crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.303 2010/01/30 21:12:08 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <netdb.h>
  58 #include <stdio.h>
  59 #include <stdlib.h>
  60 #include <string.h>
  61 #include <termios.h>
  62 #include <unistd.h>
  63 #include <stdarg.h>
  64
  65 #include "openbsd-compat/sys-queue.h"
  66 #include "xmalloc.h"
  67 #include "ssh.h"
  68 #include "ssh1.h"
  69 #include "ssh2.h"
  70 #include "packet.h"
  71 #include "log.h"
  72 #include "misc.h"
  73 #include "buffer.h"
  74 #include "channels.h"
  75 #include "compat.h"
  76 #include "canohost.h"
  77 #include "key.h"
  78 #include "authfd.h"
  79 #include "pathnames.h"
  80
  81 /* -- channel core */
  82
  83 /*
  84  * Pointer to an array containing all allocated channels.  The array is
  85  * dynamically extended as needed.
  86  */
  87 static Channel **channels = NULL;
  88
  89 /*
  90  * Size of the channel array.  All slots of the array must always be
  91  * initialized (at least the type field); unused slots set to NULL
  92  */
  93 static u_int channels_alloc = 0;
  94
  95 /*
  96  * Maximum file descriptor value used in any of the channels.  This is
  97  * updated in channel_new.
  98  */
  99 static int channel_max_fd = 0;
 100
 101
 102 /* -- tcp forwarding */
 103
 104 /*
 105  * Data structure for storing which hosts are permitted for forward requests.
 106  * The local sides of any remote forwards are stored in this array to prevent
 107  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 108  * network (which might be behind a firewall).
 109  */
 110 typedef struct {
 111         char *host_to_connect;          /* Connect to 'host'. */
 112         u_short port_to_connect;        /* Connect to 'port'. */
 113         u_short listen_port;            /* Remote side should listen port number. */
 114 } ForwardPermission;
 115
 116 /* List of all permitted host/port pairs to connect by the user. */
 117 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 118
 119 /* List of all permitted host/port pairs to connect by the admin. */
 120 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 121
 122 /* Number of permitted host/port pairs in the array permitted by the user. */
 123 static int num_permitted_opens = 0;
 124
 125 /* Number of permitted host/port pair in the array permitted by the admin. */
 126 static int num_adm_permitted_opens = 0;
 127
 128 /*
 129  * If this is true, all opens are permitted.  This is the case on the server
 130  * on which we have to trust the client anyway, and the user could do
 131  * anything after logging in anyway.
 132  */
 133 static int all_opens_permitted = 0;
 134
 135
 136 /* -- X11 forwarding */
 137
 138 /* Maximum number of fake X11 displays to try. */
 139 #define MAX_DISPLAYS  1000
 140
 141 /* Saved X11 local (client) display. */
 142 static char *x11_saved_display = NULL;
 143
 144 /* Saved X11 authentication protocol name. */
 145 static char *x11_saved_proto = NULL;
 146
 147 /* Saved X11 authentication data.  This is the real data. */
 148 static char *x11_saved_data = NULL;
 149 static u_int x11_saved_data_len = 0;
 150
 151 /*
 152  * Fake X11 authentication data.  This is what the server will be sending us;
 153  * we should replace any occurrences of this by the real data.
 154  */
 155 static u_char *x11_fake_data = NULL;
 156 static u_int x11_fake_data_len;
 157
 158
 159 /* -- agent forwarding */
 160
 161 #define NUM_SOCKS       10
 162
 163 /* AF_UNSPEC or AF_INET or AF_INET6 */
 164 static int IPv4or6 = AF_UNSPEC;
 165
 166 /* helper */
 167 static void port_open_helper(Channel *c, char *rtype);
 168
 169 /* non-blocking connect helpers */
 170 static int connect_next(struct channel_connect *);
 171 static void channel_connect_ctx_free(struct channel_connect *);
 172
 173 /* -- channel core */
 174
 175 Channel *
 176 channel_by_id(int id)
 177 {
 178         Channel *c;
 179
 180         if (id < 0 || (u_int)id >= channels_alloc) {
 181                 logit("channel_by_id: %d: bad id", id);
 182                 return NULL;
 183         }
 184         c = channels[id];
 185         if (c == NULL) {
 186                 logit("channel_by_id: %d: bad id: channel free", id);
 187                 return NULL;
 188         }
 189         return c;
 190 }
 191
 192 /*
 193  * Returns the channel if it is allowed to receive protocol messages.
 194  * Private channels, like listening sockets, may not receive messages.
 195  */
 196 Channel *
 197 channel_lookup(int id)
 198 {
 199         Channel *c;
 200
 201         if ((c = channel_by_id(id)) == NULL)
 202                 return (NULL);
 203
 204         switch (c->type) {
 205         case SSH_CHANNEL_X11_OPEN:
 206         case SSH_CHANNEL_LARVAL:
 207         case SSH_CHANNEL_CONNECTING:
 208         case SSH_CHANNEL_DYNAMIC:
 209         case SSH_CHANNEL_OPENING:
 210         case SSH_CHANNEL_OPEN:
 211         case SSH_CHANNEL_INPUT_DRAINING:
 212         case SSH_CHANNEL_OUTPUT_DRAINING:
 213                 return (c);
 214         }
 215         logit("Non-public channel %d, type %d.", id, c->type);
 216         return (NULL);
 217 }
 218
 219 /*
 220  * Register filedescriptors for a channel, used when allocating a channel or
 221  * when the channel consumer/producer is ready, e.g. shell exec'd
 222  */
 223 static void
 224 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 225     int extusage, int nonblock, int is_tty)
 226 {
 227         /* Update the maximum file descriptor value. */
 228         channel_max_fd = MAX(channel_max_fd, rfd);
 229         channel_max_fd = MAX(channel_max_fd, wfd);
 230         channel_max_fd = MAX(channel_max_fd, efd);
 231
 232         if (rfd != -1)
 233                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 234         if (wfd != -1 && wfd != rfd)
 235                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 236         if (efd != -1 && efd != rfd && efd != wfd)
 237                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 238
 239         c->rfd = rfd;
 240         c->wfd = wfd;
 241         c->sock = (rfd == wfd) ? rfd : -1;
 242         c->efd = efd;
 243         c->extended_usage = extusage;
 244
 245         if ((c->isatty = is_tty) != 0)
 246                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 247         c->wfd_isatty = is_tty || isatty(c->wfd);
 248
 249         /* enable nonblocking mode */
 250         if (nonblock) {
 251                 if (rfd != -1)
 252                         set_nonblock(rfd);
 253                 if (wfd != -1)
 254                         set_nonblock(wfd);
 255                 if (efd != -1)
 256                         set_nonblock(efd);
 257         }
 258 }
 259
 260 /*
 261  * Allocate a new channel object and set its type and socket. This will cause
 262  * remote_name to be freed.
 263  */
 264 Channel *
 265 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 266     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 267 {
 268         int found;
 269         u_int i;
 270         Channel *c;
 271
 272         /* Do initial allocation if this is the first call. */
 273         if (channels_alloc == 0) {
 274                 channels_alloc = 10;
 275                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 276                 for (i = 0; i < channels_alloc; i++)
 277                         channels[i] = NULL;
 278         }
 279         /* Try to find a free slot where to put the new channel. */
 280         for (found = -1, i = 0; i < channels_alloc; i++)
 281                 if (channels[i] == NULL) {
 282                         /* Found a free slot. */
 283                         found = (int)i;
 284                         break;
 285                 }
 286         if (found < 0) {
 287                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 288                 found = channels_alloc;
 289                 if (channels_alloc > 10000)
 290                         fatal("channel_new: internal error: channels_alloc %d "
 291                             "too big.", channels_alloc);
 292                 channels = xrealloc(channels, channels_alloc + 10,
 293                     sizeof(Channel *));
 294                 channels_alloc += 10;
 295                 debug2("channel: expanding %d", channels_alloc);
 296                 for (i = found; i < channels_alloc; i++)
 297                         channels[i] = NULL;
 298         }
 299         /* Initialize and return new channel. */
 300         c = channels[found] = xcalloc(1, sizeof(Channel));
 301         buffer_init(&c->input);
 302         buffer_init(&c->output);
 303         buffer_init(&c->extended);
 304         c->path = NULL;
 305         c->ostate = CHAN_OUTPUT_OPEN;
 306         c->istate = CHAN_INPUT_OPEN;
 307         c->flags = 0;
 308         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 309         c->self = found;
 310         c->type = type;
 311         c->ctype = ctype;
 312         c->local_window = window;
 313         c->local_window_max = window;
 314         c->local_consumed = 0;
 315         c->local_maxpacket = maxpack;
 316         c->remote_id = -1;
 317         c->remote_name = xstrdup(remote_name);
 318         c->remote_window = 0;
 319         c->remote_maxpacket = 0;
 320         c->force_drain = 0;
 321         c->single_connection = 0;
 322         c->detach_user = NULL;
 323         c->detach_close = 0;
 324         c->open_confirm = NULL;
 325         c->open_confirm_ctx = NULL;
 326         c->input_filter = NULL;
 327         c->output_filter = NULL;
 328         c->filter_ctx = NULL;
 329         c->filter_cleanup = NULL;
 330         c->ctl_chan = -1;
 331         c->mux_rcb = NULL;
 332         c->mux_ctx = NULL;
 333         c->delayed = 1;         /* prevent call to channel_post handler */
 334         TAILQ_INIT(&c->status_confirms);
 335         debug("channel %d: new [%s]", found, remote_name);
 336         return c;
 337 }
 338
 339 static int
 340 channel_find_maxfd(void)
 341 {
 342         u_int i;
 343         int max = 0;
 344         Channel *c;
 345
 346         for (i = 0; i < channels_alloc; i++) {
 347                 c = channels[i];
 348                 if (c != NULL) {
 349                         max = MAX(max, c->rfd);
 350                         max = MAX(max, c->wfd);
 351                         max = MAX(max, c->efd);
 352                 }
 353         }
 354         return max;
 355 }
 356
 357 int
 358 channel_close_fd(int *fdp)
 359 {
 360         int ret = 0, fd = *fdp;
 361
 362         if (fd != -1) {
 363                 ret = close(fd);
 364                 *fdp = -1;
 365                 if (fd == channel_max_fd)
 366                         channel_max_fd = channel_find_maxfd();
 367         }
 368         return ret;
 369 }
 370
 371 /* Close all channel fd/socket. */
 372 static void
 373 channel_close_fds(Channel *c)
 374 {
 375         debug3("channel %d: close_fds r %d w %d e %d",
 376             c->self, c->rfd, c->wfd, c->efd);
 377
 378         channel_close_fd(&c->sock);
 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         channel_close_fds(c);
 405         buffer_free(&c->input);
 406         buffer_free(&c->output);
 407         buffer_free(&c->extended);
 408         if (c->remote_name) {
 409                 xfree(c->remote_name);
 410                 c->remote_name = NULL;
 411         }
 412         if (c->path) {
 413                 xfree(c->path);
 414                 c->path = NULL;
 415         }
 416         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 417                 if (cc->abandon_cb != NULL)
 418                         cc->abandon_cb(c, cc->ctx);
 419                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 420                 bzero(cc, sizeof(*cc));
 421                 xfree(cc);
 422         }
 423         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 424                 c->filter_cleanup(c->self, c->filter_ctx);
 425         channels[c->self] = NULL;
 426         xfree(c);
 427 }
 428
 429 void
 430 channel_free_all(void)
 431 {
 432         u_int i;
 433
 434         for (i = 0; i < channels_alloc; i++)
 435                 if (channels[i] != NULL)
 436                         channel_free(channels[i]);
 437 }
 438
 439 /*
 440  * Closes the sockets/fds of all channels.  This is used to close extra file
 441  * descriptors after a fork.
 442  */
 443 void
 444 channel_close_all(void)
 445 {
 446         u_int i;
 447
 448         for (i = 0; i < channels_alloc; i++)
 449                 if (channels[i] != NULL)
 450                         channel_close_fds(channels[i]);
 451 }
 452
 453 /*
 454  * Stop listening to channels.
 455  */
 456 void
 457 channel_stop_listening(void)
 458 {
 459         u_int i;
 460         Channel *c;
 461
 462         for (i = 0; i < channels_alloc; i++) {
 463                 c = channels[i];
 464                 if (c != NULL) {
 465                         switch (c->type) {
 466                         case SSH_CHANNEL_AUTH_SOCKET:
 467                         case SSH_CHANNEL_PORT_LISTENER:
 468                         case SSH_CHANNEL_RPORT_LISTENER:
 469                         case SSH_CHANNEL_X11_LISTENER:
 470                                 channel_close_fd(&c->sock);
 471                                 channel_free(c);
 472                                 break;
 473                         }
 474                 }
 475         }
 476 }
 477
 478 /*
 479  * Returns true if no channel has too much buffered data, and false if one or
 480  * more channel is overfull.
 481  */
 482 int
 483 channel_not_very_much_buffered_data(void)
 484 {
 485         u_int i;
 486         Channel *c;
 487
 488         for (i = 0; i < channels_alloc; i++) {
 489                 c = channels[i];
 490                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 491 #if 0
 492                         if (!compat20 &&
 493                             buffer_len(&c->input) > packet_get_maxsize()) {
 494                                 debug2("channel %d: big input buffer %d",
 495                                     c->self, buffer_len(&c->input));
 496                                 return 0;
 497                         }
 498 #endif
 499                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 500                                 debug2("channel %d: big output buffer %u > %u",
 501                                     c->self, buffer_len(&c->output),
 502                                     packet_get_maxsize());
 503                                 return 0;
 504                         }
 505                 }
 506         }
 507         return 1;
 508 }
 509
 510 /* Returns true if any channel is still open. */
 511 int
 512 channel_still_open(void)
 513 {
 514         u_int i;
 515         Channel *c;
 516
 517         for (i = 0; i < channels_alloc; i++) {
 518                 c = channels[i];
 519                 if (c == NULL)
 520                         continue;
 521                 switch (c->type) {
 522                 case SSH_CHANNEL_X11_LISTENER:
 523                 case SSH_CHANNEL_PORT_LISTENER:
 524                 case SSH_CHANNEL_RPORT_LISTENER:
 525                 case SSH_CHANNEL_MUX_LISTENER:
 526                 case SSH_CHANNEL_CLOSED:
 527                 case SSH_CHANNEL_AUTH_SOCKET:
 528                 case SSH_CHANNEL_DYNAMIC:
 529                 case SSH_CHANNEL_CONNECTING:
 530                 case SSH_CHANNEL_ZOMBIE:
 531                         continue;
 532                 case SSH_CHANNEL_LARVAL:
 533                         if (!compat20)
 534                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 535                         continue;
 536                 case SSH_CHANNEL_OPENING:
 537                 case SSH_CHANNEL_OPEN:
 538                 case SSH_CHANNEL_X11_OPEN:
 539                 case SSH_CHANNEL_MUX_CLIENT:
 540                         return 1;
 541                 case SSH_CHANNEL_INPUT_DRAINING:
 542                 case SSH_CHANNEL_OUTPUT_DRAINING:
 543                         if (!compat13)
 544                                 fatal("cannot happen: OUT_DRAIN");
 545                         return 1;
 546                 default:
 547                         fatal("channel_still_open: bad channel type %d", c->type);
 548                         /* NOTREACHED */
 549                 }
 550         }
 551         return 0;
 552 }
 553
 554 /* Returns the id of an open channel suitable for keepaliving */
 555 int
 556 channel_find_open(void)
 557 {
 558         u_int i;
 559         Channel *c;
 560
 561         for (i = 0; i < channels_alloc; i++) {
 562                 c = channels[i];
 563                 if (c == NULL || c->remote_id < 0)
 564                         continue;
 565                 switch (c->type) {
 566                 case SSH_CHANNEL_CLOSED:
 567                 case SSH_CHANNEL_DYNAMIC:
 568                 case SSH_CHANNEL_X11_LISTENER:
 569                 case SSH_CHANNEL_PORT_LISTENER:
 570                 case SSH_CHANNEL_RPORT_LISTENER:
 571                 case SSH_CHANNEL_MUX_LISTENER:
 572                 case SSH_CHANNEL_MUX_CLIENT:
 573                 case SSH_CHANNEL_OPENING:
 574                 case SSH_CHANNEL_CONNECTING:
 575                 case SSH_CHANNEL_ZOMBIE:
 576                         continue;
 577                 case SSH_CHANNEL_LARVAL:
 578                 case SSH_CHANNEL_AUTH_SOCKET:
 579                 case SSH_CHANNEL_OPEN:
 580                 case SSH_CHANNEL_X11_OPEN:
 581                         return i;
 582                 case SSH_CHANNEL_INPUT_DRAINING:
 583                 case SSH_CHANNEL_OUTPUT_DRAINING:
 584                         if (!compat13)
 585                                 fatal("cannot happen: OUT_DRAIN");
 586                         return i;
 587                 default:
 588                         fatal("channel_find_open: bad channel type %d", c->type);
 589                         /* NOTREACHED */
 590                 }
 591         }
 592         return -1;
 593 }
 594
 595
 596 /*
 597  * Returns a message describing the currently open forwarded connections,
 598  * suitable for sending to the client.  The message contains crlf pairs for
 599  * newlines.
 600  */
 601 char *
 602 channel_open_message(void)
 603 {
 604         Buffer buffer;
 605         Channel *c;
 606         char buf[1024], *cp;
 607         u_int i;
 608
 609         buffer_init(&buffer);
 610         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 611         buffer_append(&buffer, buf, strlen(buf));
 612         for (i = 0; i < channels_alloc; i++) {
 613                 c = channels[i];
 614                 if (c == NULL)
 615                         continue;
 616                 switch (c->type) {
 617                 case SSH_CHANNEL_X11_LISTENER:
 618                 case SSH_CHANNEL_PORT_LISTENER:
 619                 case SSH_CHANNEL_RPORT_LISTENER:
 620                 case SSH_CHANNEL_CLOSED:
 621                 case SSH_CHANNEL_AUTH_SOCKET:
 622                 case SSH_CHANNEL_ZOMBIE:
 623                 case SSH_CHANNEL_MUX_CLIENT:
 624                 case SSH_CHANNEL_MUX_LISTENER:
 625                         continue;
 626                 case SSH_CHANNEL_LARVAL:
 627                 case SSH_CHANNEL_OPENING:
 628                 case SSH_CHANNEL_CONNECTING:
 629                 case SSH_CHANNEL_DYNAMIC:
 630                 case SSH_CHANNEL_OPEN:
 631                 case SSH_CHANNEL_X11_OPEN:
 632                 case SSH_CHANNEL_INPUT_DRAINING:
 633                 case SSH_CHANNEL_OUTPUT_DRAINING:
 634                         snprintf(buf, sizeof buf,
 635                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cc %d)\r\n",
 636                             c->self, c->remote_name,
 637                             c->type, c->remote_id,
 638                             c->istate, buffer_len(&c->input),
 639                             c->ostate, buffer_len(&c->output),
 640                             c->rfd, c->wfd, c->ctl_chan);
 641                         buffer_append(&buffer, buf, strlen(buf));
 642                         continue;
 643                 default:
 644                         fatal("channel_open_message: bad channel type %d", c->type);
 645                         /* NOTREACHED */
 646                 }
 647         }
 648         buffer_append(&buffer, "\0", 1);
 649         cp = xstrdup(buffer_ptr(&buffer));
 650         buffer_free(&buffer);
 651         return cp;
 652 }
 653
 654 void
 655 channel_send_open(int id)
 656 {
 657         Channel *c = channel_lookup(id);
 658
 659         if (c == NULL) {
 660                 logit("channel_send_open: %d: bad id", id);
 661                 return;
 662         }
 663         debug2("channel %d: send open", id);
 664         packet_start(SSH2_MSG_CHANNEL_OPEN);
 665         packet_put_cstring(c->ctype);
 666         packet_put_int(c->self);
 667         packet_put_int(c->local_window);
 668         packet_put_int(c->local_maxpacket);
 669         packet_send();
 670 }
 671
 672 void
 673 channel_request_start(int id, char *service, int wantconfirm)
 674 {
 675         Channel *c = channel_lookup(id);
 676
 677         if (c == NULL) {
 678                 logit("channel_request_start: %d: unknown channel id", id);
 679                 return;
 680         }
 681         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 682         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 683         packet_put_int(c->remote_id);
 684         packet_put_cstring(service);
 685         packet_put_char(wantconfirm);
 686 }
 687
 688 void
 689 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 690     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 691 {
 692         struct channel_confirm *cc;
 693         Channel *c;
 694
 695         if ((c = channel_lookup(id)) == NULL)
 696                 fatal("channel_register_expect: %d: bad id", id);
 697
 698         cc = xmalloc(sizeof(*cc));
 699         cc->cb = cb;
 700         cc->abandon_cb = abandon_cb;
 701         cc->ctx = ctx;
 702         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 703 }
 704
 705 void
 706 channel_register_open_confirm(int id, channel_callback_fn *fn, void *ctx)
 707 {
 708         Channel *c = channel_lookup(id);
 709
 710         if (c == NULL) {
 711                 logit("channel_register_open_confirm: %d: bad id", id);
 712                 return;
 713         }
 714         c->open_confirm = fn;
 715         c->open_confirm_ctx = ctx;
 716 }
 717
 718 void
 719 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 720 {
 721         Channel *c = channel_by_id(id);
 722
 723         if (c == NULL) {
 724                 logit("channel_register_cleanup: %d: bad id", id);
 725                 return;
 726         }
 727         c->detach_user = fn;
 728         c->detach_close = do_close;
 729 }
 730
 731 void
 732 channel_cancel_cleanup(int id)
 733 {
 734         Channel *c = channel_by_id(id);
 735
 736         if (c == NULL) {
 737                 logit("channel_cancel_cleanup: %d: bad id", id);
 738                 return;
 739         }
 740         c->detach_user = NULL;
 741         c->detach_close = 0;
 742 }
 743
 744 void
 745 channel_register_filter(int id, channel_infilter_fn *ifn,
 746     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 747 {
 748         Channel *c = channel_lookup(id);
 749
 750         if (c == NULL) {
 751                 logit("channel_register_filter: %d: bad id", id);
 752                 return;
 753         }
 754         c->input_filter = ifn;
 755         c->output_filter = ofn;
 756         c->filter_ctx = ctx;
 757         c->filter_cleanup = cfn;
 758 }
 759
 760 void
 761 channel_set_fds(int id, int rfd, int wfd, int efd,
 762     int extusage, int nonblock, int is_tty, u_int window_max)
 763 {
 764         Channel *c = channel_lookup(id);
 765
 766         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 767                 fatal("channel_activate for non-larval channel %d.", id);
 768         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 769         c->type = SSH_CHANNEL_OPEN;
 770         c->local_window = c->local_window_max = window_max;
 771         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 772         packet_put_int(c->remote_id);
 773         packet_put_int(c->local_window);
 774         packet_send();
 775 }
 776
 777 /*
 778  * 'channel_pre*' are called just before select() to add any bits relevant to
 779  * channels in the select bitmasks.
 780  */
 781 /*
 782  * 'channel_post*': perform any appropriate operations for channels which
 783  * have events pending.
 784  */
 785 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 786 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 787 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 788
 789 /* ARGSUSED */
 790 static void
 791 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 792 {
 793         FD_SET(c->sock, readset);
 794 }
 795
 796 /* ARGSUSED */
 797 static void
 798 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 799 {
 800         debug3("channel %d: waiting for connection", c->self);
 801         FD_SET(c->sock, writeset);
 802 }
 803
 804 static void
 805 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 806 {
 807         if (buffer_len(&c->input) < packet_get_maxsize())
 808                 FD_SET(c->sock, readset);
 809         if (buffer_len(&c->output) > 0)
 810                 FD_SET(c->sock, writeset);
 811 }
 812
 813 static void
 814 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 815 {
 816         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 817
 818         if (c->istate == CHAN_INPUT_OPEN &&
 819             limit > 0 &&
 820             buffer_len(&c->input) < limit &&
 821             buffer_check_alloc(&c->input, CHAN_RBUF))
 822                 FD_SET(c->rfd, readset);
 823         if (c->ostate == CHAN_OUTPUT_OPEN ||
 824             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 825                 if (buffer_len(&c->output) > 0) {
 826                         FD_SET(c->wfd, writeset);
 827                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 828                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 829                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 830                                     c->self, c->efd, buffer_len(&c->extended));
 831                         else
 832                                 chan_obuf_empty(c);
 833                 }
 834         }
 835         /** XXX check close conditions, too */
 836         if (compat20 && c->efd != -1 &&
 837             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 838                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 839                     buffer_len(&c->extended) > 0)
 840                         FD_SET(c->efd, writeset);
 841                 else if (!(c->flags & CHAN_EOF_SENT) &&
 842                     c->extended_usage == CHAN_EXTENDED_READ &&
 843                     buffer_len(&c->extended) < c->remote_window)
 844                         FD_SET(c->efd, readset);
 845         }
 846         /* XXX: What about efd? races? */
 847 }
 848
 849 /* ARGSUSED */
 850 static void
 851 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 852 {
 853         if (buffer_len(&c->input) == 0) {
 854                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 855                 packet_put_int(c->remote_id);
 856                 packet_send();
 857                 c->type = SSH_CHANNEL_CLOSED;
 858                 debug2("channel %d: closing after input drain.", c->self);
 859         }
 860 }
 861
 862 /* ARGSUSED */
 863 static void
 864 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 865 {
 866         if (buffer_len(&c->output) == 0)
 867                 chan_mark_dead(c);
 868         else
 869                 FD_SET(c->sock, writeset);
 870 }
 871
 872 /*
 873  * This is a special state for X11 authentication spoofing.  An opened X11
 874  * connection (when authentication spoofing is being done) remains in this
 875  * state until the first packet has been completely read.  The authentication
 876  * data in that packet is then substituted by the real data if it matches the
 877  * fake data, and the channel is put into normal mode.
 878  * XXX All this happens at the client side.
 879  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 880  */
 881 static int
 882 x11_open_helper(Buffer *b)
 883 {
 884         u_char *ucp;
 885         u_int proto_len, data_len;
 886
 887         /* Check if the fixed size part of the packet is in buffer. */
 888         if (buffer_len(b) < 12)
 889                 return 0;
 890
 891         /* Parse the lengths of variable-length fields. */
 892         ucp = buffer_ptr(b);
 893         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 894                 proto_len = 256 * ucp[6] + ucp[7];
 895                 data_len = 256 * ucp[8] + ucp[9];
 896         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 897                 proto_len = ucp[6] + 256 * ucp[7];
 898                 data_len = ucp[8] + 256 * ucp[9];
 899         } else {
 900                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 901                     ucp[0]);
 902                 return -1;
 903         }
 904
 905         /* Check if the whole packet is in buffer. */
 906         if (buffer_len(b) <
 907             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 908                 return 0;
 909
 910         /* Check if authentication protocol matches. */
 911         if (proto_len != strlen(x11_saved_proto) ||
 912             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 913                 debug2("X11 connection uses different authentication protocol.");
 914                 return -1;
 915         }
 916         /* Check if authentication data matches our fake data. */
 917         if (data_len != x11_fake_data_len ||
 918             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 919                 x11_fake_data, x11_fake_data_len) != 0) {
 920                 debug2("X11 auth data does not match fake data.");
 921                 return -1;
 922         }
 923         /* Check fake data length */
 924         if (x11_fake_data_len != x11_saved_data_len) {
 925                 error("X11 fake_data_len %d != saved_data_len %d",
 926                     x11_fake_data_len, x11_saved_data_len);
 927                 return -1;
 928         }
 929         /*
 930          * Received authentication protocol and data match
 931          * our fake data. Substitute the fake data with real
 932          * data.
 933          */
 934         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 935             x11_saved_data, x11_saved_data_len);
 936         return 1;
 937 }
 938
 939 static void
 940 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 941 {
 942         int ret = x11_open_helper(&c->output);
 943
 944         if (ret == 1) {
 945                 /* Start normal processing for the channel. */
 946                 c->type = SSH_CHANNEL_OPEN;
 947                 channel_pre_open_13(c, readset, writeset);
 948         } else if (ret == -1) {
 949                 /*
 950                  * We have received an X11 connection that has bad
 951                  * authentication information.
 952                  */
 953                 logit("X11 connection rejected because of wrong authentication.");
 954                 buffer_clear(&c->input);
 955                 buffer_clear(&c->output);
 956                 channel_close_fd(&c->sock);
 957                 c->sock = -1;
 958                 c->type = SSH_CHANNEL_CLOSED;
 959                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 960                 packet_put_int(c->remote_id);
 961                 packet_send();
 962         }
 963 }
 964
 965 static void
 966 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 967 {
 968         int ret = x11_open_helper(&c->output);
 969
 970         /* c->force_drain = 1; */
 971
 972         if (ret == 1) {
 973                 c->type = SSH_CHANNEL_OPEN;
 974                 channel_pre_open(c, readset, writeset);
 975         } else if (ret == -1) {
 976                 logit("X11 connection rejected because of wrong authentication.");
 977                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 978                 chan_read_failed(c);
 979                 buffer_clear(&c->input);
 980                 chan_ibuf_empty(c);
 981                 buffer_clear(&c->output);
 982                 /* for proto v1, the peer will send an IEOF */
 983                 if (compat20)
 984                         chan_write_failed(c);
 985                 else
 986                         c->type = SSH_CHANNEL_OPEN;
 987                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 988         }
 989 }
 990
 991 static void
 992 channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
 993 {
 994         if (c->istate == CHAN_INPUT_OPEN &&
 995             buffer_check_alloc(&c->input, CHAN_RBUF))
 996                 FD_SET(c->rfd, readset);
 997         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
 998                 /* clear buffer immediately (discard any partial packet) */
 999                 buffer_clear(&c->input);
1000                 chan_ibuf_empty(c);
1001                 /* Start output drain. XXX just kill chan? */
1002                 chan_rcvd_oclose(c);
1003         }
1004         if (c->ostate == CHAN_OUTPUT_OPEN ||
1005             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
1006                 if (buffer_len(&c->output) > 0)
1007                         FD_SET(c->wfd, writeset);
1008                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
1009                         chan_obuf_empty(c);
1010         }
1011 }
1012
1013 /* try to decode a socks4 header */
1014 /* ARGSUSED */
1015 static int
1016 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1017 {
1018         char *p, *host;
1019         u_int len, have, i, found, need;
1020         char username[256];
1021         struct {
1022                 u_int8_t version;
1023                 u_int8_t command;
1024                 u_int16_t dest_port;
1025                 struct in_addr dest_addr;
1026         } s4_req, s4_rsp;
1027
1028         debug2("channel %d: decode socks4", c->self);
1029
1030         have = buffer_len(&c->input);
1031         len = sizeof(s4_req);
1032         if (have < len)
1033                 return 0;
1034         p = buffer_ptr(&c->input);
1035
1036         need = 1;
1037         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1038         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1039                 debug2("channel %d: socks4a request", c->self);
1040                 /* ... and needs an extra string (the hostname) */
1041                 need = 2;
1042         }
1043         /* Check for terminating NUL on the string(s) */
1044         for (found = 0, i = len; i < have; i++) {
1045                 if (p[i] == '\0') {
1046                         found++;
1047                         if (found == need)
1048                                 break;
1049                 }
1050                 if (i > 1024) {
1051                         /* the peer is probably sending garbage */
1052                         debug("channel %d: decode socks4: too long",
1053                             c->self);
1054                         return -1;
1055                 }
1056         }
1057         if (found < need)
1058                 return 0;
1059         buffer_get(&c->input, (char *)&s4_req.version, 1);
1060         buffer_get(&c->input, (char *)&s4_req.command, 1);
1061         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1062         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1063         have = buffer_len(&c->input);
1064         p = buffer_ptr(&c->input);
1065         len = strlen(p);
1066         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1067         len++;                                  /* trailing '\0' */
1068         if (len > have)
1069                 fatal("channel %d: decode socks4: len %d > have %d",
1070                     c->self, len, have);
1071         strlcpy(username, p, sizeof(username));
1072         buffer_consume(&c->input, len);
1073
1074         if (c->path != NULL) {
1075                 xfree(c->path);
1076                 c->path = NULL;
1077         }
1078         if (need == 1) {                        /* SOCKS4: one string */
1079                 host = inet_ntoa(s4_req.dest_addr);
1080                 c->path = xstrdup(host);
1081         } else {                                /* SOCKS4A: two strings */
1082                 have = buffer_len(&c->input);
1083                 p = buffer_ptr(&c->input);
1084                 len = strlen(p);
1085                 debug2("channel %d: decode socks4a: host %s/%d",
1086                     c->self, p, len);
1087                 len++;                          /* trailing '\0' */
1088                 if (len > have)
1089                         fatal("channel %d: decode socks4a: len %d > have %d",
1090                             c->self, len, have);
1091                 if (len > NI_MAXHOST) {
1092                         error("channel %d: hostname \"%.100s\" too long",
1093                             c->self, p);
1094                         return -1;
1095                 }
1096                 c->path = xstrdup(p);
1097                 buffer_consume(&c->input, len);
1098         }
1099         c->host_port = ntohs(s4_req.dest_port);
1100
1101         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1102             c->self, c->path, c->host_port, s4_req.command);
1103
1104         if (s4_req.command != 1) {
1105                 debug("channel %d: cannot handle: %s cn %d",
1106                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1107                 return -1;
1108         }
1109         s4_rsp.version = 0;                     /* vn: 0 for reply */
1110         s4_rsp.command = 90;                    /* cd: req granted */
1111         s4_rsp.dest_port = 0;                   /* ignored */
1112         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1113         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1114         return 1;
1115 }
1116
1117 /* try to decode a socks5 header */
1118 #define SSH_SOCKS5_AUTHDONE     0x1000
1119 #define SSH_SOCKS5_NOAUTH       0x00
1120 #define SSH_SOCKS5_IPV4         0x01
1121 #define SSH_SOCKS5_DOMAIN       0x03
1122 #define SSH_SOCKS5_IPV6         0x04
1123 #define SSH_SOCKS5_CONNECT      0x01
1124 #define SSH_SOCKS5_SUCCESS      0x00
1125
1126 /* ARGSUSED */
1127 static int
1128 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1129 {
1130         struct {
1131                 u_int8_t version;
1132                 u_int8_t command;
1133                 u_int8_t reserved;
1134                 u_int8_t atyp;
1135         } s5_req, s5_rsp;
1136         u_int16_t dest_port;
1137         u_char *p, dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1138         u_int have, need, i, found, nmethods, addrlen, af;
1139
1140         debug2("channel %d: decode socks5", c->self);
1141         p = buffer_ptr(&c->input);
1142         if (p[0] != 0x05)
1143                 return -1;
1144         have = buffer_len(&c->input);
1145         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1146                 /* format: ver | nmethods | methods */
1147                 if (have < 2)
1148                         return 0;
1149                 nmethods = p[1];
1150                 if (have < nmethods + 2)
1151                         return 0;
1152                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1153                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1154                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1155                                 found = 1;
1156                                 break;
1157                         }
1158                 }
1159                 if (!found) {
1160                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1161                             c->self);
1162                         return -1;
1163                 }
1164                 buffer_consume(&c->input, nmethods + 2);
1165                 buffer_put_char(&c->output, 0x05);              /* version */
1166                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1167                 FD_SET(c->sock, writeset);
1168                 c->flags |= SSH_SOCKS5_AUTHDONE;
1169                 debug2("channel %d: socks5 auth done", c->self);
1170                 return 0;                               /* need more */
1171         }
1172         debug2("channel %d: socks5 post auth", c->self);
1173         if (have < sizeof(s5_req)+1)
1174                 return 0;                       /* need more */
1175         memcpy(&s5_req, p, sizeof(s5_req));
1176         if (s5_req.version != 0x05 ||
1177             s5_req.command != SSH_SOCKS5_CONNECT ||
1178             s5_req.reserved != 0x00) {
1179                 debug2("channel %d: only socks5 connect supported", c->self);
1180                 return -1;
1181         }
1182         switch (s5_req.atyp){
1183         case SSH_SOCKS5_IPV4:
1184                 addrlen = 4;
1185                 af = AF_INET;
1186                 break;
1187         case SSH_SOCKS5_DOMAIN:
1188                 addrlen = p[sizeof(s5_req)];
1189                 af = -1;
1190                 break;
1191         case SSH_SOCKS5_IPV6:
1192                 addrlen = 16;
1193                 af = AF_INET6;
1194                 break;
1195         default:
1196                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1197                 return -1;
1198         }
1199         need = sizeof(s5_req) + addrlen + 2;
1200         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1201                 need++;
1202         if (have < need)
1203                 return 0;
1204         buffer_consume(&c->input, sizeof(s5_req));
1205         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1206                 buffer_consume(&c->input, 1);    /* host string length */
1207         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1208         buffer_get(&c->input, (char *)&dest_port, 2);
1209         dest_addr[addrlen] = '\0';
1210         if (c->path != NULL) {
1211                 xfree(c->path);
1212                 c->path = NULL;
1213         }
1214         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1215                 if (addrlen >= NI_MAXHOST) {
1216                         error("channel %d: dynamic request: socks5 hostname "
1217                             "\"%.100s\" too long", c->self, dest_addr);
1218                         return -1;
1219                 }
1220                 c->path = xstrdup(dest_addr);
1221         } else {
1222                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1223                         return -1;
1224                 c->path = xstrdup(ntop);
1225         }
1226         c->host_port = ntohs(dest_port);
1227
1228         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1229             c->self, c->path, c->host_port, s5_req.command);
1230
1231         s5_rsp.version = 0x05;
1232         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1233         s5_rsp.reserved = 0;                    /* ignored */
1234         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1235         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1236         dest_port = 0;                          /* ignored */
1237
1238         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1239         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1240         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1241         return 1;
1242 }
1243
1244 Channel *
1245 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1246     int in, int out)
1247 {
1248         Channel *c;
1249
1250         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1251             port_to_connect);
1252
1253         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1254             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1255             0, "stdio-forward", /*nonblock*/0);
1256
1257         c->path = xstrdup(host_to_connect);
1258         c->host_port = port_to_connect;
1259         c->listening_port = 0;
1260         c->force_drain = 1;
1261
1262         channel_register_fds(c, in, out, -1, 0, 1, 0);
1263         port_open_helper(c, "direct-tcpip");
1264
1265         return c;
1266 }
1267
1268 /* dynamic port forwarding */
1269 static void
1270 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1271 {
1272         u_char *p;
1273         u_int have;
1274         int ret;
1275
1276         have = buffer_len(&c->input);
1277         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1278         /* buffer_dump(&c->input); */
1279         /* check if the fixed size part of the packet is in buffer. */
1280         if (have < 3) {
1281                 /* need more */
1282                 FD_SET(c->sock, readset);
1283                 return;
1284         }
1285         /* try to guess the protocol */
1286         p = buffer_ptr(&c->input);
1287         switch (p[0]) {
1288         case 0x04:
1289                 ret = channel_decode_socks4(c, readset, writeset);
1290                 break;
1291         case 0x05:
1292                 ret = channel_decode_socks5(c, readset, writeset);
1293                 break;
1294         default:
1295                 ret = -1;
1296                 break;
1297         }
1298         if (ret < 0) {
1299                 chan_mark_dead(c);
1300         } else if (ret == 0) {
1301                 debug2("channel %d: pre_dynamic: need more", c->self);
1302                 /* need more */
1303                 FD_SET(c->sock, readset);
1304         } else {
1305                 /* switch to the next state */
1306                 c->type = SSH_CHANNEL_OPENING;
1307                 port_open_helper(c, "direct-tcpip");
1308         }
1309 }
1310
1311 /* This is our fake X11 server socket. */
1312 /* ARGSUSED */
1313 static void
1314 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1315 {
1316         Channel *nc;
1317         struct sockaddr_storage addr;
1318         int newsock;
1319         socklen_t addrlen;
1320         char buf[16384], *remote_ipaddr;
1321         int remote_port;
1322
1323         if (FD_ISSET(c->sock, readset)) {
1324                 debug("X11 connection requested.");
1325                 addrlen = sizeof(addr);
1326                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1327                 if (c->single_connection) {
1328                         debug2("single_connection: closing X11 listener.");
1329                         channel_close_fd(&c->sock);
1330                         chan_mark_dead(c);
1331                 }
1332                 if (newsock < 0) {
1333                         error("accept: %.100s", strerror(errno));
1334                         return;
1335                 }
1336                 set_nodelay(newsock);
1337                 remote_ipaddr = get_peer_ipaddr(newsock);
1338                 remote_port = get_peer_port(newsock);
1339                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1340                     remote_ipaddr, remote_port);
1341
1342                 nc = channel_new("accepted x11 socket",
1343                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1344                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1345                 if (compat20) {
1346                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1347                         packet_put_cstring("x11");
1348                         packet_put_int(nc->self);
1349                         packet_put_int(nc->local_window_max);
1350                         packet_put_int(nc->local_maxpacket);
1351                         /* originator ipaddr and port */
1352                         packet_put_cstring(remote_ipaddr);
1353                         if (datafellows & SSH_BUG_X11FWD) {
1354                                 debug2("ssh2 x11 bug compat mode");
1355                         } else {
1356                                 packet_put_int(remote_port);
1357                         }
1358                         packet_send();
1359                 } else {
1360                         packet_start(SSH_SMSG_X11_OPEN);
1361                         packet_put_int(nc->self);
1362                         if (packet_get_protocol_flags() &
1363                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1364                                 packet_put_cstring(buf);
1365                         packet_send();
1366                 }
1367                 xfree(remote_ipaddr);
1368         }
1369 }
1370
1371 static void
1372 port_open_helper(Channel *c, char *rtype)
1373 {
1374         int direct;
1375         char buf[1024];
1376         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1377         int remote_port = get_peer_port(c->sock);
1378
1379         if (remote_port == -1) {
1380                 /* Fake addr/port to appease peers that validate it (Tectia) */
1381                 xfree(remote_ipaddr);
1382                 remote_ipaddr = xstrdup("127.0.0.1");
1383                 remote_port = 65535;
1384         }
1385
1386         direct = (strcmp(rtype, "direct-tcpip") == 0);
1387
1388         snprintf(buf, sizeof buf,
1389             "%s: listening port %d for %.100s port %d, "
1390             "connect from %.200s port %d",
1391             rtype, c->listening_port, c->path, c->host_port,
1392             remote_ipaddr, remote_port);
1393
1394         xfree(c->remote_name);
1395         c->remote_name = xstrdup(buf);
1396
1397         if (compat20) {
1398                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1399                 packet_put_cstring(rtype);
1400                 packet_put_int(c->self);
1401                 packet_put_int(c->local_window_max);
1402                 packet_put_int(c->local_maxpacket);
1403                 if (direct) {
1404                         /* target host, port */
1405                         packet_put_cstring(c->path);
1406                         packet_put_int(c->host_port);
1407                 } else {
1408                         /* listen address, port */
1409                         packet_put_cstring(c->path);
1410                         packet_put_int(c->listening_port);
1411                 }
1412                 /* originator host and port */
1413                 packet_put_cstring(remote_ipaddr);
1414                 packet_put_int((u_int)remote_port);
1415                 packet_send();
1416         } else {
1417                 packet_start(SSH_MSG_PORT_OPEN);
1418                 packet_put_int(c->self);
1419                 packet_put_cstring(c->path);
1420                 packet_put_int(c->host_port);
1421                 if (packet_get_protocol_flags() &
1422                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1423                         packet_put_cstring(c->remote_name);
1424                 packet_send();
1425         }
1426         xfree(remote_ipaddr);
1427 }
1428
1429 static void
1430 channel_set_reuseaddr(int fd)
1431 {
1432         int on = 1;
1433
1434         /*
1435          * Set socket options.
1436          * Allow local port reuse in TIME_WAIT.
1437          */
1438         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1439                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1440 }
1441
1442 /*
1443  * This socket is listening for connections to a forwarded TCP/IP port.
1444  */
1445 /* ARGSUSED */
1446 static void
1447 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1448 {
1449         Channel *nc;
1450         struct sockaddr_storage addr;
1451         int newsock, nextstate;
1452         socklen_t addrlen;
1453         char *rtype;
1454
1455         if (FD_ISSET(c->sock, readset)) {
1456                 debug("Connection to port %d forwarding "
1457                     "to %.100s port %d requested.",
1458                     c->listening_port, c->path, c->host_port);
1459
1460                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1461                         nextstate = SSH_CHANNEL_OPENING;
1462                         rtype = "forwarded-tcpip";
1463                 } else {
1464                         if (c->host_port == 0) {
1465                                 nextstate = SSH_CHANNEL_DYNAMIC;
1466                                 rtype = "dynamic-tcpip";
1467                         } else {
1468                                 nextstate = SSH_CHANNEL_OPENING;
1469                                 rtype = "direct-tcpip";
1470                         }
1471                 }
1472
1473                 addrlen = sizeof(addr);
1474                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1475                 if (newsock < 0) {
1476                         error("accept: %.100s", strerror(errno));
1477                         return;
1478                 }
1479                 set_nodelay(newsock);
1480                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1481                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1482                 nc->listening_port = c->listening_port;
1483                 nc->host_port = c->host_port;
1484                 if (c->path != NULL)
1485                         nc->path = xstrdup(c->path);
1486
1487                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1488                         port_open_helper(nc, rtype);
1489         }
1490 }
1491
1492 /*
1493  * This is the authentication agent socket listening for connections from
1494  * clients.
1495  */
1496 /* ARGSUSED */
1497 static void
1498 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1499 {
1500         Channel *nc;
1501         int newsock;
1502         struct sockaddr_storage addr;
1503         socklen_t addrlen;
1504
1505         if (FD_ISSET(c->sock, readset)) {
1506                 addrlen = sizeof(addr);
1507                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1508                 if (newsock < 0) {
1509                         error("accept from auth socket: %.100s", strerror(errno));
1510                         return;
1511                 }
1512                 nc = channel_new("accepted auth socket",
1513                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1514                     c->local_window_max, c->local_maxpacket,
1515                     0, "accepted auth socket", 1);
1516                 if (compat20) {
1517                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1518                         packet_put_cstring("auth-agent@openssh.com");
1519                         packet_put_int(nc->self);
1520                         packet_put_int(c->local_window_max);
1521                         packet_put_int(c->local_maxpacket);
1522                 } else {
1523                         packet_start(SSH_SMSG_AGENT_OPEN);
1524                         packet_put_int(nc->self);
1525                 }
1526                 packet_send();
1527         }
1528 }
1529
1530 /* ARGSUSED */
1531 static void
1532 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1533 {
1534         int err = 0, sock;
1535         socklen_t sz = sizeof(err);
1536
1537         if (FD_ISSET(c->sock, writeset)) {
1538                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1539                         err = errno;
1540                         error("getsockopt SO_ERROR failed");
1541                 }
1542                 if (err == 0) {
1543                         debug("channel %d: connected to %s port %d",
1544                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1545                         channel_connect_ctx_free(&c->connect_ctx);
1546                         c->type = SSH_CHANNEL_OPEN;
1547                         if (compat20) {
1548                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1549                                 packet_put_int(c->remote_id);
1550                                 packet_put_int(c->self);
1551                                 packet_put_int(c->local_window);
1552                                 packet_put_int(c->local_maxpacket);
1553                         } else {
1554                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1555                                 packet_put_int(c->remote_id);
1556                                 packet_put_int(c->self);
1557                         }
1558                 } else {
1559                         debug("channel %d: connection failed: %s",
1560                             c->self, strerror(err));
1561                         /* Try next address, if any */
1562                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1563                                 close(c->sock);
1564                                 c->sock = c->rfd = c->wfd = sock;
1565                                 channel_max_fd = channel_find_maxfd();
1566                                 return;
1567                         }
1568                         /* Exhausted all addresses */
1569                         error("connect_to %.100s port %d: failed.",
1570                             c->connect_ctx.host, c->connect_ctx.port);
1571                         channel_connect_ctx_free(&c->connect_ctx);
1572                         if (compat20) {
1573                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1574                                 packet_put_int(c->remote_id);
1575                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1576                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1577                                         packet_put_cstring(strerror(err));
1578                                         packet_put_cstring("");
1579                                 }
1580                         } else {
1581                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1582                                 packet_put_int(c->remote_id);
1583                         }
1584                         chan_mark_dead(c);
1585                 }
1586                 packet_send();
1587         }
1588 }
1589
1590 /* ARGSUSED */
1591 static int
1592 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1593 {
1594         char buf[CHAN_RBUF];
1595         int len, force;
1596
1597         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1598         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1599                 errno = 0;
1600                 len = read(c->rfd, buf, sizeof(buf));
1601                 if (len < 0 && (errno == EINTR ||
1602                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1603                         return 1;
1604 #ifndef PTY_ZEROREAD
1605                 if (len <= 0) {
1606 #else
1607                 if ((!c->isatty && len <= 0) ||
1608                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1609 #endif
1610                         debug2("channel %d: read<=0 rfd %d len %d",
1611                             c->self, c->rfd, len);
1612                         if (c->type != SSH_CHANNEL_OPEN) {
1613                                 debug2("channel %d: not open", c->self);
1614                                 chan_mark_dead(c);
1615                                 return -1;
1616                         } else if (compat13) {
1617                                 buffer_clear(&c->output);
1618                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1619                                 debug2("channel %d: input draining.", c->self);
1620                         } else {
1621                                 chan_read_failed(c);
1622                         }
1623                         return -1;
1624                 }
1625                 if (c->input_filter != NULL) {
1626                         if (c->input_filter(c, buf, len) == -1) {
1627                                 debug2("channel %d: filter stops", c->self);
1628                                 chan_read_failed(c);
1629                         }
1630                 } else if (c->datagram) {
1631                         buffer_put_string(&c->input, buf, len);
1632                 } else {
1633                         buffer_append(&c->input, buf, len);
1634                 }
1635         }
1636         return 1;
1637 }
1638
1639 /* ARGSUSED */
1640 static int
1641 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1642 {
1643         struct termios tio;
1644         u_char *data = NULL, *buf;
1645         u_int dlen;
1646         int len;
1647
1648         /* Send buffered output data to the socket. */
1649         if (c->wfd != -1 &&
1650             FD_ISSET(c->wfd, writeset) &&
1651             buffer_len(&c->output) > 0) {
1652                 if (c->output_filter != NULL) {
1653                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1654                                 debug2("channel %d: filter stops", c->self);
1655                                 if (c->type != SSH_CHANNEL_OPEN)
1656                                         chan_mark_dead(c);
1657                                 else
1658                                         chan_write_failed(c);
1659                                 return -1;
1660                         }
1661                 } else if (c->datagram) {
1662                         buf = data = buffer_get_string(&c->output, &dlen);
1663                 } else {
1664                         buf = data = buffer_ptr(&c->output);
1665                         dlen = buffer_len(&c->output);
1666                 }
1667
1668                 if (c->datagram) {
1669                         /* ignore truncated writes, datagrams might get lost */
1670                         c->local_consumed += dlen + 4;
1671                         len = write(c->wfd, buf, dlen);
1672                         xfree(data);
1673                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1674                             errno == EWOULDBLOCK))
1675                                 return 1;
1676                         if (len <= 0) {
1677                                 if (c->type != SSH_CHANNEL_OPEN)
1678                                         chan_mark_dead(c);
1679                                 else
1680                                         chan_write_failed(c);
1681                                 return -1;
1682                         }
1683                         return 1;
1684                 }
1685 #ifdef _AIX
1686                 /* XXX: Later AIX versions can't push as much data to tty */
1687                 if (compat20 && c->wfd_isatty)
1688                         dlen = MIN(dlen, 8*1024);
1689 #endif
1690
1691                 len = write(c->wfd, buf, dlen);
1692                 if (len < 0 &&
1693                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1694                         return 1;
1695                 if (len <= 0) {
1696                         if (c->type != SSH_CHANNEL_OPEN) {
1697                                 debug2("channel %d: not open", c->self);
1698                                 chan_mark_dead(c);
1699                                 return -1;
1700                         } else if (compat13) {
1701                                 buffer_clear(&c->output);
1702                                 debug2("channel %d: input draining.", c->self);
1703                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1704                         } else {
1705                                 chan_write_failed(c);
1706                         }
1707                         return -1;
1708                 }
1709 #ifndef BROKEN_TCGETATTR_ICANON
1710                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1711                         if (tcgetattr(c->wfd, &tio) == 0 &&
1712                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1713                                 /*
1714                                  * Simulate echo to reduce the impact of
1715                                  * traffic analysis. We need to match the
1716                                  * size of a SSH2_MSG_CHANNEL_DATA message
1717                                  * (4 byte channel id + buf)
1718                                  */
1719                                 packet_send_ignore(4 + len);
1720                                 packet_send();
1721                         }
1722                 }
1723 #endif
1724                 buffer_consume(&c->output, len);
1725                 if (compat20 && len > 0) {
1726                         c->local_consumed += len;
1727                 }
1728         }
1729         return 1;
1730 }
1731
1732 static int
1733 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1734 {
1735         char buf[CHAN_RBUF];
1736         int len;
1737
1738 /** XXX handle drain efd, too */
1739         if (c->efd != -1) {
1740                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1741                     FD_ISSET(c->efd, writeset) &&
1742                     buffer_len(&c->extended) > 0) {
1743                         len = write(c->efd, buffer_ptr(&c->extended),
1744                             buffer_len(&c->extended));
1745                         debug2("channel %d: written %d to efd %d",
1746                             c->self, len, c->efd);
1747                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1748                             errno == EWOULDBLOCK))
1749                                 return 1;
1750                         if (len <= 0) {
1751                                 debug2("channel %d: closing write-efd %d",
1752                                     c->self, c->efd);
1753                                 channel_close_fd(&c->efd);
1754                         } else {
1755                                 buffer_consume(&c->extended, len);
1756                                 c->local_consumed += len;
1757                         }
1758                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1759                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1760                         len = read(c->efd, buf, sizeof(buf));
1761                         debug2("channel %d: read %d from efd %d",
1762                             c->self, len, c->efd);
1763                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1764                             errno == EWOULDBLOCK) && !c->detach_close)))
1765                                 return 1;
1766                         if (len <= 0) {
1767                                 debug2("channel %d: closing read-efd %d",
1768                                     c->self, c->efd);
1769                                 channel_close_fd(&c->efd);
1770                         } else {
1771                                 buffer_append(&c->extended, buf, len);
1772                         }
1773                 }
1774         }
1775         return 1;
1776 }
1777
1778 static int
1779 channel_check_window(Channel *c)
1780 {
1781         if (c->type == SSH_CHANNEL_OPEN &&
1782             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1783             ((c->local_window_max - c->local_window >
1784             c->local_maxpacket*3) ||
1785             c->local_window < c->local_window_max/2) &&
1786             c->local_consumed > 0) {
1787                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1788                 packet_put_int(c->remote_id);
1789                 packet_put_int(c->local_consumed);
1790                 packet_send();
1791                 debug2("channel %d: window %d sent adjust %d",
1792                     c->self, c->local_window,
1793                     c->local_consumed);
1794                 c->local_window += c->local_consumed;
1795                 c->local_consumed = 0;
1796         }
1797         return 1;
1798 }
1799
1800 static void
1801 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1802 {
1803         channel_handle_rfd(c, readset, writeset);
1804         channel_handle_wfd(c, readset, writeset);
1805         if (!compat20)
1806                 return;
1807         channel_handle_efd(c, readset, writeset);
1808         channel_check_window(c);
1809 }
1810
1811 static u_int
1812 read_mux(Channel *c, u_int need)
1813 {
1814         char buf[CHAN_RBUF];
1815         int len;
1816         u_int rlen;
1817
1818         if (buffer_len(&c->input) < need) {
1819                 rlen = need - buffer_len(&c->input);
1820                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1821                 if (len <= 0) {
1822                         if (errno != EINTR && errno != EAGAIN) {
1823                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1824                                     c->self, c->rfd, len);
1825                                 chan_read_failed(c);
1826                                 return 0;
1827                         }
1828                 } else
1829                         buffer_append(&c->input, buf, len);
1830         }
1831         return buffer_len(&c->input);
1832 }
1833
1834 static void
1835 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1836 {
1837         u_int need;
1838         ssize_t len;
1839
1840         if (!compat20)
1841                 fatal("%s: entered with !compat20", __func__);
1842
1843         if (c->rfd != -1 && FD_ISSET(c->rfd, readset) &&
1844             (c->istate == CHAN_INPUT_OPEN ||
1845             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1846                 /*
1847                  * Don't not read past the precise end of packets to
1848                  * avoid disrupting fd passing.
1849                  */
1850                 if (read_mux(c, 4) < 4) /* read header */
1851                         return;
1852                 need = get_u32(buffer_ptr(&c->input));
1853 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1854                 if (need > CHANNEL_MUX_MAX_PACKET) {
1855                         debug2("channel %d: packet too big %u > %u",
1856                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1857                         chan_rcvd_oclose(c);
1858                         return;
1859                 }
1860                 if (read_mux(c, need + 4) < need + 4) /* read body */
1861                         return;
1862                 if (c->mux_rcb(c) != 0) {
1863                         debug("channel %d: mux_rcb failed", c->self);
1864                         chan_mark_dead(c);
1865                         return;
1866                 }
1867         }
1868
1869         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1870             buffer_len(&c->output) > 0) {
1871                 len = write(c->wfd, buffer_ptr(&c->output),
1872                     buffer_len(&c->output));
1873                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1874                         return;
1875                 if (len <= 0) {
1876                         chan_mark_dead(c);
1877                         return;
1878                 }
1879                 buffer_consume(&c->output, len);
1880         }
1881 }
1882
1883 static void
1884 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1885 {
1886         Channel *nc;
1887         struct sockaddr_storage addr;
1888         socklen_t addrlen;
1889         int newsock;
1890         uid_t euid;
1891         gid_t egid;
1892
1893         if (!FD_ISSET(c->sock, readset))
1894                 return;
1895
1896         debug("multiplexing control connection");
1897
1898         /*
1899          * Accept connection on control socket
1900          */
1901         memset(&addr, 0, sizeof(addr));
1902         addrlen = sizeof(addr);
1903         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1904             &addrlen)) == -1) {
1905                 error("%s accept: %s", __func__, strerror(errno));
1906                 return;
1907         }
1908
1909         if (getpeereid(newsock, &euid, &egid) < 0) {
1910                 error("%s getpeereid failed: %s", __func__,
1911                     strerror(errno));
1912                 close(newsock);
1913                 return;
1914         }
1915         if ((euid != 0) && (getuid() != euid)) {
1916                 error("multiplex uid mismatch: peer euid %u != uid %u",
1917                     (u_int)euid, (u_int)getuid());
1918                 close(newsock);
1919                 return;
1920         }
1921         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
1922             newsock, newsock, -1, c->local_window_max,
1923             c->local_maxpacket, 0, "mux-control", 1);
1924         nc->mux_rcb = c->mux_rcb;
1925         debug3("%s: new mux channel %d fd %d", __func__,
1926             nc->self, nc->sock);
1927         /* establish state */
1928         nc->mux_rcb(nc);
1929         /* mux state transitions must not elicit protocol messages */
1930         nc->flags |= CHAN_LOCAL;
1931 }
1932
1933 /* ARGSUSED */
1934 static void
1935 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1936 {
1937         int len;
1938
1939         /* Send buffered output data to the socket. */
1940         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1941                 len = write(c->sock, buffer_ptr(&c->output),
1942                             buffer_len(&c->output));
1943                 if (len <= 0)
1944                         buffer_clear(&c->output);
1945                 else
1946                         buffer_consume(&c->output, len);
1947         }
1948 }
1949
1950 static void
1951 channel_handler_init_20(void)
1952 {
1953         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1954         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1955         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1956         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1957         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1958         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1959         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1960         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1961         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
1962         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
1963
1964         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1965         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1966         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1967         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1968         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1969         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1970         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1971         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
1972         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
1973 }
1974
1975 static void
1976 channel_handler_init_13(void)
1977 {
1978         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1979         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1980         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1981         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1982         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1983         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1984         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1985         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1986         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1987
1988         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1989         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1990         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1991         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1992         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1993         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1994         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1995 }
1996
1997 static void
1998 channel_handler_init_15(void)
1999 {
2000         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2001         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2002         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2003         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2004         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2005         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2006         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2007
2008         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2009         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2010         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2011         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2012         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2013         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2014 }
2015
2016 static void
2017 channel_handler_init(void)
2018 {
2019         int i;
2020
2021         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2022                 channel_pre[i] = NULL;
2023                 channel_post[i] = NULL;
2024         }
2025         if (compat20)
2026                 channel_handler_init_20();
2027         else if (compat13)
2028                 channel_handler_init_13();
2029         else
2030                 channel_handler_init_15();
2031 }
2032
2033 /* gc dead channels */
2034 static void
2035 channel_garbage_collect(Channel *c)
2036 {
2037         if (c == NULL)
2038                 return;
2039         if (c->detach_user != NULL) {
2040                 if (!chan_is_dead(c, c->detach_close))
2041                         return;
2042                 debug2("channel %d: gc: notify user", c->self);
2043                 c->detach_user(c->self, NULL);
2044                 /* if we still have a callback */
2045                 if (c->detach_user != NULL)
2046                         return;
2047                 debug2("channel %d: gc: user detached", c->self);
2048         }
2049         if (!chan_is_dead(c, 1))
2050                 return;
2051         debug2("channel %d: garbage collecting", c->self);
2052         channel_free(c);
2053 }
2054
2055 static void
2056 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
2057 {
2058         static int did_init = 0;
2059         u_int i, oalloc;
2060         Channel *c;
2061
2062         if (!did_init) {
2063                 channel_handler_init();
2064                 did_init = 1;
2065         }
2066         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2067                 c = channels[i];
2068                 if (c == NULL)
2069                         continue;
2070                 if (c->delayed) {
2071                         if (ftab == channel_pre)
2072                                 c->delayed = 0;
2073                         else
2074                                 continue;
2075                 }
2076                 if (ftab[c->type] != NULL)
2077                         (*ftab[c->type])(c, readset, writeset);
2078                 channel_garbage_collect(c);
2079         }
2080 }
2081
2082 /*
2083  * Allocate/update select bitmasks and add any bits relevant to channels in
2084  * select bitmasks.
2085  */
2086 void
2087 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2088     u_int *nallocp, int rekeying)
2089 {
2090         u_int n, sz, nfdset;
2091
2092         n = MAX(*maxfdp, channel_max_fd);
2093
2094         nfdset = howmany(n+1, NFDBITS);
2095         /* Explicitly test here, because xrealloc isn't always called */
2096         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
2097                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2098         sz = nfdset * sizeof(fd_mask);
2099
2100         /* perhaps check sz < nalloc/2 and shrink? */
2101         if (*readsetp == NULL || sz > *nallocp) {
2102                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2103                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2104                 *nallocp = sz;
2105         }
2106         *maxfdp = n;
2107         memset(*readsetp, 0, sz);
2108         memset(*writesetp, 0, sz);
2109
2110         if (!rekeying)
2111                 channel_handler(channel_pre, *readsetp, *writesetp);
2112 }
2113
2114 /*
2115  * After select, perform any appropriate operations for channels which have
2116  * events pending.
2117  */
2118 void
2119 channel_after_select(fd_set *readset, fd_set *writeset)
2120 {
2121         channel_handler(channel_post, readset, writeset);
2122 }
2123
2124
2125 /* If there is data to send to the connection, enqueue some of it now. */
2126 void
2127 channel_output_poll(void)
2128 {
2129         Channel *c;
2130         u_int i, len;
2131
2132         for (i = 0; i < channels_alloc; i++) {
2133                 c = channels[i];
2134                 if (c == NULL)
2135                         continue;
2136
2137                 /*
2138                  * We are only interested in channels that can have buffered
2139                  * incoming data.
2140                  */
2141                 if (compat13) {
2142                         if (c->type != SSH_CHANNEL_OPEN &&
2143                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2144                                 continue;
2145                 } else {
2146                         if (c->type != SSH_CHANNEL_OPEN)
2147                                 continue;
2148                 }
2149                 if (compat20 &&
2150                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2151                         /* XXX is this true? */
2152                         debug3("channel %d: will not send data after close", c->self);
2153                         continue;
2154                 }
2155
2156                 /* Get the amount of buffered data for this channel. */
2157                 if ((c->istate == CHAN_INPUT_OPEN ||
2158                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2159                     (len = buffer_len(&c->input)) > 0) {
2160                         if (c->datagram) {
2161                                 if (len > 0) {
2162                                         u_char *data;
2163                                         u_int dlen;
2164
2165                                         data = buffer_get_string(&c->input,
2166                                             &dlen);
2167                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2168                                         packet_put_int(c->remote_id);
2169                                         packet_put_string(data, dlen);
2170                                         packet_send();
2171                                         c->remote_window -= dlen + 4;
2172                                         xfree(data);
2173                                 }
2174                                 continue;
2175                         }
2176                         /*
2177                          * Send some data for the other side over the secure
2178                          * connection.
2179                          */
2180                         if (compat20) {
2181                                 if (len > c->remote_window)
2182                                         len = c->remote_window;
2183                                 if (len > c->remote_maxpacket)
2184                                         len = c->remote_maxpacket;
2185                         } else {
2186                                 if (packet_is_interactive()) {
2187                                         if (len > 1024)
2188                                                 len = 512;
2189                                 } else {
2190                                         /* Keep the packets at reasonable size. */
2191                                         if (len > packet_get_maxsize()/2)
2192                                                 len = packet_get_maxsize()/2;
2193                                 }
2194                         }
2195                         if (len > 0) {
2196                                 packet_start(compat20 ?
2197                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2198                                 packet_put_int(c->remote_id);
2199                                 packet_put_string(buffer_ptr(&c->input), len);
2200                                 packet_send();
2201                                 buffer_consume(&c->input, len);
2202                                 c->remote_window -= len;
2203                         }
2204                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2205                         if (compat13)
2206                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2207                         /*
2208                          * input-buffer is empty and read-socket shutdown:
2209                          * tell peer, that we will not send more data: send IEOF.
2210                          * hack for extended data: delay EOF if EFD still in use.
2211                          */
2212                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2213                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2214                                     c->self, c->efd, buffer_len(&c->extended));
2215                         else
2216                                 chan_ibuf_empty(c);
2217                 }
2218                 /* Send extended data, i.e. stderr */
2219                 if (compat20 &&
2220                     !(c->flags & CHAN_EOF_SENT) &&
2221                     c->remote_window > 0 &&
2222                     (len = buffer_len(&c->extended)) > 0 &&
2223                     c->extended_usage == CHAN_EXTENDED_READ) {
2224                         debug2("channel %d: rwin %u elen %u euse %d",
2225                             c->self, c->remote_window, buffer_len(&c->extended),
2226                             c->extended_usage);
2227                         if (len > c->remote_window)
2228                                 len = c->remote_window;
2229                         if (len > c->remote_maxpacket)
2230                                 len = c->remote_maxpacket;
2231                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2232                         packet_put_int(c->remote_id);
2233                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2234                         packet_put_string(buffer_ptr(&c->extended), len);
2235                         packet_send();
2236                         buffer_consume(&c->extended, len);
2237                         c->remote_window -= len;
2238                         debug2("channel %d: sent ext data %d", c->self, len);
2239                 }
2240         }
2241 }
2242
2243
2244 /* -- protocol input */
2245
2246 /* ARGSUSED */
2247 void
2248 channel_input_data(int type, u_int32_t seq, void *ctxt)
2249 {
2250         int id;
2251         char *data;
2252         u_int data_len;
2253         Channel *c;
2254
2255         /* Get the channel number and verify it. */
2256         id = packet_get_int();
2257         c = channel_lookup(id);
2258         if (c == NULL)
2259                 packet_disconnect("Received data for nonexistent channel %d.", id);
2260
2261         /* Ignore any data for non-open channels (might happen on close) */
2262         if (c->type != SSH_CHANNEL_OPEN &&
2263             c->type != SSH_CHANNEL_X11_OPEN)
2264                 return;
2265
2266         /* Get the data. */
2267         data = packet_get_string_ptr(&data_len);
2268
2269         /*
2270          * Ignore data for protocol > 1.3 if output end is no longer open.
2271          * For protocol 2 the sending side is reducing its window as it sends
2272          * data, so we must 'fake' consumption of the data in order to ensure
2273          * that window updates are sent back.  Otherwise the connection might
2274          * deadlock.
2275          */
2276         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2277                 if (compat20) {
2278                         c->local_window -= data_len;
2279                         c->local_consumed += data_len;
2280                 }
2281                 return;
2282         }
2283
2284         if (compat20) {
2285                 if (data_len > c->local_maxpacket) {
2286                         logit("channel %d: rcvd big packet %d, maxpack %d",
2287                             c->self, data_len, c->local_maxpacket);
2288                 }
2289                 if (data_len > c->local_window) {
2290                         logit("channel %d: rcvd too much data %d, win %d",
2291                             c->self, data_len, c->local_window);
2292                         return;
2293                 }
2294                 c->local_window -= data_len;
2295         }
2296         if (c->datagram)
2297                 buffer_put_string(&c->output, data, data_len);
2298         else
2299                 buffer_append(&c->output, data, data_len);
2300         packet_check_eom();
2301 }
2302
2303 /* ARGSUSED */
2304 void
2305 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2306 {
2307         int id;
2308         char *data;
2309         u_int data_len, tcode;
2310         Channel *c;
2311
2312         /* Get the channel number and verify it. */
2313         id = packet_get_int();
2314         c = channel_lookup(id);
2315
2316         if (c == NULL)
2317                 packet_disconnect("Received extended_data for bad channel %d.", id);
2318         if (c->type != SSH_CHANNEL_OPEN) {
2319                 logit("channel %d: ext data for non open", id);
2320                 return;
2321         }
2322         if (c->flags & CHAN_EOF_RCVD) {
2323                 if (datafellows & SSH_BUG_EXTEOF)
2324                         debug("channel %d: accepting ext data after eof", id);
2325                 else
2326                         packet_disconnect("Received extended_data after EOF "
2327                             "on channel %d.", id);
2328         }
2329         tcode = packet_get_int();
2330         if (c->efd == -1 ||
2331             c->extended_usage != CHAN_EXTENDED_WRITE ||
2332             tcode != SSH2_EXTENDED_DATA_STDERR) {
2333                 logit("channel %d: bad ext data", c->self);
2334                 return;
2335         }
2336         data = packet_get_string(&data_len);
2337         packet_check_eom();
2338         if (data_len > c->local_window) {
2339                 logit("channel %d: rcvd too much extended_data %d, win %d",
2340                     c->self, data_len, c->local_window);
2341                 xfree(data);
2342                 return;
2343         }
2344         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2345         c->local_window -= data_len;
2346         buffer_append(&c->extended, data, data_len);
2347         xfree(data);
2348 }
2349
2350 /* ARGSUSED */
2351 void
2352 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2353 {
2354         int id;
2355         Channel *c;
2356
2357         id = packet_get_int();
2358         packet_check_eom();
2359         c = channel_lookup(id);
2360         if (c == NULL)
2361                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2362         chan_rcvd_ieof(c);
2363
2364         /* XXX force input close */
2365         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2366                 debug("channel %d: FORCE input drain", c->self);
2367                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2368                 if (buffer_len(&c->input) == 0)
2369                         chan_ibuf_empty(c);
2370         }
2371
2372 }
2373
2374 /* ARGSUSED */
2375 void
2376 channel_input_close(int type, u_int32_t seq, void *ctxt)
2377 {
2378         int id;
2379         Channel *c;
2380
2381         id = packet_get_int();
2382         packet_check_eom();
2383         c = channel_lookup(id);
2384         if (c == NULL)
2385                 packet_disconnect("Received close for nonexistent channel %d.", id);
2386
2387         /*
2388          * Send a confirmation that we have closed the channel and no more
2389          * data is coming for it.
2390          */
2391         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2392         packet_put_int(c->remote_id);
2393         packet_send();
2394
2395         /*
2396          * If the channel is in closed state, we have sent a close request,
2397          * and the other side will eventually respond with a confirmation.
2398          * Thus, we cannot free the channel here, because then there would be
2399          * no-one to receive the confirmation.  The channel gets freed when
2400          * the confirmation arrives.
2401          */
2402         if (c->type != SSH_CHANNEL_CLOSED) {
2403                 /*
2404                  * Not a closed channel - mark it as draining, which will
2405                  * cause it to be freed later.
2406                  */
2407                 buffer_clear(&c->input);
2408                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2409         }
2410 }
2411
2412 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2413 /* ARGSUSED */
2414 void
2415 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2416 {
2417         int id = packet_get_int();
2418         Channel *c = channel_lookup(id);
2419
2420         packet_check_eom();
2421         if (c == NULL)
2422                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2423         chan_rcvd_oclose(c);
2424 }
2425
2426 /* ARGSUSED */
2427 void
2428 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2429 {
2430         int id = packet_get_int();
2431         Channel *c = channel_lookup(id);
2432
2433         packet_check_eom();
2434         if (c == NULL)
2435                 packet_disconnect("Received close confirmation for "
2436                     "out-of-range channel %d.", id);
2437         if (c->type != SSH_CHANNEL_CLOSED)
2438                 packet_disconnect("Received close confirmation for "
2439                     "non-closed channel %d (type %d).", id, c->type);
2440         channel_free(c);
2441 }
2442
2443 /* ARGSUSED */
2444 void
2445 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2446 {
2447         int id, remote_id;
2448         Channel *c;
2449
2450         id = packet_get_int();
2451         c = channel_lookup(id);
2452
2453         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2454                 packet_disconnect("Received open confirmation for "
2455                     "non-opening channel %d.", id);
2456         remote_id = packet_get_int();
2457         /* Record the remote channel number and mark that the channel is now open. */
2458         c->remote_id = remote_id;
2459         c->type = SSH_CHANNEL_OPEN;
2460
2461         if (compat20) {
2462                 c->remote_window = packet_get_int();
2463                 c->remote_maxpacket = packet_get_int();
2464                 if (c->open_confirm) {
2465                         debug2("callback start");
2466                         c->open_confirm(c->self, c->open_confirm_ctx);
2467                         debug2("callback done");
2468                 }
2469                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2470                     c->remote_window, c->remote_maxpacket);
2471         }
2472         packet_check_eom();
2473 }
2474
2475 static char *
2476 reason2txt(int reason)
2477 {
2478         switch (reason) {
2479         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2480                 return "administratively prohibited";
2481         case SSH2_OPEN_CONNECT_FAILED:
2482                 return "connect failed";
2483         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2484                 return "unknown channel type";
2485         case SSH2_OPEN_RESOURCE_SHORTAGE:
2486                 return "resource shortage";
2487         }
2488         return "unknown reason";
2489 }
2490
2491 /* ARGSUSED */
2492 void
2493 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2494 {
2495         int id, reason;
2496         char *msg = NULL, *lang = NULL;
2497         Channel *c;
2498
2499         id = packet_get_int();
2500         c = channel_lookup(id);
2501
2502         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2503                 packet_disconnect("Received open failure for "
2504                     "non-opening channel %d.", id);
2505         if (compat20) {
2506                 reason = packet_get_int();
2507                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2508                         msg  = packet_get_string(NULL);
2509                         lang = packet_get_string(NULL);
2510                 }
2511                 logit("channel %d: open failed: %s%s%s", id,
2512                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2513                 if (msg != NULL)
2514                         xfree(msg);
2515                 if (lang != NULL)
2516                         xfree(lang);
2517         }
2518         packet_check_eom();
2519         /* Schedule the channel for cleanup/deletion. */
2520         chan_mark_dead(c);
2521 }
2522
2523 /* ARGSUSED */
2524 void
2525 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2526 {
2527         Channel *c;
2528         int id;
2529         u_int adjust;
2530
2531         if (!compat20)
2532                 return;
2533
2534         /* Get the channel number and verify it. */
2535         id = packet_get_int();
2536         c = channel_lookup(id);
2537
2538         if (c == NULL) {
2539                 logit("Received window adjust for non-open channel %d.", id);
2540                 return;
2541         }
2542         adjust = packet_get_int();
2543         packet_check_eom();
2544         debug2("channel %d: rcvd adjust %u", id, adjust);
2545         c->remote_window += adjust;
2546 }
2547
2548 /* ARGSUSED */
2549 void
2550 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2551 {
2552         Channel *c = NULL;
2553         u_short host_port;
2554         char *host, *originator_string;
2555         int remote_id;
2556
2557         remote_id = packet_get_int();
2558         host = packet_get_string(NULL);
2559         host_port = packet_get_int();
2560
2561         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2562                 originator_string = packet_get_string(NULL);
2563         } else {
2564                 originator_string = xstrdup("unknown (remote did not supply name)");
2565         }
2566         packet_check_eom();
2567         c = channel_connect_to(host, host_port,
2568             "connected socket", originator_string);
2569         xfree(originator_string);
2570         xfree(host);
2571         if (c == NULL) {
2572                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2573                 packet_put_int(remote_id);
2574                 packet_send();
2575         } else
2576                 c->remote_id = remote_id;
2577 }
2578
2579 /* ARGSUSED */
2580 void
2581 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2582 {
2583         Channel *c;
2584         struct channel_confirm *cc;
2585         int id;
2586
2587         /* Reset keepalive timeout */
2588         packet_set_alive_timeouts(0);
2589
2590         id = packet_get_int();
2591         packet_check_eom();
2592
2593         debug2("channel_input_status_confirm: type %d id %d", type, id);
2594
2595         if ((c = channel_lookup(id)) == NULL) {
2596                 logit("channel_input_status_confirm: %d: unknown", id);
2597                 return;
2598         }
2599         ;
2600         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2601                 return;
2602         cc->cb(type, c, cc->ctx);
2603         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2604         bzero(cc, sizeof(*cc));
2605         xfree(cc);
2606 }
2607
2608 /* -- tcp forwarding */
2609
2610 void
2611 channel_set_af(int af)
2612 {
2613         IPv4or6 = af;
2614 }
2615
2616 static int
2617 channel_setup_fwd_listener(int type, const char *listen_addr,
2618     u_short listen_port, int *allocated_listen_port,
2619     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2620 {
2621         Channel *c;
2622         int sock, r, success = 0, wildcard = 0, is_client;
2623         struct addrinfo hints, *ai, *aitop;
2624         const char *host, *addr;
2625         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2626         in_port_t *lport_p;
2627
2628         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2629             listen_addr : host_to_connect;
2630         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2631
2632         if (host == NULL) {
2633                 error("No forward host name.");
2634                 return 0;
2635         }
2636         if (strlen(host) >= NI_MAXHOST) {
2637                 error("Forward host name too long.");
2638                 return 0;
2639         }
2640
2641         /*
2642          * Determine whether or not a port forward listens to loopback,
2643          * specified address or wildcard. On the client, a specified bind
2644          * address will always override gateway_ports. On the server, a
2645          * gateway_ports of 1 (``yes'') will override the client's
2646          * specification and force a wildcard bind, whereas a value of 2
2647          * (``clientspecified'') will bind to whatever address the client
2648          * asked for.
2649          *
2650          * Special-case listen_addrs are:
2651          *
2652          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2653          * "" (empty string), "*"  -> wildcard v4/v6
2654          * "localhost"             -> loopback v4/v6
2655          */
2656         addr = NULL;
2657         if (listen_addr == NULL) {
2658                 /* No address specified: default to gateway_ports setting */
2659                 if (gateway_ports)
2660                         wildcard = 1;
2661         } else if (gateway_ports || is_client) {
2662                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2663                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2664                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2665                     (!is_client && gateway_ports == 1))
2666                         wildcard = 1;
2667                 else if (strcmp(listen_addr, "localhost") != 0)
2668                         addr = listen_addr;
2669         }
2670
2671         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2672             type, wildcard, (addr == NULL) ? "NULL" : addr);
2673
2674         /*
2675          * getaddrinfo returns a loopback address if the hostname is
2676          * set to NULL and hints.ai_flags is not AI_PASSIVE
2677          */
2678         memset(&hints, 0, sizeof(hints));
2679         hints.ai_family = IPv4or6;
2680         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2681         hints.ai_socktype = SOCK_STREAM;
2682         snprintf(strport, sizeof strport, "%d", listen_port);
2683         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2684                 if (addr == NULL) {
2685                         /* This really shouldn't happen */
2686                         packet_disconnect("getaddrinfo: fatal error: %s",
2687                             ssh_gai_strerror(r));
2688                 } else {
2689                         error("channel_setup_fwd_listener: "
2690                             "getaddrinfo(%.64s): %s", addr,
2691                             ssh_gai_strerror(r));
2692                 }
2693                 return 0;
2694         }
2695         if (allocated_listen_port != NULL)
2696                 *allocated_listen_port = 0;
2697         for (ai = aitop; ai; ai = ai->ai_next) {
2698                 switch (ai->ai_family) {
2699                 case AF_INET:
2700                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2701                             sin_port;
2702                         break;
2703                 case AF_INET6:
2704                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2705                             sin6_port;
2706                         break;
2707                 default:
2708                         continue;
2709                 }
2710                 /*
2711                  * If allocating a port for -R forwards, then use the
2712                  * same port for all address families.
2713                  */
2714                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2715                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2716                         *lport_p = htons(*allocated_listen_port);
2717
2718                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2719                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2720                         error("channel_setup_fwd_listener: getnameinfo failed");
2721                         continue;
2722                 }
2723                 /* Create a port to listen for the host. */
2724                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2725                 if (sock < 0) {
2726                         /* this is no error since kernel may not support ipv6 */
2727                         verbose("socket: %.100s", strerror(errno));
2728                         continue;
2729                 }
2730
2731                 channel_set_reuseaddr(sock);
2732                 if (ai->ai_family == AF_INET6)
2733                         sock_set_v6only(sock);
2734
2735                 debug("Local forwarding listening on %s port %s.",
2736                     ntop, strport);
2737
2738                 /* Bind the socket to the address. */
2739                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2740                         /* address can be in use ipv6 address is already bound */
2741                         if (!ai->ai_next)
2742                                 error("bind: %.100s", strerror(errno));
2743                         else
2744                                 verbose("bind: %.100s", strerror(errno));
2745
2746                         close(sock);
2747                         continue;
2748                 }
2749                 /* Start listening for connections on the socket. */
2750                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2751                         error("listen: %.100s", strerror(errno));
2752                         close(sock);
2753                         continue;
2754                 }
2755
2756                 /*
2757                  * listen_port == 0 requests a dynamically allocated port -
2758                  * record what we got.
2759                  */
2760                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2761                     allocated_listen_port != NULL &&
2762                     *allocated_listen_port == 0) {
2763                         *allocated_listen_port = get_sock_port(sock, 1);
2764                         debug("Allocated listen port %d",
2765                             *allocated_listen_port);
2766                 }
2767
2768                 /* Allocate a channel number for the socket. */
2769                 c = channel_new("port listener", type, sock, sock, -1,
2770                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2771                     0, "port listener", 1);
2772                 c->path = xstrdup(host);
2773                 c->host_port = port_to_connect;
2774                 c->listening_port = listen_port;
2775                 success = 1;
2776         }
2777         if (success == 0)
2778                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2779                     listen_port);
2780         freeaddrinfo(aitop);
2781         return success;
2782 }
2783
2784 int
2785 channel_cancel_rport_listener(const char *host, u_short port)
2786 {
2787         u_int i;
2788         int found = 0;
2789
2790         for (i = 0; i < channels_alloc; i++) {
2791                 Channel *c = channels[i];
2792
2793                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2794                     strcmp(c->path, host) == 0 && c->listening_port == port) {
2795                         debug2("%s: close channel %d", __func__, i);
2796                         channel_free(c);
2797                         found = 1;
2798                 }
2799         }
2800
2801         return (found);
2802 }
2803
2804 /* protocol local port fwd, used by ssh (and sshd in v1) */
2805 int
2806 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2807     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2808 {
2809         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2810             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2811             gateway_ports);
2812 }
2813
2814 /* protocol v2 remote port fwd, used by sshd */
2815 int
2816 channel_setup_remote_fwd_listener(const char *listen_address,
2817     u_short listen_port, int *allocated_listen_port, int gateway_ports)
2818 {
2819         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2820             listen_address, listen_port, allocated_listen_port,
2821             NULL, 0, gateway_ports);
2822 }
2823
2824 /*
2825  * Initiate forwarding of connections to port "port" on remote host through
2826  * the secure channel to host:port from local side.
2827  */
2828
2829 int
2830 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2831     const char *host_to_connect, u_short port_to_connect)
2832 {
2833         int type, success = 0;
2834
2835         /* Record locally that connection to this host/port is permitted. */
2836         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2837                 fatal("channel_request_remote_forwarding: too many forwards");
2838
2839         /* Send the forward request to the remote side. */
2840         if (compat20) {
2841                 const char *address_to_bind;
2842                 if (listen_host == NULL) {
2843                         if (datafellows & SSH_BUG_RFWD_ADDR)
2844                                 address_to_bind = "127.0.0.1";
2845                         else
2846                                 address_to_bind = "localhost";
2847                 } else if (*listen_host == '\0' ||
2848                            strcmp(listen_host, "*") == 0) {
2849                         if (datafellows & SSH_BUG_RFWD_ADDR)
2850                                 address_to_bind = "0.0.0.0";
2851                         else
2852                                 address_to_bind = "";
2853                 } else
2854                         address_to_bind = listen_host;
2855
2856                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2857                 packet_put_cstring("tcpip-forward");
2858                 packet_put_char(1);                     /* boolean: want reply */
2859                 packet_put_cstring(address_to_bind);
2860                 packet_put_int(listen_port);
2861                 packet_send();
2862                 packet_write_wait();
2863                 /* Assume that server accepts the request */
2864                 success = 1;
2865         } else {
2866                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2867                 packet_put_int(listen_port);
2868                 packet_put_cstring(host_to_connect);
2869                 packet_put_int(port_to_connect);
2870                 packet_send();
2871                 packet_write_wait();
2872
2873                 /* Wait for response from the remote side. */
2874                 type = packet_read();
2875                 switch (type) {
2876                 case SSH_SMSG_SUCCESS:
2877                         success = 1;
2878                         break;
2879                 case SSH_SMSG_FAILURE:
2880                         break;
2881                 default:
2882                         /* Unknown packet */
2883                         packet_disconnect("Protocol error for port forward request:"
2884                             "received packet type %d.", type);
2885                 }
2886         }
2887         if (success) {
2888                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2889                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2890                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2891                 num_permitted_opens++;
2892         }
2893         return (success ? 0 : -1);
2894 }
2895
2896 /*
2897  * Request cancellation of remote forwarding of connection host:port from
2898  * local side.
2899  */
2900 void
2901 channel_request_rforward_cancel(const char *host, u_short port)
2902 {
2903         int i;
2904
2905         if (!compat20)
2906                 return;
2907
2908         for (i = 0; i < num_permitted_opens; i++) {
2909                 if (permitted_opens[i].host_to_connect != NULL &&
2910                     permitted_opens[i].listen_port == port)
2911                         break;
2912         }
2913         if (i >= num_permitted_opens) {
2914                 debug("%s: requested forward not found", __func__);
2915                 return;
2916         }
2917         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2918         packet_put_cstring("cancel-tcpip-forward");
2919         packet_put_char(0);
2920         packet_put_cstring(host == NULL ? "" : host);
2921         packet_put_int(port);
2922         packet_send();
2923
2924         permitted_opens[i].listen_port = 0;
2925         permitted_opens[i].port_to_connect = 0;
2926         xfree(permitted_opens[i].host_to_connect);
2927         permitted_opens[i].host_to_connect = NULL;
2928 }
2929
2930 /*
2931  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2932  * listening for the port, and sends back a success reply (or disconnect
2933  * message if there was an error).
2934  */
2935 int
2936 channel_input_port_forward_request(int is_root, int gateway_ports)
2937 {
2938         u_short port, host_port;
2939         int success = 0;
2940         char *hostname;
2941
2942         /* Get arguments from the packet. */
2943         port = packet_get_int();
2944         hostname = packet_get_string(NULL);
2945         host_port = packet_get_int();
2946
2947 #ifndef HAVE_CYGWIN
2948         /*
2949          * Check that an unprivileged user is not trying to forward a
2950          * privileged port.
2951          */
2952         if (port < IPPORT_RESERVED && !is_root)
2953                 packet_disconnect(
2954                     "Requested forwarding of port %d but user is not root.",
2955                     port);
2956         if (host_port == 0)
2957                 packet_disconnect("Dynamic forwarding denied.");
2958 #endif
2959
2960         /* Initiate forwarding */
2961         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2962             host_port, gateway_ports);
2963
2964         /* Free the argument string. */
2965         xfree(hostname);
2966
2967         return (success ? 0 : -1);
2968 }
2969
2970 /*
2971  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2972  * usually called by the server, because the user could connect to any port
2973  * anyway, and the server has no way to know but to trust the client anyway.
2974  */
2975 void
2976 channel_permit_all_opens(void)
2977 {
2978         if (num_permitted_opens == 0)
2979                 all_opens_permitted = 1;
2980 }
2981
2982 void
2983 channel_add_permitted_opens(char *host, int port)
2984 {
2985         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2986                 fatal("channel_add_permitted_opens: too many forwards");
2987         debug("allow port forwarding to host %s port %d", host, port);
2988
2989         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2990         permitted_opens[num_permitted_opens].port_to_connect = port;
2991         num_permitted_opens++;
2992
2993         all_opens_permitted = 0;
2994 }
2995
2996 int
2997 channel_add_adm_permitted_opens(char *host, int port)
2998 {
2999         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
3000                 fatal("channel_add_adm_permitted_opens: too many forwards");
3001         debug("config allows port forwarding to host %s port %d", host, port);
3002
3003         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3004              = xstrdup(host);
3005         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3006         return ++num_adm_permitted_opens;
3007 }
3008
3009 void
3010 channel_clear_permitted_opens(void)
3011 {
3012         int i;
3013
3014         for (i = 0; i < num_permitted_opens; i++)
3015                 if (permitted_opens[i].host_to_connect != NULL)
3016                         xfree(permitted_opens[i].host_to_connect);
3017         num_permitted_opens = 0;
3018 }
3019
3020 void
3021 channel_clear_adm_permitted_opens(void)
3022 {
3023         int i;
3024
3025         for (i = 0; i < num_adm_permitted_opens; i++)
3026                 if (permitted_adm_opens[i].host_to_connect != NULL)
3027                         xfree(permitted_adm_opens[i].host_to_connect);
3028         num_adm_permitted_opens = 0;
3029 }
3030
3031 void
3032 channel_print_adm_permitted_opens(void)
3033 {
3034         int i;
3035
3036         printf("permitopen");
3037         if (num_adm_permitted_opens == 0) {
3038                 printf(" any\n");
3039                 return;
3040         }
3041         for (i = 0; i < num_adm_permitted_opens; i++)
3042                 if (permitted_adm_opens[i].host_to_connect != NULL)
3043                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3044                             permitted_adm_opens[i].port_to_connect);
3045         printf("\n");
3046 }
3047
3048 /* Try to start non-blocking connect to next host in cctx list */
3049 static int
3050 connect_next(struct channel_connect *cctx)
3051 {
3052         int sock, saved_errno;
3053         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
3054
3055         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3056                 if (cctx->ai->ai_family != AF_INET &&
3057                     cctx->ai->ai_family != AF_INET6)
3058                         continue;
3059                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3060                     ntop, sizeof(ntop), strport, sizeof(strport),
3061                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3062                         error("connect_next: getnameinfo failed");
3063                         continue;
3064                 }
3065                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3066                     cctx->ai->ai_protocol)) == -1) {
3067                         if (cctx->ai->ai_next == NULL)
3068                                 error("socket: %.100s", strerror(errno));
3069                         else
3070                                 verbose("socket: %.100s", strerror(errno));
3071                         continue;
3072                 }
3073                 if (set_nonblock(sock) == -1)
3074                         fatal("%s: set_nonblock(%d)", __func__, sock);
3075                 if (connect(sock, cctx->ai->ai_addr,
3076                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3077                         debug("connect_next: host %.100s ([%.100s]:%s): "
3078                             "%.100s", cctx->host, ntop, strport,
3079                             strerror(errno));
3080                         saved_errno = errno;
3081                         close(sock);
3082                         errno = saved_errno;
3083                         continue;       /* fail -- try next */
3084                 }
3085                 debug("connect_next: host %.100s ([%.100s]:%s) "
3086                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3087                 cctx->ai = cctx->ai->ai_next;
3088                 set_nodelay(sock);
3089                 return sock;
3090         }
3091         return -1;
3092 }
3093
3094 static void
3095 channel_connect_ctx_free(struct channel_connect *cctx)
3096 {
3097         xfree(cctx->host);
3098         if (cctx->aitop)
3099                 freeaddrinfo(cctx->aitop);
3100         bzero(cctx, sizeof(*cctx));
3101         cctx->host = NULL;
3102         cctx->ai = cctx->aitop = NULL;
3103 }
3104
3105 /* Return CONNECTING channel to remote host, port */
3106 static Channel *
3107 connect_to(const char *host, u_short port, char *ctype, char *rname)
3108 {
3109         struct addrinfo hints;
3110         int gaierr;
3111         int sock = -1;
3112         char strport[NI_MAXSERV];
3113         struct channel_connect cctx;
3114         Channel *c;
3115
3116         memset(&cctx, 0, sizeof(cctx));
3117         memset(&hints, 0, sizeof(hints));
3118         hints.ai_family = IPv4or6;
3119         hints.ai_socktype = SOCK_STREAM;
3120         snprintf(strport, sizeof strport, "%d", port);
3121         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
3122                 error("connect_to %.100s: unknown host (%s)", host,
3123                     ssh_gai_strerror(gaierr));
3124                 return NULL;
3125         }
3126
3127         cctx.host = xstrdup(host);
3128         cctx.port = port;
3129         cctx.ai = cctx.aitop;
3130
3131         if ((sock = connect_next(&cctx)) == -1) {
3132                 error("connect to %.100s port %d failed: %s",
3133                     host, port, strerror(errno));
3134                 channel_connect_ctx_free(&cctx);
3135                 return NULL;
3136         }
3137         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3138             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3139         c->connect_ctx = cctx;
3140         return c;
3141 }
3142
3143 Channel *
3144 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3145 {
3146         int i;
3147
3148         for (i = 0; i < num_permitted_opens; i++) {
3149                 if (permitted_opens[i].host_to_connect != NULL &&
3150                     permitted_opens[i].listen_port == listen_port) {
3151                         return connect_to(
3152                             permitted_opens[i].host_to_connect,
3153                             permitted_opens[i].port_to_connect, ctype, rname);
3154                 }
3155         }
3156         error("WARNING: Server requests forwarding for unknown listen_port %d",
3157             listen_port);
3158         return NULL;
3159 }
3160
3161 /* Check if connecting to that port is permitted and connect. */
3162 Channel *
3163 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3164 {
3165         int i, permit, permit_adm = 1;
3166
3167         permit = all_opens_permitted;
3168         if (!permit) {
3169                 for (i = 0; i < num_permitted_opens; i++)
3170                         if (permitted_opens[i].host_to_connect != NULL &&
3171                             permitted_opens[i].port_to_connect == port &&
3172                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3173                                 permit = 1;
3174         }
3175
3176         if (num_adm_permitted_opens > 0) {
3177                 permit_adm = 0;
3178                 for (i = 0; i < num_adm_permitted_opens; i++)
3179                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3180                             permitted_adm_opens[i].port_to_connect == port &&
3181                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3182                             == 0)
3183                                 permit_adm = 1;
3184         }
3185
3186         if (!permit || !permit_adm) {
3187                 logit("Received request to connect to host %.100s port %d, "
3188                     "but the request was denied.", host, port);
3189                 return NULL;
3190         }
3191         return connect_to(host, port, ctype, rname);
3192 }
3193
3194 void
3195 channel_send_window_changes(void)
3196 {
3197         u_int i;
3198         struct winsize ws;
3199
3200         for (i = 0; i < channels_alloc; i++) {
3201                 if (channels[i] == NULL || !channels[i]->client_tty ||
3202                     channels[i]->type != SSH_CHANNEL_OPEN)
3203                         continue;
3204                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3205                         continue;
3206                 channel_request_start(i, "window-change", 0);
3207                 packet_put_int((u_int)ws.ws_col);
3208                 packet_put_int((u_int)ws.ws_row);
3209                 packet_put_int((u_int)ws.ws_xpixel);
3210                 packet_put_int((u_int)ws.ws_ypixel);
3211                 packet_send();
3212         }
3213 }
3214
3215 /* -- X11 forwarding */
3216
3217 /*
3218  * Creates an internet domain socket for listening for X11 connections.
3219  * Returns 0 and a suitable display number for the DISPLAY variable
3220  * stored in display_numberp , or -1 if an error occurs.
3221  */
3222 int
3223 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3224     int single_connection, u_int *display_numberp, int **chanids)
3225 {
3226         Channel *nc = NULL;
3227         int display_number, sock;
3228         u_short port;
3229         struct addrinfo hints, *ai, *aitop;
3230         char strport[NI_MAXSERV];
3231         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3232
3233         if (chanids == NULL)
3234                 return -1;
3235
3236         for (display_number = x11_display_offset;
3237             display_number < MAX_DISPLAYS;
3238             display_number++) {
3239                 port = 6000 + display_number;
3240                 memset(&hints, 0, sizeof(hints));
3241                 hints.ai_family = IPv4or6;
3242                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3243                 hints.ai_socktype = SOCK_STREAM;
3244                 snprintf(strport, sizeof strport, "%d", port);
3245                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3246                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3247                         return -1;
3248                 }
3249                 for (ai = aitop; ai; ai = ai->ai_next) {
3250                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3251                                 continue;
3252                         sock = socket(ai->ai_family, ai->ai_socktype,
3253                             ai->ai_protocol);
3254                         if (sock < 0) {
3255                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3256                                         error("socket: %.100s", strerror(errno));
3257                                         freeaddrinfo(aitop);
3258                                         return -1;
3259                                 } else {
3260                                         debug("x11_create_display_inet: Socket family %d not supported",
3261                                                  ai->ai_family);
3262                                         continue;
3263                                 }
3264                         }
3265                         if (ai->ai_family == AF_INET6)
3266                                 sock_set_v6only(sock);
3267                         if (x11_use_localhost)
3268                                 channel_set_reuseaddr(sock);
3269                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3270                                 debug2("bind port %d: %.100s", port, strerror(errno));
3271                                 close(sock);
3272
3273                                 for (n = 0; n < num_socks; n++) {
3274                                         close(socks[n]);
3275                                 }
3276                                 num_socks = 0;
3277                                 break;
3278                         }
3279                         socks[num_socks++] = sock;
3280                         if (num_socks == NUM_SOCKS)
3281                                 break;
3282                 }
3283                 freeaddrinfo(aitop);
3284                 if (num_socks > 0)
3285                         break;
3286         }
3287         if (display_number >= MAX_DISPLAYS) {
3288                 error("Failed to allocate internet-domain X11 display socket.");
3289                 return -1;
3290         }
3291         /* Start listening for connections on the socket. */
3292         for (n = 0; n < num_socks; n++) {
3293                 sock = socks[n];
3294                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3295                         error("listen: %.100s", strerror(errno));
3296                         close(sock);
3297                         return -1;
3298                 }
3299         }
3300
3301         /* Allocate a channel for each socket. */
3302         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3303         for (n = 0; n < num_socks; n++) {
3304                 sock = socks[n];
3305                 nc = channel_new("x11 listener",
3306                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3307                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3308                     0, "X11 inet listener", 1);
3309                 nc->single_connection = single_connection;
3310                 (*chanids)[n] = nc->self;
3311         }
3312         (*chanids)[n] = -1;
3313
3314         /* Return the display number for the DISPLAY environment variable. */
3315         *display_numberp = display_number;
3316         return (0);
3317 }
3318
3319 static int
3320 connect_local_xsocket_path(const char *pathname)
3321 {
3322         int sock;
3323         struct sockaddr_un addr;
3324
3325         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3326         if (sock < 0)
3327                 error("socket: %.100s", strerror(errno));
3328         memset(&addr, 0, sizeof(addr));
3329         addr.sun_family = AF_UNIX;
3330         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3331         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3332                 return sock;
3333         close(sock);
3334         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3335         return -1;
3336 }
3337
3338 static int
3339 connect_local_xsocket(u_int dnr)
3340 {
3341         char buf[1024];
3342         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3343         return connect_local_xsocket_path(buf);
3344 }
3345
3346 int
3347 x11_connect_display(void)
3348 {
3349         u_int display_number;
3350         const char *display;
3351         char buf[1024], *cp;
3352         struct addrinfo hints, *ai, *aitop;
3353         char strport[NI_MAXSERV];
3354         int gaierr, sock = 0;
3355
3356         /* Try to open a socket for the local X server. */
3357         display = getenv("DISPLAY");
3358         if (!display) {
3359                 error("DISPLAY not set.");
3360                 return -1;
3361         }
3362         /*
3363          * Now we decode the value of the DISPLAY variable and make a
3364          * connection to the real X server.
3365          */
3366
3367         /* Check if the display is from launchd. */
3368 #ifdef __APPLE__
3369         if (strncmp(display, "/tmp/launch", 11) == 0) {
3370                 sock = connect_local_xsocket_path(display);
3371                 if (sock < 0)
3372                         return -1;
3373
3374                 /* OK, we now have a connection to the display. */
3375                 return sock;
3376         }
3377 #endif
3378         /*
3379          * Check if it is a unix domain socket.  Unix domain displays are in
3380          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3381          */
3382         if (strncmp(display, "unix:", 5) == 0 ||
3383             display[0] == ':') {
3384                 /* Connect to the unix domain socket. */
3385                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3386                         error("Could not parse display number from DISPLAY: %.100s",
3387                             display);
3388                         return -1;
3389                 }
3390                 /* Create a socket. */
3391                 sock = connect_local_xsocket(display_number);
3392                 if (sock < 0)
3393                         return -1;
3394
3395                 /* OK, we now have a connection to the display. */
3396                 return sock;
3397         }
3398         /*
3399          * Connect to an inet socket.  The DISPLAY value is supposedly
3400          * hostname:d[.s], where hostname may also be numeric IP address.
3401          */
3402         strlcpy(buf, display, sizeof(buf));
3403         cp = strchr(buf, ':');
3404         if (!cp) {
3405                 error("Could not find ':' in DISPLAY: %.100s", display);
3406                 return -1;
3407         }
3408         *cp = 0;
3409         /* buf now contains the host name.  But first we parse the display number. */
3410         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3411                 error("Could not parse display number from DISPLAY: %.100s",
3412                     display);
3413                 return -1;
3414         }
3415
3416         /* Look up the host address */
3417         memset(&hints, 0, sizeof(hints));
3418         hints.ai_family = IPv4or6;
3419         hints.ai_socktype = SOCK_STREAM;
3420         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3421         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3422                 error("%.100s: unknown host. (%s)", buf,
3423                 ssh_gai_strerror(gaierr));
3424                 return -1;
3425         }
3426         for (ai = aitop; ai; ai = ai->ai_next) {
3427                 /* Create a socket. */
3428                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3429                 if (sock < 0) {
3430                         debug2("socket: %.100s", strerror(errno));
3431                         continue;
3432                 }
3433                 /* Connect it to the display. */
3434                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3435                         debug2("connect %.100s port %u: %.100s", buf,
3436                             6000 + display_number, strerror(errno));
3437                         close(sock);
3438                         continue;
3439                 }
3440                 /* Success */
3441                 break;
3442         }
3443         freeaddrinfo(aitop);
3444         if (!ai) {
3445                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3446                     strerror(errno));
3447                 return -1;
3448         }
3449         set_nodelay(sock);
3450         return sock;
3451 }
3452
3453 /*
3454  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3455  * the remote channel number.  We should do whatever we want, and respond
3456  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3457  */
3458
3459 /* ARGSUSED */
3460 void
3461 x11_input_open(int type, u_int32_t seq, void *ctxt)
3462 {
3463         Channel *c = NULL;
3464         int remote_id, sock = 0;
3465         char *remote_host;
3466
3467         debug("Received X11 open request.");
3468
3469         remote_id = packet_get_int();
3470
3471         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3472                 remote_host = packet_get_string(NULL);
3473         } else {
3474                 remote_host = xstrdup("unknown (remote did not supply name)");
3475         }
3476         packet_check_eom();
3477
3478         /* Obtain a connection to the real X display. */
3479         sock = x11_connect_display();
3480         if (sock != -1) {
3481                 /* Allocate a channel for this connection. */
3482                 c = channel_new("connected x11 socket",
3483                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3484                     remote_host, 1);
3485                 c->remote_id = remote_id;
3486                 c->force_drain = 1;
3487         }
3488         xfree(remote_host);
3489         if (c == NULL) {
3490                 /* Send refusal to the remote host. */
3491                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3492                 packet_put_int(remote_id);
3493         } else {
3494                 /* Send a confirmation to the remote host. */
3495                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3496                 packet_put_int(remote_id);
3497                 packet_put_int(c->self);
3498         }
3499         packet_send();
3500 }
3501
3502 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3503 /* ARGSUSED */
3504 void
3505 deny_input_open(int type, u_int32_t seq, void *ctxt)
3506 {
3507         int rchan = packet_get_int();
3508
3509         switch (type) {
3510         case SSH_SMSG_AGENT_OPEN:
3511                 error("Warning: ssh server tried agent forwarding.");
3512                 break;
3513         case SSH_SMSG_X11_OPEN:
3514                 error("Warning: ssh server tried X11 forwarding.");
3515                 break;
3516         default:
3517                 error("deny_input_open: type %d", type);
3518                 break;
3519         }
3520         error("Warning: this is probably a break-in attempt by a malicious server.");
3521         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3522         packet_put_int(rchan);
3523         packet_send();
3524 }
3525
3526 /*
3527  * Requests forwarding of X11 connections, generates fake authentication
3528  * data, and enables authentication spoofing.
3529  * This should be called in the client only.
3530  */
3531 void
3532 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3533     const char *proto, const char *data)
3534 {
3535         u_int data_len = (u_int) strlen(data) / 2;
3536         u_int i, value;
3537         char *new_data;
3538         int screen_number;
3539         const char *cp;
3540         u_int32_t rnd = 0;
3541
3542         if (x11_saved_display == NULL)
3543                 x11_saved_display = xstrdup(disp);
3544         else if (strcmp(disp, x11_saved_display) != 0) {
3545                 error("x11_request_forwarding_with_spoofing: different "
3546                     "$DISPLAY already forwarded");
3547                 return;
3548         }
3549
3550         cp = strchr(disp, ':');
3551         if (cp)
3552                 cp = strchr(cp, '.');
3553         if (cp)
3554                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3555         else
3556                 screen_number = 0;
3557
3558         if (x11_saved_proto == NULL) {
3559                 /* Save protocol name. */
3560                 x11_saved_proto = xstrdup(proto);
3561                 /*
3562                  * Extract real authentication data and generate fake data
3563                  * of the same length.
3564                  */
3565                 x11_saved_data = xmalloc(data_len);
3566                 x11_fake_data = xmalloc(data_len);
3567                 for (i = 0; i < data_len; i++) {
3568                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3569                                 fatal("x11_request_forwarding: bad "
3570                                     "authentication data: %.100s", data);
3571                         if (i % 4 == 0)
3572                                 rnd = arc4random();
3573                         x11_saved_data[i] = value;
3574                         x11_fake_data[i] = rnd & 0xff;
3575                         rnd >>= 8;
3576                 }
3577                 x11_saved_data_len = data_len;
3578                 x11_fake_data_len = data_len;
3579         }
3580
3581         /* Convert the fake data into hex. */
3582         new_data = tohex(x11_fake_data, data_len);
3583
3584         /* Send the request packet. */
3585         if (compat20) {
3586                 channel_request_start(client_session_id, "x11-req", 0);
3587                 packet_put_char(0);     /* XXX bool single connection */
3588         } else {
3589                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3590         }
3591         packet_put_cstring(proto);
3592         packet_put_cstring(new_data);
3593         packet_put_int(screen_number);
3594         packet_send();
3595         packet_write_wait();
3596         xfree(new_data);
3597 }
3598
3599
3600 /* -- agent forwarding */
3601
3602 /* Sends a message to the server to request authentication fd forwarding. */
3603
3604 void
3605 auth_request_forwarding(void)
3606 {
3607         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3608         packet_send();
3609         packet_write_wait();
3610 }