crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.336 2014/07/15 15:54:14 millert 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/stat.h>
  46 #include <sys/ioctl.h>
  47 #include <sys/un.h>
  48 #include <sys/socket.h>
  49 #ifdef HAVE_SYS_TIME_H
  50 # include <sys/time.h>
  51 #endif
  52
  53 #include <netinet/in.h>
  54 #include <arpa/inet.h>
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <termios.h>
  63 #include <unistd.h>
  64 #include <stdarg.h>
  65
  66 #include "openbsd-compat/sys-queue.h"
  67 #include "xmalloc.h"
  68 #include "ssh.h"
  69 #include "ssh1.h"
  70 #include "ssh2.h"
  71 #include "packet.h"
  72 #include "log.h"
  73 #include "misc.h"
  74 #include "buffer.h"
  75 #include "channels.h"
  76 #include "compat.h"
  77 #include "canohost.h"
  78 #include "key.h"
  79 #include "authfd.h"
  80 #include "pathnames.h"
  81
  82 /* -- channel core */
  83
  84 /*
  85  * Pointer to an array containing all allocated channels.  The array is
  86  * dynamically extended as needed.
  87  */
  88 static Channel **channels = NULL;
  89
  90 /*
  91  * Size of the channel array.  All slots of the array must always be
  92  * initialized (at least the type field); unused slots set to NULL
  93  */
  94 static u_int channels_alloc = 0;
  95
  96 /*
  97  * Maximum file descriptor value used in any of the channels.  This is
  98  * updated in channel_new.
  99  */
 100 static int channel_max_fd = 0;
 101
 102
 103 /* -- tcp forwarding */
 104
 105 /*
 106  * Data structure for storing which hosts are permitted for forward requests.
 107  * The local sides of any remote forwards are stored in this array to prevent
 108  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 109  * network (which might be behind a firewall).
 110  */
 111 /* XXX: streamlocal wants a path instead of host:port */
 112 /*      Overload host_to_connect; we could just make this match Forward */
 113 /*      XXX - can we use listen_host instead of listen_path? */
 114 typedef struct {
 115         char *host_to_connect;          /* Connect to 'host'. */
 116         int port_to_connect;            /* Connect to 'port'. */
 117         char *listen_host;              /* Remote side should listen address. */
 118         char *listen_path;              /* Remote side should listen path. */
 119         int listen_port;                /* Remote side should listen port. */
 120 } ForwardPermission;
 121
 122 /* List of all permitted host/port pairs to connect by the user. */
 123 static ForwardPermission *permitted_opens = NULL;
 124
 125 /* List of all permitted host/port pairs to connect by the admin. */
 126 static ForwardPermission *permitted_adm_opens = NULL;
 127
 128 /* Number of permitted host/port pairs in the array permitted by the user. */
 129 static int num_permitted_opens = 0;
 130
 131 /* Number of permitted host/port pair in the array permitted by the admin. */
 132 static int num_adm_permitted_opens = 0;
 133
 134 /* special-case port number meaning allow any port */
 135 #define FWD_PERMIT_ANY_PORT     0
 136
 137 /*
 138  * If this is true, all opens are permitted.  This is the case on the server
 139  * on which we have to trust the client anyway, and the user could do
 140  * anything after logging in anyway.
 141  */
 142 static int all_opens_permitted = 0;
 143
 144
 145 /* -- X11 forwarding */
 146
 147 /* Maximum number of fake X11 displays to try. */
 148 #define MAX_DISPLAYS  1000
 149
 150 /* Saved X11 local (client) display. */
 151 static char *x11_saved_display = NULL;
 152
 153 /* Saved X11 authentication protocol name. */
 154 static char *x11_saved_proto = NULL;
 155
 156 /* Saved X11 authentication data.  This is the real data. */
 157 static char *x11_saved_data = NULL;
 158 static u_int x11_saved_data_len = 0;
 159
 160 /*
 161  * Fake X11 authentication data.  This is what the server will be sending us;
 162  * we should replace any occurrences of this by the real data.
 163  */
 164 static u_char *x11_fake_data = NULL;
 165 static u_int x11_fake_data_len;
 166
 167
 168 /* -- agent forwarding */
 169
 170 #define NUM_SOCKS       10
 171
 172 /* AF_UNSPEC or AF_INET or AF_INET6 */
 173 static int IPv4or6 = AF_UNSPEC;
 174
 175 /* helper */
 176 static void port_open_helper(Channel *c, char *rtype);
 177
 178 /* non-blocking connect helpers */
 179 static int connect_next(struct channel_connect *);
 180 static void channel_connect_ctx_free(struct channel_connect *);
 181
 182 /* -- channel core */
 183
 184 Channel *
 185 channel_by_id(int id)
 186 {
 187         Channel *c;
 188
 189         if (id < 0 || (u_int)id >= channels_alloc) {
 190                 logit("channel_by_id: %d: bad id", id);
 191                 return NULL;
 192         }
 193         c = channels[id];
 194         if (c == NULL) {
 195                 logit("channel_by_id: %d: bad id: channel free", id);
 196                 return NULL;
 197         }
 198         return c;
 199 }
 200
 201 /*
 202  * Returns the channel if it is allowed to receive protocol messages.
 203  * Private channels, like listening sockets, may not receive messages.
 204  */
 205 Channel *
 206 channel_lookup(int id)
 207 {
 208         Channel *c;
 209
 210         if ((c = channel_by_id(id)) == NULL)
 211                 return (NULL);
 212
 213         switch (c->type) {
 214         case SSH_CHANNEL_X11_OPEN:
 215         case SSH_CHANNEL_LARVAL:
 216         case SSH_CHANNEL_CONNECTING:
 217         case SSH_CHANNEL_DYNAMIC:
 218         case SSH_CHANNEL_OPENING:
 219         case SSH_CHANNEL_OPEN:
 220         case SSH_CHANNEL_INPUT_DRAINING:
 221         case SSH_CHANNEL_OUTPUT_DRAINING:
 222         case SSH_CHANNEL_ABANDONED:
 223                 return (c);
 224         }
 225         logit("Non-public channel %d, type %d.", id, c->type);
 226         return (NULL);
 227 }
 228
 229 /*
 230  * Register filedescriptors for a channel, used when allocating a channel or
 231  * when the channel consumer/producer is ready, e.g. shell exec'd
 232  */
 233 static void
 234 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 235     int extusage, int nonblock, int is_tty)
 236 {
 237         /* Update the maximum file descriptor value. */
 238         channel_max_fd = MAX(channel_max_fd, rfd);
 239         channel_max_fd = MAX(channel_max_fd, wfd);
 240         channel_max_fd = MAX(channel_max_fd, efd);
 241
 242         if (rfd != -1)
 243                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 244         if (wfd != -1 && wfd != rfd)
 245                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 246         if (efd != -1 && efd != rfd && efd != wfd)
 247                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 248
 249         c->rfd = rfd;
 250         c->wfd = wfd;
 251         c->sock = (rfd == wfd) ? rfd : -1;
 252         c->efd = efd;
 253         c->extended_usage = extusage;
 254
 255         if ((c->isatty = is_tty) != 0)
 256                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 257 #ifdef _AIX
 258         /* XXX: Later AIX versions can't push as much data to tty */
 259         c->wfd_isatty = is_tty || isatty(c->wfd);
 260 #endif
 261
 262         /* enable nonblocking mode */
 263         if (nonblock) {
 264                 if (rfd != -1)
 265                         set_nonblock(rfd);
 266                 if (wfd != -1)
 267                         set_nonblock(wfd);
 268                 if (efd != -1)
 269                         set_nonblock(efd);
 270         }
 271 }
 272
 273 /*
 274  * Allocate a new channel object and set its type and socket. This will cause
 275  * remote_name to be freed.
 276  */
 277 Channel *
 278 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 279     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 280 {
 281         int found;
 282         u_int i;
 283         Channel *c;
 284
 285         /* Do initial allocation if this is the first call. */
 286         if (channels_alloc == 0) {
 287                 channels_alloc = 10;
 288                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 289                 for (i = 0; i < channels_alloc; i++)
 290                         channels[i] = NULL;
 291         }
 292         /* Try to find a free slot where to put the new channel. */
 293         for (found = -1, i = 0; i < channels_alloc; i++)
 294                 if (channels[i] == NULL) {
 295                         /* Found a free slot. */
 296                         found = (int)i;
 297                         break;
 298                 }
 299         if (found < 0) {
 300                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 301                 found = channels_alloc;
 302                 if (channels_alloc > 10000)
 303                         fatal("channel_new: internal error: channels_alloc %d "
 304                             "too big.", channels_alloc);
 305                 channels = xrealloc(channels, channels_alloc + 10,
 306                     sizeof(Channel *));
 307                 channels_alloc += 10;
 308                 debug2("channel: expanding %d", channels_alloc);
 309                 for (i = found; i < channels_alloc; i++)
 310                         channels[i] = NULL;
 311         }
 312         /* Initialize and return new channel. */
 313         c = channels[found] = xcalloc(1, sizeof(Channel));
 314         buffer_init(&c->input);
 315         buffer_init(&c->output);
 316         buffer_init(&c->extended);
 317         c->path = NULL;
 318         c->listening_addr = NULL;
 319         c->listening_port = 0;
 320         c->ostate = CHAN_OUTPUT_OPEN;
 321         c->istate = CHAN_INPUT_OPEN;
 322         c->flags = 0;
 323         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 324         c->notbefore = 0;
 325         c->self = found;
 326         c->type = type;
 327         c->ctype = ctype;
 328         c->local_window = window;
 329         c->local_window_max = window;
 330         c->local_consumed = 0;
 331         c->local_maxpacket = maxpack;
 332         c->remote_id = -1;
 333         c->remote_name = xstrdup(remote_name);
 334         c->remote_window = 0;
 335         c->remote_maxpacket = 0;
 336         c->force_drain = 0;
 337         c->single_connection = 0;
 338         c->detach_user = NULL;
 339         c->detach_close = 0;
 340         c->open_confirm = NULL;
 341         c->open_confirm_ctx = NULL;
 342         c->input_filter = NULL;
 343         c->output_filter = NULL;
 344         c->filter_ctx = NULL;
 345         c->filter_cleanup = NULL;
 346         c->ctl_chan = -1;
 347         c->mux_rcb = NULL;
 348         c->mux_ctx = NULL;
 349         c->mux_pause = 0;
 350         c->delayed = 1;         /* prevent call to channel_post handler */
 351         TAILQ_INIT(&c->status_confirms);
 352         debug("channel %d: new [%s]", found, remote_name);
 353         return c;
 354 }
 355
 356 static int
 357 channel_find_maxfd(void)
 358 {
 359         u_int i;
 360         int max = 0;
 361         Channel *c;
 362
 363         for (i = 0; i < channels_alloc; i++) {
 364                 c = channels[i];
 365                 if (c != NULL) {
 366                         max = MAX(max, c->rfd);
 367                         max = MAX(max, c->wfd);
 368                         max = MAX(max, c->efd);
 369                 }
 370         }
 371         return max;
 372 }
 373
 374 int
 375 channel_close_fd(int *fdp)
 376 {
 377         int ret = 0, fd = *fdp;
 378
 379         if (fd != -1) {
 380                 ret = close(fd);
 381                 *fdp = -1;
 382                 if (fd == channel_max_fd)
 383                         channel_max_fd = channel_find_maxfd();
 384         }
 385         return ret;
 386 }
 387
 388 /* Close all channel fd/socket. */
 389 static void
 390 channel_close_fds(Channel *c)
 391 {
 392         channel_close_fd(&c->sock);
 393         channel_close_fd(&c->rfd);
 394         channel_close_fd(&c->wfd);
 395         channel_close_fd(&c->efd);
 396 }
 397
 398 /* Free the channel and close its fd/socket. */
 399 void
 400 channel_free(Channel *c)
 401 {
 402         char *s;
 403         u_int i, n;
 404         struct channel_confirm *cc;
 405
 406         for (n = 0, i = 0; i < channels_alloc; i++)
 407                 if (channels[i])
 408                         n++;
 409         debug("channel %d: free: %s, nchannels %u", c->self,
 410             c->remote_name ? c->remote_name : "???", n);
 411
 412         s = channel_open_message();
 413         debug3("channel %d: status: %s", c->self, s);
 414         free(s);
 415
 416         if (c->sock != -1)
 417                 shutdown(c->sock, SHUT_RDWR);
 418         channel_close_fds(c);
 419         buffer_free(&c->input);
 420         buffer_free(&c->output);
 421         buffer_free(&c->extended);
 422         free(c->remote_name);
 423         c->remote_name = NULL;
 424         free(c->path);
 425         c->path = NULL;
 426         free(c->listening_addr);
 427         c->listening_addr = NULL;
 428         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 429                 if (cc->abandon_cb != NULL)
 430                         cc->abandon_cb(c, cc->ctx);
 431                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 432                 explicit_bzero(cc, sizeof(*cc));
 433                 free(cc);
 434         }
 435         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 436                 c->filter_cleanup(c->self, c->filter_ctx);
 437         channels[c->self] = NULL;
 438         free(c);
 439 }
 440
 441 void
 442 channel_free_all(void)
 443 {
 444         u_int i;
 445
 446         for (i = 0; i < channels_alloc; i++)
 447                 if (channels[i] != NULL)
 448                         channel_free(channels[i]);
 449 }
 450
 451 /*
 452  * Closes the sockets/fds of all channels.  This is used to close extra file
 453  * descriptors after a fork.
 454  */
 455 void
 456 channel_close_all(void)
 457 {
 458         u_int i;
 459
 460         for (i = 0; i < channels_alloc; i++)
 461                 if (channels[i] != NULL)
 462                         channel_close_fds(channels[i]);
 463 }
 464
 465 /*
 466  * Stop listening to channels.
 467  */
 468 void
 469 channel_stop_listening(void)
 470 {
 471         u_int i;
 472         Channel *c;
 473
 474         for (i = 0; i < channels_alloc; i++) {
 475                 c = channels[i];
 476                 if (c != NULL) {
 477                         switch (c->type) {
 478                         case SSH_CHANNEL_AUTH_SOCKET:
 479                         case SSH_CHANNEL_PORT_LISTENER:
 480                         case SSH_CHANNEL_RPORT_LISTENER:
 481                         case SSH_CHANNEL_X11_LISTENER:
 482                         case SSH_CHANNEL_UNIX_LISTENER:
 483                         case SSH_CHANNEL_RUNIX_LISTENER:
 484                                 channel_close_fd(&c->sock);
 485                                 channel_free(c);
 486                                 break;
 487                         }
 488                 }
 489         }
 490 }
 491
 492 /*
 493  * Returns true if no channel has too much buffered data, and false if one or
 494  * more channel is overfull.
 495  */
 496 int
 497 channel_not_very_much_buffered_data(void)
 498 {
 499         u_int i;
 500         Channel *c;
 501
 502         for (i = 0; i < channels_alloc; i++) {
 503                 c = channels[i];
 504                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 505 #if 0
 506                         if (!compat20 &&
 507                             buffer_len(&c->input) > packet_get_maxsize()) {
 508                                 debug2("channel %d: big input buffer %d",
 509                                     c->self, buffer_len(&c->input));
 510                                 return 0;
 511                         }
 512 #endif
 513                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 514                                 debug2("channel %d: big output buffer %u > %u",
 515                                     c->self, buffer_len(&c->output),
 516                                     packet_get_maxsize());
 517                                 return 0;
 518                         }
 519                 }
 520         }
 521         return 1;
 522 }
 523
 524 /* Returns true if any channel is still open. */
 525 int
 526 channel_still_open(void)
 527 {
 528         u_int i;
 529         Channel *c;
 530
 531         for (i = 0; i < channels_alloc; i++) {
 532                 c = channels[i];
 533                 if (c == NULL)
 534                         continue;
 535                 switch (c->type) {
 536                 case SSH_CHANNEL_X11_LISTENER:
 537                 case SSH_CHANNEL_PORT_LISTENER:
 538                 case SSH_CHANNEL_RPORT_LISTENER:
 539                 case SSH_CHANNEL_MUX_LISTENER:
 540                 case SSH_CHANNEL_CLOSED:
 541                 case SSH_CHANNEL_AUTH_SOCKET:
 542                 case SSH_CHANNEL_DYNAMIC:
 543                 case SSH_CHANNEL_CONNECTING:
 544                 case SSH_CHANNEL_ZOMBIE:
 545                 case SSH_CHANNEL_ABANDONED:
 546                 case SSH_CHANNEL_UNIX_LISTENER:
 547                 case SSH_CHANNEL_RUNIX_LISTENER:
 548                         continue;
 549                 case SSH_CHANNEL_LARVAL:
 550                         if (!compat20)
 551                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 552                         continue;
 553                 case SSH_CHANNEL_OPENING:
 554                 case SSH_CHANNEL_OPEN:
 555                 case SSH_CHANNEL_X11_OPEN:
 556                 case SSH_CHANNEL_MUX_CLIENT:
 557                         return 1;
 558                 case SSH_CHANNEL_INPUT_DRAINING:
 559                 case SSH_CHANNEL_OUTPUT_DRAINING:
 560                         if (!compat13)
 561                                 fatal("cannot happen: OUT_DRAIN");
 562                         return 1;
 563                 default:
 564                         fatal("channel_still_open: bad channel type %d", c->type);
 565                         /* NOTREACHED */
 566                 }
 567         }
 568         return 0;
 569 }
 570
 571 /* Returns the id of an open channel suitable for keepaliving */
 572 int
 573 channel_find_open(void)
 574 {
 575         u_int i;
 576         Channel *c;
 577
 578         for (i = 0; i < channels_alloc; i++) {
 579                 c = channels[i];
 580                 if (c == NULL || c->remote_id < 0)
 581                         continue;
 582                 switch (c->type) {
 583                 case SSH_CHANNEL_CLOSED:
 584                 case SSH_CHANNEL_DYNAMIC:
 585                 case SSH_CHANNEL_X11_LISTENER:
 586                 case SSH_CHANNEL_PORT_LISTENER:
 587                 case SSH_CHANNEL_RPORT_LISTENER:
 588                 case SSH_CHANNEL_MUX_LISTENER:
 589                 case SSH_CHANNEL_MUX_CLIENT:
 590                 case SSH_CHANNEL_OPENING:
 591                 case SSH_CHANNEL_CONNECTING:
 592                 case SSH_CHANNEL_ZOMBIE:
 593                 case SSH_CHANNEL_ABANDONED:
 594                 case SSH_CHANNEL_UNIX_LISTENER:
 595                 case SSH_CHANNEL_RUNIX_LISTENER:
 596                         continue;
 597                 case SSH_CHANNEL_LARVAL:
 598                 case SSH_CHANNEL_AUTH_SOCKET:
 599                 case SSH_CHANNEL_OPEN:
 600                 case SSH_CHANNEL_X11_OPEN:
 601                         return i;
 602                 case SSH_CHANNEL_INPUT_DRAINING:
 603                 case SSH_CHANNEL_OUTPUT_DRAINING:
 604                         if (!compat13)
 605                                 fatal("cannot happen: OUT_DRAIN");
 606                         return i;
 607                 default:
 608                         fatal("channel_find_open: bad channel type %d", c->type);
 609                         /* NOTREACHED */
 610                 }
 611         }
 612         return -1;
 613 }
 614
 615
 616 /*
 617  * Returns a message describing the currently open forwarded connections,
 618  * suitable for sending to the client.  The message contains crlf pairs for
 619  * newlines.
 620  */
 621 char *
 622 channel_open_message(void)
 623 {
 624         Buffer buffer;
 625         Channel *c;
 626         char buf[1024], *cp;
 627         u_int i;
 628
 629         buffer_init(&buffer);
 630         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 631         buffer_append(&buffer, buf, strlen(buf));
 632         for (i = 0; i < channels_alloc; i++) {
 633                 c = channels[i];
 634                 if (c == NULL)
 635                         continue;
 636                 switch (c->type) {
 637                 case SSH_CHANNEL_X11_LISTENER:
 638                 case SSH_CHANNEL_PORT_LISTENER:
 639                 case SSH_CHANNEL_RPORT_LISTENER:
 640                 case SSH_CHANNEL_CLOSED:
 641                 case SSH_CHANNEL_AUTH_SOCKET:
 642                 case SSH_CHANNEL_ZOMBIE:
 643                 case SSH_CHANNEL_ABANDONED:
 644                 case SSH_CHANNEL_MUX_CLIENT:
 645                 case SSH_CHANNEL_MUX_LISTENER:
 646                 case SSH_CHANNEL_UNIX_LISTENER:
 647                 case SSH_CHANNEL_RUNIX_LISTENER:
 648                         continue;
 649                 case SSH_CHANNEL_LARVAL:
 650                 case SSH_CHANNEL_OPENING:
 651                 case SSH_CHANNEL_CONNECTING:
 652                 case SSH_CHANNEL_DYNAMIC:
 653                 case SSH_CHANNEL_OPEN:
 654                 case SSH_CHANNEL_X11_OPEN:
 655                 case SSH_CHANNEL_INPUT_DRAINING:
 656                 case SSH_CHANNEL_OUTPUT_DRAINING:
 657                         snprintf(buf, sizeof buf,
 658                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cc %d)\r\n",
 659                             c->self, c->remote_name,
 660                             c->type, c->remote_id,
 661                             c->istate, buffer_len(&c->input),
 662                             c->ostate, buffer_len(&c->output),
 663                             c->rfd, c->wfd, c->ctl_chan);
 664                         buffer_append(&buffer, buf, strlen(buf));
 665                         continue;
 666                 default:
 667                         fatal("channel_open_message: bad channel type %d", c->type);
 668                         /* NOTREACHED */
 669                 }
 670         }
 671         buffer_append(&buffer, "\0", 1);
 672         cp = xstrdup(buffer_ptr(&buffer));
 673         buffer_free(&buffer);
 674         return cp;
 675 }
 676
 677 void
 678 channel_send_open(int id)
 679 {
 680         Channel *c = channel_lookup(id);
 681
 682         if (c == NULL) {
 683                 logit("channel_send_open: %d: bad id", id);
 684                 return;
 685         }
 686         debug2("channel %d: send open", id);
 687         packet_start(SSH2_MSG_CHANNEL_OPEN);
 688         packet_put_cstring(c->ctype);
 689         packet_put_int(c->self);
 690         packet_put_int(c->local_window);
 691         packet_put_int(c->local_maxpacket);
 692         packet_send();
 693 }
 694
 695 void
 696 channel_request_start(int id, char *service, int wantconfirm)
 697 {
 698         Channel *c = channel_lookup(id);
 699
 700         if (c == NULL) {
 701                 logit("channel_request_start: %d: unknown channel id", id);
 702                 return;
 703         }
 704         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 705         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 706         packet_put_int(c->remote_id);
 707         packet_put_cstring(service);
 708         packet_put_char(wantconfirm);
 709 }
 710
 711 void
 712 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 713     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 714 {
 715         struct channel_confirm *cc;
 716         Channel *c;
 717
 718         if ((c = channel_lookup(id)) == NULL)
 719                 fatal("channel_register_expect: %d: bad id", id);
 720
 721         cc = xcalloc(1, sizeof(*cc));
 722         cc->cb = cb;
 723         cc->abandon_cb = abandon_cb;
 724         cc->ctx = ctx;
 725         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 726 }
 727
 728 void
 729 channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
 730 {
 731         Channel *c = channel_lookup(id);
 732
 733         if (c == NULL) {
 734                 logit("channel_register_open_confirm: %d: bad id", id);
 735                 return;
 736         }
 737         c->open_confirm = fn;
 738         c->open_confirm_ctx = ctx;
 739 }
 740
 741 void
 742 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 743 {
 744         Channel *c = channel_by_id(id);
 745
 746         if (c == NULL) {
 747                 logit("channel_register_cleanup: %d: bad id", id);
 748                 return;
 749         }
 750         c->detach_user = fn;
 751         c->detach_close = do_close;
 752 }
 753
 754 void
 755 channel_cancel_cleanup(int id)
 756 {
 757         Channel *c = channel_by_id(id);
 758
 759         if (c == NULL) {
 760                 logit("channel_cancel_cleanup: %d: bad id", id);
 761                 return;
 762         }
 763         c->detach_user = NULL;
 764         c->detach_close = 0;
 765 }
 766
 767 void
 768 channel_register_filter(int id, channel_infilter_fn *ifn,
 769     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 770 {
 771         Channel *c = channel_lookup(id);
 772
 773         if (c == NULL) {
 774                 logit("channel_register_filter: %d: bad id", id);
 775                 return;
 776         }
 777         c->input_filter = ifn;
 778         c->output_filter = ofn;
 779         c->filter_ctx = ctx;
 780         c->filter_cleanup = cfn;
 781 }
 782
 783 void
 784 channel_set_fds(int id, int rfd, int wfd, int efd,
 785     int extusage, int nonblock, int is_tty, u_int window_max)
 786 {
 787         Channel *c = channel_lookup(id);
 788
 789         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 790                 fatal("channel_activate for non-larval channel %d.", id);
 791         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 792         c->type = SSH_CHANNEL_OPEN;
 793         c->local_window = c->local_window_max = window_max;
 794         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 795         packet_put_int(c->remote_id);
 796         packet_put_int(c->local_window);
 797         packet_send();
 798 }
 799
 800 /*
 801  * 'channel_pre*' are called just before select() to add any bits relevant to
 802  * channels in the select bitmasks.
 803  */
 804 /*
 805  * 'channel_post*': perform any appropriate operations for channels which
 806  * have events pending.
 807  */
 808 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 809 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 810 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 811
 812 /* ARGSUSED */
 813 static void
 814 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 815 {
 816         FD_SET(c->sock, readset);
 817 }
 818
 819 /* ARGSUSED */
 820 static void
 821 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 822 {
 823         debug3("channel %d: waiting for connection", c->self);
 824         FD_SET(c->sock, writeset);
 825 }
 826
 827 static void
 828 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 829 {
 830         if (buffer_len(&c->input) < packet_get_maxsize())
 831                 FD_SET(c->sock, readset);
 832         if (buffer_len(&c->output) > 0)
 833                 FD_SET(c->sock, writeset);
 834 }
 835
 836 static void
 837 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 838 {
 839         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 840
 841         if (c->istate == CHAN_INPUT_OPEN &&
 842             limit > 0 &&
 843             buffer_len(&c->input) < limit &&
 844             buffer_check_alloc(&c->input, CHAN_RBUF))
 845                 FD_SET(c->rfd, readset);
 846         if (c->ostate == CHAN_OUTPUT_OPEN ||
 847             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 848                 if (buffer_len(&c->output) > 0) {
 849                         FD_SET(c->wfd, writeset);
 850                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 851                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 852                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 853                                     c->self, c->efd, buffer_len(&c->extended));
 854                         else
 855                                 chan_obuf_empty(c);
 856                 }
 857         }
 858         /** XXX check close conditions, too */
 859         if (compat20 && c->efd != -1 &&
 860             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 861                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 862                     buffer_len(&c->extended) > 0)
 863                         FD_SET(c->efd, writeset);
 864                 else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
 865                     (c->extended_usage == CHAN_EXTENDED_READ ||
 866                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
 867                     buffer_len(&c->extended) < c->remote_window)
 868                         FD_SET(c->efd, readset);
 869         }
 870         /* XXX: What about efd? races? */
 871 }
 872
 873 /* ARGSUSED */
 874 static void
 875 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 876 {
 877         if (buffer_len(&c->input) == 0) {
 878                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 879                 packet_put_int(c->remote_id);
 880                 packet_send();
 881                 c->type = SSH_CHANNEL_CLOSED;
 882                 debug2("channel %d: closing after input drain.", c->self);
 883         }
 884 }
 885
 886 /* ARGSUSED */
 887 static void
 888 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 889 {
 890         if (buffer_len(&c->output) == 0)
 891                 chan_mark_dead(c);
 892         else
 893                 FD_SET(c->sock, writeset);
 894 }
 895
 896 /*
 897  * This is a special state for X11 authentication spoofing.  An opened X11
 898  * connection (when authentication spoofing is being done) remains in this
 899  * state until the first packet has been completely read.  The authentication
 900  * data in that packet is then substituted by the real data if it matches the
 901  * fake data, and the channel is put into normal mode.
 902  * XXX All this happens at the client side.
 903  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 904  */
 905 static int
 906 x11_open_helper(Buffer *b)
 907 {
 908         u_char *ucp;
 909         u_int proto_len, data_len;
 910
 911         /* Check if the fixed size part of the packet is in buffer. */
 912         if (buffer_len(b) < 12)
 913                 return 0;
 914
 915         /* Parse the lengths of variable-length fields. */
 916         ucp = buffer_ptr(b);
 917         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 918                 proto_len = 256 * ucp[6] + ucp[7];
 919                 data_len = 256 * ucp[8] + ucp[9];
 920         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 921                 proto_len = ucp[6] + 256 * ucp[7];
 922                 data_len = ucp[8] + 256 * ucp[9];
 923         } else {
 924                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 925                     ucp[0]);
 926                 return -1;
 927         }
 928
 929         /* Check if the whole packet is in buffer. */
 930         if (buffer_len(b) <
 931             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 932                 return 0;
 933
 934         /* Check if authentication protocol matches. */
 935         if (proto_len != strlen(x11_saved_proto) ||
 936             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 937                 debug2("X11 connection uses different authentication protocol.");
 938                 return -1;
 939         }
 940         /* Check if authentication data matches our fake data. */
 941         if (data_len != x11_fake_data_len ||
 942             timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
 943                 x11_fake_data, x11_fake_data_len) != 0) {
 944                 debug2("X11 auth data does not match fake data.");
 945                 return -1;
 946         }
 947         /* Check fake data length */
 948         if (x11_fake_data_len != x11_saved_data_len) {
 949                 error("X11 fake_data_len %d != saved_data_len %d",
 950                     x11_fake_data_len, x11_saved_data_len);
 951                 return -1;
 952         }
 953         /*
 954          * Received authentication protocol and data match
 955          * our fake data. Substitute the fake data with real
 956          * data.
 957          */
 958         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 959             x11_saved_data, x11_saved_data_len);
 960         return 1;
 961 }
 962
 963 static void
 964 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 965 {
 966         int ret = x11_open_helper(&c->output);
 967
 968         if (ret == 1) {
 969                 /* Start normal processing for the channel. */
 970                 c->type = SSH_CHANNEL_OPEN;
 971                 channel_pre_open_13(c, readset, writeset);
 972         } else if (ret == -1) {
 973                 /*
 974                  * We have received an X11 connection that has bad
 975                  * authentication information.
 976                  */
 977                 logit("X11 connection rejected because of wrong authentication.");
 978                 buffer_clear(&c->input);
 979                 buffer_clear(&c->output);
 980                 channel_close_fd(&c->sock);
 981                 c->sock = -1;
 982                 c->type = SSH_CHANNEL_CLOSED;
 983                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 984                 packet_put_int(c->remote_id);
 985                 packet_send();
 986         }
 987 }
 988
 989 static void
 990 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 991 {
 992         int ret = x11_open_helper(&c->output);
 993
 994         /* c->force_drain = 1; */
 995
 996         if (ret == 1) {
 997                 c->type = SSH_CHANNEL_OPEN;
 998                 channel_pre_open(c, readset, writeset);
 999         } else if (ret == -1) {
1000                 logit("X11 connection rejected because of wrong authentication.");
1001                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
1002                 chan_read_failed(c);
1003                 buffer_clear(&c->input);
1004                 chan_ibuf_empty(c);
1005                 buffer_clear(&c->output);
1006                 /* for proto v1, the peer will send an IEOF */
1007                 if (compat20)
1008                         chan_write_failed(c);
1009                 else
1010                         c->type = SSH_CHANNEL_OPEN;
1011                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
1012         }
1013 }
1014
1015 static void
1016 channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1017 {
1018         if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
1019             buffer_check_alloc(&c->input, CHAN_RBUF))
1020                 FD_SET(c->rfd, readset);
1021         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1022                 /* clear buffer immediately (discard any partial packet) */
1023                 buffer_clear(&c->input);
1024                 chan_ibuf_empty(c);
1025                 /* Start output drain. XXX just kill chan? */
1026                 chan_rcvd_oclose(c);
1027         }
1028         if (c->ostate == CHAN_OUTPUT_OPEN ||
1029             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
1030                 if (buffer_len(&c->output) > 0)
1031                         FD_SET(c->wfd, writeset);
1032                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
1033                         chan_obuf_empty(c);
1034         }
1035 }
1036
1037 /* try to decode a socks4 header */
1038 /* ARGSUSED */
1039 static int
1040 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1041 {
1042         char *p, *host;
1043         u_int len, have, i, found, need;
1044         char username[256];
1045         struct {
1046                 u_int8_t version;
1047                 u_int8_t command;
1048                 u_int16_t dest_port;
1049                 struct in_addr dest_addr;
1050         } s4_req, s4_rsp;
1051
1052         debug2("channel %d: decode socks4", c->self);
1053
1054         have = buffer_len(&c->input);
1055         len = sizeof(s4_req);
1056         if (have < len)
1057                 return 0;
1058         p = buffer_ptr(&c->input);
1059
1060         need = 1;
1061         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1062         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1063                 debug2("channel %d: socks4a request", c->self);
1064                 /* ... and needs an extra string (the hostname) */
1065                 need = 2;
1066         }
1067         /* Check for terminating NUL on the string(s) */
1068         for (found = 0, i = len; i < have; i++) {
1069                 if (p[i] == '\0') {
1070                         found++;
1071                         if (found == need)
1072                                 break;
1073                 }
1074                 if (i > 1024) {
1075                         /* the peer is probably sending garbage */
1076                         debug("channel %d: decode socks4: too long",
1077                             c->self);
1078                         return -1;
1079                 }
1080         }
1081         if (found < need)
1082                 return 0;
1083         buffer_get(&c->input, (char *)&s4_req.version, 1);
1084         buffer_get(&c->input, (char *)&s4_req.command, 1);
1085         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1086         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1087         have = buffer_len(&c->input);
1088         p = buffer_ptr(&c->input);
1089         if (memchr(p, '\0', have) == NULL)
1090                 fatal("channel %d: decode socks4: user not nul terminated",
1091                     c->self);
1092         len = strlen(p);
1093         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1094         len++;                                  /* trailing '\0' */
1095         if (len > have)
1096                 fatal("channel %d: decode socks4: len %d > have %d",
1097                     c->self, len, have);
1098         strlcpy(username, p, sizeof(username));
1099         buffer_consume(&c->input, len);
1100
1101         free(c->path);
1102         c->path = NULL;
1103         if (need == 1) {                        /* SOCKS4: one string */
1104                 host = inet_ntoa(s4_req.dest_addr);
1105                 c->path = xstrdup(host);
1106         } else {                                /* SOCKS4A: two strings */
1107                 have = buffer_len(&c->input);
1108                 p = buffer_ptr(&c->input);
1109                 len = strlen(p);
1110                 debug2("channel %d: decode socks4a: host %s/%d",
1111                     c->self, p, len);
1112                 len++;                          /* trailing '\0' */
1113                 if (len > have)
1114                         fatal("channel %d: decode socks4a: len %d > have %d",
1115                             c->self, len, have);
1116                 if (len > NI_MAXHOST) {
1117                         error("channel %d: hostname \"%.100s\" too long",
1118                             c->self, p);
1119                         return -1;
1120                 }
1121                 c->path = xstrdup(p);
1122                 buffer_consume(&c->input, len);
1123         }
1124         c->host_port = ntohs(s4_req.dest_port);
1125
1126         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1127             c->self, c->path, c->host_port, s4_req.command);
1128
1129         if (s4_req.command != 1) {
1130                 debug("channel %d: cannot handle: %s cn %d",
1131                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1132                 return -1;
1133         }
1134         s4_rsp.version = 0;                     /* vn: 0 for reply */
1135         s4_rsp.command = 90;                    /* cd: req granted */
1136         s4_rsp.dest_port = 0;                   /* ignored */
1137         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1138         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1139         return 1;
1140 }
1141
1142 /* try to decode a socks5 header */
1143 #define SSH_SOCKS5_AUTHDONE     0x1000
1144 #define SSH_SOCKS5_NOAUTH       0x00
1145 #define SSH_SOCKS5_IPV4         0x01
1146 #define SSH_SOCKS5_DOMAIN       0x03
1147 #define SSH_SOCKS5_IPV6         0x04
1148 #define SSH_SOCKS5_CONNECT      0x01
1149 #define SSH_SOCKS5_SUCCESS      0x00
1150
1151 /* ARGSUSED */
1152 static int
1153 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1154 {
1155         struct {
1156                 u_int8_t version;
1157                 u_int8_t command;
1158                 u_int8_t reserved;
1159                 u_int8_t atyp;
1160         } s5_req, s5_rsp;
1161         u_int16_t dest_port;
1162         char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1163         u_char *p;
1164         u_int have, need, i, found, nmethods, addrlen, af;
1165
1166         debug2("channel %d: decode socks5", c->self);
1167         p = buffer_ptr(&c->input);
1168         if (p[0] != 0x05)
1169                 return -1;
1170         have = buffer_len(&c->input);
1171         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1172                 /* format: ver | nmethods | methods */
1173                 if (have < 2)
1174                         return 0;
1175                 nmethods = p[1];
1176                 if (have < nmethods + 2)
1177                         return 0;
1178                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1179                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1180                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1181                                 found = 1;
1182                                 break;
1183                         }
1184                 }
1185                 if (!found) {
1186                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1187                             c->self);
1188                         return -1;
1189                 }
1190                 buffer_consume(&c->input, nmethods + 2);
1191                 buffer_put_char(&c->output, 0x05);              /* version */
1192                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1193                 FD_SET(c->sock, writeset);
1194                 c->flags |= SSH_SOCKS5_AUTHDONE;
1195                 debug2("channel %d: socks5 auth done", c->self);
1196                 return 0;                               /* need more */
1197         }
1198         debug2("channel %d: socks5 post auth", c->self);
1199         if (have < sizeof(s5_req)+1)
1200                 return 0;                       /* need more */
1201         memcpy(&s5_req, p, sizeof(s5_req));
1202         if (s5_req.version != 0x05 ||
1203             s5_req.command != SSH_SOCKS5_CONNECT ||
1204             s5_req.reserved != 0x00) {
1205                 debug2("channel %d: only socks5 connect supported", c->self);
1206                 return -1;
1207         }
1208         switch (s5_req.atyp){
1209         case SSH_SOCKS5_IPV4:
1210                 addrlen = 4;
1211                 af = AF_INET;
1212                 break;
1213         case SSH_SOCKS5_DOMAIN:
1214                 addrlen = p[sizeof(s5_req)];
1215                 af = -1;
1216                 break;
1217         case SSH_SOCKS5_IPV6:
1218                 addrlen = 16;
1219                 af = AF_INET6;
1220                 break;
1221         default:
1222                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1223                 return -1;
1224         }
1225         need = sizeof(s5_req) + addrlen + 2;
1226         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1227                 need++;
1228         if (have < need)
1229                 return 0;
1230         buffer_consume(&c->input, sizeof(s5_req));
1231         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1232                 buffer_consume(&c->input, 1);    /* host string length */
1233         buffer_get(&c->input, &dest_addr, addrlen);
1234         buffer_get(&c->input, (char *)&dest_port, 2);
1235         dest_addr[addrlen] = '\0';
1236         free(c->path);
1237         c->path = NULL;
1238         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1239                 if (addrlen >= NI_MAXHOST) {
1240                         error("channel %d: dynamic request: socks5 hostname "
1241                             "\"%.100s\" too long", c->self, dest_addr);
1242                         return -1;
1243                 }
1244                 c->path = xstrdup(dest_addr);
1245         } else {
1246                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1247                         return -1;
1248                 c->path = xstrdup(ntop);
1249         }
1250         c->host_port = ntohs(dest_port);
1251
1252         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1253             c->self, c->path, c->host_port, s5_req.command);
1254
1255         s5_rsp.version = 0x05;
1256         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1257         s5_rsp.reserved = 0;                    /* ignored */
1258         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1259         dest_port = 0;                          /* ignored */
1260
1261         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1262         buffer_put_int(&c->output, ntohl(INADDR_ANY)); /* bind address */
1263         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1264         return 1;
1265 }
1266
1267 Channel *
1268 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1269     int in, int out)
1270 {
1271         Channel *c;
1272
1273         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1274             port_to_connect);
1275
1276         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1277             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1278             0, "stdio-forward", /*nonblock*/0);
1279
1280         c->path = xstrdup(host_to_connect);
1281         c->host_port = port_to_connect;
1282         c->listening_port = 0;
1283         c->force_drain = 1;
1284
1285         channel_register_fds(c, in, out, -1, 0, 1, 0);
1286         port_open_helper(c, "direct-tcpip");
1287
1288         return c;
1289 }
1290
1291 /* dynamic port forwarding */
1292 static void
1293 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1294 {
1295         u_char *p;
1296         u_int have;
1297         int ret;
1298
1299         have = buffer_len(&c->input);
1300         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1301         /* buffer_dump(&c->input); */
1302         /* check if the fixed size part of the packet is in buffer. */
1303         if (have < 3) {
1304                 /* need more */
1305                 FD_SET(c->sock, readset);
1306                 return;
1307         }
1308         /* try to guess the protocol */
1309         p = buffer_ptr(&c->input);
1310         switch (p[0]) {
1311         case 0x04:
1312                 ret = channel_decode_socks4(c, readset, writeset);
1313                 break;
1314         case 0x05:
1315                 ret = channel_decode_socks5(c, readset, writeset);
1316                 break;
1317         default:
1318                 ret = -1;
1319                 break;
1320         }
1321         if (ret < 0) {
1322                 chan_mark_dead(c);
1323         } else if (ret == 0) {
1324                 debug2("channel %d: pre_dynamic: need more", c->self);
1325                 /* need more */
1326                 FD_SET(c->sock, readset);
1327         } else {
1328                 /* switch to the next state */
1329                 c->type = SSH_CHANNEL_OPENING;
1330                 port_open_helper(c, "direct-tcpip");
1331         }
1332 }
1333
1334 /* This is our fake X11 server socket. */
1335 /* ARGSUSED */
1336 static void
1337 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1338 {
1339         Channel *nc;
1340         struct sockaddr_storage addr;
1341         int newsock, oerrno;
1342         socklen_t addrlen;
1343         char buf[16384], *remote_ipaddr;
1344         int remote_port;
1345
1346         if (FD_ISSET(c->sock, readset)) {
1347                 debug("X11 connection requested.");
1348                 addrlen = sizeof(addr);
1349                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1350                 if (c->single_connection) {
1351                         oerrno = errno;
1352                         debug2("single_connection: closing X11 listener.");
1353                         channel_close_fd(&c->sock);
1354                         chan_mark_dead(c);
1355                         errno = oerrno;
1356                 }
1357                 if (newsock < 0) {
1358                         if (errno != EINTR && errno != EWOULDBLOCK &&
1359                             errno != ECONNABORTED)
1360                                 error("accept: %.100s", strerror(errno));
1361                         if (errno == EMFILE || errno == ENFILE)
1362                                 c->notbefore = monotime() + 1;
1363                         return;
1364                 }
1365                 set_nodelay(newsock);
1366                 remote_ipaddr = get_peer_ipaddr(newsock);
1367                 remote_port = get_peer_port(newsock);
1368                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1369                     remote_ipaddr, remote_port);
1370
1371                 nc = channel_new("accepted x11 socket",
1372                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1373                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1374                 if (compat20) {
1375                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1376                         packet_put_cstring("x11");
1377                         packet_put_int(nc->self);
1378                         packet_put_int(nc->local_window_max);
1379                         packet_put_int(nc->local_maxpacket);
1380                         /* originator ipaddr and port */
1381                         packet_put_cstring(remote_ipaddr);
1382                         if (datafellows & SSH_BUG_X11FWD) {
1383                                 debug2("ssh2 x11 bug compat mode");
1384                         } else {
1385                                 packet_put_int(remote_port);
1386                         }
1387                         packet_send();
1388                 } else {
1389                         packet_start(SSH_SMSG_X11_OPEN);
1390                         packet_put_int(nc->self);
1391                         if (packet_get_protocol_flags() &
1392                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1393                                 packet_put_cstring(buf);
1394                         packet_send();
1395                 }
1396                 free(remote_ipaddr);
1397         }
1398 }
1399
1400 static void
1401 port_open_helper(Channel *c, char *rtype)
1402 {
1403         char buf[1024];
1404         char *local_ipaddr = get_local_ipaddr(c->sock);
1405         int local_port = c->sock == -1 ? 65536 : get_sock_port(c->sock, 1);
1406         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1407         int remote_port = get_peer_port(c->sock);
1408
1409         if (remote_port == -1) {
1410                 /* Fake addr/port to appease peers that validate it (Tectia) */
1411                 free(remote_ipaddr);
1412                 remote_ipaddr = xstrdup("127.0.0.1");
1413                 remote_port = 65535;
1414         }
1415
1416         snprintf(buf, sizeof buf,
1417             "%s: listening port %d for %.100s port %d, "
1418             "connect from %.200s port %d to %.100s port %d",
1419             rtype, c->listening_port, c->path, c->host_port,
1420             remote_ipaddr, remote_port, local_ipaddr, local_port);
1421
1422         free(c->remote_name);
1423         c->remote_name = xstrdup(buf);
1424
1425         if (compat20) {
1426                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1427                 packet_put_cstring(rtype);
1428                 packet_put_int(c->self);
1429                 packet_put_int(c->local_window_max);
1430                 packet_put_int(c->local_maxpacket);
1431                 if (strcmp(rtype, "direct-tcpip") == 0) {
1432                         /* target host, port */
1433                         packet_put_cstring(c->path);
1434                         packet_put_int(c->host_port);
1435                 } else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) {
1436                         /* target path */
1437                         packet_put_cstring(c->path);
1438                 } else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
1439                         /* listen path */
1440                         packet_put_cstring(c->path);
1441                 } else {
1442                         /* listen address, port */
1443                         packet_put_cstring(c->path);
1444                         packet_put_int(local_port);
1445                 }
1446                 if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
1447                         /* reserved for future owner/mode info */
1448                         packet_put_cstring("");
1449                 } else {
1450                         /* originator host and port */
1451                         packet_put_cstring(remote_ipaddr);
1452                         packet_put_int((u_int)remote_port);
1453                 }
1454                 packet_send();
1455         } else {
1456                 packet_start(SSH_MSG_PORT_OPEN);
1457                 packet_put_int(c->self);
1458                 packet_put_cstring(c->path);
1459                 packet_put_int(c->host_port);
1460                 if (packet_get_protocol_flags() &
1461                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1462                         packet_put_cstring(c->remote_name);
1463                 packet_send();
1464         }
1465         free(remote_ipaddr);
1466         free(local_ipaddr);
1467 }
1468
1469 static void
1470 channel_set_reuseaddr(int fd)
1471 {
1472         int on = 1;
1473
1474         /*
1475          * Set socket options.
1476          * Allow local port reuse in TIME_WAIT.
1477          */
1478         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1479                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1480 }
1481
1482 /*
1483  * This socket is listening for connections to a forwarded TCP/IP port.
1484  */
1485 /* ARGSUSED */
1486 static void
1487 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1488 {
1489         Channel *nc;
1490         struct sockaddr_storage addr;
1491         int newsock, nextstate;
1492         socklen_t addrlen;
1493         char *rtype;
1494
1495         if (FD_ISSET(c->sock, readset)) {
1496                 debug("Connection to port %d forwarding "
1497                     "to %.100s port %d requested.",
1498                     c->listening_port, c->path, c->host_port);
1499
1500                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1501                         nextstate = SSH_CHANNEL_OPENING;
1502                         rtype = "forwarded-tcpip";
1503                 } else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) {
1504                         nextstate = SSH_CHANNEL_OPENING;
1505                         rtype = "forwarded-streamlocal@openssh.com";
1506                 } else if (c->host_port == PORT_STREAMLOCAL) {
1507                         nextstate = SSH_CHANNEL_OPENING;
1508                         rtype = "direct-streamlocal@openssh.com";
1509                 } else if (c->host_port == 0) {
1510                         nextstate = SSH_CHANNEL_DYNAMIC;
1511                         rtype = "dynamic-tcpip";
1512                 } else {
1513                         nextstate = SSH_CHANNEL_OPENING;
1514                         rtype = "direct-tcpip";
1515                 }
1516
1517                 addrlen = sizeof(addr);
1518                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1519                 if (newsock < 0) {
1520                         if (errno != EINTR && errno != EWOULDBLOCK &&
1521                             errno != ECONNABORTED)
1522                                 error("accept: %.100s", strerror(errno));
1523                         if (errno == EMFILE || errno == ENFILE)
1524                                 c->notbefore = monotime() + 1;
1525                         return;
1526                 }
1527                 if (c->host_port != PORT_STREAMLOCAL)
1528                         set_nodelay(newsock);
1529                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1530                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1531                 nc->listening_port = c->listening_port;
1532                 nc->host_port = c->host_port;
1533                 if (c->path != NULL)
1534                         nc->path = xstrdup(c->path);
1535
1536                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1537                         port_open_helper(nc, rtype);
1538         }
1539 }
1540
1541 /*
1542  * This is the authentication agent socket listening for connections from
1543  * clients.
1544  */
1545 /* ARGSUSED */
1546 static void
1547 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1548 {
1549         Channel *nc;
1550         int newsock;
1551         struct sockaddr_storage addr;
1552         socklen_t addrlen;
1553
1554         if (FD_ISSET(c->sock, readset)) {
1555                 addrlen = sizeof(addr);
1556                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1557                 if (newsock < 0) {
1558                         error("accept from auth socket: %.100s",
1559                             strerror(errno));
1560                         if (errno == EMFILE || errno == ENFILE)
1561                                 c->notbefore = monotime() + 1;
1562                         return;
1563                 }
1564                 nc = channel_new("accepted auth socket",
1565                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1566                     c->local_window_max, c->local_maxpacket,
1567                     0, "accepted auth socket", 1);
1568                 if (compat20) {
1569                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1570                         packet_put_cstring("auth-agent@openssh.com");
1571                         packet_put_int(nc->self);
1572                         packet_put_int(c->local_window_max);
1573                         packet_put_int(c->local_maxpacket);
1574                 } else {
1575                         packet_start(SSH_SMSG_AGENT_OPEN);
1576                         packet_put_int(nc->self);
1577                 }
1578                 packet_send();
1579         }
1580 }
1581
1582 /* ARGSUSED */
1583 static void
1584 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1585 {
1586         int err = 0, sock;
1587         socklen_t sz = sizeof(err);
1588
1589         if (FD_ISSET(c->sock, writeset)) {
1590                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1591                         err = errno;
1592                         error("getsockopt SO_ERROR failed");
1593                 }
1594                 if (err == 0) {
1595                         debug("channel %d: connected to %s port %d",
1596                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1597                         channel_connect_ctx_free(&c->connect_ctx);
1598                         c->type = SSH_CHANNEL_OPEN;
1599                         if (compat20) {
1600                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1601                                 packet_put_int(c->remote_id);
1602                                 packet_put_int(c->self);
1603                                 packet_put_int(c->local_window);
1604                                 packet_put_int(c->local_maxpacket);
1605                         } else {
1606                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1607                                 packet_put_int(c->remote_id);
1608                                 packet_put_int(c->self);
1609                         }
1610                 } else {
1611                         debug("channel %d: connection failed: %s",
1612                             c->self, strerror(err));
1613                         /* Try next address, if any */
1614                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1615                                 close(c->sock);
1616                                 c->sock = c->rfd = c->wfd = sock;
1617                                 channel_max_fd = channel_find_maxfd();
1618                                 return;
1619                         }
1620                         /* Exhausted all addresses */
1621                         error("connect_to %.100s port %d: failed.",
1622                             c->connect_ctx.host, c->connect_ctx.port);
1623                         channel_connect_ctx_free(&c->connect_ctx);
1624                         if (compat20) {
1625                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1626                                 packet_put_int(c->remote_id);
1627                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1628                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1629                                         packet_put_cstring(strerror(err));
1630                                         packet_put_cstring("");
1631                                 }
1632                         } else {
1633                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1634                                 packet_put_int(c->remote_id);
1635                         }
1636                         chan_mark_dead(c);
1637                 }
1638                 packet_send();
1639         }
1640 }
1641
1642 /* ARGSUSED */
1643 static int
1644 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1645 {
1646         char buf[CHAN_RBUF];
1647         int len, force;
1648
1649         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1650         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1651                 errno = 0;
1652                 len = read(c->rfd, buf, sizeof(buf));
1653                 if (len < 0 && (errno == EINTR ||
1654                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1655                         return 1;
1656 #ifndef PTY_ZEROREAD
1657                 if (len <= 0) {
1658 #else
1659                 if ((!c->isatty && len <= 0) ||
1660                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1661 #endif
1662                         debug2("channel %d: read<=0 rfd %d len %d",
1663                             c->self, c->rfd, len);
1664                         if (c->type != SSH_CHANNEL_OPEN) {
1665                                 debug2("channel %d: not open", c->self);
1666                                 chan_mark_dead(c);
1667                                 return -1;
1668                         } else if (compat13) {
1669                                 buffer_clear(&c->output);
1670                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1671                                 debug2("channel %d: input draining.", c->self);
1672                         } else {
1673                                 chan_read_failed(c);
1674                         }
1675                         return -1;
1676                 }
1677                 if (c->input_filter != NULL) {
1678                         if (c->input_filter(c, buf, len) == -1) {
1679                                 debug2("channel %d: filter stops", c->self);
1680                                 chan_read_failed(c);
1681                         }
1682                 } else if (c->datagram) {
1683                         buffer_put_string(&c->input, buf, len);
1684                 } else {
1685                         buffer_append(&c->input, buf, len);
1686                 }
1687         }
1688         return 1;
1689 }
1690
1691 /* ARGSUSED */
1692 static int
1693 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1694 {
1695         struct termios tio;
1696         u_char *data = NULL, *buf;
1697         u_int dlen, olen = 0;
1698         int len;
1699
1700         /* Send buffered output data to the socket. */
1701         if (c->wfd != -1 &&
1702             FD_ISSET(c->wfd, writeset) &&
1703             buffer_len(&c->output) > 0) {
1704                 olen = buffer_len(&c->output);
1705                 if (c->output_filter != NULL) {
1706                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1707                                 debug2("channel %d: filter stops", c->self);
1708                                 if (c->type != SSH_CHANNEL_OPEN)
1709                                         chan_mark_dead(c);
1710                                 else
1711                                         chan_write_failed(c);
1712                                 return -1;
1713                         }
1714                 } else if (c->datagram) {
1715                         buf = data = buffer_get_string(&c->output, &dlen);
1716                 } else {
1717                         buf = data = buffer_ptr(&c->output);
1718                         dlen = buffer_len(&c->output);
1719                 }
1720
1721                 if (c->datagram) {
1722                         /* ignore truncated writes, datagrams might get lost */
1723                         len = write(c->wfd, buf, dlen);
1724                         free(data);
1725                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1726                             errno == EWOULDBLOCK))
1727                                 return 1;
1728                         if (len <= 0) {
1729                                 if (c->type != SSH_CHANNEL_OPEN)
1730                                         chan_mark_dead(c);
1731                                 else
1732                                         chan_write_failed(c);
1733                                 return -1;
1734                         }
1735                         goto out;
1736                 }
1737 #ifdef _AIX
1738                 /* XXX: Later AIX versions can't push as much data to tty */
1739                 if (compat20 && c->wfd_isatty)
1740                         dlen = MIN(dlen, 8*1024);
1741 #endif
1742
1743                 len = write(c->wfd, buf, dlen);
1744                 if (len < 0 &&
1745                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1746                         return 1;
1747                 if (len <= 0) {
1748                         if (c->type != SSH_CHANNEL_OPEN) {
1749                                 debug2("channel %d: not open", c->self);
1750                                 chan_mark_dead(c);
1751                                 return -1;
1752                         } else if (compat13) {
1753                                 buffer_clear(&c->output);
1754                                 debug2("channel %d: input draining.", c->self);
1755                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1756                         } else {
1757                                 chan_write_failed(c);
1758                         }
1759                         return -1;
1760                 }
1761 #ifndef BROKEN_TCGETATTR_ICANON
1762                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1763                         if (tcgetattr(c->wfd, &tio) == 0 &&
1764                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1765                                 /*
1766                                  * Simulate echo to reduce the impact of
1767                                  * traffic analysis. We need to match the
1768                                  * size of a SSH2_MSG_CHANNEL_DATA message
1769                                  * (4 byte channel id + buf)
1770                                  */
1771                                 packet_send_ignore(4 + len);
1772                                 packet_send();
1773                         }
1774                 }
1775 #endif
1776                 buffer_consume(&c->output, len);
1777         }
1778  out:
1779         if (compat20 && olen > 0)
1780                 c->local_consumed += olen - buffer_len(&c->output);
1781         return 1;
1782 }
1783
1784 static int
1785 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1786 {
1787         char buf[CHAN_RBUF];
1788         int len;
1789
1790 /** XXX handle drain efd, too */
1791         if (c->efd != -1) {
1792                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1793                     FD_ISSET(c->efd, writeset) &&
1794                     buffer_len(&c->extended) > 0) {
1795                         len = write(c->efd, buffer_ptr(&c->extended),
1796                             buffer_len(&c->extended));
1797                         debug2("channel %d: written %d to efd %d",
1798                             c->self, len, c->efd);
1799                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1800                             errno == EWOULDBLOCK))
1801                                 return 1;
1802                         if (len <= 0) {
1803                                 debug2("channel %d: closing write-efd %d",
1804                                     c->self, c->efd);
1805                                 channel_close_fd(&c->efd);
1806                         } else {
1807                                 buffer_consume(&c->extended, len);
1808                                 c->local_consumed += len;
1809                         }
1810                 } else if (c->efd != -1 &&
1811                     (c->extended_usage == CHAN_EXTENDED_READ ||
1812                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
1813                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1814                         len = read(c->efd, buf, sizeof(buf));
1815                         debug2("channel %d: read %d from efd %d",
1816                             c->self, len, c->efd);
1817                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1818                             errno == EWOULDBLOCK) && !c->detach_close)))
1819                                 return 1;
1820                         if (len <= 0) {
1821                                 debug2("channel %d: closing read-efd %d",
1822                                     c->self, c->efd);
1823                                 channel_close_fd(&c->efd);
1824                         } else {
1825                                 if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
1826                                         debug3("channel %d: discard efd",
1827                                             c->self);
1828                                 } else
1829                                         buffer_append(&c->extended, buf, len);
1830                         }
1831                 }
1832         }
1833         return 1;
1834 }
1835
1836 static int
1837 channel_check_window(Channel *c)
1838 {
1839         if (c->type == SSH_CHANNEL_OPEN &&
1840             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1841             ((c->local_window_max - c->local_window >
1842             c->local_maxpacket*3) ||
1843             c->local_window < c->local_window_max/2) &&
1844             c->local_consumed > 0) {
1845                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1846                 packet_put_int(c->remote_id);
1847                 packet_put_int(c->local_consumed);
1848                 packet_send();
1849                 debug2("channel %d: window %d sent adjust %d",
1850                     c->self, c->local_window,
1851                     c->local_consumed);
1852                 c->local_window += c->local_consumed;
1853                 c->local_consumed = 0;
1854         }
1855         return 1;
1856 }
1857
1858 static void
1859 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1860 {
1861         channel_handle_rfd(c, readset, writeset);
1862         channel_handle_wfd(c, readset, writeset);
1863         if (!compat20)
1864                 return;
1865         channel_handle_efd(c, readset, writeset);
1866         channel_check_window(c);
1867 }
1868
1869 static u_int
1870 read_mux(Channel *c, u_int need)
1871 {
1872         char buf[CHAN_RBUF];
1873         int len;
1874         u_int rlen;
1875
1876         if (buffer_len(&c->input) < need) {
1877                 rlen = need - buffer_len(&c->input);
1878                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1879                 if (len <= 0) {
1880                         if (errno != EINTR && errno != EAGAIN) {
1881                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1882                                     c->self, c->rfd, len);
1883                                 chan_read_failed(c);
1884                                 return 0;
1885                         }
1886                 } else
1887                         buffer_append(&c->input, buf, len);
1888         }
1889         return buffer_len(&c->input);
1890 }
1891
1892 static void
1893 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1894 {
1895         u_int need;
1896         ssize_t len;
1897
1898         if (!compat20)
1899                 fatal("%s: entered with !compat20", __func__);
1900
1901         if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
1902             (c->istate == CHAN_INPUT_OPEN ||
1903             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1904                 /*
1905                  * Don't not read past the precise end of packets to
1906                  * avoid disrupting fd passing.
1907                  */
1908                 if (read_mux(c, 4) < 4) /* read header */
1909                         return;
1910                 need = get_u32(buffer_ptr(&c->input));
1911 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1912                 if (need > CHANNEL_MUX_MAX_PACKET) {
1913                         debug2("channel %d: packet too big %u > %u",
1914                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1915                         chan_rcvd_oclose(c);
1916                         return;
1917                 }
1918                 if (read_mux(c, need + 4) < need + 4) /* read body */
1919                         return;
1920                 if (c->mux_rcb(c) != 0) {
1921                         debug("channel %d: mux_rcb failed", c->self);
1922                         chan_mark_dead(c);
1923                         return;
1924                 }
1925         }
1926
1927         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1928             buffer_len(&c->output) > 0) {
1929                 len = write(c->wfd, buffer_ptr(&c->output),
1930                     buffer_len(&c->output));
1931                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1932                         return;
1933                 if (len <= 0) {
1934                         chan_mark_dead(c);
1935                         return;
1936                 }
1937                 buffer_consume(&c->output, len);
1938         }
1939 }
1940
1941 static void
1942 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1943 {
1944         Channel *nc;
1945         struct sockaddr_storage addr;
1946         socklen_t addrlen;
1947         int newsock;
1948         uid_t euid;
1949         gid_t egid;
1950
1951         if (!FD_ISSET(c->sock, readset))
1952                 return;
1953
1954         debug("multiplexing control connection");
1955
1956         /*
1957          * Accept connection on control socket
1958          */
1959         memset(&addr, 0, sizeof(addr));
1960         addrlen = sizeof(addr);
1961         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1962             &addrlen)) == -1) {
1963                 error("%s accept: %s", __func__, strerror(errno));
1964                 if (errno == EMFILE || errno == ENFILE)
1965                         c->notbefore = monotime() + 1;
1966                 return;
1967         }
1968
1969         if (getpeereid(newsock, &euid, &egid) < 0) {
1970                 error("%s getpeereid failed: %s", __func__,
1971                     strerror(errno));
1972                 close(newsock);
1973                 return;
1974         }
1975         if ((euid != 0) && (getuid() != euid)) {
1976                 error("multiplex uid mismatch: peer euid %u != uid %u",
1977                     (u_int)euid, (u_int)getuid());
1978                 close(newsock);
1979                 return;
1980         }
1981         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
1982             newsock, newsock, -1, c->local_window_max,
1983             c->local_maxpacket, 0, "mux-control", 1);
1984         nc->mux_rcb = c->mux_rcb;
1985         debug3("%s: new mux channel %d fd %d", __func__,
1986             nc->self, nc->sock);
1987         /* establish state */
1988         nc->mux_rcb(nc);
1989         /* mux state transitions must not elicit protocol messages */
1990         nc->flags |= CHAN_LOCAL;
1991 }
1992
1993 /* ARGSUSED */
1994 static void
1995 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1996 {
1997         int len;
1998
1999         /* Send buffered output data to the socket. */
2000         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
2001                 len = write(c->sock, buffer_ptr(&c->output),
2002                             buffer_len(&c->output));
2003                 if (len <= 0)
2004                         buffer_clear(&c->output);
2005                 else
2006                         buffer_consume(&c->output, len);
2007         }
2008 }
2009
2010 static void
2011 channel_handler_init_20(void)
2012 {
2013         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2014         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2015         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2016         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
2017         channel_pre[SSH_CHANNEL_UNIX_LISTENER] =        &channel_pre_listener;
2018         channel_pre[SSH_CHANNEL_RUNIX_LISTENER] =       &channel_pre_listener;
2019         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2020         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2021         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2022         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2023         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
2024         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
2025
2026         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2027         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2028         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
2029         channel_post[SSH_CHANNEL_UNIX_LISTENER] =       &channel_post_port_listener;
2030         channel_post[SSH_CHANNEL_RUNIX_LISTENER] =      &channel_post_port_listener;
2031         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2032         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2033         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2034         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2035         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
2036         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
2037 }
2038
2039 static void
2040 channel_handler_init_13(void)
2041 {
2042         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
2043         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
2044         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2045         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2046         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2047         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
2048         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
2049         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2050         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2051
2052         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2053         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2054         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2055         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2056         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
2057         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2058         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2059 }
2060
2061 static void
2062 channel_handler_init_15(void)
2063 {
2064         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2065         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2066         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2067         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2068         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2069         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2070         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2071
2072         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2073         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2074         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2075         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2076         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2077         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2078 }
2079
2080 static void
2081 channel_handler_init(void)
2082 {
2083         int i;
2084
2085         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2086                 channel_pre[i] = NULL;
2087                 channel_post[i] = NULL;
2088         }
2089         if (compat20)
2090                 channel_handler_init_20();
2091         else if (compat13)
2092                 channel_handler_init_13();
2093         else
2094                 channel_handler_init_15();
2095 }
2096
2097 /* gc dead channels */
2098 static void
2099 channel_garbage_collect(Channel *c)
2100 {
2101         if (c == NULL)
2102                 return;
2103         if (c->detach_user != NULL) {
2104                 if (!chan_is_dead(c, c->detach_close))
2105                         return;
2106                 debug2("channel %d: gc: notify user", c->self);
2107                 c->detach_user(c->self, NULL);
2108                 /* if we still have a callback */
2109                 if (c->detach_user != NULL)
2110                         return;
2111                 debug2("channel %d: gc: user detached", c->self);
2112         }
2113         if (!chan_is_dead(c, 1))
2114                 return;
2115         debug2("channel %d: garbage collecting", c->self);
2116         channel_free(c);
2117 }
2118
2119 static void
2120 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
2121     time_t *unpause_secs)
2122 {
2123         static int did_init = 0;
2124         u_int i, oalloc;
2125         Channel *c;
2126         time_t now;
2127
2128         if (!did_init) {
2129                 channel_handler_init();
2130                 did_init = 1;
2131         }
2132         now = monotime();
2133         if (unpause_secs != NULL)
2134                 *unpause_secs = 0;
2135         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2136                 c = channels[i];
2137                 if (c == NULL)
2138                         continue;
2139                 if (c->delayed) {
2140                         if (ftab == channel_pre)
2141                                 c->delayed = 0;
2142                         else
2143                                 continue;
2144                 }
2145                 if (ftab[c->type] != NULL) {
2146                         /*
2147                          * Run handlers that are not paused.
2148                          */
2149                         if (c->notbefore <= now)
2150                                 (*ftab[c->type])(c, readset, writeset);
2151                         else if (unpause_secs != NULL) {
2152                                 /*
2153                                  * Collect the time that the earliest
2154                                  * channel comes off pause.
2155                                  */
2156                                 debug3("%s: chan %d: skip for %d more seconds",
2157                                     __func__, c->self,
2158                                     (int)(c->notbefore - now));
2159                                 if (*unpause_secs == 0 ||
2160                                     (c->notbefore - now) < *unpause_secs)
2161                                         *unpause_secs = c->notbefore - now;
2162                         }
2163                 }
2164                 channel_garbage_collect(c);
2165         }
2166         if (unpause_secs != NULL && *unpause_secs != 0)
2167                 debug3("%s: first channel unpauses in %d seconds",
2168                     __func__, (int)*unpause_secs);
2169 }
2170
2171 /*
2172  * Allocate/update select bitmasks and add any bits relevant to channels in
2173  * select bitmasks.
2174  */
2175 void
2176 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2177     u_int *nallocp, time_t *minwait_secs, int rekeying)
2178 {
2179         u_int n, sz, nfdset;
2180
2181         n = MAX(*maxfdp, channel_max_fd);
2182
2183         nfdset = howmany(n+1, NFDBITS);
2184         /* Explicitly test here, because xrealloc isn't always called */
2185         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
2186                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2187         sz = nfdset * sizeof(fd_mask);
2188
2189         /* perhaps check sz < nalloc/2 and shrink? */
2190         if (*readsetp == NULL || sz > *nallocp) {
2191                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2192                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2193                 *nallocp = sz;
2194         }
2195         *maxfdp = n;
2196         memset(*readsetp, 0, sz);
2197         memset(*writesetp, 0, sz);
2198
2199         if (!rekeying)
2200                 channel_handler(channel_pre, *readsetp, *writesetp,
2201                     minwait_secs);
2202 }
2203
2204 /*
2205  * After select, perform any appropriate operations for channels which have
2206  * events pending.
2207  */
2208 void
2209 channel_after_select(fd_set *readset, fd_set *writeset)
2210 {
2211         channel_handler(channel_post, readset, writeset, NULL);
2212 }
2213
2214
2215 /* If there is data to send to the connection, enqueue some of it now. */
2216 void
2217 channel_output_poll(void)
2218 {
2219         Channel *c;
2220         u_int i, len;
2221
2222         for (i = 0; i < channels_alloc; i++) {
2223                 c = channels[i];
2224                 if (c == NULL)
2225                         continue;
2226
2227                 /*
2228                  * We are only interested in channels that can have buffered
2229                  * incoming data.
2230                  */
2231                 if (compat13) {
2232                         if (c->type != SSH_CHANNEL_OPEN &&
2233                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2234                                 continue;
2235                 } else {
2236                         if (c->type != SSH_CHANNEL_OPEN)
2237                                 continue;
2238                 }
2239                 if (compat20 &&
2240                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2241                         /* XXX is this true? */
2242                         debug3("channel %d: will not send data after close", c->self);
2243                         continue;
2244                 }
2245
2246                 /* Get the amount of buffered data for this channel. */
2247                 if ((c->istate == CHAN_INPUT_OPEN ||
2248                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2249                     (len = buffer_len(&c->input)) > 0) {
2250                         if (c->datagram) {
2251                                 if (len > 0) {
2252                                         u_char *data;
2253                                         u_int dlen;
2254
2255                                         data = buffer_get_string(&c->input,
2256                                             &dlen);
2257                                         if (dlen > c->remote_window ||
2258                                             dlen > c->remote_maxpacket) {
2259                                                 debug("channel %d: datagram "
2260                                                     "too big for channel",
2261                                                     c->self);
2262                                                 free(data);
2263                                                 continue;
2264                                         }
2265                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2266                                         packet_put_int(c->remote_id);
2267                                         packet_put_string(data, dlen);
2268                                         packet_send();
2269                                         c->remote_window -= dlen + 4;
2270                                         free(data);
2271                                 }
2272                                 continue;
2273                         }
2274                         /*
2275                          * Send some data for the other side over the secure
2276                          * connection.
2277                          */
2278                         if (compat20) {
2279                                 if (len > c->remote_window)
2280                                         len = c->remote_window;
2281                                 if (len > c->remote_maxpacket)
2282                                         len = c->remote_maxpacket;
2283                         } else {
2284                                 if (packet_is_interactive()) {
2285                                         if (len > 1024)
2286                                                 len = 512;
2287                                 } else {
2288                                         /* Keep the packets at reasonable size. */
2289                                         if (len > packet_get_maxsize()/2)
2290                                                 len = packet_get_maxsize()/2;
2291                                 }
2292                         }
2293                         if (len > 0) {
2294                                 packet_start(compat20 ?
2295                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2296                                 packet_put_int(c->remote_id);
2297                                 packet_put_string(buffer_ptr(&c->input), len);
2298                                 packet_send();
2299                                 buffer_consume(&c->input, len);
2300                                 c->remote_window -= len;
2301                         }
2302                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2303                         if (compat13)
2304                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2305                         /*
2306                          * input-buffer is empty and read-socket shutdown:
2307                          * tell peer, that we will not send more data: send IEOF.
2308                          * hack for extended data: delay EOF if EFD still in use.
2309                          */
2310                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2311                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2312                                     c->self, c->efd, buffer_len(&c->extended));
2313                         else
2314                                 chan_ibuf_empty(c);
2315                 }
2316                 /* Send extended data, i.e. stderr */
2317                 if (compat20 &&
2318                     !(c->flags & CHAN_EOF_SENT) &&
2319                     c->remote_window > 0 &&
2320                     (len = buffer_len(&c->extended)) > 0 &&
2321                     c->extended_usage == CHAN_EXTENDED_READ) {
2322                         debug2("channel %d: rwin %u elen %u euse %d",
2323                             c->self, c->remote_window, buffer_len(&c->extended),
2324                             c->extended_usage);
2325                         if (len > c->remote_window)
2326                                 len = c->remote_window;
2327                         if (len > c->remote_maxpacket)
2328                                 len = c->remote_maxpacket;
2329                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2330                         packet_put_int(c->remote_id);
2331                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2332                         packet_put_string(buffer_ptr(&c->extended), len);
2333                         packet_send();
2334                         buffer_consume(&c->extended, len);
2335                         c->remote_window -= len;
2336                         debug2("channel %d: sent ext data %d", c->self, len);
2337                 }
2338         }
2339 }
2340
2341
2342 /* -- protocol input */
2343
2344 /* ARGSUSED */
2345 void
2346 channel_input_data(int type, u_int32_t seq, void *ctxt)
2347 {
2348         int id;
2349         const u_char *data;
2350         u_int data_len, win_len;
2351         Channel *c;
2352
2353         /* Get the channel number and verify it. */
2354         id = packet_get_int();
2355         c = channel_lookup(id);
2356         if (c == NULL)
2357                 packet_disconnect("Received data for nonexistent channel %d.", id);
2358
2359         /* Ignore any data for non-open channels (might happen on close) */
2360         if (c->type != SSH_CHANNEL_OPEN &&
2361             c->type != SSH_CHANNEL_X11_OPEN)
2362                 return;
2363
2364         /* Get the data. */
2365         data = packet_get_string_ptr(&data_len);
2366         win_len = data_len;
2367         if (c->datagram)
2368                 win_len += 4;  /* string length header */
2369
2370         /*
2371          * Ignore data for protocol > 1.3 if output end is no longer open.
2372          * For protocol 2 the sending side is reducing its window as it sends
2373          * data, so we must 'fake' consumption of the data in order to ensure
2374          * that window updates are sent back.  Otherwise the connection might
2375          * deadlock.
2376          */
2377         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2378                 if (compat20) {
2379                         c->local_window -= win_len;
2380                         c->local_consumed += win_len;
2381                 }
2382                 return;
2383         }
2384
2385         if (compat20) {
2386                 if (win_len > c->local_maxpacket) {
2387                         logit("channel %d: rcvd big packet %d, maxpack %d",
2388                             c->self, win_len, c->local_maxpacket);
2389                 }
2390                 if (win_len > c->local_window) {
2391                         logit("channel %d: rcvd too much data %d, win %d",
2392                             c->self, win_len, c->local_window);
2393                         return;
2394                 }
2395                 c->local_window -= win_len;
2396         }
2397         if (c->datagram)
2398                 buffer_put_string(&c->output, data, data_len);
2399         else
2400                 buffer_append(&c->output, data, data_len);
2401         packet_check_eom();
2402 }
2403
2404 /* ARGSUSED */
2405 void
2406 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2407 {
2408         int id;
2409         char *data;
2410         u_int data_len, tcode;
2411         Channel *c;
2412
2413         /* Get the channel number and verify it. */
2414         id = packet_get_int();
2415         c = channel_lookup(id);
2416
2417         if (c == NULL)
2418                 packet_disconnect("Received extended_data for bad channel %d.", id);
2419         if (c->type != SSH_CHANNEL_OPEN) {
2420                 logit("channel %d: ext data for non open", id);
2421                 return;
2422         }
2423         if (c->flags & CHAN_EOF_RCVD) {
2424                 if (datafellows & SSH_BUG_EXTEOF)
2425                         debug("channel %d: accepting ext data after eof", id);
2426                 else
2427                         packet_disconnect("Received extended_data after EOF "
2428                             "on channel %d.", id);
2429         }
2430         tcode = packet_get_int();
2431         if (c->efd == -1 ||
2432             c->extended_usage != CHAN_EXTENDED_WRITE ||
2433             tcode != SSH2_EXTENDED_DATA_STDERR) {
2434                 logit("channel %d: bad ext data", c->self);
2435                 return;
2436         }
2437         data = packet_get_string(&data_len);
2438         packet_check_eom();
2439         if (data_len > c->local_window) {
2440                 logit("channel %d: rcvd too much extended_data %d, win %d",
2441                     c->self, data_len, c->local_window);
2442                 free(data);
2443                 return;
2444         }
2445         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2446         c->local_window -= data_len;
2447         buffer_append(&c->extended, data, data_len);
2448         free(data);
2449 }
2450
2451 /* ARGSUSED */
2452 void
2453 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2454 {
2455         int id;
2456         Channel *c;
2457
2458         id = packet_get_int();
2459         packet_check_eom();
2460         c = channel_lookup(id);
2461         if (c == NULL)
2462                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2463         chan_rcvd_ieof(c);
2464
2465         /* XXX force input close */
2466         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2467                 debug("channel %d: FORCE input drain", c->self);
2468                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2469                 if (buffer_len(&c->input) == 0)
2470                         chan_ibuf_empty(c);
2471         }
2472
2473 }
2474
2475 /* ARGSUSED */
2476 void
2477 channel_input_close(int type, u_int32_t seq, void *ctxt)
2478 {
2479         int id;
2480         Channel *c;
2481
2482         id = packet_get_int();
2483         packet_check_eom();
2484         c = channel_lookup(id);
2485         if (c == NULL)
2486                 packet_disconnect("Received close for nonexistent channel %d.", id);
2487
2488         /*
2489          * Send a confirmation that we have closed the channel and no more
2490          * data is coming for it.
2491          */
2492         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2493         packet_put_int(c->remote_id);
2494         packet_send();
2495
2496         /*
2497          * If the channel is in closed state, we have sent a close request,
2498          * and the other side will eventually respond with a confirmation.
2499          * Thus, we cannot free the channel here, because then there would be
2500          * no-one to receive the confirmation.  The channel gets freed when
2501          * the confirmation arrives.
2502          */
2503         if (c->type != SSH_CHANNEL_CLOSED) {
2504                 /*
2505                  * Not a closed channel - mark it as draining, which will
2506                  * cause it to be freed later.
2507                  */
2508                 buffer_clear(&c->input);
2509                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2510         }
2511 }
2512
2513 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2514 /* ARGSUSED */
2515 void
2516 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2517 {
2518         int id = packet_get_int();
2519         Channel *c = channel_lookup(id);
2520
2521         packet_check_eom();
2522         if (c == NULL)
2523                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2524         chan_rcvd_oclose(c);
2525 }
2526
2527 /* ARGSUSED */
2528 void
2529 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2530 {
2531         int id = packet_get_int();
2532         Channel *c = channel_lookup(id);
2533
2534         packet_check_eom();
2535         if (c == NULL)
2536                 packet_disconnect("Received close confirmation for "
2537                     "out-of-range channel %d.", id);
2538         if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
2539                 packet_disconnect("Received close confirmation for "
2540                     "non-closed channel %d (type %d).", id, c->type);
2541         channel_free(c);
2542 }
2543
2544 /* ARGSUSED */
2545 void
2546 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2547 {
2548         int id, remote_id;
2549         Channel *c;
2550
2551         id = packet_get_int();
2552         c = channel_lookup(id);
2553
2554         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2555                 packet_disconnect("Received open confirmation for "
2556                     "non-opening channel %d.", id);
2557         remote_id = packet_get_int();
2558         /* Record the remote channel number and mark that the channel is now open. */
2559         c->remote_id = remote_id;
2560         c->type = SSH_CHANNEL_OPEN;
2561
2562         if (compat20) {
2563                 c->remote_window = packet_get_int();
2564                 c->remote_maxpacket = packet_get_int();
2565                 if (c->open_confirm) {
2566                         debug2("callback start");
2567                         c->open_confirm(c->self, 1, c->open_confirm_ctx);
2568                         debug2("callback done");
2569                 }
2570                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2571                     c->remote_window, c->remote_maxpacket);
2572         }
2573         packet_check_eom();
2574 }
2575
2576 static char *
2577 reason2txt(int reason)
2578 {
2579         switch (reason) {
2580         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2581                 return "administratively prohibited";
2582         case SSH2_OPEN_CONNECT_FAILED:
2583                 return "connect failed";
2584         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2585                 return "unknown channel type";
2586         case SSH2_OPEN_RESOURCE_SHORTAGE:
2587                 return "resource shortage";
2588         }
2589         return "unknown reason";
2590 }
2591
2592 /* ARGSUSED */
2593 void
2594 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2595 {
2596         int id, reason;
2597         char *msg = NULL, *lang = NULL;
2598         Channel *c;
2599
2600         id = packet_get_int();
2601         c = channel_lookup(id);
2602
2603         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2604                 packet_disconnect("Received open failure for "
2605                     "non-opening channel %d.", id);
2606         if (compat20) {
2607                 reason = packet_get_int();
2608                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2609                         msg  = packet_get_string(NULL);
2610                         lang = packet_get_string(NULL);
2611                 }
2612                 logit("channel %d: open failed: %s%s%s", id,
2613                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2614                 free(msg);
2615                 free(lang);
2616                 if (c->open_confirm) {
2617                         debug2("callback start");
2618                         c->open_confirm(c->self, 0, c->open_confirm_ctx);
2619                         debug2("callback done");
2620                 }
2621         }
2622         packet_check_eom();
2623         /* Schedule the channel for cleanup/deletion. */
2624         chan_mark_dead(c);
2625 }
2626
2627 /* ARGSUSED */
2628 void
2629 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2630 {
2631         Channel *c;
2632         int id;
2633         u_int adjust;
2634
2635         if (!compat20)
2636                 return;
2637
2638         /* Get the channel number and verify it. */
2639         id = packet_get_int();
2640         c = channel_lookup(id);
2641
2642         if (c == NULL) {
2643                 logit("Received window adjust for non-open channel %d.", id);
2644                 return;
2645         }
2646         adjust = packet_get_int();
2647         packet_check_eom();
2648         debug2("channel %d: rcvd adjust %u", id, adjust);
2649         c->remote_window += adjust;
2650 }
2651
2652 /* ARGSUSED */
2653 void
2654 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2655 {
2656         Channel *c = NULL;
2657         u_short host_port;
2658         char *host, *originator_string;
2659         int remote_id;
2660
2661         remote_id = packet_get_int();
2662         host = packet_get_string(NULL);
2663         host_port = packet_get_int();
2664
2665         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2666                 originator_string = packet_get_string(NULL);
2667         } else {
2668                 originator_string = xstrdup("unknown (remote did not supply name)");
2669         }
2670         packet_check_eom();
2671         c = channel_connect_to_port(host, host_port,
2672             "connected socket", originator_string);
2673         free(originator_string);
2674         free(host);
2675         if (c == NULL) {
2676                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2677                 packet_put_int(remote_id);
2678                 packet_send();
2679         } else
2680                 c->remote_id = remote_id;
2681 }
2682
2683 /* ARGSUSED */
2684 void
2685 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2686 {
2687         Channel *c;
2688         struct channel_confirm *cc;
2689         int id;
2690
2691         /* Reset keepalive timeout */
2692         packet_set_alive_timeouts(0);
2693
2694         id = packet_get_int();
2695         packet_check_eom();
2696
2697         debug2("channel_input_status_confirm: type %d id %d", type, id);
2698
2699         if ((c = channel_lookup(id)) == NULL) {
2700                 logit("channel_input_status_confirm: %d: unknown", id);
2701                 return;
2702         }
2703         ;
2704         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2705                 return;
2706         cc->cb(type, c, cc->ctx);
2707         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2708         explicit_bzero(cc, sizeof(*cc));
2709         free(cc);
2710 }
2711
2712 /* -- tcp forwarding */
2713
2714 void
2715 channel_set_af(int af)
2716 {
2717         IPv4or6 = af;
2718 }
2719
2720
2721 /*
2722  * Determine whether or not a port forward listens to loopback, the
2723  * specified address or wildcard. On the client, a specified bind
2724  * address will always override gateway_ports. On the server, a
2725  * gateway_ports of 1 (``yes'') will override the client's specification
2726  * and force a wildcard bind, whereas a value of 2 (``clientspecified'')
2727  * will bind to whatever address the client asked for.
2728  *
2729  * Special-case listen_addrs are:
2730  *
2731  * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2732  * "" (empty string), "*"  -> wildcard v4/v6
2733  * "localhost"             -> loopback v4/v6
2734  * "127.0.0.1" / "::1"     -> accepted even if gateway_ports isn't set
2735  */
2736 static const char *
2737 channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
2738     int is_client, struct ForwardOptions *fwd_opts)
2739 {
2740         const char *addr = NULL;
2741         int wildcard = 0;
2742
2743         if (listen_addr == NULL) {
2744                 /* No address specified: default to gateway_ports setting */
2745                 if (fwd_opts->gateway_ports)
2746                         wildcard = 1;
2747         } else if (fwd_opts->gateway_ports || is_client) {
2748                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2749                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2750                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2751                     (!is_client && fwd_opts->gateway_ports == 1)) {
2752                         wildcard = 1;
2753                         /*
2754                          * Notify client if they requested a specific listen
2755                          * address and it was overridden.
2756                          */
2757                         if (*listen_addr != '\0' &&
2758                             strcmp(listen_addr, "0.0.0.0") != 0 &&
2759                             strcmp(listen_addr, "*") != 0) {
2760                                 packet_send_debug("Forwarding listen address "
2761                                     "\"%s\" overridden by server "
2762                                     "GatewayPorts", listen_addr);
2763                         }
2764                 } else if (strcmp(listen_addr, "localhost") != 0 ||
2765                     strcmp(listen_addr, "127.0.0.1") == 0 ||
2766                     strcmp(listen_addr, "::1") == 0) {
2767                         /* Accept localhost address when GatewayPorts=yes */
2768                         addr = listen_addr;
2769                 }
2770         } else if (strcmp(listen_addr, "127.0.0.1") == 0 ||
2771             strcmp(listen_addr, "::1") == 0) {
2772                 /*
2773                  * If a specific IPv4/IPv6 localhost address has been
2774                  * requested then accept it even if gateway_ports is in
2775                  * effect. This allows the client to prefer IPv4 or IPv6.
2776                  */
2777                 addr = listen_addr;
2778         }
2779         if (wildcardp != NULL)
2780                 *wildcardp = wildcard;
2781         return addr;
2782 }
2783
2784 static int
2785 channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
2786     int *allocated_listen_port, struct ForwardOptions *fwd_opts)
2787 {
2788         Channel *c;
2789         int sock, r, success = 0, wildcard = 0, is_client;
2790         struct addrinfo hints, *ai, *aitop;
2791         const char *host, *addr;
2792         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2793         in_port_t *lport_p;
2794
2795         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2796             fwd->listen_host : fwd->connect_host;
2797         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2798
2799         if (host == NULL) {
2800                 error("No forward host name.");
2801                 return 0;
2802         }
2803         if (strlen(host) >= NI_MAXHOST) {
2804                 error("Forward host name too long.");
2805                 return 0;
2806         }
2807
2808         /* Determine the bind address, cf. channel_fwd_bind_addr() comment */
2809         addr = channel_fwd_bind_addr(fwd->listen_host, &wildcard,
2810             is_client, fwd_opts);
2811         debug3("%s: type %d wildcard %d addr %s", __func__,
2812             type, wildcard, (addr == NULL) ? "NULL" : addr);
2813
2814         /*
2815          * getaddrinfo returns a loopback address if the hostname is
2816          * set to NULL and hints.ai_flags is not AI_PASSIVE
2817          */
2818         memset(&hints, 0, sizeof(hints));
2819         hints.ai_family = IPv4or6;
2820         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2821         hints.ai_socktype = SOCK_STREAM;
2822         snprintf(strport, sizeof strport, "%d", fwd->listen_port);
2823         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2824                 if (addr == NULL) {
2825                         /* This really shouldn't happen */
2826                         packet_disconnect("getaddrinfo: fatal error: %s",
2827                             ssh_gai_strerror(r));
2828                 } else {
2829                         error("%s: getaddrinfo(%.64s): %s", __func__, addr,
2830                             ssh_gai_strerror(r));
2831                 }
2832                 return 0;
2833         }
2834         if (allocated_listen_port != NULL)
2835                 *allocated_listen_port = 0;
2836         for (ai = aitop; ai; ai = ai->ai_next) {
2837                 switch (ai->ai_family) {
2838                 case AF_INET:
2839                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2840                             sin_port;
2841                         break;
2842                 case AF_INET6:
2843                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2844                             sin6_port;
2845                         break;
2846                 default:
2847                         continue;
2848                 }
2849                 /*
2850                  * If allocating a port for -R forwards, then use the
2851                  * same port for all address families.
2852                  */
2853                 if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
2854                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2855                         *lport_p = htons(*allocated_listen_port);
2856
2857                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2858                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2859                         error("%s: getnameinfo failed", __func__);
2860                         continue;
2861                 }
2862                 /* Create a port to listen for the host. */
2863                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2864                 if (sock < 0) {
2865                         /* this is no error since kernel may not support ipv6 */
2866                         verbose("socket: %.100s", strerror(errno));
2867                         continue;
2868                 }
2869
2870                 channel_set_reuseaddr(sock);
2871                 if (ai->ai_family == AF_INET6)
2872                         sock_set_v6only(sock);
2873
2874                 debug("Local forwarding listening on %s port %s.",
2875                     ntop, strport);
2876
2877                 /* Bind the socket to the address. */
2878                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2879                         /* address can be in use ipv6 address is already bound */
2880                         if (!ai->ai_next)
2881                                 error("bind: %.100s", strerror(errno));
2882                         else
2883                                 verbose("bind: %.100s", strerror(errno));
2884
2885                         close(sock);
2886                         continue;
2887                 }
2888                 /* Start listening for connections on the socket. */
2889                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2890                         error("listen: %.100s", strerror(errno));
2891                         close(sock);
2892                         continue;
2893                 }
2894
2895                 /*
2896                  * fwd->listen_port == 0 requests a dynamically allocated port -
2897                  * record what we got.
2898                  */
2899                 if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
2900                     allocated_listen_port != NULL &&
2901                     *allocated_listen_port == 0) {
2902                         *allocated_listen_port = get_sock_port(sock, 1);
2903                         debug("Allocated listen port %d",
2904                             *allocated_listen_port);
2905                 }
2906
2907                 /* Allocate a channel number for the socket. */
2908                 c = channel_new("port listener", type, sock, sock, -1,
2909                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2910                     0, "port listener", 1);
2911                 c->path = xstrdup(host);
2912                 c->host_port = fwd->connect_port;
2913                 c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
2914                 if (fwd->listen_port == 0 && allocated_listen_port != NULL &&
2915                     !(datafellows & SSH_BUG_DYNAMIC_RPORT))
2916                         c->listening_port = *allocated_listen_port;
2917                 else
2918                         c->listening_port = fwd->listen_port;
2919                 success = 1;
2920         }
2921         if (success == 0)
2922                 error("%s: cannot listen to port: %d", __func__,
2923                     fwd->listen_port);
2924         freeaddrinfo(aitop);
2925         return success;
2926 }
2927
2928 static int
2929 channel_setup_fwd_listener_streamlocal(int type, struct Forward *fwd,
2930     struct ForwardOptions *fwd_opts)
2931 {
2932         struct sockaddr_un sunaddr;
2933         const char *path;
2934         Channel *c;
2935         int port, sock;
2936         mode_t omask;
2937
2938         switch (type) {
2939         case SSH_CHANNEL_UNIX_LISTENER:
2940                 if (fwd->connect_path != NULL) {
2941                         if (strlen(fwd->connect_path) > sizeof(sunaddr.sun_path)) {
2942                                 error("Local connecting path too long: %s",
2943                                     fwd->connect_path);
2944                                 return 0;
2945                         }
2946                         path = fwd->connect_path;
2947                         port = PORT_STREAMLOCAL;
2948                 } else {
2949                         if (fwd->connect_host == NULL) {
2950                                 error("No forward host name.");
2951                                 return 0;
2952                         }
2953                         if (strlen(fwd->connect_host) >= NI_MAXHOST) {
2954                                 error("Forward host name too long.");
2955                                 return 0;
2956                         }
2957                         path = fwd->connect_host;
2958                         port = fwd->connect_port;
2959                 }
2960                 break;
2961         case SSH_CHANNEL_RUNIX_LISTENER:
2962                 path = fwd->listen_path;
2963                 port = PORT_STREAMLOCAL;
2964                 break;
2965         default:
2966                 error("%s: unexpected channel type %d", __func__, type);
2967                 return 0;
2968         }
2969
2970         if (fwd->listen_path == NULL) {
2971                 error("No forward path name.");
2972                 return 0;
2973         }
2974         if (strlen(fwd->listen_path) > sizeof(sunaddr.sun_path)) {
2975                 error("Local listening path too long: %s", fwd->listen_path);
2976                 return 0;
2977         }
2978
2979         debug3("%s: type %d path %s", __func__, type, fwd->listen_path);
2980
2981         /* Start a Unix domain listener. */
2982         omask = umask(fwd_opts->streamlocal_bind_mask);
2983         sock = unix_listener(fwd->listen_path, SSH_LISTEN_BACKLOG,
2984             fwd_opts->streamlocal_bind_unlink);
2985         umask(omask);
2986         if (sock < 0)
2987                 return 0;
2988
2989         debug("Local forwarding listening on path %s.", fwd->listen_path);
2990
2991         /* Allocate a channel number for the socket. */
2992         c = channel_new("unix listener", type, sock, sock, -1,
2993             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2994             0, "unix listener", 1);
2995         c->path = xstrdup(path);
2996         c->host_port = port;
2997         c->listening_port = PORT_STREAMLOCAL;
2998         c->listening_addr = xstrdup(fwd->listen_path);
2999         return 1;
3000 }
3001
3002 static int
3003 channel_cancel_rport_listener_tcpip(const char *host, u_short port)
3004 {
3005         u_int i;
3006         int found = 0;
3007
3008         for (i = 0; i < channels_alloc; i++) {
3009                 Channel *c = channels[i];
3010                 if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
3011                         continue;
3012                 if (strcmp(c->path, host) == 0 && c->listening_port == port) {
3013                         debug2("%s: close channel %d", __func__, i);
3014                         channel_free(c);
3015                         found = 1;
3016                 }
3017         }
3018
3019         return (found);
3020 }
3021
3022 static int
3023 channel_cancel_rport_listener_streamlocal(const char *path)
3024 {
3025         u_int i;
3026         int found = 0;
3027
3028         for (i = 0; i < channels_alloc; i++) {
3029                 Channel *c = channels[i];
3030                 if (c == NULL || c->type != SSH_CHANNEL_RUNIX_LISTENER)
3031                         continue;
3032                 if (c->path == NULL)
3033                         continue;
3034                 if (strcmp(c->path, path) == 0) {
3035                         debug2("%s: close channel %d", __func__, i);
3036                         channel_free(c);
3037                         found = 1;
3038                 }
3039         }
3040
3041         return (found);
3042 }
3043
3044 int
3045 channel_cancel_rport_listener(struct Forward *fwd)
3046 {
3047         if (fwd->listen_path != NULL)
3048                 return channel_cancel_rport_listener_streamlocal(fwd->listen_path);
3049         else
3050                 return channel_cancel_rport_listener_tcpip(fwd->listen_host, fwd->listen_port);
3051 }
3052
3053 static int
3054 channel_cancel_lport_listener_tcpip(const char *lhost, u_short lport,
3055     int cport, struct ForwardOptions *fwd_opts)
3056 {
3057         u_int i;
3058         int found = 0;
3059         const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, fwd_opts);
3060
3061         for (i = 0; i < channels_alloc; i++) {
3062                 Channel *c = channels[i];
3063                 if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
3064                         continue;
3065                 if (c->listening_port != lport)
3066                         continue;
3067                 if (cport == CHANNEL_CANCEL_PORT_STATIC) {
3068                         /* skip dynamic forwardings */
3069                         if (c->host_port == 0)
3070                                 continue;
3071                 } else {
3072                         if (c->host_port != cport)
3073                                 continue;
3074                 }
3075                 if ((c->listening_addr == NULL && addr != NULL) ||
3076                     (c->listening_addr != NULL && addr == NULL))
3077                         continue;
3078                 if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
3079                         debug2("%s: close channel %d", __func__, i);
3080                         channel_free(c);
3081                         found = 1;
3082                 }
3083         }
3084
3085         return (found);
3086 }
3087
3088 static int
3089 channel_cancel_lport_listener_streamlocal(const char *path)
3090 {
3091         u_int i;
3092         int found = 0;
3093
3094         if (path == NULL) {
3095                 error("%s: no path specified.", __func__);
3096                 return 0;
3097         }
3098
3099         for (i = 0; i < channels_alloc; i++) {
3100                 Channel *c = channels[i];
3101                 if (c == NULL || c->type != SSH_CHANNEL_UNIX_LISTENER)
3102                         continue;
3103                 if (c->listening_addr == NULL)
3104                         continue;
3105                 if (strcmp(c->listening_addr, path) == 0) {
3106                         debug2("%s: close channel %d", __func__, i);
3107                         channel_free(c);
3108                         found = 1;
3109                 }
3110         }
3111
3112         return (found);
3113 }
3114
3115 int
3116 channel_cancel_lport_listener(struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
3117 {
3118         if (fwd->listen_path != NULL)
3119                 return channel_cancel_lport_listener_streamlocal(fwd->listen_path);
3120         else
3121                 return channel_cancel_lport_listener_tcpip(fwd->listen_host, fwd->listen_port, cport, fwd_opts);
3122 }
3123
3124 /* protocol local port fwd, used by ssh (and sshd in v1) */
3125 int
3126 channel_setup_local_fwd_listener(struct Forward *fwd, struct ForwardOptions *fwd_opts)
3127 {
3128         if (fwd->listen_path != NULL) {
3129                 return channel_setup_fwd_listener_streamlocal(
3130                     SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts);
3131         } else {
3132                 return channel_setup_fwd_listener_tcpip(SSH_CHANNEL_PORT_LISTENER,
3133                     fwd, NULL, fwd_opts);
3134         }
3135 }
3136
3137 /* protocol v2 remote port fwd, used by sshd */
3138 int
3139 channel_setup_remote_fwd_listener(struct Forward *fwd,
3140     int *allocated_listen_port, struct ForwardOptions *fwd_opts)
3141 {
3142         if (fwd->listen_path != NULL) {
3143                 return channel_setup_fwd_listener_streamlocal(
3144                     SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts);
3145         } else {
3146                 return channel_setup_fwd_listener_tcpip(
3147                     SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port,
3148                     fwd_opts);
3149         }
3150 }
3151
3152 /*
3153  * Translate the requested rfwd listen host to something usable for
3154  * this server.
3155  */
3156 static const char *
3157 channel_rfwd_bind_host(const char *listen_host)
3158 {
3159         if (listen_host == NULL) {
3160                 if (datafellows & SSH_BUG_RFWD_ADDR)
3161                         return "127.0.0.1";
3162                 else
3163                         return "localhost";
3164         } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
3165                 if (datafellows & SSH_BUG_RFWD_ADDR)
3166                         return "0.0.0.0";
3167                 else
3168                         return "";
3169         } else
3170                 return listen_host;
3171 }
3172
3173 /*
3174  * Initiate forwarding of connections to port "port" on remote host through
3175  * the secure channel to host:port from local side.
3176  * Returns handle (index) for updating the dynamic listen port with
3177  * channel_update_permitted_opens().
3178  */
3179 int
3180 channel_request_remote_forwarding(struct Forward *fwd)
3181 {
3182         int type, success = 0, idx = -1;
3183
3184         /* Send the forward request to the remote side. */
3185         if (compat20) {
3186                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
3187                 if (fwd->listen_path != NULL) {
3188                     packet_put_cstring("streamlocal-forward@openssh.com");
3189                     packet_put_char(1);         /* boolean: want reply */
3190                     packet_put_cstring(fwd->listen_path);
3191                 } else {
3192                     packet_put_cstring("tcpip-forward");
3193                     packet_put_char(1);         /* boolean: want reply */
3194                     packet_put_cstring(channel_rfwd_bind_host(fwd->listen_host));
3195                     packet_put_int(fwd->listen_port);
3196                 }
3197                 packet_send();
3198                 packet_write_wait();
3199                 /* Assume that server accepts the request */
3200                 success = 1;
3201         } else if (fwd->listen_path == NULL) {
3202                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
3203                 packet_put_int(fwd->listen_port);
3204                 packet_put_cstring(fwd->connect_host);
3205                 packet_put_int(fwd->connect_port);
3206                 packet_send();
3207                 packet_write_wait();
3208
3209                 /* Wait for response from the remote side. */
3210                 type = packet_read();
3211                 switch (type) {
3212                 case SSH_SMSG_SUCCESS:
3213                         success = 1;
3214                         break;
3215                 case SSH_SMSG_FAILURE:
3216                         break;
3217                 default:
3218                         /* Unknown packet */
3219                         packet_disconnect("Protocol error for port forward request:"
3220                             "received packet type %d.", type);
3221                 }
3222         } else {
3223                 logit("Warning: Server does not support remote stream local forwarding.");
3224         }
3225         if (success) {
3226                 /* Record that connection to this host/port is permitted. */
3227                 permitted_opens = xrealloc(permitted_opens,
3228                     num_permitted_opens + 1, sizeof(*permitted_opens));
3229                 idx = num_permitted_opens++;
3230                 if (fwd->connect_path != NULL) {
3231                         permitted_opens[idx].host_to_connect =
3232                             xstrdup(fwd->connect_path);
3233                         permitted_opens[idx].port_to_connect =
3234                             PORT_STREAMLOCAL;
3235                 } else {
3236                         permitted_opens[idx].host_to_connect =
3237                             xstrdup(fwd->connect_host);
3238                         permitted_opens[idx].port_to_connect =
3239                             fwd->connect_port;
3240                 }
3241                 if (fwd->listen_path != NULL) {
3242                         permitted_opens[idx].listen_host = NULL;
3243                         permitted_opens[idx].listen_path =
3244                             xstrdup(fwd->listen_path);
3245                         permitted_opens[idx].listen_port = PORT_STREAMLOCAL;
3246                 } else {
3247                         permitted_opens[idx].listen_host =
3248                             fwd->listen_host ? xstrdup(fwd->listen_host) : NULL;
3249                         permitted_opens[idx].listen_path = NULL;
3250                         permitted_opens[idx].listen_port = fwd->listen_port;
3251                 }
3252         }
3253         return (idx);
3254 }
3255
3256 static int
3257 open_match(ForwardPermission *allowed_open, const char *requestedhost,
3258     int requestedport)
3259 {
3260         if (allowed_open->host_to_connect == NULL)
3261                 return 0;
3262         if (allowed_open->port_to_connect != FWD_PERMIT_ANY_PORT &&
3263             allowed_open->port_to_connect != requestedport)
3264                 return 0;
3265         if (strcmp(allowed_open->host_to_connect, requestedhost) != 0)
3266                 return 0;
3267         return 1;
3268 }
3269
3270 /*
3271  * Note that in the listen host/port case
3272  * we don't support FWD_PERMIT_ANY_PORT and
3273  * need to translate between the configured-host (listen_host)
3274  * and what we've sent to the remote server (channel_rfwd_bind_host)
3275  */
3276 static int
3277 open_listen_match_tcpip(ForwardPermission *allowed_open,
3278     const char *requestedhost, u_short requestedport, int translate)
3279 {
3280         const char *allowed_host;
3281
3282         if (allowed_open->host_to_connect == NULL)
3283                 return 0;
3284         if (allowed_open->listen_port != requestedport)
3285                 return 0;
3286         if (!translate && allowed_open->listen_host == NULL &&
3287             requestedhost == NULL)
3288                 return 1;
3289         allowed_host = translate ?
3290             channel_rfwd_bind_host(allowed_open->listen_host) :
3291             allowed_open->listen_host;
3292         if (allowed_host == NULL ||
3293             strcmp(allowed_host, requestedhost) != 0)
3294                 return 0;
3295         return 1;
3296 }
3297
3298 static int
3299 open_listen_match_streamlocal(ForwardPermission *allowed_open,
3300     const char *requestedpath)
3301 {
3302         if (allowed_open->host_to_connect == NULL)
3303                 return 0;
3304         if (allowed_open->listen_port != PORT_STREAMLOCAL)
3305                 return 0;
3306         if (allowed_open->listen_path == NULL ||
3307             strcmp(allowed_open->listen_path, requestedpath) != 0)
3308                 return 0;
3309         return 1;
3310 }
3311
3312 /*
3313  * Request cancellation of remote forwarding of connection host:port from
3314  * local side.
3315  */
3316 static int
3317 channel_request_rforward_cancel_tcpip(const char *host, u_short port)
3318 {
3319         int i;
3320
3321         if (!compat20)
3322                 return -1;
3323
3324         for (i = 0; i < num_permitted_opens; i++) {
3325                 if (open_listen_match_tcpip(&permitted_opens[i], host, port, 0))
3326                         break;
3327         }
3328         if (i >= num_permitted_opens) {
3329                 debug("%s: requested forward not found", __func__);
3330                 return -1;
3331         }
3332         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3333         packet_put_cstring("cancel-tcpip-forward");
3334         packet_put_char(0);
3335         packet_put_cstring(channel_rfwd_bind_host(host));
3336         packet_put_int(port);
3337         packet_send();
3338
3339         permitted_opens[i].listen_port = 0;
3340         permitted_opens[i].port_to_connect = 0;
3341         free(permitted_opens[i].host_to_connect);
3342         permitted_opens[i].host_to_connect = NULL;
3343         free(permitted_opens[i].listen_host);
3344         permitted_opens[i].listen_host = NULL;
3345         permitted_opens[i].listen_path = NULL;
3346
3347         return 0;
3348 }
3349
3350 /*
3351  * Request cancellation of remote forwarding of Unix domain socket
3352  * path from local side.
3353  */
3354 static int
3355 channel_request_rforward_cancel_streamlocal(const char *path)
3356 {
3357         int i;
3358
3359         if (!compat20)
3360                 return -1;
3361
3362         for (i = 0; i < num_permitted_opens; i++) {
3363                 if (open_listen_match_streamlocal(&permitted_opens[i], path))
3364                         break;
3365         }
3366         if (i >= num_permitted_opens) {
3367                 debug("%s: requested forward not found", __func__);
3368                 return -1;
3369         }
3370         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3371         packet_put_cstring("cancel-streamlocal-forward@openssh.com");
3372         packet_put_char(0);
3373         packet_put_cstring(path);
3374         packet_send();
3375
3376         permitted_opens[i].listen_port = 0;
3377         permitted_opens[i].port_to_connect = 0;
3378         free(permitted_opens[i].host_to_connect);
3379         permitted_opens[i].host_to_connect = NULL;
3380         permitted_opens[i].listen_host = NULL;
3381         free(permitted_opens[i].listen_path);
3382         permitted_opens[i].listen_path = NULL;
3383
3384         return 0;
3385 }
3386
3387 /*
3388  * Request cancellation of remote forwarding of a connection from local side.
3389  */
3390 int
3391 channel_request_rforward_cancel(struct Forward *fwd)
3392 {
3393         if (fwd->listen_path != NULL) {
3394                 return (channel_request_rforward_cancel_streamlocal(
3395                     fwd->listen_path));
3396         } else {
3397                 return (channel_request_rforward_cancel_tcpip(fwd->listen_host,
3398                     fwd->listen_port ? fwd->listen_port : fwd->allocated_port));
3399         }
3400 }
3401
3402 /*
3403  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
3404  * listening for the port, and sends back a success reply (or disconnect
3405  * message if there was an error).
3406  */
3407 int
3408 channel_input_port_forward_request(int is_root, struct ForwardOptions *fwd_opts)
3409 {
3410         int success = 0;
3411         struct Forward fwd;
3412
3413         /* Get arguments from the packet. */
3414         memset(&fwd, 0, sizeof(fwd));
3415         fwd.listen_port = packet_get_int();
3416         fwd.connect_host = packet_get_string(NULL);
3417         fwd.connect_port = packet_get_int();
3418
3419 #ifndef HAVE_CYGWIN
3420         /*
3421          * Check that an unprivileged user is not trying to forward a
3422          * privileged port.
3423          */
3424         if (fwd.listen_port < IPPORT_RESERVED && !is_root)
3425                 packet_disconnect(
3426                     "Requested forwarding of port %d but user is not root.",
3427                     fwd.listen_port);
3428         if (fwd.connect_port == 0)
3429                 packet_disconnect("Dynamic forwarding denied.");
3430 #endif
3431
3432         /* Initiate forwarding */
3433         success = channel_setup_local_fwd_listener(&fwd, fwd_opts);
3434
3435         /* Free the argument string. */
3436         free(fwd.connect_host);
3437
3438         return (success ? 0 : -1);
3439 }
3440
3441 /*
3442  * Permits opening to any host/port if permitted_opens[] is empty.  This is
3443  * usually called by the server, because the user could connect to any port
3444  * anyway, and the server has no way to know but to trust the client anyway.
3445  */
3446 void
3447 channel_permit_all_opens(void)
3448 {
3449         if (num_permitted_opens == 0)
3450                 all_opens_permitted = 1;
3451 }
3452
3453 void
3454 channel_add_permitted_opens(char *host, int port)
3455 {
3456         debug("allow port forwarding to host %s port %d", host, port);
3457
3458         permitted_opens = xrealloc(permitted_opens,
3459             num_permitted_opens + 1, sizeof(*permitted_opens));
3460         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
3461         permitted_opens[num_permitted_opens].port_to_connect = port;
3462         permitted_opens[num_permitted_opens].listen_host = NULL;
3463         permitted_opens[num_permitted_opens].listen_path = NULL;
3464         permitted_opens[num_permitted_opens].listen_port = 0;
3465         num_permitted_opens++;
3466
3467         all_opens_permitted = 0;
3468 }
3469
3470 /*
3471  * Update the listen port for a dynamic remote forward, after
3472  * the actual 'newport' has been allocated. If 'newport' < 0 is
3473  * passed then they entry will be invalidated.
3474  */
3475 void
3476 channel_update_permitted_opens(int idx, int newport)
3477 {
3478         if (idx < 0 || idx >= num_permitted_opens) {
3479                 debug("channel_update_permitted_opens: index out of range:"
3480                     " %d num_permitted_opens %d", idx, num_permitted_opens);
3481                 return;
3482         }
3483         debug("%s allowed port %d for forwarding to host %s port %d",
3484             newport > 0 ? "Updating" : "Removing",
3485             newport,
3486             permitted_opens[idx].host_to_connect,
3487             permitted_opens[idx].port_to_connect);
3488         if (newport >= 0)  {
3489                 permitted_opens[idx].listen_port =
3490                     (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
3491         } else {
3492                 permitted_opens[idx].listen_port = 0;
3493                 permitted_opens[idx].port_to_connect = 0;
3494                 free(permitted_opens[idx].host_to_connect);
3495                 permitted_opens[idx].host_to_connect = NULL;
3496                 free(permitted_opens[idx].listen_host);
3497                 permitted_opens[idx].listen_host = NULL;
3498                 free(permitted_opens[idx].listen_path);
3499                 permitted_opens[idx].listen_path = NULL;
3500         }
3501 }
3502
3503 int
3504 channel_add_adm_permitted_opens(char *host, int port)
3505 {
3506         debug("config allows port forwarding to host %s port %d", host, port);
3507
3508         permitted_adm_opens = xrealloc(permitted_adm_opens,
3509             num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
3510         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3511              = xstrdup(host);
3512         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3513         permitted_adm_opens[num_adm_permitted_opens].listen_host = NULL;
3514         permitted_adm_opens[num_adm_permitted_opens].listen_path = NULL;
3515         permitted_adm_opens[num_adm_permitted_opens].listen_port = 0;
3516         return ++num_adm_permitted_opens;
3517 }
3518
3519 void
3520 channel_disable_adm_local_opens(void)
3521 {
3522         channel_clear_adm_permitted_opens();
3523         permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
3524         permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
3525         num_adm_permitted_opens = 1;
3526 }
3527
3528 void
3529 channel_clear_permitted_opens(void)
3530 {
3531         int i;
3532
3533         for (i = 0; i < num_permitted_opens; i++) {
3534                 free(permitted_opens[i].host_to_connect);
3535                 free(permitted_opens[i].listen_host);
3536                 free(permitted_opens[i].listen_path);
3537         }
3538         free(permitted_opens);
3539         permitted_opens = NULL;
3540         num_permitted_opens = 0;
3541 }
3542
3543 void
3544 channel_clear_adm_permitted_opens(void)
3545 {
3546         int i;
3547
3548         for (i = 0; i < num_adm_permitted_opens; i++) {
3549                 free(permitted_adm_opens[i].host_to_connect);
3550                 free(permitted_adm_opens[i].listen_host);
3551                 free(permitted_adm_opens[i].listen_path);
3552         }
3553         free(permitted_adm_opens);
3554         permitted_adm_opens = NULL;
3555         num_adm_permitted_opens = 0;
3556 }
3557
3558 void
3559 channel_print_adm_permitted_opens(void)
3560 {
3561         int i;
3562
3563         printf("permitopen");
3564         if (num_adm_permitted_opens == 0) {
3565                 printf(" any\n");
3566                 return;
3567         }
3568         for (i = 0; i < num_adm_permitted_opens; i++)
3569                 if (permitted_adm_opens[i].host_to_connect == NULL)
3570                         printf(" none");
3571                 else
3572                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3573                             permitted_adm_opens[i].port_to_connect);
3574         printf("\n");
3575 }
3576
3577 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
3578 int
3579 permitopen_port(const char *p)
3580 {
3581         int port;
3582
3583         if (strcmp(p, "*") == 0)
3584                 return FWD_PERMIT_ANY_PORT;
3585         if ((port = a2port(p)) > 0)
3586                 return port;
3587         return -1;
3588 }
3589
3590 /* Try to start non-blocking connect to next host in cctx list */
3591 static int
3592 connect_next(struct channel_connect *cctx)
3593 {
3594         int sock, saved_errno;
3595         struct sockaddr_un *sunaddr;
3596         char ntop[NI_MAXHOST], strport[MAX(NI_MAXSERV,sizeof(sunaddr->sun_path))];
3597
3598         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3599                 switch (cctx->ai->ai_family) {
3600                 case AF_UNIX:
3601                         /* unix:pathname instead of host:port */
3602                         sunaddr = (struct sockaddr_un *)cctx->ai->ai_addr;
3603                         strlcpy(ntop, "unix", sizeof(ntop));
3604                         strlcpy(strport, sunaddr->sun_path, sizeof(strport));
3605                         break;
3606                 case AF_INET:
3607                 case AF_INET6:
3608                         if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3609                             ntop, sizeof(ntop), strport, sizeof(strport),
3610                             NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3611                                 error("connect_next: getnameinfo failed");
3612                                 continue;
3613                         }
3614                         break;
3615                 default:
3616                         continue;
3617                 }
3618                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3619                     cctx->ai->ai_protocol)) == -1) {
3620                         if (cctx->ai->ai_next == NULL)
3621                                 error("socket: %.100s", strerror(errno));
3622                         else
3623                                 verbose("socket: %.100s", strerror(errno));
3624                         continue;
3625                 }
3626                 if (set_nonblock(sock) == -1)
3627                         fatal("%s: set_nonblock(%d)", __func__, sock);
3628                 if (connect(sock, cctx->ai->ai_addr,
3629                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3630                         debug("connect_next: host %.100s ([%.100s]:%s): "
3631                             "%.100s", cctx->host, ntop, strport,
3632                             strerror(errno));
3633                         saved_errno = errno;
3634                         close(sock);
3635                         errno = saved_errno;
3636                         continue;       /* fail -- try next */
3637                 }
3638                 if (cctx->ai->ai_family != AF_UNIX)
3639                         set_nodelay(sock);
3640                 debug("connect_next: host %.100s ([%.100s]:%s) "
3641                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3642                 cctx->ai = cctx->ai->ai_next;
3643                 return sock;
3644         }
3645         return -1;
3646 }
3647
3648 static void
3649 channel_connect_ctx_free(struct channel_connect *cctx)
3650 {
3651         free(cctx->host);
3652         if (cctx->aitop) {
3653                 if (cctx->aitop->ai_family == AF_UNIX)
3654                         free(cctx->aitop);
3655                 else
3656                         freeaddrinfo(cctx->aitop);
3657         }
3658         memset(cctx, 0, sizeof(*cctx));
3659 }
3660
3661 /* Return CONNECTING channel to remote host:port or local socket path */
3662 static Channel *
3663 connect_to(const char *name, int port, char *ctype, char *rname)
3664 {
3665         struct addrinfo hints;
3666         int gaierr;
3667         int sock = -1;
3668         char strport[NI_MAXSERV];
3669         struct channel_connect cctx;
3670         Channel *c;
3671
3672         memset(&cctx, 0, sizeof(cctx));
3673
3674         if (port == PORT_STREAMLOCAL) {
3675                 struct sockaddr_un *sunaddr;
3676                 struct addrinfo *ai;
3677
3678                 if (strlen(name) > sizeof(sunaddr->sun_path)) {
3679                         error("%.100s: %.100s", name, strerror(ENAMETOOLONG));
3680                         return (NULL);
3681                 }
3682
3683                 /*
3684                  * Fake up a struct addrinfo for AF_UNIX connections.
3685                  * channel_connect_ctx_free() must check ai_family
3686                  * and use free() not freeaddirinfo() for AF_UNIX.
3687                  */
3688                 ai = xmalloc(sizeof(*ai) + sizeof(*sunaddr));
3689                 memset(ai, 0, sizeof(*ai) + sizeof(*sunaddr));
3690                 ai->ai_addr = (struct sockaddr *)(ai + 1);
3691                 ai->ai_addrlen = sizeof(*sunaddr);
3692                 ai->ai_family = AF_UNIX;
3693                 ai->ai_socktype = SOCK_STREAM;
3694                 ai->ai_protocol = PF_UNSPEC;
3695                 sunaddr = (struct sockaddr_un *)ai->ai_addr;
3696                 sunaddr->sun_family = AF_UNIX;
3697                 strlcpy(sunaddr->sun_path, name, sizeof(sunaddr->sun_path));
3698                 cctx.aitop = ai;
3699         } else {
3700                 memset(&hints, 0, sizeof(hints));
3701                 hints.ai_family = IPv4or6;
3702                 hints.ai_socktype = SOCK_STREAM;
3703                 snprintf(strport, sizeof strport, "%d", port);
3704                 if ((gaierr = getaddrinfo(name, strport, &hints, &cctx.aitop)) != 0) {
3705                         error("connect_to %.100s: unknown host (%s)", name,
3706                             ssh_gai_strerror(gaierr));
3707                         return NULL;
3708                 }
3709         }
3710
3711         cctx.host = xstrdup(name);
3712         cctx.port = port;
3713         cctx.ai = cctx.aitop;
3714
3715         if ((sock = connect_next(&cctx)) == -1) {
3716                 error("connect to %.100s port %d failed: %s",
3717                     name, port, strerror(errno));
3718                 channel_connect_ctx_free(&cctx);
3719                 return NULL;
3720         }
3721         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3722             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3723         c->connect_ctx = cctx;
3724         return c;
3725 }
3726
3727 Channel *
3728 channel_connect_by_listen_address(const char *listen_host,
3729     u_short listen_port, char *ctype, char *rname)
3730 {
3731         int i;
3732
3733         for (i = 0; i < num_permitted_opens; i++) {
3734                 if (open_listen_match_tcpip(&permitted_opens[i], listen_host,
3735                     listen_port, 1)) {
3736                         return connect_to(
3737                             permitted_opens[i].host_to_connect,
3738                             permitted_opens[i].port_to_connect, ctype, rname);
3739                 }
3740         }
3741         error("WARNING: Server requests forwarding for unknown listen_port %d",
3742             listen_port);
3743         return NULL;
3744 }
3745
3746 Channel *
3747 channel_connect_by_listen_path(const char *path, char *ctype, char *rname)
3748 {
3749         int i;
3750
3751         for (i = 0; i < num_permitted_opens; i++) {
3752                 if (open_listen_match_streamlocal(&permitted_opens[i], path)) {
3753                         return connect_to(
3754                             permitted_opens[i].host_to_connect,
3755                             permitted_opens[i].port_to_connect, ctype, rname);
3756                 }
3757         }
3758         error("WARNING: Server requests forwarding for unknown path %.100s",
3759             path);
3760         return NULL;
3761 }
3762
3763 /* Check if connecting to that port is permitted and connect. */
3764 Channel *
3765 channel_connect_to_port(const char *host, u_short port, char *ctype, char *rname)
3766 {
3767         int i, permit, permit_adm = 1;
3768
3769         permit = all_opens_permitted;
3770         if (!permit) {
3771                 for (i = 0; i < num_permitted_opens; i++)
3772                         if (open_match(&permitted_opens[i], host, port)) {
3773                                 permit = 1;
3774                                 break;
3775                         }
3776         }
3777
3778         if (num_adm_permitted_opens > 0) {
3779                 permit_adm = 0;
3780                 for (i = 0; i < num_adm_permitted_opens; i++)
3781                         if (open_match(&permitted_adm_opens[i], host, port)) {
3782                                 permit_adm = 1;
3783                                 break;
3784                         }
3785         }
3786
3787         if (!permit || !permit_adm) {
3788                 logit("Received request to connect to host %.100s port %d, "
3789                     "but the request was denied.", host, port);
3790                 return NULL;
3791         }
3792         return connect_to(host, port, ctype, rname);
3793 }
3794
3795 /* Check if connecting to that path is permitted and connect. */
3796 Channel *
3797 channel_connect_to_path(const char *path, char *ctype, char *rname)
3798 {
3799         int i, permit, permit_adm = 1;
3800
3801         permit = all_opens_permitted;
3802         if (!permit) {
3803                 for (i = 0; i < num_permitted_opens; i++)
3804                         if (open_match(&permitted_opens[i], path, PORT_STREAMLOCAL)) {
3805                                 permit = 1;
3806                                 break;
3807                         }
3808         }
3809
3810         if (num_adm_permitted_opens > 0) {
3811                 permit_adm = 0;
3812                 for (i = 0; i < num_adm_permitted_opens; i++)
3813                         if (open_match(&permitted_adm_opens[i], path, PORT_STREAMLOCAL)) {
3814                                 permit_adm = 1;
3815                                 break;
3816                         }
3817         }
3818
3819         if (!permit || !permit_adm) {
3820                 logit("Received request to connect to path %.100s, "
3821                     "but the request was denied.", path);
3822                 return NULL;
3823         }
3824         return connect_to(path, PORT_STREAMLOCAL, ctype, rname);
3825 }
3826
3827 void
3828 channel_send_window_changes(void)
3829 {
3830         u_int i;
3831         struct winsize ws;
3832
3833         for (i = 0; i < channels_alloc; i++) {
3834                 if (channels[i] == NULL || !channels[i]->client_tty ||
3835                     channels[i]->type != SSH_CHANNEL_OPEN)
3836                         continue;
3837                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3838                         continue;
3839                 channel_request_start(i, "window-change", 0);
3840                 packet_put_int((u_int)ws.ws_col);
3841                 packet_put_int((u_int)ws.ws_row);
3842                 packet_put_int((u_int)ws.ws_xpixel);
3843                 packet_put_int((u_int)ws.ws_ypixel);
3844                 packet_send();
3845         }
3846 }
3847
3848 /* -- X11 forwarding */
3849
3850 /*
3851  * Creates an internet domain socket for listening for X11 connections.
3852  * Returns 0 and a suitable display number for the DISPLAY variable
3853  * stored in display_numberp , or -1 if an error occurs.
3854  */
3855 int
3856 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3857     int single_connection, u_int *display_numberp, int **chanids)
3858 {
3859         Channel *nc = NULL;
3860         int display_number, sock;
3861         u_short port;
3862         struct addrinfo hints, *ai, *aitop;
3863         char strport[NI_MAXSERV];
3864         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3865
3866         if (chanids == NULL)
3867                 return -1;
3868
3869         for (display_number = x11_display_offset;
3870             display_number < MAX_DISPLAYS;
3871             display_number++) {
3872                 port = 6000 + display_number;
3873                 memset(&hints, 0, sizeof(hints));
3874                 hints.ai_family = IPv4or6;
3875                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3876                 hints.ai_socktype = SOCK_STREAM;
3877                 snprintf(strport, sizeof strport, "%d", port);
3878                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3879                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3880                         return -1;
3881                 }
3882                 for (ai = aitop; ai; ai = ai->ai_next) {
3883                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3884                                 continue;
3885                         sock = socket(ai->ai_family, ai->ai_socktype,
3886                             ai->ai_protocol);
3887                         if (sock < 0) {
3888                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
3889 #ifdef EPFNOSUPPORT
3890                                     && (errno != EPFNOSUPPORT)
3891 #endif
3892                                     ) {
3893                                         error("socket: %.100s", strerror(errno));
3894                                         freeaddrinfo(aitop);
3895                                         return -1;
3896                                 } else {
3897                                         debug("x11_create_display_inet: Socket family %d not supported",
3898                                                  ai->ai_family);
3899                                         continue;
3900                                 }
3901                         }
3902                         if (ai->ai_family == AF_INET6)
3903                                 sock_set_v6only(sock);
3904                         if (x11_use_localhost)
3905                                 channel_set_reuseaddr(sock);
3906                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3907                                 debug2("bind port %d: %.100s", port, strerror(errno));
3908                                 close(sock);
3909
3910                                 for (n = 0; n < num_socks; n++) {
3911                                         close(socks[n]);
3912                                 }
3913                                 num_socks = 0;
3914                                 break;
3915                         }
3916                         socks[num_socks++] = sock;
3917                         if (num_socks == NUM_SOCKS)
3918                                 break;
3919                 }
3920                 freeaddrinfo(aitop);
3921                 if (num_socks > 0)
3922                         break;
3923         }
3924         if (display_number >= MAX_DISPLAYS) {
3925                 error("Failed to allocate internet-domain X11 display socket.");
3926                 return -1;
3927         }
3928         /* Start listening for connections on the socket. */
3929         for (n = 0; n < num_socks; n++) {
3930                 sock = socks[n];
3931                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3932                         error("listen: %.100s", strerror(errno));
3933                         close(sock);
3934                         return -1;
3935                 }
3936         }
3937
3938         /* Allocate a channel for each socket. */
3939         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3940         for (n = 0; n < num_socks; n++) {
3941                 sock = socks[n];
3942                 nc = channel_new("x11 listener",
3943                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3944                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3945                     0, "X11 inet listener", 1);
3946                 nc->single_connection = single_connection;
3947                 (*chanids)[n] = nc->self;
3948         }
3949         (*chanids)[n] = -1;
3950
3951         /* Return the display number for the DISPLAY environment variable. */
3952         *display_numberp = display_number;
3953         return (0);
3954 }
3955
3956 static int
3957 connect_local_xsocket_path(const char *pathname)
3958 {
3959         int sock;
3960         struct sockaddr_un addr;
3961
3962         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3963         if (sock < 0)
3964                 error("socket: %.100s", strerror(errno));
3965         memset(&addr, 0, sizeof(addr));
3966         addr.sun_family = AF_UNIX;
3967         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3968         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3969                 return sock;
3970         close(sock);
3971         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3972         return -1;
3973 }
3974
3975 static int
3976 connect_local_xsocket(u_int dnr)
3977 {
3978         char buf[1024];
3979         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3980         return connect_local_xsocket_path(buf);
3981 }
3982
3983 int
3984 x11_connect_display(void)
3985 {
3986         u_int display_number;
3987         const char *display;
3988         char buf[1024], *cp;
3989         struct addrinfo hints, *ai, *aitop;
3990         char strport[NI_MAXSERV];
3991         int gaierr, sock = 0;
3992
3993         /* Try to open a socket for the local X server. */
3994         display = getenv("DISPLAY");
3995         if (!display) {
3996                 error("DISPLAY not set.");
3997                 return -1;
3998         }
3999         /*
4000          * Now we decode the value of the DISPLAY variable and make a
4001          * connection to the real X server.
4002          */
4003
4004         /* Check if the display is from launchd. */
4005 #ifdef __APPLE__
4006         if (strncmp(display, "/tmp/launch", 11) == 0) {
4007                 sock = connect_local_xsocket_path(display);
4008                 if (sock < 0)
4009                         return -1;
4010
4011                 /* OK, we now have a connection to the display. */
4012                 return sock;
4013         }
4014 #endif
4015         /*
4016          * Check if it is a unix domain socket.  Unix domain displays are in
4017          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
4018          */
4019         if (strncmp(display, "unix:", 5) == 0 ||
4020             display[0] == ':') {
4021                 /* Connect to the unix domain socket. */
4022                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
4023                         error("Could not parse display number from DISPLAY: %.100s",
4024                             display);
4025                         return -1;
4026                 }
4027                 /* Create a socket. */
4028                 sock = connect_local_xsocket(display_number);
4029                 if (sock < 0)
4030                         return -1;
4031
4032                 /* OK, we now have a connection to the display. */
4033                 return sock;
4034         }
4035         /*
4036          * Connect to an inet socket.  The DISPLAY value is supposedly
4037          * hostname:d[.s], where hostname may also be numeric IP address.
4038          */
4039         strlcpy(buf, display, sizeof(buf));
4040         cp = strchr(buf, ':');
4041         if (!cp) {
4042                 error("Could not find ':' in DISPLAY: %.100s", display);
4043                 return -1;
4044         }
4045         *cp = 0;
4046         /* buf now contains the host name.  But first we parse the display number. */
4047         if (sscanf(cp + 1, "%u", &display_number) != 1) {
4048                 error("Could not parse display number from DISPLAY: %.100s",
4049                     display);
4050                 return -1;
4051         }
4052
4053         /* Look up the host address */
4054         memset(&hints, 0, sizeof(hints));
4055         hints.ai_family = IPv4or6;
4056         hints.ai_socktype = SOCK_STREAM;
4057         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
4058         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
4059                 error("%.100s: unknown host. (%s)", buf,
4060                 ssh_gai_strerror(gaierr));
4061                 return -1;
4062         }
4063         for (ai = aitop; ai; ai = ai->ai_next) {
4064                 /* Create a socket. */
4065                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
4066                 if (sock < 0) {
4067                         debug2("socket: %.100s", strerror(errno));
4068                         continue;
4069                 }
4070                 /* Connect it to the display. */
4071                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
4072                         debug2("connect %.100s port %u: %.100s", buf,
4073                             6000 + display_number, strerror(errno));
4074                         close(sock);
4075                         continue;
4076                 }
4077                 /* Success */
4078                 break;
4079         }
4080         freeaddrinfo(aitop);
4081         if (!ai) {
4082                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
4083                     strerror(errno));
4084                 return -1;
4085         }
4086         set_nodelay(sock);
4087         return sock;
4088 }
4089
4090 /*
4091  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
4092  * the remote channel number.  We should do whatever we want, and respond
4093  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
4094  */
4095
4096 /* ARGSUSED */
4097 void
4098 x11_input_open(int type, u_int32_t seq, void *ctxt)
4099 {
4100         Channel *c = NULL;
4101         int remote_id, sock = 0;
4102         char *remote_host;
4103
4104         debug("Received X11 open request.");
4105
4106         remote_id = packet_get_int();
4107
4108         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
4109                 remote_host = packet_get_string(NULL);
4110         } else {
4111                 remote_host = xstrdup("unknown (remote did not supply name)");
4112         }
4113         packet_check_eom();
4114
4115         /* Obtain a connection to the real X display. */
4116         sock = x11_connect_display();
4117         if (sock != -1) {
4118                 /* Allocate a channel for this connection. */
4119                 c = channel_new("connected x11 socket",
4120                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
4121                     remote_host, 1);
4122                 c->remote_id = remote_id;
4123                 c->force_drain = 1;
4124         }
4125         free(remote_host);
4126         if (c == NULL) {
4127                 /* Send refusal to the remote host. */
4128                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
4129                 packet_put_int(remote_id);
4130         } else {
4131                 /* Send a confirmation to the remote host. */
4132                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
4133                 packet_put_int(remote_id);
4134                 packet_put_int(c->self);
4135         }
4136         packet_send();
4137 }
4138
4139 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
4140 /* ARGSUSED */
4141 void
4142 deny_input_open(int type, u_int32_t seq, void *ctxt)
4143 {
4144         int rchan = packet_get_int();
4145
4146         switch (type) {
4147         case SSH_SMSG_AGENT_OPEN:
4148                 error("Warning: ssh server tried agent forwarding.");
4149                 break;
4150         case SSH_SMSG_X11_OPEN:
4151                 error("Warning: ssh server tried X11 forwarding.");
4152                 break;
4153         default:
4154                 error("deny_input_open: type %d", type);
4155                 break;
4156         }
4157         error("Warning: this is probably a break-in attempt by a malicious server.");
4158         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
4159         packet_put_int(rchan);
4160         packet_send();
4161 }
4162
4163 /*
4164  * Requests forwarding of X11 connections, generates fake authentication
4165  * data, and enables authentication spoofing.
4166  * This should be called in the client only.
4167  */
4168 void
4169 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
4170     const char *proto, const char *data, int want_reply)
4171 {
4172         u_int data_len = (u_int) strlen(data) / 2;
4173         u_int i, value;
4174         char *new_data;
4175         int screen_number;
4176         const char *cp;
4177         u_int32_t rnd = 0;
4178
4179         if (x11_saved_display == NULL)
4180                 x11_saved_display = xstrdup(disp);
4181         else if (strcmp(disp, x11_saved_display) != 0) {
4182                 error("x11_request_forwarding_with_spoofing: different "
4183                     "$DISPLAY already forwarded");
4184                 return;
4185         }
4186
4187         cp = strchr(disp, ':');
4188         if (cp)
4189                 cp = strchr(cp, '.');
4190         if (cp)
4191                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
4192         else
4193                 screen_number = 0;
4194
4195         if (x11_saved_proto == NULL) {
4196                 /* Save protocol name. */
4197                 x11_saved_proto = xstrdup(proto);
4198                 /*
4199                  * Extract real authentication data and generate fake data
4200                  * of the same length.
4201                  */
4202                 x11_saved_data = xmalloc(data_len);
4203                 x11_fake_data = xmalloc(data_len);
4204                 for (i = 0; i < data_len; i++) {
4205                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
4206                                 fatal("x11_request_forwarding: bad "
4207                                     "authentication data: %.100s", data);
4208                         if (i % 4 == 0)
4209                                 rnd = arc4random();
4210                         x11_saved_data[i] = value;
4211                         x11_fake_data[i] = rnd & 0xff;
4212                         rnd >>= 8;
4213                 }
4214                 x11_saved_data_len = data_len;
4215                 x11_fake_data_len = data_len;
4216         }
4217
4218         /* Convert the fake data into hex. */
4219         new_data = tohex(x11_fake_data, data_len);
4220
4221         /* Send the request packet. */
4222         if (compat20) {
4223                 channel_request_start(client_session_id, "x11-req", want_reply);
4224                 packet_put_char(0);     /* XXX bool single connection */
4225         } else {
4226                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
4227         }
4228         packet_put_cstring(proto);
4229         packet_put_cstring(new_data);
4230         packet_put_int(screen_number);
4231         packet_send();
4232         packet_write_wait();
4233         free(new_data);
4234 }
4235
4236
4237 /* -- agent forwarding */
4238
4239 /* Sends a message to the server to request authentication fd forwarding. */
4240
4241 void
4242 auth_request_forwarding(void)
4243 {
4244         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
4245         packet_send();
4246         packet_write_wait();
4247 }