crypto/openssh/channels.c

   1 /* $OpenBSD: channels.c,v 1.296 2009/05/25 06:48:00 andreas 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 #ifndef BROKEN_TCGETATTR_ICANON
1657                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1658                         if (tcgetattr(c->wfd, &tio) == 0 &&
1659                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1660                                 /*
1661                                  * Simulate echo to reduce the impact of
1662                                  * traffic analysis. We need to match the
1663                                  * size of a SSH2_MSG_CHANNEL_DATA message
1664                                  * (4 byte channel id + buf)
1665                                  */
1666                                 packet_send_ignore(4 + len);
1667                                 packet_send();
1668                         }
1669                 }
1670 #endif
1671                 buffer_consume(&c->output, len);
1672                 if (compat20 && len > 0) {
1673                         c->local_consumed += len;
1674                 }
1675         }
1676         return 1;
1677 }
1678
1679 static int
1680 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1681 {
1682         char buf[CHAN_RBUF];
1683         int len;
1684
1685 /** XXX handle drain efd, too */
1686         if (c->efd != -1) {
1687                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1688                     FD_ISSET(c->efd, writeset) &&
1689                     buffer_len(&c->extended) > 0) {
1690                         len = write(c->efd, buffer_ptr(&c->extended),
1691                             buffer_len(&c->extended));
1692                         debug2("channel %d: written %d to efd %d",
1693                             c->self, len, c->efd);
1694                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1695                             errno == EWOULDBLOCK))
1696                                 return 1;
1697                         if (len <= 0) {
1698                                 debug2("channel %d: closing write-efd %d",
1699                                     c->self, c->efd);
1700                                 channel_close_fd(&c->efd);
1701                         } else {
1702                                 buffer_consume(&c->extended, len);
1703                                 c->local_consumed += len;
1704                         }
1705                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1706                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1707                         len = read(c->efd, buf, sizeof(buf));
1708                         debug2("channel %d: read %d from efd %d",
1709                             c->self, len, c->efd);
1710                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1711                             errno == EWOULDBLOCK) && !c->detach_close)))
1712                                 return 1;
1713                         if (len <= 0) {
1714                                 debug2("channel %d: closing read-efd %d",
1715                                     c->self, c->efd);
1716                                 channel_close_fd(&c->efd);
1717                         } else {
1718                                 buffer_append(&c->extended, buf, len);
1719                         }
1720                 }
1721         }
1722         return 1;
1723 }
1724
1725 /* ARGSUSED */
1726 static int
1727 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1728 {
1729         char buf[16];
1730         int len;
1731
1732         /* Monitor control fd to detect if the slave client exits */
1733         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1734                 len = read(c->ctl_fd, buf, sizeof(buf));
1735                 if (len < 0 &&
1736                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1737                         return 1;
1738                 if (len <= 0) {
1739                         debug2("channel %d: ctl read<=0", c->self);
1740                         if (c->type != SSH_CHANNEL_OPEN) {
1741                                 debug2("channel %d: not open", c->self);
1742                                 chan_mark_dead(c);
1743                                 return -1;
1744                         } else {
1745                                 chan_read_failed(c);
1746                                 chan_write_failed(c);
1747                         }
1748                         return -1;
1749                 } else
1750                         fatal("%s: unexpected data on ctl fd", __func__);
1751         }
1752         return 1;
1753 }
1754
1755 static int
1756 channel_check_window(Channel *c)
1757 {
1758         if (c->type == SSH_CHANNEL_OPEN &&
1759             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1760             ((c->local_window_max - c->local_window >
1761             c->local_maxpacket*3) ||
1762             c->local_window < c->local_window_max/2) &&
1763             c->local_consumed > 0) {
1764                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1765                 packet_put_int(c->remote_id);
1766                 packet_put_int(c->local_consumed);
1767                 packet_send();
1768                 debug2("channel %d: window %d sent adjust %d",
1769                     c->self, c->local_window,
1770                     c->local_consumed);
1771                 c->local_window += c->local_consumed;
1772                 c->local_consumed = 0;
1773         }
1774         return 1;
1775 }
1776
1777 static void
1778 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1779 {
1780         if (c->delayed)
1781                 return;
1782         channel_handle_rfd(c, readset, writeset);
1783         channel_handle_wfd(c, readset, writeset);
1784         if (!compat20)
1785                 return;
1786         channel_handle_efd(c, readset, writeset);
1787         channel_handle_ctl(c, readset, writeset);
1788         channel_check_window(c);
1789 }
1790
1791 /* ARGSUSED */
1792 static void
1793 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1794 {
1795         int len;
1796
1797         /* Send buffered output data to the socket. */
1798         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1799                 len = write(c->sock, buffer_ptr(&c->output),
1800                             buffer_len(&c->output));
1801                 if (len <= 0)
1802                         buffer_clear(&c->output);
1803                 else
1804                         buffer_consume(&c->output, len);
1805         }
1806 }
1807
1808 static void
1809 channel_handler_init_20(void)
1810 {
1811         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1812         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1813         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1814         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1815         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1816         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1817         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1818         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1819
1820         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1821         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1822         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1823         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1824         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1825         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1826         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1827 }
1828
1829 static void
1830 channel_handler_init_13(void)
1831 {
1832         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1833         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1834         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1835         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1836         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1837         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1838         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1839         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1840         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1841
1842         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1843         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1844         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1845         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1846         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1847         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1848         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1849 }
1850
1851 static void
1852 channel_handler_init_15(void)
1853 {
1854         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1855         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1856         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1857         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1858         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1859         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1860         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1861
1862         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1863         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1864         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1865         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1866         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1867         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1868 }
1869
1870 static void
1871 channel_handler_init(void)
1872 {
1873         int i;
1874
1875         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1876                 channel_pre[i] = NULL;
1877                 channel_post[i] = NULL;
1878         }
1879         if (compat20)
1880                 channel_handler_init_20();
1881         else if (compat13)
1882                 channel_handler_init_13();
1883         else
1884                 channel_handler_init_15();
1885 }
1886
1887 /* gc dead channels */
1888 static void
1889 channel_garbage_collect(Channel *c)
1890 {
1891         if (c == NULL)
1892                 return;
1893         if (c->detach_user != NULL) {
1894                 if (!chan_is_dead(c, c->detach_close))
1895                         return;
1896                 debug2("channel %d: gc: notify user", c->self);
1897                 c->detach_user(c->self, NULL);
1898                 /* if we still have a callback */
1899                 if (c->detach_user != NULL)
1900                         return;
1901                 debug2("channel %d: gc: user detached", c->self);
1902         }
1903         if (!chan_is_dead(c, 1))
1904                 return;
1905         debug2("channel %d: garbage collecting", c->self);
1906         channel_free(c);
1907 }
1908
1909 static void
1910 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1911 {
1912         static int did_init = 0;
1913         u_int i;
1914         Channel *c;
1915
1916         if (!did_init) {
1917                 channel_handler_init();
1918                 did_init = 1;
1919         }
1920         for (i = 0; i < channels_alloc; i++) {
1921                 c = channels[i];
1922                 if (c == NULL)
1923                         continue;
1924                 if (ftab[c->type] != NULL)
1925                         (*ftab[c->type])(c, readset, writeset);
1926                 channel_garbage_collect(c);
1927         }
1928 }
1929
1930 /*
1931  * Allocate/update select bitmasks and add any bits relevant to channels in
1932  * select bitmasks.
1933  */
1934 void
1935 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1936     u_int *nallocp, int rekeying)
1937 {
1938         u_int n, sz, nfdset;
1939
1940         n = MAX(*maxfdp, channel_max_fd);
1941
1942         nfdset = howmany(n+1, NFDBITS);
1943         /* Explicitly test here, because xrealloc isn't always called */
1944         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1945                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1946         sz = nfdset * sizeof(fd_mask);
1947
1948         /* perhaps check sz < nalloc/2 and shrink? */
1949         if (*readsetp == NULL || sz > *nallocp) {
1950                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1951                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1952                 *nallocp = sz;
1953         }
1954         *maxfdp = n;
1955         memset(*readsetp, 0, sz);
1956         memset(*writesetp, 0, sz);
1957
1958         if (!rekeying)
1959                 channel_handler(channel_pre, *readsetp, *writesetp);
1960 }
1961
1962 /*
1963  * After select, perform any appropriate operations for channels which have
1964  * events pending.
1965  */
1966 void
1967 channel_after_select(fd_set *readset, fd_set *writeset)
1968 {
1969         channel_handler(channel_post, readset, writeset);
1970 }
1971
1972
1973 /* If there is data to send to the connection, enqueue some of it now. */
1974 void
1975 channel_output_poll(void)
1976 {
1977         Channel *c;
1978         u_int i, len;
1979
1980         for (i = 0; i < channels_alloc; i++) {
1981                 c = channels[i];
1982                 if (c == NULL)
1983                         continue;
1984
1985                 /*
1986                  * We are only interested in channels that can have buffered
1987                  * incoming data.
1988                  */
1989                 if (compat13) {
1990                         if (c->type != SSH_CHANNEL_OPEN &&
1991                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1992                                 continue;
1993                 } else {
1994                         if (c->type != SSH_CHANNEL_OPEN)
1995                                 continue;
1996                 }
1997                 if (compat20 &&
1998                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1999                         /* XXX is this true? */
2000                         debug3("channel %d: will not send data after close", c->self);
2001                         continue;
2002                 }
2003
2004                 /* Get the amount of buffered data for this channel. */
2005                 if ((c->istate == CHAN_INPUT_OPEN ||
2006                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2007                     (len = buffer_len(&c->input)) > 0) {
2008                         if (c->datagram) {
2009                                 if (len > 0) {
2010                                         u_char *data;
2011                                         u_int dlen;
2012
2013                                         data = buffer_get_string(&c->input,
2014                                             &dlen);
2015                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2016                                         packet_put_int(c->remote_id);
2017                                         packet_put_string(data, dlen);
2018                                         packet_send();
2019                                         c->remote_window -= dlen + 4;
2020                                         xfree(data);
2021                                 }
2022                                 continue;
2023                         }
2024                         /*
2025                          * Send some data for the other side over the secure
2026                          * connection.
2027                          */
2028                         if (compat20) {
2029                                 if (len > c->remote_window)
2030                                         len = c->remote_window;
2031                                 if (len > c->remote_maxpacket)
2032                                         len = c->remote_maxpacket;
2033                         } else {
2034                                 if (packet_is_interactive()) {
2035                                         if (len > 1024)
2036                                                 len = 512;
2037                                 } else {
2038                                         /* Keep the packets at reasonable size. */
2039                                         if (len > packet_get_maxsize()/2)
2040                                                 len = packet_get_maxsize()/2;
2041                                 }
2042                         }
2043                         if (len > 0) {
2044                                 packet_start(compat20 ?
2045                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2046                                 packet_put_int(c->remote_id);
2047                                 packet_put_string(buffer_ptr(&c->input), len);
2048                                 packet_send();
2049                                 buffer_consume(&c->input, len);
2050                                 c->remote_window -= len;
2051                         }
2052                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2053                         if (compat13)
2054                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2055                         /*
2056                          * input-buffer is empty and read-socket shutdown:
2057                          * tell peer, that we will not send more data: send IEOF.
2058                          * hack for extended data: delay EOF if EFD still in use.
2059                          */
2060                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2061                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2062                                     c->self, c->efd, buffer_len(&c->extended));
2063                         else
2064                                 chan_ibuf_empty(c);
2065                 }
2066                 /* Send extended data, i.e. stderr */
2067                 if (compat20 &&
2068                     !(c->flags & CHAN_EOF_SENT) &&
2069                     c->remote_window > 0 &&
2070                     (len = buffer_len(&c->extended)) > 0 &&
2071                     c->extended_usage == CHAN_EXTENDED_READ) {
2072                         debug2("channel %d: rwin %u elen %u euse %d",
2073                             c->self, c->remote_window, buffer_len(&c->extended),
2074                             c->extended_usage);
2075                         if (len > c->remote_window)
2076                                 len = c->remote_window;
2077                         if (len > c->remote_maxpacket)
2078                                 len = c->remote_maxpacket;
2079                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2080                         packet_put_int(c->remote_id);
2081                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2082                         packet_put_string(buffer_ptr(&c->extended), len);
2083                         packet_send();
2084                         buffer_consume(&c->extended, len);
2085                         c->remote_window -= len;
2086                         debug2("channel %d: sent ext data %d", c->self, len);
2087                 }
2088         }
2089 }
2090
2091
2092 /* -- protocol input */
2093
2094 /* ARGSUSED */
2095 void
2096 channel_input_data(int type, u_int32_t seq, void *ctxt)
2097 {
2098         int id;
2099         char *data;
2100         u_int data_len;
2101         Channel *c;
2102
2103         /* Get the channel number and verify it. */
2104         id = packet_get_int();
2105         c = channel_lookup(id);
2106         if (c == NULL)
2107                 packet_disconnect("Received data for nonexistent channel %d.", id);
2108
2109         /* Ignore any data for non-open channels (might happen on close) */
2110         if (c->type != SSH_CHANNEL_OPEN &&
2111             c->type != SSH_CHANNEL_X11_OPEN)
2112                 return;
2113
2114         /* Get the data. */
2115         data = packet_get_string_ptr(&data_len);
2116
2117         /*
2118          * Ignore data for protocol > 1.3 if output end is no longer open.
2119          * For protocol 2 the sending side is reducing its window as it sends
2120          * data, so we must 'fake' consumption of the data in order to ensure
2121          * that window updates are sent back.  Otherwise the connection might
2122          * deadlock.
2123          */
2124         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2125                 if (compat20) {
2126                         c->local_window -= data_len;
2127                         c->local_consumed += data_len;
2128                 }
2129                 return;
2130         }
2131
2132         if (compat20) {
2133                 if (data_len > c->local_maxpacket) {
2134                         logit("channel %d: rcvd big packet %d, maxpack %d",
2135                             c->self, data_len, c->local_maxpacket);
2136                 }
2137                 if (data_len > c->local_window) {
2138                         logit("channel %d: rcvd too much data %d, win %d",
2139                             c->self, data_len, c->local_window);
2140                         return;
2141                 }
2142                 c->local_window -= data_len;
2143         }
2144         if (c->datagram)
2145                 buffer_put_string(&c->output, data, data_len);
2146         else
2147                 buffer_append(&c->output, data, data_len);
2148         packet_check_eom();
2149 }
2150
2151 /* ARGSUSED */
2152 void
2153 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2154 {
2155         int id;
2156         char *data;
2157         u_int data_len, tcode;
2158         Channel *c;
2159
2160         /* Get the channel number and verify it. */
2161         id = packet_get_int();
2162         c = channel_lookup(id);
2163
2164         if (c == NULL)
2165                 packet_disconnect("Received extended_data for bad channel %d.", id);
2166         if (c->type != SSH_CHANNEL_OPEN) {
2167                 logit("channel %d: ext data for non open", id);
2168                 return;
2169         }
2170         if (c->flags & CHAN_EOF_RCVD) {
2171                 if (datafellows & SSH_BUG_EXTEOF)
2172                         debug("channel %d: accepting ext data after eof", id);
2173                 else
2174                         packet_disconnect("Received extended_data after EOF "
2175                             "on channel %d.", id);
2176         }
2177         tcode = packet_get_int();
2178         if (c->efd == -1 ||
2179             c->extended_usage != CHAN_EXTENDED_WRITE ||
2180             tcode != SSH2_EXTENDED_DATA_STDERR) {
2181                 logit("channel %d: bad ext data", c->self);
2182                 return;
2183         }
2184         data = packet_get_string(&data_len);
2185         packet_check_eom();
2186         if (data_len > c->local_window) {
2187                 logit("channel %d: rcvd too much extended_data %d, win %d",
2188                     c->self, data_len, c->local_window);
2189                 xfree(data);
2190                 return;
2191         }
2192         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2193         c->local_window -= data_len;
2194         buffer_append(&c->extended, data, data_len);
2195         xfree(data);
2196 }
2197
2198 /* ARGSUSED */
2199 void
2200 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2201 {
2202         int id;
2203         Channel *c;
2204
2205         id = packet_get_int();
2206         packet_check_eom();
2207         c = channel_lookup(id);
2208         if (c == NULL)
2209                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2210         chan_rcvd_ieof(c);
2211
2212         /* XXX force input close */
2213         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2214                 debug("channel %d: FORCE input drain", c->self);
2215                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2216                 if (buffer_len(&c->input) == 0)
2217                         chan_ibuf_empty(c);
2218         }
2219
2220 }
2221
2222 /* ARGSUSED */
2223 void
2224 channel_input_close(int type, u_int32_t seq, void *ctxt)
2225 {
2226         int id;
2227         Channel *c;
2228
2229         id = packet_get_int();
2230         packet_check_eom();
2231         c = channel_lookup(id);
2232         if (c == NULL)
2233                 packet_disconnect("Received close for nonexistent channel %d.", id);
2234
2235         /*
2236          * Send a confirmation that we have closed the channel and no more
2237          * data is coming for it.
2238          */
2239         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2240         packet_put_int(c->remote_id);
2241         packet_send();
2242
2243         /*
2244          * If the channel is in closed state, we have sent a close request,
2245          * and the other side will eventually respond with a confirmation.
2246          * Thus, we cannot free the channel here, because then there would be
2247          * no-one to receive the confirmation.  The channel gets freed when
2248          * the confirmation arrives.
2249          */
2250         if (c->type != SSH_CHANNEL_CLOSED) {
2251                 /*
2252                  * Not a closed channel - mark it as draining, which will
2253                  * cause it to be freed later.
2254                  */
2255                 buffer_clear(&c->input);
2256                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2257         }
2258 }
2259
2260 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2261 /* ARGSUSED */
2262 void
2263 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2264 {
2265         int id = packet_get_int();
2266         Channel *c = channel_lookup(id);
2267
2268         packet_check_eom();
2269         if (c == NULL)
2270                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2271         chan_rcvd_oclose(c);
2272 }
2273
2274 /* ARGSUSED */
2275 void
2276 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2277 {
2278         int id = packet_get_int();
2279         Channel *c = channel_lookup(id);
2280
2281         packet_check_eom();
2282         if (c == NULL)
2283                 packet_disconnect("Received close confirmation for "
2284                     "out-of-range channel %d.", id);
2285         if (c->type != SSH_CHANNEL_CLOSED)
2286                 packet_disconnect("Received close confirmation for "
2287                     "non-closed channel %d (type %d).", id, c->type);
2288         channel_free(c);
2289 }
2290
2291 /* ARGSUSED */
2292 void
2293 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2294 {
2295         int id, remote_id;
2296         Channel *c;
2297
2298         id = packet_get_int();
2299         c = channel_lookup(id);
2300
2301         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2302                 packet_disconnect("Received open confirmation for "
2303                     "non-opening channel %d.", id);
2304         remote_id = packet_get_int();
2305         /* Record the remote channel number and mark that the channel is now open. */
2306         c->remote_id = remote_id;
2307         c->type = SSH_CHANNEL_OPEN;
2308
2309         if (compat20) {
2310                 c->remote_window = packet_get_int();
2311                 c->remote_maxpacket = packet_get_int();
2312                 if (c->open_confirm) {
2313                         debug2("callback start");
2314                         c->open_confirm(c->self, c->open_confirm_ctx);
2315                         debug2("callback done");
2316                 }
2317                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2318                     c->remote_window, c->remote_maxpacket);
2319         }
2320         packet_check_eom();
2321 }
2322
2323 static char *
2324 reason2txt(int reason)
2325 {
2326         switch (reason) {
2327         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2328                 return "administratively prohibited";
2329         case SSH2_OPEN_CONNECT_FAILED:
2330                 return "connect failed";
2331         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2332                 return "unknown channel type";
2333         case SSH2_OPEN_RESOURCE_SHORTAGE:
2334                 return "resource shortage";
2335         }
2336         return "unknown reason";
2337 }
2338
2339 /* ARGSUSED */
2340 void
2341 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2342 {
2343         int id, reason;
2344         char *msg = NULL, *lang = NULL;
2345         Channel *c;
2346
2347         id = packet_get_int();
2348         c = channel_lookup(id);
2349
2350         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2351                 packet_disconnect("Received open failure for "
2352                     "non-opening channel %d.", id);
2353         if (compat20) {
2354                 reason = packet_get_int();
2355                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2356                         msg  = packet_get_string(NULL);
2357                         lang = packet_get_string(NULL);
2358                 }
2359                 logit("channel %d: open failed: %s%s%s", id,
2360                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2361                 if (msg != NULL)
2362                         xfree(msg);
2363                 if (lang != NULL)
2364                         xfree(lang);
2365         }
2366         packet_check_eom();
2367         /* Schedule the channel for cleanup/deletion. */
2368         chan_mark_dead(c);
2369 }
2370
2371 /* ARGSUSED */
2372 void
2373 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2374 {
2375         Channel *c;
2376         int id;
2377         u_int adjust;
2378
2379         if (!compat20)
2380                 return;
2381
2382         /* Get the channel number and verify it. */
2383         id = packet_get_int();
2384         c = channel_lookup(id);
2385
2386         if (c == NULL) {
2387                 logit("Received window adjust for non-open channel %d.", id);
2388                 return;
2389         }
2390         adjust = packet_get_int();
2391         packet_check_eom();
2392         debug2("channel %d: rcvd adjust %u", id, adjust);
2393         c->remote_window += adjust;
2394 }
2395
2396 /* ARGSUSED */
2397 void
2398 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2399 {
2400         Channel *c = NULL;
2401         u_short host_port;
2402         char *host, *originator_string;
2403         int remote_id;
2404
2405         remote_id = packet_get_int();
2406         host = packet_get_string(NULL);
2407         host_port = packet_get_int();
2408
2409         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2410                 originator_string = packet_get_string(NULL);
2411         } else {
2412                 originator_string = xstrdup("unknown (remote did not supply name)");
2413         }
2414         packet_check_eom();
2415         c = channel_connect_to(host, host_port,
2416             "connected socket", originator_string);
2417         xfree(originator_string);
2418         xfree(host);
2419         if (c == NULL) {
2420                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2421                 packet_put_int(remote_id);
2422                 packet_send();
2423         } else
2424                 c->remote_id = remote_id;
2425 }
2426
2427 /* ARGSUSED */
2428 void
2429 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2430 {
2431         Channel *c;
2432         struct channel_confirm *cc;
2433         int id;
2434
2435         /* Reset keepalive timeout */
2436         packet_set_alive_timeouts(0);
2437
2438         id = packet_get_int();
2439         packet_check_eom();
2440
2441         debug2("channel_input_status_confirm: type %d id %d", type, id);
2442
2443         if ((c = channel_lookup(id)) == NULL) {
2444                 logit("channel_input_status_confirm: %d: unknown", id);
2445                 return;
2446         }
2447         ;
2448         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2449                 return;
2450         cc->cb(type, c, cc->ctx);
2451         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2452         bzero(cc, sizeof(*cc));
2453         xfree(cc);
2454 }
2455
2456 /* -- tcp forwarding */
2457
2458 void
2459 channel_set_af(int af)
2460 {
2461         IPv4or6 = af;
2462 }
2463
2464 static int
2465 channel_setup_fwd_listener(int type, const char *listen_addr,
2466     u_short listen_port, int *allocated_listen_port,
2467     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2468 {
2469         Channel *c;
2470         int sock, r, success = 0, wildcard = 0, is_client;
2471         struct addrinfo hints, *ai, *aitop;
2472         const char *host, *addr;
2473         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2474         in_port_t *lport_p;
2475
2476         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2477             listen_addr : host_to_connect;
2478         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2479
2480         if (host == NULL) {
2481                 error("No forward host name.");
2482                 return 0;
2483         }
2484         if (strlen(host) >= NI_MAXHOST) {
2485                 error("Forward host name too long.");
2486                 return 0;
2487         }
2488
2489         /*
2490          * Determine whether or not a port forward listens to loopback,
2491          * specified address or wildcard. On the client, a specified bind
2492          * address will always override gateway_ports. On the server, a
2493          * gateway_ports of 1 (``yes'') will override the client's
2494          * specification and force a wildcard bind, whereas a value of 2
2495          * (``clientspecified'') will bind to whatever address the client
2496          * asked for.
2497          *
2498          * Special-case listen_addrs are:
2499          *
2500          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2501          * "" (empty string), "*"  -> wildcard v4/v6
2502          * "localhost"             -> loopback v4/v6
2503          */
2504         addr = NULL;
2505         if (listen_addr == NULL) {
2506                 /* No address specified: default to gateway_ports setting */
2507                 if (gateway_ports)
2508                         wildcard = 1;
2509         } else if (gateway_ports || is_client) {
2510                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2511                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2512                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2513                     (!is_client && gateway_ports == 1))
2514                         wildcard = 1;
2515                 else if (strcmp(listen_addr, "localhost") != 0)
2516                         addr = listen_addr;
2517         }
2518
2519         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2520             type, wildcard, (addr == NULL) ? "NULL" : addr);
2521
2522         /*
2523          * getaddrinfo returns a loopback address if the hostname is
2524          * set to NULL and hints.ai_flags is not AI_PASSIVE
2525          */
2526         memset(&hints, 0, sizeof(hints));
2527         hints.ai_family = IPv4or6;
2528         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2529         hints.ai_socktype = SOCK_STREAM;
2530         snprintf(strport, sizeof strport, "%d", listen_port);
2531         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2532                 if (addr == NULL) {
2533                         /* This really shouldn't happen */
2534                         packet_disconnect("getaddrinfo: fatal error: %s",
2535                             ssh_gai_strerror(r));
2536                 } else {
2537                         error("channel_setup_fwd_listener: "
2538                             "getaddrinfo(%.64s): %s", addr,
2539                             ssh_gai_strerror(r));
2540                 }
2541                 return 0;
2542         }
2543         if (allocated_listen_port != NULL)
2544                 *allocated_listen_port = 0;
2545         for (ai = aitop; ai; ai = ai->ai_next) {
2546                 switch (ai->ai_family) {
2547                 case AF_INET:
2548                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2549                             sin_port;
2550                         break;
2551                 case AF_INET6:
2552                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2553                             sin6_port;
2554                         break;
2555                 default:
2556                         continue;
2557                 }
2558                 /*
2559                  * If allocating a port for -R forwards, then use the
2560                  * same port for all address families.
2561                  */
2562                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2563                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2564                         *lport_p = htons(*allocated_listen_port);
2565
2566                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2567                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2568                         error("channel_setup_fwd_listener: getnameinfo failed");
2569                         continue;
2570                 }
2571                 /* Create a port to listen for the host. */
2572                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2573                 if (sock < 0) {
2574                         /* this is no error since kernel may not support ipv6 */
2575                         verbose("socket: %.100s", strerror(errno));
2576                         continue;
2577                 }
2578
2579                 channel_set_reuseaddr(sock);
2580
2581                 debug("Local forwarding listening on %s port %s.",
2582                     ntop, strport);
2583
2584                 /* Bind the socket to the address. */
2585                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2586                         /* address can be in use ipv6 address is already bound */
2587                         if (!ai->ai_next)
2588                                 error("bind: %.100s", strerror(errno));
2589                         else
2590                                 verbose("bind: %.100s", strerror(errno));
2591
2592                         close(sock);
2593                         continue;
2594                 }
2595                 /* Start listening for connections on the socket. */
2596                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2597                         error("listen: %.100s", strerror(errno));
2598                         close(sock);
2599                         continue;
2600                 }
2601
2602                 /*
2603                  * listen_port == 0 requests a dynamically allocated port -
2604                  * record what we got.
2605                  */
2606                 if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
2607                     allocated_listen_port != NULL &&
2608                     *allocated_listen_port == 0) {
2609                         *allocated_listen_port = get_sock_port(sock, 1);
2610                         debug("Allocated listen port %d",
2611                             *allocated_listen_port);
2612                 }
2613
2614                 /* Allocate a channel number for the socket. */
2615                 c = channel_new("port listener", type, sock, sock, -1,
2616                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2617                     0, "port listener", 1);
2618                 c->path = xstrdup(host);
2619                 c->host_port = port_to_connect;
2620                 c->listening_port = listen_port;
2621                 success = 1;
2622         }
2623         if (success == 0)
2624                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2625                     listen_port);
2626         freeaddrinfo(aitop);
2627         return success;
2628 }
2629
2630 int
2631 channel_cancel_rport_listener(const char *host, u_short port)
2632 {
2633         u_int i;
2634         int found = 0;
2635
2636         for (i = 0; i < channels_alloc; i++) {
2637                 Channel *c = channels[i];
2638
2639                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2640                     strcmp(c->path, host) == 0 && c->listening_port == port) {
2641                         debug2("%s: close channel %d", __func__, i);
2642                         channel_free(c);
2643                         found = 1;
2644                 }
2645         }
2646
2647         return (found);
2648 }
2649
2650 /* protocol local port fwd, used by ssh (and sshd in v1) */
2651 int
2652 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2653     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2654 {
2655         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2656             listen_host, listen_port, NULL, host_to_connect, port_to_connect,
2657             gateway_ports);
2658 }
2659
2660 /* protocol v2 remote port fwd, used by sshd */
2661 int
2662 channel_setup_remote_fwd_listener(const char *listen_address,
2663     u_short listen_port, int *allocated_listen_port, int gateway_ports)
2664 {
2665         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2666             listen_address, listen_port, allocated_listen_port,
2667             NULL, 0, gateway_ports);
2668 }
2669
2670 /*
2671  * Initiate forwarding of connections to port "port" on remote host through
2672  * the secure channel to host:port from local side.
2673  */
2674
2675 int
2676 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2677     const char *host_to_connect, u_short port_to_connect)
2678 {
2679         int type, success = 0;
2680
2681         /* Record locally that connection to this host/port is permitted. */
2682         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2683                 fatal("channel_request_remote_forwarding: too many forwards");
2684
2685         /* Send the forward request to the remote side. */
2686         if (compat20) {
2687                 const char *address_to_bind;
2688                 if (listen_host == NULL) {
2689                         if (datafellows & SSH_BUG_RFWD_ADDR)
2690                                 address_to_bind = "127.0.0.1";
2691                         else
2692                                 address_to_bind = "localhost";
2693                 } else if (*listen_host == '\0' ||
2694                            strcmp(listen_host, "*") == 0) {
2695                         if (datafellows & SSH_BUG_RFWD_ADDR)
2696                                 address_to_bind = "0.0.0.0";
2697                         else
2698                                 address_to_bind = "";
2699                 } else
2700                         address_to_bind = listen_host;
2701
2702                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2703                 packet_put_cstring("tcpip-forward");
2704                 packet_put_char(1);                     /* boolean: want reply */
2705                 packet_put_cstring(address_to_bind);
2706                 packet_put_int(listen_port);
2707                 packet_send();
2708                 packet_write_wait();
2709                 /* Assume that server accepts the request */
2710                 success = 1;
2711         } else {
2712                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2713                 packet_put_int(listen_port);
2714                 packet_put_cstring(host_to_connect);
2715                 packet_put_int(port_to_connect);
2716                 packet_send();
2717                 packet_write_wait();
2718
2719                 /* Wait for response from the remote side. */
2720                 type = packet_read();
2721                 switch (type) {
2722                 case SSH_SMSG_SUCCESS:
2723                         success = 1;
2724                         break;
2725                 case SSH_SMSG_FAILURE:
2726                         break;
2727                 default:
2728                         /* Unknown packet */
2729                         packet_disconnect("Protocol error for port forward request:"
2730                             "received packet type %d.", type);
2731                 }
2732         }
2733         if (success) {
2734                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2735                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2736                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2737                 num_permitted_opens++;
2738         }
2739         return (success ? 0 : -1);
2740 }
2741
2742 /*
2743  * Request cancellation of remote forwarding of connection host:port from
2744  * local side.
2745  */
2746 void
2747 channel_request_rforward_cancel(const char *host, u_short port)
2748 {
2749         int i;
2750
2751         if (!compat20)
2752                 return;
2753
2754         for (i = 0; i < num_permitted_opens; i++) {
2755                 if (permitted_opens[i].host_to_connect != NULL &&
2756                     permitted_opens[i].listen_port == port)
2757                         break;
2758         }
2759         if (i >= num_permitted_opens) {
2760                 debug("%s: requested forward not found", __func__);
2761                 return;
2762         }
2763         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2764         packet_put_cstring("cancel-tcpip-forward");
2765         packet_put_char(0);
2766         packet_put_cstring(host == NULL ? "" : host);
2767         packet_put_int(port);
2768         packet_send();
2769
2770         permitted_opens[i].listen_port = 0;
2771         permitted_opens[i].port_to_connect = 0;
2772         xfree(permitted_opens[i].host_to_connect);
2773         permitted_opens[i].host_to_connect = NULL;
2774 }
2775
2776 /*
2777  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2778  * listening for the port, and sends back a success reply (or disconnect
2779  * message if there was an error).
2780  */
2781 int
2782 channel_input_port_forward_request(int is_root, int gateway_ports)
2783 {
2784         u_short port, host_port;
2785         int success = 0;
2786         char *hostname;
2787
2788         /* Get arguments from the packet. */
2789         port = packet_get_int();
2790         hostname = packet_get_string(NULL);
2791         host_port = packet_get_int();
2792
2793 #ifndef HAVE_CYGWIN
2794         /*
2795          * Check that an unprivileged user is not trying to forward a
2796          * privileged port.
2797          */
2798         if (port < IPPORT_RESERVED && !is_root)
2799                 packet_disconnect(
2800                     "Requested forwarding of port %d but user is not root.",
2801                     port);
2802         if (host_port == 0)
2803                 packet_disconnect("Dynamic forwarding denied.");
2804 #endif
2805
2806         /* Initiate forwarding */
2807         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2808             host_port, gateway_ports);
2809
2810         /* Free the argument string. */
2811         xfree(hostname);
2812
2813         return (success ? 0 : -1);
2814 }
2815
2816 /*
2817  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2818  * usually called by the server, because the user could connect to any port
2819  * anyway, and the server has no way to know but to trust the client anyway.
2820  */
2821 void
2822 channel_permit_all_opens(void)
2823 {
2824         if (num_permitted_opens == 0)
2825                 all_opens_permitted = 1;
2826 }
2827
2828 void
2829 channel_add_permitted_opens(char *host, int port)
2830 {
2831         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2832                 fatal("channel_add_permitted_opens: too many forwards");
2833         debug("allow port forwarding to host %s port %d", host, port);
2834
2835         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2836         permitted_opens[num_permitted_opens].port_to_connect = port;
2837         num_permitted_opens++;
2838
2839         all_opens_permitted = 0;
2840 }
2841
2842 int
2843 channel_add_adm_permitted_opens(char *host, int port)
2844 {
2845         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2846                 fatal("channel_add_adm_permitted_opens: too many forwards");
2847         debug("config allows port forwarding to host %s port %d", host, port);
2848
2849         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2850              = xstrdup(host);
2851         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2852         return ++num_adm_permitted_opens;
2853 }
2854
2855 void
2856 channel_clear_permitted_opens(void)
2857 {
2858         int i;
2859
2860         for (i = 0; i < num_permitted_opens; i++)
2861                 if (permitted_opens[i].host_to_connect != NULL)
2862                         xfree(permitted_opens[i].host_to_connect);
2863         num_permitted_opens = 0;
2864 }
2865
2866 void
2867 channel_clear_adm_permitted_opens(void)
2868 {
2869         int i;
2870
2871         for (i = 0; i < num_adm_permitted_opens; i++)
2872                 if (permitted_adm_opens[i].host_to_connect != NULL)
2873                         xfree(permitted_adm_opens[i].host_to_connect);
2874         num_adm_permitted_opens = 0;
2875 }
2876
2877 void
2878 channel_print_adm_permitted_opens(void)
2879 {
2880         int i;
2881
2882         printf("permitopen");
2883         if (num_adm_permitted_opens == 0) {
2884                 printf(" any\n");
2885                 return;
2886         }
2887         for (i = 0; i < num_adm_permitted_opens; i++)
2888                 if (permitted_adm_opens[i].host_to_connect != NULL)
2889                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
2890                             permitted_adm_opens[i].port_to_connect);
2891         printf("\n");
2892 }
2893
2894 /* Try to start non-blocking connect to next host in cctx list */
2895 static int
2896 connect_next(struct channel_connect *cctx)
2897 {
2898         int sock, saved_errno;
2899         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2900
2901         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
2902                 if (cctx->ai->ai_family != AF_INET &&
2903                     cctx->ai->ai_family != AF_INET6)
2904                         continue;
2905                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
2906                     ntop, sizeof(ntop), strport, sizeof(strport),
2907                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2908                         error("connect_next: getnameinfo failed");
2909                         continue;
2910                 }
2911                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
2912                     cctx->ai->ai_protocol)) == -1) {
2913                         if (cctx->ai->ai_next == NULL)
2914                                 error("socket: %.100s", strerror(errno));
2915                         else
2916                                 verbose("socket: %.100s", strerror(errno));
2917                         continue;
2918                 }
2919                 if (set_nonblock(sock) == -1)
2920                         fatal("%s: set_nonblock(%d)", __func__, sock);
2921                 if (connect(sock, cctx->ai->ai_addr,
2922                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
2923                         debug("connect_next: host %.100s ([%.100s]:%s): "
2924                             "%.100s", cctx->host, ntop, strport,
2925                             strerror(errno));
2926                         saved_errno = errno;
2927                         close(sock);
2928                         errno = saved_errno;
2929                         continue;       /* fail -- try next */
2930                 }
2931                 debug("connect_next: host %.100s ([%.100s]:%s) "
2932                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
2933                 cctx->ai = cctx->ai->ai_next;
2934                 set_nodelay(sock);
2935                 return sock;
2936         }
2937         return -1;
2938 }
2939
2940 static void
2941 channel_connect_ctx_free(struct channel_connect *cctx)
2942 {
2943         xfree(cctx->host);
2944         if (cctx->aitop)
2945                 freeaddrinfo(cctx->aitop);
2946         bzero(cctx, sizeof(*cctx));
2947         cctx->host = NULL;
2948         cctx->ai = cctx->aitop = NULL;
2949 }
2950
2951 /* Return CONNECTING channel to remote host, port */
2952 static Channel *
2953 connect_to(const char *host, u_short port, char *ctype, char *rname)
2954 {
2955         struct addrinfo hints;
2956         int gaierr;
2957         int sock = -1;
2958         char strport[NI_MAXSERV];
2959         struct channel_connect cctx;
2960         Channel *c;
2961
2962         memset(&cctx, 0, sizeof(cctx));
2963         memset(&hints, 0, sizeof(hints));
2964         hints.ai_family = IPv4or6;
2965         hints.ai_socktype = SOCK_STREAM;
2966         snprintf(strport, sizeof strport, "%d", port);
2967         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
2968                 error("connect_to %.100s: unknown host (%s)", host,
2969                     ssh_gai_strerror(gaierr));
2970                 return NULL;
2971         }
2972
2973         cctx.host = xstrdup(host);
2974         cctx.port = port;
2975         cctx.ai = cctx.aitop;
2976
2977         if ((sock = connect_next(&cctx)) == -1) {
2978                 error("connect to %.100s port %d failed: %s",
2979                     host, port, strerror(errno));
2980                 channel_connect_ctx_free(&cctx);
2981                 return NULL;
2982         }
2983         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
2984             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
2985         c->connect_ctx = cctx;
2986         return c;
2987 }
2988
2989 Channel *
2990 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
2991 {
2992         int i;
2993
2994         for (i = 0; i < num_permitted_opens; i++) {
2995                 if (permitted_opens[i].host_to_connect != NULL &&
2996                     permitted_opens[i].listen_port == listen_port) {
2997                         return connect_to(
2998                             permitted_opens[i].host_to_connect,
2999                             permitted_opens[i].port_to_connect, ctype, rname);
3000                 }
3001         }
3002         error("WARNING: Server requests forwarding for unknown listen_port %d",
3003             listen_port);
3004         return NULL;
3005 }
3006
3007 /* Check if connecting to that port is permitted and connect. */
3008 Channel *
3009 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
3010 {
3011         int i, permit, permit_adm = 1;
3012
3013         permit = all_opens_permitted;
3014         if (!permit) {
3015                 for (i = 0; i < num_permitted_opens; i++)
3016                         if (permitted_opens[i].host_to_connect != NULL &&
3017                             permitted_opens[i].port_to_connect == port &&
3018                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
3019                                 permit = 1;
3020         }
3021
3022         if (num_adm_permitted_opens > 0) {
3023                 permit_adm = 0;
3024                 for (i = 0; i < num_adm_permitted_opens; i++)
3025                         if (permitted_adm_opens[i].host_to_connect != NULL &&
3026                             permitted_adm_opens[i].port_to_connect == port &&
3027                             strcmp(permitted_adm_opens[i].host_to_connect, host)
3028                             == 0)
3029                                 permit_adm = 1;
3030         }
3031
3032         if (!permit || !permit_adm) {
3033                 logit("Received request to connect to host %.100s port %d, "
3034                     "but the request was denied.", host, port);
3035                 return NULL;
3036         }
3037         return connect_to(host, port, ctype, rname);
3038 }
3039
3040 void
3041 channel_send_window_changes(void)
3042 {
3043         u_int i;
3044         struct winsize ws;
3045
3046         for (i = 0; i < channels_alloc; i++) {
3047                 if (channels[i] == NULL || !channels[i]->client_tty ||
3048                     channels[i]->type != SSH_CHANNEL_OPEN)
3049                         continue;
3050                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3051                         continue;
3052                 channel_request_start(i, "window-change", 0);
3053                 packet_put_int((u_int)ws.ws_col);
3054                 packet_put_int((u_int)ws.ws_row);
3055                 packet_put_int((u_int)ws.ws_xpixel);
3056                 packet_put_int((u_int)ws.ws_ypixel);
3057                 packet_send();
3058         }
3059 }
3060
3061 /* -- X11 forwarding */
3062
3063 /*
3064  * Creates an internet domain socket for listening for X11 connections.
3065  * Returns 0 and a suitable display number for the DISPLAY variable
3066  * stored in display_numberp , or -1 if an error occurs.
3067  */
3068 int
3069 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3070     int single_connection, u_int *display_numberp, int **chanids)
3071 {
3072         Channel *nc = NULL;
3073         int display_number, sock;
3074         u_short port;
3075         struct addrinfo hints, *ai, *aitop;
3076         char strport[NI_MAXSERV];
3077         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3078
3079         if (chanids == NULL)
3080                 return -1;
3081
3082         for (display_number = x11_display_offset;
3083             display_number < MAX_DISPLAYS;
3084             display_number++) {
3085                 port = 6000 + display_number;
3086                 memset(&hints, 0, sizeof(hints));
3087                 hints.ai_family = IPv4or6;
3088                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3089                 hints.ai_socktype = SOCK_STREAM;
3090                 snprintf(strport, sizeof strport, "%d", port);
3091                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3092                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3093                         return -1;
3094                 }
3095                 for (ai = aitop; ai; ai = ai->ai_next) {
3096                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3097                                 continue;
3098                         sock = socket(ai->ai_family, ai->ai_socktype,
3099                             ai->ai_protocol);
3100                         if (sock < 0) {
3101                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3102                                         error("socket: %.100s", strerror(errno));
3103                                         freeaddrinfo(aitop);
3104                                         return -1;
3105                                 } else {
3106                                         debug("x11_create_display_inet: Socket family %d not supported",
3107                                                  ai->ai_family);
3108                                         continue;
3109                                 }
3110                         }
3111 #ifdef IPV6_V6ONLY
3112                         if (ai->ai_family == AF_INET6) {
3113                                 int on = 1;
3114                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
3115                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
3116                         }
3117 #endif
3118                         if (x11_use_localhost)
3119                                 channel_set_reuseaddr(sock);
3120                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3121                                 debug2("bind port %d: %.100s", port, strerror(errno));
3122                                 close(sock);
3123
3124                                 for (n = 0; n < num_socks; n++) {
3125                                         close(socks[n]);
3126                                 }
3127                                 num_socks = 0;
3128                                 break;
3129                         }
3130                         socks[num_socks++] = sock;
3131                         if (num_socks == NUM_SOCKS)
3132                                 break;
3133                 }
3134                 freeaddrinfo(aitop);
3135                 if (num_socks > 0)
3136                         break;
3137         }
3138         if (display_number >= MAX_DISPLAYS) {
3139                 error("Failed to allocate internet-domain X11 display socket.");
3140                 return -1;
3141         }
3142         /* Start listening for connections on the socket. */
3143         for (n = 0; n < num_socks; n++) {
3144                 sock = socks[n];
3145                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3146                         error("listen: %.100s", strerror(errno));
3147                         close(sock);
3148                         return -1;
3149                 }
3150         }
3151
3152         /* Allocate a channel for each socket. */
3153         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3154         for (n = 0; n < num_socks; n++) {
3155                 sock = socks[n];
3156                 nc = channel_new("x11 listener",
3157                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3158                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3159                     0, "X11 inet listener", 1);
3160                 nc->single_connection = single_connection;
3161                 (*chanids)[n] = nc->self;
3162         }
3163         (*chanids)[n] = -1;
3164
3165         /* Return the display number for the DISPLAY environment variable. */
3166         *display_numberp = display_number;
3167         return (0);
3168 }
3169
3170 static int
3171 connect_local_xsocket_path(const char *pathname)
3172 {
3173         int sock;
3174         struct sockaddr_un addr;
3175
3176         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3177         if (sock < 0)
3178                 error("socket: %.100s", strerror(errno));
3179         memset(&addr, 0, sizeof(addr));
3180         addr.sun_family = AF_UNIX;
3181         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3182         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3183                 return sock;
3184         close(sock);
3185         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3186         return -1;
3187 }
3188
3189 static int
3190 connect_local_xsocket(u_int dnr)
3191 {
3192         char buf[1024];
3193         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3194         return connect_local_xsocket_path(buf);
3195 }
3196
3197 int
3198 x11_connect_display(void)
3199 {
3200         u_int display_number;
3201         const char *display;
3202         char buf[1024], *cp;
3203         struct addrinfo hints, *ai, *aitop;
3204         char strport[NI_MAXSERV];
3205         int gaierr, sock = 0;
3206
3207         /* Try to open a socket for the local X server. */
3208         display = getenv("DISPLAY");
3209         if (!display) {
3210                 error("DISPLAY not set.");
3211                 return -1;
3212         }
3213         /*
3214          * Now we decode the value of the DISPLAY variable and make a
3215          * connection to the real X server.
3216          */
3217
3218         /* Check if the display is from launchd. */
3219 #ifdef __APPLE__
3220         if (strncmp(display, "/tmp/launch", 11) == 0) {
3221                 sock = connect_local_xsocket_path(display);
3222                 if (sock < 0)
3223                         return -1;
3224
3225                 /* OK, we now have a connection to the display. */
3226                 return sock;
3227         }
3228 #endif
3229         /*
3230          * Check if it is a unix domain socket.  Unix domain displays are in
3231          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3232          */
3233         if (strncmp(display, "unix:", 5) == 0 ||
3234             display[0] == ':') {
3235                 /* Connect to the unix domain socket. */
3236                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3237                         error("Could not parse display number from DISPLAY: %.100s",
3238                             display);
3239                         return -1;
3240                 }
3241                 /* Create a socket. */
3242                 sock = connect_local_xsocket(display_number);
3243                 if (sock < 0)
3244                         return -1;
3245
3246                 /* OK, we now have a connection to the display. */
3247                 return sock;
3248         }
3249         /*
3250          * Connect to an inet socket.  The DISPLAY value is supposedly
3251          * hostname:d[.s], where hostname may also be numeric IP address.
3252          */
3253         strlcpy(buf, display, sizeof(buf));
3254         cp = strchr(buf, ':');
3255         if (!cp) {
3256                 error("Could not find ':' in DISPLAY: %.100s", display);
3257                 return -1;
3258         }
3259         *cp = 0;
3260         /* buf now contains the host name.  But first we parse the display number. */
3261         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3262                 error("Could not parse display number from DISPLAY: %.100s",
3263                     display);
3264                 return -1;
3265         }
3266
3267         /* Look up the host address */
3268         memset(&hints, 0, sizeof(hints));
3269         hints.ai_family = IPv4or6;
3270         hints.ai_socktype = SOCK_STREAM;
3271         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3272         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3273                 error("%.100s: unknown host. (%s)", buf,
3274                 ssh_gai_strerror(gaierr));
3275                 return -1;
3276         }
3277         for (ai = aitop; ai; ai = ai->ai_next) {
3278                 /* Create a socket. */
3279                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3280                 if (sock < 0) {
3281                         debug2("socket: %.100s", strerror(errno));
3282                         continue;
3283                 }
3284                 /* Connect it to the display. */
3285                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3286                         debug2("connect %.100s port %u: %.100s", buf,
3287                             6000 + display_number, strerror(errno));
3288                         close(sock);
3289                         continue;
3290                 }
3291                 /* Success */
3292                 break;
3293         }
3294         freeaddrinfo(aitop);
3295         if (!ai) {
3296                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3297                     strerror(errno));
3298                 return -1;
3299         }
3300         set_nodelay(sock);
3301         return sock;
3302 }
3303
3304 /*
3305  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3306  * the remote channel number.  We should do whatever we want, and respond
3307  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3308  */
3309
3310 /* ARGSUSED */
3311 void
3312 x11_input_open(int type, u_int32_t seq, void *ctxt)
3313 {
3314         Channel *c = NULL;
3315         int remote_id, sock = 0;
3316         char *remote_host;
3317
3318         debug("Received X11 open request.");
3319
3320         remote_id = packet_get_int();
3321
3322         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3323                 remote_host = packet_get_string(NULL);
3324         } else {
3325                 remote_host = xstrdup("unknown (remote did not supply name)");
3326         }
3327         packet_check_eom();
3328
3329         /* Obtain a connection to the real X display. */
3330         sock = x11_connect_display();
3331         if (sock != -1) {
3332                 /* Allocate a channel for this connection. */
3333                 c = channel_new("connected x11 socket",
3334                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3335                     remote_host, 1);
3336                 c->remote_id = remote_id;
3337                 c->force_drain = 1;
3338         }
3339         xfree(remote_host);
3340         if (c == NULL) {
3341                 /* Send refusal to the remote host. */
3342                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3343                 packet_put_int(remote_id);
3344         } else {
3345                 /* Send a confirmation to the remote host. */
3346                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3347                 packet_put_int(remote_id);
3348                 packet_put_int(c->self);
3349         }
3350         packet_send();
3351 }
3352
3353 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3354 /* ARGSUSED */
3355 void
3356 deny_input_open(int type, u_int32_t seq, void *ctxt)
3357 {
3358         int rchan = packet_get_int();
3359
3360         switch (type) {
3361         case SSH_SMSG_AGENT_OPEN:
3362                 error("Warning: ssh server tried agent forwarding.");
3363                 break;
3364         case SSH_SMSG_X11_OPEN:
3365                 error("Warning: ssh server tried X11 forwarding.");
3366                 break;
3367         default:
3368                 error("deny_input_open: type %d", type);
3369                 break;
3370         }
3371         error("Warning: this is probably a break-in attempt by a malicious server.");
3372         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3373         packet_put_int(rchan);
3374         packet_send();
3375 }
3376
3377 /*
3378  * Requests forwarding of X11 connections, generates fake authentication
3379  * data, and enables authentication spoofing.
3380  * This should be called in the client only.
3381  */
3382 void
3383 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3384     const char *proto, const char *data)
3385 {
3386         u_int data_len = (u_int) strlen(data) / 2;
3387         u_int i, value;
3388         char *new_data;
3389         int screen_number;
3390         const char *cp;
3391         u_int32_t rnd = 0;
3392
3393         if (x11_saved_display == NULL)
3394                 x11_saved_display = xstrdup(disp);
3395         else if (strcmp(disp, x11_saved_display) != 0) {
3396                 error("x11_request_forwarding_with_spoofing: different "
3397                     "$DISPLAY already forwarded");
3398                 return;
3399         }
3400
3401         cp = strchr(disp, ':');
3402         if (cp)
3403                 cp = strchr(cp, '.');
3404         if (cp)
3405                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3406         else
3407                 screen_number = 0;
3408
3409         if (x11_saved_proto == NULL) {
3410                 /* Save protocol name. */
3411                 x11_saved_proto = xstrdup(proto);
3412                 /*
3413                  * Extract real authentication data and generate fake data
3414                  * of the same length.
3415                  */
3416                 x11_saved_data = xmalloc(data_len);
3417                 x11_fake_data = xmalloc(data_len);
3418                 for (i = 0; i < data_len; i++) {
3419                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3420                                 fatal("x11_request_forwarding: bad "
3421                                     "authentication data: %.100s", data);
3422                         if (i % 4 == 0)
3423                                 rnd = arc4random();
3424                         x11_saved_data[i] = value;
3425                         x11_fake_data[i] = rnd & 0xff;
3426                         rnd >>= 8;
3427                 }
3428                 x11_saved_data_len = data_len;
3429                 x11_fake_data_len = data_len;
3430         }
3431
3432         /* Convert the fake data into hex. */
3433         new_data = tohex(x11_fake_data, data_len);
3434
3435         /* Send the request packet. */
3436         if (compat20) {
3437                 channel_request_start(client_session_id, "x11-req", 0);
3438                 packet_put_char(0);     /* XXX bool single connection */
3439         } else {
3440                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3441         }
3442         packet_put_cstring(proto);
3443         packet_put_cstring(new_data);
3444         packet_put_int(screen_number);
3445         packet_send();
3446         packet_write_wait();
3447         xfree(new_data);
3448 }
3449
3450
3451 /* -- agent forwarding */
3452
3453 /* Sends a message to the server to request authentication fd forwarding. */
3454
3455 void
3456 auth_request_forwarding(void)
3457 {
3458         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3459         packet_send();
3460         packet_write_wait();
3461 }