channels.c

   1 /* $OpenBSD: channels.c,v 1.280 2008/06/12 15:19:17 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <netdb.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <termios.h>
  61 #include <unistd.h>
  62 #include <stdarg.h>
  63
  64 #include "openbsd-compat/sys-queue.h"
  65 #include "xmalloc.h"
  66 #include "ssh.h"
  67 #include "ssh1.h"
  68 #include "ssh2.h"
  69 #include "packet.h"
  70 #include "log.h"
  71 #include "misc.h"
  72 #include "buffer.h"
  73 #include "channels.h"
  74 #include "compat.h"
  75 #include "canohost.h"
  76 #include "key.h"
  77 #include "authfd.h"
  78 #include "pathnames.h"
  79
  80 /* -- channel core */
  81
  82 /*
  83  * Pointer to an array containing all allocated channels.  The array is
  84  * dynamically extended as needed.
  85  */
  86 static Channel **channels = NULL;
  87
  88 /*
  89  * Size of the channel array.  All slots of the array must always be
  90  * initialized (at least the type field); unused slots set to NULL
  91  */
  92 static u_int channels_alloc = 0;
  93
  94 /*
  95  * Maximum file descriptor value used in any of the channels.  This is
  96  * updated in channel_new.
  97  */
  98 static int channel_max_fd = 0;
  99
 100
 101 /* -- tcp forwarding */
 102
 103 /*
 104  * Data structure for storing which hosts are permitted for forward requests.
 105  * The local sides of any remote forwards are stored in this array to prevent
 106  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 107  * network (which might be behind a firewall).
 108  */
 109 typedef struct {
 110         char *host_to_connect;          /* Connect to 'host'. */
 111         u_short port_to_connect;        /* Connect to 'port'. */
 112         u_short listen_port;            /* Remote side should listen port number. */
 113 } ForwardPermission;
 114
 115 /* List of all permitted host/port pairs to connect by the user. */
 116 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 117
 118 /* List of all permitted host/port pairs to connect by the admin. */
 119 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 120
 121 /* Number of permitted host/port pairs in the array permitted by the user. */
 122 static int num_permitted_opens = 0;
 123
 124 /* Number of permitted host/port pair in the array permitted by the admin. */
 125 static int num_adm_permitted_opens = 0;
 126
 127 /*
 128  * If this is true, all opens are permitted.  This is the case on the server
 129  * on which we have to trust the client anyway, and the user could do
 130  * anything after logging in anyway.
 131  */
 132 static int all_opens_permitted = 0;
 133
 134
 135 /* -- X11 forwarding */
 136
 137 /* Maximum number of fake X11 displays to try. */
 138 #define MAX_DISPLAYS  1000
 139
 140 /* Saved X11 local (client) display. */
 141 static char *x11_saved_display = NULL;
 142
 143 /* Saved X11 authentication protocol name. */
 144 static char *x11_saved_proto = NULL;
 145
 146 /* Saved X11 authentication data.  This is the real data. */
 147 static char *x11_saved_data = NULL;
 148 static u_int x11_saved_data_len = 0;
 149
 150 /*
 151  * Fake X11 authentication data.  This is what the server will be sending us;
 152  * we should replace any occurrences of this by the real data.
 153  */
 154 static u_char *x11_fake_data = NULL;
 155 static u_int x11_fake_data_len;
 156
 157
 158 /* -- agent forwarding */
 159
 160 #define NUM_SOCKS       10
 161
 162 /* AF_UNSPEC or AF_INET or AF_INET6 */
 163 static int IPv4or6 = AF_UNSPEC;
 164
 165 /* helper */
 166 static void port_open_helper(Channel *c, char *rtype);
 167
 168 /* non-blocking connect helpers */
 169 static int connect_next(struct channel_connect *);
 170 static void channel_connect_ctx_free(struct channel_connect *);
 171
 172 /* -- channel core */
 173
 174 Channel *
 175 channel_by_id(int id)
 176 {
 177         Channel *c;
 178
 179         if (id < 0 || (u_int)id >= channels_alloc) {
 180                 logit("channel_by_id: %d: bad id", id);
 181                 return NULL;
 182         }
 183         c = channels[id];
 184         if (c == NULL) {
 185                 logit("channel_by_id: %d: bad id: channel free", id);
 186                 return NULL;
 187         }
 188         return c;
 189 }
 190
 191 /*
 192  * Returns the channel if it is allowed to receive protocol messages.
 193  * Private channels, like listening sockets, may not receive messages.
 194  */
 195 Channel *
 196 channel_lookup(int id)
 197 {
 198         Channel *c;
 199
 200         if ((c = channel_by_id(id)) == NULL)
 201                 return (NULL);
 202
 203         switch (c->type) {
 204         case SSH_CHANNEL_X11_OPEN:
 205         case SSH_CHANNEL_LARVAL:
 206         case SSH_CHANNEL_CONNECTING:
 207         case SSH_CHANNEL_DYNAMIC:
 208         case SSH_CHANNEL_OPENING:
 209         case SSH_CHANNEL_OPEN:
 210         case SSH_CHANNEL_INPUT_DRAINING:
 211         case SSH_CHANNEL_OUTPUT_DRAINING:
 212                 return (c);
 213         }
 214         logit("Non-public channel %d, type %d.", id, c->type);
 215         return (NULL);
 216 }
 217
 218 /*
 219  * Register filedescriptors for a channel, used when allocating a channel or
 220  * when the channel consumer/producer is ready, e.g. shell exec'd
 221  */
 222 static void
 223 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 224     int extusage, int nonblock)
 225 {
 226         /* Update the maximum file descriptor value. */
 227         channel_max_fd = MAX(channel_max_fd, rfd);
 228         channel_max_fd = MAX(channel_max_fd, wfd);
 229         channel_max_fd = MAX(channel_max_fd, efd);
 230
 231         /* XXX set close-on-exec -markus */
 232
 233         c->rfd = rfd;
 234         c->wfd = wfd;
 235         c->sock = (rfd == wfd) ? rfd : -1;
 236         c->ctl_fd = -1; /* XXX: set elsewhere */
 237         c->efd = efd;
 238         c->extended_usage = extusage;
 239
 240         /* XXX ugly hack: nonblock is only set by the server */
 241         if (nonblock && isatty(c->rfd)) {
 242                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 243                 c->isatty = 1;
 244                 if (!isatty(c->wfd)) {
 245                         error("channel %d: wfd %d is not a tty?",
 246                             c->self, c->wfd);
 247                 }
 248         } else {
 249                 c->isatty = 0;
 250         }
 251         c->wfd_isatty = isatty(c->wfd);
 252
 253         /* enable nonblocking mode */
 254         if (nonblock) {
 255                 if (rfd != -1)
 256                         set_nonblock(rfd);
 257                 if (wfd != -1)
 258                         set_nonblock(wfd);
 259                 if (efd != -1)
 260                         set_nonblock(efd);
 261         }
 262 }
 263
 264 /*
 265  * Allocate a new channel object and set its type and socket. This will cause
 266  * remote_name to be freed.
 267  */
 268 Channel *
 269 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 270     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 271 {
 272         int found;
 273         u_int i;
 274         Channel *c;
 275
 276         /* Do initial allocation if this is the first call. */
 277         if (channels_alloc == 0) {
 278                 channels_alloc = 10;
 279                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 280                 for (i = 0; i < channels_alloc; i++)
 281                         channels[i] = NULL;
 282         }
 283         /* Try to find a free slot where to put the new channel. */
 284         for (found = -1, i = 0; i < channels_alloc; i++)
 285                 if (channels[i] == NULL) {
 286                         /* Found a free slot. */
 287                         found = (int)i;
 288                         break;
 289                 }
 290         if (found < 0) {
 291                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 292                 found = channels_alloc;
 293                 if (channels_alloc > 10000)
 294                         fatal("channel_new: internal error: channels_alloc %d "
 295                             "too big.", channels_alloc);
 296                 channels = xrealloc(channels, channels_alloc + 10,
 297                     sizeof(Channel *));
 298                 channels_alloc += 10;
 299                 debug2("channel: expanding %d", channels_alloc);
 300                 for (i = found; i < channels_alloc; i++)
 301                         channels[i] = NULL;
 302         }
 303         /* Initialize and return new channel. */
 304         c = channels[found] = xcalloc(1, sizeof(Channel));
 305         buffer_init(&c->input);
 306         buffer_init(&c->output);
 307         buffer_init(&c->extended);
 308         c->ostate = CHAN_OUTPUT_OPEN;
 309         c->istate = CHAN_INPUT_OPEN;
 310         c->flags = 0;
 311         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 312         c->self = found;
 313         c->type = type;
 314         c->ctype = ctype;
 315         c->local_window = window;
 316         c->local_window_max = window;
 317         c->local_consumed = 0;
 318         c->local_maxpacket = maxpack;
 319         c->remote_id = -1;
 320         c->remote_name = xstrdup(remote_name);
 321         c->remote_window = 0;
 322         c->remote_maxpacket = 0;
 323         c->force_drain = 0;
 324         c->single_connection = 0;
 325         c->detach_user = NULL;
 326         c->detach_close = 0;
 327         c->open_confirm = NULL;
 328         c->open_confirm_ctx = NULL;
 329         c->input_filter = NULL;
 330         c->output_filter = NULL;
 331         c->filter_ctx = NULL;
 332         c->filter_cleanup = NULL;
 333         TAILQ_INIT(&c->status_confirms);
 334         debug("channel %d: new [%s]", found, remote_name);
 335         return c;
 336 }
 337
 338 static int
 339 channel_find_maxfd(void)
 340 {
 341         u_int i;
 342         int max = 0;
 343         Channel *c;
 344
 345         for (i = 0; i < channels_alloc; i++) {
 346                 c = channels[i];
 347                 if (c != NULL) {
 348                         max = MAX(max, c->rfd);
 349                         max = MAX(max, c->wfd);
 350                         max = MAX(max, c->efd);
 351                 }
 352         }
 353         return max;
 354 }
 355
 356 int
 357 channel_close_fd(int *fdp)
 358 {
 359         int ret = 0, fd = *fdp;
 360
 361         if (fd != -1) {
 362                 ret = close(fd);
 363                 *fdp = -1;
 364                 if (fd == channel_max_fd)
 365                         channel_max_fd = channel_find_maxfd();
 366         }
 367         return ret;
 368 }
 369
 370 /* Close all channel fd/socket. */
 371 static void
 372 channel_close_fds(Channel *c)
 373 {
 374         debug3("channel %d: close_fds r %d w %d e %d c %d",
 375             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 376
 377         channel_close_fd(&c->sock);
 378         channel_close_fd(&c->ctl_fd);
 379         channel_close_fd(&c->rfd);
 380         channel_close_fd(&c->wfd);
 381         channel_close_fd(&c->efd);
 382 }
 383
 384 /* Free the channel and close its fd/socket. */
 385 void
 386 channel_free(Channel *c)
 387 {
 388         char *s;
 389         u_int i, n;
 390         struct channel_confirm *cc;
 391
 392         for (n = 0, i = 0; i < channels_alloc; i++)
 393                 if (channels[i])
 394                         n++;
 395         debug("channel %d: free: %s, nchannels %u", c->self,
 396             c->remote_name ? c->remote_name : "???", n);
 397
 398         s = channel_open_message();
 399         debug3("channel %d: status: %s", c->self, s);
 400         xfree(s);
 401
 402         if (c->sock != -1)
 403                 shutdown(c->sock, SHUT_RDWR);
 404         if (c->ctl_fd != -1)
 405                 shutdown(c->ctl_fd, SHUT_RDWR);
 406         channel_close_fds(c);
 407         buffer_free(&c->input);
 408         buffer_free(&c->output);
 409         buffer_free(&c->extended);
 410         if (c->remote_name) {
 411                 xfree(c->remote_name);
 412                 c->remote_name = NULL;
 413         }
 414         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 415                 if (cc->abandon_cb != NULL)
 416                         cc->abandon_cb(c, cc->ctx);
 417                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 418                 bzero(cc, sizeof(*cc));
 419                 xfree(cc);
 420         }
 421         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 422                 c->filter_cleanup(c->self, c->filter_ctx);
 423         channels[c->self] = NULL;
 424         xfree(c);
 425 }
 426
 427 void
 428 channel_free_all(void)
 429 {
 430         u_int i;
 431
 432         for (i = 0; i < channels_alloc; i++)
 433                 if (channels[i] != NULL)
 434                         channel_free(channels[i]);
 435 }
 436
 437 /*
 438  * Closes the sockets/fds of all channels.  This is used to close extra file
 439  * descriptors after a fork.
 440  */
 441 void
 442 channel_close_all(void)
 443 {
 444         u_int i;
 445
 446         for (i = 0; i < channels_alloc; i++)
 447                 if (channels[i] != NULL)
 448                         channel_close_fds(channels[i]);
 449 }
 450
 451 /*
 452  * Stop listening to channels.
 453  */
 454 void
 455 channel_stop_listening(void)
 456 {
 457         u_int i;
 458         Channel *c;
 459
 460         for (i = 0; i < channels_alloc; i++) {
 461                 c = channels[i];
 462                 if (c != NULL) {
 463                         switch (c->type) {
 464                         case SSH_CHANNEL_AUTH_SOCKET:
 465                         case SSH_CHANNEL_PORT_LISTENER:
 466                         case SSH_CHANNEL_RPORT_LISTENER:
 467                         case SSH_CHANNEL_X11_LISTENER:
 468                                 channel_close_fd(&c->sock);
 469                                 channel_free(c);
 470                                 break;
 471                         }
 472                 }
 473         }
 474 }
 475
 476 /*
 477  * Returns true if no channel has too much buffered data, and false if one or
 478  * more channel is overfull.
 479  */
 480 int
 481 channel_not_very_much_buffered_data(void)
 482 {
 483         u_int i;
 484         Channel *c;
 485
 486         for (i = 0; i < channels_alloc; i++) {
 487                 c = channels[i];
 488                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 489 #if 0
 490                         if (!compat20 &&
 491                             buffer_len(&c->input) > packet_get_maxsize()) {
 492                                 debug2("channel %d: big input buffer %d",
 493                                     c->self, buffer_len(&c->input));
 494                                 return 0;
 495                         }
 496 #endif
 497                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 498                                 debug2("channel %d: big output buffer %u > %u",
 499                                     c->self, buffer_len(&c->output),
 500                                     packet_get_maxsize());
 501                                 return 0;
 502                         }
 503                 }
 504         }
 505         return 1;
 506 }
 507
 508 /* Returns true if any channel is still open. */
 509 int
 510 channel_still_open(void)
 511 {
 512         u_int i;
 513         Channel *c;
 514
 515         for (i = 0; i < channels_alloc; i++) {
 516                 c = channels[i];
 517                 if (c == NULL)
 518                         continue;
 519                 switch (c->type) {
 520                 case SSH_CHANNEL_X11_LISTENER:
 521                 case SSH_CHANNEL_PORT_LISTENER:
 522                 case SSH_CHANNEL_RPORT_LISTENER:
 523                 case SSH_CHANNEL_CLOSED:
 524                 case SSH_CHANNEL_AUTH_SOCKET:
 525                 case SSH_CHANNEL_DYNAMIC:
 526                 case SSH_CHANNEL_CONNECTING:
 527                 case SSH_CHANNEL_ZOMBIE:
 528                         continue;
 529                 case SSH_CHANNEL_LARVAL:
 530                         if (!compat20)
 531                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 532                         continue;
 533                 case SSH_CHANNEL_OPENING:
 534                 case SSH_CHANNEL_OPEN:
 535                 case SSH_CHANNEL_X11_OPEN:
 536                         return 1;
 537                 case SSH_CHANNEL_INPUT_DRAINING:
 538                 case SSH_CHANNEL_OUTPUT_DRAINING:
 539                         if (!compat13)
 540                                 fatal("cannot happen: OUT_DRAIN");
 541                         return 1;
 542                 default:
 543                         fatal("channel_still_open: bad channel type %d", c->type);
 544                         /* NOTREACHED */
 545                 }
 546         }
 547         return 0;
 548 }
 549
 550 /* Returns the id of an open channel suitable for keepaliving */
 551 int
 552 channel_find_open(void)
 553 {
 554         u_int i;
 555         Channel *c;
 556
 557         for (i = 0; i < channels_alloc; i++) {
 558                 c = channels[i];
 559                 if (c == NULL || c->remote_id < 0)
 560                         continue;
 561                 switch (c->type) {
 562                 case SSH_CHANNEL_CLOSED:
 563                 case SSH_CHANNEL_DYNAMIC:
 564                 case SSH_CHANNEL_X11_LISTENER:
 565                 case SSH_CHANNEL_PORT_LISTENER:
 566                 case SSH_CHANNEL_RPORT_LISTENER:
 567                 case SSH_CHANNEL_OPENING:
 568                 case SSH_CHANNEL_CONNECTING:
 569                 case SSH_CHANNEL_ZOMBIE:
 570                         continue;
 571                 case SSH_CHANNEL_LARVAL:
 572                 case SSH_CHANNEL_AUTH_SOCKET:
 573                 case SSH_CHANNEL_OPEN:
 574                 case SSH_CHANNEL_X11_OPEN:
 575                         return i;
 576                 case SSH_CHANNEL_INPUT_DRAINING:
 577                 case SSH_CHANNEL_OUTPUT_DRAINING:
 578                         if (!compat13)
 579                                 fatal("cannot happen: OUT_DRAIN");
 580                         return i;
 581                 default:
 582                         fatal("channel_find_open: bad channel type %d", c->type);
 583                         /* NOTREACHED */
 584                 }
 585         }
 586         return -1;
 587 }
 588
 589
 590 /*
 591  * Returns a message describing the currently open forwarded connections,
 592  * suitable for sending to the client.  The message contains crlf pairs for
 593  * newlines.
 594  */
 595 char *
 596 channel_open_message(void)
 597 {
 598         Buffer buffer;
 599         Channel *c;
 600         char buf[1024], *cp;
 601         u_int i;
 602
 603         buffer_init(&buffer);
 604         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 605         buffer_append(&buffer, buf, strlen(buf));
 606         for (i = 0; i < channels_alloc; i++) {
 607                 c = channels[i];
 608                 if (c == NULL)
 609                         continue;
 610                 switch (c->type) {
 611                 case SSH_CHANNEL_X11_LISTENER:
 612                 case SSH_CHANNEL_PORT_LISTENER:
 613                 case SSH_CHANNEL_RPORT_LISTENER:
 614                 case SSH_CHANNEL_CLOSED:
 615                 case SSH_CHANNEL_AUTH_SOCKET:
 616                 case SSH_CHANNEL_ZOMBIE:
 617                         continue;
 618                 case SSH_CHANNEL_LARVAL:
 619                 case SSH_CHANNEL_OPENING:
 620                 case SSH_CHANNEL_CONNECTING:
 621                 case SSH_CHANNEL_DYNAMIC:
 622                 case SSH_CHANNEL_OPEN:
 623                 case SSH_CHANNEL_X11_OPEN:
 624                 case SSH_CHANNEL_INPUT_DRAINING:
 625                 case SSH_CHANNEL_OUTPUT_DRAINING:
 626                         snprintf(buf, sizeof buf,
 627                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 628                             c->self, c->remote_name,
 629                             c->type, c->remote_id,
 630                             c->istate, buffer_len(&c->input),
 631                             c->ostate, buffer_len(&c->output),
 632                             c->rfd, c->wfd, c->ctl_fd);
 633                         buffer_append(&buffer, buf, strlen(buf));
 634                         continue;
 635                 default:
 636                         fatal("channel_open_message: bad channel type %d", c->type);
 637                         /* NOTREACHED */
 638                 }
 639         }
 640         buffer_append(&buffer, "\0", 1);
 641         cp = xstrdup(buffer_ptr(&buffer));
 642         buffer_free(&buffer);
 643         return cp;
 644 }
 645
 646 void
 647 channel_send_open(int id)
 648 {
 649         Channel *c = channel_lookup(id);
 650
 651         if (c == NULL) {
 652                 logit("channel_send_open: %d: bad id", id);
 653                 return;
 654         }
 655         debug2("channel %d: send open", id);
 656         packet_start(SSH2_MSG_CHANNEL_OPEN);
 657         packet_put_cstring(c->ctype);
 658         packet_put_int(c->self);
 659         packet_put_int(c->local_window);
 660         packet_put_int(c->local_maxpacket);
 661         packet_send();
 662 }
 663
 664 void
 665 channel_request_start(int id, char *service, int wantconfirm)
 666 {
 667         Channel *c = channel_lookup(id);
 668
 669         if (c == NULL) {
 670                 logit("channel_request_start: %d: unknown channel id", id);
 671                 return;
 672         }
 673         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 674         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 675         packet_put_int(c->remote_id);
 676         packet_put_cstring(service);
 677         packet_put_char(wantconfirm);
 678 }
 679
 680 void
 681 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 682     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 683 {
 684         struct channel_confirm *cc;
 685         Channel *c;
 686
 687         if ((c = channel_lookup(id)) == NULL)
 688                 fatal("channel_register_expect: %d: bad id", id);
 689
 690         cc = xmalloc(sizeof(*cc));
 691         cc->cb = cb;
 692         cc->abandon_cb = abandon_cb;
 693         cc->ctx = ctx;
 694         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 695 }
 696
 697 void
 698 channel_register_open_confirm(int id, channel_callback_fn *fn, void *ctx)
 699 {
 700         Channel *c = channel_lookup(id);
 701
 702         if (c == NULL) {
 703                 logit("channel_register_open_comfirm: %d: bad id", id);
 704                 return;
 705         }
 706         c->open_confirm = fn;
 707         c->open_confirm_ctx = ctx;
 708 }
 709
 710 void
 711 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 712 {
 713         Channel *c = channel_by_id(id);
 714
 715         if (c == NULL) {
 716                 logit("channel_register_cleanup: %d: bad id", id);
 717                 return;
 718         }
 719         c->detach_user = fn;
 720         c->detach_close = do_close;
 721 }
 722
 723 void
 724 channel_cancel_cleanup(int id)
 725 {
 726         Channel *c = channel_by_id(id);
 727
 728         if (c == NULL) {
 729                 logit("channel_cancel_cleanup: %d: bad id", id);
 730                 return;
 731         }
 732         c->detach_user = NULL;
 733         c->detach_close = 0;
 734 }
 735
 736 void
 737 channel_register_filter(int id, channel_infilter_fn *ifn,
 738     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 739 {
 740         Channel *c = channel_lookup(id);
 741
 742         if (c == NULL) {
 743                 logit("channel_register_filter: %d: bad id", id);
 744                 return;
 745         }
 746         c->input_filter = ifn;
 747         c->output_filter = ofn;
 748         c->filter_ctx = ctx;
 749         c->filter_cleanup = cfn;
 750 }
 751
 752 void
 753 channel_set_fds(int id, int rfd, int wfd, int efd,
 754     int extusage, int nonblock, u_int window_max)
 755 {
 756         Channel *c = channel_lookup(id);
 757
 758         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 759                 fatal("channel_activate for non-larval channel %d.", id);
 760         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
 761         c->type = SSH_CHANNEL_OPEN;
 762         c->local_window = c->local_window_max = window_max;
 763         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 764         packet_put_int(c->remote_id);
 765         packet_put_int(c->local_window);
 766         packet_send();
 767 }
 768
 769 /*
 770  * 'channel_pre*' are called just before select() to add any bits relevant to
 771  * channels in the select bitmasks.
 772  */
 773 /*
 774  * 'channel_post*': perform any appropriate operations for channels which
 775  * have events pending.
 776  */
 777 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 778 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 779 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 780
 781 /* ARGSUSED */
 782 static void
 783 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 784 {
 785         FD_SET(c->sock, readset);
 786 }
 787
 788 /* ARGSUSED */
 789 static void
 790 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 791 {
 792         debug3("channel %d: waiting for connection", c->self);
 793         FD_SET(c->sock, writeset);
 794 }
 795
 796 static void
 797 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 798 {
 799         if (buffer_len(&c->input) < packet_get_maxsize())
 800                 FD_SET(c->sock, readset);
 801         if (buffer_len(&c->output) > 0)
 802                 FD_SET(c->sock, writeset);
 803 }
 804
 805 static void
 806 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 807 {
 808         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 809
 810         if (c->istate == CHAN_INPUT_OPEN &&
 811             limit > 0 &&
 812             buffer_len(&c->input) < limit &&
 813             buffer_check_alloc(&c->input, CHAN_RBUF))
 814                 FD_SET(c->rfd, readset);
 815         if (c->ostate == CHAN_OUTPUT_OPEN ||
 816             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 817                 if (buffer_len(&c->output) > 0) {
 818                         FD_SET(c->wfd, writeset);
 819                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 820                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 821                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 822                                     c->self, c->efd, buffer_len(&c->extended));
 823                         else
 824                                 chan_obuf_empty(c);
 825                 }
 826         }
 827         /** XXX check close conditions, too */
 828         if (compat20 && c->efd != -1 &&
 829             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 830                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 831                     buffer_len(&c->extended) > 0)
 832                         FD_SET(c->efd, writeset);
 833                 else if (!(c->flags & CHAN_EOF_SENT) &&
 834                     c->extended_usage == CHAN_EXTENDED_READ &&
 835                     buffer_len(&c->extended) < c->remote_window)
 836                         FD_SET(c->efd, readset);
 837         }
 838         /* XXX: What about efd? races? */
 839         if (compat20 && c->ctl_fd != -1 &&
 840             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 841                 FD_SET(c->ctl_fd, readset);
 842 }
 843
 844 /* ARGSUSED */
 845 static void
 846 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 847 {
 848         if (buffer_len(&c->input) == 0) {
 849                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 850                 packet_put_int(c->remote_id);
 851                 packet_send();
 852                 c->type = SSH_CHANNEL_CLOSED;
 853                 debug2("channel %d: closing after input drain.", c->self);
 854         }
 855 }
 856
 857 /* ARGSUSED */
 858 static void
 859 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 860 {
 861         if (buffer_len(&c->output) == 0)
 862                 chan_mark_dead(c);
 863         else
 864                 FD_SET(c->sock, writeset);
 865 }
 866
 867 /*
 868  * This is a special state for X11 authentication spoofing.  An opened X11
 869  * connection (when authentication spoofing is being done) remains in this
 870  * state until the first packet has been completely read.  The authentication
 871  * data in that packet is then substituted by the real data if it matches the
 872  * fake data, and the channel is put into normal mode.
 873  * XXX All this happens at the client side.
 874  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 875  */
 876 static int
 877 x11_open_helper(Buffer *b)
 878 {
 879         u_char *ucp;
 880         u_int proto_len, data_len;
 881
 882         /* Check if the fixed size part of the packet is in buffer. */
 883         if (buffer_len(b) < 12)
 884                 return 0;
 885
 886         /* Parse the lengths of variable-length fields. */
 887         ucp = buffer_ptr(b);
 888         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 889                 proto_len = 256 * ucp[6] + ucp[7];
 890                 data_len = 256 * ucp[8] + ucp[9];
 891         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 892                 proto_len = ucp[6] + 256 * ucp[7];
 893                 data_len = ucp[8] + 256 * ucp[9];
 894         } else {
 895                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 896                     ucp[0]);
 897                 return -1;
 898         }
 899
 900         /* Check if the whole packet is in buffer. */
 901         if (buffer_len(b) <
 902             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 903                 return 0;
 904
 905         /* Check if authentication protocol matches. */
 906         if (proto_len != strlen(x11_saved_proto) ||
 907             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 908                 debug2("X11 connection uses different authentication protocol.");
 909                 return -1;
 910         }
 911         /* Check if authentication data matches our fake data. */
 912         if (data_len != x11_fake_data_len ||
 913             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 914                 x11_fake_data, x11_fake_data_len) != 0) {
 915                 debug2("X11 auth data does not match fake data.");
 916                 return -1;
 917         }
 918         /* Check fake data length */
 919         if (x11_fake_data_len != x11_saved_data_len) {
 920                 error("X11 fake_data_len %d != saved_data_len %d",
 921                     x11_fake_data_len, x11_saved_data_len);
 922                 return -1;
 923         }
 924         /*
 925          * Received authentication protocol and data match
 926          * our fake data. Substitute the fake data with real
 927          * data.
 928          */
 929         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 930             x11_saved_data, x11_saved_data_len);
 931         return 1;
 932 }
 933
 934 static void
 935 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 936 {
 937         int ret = x11_open_helper(&c->output);
 938
 939         if (ret == 1) {
 940                 /* Start normal processing for the channel. */
 941                 c->type = SSH_CHANNEL_OPEN;
 942                 channel_pre_open_13(c, readset, writeset);
 943         } else if (ret == -1) {
 944                 /*
 945                  * We have received an X11 connection that has bad
 946                  * authentication information.
 947                  */
 948                 logit("X11 connection rejected because of wrong authentication.");
 949                 buffer_clear(&c->input);
 950                 buffer_clear(&c->output);
 951                 channel_close_fd(&c->sock);
 952                 c->sock = -1;
 953                 c->type = SSH_CHANNEL_CLOSED;
 954                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 955                 packet_put_int(c->remote_id);
 956                 packet_send();
 957         }
 958 }
 959
 960 static void
 961 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 962 {
 963         int ret = x11_open_helper(&c->output);
 964
 965         /* c->force_drain = 1; */
 966
 967         if (ret == 1) {
 968                 c->type = SSH_CHANNEL_OPEN;
 969                 channel_pre_open(c, readset, writeset);
 970         } else if (ret == -1) {
 971                 logit("X11 connection rejected because of wrong authentication.");
 972                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 973                 chan_read_failed(c);
 974                 buffer_clear(&c->input);
 975                 chan_ibuf_empty(c);
 976                 buffer_clear(&c->output);
 977                 /* for proto v1, the peer will send an IEOF */
 978                 if (compat20)
 979                         chan_write_failed(c);
 980                 else
 981                         c->type = SSH_CHANNEL_OPEN;
 982                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 983         }
 984 }
 985
 986 /* try to decode a socks4 header */
 987 /* ARGSUSED */
 988 static int
 989 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 990 {
 991         char *p, *host;
 992         u_int len, have, i, found;
 993         char username[256];
 994         struct {
 995                 u_int8_t version;
 996                 u_int8_t command;
 997                 u_int16_t dest_port;
 998                 struct in_addr dest_addr;
 999         } s4_req, s4_rsp;
1000
1001         debug2("channel %d: decode socks4", c->self);
1002
1003         have = buffer_len(&c->input);
1004         len = sizeof(s4_req);
1005         if (have < len)
1006                 return 0;
1007         p = buffer_ptr(&c->input);
1008         for (found = 0, i = len; i < have; i++) {
1009                 if (p[i] == '\0') {
1010                         found = 1;
1011                         break;
1012                 }
1013                 if (i > 1024) {
1014                         /* the peer is probably sending garbage */
1015                         debug("channel %d: decode socks4: too long",
1016                             c->self);
1017                         return -1;
1018                 }
1019         }
1020         if (!found)
1021                 return 0;
1022         buffer_get(&c->input, (char *)&s4_req.version, 1);
1023         buffer_get(&c->input, (char *)&s4_req.command, 1);
1024         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1025         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1026         have = buffer_len(&c->input);
1027         p = buffer_ptr(&c->input);
1028         len = strlen(p);
1029         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1030         if (len > have)
1031                 fatal("channel %d: decode socks4: len %d > have %d",
1032                     c->self, len, have);
1033         strlcpy(username, p, sizeof(username));
1034         buffer_consume(&c->input, len);
1035         buffer_consume(&c->input, 1);           /* trailing '\0' */
1036
1037         host = inet_ntoa(s4_req.dest_addr);
1038         strlcpy(c->path, host, sizeof(c->path));
1039         c->host_port = ntohs(s4_req.dest_port);
1040
1041         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1042             c->self, host, c->host_port, s4_req.command);
1043
1044         if (s4_req.command != 1) {
1045                 debug("channel %d: cannot handle: socks4 cn %d",
1046                     c->self, s4_req.command);
1047                 return -1;
1048         }
1049         s4_rsp.version = 0;                     /* vn: 0 for reply */
1050         s4_rsp.command = 90;                    /* cd: req granted */
1051         s4_rsp.dest_port = 0;                   /* ignored */
1052         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1053         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1054         return 1;
1055 }
1056
1057 /* try to decode a socks5 header */
1058 #define SSH_SOCKS5_AUTHDONE     0x1000
1059 #define SSH_SOCKS5_NOAUTH       0x00
1060 #define SSH_SOCKS5_IPV4         0x01
1061 #define SSH_SOCKS5_DOMAIN       0x03
1062 #define SSH_SOCKS5_IPV6         0x04
1063 #define SSH_SOCKS5_CONNECT      0x01
1064 #define SSH_SOCKS5_SUCCESS      0x00
1065
1066 /* ARGSUSED */
1067 static int
1068 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1069 {
1070         struct {
1071                 u_int8_t version;
1072                 u_int8_t command;
1073                 u_int8_t reserved;
1074                 u_int8_t atyp;
1075         } s5_req, s5_rsp;
1076         u_int16_t dest_port;
1077         u_char *p, dest_addr[255+1];
1078         u_int have, need, i, found, nmethods, addrlen, af;
1079
1080         debug2("channel %d: decode socks5", c->self);
1081         p = buffer_ptr(&c->input);
1082         if (p[0] != 0x05)
1083                 return -1;
1084         have = buffer_len(&c->input);
1085         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1086                 /* format: ver | nmethods | methods */
1087                 if (have < 2)
1088                         return 0;
1089                 nmethods = p[1];
1090                 if (have < nmethods + 2)
1091                         return 0;
1092                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1093                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1094                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1095                                 found = 1;
1096                                 break;
1097                         }
1098                 }
1099                 if (!found) {
1100                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1101                             c->self);
1102                         return -1;
1103                 }
1104                 buffer_consume(&c->input, nmethods + 2);
1105                 buffer_put_char(&c->output, 0x05);              /* version */
1106                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1107                 FD_SET(c->sock, writeset);
1108                 c->flags |= SSH_SOCKS5_AUTHDONE;
1109                 debug2("channel %d: socks5 auth done", c->self);
1110                 return 0;                               /* need more */
1111         }
1112         debug2("channel %d: socks5 post auth", c->self);
1113         if (have < sizeof(s5_req)+1)
1114                 return 0;                       /* need more */
1115         memcpy(&s5_req, p, sizeof(s5_req));
1116         if (s5_req.version != 0x05 ||
1117             s5_req.command != SSH_SOCKS5_CONNECT ||
1118             s5_req.reserved != 0x00) {
1119                 debug2("channel %d: only socks5 connect supported", c->self);
1120                 return -1;
1121         }
1122         switch (s5_req.atyp){
1123         case SSH_SOCKS5_IPV4:
1124                 addrlen = 4;
1125                 af = AF_INET;
1126                 break;
1127         case SSH_SOCKS5_DOMAIN:
1128                 addrlen = p[sizeof(s5_req)];
1129                 af = -1;
1130                 break;
1131         case SSH_SOCKS5_IPV6:
1132                 addrlen = 16;
1133                 af = AF_INET6;
1134                 break;
1135         default:
1136                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1137                 return -1;
1138         }
1139         need = sizeof(s5_req) + addrlen + 2;
1140         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1141                 need++;
1142         if (have < need)
1143                 return 0;
1144         buffer_consume(&c->input, sizeof(s5_req));
1145         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1146                 buffer_consume(&c->input, 1);    /* host string length */
1147         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1148         buffer_get(&c->input, (char *)&dest_port, 2);
1149         dest_addr[addrlen] = '\0';
1150         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1151                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1152         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1153                 return -1;
1154         c->host_port = ntohs(dest_port);
1155
1156         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1157             c->self, c->path, c->host_port, s5_req.command);
1158
1159         s5_rsp.version = 0x05;
1160         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1161         s5_rsp.reserved = 0;                    /* ignored */
1162         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1163         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1164         dest_port = 0;                          /* ignored */
1165
1166         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1167         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1168         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1169         return 1;
1170 }
1171
1172 /* dynamic port forwarding */
1173 static void
1174 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1175 {
1176         u_char *p;
1177         u_int have;
1178         int ret;
1179
1180         have = buffer_len(&c->input);
1181         c->delayed = 0;
1182         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1183         /* buffer_dump(&c->input); */
1184         /* check if the fixed size part of the packet is in buffer. */
1185         if (have < 3) {
1186                 /* need more */
1187                 FD_SET(c->sock, readset);
1188                 return;
1189         }
1190         /* try to guess the protocol */
1191         p = buffer_ptr(&c->input);
1192         switch (p[0]) {
1193         case 0x04:
1194                 ret = channel_decode_socks4(c, readset, writeset);
1195                 break;
1196         case 0x05:
1197                 ret = channel_decode_socks5(c, readset, writeset);
1198                 break;
1199         default:
1200                 ret = -1;
1201                 break;
1202         }
1203         if (ret < 0) {
1204                 chan_mark_dead(c);
1205         } else if (ret == 0) {
1206                 debug2("channel %d: pre_dynamic: need more", c->self);
1207                 /* need more */
1208                 FD_SET(c->sock, readset);
1209         } else {
1210                 /* switch to the next state */
1211                 c->type = SSH_CHANNEL_OPENING;
1212                 port_open_helper(c, "direct-tcpip");
1213         }
1214 }
1215
1216 /* This is our fake X11 server socket. */
1217 /* ARGSUSED */
1218 static void
1219 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1220 {
1221         Channel *nc;
1222         struct sockaddr addr;
1223         int newsock;
1224         socklen_t addrlen;
1225         char buf[16384], *remote_ipaddr;
1226         int remote_port;
1227
1228         if (FD_ISSET(c->sock, readset)) {
1229                 debug("X11 connection requested.");
1230                 addrlen = sizeof(addr);
1231                 newsock = accept(c->sock, &addr, &addrlen);
1232                 if (c->single_connection) {
1233                         debug2("single_connection: closing X11 listener.");
1234                         channel_close_fd(&c->sock);
1235                         chan_mark_dead(c);
1236                 }
1237                 if (newsock < 0) {
1238                         error("accept: %.100s", strerror(errno));
1239                         return;
1240                 }
1241                 set_nodelay(newsock);
1242                 remote_ipaddr = get_peer_ipaddr(newsock);
1243                 remote_port = get_peer_port(newsock);
1244                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1245                     remote_ipaddr, remote_port);
1246
1247                 nc = channel_new("accepted x11 socket",
1248                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1249                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1250                 if (compat20) {
1251                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1252                         packet_put_cstring("x11");
1253                         packet_put_int(nc->self);
1254                         packet_put_int(nc->local_window_max);
1255                         packet_put_int(nc->local_maxpacket);
1256                         /* originator ipaddr and port */
1257                         packet_put_cstring(remote_ipaddr);
1258                         if (datafellows & SSH_BUG_X11FWD) {
1259                                 debug2("ssh2 x11 bug compat mode");
1260                         } else {
1261                                 packet_put_int(remote_port);
1262                         }
1263                         packet_send();
1264                 } else {
1265                         packet_start(SSH_SMSG_X11_OPEN);
1266                         packet_put_int(nc->self);
1267                         if (packet_get_protocol_flags() &
1268                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1269                                 packet_put_cstring(buf);
1270                         packet_send();
1271                 }
1272                 xfree(remote_ipaddr);
1273         }
1274 }
1275
1276 static void
1277 port_open_helper(Channel *c, char *rtype)
1278 {
1279         int direct;
1280         char buf[1024];
1281         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1282         int remote_port = get_peer_port(c->sock);
1283
1284         direct = (strcmp(rtype, "direct-tcpip") == 0);
1285
1286         snprintf(buf, sizeof buf,
1287             "%s: listening port %d for %.100s port %d, "
1288             "connect from %.200s port %d",
1289             rtype, c->listening_port, c->path, c->host_port,
1290             remote_ipaddr, remote_port);
1291
1292         xfree(c->remote_name);
1293         c->remote_name = xstrdup(buf);
1294
1295         if (compat20) {
1296                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1297                 packet_put_cstring(rtype);
1298                 packet_put_int(c->self);
1299                 packet_put_int(c->local_window_max);
1300                 packet_put_int(c->local_maxpacket);
1301                 if (direct) {
1302                         /* target host, port */
1303                         packet_put_cstring(c->path);
1304                         packet_put_int(c->host_port);
1305                 } else {
1306                         /* listen address, port */
1307                         packet_put_cstring(c->path);
1308                         packet_put_int(c->listening_port);
1309                 }
1310                 /* originator host and port */
1311                 packet_put_cstring(remote_ipaddr);
1312                 packet_put_int((u_int)remote_port);
1313                 packet_send();
1314         } else {
1315                 packet_start(SSH_MSG_PORT_OPEN);
1316                 packet_put_int(c->self);
1317                 packet_put_cstring(c->path);
1318                 packet_put_int(c->host_port);
1319                 if (packet_get_protocol_flags() &
1320                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1321                         packet_put_cstring(c->remote_name);
1322                 packet_send();
1323         }
1324         xfree(remote_ipaddr);
1325 }
1326
1327 static void
1328 channel_set_reuseaddr(int fd)
1329 {
1330         int on = 1;
1331
1332         /*
1333          * Set socket options.
1334          * Allow local port reuse in TIME_WAIT.
1335          */
1336         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1337                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1338 }
1339
1340 /*
1341  * This socket is listening for connections to a forwarded TCP/IP port.
1342  */
1343 /* ARGSUSED */
1344 static void
1345 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1346 {
1347         Channel *nc;
1348         struct sockaddr addr;
1349         int newsock, nextstate;
1350         socklen_t addrlen;
1351         char *rtype;
1352
1353         if (FD_ISSET(c->sock, readset)) {
1354                 debug("Connection to port %d forwarding "
1355                     "to %.100s port %d requested.",
1356                     c->listening_port, c->path, c->host_port);
1357
1358                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1359                         nextstate = SSH_CHANNEL_OPENING;
1360                         rtype = "forwarded-tcpip";
1361                 } else {
1362                         if (c->host_port == 0) {
1363                                 nextstate = SSH_CHANNEL_DYNAMIC;
1364                                 rtype = "dynamic-tcpip";
1365                         } else {
1366                                 nextstate = SSH_CHANNEL_OPENING;
1367                                 rtype = "direct-tcpip";
1368                         }
1369                 }
1370
1371                 addrlen = sizeof(addr);
1372                 newsock = accept(c->sock, &addr, &addrlen);
1373                 if (newsock < 0) {
1374                         error("accept: %.100s", strerror(errno));
1375                         return;
1376                 }
1377                 set_nodelay(newsock);
1378                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1379                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1380                 nc->listening_port = c->listening_port;
1381                 nc->host_port = c->host_port;
1382                 strlcpy(nc->path, c->path, sizeof(nc->path));
1383
1384                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1385                         /*
1386                          * do not call the channel_post handler until
1387                          * this flag has been reset by a pre-handler.
1388                          * otherwise the FD_ISSET calls might overflow
1389                          */
1390                         nc->delayed = 1;
1391                 } else {
1392                         port_open_helper(nc, rtype);
1393                 }
1394         }
1395 }
1396
1397 /*
1398  * This is the authentication agent socket listening for connections from
1399  * clients.
1400  */
1401 /* ARGSUSED */
1402 static void
1403 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1404 {
1405         Channel *nc;
1406         int newsock;
1407         struct sockaddr addr;
1408         socklen_t addrlen;
1409
1410         if (FD_ISSET(c->sock, readset)) {
1411                 addrlen = sizeof(addr);
1412                 newsock = accept(c->sock, &addr, &addrlen);
1413                 if (newsock < 0) {
1414                         error("accept from auth socket: %.100s", strerror(errno));
1415                         return;
1416                 }
1417                 nc = channel_new("accepted auth socket",
1418                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1419                     c->local_window_max, c->local_maxpacket,
1420                     0, "accepted auth socket", 1);
1421                 if (compat20) {
1422                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1423                         packet_put_cstring("auth-agent@openssh.com");
1424                         packet_put_int(nc->self);
1425                         packet_put_int(c->local_window_max);
1426                         packet_put_int(c->local_maxpacket);
1427                 } else {
1428                         packet_start(SSH_SMSG_AGENT_OPEN);
1429                         packet_put_int(nc->self);
1430                 }
1431                 packet_send();
1432         }
1433 }
1434
1435 /* ARGSUSED */
1436 static void
1437 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1438 {
1439         int err = 0, sock;
1440         socklen_t sz = sizeof(err);
1441
1442         if (FD_ISSET(c->sock, writeset)) {
1443                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1444                         err = errno;
1445                         error("getsockopt SO_ERROR failed");
1446                 }
1447                 if (err == 0) {
1448                         debug("channel %d: connected to %s port %d",
1449                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1450                         channel_connect_ctx_free(&c->connect_ctx);
1451                         c->type = SSH_CHANNEL_OPEN;
1452                         if (compat20) {
1453                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1454                                 packet_put_int(c->remote_id);
1455                                 packet_put_int(c->self);
1456                                 packet_put_int(c->local_window);
1457                                 packet_put_int(c->local_maxpacket);
1458                         } else {
1459                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1460                                 packet_put_int(c->remote_id);
1461                                 packet_put_int(c->self);
1462                         }
1463                 } else {
1464                         debug("channel %d: connection failed: %s",
1465                             c->self, strerror(err));
1466                         /* Try next address, if any */
1467                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1468                                 close(c->sock);
1469                                 c->sock = c->rfd = c->wfd = sock;
1470                                 channel_max_fd = channel_find_maxfd();
1471                                 return;
1472                         }
1473                         /* Exhausted all addresses */
1474                         error("connect_to %.100s port %d: failed.",
1475                             c->connect_ctx.host, c->connect_ctx.port);
1476                         channel_connect_ctx_free(&c->connect_ctx);
1477                         if (compat20) {
1478                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1479                                 packet_put_int(c->remote_id);
1480                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1481                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1482                                         packet_put_cstring(strerror(err));
1483                                         packet_put_cstring("");
1484                                 }
1485                         } else {
1486                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1487                                 packet_put_int(c->remote_id);
1488                         }
1489                         chan_mark_dead(c);
1490                 }
1491                 packet_send();
1492         }
1493 }
1494
1495 /* ARGSUSED */
1496 static int
1497 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1498 {
1499         char buf[CHAN_RBUF];
1500         int len, force;
1501
1502         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1503         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1504                 errno = 0;
1505                 len = read(c->rfd, buf, sizeof(buf));
1506                 if (len < 0 && (errno == EINTR || (errno == EAGAIN && !force)))
1507                         return 1;
1508 #ifndef PTY_ZEROREAD
1509                 if (len <= 0) {
1510 #else
1511                 if ((!c->isatty && len <= 0) ||
1512                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1513 #endif
1514                         debug2("channel %d: read<=0 rfd %d len %d",
1515                             c->self, c->rfd, len);
1516                         if (c->type != SSH_CHANNEL_OPEN) {
1517                                 debug2("channel %d: not open", c->self);
1518                                 chan_mark_dead(c);
1519                                 return -1;
1520                         } else if (compat13) {
1521                                 buffer_clear(&c->output);
1522                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1523                                 debug2("channel %d: input draining.", c->self);
1524                         } else {
1525                                 chan_read_failed(c);
1526                         }
1527                         return -1;
1528                 }
1529                 if (c->input_filter != NULL) {
1530                         if (c->input_filter(c, buf, len) == -1) {
1531                                 debug2("channel %d: filter stops", c->self);
1532                                 chan_read_failed(c);
1533                         }
1534                 } else if (c->datagram) {
1535                         buffer_put_string(&c->input, buf, len);
1536                 } else {
1537                         buffer_append(&c->input, buf, len);
1538                 }
1539         }
1540         return 1;
1541 }
1542
1543 /* ARGSUSED */
1544 static int
1545 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1546 {
1547         struct termios tio;
1548         u_char *data = NULL, *buf;
1549         u_int dlen;
1550         int len;
1551
1552         /* Send buffered output data to the socket. */
1553         if (c->wfd != -1 &&
1554             FD_ISSET(c->wfd, writeset) &&
1555             buffer_len(&c->output) > 0) {
1556                 if (c->output_filter != NULL) {
1557                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1558                                 debug2("channel %d: filter stops", c->self);
1559                                 if (c->type != SSH_CHANNEL_OPEN)
1560                                         chan_mark_dead(c);
1561                                 else
1562                                         chan_write_failed(c);
1563                                 return -1;
1564                         }
1565                 } else if (c->datagram) {
1566                         buf = data = buffer_get_string(&c->output, &dlen);
1567                 } else {
1568                         buf = data = buffer_ptr(&c->output);
1569                         dlen = buffer_len(&c->output);
1570                 }
1571
1572                 if (c->datagram) {
1573                         /* ignore truncated writes, datagrams might get lost */
1574                         c->local_consumed += dlen + 4;
1575                         len = write(c->wfd, buf, dlen);
1576                         xfree(data);
1577                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1578                                 return 1;
1579                         if (len <= 0) {
1580                                 if (c->type != SSH_CHANNEL_OPEN)
1581                                         chan_mark_dead(c);
1582                                 else
1583                                         chan_write_failed(c);
1584                                 return -1;
1585                         }
1586                         return 1;
1587                 }
1588 #ifdef _AIX
1589                 /* XXX: Later AIX versions can't push as much data to tty */
1590                 if (compat20 && c->wfd_isatty)
1591                         dlen = MIN(dlen, 8*1024);
1592 #endif
1593
1594                 len = write(c->wfd, buf, dlen);
1595                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1596                         return 1;
1597                 if (len <= 0) {
1598                         if (c->type != SSH_CHANNEL_OPEN) {
1599                                 debug2("channel %d: not open", c->self);
1600                                 chan_mark_dead(c);
1601                                 return -1;
1602                         } else if (compat13) {
1603                                 buffer_clear(&c->output);
1604                                 debug2("channel %d: input draining.", c->self);
1605                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1606                         } else {
1607                                 chan_write_failed(c);
1608                         }
1609                         return -1;
1610                 }
1611                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1612                         if (tcgetattr(c->wfd, &tio) == 0 &&
1613                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1614                                 /*
1615                                  * Simulate echo to reduce the impact of
1616                                  * traffic analysis. We need to match the
1617                                  * size of a SSH2_MSG_CHANNEL_DATA message
1618                                  * (4 byte channel id + buf)
1619                                  */
1620                                 packet_send_ignore(4 + len);
1621                                 packet_send();
1622                         }
1623                 }
1624                 buffer_consume(&c->output, len);
1625                 if (compat20 && len > 0) {
1626                         c->local_consumed += len;
1627                 }
1628         }
1629         return 1;
1630 }
1631
1632 static int
1633 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1634 {
1635         char buf[CHAN_RBUF];
1636         int len;
1637
1638 /** XXX handle drain efd, too */
1639         if (c->efd != -1) {
1640                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1641                     FD_ISSET(c->efd, writeset) &&
1642                     buffer_len(&c->extended) > 0) {
1643                         len = write(c->efd, buffer_ptr(&c->extended),
1644                             buffer_len(&c->extended));
1645                         debug2("channel %d: written %d to efd %d",
1646                             c->self, len, c->efd);
1647                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1648                                 return 1;
1649                         if (len <= 0) {
1650                                 debug2("channel %d: closing write-efd %d",
1651                                     c->self, c->efd);
1652                                 channel_close_fd(&c->efd);
1653                         } else {
1654                                 buffer_consume(&c->extended, len);
1655                                 c->local_consumed += len;
1656                         }
1657                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1658                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1659                         len = read(c->efd, buf, sizeof(buf));
1660                         debug2("channel %d: read %d from efd %d",
1661                             c->self, len, c->efd);
1662                         if (len < 0 && (errno == EINTR ||
1663                             (errno == EAGAIN && !c->detach_close)))
1664                                 return 1;
1665                         if (len <= 0) {
1666                                 debug2("channel %d: closing read-efd %d",
1667                                     c->self, c->efd);
1668                                 channel_close_fd(&c->efd);
1669                         } else {
1670                                 buffer_append(&c->extended, buf, len);
1671                         }
1672                 }
1673         }
1674         return 1;
1675 }
1676
1677 /* ARGSUSED */
1678 static int
1679 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1680 {
1681         char buf[16];
1682         int len;
1683
1684         /* Monitor control fd to detect if the slave client exits */
1685         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1686                 len = read(c->ctl_fd, buf, sizeof(buf));
1687                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1688                         return 1;
1689                 if (len <= 0) {
1690                         debug2("channel %d: ctl read<=0", c->self);
1691                         if (c->type != SSH_CHANNEL_OPEN) {
1692                                 debug2("channel %d: not open", c->self);
1693                                 chan_mark_dead(c);
1694                                 return -1;
1695                         } else {
1696                                 chan_read_failed(c);
1697                                 chan_write_failed(c);
1698                         }
1699                         return -1;
1700                 } else
1701                         fatal("%s: unexpected data on ctl fd", __func__);
1702         }
1703         return 1;
1704 }
1705
1706 static int
1707 channel_check_window(Channel *c)
1708 {
1709         if (c->type == SSH_CHANNEL_OPEN &&
1710             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1711             ((c->local_window_max - c->local_window >
1712             c->local_maxpacket*3) ||
1713             c->local_window < c->local_window_max/2) &&
1714             c->local_consumed > 0) {
1715                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1716                 packet_put_int(c->remote_id);
1717                 packet_put_int(c->local_consumed);
1718                 packet_send();
1719                 debug2("channel %d: window %d sent adjust %d",
1720                     c->self, c->local_window,
1721                     c->local_consumed);
1722                 c->local_window += c->local_consumed;
1723                 c->local_consumed = 0;
1724         }
1725         return 1;
1726 }
1727
1728 static void
1729 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1730 {
1731         if (c->delayed)
1732                 return;
1733         channel_handle_rfd(c, readset, writeset);
1734         channel_handle_wfd(c, readset, writeset);
1735         if (!compat20)
1736                 return;
1737         channel_handle_efd(c, readset, writeset);
1738         channel_handle_ctl(c, readset, writeset);
1739         channel_check_window(c);
1740 }
1741
1742 /* ARGSUSED */
1743 static void
1744 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1745 {
1746         int len;
1747
1748         /* Send buffered output data to the socket. */
1749         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1750                 len = write(c->sock, buffer_ptr(&c->output),
1751                             buffer_len(&c->output));
1752                 if (len <= 0)
1753                         buffer_clear(&c->output);
1754                 else
1755                         buffer_consume(&c->output, len);
1756         }
1757 }
1758
1759 static void
1760 channel_handler_init_20(void)
1761 {
1762         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1763         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1764         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1765         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1766         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1767         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1768         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1769         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1770
1771         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1772         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1773         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1774         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1775         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1776         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1777         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1778 }
1779
1780 static void
1781 channel_handler_init_13(void)
1782 {
1783         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1784         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1785         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1786         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1787         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1788         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1789         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1790         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1791         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1792
1793         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1794         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1795         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1796         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1797         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1798         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1799         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1800 }
1801
1802 static void
1803 channel_handler_init_15(void)
1804 {
1805         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1806         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1807         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1808         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1809         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1810         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1811         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1812
1813         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1814         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1815         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1816         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1817         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1818         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1819 }
1820
1821 static void
1822 channel_handler_init(void)
1823 {
1824         int i;
1825
1826         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1827                 channel_pre[i] = NULL;
1828                 channel_post[i] = NULL;
1829         }
1830         if (compat20)
1831                 channel_handler_init_20();
1832         else if (compat13)
1833                 channel_handler_init_13();
1834         else
1835                 channel_handler_init_15();
1836 }
1837
1838 /* gc dead channels */
1839 static void
1840 channel_garbage_collect(Channel *c)
1841 {
1842         if (c == NULL)
1843                 return;
1844         if (c->detach_user != NULL) {
1845                 if (!chan_is_dead(c, c->detach_close))
1846                         return;
1847                 debug2("channel %d: gc: notify user", c->self);
1848                 c->detach_user(c->self, NULL);
1849                 /* if we still have a callback */
1850                 if (c->detach_user != NULL)
1851                         return;
1852                 debug2("channel %d: gc: user detached", c->self);
1853         }
1854         if (!chan_is_dead(c, 1))
1855                 return;
1856         debug2("channel %d: garbage collecting", c->self);
1857         channel_free(c);
1858 }
1859
1860 static void
1861 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1862 {
1863         static int did_init = 0;
1864         u_int i;
1865         Channel *c;
1866
1867         if (!did_init) {
1868                 channel_handler_init();
1869                 did_init = 1;
1870         }
1871         for (i = 0; i < channels_alloc; i++) {
1872                 c = channels[i];
1873                 if (c == NULL)
1874                         continue;
1875                 if (ftab[c->type] != NULL)
1876                         (*ftab[c->type])(c, readset, writeset);
1877                 channel_garbage_collect(c);
1878         }
1879 }
1880
1881 /*
1882  * Allocate/update select bitmasks and add any bits relevant to channels in
1883  * select bitmasks.
1884  */
1885 void
1886 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1887     u_int *nallocp, int rekeying)
1888 {
1889         u_int n, sz, nfdset;
1890
1891         n = MAX(*maxfdp, channel_max_fd);
1892
1893         nfdset = howmany(n+1, NFDBITS);
1894         /* Explicitly test here, because xrealloc isn't always called */
1895         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1896                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1897         sz = nfdset * sizeof(fd_mask);
1898
1899         /* perhaps check sz < nalloc/2 and shrink? */
1900         if (*readsetp == NULL || sz > *nallocp) {
1901                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1902                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1903                 *nallocp = sz;
1904         }
1905         *maxfdp = n;
1906         memset(*readsetp, 0, sz);
1907         memset(*writesetp, 0, sz);
1908
1909         if (!rekeying)
1910                 channel_handler(channel_pre, *readsetp, *writesetp);
1911 }
1912
1913 /*
1914  * After select, perform any appropriate operations for channels which have
1915  * events pending.
1916  */
1917 void
1918 channel_after_select(fd_set *readset, fd_set *writeset)
1919 {
1920         channel_handler(channel_post, readset, writeset);
1921 }
1922
1923
1924 /* If there is data to send to the connection, enqueue some of it now. */
1925 void
1926 channel_output_poll(void)
1927 {
1928         Channel *c;
1929         u_int i, len;
1930
1931         for (i = 0; i < channels_alloc; i++) {
1932                 c = channels[i];
1933                 if (c == NULL)
1934                         continue;
1935
1936                 /*
1937                  * We are only interested in channels that can have buffered
1938                  * incoming data.
1939                  */
1940                 if (compat13) {
1941                         if (c->type != SSH_CHANNEL_OPEN &&
1942                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1943                                 continue;
1944                 } else {
1945                         if (c->type != SSH_CHANNEL_OPEN)
1946                                 continue;
1947                 }
1948                 if (compat20 &&
1949                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1950                         /* XXX is this true? */
1951                         debug3("channel %d: will not send data after close", c->self);
1952                         continue;
1953                 }
1954
1955                 /* Get the amount of buffered data for this channel. */
1956                 if ((c->istate == CHAN_INPUT_OPEN ||
1957                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1958                     (len = buffer_len(&c->input)) > 0) {
1959                         if (c->datagram) {
1960                                 if (len > 0) {
1961                                         u_char *data;
1962                                         u_int dlen;
1963
1964                                         data = buffer_get_string(&c->input,
1965                                             &dlen);
1966                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1967                                         packet_put_int(c->remote_id);
1968                                         packet_put_string(data, dlen);
1969                                         packet_send();
1970                                         c->remote_window -= dlen + 4;
1971                                         xfree(data);
1972                                 }
1973                                 continue;
1974                         }
1975                         /*
1976                          * Send some data for the other side over the secure
1977                          * connection.
1978                          */
1979                         if (compat20) {
1980                                 if (len > c->remote_window)
1981                                         len = c->remote_window;
1982                                 if (len > c->remote_maxpacket)
1983                                         len = c->remote_maxpacket;
1984                         } else {
1985                                 if (packet_is_interactive()) {
1986                                         if (len > 1024)
1987                                                 len = 512;
1988                                 } else {
1989                                         /* Keep the packets at reasonable size. */
1990                                         if (len > packet_get_maxsize()/2)
1991                                                 len = packet_get_maxsize()/2;
1992                                 }
1993                         }
1994                         if (len > 0) {
1995                                 packet_start(compat20 ?
1996                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1997                                 packet_put_int(c->remote_id);
1998                                 packet_put_string(buffer_ptr(&c->input), len);
1999                                 packet_send();
2000                                 buffer_consume(&c->input, len);
2001                                 c->remote_window -= len;
2002                         }
2003                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2004                         if (compat13)
2005                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2006                         /*
2007                          * input-buffer is empty and read-socket shutdown:
2008                          * tell peer, that we will not send more data: send IEOF.
2009                          * hack for extended data: delay EOF if EFD still in use.
2010                          */
2011                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2012                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2013                                     c->self, c->efd, buffer_len(&c->extended));
2014                         else
2015                                 chan_ibuf_empty(c);
2016                 }
2017                 /* Send extended data, i.e. stderr */
2018                 if (compat20 &&
2019                     !(c->flags & CHAN_EOF_SENT) &&
2020                     c->remote_window > 0 &&
2021                     (len = buffer_len(&c->extended)) > 0 &&
2022                     c->extended_usage == CHAN_EXTENDED_READ) {
2023                         debug2("channel %d: rwin %u elen %u euse %d",
2024                             c->self, c->remote_window, buffer_len(&c->extended),
2025                             c->extended_usage);
2026                         if (len > c->remote_window)
2027                                 len = c->remote_window;
2028                         if (len > c->remote_maxpacket)
2029                                 len = c->remote_maxpacket;
2030                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2031                         packet_put_int(c->remote_id);
2032                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2033                         packet_put_string(buffer_ptr(&c->extended), len);
2034                         packet_send();
2035                         buffer_consume(&c->extended, len);
2036                         c->remote_window -= len;
2037                         debug2("channel %d: sent ext data %d", c->self, len);
2038                 }
2039         }
2040 }
2041
2042
2043 /* -- protocol input */
2044
2045 /* ARGSUSED */
2046 void
2047 channel_input_data(int type, u_int32_t seq, void *ctxt)
2048 {
2049         int id;
2050         char *data;
2051         u_int data_len;
2052         Channel *c;
2053
2054         /* Get the channel number and verify it. */
2055         id = packet_get_int();
2056         c = channel_lookup(id);
2057         if (c == NULL)
2058                 packet_disconnect("Received data for nonexistent channel %d.", id);
2059
2060         /* Ignore any data for non-open channels (might happen on close) */
2061         if (c->type != SSH_CHANNEL_OPEN &&
2062             c->type != SSH_CHANNEL_X11_OPEN)
2063                 return;
2064
2065         /* Get the data. */
2066         data = packet_get_string_ptr(&data_len);
2067
2068         /*
2069          * Ignore data for protocol > 1.3 if output end is no longer open.
2070          * For protocol 2 the sending side is reducing its window as it sends
2071          * data, so we must 'fake' consumption of the data in order to ensure
2072          * that window updates are sent back.  Otherwise the connection might
2073          * deadlock.
2074          */
2075         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2076                 if (compat20) {
2077                         c->local_window -= data_len;
2078                         c->local_consumed += data_len;
2079                 }
2080                 return;
2081         }
2082
2083         if (compat20) {
2084                 if (data_len > c->local_maxpacket) {
2085                         logit("channel %d: rcvd big packet %d, maxpack %d",
2086                             c->self, data_len, c->local_maxpacket);
2087                 }
2088                 if (data_len > c->local_window) {
2089                         logit("channel %d: rcvd too much data %d, win %d",
2090                             c->self, data_len, c->local_window);
2091                         return;
2092                 }
2093                 c->local_window -= data_len;
2094         }
2095         if (c->datagram)
2096                 buffer_put_string(&c->output, data, data_len);
2097         else
2098                 buffer_append(&c->output, data, data_len);
2099         packet_check_eom();
2100 }
2101
2102 /* ARGSUSED */
2103 void
2104 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2105 {
2106         int id;
2107         char *data;
2108         u_int data_len, tcode;
2109         Channel *c;
2110
2111         /* Get the channel number and verify it. */
2112         id = packet_get_int();
2113         c = channel_lookup(id);
2114
2115         if (c == NULL)
2116                 packet_disconnect("Received extended_data for bad channel %d.", id);
2117         if (c->type != SSH_CHANNEL_OPEN) {
2118                 logit("channel %d: ext data for non open", id);
2119                 return;
2120         }
2121         if (c->flags & CHAN_EOF_RCVD) {
2122                 if (datafellows & SSH_BUG_EXTEOF)
2123                         debug("channel %d: accepting ext data after eof", id);
2124                 else
2125                         packet_disconnect("Received extended_data after EOF "
2126                             "on channel %d.", id);
2127         }
2128         tcode = packet_get_int();
2129         if (c->efd == -1 ||
2130             c->extended_usage != CHAN_EXTENDED_WRITE ||
2131             tcode != SSH2_EXTENDED_DATA_STDERR) {
2132                 logit("channel %d: bad ext data", c->self);
2133                 return;
2134         }
2135         data = packet_get_string(&data_len);
2136         packet_check_eom();
2137         if (data_len > c->local_window) {
2138                 logit("channel %d: rcvd too much extended_data %d, win %d",
2139                     c->self, data_len, c->local_window);
2140                 xfree(data);
2141                 return;
2142         }
2143         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2144         c->local_window -= data_len;
2145         buffer_append(&c->extended, data, data_len);
2146         xfree(data);
2147 }
2148
2149 /* ARGSUSED */
2150 void
2151 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2152 {
2153         int id;
2154         Channel *c;
2155
2156         id = packet_get_int();
2157         packet_check_eom();
2158         c = channel_lookup(id);
2159         if (c == NULL)
2160                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2161         chan_rcvd_ieof(c);
2162
2163         /* XXX force input close */
2164         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2165                 debug("channel %d: FORCE input drain", c->self);
2166                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2167                 if (buffer_len(&c->input) == 0)
2168                         chan_ibuf_empty(c);
2169         }
2170
2171 }
2172
2173 /* ARGSUSED */
2174 void
2175 channel_input_close(int type, u_int32_t seq, void *ctxt)
2176 {
2177         int id;
2178         Channel *c;
2179
2180         id = packet_get_int();
2181         packet_check_eom();
2182         c = channel_lookup(id);
2183         if (c == NULL)
2184                 packet_disconnect("Received close for nonexistent channel %d.", id);
2185
2186         /*
2187          * Send a confirmation that we have closed the channel and no more
2188          * data is coming for it.
2189          */
2190         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2191         packet_put_int(c->remote_id);
2192         packet_send();
2193
2194         /*
2195          * If the channel is in closed state, we have sent a close request,
2196          * and the other side will eventually respond with a confirmation.
2197          * Thus, we cannot free the channel here, because then there would be
2198          * no-one to receive the confirmation.  The channel gets freed when
2199          * the confirmation arrives.
2200          */
2201         if (c->type != SSH_CHANNEL_CLOSED) {
2202                 /*
2203                  * Not a closed channel - mark it as draining, which will
2204                  * cause it to be freed later.
2205                  */
2206                 buffer_clear(&c->input);
2207                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2208         }
2209 }
2210
2211 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2212 /* ARGSUSED */
2213 void
2214 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2215 {
2216         int id = packet_get_int();
2217         Channel *c = channel_lookup(id);
2218
2219         packet_check_eom();
2220         if (c == NULL)
2221                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2222         chan_rcvd_oclose(c);
2223 }
2224
2225 /* ARGSUSED */
2226 void
2227 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2228 {
2229         int id = packet_get_int();
2230         Channel *c = channel_lookup(id);
2231
2232         packet_check_eom();
2233         if (c == NULL)
2234                 packet_disconnect("Received close confirmation for "
2235                     "out-of-range channel %d.", id);
2236         if (c->type != SSH_CHANNEL_CLOSED)
2237                 packet_disconnect("Received close confirmation for "
2238                     "non-closed channel %d (type %d).", id, c->type);
2239         channel_free(c);
2240 }
2241
2242 /* ARGSUSED */
2243 void
2244 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2245 {
2246         int id, remote_id;
2247         Channel *c;
2248
2249         id = packet_get_int();
2250         c = channel_lookup(id);
2251
2252         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2253                 packet_disconnect("Received open confirmation for "
2254                     "non-opening channel %d.", id);
2255         remote_id = packet_get_int();
2256         /* Record the remote channel number and mark that the channel is now open. */
2257         c->remote_id = remote_id;
2258         c->type = SSH_CHANNEL_OPEN;
2259
2260         if (compat20) {
2261                 c->remote_window = packet_get_int();
2262                 c->remote_maxpacket = packet_get_int();
2263                 if (c->open_confirm) {
2264                         debug2("callback start");
2265                         c->open_confirm(c->self, c->open_confirm_ctx);
2266                         debug2("callback done");
2267                 }
2268                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2269                     c->remote_window, c->remote_maxpacket);
2270         }
2271         packet_check_eom();
2272 }
2273
2274 static char *
2275 reason2txt(int reason)
2276 {
2277         switch (reason) {
2278         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2279                 return "administratively prohibited";
2280         case SSH2_OPEN_CONNECT_FAILED:
2281                 return "connect failed";
2282         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2283                 return "unknown channel type";
2284         case SSH2_OPEN_RESOURCE_SHORTAGE:
2285                 return "resource shortage";
2286         }
2287         return "unknown reason";
2288 }
2289
2290 /* ARGSUSED */
2291 void
2292 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2293 {
2294         int id, reason;
2295         char *msg = NULL, *lang = NULL;
2296         Channel *c;
2297
2298         id = packet_get_int();
2299         c = channel_lookup(id);
2300
2301         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2302                 packet_disconnect("Received open failure for "
2303                     "non-opening channel %d.", id);
2304         if (compat20) {
2305                 reason = packet_get_int();
2306                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2307                         msg  = packet_get_string(NULL);
2308                         lang = packet_get_string(NULL);
2309                 }
2310                 logit("channel %d: open failed: %s%s%s", id,
2311                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2312                 if (msg != NULL)
2313                         xfree(msg);
2314                 if (lang != NULL)
2315                         xfree(lang);
2316         }
2317         packet_check_eom();
2318         /* Free the channel.  This will also close the socket. */
2319         channel_free(c);
2320 }
2321
2322 /* ARGSUSED */
2323 void
2324 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2325 {
2326         Channel *c;
2327         int id;
2328         u_int adjust;
2329
2330         if (!compat20)
2331                 return;
2332
2333         /* Get the channel number and verify it. */
2334         id = packet_get_int();
2335         c = channel_lookup(id);
2336
2337         if (c == NULL) {
2338                 logit("Received window adjust for non-open channel %d.", id);
2339                 return;
2340         }
2341         adjust = packet_get_int();
2342         packet_check_eom();
2343         debug2("channel %d: rcvd adjust %u", id, adjust);
2344         c->remote_window += adjust;
2345 }
2346
2347 /* ARGSUSED */
2348 void
2349 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2350 {
2351         Channel *c = NULL;
2352         u_short host_port;
2353         char *host, *originator_string;
2354         int remote_id;
2355
2356         remote_id = packet_get_int();
2357         host = packet_get_string(NULL);
2358         host_port = packet_get_int();
2359
2360         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2361                 originator_string = packet_get_string(NULL);
2362         } else {
2363                 originator_string = xstrdup("unknown (remote did not supply name)");
2364         }
2365         packet_check_eom();
2366         c = channel_connect_to(host, host_port,
2367             "connected socket", originator_string);
2368         xfree(originator_string);
2369         xfree(host);
2370         if (c == NULL) {
2371                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2372                 packet_put_int(remote_id);
2373                 packet_send();
2374         } else
2375                 c->remote_id = remote_id;
2376 }
2377
2378 /* ARGSUSED */
2379 void
2380 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2381 {
2382         Channel *c;
2383         struct channel_confirm *cc;
2384         int remote_id;
2385
2386         /* Reset keepalive timeout */
2387         keep_alive_timeouts = 0;
2388
2389         remote_id = packet_get_int();
2390         packet_check_eom();
2391
2392         debug2("channel_input_confirm: type %d id %d", type, remote_id);
2393
2394         if ((c = channel_lookup(remote_id)) == NULL) {
2395                 logit("channel_input_success_failure: %d: unknown", remote_id);
2396                 return;
2397         }
2398         ;
2399         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2400                 return;
2401         cc->cb(type, c, cc->ctx);
2402         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2403         bzero(cc, sizeof(*cc));
2404         xfree(cc);
2405 }
2406
2407 /* -- tcp forwarding */
2408
2409 void
2410 channel_set_af(int af)
2411 {
2412         IPv4or6 = af;
2413 }
2414
2415 static int
2416 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2417     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2418 {
2419         Channel *c;
2420         int sock, r, success = 0, wildcard = 0, is_client;
2421         struct addrinfo hints, *ai, *aitop;
2422         const char *host, *addr;
2423         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2424
2425         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2426             listen_addr : host_to_connect;
2427         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2428
2429         if (host == NULL) {
2430                 error("No forward host name.");
2431                 return 0;
2432         }
2433         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2434                 error("Forward host name too long.");
2435                 return 0;
2436         }
2437
2438         /*
2439          * Determine whether or not a port forward listens to loopback,
2440          * specified address or wildcard. On the client, a specified bind
2441          * address will always override gateway_ports. On the server, a
2442          * gateway_ports of 1 (``yes'') will override the client's
2443          * specification and force a wildcard bind, whereas a value of 2
2444          * (``clientspecified'') will bind to whatever address the client
2445          * asked for.
2446          *
2447          * Special-case listen_addrs are:
2448          *
2449          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2450          * "" (empty string), "*"  -> wildcard v4/v6
2451          * "localhost"             -> loopback v4/v6
2452          */
2453         addr = NULL;
2454         if (listen_addr == NULL) {
2455                 /* No address specified: default to gateway_ports setting */
2456                 if (gateway_ports)
2457                         wildcard = 1;
2458         } else if (gateway_ports || is_client) {
2459                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2460                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2461                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2462                     (!is_client && gateway_ports == 1))
2463                         wildcard = 1;
2464                 else if (strcmp(listen_addr, "localhost") != 0)
2465                         addr = listen_addr;
2466         }
2467
2468         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2469             type, wildcard, (addr == NULL) ? "NULL" : addr);
2470
2471         /*
2472          * getaddrinfo returns a loopback address if the hostname is
2473          * set to NULL and hints.ai_flags is not AI_PASSIVE
2474          */
2475         memset(&hints, 0, sizeof(hints));
2476         hints.ai_family = IPv4or6;
2477         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2478         hints.ai_socktype = SOCK_STREAM;
2479         snprintf(strport, sizeof strport, "%d", listen_port);
2480         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2481                 if (addr == NULL) {
2482                         /* This really shouldn't happen */
2483                         packet_disconnect("getaddrinfo: fatal error: %s",
2484                             ssh_gai_strerror(r));
2485                 } else {
2486                         error("channel_setup_fwd_listener: "
2487                             "getaddrinfo(%.64s): %s", addr,
2488                             ssh_gai_strerror(r));
2489                 }
2490                 return 0;
2491         }
2492
2493         for (ai = aitop; ai; ai = ai->ai_next) {
2494                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2495                         continue;
2496                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2497                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2498                         error("channel_setup_fwd_listener: getnameinfo failed");
2499                         continue;
2500                 }
2501                 /* Create a port to listen for the host. */
2502                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2503                 if (sock < 0) {
2504                         /* this is no error since kernel may not support ipv6 */
2505                         verbose("socket: %.100s", strerror(errno));
2506                         continue;
2507                 }
2508
2509                 channel_set_reuseaddr(sock);
2510
2511                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2512
2513                 /* Bind the socket to the address. */
2514                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2515                         /* address can be in use ipv6 address is already bound */
2516                         if (!ai->ai_next)
2517                                 error("bind: %.100s", strerror(errno));
2518                         else
2519                                 verbose("bind: %.100s", strerror(errno));
2520
2521                         close(sock);
2522                         continue;
2523                 }
2524                 /* Start listening for connections on the socket. */
2525                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2526                         error("listen: %.100s", strerror(errno));
2527                         close(sock);
2528                         continue;
2529                 }
2530                 /* Allocate a channel number for the socket. */
2531                 c = channel_new("port listener", type, sock, sock, -1,
2532                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2533                     0, "port listener", 1);
2534                 strlcpy(c->path, host, sizeof(c->path));
2535                 c->host_port = port_to_connect;
2536                 c->listening_port = listen_port;
2537                 success = 1;
2538         }
2539         if (success == 0)
2540                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2541                     listen_port);
2542         freeaddrinfo(aitop);
2543         return success;
2544 }
2545
2546 int
2547 channel_cancel_rport_listener(const char *host, u_short port)
2548 {
2549         u_int i;
2550         int found = 0;
2551
2552         for (i = 0; i < channels_alloc; i++) {
2553                 Channel *c = channels[i];
2554
2555                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2556                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2557                     c->listening_port == port) {
2558                         debug2("%s: close channel %d", __func__, i);
2559                         channel_free(c);
2560                         found = 1;
2561                 }
2562         }
2563
2564         return (found);
2565 }
2566
2567 /* protocol local port fwd, used by ssh (and sshd in v1) */
2568 int
2569 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2570     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2571 {
2572         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2573             listen_host, listen_port, host_to_connect, port_to_connect,
2574             gateway_ports);
2575 }
2576
2577 /* protocol v2 remote port fwd, used by sshd */
2578 int
2579 channel_setup_remote_fwd_listener(const char *listen_address,
2580     u_short listen_port, int gateway_ports)
2581 {
2582         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2583             listen_address, listen_port, NULL, 0, gateway_ports);
2584 }
2585
2586 /*
2587  * Initiate forwarding of connections to port "port" on remote host through
2588  * the secure channel to host:port from local side.
2589  */
2590
2591 int
2592 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2593     const char *host_to_connect, u_short port_to_connect)
2594 {
2595         int type, success = 0;
2596
2597         /* Record locally that connection to this host/port is permitted. */
2598         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2599                 fatal("channel_request_remote_forwarding: too many forwards");
2600
2601         /* Send the forward request to the remote side. */
2602         if (compat20) {
2603                 const char *address_to_bind;
2604                 if (listen_host == NULL) {
2605                         if (datafellows & SSH_BUG_RFWD_ADDR)
2606                                 address_to_bind = "127.0.0.1";
2607                         else
2608                                 address_to_bind = "localhost";
2609                 } else if (*listen_host == '\0' ||
2610                            strcmp(listen_host, "*") == 0) {
2611                         if (datafellows & SSH_BUG_RFWD_ADDR)
2612                                 address_to_bind = "0.0.0.0";
2613                         else
2614                                 address_to_bind = "";
2615                 } else
2616                         address_to_bind = listen_host;
2617
2618                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2619                 packet_put_cstring("tcpip-forward");
2620                 packet_put_char(1);                     /* boolean: want reply */
2621                 packet_put_cstring(address_to_bind);
2622                 packet_put_int(listen_port);
2623                 packet_send();
2624                 packet_write_wait();
2625                 /* Assume that server accepts the request */
2626                 success = 1;
2627         } else {
2628                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2629                 packet_put_int(listen_port);
2630                 packet_put_cstring(host_to_connect);
2631                 packet_put_int(port_to_connect);
2632                 packet_send();
2633                 packet_write_wait();
2634
2635                 /* Wait for response from the remote side. */
2636                 type = packet_read();
2637                 switch (type) {
2638                 case SSH_SMSG_SUCCESS:
2639                         success = 1;
2640                         break;
2641                 case SSH_SMSG_FAILURE:
2642                         break;
2643                 default:
2644                         /* Unknown packet */
2645                         packet_disconnect("Protocol error for port forward request:"
2646                             "received packet type %d.", type);
2647                 }
2648         }
2649         if (success) {
2650                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2651                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2652                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2653                 num_permitted_opens++;
2654         }
2655         return (success ? 0 : -1);
2656 }
2657
2658 /*
2659  * Request cancellation of remote forwarding of connection host:port from
2660  * local side.
2661  */
2662 void
2663 channel_request_rforward_cancel(const char *host, u_short port)
2664 {
2665         int i;
2666
2667         if (!compat20)
2668                 return;
2669
2670         for (i = 0; i < num_permitted_opens; i++) {
2671                 if (permitted_opens[i].host_to_connect != NULL &&
2672                     permitted_opens[i].listen_port == port)
2673                         break;
2674         }
2675         if (i >= num_permitted_opens) {
2676                 debug("%s: requested forward not found", __func__);
2677                 return;
2678         }
2679         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2680         packet_put_cstring("cancel-tcpip-forward");
2681         packet_put_char(0);
2682         packet_put_cstring(host == NULL ? "" : host);
2683         packet_put_int(port);
2684         packet_send();
2685
2686         permitted_opens[i].listen_port = 0;
2687         permitted_opens[i].port_to_connect = 0;
2688         xfree(permitted_opens[i].host_to_connect);
2689         permitted_opens[i].host_to_connect = NULL;
2690 }
2691
2692 /*
2693  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2694  * listening for the port, and sends back a success reply (or disconnect
2695  * message if there was an error).
2696  */
2697 int
2698 channel_input_port_forward_request(int is_root, int gateway_ports)
2699 {
2700         u_short port, host_port;
2701         int success = 0;
2702         char *hostname;
2703
2704         /* Get arguments from the packet. */
2705         port = packet_get_int();
2706         hostname = packet_get_string(NULL);
2707         host_port = packet_get_int();
2708
2709 #ifndef HAVE_CYGWIN
2710         /*
2711          * Check that an unprivileged user is not trying to forward a
2712          * privileged port.
2713          */
2714         if (port < IPPORT_RESERVED && !is_root)
2715                 packet_disconnect(
2716                     "Requested forwarding of port %d but user is not root.",
2717                     port);
2718         if (host_port == 0)
2719                 packet_disconnect("Dynamic forwarding denied.");
2720 #endif
2721
2722         /* Initiate forwarding */
2723         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2724             host_port, gateway_ports);
2725
2726         /* Free the argument string. */
2727         xfree(hostname);
2728
2729         return (success ? 0 : -1);
2730 }
2731
2732 /*
2733  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2734  * usually called by the server, because the user could connect to any port
2735  * anyway, and the server has no way to know but to trust the client anyway.
2736  */
2737 void
2738 channel_permit_all_opens(void)
2739 {
2740         if (num_permitted_opens == 0)
2741                 all_opens_permitted = 1;
2742 }
2743
2744 void
2745 channel_add_permitted_opens(char *host, int port)
2746 {
2747         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2748                 fatal("channel_add_permitted_opens: too many forwards");
2749         debug("allow port forwarding to host %s port %d", host, port);
2750
2751         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2752         permitted_opens[num_permitted_opens].port_to_connect = port;
2753         num_permitted_opens++;
2754
2755         all_opens_permitted = 0;
2756 }
2757
2758 int
2759 channel_add_adm_permitted_opens(char *host, int port)
2760 {
2761         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2762                 fatal("channel_add_adm_permitted_opens: too many forwards");
2763         debug("config allows port forwarding to host %s port %d", host, port);
2764
2765         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2766              = xstrdup(host);
2767         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2768         return ++num_adm_permitted_opens;
2769 }
2770
2771 void
2772 channel_clear_permitted_opens(void)
2773 {
2774         int i;
2775
2776         for (i = 0; i < num_permitted_opens; i++)
2777                 if (permitted_opens[i].host_to_connect != NULL)
2778                         xfree(permitted_opens[i].host_to_connect);
2779         num_permitted_opens = 0;
2780 }
2781
2782 void
2783 channel_clear_adm_permitted_opens(void)
2784 {
2785         int i;
2786
2787         for (i = 0; i < num_adm_permitted_opens; i++)
2788                 if (permitted_adm_opens[i].host_to_connect != NULL)
2789                         xfree(permitted_adm_opens[i].host_to_connect);
2790         num_adm_permitted_opens = 0;
2791 }
2792
2793 void
2794 channel_print_adm_permitted_opens(void)
2795 {
2796         static int i;
2797
2798         for (i = 0; i < num_adm_permitted_opens; i++)
2799                 if (permitted_adm_opens[i].host_to_connect != NULL)
2800                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
2801                             permitted_adm_opens[i].port_to_connect);
2802 }
2803
2804 /* Try to start non-blocking connect to next host in cctx list */
2805 static int
2806 connect_next(struct channel_connect *cctx)
2807 {
2808         int sock, saved_errno;
2809         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2810
2811         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
2812                 if (cctx->ai->ai_family != AF_INET &&
2813                     cctx->ai->ai_family != AF_INET6)
2814                         continue;
2815                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
2816                     ntop, sizeof(ntop), strport, sizeof(strport),
2817                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2818                         error("connect_next: getnameinfo failed");
2819                         continue;
2820                 }
2821                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
2822                     cctx->ai->ai_protocol)) == -1) {
2823                         if (cctx->ai->ai_next == NULL)
2824                                 error("socket: %.100s", strerror(errno));
2825                         else
2826                                 verbose("socket: %.100s", strerror(errno));
2827                         continue;
2828                 }
2829                 if (set_nonblock(sock) == -1)
2830                         fatal("%s: set_nonblock(%d)", __func__, sock);
2831                 if (connect(sock, cctx->ai->ai_addr,
2832                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
2833                         debug("connect_next: host %.100s ([%.100s]:%s): "
2834                             "%.100s", cctx->host, ntop, strport,
2835                             strerror(errno));
2836                         saved_errno = errno;
2837                         close(sock);
2838                         errno = saved_errno;
2839                         continue;       /* fail -- try next */
2840                 }
2841                 debug("connect_next: host %.100s ([%.100s]:%s) "
2842                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
2843                 cctx->ai = cctx->ai->ai_next;
2844                 set_nodelay(sock);
2845                 return sock;
2846         }
2847         return -1;
2848 }
2849
2850 static void
2851 channel_connect_ctx_free(struct channel_connect *cctx)
2852 {
2853         xfree(cctx->host);
2854         if (cctx->aitop)
2855                 freeaddrinfo(cctx->aitop);
2856         bzero(cctx, sizeof(*cctx));
2857         cctx->host = NULL;
2858         cctx->ai = cctx->aitop = NULL;
2859 }
2860
2861 /* Return CONNECTING channel to remote host, port */
2862 static Channel *
2863 connect_to(const char *host, u_short port, char *ctype, char *rname)
2864 {
2865         struct addrinfo hints;
2866         int gaierr;
2867         int sock = -1;
2868         char strport[NI_MAXSERV];
2869         struct channel_connect cctx;
2870         Channel *c;
2871
2872         memset(&hints, 0, sizeof(hints));
2873         hints.ai_family = IPv4or6;
2874         hints.ai_socktype = SOCK_STREAM;
2875         snprintf(strport, sizeof strport, "%d", port);
2876         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
2877                 error("connect_to %.100s: unknown host (%s)", host,
2878                     ssh_gai_strerror(gaierr));
2879                 return NULL;
2880         }
2881
2882         cctx.host = xstrdup(host);
2883         cctx.port = port;
2884         cctx.ai = cctx.aitop;
2885
2886         if ((sock = connect_next(&cctx)) == -1) {
2887                 error("connect to %.100s port %d failed: %s",
2888                     host, port, strerror(errno));
2889                 channel_connect_ctx_free(&cctx);
2890                 return NULL;
2891         }
2892         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
2893             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
2894         c->connect_ctx = cctx;
2895         return c;
2896 }
2897
2898 Channel *
2899 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
2900 {
2901         int i;
2902
2903         for (i = 0; i < num_permitted_opens; i++) {
2904                 if (permitted_opens[i].host_to_connect != NULL &&
2905                     permitted_opens[i].listen_port == listen_port) {
2906                         return connect_to(
2907                             permitted_opens[i].host_to_connect,
2908                             permitted_opens[i].port_to_connect, ctype, rname);
2909                 }
2910         }
2911         error("WARNING: Server requests forwarding for unknown listen_port %d",
2912             listen_port);
2913         return NULL;
2914 }
2915
2916 /* Check if connecting to that port is permitted and connect. */
2917 Channel *
2918 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
2919 {
2920         int i, permit, permit_adm = 1;
2921
2922         permit = all_opens_permitted;
2923         if (!permit) {
2924                 for (i = 0; i < num_permitted_opens; i++)
2925                         if (permitted_opens[i].host_to_connect != NULL &&
2926                             permitted_opens[i].port_to_connect == port &&
2927                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2928                                 permit = 1;
2929         }
2930
2931         if (num_adm_permitted_opens > 0) {
2932                 permit_adm = 0;
2933                 for (i = 0; i < num_adm_permitted_opens; i++)
2934                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2935                             permitted_adm_opens[i].port_to_connect == port &&
2936                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2937                             == 0)
2938                                 permit_adm = 1;
2939         }
2940
2941         if (!permit || !permit_adm) {
2942                 logit("Received request to connect to host %.100s port %d, "
2943                     "but the request was denied.", host, port);
2944                 return NULL;
2945         }
2946         return connect_to(host, port, ctype, rname);
2947 }
2948
2949 void
2950 channel_send_window_changes(void)
2951 {
2952         u_int i;
2953         struct winsize ws;
2954
2955         for (i = 0; i < channels_alloc; i++) {
2956                 if (channels[i] == NULL || !channels[i]->client_tty ||
2957                     channels[i]->type != SSH_CHANNEL_OPEN)
2958                         continue;
2959                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2960                         continue;
2961                 channel_request_start(i, "window-change", 0);
2962                 packet_put_int((u_int)ws.ws_col);
2963                 packet_put_int((u_int)ws.ws_row);
2964                 packet_put_int((u_int)ws.ws_xpixel);
2965                 packet_put_int((u_int)ws.ws_ypixel);
2966                 packet_send();
2967         }
2968 }
2969
2970 /* -- X11 forwarding */
2971
2972 /*
2973  * Creates an internet domain socket for listening for X11 connections.
2974  * Returns 0 and a suitable display number for the DISPLAY variable
2975  * stored in display_numberp , or -1 if an error occurs.
2976  */
2977 int
2978 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2979     int single_connection, u_int *display_numberp, int **chanids)
2980 {
2981         Channel *nc = NULL;
2982         int display_number, sock;
2983         u_short port;
2984         struct addrinfo hints, *ai, *aitop;
2985         char strport[NI_MAXSERV];
2986         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2987
2988         if (chanids == NULL)
2989                 return -1;
2990
2991         for (display_number = x11_display_offset;
2992             display_number < MAX_DISPLAYS;
2993             display_number++) {
2994                 port = 6000 + display_number;
2995                 memset(&hints, 0, sizeof(hints));
2996                 hints.ai_family = IPv4or6;
2997                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2998                 hints.ai_socktype = SOCK_STREAM;
2999                 snprintf(strport, sizeof strport, "%d", port);
3000                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3001                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3002                         return -1;
3003                 }
3004                 for (ai = aitop; ai; ai = ai->ai_next) {
3005                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3006                                 continue;
3007                         sock = socket(ai->ai_family, ai->ai_socktype,
3008                             ai->ai_protocol);
3009                         if (sock < 0) {
3010                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3011                                         error("socket: %.100s", strerror(errno));
3012                                         freeaddrinfo(aitop);
3013                                         return -1;
3014                                 } else {
3015                                         debug("x11_create_display_inet: Socket family %d not supported",
3016                                                  ai->ai_family);
3017                                         continue;
3018                                 }
3019                         }
3020 #ifdef IPV6_V6ONLY
3021                         if (ai->ai_family == AF_INET6) {
3022                                 int on = 1;
3023                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
3024                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
3025                         }
3026 #endif
3027                         if (x11_use_localhost)
3028                                 channel_set_reuseaddr(sock);
3029                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3030                                 debug2("bind port %d: %.100s", port, strerror(errno));
3031                                 close(sock);
3032
3033                                 for (n = 0; n < num_socks; n++) {
3034                                         close(socks[n]);
3035                                 }
3036                                 num_socks = 0;
3037                                 break;
3038                         }
3039                         socks[num_socks++] = sock;
3040                         if (num_socks == NUM_SOCKS)
3041                                 break;
3042                 }
3043                 freeaddrinfo(aitop);
3044                 if (num_socks > 0)
3045                         break;
3046         }
3047         if (display_number >= MAX_DISPLAYS) {
3048                 error("Failed to allocate internet-domain X11 display socket.");
3049                 return -1;
3050         }
3051         /* Start listening for connections on the socket. */
3052         for (n = 0; n < num_socks; n++) {
3053                 sock = socks[n];
3054                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3055                         error("listen: %.100s", strerror(errno));
3056                         close(sock);
3057                         return -1;
3058                 }
3059         }
3060
3061         /* Allocate a channel for each socket. */
3062         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3063         for (n = 0; n < num_socks; n++) {
3064                 sock = socks[n];
3065                 nc = channel_new("x11 listener",
3066                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3067                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3068                     0, "X11 inet listener", 1);
3069                 nc->single_connection = single_connection;
3070                 (*chanids)[n] = nc->self;
3071         }
3072         (*chanids)[n] = -1;
3073
3074         /* Return the display number for the DISPLAY environment variable. */
3075         *display_numberp = display_number;
3076         return (0);
3077 }
3078
3079 static int
3080 connect_local_xsocket(u_int dnr)
3081 {
3082         int sock;
3083         struct sockaddr_un addr;
3084
3085         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3086         if (sock < 0)
3087                 error("socket: %.100s", strerror(errno));
3088         memset(&addr, 0, sizeof(addr));
3089         addr.sun_family = AF_UNIX;
3090         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
3091         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3092                 return sock;
3093         close(sock);
3094         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3095         return -1;
3096 }
3097
3098 int
3099 x11_connect_display(void)
3100 {
3101         u_int display_number;
3102         const char *display;
3103         char buf[1024], *cp;
3104         struct addrinfo hints, *ai, *aitop;
3105         char strport[NI_MAXSERV];
3106         int gaierr, sock = 0;
3107
3108         /* Try to open a socket for the local X server. */
3109         display = getenv("DISPLAY");
3110         if (!display) {
3111                 error("DISPLAY not set.");
3112                 return -1;
3113         }
3114         /*
3115          * Now we decode the value of the DISPLAY variable and make a
3116          * connection to the real X server.
3117          */
3118
3119         /*
3120          * Check if it is a unix domain socket.  Unix domain displays are in
3121          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3122          */
3123         if (strncmp(display, "unix:", 5) == 0 ||
3124             display[0] == ':') {
3125                 /* Connect to the unix domain socket. */
3126                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3127                         error("Could not parse display number from DISPLAY: %.100s",
3128                             display);
3129                         return -1;
3130                 }
3131                 /* Create a socket. */
3132                 sock = connect_local_xsocket(display_number);
3133                 if (sock < 0)
3134                         return -1;
3135
3136                 /* OK, we now have a connection to the display. */
3137                 return sock;
3138         }
3139         /*
3140          * Connect to an inet socket.  The DISPLAY value is supposedly
3141          * hostname:d[.s], where hostname may also be numeric IP address.
3142          */
3143         strlcpy(buf, display, sizeof(buf));
3144         cp = strchr(buf, ':');
3145         if (!cp) {
3146                 error("Could not find ':' in DISPLAY: %.100s", display);
3147                 return -1;
3148         }
3149         *cp = 0;
3150         /* buf now contains the host name.  But first we parse the display number. */
3151         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3152                 error("Could not parse display number from DISPLAY: %.100s",
3153                     display);
3154                 return -1;
3155         }
3156
3157         /* Look up the host address */
3158         memset(&hints, 0, sizeof(hints));
3159         hints.ai_family = IPv4or6;
3160         hints.ai_socktype = SOCK_STREAM;
3161         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3162         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3163                 error("%.100s: unknown host. (%s)", buf,
3164                 ssh_gai_strerror(gaierr));
3165                 return -1;
3166         }
3167         for (ai = aitop; ai; ai = ai->ai_next) {
3168                 /* Create a socket. */
3169                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3170                 if (sock < 0) {
3171                         debug2("socket: %.100s", strerror(errno));
3172                         continue;
3173                 }
3174                 /* Connect it to the display. */
3175                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3176                         debug2("connect %.100s port %u: %.100s", buf,
3177                             6000 + display_number, strerror(errno));
3178                         close(sock);
3179                         continue;
3180                 }
3181                 /* Success */
3182                 break;
3183         }
3184         freeaddrinfo(aitop);
3185         if (!ai) {
3186                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3187                     strerror(errno));
3188                 return -1;
3189         }
3190         set_nodelay(sock);
3191         return sock;
3192 }
3193
3194 /*
3195  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3196  * the remote channel number.  We should do whatever we want, and respond
3197  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3198  */
3199
3200 /* ARGSUSED */
3201 void
3202 x11_input_open(int type, u_int32_t seq, void *ctxt)
3203 {
3204         Channel *c = NULL;
3205         int remote_id, sock = 0;
3206         char *remote_host;
3207
3208         debug("Received X11 open request.");
3209
3210         remote_id = packet_get_int();
3211
3212         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3213                 remote_host = packet_get_string(NULL);
3214         } else {
3215                 remote_host = xstrdup("unknown (remote did not supply name)");
3216         }
3217         packet_check_eom();
3218
3219         /* Obtain a connection to the real X display. */
3220         sock = x11_connect_display();
3221         if (sock != -1) {
3222                 /* Allocate a channel for this connection. */
3223                 c = channel_new("connected x11 socket",
3224                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3225                     remote_host, 1);
3226                 c->remote_id = remote_id;
3227                 c->force_drain = 1;
3228         }
3229         xfree(remote_host);
3230         if (c == NULL) {
3231                 /* Send refusal to the remote host. */
3232                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3233                 packet_put_int(remote_id);
3234         } else {
3235                 /* Send a confirmation to the remote host. */
3236                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3237                 packet_put_int(remote_id);
3238                 packet_put_int(c->self);
3239         }
3240         packet_send();
3241 }
3242
3243 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3244 /* ARGSUSED */
3245 void
3246 deny_input_open(int type, u_int32_t seq, void *ctxt)
3247 {
3248         int rchan = packet_get_int();
3249
3250         switch (type) {
3251         case SSH_SMSG_AGENT_OPEN:
3252                 error("Warning: ssh server tried agent forwarding.");
3253                 break;
3254         case SSH_SMSG_X11_OPEN:
3255                 error("Warning: ssh server tried X11 forwarding.");
3256                 break;
3257         default:
3258                 error("deny_input_open: type %d", type);
3259                 break;
3260         }
3261         error("Warning: this is probably a break-in attempt by a malicious server.");
3262         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3263         packet_put_int(rchan);
3264         packet_send();
3265 }
3266
3267 /*
3268  * Requests forwarding of X11 connections, generates fake authentication
3269  * data, and enables authentication spoofing.
3270  * This should be called in the client only.
3271  */
3272 void
3273 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3274     const char *proto, const char *data)
3275 {
3276         u_int data_len = (u_int) strlen(data) / 2;
3277         u_int i, value;
3278         char *new_data;
3279         int screen_number;
3280         const char *cp;
3281         u_int32_t rnd = 0;
3282
3283         if (x11_saved_display == NULL)
3284                 x11_saved_display = xstrdup(disp);
3285         else if (strcmp(disp, x11_saved_display) != 0) {
3286                 error("x11_request_forwarding_with_spoofing: different "
3287                     "$DISPLAY already forwarded");
3288                 return;
3289         }
3290
3291         cp = strchr(disp, ':');
3292         if (cp)
3293                 cp = strchr(cp, '.');
3294         if (cp)
3295                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3296         else
3297                 screen_number = 0;
3298
3299         if (x11_saved_proto == NULL) {
3300                 /* Save protocol name. */
3301                 x11_saved_proto = xstrdup(proto);
3302                 /*
3303                  * Extract real authentication data and generate fake data
3304                  * of the same length.
3305                  */
3306                 x11_saved_data = xmalloc(data_len);
3307                 x11_fake_data = xmalloc(data_len);
3308                 for (i = 0; i < data_len; i++) {
3309                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3310                                 fatal("x11_request_forwarding: bad "
3311                                     "authentication data: %.100s", data);
3312                         if (i % 4 == 0)
3313                                 rnd = arc4random();
3314                         x11_saved_data[i] = value;
3315                         x11_fake_data[i] = rnd & 0xff;
3316                         rnd >>= 8;
3317                 }
3318                 x11_saved_data_len = data_len;
3319                 x11_fake_data_len = data_len;
3320         }
3321
3322         /* Convert the fake data into hex. */
3323         new_data = tohex(x11_fake_data, data_len);
3324
3325         /* Send the request packet. */
3326         if (compat20) {
3327                 channel_request_start(client_session_id, "x11-req", 0);
3328                 packet_put_char(0);     /* XXX bool single connection */
3329         } else {
3330                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3331         }
3332         packet_put_cstring(proto);
3333         packet_put_cstring(new_data);
3334         packet_put_int(screen_number);
3335         packet_send();
3336         packet_write_wait();
3337         xfree(new_data);
3338 }
3339
3340
3341 /* -- agent forwarding */
3342
3343 /* Sends a message to the server to request authentication fd forwarding. */
3344
3345 void
3346 auth_request_forwarding(void)
3347 {
3348         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3349         packet_send();
3350         packet_write_wait();
3351 }