 static int
2752 connect_to(const char *host, u_short port)
2753 {
2754         struct addrinfo hints, *ai, *aitop;
2755         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2756         int gaierr;
2757         int sock = -1;
2758
2759         memset(&hints, 0, sizeof(hints));
2760         hints.ai_family = IPv4or6;
2761         hints.ai_socktype = SOCK_STREAM;
2762         snprintf(strport, sizeof strport, "%d", port);
2763         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2764                 error("connect_to %.100s: unknown host (%s)", host,
2765                     gai_strerror(gaierr));
2766                 return -1;
2767         }
2768         for (ai = aitop; ai; ai = ai->ai_next) {
2769                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2770                         continue;
2771                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2772                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2773                         error("connect_to: getnameinfo failed");
2774                         continue;
2775                 }
2776                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2777                 if (sock < 0) {
2778                         if (ai->ai_next == NULL)
2779                                 error("socket: %.100s", strerror(errno));
2780                         else
2781                                 verbose("socket: %.100s", strerror(errno));
2782                         continue;
2783                 }
2784                 if (set_nonblock(sock) == -1)
2785                         fatal("%s: set_nonblock(%d)", __func__, sock);
2786                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2787                     errno != EINPROGRESS) {
2788                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2789                             strerror(errno));
2790                         close(sock);
2791                         continue;       /* fail -- try next */
2792                 }
2793                 break; /* success */
2794
2795         }
2796         freeaddrinfo(aitop);
2797         if (!ai) {
2798                 error("connect_to %.100s port %d: failed.", host, port);
2799                 return -1;
2800         }
2801         /* success */
2802         set_nodelay(sock);
2803         return sock;
2804 }
2805
2806 int
2807 channel_connect_by_listen_address(u_short listen_port)
2808 {
2809         int i;
2810
2811         for (i = 0; i < num_permitted_opens; i++)
2812                 if (permitted_opens[i].host_to_connect != NULL &&
2813                     permitted_opens[i].listen_port == listen_port)
2814                         return connect_to(
2815                             permitted_opens[i].host_to_connect,
2816                             permitted_opens[i].port_to_connect);
2817         error("WARNING: Server requests forwarding for unknown listen_port %d",
2818             listen_port);
2819         return -1;
2820 }
2821
2822 /* Check if connecting to that port is permitted and connect. */
2823 int
2824 channel_connect_to(const char *host, u_short port)
2825 {
2826         int i, permit, permit_adm = 1;
2827
2828         permit = all_opens_permitted;
2829         if (!permit) {
2830                 for (i = 0; i < num_permitted_opens; i++)
2831                         if (permitted_opens[i].host_to_connect != NULL &&
2832                             permitted_opens[i].port_to_connect == port &&
2833                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2834                                 permit = 1;
2835         }
2836
2837         if (num_adm_permitted_opens > 0) {
2838                 permit_adm = 0;
2839                 for (i = 0; i < num_adm_permitted_opens; i++)
2840                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2841                             permitted_adm_opens[i].port_to_connect == port &&
2842                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2843                             == 0)
2844                                 permit_adm = 1;
2845         }
2846
2847         if (!permit || !permit_adm) {
2848                 logit("Received request to connect to host %.100s port %d, "
2849                     "but the request was denied.", host, port);
2850                 return -1;
2851         }
2852         return connect_to(host, port);
2853 }
2854
2855 void
2856 channel_send_window_changes(void)
2857 {
2858         u_int i;
2859         struct winsize ws;
2860
2861         for (i = 0; i < channels_alloc; i++) {
2862                 if (channels[i] == NULL || !channels[i]->client_tty ||
2863                     channels[i]->type != SSH_CHANNEL_OPEN)
2864                         continue;
2865                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2866                         continue;
2867                 channel_request_start(i, "window-change", 0);
2868                 packet_put_int((u_int)ws.ws_col);
2869                 packet_put_int((u_int)ws.ws_row);
2870                 packet_put_int((u_int)ws.ws_xpixel);
2871                 packet_put_int((u_int)ws.ws_ypixel);
2872                 packet_send();
2873         }
2874 }
2875
2876 /* -- X11 forwarding */
2877
2878 /*
2879  * Creates an internet domain socket for listening for X11 connections.
2880  * Returns 0 and a suitable display number for the DISPLAY variable
2881  * stored in display_numberp , or -1 if an error occurs.
2882  */
2883 int
2884 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2885     int single_connection, u_int *display_numberp, int **chanids,
2886     int hpn_disabled, int hpn_buffer_size)
2887 {
2888         Channel *nc = NULL;
2889         int display_number, sock;
2890         u_short port;
2891         struct addrinfo hints, *ai, *aitop;
2892         char strport[NI_MAXSERV];
2893         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2894
2895         if (chanids == NULL)
2896                 return -1;
2897
2898         for (display_number = x11_display_offset;
2899             display_number < MAX_DISPLAYS;
2900             display_number++) {
2901                 port = 6000 + display_number;
2902                 memset(&hints, 0, sizeof(hints));
2903                 hints.ai_family = IPv4or6;
2904                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2905                 hints.ai_socktype = SOCK_STREAM;
2906                 snprintf(strport, sizeof strport, "%d", port);
2907                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2908                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2909                         return -1;
2910                 }
2911                 for (ai = aitop; ai; ai = ai->ai_next) {
2912                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2913                                 continue;
2914                         sock = socket(ai->ai_family, ai->ai_socktype,
2915                             ai->ai_protocol);
2916                         if (sock < 0) {
2917                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2918                                         error("socket: %.100s", strerror(errno));
2919                                         freeaddrinfo(aitop);
2920                                         return -1;
2921                                 } else {
2922                                         debug("x11_create_display_inet: Socket family %d not supported",
2923                                                  ai->ai_family);
2924                                         continue;
2925                                 }
2926                         }
2927 #ifdef IPV6_V6ONLY
2928                         if (ai->ai_family == AF_INET6) {
2929                                 int on = 1;
2930                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2931                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2932                         }
2933 #endif
2934                         channel_set_reuseaddr(sock);
2935                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2936                                 debug2("bind port %d: %.100s", port, strerror(errno));
2937                                 close(sock);
2938
2939                                 if (ai->ai_next)
2940                                         continue;
2941
2942                                 for (n = 0; n < num_socks; n++) {
2943                                         close(socks[n]);
2944                                 }
2945                                 num_socks = 0;
2946                                 break;
2947                         }
2948                         socks[num_socks++] = sock;
2949 #ifndef DONT_TRY_OTHER_AF
2950                         if (num_socks == NUM_SOCKS)
2951                                 break;
2952 #else
2953                         if (x11_use_localhost) {
2954                                 if (num_socks == NUM_SOCKS)
2955                                         break;
2956                         } else {
2957                                 break;
2958                         }
2959 #endif
2960                 }
2961                 freeaddrinfo(aitop);
2962                 if (num_socks > 0)
2963                         break;
2964         }
2965         if (display_number >= MAX_DISPLAYS) {
2966                 error("Failed to allocate internet-domain X11 display socket.");
2967                 return -1;
2968         }
2969         /* Start listening for connections on the socket. */
2970         for (n = 0; n < num_socks; n++) {
2971                 sock = socks[n];
2972                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2973                         error("listen: %.100s", strerror(errno));
2974                         close(sock);
2975                         return -1;
2976                 }
2977         }
2978
2979         /* Allocate a channel for each socket. */
2980         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2981         for (n = 0; n < num_socks; n++) {
2982                 sock = socks[n];
2983                 if (hpn_disabled)
2984                         nc = channel_new("x11 listener",
2985                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2986                             CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2987                             0, "X11 inet listener", 1);
2988                 else
2989                         nc = channel_new("x11 listener",
2990                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2991                             hpn_buffer_size, CHAN_X11_PACKET_DEFAULT,
2992                             0, "X11 inet listener", 1);
2993                 nc->single_connection = single_connection;
2994                 (*chanids)[n] = nc->self;
2995         }
2996         (*chanids)[n] = -1;
2997
2998         /* Return the display number for the DISPLAY environment variable. */
2999         *display_numberp = display_number;
3000         return (0);
3001 }
3002
3003 static int
3004 connect_local_xsocket(u_int dnr)
3005 {
3006         int sock;
3007         struct sockaddr_un addr;
3008
3009         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3010         if (sock < 0)
3011                 error("socket: %.100s", strerror(errno));
3012         memset(&addr, 0, sizeof(addr));
3013         addr.sun_family = AF_UNIX;
3014         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
3015         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3016                 return sock;
3017         close(sock);
3018         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3019         return -1;
3020 }
3021
3022 int
3023 x11_connect_display(void)
3024 {
3025         u_int display_number;
3026         const char *display;
3027         char buf[1024], *cp;
3028         struct addrinfo hints, *ai, *aitop;
3029         char strport[NI_MAXSERV];
3030         int gaierr, sock = 0;
3031
3032         /* Try to open a socket for the local X server. */
3033         display = getenv("DISPLAY");
3034         if (!display) {
3035                 error("DISPLAY not set.");
3036                 return -1;
3037         }
3038         /*
3039          * Now we decode the value of the DISPLAY variable and make a
3040          * connection to the real X server.
3041          */
3042
3043         /*
3044          * Check if it is a unix domain socket.  Unix domain displays are in
3045          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3046          */
3047         if (strncmp(display, "unix:", 5) == 0 ||
3048             display[0] == ':') {
3049                 /* Connect to the unix domain socket. */
3050                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3051                         error("Could not parse display number from DISPLAY: %.100s",
3052                             display);
3053                         return -1;
3054                 }
3055                 /* Create a socket. */
3056                 sock = connect_local_xsocket(display_number);
3057                 if (sock < 0)
3058                         return -1;
3059
3060                 /* OK, we now have a connection to the display. */
3061                 return sock;
3062         }
3063         /*
3064          * Connect to an inet socket.  The DISPLAY value is supposedly
3065          * hostname:d[.s], where hostname may also be numeric IP address.
3066          */
3067         strlcpy(buf, display, sizeof(buf));
3068         cp = strchr(buf, ':');
3069         if (!cp) {
3070                 error("Could not find ':' in DISPLAY: %.100s", display);
3071                 return -1;
3072         }
3073         *cp = 0;
3074         /* buf now contains the host name.  But first we parse the display number. */
3075         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3076                 error("Could not parse display number from DISPLAY: %.100s",
3077                     display);
3078                 return -1;
3079         }
3080
3081         /* Look up the host address */
3082         memset(&hints, 0, sizeof(hints));
3083         hints.ai_family = IPv4or6;
3084         hints.ai_socktype = SOCK_STREAM;
3085         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3086         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3087                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
3088                 return -1;
3089         }
3090         for (ai = aitop; ai; ai = ai->ai_next) {
3091                 /* Create a socket. */
3092                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3093                 if (sock < 0) {
3094                         debug2("socket: %.100s", strerror(errno));
3095                         continue;
3096                 }
3097                 /* Connect it to the display. */
3098                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3099                         debug2("connect %.100s port %u: %.100s", buf,
3100                             6000 + display_number, strerror(errno));
3101                         close(sock);
3102                         continue;
3103                 }
3104                 /* Success */
3105                 break;
3106         }
3107         freeaddrinfo(aitop);
3108         if (!ai) {
3109                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3110                     strerror(errno));
3111                 return -1;
3112         }
3113         set_nodelay(sock);
3114         return sock;
3115 }
3116
3117 /*
3118  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3119  * the remote channel number.  We should do whatever we want, and respond
3120  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3121  */
3122
3123 /* ARGSUSED */
3124 void
3125 x11_input_open(int type, u_int32_t seq, void *ctxt)
3126 {
3127         Channel *c = NULL;
3128         int remote_id, sock = 0;
3129         char *remote_host;
3130
3131         debug("Received X11 open request.");
3132
3133         remote_id = packet_get_int();
3134
3135         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3136                 remote_host = packet_get_string(NULL);
3137         } else {
3138                 remote_host = xstrdup("unknown (remote did not supply name)");
3139         }
3140         packet_check_eom();
3141
3142         /* Obtain a connection to the real X display. */
3143         sock = x11_connect_display();
3144         if (sock != -1) {
3145                 /* Allocate a channel for this connection. */
3146                 c = channel_new("connected x11 socket",
3147                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3148                     remote_host, 1);
3149                 c->remote_id = remote_id;
3150                 c->force_drain = 1;
3151         }
3152         xfree(remote_host);
3153         if (c == NULL) {
3154                 /* Send refusal to the remote host. */
3155                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3156                 packet_put_int(remote_id);
3157         } else {
3158                 /* Send a confirmation to the remote host. */
3159                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3160                 packet_put_int(remote_id);
3161                 packet_put_int(c->self);
3162         }
3163         packet_send();
3164 }
3165
3166 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3167 /* ARGSUSED */
3168 void
3169 deny_input_open(int type, u_int32_t seq, void *ctxt)
3170 {
3171         int rchan = packet_get_int();
3172
3173         switch (type) {
3174         case SSH_SMSG_AGENT_OPEN:
3175                 error("Warning: ssh server tried agent forwarding.");
3176                 break;
3177         case SSH_SMSG_X11_OPEN:
3178                 error("Warning: ssh server tried X11 forwarding.");
3179                 break;
3180         default:
3181                 error("deny_input_open: type %d", type);
3182                 break;
3183         }
3184         error("Warning: this is probably a break-in attempt by a malicious server.");
3185         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3186         packet_put_int(rchan);
3187         packet_send();
3188 }
3189
3190 /*
3191  * Requests forwarding of X11 connections, generates fake authentication
3192  * data, and enables authentication spoofing.
3193  * This should be called in the client only.
3194  */
3195 void
3196 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3197     const char *proto, const char *data)
3198 {
3199         u_int data_len = (u_int) strlen(data) / 2;
3200         u_int i, value;
3201         char *new_data;
3202         int screen_number;
3203         const char *cp;
3204         u_int32_t rnd = 0;
3205
3206         if (x11_saved_display == NULL)
3207                 x11_saved_display = xstrdup(disp);
3208         else if (strcmp(disp, x11_saved_display) != 0) {
3209                 error("x11_request_forwarding_with_spoofing: different "
3210                     "$DISPLAY already forwarded");
3211                 return;
3212         }
3213
3214         cp = strchr(disp, ':');
3215         if (cp)
3216                 cp = strchr(cp, '.');
3217         if (cp)
3218                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3219         else
3220                 screen_number = 0;
3221
3222         if (x11_saved_proto == NULL) {
3223                 /* Save protocol name. */
3224                 x11_saved_proto = xstrdup(proto);
3225                 /*
3226                  * Extract real authentication data and generate fake data
3227                  * of the same length.
3228                  */
3229                 x11_saved_data = xmalloc(data_len);
3230                 x11_fake_data = xmalloc(data_len);
3231                 for (i = 0; i < data_len; i++) {
3232                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3233                                 fatal("x11_request_forwarding: bad "
3234                                     "authentication data: %.100s", data);
3235                         if (i % 4 == 0)
3236                                 rnd = arc4random();
3237                         x11_saved_data[i] = value;
3238                         x11_fake_data[i] = rnd & 0xff;
3239                         rnd >>= 8;
3240                 }
3241                 x11_saved_data_len = data_len;
3242                 x11_fake_data_len = data_len;
3243         }
3244
3245         /* Convert the fake data into hex. */
3246         new_data = tohex(x11_fake_data, data_len);
3247
3248         /* Send the request packet. */
3249         if (compat20) {
3250                 channel_request_start(client_session_id, "x11-req", 0);
3251                 packet_put_char(0);     /* XXX bool single connection */
3252         } else {
3253                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3254         }
3255         packet_put_cstring(proto);
3256         packet_put_cstring(new_data);
3257         packet_put_int(screen_number);
3258         packet_send();
3259         packet_write_wait();
3260         xfree(new_data);
3261 }
3262
3263
3264 /* -- agent forwarding */
3265
3266 /* Sends a message to the server to request authentication fd forwarding. */
3267
3268 void
3269 auth_request_forwarding(void)
3270 {
3271         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3272         packet_send();
3273         packet_write_wait();
3274 }