channels.c

   1 /* $OpenBSD: channels.c,v 1.302 2010/01/26 01:28:35 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         direct = (strcmp(rtype, "direct-tcpip") == 0);
1380
1381         snprintf(buf, sizeof buf,
1382             "%s: listening port %d for %.100s port %d, "
1383             "connect from %.200s port %d",
1384             rtype, c->listening_port, c->path, c->host_port,
1385             remote_ipaddr, remote_port);
1386
1387         xfree(c->remote_name);
1388         c->remote_name = xstrdup(buf);
1389
1390         if (compat20) {
1391                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1392                 packet_put_cstring(rtype);
1393                 packet_put_int(c->self);
1394                 packet_put_int(c->local_window_max);
1395                 packet_put_int(c->local_maxpacket);
1396                 if (direct) {
1397                         /* target host, port */
1398                         packet_put_cstring(c->path);
1399                         packet_put_int(c->host_port);
1400                 } else {
1401                         /* listen address, port */
1402                         packet_put_cstring(c->path);
1403                         packet_put_int(c->listening_port);
1404                 }
1405                 /* originator host and port */
1406                 packet_put_cstring(remote_ipaddr);
1407                 packet_put_int((u_int)remote_port);
1408                 packet_send();
1409         } else {
1410                 packet_start(SSH_MSG_PORT_OPEN);
1411                 packet_put_int(c->self);
1412                 packet_put_cstring(c->path);
1413                 packet_put_int(c->host_port);
1414                 if (packet_get_protocol_flags() &
1415                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1416                         packet_put_cstring(c->remote_name);
1417                 packet_send();
1418         }
1419         xfree(remote_ipaddr);
1420 }
1421
1422 static void
1423 channel_set_reuseaddr(int fd)
1424 {
1425         int on = 1;
1426
1427         /*
1428          * Set socket options.
1429          * Allow local port reuse in TIME_WAIT.
1430          */
1431         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1432                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1433 }
1434
1435 /*
1436  * This socket is listening for connections to a forwarded TCP/IP port.
1437  */
1438 /* ARGSUSED */
1439 static void
1440 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1441 {
1442         Channel *nc;
1443         struct sockaddr_storage addr;
1444         int newsock, nextstate;
1445         socklen_t addrlen;
1446         char *rtype;
1447
1448         if (FD_ISSET(c->sock, readset)) {
1449                 debug("Connection to port %d forwarding "
1450                     "to %.100s port %d requested.",
1451                     c->listening_port, c->path, c->host_port);
1452
1453                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1454                         nextstate = SSH_CHANNEL_OPENING;
1455                         rtype = "forwarded-tcpip";
1456                 } else {
1457                         if (c->host_port == 0) {
1458                                 nextstate = SSH_CHANNEL_DYNAMIC;
1459                                 rtype = "dynamic-tcpip";
1460                         } else {
1461                                 nextstate = SSH_CHANNEL_OPENING;
1462                                 rtype = "direct-tcpip";
1463                         }
1464                 }
1465
1466                 addrlen = sizeof(addr);
1467                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1468                 if (newsock < 0) {
1469                         error("accept: %.100s", strerror(errno));
1470                         return;
1471                 }
1472                 set_nodelay(newsock);
1473                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1474                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1475                 nc->listening_port = c->listening_port;
1476                 nc->host_port = c->host_port;
1477                 if (c->path != NULL)
1478                         nc->path = xstrdup(c->path);
1479
1480                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1481                         port_open_helper(nc, rtype);
1482         }
1483 }
1484
1485 /*
1486  * This is the authentication agent socket listening for connections from
1487  * clients.
1488  */
1489 /* ARGSUSED */
1490 static void
1491 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1492 {
1493         Channel *nc;
1494         int newsock;
1495         struct sockaddr_storage addr;
1496         socklen_t addrlen;
1497
1498         if (FD_ISSET(c->sock, readset)) {
1499                 addrlen = sizeof(addr);
1500                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1501                 if (newsock < 0) {
1502                         error("accept from auth socket: %.100s", strerror(errno));
1503                         return;
1504                 }
1505                 nc = channel_new("accepted auth socket",
1506                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1507                     c->local_window_max, c->local_maxpacket,
1508                     0, "accepted auth socket", 1);
1509                 if (compat20) {
1510                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1511                         packet_put_cstring("auth-agent@openssh.com");
1512                         packet_put_int(nc->self);
1513                         packet_put_int(c->local_window_max);
1514                         packet_put_int(c->local_maxpacket);
1515                 } else {
1516                         packet_start(SSH_SMSG_AGENT_OPEN);
1517                         packet_put_int(nc->self);
1518                 }
1519                 packet_send();
1520         }
1521 }
1522
1523 /* ARGSUSED */
1524 static void
1525 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1526 {
1527         int err = 0, sock;
1528         socklen_t sz = sizeof(err);
1529
1530         if (FD_ISSET(c->sock, writeset)) {
1531                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1532                         err = errno;
1533                         error("getsockopt SO_ERROR failed");
1534                 }
1535                 if (err == 0) {
1536                         debug("channel %d: connected to %s port %d",
1537                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1538                         channel_connect_ctx_free(&c->connect_ctx);
1539                         c->type = SSH_CHANNEL_OPEN;
1540                         if (compat20) {
1541                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1542                                 packet_put_int(c->remote_id);
1543                                 packet_put_int(c->self);
1544                                 packet_put_int(c->local_window);
1545                                 packet_put_int(c->local_maxpacket);
1546                         } else {
1547                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1548                                 packet_put_int(c->remote_id);
1549                                 packet_put_int(c->self);
1550                         }
1551                 } else {
1552                         debug("channel %d: connection failed: %s",
1553                             c->self, strerror(err));
1554                         /* Try next address, if any */
1555                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1556                                 close(c->sock);
1557                                 c->sock = c->rfd = c->wfd = sock;
1558                                 channel_max_fd = channel_find_maxfd();
1559                                 return;
1560                         }
1561                         /* Exhausted all addresses */
1562                         error("connect_to %.100s port %d: failed.",
1563                             c->connect_ctx.host, c->connect_ctx.port);
1564                         channel_connect_ctx_free(&c->connect_ctx);
1565                         if (compat20) {
1566                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1567                                 packet_put_int(c->remote_id);
1568                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1569                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1570                                         packet_put_cstring(strerror(err));
1571                                         packet_put_cstring("");
1572                                 }
1573                         } else {
1574                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1575                                 packet_put_int(c->remote_id);
1576                         }
1577                         chan_mark_dead(c);
1578                 }
1579                 packet_send();
1580         }
1581 }
1582
1583 /* ARGSUSED */
1584 static int
1585 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1586 {
1587         char buf[CHAN_RBUF];
1588         int len, force;
1589
1590         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1591         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1592                 errno = 0;
1593                 len = read(c->rfd, buf, sizeof(buf));
1594                 if (len < 0 && (errno == EINTR ||
1595                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1596                         return 1;
1597 #ifndef PTY_ZEROREAD
1598                 if (len <= 0) {
1599 #else
1600                 if ((!c->isatty && len <= 0) ||
1601                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1602 #endif
1603                         debug2("channel %d: read<=0 rfd %d len %d",
1604                             c->self, c->rfd, len);
1605                         if (c->type != SSH_CHANNEL_OPEN) {
1606                                 debug2("channel %d: not open", c->self);
1607                                 chan_mark_dead(c);
1608                                 return -1;
1609                         } else if (compat13) {
1610                                 buffer_clear(&c->output);
1611                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1612                                 debug2("channel %d: input draining.", c->self);
1613                         } else {
1614                                 chan_read_failed(c);
1615                         }
1616                         return -1;
1617                 }
1618                 if (c->input_filter != NULL) {
1619                         if (c->input_filter(c, buf, len) == -1) {
1620                                 debug2("channel %d: filter stops", c->self);
1621                                 chan_read_failed(c);
1622                         }
1623                 } else if (c->datagram) {
1624                         buffer_put_string(&c->input, buf, len);
1625                 } else {
1626                         buffer_append(&c->input, buf, len);
1627                 }
1628         }
1629         return 1;
1630 }
1631
1632 /* ARGSUSED */
1633 static int
1634 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1635 {
1636         struct termios tio;
1637         u_char *data = NULL, *buf;
1638         u_int dlen;
1639         int len;
1640
1641         /* Send buffered output data to the socket. */
1642         if (c->wfd != -1 &&
1643             FD_ISSET(c->wfd, writeset) &&
1644             buffer_len(&c->output) > 0) {
1645                 if (c->output_filter != NULL) {
1646                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1647                                 debug2("channel %d: filter stops", c->self);
1648                                 if (c->type != SSH_CHANNEL_OPEN)
1649                                         chan_mark_dead(c);
1650                                 else
1651                                         chan_write_failed(c);
1652                                 return -1;
1653                         }
1654                 } else if (c->datagram) {
1655                         buf = data = buffer_get_string(&c->output, &dlen);
1656                 } else {
1657                         buf = data = buffer_ptr(&c->output);
1658                         dlen = buffer_len(&c->output);
1659                 }
1660
1661                 if (c->datagram) {
1662                         /* ignore truncated writes, datagrams might get lost */
1663                         c->local_consumed += dlen + 4;
1664                         len = write(c->wfd, buf, dlen);
1665                         xfree(data);
1666                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1667                             errno == EWOULDBLOCK))
1668                                 return 1;
1669                         if (len <= 0) {
1670                                 if (c->type != SSH_CHANNEL_OPEN)
1671                                         chan_mark_dead(c);
1672                                 else
1673                                         chan_write_failed(c);
1674                                 return -1;
1675                         }
1676                         return 1;
1677                 }
1678 #ifdef _AIX
1679                 /* XXX: Later AIX versions can't push as much data to tty */
1680                 if (compat20 && c->wfd_isatty)
1681                         dlen = MIN(dlen, 8*1024);
1682 #endif
1683
1684                 len = write(c->wfd, buf, dlen);
1685                 if (len < 0 &&
1686                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1687                         return 1;
1688                 if (len <= 0) {
1689                         if (c->type != SSH_CHANNEL_OPEN) {
1690                                 debug2("channel %d: not open", c->self);
1691                                 chan_mark_dead(c);
1692                                 return -1;
1693                         } else if (compat13) {
1694                                 buffer_clear(&c->output);
1695                                 debug2("channel %d: input draining.", c->self);
1696                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1697                         } else {
1698                                 chan_write_failed(c);
1699                         }
1700                         return -1;
1701                 }
1702 #ifndef BROKEN_TCGETATTR_ICANON
1703                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1704                         if (tcgetattr(c->wfd, &tio) == 0 &&
1705                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1706                                 /*
1707                                  * Simulate echo to reduce the impact of
1708                                  * traffic analysis. We need to match the
1709                                  * size of a SSH2_MSG_CHANNEL_DATA message
1710                                  * (4 byte channel id + buf)
1711                                  */
1712                                 packet_send_ignore(4 + len);
1713                                 packet_send();
1714                         }
1715                 }
1716 #endif
1717                 buffer_consume(&c->output, len);
1718                 if (compat20 && len > 0) {
1719                         c->local_consumed += len;
1720                 }
1721         }
1722         return 1;
1723 }
1724
1725 static int
1726 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1727 {
1728         char buf[CHAN_RBUF];
1729         int len;
1730
1731 /** XXX handle drain efd, too */
1732         if (c->efd != -1) {
1733                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1734                     FD_ISSET(c->efd, writeset) &&
1735                     buffer_len(&c->extended) > 0) {
1736                         len = write(c->efd, buffer_ptr(&c->extended),
1737                             buffer_len(&c->extended));
1738                         debug2("channel %d: written %d to efd %d",
1739                             c->self, len, c->efd);
1740                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1741                             errno == EWOULDBLOCK))
1742                                 return 1;
1743                         if (len <= 0) {
1744                                 debug2("channel %d: closing write-efd %d",
1745                                     c->self, c->efd);
1746                                 channel_close_fd(&c->efd);
1747                         } else {
1748                                 buffer_consume(&c->extended, len);
1749                                 c->local_consumed += len;
1750                         }
1751                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1752                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1753                         len = read(c->efd, buf, sizeof(buf));
1754                         debug2("channel %d: read %d from efd %d",
1755                             c->self, len, c->efd);
1756                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1757                             errno == EWOULDBLOCK) && !c->detach_close)))
1758                                 return 1;
1759                         if (len <= 0) {
1760                                 debug2("channel %d: closing read-efd %d",
1761                                     c->self, c->efd);
1762                                 channel_close_fd(&c->efd);
1763                         } else {
1764                                 buffer_append(&c->extended, buf, len);
1765                         }
1766                 }
1767         }
1768         return 1;
1769 }
1770
1771 static int
1772 channel_check_window(Channel *c)
1773 {
1774         if (c->type == SSH_CHANNEL_OPEN &&
1775             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1776             ((c->local_window_max - c->local_window >
1777             c->local_maxpacket*3) ||
1778             c->local_window < c->local_window_max/2) &&
1779             c->local_consumed > 0) {
1780                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1781                 packet_put_int(c->remote_id);
1782                 packet_put_int(c->local_consumed);
1783                 packet_send();
1784                 debug2("channel %d: window %d sent adjust %d",
1785                     c->self, c->local_window,
1786                     c->local_consumed);
1787                 c->local_window += c->local_consumed;
1788                 c->local_consumed = 0;
1789         }
1790         return 1;
1791 }
1792
1793 static void
1794 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1795 {
1796         channel_handle_rfd(c, readset, writeset);
1797         channel_handle_wfd(c, readset, writeset);
1798         if (!compat20)
1799                 return;
1800         channel_handle_efd(c, readset, writeset);
1801         channel_check_window(c);
1802 }
1803
1804 static u_int
1805 read_mux(Channel *c, u_int need)
1806 {
1807         char buf[CHAN_RBUF];
1808         int len;
1809         u_int rlen;
1810
1811         if (buffer_len(&c->input) < need) {
1812                 rlen = need - buffer_len(&c->input);
1813                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1814                 if (len <= 0) {
1815                         if (errno != EINTR && errno != EAGAIN) {
1816                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1817                                     c->self, c->rfd, len);
1818                                 chan_read_failed(c);
1819                                 return 0;
1820                         }
1821                 } else
1822                         buffer_append(&c->input, buf, len);
1823         }
1824         return buffer_len(&c->input);
1825 }
1826
1827 static void
1828 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1829 {
1830         u_int need;
1831         ssize_t len;
1832
1833         if (!compat20)
1834                 fatal("%s: entered with !compat20", __func__);
1835
1836         if (c->rfd != -1 && FD_ISSET(c->rfd, readset) &&
1837             (c->istate == CHAN_INPUT_OPEN ||
1838             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1839                 /*
1840                  * Don't not read past the precise end of packets to
1841                  * avoid disrupting fd passing.
1842                  */
1843                 if (read_mux(c, 4) < 4) /* read header */
1844                         return;
1845                 need = get_u32(buffer_ptr(&c->input));
1846 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1847                 if (need > CHANNEL_MUX_MAX_PACKET) {
1848                         debug2("channel %d: packet too big %u > %u",
1849                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1850                         chan_rcvd_oclose(c);
1851                         return;
1852                 }
1853                 if (read_mux(c, need + 4) < need + 4) /* read body */
1854                         return;
1855                 if (c->mux_rcb(c) != 0) {
1856                         debug("channel %d: mux_rcb failed", c->self);
1857                         chan_mark_dead(c);
1858                         return;
1859                 }
1860         }
1861
1862         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1863             buffer_len(&c->output) > 0) {
1864                 len = write(c->wfd, buffer_ptr(&c->output),
1865                     buffer_len(&c->output));
1866                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1867                         return;
1868                 if (len <= 0) {
1869                         chan_mark_dead(c);
1870                         return;
1871                 }
1872                 buffer_consume(&c->output, len);
1873         }
1874 }
1875
1876 static void
1877 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1878 {
1879         Channel *nc;
1880         struct sockaddr_storage addr;
1881         socklen_t addrlen;
1882         int newsock;
1883         uid_t euid;
1884         gid_t egid;
1885
1886         if (!FD_ISSET(c->sock, readset))
1887                 return;
1888
1889         debug("multiplexing control connection");
1890
1891         /*
1892          * Accept connection on control socket
1893          */
1894         memset(&addr, 0, sizeof(addr));
1895         addrlen = sizeof(addr);
1896         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1897             &addrlen)) == -1) {
1898                 error("%s accept: %s", __func__, strerror(errno));
1899                 return;
1900         }
1901
1902         if (getpeereid(newsock, &euid, &egid) < 0) {
1903                 error("%s getpeereid failed: %s", __func__,
1904                     strerror(errno));
1905                 close(newsock);
1906                 return;
1907         }
1908         if ((euid != 0) && (getuid() != euid)) {
1909                 error("multiplex uid mismatch: peer euid %u != uid %u",
1910                     (u_int)euid, (u_int)getuid());
1911                 close(newsock);
1912                 return;
1913         }
1914         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
1915             newsock, newsock, -1, c->local_window_max,
1916             c->local_maxpacket, 0, "mux-control", 1);
1917         nc->mux_rcb = c->mux_rcb;
1918         debug3("%s: new mux channel %d fd %d", __func__,
1919             nc->self, nc->sock);
1920         /* establish state */
1921         nc->mux_rcb(nc);
1922         /* mux state transitions must not elicit protocol messages */
1923         nc->flags |= CHAN_LOCAL;
1924 }
1925
1926 /* ARGSUSED */
1927 static void
1928 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1929 {
1930         int len;
1931
1932         /* Send buffered output data to the socket. */
1933         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1934                 len = write(c->sock, buffer_ptr(&c->output),
1935                             buffer_len(&c->output));
1936                 if (len <= 0)
1937                         buffer_clear(&c->output);
1938                 else
1939                         buffer_consume(&c->output, len);
1940         }
1941 }
1942
1943 static void
1944 channel_handler_init_20(void)
1945 {
1946         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1947         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1948         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1949         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1950         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1951         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1952         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1953         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1954         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
1955         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
1956
1957         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1958         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1959         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1960         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1961         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1962         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1963         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1964         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
1965         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
1966 }
1967
1968 static void
1969 channel_handler_init_13(void)
1970 {
1971         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1972         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1973         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1974         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1975         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1976         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1977         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1978         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1979         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1980
1981         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1982         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1983         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1984         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1985         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1986         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1987         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1988 }
1989
1990 static void
1991 channel_handler_init_15(void)
1992 {
1993         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1994         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1995         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1996         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1997         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1998         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1999         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2000
2001         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2002         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2003         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2004         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2005         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2006         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2007 }
2008
2009 static void
2010 channel_handler_init(void)
2011 {
2012         int i;
2013
2014         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2015                 channel_pre[i] = NULL;
2016                 channel_post[i] = NULL;
2017         }
2018         if (compat20)
2019                 channel_handler_init_20();
2020         else if (compat13)
2021                 channel_handler_init_13();
2022         else
2023                 channel_handler_init_15();
2024 }
2025
2026 /* gc dead channels */
2027 static void
2028 channel_garbage_collect(Channel *c)
2029 {
2030         if (c == NULL)
2031                 return;
2032         if (c->detach_user != NULL) {
2033                 if (!chan_is_dead(c, c->detach_close))
2034                         return;
2035                 debug2("channel %d: gc: notify user", c->self);
2036                 c->detach_user(c->self, NULL);
2037                 /* if we still have a callback */
2038                 if (c->detach_user != NULL)
2039                         return;
2040                 debug2("channel %d: gc: user detached", c->self);
2041         }
2042         if (!chan_is_dead(c, 1))
2043                 return;
2044         debug2("channel %d: garbage collecting", c->self);
2045         channel_free(c);
2046 }
2047
2048 static void
2049 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
2050 {
2051         static int did_init = 0;
2052         u_int i, oalloc;
2053         Channel *c;
2054
2055         if (!did_init) {
2056                 channel_handler_init();
2057                 did_init = 1;
2058         }
2059         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2060                 c = channels[i];
2061                 if (c == NULL)
2062                         continue;
2063                 if (c->delayed) {
2064                         if (ftab == channel_pre)
2065                                 c->delayed = 0;
2066                         else
2067                                 continue;
2068                 }
2069                 if (ftab[c->type] != NULL)
2070                         (*ftab[c->type])(c, readset, writeset);
2071                 channel_garbage_collect(c);
2072         }
2073 }
2074
2075 /*
2076  * Allocate/update select bitmasks and add any bits relevant to channels in
2077  * select bitmasks.
2078  */
2079 void
2080 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2081     u_int *nallocp, int rekeying)
2082 {
2083         u_int n, sz, nfdset;
2084
2085         n = MAX(*maxfdp, channel_max_fd);
2086
2087         nfdset = howmany(n+1, NFDBITS);
2088         /* Explicitly test here, because xrealloc isn't always called */
2089         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
2090                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2091         sz = nfdset * sizeof(fd_mask);
2092
2093         /* perhaps check sz < nalloc/2 and shrink? */
2094         if (*readsetp == NULL || sz > *nallocp) {
2095                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2096                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2097                 *nallocp = sz;
2098         }
2099         *maxfdp = n;
2100         memset(*readsetp, 0, sz);
2101         memset(*writesetp, 0, sz);
2102
2103         if (!rekeying)
2104                 channel_handler(channel_pre, *readsetp, *writesetp);
2105 }
2106
2107 /*
2108  * After select, perform any appropriate operations for channels which have
2109  * events pending.
2110  */
2111 void
2112 channel_after_select(fd_set *readset, fd_set *writeset)
2113 {
2114         channel_handler(channel_post, readset, writeset);
2115 }
2116
2117
2118 /* If there is data to send to the connection, enqueue some of it now. */
2119 void
2120 channel_output_poll(void)
2121 {
2122         Channel *c;
2123         u_int i, len;
2124
2125         for (i = 0; i < channels_alloc; i++) {
2126                 c = channels[i];
2127                 if (c == NULL)
2128                         continue;
2129
2130                 /*
2131                  * We are only interested in channels that can have buffered
2132                  * incoming data.
2133                  */
2134                 if (compat13) {
2135                         if (c->type != SSH_CHANNEL_OPEN &&
2136                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2137                                 continue;
2138                 } else {
2139                         if (c->type != SSH_CHANNEL_OPEN)
2140                                 continue;
2141                 }
2142                 if (compat20 &&
2143                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2144                         /* XXX is this true? */
2145                         debug3("channel %d: will not send data after close", c->self);
2146                         continue;
2147                 }
2148
2149                 /* Get the amount of buffered data for this channel. */
2150                 if ((c->istate == CHAN_INPUT_OPEN ||
2151                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2152                     (len = buffer_len(&c->input)) > 0) {
2153                         if (c->datagram) {
2154                                 if (len > 0) {
2155                                         u_char *data;
2156                                         u_int dlen;
2157
2158                                         data = buffer_get_string(&c->input,
2159                                             &dlen);
2160                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2161                                         packet_put_int(c->remote_id);
2162                                         packet_put_string(data, dlen);
2163                                         packet_send();
2164                                         c->remote_window -= dlen + 4;
2165                                         xfree(data);
2166                                 }
2167                                 continue;
2168                         }
2169                         /*
2170                          * Send some data for the other side over the secure
2171                          * connection.
2172                          */
2173                         if (compat20) {
2174                                 if (len > c->remote_window)
2175                                         len = c->remote_window;
2176                                 if (len > c->remote_maxpacket)
2177                                         len = c->remote_maxpacket;
2178                         } else {
2179                                 if (packet_is_interactive()) {
2180                                         if (len > 1024)
2181                                                 len = 512;
2182                                 } else {
2183                                         /* Keep the packets at reasonable size. */
2184                                         if (len > packet_get_maxsize()/2)
2185                                                 len = packet_get_maxsize()/2;
2186                                 }
2187                         }
2188                         if (len > 0) {
2189                                 packet_start(compat20 ?
2190                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2191                                 packet_put_int(c->remote_id);
2192                                 packet_put_string(buffer_ptr(&c->input), len);
2193                                 packet_send();
2194                                 buffer_consume(&c->input, len);
2195                                 c->remote_window -= len;
2196                         }
2197                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2198                         if (compat13)
2199                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2200                         /*
2201                          * input-buffer is empty and read-socket shutdown:
2202                          * tell peer, that we will not send more data: send IEOF.
2203                          * hack for extended data: delay EOF if EFD still in use.
2204                          */
2205                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2206                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2207                                     c->self, c->efd, buffer_len(&c->extended));
2208                         else
2209                                 chan_ibuf_empty(c);
2210                 }
2211                 /* Send extended data, i.e. stderr */
2212                 if (compat20 &&
2213                     !(c->flags & CHAN_EOF_SENT) &&
2214                     c->remote_window > 0 &&
2215                     (len = buffer_len(&c->extended)) > 0 &&
2216                     c->extended_usage == CHAN_EXTENDED_READ) {
2217                         debug2("channel %d: rwin %u elen %u euse %d",
2218                             c->self, c->remote_window, buffer_len(&c->extended),
2219                             c->extended_usage);
2220                         if (len > c->remote_window)
2221                                 len = c->remote_window;
2222                         if (len > c->remote_maxpacket)
2223                                 len = c->remote_maxpacket;
2224                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2225                         packet_put_int(c->remote_id);
2226                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2227                         packet_put_string(buffer_ptr(&c->extended), len);
2228                         packet_send();
2229                         buffer_consume(&c->extended, len);
2230                         c->remote_window -= len;
2231                         debug2("channel %d: sent ext data %d", c->self, len);
2232                 }
2233         }
2234 }
2235
2236
2237 /* -- protocol input */
2238
2239 /* ARGSUSED */
2240 void
2241 channel_input_data(int type, u_int32_t seq, void *ctxt)
2242 {
2243         int id;
2244         char *data;
2245         u_int data_len;
2246         Channel *c;
2247
2248         /* Get the channel number and verify it. */
2249         id = packet_get_int();
2250         c = channel_lookup(id);
2251         if (c == NULL)
2252                 packet_disconnect("Received data for nonexistent channel %d.", id);
2253
2254         /* Ignore any data for non-open channels (might happen on close) */
2255         if (c->type != SSH_CHANNEL_OPEN &&
2256             c->type != SSH_CHANNEL_X11_OPEN)
2257                 return;
2258
2259         /* Get the data. */
2260         data = packet_get_string_ptr(&data_len);
2261
2262         /*
2263          * Ignore data for protocol > 1.3 if output end is no longer open.
2264          * For protocol 2 the sending side is reducing its window as it sends
2265          * data, so we must 'fake' consumption of the data in order to ensure
2266          * that window updates are sent back.  Otherwise the connection might
2267          * deadlock.
2268          */
2269         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2270                 if (compat20) {
2271                         c->local_window -= data_len;
2272                         c->local_consumed += data_len;
2273                 }
2274                 return;
2275         }
2276
2277         if (compat20) {
2278                 if (data_len > c->local_maxpacket) {
2279                         logit("channel %d: rcvd big packet %d, maxpack %d",
2280                             c->self, data_len, c->local_maxpacket);
2281                 }
2282                 if (data_len > c->local_window) {
2283                         logit("channel %d: rcvd too much data %d, win %d",
2284                             c->self, data_len, c->local_window);
2285                         return;
2286                 }
2287                 c->local_window -= data_len;
2288         }
2289         if (c->datagram)
2290                 buffer_put_string(&c->output, data, data_len);
2291         else
2292                 buffer_append(&c->output, data, data_len);
2293         packet_check_eom();
2294 }
2295
2296 /* ARGSUSED */
2297 void
2298 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2299 {
2300         int id;
2301         char *data;
2302         u_int data_len, tcode;
2303         Channel *c;
2304
2305         /* Get the channel number and verify it. */
2306         id = packet_get_int();
2307         c = channel_lookup(id);
2308
2309         if (c == NULL)
2310                 packet_disconnect("Received extended_data for bad channel %d.", id);
2311         if (c->type != SSH_CHANNEL_OPEN) {
2312                 logit("channel %d: ext data for non open", id);
2313                 return;
2314         }
2315         if (c->flags & CHAN_EOF_RCVD) {
2316                 if (datafellows & SSH_BUG_EXTEOF)
2317                         debug("channel %d: accepting ext data after eof", id);
2318                 else
2319                         packet_disconnect("Received extended_data after EOF "
2320                             "on channel %d.", id);
2321         }
2322         tcode = packet_get_int();
2323         if (c->efd == -1 ||
2324             c->extended_usage != CHAN_EXTENDED_WRITE ||
2325             tcode != SSH2_EXTENDED_DATA_STDERR) {
2326                 logit("channel %d: bad ext data", c->self);
2327                 return;
2328         }
2329         data = packet_get_string(&data_len);
2330         packet_check_eom();
2331         if (data_len > c->local_window) {
2332                 logit("channel %d: rcvd too much extended_data %d, win %d",
2333                     c->self, data_len, c->local_window);
2334                 xfree(data);
2335                 return;
2336         }
2337         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2338         c->local_window -= data_len;
2339         buffer_append(&c->extended, data, data_len);
2340         xfree(data);
2341 }
2342
2343 /* ARGSUSED */
2344 void
2345 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2346 {
2347         int id;
2348         Channel *c;
2349
2350         id = packet_get_int();
2351         packet_check_eom();
2352         c = channel_lookup(id);
2353         if (c == NULL)
2354                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2355         chan_rcvd_ieof(c);
2356
2357         /* XXX force input close */
2358         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2359                 debug("channel %d: FORCE input drain", c->self);
2360                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2361                 if (buffer_len(&c->input) == 0)
2362                         chan_ibuf_empty(c);
2363         }
2364
2365 }
2366
2367 /* ARGSUSED */
2368 void
2369 channel_input_close(int type, u_int32_t seq, void *ctxt)
2370 {
2371         int id;
2372         Channel *c;
2373
2374         id = packet_get_int();
2375         packet_check_eom();
2376         c = channel_lookup(id);
2377         if (c == NULL)
2378                 packet_disconnect("Received close for nonexistent channel %d.", id);
2379
2380         /*
2381          * Send a confirmation that we have closed the channel and no more
2382          * data is coming for it.
2383          */
2384         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2385         packet_put_int(c->remote_id);
2386         packet_send();
2387
2388         /*
2389          * If the channel is in closed state, we have sent a close request,
2390          * and the other side will eventually respond with a confirmation.
2391          * Thus, we cannot free the channel here, because then there would be
2392          * no-one to receive the confirmation.  The channel gets freed when
2393          * the confirmation arrives.
2394          */
2395         if (c->type != SSH_CHANNEL_CLOSED) {
2396                 /*
2397                  * Not a closed channel - mark it as draining, which will
2398                  * cause it to be freed later.
2399                  */
2400                 buffer_clear(&c->input);
2401                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2402         }
2403 }
2404
2405 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2406 /* ARGSUSED */
2407 void
2408 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2409 {
2410         int id = packet_get_int();
2411         Channel *c = channel_lookup(id);
2412
2413         packet_check_eom();
2414         if (c == NULL)
2415                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2416         chan_rcvd_oclose(c);
2417 }
2418
2419 /* ARGSUSED */
2420 void
2421 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2422 {
2423         int id = packet_get_int();
2424         Channel *c = channel_lookup(id);
2425
2426         packet_check_eom();
2427         if (c == NULL)
2428                 packet_disconnect("Received close confirmation for "
2429                     "out-of-range channel %d.", id);
2430         if (c->type != SSH_CHANNEL_CLOSED)
2431                 packet_disconnect("Received close confirmation for "
2432                     "non-closed channel %d (type %d).", id, c->type);
2433         channel_free(c);
2434 }
2435
2436 /* ARGSUSED */
2437 void
2438 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2439 {
2440         int id, remote_id;
2441         Channel *c;
2442
2443         id = packet_get_int();
2444         c = channel_lookup(id);
2445
2446         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2447                 packet_disconnect("Received open confirmation for "
2448                     "non-opening channel %d.", id);
2449         remote_id = packet_get_int();
2450         /* Record the remote channel number and mark that the channel is now open. */
2451         c->remote_id = remote_id;
2452         c->type = SSH_CHANNEL_OPEN;
2453
2454         if (compat20) {
2455                 c->remote_window = packet_get_int();
2456                 c->remote_maxpacket = packet_get_int();
2457                 if (c->open_confirm) {
2458                         debug2("callback start");
2459                         c->open_confirm(c->self, c->open_confirm_ctx);
2460                         debug2("callback done");
2461                 }
2462                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2463                     c->remote_window, c->remote_maxpacket);
2464         }
2465         packet_check_eom();
2466 }
2467
2468 static char *
2469 reason2txt(int reason)
2470 {
2471         switch (reason) {
2472         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2473                 return "administratively prohibited";
2474         case SSH2_OPEN_CONNECT_FAILED:
2475                 return "connect failed";
2476         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2477                 return "unknown channel type";
2478         case SSH2_OPEN_RESOURCE_SHORTAGE:
2479                 return "resource shortage";
2480         }
2481         return "unknown reason";
2482 }
2483
2484 /* ARGSUSED */
2485 void
2486 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2487 {
2488         int id, reason;
2489         char *msg = NULL, *lang = NULL;
2490         Channel *c;
2491
2492         id = packet_get_int();
2493         c = channel_lookup(id);
2494
2495         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2496                 packet_disconnect("Received open failure for "
2497                     "non-opening channel %d.", id);
2498         if (compat20) {
2499                 reason = packet_get_int();
2500                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2501                         msg  = packet_get_string(NULL);
2502                         lang = packet_get_string(NULL);
2503                 }
2504                 logit("channel %d: open failed: %s%s%s", id,
2505                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2506                 if (msg != NULL)
2507                         xfree(msg);
2508                 if (lang != NULL)
2509                         xfree(lang);
2510         }
2511         packet_check_eom();
2512         /* Schedule the channel for cleanup/deletion. */
2513         chan_mark_dead(c);
2514 }
2515
2516 /* ARGSUSED */
2517 void
2518 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2519 {
2520         Channel *c;
2521         int id;
2522         u_int adjust;
2523
2524         if (!compat20)
2525                 return;
2526
2527         /* Get the channel number and verify it. */
2528         id = packet_get_int();
2529         c = channel_lookup(id);
2530
2531         if (c == NULL) {
2532                 logit("Received window adjust for non-open channel %d.", id);
2533                 return;
2534         }
2535         adjust = packet_get_int();
2536         packet_check_eom();
2537         debug2("channel %d: rcvd adjust %u", id, adjust);
2538         c->remote_window += adjust;
2539 }
2540
2541 /* ARGSUSED */
2542 void
2543 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2544 {
2545         Channel *c = NULL;
2546         u_short host_port;
2547         char *host, *originator_string;
2548         int remote_id;
2549
2550         remote_id = packet_get_int();
2551         host = packet_get_string(NULL);
2552         host_port = packet_get_int();
2553
2554         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2555                 originator_string = packet_get_string(NULL);
2556         } else {
2557                 originator_string = xstrdup("unknown (remote did not supply name)");
2558         }
2559         packet_check_eom();
2560         c = channel_connect_to(host, host_port,
2561             "connected socket", originator_string);
2562         xfree(originator_string);
2563         xfree(host);
2564         if (c == NULL) {
2565                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2566                 packet_put_int(remote_id);
2567                 packet_send();
2568         } else
2569                 c->remote_id = remote_id;
2570 }
2571
2572 /* ARGSUSED */
2573 void
2574 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2575 {
2576         Channel *c;
2577         struct channel_confirm *cc;
2578         int id;
2579
2580         /* Reset keepalive timeout */
2581         packet_set_alive_timeouts(0);
2582
2583         id = packet_get_int();
2584         packet_check_eom();
2585
2586         debug2("channel_input_status_confirm: type %d id %d", type, id);
2587
2588         if ((c = channel_lookup(id)) == NULL) {
2589                 logit("channel_input_status_confirm: %d: unknown", id);
2590                 return;
2591         }
2592         ;
2593         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2594                 return;
2595         cc->cb(type, c, cc->ctx);
2596         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2597         bzero(cc, sizeof(*cc));
2598         xfree(cc);
2599 }
2600
2601 /* -- tcp forwarding */
2602
2603 void
2604 channel_set_af(int af)
2605 {
2606         IPv4or6 = af;
2607 }
2608
2609 static int
2610 channel_setup_fwd_listener(int type, const char *listen_addr,
2611     u_short listen_port, int *allocated_listen_port,
2612     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2613 {
2614         Channel *c;
2615         int sock, r, success = 0, wildcard = 0, is_client;
2616         struct addrinfo hints, *ai, *aitop;
2617         const char *host, *addr;
2618         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2619         in_port_t *lport_p;
2620
2621         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2622             listen_addr : host_to_connect;
2623         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2624
2625         if (host == NULL) {
2626                 error("No forward host name.");
2627                 return 0;
2628         }
2629         if (strlen(host) >= NI_MAXHOST) {
2630                 error("Forward host name too long.");
2631                 return 0;
2632         }
2633
2634         /*
2635          * Determine whether or not a port forward listens to loopback,
2636          * specified address or wildcard. On the client, a specified bind
2637          * address will always override gateway_ports. On the server, a
2638          * gateway_ports of 1 (``yes'') will override the client's
2639          * specification and force a wildcard bind, whereas a value of 2
2640          * (``clientspecified'') will bind to whatever address the client
2641          * asked for.
2642          *
2643          * Special-case listen_addrs are:
2644          *
2645          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2646          * "" (empty string), "*"  -> wildcard v4/v6
2647          * "localhost"             -> loopback v4/v6
2648          */
2649         addr = NULL;
2650         if (listen_addr == NULL) {
2651                 /* No address specified: default to gateway_ports setting */
2652                 if (gateway_ports)
2653                         wildcard = 1;
2654         } else if (gateway_ports || is_client) {
2655                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2656                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2657                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2658                     (!is_client && gateway_ports == 1))
2659                         wildcard = 1;
2660                 else if (strcmp(listen_addr, "localhost") != 0)
2661                         addr = listen_addr;
2662         }
2663
2664         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2665             type, wildcard, (addr == NULL) ? "NULL" : addr);
2666
2667         /*
2668          * getaddrinfo returns a loopback address if the hostname is
2669          * set to NULL and hints.ai_flags is not AI_PASSIVE
2670          */
2671         memset(&hints, 0, sizeof(hints));
2672         hints.ai_family = IPv4or6;
2673         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2674         hints.ai_socktype = SOCK_STREAM;
2675         snprintf(strport, sizeof strport, "%d", listen_port);
2676         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2677                 if (addr == NULL) {
2678                         /* This really shouldn't happen */
2679                         packet_disconnect("getaddrinfo: fatal error: %s",
2680                             ssh_gai_strerror(r));
2681                 } else {
2682                         error("channel_setup_fwd_listener: "
2683                             "getaddrinfo(%.64s): %s", addr,
2684                             ssh_gai_strerror(r));
2685                 }
2686                 return 0;
2687         }
2688         if (allocated_listen_port != NULL)
2689                 *allocated_listen_port = 0;
2690         for (ai = aitop; ai; ai = ai->ai_next) {
2691                 switch (ai->ai_family) {
2692                 case AF_INET:
2693                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2694                             sin_port;
2695                         break;
2696                 case AF_INET6:
2697                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2698                             sin6_port;
2699                         break;
2700                 default:
2701                         continue;
2702                 }
2703                 /*
2704                  * If allocating a port for -R forwards, then use the
2705                  * same port for all address families.
2706                  */
2707                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2708                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2709                         *lport_p = htons(*allocated_listen_port);
2710
2711                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2712                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2713                         error("channel_setup_fwd_listener: getnameinfo failed");
2714                         continue;
2715                 }
2716                 /* Create a port to listen for the host. */
2717                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2718                 if (sock < 0) {
2719                         /* this is no error since kernel may not support ipv6 */
2720                         verbose("socket: %.100s", strerror(errno));
2721                         continue;
2722                 }
2723
2724                 channel_set_reuseaddr(sock);
2725                 if (ai->ai_family == AF_INET6)
2726                         sock_set_v6only(sock);
2727
2728                 debug("Local forwarding listening on %s port %s.",
2729                     ntop, strport);
2730
2731                 /* Bind the socket to the address. */
2732                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2733                         /* address can be in use ipv6 address is already bound */
2734                         if (!ai->ai_next)
2735                                 error("bind: %.100s", strerror(errno));
2736                         else
2737                                 verbose("bind: %.100s", strerror(errno));
2738
2739                         close(sock);
2740                         continue;
2741                 }
2742                 /* Start listening for connections on the socket. */
2743                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2744                         error("listen: %.100s", strerror(errno));
2745                         close(sock);
2746                         continue;
2747                 }
2748
2749                 /*
2750                  * listen_port == 0 requests a dynamically allocated port -
2751                  * record what we got.
2752                  */
2753                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2754                     allocated_listen_port != NULL &&
2755                     *allocated_listen_port == 0) {
2756                         *allocated_listen_port = get_sock_port(sock, 1);
2757                         debug("Allocated listen port %d",
2758                             *allocated_listen_port);
2759                 }
2760
2761                 /* Allocate a channel number for the socket. */
2762                 c = channel_new("port listener", type, sock, sock, -1,
2763                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2764                     0, "port listener", 1);
2765                 c->path = xstrdup(host);
2766                 c->host_port = port_to_connect;
2767                 c->listening_port = listen_port;
2768                 success = 1;
2769         }
2770         if (success == 0)
2771                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2772                     listen_port);
2773         freeaddrinfo(aitop);
2774         return success;
2775 }
2776
2777 int
2778 channel_cancel_rport_listener(const char *host, u_short port)
2779 {
2780         u_int i;
2781         int found = 0;
2782
2783         for (i = 0; i < channels_alloc; i++) {
2784                 Channel *c = channels[i];
2785
2786                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2787                     strcmp(c->path, host) == 0 && c->listening_port == port) {
2788                         debug2("%s: close channel %d", __func__, i);
2789                         channel_free(c);
2790                         found = 1;
2791                 }
2792         }
2793
2794         return (found);
2795 }
2796
2797 /* protocol local port fwd, used by ssh (and sshd in v1) */
2798 int
2799 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2800     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2801 {
2802         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2803             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2804             gateway_ports);
2805 }
2806
2807 /* protocol v2 remote port fwd, used by sshd */
2808 int
2809 channel_setup_remote_fwd_listener(const char *listen_address,
2810     u_short listen_port, int *allocated_listen_port, int gateway_ports)
2811 {
2812         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2813             listen_address, listen_port, allocated_listen_port,
2814             NULL, 0, gateway_ports);
2815 }
2816
2817 /*
2818  * Initiate forwarding of connections to port "port" on remote host through
2819  * the secure channel to host:port from local side.
2820  */
2821
2822 int
2823 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2824     const char *host_to_connect, u_short port_to_connect)
2825 {
2826         int type, success = 0;
2827
2828         /* Record locally that connection to this host/port is permitted. */
2829         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2830                 fatal("channel_request_remote_forwarding: too many forwards");
2831
2832         /* Send the forward request to the remote side. */
2833         if (compat20) {
2834                 const char *address_to_bind;
2835                 if (listen_host == NULL) {
2836                         if (datafellows & SSH_BUG_RFWD_ADDR)
2837                                 address_to_bind = "127.0.0.1";
2838                         else
2839                                 address_to_bind = "localhost";
2840                 } else if (*listen_host == '\0' ||
2841                            strcmp(listen_host, "*") == 0) {
2842                         if (datafellows & SSH_BUG_RFWD_ADDR)
2843                                 address_to_bind = "0.0.0.0";
2844                         else
2845                                 address_to_bind = "";
2846                 } else
2847                         address_to_bind = listen_host;
2848
2849                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2850                 packet_put_cstring("tcpip-forward");
2851                 packet_put_char(1);                     /* boolean: want reply */
2852                 packet_put_cstring(address_to_bind);
2853                 packet_put_int(listen_port);
2854                 packet_send();
2855                 packet_write_wait();
2856                 /* Assume that server accepts the request */
2857                 success = 1;
2858         } else {
2859                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2860                 packet_put_int(listen_port);
2861                 packet_put_cstring(host_to_connect);
2862                 packet_put_int(port_to_connect);
2863                 packet_send();
2864                 packet_write_wait();
2865
2866                 /* Wait for response from the remote side. */
2867                 type = packet_read();
2868                 switch (type) {
2869                 case SSH_SMSG_SUCCESS:
2870                         success = 1;
2871                         break;
2872                 case SSH_SMSG_FAILURE:
2873                         break;
2874                 default:
2875                         /* Unknown packet */
2876                         packet_disconnect("Protocol error for port forward request:"
2877                             "received packet type %d.", type);
2878                 }
2879         }
2880         if (success) {
2881                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2882                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2883                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2884                 num_permitted_opens++;
2885         }
2886         return (success ? 0 : -1);
2887 }
2888
2889 /*
2890  * Request cancellation of remote forwarding of connection host:port from
2891  * local side.
2892  */
2893 void
2894 channel_request_rforward_cancel(const char *host, u_short port)
2895 {
2896         int i;
2897
2898         if (!compat20)
2899                 return;
2900
2901         for (i = 0; i < num_permitted_opens; i++) {
2902                 if (permitted_opens[i].host_to_connect != NULL &&
2903                     permitted_opens[i].listen_port == port)
2904                         break;
2905         }
2906         if (i >= num_permitted_opens) {
2907                 debug("%s: requested forward not found", __func__);
2908                 return;
2909         }
2910         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2911         packet_put_cstring("cancel-tcpip-forward");
2912         packet_put_char(0);
2913         packet_put_cstring(host == NULL ? "" : host);
2914         packet_put_int(port);
2915         packet_send();
2916
2917         permitted_opens[i].listen_port = 0;
2918         permitted_opens[i].port_to_connect = 0;
2919         xfree(permitted_opens[i].host_to_connect);
2920         permitted_opens[i].host_to_connect = NULL;
2921 }
2922
2923 /*
2924  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2925  * listening for the port, and sends back a success reply (or disconnect
2926  * message if there was an error).
2927  */
2928 int
2929 channel_input_port_forward_request(int is_root, int gateway_ports)
2930 {
2931         u_short port, host_port;
2932         int success = 0;
2933         char *hostname;
2934
2935         /* Get arguments from the packet. */
2936         port = packet_get_int();
2937         hostname = packet_get_string(NULL);
2938         host_port = packet_get_int();
2939
2940 #ifndef HAVE_CYGWIN
2941         /*
2942          * Check that an unprivileged user is not trying to forward a
2943          * privileged port.
2944          */
2945         if (port < IPPORT_RESERVED && !is_root)
2946                 packet_disconnect(
2947                     "Requested forwarding of port %d but user is not root.",
2948                     port);
2949         if (host_port == 0)
2950                 packet_disconnect("Dynamic forwarding denied.");
2951 #endif
2952
2953         /* Initiate forwarding */
2954         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2955             host_port, gateway_ports);
2956
2957         /* Free the argument string. */
2958         xfree(hostname);
2959
2960         return (success ? 0 : -1);
2961 }
2962
2963 /*
2964  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2965  * usually called by the server, because the user could connect to any port
2966  * anyway, and the server has no way to know but to trust the client anyway.
2967  */
2968 void
2969 channel_permit_all_opens(void)
2970 {
2971         if (num_permitted_opens == 0)
2972                 all_opens_permitted = 1;
2973 }
2974
2975 void
2976 channel_add_permitted_opens(char *host, int port)
2977 {
2978         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2979                 fatal("channel_add_permitted_opens: too many forwards");
2980         debug("allow port forwarding to host %s port %d", host, port);
2981
2982         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2983         permitted_opens[num_permitted_opens].port_to_connect = port;
2984         num_permitted_opens++;
2985
2986         all_opens_permitted = 0;
2987 }
2988
2989 int
2990 channel_add_adm_permitted_opens(char *host, int port)
2991 {
2992         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2993                 fatal("channel_add_adm_permitted_opens: too many forwards");
2994         debug("config allows port forwarding to host %s port %d", host, port);
2995
2996         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2997              = xstrdup(host);
2998         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2999         return ++num_adm_permitted_opens;
3000 }
3001
3002 void
3003 channel_clear_permitted_opens(void)
3004 {
3005         int i;
3006
3007         for (i = 0; i < num_permitted_opens; i++)
3008                 if (permitted_opens[i].host_to_connect != NULL)
3009                         xfree(permitted_opens[i].host_to_connect);
3010         num_permitted_opens = 0;
3011 }
3012
3013 void
3014 channel_clear_adm_permitted_opens(void)
3015 {
3016         int i;
3017
3018         for (i = 0; i < num_adm_permitted_opens; i++)
3019                 if (permitted_adm_opens[i].host_to_connect != NULL)
3020                         xfree(permitted_adm_opens[i].host_to_connect);
3021         num_adm_permitted_opens = 0;
3022 }
3023
3024 void
3025 channel_print_adm_permitted_opens(void)
3026 {
3027         int i;
3028
3029         printf("permitopen");
3030         if (num_adm_permitted_opens == 0) {
3031                 printf(" any\n");
3032                 return;
3033         }
3034         for (i = 0; i < num_adm_permitted_opens; i++)
3035                 if (permitted_adm_opens[i].host_to_connect != NULL)
3036                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3037                             permitted_adm_opens[i].port_to_connect);
3038         printf("\n");
3039 }
3040
3041 /* Try to start non-blocking connect to next host in cctx list */
3042 static int
3043 connect_next(struct channel_connect *cctx)
3044 {
3045         int sock, saved_errno;
3046         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
3047
3048         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3049                 if (cctx->ai->ai_family != AF_INET &&
3050                     cctx->ai->ai_family != AF_INET6)
3051                         continue;
3052                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3053                     ntop, sizeof(ntop), strport, sizeof(strport),
3054                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3055                         error("connect_next: getnameinfo failed");
3056                         continue;
3057                 }
3058                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3059                     cctx->ai->ai_protocol)) == -1) {
3060                         if (cctx->ai->ai_next == NULL)
3061                                 error("socket: %.100s", strerror(errno));
3062                         else
3063                                 verbose("socket: %.100s", strerror(errno));
3064                         continue;
3065                 }
3066                 if (set_nonblock(sock) == -1)
3067                         fatal("%s: set_nonblock(%d)", __func__, sock);
3068                 if (connect(sock, cctx->ai->ai_addr,
3069                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3070                         debug("connect_next: host %.100s ([%.100s]:%s): "
3071                             "%.100s", cctx->host, ntop, strport,
3072                             strerror(errno));
3073                         saved_errno = errno;
3074                         close(sock);
3075                         errno = saved_errno;
3076                         continue;       /* fail -- try next */
3077                 }
3078                 debug("connect_next: host %.100s ([%.100s]:%s) "
3079                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3080                 cctx->ai = cctx->ai->ai_next;
3081                 set_nodelay(sock);
3082                 return sock;
3083         }
3084         return -1;
3085 }
3086
3087 static void
3088 channel_connect_ctx_free(struct channel_connect *cctx)
3089 {
3090         xfree(cctx->host);
3091         if (cctx->aitop)
3092                 freeaddrinfo(cctx->aitop);
3093         bzero(cctx, sizeof(*cctx));
3094         cctx->host = NULL;
3095         cctx->ai = cctx->aitop = NULL;
3096 }
3097
3098 /* Return CONNECTING channel to remote host, port */
3099 static Channel *
3100 connect_to(const char *host, u_short port, char *ctype, char *rname)
3101 {
3102         struct addrinfo hints;
3103         int gaierr;
3104         int sock = -1;
3105         char strport[NI_MAXSERV];
3106         struct channel_connect cctx;
3107         Channel *c;
3108
3109         memset(&cctx, 0, sizeof(cctx));
3110         memset(&hints, 0, sizeof(hints));
3111         hints.ai_family = IPv4or6;
3112         hints.ai_socktype = SOCK_STREAM;
3113         snprintf(strport, sizeof strport, "%d", port);
3114         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
3115                 error("connect_to %.100s: unknown host (%s)", host,
3116                     ssh_gai_strerror(gaierr));
3117                 return NULL;
3118         }
3119
3120         cctx.host = xstrdup(host);
3121         cctx.port = port;
3122         cctx.ai = cctx.aitop;
3123
3124         if ((sock = connect_next(&cctx)) == -1) {
3125                 error("connect to %.100s port %d failed: %s",
3126                     host, port, strerror(errno));
3127                 channel_connect_ctx_free(&cctx);
3128                 return NULL;
3129         }
3130         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3131             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3132         c->connect_ctx = cctx;
3133         return c;
3134 }
3135
3136 Channel *
3137 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
3138 {
3139         int i;
3140
3141         for (i = 0; i < num_permitted_opens; i++) {
3142                 if (permitted_opens[i].host_to_connect != NULL &&
3143                     permitted_opens[i].listen_port == listen_port) {
3144                         return connect_to(
3145                             permitted_opens[i].host_to_connect,
3146                             permitted_opens[i].port_to_connect, ctype, rname);
3147                 }
3148         }
3149         error("WARNING: Server requests forwarding for unknown listen_port %d",
3150             listen_port);
3151         return NULL;
3152 }
3153
3154 /* Check if connecting to that port is permitted and connect. */
3155 Channel *
3156 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3157 {
3158         int i, permit, permit_adm = 1;
3159
3160         permit = all_opens_permitted;
3161         if (!permit) {
3162                 for (i = 0; i < num_permitted_opens; i++)
3163                         if (permitted_opens[i].host_to_connect != NULL &&
3164                             permitted_opens[i].port_to_connect == port &&
3165                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3166                                 permit = 1;
3167         }
3168
3169         if (num_adm_permitted_opens > 0) {
3170                 permit_adm = 0;
3171                 for (i = 0; i < num_adm_permitted_opens; i++)
3172                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3173                             permitted_adm_opens[i].port_to_connect == port &&
3174                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3175                             == 0)
3176                                 permit_adm = 1;
3177         }
3178
3179         if (!permit || !permit_adm) {
3180                 logit("Received request to connect to host %.100s port %d, "
3181                     "but the request was denied.", host, port);
3182                 return NULL;
3183         }
3184         return connect_to(host, port, ctype, rname);
3185 }
3186
3187 void
3188 channel_send_window_changes(void)
3189 {
3190         u_int i;
3191         struct winsize ws;
3192
3193         for (i = 0; i < channels_alloc; i++) {
3194                 if (channels[i] == NULL || !channels[i]->client_tty ||
3195                     channels[i]->type != SSH_CHANNEL_OPEN)
3196                         continue;
3197                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3198                         continue;
3199                 channel_request_start(i, "window-change", 0);
3200                 packet_put_int((u_int)ws.ws_col);
3201                 packet_put_int((u_int)ws.ws_row);
3202                 packet_put_int((u_int)ws.ws_xpixel);
3203                 packet_put_int((u_int)ws.ws_ypixel);
3204                 packet_send();
3205         }
3206 }
3207
3208 /* -- X11 forwarding */
3209
3210 /*
3211  * Creates an internet domain socket for listening for X11 connections.
3212  * Returns 0 and a suitable display number for the DISPLAY variable
3213  * stored in display_numberp , or -1 if an error occurs.
3214  */
3215 int
3216 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3217     int single_connection, u_int *display_numberp, int **chanids)
3218 {
3219         Channel *nc = NULL;
3220         int display_number, sock;
3221         u_short port;
3222         struct addrinfo hints, *ai, *aitop;
3223         char strport[NI_MAXSERV];
3224         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3225
3226         if (chanids == NULL)
3227                 return -1;
3228
3229         for (display_number = x11_display_offset;
3230             display_number < MAX_DISPLAYS;
3231             display_number++) {
3232                 port = 6000 + display_number;
3233                 memset(&hints, 0, sizeof(hints));
3234                 hints.ai_family = IPv4or6;
3235                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3236                 hints.ai_socktype = SOCK_STREAM;
3237                 snprintf(strport, sizeof strport, "%d", port);
3238                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3239                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3240                         return -1;
3241                 }
3242                 for (ai = aitop; ai; ai = ai->ai_next) {
3243                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3244                                 continue;
3245                         sock = socket(ai->ai_family, ai->ai_socktype,
3246                             ai->ai_protocol);
3247                         if (sock < 0) {
3248                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3249                                         error("socket: %.100s", strerror(errno));
3250                                         freeaddrinfo(aitop);
3251                                         return -1;
3252                                 } else {
3253                                         debug("x11_create_display_inet: Socket family %d not supported",
3254                                                  ai->ai_family);
3255                                         continue;
3256                                 }
3257                         }
3258                         if (ai->ai_family == AF_INET6)
3259                                 sock_set_v6only(sock);
3260                         if (x11_use_localhost)
3261                                 channel_set_reuseaddr(sock);
3262                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3263                                 debug2("bind port %d: %.100s", port, strerror(errno));
3264                                 close(sock);
3265
3266                                 for (n = 0; n < num_socks; n++) {
3267                                         close(socks[n]);
3268                                 }
3269                                 num_socks = 0;
3270                                 break;
3271                         }
3272                         socks[num_socks++] = sock;
3273                         if (num_socks == NUM_SOCKS)
3274                                 break;
3275                 }
3276                 freeaddrinfo(aitop);
3277                 if (num_socks > 0)
3278                         break;
3279         }
3280         if (display_number >= MAX_DISPLAYS) {
3281                 error("Failed to allocate internet-domain X11 display socket.");
3282                 return -1;
3283         }
3284         /* Start listening for connections on the socket. */
3285         for (n = 0; n < num_socks; n++) {
3286                 sock = socks[n];
3287                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3288                         error("listen: %.100s", strerror(errno));
3289                         close(sock);
3290                         return -1;
3291                 }
3292         }
3293
3294         /* Allocate a channel for each socket. */
3295         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3296         for (n = 0; n < num_socks; n++) {
3297                 sock = socks[n];
3298                 nc = channel_new("x11 listener",
3299                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3300                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3301                     0, "X11 inet listener", 1);
3302                 nc->single_connection = single_connection;
3303                 (*chanids)[n] = nc->self;
3304         }
3305         (*chanids)[n] = -1;
3306
3307         /* Return the display number for the DISPLAY environment variable. */
3308         *display_numberp = display_number;
3309         return (0);
3310 }
3311
3312 static int
3313 connect_local_xsocket_path(const char *pathname)
3314 {
3315         int sock;
3316         struct sockaddr_un addr;
3317
3318         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3319         if (sock < 0)
3320                 error("socket: %.100s", strerror(errno));
3321         memset(&addr, 0, sizeof(addr));
3322         addr.sun_family = AF_UNIX;
3323         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3324         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3325                 return sock;
3326         close(sock);
3327         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3328         return -1;
3329 }
3330
3331 static int
3332 connect_local_xsocket(u_int dnr)
3333 {
3334         char buf[1024];
3335         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3336         return connect_local_xsocket_path(buf);
3337 }
3338
3339 int
3340 x11_connect_display(void)
3341 {
3342         u_int display_number;
3343         const char *display;
3344         char buf[1024], *cp;
3345         struct addrinfo hints, *ai, *aitop;
3346         char strport[NI_MAXSERV];
3347         int gaierr, sock = 0;
3348
3349         /* Try to open a socket for the local X server. */
3350         display = getenv("DISPLAY");
3351         if (!display) {
3352                 error("DISPLAY not set.");
3353                 return -1;
3354         }
3355         /*
3356          * Now we decode the value of the DISPLAY variable and make a
3357          * connection to the real X server.
3358          */
3359
3360         /* Check if the display is from launchd. */
3361 #ifdef __APPLE__
3362         if (strncmp(display, "/tmp/launch", 11) == 0) {
3363                 sock = connect_local_xsocket_path(display);
3364                 if (sock < 0)
3365                         return -1;
3366
3367                 /* OK, we now have a connection to the display. */
3368                 return sock;
3369         }
3370 #endif
3371         /*
3372          * Check if it is a unix domain socket.  Unix domain displays are in
3373          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3374          */
3375         if (strncmp(display, "unix:", 5) == 0 ||
3376             display[0] == ':') {
3377                 /* Connect to the unix domain socket. */
3378                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3379                         error("Could not parse display number from DISPLAY: %.100s",
3380                             display);
3381                         return -1;
3382                 }
3383                 /* Create a socket. */
3384                 sock = connect_local_xsocket(display_number);
3385                 if (sock < 0)
3386                         return -1;
3387
3388                 /* OK, we now have a connection to the display. */
3389                 return sock;
3390         }
3391         /*
3392          * Connect to an inet socket.  The DISPLAY value is supposedly
3393          * hostname:d[.s], where hostname may also be numeric IP address.
3394          */
3395         strlcpy(buf, display, sizeof(buf));
3396         cp = strchr(buf, ':');
3397         if (!cp) {
3398                 error("Could not find ':' in DISPLAY: %.100s", display);
3399                 return -1;
3400         }
3401         *cp = 0;
3402         /* buf now contains the host name.  But first we parse the display number. */
3403         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3404                 error("Could not parse display number from DISPLAY: %.100s",
3405                     display);
3406                 return -1;
3407         }
3408
3409         /* Look up the host address */
3410         memset(&hints, 0, sizeof(hints));
3411         hints.ai_family = IPv4or6;
3412         hints.ai_socktype = SOCK_STREAM;
3413         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3414         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3415                 error("%.100s: unknown host. (%s)", buf,
3416                 ssh_gai_strerror(gaierr));
3417                 return -1;
3418         }
3419         for (ai = aitop; ai; ai = ai->ai_next) {
3420                 /* Create a socket. */
3421                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3422                 if (sock < 0) {
3423                         debug2("socket: %.100s", strerror(errno));
3424                         continue;
3425                 }
3426                 /* Connect it to the display. */
3427                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3428                         debug2("connect %.100s port %u: %.100s", buf,
3429                             6000 + display_number, strerror(errno));
3430                         close(sock);
3431                         continue;
3432                 }
3433                 /* Success */
3434                 break;
3435         }
3436         freeaddrinfo(aitop);
3437         if (!ai) {
3438                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3439                     strerror(errno));
3440                 return -1;
3441         }
3442         set_nodelay(sock);
3443         return sock;
3444 }
3445
3446 /*
3447  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3448  * the remote channel number.  We should do whatever we want, and respond
3449  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3450  */
3451
3452 /* ARGSUSED */
3453 void
3454 x11_input_open(int type, u_int32_t seq, void *ctxt)
3455 {
3456         Channel *c = NULL;
3457         int remote_id, sock = 0;
3458         char *remote_host;
3459
3460         debug("Received X11 open request.");
3461
3462         remote_id = packet_get_int();
3463
3464         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3465                 remote_host = packet_get_string(NULL);
3466         } else {
3467                 remote_host = xstrdup("unknown (remote did not supply name)");
3468         }
3469         packet_check_eom();
3470
3471         /* Obtain a connection to the real X display. */
3472         sock = x11_connect_display();
3473         if (sock != -1) {
3474                 /* Allocate a channel for this connection. */
3475                 c = channel_new("connected x11 socket",
3476                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3477                     remote_host, 1);
3478                 c->remote_id = remote_id;
3479                 c->force_drain = 1;
3480         }
3481         xfree(remote_host);
3482         if (c == NULL) {
3483                 /* Send refusal to the remote host. */
3484                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3485                 packet_put_int(remote_id);
3486         } else {
3487                 /* Send a confirmation to the remote host. */
3488                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3489                 packet_put_int(remote_id);
3490                 packet_put_int(c->self);
3491         }
3492         packet_send();
3493 }
3494
3495 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3496 /* ARGSUSED */
3497 void
3498 deny_input_open(int type, u_int32_t seq, void *ctxt)
3499 {
3500         int rchan = packet_get_int();
3501
3502         switch (type) {
3503         case SSH_SMSG_AGENT_OPEN:
3504                 error("Warning: ssh server tried agent forwarding.");
3505                 break;
3506         case SSH_SMSG_X11_OPEN:
3507                 error("Warning: ssh server tried X11 forwarding.");
3508                 break;
3509         default:
3510                 error("deny_input_open: type %d", type);
3511                 break;
3512         }
3513         error("Warning: this is probably a break-in attempt by a malicious server.");
3514         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3515         packet_put_int(rchan);
3516         packet_send();
3517 }
3518
3519 /*
3520  * Requests forwarding of X11 connections, generates fake authentication
3521  * data, and enables authentication spoofing.
3522  * This should be called in the client only.
3523  */
3524 void
3525 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3526     const char *proto, const char *data)
3527 {
3528         u_int data_len = (u_int) strlen(data) / 2;
3529         u_int i, value;
3530         char *new_data;
3531         int screen_number;
3532         const char *cp;
3533         u_int32_t rnd = 0;
3534
3535         if (x11_saved_display == NULL)
3536                 x11_saved_display = xstrdup(disp);
3537         else if (strcmp(disp, x11_saved_display) != 0) {
3538                 error("x11_request_forwarding_with_spoofing: different "
3539                     "$DISPLAY already forwarded");
3540                 return;
3541         }
3542
3543         cp = strchr(disp, ':');
3544         if (cp)
3545                 cp = strchr(cp, '.');
3546         if (cp)
3547                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3548         else
3549                 screen_number = 0;
3550
3551         if (x11_saved_proto == NULL) {
3552                 /* Save protocol name. */
3553                 x11_saved_proto = xstrdup(proto);
3554                 /*
3555                  * Extract real authentication data and generate fake data
3556                  * of the same length.
3557                  */
3558                 x11_saved_data = xmalloc(data_len);
3559                 x11_fake_data = xmalloc(data_len);
3560                 for (i = 0; i < data_len; i++) {
3561                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3562                                 fatal("x11_request_forwarding: bad "
3563                                     "authentication data: %.100s", data);
3564                         if (i % 4 == 0)
3565                                 rnd = arc4random();
3566                         x11_saved_data[i] = value;
3567                         x11_fake_data[i] = rnd & 0xff;
3568                         rnd >>= 8;
3569                 }
3570                 x11_saved_data_len = data_len;
3571                 x11_fake_data_len = data_len;
3572         }
3573
3574         /* Convert the fake data into hex. */
3575         new_data = tohex(x11_fake_data, data_len);
3576
3577         /* Send the request packet. */
3578         if (compat20) {
3579                 channel_request_start(client_session_id, "x11-req", 0);
3580                 packet_put_char(0);     /* XXX bool single connection */
3581         } else {
3582                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3583         }
3584         packet_put_cstring(proto);
3585         packet_put_cstring(new_data);
3586         packet_put_int(screen_number);
3587         packet_send();
3588         packet_write_wait();
3589         xfree(new_data);
3590 }
3591
3592
3593 /* -- agent forwarding */
3594
3595 /* Sends a message to the server to request authentication fd forwarding. */
3596
3597 void
3598 auth_request_forwarding(void)
3599 {
3600         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3601         packet_send();
3602         packet_write_wait();
3603 }