crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.309 2010/08/05 13:08:42 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 <fcntl.h>
  57 #include <netdb.h>
  58 #include <stdio.h>
  59 #include <stdlib.h>
  60 #include <string.h>
  61 #include <termios.h>
  62 #include <unistd.h>
  63 #include <stdarg.h>
  64
  65 #include "openbsd-compat/sys-queue.h"
  66 #include "xmalloc.h"
  67 #include "ssh.h"
  68 #include "ssh1.h"
  69 #include "ssh2.h"
  70 #include "packet.h"
  71 #include "log.h"
  72 #include "misc.h"
  73 #include "buffer.h"
  74 #include "channels.h"
  75 #include "compat.h"
  76 #include "canohost.h"
  77 #include "key.h"
  78 #include "authfd.h"
  79 #include "pathnames.h"
  80
  81 /* -- channel core */
  82
  83 /*
  84  * Pointer to an array containing all allocated channels.  The array is
  85  * dynamically extended as needed.
  86  */
  87 static Channel **channels = NULL;
  88
  89 /*
  90  * Size of the channel array.  All slots of the array must always be
  91  * initialized (at least the type field); unused slots set to NULL
  92  */
  93 static u_int channels_alloc = 0;
  94
  95 /*
  96  * Maximum file descriptor value used in any of the channels.  This is
  97  * updated in channel_new.
  98  */
  99 static int channel_max_fd = 0;
 100
 101
 102 /* -- tcp forwarding */
 103
 104 /*
 105  * Data structure for storing which hosts are permitted for forward requests.
 106  * The local sides of any remote forwards are stored in this array to prevent
 107  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 108  * network (which might be behind a firewall).
 109  */
 110 typedef struct {
 111         char *host_to_connect;          /* Connect to 'host'. */
 112         u_short port_to_connect;        /* Connect to 'port'. */
 113         u_short listen_port;            /* Remote side should listen port number. */
 114 } ForwardPermission;
 115
 116 /* List of all permitted host/port pairs to connect by the user. */
 117 static ForwardPermission *permitted_opens = NULL;
 118
 119 /* List of all permitted host/port pairs to connect by the admin. */
 120 static ForwardPermission *permitted_adm_opens = NULL;
 121
 122 /* Number of permitted host/port pairs in the array permitted by the user. */
 123 static int num_permitted_opens = 0;
 124
 125 /* Number of permitted host/port pair in the array permitted by the admin. */
 126 static int num_adm_permitted_opens = 0;
 127
 128 /*
 129  * If this is true, all opens are permitted.  This is the case on the server
 130  * on which we have to trust the client anyway, and the user could do
 131  * anything after logging in anyway.
 132  */
 133 static int all_opens_permitted = 0;
 134
 135
 136 /* -- X11 forwarding */
 137
 138 /* Maximum number of fake X11 displays to try. */
 139 #define MAX_DISPLAYS  1000
 140
 141 /* Saved X11 local (client) display. */
 142 static char *x11_saved_display = NULL;
 143
 144 /* Saved X11 authentication protocol name. */
 145 static char *x11_saved_proto = NULL;
 146
 147 /* Saved X11 authentication data.  This is the real data. */
 148 static char *x11_saved_data = NULL;
 149 static u_int x11_saved_data_len = 0;
 150
 151 /*
 152  * Fake X11 authentication data.  This is what the server will be sending us;
 153  * we should replace any occurrences of this by the real data.
 154  */
 155 static u_char *x11_fake_data = NULL;
 156 static u_int x11_fake_data_len;
 157
 158
 159 /* -- agent forwarding */
 160
 161 #define NUM_SOCKS       10
 162
 163 /* AF_UNSPEC or AF_INET or AF_INET6 */
 164 static int IPv4or6 = AF_UNSPEC;
 165
 166 /* helper */
 167 static void port_open_helper(Channel *c, char *rtype);
 168
 169 /* non-blocking connect helpers */
 170 static int connect_next(struct channel_connect *);
 171 static void channel_connect_ctx_free(struct channel_connect *);
 172
 173
 174 static int hpn_disabled = 0;
 175 static int hpn_buffer_size = 2 * 1024 * 1024;
 176
 177 /* -- channel core */
 178
 179
 180
 181 Channel *
 182 channel_by_id(int id)
 183 {
 184         Channel *c;
 185
 186         if (id < 0 || (u_int)id >= channels_alloc) {
 187                 logit("channel_by_id: %d: bad id", id);
 188                 return NULL;
 189         }
 190         c = channels[id];
 191         if (c == NULL) {
 192                 logit("channel_by_id: %d: bad id: channel free", id);
 193                 return NULL;
 194         }
 195         return c;
 196 }
 197
 198 /*
 199  * Returns the channel if it is allowed to receive protocol messages.
 200  * Private channels, like listening sockets, may not receive messages.
 201  */
 202 Channel *
 203 channel_lookup(int id)
 204 {
 205         Channel *c;
 206
 207         if ((c = channel_by_id(id)) == NULL)
 208                 return (NULL);
 209
 210         switch (c->type) {
 211         case SSH_CHANNEL_X11_OPEN:
 212         case SSH_CHANNEL_LARVAL:
 213         case SSH_CHANNEL_CONNECTING:
 214         case SSH_CHANNEL_DYNAMIC:
 215         case SSH_CHANNEL_OPENING:
 216         case SSH_CHANNEL_OPEN:
 217         case SSH_CHANNEL_INPUT_DRAINING:
 218         case SSH_CHANNEL_OUTPUT_DRAINING:
 219                 return (c);
 220         }
 221         logit("Non-public channel %d, type %d.", id, c->type);
 222         return (NULL);
 223 }
 224
 225 /*
 226  * Register filedescriptors for a channel, used when allocating a channel or
 227  * when the channel consumer/producer is ready, e.g. shell exec'd
 228  */
 229 static void
 230 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 231     int extusage, int nonblock, int is_tty)
 232 {
 233         /* Update the maximum file descriptor value. */
 234         channel_max_fd = MAX(channel_max_fd, rfd);
 235         channel_max_fd = MAX(channel_max_fd, wfd);
 236         channel_max_fd = MAX(channel_max_fd, efd);
 237
 238         if (rfd != -1)
 239                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 240         if (wfd != -1 && wfd != rfd)
 241                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 242         if (efd != -1 && efd != rfd && efd != wfd)
 243                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 244
 245         c->rfd = rfd;
 246         c->wfd = wfd;
 247         c->sock = (rfd == wfd) ? rfd : -1;
 248         c->efd = efd;
 249         c->extended_usage = extusage;
 250
 251         if ((c->isatty = is_tty) != 0)
 252                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 253         c->wfd_isatty = is_tty || isatty(c->wfd);
 254
 255         /* enable nonblocking mode */
 256         if (nonblock) {
 257                 if (rfd != -1)
 258                         set_nonblock(rfd);
 259                 if (wfd != -1)
 260                         set_nonblock(wfd);
 261                 if (efd != -1)
 262                         set_nonblock(efd);
 263         }
 264 }
 265
 266 /*
 267  * Allocate a new channel object and set its type and socket. This will cause
 268  * remote_name to be freed.
 269  */
 270 Channel *
 271 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 272     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 273 {
 274         int found;
 275         u_int i;
 276         Channel *c;
 277
 278         /* Do initial allocation if this is the first call. */
 279         if (channels_alloc == 0) {
 280                 channels_alloc = 10;
 281                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 282                 for (i = 0; i < channels_alloc; i++)
 283                         channels[i] = NULL;
 284         }
 285         /* Try to find a free slot where to put the new channel. */
 286         for (found = -1, i = 0; i < channels_alloc; i++)
 287                 if (channels[i] == NULL) {
 288                         /* Found a free slot. */
 289                         found = (int)i;
 290                         break;
 291                 }
 292         if (found < 0) {
 293                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 294                 found = channels_alloc;
 295                 if (channels_alloc > 10000)
 296                         fatal("channel_new: internal error: channels_alloc %d "
 297                             "too big.", channels_alloc);
 298                 channels = xrealloc(channels, channels_alloc + 10,
 299                     sizeof(Channel *));
 300                 channels_alloc += 10;
 301                 debug2("channel: expanding %d", channels_alloc);
 302                 for (i = found; i < channels_alloc; i++)
 303                         channels[i] = NULL;
 304         }
 305         /* Initialize and return new channel. */
 306         c = channels[found] = xcalloc(1, sizeof(Channel));
 307         buffer_init(&c->input);
 308         buffer_init(&c->output);
 309         buffer_init(&c->extended);
 310         c->path = NULL;
 311         c->ostate = CHAN_OUTPUT_OPEN;
 312         c->istate = CHAN_INPUT_OPEN;
 313         c->flags = 0;
 314         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 315         c->self = found;
 316         c->type = type;
 317         c->ctype = ctype;
 318         c->local_window = window;
 319         c->local_window_max = window;
 320         c->local_consumed = 0;
 321         c->local_maxpacket = maxpack;
 322         c->dynamic_window = 0;
 323         c->remote_id = -1;
 324         c->remote_name = xstrdup(remote_name);
 325         c->remote_window = 0;
 326         c->remote_maxpacket = 0;
 327         c->force_drain = 0;
 328         c->single_connection = 0;
 329         c->detach_user = NULL;
 330         c->detach_close = 0;
 331         c->open_confirm = NULL;
 332         c->open_confirm_ctx = NULL;
 333         c->input_filter = NULL;
 334         c->output_filter = NULL;
 335         c->filter_ctx = NULL;
 336         c->filter_cleanup = NULL;
 337         c->ctl_chan = -1;
 338         c->mux_rcb = NULL;
 339         c->mux_ctx = NULL;
 340         c->mux_pause = 0;
 341         c->delayed = 1;         /* prevent call to channel_post handler */
 342         TAILQ_INIT(&c->status_confirms);
 343         debug("channel %d: new [%s]", found, remote_name);
 344         return c;
 345 }
 346
 347 static int
 348 channel_find_maxfd(void)
 349 {
 350         u_int i;
 351         int max = 0;
 352         Channel *c;
 353
 354         for (i = 0; i < channels_alloc; i++) {
 355                 c = channels[i];
 356                 if (c != NULL) {
 357                         max = MAX(max, c->rfd);
 358                         max = MAX(max, c->wfd);
 359                         max = MAX(max, c->efd);
 360                 }
 361         }
 362         return max;
 363 }
 364
 365 int
 366 channel_close_fd(int *fdp)
 367 {
 368         int ret = 0, fd = *fdp;
 369
 370         if (fd != -1) {
 371                 ret = close(fd);
 372                 *fdp = -1;
 373                 if (fd == channel_max_fd)
 374                         channel_max_fd = channel_find_maxfd();
 375         }
 376         return ret;
 377 }
 378
 379 /* Close all channel fd/socket. */
 380 static void
 381 channel_close_fds(Channel *c)
 382 {
 383         debug3("channel %d: close_fds r %d w %d e %d",
 384             c->self, c->rfd, c->wfd, c->efd);
 385
 386         channel_close_fd(&c->sock);
 387         channel_close_fd(&c->rfd);
 388         channel_close_fd(&c->wfd);
 389         channel_close_fd(&c->efd);
 390 }
 391
 392 /* Free the channel and close its fd/socket. */
 393 void
 394 channel_free(Channel *c)
 395 {
 396         char *s;
 397         u_int i, n;
 398         struct channel_confirm *cc;
 399
 400         for (n = 0, i = 0; i < channels_alloc; i++)
 401                 if (channels[i])
 402                         n++;
 403         debug("channel %d: free: %s, nchannels %u", c->self,
 404             c->remote_name ? c->remote_name : "???", n);
 405
 406         s = channel_open_message();
 407         debug3("channel %d: status: %s", c->self, s);
 408         xfree(s);
 409
 410         if (c->sock != -1)
 411                 shutdown(c->sock, SHUT_RDWR);
 412         channel_close_fds(c);
 413         buffer_free(&c->input);
 414         buffer_free(&c->output);
 415         buffer_free(&c->extended);
 416         if (c->remote_name) {
 417                 xfree(c->remote_name);
 418                 c->remote_name = NULL;
 419         }
 420         if (c->path) {
 421                 xfree(c->path);
 422                 c->path = NULL;
 423         }
 424         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 425                 if (cc->abandon_cb != NULL)
 426                         cc->abandon_cb(c, cc->ctx);
 427                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 428                 bzero(cc, sizeof(*cc));
 429                 xfree(cc);
 430         }
 431         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 432                 c->filter_cleanup(c->self, c->filter_ctx);
 433         channels[c->self] = NULL;
 434         xfree(c);
 435 }
 436
 437 void
 438 channel_free_all(void)
 439 {
 440         u_int i;
 441
 442         for (i = 0; i < channels_alloc; i++)
 443                 if (channels[i] != NULL)
 444                         channel_free(channels[i]);
 445 }
 446
 447 /*
 448  * Closes the sockets/fds of all channels.  This is used to close extra file
 449  * descriptors after a fork.
 450  */
 451 void
 452 channel_close_all(void)
 453 {
 454         u_int i;
 455
 456         for (i = 0; i < channels_alloc; i++)
 457                 if (channels[i] != NULL)
 458                         channel_close_fds(channels[i]);
 459 }
 460
 461 /*
 462  * Stop listening to channels.
 463  */
 464 void
 465 channel_stop_listening(void)
 466 {
 467         u_int i;
 468         Channel *c;
 469
 470         for (i = 0; i < channels_alloc; i++) {
 471                 c = channels[i];
 472                 if (c != NULL) {
 473                         switch (c->type) {
 474                         case SSH_CHANNEL_AUTH_SOCKET:
 475                         case SSH_CHANNEL_PORT_LISTENER:
 476                         case SSH_CHANNEL_RPORT_LISTENER:
 477                         case SSH_CHANNEL_X11_LISTENER:
 478                                 channel_close_fd(&c->sock);
 479                                 channel_free(c);
 480                                 break;
 481                         }
 482                 }
 483         }
 484 }
 485
 486 /*
 487  * Returns true if no channel has too much buffered data, and false if one or
 488  * more channel is overfull.
 489  */
 490 int
 491 channel_not_very_much_buffered_data(void)
 492 {
 493         u_int i;
 494         Channel *c;
 495
 496         for (i = 0; i < channels_alloc; i++) {
 497                 c = channels[i];
 498                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 499 #if 0
 500                         if (!compat20 &&
 501                             buffer_len(&c->input) > packet_get_maxsize()) {
 502                                 debug2("channel %d: big input buffer %d",
 503                                     c->self, buffer_len(&c->input));
 504                                 return 0;
 505                         }
 506 #endif
 507                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 508                                 debug2("channel %d: big output buffer %u > %u",
 509                                     c->self, buffer_len(&c->output),
 510                                     packet_get_maxsize());
 511                                 return 0;
 512                         }
 513                 }
 514         }
 515         return 1;
 516 }
 517
 518 /* Returns true if any channel is still open. */
 519 int
 520 channel_still_open(void)
 521 {
 522         u_int i;
 523         Channel *c;
 524
 525         for (i = 0; i < channels_alloc; i++) {
 526                 c = channels[i];
 527                 if (c == NULL)
 528                         continue;
 529                 switch (c->type) {
 530                 case SSH_CHANNEL_X11_LISTENER:
 531                 case SSH_CHANNEL_PORT_LISTENER:
 532                 case SSH_CHANNEL_RPORT_LISTENER:
 533                 case SSH_CHANNEL_MUX_LISTENER:
 534                 case SSH_CHANNEL_CLOSED:
 535                 case SSH_CHANNEL_AUTH_SOCKET:
 536                 case SSH_CHANNEL_DYNAMIC:
 537                 case SSH_CHANNEL_CONNECTING:
 538                 case SSH_CHANNEL_ZOMBIE:
 539                         continue;
 540                 case SSH_CHANNEL_LARVAL:
 541                         if (!compat20)
 542                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 543                         continue;
 544                 case SSH_CHANNEL_OPENING:
 545                 case SSH_CHANNEL_OPEN:
 546                 case SSH_CHANNEL_X11_OPEN:
 547                 case SSH_CHANNEL_MUX_CLIENT:
 548                         return 1;
 549                 case SSH_CHANNEL_INPUT_DRAINING:
 550                 case SSH_CHANNEL_OUTPUT_DRAINING:
 551                         if (!compat13)
 552                                 fatal("cannot happen: OUT_DRAIN");
 553                         return 1;
 554                 default:
 555                         fatal("channel_still_open: bad channel type %d", c->type);
 556                         /* NOTREACHED */
 557                 }
 558         }
 559         return 0;
 560 }
 561
 562 /* Returns the id of an open channel suitable for keepaliving */
 563 int
 564 channel_find_open(void)
 565 {
 566         u_int i;
 567         Channel *c;
 568
 569         for (i = 0; i < channels_alloc; i++) {
 570                 c = channels[i];
 571                 if (c == NULL || c->remote_id < 0)
 572                         continue;
 573                 switch (c->type) {
 574                 case SSH_CHANNEL_CLOSED:
 575                 case SSH_CHANNEL_DYNAMIC:
 576                 case SSH_CHANNEL_X11_LISTENER:
 577                 case SSH_CHANNEL_PORT_LISTENER:
 578                 case SSH_CHANNEL_RPORT_LISTENER:
 579                 case SSH_CHANNEL_MUX_LISTENER:
 580                 case SSH_CHANNEL_MUX_CLIENT:
 581                 case SSH_CHANNEL_OPENING:
 582                 case SSH_CHANNEL_CONNECTING:
 583                 case SSH_CHANNEL_ZOMBIE:
 584                         continue;
 585                 case SSH_CHANNEL_LARVAL:
 586                 case SSH_CHANNEL_AUTH_SOCKET:
 587                 case SSH_CHANNEL_OPEN:
 588                 case SSH_CHANNEL_X11_OPEN:
 589                         return i;
 590                 case SSH_CHANNEL_INPUT_DRAINING:
 591                 case SSH_CHANNEL_OUTPUT_DRAINING:
 592                         if (!compat13)
 593                                 fatal("cannot happen: OUT_DRAIN");
 594                         return i;
 595                 default:
 596                         fatal("channel_find_open: bad channel type %d", c->type);
 597                         /* NOTREACHED */
 598                 }
 599         }
 600         return -1;
 601 }
 602
 603
 604 /*
 605  * Returns a message describing the currently open forwarded connections,
 606  * suitable for sending to the client.  The message contains crlf pairs for
 607  * newlines.
 608  */
 609 char *
 610 channel_open_message(void)
 611 {
 612         Buffer buffer;
 613         Channel *c;
 614         char buf[1024], *cp;
 615         u_int i;
 616
 617         buffer_init(&buffer);
 618         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 619         buffer_append(&buffer, buf, strlen(buf));
 620         for (i = 0; i < channels_alloc; i++) {
 621                 c = channels[i];
 622                 if (c == NULL)
 623                         continue;
 624                 switch (c->type) {
 625                 case SSH_CHANNEL_X11_LISTENER:
 626                 case SSH_CHANNEL_PORT_LISTENER:
 627                 case SSH_CHANNEL_RPORT_LISTENER:
 628                 case SSH_CHANNEL_CLOSED:
 629                 case SSH_CHANNEL_AUTH_SOCKET:
 630                 case SSH_CHANNEL_ZOMBIE:
 631                 case SSH_CHANNEL_MUX_CLIENT:
 632                 case SSH_CHANNEL_MUX_LISTENER:
 633                         continue;
 634                 case SSH_CHANNEL_LARVAL:
 635                 case SSH_CHANNEL_OPENING:
 636                 case SSH_CHANNEL_CONNECTING:
 637                 case SSH_CHANNEL_DYNAMIC:
 638                 case SSH_CHANNEL_OPEN:
 639                 case SSH_CHANNEL_X11_OPEN:
 640                 case SSH_CHANNEL_INPUT_DRAINING:
 641                 case SSH_CHANNEL_OUTPUT_DRAINING:
 642                         snprintf(buf, sizeof buf,
 643                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cc %d)\r\n",
 644                             c->self, c->remote_name,
 645                             c->type, c->remote_id,
 646                             c->istate, buffer_len(&c->input),
 647                             c->ostate, buffer_len(&c->output),
 648                             c->rfd, c->wfd, c->ctl_chan);
 649                         buffer_append(&buffer, buf, strlen(buf));
 650                         continue;
 651                 default:
 652                         fatal("channel_open_message: bad channel type %d", c->type);
 653                         /* NOTREACHED */
 654                 }
 655         }
 656         buffer_append(&buffer, "\0", 1);
 657         cp = xstrdup(buffer_ptr(&buffer));
 658         buffer_free(&buffer);
 659         return cp;
 660 }
 661
 662 void
 663 channel_send_open(int id)
 664 {
 665         Channel *c = channel_lookup(id);
 666
 667         if (c == NULL) {
 668                 logit("channel_send_open: %d: bad id", id);
 669                 return;
 670         }
 671         debug2("channel %d: send open", id);
 672         packet_start(SSH2_MSG_CHANNEL_OPEN);
 673         packet_put_cstring(c->ctype);
 674         packet_put_int(c->self);
 675         packet_put_int(c->local_window);
 676         packet_put_int(c->local_maxpacket);
 677         packet_send();
 678 }
 679
 680 void
 681 channel_request_start(int id, char *service, int wantconfirm)
 682 {
 683         Channel *c = channel_lookup(id);
 684
 685         if (c == NULL) {
 686                 logit("channel_request_start: %d: unknown channel id", id);
 687                 return;
 688         }
 689         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 690         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 691         packet_put_int(c->remote_id);
 692         packet_put_cstring(service);
 693         packet_put_char(wantconfirm);
 694 }
 695
 696 void
 697 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 698     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 699 {
 700         struct channel_confirm *cc;
 701         Channel *c;
 702
 703         if ((c = channel_lookup(id)) == NULL)
 704                 fatal("channel_register_expect: %d: bad id", id);
 705
 706         cc = xmalloc(sizeof(*cc));
 707         cc->cb = cb;
 708         cc->abandon_cb = abandon_cb;
 709         cc->ctx = ctx;
 710         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 711 }
 712
 713 void
 714 channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
 715 {
 716         Channel *c = channel_lookup(id);
 717
 718         if (c == NULL) {
 719                 logit("channel_register_open_confirm: %d: bad id", id);
 720                 return;
 721         }
 722         c->open_confirm = fn;
 723         c->open_confirm_ctx = ctx;
 724 }
 725
 726 void
 727 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 728 {
 729         Channel *c = channel_by_id(id);
 730
 731         if (c == NULL) {
 732                 logit("channel_register_cleanup: %d: bad id", id);
 733                 return;
 734         }
 735         c->detach_user = fn;
 736         c->detach_close = do_close;
 737 }
 738
 739 void
 740 channel_cancel_cleanup(int id)
 741 {
 742         Channel *c = channel_by_id(id);
 743
 744         if (c == NULL) {
 745                 logit("channel_cancel_cleanup: %d: bad id", id);
 746                 return;
 747         }
 748         c->detach_user = NULL;
 749         c->detach_close = 0;
 750 }
 751
 752 void
 753 channel_register_filter(int id, channel_infilter_fn *ifn,
 754     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 755 {
 756         Channel *c = channel_lookup(id);
 757
 758         if (c == NULL) {
 759                 logit("channel_register_filter: %d: bad id", id);
 760                 return;
 761         }
 762         c->input_filter = ifn;
 763         c->output_filter = ofn;
 764         c->filter_ctx = ctx;
 765         c->filter_cleanup = cfn;
 766 }
 767
 768 void
 769 channel_set_fds(int id, int rfd, int wfd, int efd,
 770     int extusage, int nonblock, int is_tty, u_int window_max)
 771 {
 772         Channel *c = channel_lookup(id);
 773
 774         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 775                 fatal("channel_activate for non-larval channel %d.", id);
 776         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 777         c->type = SSH_CHANNEL_OPEN;
 778         c->local_window = c->local_window_max = window_max;
 779         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 780         packet_put_int(c->remote_id);
 781         packet_put_int(c->local_window);
 782         packet_send();
 783 }
 784
 785 /*
 786  * 'channel_pre*' are called just before select() to add any bits relevant to
 787  * channels in the select bitmasks.
 788  */
 789 /*
 790  * 'channel_post*': perform any appropriate operations for channels which
 791  * have events pending.
 792  */
 793 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 794 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 795 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 796
 797 /* ARGSUSED */
 798 static void
 799 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 800 {
 801         FD_SET(c->sock, readset);
 802 }
 803
 804 /* ARGSUSED */
 805 static void
 806 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 807 {
 808         debug3("channel %d: waiting for connection", c->self);
 809         FD_SET(c->sock, writeset);
 810 }
 811
 812 static void
 813 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 814 {
 815         if (buffer_len(&c->input) < packet_get_maxsize())
 816                 FD_SET(c->sock, readset);
 817         if (buffer_len(&c->output) > 0)
 818                 FD_SET(c->sock, writeset);
 819 }
 820
 821 int channel_tcpwinsz () {
 822         u_int32_t tcpwinsz = 0;
 823         socklen_t optsz = sizeof(tcpwinsz);
 824         int ret = -1;
 825
 826         /* if we aren't on a socket return 128KB*/
 827         if(!packet_connection_is_on_socket())
 828             return(128*1024);
 829         ret = getsockopt(packet_get_connection_in(),
 830                          SOL_SOCKET, SO_RCVBUF, &tcpwinsz, &optsz);
 831         /* return no more than 64MB */
 832         if ((ret == 0) && tcpwinsz > BUFFER_MAX_LEN_HPN)
 833             tcpwinsz = BUFFER_MAX_LEN_HPN;
 834         debug2("tcpwinsz: %d for connection: %d", tcpwinsz,
 835                packet_get_connection_in());
 836         return(tcpwinsz);
 837 }
 838
 839 static void
 840 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 841 {
 842         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 843
 844         /* check buffer limits */
 845         if ((!c->tcpwinsz) || (c->dynamic_window > 0))
 846             c->tcpwinsz = channel_tcpwinsz();
 847
 848         limit = MIN(limit, 2 * c->tcpwinsz);
 849
 850         if (c->istate == CHAN_INPUT_OPEN &&
 851             limit > 0 &&
 852             buffer_len(&c->input) < limit &&
 853             buffer_check_alloc(&c->input, CHAN_RBUF))
 854                 FD_SET(c->rfd, readset);
 855         if (c->ostate == CHAN_OUTPUT_OPEN ||
 856             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 857                 if (buffer_len(&c->output) > 0) {
 858                         FD_SET(c->wfd, writeset);
 859                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 860                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 861                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 862                                     c->self, c->efd, buffer_len(&c->extended));
 863                         else
 864                                 chan_obuf_empty(c);
 865                 }
 866         }
 867         /** XXX check close conditions, too */
 868         if (compat20 && c->efd != -1 &&
 869             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 870                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 871                     buffer_len(&c->extended) > 0)
 872                         FD_SET(c->efd, writeset);
 873                 else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
 874                     (c->extended_usage == CHAN_EXTENDED_READ ||
 875                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
 876                     buffer_len(&c->extended) < c->remote_window)
 877                         FD_SET(c->efd, readset);
 878         }
 879         /* XXX: What about efd? races? */
 880 }
 881
 882 /* ARGSUSED */
 883 static void
 884 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 885 {
 886         if (buffer_len(&c->input) == 0) {
 887                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 888                 packet_put_int(c->remote_id);
 889                 packet_send();
 890                 c->type = SSH_CHANNEL_CLOSED;
 891                 debug2("channel %d: closing after input drain.", c->self);
 892         }
 893 }
 894
 895 /* ARGSUSED */
 896 static void
 897 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 898 {
 899         if (buffer_len(&c->output) == 0)
 900                 chan_mark_dead(c);
 901         else
 902                 FD_SET(c->sock, writeset);
 903 }
 904
 905 /*
 906  * This is a special state for X11 authentication spoofing.  An opened X11
 907  * connection (when authentication spoofing is being done) remains in this
 908  * state until the first packet has been completely read.  The authentication
 909  * data in that packet is then substituted by the real data if it matches the
 910  * fake data, and the channel is put into normal mode.
 911  * XXX All this happens at the client side.
 912  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 913  */
 914 static int
 915 x11_open_helper(Buffer *b)
 916 {
 917         u_char *ucp;
 918         u_int proto_len, data_len;
 919
 920         /* Check if the fixed size part of the packet is in buffer. */
 921         if (buffer_len(b) < 12)
 922                 return 0;
 923
 924         /* Parse the lengths of variable-length fields. */
 925         ucp = buffer_ptr(b);
 926         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 927                 proto_len = 256 * ucp[6] + ucp[7];
 928                 data_len = 256 * ucp[8] + ucp[9];
 929         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 930                 proto_len = ucp[6] + 256 * ucp[7];
 931                 data_len = ucp[8] + 256 * ucp[9];
 932         } else {
 933                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 934                     ucp[0]);
 935                 return -1;
 936         }
 937
 938         /* Check if the whole packet is in buffer. */
 939         if (buffer_len(b) <
 940             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 941                 return 0;
 942
 943         /* Check if authentication protocol matches. */
 944         if (proto_len != strlen(x11_saved_proto) ||
 945             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 946                 debug2("X11 connection uses different authentication protocol.");
 947                 return -1;
 948         }
 949         /* Check if authentication data matches our fake data. */
 950         if (data_len != x11_fake_data_len ||
 951             timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
 952                 x11_fake_data, x11_fake_data_len) != 0) {
 953                 debug2("X11 auth data does not match fake data.");
 954                 return -1;
 955         }
 956         /* Check fake data length */
 957         if (x11_fake_data_len != x11_saved_data_len) {
 958                 error("X11 fake_data_len %d != saved_data_len %d",
 959                     x11_fake_data_len, x11_saved_data_len);
 960                 return -1;
 961         }
 962         /*
 963          * Received authentication protocol and data match
 964          * our fake data. Substitute the fake data with real
 965          * data.
 966          */
 967         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 968             x11_saved_data, x11_saved_data_len);
 969         return 1;
 970 }
 971
 972 static void
 973 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 974 {
 975         int ret = x11_open_helper(&c->output);
 976
 977         if (ret == 1) {
 978                 /* Start normal processing for the channel. */
 979                 c->type = SSH_CHANNEL_OPEN;
 980                 channel_pre_open_13(c, readset, writeset);
 981         } else if (ret == -1) {
 982                 /*
 983                  * We have received an X11 connection that has bad
 984                  * authentication information.
 985                  */
 986                 logit("X11 connection rejected because of wrong authentication.");
 987                 buffer_clear(&c->input);
 988                 buffer_clear(&c->output);
 989                 channel_close_fd(&c->sock);
 990                 c->sock = -1;
 991                 c->type = SSH_CHANNEL_CLOSED;
 992                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 993                 packet_put_int(c->remote_id);
 994                 packet_send();
 995         }
 996 }
 997
 998 static void
 999 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
1000 {
1001         int ret = x11_open_helper(&c->output);
1002
1003         /* c->force_drain = 1; */
1004
1005         if (ret == 1) {
1006                 c->type = SSH_CHANNEL_OPEN;
1007                 channel_pre_open(c, readset, writeset);
1008         } else if (ret == -1) {
1009                 logit("X11 connection rejected because of wrong authentication.");
1010                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
1011                 chan_read_failed(c);
1012                 buffer_clear(&c->input);
1013                 chan_ibuf_empty(c);
1014                 buffer_clear(&c->output);
1015                 /* for proto v1, the peer will send an IEOF */
1016                 if (compat20)
1017                         chan_write_failed(c);
1018                 else
1019                         c->type = SSH_CHANNEL_OPEN;
1020                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
1021         }
1022 }
1023
1024 static void
1025 channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1026 {
1027         if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
1028             buffer_check_alloc(&c->input, CHAN_RBUF))
1029                 FD_SET(c->rfd, readset);
1030         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1031                 /* clear buffer immediately (discard any partial packet) */
1032                 buffer_clear(&c->input);
1033                 chan_ibuf_empty(c);
1034                 /* Start output drain. XXX just kill chan? */
1035                 chan_rcvd_oclose(c);
1036         }
1037         if (c->ostate == CHAN_OUTPUT_OPEN ||
1038             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
1039                 if (buffer_len(&c->output) > 0)
1040                         FD_SET(c->wfd, writeset);
1041                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
1042                         chan_obuf_empty(c);
1043         }
1044 }
1045
1046 /* try to decode a socks4 header */
1047 /* ARGSUSED */
1048 static int
1049 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1050 {
1051         char *p, *host;
1052         u_int len, have, i, found, need;
1053         char username[256];
1054         struct {
1055                 u_int8_t version;
1056                 u_int8_t command;
1057                 u_int16_t dest_port;
1058                 struct in_addr dest_addr;
1059         } s4_req, s4_rsp;
1060
1061         debug2("channel %d: decode socks4", c->self);
1062
1063         have = buffer_len(&c->input);
1064         len = sizeof(s4_req);
1065         if (have < len)
1066                 return 0;
1067         p = buffer_ptr(&c->input);
1068
1069         need = 1;
1070         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1071         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1072                 debug2("channel %d: socks4a request", c->self);
1073                 /* ... and needs an extra string (the hostname) */
1074                 need = 2;
1075         }
1076         /* Check for terminating NUL on the string(s) */
1077         for (found = 0, i = len; i < have; i++) {
1078                 if (p[i] == '\0') {
1079                         found++;
1080                         if (found == need)
1081                                 break;
1082                 }
1083                 if (i > 1024) {
1084                         /* the peer is probably sending garbage */
1085                         debug("channel %d: decode socks4: too long",
1086                             c->self);
1087                         return -1;
1088                 }
1089         }
1090         if (found < need)
1091                 return 0;
1092         buffer_get(&c->input, (char *)&s4_req.version, 1);
1093         buffer_get(&c->input, (char *)&s4_req.command, 1);
1094         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1095         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1096         have = buffer_len(&c->input);
1097         p = buffer_ptr(&c->input);
1098         len = strlen(p);
1099         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1100         len++;                                  /* trailing '\0' */
1101         if (len > have)
1102                 fatal("channel %d: decode socks4: len %d > have %d",
1103                     c->self, len, have);
1104         strlcpy(username, p, sizeof(username));
1105         buffer_consume(&c->input, len);
1106
1107         if (c->path != NULL) {
1108                 xfree(c->path);
1109                 c->path = NULL;
1110         }
1111         if (need == 1) {                        /* SOCKS4: one string */
1112                 host = inet_ntoa(s4_req.dest_addr);
1113                 c->path = xstrdup(host);
1114         } else {                                /* SOCKS4A: two strings */
1115                 have = buffer_len(&c->input);
1116                 p = buffer_ptr(&c->input);
1117                 len = strlen(p);
1118                 debug2("channel %d: decode socks4a: host %s/%d",
1119                     c->self, p, len);
1120                 len++;                          /* trailing '\0' */
1121                 if (len > have)
1122                         fatal("channel %d: decode socks4a: len %d > have %d",
1123                             c->self, len, have);
1124                 if (len > NI_MAXHOST) {
1125                         error("channel %d: hostname \"%.100s\" too long",
1126                             c->self, p);
1127                         return -1;
1128                 }
1129                 c->path = xstrdup(p);
1130                 buffer_consume(&c->input, len);
1131         }
1132         c->host_port = ntohs(s4_req.dest_port);
1133
1134         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1135             c->self, c->path, c->host_port, s4_req.command);
1136
1137         if (s4_req.command != 1) {
1138                 debug("channel %d: cannot handle: %s cn %d",
1139                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1140                 return -1;
1141         }
1142         s4_rsp.version = 0;                     /* vn: 0 for reply */
1143         s4_rsp.command = 90;                    /* cd: req granted */
1144         s4_rsp.dest_port = 0;                   /* ignored */
1145         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1146         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1147         return 1;
1148 }
1149
1150 /* try to decode a socks5 header */
1151 #define SSH_SOCKS5_AUTHDONE     0x1000
1152 #define SSH_SOCKS5_NOAUTH       0x00
1153 #define SSH_SOCKS5_IPV4         0x01
1154 #define SSH_SOCKS5_DOMAIN       0x03
1155 #define SSH_SOCKS5_IPV6         0x04
1156 #define SSH_SOCKS5_CONNECT      0x01
1157 #define SSH_SOCKS5_SUCCESS      0x00
1158
1159 /* ARGSUSED */
1160 static int
1161 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1162 {
1163         struct {
1164                 u_int8_t version;
1165                 u_int8_t command;
1166                 u_int8_t reserved;
1167                 u_int8_t atyp;
1168         } s5_req, s5_rsp;
1169         u_int16_t dest_port;
1170         u_char *p, dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1171         u_int have, need, i, found, nmethods, addrlen, af;
1172
1173         debug2("channel %d: decode socks5", c->self);
1174         p = buffer_ptr(&c->input);
1175         if (p[0] != 0x05)
1176                 return -1;
1177         have = buffer_len(&c->input);
1178         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1179                 /* format: ver | nmethods | methods */
1180                 if (have < 2)
1181                         return 0;
1182                 nmethods = p[1];
1183                 if (have < nmethods + 2)
1184                         return 0;
1185                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1186                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1187                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1188                                 found = 1;
1189                                 break;
1190                         }
1191                 }
1192                 if (!found) {
1193                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1194                             c->self);
1195                         return -1;
1196                 }
1197                 buffer_consume(&c->input, nmethods + 2);
1198                 buffer_put_char(&c->output, 0x05);              /* version */
1199                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1200                 FD_SET(c->sock, writeset);
1201                 c->flags |= SSH_SOCKS5_AUTHDONE;
1202                 debug2("channel %d: socks5 auth done", c->self);
1203                 return 0;                               /* need more */
1204         }
1205         debug2("channel %d: socks5 post auth", c->self);
1206         if (have < sizeof(s5_req)+1)
1207                 return 0;                       /* need more */
1208         memcpy(&s5_req, p, sizeof(s5_req));
1209         if (s5_req.version != 0x05 ||
1210             s5_req.command != SSH_SOCKS5_CONNECT ||
1211             s5_req.reserved != 0x00) {
1212                 debug2("channel %d: only socks5 connect supported", c->self);
1213                 return -1;
1214         }
1215         switch (s5_req.atyp){
1216         case SSH_SOCKS5_IPV4:
1217                 addrlen = 4;
1218                 af = AF_INET;
1219                 break;
1220         case SSH_SOCKS5_DOMAIN:
1221                 addrlen = p[sizeof(s5_req)];
1222                 af = -1;
1223                 break;
1224         case SSH_SOCKS5_IPV6:
1225                 addrlen = 16;
1226                 af = AF_INET6;
1227                 break;
1228         default:
1229                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1230                 return -1;
1231         }
1232         need = sizeof(s5_req) + addrlen + 2;
1233         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1234                 need++;
1235         if (have < need)
1236                 return 0;
1237         buffer_consume(&c->input, sizeof(s5_req));
1238         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1239                 buffer_consume(&c->input, 1);    /* host string length */
1240         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1241         buffer_get(&c->input, (char *)&dest_port, 2);
1242         dest_addr[addrlen] = '\0';
1243         if (c->path != NULL) {
1244                 xfree(c->path);
1245                 c->path = NULL;
1246         }
1247         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1248                 if (addrlen >= NI_MAXHOST) {
1249                         error("channel %d: dynamic request: socks5 hostname "
1250                             "\"%.100s\" too long", c->self, dest_addr);
1251                         return -1;
1252                 }
1253                 c->path = xstrdup(dest_addr);
1254         } else {
1255                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1256                         return -1;
1257                 c->path = xstrdup(ntop);
1258         }
1259         c->host_port = ntohs(dest_port);
1260
1261         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1262             c->self, c->path, c->host_port, s5_req.command);
1263
1264         s5_rsp.version = 0x05;
1265         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1266         s5_rsp.reserved = 0;                    /* ignored */
1267         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1268         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1269         dest_port = 0;                          /* ignored */
1270
1271         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1272         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1273         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1274         return 1;
1275 }
1276
1277 Channel *
1278 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1279     int in, int out)
1280 {
1281         Channel *c;
1282
1283         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1284             port_to_connect);
1285
1286         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1287             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1288             0, "stdio-forward", /*nonblock*/0);
1289
1290         c->path = xstrdup(host_to_connect);
1291         c->host_port = port_to_connect;
1292         c->listening_port = 0;
1293         c->force_drain = 1;
1294
1295         channel_register_fds(c, in, out, -1, 0, 1, 0);
1296         port_open_helper(c, "direct-tcpip");
1297
1298         return c;
1299 }
1300
1301 /* dynamic port forwarding */
1302 static void
1303 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1304 {
1305         u_char *p;
1306         u_int have;
1307         int ret;
1308
1309         have = buffer_len(&c->input);
1310         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1311         /* buffer_dump(&c->input); */
1312         /* check if the fixed size part of the packet is in buffer. */
1313         if (have < 3) {
1314                 /* need more */
1315                 FD_SET(c->sock, readset);
1316                 return;
1317         }
1318         /* try to guess the protocol */
1319         p = buffer_ptr(&c->input);
1320         switch (p[0]) {
1321         case 0x04:
1322                 ret = channel_decode_socks4(c, readset, writeset);
1323                 break;
1324         case 0x05:
1325                 ret = channel_decode_socks5(c, readset, writeset);
1326                 break;
1327         default:
1328                 ret = -1;
1329                 break;
1330         }
1331         if (ret < 0) {
1332                 chan_mark_dead(c);
1333         } else if (ret == 0) {
1334                 debug2("channel %d: pre_dynamic: need more", c->self);
1335                 /* need more */
1336                 FD_SET(c->sock, readset);
1337         } else {
1338                 /* switch to the next state */
1339                 c->type = SSH_CHANNEL_OPENING;
1340                 port_open_helper(c, "direct-tcpip");
1341         }
1342 }
1343
1344 /* This is our fake X11 server socket. */
1345 /* ARGSUSED */
1346 static void
1347 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1348 {
1349         Channel *nc;
1350         struct sockaddr_storage addr;
1351         int newsock;
1352         socklen_t addrlen;
1353         char buf[16384], *remote_ipaddr;
1354         int remote_port;
1355
1356         if (FD_ISSET(c->sock, readset)) {
1357                 debug("X11 connection requested.");
1358                 addrlen = sizeof(addr);
1359                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1360                 if (c->single_connection) {
1361                         debug2("single_connection: closing X11 listener.");
1362                         channel_close_fd(&c->sock);
1363                         chan_mark_dead(c);
1364                 }
1365                 if (newsock < 0) {
1366                         error("accept: %.100s", strerror(errno));
1367                         return;
1368                 }
1369                 set_nodelay(newsock);
1370                 remote_ipaddr = get_peer_ipaddr(newsock);
1371                 remote_port = get_peer_port(newsock);
1372                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1373                     remote_ipaddr, remote_port);
1374
1375                 nc = channel_new("accepted x11 socket",
1376                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1377                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1378                 if (compat20) {
1379                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1380                         packet_put_cstring("x11");
1381                         packet_put_int(nc->self);
1382                         packet_put_int(nc->local_window_max);
1383                         packet_put_int(nc->local_maxpacket);
1384                         /* originator ipaddr and port */
1385                         packet_put_cstring(remote_ipaddr);
1386                         if (datafellows & SSH_BUG_X11FWD) {
1387                                 debug2("ssh2 x11 bug compat mode");
1388                         } else {
1389                                 packet_put_int(remote_port);
1390                         }
1391                         packet_send();
1392                 } else {
1393                         packet_start(SSH_SMSG_X11_OPEN);
1394                         packet_put_int(nc->self);
1395                         if (packet_get_protocol_flags() &
1396                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1397                                 packet_put_cstring(buf);
1398                         packet_send();
1399                 }
1400                 xfree(remote_ipaddr);
1401         }
1402 }
1403
1404 static void
1405 port_open_helper(Channel *c, char *rtype)
1406 {
1407         int direct;
1408         char buf[1024];
1409         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1410         int remote_port = get_peer_port(c->sock);
1411
1412         if (remote_port == -1) {
1413                 /* Fake addr/port to appease peers that validate it (Tectia) */
1414                 xfree(remote_ipaddr);
1415                 remote_ipaddr = xstrdup("127.0.0.1");
1416                 remote_port = 65535;
1417         }
1418
1419         direct = (strcmp(rtype, "direct-tcpip") == 0);
1420
1421         snprintf(buf, sizeof buf,
1422             "%s: listening port %d for %.100s port %d, "
1423             "connect from %.200s port %d",
1424             rtype, c->listening_port, c->path, c->host_port,
1425             remote_ipaddr, remote_port);
1426
1427         xfree(c->remote_name);
1428         c->remote_name = xstrdup(buf);
1429
1430         if (compat20) {
1431                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1432                 packet_put_cstring(rtype);
1433                 packet_put_int(c->self);
1434                 packet_put_int(c->local_window_max);
1435                 packet_put_int(c->local_maxpacket);
1436                 if (direct) {
1437                         /* target host, port */
1438                         packet_put_cstring(c->path);
1439                         packet_put_int(c->host_port);
1440                 } else {
1441                         /* listen address, port */
1442                         packet_put_cstring(c->path);
1443                         packet_put_int(c->listening_port);
1444                 }
1445                 /* originator host and port */
1446                 packet_put_cstring(remote_ipaddr);
1447                 packet_put_int((u_int)remote_port);
1448                 packet_send();
1449         } else {
1450                 packet_start(SSH_MSG_PORT_OPEN);
1451                 packet_put_int(c->self);
1452                 packet_put_cstring(c->path);
1453                 packet_put_int(c->host_port);
1454                 if (packet_get_protocol_flags() &
1455                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1456                         packet_put_cstring(c->remote_name);
1457                 packet_send();
1458         }
1459         xfree(remote_ipaddr);
1460 }
1461
1462 static void
1463 channel_set_reuseaddr(int fd)
1464 {
1465         int on = 1;
1466
1467         /*
1468          * Set socket options.
1469          * Allow local port reuse in TIME_WAIT.
1470          */
1471         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1472                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1473 }
1474
1475 /*
1476  * This socket is listening for connections to a forwarded TCP/IP port.
1477  */
1478 /* ARGSUSED */
1479 static void
1480 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1481 {
1482         Channel *nc;
1483         struct sockaddr_storage addr;
1484         int newsock, nextstate;
1485         socklen_t addrlen;
1486         char *rtype;
1487
1488         if (FD_ISSET(c->sock, readset)) {
1489                 debug("Connection to port %d forwarding "
1490                     "to %.100s port %d requested.",
1491                     c->listening_port, c->path, c->host_port);
1492
1493                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1494                         nextstate = SSH_CHANNEL_OPENING;
1495                         rtype = "forwarded-tcpip";
1496                 } else {
1497                         if (c->host_port == 0) {
1498                                 nextstate = SSH_CHANNEL_DYNAMIC;
1499                                 rtype = "dynamic-tcpip";
1500                         } else {
1501                                 nextstate = SSH_CHANNEL_OPENING;
1502                                 rtype = "direct-tcpip";
1503                         }
1504                 }
1505
1506                 addrlen = sizeof(addr);
1507                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1508                 if (newsock < 0) {
1509                         error("accept: %.100s", strerror(errno));
1510                         return;
1511                 }
1512                 set_nodelay(newsock);
1513                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1514                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1515                 nc->listening_port = c->listening_port;
1516                 nc->host_port = c->host_port;
1517                 if (c->path != NULL)
1518                         nc->path = xstrdup(c->path);
1519
1520                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1521                         port_open_helper(nc, rtype);
1522         }
1523 }
1524
1525 /*
1526  * This is the authentication agent socket listening for connections from
1527  * clients.
1528  */
1529 /* ARGSUSED */
1530 static void
1531 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1532 {
1533         Channel *nc;
1534         int newsock;
1535         struct sockaddr_storage addr;
1536         socklen_t addrlen;
1537
1538         if (FD_ISSET(c->sock, readset)) {
1539                 addrlen = sizeof(addr);
1540                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1541                 if (newsock < 0) {
1542                         error("accept from auth socket: %.100s", strerror(errno));
1543                         return;
1544                 }
1545                 nc = channel_new("accepted auth socket",
1546                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1547                     c->local_window_max, c->local_maxpacket,
1548                     0, "accepted auth socket", 1);
1549                 if (compat20) {
1550                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1551                         packet_put_cstring("auth-agent@openssh.com");
1552                         packet_put_int(nc->self);
1553                         packet_put_int(c->local_window_max);
1554                         packet_put_int(c->local_maxpacket);
1555                 } else {
1556                         packet_start(SSH_SMSG_AGENT_OPEN);
1557                         packet_put_int(nc->self);
1558                 }
1559                 packet_send();
1560         }
1561 }
1562
1563 /* ARGSUSED */
1564 static void
1565 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1566 {
1567         int err = 0, sock;
1568         socklen_t sz = sizeof(err);
1569
1570         if (FD_ISSET(c->sock, writeset)) {
1571                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1572                         err = errno;
1573                         error("getsockopt SO_ERROR failed");
1574                 }
1575                 if (err == 0) {
1576                         debug("channel %d: connected to %s port %d",
1577                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1578                         channel_connect_ctx_free(&c->connect_ctx);
1579                         c->type = SSH_CHANNEL_OPEN;
1580                         if (compat20) {
1581                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1582                                 packet_put_int(c->remote_id);
1583                                 packet_put_int(c->self);
1584                                 packet_put_int(c->local_window);
1585                                 packet_put_int(c->local_maxpacket);
1586                         } else {
1587                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1588                                 packet_put_int(c->remote_id);
1589                                 packet_put_int(c->self);
1590                         }
1591                 } else {
1592                         debug("channel %d: connection failed: %s",
1593                             c->self, strerror(err));
1594                         /* Try next address, if any */
1595                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1596                                 close(c->sock);
1597                                 c->sock = c->rfd = c->wfd = sock;
1598                                 channel_max_fd = channel_find_maxfd();
1599                                 return;
1600                         }
1601                         /* Exhausted all addresses */
1602                         error("connect_to %.100s port %d: failed.",
1603                             c->connect_ctx.host, c->connect_ctx.port);
1604                         channel_connect_ctx_free(&c->connect_ctx);
1605                         if (compat20) {
1606                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1607                                 packet_put_int(c->remote_id);
1608                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1609                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1610                                         packet_put_cstring(strerror(err));
1611                                         packet_put_cstring("");
1612                                 }
1613                         } else {
1614                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1615                                 packet_put_int(c->remote_id);
1616                         }
1617                         chan_mark_dead(c);
1618                 }
1619                 packet_send();
1620         }
1621 }
1622
1623 /* ARGSUSED */
1624 static int
1625 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1626 {
1627         char buf[CHAN_RBUF];
1628         int len, force;
1629
1630         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1631         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1632                 errno = 0;
1633                 len = read(c->rfd, buf, sizeof(buf));
1634                 if (len < 0 && (errno == EINTR ||
1635                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1636                         return 1;
1637 #ifndef PTY_ZEROREAD
1638                 if (len <= 0) {
1639 #else
1640                 if ((!c->isatty && len <= 0) ||
1641                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1642 #endif
1643                         debug2("channel %d: read<=0 rfd %d len %d",
1644                             c->self, c->rfd, len);
1645                         if (c->type != SSH_CHANNEL_OPEN) {
1646                                 debug2("channel %d: not open", c->self);
1647                                 chan_mark_dead(c);
1648                                 return -1;
1649                         } else if (compat13) {
1650                                 buffer_clear(&c->output);
1651                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1652                                 debug2("channel %d: input draining.", c->self);
1653                         } else {
1654                                 chan_read_failed(c);
1655                         }
1656                         return -1;
1657                 }
1658                 if (c->input_filter != NULL) {
1659                         if (c->input_filter(c, buf, len) == -1) {
1660                                 debug2("channel %d: filter stops", c->self);
1661                                 chan_read_failed(c);
1662                         }
1663                 } else if (c->datagram) {
1664                         buffer_put_string(&c->input, buf, len);
1665                 } else {
1666                         buffer_append(&c->input, buf, len);
1667                 }
1668         }
1669         return 1;
1670 }
1671
1672 /* ARGSUSED */
1673 static int
1674 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1675 {
1676         struct termios tio;
1677         u_char *data = NULL, *buf;
1678         u_int dlen, olen = 0;
1679         int len;
1680
1681         /* Send buffered output data to the socket. */
1682         if (c->wfd != -1 &&
1683             FD_ISSET(c->wfd, writeset) &&
1684             buffer_len(&c->output) > 0) {
1685                 olen = buffer_len(&c->output);
1686                 if (c->output_filter != NULL) {
1687                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1688                                 debug2("channel %d: filter stops", c->self);
1689                                 if (c->type != SSH_CHANNEL_OPEN)
1690                                         chan_mark_dead(c);
1691                                 else
1692                                         chan_write_failed(c);
1693                                 return -1;
1694                         }
1695                 } else if (c->datagram) {
1696                         buf = data = buffer_get_string(&c->output, &dlen);
1697                 } else {
1698                         buf = data = buffer_ptr(&c->output);
1699                         dlen = buffer_len(&c->output);
1700                 }
1701
1702                 if (c->datagram) {
1703                         /* ignore truncated writes, datagrams might get lost */
1704                         len = write(c->wfd, buf, dlen);
1705                         xfree(data);
1706                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1707                             errno == EWOULDBLOCK))
1708                                 return 1;
1709                         if (len <= 0) {
1710                                 if (c->type != SSH_CHANNEL_OPEN)
1711                                         chan_mark_dead(c);
1712                                 else
1713                                         chan_write_failed(c);
1714                                 return -1;
1715                         }
1716                         goto out;
1717                 }
1718 #ifdef _AIX
1719                 /* XXX: Later AIX versions can't push as much data to tty */
1720                 if (compat20 && c->wfd_isatty)
1721                         dlen = MIN(dlen, 8*1024);
1722 #endif
1723
1724                 len = write(c->wfd, buf, dlen);
1725                 if (len < 0 &&
1726                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1727                         return 1;
1728                 if (len <= 0) {
1729                         if (c->type != SSH_CHANNEL_OPEN) {
1730                                 debug2("channel %d: not open", c->self);
1731                                 chan_mark_dead(c);
1732                                 return -1;
1733                         } else if (compat13) {
1734                                 buffer_clear(&c->output);
1735                                 debug2("channel %d: input draining.", c->self);
1736                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1737                         } else {
1738                                 chan_write_failed(c);
1739                         }
1740                         return -1;
1741                 }
1742 #ifndef BROKEN_TCGETATTR_ICANON
1743                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1744                         if (tcgetattr(c->wfd, &tio) == 0 &&
1745                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1746                                 /*
1747                                  * Simulate echo to reduce the impact of
1748                                  * traffic analysis. We need to match the
1749                                  * size of a SSH2_MSG_CHANNEL_DATA message
1750                                  * (4 byte channel id + buf)
1751                                  */
1752                                 packet_send_ignore(4 + len);
1753                                 packet_send();
1754                         }
1755                 }
1756 #endif
1757                 buffer_consume(&c->output, len);
1758         }
1759  out:
1760         if (compat20 && olen > 0)
1761                 c->local_consumed += olen - buffer_len(&c->output);
1762         return 1;
1763 }
1764
1765 static int
1766 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1767 {
1768         char buf[CHAN_RBUF];
1769         int len;
1770
1771 /** XXX handle drain efd, too */
1772         if (c->efd != -1) {
1773                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1774                     FD_ISSET(c->efd, writeset) &&
1775                     buffer_len(&c->extended) > 0) {
1776                         len = write(c->efd, buffer_ptr(&c->extended),
1777                             buffer_len(&c->extended));
1778                         debug2("channel %d: written %d to efd %d",
1779                             c->self, len, c->efd);
1780                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1781                             errno == EWOULDBLOCK))
1782                                 return 1;
1783                         if (len <= 0) {
1784                                 debug2("channel %d: closing write-efd %d",
1785                                     c->self, c->efd);
1786                                 channel_close_fd(&c->efd);
1787                         } else {
1788                                 buffer_consume(&c->extended, len);
1789                                 c->local_consumed += len;
1790                         }
1791                 } else if (c->efd != -1 &&
1792                     (c->extended_usage == CHAN_EXTENDED_READ ||
1793                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
1794                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1795                         len = read(c->efd, buf, sizeof(buf));
1796                         debug2("channel %d: read %d from efd %d",
1797                             c->self, len, c->efd);
1798                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1799                             errno == EWOULDBLOCK) && !c->detach_close)))
1800                                 return 1;
1801                         if (len <= 0) {
1802                                 debug2("channel %d: closing read-efd %d",
1803                                     c->self, c->efd);
1804                                 channel_close_fd(&c->efd);
1805                         } else {
1806                                 if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
1807                                         debug3("channel %d: discard efd",
1808                                             c->self);
1809                                 } else
1810                                         buffer_append(&c->extended, buf, len);
1811                         }
1812                 }
1813         }
1814         return 1;
1815 }
1816
1817 static int
1818 channel_check_window(Channel *c)
1819 {
1820         if (c->type == SSH_CHANNEL_OPEN &&
1821             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1822             ((c->local_window_max - c->local_window >
1823             c->local_maxpacket*3) ||
1824             c->local_window < c->local_window_max/2) &&
1825             c->local_consumed > 0) {
1826                 u_int addition = 0;
1827                 /* adjust max window size if we are in a dynamic environment */
1828                 if (c->dynamic_window && (c->tcpwinsz > c->local_window_max)) {
1829                         /* grow the window somewhat aggressively to maintain pressure */
1830                         addition = 1.5*(c->tcpwinsz - c->local_window_max);
1831                         c->local_window_max += addition;
1832                 }
1833                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1834                 packet_put_int(c->remote_id);
1835                 packet_put_int(c->local_consumed + addition);
1836                 packet_send();
1837                 debug2("channel %d: window %d sent adjust %d",
1838                     c->self, c->local_window,
1839                     c->local_consumed);
1840                 c->local_window += c->local_consumed + addition;
1841                 c->local_consumed = 0;
1842         }
1843         return 1;
1844 }
1845
1846 static void
1847 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1848 {
1849         channel_handle_rfd(c, readset, writeset);
1850         channel_handle_wfd(c, readset, writeset);
1851         if (!compat20)
1852                 return;
1853         channel_handle_efd(c, readset, writeset);
1854         channel_check_window(c);
1855 }
1856
1857 static u_int
1858 read_mux(Channel *c, u_int need)
1859 {
1860         char buf[CHAN_RBUF];
1861         int len;
1862         u_int rlen;
1863
1864         if (buffer_len(&c->input) < need) {
1865                 rlen = need - buffer_len(&c->input);
1866                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1867                 if (len <= 0) {
1868                         if (errno != EINTR && errno != EAGAIN) {
1869                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1870                                     c->self, c->rfd, len);
1871                                 chan_read_failed(c);
1872                                 return 0;
1873                         }
1874                 } else
1875                         buffer_append(&c->input, buf, len);
1876         }
1877         return buffer_len(&c->input);
1878 }
1879
1880 static void
1881 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1882 {
1883         u_int need;
1884         ssize_t len;
1885
1886         if (!compat20)
1887                 fatal("%s: entered with !compat20", __func__);
1888
1889         if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
1890             (c->istate == CHAN_INPUT_OPEN ||
1891             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1892                 /*
1893                  * Don't not read past the precise end of packets to
1894                  * avoid disrupting fd passing.
1895                  */
1896                 if (read_mux(c, 4) < 4) /* read header */
1897                         return;
1898                 need = get_u32(buffer_ptr(&c->input));
1899 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1900                 if (need > CHANNEL_MUX_MAX_PACKET) {
1901                         debug2("channel %d: packet too big %u > %u",
1902                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1903                         chan_rcvd_oclose(c);
1904                         return;
1905                 }
1906                 if (read_mux(c, need + 4) < need + 4) /* read body */
1907                         return;
1908                 if (c->mux_rcb(c) != 0) {
1909                         debug("channel %d: mux_rcb failed", c->self);
1910                         chan_mark_dead(c);
1911                         return;
1912                 }
1913         }
1914
1915         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1916             buffer_len(&c->output) > 0) {
1917                 len = write(c->wfd, buffer_ptr(&c->output),
1918                     buffer_len(&c->output));
1919                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1920                         return;
1921                 if (len <= 0) {
1922                         chan_mark_dead(c);
1923                         return;
1924                 }
1925                 buffer_consume(&c->output, len);
1926         }
1927 }
1928
1929 static void
1930 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1931 {
1932         Channel *nc;
1933         struct sockaddr_storage addr;
1934         socklen_t addrlen;
1935         int newsock;
1936         uid_t euid;
1937         gid_t egid;
1938
1939         if (!FD_ISSET(c->sock, readset))
1940                 return;
1941
1942         debug("multiplexing control connection");
1943
1944         /*
1945          * Accept connection on control socket
1946          */
1947         memset(&addr, 0, sizeof(addr));
1948         addrlen = sizeof(addr);
1949         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1950             &addrlen)) == -1) {
1951                 error("%s accept: %s", __func__, strerror(errno));
1952                 return;
1953         }
1954
1955         if (getpeereid(newsock, &euid, &egid) < 0) {
1956                 error("%s getpeereid failed: %s", __func__,
1957                     strerror(errno));
1958                 close(newsock);
1959                 return;
1960         }
1961         if ((euid != 0) && (getuid() != euid)) {
1962                 error("multiplex uid mismatch: peer euid %u != uid %u",
1963                     (u_int)euid, (u_int)getuid());
1964                 close(newsock);
1965                 return;
1966         }
1967         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
1968             newsock, newsock, -1, c->local_window_max,
1969             c->local_maxpacket, 0, "mux-control", 1);
1970         nc->mux_rcb = c->mux_rcb;
1971         debug3("%s: new mux channel %d fd %d", __func__,
1972             nc->self, nc->sock);
1973         /* establish state */
1974         nc->mux_rcb(nc);
1975         /* mux state transitions must not elicit protocol messages */
1976         nc->flags |= CHAN_LOCAL;
1977 }
1978
1979 /* ARGSUSED */
1980 static void
1981 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1982 {
1983         int len;
1984
1985         /* Send buffered output data to the socket. */
1986         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1987                 len = write(c->sock, buffer_ptr(&c->output),
1988                             buffer_len(&c->output));
1989                 if (len <= 0)
1990                         buffer_clear(&c->output);
1991                 else
1992                         buffer_consume(&c->output, len);
1993         }
1994 }
1995
1996 static void
1997 channel_handler_init_20(void)
1998 {
1999         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2000         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2001         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2002         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
2003         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2004         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2005         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2006         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2007         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
2008         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
2009
2010         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2011         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2012         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
2013         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2014         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2015         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2016         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2017         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
2018         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
2019 }
2020
2021 static void
2022 channel_handler_init_13(void)
2023 {
2024         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
2025         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
2026         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2027         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2028         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2029         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
2030         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
2031         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2032         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2033
2034         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2035         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2036         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2037         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2038         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
2039         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2040         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2041 }
2042
2043 static void
2044 channel_handler_init_15(void)
2045 {
2046         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2047         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2048         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2049         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2050         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2051         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2052         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2053
2054         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2055         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2056         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2057         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2058         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2059         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2060 }
2061
2062 static void
2063 channel_handler_init(void)
2064 {
2065         int i;
2066
2067         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2068                 channel_pre[i] = NULL;
2069                 channel_post[i] = NULL;
2070         }
2071         if (compat20)
2072                 channel_handler_init_20();
2073         else if (compat13)
2074                 channel_handler_init_13();
2075         else
2076                 channel_handler_init_15();
2077 }
2078
2079 /* gc dead channels */
2080 static void
2081 channel_garbage_collect(Channel *c)
2082 {
2083         if (c == NULL)
2084                 return;
2085         if (c->detach_user != NULL) {
2086                 if (!chan_is_dead(c, c->detach_close))
2087                         return;
2088                 debug2("channel %d: gc: notify user", c->self);
2089                 c->detach_user(c->self, NULL);
2090                 /* if we still have a callback */
2091                 if (c->detach_user != NULL)
2092                         return;
2093                 debug2("channel %d: gc: user detached", c->self);
2094         }
2095         if (!chan_is_dead(c, 1))
2096                 return;
2097         debug2("channel %d: garbage collecting", c->self);
2098         channel_free(c);
2099 }
2100
2101 static void
2102 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
2103 {
2104         static int did_init = 0;
2105         u_int i, oalloc;
2106         Channel *c;
2107
2108         if (!did_init) {
2109                 channel_handler_init();
2110                 did_init = 1;
2111         }
2112         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2113                 c = channels[i];
2114                 if (c == NULL)
2115                         continue;
2116                 if (c->delayed) {
2117                         if (ftab == channel_pre)
2118                                 c->delayed = 0;
2119                         else
2120                                 continue;
2121                 }
2122                 if (ftab[c->type] != NULL)
2123                         (*ftab[c->type])(c, readset, writeset);
2124                 channel_garbage_collect(c);
2125         }
2126 }
2127
2128 /*
2129  * Allocate/update select bitmasks and add any bits relevant to channels in
2130  * select bitmasks.
2131  */
2132 void
2133 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2134     u_int *nallocp, int rekeying)
2135 {
2136         u_int n, sz, nfdset;
2137
2138         n = MAX(*maxfdp, channel_max_fd);
2139
2140         nfdset = howmany(n+1, NFDBITS);
2141         /* Explicitly test here, because xrealloc isn't always called */
2142         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
2143                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2144         sz = nfdset * sizeof(fd_mask);
2145
2146         /* perhaps check sz < nalloc/2 and shrink? */
2147         if (*readsetp == NULL || sz > *nallocp) {
2148                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2149                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2150                 *nallocp = sz;
2151         }
2152         *maxfdp = n;
2153         memset(*readsetp, 0, sz);
2154         memset(*writesetp, 0, sz);
2155
2156         if (!rekeying)
2157                 channel_handler(channel_pre, *readsetp, *writesetp);
2158 }
2159
2160 /*
2161  * After select, perform any appropriate operations for channels which have
2162  * events pending.
2163  */
2164 void
2165 channel_after_select(fd_set *readset, fd_set *writeset)
2166 {
2167         channel_handler(channel_post, readset, writeset);
2168 }
2169
2170
2171 /* If there is data to send to the connection, enqueue some of it now. */
2172 int
2173 channel_output_poll(void)
2174 {
2175         Channel *c;
2176         u_int i, len;
2177         int packet_length = 0;
2178
2179         for (i = 0; i < channels_alloc; i++) {
2180                 c = channels[i];
2181                 if (c == NULL)
2182                         continue;
2183
2184                 /*
2185                  * We are only interested in channels that can have buffered
2186                  * incoming data.
2187                  */
2188                 if (compat13) {
2189                         if (c->type != SSH_CHANNEL_OPEN &&
2190                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2191                                 continue;
2192                 } else {
2193                         if (c->type != SSH_CHANNEL_OPEN)
2194                                 continue;
2195                 }
2196                 if (compat20 &&
2197                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2198                         /* XXX is this true? */
2199                         debug3("channel %d: will not send data after close", c->self);
2200                         continue;
2201                 }
2202
2203                 /* Get the amount of buffered data for this channel. */
2204                 if ((c->istate == CHAN_INPUT_OPEN ||
2205                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2206                     (len = buffer_len(&c->input)) > 0) {
2207                         if (c->datagram) {
2208                                 if (len > 0) {
2209                                         u_char *data;
2210                                         u_int dlen;
2211
2212                                         data = buffer_get_string(&c->input,
2213                                             &dlen);
2214                                         if (dlen > c->remote_window ||
2215                                             dlen > c->remote_maxpacket) {
2216                                                 debug("channel %d: datagram "
2217                                                     "too big for channel",
2218                                                     c->self);
2219                                                 xfree(data);
2220                                                 continue;
2221                                         }
2222                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2223                                         packet_put_int(c->remote_id);
2224                                         packet_put_string(data, dlen);
2225                                         packet_length = packet_send();
2226                                         c->remote_window -= dlen + 4;
2227                                         xfree(data);
2228                                 }
2229                                 continue;
2230                         }
2231                         /*
2232                          * Send some data for the other side over the secure
2233                          * connection.
2234                          */
2235                         if (compat20) {
2236                                 if (len > c->remote_window)
2237                                         len = c->remote_window;
2238                                 if (len > c->remote_maxpacket)
2239                                         len = c->remote_maxpacket;
2240                         } else {
2241                                 if (packet_is_interactive()) {
2242                                         if (len > 1024)
2243                                                 len = 512;
2244                                 } else {
2245                                         /* Keep the packets at reasonable size. */
2246                                         if (len > packet_get_maxsize()/2)
2247                                                 len = packet_get_maxsize()/2;
2248                                 }
2249                         }
2250                         if (len > 0) {
2251                                 packet_start(compat20 ?
2252                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2253                                 packet_put_int(c->remote_id);
2254                                 packet_put_string(buffer_ptr(&c->input), len);
2255                                 packet_length = packet_send();
2256                                 buffer_consume(&c->input, len);
2257                                 c->remote_window -= len;
2258                         }
2259                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2260                         if (compat13)
2261                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2262                         /*
2263                          * input-buffer is empty and read-socket shutdown:
2264                          * tell peer, that we will not send more data: send IEOF.
2265                          * hack for extended data: delay EOF if EFD still in use.
2266                          */
2267                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2268                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2269                                     c->self, c->efd, buffer_len(&c->extended));
2270                         else
2271                                 chan_ibuf_empty(c);
2272                 }
2273                 /* Send extended data, i.e. stderr */
2274                 if (compat20 &&
2275                     !(c->flags & CHAN_EOF_SENT) &&
2276                     c->remote_window > 0 &&
2277                     (len = buffer_len(&c->extended)) > 0 &&
2278                     c->extended_usage == CHAN_EXTENDED_READ) {
2279                         debug2("channel %d: rwin %u elen %u euse %d",
2280                             c->self, c->remote_window, buffer_len(&c->extended),
2281                             c->extended_usage);
2282                         if (len > c->remote_window)
2283                                 len = c->remote_window;
2284                         if (len > c->remote_maxpacket)
2285                                 len = c->remote_maxpacket;
2286                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2287                         packet_put_int(c->remote_id);
2288                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2289                         packet_put_string(buffer_ptr(&c->extended), len);
2290                         packet_length = packet_send();
2291                         buffer_consume(&c->extended, len);
2292                         c->remote_window -= len;
2293                         debug2("channel %d: sent ext data %d", c->self, len);
2294                 }
2295         }
2296         return (packet_length);
2297 }
2298
2299
2300 /* -- protocol input */
2301
2302 /* ARGSUSED */
2303 void
2304 channel_input_data(int type, u_int32_t seq, void *ctxt)
2305 {
2306         int id;
2307         char *data;
2308         u_int data_len, win_len;
2309         Channel *c;
2310
2311         /* Get the channel number and verify it. */
2312         id = packet_get_int();
2313         c = channel_lookup(id);
2314         if (c == NULL)
2315                 packet_disconnect("Received data for nonexistent channel %d.", id);
2316
2317         /* Ignore any data for non-open channels (might happen on close) */
2318         if (c->type != SSH_CHANNEL_OPEN &&
2319             c->type != SSH_CHANNEL_X11_OPEN)
2320                 return;
2321
2322         /* Get the data. */
2323         data = packet_get_string_ptr(&data_len);
2324         win_len = data_len;
2325         if (c->datagram)
2326                 win_len += 4;  /* string length header */
2327
2328         /*
2329          * Ignore data for protocol > 1.3 if output end is no longer open.
2330          * For protocol 2 the sending side is reducing its window as it sends
2331          * data, so we must 'fake' consumption of the data in order to ensure
2332          * that window updates are sent back.  Otherwise the connection might
2333          * deadlock.
2334          */
2335         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2336                 if (compat20) {
2337                         c->local_window -= win_len;
2338                         c->local_consumed += win_len;
2339                 }
2340                 return;
2341         }
2342
2343         if (compat20) {
2344                 if (win_len > c->local_maxpacket) {
2345                         logit("channel %d: rcvd big packet %d, maxpack %d",
2346                             c->self, win_len, c->local_maxpacket);
2347                 }
2348                 if (win_len > c->local_window) {
2349                         logit("channel %d: rcvd too much data %d, win %d",
2350                             c->self, win_len, c->local_window);
2351                         return;
2352                 }
2353                 c->local_window -= win_len;
2354         }
2355         if (c->datagram)
2356                 buffer_put_string(&c->output, data, data_len);
2357         else
2358                 buffer_append(&c->output, data, data_len);
2359         packet_check_eom();
2360 }
2361
2362 /* ARGSUSED */
2363 void
2364 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2365 {
2366         int id;
2367         char *data;
2368         u_int data_len, tcode;
2369         Channel *c;
2370
2371         /* Get the channel number and verify it. */
2372         id = packet_get_int();
2373         c = channel_lookup(id);
2374
2375         if (c == NULL)
2376                 packet_disconnect("Received extended_data for bad channel %d.", id);
2377         if (c->type != SSH_CHANNEL_OPEN) {
2378                 logit("channel %d: ext data for non open", id);
2379                 return;
2380         }
2381         if (c->flags & CHAN_EOF_RCVD) {
2382                 if (datafellows & SSH_BUG_EXTEOF)
2383                         debug("channel %d: accepting ext data after eof", id);
2384                 else
2385                         packet_disconnect("Received extended_data after EOF "
2386                             "on channel %d.", id);
2387         }
2388         tcode = packet_get_int();
2389         if (c->efd == -1 ||
2390             c->extended_usage != CHAN_EXTENDED_WRITE ||
2391             tcode != SSH2_EXTENDED_DATA_STDERR) {
2392                 logit("channel %d: bad ext data", c->self);
2393                 return;
2394         }
2395         data = packet_get_string(&data_len);
2396         packet_check_eom();
2397         if (data_len > c->local_window) {
2398                 logit("channel %d: rcvd too much extended_data %d, win %d",
2399                     c->self, data_len, c->local_window);
2400                 xfree(data);
2401                 return;
2402         }
2403         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2404         c->local_window -= data_len;
2405         buffer_append(&c->extended, data, data_len);
2406         xfree(data);
2407 }
2408
2409 /* ARGSUSED */
2410 void
2411 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2412 {
2413         int id;
2414         Channel *c;
2415
2416         id = packet_get_int();
2417         packet_check_eom();
2418         c = channel_lookup(id);
2419         if (c == NULL)
2420                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2421         chan_rcvd_ieof(c);
2422
2423         /* XXX force input close */
2424         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2425                 debug("channel %d: FORCE input drain", c->self);
2426                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2427                 if (buffer_len(&c->input) == 0)
2428                         chan_ibuf_empty(c);
2429         }
2430
2431 }
2432
2433 /* ARGSUSED */
2434 void
2435 channel_input_close(int type, u_int32_t seq, void *ctxt)
2436 {
2437         int id;
2438         Channel *c;
2439
2440         id = packet_get_int();
2441         packet_check_eom();
2442         c = channel_lookup(id);
2443         if (c == NULL)
2444                 packet_disconnect("Received close for nonexistent channel %d.", id);
2445
2446         /*
2447          * Send a confirmation that we have closed the channel and no more
2448          * data is coming for it.
2449          */
2450         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2451         packet_put_int(c->remote_id);
2452         packet_send();
2453
2454         /*
2455          * If the channel is in closed state, we have sent a close request,
2456          * and the other side will eventually respond with a confirmation.
2457          * Thus, we cannot free the channel here, because then there would be
2458          * no-one to receive the confirmation.  The channel gets freed when
2459          * the confirmation arrives.
2460          */
2461         if (c->type != SSH_CHANNEL_CLOSED) {
2462                 /*
2463                  * Not a closed channel - mark it as draining, which will
2464                  * cause it to be freed later.
2465                  */
2466                 buffer_clear(&c->input);
2467                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2468         }
2469 }
2470
2471 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2472 /* ARGSUSED */
2473 void
2474 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2475 {
2476         int id = packet_get_int();
2477         Channel *c = channel_lookup(id);
2478
2479         packet_check_eom();
2480         if (c == NULL)
2481                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2482         chan_rcvd_oclose(c);
2483 }
2484
2485 /* ARGSUSED */
2486 void
2487 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2488 {
2489         int id = packet_get_int();
2490         Channel *c = channel_lookup(id);
2491
2492         packet_check_eom();
2493         if (c == NULL)
2494                 packet_disconnect("Received close confirmation for "
2495                     "out-of-range channel %d.", id);
2496         if (c->type != SSH_CHANNEL_CLOSED)
2497                 packet_disconnect("Received close confirmation for "
2498                     "non-closed channel %d (type %d).", id, c->type);
2499         channel_free(c);
2500 }
2501
2502 /* ARGSUSED */
2503 void
2504 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2505 {
2506         int id, remote_id;
2507         Channel *c;
2508
2509         id = packet_get_int();
2510         c = channel_lookup(id);
2511
2512         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2513                 packet_disconnect("Received open confirmation for "
2514                     "non-opening channel %d.", id);
2515         remote_id = packet_get_int();
2516         /* Record the remote channel number and mark that the channel is now open. */
2517         c->remote_id = remote_id;
2518         c->type = SSH_CHANNEL_OPEN;
2519
2520         if (compat20) {
2521                 c->remote_window = packet_get_int();
2522                 c->remote_maxpacket = packet_get_int();
2523                 if (c->open_confirm) {
2524                         debug2("callback start");
2525                         c->open_confirm(c->self, 1, c->open_confirm_ctx);
2526                         debug2("callback done");
2527                 }
2528                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2529                     c->remote_window, c->remote_maxpacket);
2530         }
2531         packet_check_eom();
2532 }
2533
2534 static char *
2535 reason2txt(int reason)
2536 {
2537         switch (reason) {
2538         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2539                 return "administratively prohibited";
2540         case SSH2_OPEN_CONNECT_FAILED:
2541                 return "connect failed";
2542         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2543                 return "unknown channel type";
2544         case SSH2_OPEN_RESOURCE_SHORTAGE:
2545                 return "resource shortage";
2546         }
2547         return "unknown reason";
2548 }
2549
2550 /* ARGSUSED */
2551 void
2552 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2553 {
2554         int id, reason;
2555         char *msg = NULL, *lang = NULL;
2556         Channel *c;
2557
2558         id = packet_get_int();
2559         c = channel_lookup(id);
2560
2561         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2562                 packet_disconnect("Received open failure for "
2563                     "non-opening channel %d.", id);
2564         if (compat20) {
2565                 reason = packet_get_int();
2566                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2567                         msg  = packet_get_string(NULL);
2568                         lang = packet_get_string(NULL);
2569                 }
2570                 logit("channel %d: open failed: %s%s%s", id,
2571                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2572                 if (msg != NULL)
2573                         xfree(msg);
2574                 if (lang != NULL)
2575                         xfree(lang);
2576                 if (c->open_confirm) {
2577                         debug2("callback start");
2578                         c->open_confirm(c->self, 0, c->open_confirm_ctx);
2579                         debug2("callback done");
2580                 }
2581         }
2582         packet_check_eom();
2583         /* Schedule the channel for cleanup/deletion. */
2584         chan_mark_dead(c);
2585 }
2586
2587 /* ARGSUSED */
2588 void
2589 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2590 {
2591         Channel *c;
2592         int id;
2593         u_int adjust;
2594
2595         if (!compat20)
2596                 return;
2597
2598         /* Get the channel number and verify it. */
2599         id = packet_get_int();
2600         c = channel_lookup(id);
2601
2602         if (c == NULL) {
2603                 logit("Received window adjust for non-open channel %d.", id);
2604                 return;
2605         }
2606         adjust = packet_get_int();
2607         packet_check_eom();
2608         debug2("channel %d: rcvd adjust %u", id, adjust);
2609         c->remote_window += adjust;
2610 }
2611
2612 /* ARGSUSED */
2613 void
2614 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2615 {
2616         Channel *c = NULL;
2617         u_short host_port;
2618         char *host, *originator_string;
2619         int remote_id;
2620
2621         remote_id = packet_get_int();
2622         host = packet_get_string(NULL);
2623         host_port = packet_get_int();
2624
2625         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2626                 originator_string = packet_get_string(NULL);
2627         } else {
2628                 originator_string = xstrdup("unknown (remote did not supply name)");
2629         }
2630         packet_check_eom();
2631         c = channel_connect_to(host, host_port,
2632             "connected socket", originator_string);
2633         xfree(originator_string);
2634         xfree(host);
2635         if (c == NULL) {
2636                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2637                 packet_put_int(remote_id);
2638                 packet_send();
2639         } else
2640                 c->remote_id = remote_id;
2641 }
2642
2643 /* ARGSUSED */
2644 void
2645 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2646 {
2647         Channel *c;
2648         struct channel_confirm *cc;
2649         int id;
2650
2651         /* Reset keepalive timeout */
2652         packet_set_alive_timeouts(0);
2653
2654         id = packet_get_int();
2655         packet_check_eom();
2656
2657         debug2("channel_input_status_confirm: type %d id %d", type, id);
2658
2659         if ((c = channel_lookup(id)) == NULL) {
2660                 logit("channel_input_status_confirm: %d: unknown", id);
2661                 return;
2662         }
2663         ;
2664         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2665                 return;
2666         cc->cb(type, c, cc->ctx);
2667         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2668         bzero(cc, sizeof(*cc));
2669         xfree(cc);
2670 }
2671
2672 /* -- tcp forwarding */
2673
2674 void
2675 channel_set_af(int af)
2676 {
2677         IPv4or6 = af;
2678 }
2679
2680
2681 void
2682 channel_set_hpn(int external_hpn_disabled, int external_hpn_buffer_size)
2683 {
2684         hpn_disabled = external_hpn_disabled;
2685         hpn_buffer_size = external_hpn_buffer_size;
2686         debug("HPN Disabled: %d, HPN Buffer Size: %d", hpn_disabled, hpn_buffer_size);
2687 }
2688
2689 static int
2690 channel_setup_fwd_listener(int type, const char *listen_addr,
2691     u_short listen_port, int *allocated_listen_port,
2692     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2693 {
2694         Channel *c;
2695         int sock, r, success = 0, wildcard = 0, is_client;
2696         struct addrinfo hints, *ai, *aitop;
2697         const char *host, *addr;
2698         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2699         in_port_t *lport_p;
2700
2701         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2702             listen_addr : host_to_connect;
2703         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2704
2705         if (host == NULL) {
2706                 error("No forward host name.");
2707                 return 0;
2708         }
2709         if (strlen(host) >= NI_MAXHOST) {
2710                 error("Forward host name too long.");
2711                 return 0;
2712         }
2713
2714         /*
2715          * Determine whether or not a port forward listens to loopback,
2716          * specified address or wildcard. On the client, a specified bind
2717          * address will always override gateway_ports. On the server, a
2718          * gateway_ports of 1 (``yes'') will override the client's
2719          * specification and force a wildcard bind, whereas a value of 2
2720          * (``clientspecified'') will bind to whatever address the client
2721          * asked for.
2722          *
2723          * Special-case listen_addrs are:
2724          *
2725          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2726          * "" (empty string), "*"  -> wildcard v4/v6
2727          * "localhost"             -> loopback v4/v6
2728          */
2729         addr = NULL;
2730         if (listen_addr == NULL) {
2731                 /* No address specified: default to gateway_ports setting */
2732                 if (gateway_ports)
2733                         wildcard = 1;
2734         } else if (gateway_ports || is_client) {
2735                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2736                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2737                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2738                     (!is_client && gateway_ports == 1))
2739                         wildcard = 1;
2740                 else if (strcmp(listen_addr, "localhost") != 0)
2741                         addr = listen_addr;
2742         }
2743
2744         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2745             type, wildcard, (addr == NULL) ? "NULL" : addr);
2746
2747         /*
2748          * getaddrinfo returns a loopback address if the hostname is
2749          * set to NULL and hints.ai_flags is not AI_PASSIVE
2750          */
2751         memset(&hints, 0, sizeof(hints));
2752         hints.ai_family = IPv4or6;
2753         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2754         hints.ai_socktype = SOCK_STREAM;
2755         snprintf(strport, sizeof strport, "%d", listen_port);
2756         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2757                 if (addr == NULL) {
2758                         /* This really shouldn't happen */
2759                         packet_disconnect("getaddrinfo: fatal error: %s",
2760                             ssh_gai_strerror(r));
2761                 } else {
2762                         error("channel_setup_fwd_listener: "
2763                             "getaddrinfo(%.64s): %s", addr,
2764                             ssh_gai_strerror(r));
2765                 }
2766                 return 0;
2767         }
2768         if (allocated_listen_port != NULL)
2769                 *allocated_listen_port = 0;
2770         for (ai = aitop; ai; ai = ai->ai_next) {
2771                 switch (ai->ai_family) {
2772                 case AF_INET:
2773                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2774                             sin_port;
2775                         break;
2776                 case AF_INET6:
2777                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2778                             sin6_port;
2779                         break;
2780                 default:
2781                         continue;
2782                 }
2783                 /*
2784                  * If allocating a port for -R forwards, then use the
2785                  * same port for all address families.
2786                  */
2787                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2788                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2789                         *lport_p = htons(*allocated_listen_port);
2790
2791                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2792                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2793                         error("channel_setup_fwd_listener: getnameinfo failed");
2794                         continue;
2795                 }
2796                 /* Create a port to listen for the host. */
2797                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2798                 if (sock < 0) {
2799                         /* this is no error since kernel may not support ipv6 */
2800                         verbose("socket: %.100s", strerror(errno));
2801                         continue;
2802                 }
2803
2804                 channel_set_reuseaddr(sock);
2805                 if (ai->ai_family == AF_INET6)
2806                         sock_set_v6only(sock);
2807
2808                 debug("Local forwarding listening on %s port %s.",
2809                     ntop, strport);
2810
2811                 /* Bind the socket to the address. */
2812                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2813                         /* address can be in use ipv6 address is already bound */
2814                         if (!ai->ai_next)
2815                                 error("bind: %.100s", strerror(errno));
2816                         else
2817                                 verbose("bind: %.100s", strerror(errno));
2818
2819                         close(sock);
2820                         continue;
2821                 }
2822                 /* Start listening for connections on the socket. */
2823                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2824                         error("listen: %.100s", strerror(errno));
2825                         close(sock);
2826                         continue;
2827                 }
2828
2829                 /*
2830                  * listen_port == 0 requests a dynamically allocated port -
2831                  * record what we got.
2832                  */
2833                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2834                     allocated_listen_port != NULL &&
2835                     *allocated_listen_port == 0) {
2836                         *allocated_listen_port = get_sock_port(sock, 1);
2837                         debug("Allocated listen port %d",
2838                             *allocated_listen_port);
2839                 }
2840
2841                 /* Allocate a channel number for the socket. */
2842                 /* explicitly test for hpn disabled option. if true use smaller window size */
2843                 if (hpn_disabled)
2844                 c = channel_new("port listener", type, sock, sock, -1,
2845                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2846                     0, "port listener", 1);
2847                 else
2848                         c = channel_new("port listener", type, sock, sock, -1,
2849                           hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT,
2850                           0, "port listener", 1);
2851                 c->path = xstrdup(host);
2852                 c->host_port = port_to_connect;
2853                 c->listening_port = listen_port;
2854                 success = 1;
2855         }
2856         if (success == 0)
2857                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2858                     listen_port);
2859         freeaddrinfo(aitop);
2860         return success;
2861 }
2862
2863 int
2864 channel_cancel_rport_listener(const char *host, u_short port)
2865 {
2866         u_int i;
2867         int found = 0;
2868
2869         for (i = 0; i < channels_alloc; i++) {
2870                 Channel *c = channels[i];
2871
2872                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2873                     strcmp(c->path, host) == 0 && c->listening_port == port) {
2874                         debug2("%s: close channel %d", __func__, i);
2875                         channel_free(c);
2876                         found = 1;
2877                 }
2878         }
2879
2880         return (found);
2881 }
2882
2883 /* protocol local port fwd, used by ssh (and sshd in v1) */
2884 int
2885 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2886     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2887 {
2888         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2889             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2890             gateway_ports);
2891 }
2892
2893 /* protocol v2 remote port fwd, used by sshd */
2894 int
2895 channel_setup_remote_fwd_listener(const char *listen_address,
2896     u_short listen_port, int *allocated_listen_port, int gateway_ports)
2897 {
2898         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2899             listen_address, listen_port, allocated_listen_port,
2900             NULL, 0, gateway_ports);
2901 }
2902
2903 /*
2904  * Initiate forwarding of connections to port "port" on remote host through
2905  * the secure channel to host:port from local side.
2906  */
2907
2908 int
2909 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2910     const char *host_to_connect, u_short port_to_connect)
2911 {
2912         int type, success = 0;
2913
2914         /* Send the forward request to the remote side. */
2915         if (compat20) {
2916                 const char *address_to_bind;
2917                 if (listen_host == NULL) {
2918                         if (datafellows & SSH_BUG_RFWD_ADDR)
2919                                 address_to_bind = "127.0.0.1";
2920                         else
2921                                 address_to_bind = "localhost";
2922                 } else if (*listen_host == '\0' ||
2923                            strcmp(listen_host, "*") == 0) {
2924                         if (datafellows & SSH_BUG_RFWD_ADDR)
2925                                 address_to_bind = "0.0.0.0";
2926                         else
2927                                 address_to_bind = "";
2928                 } else
2929                         address_to_bind = listen_host;
2930
2931                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2932                 packet_put_cstring("tcpip-forward");
2933                 packet_put_char(1);                     /* boolean: want reply */
2934                 packet_put_cstring(address_to_bind);
2935                 packet_put_int(listen_port);
2936                 packet_send();
2937                 packet_write_wait();
2938                 /* Assume that server accepts the request */
2939                 success = 1;
2940         } else {
2941                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2942                 packet_put_int(listen_port);
2943                 packet_put_cstring(host_to_connect);
2944                 packet_put_int(port_to_connect);
2945                 packet_send();
2946                 packet_write_wait();
2947
2948                 /* Wait for response from the remote side. */
2949                 type = packet_read();
2950                 switch (type) {
2951                 case SSH_SMSG_SUCCESS:
2952                         success = 1;
2953                         break;
2954                 case SSH_SMSG_FAILURE:
2955                         break;
2956                 default:
2957                         /* Unknown packet */
2958                         packet_disconnect("Protocol error for port forward request:"
2959                             "received packet type %d.", type);
2960                 }
2961         }
2962         if (success) {
2963                 /* Record that connection to this host/port is permitted. */
2964                 permitted_opens = xrealloc(permitted_opens,
2965                     num_permitted_opens + 1, sizeof(*permitted_opens));
2966                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2967                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2968                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2969                 num_permitted_opens++;
2970         }
2971         return (success ? 0 : -1);
2972 }
2973
2974 /*
2975  * Request cancellation of remote forwarding of connection host:port from
2976  * local side.
2977  */
2978 void
2979 channel_request_rforward_cancel(const char *host, u_short port)
2980 {
2981         int i;
2982
2983         if (!compat20)
2984                 return;
2985
2986         for (i = 0; i < num_permitted_opens; i++) {
2987                 if (permitted_opens[i].host_to_connect != NULL &&
2988                     permitted_opens[i].listen_port == port)
2989                         break;
2990         }
2991         if (i >= num_permitted_opens) {
2992                 debug("%s: requested forward not found", __func__);
2993                 return;
2994         }
2995         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2996         packet_put_cstring("cancel-tcpip-forward");
2997         packet_put_char(0);
2998         packet_put_cstring(host == NULL ? "" : host);
2999         packet_put_int(port);
3000         packet_send();
3001
3002         permitted_opens[i].listen_port = 0;
3003         permitted_opens[i].port_to_connect = 0;
3004         xfree(permitted_opens[i].host_to_connect);
3005         permitted_opens[i].host_to_connect = NULL;
3006 }
3007
3008 /*
3009  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
3010  * listening for the port, and sends back a success reply (or disconnect
3011  * message if there was an error).
3012  */
3013 int
3014 channel_input_port_forward_request(int is_root, int gateway_ports)
3015 {
3016         u_short port, host_port;
3017         int success = 0;
3018         char *hostname;
3019
3020         /* Get arguments from the packet. */
3021         port = packet_get_int();
3022         hostname = packet_get_string(NULL);
3023         host_port = packet_get_int();
3024
3025 #ifndef HAVE_CYGWIN
3026         /*
3027          * Check that an unprivileged user is not trying to forward a
3028          * privileged port.
3029          */
3030         if (port < IPPORT_RESERVED && !is_root)
3031                 packet_disconnect(
3032                     "Requested forwarding of port %d but user is not root.",
3033                     port);
3034         if (host_port == 0)
3035                 packet_disconnect("Dynamic forwarding denied.");
3036 #endif
3037
3038         /* Initiate forwarding */
3039         success = channel_setup_local_fwd_listener(NULL, port, hostname,
3040             host_port, gateway_ports);
3041
3042         /* Free the argument string. */
3043         xfree(hostname);
3044
3045         return (success ? 0 : -1);
3046 }
3047
3048 /*
3049  * Permits opening to any host/port if permitted_opens[] is empty.  This is
3050  * usually called by the server, because the user could connect to any port
3051  * anyway, and the server has no way to know but to trust the client anyway.
3052  */
3053 void
3054 channel_permit_all_opens(void)
3055 {
3056         if (num_permitted_opens == 0)
3057                 all_opens_permitted = 1;
3058 }
3059
3060 void
3061 channel_add_permitted_opens(char *host, int port)
3062 {
3063         debug("allow port forwarding to host %s port %d", host, port);
3064
3065         permitted_opens = xrealloc(permitted_opens,
3066             num_permitted_opens + 1, sizeof(*permitted_opens));
3067         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
3068         permitted_opens[num_permitted_opens].port_to_connect = port;
3069         num_permitted_opens++;
3070
3071         all_opens_permitted = 0;
3072 }
3073
3074 int
3075 channel_add_adm_permitted_opens(char *host, int port)
3076 {
3077         debug("config allows port forwarding to host %s port %d", host, port);
3078
3079         permitted_adm_opens = xrealloc(permitted_adm_opens,
3080             num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
3081         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3082              = xstrdup(host);
3083         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3084         return ++num_adm_permitted_opens;
3085 }
3086
3087 void
3088 channel_clear_permitted_opens(void)
3089 {
3090         int i;
3091
3092         for (i = 0; i < num_permitted_opens; i++)
3093                 if (permitted_opens[i].host_to_connect != NULL)
3094                         xfree(permitted_opens[i].host_to_connect);
3095         if (num_permitted_opens > 0) {
3096                 xfree(permitted_opens);
3097                 permitted_opens = NULL;
3098         }
3099         num_permitted_opens = 0;
3100 }
3101
3102 void
3103 channel_clear_adm_permitted_opens(void)
3104 {
3105         int i;
3106
3107         for (i = 0; i < num_adm_permitted_opens; i++)
3108                 if (permitted_adm_opens[i].host_to_connect != NULL)
3109                         xfree(permitted_adm_opens[i].host_to_connect);
3110         if (num_adm_permitted_opens > 0) {
3111                 xfree(permitted_adm_opens);
3112                 permitted_adm_opens = NULL;
3113         }
3114         num_adm_permitted_opens = 0;
3115 }
3116
3117 void
3118 channel_print_adm_permitted_opens(void)
3119 {
3120         int i;
3121
3122         printf("permitopen");
3123         if (num_adm_permitted_opens == 0) {
3124                 printf(" any\n");
3125                 return;
3126         }
3127         for (i = 0; i < num_adm_permitted_opens; i++)
3128                 if (permitted_adm_opens[i].host_to_connect != NULL)
3129                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3130                             permitted_adm_opens[i].port_to_connect);
3131         printf("\n");
3132 }
3133
3134 /* Try to start non-blocking connect to next host in cctx list */
3135 static int
3136 connect_next(struct channel_connect *cctx)
3137 {
3138         int sock, saved_errno;
3139         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
3140
3141         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3142                 if (cctx->ai->ai_family != AF_INET &&
3143                     cctx->ai->ai_family != AF_INET6)
3144                         continue;
3145                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3146                     ntop, sizeof(ntop), strport, sizeof(strport),
3147                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3148                         error("connect_next: getnameinfo failed");
3149                         continue;
3150                 }
3151                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3152                     cctx->ai->ai_protocol)) == -1) {
3153                         if (cctx->ai->ai_next == NULL)
3154                                 error("socket: %.100s", strerror(errno));
3155                         else
3156                                 verbose("socket: %.100s", strerror(errno));
3157                         continue;
3158                 }
3159                 if (set_nonblock(sock) == -1)
3160                         fatal("%s: set_nonblock(%d)", __func__, sock);
3161                 if (connect(sock, cctx->ai->ai_addr,
3162                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3163                         debug("connect_next: host %.100s ([%.100s]:%s): "
3164                             "%.100s", cctx->host, ntop, strport,
3165                             strerror(errno));
3166                         saved_errno = errno;
3167                         close(sock);
3168                         errno = saved_errno;
3169                         continue;       /* fail -- try next */
3170                 }
3171                 debug("connect_next: host %.100s ([%.100s]:%s) "
3172                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3173                 cctx->ai = cctx->ai->ai_next;
3174                 set_nodelay(sock);
3175                 return sock;
3176         }
3177         return -1;
3178 }
3179
3180 static void
3181 channel_connect_ctx_free(struct channel_connect *cctx)
3182 {
3183         xfree(cctx->host);
3184         if (cctx->aitop)
3185                 freeaddrinfo(cctx->aitop);
3186         bzero(cctx, sizeof(*cctx));
3187         cctx->host = NULL;
3188         cctx->ai = cctx->aitop = NULL;
3189 }
3190
3191 /* Return CONNECTING channel to remote host, port */
3192 static Channel *
3193 connect_to(const char *host, u_short port, char *ctype, char *rname)
3194 {
3195         struct addrinfo hints;
3196         int gaierr;
3197         int sock = -1;
3198         char strport[NI_MAXSERV];
3199         struct channel_connect cctx;
3200         Channel *c;
3201
3202         memset(&cctx, 0, sizeof(cctx));
3203         memset(&hints, 0, sizeof(hints));
3204         hints.ai_family = IPv4or6;
3205         hints.ai_socktype = SOCK_STREAM;
3206         snprintf(strport, sizeof strport, "%d", port);
3207         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
3208                 error("connect_to %.100s: unknown host (%s)", host,
3209                     ssh_gai_strerror(gaierr));
3210                 return NULL;
3211         }
3212
3213         cctx.host = xstrdup(host);
3214         cctx.port = port;
3215         cctx.ai = cctx.aitop;
3216
3217         if ((sock = connect_next(&cctx)) == -1) {
3218                 error("connect to %.100s port %d failed: %s",
3219                     host, port, strerror(errno));
3220                 channel_connect_ctx_free(&cctx);
3221                 return NULL;
3222         }
3223         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3224             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3225         c->connect_ctx = cctx;
3226         return c;
3227 }
3228
3229 Channel *
3230 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3231 {
3232         int i;
3233
3234         for (i = 0; i < num_permitted_opens; i++) {
3235                 if (permitted_opens[i].host_to_connect != NULL &&
3236                     permitted_opens[i].listen_port == listen_port) {
3237                         return connect_to(
3238                             permitted_opens[i].host_to_connect,
3239                             permitted_opens[i].port_to_connect, ctype, rname);
3240                 }
3241         }
3242         error("WARNING: Server requests forwarding for unknown listen_port %d",
3243             listen_port);
3244         return NULL;
3245 }
3246
3247 /* Check if connecting to that port is permitted and connect. */
3248 Channel *
3249 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3250 {
3251         int i, permit, permit_adm = 1;
3252
3253         permit = all_opens_permitted;
3254         if (!permit) {
3255                 for (i = 0; i < num_permitted_opens; i++)
3256                         if (permitted_opens[i].host_to_connect != NULL &&
3257                             permitted_opens[i].port_to_connect == port &&
3258                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3259                                 permit = 1;
3260         }
3261
3262         if (num_adm_permitted_opens > 0) {
3263                 permit_adm = 0;
3264                 for (i = 0; i < num_adm_permitted_opens; i++)
3265                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3266                             permitted_adm_opens[i].port_to_connect == port &&
3267                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3268                             == 0)
3269                                 permit_adm = 1;
3270         }
3271
3272         if (!permit || !permit_adm) {
3273                 logit("Received request to connect to host %.100s port %d, "
3274                     "but the request was denied.", host, port);
3275                 return NULL;
3276         }
3277         return connect_to(host, port, ctype, rname);
3278 }
3279
3280 void
3281 channel_send_window_changes(void)
3282 {
3283         u_int i;
3284         struct winsize ws;
3285
3286         for (i = 0; i < channels_alloc; i++) {
3287                 if (channels[i] == NULL || !channels[i]->client_tty ||
3288                     channels[i]->type != SSH_CHANNEL_OPEN)
3289                         continue;
3290                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3291                         continue;
3292                 channel_request_start(i, "window-change", 0);
3293                 packet_put_int((u_int)ws.ws_col);
3294                 packet_put_int((u_int)ws.ws_row);
3295                 packet_put_int((u_int)ws.ws_xpixel);
3296                 packet_put_int((u_int)ws.ws_ypixel);
3297                 packet_send();
3298         }
3299 }
3300
3301 /* -- X11 forwarding */
3302
3303 /*
3304  * Creates an internet domain socket for listening for X11 connections.
3305  * Returns 0 and a suitable display number for the DISPLAY variable
3306  * stored in display_numberp , or -1 if an error occurs.
3307  */
3308 int
3309 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3310     int single_connection, u_int *display_numberp, int **chanids)
3311 {
3312         Channel *nc = NULL;
3313         int display_number, sock;
3314         u_short port;
3315         struct addrinfo hints, *ai, *aitop;
3316         char strport[NI_MAXSERV];
3317         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3318
3319         if (chanids == NULL)
3320                 return -1;
3321
3322         for (display_number = x11_display_offset;
3323             display_number < MAX_DISPLAYS;
3324             display_number++) {
3325                 port = 6000 + display_number;
3326                 memset(&hints, 0, sizeof(hints));
3327                 hints.ai_family = IPv4or6;
3328                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3329                 hints.ai_socktype = SOCK_STREAM;
3330                 snprintf(strport, sizeof strport, "%d", port);
3331                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3332                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3333                         return -1;
3334                 }
3335                 for (ai = aitop; ai; ai = ai->ai_next) {
3336                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3337                                 continue;
3338                         sock = socket(ai->ai_family, ai->ai_socktype,
3339                             ai->ai_protocol);
3340                         if (sock < 0) {
3341                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
3342 #ifdef EPFNOSUPPORT
3343                                     && (errno != EPFNOSUPPORT)
3344 #endif
3345                                     ) {
3346                                         error("socket: %.100s", strerror(errno));
3347                                         freeaddrinfo(aitop);
3348                                         return -1;
3349                                 } else {
3350                                         debug("x11_create_display_inet: Socket family %d not supported",
3351                                                  ai->ai_family);
3352                                         continue;
3353                                 }
3354                         }
3355                         if (ai->ai_family == AF_INET6)
3356                                 sock_set_v6only(sock);
3357                         if (x11_use_localhost)
3358                                 channel_set_reuseaddr(sock);
3359                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3360                                 debug2("bind port %d: %.100s", port, strerror(errno));
3361                                 close(sock);
3362
3363                                 for (n = 0; n < num_socks; n++) {
3364                                         close(socks[n]);
3365                                 }
3366                                 num_socks = 0;
3367                                 break;
3368                         }
3369                         socks[num_socks++] = sock;
3370                         if (num_socks == NUM_SOCKS)
3371                                 break;
3372                 }
3373                 freeaddrinfo(aitop);
3374                 if (num_socks > 0)
3375                         break;
3376         }
3377         if (display_number >= MAX_DISPLAYS) {
3378                 error("Failed to allocate internet-domain X11 display socket.");
3379                 return -1;
3380         }
3381         /* Start listening for connections on the socket. */
3382         for (n = 0; n < num_socks; n++) {
3383                 sock = socks[n];
3384                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3385                         error("listen: %.100s", strerror(errno));
3386                         close(sock);
3387                         return -1;
3388                 }
3389         }
3390
3391         /* Allocate a channel for each socket. */
3392         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3393         for (n = 0; n < num_socks; n++) {
3394                 sock = socks[n];
3395                 /* Is this really necassary? */
3396                 if (hpn_disabled)
3397                 nc = channel_new("x11 listener",
3398                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3399                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3400                     0, "X11 inet listener", 1);
3401                 else
3402                         nc = channel_new("x11 listener",
3403                             SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3404                             hpn_buffer_size, CHAN_X11_PACKET_DEFAULT,
3405                             0, "X11 inet listener", 1);
3406                 nc->single_connection = single_connection;
3407                 (*chanids)[n] = nc->self;
3408         }
3409         (*chanids)[n] = -1;
3410
3411         /* Return the display number for the DISPLAY environment variable. */
3412         *display_numberp = display_number;
3413         return (0);
3414 }
3415
3416 static int
3417 connect_local_xsocket_path(const char *pathname)
3418 {
3419         int sock;
3420         struct sockaddr_un addr;
3421
3422         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3423         if (sock < 0)
3424                 error("socket: %.100s", strerror(errno));
3425         memset(&addr, 0, sizeof(addr));
3426         addr.sun_family = AF_UNIX;
3427         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3428         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3429                 return sock;
3430         close(sock);
3431         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3432         return -1;
3433 }
3434
3435 static int
3436 connect_local_xsocket(u_int dnr)
3437 {
3438         char buf[1024];
3439         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3440         return connect_local_xsocket_path(buf);
3441 }
3442
3443 int
3444 x11_connect_display(void)
3445 {
3446         u_int display_number;
3447         const char *display;
3448         char buf[1024], *cp;
3449         struct addrinfo hints, *ai, *aitop;
3450         char strport[NI_MAXSERV];
3451         int gaierr, sock = 0;
3452
3453         /* Try to open a socket for the local X server. */
3454         display = getenv("DISPLAY");
3455         if (!display) {
3456                 error("DISPLAY not set.");
3457                 return -1;
3458         }
3459         /*
3460          * Now we decode the value of the DISPLAY variable and make a
3461          * connection to the real X server.
3462          */
3463
3464         /* Check if the display is from launchd. */
3465 #ifdef __APPLE__
3466         if (strncmp(display, "/tmp/launch", 11) == 0) {
3467                 sock = connect_local_xsocket_path(display);
3468                 if (sock < 0)
3469                         return -1;
3470
3471                 /* OK, we now have a connection to the display. */
3472                 return sock;
3473         }
3474 #endif
3475         /*
3476          * Check if it is a unix domain socket.  Unix domain displays are in
3477          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3478          */
3479         if (strncmp(display, "unix:", 5) == 0 ||
3480             display[0] == ':') {
3481                 /* Connect to the unix domain socket. */
3482                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3483                         error("Could not parse display number from DISPLAY: %.100s",
3484                             display);
3485                         return -1;
3486                 }
3487                 /* Create a socket. */
3488                 sock = connect_local_xsocket(display_number);
3489                 if (sock < 0)
3490                         return -1;
3491
3492                 /* OK, we now have a connection to the display. */
3493                 return sock;
3494         }
3495         /*
3496          * Connect to an inet socket.  The DISPLAY value is supposedly
3497          * hostname:d[.s], where hostname may also be numeric IP address.
3498          */
3499         strlcpy(buf, display, sizeof(buf));
3500         cp = strchr(buf, ':');
3501         if (!cp) {
3502                 error("Could not find ':' in DISPLAY: %.100s", display);
3503                 return -1;
3504         }
3505         *cp = 0;
3506         /* buf now contains the host name.  But first we parse the display number. */
3507         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3508                 error("Could not parse display number from DISPLAY: %.100s",
3509                     display);
3510                 return -1;
3511         }
3512
3513         /* Look up the host address */
3514         memset(&hints, 0, sizeof(hints));
3515         hints.ai_family = IPv4or6;
3516         hints.ai_socktype = SOCK_STREAM;
3517         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3518         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3519                 error("%.100s: unknown host. (%s)", buf,
3520                 ssh_gai_strerror(gaierr));
3521                 return -1;
3522         }
3523         for (ai = aitop; ai; ai = ai->ai_next) {
3524                 /* Create a socket. */
3525                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3526                 if (sock < 0) {
3527                         debug2("socket: %.100s", strerror(errno));
3528                         continue;
3529                 }
3530                 /* Connect it to the display. */
3531                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3532                         debug2("connect %.100s port %u: %.100s", buf,
3533                             6000 + display_number, strerror(errno));
3534                         close(sock);
3535                         continue;
3536                 }
3537                 /* Success */
3538                 break;
3539         }
3540         freeaddrinfo(aitop);
3541         if (!ai) {
3542                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3543                     strerror(errno));
3544                 return -1;
3545         }
3546         set_nodelay(sock);
3547         return sock;
3548 }
3549
3550 /*
3551  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3552  * the remote channel number.  We should do whatever we want, and respond
3553  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3554  */
3555
3556 /* ARGSUSED */
3557 void
3558 x11_input_open(int type, u_int32_t seq, void *ctxt)
3559 {
3560         Channel *c = NULL;
3561         int remote_id, sock = 0;
3562         char *remote_host;
3563
3564         debug("Received X11 open request.");
3565
3566         remote_id = packet_get_int();
3567
3568         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3569                 remote_host = packet_get_string(NULL);
3570         } else {
3571                 remote_host = xstrdup("unknown (remote did not supply name)");
3572         }
3573         packet_check_eom();
3574
3575         /* Obtain a connection to the real X display. */
3576         sock = x11_connect_display();
3577         if (sock != -1) {
3578                 /* Allocate a channel for this connection. */
3579                 c = channel_new("connected x11 socket",
3580                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3581                     remote_host, 1);
3582                 c->remote_id = remote_id;
3583                 c->force_drain = 1;
3584         }
3585         xfree(remote_host);
3586         if (c == NULL) {
3587                 /* Send refusal to the remote host. */
3588                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3589                 packet_put_int(remote_id);
3590         } else {
3591                 /* Send a confirmation to the remote host. */
3592                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3593                 packet_put_int(remote_id);
3594                 packet_put_int(c->self);
3595         }
3596         packet_send();
3597 }
3598
3599 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3600 /* ARGSUSED */
3601 void
3602 deny_input_open(int type, u_int32_t seq, void *ctxt)
3603 {
3604         int rchan = packet_get_int();
3605
3606         switch (type) {
3607         case SSH_SMSG_AGENT_OPEN:
3608                 error("Warning: ssh server tried agent forwarding.");
3609                 break;
3610         case SSH_SMSG_X11_OPEN:
3611                 error("Warning: ssh server tried X11 forwarding.");
3612                 break;
3613         default:
3614                 error("deny_input_open: type %d", type);
3615                 break;
3616         }
3617         error("Warning: this is probably a break-in attempt by a malicious server.");
3618         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3619         packet_put_int(rchan);
3620         packet_send();
3621 }
3622
3623 /*
3624  * Requests forwarding of X11 connections, generates fake authentication
3625  * data, and enables authentication spoofing.
3626  * This should be called in the client only.
3627  */
3628 void
3629 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3630     const char *proto, const char *data)
3631 {
3632         u_int data_len = (u_int) strlen(data) / 2;
3633         u_int i, value;
3634         char *new_data;
3635         int screen_number;
3636         const char *cp;
3637         u_int32_t rnd = 0;
3638
3639         if (x11_saved_display == NULL)
3640                 x11_saved_display = xstrdup(disp);
3641         else if (strcmp(disp, x11_saved_display) != 0) {
3642                 error("x11_request_forwarding_with_spoofing: different "
3643                     "$DISPLAY already forwarded");
3644                 return;
3645         }
3646
3647         cp = strchr(disp, ':');
3648         if (cp)
3649                 cp = strchr(cp, '.');
3650         if (cp)
3651                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3652         else
3653                 screen_number = 0;
3654
3655         if (x11_saved_proto == NULL) {
3656                 /* Save protocol name. */
3657                 x11_saved_proto = xstrdup(proto);
3658                 /*
3659                  * Extract real authentication data and generate fake data
3660                  * of the same length.
3661                  */
3662                 x11_saved_data = xmalloc(data_len);
3663                 x11_fake_data = xmalloc(data_len);
3664                 for (i = 0; i < data_len; i++) {
3665                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3666                                 fatal("x11_request_forwarding: bad "
3667                                     "authentication data: %.100s", data);
3668                         if (i % 4 == 0)
3669                                 rnd = arc4random();
3670                         x11_saved_data[i] = value;
3671                         x11_fake_data[i] = rnd & 0xff;
3672                         rnd >>= 8;
3673                 }
3674                 x11_saved_data_len = data_len;
3675                 x11_fake_data_len = data_len;
3676         }
3677
3678         /* Convert the fake data into hex. */
3679         new_data = tohex(x11_fake_data, data_len);
3680
3681         /* Send the request packet. */
3682         if (compat20) {
3683                 channel_request_start(client_session_id, "x11-req", 0);
3684                 packet_put_char(0);     /* XXX bool single connection */
3685         } else {
3686                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3687         }
3688         packet_put_cstring(proto);
3689         packet_put_cstring(new_data);
3690         packet_put_int(screen_number);
3691         packet_send();
3692         packet_write_wait();
3693         xfree(new_data);
3694 }
3695
3696
3697 /* -- agent forwarding */
3698
3699 /* Sends a message to the server to request authentication fd forwarding. */
3700
3701 void
3702 auth_request_forwarding(void)
3703 {
3704         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3705         packet_send();
3706         packet_write_wait();
3707 }