crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.295 2009/02/12 03:00:56 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <netdb.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <termios.h>
  61 #include <unistd.h>
  62 #include <stdarg.h>
  63
  64 #include "openbsd-compat/sys-queue.h"
  65 #include "xmalloc.h"
  66 #include "ssh.h"
  67 #include "ssh1.h"
  68 #include "ssh2.h"
  69 #include "packet.h"
  70 #include "log.h"
  71 #include "misc.h"
  72 #include "buffer.h"
  73 #include "channels.h"
  74 #include "compat.h"
  75 #include "canohost.h"
  76 #include "key.h"
  77 #include "authfd.h"
  78 #include "pathnames.h"
  79
  80 /* -- channel core */
  81
  82 /*
  83  * Pointer to an array containing all allocated channels.  The array is
  84  * dynamically extended as needed.
  85  */
  86 static Channel **channels = NULL;
  87
  88 /*
  89  * Size of the channel array.  All slots of the array must always be
  90  * initialized (at least the type field); unused slots set to NULL
  91  */
  92 static u_int channels_alloc = 0;
  93
  94 /*
  95  * Maximum file descriptor value used in any of the channels.  This is
  96  * updated in channel_new.
  97  */
  98 static int channel_max_fd = 0;
  99
 100
 101 /* -- tcp forwarding */
 102
 103 /*
 104  * Data structure for storing which hosts are permitted for forward requests.
 105  * The local sides of any remote forwards are stored in this array to prevent
 106  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 107  * network (which might be behind a firewall).
 108  */
 109 typedef struct {
 110         char *host_to_connect;          /* Connect to 'host'. */
 111         u_short port_to_connect;        /* Connect to 'port'. */
 112         u_short listen_port;            /* Remote side should listen port number. */
 113 } ForwardPermission;
 114
 115 /* List of all permitted host/port pairs to connect by the user. */
 116 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 117
 118 /* List of all permitted host/port pairs to connect by the admin. */
 119 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 120
 121 /* Number of permitted host/port pairs in the array permitted by the user. */
 122 static int num_permitted_opens = 0;
 123
 124 /* Number of permitted host/port pair in the array permitted by the admin. */
 125 static int num_adm_permitted_opens = 0;
 126
 127 /*
 128  * If this is true, all opens are permitted.  This is the case on the server
 129  * on which we have to trust the client anyway, and the user could do
 130  * anything after logging in anyway.
 131  */
 132 static int all_opens_permitted = 0;
 133
 134
 135 /* -- X11 forwarding */
 136
 137 /* Maximum number of fake X11 displays to try. */
 138 #define MAX_DISPLAYS  1000
 139
 140 /* Saved X11 local (client) display. */
 141 static char *x11_saved_display = NULL;
 142
 143 /* Saved X11 authentication protocol name. */
 144 static char *x11_saved_proto = NULL;
 145
 146 /* Saved X11 authentication data.  This is the real data. */
 147 static char *x11_saved_data = NULL;
 148 static u_int x11_saved_data_len = 0;
 149
 150 /*
 151  * Fake X11 authentication data.  This is what the server will be sending us;
 152  * we should replace any occurrences of this by the real data.
 153  */
 154 static u_char *x11_fake_data = NULL;
 155 static u_int x11_fake_data_len;
 156
 157
 158 /* -- agent forwarding */
 159
 160 #define NUM_SOCKS       10
 161
 162 /* AF_UNSPEC or AF_INET or AF_INET6 */
 163 static int IPv4or6 = AF_UNSPEC;
 164
 165 /* helper */
 166 static void port_open_helper(Channel *c, char *rtype);
 167
 168 /* non-blocking connect helpers */
 169 static int connect_next(struct channel_connect *);
 170 static void channel_connect_ctx_free(struct channel_connect *);
 171
 172 /* -- channel core */
 173
 174 Channel *
 175 channel_by_id(int id)
 176 {
 177         Channel *c;
 178
 179         if (id < 0 || (u_int)id >= channels_alloc) {
 180                 logit("channel_by_id: %d: bad id", id);
 181                 return NULL;
 182         }
 183         c = channels[id];
 184         if (c == NULL) {
 185                 logit("channel_by_id: %d: bad id: channel free", id);
 186                 return NULL;
 187         }
 188         return c;
 189 }
 190
 191 /*
 192  * Returns the channel if it is allowed to receive protocol messages.
 193  * Private channels, like listening sockets, may not receive messages.
 194  */
 195 Channel *
 196 channel_lookup(int id)
 197 {
 198         Channel *c;
 199
 200         if ((c = channel_by_id(id)) == NULL)
 201                 return (NULL);
 202
 203         switch (c->type) {
 204         case SSH_CHANNEL_X11_OPEN:
 205         case SSH_CHANNEL_LARVAL:
 206         case SSH_CHANNEL_CONNECTING:
 207         case SSH_CHANNEL_DYNAMIC:
 208         case SSH_CHANNEL_OPENING:
 209         case SSH_CHANNEL_OPEN:
 210         case SSH_CHANNEL_INPUT_DRAINING:
 211         case SSH_CHANNEL_OUTPUT_DRAINING:
 212                 return (c);
 213         }
 214         logit("Non-public channel %d, type %d.", id, c->type);
 215         return (NULL);
 216 }
 217
 218 /*
 219  * Register filedescriptors for a channel, used when allocating a channel or
 220  * when the channel consumer/producer is ready, e.g. shell exec'd
 221  */
 222 static void
 223 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 224     int extusage, int nonblock, int is_tty)
 225 {
 226         /* Update the maximum file descriptor value. */
 227         channel_max_fd = MAX(channel_max_fd, rfd);
 228         channel_max_fd = MAX(channel_max_fd, wfd);
 229         channel_max_fd = MAX(channel_max_fd, efd);
 230
 231         /* XXX set close-on-exec -markus */
 232
 233         c->rfd = rfd;
 234         c->wfd = wfd;
 235         c->sock = (rfd == wfd) ? rfd : -1;
 236         c->ctl_fd = -1; /* XXX: set elsewhere */
 237         c->efd = efd;
 238         c->extended_usage = extusage;
 239
 240         if ((c->isatty = is_tty) != 0)
 241                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 242         c->wfd_isatty = is_tty || isatty(c->wfd);
 243
 244         /* enable nonblocking mode */
 245         if (nonblock) {
 246                 if (rfd != -1)
 247                         set_nonblock(rfd);
 248                 if (wfd != -1)
 249                         set_nonblock(wfd);
 250                 if (efd != -1)
 251                         set_nonblock(efd);
 252         }
 253 }
 254
 255 /*
 256  * Allocate a new channel object and set its type and socket. This will cause
 257  * remote_name to be freed.
 258  */
 259 Channel *
 260 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 261     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 262 {
 263         int found;
 264         u_int i;
 265         Channel *c;
 266
 267         /* Do initial allocation if this is the first call. */
 268         if (channels_alloc == 0) {
 269                 channels_alloc = 10;
 270                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 271                 for (i = 0; i < channels_alloc; i++)
 272                         channels[i] = NULL;
 273         }
 274         /* Try to find a free slot where to put the new channel. */
 275         for (found = -1, i = 0; i < channels_alloc; i++)
 276                 if (channels[i] == NULL) {
 277                         /* Found a free slot. */
 278                         found = (int)i;
 279                         break;
 280                 }
 281         if (found < 0) {
 282                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 283                 found = channels_alloc;
 284                 if (channels_alloc > 10000)
 285                         fatal("channel_new: internal error: channels_alloc %d "
 286                             "too big.", channels_alloc);
 287                 channels = xrealloc(channels, channels_alloc + 10,
 288                     sizeof(Channel *));
 289                 channels_alloc += 10;
 290                 debug2("channel: expanding %d", channels_alloc);
 291                 for (i = found; i < channels_alloc; i++)
 292                         channels[i] = NULL;
 293         }
 294         /* Initialize and return new channel. */
 295         c = channels[found] = xcalloc(1, sizeof(Channel));
 296         buffer_init(&c->input);
 297         buffer_init(&c->output);
 298         buffer_init(&c->extended);
 299         c->path = NULL;
 300         c->ostate = CHAN_OUTPUT_OPEN;
 301         c->istate = CHAN_INPUT_OPEN;
 302         c->flags = 0;
 303         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 304         c->self = found;
 305         c->type = type;
 306         c->ctype = ctype;
 307         c->local_window = window;
 308         c->local_window_max = window;
 309         c->local_consumed = 0;
 310         c->local_maxpacket = maxpack;
 311         c->remote_id = -1;
 312         c->remote_name = xstrdup(remote_name);
 313         c->remote_window = 0;
 314         c->remote_maxpacket = 0;
 315         c->force_drain = 0;
 316         c->single_connection = 0;
 317         c->detach_user = NULL;
 318         c->detach_close = 0;
 319         c->open_confirm = NULL;
 320         c->open_confirm_ctx = NULL;
 321         c->input_filter = NULL;
 322         c->output_filter = NULL;
 323         c->filter_ctx = NULL;
 324         c->filter_cleanup = NULL;
 325         TAILQ_INIT(&c->status_confirms);
 326         debug("channel %d: new [%s]", found, remote_name);
 327         return c;
 328 }
 329
 330 static int
 331 channel_find_maxfd(void)
 332 {
 333         u_int i;
 334         int max = 0;
 335         Channel *c;
 336
 337         for (i = 0; i < channels_alloc; i++) {
 338                 c = channels[i];
 339                 if (c != NULL) {
 340                         max = MAX(max, c->rfd);
 341                         max = MAX(max, c->wfd);
 342                         max = MAX(max, c->efd);
 343                 }
 344         }
 345         return max;
 346 }
 347
 348 int
 349 channel_close_fd(int *fdp)
 350 {
 351         int ret = 0, fd = *fdp;
 352
 353         if (fd != -1) {
 354                 ret = close(fd);
 355                 *fdp = -1;
 356                 if (fd == channel_max_fd)
 357                         channel_max_fd = channel_find_maxfd();
 358         }
 359         return ret;
 360 }
 361
 362 /* Close all channel fd/socket. */
 363 static void
 364 channel_close_fds(Channel *c)
 365 {
 366         debug3("channel %d: close_fds r %d w %d e %d c %d",
 367             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 368
 369         channel_close_fd(&c->sock);
 370         channel_close_fd(&c->ctl_fd);
 371         channel_close_fd(&c->rfd);
 372         channel_close_fd(&c->wfd);
 373         channel_close_fd(&c->efd);
 374 }
 375
 376 /* Free the channel and close its fd/socket. */
 377 void
 378 channel_free(Channel *c)
 379 {
 380         char *s;
 381         u_int i, n;
 382         struct channel_confirm *cc;
 383
 384         for (n = 0, i = 0; i < channels_alloc; i++)
 385                 if (channels[i])
 386                         n++;
 387         debug("channel %d: free: %s, nchannels %u", c->self,
 388             c->remote_name ? c->remote_name : "???", n);
 389
 390         s = channel_open_message();
 391         debug3("channel %d: status: %s", c->self, s);
 392         xfree(s);
 393
 394         if (c->sock != -1)
 395                 shutdown(c->sock, SHUT_RDWR);
 396         if (c->ctl_fd != -1)
 397                 shutdown(c->ctl_fd, SHUT_RDWR);
 398         channel_close_fds(c);
 399         buffer_free(&c->input);
 400         buffer_free(&c->output);
 401         buffer_free(&c->extended);
 402         if (c->remote_name) {
 403                 xfree(c->remote_name);
 404                 c->remote_name = NULL;
 405         }
 406         if (c->path) {
 407                 xfree(c->path);
 408                 c->path = NULL;
 409         }
 410         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 411                 if (cc->abandon_cb != NULL)
 412                         cc->abandon_cb(c, cc->ctx);
 413                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 414                 bzero(cc, sizeof(*cc));
 415                 xfree(cc);
 416         }
 417         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 418                 c->filter_cleanup(c->self, c->filter_ctx);
 419         channels[c->self] = NULL;
 420         xfree(c);
 421 }
 422
 423 void
 424 channel_free_all(void)
 425 {
 426         u_int i;
 427
 428         for (i = 0; i < channels_alloc; i++)
 429                 if (channels[i] != NULL)
 430                         channel_free(channels[i]);
 431 }
 432
 433 /*
 434  * Closes the sockets/fds of all channels.  This is used to close extra file
 435  * descriptors after a fork.
 436  */
 437 void
 438 channel_close_all(void)
 439 {
 440         u_int i;
 441
 442         for (i = 0; i < channels_alloc; i++)
 443                 if (channels[i] != NULL)
 444                         channel_close_fds(channels[i]);
 445 }
 446
 447 /*
 448  * Stop listening to channels.
 449  */
 450 void
 451 channel_stop_listening(void)
 452 {
 453         u_int i;
 454         Channel *c;
 455
 456         for (i = 0; i < channels_alloc; i++) {
 457                 c = channels[i];
 458                 if (c != NULL) {
 459                         switch (c->type) {
 460                         case SSH_CHANNEL_AUTH_SOCKET:
 461                         case SSH_CHANNEL_PORT_LISTENER:
 462                         case SSH_CHANNEL_RPORT_LISTENER:
 463                         case SSH_CHANNEL_X11_LISTENER:
 464                                 channel_close_fd(&c->sock);
 465                                 channel_free(c);
 466                                 break;
 467                         }
 468                 }
 469         }
 470 }
 471
 472 /*
 473  * Returns true if no channel has too much buffered data, and false if one or
 474  * more channel is overfull.
 475  */
 476 int
 477 channel_not_very_much_buffered_data(void)
 478 {
 479         u_int i;
 480         Channel *c;
 481
 482         for (i = 0; i < channels_alloc; i++) {
 483                 c = channels[i];
 484                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 485 #if 0
 486                         if (!compat20 &&
 487                             buffer_len(&c->input) > packet_get_maxsize()) {
 488                                 debug2("channel %d: big input buffer %d",
 489                                     c->self, buffer_len(&c->input));
 490                                 return 0;
 491                         }
 492 #endif
 493                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 494                                 debug2("channel %d: big output buffer %u > %u",
 495                                     c->self, buffer_len(&c->output),
 496                                     packet_get_maxsize());
 497                                 return 0;
 498                         }
 499                 }
 500         }
 501         return 1;
 502 }
 503
 504 /* Returns true if any channel is still open. */
 505 int
 506 channel_still_open(void)
 507 {
 508         u_int i;
 509         Channel *c;
 510
 511         for (i = 0; i < channels_alloc; i++) {
 512                 c = channels[i];
 513                 if (c == NULL)
 514                         continue;
 515                 switch (c->type) {
 516                 case SSH_CHANNEL_X11_LISTENER:
 517                 case SSH_CHANNEL_PORT_LISTENER:
 518                 case SSH_CHANNEL_RPORT_LISTENER:
 519                 case SSH_CHANNEL_CLOSED:
 520                 case SSH_CHANNEL_AUTH_SOCKET:
 521                 case SSH_CHANNEL_DYNAMIC:
 522                 case SSH_CHANNEL_CONNECTING:
 523                 case SSH_CHANNEL_ZOMBIE:
 524                         continue;
 525                 case SSH_CHANNEL_LARVAL:
 526                         if (!compat20)
 527                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 528                         continue;
 529                 case SSH_CHANNEL_OPENING:
 530                 case SSH_CHANNEL_OPEN:
 531                 case SSH_CHANNEL_X11_OPEN:
 532                         return 1;
 533                 case SSH_CHANNEL_INPUT_DRAINING:
 534                 case SSH_CHANNEL_OUTPUT_DRAINING:
 535                         if (!compat13)
 536                                 fatal("cannot happen: OUT_DRAIN");
 537                         return 1;
 538                 default:
 539                         fatal("channel_still_open: bad channel type %d", c->type);
 540                         /* NOTREACHED */
 541                 }
 542         }
 543         return 0;
 544 }
 545
 546 /* Returns the id of an open channel suitable for keepaliving */
 547 int
 548 channel_find_open(void)
 549 {
 550         u_int i;
 551         Channel *c;
 552
 553         for (i = 0; i < channels_alloc; i++) {
 554                 c = channels[i];
 555                 if (c == NULL || c->remote_id < 0)
 556                         continue;
 557                 switch (c->type) {
 558                 case SSH_CHANNEL_CLOSED:
 559                 case SSH_CHANNEL_DYNAMIC:
 560                 case SSH_CHANNEL_X11_LISTENER:
 561                 case SSH_CHANNEL_PORT_LISTENER:
 562                 case SSH_CHANNEL_RPORT_LISTENER:
 563                 case SSH_CHANNEL_OPENING:
 564                 case SSH_CHANNEL_CONNECTING:
 565                 case SSH_CHANNEL_ZOMBIE:
 566                         continue;
 567                 case SSH_CHANNEL_LARVAL:
 568                 case SSH_CHANNEL_AUTH_SOCKET:
 569                 case SSH_CHANNEL_OPEN:
 570                 case SSH_CHANNEL_X11_OPEN:
 571                         return i;
 572                 case SSH_CHANNEL_INPUT_DRAINING:
 573                 case SSH_CHANNEL_OUTPUT_DRAINING:
 574                         if (!compat13)
 575                                 fatal("cannot happen: OUT_DRAIN");
 576                         return i;
 577                 default:
 578                         fatal("channel_find_open: bad channel type %d", c->type);
 579                         /* NOTREACHED */
 580                 }
 581         }
 582         return -1;
 583 }
 584
 585
 586 /*
 587  * Returns a message describing the currently open forwarded connections,
 588  * suitable for sending to the client.  The message contains crlf pairs for
 589  * newlines.
 590  */
 591 char *
 592 channel_open_message(void)
 593 {
 594         Buffer buffer;
 595         Channel *c;
 596         char buf[1024], *cp;
 597         u_int i;
 598
 599         buffer_init(&buffer);
 600         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 601         buffer_append(&buffer, buf, strlen(buf));
 602         for (i = 0; i < channels_alloc; i++) {
 603                 c = channels[i];
 604                 if (c == NULL)
 605                         continue;
 606                 switch (c->type) {
 607                 case SSH_CHANNEL_X11_LISTENER:
 608                 case SSH_CHANNEL_PORT_LISTENER:
 609                 case SSH_CHANNEL_RPORT_LISTENER:
 610                 case SSH_CHANNEL_CLOSED:
 611                 case SSH_CHANNEL_AUTH_SOCKET:
 612                 case SSH_CHANNEL_ZOMBIE:
 613                         continue;
 614                 case SSH_CHANNEL_LARVAL:
 615                 case SSH_CHANNEL_OPENING:
 616                 case SSH_CHANNEL_CONNECTING:
 617                 case SSH_CHANNEL_DYNAMIC:
 618                 case SSH_CHANNEL_OPEN:
 619                 case SSH_CHANNEL_X11_OPEN:
 620                 case SSH_CHANNEL_INPUT_DRAINING:
 621                 case SSH_CHANNEL_OUTPUT_DRAINING:
 622                         snprintf(buf, sizeof buf,
 623                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 624                             c->self, c->remote_name,
 625                             c->type, c->remote_id,
 626                             c->istate, buffer_len(&c->input),
 627                             c->ostate, buffer_len(&c->output),
 628                             c->rfd, c->wfd, c->ctl_fd);
 629                         buffer_append(&buffer, buf, strlen(buf));
 630                         continue;
 631                 default:
 632                         fatal("channel_open_message: bad channel type %d", c->type);
 633                         /* NOTREACHED */
 634                 }
 635         }
 636         buffer_append(&buffer, "\0", 1);
 637         cp = xstrdup(buffer_ptr(&buffer));
 638         buffer_free(&buffer);
 639         return cp;
 640 }
 641
 642 void
 643 channel_send_open(int id)
 644 {
 645         Channel *c = channel_lookup(id);
 646
 647         if (c == NULL) {
 648                 logit("channel_send_open: %d: bad id", id);
 649                 return;
 650         }
 651         debug2("channel %d: send open", id);
 652         packet_start(SSH2_MSG_CHANNEL_OPEN);
 653         packet_put_cstring(c->ctype);
 654         packet_put_int(c->self);
 655         packet_put_int(c->local_window);
 656         packet_put_int(c->local_maxpacket);
 657         packet_send();
 658 }
 659
 660 void
 661 channel_request_start(int id, char *service, int wantconfirm)
 662 {
 663         Channel *c = channel_lookup(id);
 664
 665         if (c == NULL) {
 666                 logit("channel_request_start: %d: unknown channel id", id);
 667                 return;
 668         }
 669         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 670         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 671         packet_put_int(c->remote_id);
 672         packet_put_cstring(service);
 673         packet_put_char(wantconfirm);
 674 }
 675
 676 void
 677 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 678     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 679 {
 680         struct channel_confirm *cc;
 681         Channel *c;
 682
 683         if ((c = channel_lookup(id)) == NULL)
 684                 fatal("channel_register_expect: %d: bad id", id);
 685
 686         cc = xmalloc(sizeof(*cc));
 687         cc->cb = cb;
 688         cc->abandon_cb = abandon_cb;
 689         cc->ctx = ctx;
 690         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 691 }
 692
 693 void
 694 channel_register_open_confirm(int id, channel_callback_fn *fn, void *ctx)
 695 {
 696         Channel *c = channel_lookup(id);
 697
 698         if (c == NULL) {
 699                 logit("channel_register_open_confirm: %d: bad id", id);
 700                 return;
 701         }
 702         c->open_confirm = fn;
 703         c->open_confirm_ctx = ctx;
 704 }
 705
 706 void
 707 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 708 {
 709         Channel *c = channel_by_id(id);
 710
 711         if (c == NULL) {
 712                 logit("channel_register_cleanup: %d: bad id", id);
 713                 return;
 714         }
 715         c->detach_user = fn;
 716         c->detach_close = do_close;
 717 }
 718
 719 void
 720 channel_cancel_cleanup(int id)
 721 {
 722         Channel *c = channel_by_id(id);
 723
 724         if (c == NULL) {
 725                 logit("channel_cancel_cleanup: %d: bad id", id);
 726                 return;
 727         }
 728         c->detach_user = NULL;
 729         c->detach_close = 0;
 730 }
 731
 732 void
 733 channel_register_filter(int id, channel_infilter_fn *ifn,
 734     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 735 {
 736         Channel *c = channel_lookup(id);
 737
 738         if (c == NULL) {
 739                 logit("channel_register_filter: %d: bad id", id);
 740                 return;
 741         }
 742         c->input_filter = ifn;
 743         c->output_filter = ofn;
 744         c->filter_ctx = ctx;
 745         c->filter_cleanup = cfn;
 746 }
 747
 748 void
 749 channel_set_fds(int id, int rfd, int wfd, int efd,
 750     int extusage, int nonblock, int is_tty, u_int window_max)
 751 {
 752         Channel *c = channel_lookup(id);
 753
 754         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 755                 fatal("channel_activate for non-larval channel %d.", id);
 756         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 757         c->type = SSH_CHANNEL_OPEN;
 758         c->local_window = c->local_window_max = window_max;
 759         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 760         packet_put_int(c->remote_id);
 761         packet_put_int(c->local_window);
 762         packet_send();
 763 }
 764
 765 /*
 766  * 'channel_pre*' are called just before select() to add any bits relevant to
 767  * channels in the select bitmasks.
 768  */
 769 /*
 770  * 'channel_post*': perform any appropriate operations for channels which
 771  * have events pending.
 772  */
 773 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 774 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 775 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 776
 777 /* ARGSUSED */
 778 static void
 779 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 780 {
 781         FD_SET(c->sock, readset);
 782 }
 783
 784 /* ARGSUSED */
 785 static void
 786 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 787 {
 788         debug3("channel %d: waiting for connection", c->self);
 789         FD_SET(c->sock, writeset);
 790 }
 791
 792 static void
 793 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 794 {
 795         if (buffer_len(&c->input) < packet_get_maxsize())
 796                 FD_SET(c->sock, readset);
 797         if (buffer_len(&c->output) > 0)
 798                 FD_SET(c->sock, writeset);
 799 }
 800
 801 static void
 802 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 803 {
 804         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 805
 806         if (c->istate == CHAN_INPUT_OPEN &&
 807             limit > 0 &&
 808             buffer_len(&c->input) < limit &&
 809             buffer_check_alloc(&c->input, CHAN_RBUF))
 810                 FD_SET(c->rfd, readset);
 811         if (c->ostate == CHAN_OUTPUT_OPEN ||
 812             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 813                 if (buffer_len(&c->output) > 0) {
 814                         FD_SET(c->wfd, writeset);
 815                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 816                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 817                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 818                                     c->self, c->efd, buffer_len(&c->extended));
 819                         else
 820                                 chan_obuf_empty(c);
 821                 }
 822         }
 823         /** XXX check close conditions, too */
 824         if (compat20 && c->efd != -1 &&
 825             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 826                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 827                     buffer_len(&c->extended) > 0)
 828                         FD_SET(c->efd, writeset);
 829                 else if (!(c->flags & CHAN_EOF_SENT) &&
 830                     c->extended_usage == CHAN_EXTENDED_READ &&
 831                     buffer_len(&c->extended) < c->remote_window)
 832                         FD_SET(c->efd, readset);
 833         }
 834         /* XXX: What about efd? races? */
 835         if (compat20 && c->ctl_fd != -1 &&
 836             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 837                 FD_SET(c->ctl_fd, readset);
 838 }
 839
 840 /* ARGSUSED */
 841 static void
 842 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 843 {
 844         if (buffer_len(&c->input) == 0) {
 845                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 846                 packet_put_int(c->remote_id);
 847                 packet_send();
 848                 c->type = SSH_CHANNEL_CLOSED;
 849                 debug2("channel %d: closing after input drain.", c->self);
 850         }
 851 }
 852
 853 /* ARGSUSED */
 854 static void
 855 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 856 {
 857         if (buffer_len(&c->output) == 0)
 858                 chan_mark_dead(c);
 859         else
 860                 FD_SET(c->sock, writeset);
 861 }
 862
 863 /*
 864  * This is a special state for X11 authentication spoofing.  An opened X11
 865  * connection (when authentication spoofing is being done) remains in this
 866  * state until the first packet has been completely read.  The authentication
 867  * data in that packet is then substituted by the real data if it matches the
 868  * fake data, and the channel is put into normal mode.
 869  * XXX All this happens at the client side.
 870  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 871  */
 872 static int
 873 x11_open_helper(Buffer *b)
 874 {
 875         u_char *ucp;
 876         u_int proto_len, data_len;
 877
 878         /* Check if the fixed size part of the packet is in buffer. */
 879         if (buffer_len(b) < 12)
 880                 return 0;
 881
 882         /* Parse the lengths of variable-length fields. */
 883         ucp = buffer_ptr(b);
 884         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 885                 proto_len = 256 * ucp[6] + ucp[7];
 886                 data_len = 256 * ucp[8] + ucp[9];
 887         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 888                 proto_len = ucp[6] + 256 * ucp[7];
 889                 data_len = ucp[8] + 256 * ucp[9];
 890         } else {
 891                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 892                     ucp[0]);
 893                 return -1;
 894         }
 895
 896         /* Check if the whole packet is in buffer. */
 897         if (buffer_len(b) <
 898             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 899                 return 0;
 900
 901         /* Check if authentication protocol matches. */
 902         if (proto_len != strlen(x11_saved_proto) ||
 903             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 904                 debug2("X11 connection uses different authentication protocol.");
 905                 return -1;
 906         }
 907         /* Check if authentication data matches our fake data. */
 908         if (data_len != x11_fake_data_len ||
 909             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 910                 x11_fake_data, x11_fake_data_len) != 0) {
 911                 debug2("X11 auth data does not match fake data.");
 912                 return -1;
 913         }
 914         /* Check fake data length */
 915         if (x11_fake_data_len != x11_saved_data_len) {
 916                 error("X11 fake_data_len %d != saved_data_len %d",
 917                     x11_fake_data_len, x11_saved_data_len);
 918                 return -1;
 919         }
 920         /*
 921          * Received authentication protocol and data match
 922          * our fake data. Substitute the fake data with real
 923          * data.
 924          */
 925         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 926             x11_saved_data, x11_saved_data_len);
 927         return 1;
 928 }
 929
 930 static void
 931 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 932 {
 933         int ret = x11_open_helper(&c->output);
 934
 935         if (ret == 1) {
 936                 /* Start normal processing for the channel. */
 937                 c->type = SSH_CHANNEL_OPEN;
 938                 channel_pre_open_13(c, readset, writeset);
 939         } else if (ret == -1) {
 940                 /*
 941                  * We have received an X11 connection that has bad
 942                  * authentication information.
 943                  */
 944                 logit("X11 connection rejected because of wrong authentication.");
 945                 buffer_clear(&c->input);
 946                 buffer_clear(&c->output);
 947                 channel_close_fd(&c->sock);
 948                 c->sock = -1;
 949                 c->type = SSH_CHANNEL_CLOSED;
 950                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 951                 packet_put_int(c->remote_id);
 952                 packet_send();
 953         }
 954 }
 955
 956 static void
 957 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 958 {
 959         int ret = x11_open_helper(&c->output);
 960
 961         /* c->force_drain = 1; */
 962
 963         if (ret == 1) {
 964                 c->type = SSH_CHANNEL_OPEN;
 965                 channel_pre_open(c, readset, writeset);
 966         } else if (ret == -1) {
 967                 logit("X11 connection rejected because of wrong authentication.");
 968                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 969                 chan_read_failed(c);
 970                 buffer_clear(&c->input);
 971                 chan_ibuf_empty(c);
 972                 buffer_clear(&c->output);
 973                 /* for proto v1, the peer will send an IEOF */
 974                 if (compat20)
 975                         chan_write_failed(c);
 976                 else
 977                         c->type = SSH_CHANNEL_OPEN;
 978                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 979         }
 980 }
 981
 982 /* try to decode a socks4 header */
 983 /* ARGSUSED */
 984 static int
 985 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 986 {
 987         char *p, *host;
 988         u_int len, have, i, found, need;
 989         char username[256];
 990         struct {
 991                 u_int8_t version;
 992                 u_int8_t command;
 993                 u_int16_t dest_port;
 994                 struct in_addr dest_addr;
 995         } s4_req, s4_rsp;
 996
 997         debug2("channel %d: decode socks4", c->self);
 998
 999         have = buffer_len(&c->input);
1000         len = sizeof(s4_req);
1001         if (have < len)
1002                 return 0;
1003         p = buffer_ptr(&c->input);
1004
1005         need = 1;
1006         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1007         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1008                 debug2("channel %d: socks4a request", c->self);
1009                 /* ... and needs an extra string (the hostname) */
1010                 need = 2;
1011         }
1012         /* Check for terminating NUL on the string(s) */
1013         for (found = 0, i = len; i < have; i++) {
1014                 if (p[i] == '\0') {
1015                         found++;
1016                         if (found == need)
1017                                 break;
1018                 }
1019                 if (i > 1024) {
1020                         /* the peer is probably sending garbage */
1021                         debug("channel %d: decode socks4: too long",
1022                             c->self);
1023                         return -1;
1024                 }
1025         }
1026         if (found < need)
1027                 return 0;
1028         buffer_get(&c->input, (char *)&s4_req.version, 1);
1029         buffer_get(&c->input, (char *)&s4_req.command, 1);
1030         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1031         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1032         have = buffer_len(&c->input);
1033         p = buffer_ptr(&c->input);
1034         len = strlen(p);
1035         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1036         len++;                                  /* trailing '\0' */
1037         if (len > have)
1038                 fatal("channel %d: decode socks4: len %d > have %d",
1039                     c->self, len, have);
1040         strlcpy(username, p, sizeof(username));
1041         buffer_consume(&c->input, len);
1042
1043         if (c->path != NULL) {
1044                 xfree(c->path);
1045                 c->path = NULL;
1046         }
1047         if (need == 1) {                        /* SOCKS4: one string */
1048                 host = inet_ntoa(s4_req.dest_addr);
1049                 c->path = xstrdup(host);
1050         } else {                                /* SOCKS4A: two strings */
1051                 have = buffer_len(&c->input);
1052                 p = buffer_ptr(&c->input);
1053                 len = strlen(p);
1054                 debug2("channel %d: decode socks4a: host %s/%d",
1055                     c->self, p, len);
1056                 len++;                          /* trailing '\0' */
1057                 if (len > have)
1058                         fatal("channel %d: decode socks4a: len %d > have %d",
1059                             c->self, len, have);
1060                 if (len > NI_MAXHOST) {
1061                         error("channel %d: hostname \"%.100s\" too long",
1062                             c->self, p);
1063                         return -1;
1064                 }
1065                 c->path = xstrdup(p);
1066                 buffer_consume(&c->input, len);
1067         }
1068         c->host_port = ntohs(s4_req.dest_port);
1069
1070         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1071             c->self, c->path, c->host_port, s4_req.command);
1072
1073         if (s4_req.command != 1) {
1074                 debug("channel %d: cannot handle: %s cn %d",
1075                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1076                 return -1;
1077         }
1078         s4_rsp.version = 0;                     /* vn: 0 for reply */
1079         s4_rsp.command = 90;                    /* cd: req granted */
1080         s4_rsp.dest_port = 0;                   /* ignored */
1081         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1082         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1083         return 1;
1084 }
1085
1086 /* try to decode a socks5 header */
1087 #define SSH_SOCKS5_AUTHDONE     0x1000
1088 #define SSH_SOCKS5_NOAUTH       0x00
1089 #define SSH_SOCKS5_IPV4         0x01
1090 #define SSH_SOCKS5_DOMAIN       0x03
1091 #define SSH_SOCKS5_IPV6         0x04
1092 #define SSH_SOCKS5_CONNECT      0x01
1093 #define SSH_SOCKS5_SUCCESS      0x00
1094
1095 /* ARGSUSED */
1096 static int
1097 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1098 {
1099         struct {
1100                 u_int8_t version;
1101                 u_int8_t command;
1102                 u_int8_t reserved;
1103                 u_int8_t atyp;
1104         } s5_req, s5_rsp;
1105         u_int16_t dest_port;
1106         u_char *p, dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1107         u_int have, need, i, found, nmethods, addrlen, af;
1108
1109         debug2("channel %d: decode socks5", c->self);
1110         p = buffer_ptr(&c->input);
1111         if (p[0] != 0x05)
1112                 return -1;
1113         have = buffer_len(&c->input);
1114         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1115                 /* format: ver | nmethods | methods */
1116                 if (have < 2)
1117                         return 0;
1118                 nmethods = p[1];
1119                 if (have < nmethods + 2)
1120                         return 0;
1121                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1122                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1123                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1124                                 found = 1;
1125                                 break;
1126                         }
1127                 }
1128                 if (!found) {
1129                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1130                             c->self);
1131                         return -1;
1132                 }
1133                 buffer_consume(&c->input, nmethods + 2);
1134                 buffer_put_char(&c->output, 0x05);              /* version */
1135                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1136                 FD_SET(c->sock, writeset);
1137                 c->flags |= SSH_SOCKS5_AUTHDONE;
1138                 debug2("channel %d: socks5 auth done", c->self);
1139                 return 0;                               /* need more */
1140         }
1141         debug2("channel %d: socks5 post auth", c->self);
1142         if (have < sizeof(s5_req)+1)
1143                 return 0;                       /* need more */
1144         memcpy(&s5_req, p, sizeof(s5_req));
1145         if (s5_req.version != 0x05 ||
1146             s5_req.command != SSH_SOCKS5_CONNECT ||
1147             s5_req.reserved != 0x00) {
1148                 debug2("channel %d: only socks5 connect supported", c->self);
1149                 return -1;
1150         }
1151         switch (s5_req.atyp){
1152         case SSH_SOCKS5_IPV4:
1153                 addrlen = 4;
1154                 af = AF_INET;
1155                 break;
1156         case SSH_SOCKS5_DOMAIN:
1157                 addrlen = p[sizeof(s5_req)];
1158                 af = -1;
1159                 break;
1160         case SSH_SOCKS5_IPV6:
1161                 addrlen = 16;
1162                 af = AF_INET6;
1163                 break;
1164         default:
1165                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1166                 return -1;
1167         }
1168         need = sizeof(s5_req) + addrlen + 2;
1169         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1170                 need++;
1171         if (have < need)
1172                 return 0;
1173         buffer_consume(&c->input, sizeof(s5_req));
1174         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1175                 buffer_consume(&c->input, 1);    /* host string length */
1176         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1177         buffer_get(&c->input, (char *)&dest_port, 2);
1178         dest_addr[addrlen] = '\0';
1179         if (c->path != NULL) {
1180                 xfree(c->path);
1181                 c->path = NULL;
1182         }
1183         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1184                 if (addrlen >= NI_MAXHOST) {
1185                         error("channel %d: dynamic request: socks5 hostname "
1186                             "\"%.100s\" too long", c->self, dest_addr);
1187                         return -1;
1188                 }
1189                 c->path = xstrdup(dest_addr);
1190         } else {
1191                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1192                         return -1;
1193                 c->path = xstrdup(ntop);
1194         }
1195         c->host_port = ntohs(dest_port);
1196
1197         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1198             c->self, c->path, c->host_port, s5_req.command);
1199
1200         s5_rsp.version = 0x05;
1201         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1202         s5_rsp.reserved = 0;                    /* ignored */
1203         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1204         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1205         dest_port = 0;                          /* ignored */
1206
1207         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1208         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1209         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1210         return 1;
1211 }
1212
1213 /* dynamic port forwarding */
1214 static void
1215 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1216 {
1217         u_char *p;
1218         u_int have;
1219         int ret;
1220
1221         have = buffer_len(&c->input);
1222         c->delayed = 0;
1223         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1224         /* buffer_dump(&c->input); */
1225         /* check if the fixed size part of the packet is in buffer. */
1226         if (have < 3) {
1227                 /* need more */
1228                 FD_SET(c->sock, readset);
1229                 return;
1230         }
1231         /* try to guess the protocol */
1232         p = buffer_ptr(&c->input);
1233         switch (p[0]) {
1234         case 0x04:
1235                 ret = channel_decode_socks4(c, readset, writeset);
1236                 break;
1237         case 0x05:
1238                 ret = channel_decode_socks5(c, readset, writeset);
1239                 break;
1240         default:
1241                 ret = -1;
1242                 break;
1243         }
1244         if (ret < 0) {
1245                 chan_mark_dead(c);
1246         } else if (ret == 0) {
1247                 debug2("channel %d: pre_dynamic: need more", c->self);
1248                 /* need more */
1249                 FD_SET(c->sock, readset);
1250         } else {
1251                 /* switch to the next state */
1252                 c->type = SSH_CHANNEL_OPENING;
1253                 port_open_helper(c, "direct-tcpip");
1254         }
1255 }
1256
1257 /* This is our fake X11 server socket. */
1258 /* ARGSUSED */
1259 static void
1260 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1261 {
1262         Channel *nc;
1263         struct sockaddr_storage addr;
1264         int newsock;
1265         socklen_t addrlen;
1266         char buf[16384], *remote_ipaddr;
1267         int remote_port;
1268
1269         if (FD_ISSET(c->sock, readset)) {
1270                 debug("X11 connection requested.");
1271                 addrlen = sizeof(addr);
1272                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1273                 if (c->single_connection) {
1274                         debug2("single_connection: closing X11 listener.");
1275                         channel_close_fd(&c->sock);
1276                         chan_mark_dead(c);
1277                 }
1278                 if (newsock < 0) {
1279                         error("accept: %.100s", strerror(errno));
1280                         return;
1281                 }
1282                 set_nodelay(newsock);
1283                 remote_ipaddr = get_peer_ipaddr(newsock);
1284                 remote_port = get_peer_port(newsock);
1285                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1286                     remote_ipaddr, remote_port);
1287
1288                 nc = channel_new("accepted x11 socket",
1289                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1290                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1291                 if (compat20) {
1292                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1293                         packet_put_cstring("x11");
1294                         packet_put_int(nc->self);
1295                         packet_put_int(nc->local_window_max);
1296                         packet_put_int(nc->local_maxpacket);
1297                         /* originator ipaddr and port */
1298                         packet_put_cstring(remote_ipaddr);
1299                         if (datafellows & SSH_BUG_X11FWD) {
1300                                 debug2("ssh2 x11 bug compat mode");
1301                         } else {
1302                                 packet_put_int(remote_port);
1303                         }
1304                         packet_send();
1305                 } else {
1306                         packet_start(SSH_SMSG_X11_OPEN);
1307                         packet_put_int(nc->self);
1308                         if (packet_get_protocol_flags() &
1309                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1310                                 packet_put_cstring(buf);
1311                         packet_send();
1312                 }
1313                 xfree(remote_ipaddr);
1314         }
1315 }
1316
1317 static void
1318 port_open_helper(Channel *c, char *rtype)
1319 {
1320         int direct;
1321         char buf[1024];
1322         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1323         int remote_port = get_peer_port(c->sock);
1324
1325         direct = (strcmp(rtype, "direct-tcpip") == 0);
1326
1327         snprintf(buf, sizeof buf,
1328             "%s: listening port %d for %.100s port %d, "
1329             "connect from %.200s port %d",
1330             rtype, c->listening_port, c->path, c->host_port,
1331             remote_ipaddr, remote_port);
1332
1333         xfree(c->remote_name);
1334         c->remote_name = xstrdup(buf);
1335
1336         if (compat20) {
1337                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1338                 packet_put_cstring(rtype);
1339                 packet_put_int(c->self);
1340                 packet_put_int(c->local_window_max);
1341                 packet_put_int(c->local_maxpacket);
1342                 if (direct) {
1343                         /* target host, port */
1344                         packet_put_cstring(c->path);
1345                         packet_put_int(c->host_port);
1346                 } else {
1347                         /* listen address, port */
1348                         packet_put_cstring(c->path);
1349                         packet_put_int(c->listening_port);
1350                 }
1351                 /* originator host and port */
1352                 packet_put_cstring(remote_ipaddr);
1353                 packet_put_int((u_int)remote_port);
1354                 packet_send();
1355         } else {
1356                 packet_start(SSH_MSG_PORT_OPEN);
1357                 packet_put_int(c->self);
1358                 packet_put_cstring(c->path);
1359                 packet_put_int(c->host_port);
1360                 if (packet_get_protocol_flags() &
1361                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1362                         packet_put_cstring(c->remote_name);
1363                 packet_send();
1364         }
1365         xfree(remote_ipaddr);
1366 }
1367
1368 static void
1369 channel_set_reuseaddr(int fd)
1370 {
1371         int on = 1;
1372
1373         /*
1374          * Set socket options.
1375          * Allow local port reuse in TIME_WAIT.
1376          */
1377         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1378                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1379 }
1380
1381 /*
1382  * This socket is listening for connections to a forwarded TCP/IP port.
1383  */
1384 /* ARGSUSED */
1385 static void
1386 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1387 {
1388         Channel *nc;
1389         struct sockaddr_storage addr;
1390         int newsock, nextstate;
1391         socklen_t addrlen;
1392         char *rtype;
1393
1394         if (FD_ISSET(c->sock, readset)) {
1395                 debug("Connection to port %d forwarding "
1396                     "to %.100s port %d requested.",
1397                     c->listening_port, c->path, c->host_port);
1398
1399                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1400                         nextstate = SSH_CHANNEL_OPENING;
1401                         rtype = "forwarded-tcpip";
1402                 } else {
1403                         if (c->host_port == 0) {
1404                                 nextstate = SSH_CHANNEL_DYNAMIC;
1405                                 rtype = "dynamic-tcpip";
1406                         } else {
1407                                 nextstate = SSH_CHANNEL_OPENING;
1408                                 rtype = "direct-tcpip";
1409                         }
1410                 }
1411
1412                 addrlen = sizeof(addr);
1413                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1414                 if (newsock < 0) {
1415                         error("accept: %.100s", strerror(errno));
1416                         return;
1417                 }
1418                 set_nodelay(newsock);
1419                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1420                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1421                 nc->listening_port = c->listening_port;
1422                 nc->host_port = c->host_port;
1423                 if (c->path != NULL)
1424                         nc->path = xstrdup(c->path);
1425
1426                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1427                         /*
1428                          * do not call the channel_post handler until
1429                          * this flag has been reset by a pre-handler.
1430                          * otherwise the FD_ISSET calls might overflow
1431                          */
1432                         nc->delayed = 1;
1433                 } else {
1434                         port_open_helper(nc, rtype);
1435                 }
1436         }
1437 }
1438
1439 /*
1440  * This is the authentication agent socket listening for connections from
1441  * clients.
1442  */
1443 /* ARGSUSED */
1444 static void
1445 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1446 {
1447         Channel *nc;
1448         int newsock;
1449         struct sockaddr_storage addr;
1450         socklen_t addrlen;
1451
1452         if (FD_ISSET(c->sock, readset)) {
1453                 addrlen = sizeof(addr);
1454                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1455                 if (newsock < 0) {
1456                         error("accept from auth socket: %.100s", strerror(errno));
1457                         return;
1458                 }
1459                 nc = channel_new("accepted auth socket",
1460                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1461                     c->local_window_max, c->local_maxpacket,
1462                     0, "accepted auth socket", 1);
1463                 if (compat20) {
1464                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1465                         packet_put_cstring("auth-agent@openssh.com");
1466                         packet_put_int(nc->self);
1467                         packet_put_int(c->local_window_max);
1468                         packet_put_int(c->local_maxpacket);
1469                 } else {
1470                         packet_start(SSH_SMSG_AGENT_OPEN);
1471                         packet_put_int(nc->self);
1472                 }
1473                 packet_send();
1474         }
1475 }
1476
1477 /* ARGSUSED */
1478 static void
1479 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1480 {
1481         int err = 0, sock;
1482         socklen_t sz = sizeof(err);
1483
1484         if (FD_ISSET(c->sock, writeset)) {
1485                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1486                         err = errno;
1487                         error("getsockopt SO_ERROR failed");
1488                 }
1489                 if (err == 0) {
1490                         debug("channel %d: connected to %s port %d",
1491                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1492                         channel_connect_ctx_free(&c->connect_ctx);
1493                         c->type = SSH_CHANNEL_OPEN;
1494                         if (compat20) {
1495                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1496                                 packet_put_int(c->remote_id);
1497                                 packet_put_int(c->self);
1498                                 packet_put_int(c->local_window);
1499                                 packet_put_int(c->local_maxpacket);
1500                         } else {
1501                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1502                                 packet_put_int(c->remote_id);
1503                                 packet_put_int(c->self);
1504                         }
1505                 } else {
1506                         debug("channel %d: connection failed: %s",
1507                             c->self, strerror(err));
1508                         /* Try next address, if any */
1509                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1510                                 close(c->sock);
1511                                 c->sock = c->rfd = c->wfd = sock;
1512                                 channel_max_fd = channel_find_maxfd();
1513                                 return;
1514                         }
1515                         /* Exhausted all addresses */
1516                         error("connect_to %.100s port %d: failed.",
1517                             c->connect_ctx.host, c->connect_ctx.port);
1518                         channel_connect_ctx_free(&c->connect_ctx);
1519                         if (compat20) {
1520                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1521                                 packet_put_int(c->remote_id);
1522                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1523                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1524                                         packet_put_cstring(strerror(err));
1525                                         packet_put_cstring("");
1526                                 }
1527                         } else {
1528                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1529                                 packet_put_int(c->remote_id);
1530                         }
1531                         chan_mark_dead(c);
1532                 }
1533                 packet_send();
1534         }
1535 }
1536
1537 /* ARGSUSED */
1538 static int
1539 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1540 {
1541         char buf[CHAN_RBUF];
1542         int len, force;
1543
1544         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1545         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1546                 errno = 0;
1547                 len = read(c->rfd, buf, sizeof(buf));
1548                 if (len < 0 && (errno == EINTR ||
1549                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1550                         return 1;
1551 #ifndef PTY_ZEROREAD
1552                 if (len <= 0) {
1553 #else
1554                 if ((!c->isatty && len <= 0) ||
1555                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1556 #endif
1557                         debug2("channel %d: read<=0 rfd %d len %d",
1558                             c->self, c->rfd, len);
1559                         if (c->type != SSH_CHANNEL_OPEN) {
1560                                 debug2("channel %d: not open", c->self);
1561                                 chan_mark_dead(c);
1562                                 return -1;
1563                         } else if (compat13) {
1564                                 buffer_clear(&c->output);
1565                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1566                                 debug2("channel %d: input draining.", c->self);
1567                         } else {
1568                                 chan_read_failed(c);
1569                         }
1570                         return -1;
1571                 }
1572                 if (c->input_filter != NULL) {
1573                         if (c->input_filter(c, buf, len) == -1) {
1574                                 debug2("channel %d: filter stops", c->self);
1575                                 chan_read_failed(c);
1576                         }
1577                 } else if (c->datagram) {
1578                         buffer_put_string(&c->input, buf, len);
1579                 } else {
1580                         buffer_append(&c->input, buf, len);
1581                 }
1582         }
1583         return 1;
1584 }
1585
1586 /* ARGSUSED */
1587 static int
1588 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1589 {
1590         struct termios tio;
1591         u_char *data = NULL, *buf;
1592         u_int dlen;
1593         int len;
1594
1595         /* Send buffered output data to the socket. */
1596         if (c->wfd != -1 &&
1597             FD_ISSET(c->wfd, writeset) &&
1598             buffer_len(&c->output) > 0) {
1599                 if (c->output_filter != NULL) {
1600                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1601                                 debug2("channel %d: filter stops", c->self);
1602                                 if (c->type != SSH_CHANNEL_OPEN)
1603                                         chan_mark_dead(c);
1604                                 else
1605                                         chan_write_failed(c);
1606                                 return -1;
1607                         }
1608                 } else if (c->datagram) {
1609                         buf = data = buffer_get_string(&c->output, &dlen);
1610                 } else {
1611                         buf = data = buffer_ptr(&c->output);
1612                         dlen = buffer_len(&c->output);
1613                 }
1614
1615                 if (c->datagram) {
1616                         /* ignore truncated writes, datagrams might get lost */
1617                         c->local_consumed += dlen + 4;
1618                         len = write(c->wfd, buf, dlen);
1619                         xfree(data);
1620                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1621                             errno == EWOULDBLOCK))
1622                                 return 1;
1623                         if (len <= 0) {
1624                                 if (c->type != SSH_CHANNEL_OPEN)
1625                                         chan_mark_dead(c);
1626                                 else
1627                                         chan_write_failed(c);
1628                                 return -1;
1629                         }
1630                         return 1;
1631                 }
1632 #ifdef _AIX
1633                 /* XXX: Later AIX versions can't push as much data to tty */
1634                 if (compat20 && c->wfd_isatty)
1635                         dlen = MIN(dlen, 8*1024);
1636 #endif
1637
1638                 len = write(c->wfd, buf, dlen);
1639                 if (len < 0 &&
1640                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1641                         return 1;
1642                 if (len <= 0) {
1643                         if (c->type != SSH_CHANNEL_OPEN) {
1644                                 debug2("channel %d: not open", c->self);
1645                                 chan_mark_dead(c);
1646                                 return -1;
1647                         } else if (compat13) {
1648                                 buffer_clear(&c->output);
1649                                 debug2("channel %d: input draining.", c->self);
1650                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1651                         } else {
1652                                 chan_write_failed(c);
1653                         }
1654                         return -1;
1655                 }
1656                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1657                         if (tcgetattr(c->wfd, &tio) == 0 &&
1658                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1659                                 /*
1660                                  * Simulate echo to reduce the impact of
1661                                  * traffic analysis. We need to match the
1662                                  * size of a SSH2_MSG_CHANNEL_DATA message
1663                                  * (4 byte channel id + buf)
1664                                  */
1665                                 packet_send_ignore(4 + len);
1666                                 packet_send();
1667                         }
1668                 }
1669                 buffer_consume(&c->output, len);
1670                 if (compat20 && len > 0) {
1671                         c->local_consumed += len;
1672                 }
1673         }
1674         return 1;
1675 }
1676
1677 static int
1678 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1679 {
1680         char buf[CHAN_RBUF];
1681         int len;
1682
1683 /** XXX handle drain efd, too */
1684         if (c->efd != -1) {
1685                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1686                     FD_ISSET(c->efd, writeset) &&
1687                     buffer_len(&c->extended) > 0) {
1688                         len = write(c->efd, buffer_ptr(&c->extended),
1689                             buffer_len(&c->extended));
1690                         debug2("channel %d: written %d to efd %d",
1691                             c->self, len, c->efd);
1692                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1693                             errno == EWOULDBLOCK))
1694                                 return 1;
1695                         if (len <= 0) {
1696                                 debug2("channel %d: closing write-efd %d",
1697                                     c->self, c->efd);
1698                                 channel_close_fd(&c->efd);
1699                         } else {
1700                                 buffer_consume(&c->extended, len);
1701                                 c->local_consumed += len;
1702                         }
1703                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1704                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1705                         len = read(c->efd, buf, sizeof(buf));
1706                         debug2("channel %d: read %d from efd %d",
1707                             c->self, len, c->efd);
1708                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1709                             errno == EWOULDBLOCK) && !c->detach_close)))
1710                                 return 1;
1711                         if (len <= 0) {
1712                                 debug2("channel %d: closing read-efd %d",
1713                                     c->self, c->efd);
1714                                 channel_close_fd(&c->efd);
1715                         } else {
1716                                 buffer_append(&c->extended, buf, len);
1717                         }
1718                 }
1719         }
1720         return 1;
1721 }
1722
1723 /* ARGSUSED */
1724 static int
1725 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1726 {
1727         char buf[16];
1728         int len;
1729
1730         /* Monitor control fd to detect if the slave client exits */
1731         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1732                 len = read(c->ctl_fd, buf, sizeof(buf));
1733                 if (len < 0 &&
1734                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1735                         return 1;
1736                 if (len <= 0) {
1737                         debug2("channel %d: ctl read<=0", c->self);
1738                         if (c->type != SSH_CHANNEL_OPEN) {
1739                                 debug2("channel %d: not open", c->self);
1740                                 chan_mark_dead(c);
1741                                 return -1;
1742                         } else {
1743                                 chan_read_failed(c);
1744                                 chan_write_failed(c);
1745                         }
1746                         return -1;
1747                 } else
1748                         fatal("%s: unexpected data on ctl fd", __func__);
1749         }
1750         return 1;
1751 }
1752
1753 static int
1754 channel_check_window(Channel *c)
1755 {
1756         if (c->type == SSH_CHANNEL_OPEN &&
1757             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1758             ((c->local_window_max - c->local_window >
1759             c->local_maxpacket*3) ||
1760             c->local_window < c->local_window_max/2) &&
1761             c->local_consumed > 0) {
1762                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1763                 packet_put_int(c->remote_id);
1764                 packet_put_int(c->local_consumed);
1765                 packet_send();
1766                 debug2("channel %d: window %d sent adjust %d",
1767                     c->self, c->local_window,
1768                     c->local_consumed);
1769                 c->local_window += c->local_consumed;
1770                 c->local_consumed = 0;
1771         }
1772         return 1;
1773 }
1774
1775 static void
1776 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1777 {
1778         if (c->delayed)
1779                 return;
1780         channel_handle_rfd(c, readset, writeset);
1781         channel_handle_wfd(c, readset, writeset);
1782         if (!compat20)
1783                 return;
1784         channel_handle_efd(c, readset, writeset);
1785         channel_handle_ctl(c, readset, writeset);
1786         channel_check_window(c);
1787 }
1788
1789 /* ARGSUSED */
1790 static void
1791 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1792 {
1793         int len;
1794
1795         /* Send buffered output data to the socket. */
1796         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1797                 len = write(c->sock, buffer_ptr(&c->output),
1798                             buffer_len(&c->output));
1799                 if (len <= 0)
1800                         buffer_clear(&c->output);
1801                 else
1802                         buffer_consume(&c->output, len);
1803         }
1804 }
1805
1806 static void
1807 channel_handler_init_20(void)
1808 {
1809         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1810         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1811         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1812         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1813         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1814         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1815         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1816         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1817
1818         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1819         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1820         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1821         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1822         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1823         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1824         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1825 }
1826
1827 static void
1828 channel_handler_init_13(void)
1829 {
1830         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1831         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1832         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1833         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1834         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1835         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1836         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1837         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1838         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1839
1840         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1841         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1842         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1843         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1844         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1845         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1846         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1847 }
1848
1849 static void
1850 channel_handler_init_15(void)
1851 {
1852         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1853         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1854         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1855         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1856         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1857         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1858         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1859
1860         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1861         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1862         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1863         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1864         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1865         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1866 }
1867
1868 static void
1869 channel_handler_init(void)
1870 {
1871         int i;
1872
1873         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1874                 channel_pre[i] = NULL;
1875                 channel_post[i] = NULL;
1876         }
1877         if (compat20)
1878                 channel_handler_init_20();
1879         else if (compat13)
1880                 channel_handler_init_13();
1881         else
1882                 channel_handler_init_15();
1883 }
1884
1885 /* gc dead channels */
1886 static void
1887 channel_garbage_collect(Channel *c)
1888 {
1889         if (c == NULL)
1890                 return;
1891         if (c->detach_user != NULL) {
1892                 if (!chan_is_dead(c, c->detach_close))
1893                         return;
1894                 debug2("channel %d: gc: notify user", c->self);
1895                 c->detach_user(c->self, NULL);
1896                 /* if we still have a callback */
1897                 if (c->detach_user != NULL)
1898                         return;
1899                 debug2("channel %d: gc: user detached", c->self);
1900         }
1901         if (!chan_is_dead(c, 1))
1902                 return;
1903         debug2("channel %d: garbage collecting", c->self);
1904         channel_free(c);
1905 }
1906
1907 static void
1908 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1909 {
1910         static int did_init = 0;
1911         u_int i;
1912         Channel *c;
1913
1914         if (!did_init) {
1915                 channel_handler_init();
1916                 did_init = 1;
1917         }
1918         for (i = 0; i < channels_alloc; i++) {
1919                 c = channels[i];
1920                 if (c == NULL)
1921                         continue;
1922                 if (ftab[c->type] != NULL)
1923                         (*ftab[c->type])(c, readset, writeset);
1924                 channel_garbage_collect(c);
1925         }
1926 }
1927
1928 /*
1929  * Allocate/update select bitmasks and add any bits relevant to channels in
1930  * select bitmasks.
1931  */
1932 void
1933 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1934     u_int *nallocp, int rekeying)
1935 {
1936         u_int n, sz, nfdset;
1937
1938         n = MAX(*maxfdp, channel_max_fd);
1939
1940         nfdset = howmany(n+1, NFDBITS);
1941         /* Explicitly test here, because xrealloc isn't always called */
1942         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1943                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1944         sz = nfdset * sizeof(fd_mask);
1945
1946         /* perhaps check sz < nalloc/2 and shrink? */
1947         if (*readsetp == NULL || sz > *nallocp) {
1948                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1949                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1950                 *nallocp = sz;
1951         }
1952         *maxfdp = n;
1953         memset(*readsetp, 0, sz);
1954         memset(*writesetp, 0, sz);
1955
1956         if (!rekeying)
1957                 channel_handler(channel_pre, *readsetp, *writesetp);
1958 }
1959
1960 /*
1961  * After select, perform any appropriate operations for channels which have
1962  * events pending.
1963  */
1964 void
1965 channel_after_select(fd_set *readset, fd_set *writeset)
1966 {
1967         channel_handler(channel_post, readset, writeset);
1968 }
1969
1970
1971 /* If there is data to send to the connection, enqueue some of it now. */
1972 void
1973 channel_output_poll(void)
1974 {
1975         Channel *c;
1976         u_int i, len;
1977
1978         for (i = 0; i < channels_alloc; i++) {
1979                 c = channels[i];
1980                 if (c == NULL)
1981                         continue;
1982
1983                 /*
1984                  * We are only interested in channels that can have buffered
1985                  * incoming data.
1986                  */
1987                 if (compat13) {
1988                         if (c->type != SSH_CHANNEL_OPEN &&
1989                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1990                                 continue;
1991                 } else {
1992                         if (c->type != SSH_CHANNEL_OPEN)
1993                                 continue;
1994                 }
1995                 if (compat20 &&
1996                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1997                         /* XXX is this true? */
1998                         debug3("channel %d: will not send data after close", c->self);
1999                         continue;
2000                 }
2001
2002                 /* Get the amount of buffered data for this channel. */
2003                 if ((c->istate == CHAN_INPUT_OPEN ||
2004                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2005                     (len = buffer_len(&c->input)) > 0) {
2006                         if (c->datagram) {
2007                                 if (len > 0) {
2008                                         u_char *data;
2009                                         u_int dlen;
2010
2011                                         data = buffer_get_string(&c->input,
2012                                             &dlen);
2013                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2014                                         packet_put_int(c->remote_id);
2015                                         packet_put_string(data, dlen);
2016                                         packet_send();
2017                                         c->remote_window -= dlen + 4;
2018                                         xfree(data);
2019                                 }
2020                                 continue;
2021                         }
2022                         /*
2023                          * Send some data for the other side over the secure
2024                          * connection.
2025                          */
2026                         if (compat20) {
2027                                 if (len > c->remote_window)
2028                                         len = c->remote_window;
2029                                 if (len > c->remote_maxpacket)
2030                                         len = c->remote_maxpacket;
2031                         } else {
2032                                 if (packet_is_interactive()) {
2033                                         if (len > 1024)
2034                                                 len = 512;
2035                                 } else {
2036                                         /* Keep the packets at reasonable size. */
2037                                         if (len > packet_get_maxsize()/2)
2038                                                 len = packet_get_maxsize()/2;
2039                                 }
2040                         }
2041                         if (len > 0) {
2042                                 packet_start(compat20 ?
2043                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2044                                 packet_put_int(c->remote_id);
2045                                 packet_put_string(buffer_ptr(&c->input), len);
2046                                 packet_send();
2047                                 buffer_consume(&c->input, len);
2048                                 c->remote_window -= len;
2049                         }
2050                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2051                         if (compat13)
2052                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2053                         /*
2054                          * input-buffer is empty and read-socket shutdown:
2055                          * tell peer, that we will not send more data: send IEOF.
2056                          * hack for extended data: delay EOF if EFD still in use.
2057                          */
2058                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2059                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2060                                     c->self, c->efd, buffer_len(&c->extended));
2061                         else
2062                                 chan_ibuf_empty(c);
2063                 }
2064                 /* Send extended data, i.e. stderr */
2065                 if (compat20 &&
2066                     !(c->flags & CHAN_EOF_SENT) &&
2067                     c->remote_window > 0 &&
2068                     (len = buffer_len(&c->extended)) > 0 &&
2069                     c->extended_usage == CHAN_EXTENDED_READ) {
2070                         debug2("channel %d: rwin %u elen %u euse %d",
2071                             c->self, c->remote_window, buffer_len(&c->extended),
2072                             c->extended_usage);
2073                         if (len > c->remote_window)
2074                                 len = c->remote_window;
2075                         if (len > c->remote_maxpacket)
2076                                 len = c->remote_maxpacket;
2077                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2078                         packet_put_int(c->remote_id);
2079                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2080                         packet_put_string(buffer_ptr(&c->extended), len);
2081                         packet_send();
2082                         buffer_consume(&c->extended, len);
2083                         c->remote_window -= len;
2084                         debug2("channel %d: sent ext data %d", c->self, len);
2085                 }
2086         }
2087 }
2088
2089
2090 /* -- protocol input */
2091
2092 /* ARGSUSED */
2093 void
2094 channel_input_data(int type, u_int32_t seq, void *ctxt)
2095 {
2096         int id;
2097         char *data;
2098         u_int data_len;
2099         Channel *c;
2100
2101         /* Get the channel number and verify it. */
2102         id = packet_get_int();
2103         c = channel_lookup(id);
2104         if (c == NULL)
2105                 packet_disconnect("Received data for nonexistent channel %d.", id);
2106
2107         /* Ignore any data for non-open channels (might happen on close) */
2108         if (c->type != SSH_CHANNEL_OPEN &&
2109             c->type != SSH_CHANNEL_X11_OPEN)
2110                 return;
2111
2112         /* Get the data. */
2113         data = packet_get_string_ptr(&data_len);
2114
2115         /*
2116          * Ignore data for protocol > 1.3 if output end is no longer open.
2117          * For protocol 2 the sending side is reducing its window as it sends
2118          * data, so we must 'fake' consumption of the data in order to ensure
2119          * that window updates are sent back.  Otherwise the connection might
2120          * deadlock.
2121          */
2122         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2123                 if (compat20) {
2124                         c->local_window -= data_len;
2125                         c->local_consumed += data_len;
2126                 }
2127                 return;
2128         }
2129
2130         if (compat20) {
2131                 if (data_len > c->local_maxpacket) {
2132                         logit("channel %d: rcvd big packet %d, maxpack %d",
2133                             c->self, data_len, c->local_maxpacket);
2134                 }
2135                 if (data_len > c->local_window) {
2136                         logit("channel %d: rcvd too much data %d, win %d",
2137                             c->self, data_len, c->local_window);
2138                         return;
2139                 }
2140                 c->local_window -= data_len;
2141         }
2142         if (c->datagram)
2143                 buffer_put_string(&c->output, data, data_len);
2144         else
2145                 buffer_append(&c->output, data, data_len);
2146         packet_check_eom();
2147 }
2148
2149 /* ARGSUSED */
2150 void
2151 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2152 {
2153         int id;
2154         char *data;
2155         u_int data_len, tcode;
2156         Channel *c;
2157
2158         /* Get the channel number and verify it. */
2159         id = packet_get_int();
2160         c = channel_lookup(id);
2161
2162         if (c == NULL)
2163                 packet_disconnect("Received extended_data for bad channel %d.", id);
2164         if (c->type != SSH_CHANNEL_OPEN) {
2165                 logit("channel %d: ext data for non open", id);
2166                 return;
2167         }
2168         if (c->flags & CHAN_EOF_RCVD) {
2169                 if (datafellows & SSH_BUG_EXTEOF)
2170                         debug("channel %d: accepting ext data after eof", id);
2171                 else
2172                         packet_disconnect("Received extended_data after EOF "
2173                             "on channel %d.", id);
2174         }
2175         tcode = packet_get_int();
2176         if (c->efd == -1 ||
2177             c->extended_usage != CHAN_EXTENDED_WRITE ||
2178             tcode != SSH2_EXTENDED_DATA_STDERR) {
2179                 logit("channel %d: bad ext data", c->self);
2180                 return;
2181         }
2182         data = packet_get_string(&data_len);
2183         packet_check_eom();
2184         if (data_len > c->local_window) {
2185                 logit("channel %d: rcvd too much extended_data %d, win %d",
2186                     c->self, data_len, c->local_window);
2187                 xfree(data);
2188                 return;
2189         }
2190         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2191         c->local_window -= data_len;
2192         buffer_append(&c->extended, data, data_len);
2193         xfree(data);
2194 }
2195
2196 /* ARGSUSED */
2197 void
2198 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2199 {
2200         int id;
2201         Channel *c;
2202
2203         id = packet_get_int();
2204         packet_check_eom();
2205         c = channel_lookup(id);
2206         if (c == NULL)
2207                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2208         chan_rcvd_ieof(c);
2209
2210         /* XXX force input close */
2211         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2212                 debug("channel %d: FORCE input drain", c->self);
2213                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2214                 if (buffer_len(&c->input) == 0)
2215                         chan_ibuf_empty(c);
2216         }
2217
2218 }
2219
2220 /* ARGSUSED */
2221 void
2222 channel_input_close(int type, u_int32_t seq, void *ctxt)
2223 {
2224         int id;
2225         Channel *c;
2226
2227         id = packet_get_int();
2228         packet_check_eom();
2229         c = channel_lookup(id);
2230         if (c == NULL)
2231                 packet_disconnect("Received close for nonexistent channel %d.", id);
2232
2233         /*
2234          * Send a confirmation that we have closed the channel and no more
2235          * data is coming for it.
2236          */
2237         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2238         packet_put_int(c->remote_id);
2239         packet_send();
2240
2241         /*
2242          * If the channel is in closed state, we have sent a close request,
2243          * and the other side will eventually respond with a confirmation.
2244          * Thus, we cannot free the channel here, because then there would be
2245          * no-one to receive the confirmation.  The channel gets freed when
2246          * the confirmation arrives.
2247          */
2248         if (c->type != SSH_CHANNEL_CLOSED) {
2249                 /*
2250                  * Not a closed channel - mark it as draining, which will
2251                  * cause it to be freed later.
2252                  */
2253                 buffer_clear(&c->input);
2254                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2255         }
2256 }
2257
2258 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2259 /* ARGSUSED */
2260 void
2261 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2262 {
2263         int id = packet_get_int();
2264         Channel *c = channel_lookup(id);
2265
2266         packet_check_eom();
2267         if (c == NULL)
2268                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2269         chan_rcvd_oclose(c);
2270 }
2271
2272 /* ARGSUSED */
2273 void
2274 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2275 {
2276         int id = packet_get_int();
2277         Channel *c = channel_lookup(id);
2278
2279         packet_check_eom();
2280         if (c == NULL)
2281                 packet_disconnect("Received close confirmation for "
2282                     "out-of-range channel %d.", id);
2283         if (c->type != SSH_CHANNEL_CLOSED)
2284                 packet_disconnect("Received close confirmation for "
2285                     "non-closed channel %d (type %d).", id, c->type);
2286         channel_free(c);
2287 }
2288
2289 /* ARGSUSED */
2290 void
2291 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2292 {
2293         int id, remote_id;
2294         Channel *c;
2295
2296         id = packet_get_int();
2297         c = channel_lookup(id);
2298
2299         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2300                 packet_disconnect("Received open confirmation for "
2301                     "non-opening channel %d.", id);
2302         remote_id = packet_get_int();
2303         /* Record the remote channel number and mark that the channel is now open. */
2304         c->remote_id = remote_id;
2305         c->type = SSH_CHANNEL_OPEN;
2306
2307         if (compat20) {
2308                 c->remote_window = packet_get_int();
2309                 c->remote_maxpacket = packet_get_int();
2310                 if (c->open_confirm) {
2311                         debug2("callback start");
2312                         c->open_confirm(c->self, c->open_confirm_ctx);
2313                         debug2("callback done");
2314                 }
2315                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2316                     c->remote_window, c->remote_maxpacket);
2317         }
2318         packet_check_eom();
2319 }
2320
2321 static char *
2322 reason2txt(int reason)
2323 {
2324         switch (reason) {
2325         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2326                 return "administratively prohibited";
2327         case SSH2_OPEN_CONNECT_FAILED:
2328                 return "connect failed";
2329         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2330                 return "unknown channel type";
2331         case SSH2_OPEN_RESOURCE_SHORTAGE:
2332                 return "resource shortage";
2333         }
2334         return "unknown reason";
2335 }
2336
2337 /* ARGSUSED */
2338 void
2339 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2340 {
2341         int id, reason;
2342         char *msg = NULL, *lang = NULL;
2343         Channel *c;
2344
2345         id = packet_get_int();
2346         c = channel_lookup(id);
2347
2348         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2349                 packet_disconnect("Received open failure for "
2350                     "non-opening channel %d.", id);
2351         if (compat20) {
2352                 reason = packet_get_int();
2353                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2354                         msg  = packet_get_string(NULL);
2355                         lang = packet_get_string(NULL);
2356                 }
2357                 logit("channel %d: open failed: %s%s%s", id,
2358                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2359                 if (msg != NULL)
2360                         xfree(msg);
2361                 if (lang != NULL)
2362                         xfree(lang);
2363         }
2364         packet_check_eom();
2365         /* Schedule the channel for cleanup/deletion. */
2366         chan_mark_dead(c);
2367 }
2368
2369 /* ARGSUSED */
2370 void
2371 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2372 {
2373         Channel *c;
2374         int id;
2375         u_int adjust;
2376
2377         if (!compat20)
2378                 return;
2379
2380         /* Get the channel number and verify it. */
2381         id = packet_get_int();
2382         c = channel_lookup(id);
2383
2384         if (c == NULL) {
2385                 logit("Received window adjust for non-open channel %d.", id);
2386                 return;
2387         }
2388         adjust = packet_get_int();
2389         packet_check_eom();
2390         debug2("channel %d: rcvd adjust %u", id, adjust);
2391         c->remote_window += adjust;
2392 }
2393
2394 /* ARGSUSED */
2395 void
2396 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2397 {
2398         Channel *c = NULL;
2399         u_short host_port;
2400         char *host, *originator_string;
2401         int remote_id;
2402
2403         remote_id = packet_get_int();
2404         host = packet_get_string(NULL);
2405         host_port = packet_get_int();
2406
2407         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2408                 originator_string = packet_get_string(NULL);
2409         } else {
2410                 originator_string = xstrdup("unknown (remote did not supply name)");
2411         }
2412         packet_check_eom();
2413         c = channel_connect_to(host, host_port,
2414             "connected socket", originator_string);
2415         xfree(originator_string);
2416         xfree(host);
2417         if (c == NULL) {
2418                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2419                 packet_put_int(remote_id);
2420                 packet_send();
2421         } else
2422                 c->remote_id = remote_id;
2423 }
2424
2425 /* ARGSUSED */
2426 void
2427 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2428 {
2429         Channel *c;
2430         struct channel_confirm *cc;
2431         int id;
2432
2433         /* Reset keepalive timeout */
2434         keep_alive_timeouts = 0;
2435
2436         id = packet_get_int();
2437         packet_check_eom();
2438
2439         debug2("channel_input_status_confirm: type %d id %d", type, id);
2440
2441         if ((c = channel_lookup(id)) == NULL) {
2442                 logit("channel_input_status_confirm: %d: unknown", id);
2443                 return;
2444         }
2445         ;
2446         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2447                 return;
2448         cc->cb(type, c, cc->ctx);
2449         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2450         bzero(cc, sizeof(*cc));
2451         xfree(cc);
2452 }
2453
2454 /* -- tcp forwarding */
2455
2456 void
2457 channel_set_af(int af)
2458 {
2459         IPv4or6 = af;
2460 }
2461
2462 static int
2463 channel_setup_fwd_listener(int type, const char *listen_addr,
2464     u_short listen_port, int *allocated_listen_port,
2465     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2466 {
2467         Channel *c;
2468         int sock, r, success = 0, wildcard = 0, is_client;
2469         struct addrinfo hints, *ai, *aitop;
2470         const char *host, *addr;
2471         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2472         in_port_t *lport_p;
2473
2474         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2475             listen_addr : host_to_connect;
2476         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2477
2478         if (host == NULL) {
2479                 error("No forward host name.");
2480                 return 0;
2481         }
2482         if (strlen(host) >= NI_MAXHOST) {
2483                 error("Forward host name too long.");
2484                 return 0;
2485         }
2486
2487         /*
2488          * Determine whether or not a port forward listens to loopback,
2489          * specified address or wildcard. On the client, a specified bind
2490          * address will always override gateway_ports. On the server, a
2491          * gateway_ports of 1 (``yes'') will override the client's
2492          * specification and force a wildcard bind, whereas a value of 2
2493          * (``clientspecified'') will bind to whatever address the client
2494          * asked for.
2495          *
2496          * Special-case listen_addrs are:
2497          *
2498          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2499          * "" (empty string), "*"  -> wildcard v4/v6
2500          * "localhost"             -> loopback v4/v6
2501          */
2502         addr = NULL;
2503         if (listen_addr == NULL) {
2504                 /* No address specified: default to gateway_ports setting */
2505                 if (gateway_ports)
2506                         wildcard = 1;
2507         } else if (gateway_ports || is_client) {
2508                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2509                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2510                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2511                     (!is_client && gateway_ports == 1))
2512                         wildcard = 1;
2513                 else if (strcmp(listen_addr, "localhost") != 0)
2514                         addr = listen_addr;
2515         }
2516
2517         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2518             type, wildcard, (addr == NULL) ? "NULL" : addr);
2519
2520         /*
2521          * getaddrinfo returns a loopback address if the hostname is
2522          * set to NULL and hints.ai_flags is not AI_PASSIVE
2523          */
2524         memset(&hints, 0, sizeof(hints));
2525         hints.ai_family = IPv4or6;
2526         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2527         hints.ai_socktype = SOCK_STREAM;
2528         snprintf(strport, sizeof strport, "%d", listen_port);
2529         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2530                 if (addr == NULL) {
2531                         /* This really shouldn't happen */
2532                         packet_disconnect("getaddrinfo: fatal error: %s",
2533                             ssh_gai_strerror(r));
2534                 } else {
2535                         error("channel_setup_fwd_listener: "
2536                             "getaddrinfo(%.64s): %s", addr,
2537                             ssh_gai_strerror(r));
2538                 }
2539                 return 0;
2540         }
2541         if (allocated_listen_port != NULL)
2542                 *allocated_listen_port = 0;
2543         for (ai = aitop; ai; ai = ai->ai_next) {
2544                 switch (ai->ai_family) {
2545                 case AF_INET:
2546                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2547                             sin_port;
2548                         break;
2549                 case AF_INET6:
2550                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2551                             sin6_port;
2552                         break;
2553                 default:
2554                         continue;
2555                 }
2556                 /*
2557                  * If allocating a port for -R forwards, then use the
2558                  * same port for all address families.
2559                  */
2560                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2561                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2562                         *lport_p = htons(*allocated_listen_port);
2563
2564                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2565                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2566                         error("channel_setup_fwd_listener: getnameinfo failed");
2567                         continue;
2568                 }
2569                 /* Create a port to listen for the host. */
2570                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2571                 if (sock < 0) {
2572                         /* this is no error since kernel may not support ipv6 */
2573                         verbose("socket: %.100s", strerror(errno));
2574                         continue;
2575                 }
2576
2577                 channel_set_reuseaddr(sock);
2578
2579                 debug("Local forwarding listening on %s port %s.",
2580                     ntop, strport);
2581
2582                 /* Bind the socket to the address. */
2583                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2584                         /* address can be in use ipv6 address is already bound */
2585                         if (!ai->ai_next)
2586                                 error("bind: %.100s", strerror(errno));
2587                         else
2588                                 verbose("bind: %.100s", strerror(errno));
2589
2590                         close(sock);
2591                         continue;
2592                 }
2593                 /* Start listening for connections on the socket. */
2594                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2595                         error("listen: %.100s", strerror(errno));
2596                         close(sock);
2597                         continue;
2598                 }
2599
2600                 /*
2601                  * listen_port == 0 requests a dynamically allocated port -
2602                  * record what we got.
2603                  */
2604                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2605                     allocated_listen_port != NULL &&
2606                     *allocated_listen_port == 0) {
2607                         *allocated_listen_port = get_sock_port(sock, 1);
2608                         debug("Allocated listen port %d",
2609                             *allocated_listen_port);
2610                 }
2611
2612                 /* Allocate a channel number for the socket. */
2613                 c = channel_new("port listener", type, sock, sock, -1,
2614                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2615                     0, "port listener", 1);
2616                 c->path = xstrdup(host);
2617                 c->host_port = port_to_connect;
2618                 c->listening_port = listen_port;
2619                 success = 1;
2620         }
2621         if (success == 0)
2622                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2623                     listen_port);
2624         freeaddrinfo(aitop);
2625         return success;
2626 }
2627
2628 int
2629 channel_cancel_rport_listener(const char *host, u_short port)
2630 {
2631         u_int i;
2632         int found = 0;
2633
2634         for (i = 0; i < channels_alloc; i++) {
2635                 Channel *c = channels[i];
2636
2637                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2638                     strcmp(c->path, host) == 0 && c->listening_port == port) {
2639                         debug2("%s: close channel %d", __func__, i);
2640                         channel_free(c);
2641                         found = 1;
2642                 }
2643         }
2644
2645         return (found);
2646 }
2647
2648 /* protocol local port fwd, used by ssh (and sshd in v1) */
2649 int
2650 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2651     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2652 {
2653         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2654             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2655             gateway_ports);
2656 }
2657
2658 /* protocol v2 remote port fwd, used by sshd */
2659 int
2660 channel_setup_remote_fwd_listener(const char *listen_address,
2661     u_short listen_port, int *allocated_listen_port, int gateway_ports)
2662 {
2663         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2664             listen_address, listen_port, allocated_listen_port,
2665             NULL, 0, gateway_ports);
2666 }
2667
2668 /*
2669  * Initiate forwarding of connections to port "port" on remote host through
2670  * the secure channel to host:port from local side.
2671  */
2672
2673 int
2674 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2675     const char *host_to_connect, u_short port_to_connect)
2676 {
2677         int type, success = 0;
2678
2679         /* Record locally that connection to this host/port is permitted. */
2680         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2681                 fatal("channel_request_remote_forwarding: too many forwards");
2682
2683         /* Send the forward request to the remote side. */
2684         if (compat20) {
2685                 const char *address_to_bind;
2686                 if (listen_host == NULL) {
2687                         if (datafellows & SSH_BUG_RFWD_ADDR)
2688                                 address_to_bind = "127.0.0.1";
2689                         else
2690                                 address_to_bind = "localhost";
2691                 } else if (*listen_host == '\0' ||
2692                            strcmp(listen_host, "*") == 0) {
2693                         if (datafellows & SSH_BUG_RFWD_ADDR)
2694                                 address_to_bind = "0.0.0.0";
2695                         else
2696                                 address_to_bind = "";
2697                 } else
2698                         address_to_bind = listen_host;
2699
2700                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2701                 packet_put_cstring("tcpip-forward");
2702                 packet_put_char(1);                     /* boolean: want reply */
2703                 packet_put_cstring(address_to_bind);
2704                 packet_put_int(listen_port);
2705                 packet_send();
2706                 packet_write_wait();
2707                 /* Assume that server accepts the request */
2708                 success = 1;
2709         } else {
2710                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2711                 packet_put_int(listen_port);
2712                 packet_put_cstring(host_to_connect);
2713                 packet_put_int(port_to_connect);
2714                 packet_send();
2715                 packet_write_wait();
2716
2717                 /* Wait for response from the remote side. */
2718                 type = packet_read();
2719                 switch (type) {
2720                 case SSH_SMSG_SUCCESS:
2721                         success = 1;
2722                         break;
2723                 case SSH_SMSG_FAILURE:
2724                         break;
2725                 default:
2726                         /* Unknown packet */
2727                         packet_disconnect("Protocol error for port forward request:"
2728                             "received packet type %d.", type);
2729                 }
2730         }
2731         if (success) {
2732                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2733                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2734                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2735                 num_permitted_opens++;
2736         }
2737         return (success ? 0 : -1);
2738 }
2739
2740 /*
2741  * Request cancellation of remote forwarding of connection host:port from
2742  * local side.
2743  */
2744 void
2745 channel_request_rforward_cancel(const char *host, u_short port)
2746 {
2747         int i;
2748
2749         if (!compat20)
2750                 return;
2751
2752         for (i = 0; i < num_permitted_opens; i++) {
2753                 if (permitted_opens[i].host_to_connect != NULL &&
2754                     permitted_opens[i].listen_port == port)
2755                         break;
2756         }
2757         if (i >= num_permitted_opens) {
2758                 debug("%s: requested forward not found", __func__);
2759                 return;
2760         }
2761         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2762         packet_put_cstring("cancel-tcpip-forward");
2763         packet_put_char(0);
2764         packet_put_cstring(host == NULL ? "" : host);
2765         packet_put_int(port);
2766         packet_send();
2767
2768         permitted_opens[i].listen_port = 0;
2769         permitted_opens[i].port_to_connect = 0;
2770         xfree(permitted_opens[i].host_to_connect);
2771         permitted_opens[i].host_to_connect = NULL;
2772 }
2773
2774 /*
2775  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2776  * listening for the port, and sends back a success reply (or disconnect
2777  * message if there was an error).
2778  */
2779 int
2780 channel_input_port_forward_request(int is_root, int gateway_ports)
2781 {
2782         u_short port, host_port;
2783         int success = 0;
2784         char *hostname;
2785
2786         /* Get arguments from the packet. */
2787         port = packet_get_int();
2788         hostname = packet_get_string(NULL);
2789         host_port = packet_get_int();
2790
2791 #ifndef HAVE_CYGWIN
2792         /*
2793          * Check that an unprivileged user is not trying to forward a
2794          * privileged port.
2795          */
2796         if (port < IPPORT_RESERVED && !is_root)
2797                 packet_disconnect(
2798                     "Requested forwarding of port %d but user is not root.",
2799                     port);
2800         if (host_port == 0)
2801                 packet_disconnect("Dynamic forwarding denied.");
2802 #endif
2803
2804         /* Initiate forwarding */
2805         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2806             host_port, gateway_ports);
2807
2808         /* Free the argument string. */
2809         xfree(hostname);
2810
2811         return (success ? 0 : -1);
2812 }
2813
2814 /*
2815  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2816  * usually called by the server, because the user could connect to any port
2817  * anyway, and the server has no way to know but to trust the client anyway.
2818  */
2819 void
2820 channel_permit_all_opens(void)
2821 {
2822         if (num_permitted_opens == 0)
2823                 all_opens_permitted = 1;
2824 }
2825
2826 void
2827 channel_add_permitted_opens(char *host, int port)
2828 {
2829         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2830                 fatal("channel_add_permitted_opens: too many forwards");
2831         debug("allow port forwarding to host %s port %d", host, port);
2832
2833         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2834         permitted_opens[num_permitted_opens].port_to_connect = port;
2835         num_permitted_opens++;
2836
2837         all_opens_permitted = 0;
2838 }
2839
2840 int
2841 channel_add_adm_permitted_opens(char *host, int port)
2842 {
2843         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2844                 fatal("channel_add_adm_permitted_opens: too many forwards");
2845         debug("config allows port forwarding to host %s port %d", host, port);
2846
2847         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2848              = xstrdup(host);
2849         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2850         return ++num_adm_permitted_opens;
2851 }
2852
2853 void
2854 channel_clear_permitted_opens(void)
2855 {
2856         int i;
2857
2858         for (i = 0; i < num_permitted_opens; i++)
2859                 if (permitted_opens[i].host_to_connect != NULL)
2860                         xfree(permitted_opens[i].host_to_connect);
2861         num_permitted_opens = 0;
2862 }
2863
2864 void
2865 channel_clear_adm_permitted_opens(void)
2866 {
2867         int i;
2868
2869         for (i = 0; i < num_adm_permitted_opens; i++)
2870                 if (permitted_adm_opens[i].host_to_connect != NULL)
2871                         xfree(permitted_adm_opens[i].host_to_connect);
2872         num_adm_permitted_opens = 0;
2873 }
2874
2875 void
2876 channel_print_adm_permitted_opens(void)
2877 {
2878         int i;
2879
2880         printf("permitopen");
2881         if (num_adm_permitted_opens == 0) {
2882                 printf(" any\n");
2883                 return;
2884         }
2885         for (i = 0; i < num_adm_permitted_opens; i++)
2886                 if (permitted_adm_opens[i].host_to_connect != NULL)
2887                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
2888                             permitted_adm_opens[i].port_to_connect);
2889         printf("\n");
2890 }
2891
2892 /* Try to start non-blocking connect to next host in cctx list */
2893 static int
2894 connect_next(struct channel_connect *cctx)
2895 {
2896         int sock, saved_errno;
2897         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2898
2899         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
2900                 if (cctx->ai->ai_family != AF_INET &&
2901                     cctx->ai->ai_family != AF_INET6)
2902                         continue;
2903                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
2904                     ntop, sizeof(ntop), strport, sizeof(strport),
2905                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2906                         error("connect_next: getnameinfo failed");
2907                         continue;
2908                 }
2909                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
2910                     cctx->ai->ai_protocol)) == -1) {
2911                         if (cctx->ai->ai_next == NULL)
2912                                 error("socket: %.100s", strerror(errno));
2913                         else
2914                                 verbose("socket: %.100s", strerror(errno));
2915                         continue;
2916                 }
2917                 if (set_nonblock(sock) == -1)
2918                         fatal("%s: set_nonblock(%d)", __func__, sock);
2919                 if (connect(sock, cctx->ai->ai_addr,
2920                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
2921                         debug("connect_next: host %.100s ([%.100s]:%s): "
2922                             "%.100s", cctx->host, ntop, strport,
2923                             strerror(errno));
2924                         saved_errno = errno;
2925                         close(sock);
2926                         errno = saved_errno;
2927                         continue;       /* fail -- try next */
2928                 }
2929                 debug("connect_next: host %.100s ([%.100s]:%s) "
2930                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
2931                 cctx->ai = cctx->ai->ai_next;
2932                 set_nodelay(sock);
2933                 return sock;
2934         }
2935         return -1;
2936 }
2937
2938 static void
2939 channel_connect_ctx_free(struct channel_connect *cctx)
2940 {
2941         xfree(cctx->host);
2942         if (cctx->aitop)
2943                 freeaddrinfo(cctx->aitop);
2944         bzero(cctx, sizeof(*cctx));
2945         cctx->host = NULL;
2946         cctx->ai = cctx->aitop = NULL;
2947 }
2948
2949 /* Return CONNECTING channel to remote host, port */
2950 static Channel *
2951 connect_to(const char *host, u_short port, char *ctype, char *rname)
2952 {
2953         struct addrinfo hints;
2954         int gaierr;
2955         int sock = -1;
2956         char strport[NI_MAXSERV];
2957         struct channel_connect cctx;
2958         Channel *c;
2959
2960         memset(&cctx, 0, sizeof(cctx));
2961         memset(&hints, 0, sizeof(hints));
2962         hints.ai_family = IPv4or6;
2963         hints.ai_socktype = SOCK_STREAM;
2964         snprintf(strport, sizeof strport, "%d", port);
2965         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
2966                 error("connect_to %.100s: unknown host (%s)", host,
2967                     ssh_gai_strerror(gaierr));
2968                 return NULL;
2969         }
2970
2971         cctx.host = xstrdup(host);
2972         cctx.port = port;
2973         cctx.ai = cctx.aitop;
2974
2975         if ((sock = connect_next(&cctx)) == -1) {
2976                 error("connect to %.100s port %d failed: %s",
2977                     host, port, strerror(errno));
2978                 channel_connect_ctx_free(&cctx);
2979                 return NULL;
2980         }
2981         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
2982             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
2983         c->connect_ctx = cctx;
2984         return c;
2985 }
2986
2987 Channel *
2988 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
2989 {
2990         int i;
2991
2992         for (i = 0; i < num_permitted_opens; i++) {
2993                 if (permitted_opens[i].host_to_connect != NULL &&
2994                     permitted_opens[i].listen_port == listen_port) {
2995                         return connect_to(
2996                             permitted_opens[i].host_to_connect,
2997                             permitted_opens[i].port_to_connect, ctype, rname);
2998                 }
2999         }
3000         error("WARNING: Server requests forwarding for unknown listen_port %d",
3001             listen_port);
3002         return NULL;
3003 }
3004
3005 /* Check if connecting to that port is permitted and connect. */
3006 Channel *
3007 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3008 {
3009         int i, permit, permit_adm = 1;
3010
3011         permit = all_opens_permitted;
3012         if (!permit) {
3013                 for (i = 0; i < num_permitted_opens; i++)
3014                         if (permitted_opens[i].host_to_connect != NULL &&
3015                             permitted_opens[i].port_to_connect == port &&
3016                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3017                                 permit = 1;
3018         }
3019
3020         if (num_adm_permitted_opens > 0) {
3021                 permit_adm = 0;
3022                 for (i = 0; i < num_adm_permitted_opens; i++)
3023                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3024                             permitted_adm_opens[i].port_to_connect == port &&
3025                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3026                             == 0)
3027                                 permit_adm = 1;
3028         }
3029
3030         if (!permit || !permit_adm) {
3031                 logit("Received request to connect to host %.100s port %d, "
3032                     "but the request was denied.", host, port);
3033                 return NULL;
3034         }
3035         return connect_to(host, port, ctype, rname);
3036 }
3037
3038 void
3039 channel_send_window_changes(void)
3040 {
3041         u_int i;
3042         struct winsize ws;
3043
3044         for (i = 0; i < channels_alloc; i++) {
3045                 if (channels[i] == NULL || !channels[i]->client_tty ||
3046                     channels[i]->type != SSH_CHANNEL_OPEN)
3047                         continue;
3048                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3049                         continue;
3050                 channel_request_start(i, "window-change", 0);
3051                 packet_put_int((u_int)ws.ws_col);
3052                 packet_put_int((u_int)ws.ws_row);
3053                 packet_put_int((u_int)ws.ws_xpixel);
3054                 packet_put_int((u_int)ws.ws_ypixel);
3055                 packet_send();
3056         }
3057 }
3058
3059 /* -- X11 forwarding */
3060
3061 /*
3062  * Creates an internet domain socket for listening for X11 connections.
3063  * Returns 0 and a suitable display number for the DISPLAY variable
3064  * stored in display_numberp , or -1 if an error occurs.
3065  */
3066 int
3067 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3068     int single_connection, u_int *display_numberp, int **chanids)
3069 {
3070         Channel *nc = NULL;
3071         int display_number, sock;
3072         u_short port;
3073         struct addrinfo hints, *ai, *aitop;
3074         char strport[NI_MAXSERV];
3075         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3076
3077         if (chanids == NULL)
3078                 return -1;
3079
3080         for (display_number = x11_display_offset;
3081             display_number < MAX_DISPLAYS;
3082             display_number++) {
3083                 port = 6000 + display_number;
3084                 memset(&hints, 0, sizeof(hints));
3085                 hints.ai_family = IPv4or6;
3086                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3087                 hints.ai_socktype = SOCK_STREAM;
3088                 snprintf(strport, sizeof strport, "%d", port);
3089                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3090                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3091                         return -1;
3092                 }
3093                 for (ai = aitop; ai; ai = ai->ai_next) {
3094                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3095                                 continue;
3096                         sock = socket(ai->ai_family, ai->ai_socktype,
3097                             ai->ai_protocol);
3098                         if (sock < 0) {
3099                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3100                                         error("socket: %.100s", strerror(errno));
3101                                         freeaddrinfo(aitop);
3102                                         return -1;
3103                                 } else {
3104                                         debug("x11_create_display_inet: Socket family %d not supported",
3105                                                  ai->ai_family);
3106                                         continue;
3107                                 }
3108                         }
3109 #ifdef IPV6_V6ONLY
3110                         if (ai->ai_family == AF_INET6) {
3111                                 int on = 1;
3112                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
3113                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
3114                         }
3115 #endif
3116                         if (x11_use_localhost)
3117                                 channel_set_reuseaddr(sock);
3118                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3119                                 debug2("bind port %d: %.100s", port, strerror(errno));
3120                                 close(sock);
3121
3122                                 for (n = 0; n < num_socks; n++) {
3123                                         close(socks[n]);
3124                                 }
3125                                 num_socks = 0;
3126                                 break;
3127                         }
3128                         socks[num_socks++] = sock;
3129                         if (num_socks == NUM_SOCKS)
3130                                 break;
3131                 }
3132                 freeaddrinfo(aitop);
3133                 if (num_socks > 0)
3134                         break;
3135         }
3136         if (display_number >= MAX_DISPLAYS) {
3137                 error("Failed to allocate internet-domain X11 display socket.");
3138                 return -1;
3139         }
3140         /* Start listening for connections on the socket. */
3141         for (n = 0; n < num_socks; n++) {
3142                 sock = socks[n];
3143                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3144                         error("listen: %.100s", strerror(errno));
3145                         close(sock);
3146                         return -1;
3147                 }
3148         }
3149
3150         /* Allocate a channel for each socket. */
3151         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3152         for (n = 0; n < num_socks; n++) {
3153                 sock = socks[n];
3154                 nc = channel_new("x11 listener",
3155                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3156                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3157                     0, "X11 inet listener", 1);
3158                 nc->single_connection = single_connection;
3159                 (*chanids)[n] = nc->self;
3160         }
3161         (*chanids)[n] = -1;
3162
3163         /* Return the display number for the DISPLAY environment variable. */
3164         *display_numberp = display_number;
3165         return (0);
3166 }
3167
3168 static int
3169 connect_local_xsocket_path(const char *pathname)
3170 {
3171         int sock;
3172         struct sockaddr_un addr;
3173
3174         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3175         if (sock < 0)
3176                 error("socket: %.100s", strerror(errno));
3177         memset(&addr, 0, sizeof(addr));
3178         addr.sun_family = AF_UNIX;
3179         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3180         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3181                 return sock;
3182         close(sock);
3183         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3184         return -1;
3185 }
3186
3187 static int
3188 connect_local_xsocket(u_int dnr)
3189 {
3190         char buf[1024];
3191         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3192         return connect_local_xsocket_path(buf);
3193 }
3194
3195 int
3196 x11_connect_display(void)
3197 {
3198         u_int display_number;
3199         const char *display;
3200         char buf[1024], *cp;
3201         struct addrinfo hints, *ai, *aitop;
3202         char strport[NI_MAXSERV];
3203         int gaierr, sock = 0;
3204
3205         /* Try to open a socket for the local X server. */
3206         display = getenv("DISPLAY");
3207         if (!display) {
3208                 error("DISPLAY not set.");
3209                 return -1;
3210         }
3211         /*
3212          * Now we decode the value of the DISPLAY variable and make a
3213          * connection to the real X server.
3214          */
3215
3216         /* Check if the display is from launchd. */
3217 #ifdef __APPLE__
3218         if (strncmp(display, "/tmp/launch", 11) == 0) {
3219                 sock = connect_local_xsocket_path(display);
3220                 if (sock < 0)
3221                         return -1;
3222
3223                 /* OK, we now have a connection to the display. */
3224                 return sock;
3225         }
3226 #endif
3227         /*
3228          * Check if it is a unix domain socket.  Unix domain displays are in
3229          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3230          */
3231         if (strncmp(display, "unix:", 5) == 0 ||
3232             display[0] == ':') {
3233                 /* Connect to the unix domain socket. */
3234                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3235                         error("Could not parse display number from DISPLAY: %.100s",
3236                             display);
3237                         return -1;
3238                 }
3239                 /* Create a socket. */
3240                 sock = connect_local_xsocket(display_number);
3241                 if (sock < 0)
3242                         return -1;
3243
3244                 /* OK, we now have a connection to the display. */
3245                 return sock;
3246         }
3247         /*
3248          * Connect to an inet socket.  The DISPLAY value is supposedly
3249          * hostname:d[.s], where hostname may also be numeric IP address.
3250          */
3251         strlcpy(buf, display, sizeof(buf));
3252         cp = strchr(buf, ':');
3253         if (!cp) {
3254                 error("Could not find ':' in DISPLAY: %.100s", display);
3255                 return -1;
3256         }
3257         *cp = 0;
3258         /* buf now contains the host name.  But first we parse the display number. */
3259         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3260                 error("Could not parse display number from DISPLAY: %.100s",
3261                     display);
3262                 return -1;
3263         }
3264
3265         /* Look up the host address */
3266         memset(&hints, 0, sizeof(hints));
3267         hints.ai_family = IPv4or6;
3268         hints.ai_socktype = SOCK_STREAM;
3269         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3270         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3271                 error("%.100s: unknown host. (%s)", buf,
3272                 ssh_gai_strerror(gaierr));
3273                 return -1;
3274         }
3275         for (ai = aitop; ai; ai = ai->ai_next) {
3276                 /* Create a socket. */
3277                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3278                 if (sock < 0) {
3279                         debug2("socket: %.100s", strerror(errno));
3280                         continue;
3281                 }
3282                 /* Connect it to the display. */
3283                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3284                         debug2("connect %.100s port %u: %.100s", buf,
3285                             6000 + display_number, strerror(errno));
3286                         close(sock);
3287                         continue;
3288                 }
3289                 /* Success */
3290                 break;
3291         }
3292         freeaddrinfo(aitop);
3293         if (!ai) {
3294                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3295                     strerror(errno));
3296                 return -1;
3297         }
3298         set_nodelay(sock);
3299         return sock;
3300 }
3301
3302 /*
3303  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3304  * the remote channel number.  We should do whatever we want, and respond
3305  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3306  */
3307
3308 /* ARGSUSED */
3309 void
3310 x11_input_open(int type, u_int32_t seq, void *ctxt)
3311 {
3312         Channel *c = NULL;
3313         int remote_id, sock = 0;
3314         char *remote_host;
3315
3316         debug("Received X11 open request.");
3317
3318         remote_id = packet_get_int();
3319
3320         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3321                 remote_host = packet_get_string(NULL);
3322         } else {
3323                 remote_host = xstrdup("unknown (remote did not supply name)");
3324         }
3325         packet_check_eom();
3326
3327         /* Obtain a connection to the real X display. */
3328         sock = x11_connect_display();
3329         if (sock != -1) {
3330                 /* Allocate a channel for this connection. */
3331                 c = channel_new("connected x11 socket",
3332                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3333                     remote_host, 1);
3334                 c->remote_id = remote_id;
3335                 c->force_drain = 1;
3336         }
3337         xfree(remote_host);
3338         if (c == NULL) {
3339                 /* Send refusal to the remote host. */
3340                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3341                 packet_put_int(remote_id);
3342         } else {
3343                 /* Send a confirmation to the remote host. */
3344                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3345                 packet_put_int(remote_id);
3346                 packet_put_int(c->self);
3347         }
3348         packet_send();
3349 }
3350
3351 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3352 /* ARGSUSED */
3353 void
3354 deny_input_open(int type, u_int32_t seq, void *ctxt)
3355 {
3356         int rchan = packet_get_int();
3357
3358         switch (type) {
3359         case SSH_SMSG_AGENT_OPEN:
3360                 error("Warning: ssh server tried agent forwarding.");
3361                 break;
3362         case SSH_SMSG_X11_OPEN:
3363                 error("Warning: ssh server tried X11 forwarding.");
3364                 break;
3365         default:
3366                 error("deny_input_open: type %d", type);
3367                 break;
3368         }
3369         error("Warning: this is probably a break-in attempt by a malicious server.");
3370         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3371         packet_put_int(rchan);
3372         packet_send();
3373 }
3374
3375 /*
3376  * Requests forwarding of X11 connections, generates fake authentication
3377  * data, and enables authentication spoofing.
3378  * This should be called in the client only.
3379  */
3380 void
3381 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3382     const char *proto, const char *data)
3383 {
3384         u_int data_len = (u_int) strlen(data) / 2;
3385         u_int i, value;
3386         char *new_data;
3387         int screen_number;
3388         const char *cp;
3389         u_int32_t rnd = 0;
3390
3391         if (x11_saved_display == NULL)
3392                 x11_saved_display = xstrdup(disp);
3393         else if (strcmp(disp, x11_saved_display) != 0) {
3394                 error("x11_request_forwarding_with_spoofing: different "
3395                     "$DISPLAY already forwarded");
3396                 return;
3397         }
3398
3399         cp = strchr(disp, ':');
3400         if (cp)
3401                 cp = strchr(cp, '.');
3402         if (cp)
3403                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3404         else
3405                 screen_number = 0;
3406
3407         if (x11_saved_proto == NULL) {
3408                 /* Save protocol name. */
3409                 x11_saved_proto = xstrdup(proto);
3410                 /*
3411                  * Extract real authentication data and generate fake data
3412                  * of the same length.
3413                  */
3414                 x11_saved_data = xmalloc(data_len);
3415                 x11_fake_data = xmalloc(data_len);
3416                 for (i = 0; i < data_len; i++) {
3417                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3418                                 fatal("x11_request_forwarding: bad "
3419                                     "authentication data: %.100s", data);
3420                         if (i % 4 == 0)
3421                                 rnd = arc4random();
3422                         x11_saved_data[i] = value;
3423                         x11_fake_data[i] = rnd & 0xff;
3424                         rnd >>= 8;
3425                 }
3426                 x11_saved_data_len = data_len;
3427                 x11_fake_data_len = data_len;
3428         }
3429
3430         /* Convert the fake data into hex. */
3431         new_data = tohex(x11_fake_data, data_len);
3432
3433         /* Send the request packet. */
3434         if (compat20) {
3435                 channel_request_start(client_session_id, "x11-req", 0);
3436                 packet_put_char(0);     /* XXX bool single connection */
3437         } else {
3438                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3439         }
3440         packet_put_cstring(proto);
3441         packet_put_cstring(new_data);
3442         packet_put_int(screen_number);
3443         packet_send();
3444         packet_write_wait();
3445         xfree(new_data);
3446 }
3447
3448
3449 /* -- agent forwarding */
3450
3451 /* Sends a message to the server to request authentication fd forwarding. */
3452
3453 void
3454 auth_request_forwarding(void)
3455 {
3456         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3457         packet_send();
3458         packet_write_wait();
3459 }