channels.c

   1 /* $OpenBSD: channels.c,v 1.254 2006/07/11 20:07:25 stevesk 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/ioctl.h>
  45 #include <sys/types.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48
  49 #include <netinet/in.h>
  50 #include <arpa/inet.h>
  51
  52 #include <errno.h>
  53 #include <termios.h>
  54
  55 #include "ssh.h"
  56 #include "ssh1.h"
  57 #include "ssh2.h"
  58 #include "packet.h"
  59 #include "xmalloc.h"
  60 #include "log.h"
  61 #include "misc.h"
  62 #include "channels.h"
  63 #include "compat.h"
  64 #include "canohost.h"
  65 #include "key.h"
  66 #include "authfd.h"
  67 #include "pathnames.h"
  68 #include "bufaux.h"
  69
  70 /* -- channel core */
  71
  72 /*
  73  * Pointer to an array containing all allocated channels.  The array is
  74  * dynamically extended as needed.
  75  */
  76 static Channel **channels = NULL;
  77
  78 /*
  79  * Size of the channel array.  All slots of the array must always be
  80  * initialized (at least the type field); unused slots set to NULL
  81  */
  82 static u_int channels_alloc = 0;
  83
  84 /*
  85  * Maximum file descriptor value used in any of the channels.  This is
  86  * updated in channel_new.
  87  */
  88 static int channel_max_fd = 0;
  89
  90
  91 /* -- tcp forwarding */
  92
  93 /*
  94  * Data structure for storing which hosts are permitted for forward requests.
  95  * The local sides of any remote forwards are stored in this array to prevent
  96  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
  97  * network (which might be behind a firewall).
  98  */
  99 typedef struct {
 100         char *host_to_connect;          /* Connect to 'host'. */
 101         u_short port_to_connect;        /* Connect to 'port'. */
 102         u_short listen_port;            /* Remote side should listen port number. */
 103 } ForwardPermission;
 104
 105 /* List of all permitted host/port pairs to connect. */
 106 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 107
 108 /* Number of permitted host/port pairs in the array. */
 109 static int num_permitted_opens = 0;
 110 /*
 111  * If this is true, all opens are permitted.  This is the case on the server
 112  * on which we have to trust the client anyway, and the user could do
 113  * anything after logging in anyway.
 114  */
 115 static int all_opens_permitted = 0;
 116
 117
 118 /* -- X11 forwarding */
 119
 120 /* Maximum number of fake X11 displays to try. */
 121 #define MAX_DISPLAYS  1000
 122
 123 /* Saved X11 local (client) display. */
 124 static char *x11_saved_display = NULL;
 125
 126 /* Saved X11 authentication protocol name. */
 127 static char *x11_saved_proto = NULL;
 128
 129 /* Saved X11 authentication data.  This is the real data. */
 130 static char *x11_saved_data = NULL;
 131 static u_int x11_saved_data_len = 0;
 132
 133 /*
 134  * Fake X11 authentication data.  This is what the server will be sending us;
 135  * we should replace any occurrences of this by the real data.
 136  */
 137 static u_char *x11_fake_data = NULL;
 138 static u_int x11_fake_data_len;
 139
 140
 141 /* -- agent forwarding */
 142
 143 #define NUM_SOCKS       10
 144
 145 /* AF_UNSPEC or AF_INET or AF_INET6 */
 146 static int IPv4or6 = AF_UNSPEC;
 147
 148 /* helper */
 149 static void port_open_helper(Channel *c, char *rtype);
 150
 151 /* -- channel core */
 152
 153 Channel *
 154 channel_by_id(int id)
 155 {
 156         Channel *c;
 157
 158         if (id < 0 || (u_int)id >= channels_alloc) {
 159                 logit("channel_by_id: %d: bad id", id);
 160                 return NULL;
 161         }
 162         c = channels[id];
 163         if (c == NULL) {
 164                 logit("channel_by_id: %d: bad id: channel free", id);
 165                 return NULL;
 166         }
 167         return c;
 168 }
 169
 170 /*
 171  * Returns the channel if it is allowed to receive protocol messages.
 172  * Private channels, like listening sockets, may not receive messages.
 173  */
 174 Channel *
 175 channel_lookup(int id)
 176 {
 177         Channel *c;
 178
 179         if ((c = channel_by_id(id)) == NULL)
 180                 return (NULL);
 181
 182         switch (c->type) {
 183         case SSH_CHANNEL_X11_OPEN:
 184         case SSH_CHANNEL_LARVAL:
 185         case SSH_CHANNEL_CONNECTING:
 186         case SSH_CHANNEL_DYNAMIC:
 187         case SSH_CHANNEL_OPENING:
 188         case SSH_CHANNEL_OPEN:
 189         case SSH_CHANNEL_INPUT_DRAINING:
 190         case SSH_CHANNEL_OUTPUT_DRAINING:
 191                 return (c);
 192         }
 193         logit("Non-public channel %d, type %d.", id, c->type);
 194         return (NULL);
 195 }
 196
 197 /*
 198  * Register filedescriptors for a channel, used when allocating a channel or
 199  * when the channel consumer/producer is ready, e.g. shell exec'd
 200  */
 201 static void
 202 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 203     int extusage, int nonblock)
 204 {
 205         /* Update the maximum file descriptor value. */
 206         channel_max_fd = MAX(channel_max_fd, rfd);
 207         channel_max_fd = MAX(channel_max_fd, wfd);
 208         channel_max_fd = MAX(channel_max_fd, efd);
 209
 210         /* XXX set close-on-exec -markus */
 211
 212         c->rfd = rfd;
 213         c->wfd = wfd;
 214         c->sock = (rfd == wfd) ? rfd : -1;
 215         c->ctl_fd = -1; /* XXX: set elsewhere */
 216         c->efd = efd;
 217         c->extended_usage = extusage;
 218
 219         /* XXX ugly hack: nonblock is only set by the server */
 220         if (nonblock && isatty(c->rfd)) {
 221                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 222                 c->isatty = 1;
 223                 if (!isatty(c->wfd)) {
 224                         error("channel %d: wfd %d is not a tty?",
 225                             c->self, c->wfd);
 226                 }
 227         } else {
 228                 c->isatty = 0;
 229         }
 230         c->wfd_isatty = isatty(c->wfd);
 231
 232         /* enable nonblocking mode */
 233         if (nonblock) {
 234                 if (rfd != -1)
 235                         set_nonblock(rfd);
 236                 if (wfd != -1)
 237                         set_nonblock(wfd);
 238                 if (efd != -1)
 239                         set_nonblock(efd);
 240         }
 241 }
 242
 243 /*
 244  * Allocate a new channel object and set its type and socket. This will cause
 245  * remote_name to be freed.
 246  */
 247 Channel *
 248 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 249     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 250 {
 251         int found;
 252         u_int i;
 253         Channel *c;
 254
 255         /* Do initial allocation if this is the first call. */
 256         if (channels_alloc == 0) {
 257                 channels_alloc = 10;
 258                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 259                 for (i = 0; i < channels_alloc; i++)
 260                         channels[i] = NULL;
 261         }
 262         /* Try to find a free slot where to put the new channel. */
 263         for (found = -1, i = 0; i < channels_alloc; i++)
 264                 if (channels[i] == NULL) {
 265                         /* Found a free slot. */
 266                         found = (int)i;
 267                         break;
 268                 }
 269         if (found < 0) {
 270                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 271                 found = channels_alloc;
 272                 if (channels_alloc > 10000)
 273                         fatal("channel_new: internal error: channels_alloc %d "
 274                             "too big.", channels_alloc);
 275                 channels = xrealloc(channels, channels_alloc + 10,
 276                     sizeof(Channel *));
 277                 channels_alloc += 10;
 278                 debug2("channel: expanding %d", channels_alloc);
 279                 for (i = found; i < channels_alloc; i++)
 280                         channels[i] = NULL;
 281         }
 282         /* Initialize and return new channel. */
 283         c = channels[found] = xcalloc(1, sizeof(Channel));
 284         buffer_init(&c->input);
 285         buffer_init(&c->output);
 286         buffer_init(&c->extended);
 287         c->ostate = CHAN_OUTPUT_OPEN;
 288         c->istate = CHAN_INPUT_OPEN;
 289         c->flags = 0;
 290         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 291         c->self = found;
 292         c->type = type;
 293         c->ctype = ctype;
 294         c->local_window = window;
 295         c->local_window_max = window;
 296         c->local_consumed = 0;
 297         c->local_maxpacket = maxpack;
 298         c->remote_id = -1;
 299         c->remote_name = xstrdup(remote_name);
 300         c->remote_window = 0;
 301         c->remote_maxpacket = 0;
 302         c->force_drain = 0;
 303         c->single_connection = 0;
 304         c->detach_user = NULL;
 305         c->detach_close = 0;
 306         c->confirm = NULL;
 307         c->confirm_ctx = NULL;
 308         c->input_filter = NULL;
 309         c->output_filter = NULL;
 310         debug("channel %d: new [%s]", found, remote_name);
 311         return c;
 312 }
 313
 314 static int
 315 channel_find_maxfd(void)
 316 {
 317         u_int i;
 318         int max = 0;
 319         Channel *c;
 320
 321         for (i = 0; i < channels_alloc; i++) {
 322                 c = channels[i];
 323                 if (c != NULL) {
 324                         max = MAX(max, c->rfd);
 325                         max = MAX(max, c->wfd);
 326                         max = MAX(max, c->efd);
 327                 }
 328         }
 329         return max;
 330 }
 331
 332 int
 333 channel_close_fd(int *fdp)
 334 {
 335         int ret = 0, fd = *fdp;
 336
 337         if (fd != -1) {
 338                 ret = close(fd);
 339                 *fdp = -1;
 340                 if (fd == channel_max_fd)
 341                         channel_max_fd = channel_find_maxfd();
 342         }
 343         return ret;
 344 }
 345
 346 /* Close all channel fd/socket. */
 347 static void
 348 channel_close_fds(Channel *c)
 349 {
 350         debug3("channel %d: close_fds r %d w %d e %d c %d",
 351             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 352
 353         channel_close_fd(&c->sock);
 354         channel_close_fd(&c->ctl_fd);
 355         channel_close_fd(&c->rfd);
 356         channel_close_fd(&c->wfd);
 357         channel_close_fd(&c->efd);
 358 }
 359
 360 /* Free the channel and close its fd/socket. */
 361 void
 362 channel_free(Channel *c)
 363 {
 364         char *s;
 365         u_int i, n;
 366
 367         for (n = 0, i = 0; i < channels_alloc; i++)
 368                 if (channels[i])
 369                         n++;
 370         debug("channel %d: free: %s, nchannels %u", c->self,
 371             c->remote_name ? c->remote_name : "???", n);
 372
 373         s = channel_open_message();
 374         debug3("channel %d: status: %s", c->self, s);
 375         xfree(s);
 376
 377         if (c->sock != -1)
 378                 shutdown(c->sock, SHUT_RDWR);
 379         if (c->ctl_fd != -1)
 380                 shutdown(c->ctl_fd, SHUT_RDWR);
 381         channel_close_fds(c);
 382         buffer_free(&c->input);
 383         buffer_free(&c->output);
 384         buffer_free(&c->extended);
 385         if (c->remote_name) {
 386                 xfree(c->remote_name);
 387                 c->remote_name = NULL;
 388         }
 389         channels[c->self] = NULL;
 390         xfree(c);
 391 }
 392
 393 void
 394 channel_free_all(void)
 395 {
 396         u_int i;
 397
 398         for (i = 0; i < channels_alloc; i++)
 399                 if (channels[i] != NULL)
 400                         channel_free(channels[i]);
 401 }
 402
 403 /*
 404  * Closes the sockets/fds of all channels.  This is used to close extra file
 405  * descriptors after a fork.
 406  */
 407 void
 408 channel_close_all(void)
 409 {
 410         u_int i;
 411
 412         for (i = 0; i < channels_alloc; i++)
 413                 if (channels[i] != NULL)
 414                         channel_close_fds(channels[i]);
 415 }
 416
 417 /*
 418  * Stop listening to channels.
 419  */
 420 void
 421 channel_stop_listening(void)
 422 {
 423         u_int i;
 424         Channel *c;
 425
 426         for (i = 0; i < channels_alloc; i++) {
 427                 c = channels[i];
 428                 if (c != NULL) {
 429                         switch (c->type) {
 430                         case SSH_CHANNEL_AUTH_SOCKET:
 431                         case SSH_CHANNEL_PORT_LISTENER:
 432                         case SSH_CHANNEL_RPORT_LISTENER:
 433                         case SSH_CHANNEL_X11_LISTENER:
 434                                 channel_close_fd(&c->sock);
 435                                 channel_free(c);
 436                                 break;
 437                         }
 438                 }
 439         }
 440 }
 441
 442 /*
 443  * Returns true if no channel has too much buffered data, and false if one or
 444  * more channel is overfull.
 445  */
 446 int
 447 channel_not_very_much_buffered_data(void)
 448 {
 449         u_int i;
 450         Channel *c;
 451
 452         for (i = 0; i < channels_alloc; i++) {
 453                 c = channels[i];
 454                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 455 #if 0
 456                         if (!compat20 &&
 457                             buffer_len(&c->input) > packet_get_maxsize()) {
 458                                 debug2("channel %d: big input buffer %d",
 459                                     c->self, buffer_len(&c->input));
 460                                 return 0;
 461                         }
 462 #endif
 463                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 464                                 debug2("channel %d: big output buffer %u > %u",
 465                                     c->self, buffer_len(&c->output),
 466                                     packet_get_maxsize());
 467                                 return 0;
 468                         }
 469                 }
 470         }
 471         return 1;
 472 }
 473
 474 /* Returns true if any channel is still open. */
 475 int
 476 channel_still_open(void)
 477 {
 478         u_int i;
 479         Channel *c;
 480
 481         for (i = 0; i < channels_alloc; i++) {
 482                 c = channels[i];
 483                 if (c == NULL)
 484                         continue;
 485                 switch (c->type) {
 486                 case SSH_CHANNEL_X11_LISTENER:
 487                 case SSH_CHANNEL_PORT_LISTENER:
 488                 case SSH_CHANNEL_RPORT_LISTENER:
 489                 case SSH_CHANNEL_CLOSED:
 490                 case SSH_CHANNEL_AUTH_SOCKET:
 491                 case SSH_CHANNEL_DYNAMIC:
 492                 case SSH_CHANNEL_CONNECTING:
 493                 case SSH_CHANNEL_ZOMBIE:
 494                         continue;
 495                 case SSH_CHANNEL_LARVAL:
 496                         if (!compat20)
 497                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 498                         continue;
 499                 case SSH_CHANNEL_OPENING:
 500                 case SSH_CHANNEL_OPEN:
 501                 case SSH_CHANNEL_X11_OPEN:
 502                         return 1;
 503                 case SSH_CHANNEL_INPUT_DRAINING:
 504                 case SSH_CHANNEL_OUTPUT_DRAINING:
 505                         if (!compat13)
 506                                 fatal("cannot happen: OUT_DRAIN");
 507                         return 1;
 508                 default:
 509                         fatal("channel_still_open: bad channel type %d", c->type);
 510                         /* NOTREACHED */
 511                 }
 512         }
 513         return 0;
 514 }
 515
 516 /* Returns the id of an open channel suitable for keepaliving */
 517 int
 518 channel_find_open(void)
 519 {
 520         u_int i;
 521         Channel *c;
 522
 523         for (i = 0; i < channels_alloc; i++) {
 524                 c = channels[i];
 525                 if (c == NULL || c->remote_id < 0)
 526                         continue;
 527                 switch (c->type) {
 528                 case SSH_CHANNEL_CLOSED:
 529                 case SSH_CHANNEL_DYNAMIC:
 530                 case SSH_CHANNEL_X11_LISTENER:
 531                 case SSH_CHANNEL_PORT_LISTENER:
 532                 case SSH_CHANNEL_RPORT_LISTENER:
 533                 case SSH_CHANNEL_OPENING:
 534                 case SSH_CHANNEL_CONNECTING:
 535                 case SSH_CHANNEL_ZOMBIE:
 536                         continue;
 537                 case SSH_CHANNEL_LARVAL:
 538                 case SSH_CHANNEL_AUTH_SOCKET:
 539                 case SSH_CHANNEL_OPEN:
 540                 case SSH_CHANNEL_X11_OPEN:
 541                         return i;
 542                 case SSH_CHANNEL_INPUT_DRAINING:
 543                 case SSH_CHANNEL_OUTPUT_DRAINING:
 544                         if (!compat13)
 545                                 fatal("cannot happen: OUT_DRAIN");
 546                         return i;
 547                 default:
 548                         fatal("channel_find_open: bad channel type %d", c->type);
 549                         /* NOTREACHED */
 550                 }
 551         }
 552         return -1;
 553 }
 554
 555
 556 /*
 557  * Returns a message describing the currently open forwarded connections,
 558  * suitable for sending to the client.  The message contains crlf pairs for
 559  * newlines.
 560  */
 561 char *
 562 channel_open_message(void)
 563 {
 564         Buffer buffer;
 565         Channel *c;
 566         char buf[1024], *cp;
 567         u_int i;
 568
 569         buffer_init(&buffer);
 570         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 571         buffer_append(&buffer, buf, strlen(buf));
 572         for (i = 0; i < channels_alloc; i++) {
 573                 c = channels[i];
 574                 if (c == NULL)
 575                         continue;
 576                 switch (c->type) {
 577                 case SSH_CHANNEL_X11_LISTENER:
 578                 case SSH_CHANNEL_PORT_LISTENER:
 579                 case SSH_CHANNEL_RPORT_LISTENER:
 580                 case SSH_CHANNEL_CLOSED:
 581                 case SSH_CHANNEL_AUTH_SOCKET:
 582                 case SSH_CHANNEL_ZOMBIE:
 583                         continue;
 584                 case SSH_CHANNEL_LARVAL:
 585                 case SSH_CHANNEL_OPENING:
 586                 case SSH_CHANNEL_CONNECTING:
 587                 case SSH_CHANNEL_DYNAMIC:
 588                 case SSH_CHANNEL_OPEN:
 589                 case SSH_CHANNEL_X11_OPEN:
 590                 case SSH_CHANNEL_INPUT_DRAINING:
 591                 case SSH_CHANNEL_OUTPUT_DRAINING:
 592                         snprintf(buf, sizeof buf,
 593                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 594                             c->self, c->remote_name,
 595                             c->type, c->remote_id,
 596                             c->istate, buffer_len(&c->input),
 597                             c->ostate, buffer_len(&c->output),
 598                             c->rfd, c->wfd, c->ctl_fd);
 599                         buffer_append(&buffer, buf, strlen(buf));
 600                         continue;
 601                 default:
 602                         fatal("channel_open_message: bad channel type %d", c->type);
 603                         /* NOTREACHED */
 604                 }
 605         }
 606         buffer_append(&buffer, "\0", 1);
 607         cp = xstrdup(buffer_ptr(&buffer));
 608         buffer_free(&buffer);
 609         return cp;
 610 }
 611
 612 void
 613 channel_send_open(int id)
 614 {
 615         Channel *c = channel_lookup(id);
 616
 617         if (c == NULL) {
 618                 logit("channel_send_open: %d: bad id", id);
 619                 return;
 620         }
 621         debug2("channel %d: send open", id);
 622         packet_start(SSH2_MSG_CHANNEL_OPEN);
 623         packet_put_cstring(c->ctype);
 624         packet_put_int(c->self);
 625         packet_put_int(c->local_window);
 626         packet_put_int(c->local_maxpacket);
 627         packet_send();
 628 }
 629
 630 void
 631 channel_request_start(int id, char *service, int wantconfirm)
 632 {
 633         Channel *c = channel_lookup(id);
 634
 635         if (c == NULL) {
 636                 logit("channel_request_start: %d: unknown channel id", id);
 637                 return;
 638         }
 639         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 640         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 641         packet_put_int(c->remote_id);
 642         packet_put_cstring(service);
 643         packet_put_char(wantconfirm);
 644 }
 645
 646 void
 647 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
 648 {
 649         Channel *c = channel_lookup(id);
 650
 651         if (c == NULL) {
 652                 logit("channel_register_comfirm: %d: bad id", id);
 653                 return;
 654         }
 655         c->confirm = fn;
 656         c->confirm_ctx = ctx;
 657 }
 658
 659 void
 660 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 661 {
 662         Channel *c = channel_by_id(id);
 663
 664         if (c == NULL) {
 665                 logit("channel_register_cleanup: %d: bad id", id);
 666                 return;
 667         }
 668         c->detach_user = fn;
 669         c->detach_close = do_close;
 670 }
 671
 672 void
 673 channel_cancel_cleanup(int id)
 674 {
 675         Channel *c = channel_by_id(id);
 676
 677         if (c == NULL) {
 678                 logit("channel_cancel_cleanup: %d: bad id", id);
 679                 return;
 680         }
 681         c->detach_user = NULL;
 682         c->detach_close = 0;
 683 }
 684
 685 void
 686 channel_register_filter(int id, channel_infilter_fn *ifn,
 687     channel_outfilter_fn *ofn)
 688 {
 689         Channel *c = channel_lookup(id);
 690
 691         if (c == NULL) {
 692                 logit("channel_register_filter: %d: bad id", id);
 693                 return;
 694         }
 695         c->input_filter = ifn;
 696         c->output_filter = ofn;
 697 }
 698
 699 void
 700 channel_set_fds(int id, int rfd, int wfd, int efd,
 701     int extusage, int nonblock, u_int window_max)
 702 {
 703         Channel *c = channel_lookup(id);
 704
 705         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 706                 fatal("channel_activate for non-larval channel %d.", id);
 707         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 708         c->type = SSH_CHANNEL_OPEN;
 709         c->local_window = c->local_window_max = window_max;
 710         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 711         packet_put_int(c->remote_id);
 712         packet_put_int(c->local_window);
 713         packet_send();
 714 }
 715
 716 /*
 717  * 'channel_pre*' are called just before select() to add any bits relevant to
 718  * channels in the select bitmasks.
 719  */
 720 /*
 721  * 'channel_post*': perform any appropriate operations for channels which
 722  * have events pending.
 723  */
 724 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 725 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 726 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 727
 728 static void
 729 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 730 {
 731         FD_SET(c->sock, readset);
 732 }
 733
 734 static void
 735 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 736 {
 737         debug3("channel %d: waiting for connection", c->self);
 738         FD_SET(c->sock, writeset);
 739 }
 740
 741 static void
 742 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 743 {
 744         if (buffer_len(&c->input) < packet_get_maxsize())
 745                 FD_SET(c->sock, readset);
 746         if (buffer_len(&c->output) > 0)
 747                 FD_SET(c->sock, writeset);
 748 }
 749
 750 static void
 751 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 752 {
 753         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 754
 755         if (c->istate == CHAN_INPUT_OPEN &&
 756             limit > 0 &&
 757             buffer_len(&c->input) < limit &&
 758             buffer_check_alloc(&c->input, CHAN_RBUF))
 759                 FD_SET(c->rfd, readset);
 760         if (c->ostate == CHAN_OUTPUT_OPEN ||
 761             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 762                 if (buffer_len(&c->output) > 0) {
 763                         FD_SET(c->wfd, writeset);
 764                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 765                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 766                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 767                                     c->self, c->efd, buffer_len(&c->extended));
 768                         else
 769                                 chan_obuf_empty(c);
 770                 }
 771         }
 772         /** XXX check close conditions, too */
 773         if (compat20 && c->efd != -1) {
 774                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 775                     buffer_len(&c->extended) > 0)
 776                         FD_SET(c->efd, writeset);
 777                 else if (!(c->flags & CHAN_EOF_SENT) &&
 778                     c->extended_usage == CHAN_EXTENDED_READ &&
 779                     buffer_len(&c->extended) < c->remote_window)
 780                         FD_SET(c->efd, readset);
 781         }
 782         /* XXX: What about efd? races? */
 783         if (compat20 && c->ctl_fd != -1 &&
 784             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 785                 FD_SET(c->ctl_fd, readset);
 786 }
 787
 788 static void
 789 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 790 {
 791         if (buffer_len(&c->input) == 0) {
 792                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 793                 packet_put_int(c->remote_id);
 794                 packet_send();
 795                 c->type = SSH_CHANNEL_CLOSED;
 796                 debug2("channel %d: closing after input drain.", c->self);
 797         }
 798 }
 799
 800 static void
 801 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 802 {
 803         if (buffer_len(&c->output) == 0)
 804                 chan_mark_dead(c);
 805         else
 806                 FD_SET(c->sock, writeset);
 807 }
 808
 809 /*
 810  * This is a special state for X11 authentication spoofing.  An opened X11
 811  * connection (when authentication spoofing is being done) remains in this
 812  * state until the first packet has been completely read.  The authentication
 813  * data in that packet is then substituted by the real data if it matches the
 814  * fake data, and the channel is put into normal mode.
 815  * XXX All this happens at the client side.
 816  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 817  */
 818 static int
 819 x11_open_helper(Buffer *b)
 820 {
 821         u_char *ucp;
 822         u_int proto_len, data_len;
 823
 824         /* Check if the fixed size part of the packet is in buffer. */
 825         if (buffer_len(b) < 12)
 826                 return 0;
 827
 828         /* Parse the lengths of variable-length fields. */
 829         ucp = buffer_ptr(b);
 830         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 831                 proto_len = 256 * ucp[6] + ucp[7];
 832                 data_len = 256 * ucp[8] + ucp[9];
 833         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 834                 proto_len = ucp[6] + 256 * ucp[7];
 835                 data_len = ucp[8] + 256 * ucp[9];
 836         } else {
 837                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 838                     ucp[0]);
 839                 return -1;
 840         }
 841
 842         /* Check if the whole packet is in buffer. */
 843         if (buffer_len(b) <
 844             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 845                 return 0;
 846
 847         /* Check if authentication protocol matches. */
 848         if (proto_len != strlen(x11_saved_proto) ||
 849             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 850                 debug2("X11 connection uses different authentication protocol.");
 851                 return -1;
 852         }
 853         /* Check if authentication data matches our fake data. */
 854         if (data_len != x11_fake_data_len ||
 855             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 856                 x11_fake_data, x11_fake_data_len) != 0) {
 857                 debug2("X11 auth data does not match fake data.");
 858                 return -1;
 859         }
 860         /* Check fake data length */
 861         if (x11_fake_data_len != x11_saved_data_len) {
 862                 error("X11 fake_data_len %d != saved_data_len %d",
 863                     x11_fake_data_len, x11_saved_data_len);
 864                 return -1;
 865         }
 866         /*
 867          * Received authentication protocol and data match
 868          * our fake data. Substitute the fake data with real
 869          * data.
 870          */
 871         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 872             x11_saved_data, x11_saved_data_len);
 873         return 1;
 874 }
 875
 876 static void
 877 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 878 {
 879         int ret = x11_open_helper(&c->output);
 880
 881         if (ret == 1) {
 882                 /* Start normal processing for the channel. */
 883                 c->type = SSH_CHANNEL_OPEN;
 884                 channel_pre_open_13(c, readset, writeset);
 885         } else if (ret == -1) {
 886                 /*
 887                  * We have received an X11 connection that has bad
 888                  * authentication information.
 889                  */
 890                 logit("X11 connection rejected because of wrong authentication.");
 891                 buffer_clear(&c->input);
 892                 buffer_clear(&c->output);
 893                 channel_close_fd(&c->sock);
 894                 c->sock = -1;
 895                 c->type = SSH_CHANNEL_CLOSED;
 896                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 897                 packet_put_int(c->remote_id);
 898                 packet_send();
 899         }
 900 }
 901
 902 static void
 903 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 904 {
 905         int ret = x11_open_helper(&c->output);
 906
 907         /* c->force_drain = 1; */
 908
 909         if (ret == 1) {
 910                 c->type = SSH_CHANNEL_OPEN;
 911                 channel_pre_open(c, readset, writeset);
 912         } else if (ret == -1) {
 913                 logit("X11 connection rejected because of wrong authentication.");
 914                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 915                 chan_read_failed(c);
 916                 buffer_clear(&c->input);
 917                 chan_ibuf_empty(c);
 918                 buffer_clear(&c->output);
 919                 /* for proto v1, the peer will send an IEOF */
 920                 if (compat20)
 921                         chan_write_failed(c);
 922                 else
 923                         c->type = SSH_CHANNEL_OPEN;
 924                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 925         }
 926 }
 927
 928 /* try to decode a socks4 header */
 929 static int
 930 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 931 {
 932         char *p, *host;
 933         u_int len, have, i, found;
 934         char username[256];
 935         struct {
 936                 u_int8_t version;
 937                 u_int8_t command;
 938                 u_int16_t dest_port;
 939                 struct in_addr dest_addr;
 940         } s4_req, s4_rsp;
 941
 942         debug2("channel %d: decode socks4", c->self);
 943
 944         have = buffer_len(&c->input);
 945         len = sizeof(s4_req);
 946         if (have < len)
 947                 return 0;
 948         p = buffer_ptr(&c->input);
 949         for (found = 0, i = len; i < have; i++) {
 950                 if (p[i] == '\0') {
 951                         found = 1;
 952                         break;
 953                 }
 954                 if (i > 1024) {
 955                         /* the peer is probably sending garbage */
 956                         debug("channel %d: decode socks4: too long",
 957                             c->self);
 958                         return -1;
 959                 }
 960         }
 961         if (!found)
 962                 return 0;
 963         buffer_get(&c->input, (char *)&s4_req.version, 1);
 964         buffer_get(&c->input, (char *)&s4_req.command, 1);
 965         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
 966         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
 967         have = buffer_len(&c->input);
 968         p = buffer_ptr(&c->input);
 969         len = strlen(p);
 970         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
 971         if (len > have)
 972                 fatal("channel %d: decode socks4: len %d > have %d",
 973                     c->self, len, have);
 974         strlcpy(username, p, sizeof(username));
 975         buffer_consume(&c->input, len);
 976         buffer_consume(&c->input, 1);           /* trailing '\0' */
 977
 978         host = inet_ntoa(s4_req.dest_addr);
 979         strlcpy(c->path, host, sizeof(c->path));
 980         c->host_port = ntohs(s4_req.dest_port);
 981
 982         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
 983             c->self, host, c->host_port, s4_req.command);
 984
 985         if (s4_req.command != 1) {
 986                 debug("channel %d: cannot handle: socks4 cn %d",
 987                     c->self, s4_req.command);
 988                 return -1;
 989         }
 990         s4_rsp.version = 0;                     /* vn: 0 for reply */
 991         s4_rsp.command = 90;                    /* cd: req granted */
 992         s4_rsp.dest_port = 0;                   /* ignored */
 993         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
 994         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
 995         return 1;
 996 }
 997
 998 /* try to decode a socks5 header */
 999 #define SSH_SOCKS5_AUTHDONE     0x1000
1000 #define SSH_SOCKS5_NOAUTH       0x00
1001 #define SSH_SOCKS5_IPV4         0x01
1002 #define SSH_SOCKS5_DOMAIN       0x03
1003 #define SSH_SOCKS5_IPV6         0x04
1004 #define SSH_SOCKS5_CONNECT      0x01
1005 #define SSH_SOCKS5_SUCCESS      0x00
1006
1007 static int
1008 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1009 {
1010         struct {
1011                 u_int8_t version;
1012                 u_int8_t command;
1013                 u_int8_t reserved;
1014                 u_int8_t atyp;
1015         } s5_req, s5_rsp;
1016         u_int16_t dest_port;
1017         u_char *p, dest_addr[255+1];
1018         u_int have, need, i, found, nmethods, addrlen, af;
1019
1020         debug2("channel %d: decode socks5", c->self);
1021         p = buffer_ptr(&c->input);
1022         if (p[0] != 0x05)
1023                 return -1;
1024         have = buffer_len(&c->input);
1025         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1026                 /* format: ver | nmethods | methods */
1027                 if (have < 2)
1028                         return 0;
1029                 nmethods = p[1];
1030                 if (have < nmethods + 2)
1031                         return 0;
1032                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1033                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1034                         if (p[i] == SSH_SOCKS5_NOAUTH ) {
1035                                 found = 1;
1036                                 break;
1037                         }
1038                 }
1039                 if (!found) {
1040                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1041                             c->self);
1042                         return -1;
1043                 }
1044                 buffer_consume(&c->input, nmethods + 2);
1045                 buffer_put_char(&c->output, 0x05);              /* version */
1046                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1047                 FD_SET(c->sock, writeset);
1048                 c->flags |= SSH_SOCKS5_AUTHDONE;
1049                 debug2("channel %d: socks5 auth done", c->self);
1050                 return 0;                               /* need more */
1051         }
1052         debug2("channel %d: socks5 post auth", c->self);
1053         if (have < sizeof(s5_req)+1)
1054                 return 0;                       /* need more */
1055         memcpy(&s5_req, p, sizeof(s5_req));
1056         if (s5_req.version != 0x05 ||
1057             s5_req.command != SSH_SOCKS5_CONNECT ||
1058             s5_req.reserved != 0x00) {
1059                 debug2("channel %d: only socks5 connect supported", c->self);
1060                 return -1;
1061         }
1062         switch (s5_req.atyp){
1063         case SSH_SOCKS5_IPV4:
1064                 addrlen = 4;
1065                 af = AF_INET;
1066                 break;
1067         case SSH_SOCKS5_DOMAIN:
1068                 addrlen = p[sizeof(s5_req)];
1069                 af = -1;
1070                 break;
1071         case SSH_SOCKS5_IPV6:
1072                 addrlen = 16;
1073                 af = AF_INET6;
1074                 break;
1075         default:
1076                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1077                 return -1;
1078         }
1079         need = sizeof(s5_req) + addrlen + 2;
1080         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1081                 need++;
1082         if (have < need)
1083                 return 0;
1084         buffer_consume(&c->input, sizeof(s5_req));
1085         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1086                 buffer_consume(&c->input, 1);    /* host string length */
1087         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1088         buffer_get(&c->input, (char *)&dest_port, 2);
1089         dest_addr[addrlen] = '\0';
1090         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1091                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1092         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1093                 return -1;
1094         c->host_port = ntohs(dest_port);
1095
1096         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1097             c->self, c->path, c->host_port, s5_req.command);
1098
1099         s5_rsp.version = 0x05;
1100         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1101         s5_rsp.reserved = 0;                    /* ignored */
1102         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1103         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1104         dest_port = 0;                          /* ignored */
1105
1106         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1107         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1108         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1109         return 1;
1110 }
1111
1112 /* dynamic port forwarding */
1113 static void
1114 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1115 {
1116         u_char *p;
1117         u_int have;
1118         int ret;
1119
1120         have = buffer_len(&c->input);
1121         c->delayed = 0;
1122         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1123         /* buffer_dump(&c->input); */
1124         /* check if the fixed size part of the packet is in buffer. */
1125         if (have < 3) {
1126                 /* need more */
1127                 FD_SET(c->sock, readset);
1128                 return;
1129         }
1130         /* try to guess the protocol */
1131         p = buffer_ptr(&c->input);
1132         switch (p[0]) {
1133         case 0x04:
1134                 ret = channel_decode_socks4(c, readset, writeset);
1135                 break;
1136         case 0x05:
1137                 ret = channel_decode_socks5(c, readset, writeset);
1138                 break;
1139         default:
1140                 ret = -1;
1141                 break;
1142         }
1143         if (ret < 0) {
1144                 chan_mark_dead(c);
1145         } else if (ret == 0) {
1146                 debug2("channel %d: pre_dynamic: need more", c->self);
1147                 /* need more */
1148                 FD_SET(c->sock, readset);
1149         } else {
1150                 /* switch to the next state */
1151                 c->type = SSH_CHANNEL_OPENING;
1152                 port_open_helper(c, "direct-tcpip");
1153         }
1154 }
1155
1156 /* This is our fake X11 server socket. */
1157 static void
1158 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1159 {
1160         Channel *nc;
1161         struct sockaddr addr;
1162         int newsock;
1163         socklen_t addrlen;
1164         char buf[16384], *remote_ipaddr;
1165         int remote_port;
1166
1167         if (FD_ISSET(c->sock, readset)) {
1168                 debug("X11 connection requested.");
1169                 addrlen = sizeof(addr);
1170                 newsock = accept(c->sock, &addr, &addrlen);
1171                 if (c->single_connection) {
1172                         debug2("single_connection: closing X11 listener.");
1173                         channel_close_fd(&c->sock);
1174                         chan_mark_dead(c);
1175                 }
1176                 if (newsock < 0) {
1177                         error("accept: %.100s", strerror(errno));
1178                         return;
1179                 }
1180                 set_nodelay(newsock);
1181                 remote_ipaddr = get_peer_ipaddr(newsock);
1182                 remote_port = get_peer_port(newsock);
1183                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1184                     remote_ipaddr, remote_port);
1185
1186                 nc = channel_new("accepted x11 socket",
1187                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1188                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1189                 if (compat20) {
1190                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1191                         packet_put_cstring("x11");
1192                         packet_put_int(nc->self);
1193                         packet_put_int(nc->local_window_max);
1194                         packet_put_int(nc->local_maxpacket);
1195                         /* originator ipaddr and port */
1196                         packet_put_cstring(remote_ipaddr);
1197                         if (datafellows & SSH_BUG_X11FWD) {
1198                                 debug2("ssh2 x11 bug compat mode");
1199                         } else {
1200                                 packet_put_int(remote_port);
1201                         }
1202                         packet_send();
1203                 } else {
1204                         packet_start(SSH_SMSG_X11_OPEN);
1205                         packet_put_int(nc->self);
1206                         if (packet_get_protocol_flags() &
1207                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1208                                 packet_put_cstring(buf);
1209                         packet_send();
1210                 }
1211                 xfree(remote_ipaddr);
1212         }
1213 }
1214
1215 static void
1216 port_open_helper(Channel *c, char *rtype)
1217 {
1218         int direct;
1219         char buf[1024];
1220         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1221         int remote_port = get_peer_port(c->sock);
1222
1223         direct = (strcmp(rtype, "direct-tcpip") == 0);
1224
1225         snprintf(buf, sizeof buf,
1226             "%s: listening port %d for %.100s port %d, "
1227             "connect from %.200s port %d",
1228             rtype, c->listening_port, c->path, c->host_port,
1229             remote_ipaddr, remote_port);
1230
1231         xfree(c->remote_name);
1232         c->remote_name = xstrdup(buf);
1233
1234         if (compat20) {
1235                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1236                 packet_put_cstring(rtype);
1237                 packet_put_int(c->self);
1238                 packet_put_int(c->local_window_max);
1239                 packet_put_int(c->local_maxpacket);
1240                 if (direct) {
1241                         /* target host, port */
1242                         packet_put_cstring(c->path);
1243                         packet_put_int(c->host_port);
1244                 } else {
1245                         /* listen address, port */
1246                         packet_put_cstring(c->path);
1247                         packet_put_int(c->listening_port);
1248                 }
1249                 /* originator host and port */
1250                 packet_put_cstring(remote_ipaddr);
1251                 packet_put_int((u_int)remote_port);
1252                 packet_send();
1253         } else {
1254                 packet_start(SSH_MSG_PORT_OPEN);
1255                 packet_put_int(c->self);
1256                 packet_put_cstring(c->path);
1257                 packet_put_int(c->host_port);
1258                 if (packet_get_protocol_flags() &
1259                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1260                         packet_put_cstring(c->remote_name);
1261                 packet_send();
1262         }
1263         xfree(remote_ipaddr);
1264 }
1265
1266 static void
1267 channel_set_reuseaddr(int fd)
1268 {
1269         int on = 1;
1270
1271         /*
1272          * Set socket options.
1273          * Allow local port reuse in TIME_WAIT.
1274          */
1275         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1276                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1277 }
1278
1279 /*
1280  * This socket is listening for connections to a forwarded TCP/IP port.
1281  */
1282 static void
1283 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1284 {
1285         Channel *nc;
1286         struct sockaddr addr;
1287         int newsock, nextstate;
1288         socklen_t addrlen;
1289         char *rtype;
1290
1291         if (FD_ISSET(c->sock, readset)) {
1292                 debug("Connection to port %d forwarding "
1293                     "to %.100s port %d requested.",
1294                     c->listening_port, c->path, c->host_port);
1295
1296                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1297                         nextstate = SSH_CHANNEL_OPENING;
1298                         rtype = "forwarded-tcpip";
1299                 } else {
1300                         if (c->host_port == 0) {
1301                                 nextstate = SSH_CHANNEL_DYNAMIC;
1302                                 rtype = "dynamic-tcpip";
1303                         } else {
1304                                 nextstate = SSH_CHANNEL_OPENING;
1305                                 rtype = "direct-tcpip";
1306                         }
1307                 }
1308
1309                 addrlen = sizeof(addr);
1310                 newsock = accept(c->sock, &addr, &addrlen);
1311                 if (newsock < 0) {
1312                         error("accept: %.100s", strerror(errno));
1313                         return;
1314                 }
1315                 set_nodelay(newsock);
1316                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1317                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1318                 nc->listening_port = c->listening_port;
1319                 nc->host_port = c->host_port;
1320                 strlcpy(nc->path, c->path, sizeof(nc->path));
1321
1322                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1323                         /*
1324                          * do not call the channel_post handler until
1325                          * this flag has been reset by a pre-handler.
1326                          * otherwise the FD_ISSET calls might overflow
1327                          */
1328                         nc->delayed = 1;
1329                 } else {
1330                         port_open_helper(nc, rtype);
1331                 }
1332         }
1333 }
1334
1335 /*
1336  * This is the authentication agent socket listening for connections from
1337  * clients.
1338  */
1339 static void
1340 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1341 {
1342         Channel *nc;
1343         int newsock;
1344         struct sockaddr addr;
1345         socklen_t addrlen;
1346
1347         if (FD_ISSET(c->sock, readset)) {
1348                 addrlen = sizeof(addr);
1349                 newsock = accept(c->sock, &addr, &addrlen);
1350                 if (newsock < 0) {
1351                         error("accept from auth socket: %.100s", strerror(errno));
1352                         return;
1353                 }
1354                 nc = channel_new("accepted auth socket",
1355                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1356                     c->local_window_max, c->local_maxpacket,
1357                     0, "accepted auth socket", 1);
1358                 if (compat20) {
1359                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1360                         packet_put_cstring("auth-agent@openssh.com");
1361                         packet_put_int(nc->self);
1362                         packet_put_int(c->local_window_max);
1363                         packet_put_int(c->local_maxpacket);
1364                 } else {
1365                         packet_start(SSH_SMSG_AGENT_OPEN);
1366                         packet_put_int(nc->self);
1367                 }
1368                 packet_send();
1369         }
1370 }
1371
1372 static void
1373 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1374 {
1375         int err = 0;
1376         socklen_t sz = sizeof(err);
1377
1378         if (FD_ISSET(c->sock, writeset)) {
1379                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1380                         err = errno;
1381                         error("getsockopt SO_ERROR failed");
1382                 }
1383                 if (err == 0) {
1384                         debug("channel %d: connected", c->self);
1385                         c->type = SSH_CHANNEL_OPEN;
1386                         if (compat20) {
1387                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1388                                 packet_put_int(c->remote_id);
1389                                 packet_put_int(c->self);
1390                                 packet_put_int(c->local_window);
1391                                 packet_put_int(c->local_maxpacket);
1392                         } else {
1393                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1394                                 packet_put_int(c->remote_id);
1395                                 packet_put_int(c->self);
1396                         }
1397                 } else {
1398                         debug("channel %d: not connected: %s",
1399                             c->self, strerror(err));
1400                         if (compat20) {
1401                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1402                                 packet_put_int(c->remote_id);
1403                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1404                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1405                                         packet_put_cstring(strerror(err));
1406                                         packet_put_cstring("");
1407                                 }
1408                         } else {
1409                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1410                                 packet_put_int(c->remote_id);
1411                         }
1412                         chan_mark_dead(c);
1413                 }
1414                 packet_send();
1415         }
1416 }
1417
1418 static int
1419 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1420 {
1421         char buf[CHAN_RBUF];
1422         int len;
1423
1424         if (c->rfd != -1 &&
1425             FD_ISSET(c->rfd, readset)) {
1426                 errno = 0;
1427                 len = read(c->rfd, buf, sizeof(buf));
1428                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1429                         return 1;
1430 #ifndef PTY_ZEROREAD
1431                 if (len <= 0) {
1432 #else
1433                 if ((!c->isatty && len <= 0) ||
1434                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1435 #endif
1436                         debug2("channel %d: read<=0 rfd %d len %d",
1437                             c->self, c->rfd, len);
1438                         if (c->type != SSH_CHANNEL_OPEN) {
1439                                 debug2("channel %d: not open", c->self);
1440                                 chan_mark_dead(c);
1441                                 return -1;
1442                         } else if (compat13) {
1443                                 buffer_clear(&c->output);
1444                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1445                                 debug2("channel %d: input draining.", c->self);
1446                         } else {
1447                                 chan_read_failed(c);
1448                         }
1449                         return -1;
1450                 }
1451                 if (c->input_filter != NULL) {
1452                         if (c->input_filter(c, buf, len) == -1) {
1453                                 debug2("channel %d: filter stops", c->self);
1454                                 chan_read_failed(c);
1455                         }
1456                 } else if (c->datagram) {
1457                         buffer_put_string(&c->input, buf, len);
1458                 } else {
1459                         buffer_append(&c->input, buf, len);
1460                 }
1461         }
1462         return 1;
1463 }
1464
1465 static int
1466 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1467 {
1468         struct termios tio;
1469         u_char *data = NULL, *buf;
1470         u_int dlen;
1471         int len;
1472
1473         /* Send buffered output data to the socket. */
1474         if (c->wfd != -1 &&
1475             FD_ISSET(c->wfd, writeset) &&
1476             buffer_len(&c->output) > 0) {
1477                 if (c->output_filter != NULL) {
1478                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1479                                 debug2("channel %d: filter stops", c->self);
1480                                 if (c->type != SSH_CHANNEL_OPEN)
1481                                         chan_mark_dead(c);
1482                                 else
1483                                         chan_write_failed(c);
1484                                 return -1;
1485                         }
1486                 } else if (c->datagram) {
1487                         buf = data = buffer_get_string(&c->output, &dlen);
1488                 } else {
1489                         buf = data = buffer_ptr(&c->output);
1490                         dlen = buffer_len(&c->output);
1491                 }
1492
1493                 if (c->datagram) {
1494                         /* ignore truncated writes, datagrams might get lost */
1495                         c->local_consumed += dlen + 4;
1496                         len = write(c->wfd, buf, dlen);
1497                         xfree(data);
1498                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1499                                 return 1;
1500                         if (len <= 0) {
1501                                 if (c->type != SSH_CHANNEL_OPEN)
1502                                         chan_mark_dead(c);
1503                                 else
1504                                         chan_write_failed(c);
1505                                 return -1;
1506                         }
1507                         return 1;
1508                 }
1509 #ifdef _AIX
1510                 /* XXX: Later AIX versions can't push as much data to tty */
1511                 if (compat20 && c->wfd_isatty)
1512                         dlen = MIN(dlen, 8*1024);
1513 #endif
1514
1515                 len = write(c->wfd, buf, dlen);
1516                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1517                         return 1;
1518                 if (len <= 0) {
1519                         if (c->type != SSH_CHANNEL_OPEN) {
1520                                 debug2("channel %d: not open", c->self);
1521                                 chan_mark_dead(c);
1522                                 return -1;
1523                         } else if (compat13) {
1524                                 buffer_clear(&c->output);
1525                                 debug2("channel %d: input draining.", c->self);
1526                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1527                         } else {
1528                                 chan_write_failed(c);
1529                         }
1530                         return -1;
1531                 }
1532                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1533                         if (tcgetattr(c->wfd, &tio) == 0 &&
1534                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1535                                 /*
1536                                  * Simulate echo to reduce the impact of
1537                                  * traffic analysis. We need to match the
1538                                  * size of a SSH2_MSG_CHANNEL_DATA message
1539                                  * (4 byte channel id + buf)
1540                                  */
1541                                 packet_send_ignore(4 + len);
1542                                 packet_send();
1543                         }
1544                 }
1545                 buffer_consume(&c->output, len);
1546                 if (compat20 && len > 0) {
1547                         c->local_consumed += len;
1548                 }
1549         }
1550         return 1;
1551 }
1552
1553 static int
1554 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1555 {
1556         char buf[CHAN_RBUF];
1557         int len;
1558
1559 /** XXX handle drain efd, too */
1560         if (c->efd != -1) {
1561                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1562                     FD_ISSET(c->efd, writeset) &&
1563                     buffer_len(&c->extended) > 0) {
1564                         len = write(c->efd, buffer_ptr(&c->extended),
1565                             buffer_len(&c->extended));
1566                         debug2("channel %d: written %d to efd %d",
1567                             c->self, len, c->efd);
1568                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1569                                 return 1;
1570                         if (len <= 0) {
1571                                 debug2("channel %d: closing write-efd %d",
1572                                     c->self, c->efd);
1573                                 channel_close_fd(&c->efd);
1574                         } else {
1575                                 buffer_consume(&c->extended, len);
1576                                 c->local_consumed += len;
1577                         }
1578                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1579                     FD_ISSET(c->efd, readset)) {
1580                         len = read(c->efd, buf, sizeof(buf));
1581                         debug2("channel %d: read %d from efd %d",
1582                             c->self, len, c->efd);
1583                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1584                                 return 1;
1585                         if (len <= 0) {
1586                                 debug2("channel %d: closing read-efd %d",
1587                                     c->self, c->efd);
1588                                 channel_close_fd(&c->efd);
1589                         } else {
1590                                 buffer_append(&c->extended, buf, len);
1591                         }
1592                 }
1593         }
1594         return 1;
1595 }
1596
1597 static int
1598 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1599 {
1600         char buf[16];
1601         int len;
1602
1603         /* Monitor control fd to detect if the slave client exits */
1604         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1605                 len = read(c->ctl_fd, buf, sizeof(buf));
1606                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1607                         return 1;
1608                 if (len <= 0) {
1609                         debug2("channel %d: ctl read<=0", c->self);
1610                         if (c->type != SSH_CHANNEL_OPEN) {
1611                                 debug2("channel %d: not open", c->self);
1612                                 chan_mark_dead(c);
1613                                 return -1;
1614                         } else {
1615                                 chan_read_failed(c);
1616                                 chan_write_failed(c);
1617                         }
1618                         return -1;
1619                 } else
1620                         fatal("%s: unexpected data on ctl fd", __func__);
1621         }
1622         return 1;
1623 }
1624
1625 static int
1626 channel_check_window(Channel *c)
1627 {
1628         if (c->type == SSH_CHANNEL_OPEN &&
1629             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1630             c->local_window < c->local_window_max/2 &&
1631             c->local_consumed > 0) {
1632                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1633                 packet_put_int(c->remote_id);
1634                 packet_put_int(c->local_consumed);
1635                 packet_send();
1636                 debug2("channel %d: window %d sent adjust %d",
1637                     c->self, c->local_window,
1638                     c->local_consumed);
1639                 c->local_window += c->local_consumed;
1640                 c->local_consumed = 0;
1641         }
1642         return 1;
1643 }
1644
1645 static void
1646 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1647 {
1648         if (c->delayed)
1649                 return;
1650         channel_handle_rfd(c, readset, writeset);
1651         channel_handle_wfd(c, readset, writeset);
1652         if (!compat20)
1653                 return;
1654         channel_handle_efd(c, readset, writeset);
1655         channel_handle_ctl(c, readset, writeset);
1656         channel_check_window(c);
1657 }
1658
1659 static void
1660 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1661 {
1662         int len;
1663
1664         /* Send buffered output data to the socket. */
1665         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1666                 len = write(c->sock, buffer_ptr(&c->output),
1667                             buffer_len(&c->output));
1668                 if (len <= 0)
1669                         buffer_clear(&c->output);
1670                 else
1671                         buffer_consume(&c->output, len);
1672         }
1673 }
1674
1675 static void
1676 channel_handler_init_20(void)
1677 {
1678         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1679         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1680         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1681         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1682         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1683         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1684         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1685         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1686
1687         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1688         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1689         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1690         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1691         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1692         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1693         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1694 }
1695
1696 static void
1697 channel_handler_init_13(void)
1698 {
1699         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1700         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1701         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1702         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1703         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1704         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1705         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1706         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1707         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1708
1709         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1710         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1711         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1712         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1713         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1714         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1715         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1716 }
1717
1718 static void
1719 channel_handler_init_15(void)
1720 {
1721         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1722         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1723         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1724         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1725         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1726         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1727         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1728
1729         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1730         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1731         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1732         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1733         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1734         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1735 }
1736
1737 static void
1738 channel_handler_init(void)
1739 {
1740         int i;
1741
1742         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1743                 channel_pre[i] = NULL;
1744                 channel_post[i] = NULL;
1745         }
1746         if (compat20)
1747                 channel_handler_init_20();
1748         else if (compat13)
1749                 channel_handler_init_13();
1750         else
1751                 channel_handler_init_15();
1752 }
1753
1754 /* gc dead channels */
1755 static void
1756 channel_garbage_collect(Channel *c)
1757 {
1758         if (c == NULL)
1759                 return;
1760         if (c->detach_user != NULL) {
1761                 if (!chan_is_dead(c, c->detach_close))
1762                         return;
1763                 debug2("channel %d: gc: notify user", c->self);
1764                 c->detach_user(c->self, NULL);
1765                 /* if we still have a callback */
1766                 if (c->detach_user != NULL)
1767                         return;
1768                 debug2("channel %d: gc: user detached", c->self);
1769         }
1770         if (!chan_is_dead(c, 1))
1771                 return;
1772         debug2("channel %d: garbage collecting", c->self);
1773         channel_free(c);
1774 }
1775
1776 static void
1777 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1778 {
1779         static int did_init = 0;
1780         u_int i;
1781         Channel *c;
1782
1783         if (!did_init) {
1784                 channel_handler_init();
1785                 did_init = 1;
1786         }
1787         for (i = 0; i < channels_alloc; i++) {
1788                 c = channels[i];
1789                 if (c == NULL)
1790                         continue;
1791                 if (ftab[c->type] != NULL)
1792                         (*ftab[c->type])(c, readset, writeset);
1793                 channel_garbage_collect(c);
1794         }
1795 }
1796
1797 /*
1798  * Allocate/update select bitmasks and add any bits relevant to channels in
1799  * select bitmasks.
1800  */
1801 void
1802 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1803     u_int *nallocp, int rekeying)
1804 {
1805         u_int n, sz, nfdset;
1806
1807         n = MAX(*maxfdp, channel_max_fd);
1808
1809         nfdset = howmany(n+1, NFDBITS);
1810         /* Explicitly test here, because xrealloc isn't always called */
1811         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1812                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1813         sz = nfdset * sizeof(fd_mask);
1814
1815         /* perhaps check sz < nalloc/2 and shrink? */
1816         if (*readsetp == NULL || sz > *nallocp) {
1817                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1818                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1819                 *nallocp = sz;
1820         }
1821         *maxfdp = n;
1822         memset(*readsetp, 0, sz);
1823         memset(*writesetp, 0, sz);
1824
1825         if (!rekeying)
1826                 channel_handler(channel_pre, *readsetp, *writesetp);
1827 }
1828
1829 /*
1830  * After select, perform any appropriate operations for channels which have
1831  * events pending.
1832  */
1833 void
1834 channel_after_select(fd_set *readset, fd_set *writeset)
1835 {
1836         channel_handler(channel_post, readset, writeset);
1837 }
1838
1839
1840 /* If there is data to send to the connection, enqueue some of it now. */
1841 void
1842 channel_output_poll(void)
1843 {
1844         Channel *c;
1845         u_int i, len;
1846
1847         for (i = 0; i < channels_alloc; i++) {
1848                 c = channels[i];
1849                 if (c == NULL)
1850                         continue;
1851
1852                 /*
1853                  * We are only interested in channels that can have buffered
1854                  * incoming data.
1855                  */
1856                 if (compat13) {
1857                         if (c->type != SSH_CHANNEL_OPEN &&
1858                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1859                                 continue;
1860                 } else {
1861                         if (c->type != SSH_CHANNEL_OPEN)
1862                                 continue;
1863                 }
1864                 if (compat20 &&
1865                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1866                         /* XXX is this true? */
1867                         debug3("channel %d: will not send data after close", c->self);
1868                         continue;
1869                 }
1870
1871                 /* Get the amount of buffered data for this channel. */
1872                 if ((c->istate == CHAN_INPUT_OPEN ||
1873                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1874                     (len = buffer_len(&c->input)) > 0) {
1875                         if (c->datagram) {
1876                                 if (len > 0) {
1877                                         u_char *data;
1878                                         u_int dlen;
1879
1880                                         data = buffer_get_string(&c->input,
1881                                             &dlen);
1882                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1883                                         packet_put_int(c->remote_id);
1884                                         packet_put_string(data, dlen);
1885                                         packet_send();
1886                                         c->remote_window -= dlen + 4;
1887                                         xfree(data);
1888                                 }
1889                                 continue;
1890                         }
1891                         /*
1892                          * Send some data for the other side over the secure
1893                          * connection.
1894                          */
1895                         if (compat20) {
1896                                 if (len > c->remote_window)
1897                                         len = c->remote_window;
1898                                 if (len > c->remote_maxpacket)
1899                                         len = c->remote_maxpacket;
1900                         } else {
1901                                 if (packet_is_interactive()) {
1902                                         if (len > 1024)
1903                                                 len = 512;
1904                                 } else {
1905                                         /* Keep the packets at reasonable size. */
1906                                         if (len > packet_get_maxsize()/2)
1907                                                 len = packet_get_maxsize()/2;
1908                                 }
1909                         }
1910                         if (len > 0) {
1911                                 packet_start(compat20 ?
1912                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1913                                 packet_put_int(c->remote_id);
1914                                 packet_put_string(buffer_ptr(&c->input), len);
1915                                 packet_send();
1916                                 buffer_consume(&c->input, len);
1917                                 c->remote_window -= len;
1918                         }
1919                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1920                         if (compat13)
1921                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1922                         /*
1923                          * input-buffer is empty and read-socket shutdown:
1924                          * tell peer, that we will not send more data: send IEOF.
1925                          * hack for extended data: delay EOF if EFD still in use.
1926                          */
1927                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1928                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1929                                     c->self, c->efd, buffer_len(&c->extended));
1930                         else
1931                                 chan_ibuf_empty(c);
1932                 }
1933                 /* Send extended data, i.e. stderr */
1934                 if (compat20 &&
1935                     !(c->flags & CHAN_EOF_SENT) &&
1936                     c->remote_window > 0 &&
1937                     (len = buffer_len(&c->extended)) > 0 &&
1938                     c->extended_usage == CHAN_EXTENDED_READ) {
1939                         debug2("channel %d: rwin %u elen %u euse %d",
1940                             c->self, c->remote_window, buffer_len(&c->extended),
1941                             c->extended_usage);
1942                         if (len > c->remote_window)
1943                                 len = c->remote_window;
1944                         if (len > c->remote_maxpacket)
1945                                 len = c->remote_maxpacket;
1946                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1947                         packet_put_int(c->remote_id);
1948                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1949                         packet_put_string(buffer_ptr(&c->extended), len);
1950                         packet_send();
1951                         buffer_consume(&c->extended, len);
1952                         c->remote_window -= len;
1953                         debug2("channel %d: sent ext data %d", c->self, len);
1954                 }
1955         }
1956 }
1957
1958
1959 /* -- protocol input */
1960
1961 /* ARGSUSED */
1962 void
1963 channel_input_data(int type, u_int32_t seq, void *ctxt)
1964 {
1965         int id;
1966         char *data;
1967         u_int data_len;
1968         Channel *c;
1969
1970         /* Get the channel number and verify it. */
1971         id = packet_get_int();
1972         c = channel_lookup(id);
1973         if (c == NULL)
1974                 packet_disconnect("Received data for nonexistent channel %d.", id);
1975
1976         /* Ignore any data for non-open channels (might happen on close) */
1977         if (c->type != SSH_CHANNEL_OPEN &&
1978             c->type != SSH_CHANNEL_X11_OPEN)
1979                 return;
1980
1981         /* Get the data. */
1982         data = packet_get_string(&data_len);
1983
1984         /*
1985          * Ignore data for protocol > 1.3 if output end is no longer open.
1986          * For protocol 2 the sending side is reducing its window as it sends
1987          * data, so we must 'fake' consumption of the data in order to ensure
1988          * that window updates are sent back.  Otherwise the connection might
1989          * deadlock.
1990          */
1991         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
1992                 if (compat20) {
1993                         c->local_window -= data_len;
1994                         c->local_consumed += data_len;
1995                 }
1996                 xfree(data);
1997                 return;
1998         }
1999
2000         if (compat20) {
2001                 if (data_len > c->local_maxpacket) {
2002                         logit("channel %d: rcvd big packet %d, maxpack %d",
2003                             c->self, data_len, c->local_maxpacket);
2004                 }
2005                 if (data_len > c->local_window) {
2006                         logit("channel %d: rcvd too much data %d, win %d",
2007                             c->self, data_len, c->local_window);
2008                         xfree(data);
2009                         return;
2010                 }
2011                 c->local_window -= data_len;
2012         }
2013         packet_check_eom();
2014         if (c->datagram)
2015                 buffer_put_string(&c->output, data, data_len);
2016         else
2017                 buffer_append(&c->output, data, data_len);
2018         xfree(data);
2019 }
2020
2021 /* ARGSUSED */
2022 void
2023 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2024 {
2025         int id;
2026         char *data;
2027         u_int data_len, tcode;
2028         Channel *c;
2029
2030         /* Get the channel number and verify it. */
2031         id = packet_get_int();
2032         c = channel_lookup(id);
2033
2034         if (c == NULL)
2035                 packet_disconnect("Received extended_data for bad channel %d.", id);
2036         if (c->type != SSH_CHANNEL_OPEN) {
2037                 logit("channel %d: ext data for non open", id);
2038                 return;
2039         }
2040         if (c->flags & CHAN_EOF_RCVD) {
2041                 if (datafellows & SSH_BUG_EXTEOF)
2042                         debug("channel %d: accepting ext data after eof", id);
2043                 else
2044                         packet_disconnect("Received extended_data after EOF "
2045                             "on channel %d.", id);
2046         }
2047         tcode = packet_get_int();
2048         if (c->efd == -1 ||
2049             c->extended_usage != CHAN_EXTENDED_WRITE ||
2050             tcode != SSH2_EXTENDED_DATA_STDERR) {
2051                 logit("channel %d: bad ext data", c->self);
2052                 return;
2053         }
2054         data = packet_get_string(&data_len);
2055         packet_check_eom();
2056         if (data_len > c->local_window) {
2057                 logit("channel %d: rcvd too much extended_data %d, win %d",
2058                     c->self, data_len, c->local_window);
2059                 xfree(data);
2060                 return;
2061         }
2062         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2063         c->local_window -= data_len;
2064         buffer_append(&c->extended, data, data_len);
2065         xfree(data);
2066 }
2067
2068 /* ARGSUSED */
2069 void
2070 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2071 {
2072         int id;
2073         Channel *c;
2074
2075         id = packet_get_int();
2076         packet_check_eom();
2077         c = channel_lookup(id);
2078         if (c == NULL)
2079                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2080         chan_rcvd_ieof(c);
2081
2082         /* XXX force input close */
2083         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2084                 debug("channel %d: FORCE input drain", c->self);
2085                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2086                 if (buffer_len(&c->input) == 0)
2087                         chan_ibuf_empty(c);
2088         }
2089
2090 }
2091
2092 /* ARGSUSED */
2093 void
2094 channel_input_close(int type, u_int32_t seq, void *ctxt)
2095 {
2096         int id;
2097         Channel *c;
2098
2099         id = packet_get_int();
2100         packet_check_eom();
2101         c = channel_lookup(id);
2102         if (c == NULL)
2103                 packet_disconnect("Received close for nonexistent channel %d.", id);
2104
2105         /*
2106          * Send a confirmation that we have closed the channel and no more
2107          * data is coming for it.
2108          */
2109         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2110         packet_put_int(c->remote_id);
2111         packet_send();
2112
2113         /*
2114          * If the channel is in closed state, we have sent a close request,
2115          * and the other side will eventually respond with a confirmation.
2116          * Thus, we cannot free the channel here, because then there would be
2117          * no-one to receive the confirmation.  The channel gets freed when
2118          * the confirmation arrives.
2119          */
2120         if (c->type != SSH_CHANNEL_CLOSED) {
2121                 /*
2122                  * Not a closed channel - mark it as draining, which will
2123                  * cause it to be freed later.
2124                  */
2125                 buffer_clear(&c->input);
2126                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2127         }
2128 }
2129
2130 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2131 /* ARGSUSED */
2132 void
2133 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2134 {
2135         int id = packet_get_int();
2136         Channel *c = channel_lookup(id);
2137
2138         packet_check_eom();
2139         if (c == NULL)
2140                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2141         chan_rcvd_oclose(c);
2142 }
2143
2144 /* ARGSUSED */
2145 void
2146 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2147 {
2148         int id = packet_get_int();
2149         Channel *c = channel_lookup(id);
2150
2151         packet_check_eom();
2152         if (c == NULL)
2153                 packet_disconnect("Received close confirmation for "
2154                     "out-of-range channel %d.", id);
2155         if (c->type != SSH_CHANNEL_CLOSED)
2156                 packet_disconnect("Received close confirmation for "
2157                     "non-closed channel %d (type %d).", id, c->type);
2158         channel_free(c);
2159 }
2160
2161 /* ARGSUSED */
2162 void
2163 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2164 {
2165         int id, remote_id;
2166         Channel *c;
2167
2168         id = packet_get_int();
2169         c = channel_lookup(id);
2170
2171         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2172                 packet_disconnect("Received open confirmation for "
2173                     "non-opening channel %d.", id);
2174         remote_id = packet_get_int();
2175         /* Record the remote channel number and mark that the channel is now open. */
2176         c->remote_id = remote_id;
2177         c->type = SSH_CHANNEL_OPEN;
2178
2179         if (compat20) {
2180                 c->remote_window = packet_get_int();
2181                 c->remote_maxpacket = packet_get_int();
2182                 if (c->confirm) {
2183                         debug2("callback start");
2184                         c->confirm(c->self, c->confirm_ctx);
2185                         debug2("callback done");
2186                 }
2187                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2188                     c->remote_window, c->remote_maxpacket);
2189         }
2190         packet_check_eom();
2191 }
2192
2193 static char *
2194 reason2txt(int reason)
2195 {
2196         switch (reason) {
2197         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2198                 return "administratively prohibited";
2199         case SSH2_OPEN_CONNECT_FAILED:
2200                 return "connect failed";
2201         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2202                 return "unknown channel type";
2203         case SSH2_OPEN_RESOURCE_SHORTAGE:
2204                 return "resource shortage";
2205         }
2206         return "unknown reason";
2207 }
2208
2209 /* ARGSUSED */
2210 void
2211 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2212 {
2213         int id, reason;
2214         char *msg = NULL, *lang = NULL;
2215         Channel *c;
2216
2217         id = packet_get_int();
2218         c = channel_lookup(id);
2219
2220         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2221                 packet_disconnect("Received open failure for "
2222                     "non-opening channel %d.", id);
2223         if (compat20) {
2224                 reason = packet_get_int();
2225                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2226                         msg  = packet_get_string(NULL);
2227                         lang = packet_get_string(NULL);
2228                 }
2229                 logit("channel %d: open failed: %s%s%s", id,
2230                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2231                 if (msg != NULL)
2232                         xfree(msg);
2233                 if (lang != NULL)
2234                         xfree(lang);
2235         }
2236         packet_check_eom();
2237         /* Free the channel.  This will also close the socket. */
2238         channel_free(c);
2239 }
2240
2241 /* ARGSUSED */
2242 void
2243 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2244 {
2245         Channel *c;
2246         int id;
2247         u_int adjust;
2248
2249         if (!compat20)
2250                 return;
2251
2252         /* Get the channel number and verify it. */
2253         id = packet_get_int();
2254         c = channel_lookup(id);
2255
2256         if (c == NULL) {
2257                 logit("Received window adjust for non-open channel %d.", id);
2258                 return;
2259         }
2260         adjust = packet_get_int();
2261         packet_check_eom();
2262         debug2("channel %d: rcvd adjust %u", id, adjust);
2263         c->remote_window += adjust;
2264 }
2265
2266 /* ARGSUSED */
2267 void
2268 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2269 {
2270         Channel *c = NULL;
2271         u_short host_port;
2272         char *host, *originator_string;
2273         int remote_id, sock = -1;
2274
2275         remote_id = packet_get_int();
2276         host = packet_get_string(NULL);
2277         host_port = packet_get_int();
2278
2279         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2280                 originator_string = packet_get_string(NULL);
2281         } else {
2282                 originator_string = xstrdup("unknown (remote did not supply name)");
2283         }
2284         packet_check_eom();
2285         sock = channel_connect_to(host, host_port);
2286         if (sock != -1) {
2287                 c = channel_new("connected socket",
2288                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2289                     originator_string, 1);
2290                 c->remote_id = remote_id;
2291         }
2292         xfree(originator_string);
2293         if (c == NULL) {
2294                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2295                 packet_put_int(remote_id);
2296                 packet_send();
2297         }
2298         xfree(host);
2299 }
2300
2301
2302 /* -- tcp forwarding */
2303
2304 void
2305 channel_set_af(int af)
2306 {
2307         IPv4or6 = af;
2308 }
2309
2310 static int
2311 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2312     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2313 {
2314         Channel *c;
2315         int sock, r, success = 0, wildcard = 0, is_client;
2316         struct addrinfo hints, *ai, *aitop;
2317         const char *host, *addr;
2318         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2319
2320         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2321             listen_addr : host_to_connect;
2322         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2323
2324         if (host == NULL) {
2325                 error("No forward host name.");
2326                 return 0;
2327         }
2328         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2329                 error("Forward host name too long.");
2330                 return 0;
2331         }
2332
2333         /*
2334          * Determine whether or not a port forward listens to loopback,
2335          * specified address or wildcard. On the client, a specified bind
2336          * address will always override gateway_ports. On the server, a
2337          * gateway_ports of 1 (``yes'') will override the client's
2338          * specification and force a wildcard bind, whereas a value of 2
2339          * (``clientspecified'') will bind to whatever address the client
2340          * asked for.
2341          *
2342          * Special-case listen_addrs are:
2343          *
2344          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2345          * "" (empty string), "*"  -> wildcard v4/v6
2346          * "localhost"             -> loopback v4/v6
2347          */
2348         addr = NULL;
2349         if (listen_addr == NULL) {
2350                 /* No address specified: default to gateway_ports setting */
2351                 if (gateway_ports)
2352                         wildcard = 1;
2353         } else if (gateway_ports || is_client) {
2354                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2355                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2356                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2357                     (!is_client && gateway_ports == 1))
2358                         wildcard = 1;
2359                 else if (strcmp(listen_addr, "localhost") != 0)
2360                         addr = listen_addr;
2361         }
2362
2363         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2364             type, wildcard, (addr == NULL) ? "NULL" : addr);
2365
2366         /*
2367          * getaddrinfo returns a loopback address if the hostname is
2368          * set to NULL and hints.ai_flags is not AI_PASSIVE
2369          */
2370         memset(&hints, 0, sizeof(hints));
2371         hints.ai_family = IPv4or6;
2372         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2373         hints.ai_socktype = SOCK_STREAM;
2374         snprintf(strport, sizeof strport, "%d", listen_port);
2375         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2376                 if (addr == NULL) {
2377                         /* This really shouldn't happen */
2378                         packet_disconnect("getaddrinfo: fatal error: %s",
2379                             gai_strerror(r));
2380                 } else {
2381                         error("channel_setup_fwd_listener: "
2382                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2383                 }
2384                 return 0;
2385         }
2386
2387         for (ai = aitop; ai; ai = ai->ai_next) {
2388                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2389                         continue;
2390                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2391                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2392                         error("channel_setup_fwd_listener: getnameinfo failed");
2393                         continue;
2394                 }
2395                 /* Create a port to listen for the host. */
2396                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2397                 if (sock < 0) {
2398                         /* this is no error since kernel may not support ipv6 */
2399                         verbose("socket: %.100s", strerror(errno));
2400                         continue;
2401                 }
2402
2403                 channel_set_reuseaddr(sock);
2404
2405                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2406
2407                 /* Bind the socket to the address. */
2408                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2409                         /* address can be in use ipv6 address is already bound */
2410                         if (!ai->ai_next)
2411                                 error("bind: %.100s", strerror(errno));
2412                         else
2413                                 verbose("bind: %.100s", strerror(errno));
2414
2415                         close(sock);
2416                         continue;
2417                 }
2418                 /* Start listening for connections on the socket. */
2419                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2420                         error("listen: %.100s", strerror(errno));
2421                         close(sock);
2422                         continue;
2423                 }
2424                 /* Allocate a channel number for the socket. */
2425                 c = channel_new("port listener", type, sock, sock, -1,
2426                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2427                     0, "port listener", 1);
2428                 strlcpy(c->path, host, sizeof(c->path));
2429                 c->host_port = port_to_connect;
2430                 c->listening_port = listen_port;
2431                 success = 1;
2432         }
2433         if (success == 0)
2434                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2435                     listen_port);
2436         freeaddrinfo(aitop);
2437         return success;
2438 }
2439
2440 int
2441 channel_cancel_rport_listener(const char *host, u_short port)
2442 {
2443         u_int i;
2444         int found = 0;
2445
2446         for (i = 0; i < channels_alloc; i++) {
2447                 Channel *c = channels[i];
2448
2449                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2450                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2451                     c->listening_port == port) {
2452                         debug2("%s: close channel %d", __func__, i);
2453                         channel_free(c);
2454                         found = 1;
2455                 }
2456         }
2457
2458         return (found);
2459 }
2460
2461 /* protocol local port fwd, used by ssh (and sshd in v1) */
2462 int
2463 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2464     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2465 {
2466         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2467             listen_host, listen_port, host_to_connect, port_to_connect,
2468             gateway_ports);
2469 }
2470
2471 /* protocol v2 remote port fwd, used by sshd */
2472 int
2473 channel_setup_remote_fwd_listener(const char *listen_address,
2474     u_short listen_port, int gateway_ports)
2475 {
2476         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2477             listen_address, listen_port, NULL, 0, gateway_ports);
2478 }
2479
2480 /*
2481  * Initiate forwarding of connections to port "port" on remote host through
2482  * the secure channel to host:port from local side.
2483  */
2484
2485 int
2486 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2487     const char *host_to_connect, u_short port_to_connect)
2488 {
2489         int type, success = 0;
2490
2491         /* Record locally that connection to this host/port is permitted. */
2492         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2493                 fatal("channel_request_remote_forwarding: too many forwards");
2494
2495         /* Send the forward request to the remote side. */
2496         if (compat20) {
2497                 const char *address_to_bind;
2498                 if (listen_host == NULL)
2499                         address_to_bind = "localhost";
2500                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2501                         address_to_bind = "";
2502                 else
2503                         address_to_bind = listen_host;
2504
2505                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2506                 packet_put_cstring("tcpip-forward");
2507                 packet_put_char(1);                     /* boolean: want reply */
2508                 packet_put_cstring(address_to_bind);
2509                 packet_put_int(listen_port);
2510                 packet_send();
2511                 packet_write_wait();
2512                 /* Assume that server accepts the request */
2513                 success = 1;
2514         } else {
2515                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2516                 packet_put_int(listen_port);
2517                 packet_put_cstring(host_to_connect);
2518                 packet_put_int(port_to_connect);
2519                 packet_send();
2520                 packet_write_wait();
2521
2522                 /* Wait for response from the remote side. */
2523                 type = packet_read();
2524                 switch (type) {
2525                 case SSH_SMSG_SUCCESS:
2526                         success = 1;
2527                         break;
2528                 case SSH_SMSG_FAILURE:
2529                         break;
2530                 default:
2531                         /* Unknown packet */
2532                         packet_disconnect("Protocol error for port forward request:"
2533                             "received packet type %d.", type);
2534                 }
2535         }
2536         if (success) {
2537                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2538                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2539                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2540                 num_permitted_opens++;
2541         }
2542         return (success ? 0 : -1);
2543 }
2544
2545 /*
2546  * Request cancellation of remote forwarding of connection host:port from
2547  * local side.
2548  */
2549 void
2550 channel_request_rforward_cancel(const char *host, u_short port)
2551 {
2552         int i;
2553
2554         if (!compat20)
2555                 return;
2556
2557         for (i = 0; i < num_permitted_opens; i++) {
2558                 if (permitted_opens[i].host_to_connect != NULL &&
2559                     permitted_opens[i].listen_port == port)
2560                         break;
2561         }
2562         if (i >= num_permitted_opens) {
2563                 debug("%s: requested forward not found", __func__);
2564                 return;
2565         }
2566         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2567         packet_put_cstring("cancel-tcpip-forward");
2568         packet_put_char(0);
2569         packet_put_cstring(host == NULL ? "" : host);
2570         packet_put_int(port);
2571         packet_send();
2572
2573         permitted_opens[i].listen_port = 0;
2574         permitted_opens[i].port_to_connect = 0;
2575         xfree(permitted_opens[i].host_to_connect);
2576         permitted_opens[i].host_to_connect = NULL;
2577 }
2578
2579 /*
2580  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2581  * listening for the port, and sends back a success reply (or disconnect
2582  * message if there was an error).
2583  */
2584 int
2585 channel_input_port_forward_request(int is_root, int gateway_ports)
2586 {
2587         u_short port, host_port;
2588         int success = 0;
2589         char *hostname;
2590
2591         /* Get arguments from the packet. */
2592         port = packet_get_int();
2593         hostname = packet_get_string(NULL);
2594         host_port = packet_get_int();
2595
2596 #ifndef HAVE_CYGWIN
2597         /*
2598          * Check that an unprivileged user is not trying to forward a
2599          * privileged port.
2600          */
2601         if (port < IPPORT_RESERVED && !is_root)
2602                 packet_disconnect(
2603                     "Requested forwarding of port %d but user is not root.",
2604                     port);
2605         if (host_port == 0)
2606                 packet_disconnect("Dynamic forwarding denied.");
2607 #endif
2608
2609         /* Initiate forwarding */
2610         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2611             host_port, gateway_ports);
2612
2613         /* Free the argument string. */
2614         xfree(hostname);
2615
2616         return (success ? 0 : -1);
2617 }
2618
2619 /*
2620  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2621  * usually called by the server, because the user could connect to any port
2622  * anyway, and the server has no way to know but to trust the client anyway.
2623  */
2624 void
2625 channel_permit_all_opens(void)
2626 {
2627         if (num_permitted_opens == 0)
2628                 all_opens_permitted = 1;
2629 }
2630
2631 void
2632 channel_add_permitted_opens(char *host, int port)
2633 {
2634         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2635                 fatal("channel_add_permitted_opens: too many forwards");
2636         debug("allow port forwarding to host %s port %d", host, port);
2637
2638         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2639         permitted_opens[num_permitted_opens].port_to_connect = port;
2640         num_permitted_opens++;
2641
2642         all_opens_permitted = 0;
2643 }
2644
2645 void
2646 channel_clear_permitted_opens(void)
2647 {
2648         int i;
2649
2650         for (i = 0; i < num_permitted_opens; i++)
2651                 if (permitted_opens[i].host_to_connect != NULL)
2652                         xfree(permitted_opens[i].host_to_connect);
2653         num_permitted_opens = 0;
2654
2655 }
2656
2657 /* return socket to remote host, port */
2658 static int
2659 connect_to(const char *host, u_short port)
2660 {
2661         struct addrinfo hints, *ai, *aitop;
2662         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2663         int gaierr;
2664         int sock = -1;
2665
2666         memset(&hints, 0, sizeof(hints));
2667         hints.ai_family = IPv4or6;
2668         hints.ai_socktype = SOCK_STREAM;
2669         snprintf(strport, sizeof strport, "%d", port);
2670         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2671                 error("connect_to %.100s: unknown host (%s)", host,
2672                     gai_strerror(gaierr));
2673                 return -1;
2674         }
2675         for (ai = aitop; ai; ai = ai->ai_next) {
2676                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2677                         continue;
2678                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2679                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2680                         error("connect_to: getnameinfo failed");
2681                         continue;
2682                 }
2683                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2684                 if (sock < 0) {
2685                         if (ai->ai_next == NULL)
2686                                 error("socket: %.100s", strerror(errno));
2687                         else
2688                                 verbose("socket: %.100s", strerror(errno));
2689                         continue;
2690                 }
2691                 if (set_nonblock(sock) == -1)
2692                         fatal("%s: set_nonblock(%d)", __func__, sock);
2693                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2694                     errno != EINPROGRESS) {
2695                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2696                             strerror(errno));
2697                         close(sock);
2698                         continue;       /* fail -- try next */
2699                 }
2700                 break; /* success */
2701
2702         }
2703         freeaddrinfo(aitop);
2704         if (!ai) {
2705                 error("connect_to %.100s port %d: failed.", host, port);
2706                 return -1;
2707         }
2708         /* success */
2709         set_nodelay(sock);
2710         return sock;
2711 }
2712
2713 int
2714 channel_connect_by_listen_address(u_short listen_port)
2715 {
2716         int i;
2717
2718         for (i = 0; i < num_permitted_opens; i++)
2719                 if (permitted_opens[i].host_to_connect != NULL &&
2720                     permitted_opens[i].listen_port == listen_port)
2721                         return connect_to(
2722                             permitted_opens[i].host_to_connect,
2723                             permitted_opens[i].port_to_connect);
2724         error("WARNING: Server requests forwarding for unknown listen_port %d",
2725             listen_port);
2726         return -1;
2727 }
2728
2729 /* Check if connecting to that port is permitted and connect. */
2730 int
2731 channel_connect_to(const char *host, u_short port)
2732 {
2733         int i, permit;
2734
2735         permit = all_opens_permitted;
2736         if (!permit) {
2737                 for (i = 0; i < num_permitted_opens; i++)
2738                         if (permitted_opens[i].host_to_connect != NULL &&
2739                             permitted_opens[i].port_to_connect == port &&
2740                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2741                                 permit = 1;
2742
2743         }
2744         if (!permit) {
2745                 logit("Received request to connect to host %.100s port %d, "
2746                     "but the request was denied.", host, port);
2747                 return -1;
2748         }
2749         return connect_to(host, port);
2750 }
2751
2752 void
2753 channel_send_window_changes(void)
2754 {
2755         u_int i;
2756         struct winsize ws;
2757
2758         for (i = 0; i < channels_alloc; i++) {
2759                 if (channels[i] == NULL || !channels[i]->client_tty ||
2760                     channels[i]->type != SSH_CHANNEL_OPEN)
2761                         continue;
2762                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2763                         continue;
2764                 channel_request_start(i, "window-change", 0);
2765                 packet_put_int((u_int)ws.ws_col);
2766                 packet_put_int((u_int)ws.ws_row);
2767                 packet_put_int((u_int)ws.ws_xpixel);
2768                 packet_put_int((u_int)ws.ws_ypixel);
2769                 packet_send();
2770         }
2771 }
2772
2773 /* -- X11 forwarding */
2774
2775 /*
2776  * Creates an internet domain socket for listening for X11 connections.
2777  * Returns 0 and a suitable display number for the DISPLAY variable
2778  * stored in display_numberp , or -1 if an error occurs.
2779  */
2780 int
2781 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2782     int single_connection, u_int *display_numberp, int **chanids)
2783 {
2784         Channel *nc = NULL;
2785         int display_number, sock;
2786         u_short port;
2787         struct addrinfo hints, *ai, *aitop;
2788         char strport[NI_MAXSERV];
2789         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2790
2791         if (chanids == NULL)
2792                 return -1;
2793
2794         for (display_number = x11_display_offset;
2795             display_number < MAX_DISPLAYS;
2796             display_number++) {
2797                 port = 6000 + display_number;
2798                 memset(&hints, 0, sizeof(hints));
2799                 hints.ai_family = IPv4or6;
2800                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2801                 hints.ai_socktype = SOCK_STREAM;
2802                 snprintf(strport, sizeof strport, "%d", port);
2803                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2804                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2805                         return -1;
2806                 }
2807                 for (ai = aitop; ai; ai = ai->ai_next) {
2808                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2809                                 continue;
2810                         sock = socket(ai->ai_family, ai->ai_socktype,
2811                             ai->ai_protocol);
2812                         if (sock < 0) {
2813                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2814                                         error("socket: %.100s", strerror(errno));
2815                                         freeaddrinfo(aitop);
2816                                         return -1;
2817                                 } else {
2818                                         debug("x11_create_display_inet: Socket family %d not supported",
2819                                                  ai->ai_family);
2820                                         continue;
2821                                 }
2822                         }
2823 #ifdef IPV6_V6ONLY
2824                         if (ai->ai_family == AF_INET6) {
2825                                 int on = 1;
2826                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2827                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2828                         }
2829 #endif
2830                         channel_set_reuseaddr(sock);
2831                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2832                                 debug2("bind port %d: %.100s", port, strerror(errno));
2833                                 close(sock);
2834
2835                                 if (ai->ai_next)
2836                                         continue;
2837
2838                                 for (n = 0; n < num_socks; n++) {
2839                                         close(socks[n]);
2840                                 }
2841                                 num_socks = 0;
2842                                 break;
2843                         }
2844                         socks[num_socks++] = sock;
2845 #ifndef DONT_TRY_OTHER_AF
2846                         if (num_socks == NUM_SOCKS)
2847                                 break;
2848 #else
2849                         if (x11_use_localhost) {
2850                                 if (num_socks == NUM_SOCKS)
2851                                         break;
2852                         } else {
2853                                 break;
2854                         }
2855 #endif
2856                 }
2857                 freeaddrinfo(aitop);
2858                 if (num_socks > 0)
2859                         break;
2860         }
2861         if (display_number >= MAX_DISPLAYS) {
2862                 error("Failed to allocate internet-domain X11 display socket.");
2863                 return -1;
2864         }
2865         /* Start listening for connections on the socket. */
2866         for (n = 0; n < num_socks; n++) {
2867                 sock = socks[n];
2868                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2869                         error("listen: %.100s", strerror(errno));
2870                         close(sock);
2871                         return -1;
2872                 }
2873         }
2874
2875         /* Allocate a channel for each socket. */
2876         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2877         for (n = 0; n < num_socks; n++) {
2878                 sock = socks[n];
2879                 nc = channel_new("x11 listener",
2880                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2881                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2882                     0, "X11 inet listener", 1);
2883                 nc->single_connection = single_connection;
2884                 (*chanids)[n] = nc->self;
2885         }
2886         (*chanids)[n] = -1;
2887
2888         /* Return the display number for the DISPLAY environment variable. */
2889         *display_numberp = display_number;
2890         return (0);
2891 }
2892
2893 static int
2894 connect_local_xsocket(u_int dnr)
2895 {
2896         int sock;
2897         struct sockaddr_un addr;
2898
2899         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2900         if (sock < 0)
2901                 error("socket: %.100s", strerror(errno));
2902         memset(&addr, 0, sizeof(addr));
2903         addr.sun_family = AF_UNIX;
2904         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2905         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
2906                 return sock;
2907         close(sock);
2908         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2909         return -1;
2910 }
2911
2912 int
2913 x11_connect_display(void)
2914 {
2915         u_int display_number;
2916         const char *display;
2917         char buf[1024], *cp;
2918         struct addrinfo hints, *ai, *aitop;
2919         char strport[NI_MAXSERV];
2920         int gaierr, sock = 0;
2921
2922         /* Try to open a socket for the local X server. */
2923         display = getenv("DISPLAY");
2924         if (!display) {
2925                 error("DISPLAY not set.");
2926                 return -1;
2927         }
2928         /*
2929          * Now we decode the value of the DISPLAY variable and make a
2930          * connection to the real X server.
2931          */
2932
2933         /*
2934          * Check if it is a unix domain socket.  Unix domain displays are in
2935          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2936          */
2937         if (strncmp(display, "unix:", 5) == 0 ||
2938             display[0] == ':') {
2939                 /* Connect to the unix domain socket. */
2940                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
2941                         error("Could not parse display number from DISPLAY: %.100s",
2942                             display);
2943                         return -1;
2944                 }
2945                 /* Create a socket. */
2946                 sock = connect_local_xsocket(display_number);
2947                 if (sock < 0)
2948                         return -1;
2949
2950                 /* OK, we now have a connection to the display. */
2951                 return sock;
2952         }
2953         /*
2954          * Connect to an inet socket.  The DISPLAY value is supposedly
2955          * hostname:d[.s], where hostname may also be numeric IP address.
2956          */
2957         strlcpy(buf, display, sizeof(buf));
2958         cp = strchr(buf, ':');
2959         if (!cp) {
2960                 error("Could not find ':' in DISPLAY: %.100s", display);
2961                 return -1;
2962         }
2963         *cp = 0;
2964         /* buf now contains the host name.  But first we parse the display number. */
2965         if (sscanf(cp + 1, "%u", &display_number) != 1) {
2966                 error("Could not parse display number from DISPLAY: %.100s",
2967                     display);
2968                 return -1;
2969         }
2970
2971         /* Look up the host address */
2972         memset(&hints, 0, sizeof(hints));
2973         hints.ai_family = IPv4or6;
2974         hints.ai_socktype = SOCK_STREAM;
2975         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
2976         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
2977                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
2978                 return -1;
2979         }
2980         for (ai = aitop; ai; ai = ai->ai_next) {
2981                 /* Create a socket. */
2982                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2983                 if (sock < 0) {
2984                         debug2("socket: %.100s", strerror(errno));
2985                         continue;
2986                 }
2987                 /* Connect it to the display. */
2988                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2989                         debug2("connect %.100s port %u: %.100s", buf,
2990                             6000 + display_number, strerror(errno));
2991                         close(sock);
2992                         continue;
2993                 }
2994                 /* Success */
2995                 break;
2996         }
2997         freeaddrinfo(aitop);
2998         if (!ai) {
2999                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3000                     strerror(errno));
3001                 return -1;
3002         }
3003         set_nodelay(sock);
3004         return sock;
3005 }
3006
3007 /*
3008  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3009  * the remote channel number.  We should do whatever we want, and respond
3010  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3011  */
3012
3013 void
3014 x11_input_open(int type, u_int32_t seq, void *ctxt)
3015 {
3016         Channel *c = NULL;
3017         int remote_id, sock = 0;
3018         char *remote_host;
3019
3020         debug("Received X11 open request.");
3021
3022         remote_id = packet_get_int();
3023
3024         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3025                 remote_host = packet_get_string(NULL);
3026         } else {
3027                 remote_host = xstrdup("unknown (remote did not supply name)");
3028         }
3029         packet_check_eom();
3030
3031         /* Obtain a connection to the real X display. */
3032         sock = x11_connect_display();
3033         if (sock != -1) {
3034                 /* Allocate a channel for this connection. */
3035                 c = channel_new("connected x11 socket",
3036                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3037                     remote_host, 1);
3038                 c->remote_id = remote_id;
3039                 c->force_drain = 1;
3040         }
3041         xfree(remote_host);
3042         if (c == NULL) {
3043                 /* Send refusal to the remote host. */
3044                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3045                 packet_put_int(remote_id);
3046         } else {
3047                 /* Send a confirmation to the remote host. */
3048                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3049                 packet_put_int(remote_id);
3050                 packet_put_int(c->self);
3051         }
3052         packet_send();
3053 }
3054
3055 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3056 void
3057 deny_input_open(int type, u_int32_t seq, void *ctxt)
3058 {
3059         int rchan = packet_get_int();
3060
3061         switch (type) {
3062         case SSH_SMSG_AGENT_OPEN:
3063                 error("Warning: ssh server tried agent forwarding.");
3064                 break;
3065         case SSH_SMSG_X11_OPEN:
3066                 error("Warning: ssh server tried X11 forwarding.");
3067                 break;
3068         default:
3069                 error("deny_input_open: type %d", type);
3070                 break;
3071         }
3072         error("Warning: this is probably a break-in attempt by a malicious server.");
3073         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3074         packet_put_int(rchan);
3075         packet_send();
3076 }
3077
3078 /*
3079  * Requests forwarding of X11 connections, generates fake authentication
3080  * data, and enables authentication spoofing.
3081  * This should be called in the client only.
3082  */
3083 void
3084 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3085     const char *proto, const char *data)
3086 {
3087         u_int data_len = (u_int) strlen(data) / 2;
3088         u_int i, value;
3089         char *new_data;
3090         int screen_number;
3091         const char *cp;
3092         u_int32_t rnd = 0;
3093
3094         if (x11_saved_display == NULL)
3095                 x11_saved_display = xstrdup(disp);
3096         else if (strcmp(disp, x11_saved_display) != 0) {
3097                 error("x11_request_forwarding_with_spoofing: different "
3098                     "$DISPLAY already forwarded");
3099                 return;
3100         }
3101
3102         cp = disp;
3103         if (disp)
3104                 cp = strchr(disp, ':');
3105         if (cp)
3106                 cp = strchr(cp, '.');
3107         if (cp)
3108                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3109         else
3110                 screen_number = 0;
3111
3112         if (x11_saved_proto == NULL) {
3113                 /* Save protocol name. */
3114                 x11_saved_proto = xstrdup(proto);
3115                 /*
3116                  * Extract real authentication data and generate fake data
3117                  * of the same length.
3118                  */
3119                 x11_saved_data = xmalloc(data_len);
3120                 x11_fake_data = xmalloc(data_len);
3121                 for (i = 0; i < data_len; i++) {
3122                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3123                                 fatal("x11_request_forwarding: bad "
3124                                     "authentication data: %.100s", data);
3125                         if (i % 4 == 0)
3126                                 rnd = arc4random();
3127                         x11_saved_data[i] = value;
3128                         x11_fake_data[i] = rnd & 0xff;
3129                         rnd >>= 8;
3130                 }
3131                 x11_saved_data_len = data_len;
3132                 x11_fake_data_len = data_len;
3133         }
3134
3135         /* Convert the fake data into hex. */
3136         new_data = tohex(x11_fake_data, data_len);
3137
3138         /* Send the request packet. */
3139         if (compat20) {
3140                 channel_request_start(client_session_id, "x11-req", 0);
3141                 packet_put_char(0);     /* XXX bool single connection */
3142         } else {
3143                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3144         }
3145         packet_put_cstring(proto);
3146         packet_put_cstring(new_data);
3147         packet_put_int(screen_number);
3148         packet_send();
3149         packet_write_wait();
3150         xfree(new_data);
3151 }
3152
3153
3154 /* -- agent forwarding */
3155
3156 /* Sends a message to the server to request authentication fd forwarding. */
3157
3158 void
3159 auth_request_forwarding(void)
3160 {
3161         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3162         packet_send();
3163         packet_write_wait();
3164 }