channels.c

   1 /* $OpenBSD: channels.c,v 1.292 2009/01/14 01:38:06 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains functions for generic socket connection forwarding.
   7  * There is also code for initiating connection forwarding for X11 connections,
   8  * arbitrary tcp/ip connections, and the authentication agent connection.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * SSH2 support added by Markus Friedl.
  17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  18  * Copyright (c) 1999 Dug Song.  All rights reserved.
  19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/un.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_TIME_H
  49 # include <sys/time.h>
  50 #endif
  51
  52 #include <netinet/in.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <netdb.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <termios.h>
  61 #include <unistd.h>
  62 #include <stdarg.h>
  63
  64 #include "openbsd-compat/sys-queue.h"
  65 #include "xmalloc.h"
  66 #include "ssh.h"
  67 #include "ssh1.h"
  68 #include "ssh2.h"
  69 #include "packet.h"
  70 #include "log.h"
  71 #include "misc.h"
  72 #include "buffer.h"
  73 #include "channels.h"
  74 #include "compat.h"
  75 #include "canohost.h"
  76 #include "key.h"
  77 #include "authfd.h"
  78 #include "pathnames.h"
  79
  80 /* -- channel core */
  81
  82 /*
  83  * Pointer to an array containing all allocated channels.  The array is
  84  * dynamically extended as needed.
  85  */
  86 static Channel **channels = NULL;
  87
  88 /*
  89  * Size of the channel array.  All slots of the array must always be
  90  * initialized (at least the type field); unused slots set to NULL
  91  */
  92 static u_int channels_alloc = 0;
  93
  94 /*
  95  * Maximum file descriptor value used in any of the channels.  This is
  96  * updated in channel_new.
  97  */
  98 static int channel_max_fd = 0;
  99
 100
 101 /* -- tcp forwarding */
 102
 103 /*
 104  * Data structure for storing which hosts are permitted for forward requests.
 105  * The local sides of any remote forwards are stored in this array to prevent
 106  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 107  * network (which might be behind a firewall).
 108  */
 109 typedef struct {
 110         char *host_to_connect;          /* Connect to 'host'. */
 111         u_short port_to_connect;        /* Connect to 'port'. */
 112         u_short listen_port;            /* Remote side should listen port number. */
 113 } ForwardPermission;
 114
 115 /* List of all permitted host/port pairs to connect by the user. */
 116 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 117
 118 /* List of all permitted host/port pairs to connect by the admin. */
 119 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
 120
 121 /* Number of permitted host/port pairs in the array permitted by the user. */
 122 static int num_permitted_opens = 0;
 123
 124 /* Number of permitted host/port pair in the array permitted by the admin. */
 125 static int num_adm_permitted_opens = 0;
 126
 127 /*
 128  * If this is true, all opens are permitted.  This is the case on the server
 129  * on which we have to trust the client anyway, and the user could do
 130  * anything after logging in anyway.
 131  */
 132 static int all_opens_permitted = 0;
 133
 134
 135 /* -- X11 forwarding */
 136
 137 /* Maximum number of fake X11 displays to try. */
 138 #define MAX_DISPLAYS  1000
 139
 140 /* Saved X11 local (client) display. */
 141 static char *x11_saved_display = NULL;
 142
 143 /* Saved X11 authentication protocol name. */
 144 static char *x11_saved_proto = NULL;
 145
 146 /* Saved X11 authentication data.  This is the real data. */
 147 static char *x11_saved_data = NULL;
 148 static u_int x11_saved_data_len = 0;
 149
 150 /*
 151  * Fake X11 authentication data.  This is what the server will be sending us;
 152  * we should replace any occurrences of this by the real data.
 153  */
 154 static u_char *x11_fake_data = NULL;
 155 static u_int x11_fake_data_len;
 156
 157
 158 /* -- agent forwarding */
 159
 160 #define NUM_SOCKS       10
 161
 162 /* AF_UNSPEC or AF_INET or AF_INET6 */
 163 static int IPv4or6 = AF_UNSPEC;
 164
 165 /* helper */
 166 static void port_open_helper(Channel *c, char *rtype);
 167
 168 /* non-blocking connect helpers */
 169 static int connect_next(struct channel_connect *);
 170 static void channel_connect_ctx_free(struct channel_connect *);
 171
 172 /* -- channel core */
 173
 174 Channel *
 175 channel_by_id(int id)
 176 {
 177         Channel *c;
 178
 179         if (id < 0 || (u_int)id >= channels_alloc) {
 180                 logit("channel_by_id: %d: bad id", id);
 181                 return NULL;
 182         }
 183         c = channels[id];
 184         if (c == NULL) {
 185                 logit("channel_by_id: %d: bad id: channel free", id);
 186                 return NULL;
 187         }
 188         return c;
 189 }
 190
 191 /*
 192  * Returns the channel if it is allowed to receive protocol messages.
 193  * Private channels, like listening sockets, may not receive messages.
 194  */
 195 Channel *
 196 channel_lookup(int id)
 197 {
 198         Channel *c;
 199
 200         if ((c = channel_by_id(id)) == NULL)
 201                 return (NULL);
 202
 203         switch (c->type) {
 204         case SSH_CHANNEL_X11_OPEN:
 205         case SSH_CHANNEL_LARVAL:
 206         case SSH_CHANNEL_CONNECTING:
 207         case SSH_CHANNEL_DYNAMIC:
 208         case SSH_CHANNEL_OPENING:
 209         case SSH_CHANNEL_OPEN:
 210         case SSH_CHANNEL_INPUT_DRAINING:
 211         case SSH_CHANNEL_OUTPUT_DRAINING:
 212                 return (c);
 213         }
 214         logit("Non-public channel %d, type %d.", id, c->type);
 215         return (NULL);
 216 }
 217
 218 /*
 219  * Register filedescriptors for a channel, used when allocating a channel or
 220  * when the channel consumer/producer is ready, e.g. shell exec'd
 221  */
 222 static void
 223 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 224     int extusage, int nonblock, int is_tty)
 225 {
 226         /* Update the maximum file descriptor value. */
 227         channel_max_fd = MAX(channel_max_fd, rfd);
 228         channel_max_fd = MAX(channel_max_fd, wfd);
 229         channel_max_fd = MAX(channel_max_fd, efd);
 230
 231         /* XXX set close-on-exec -markus */
 232
 233         c->rfd = rfd;
 234         c->wfd = wfd;
 235         c->sock = (rfd == wfd) ? rfd : -1;
 236         c->ctl_fd = -1; /* XXX: set elsewhere */
 237         c->efd = efd;
 238         c->extended_usage = extusage;
 239
 240         if ((c->isatty = is_tty) != 0)
 241                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 242         c->wfd_isatty = is_tty || isatty(c->wfd);
 243
 244         /* enable nonblocking mode */
 245         if (nonblock) {
 246                 if (rfd != -1)
 247                         set_nonblock(rfd);
 248                 if (wfd != -1)
 249                         set_nonblock(wfd);
 250                 if (efd != -1)
 251                         set_nonblock(efd);
 252         }
 253 }
 254
 255 /*
 256  * Allocate a new channel object and set its type and socket. This will cause
 257  * remote_name to be freed.
 258  */
 259 Channel *
 260 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 261     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 262 {
 263         int found;
 264         u_int i;
 265         Channel *c;
 266
 267         /* Do initial allocation if this is the first call. */
 268         if (channels_alloc == 0) {
 269                 channels_alloc = 10;
 270                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 271                 for (i = 0; i < channels_alloc; i++)
 272                         channels[i] = NULL;
 273         }
 274         /* Try to find a free slot where to put the new channel. */
 275         for (found = -1, i = 0; i < channels_alloc; i++)
 276                 if (channels[i] == NULL) {
 277                         /* Found a free slot. */
 278                         found = (int)i;
 279                         break;
 280                 }
 281         if (found < 0) {
 282                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 283                 found = channels_alloc;
 284                 if (channels_alloc > 10000)
 285                         fatal("channel_new: internal error: channels_alloc %d "
 286                             "too big.", channels_alloc);
 287                 channels = xrealloc(channels, channels_alloc + 10,
 288                     sizeof(Channel *));
 289                 channels_alloc += 10;
 290                 debug2("channel: expanding %d", channels_alloc);
 291                 for (i = found; i < channels_alloc; i++)
 292                         channels[i] = NULL;
 293         }
 294         /* Initialize and return new channel. */
 295         c = channels[found] = xcalloc(1, sizeof(Channel));
 296         buffer_init(&c->input);
 297         buffer_init(&c->output);
 298         buffer_init(&c->extended);
 299         c->ostate = CHAN_OUTPUT_OPEN;
 300         c->istate = CHAN_INPUT_OPEN;
 301         c->flags = 0;
 302         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 303         c->self = found;
 304         c->type = type;
 305         c->ctype = ctype;
 306         c->local_window = window;
 307         c->local_window_max = window;
 308         c->local_consumed = 0;
 309         c->local_maxpacket = maxpack;
 310         c->remote_id = -1;
 311         c->remote_name = xstrdup(remote_name);
 312         c->remote_window = 0;
 313         c->remote_maxpacket = 0;
 314         c->force_drain = 0;
 315         c->single_connection = 0;
 316         c->detach_user = NULL;
 317         c->detach_close = 0;
 318         c->open_confirm = NULL;
 319         c->open_confirm_ctx = NULL;
 320         c->input_filter = NULL;
 321         c->output_filter = NULL;
 322         c->filter_ctx = NULL;
 323         c->filter_cleanup = NULL;
 324         TAILQ_INIT(&c->status_confirms);
 325         debug("channel %d: new [%s]", found, remote_name);
 326         return c;
 327 }
 328
 329 static int
 330 channel_find_maxfd(void)
 331 {
 332         u_int i;
 333         int max = 0;
 334         Channel *c;
 335
 336         for (i = 0; i < channels_alloc; i++) {
 337                 c = channels[i];
 338                 if (c != NULL) {
 339                         max = MAX(max, c->rfd);
 340                         max = MAX(max, c->wfd);
 341                         max = MAX(max, c->efd);
 342                 }
 343         }
 344         return max;
 345 }
 346
 347 int
 348 channel_close_fd(int *fdp)
 349 {
 350         int ret = 0, fd = *fdp;
 351
 352         if (fd != -1) {
 353                 ret = close(fd);
 354                 *fdp = -1;
 355                 if (fd == channel_max_fd)
 356                         channel_max_fd = channel_find_maxfd();
 357         }
 358         return ret;
 359 }
 360
 361 /* Close all channel fd/socket. */
 362 static void
 363 channel_close_fds(Channel *c)
 364 {
 365         debug3("channel %d: close_fds r %d w %d e %d c %d",
 366             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
 367
 368         channel_close_fd(&c->sock);
 369         channel_close_fd(&c->ctl_fd);
 370         channel_close_fd(&c->rfd);
 371         channel_close_fd(&c->wfd);
 372         channel_close_fd(&c->efd);
 373 }
 374
 375 /* Free the channel and close its fd/socket. */
 376 void
 377 channel_free(Channel *c)
 378 {
 379         char *s;
 380         u_int i, n;
 381         struct channel_confirm *cc;
 382
 383         for (n = 0, i = 0; i < channels_alloc; i++)
 384                 if (channels[i])
 385                         n++;
 386         debug("channel %d: free: %s, nchannels %u", c->self,
 387             c->remote_name ? c->remote_name : "???", n);
 388
 389         s = channel_open_message();
 390         debug3("channel %d: status: %s", c->self, s);
 391         xfree(s);
 392
 393         if (c->sock != -1)
 394                 shutdown(c->sock, SHUT_RDWR);
 395         if (c->ctl_fd != -1)
 396                 shutdown(c->ctl_fd, SHUT_RDWR);
 397         channel_close_fds(c);
 398         buffer_free(&c->input);
 399         buffer_free(&c->output);
 400         buffer_free(&c->extended);
 401         if (c->remote_name) {
 402                 xfree(c->remote_name);
 403                 c->remote_name = NULL;
 404         }
 405         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 406                 if (cc->abandon_cb != NULL)
 407                         cc->abandon_cb(c, cc->ctx);
 408                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 409                 bzero(cc, sizeof(*cc));
 410                 xfree(cc);
 411         }
 412         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 413                 c->filter_cleanup(c->self, c->filter_ctx);
 414         channels[c->self] = NULL;
 415         xfree(c);
 416 }
 417
 418 void
 419 channel_free_all(void)
 420 {
 421         u_int i;
 422
 423         for (i = 0; i < channels_alloc; i++)
 424                 if (channels[i] != NULL)
 425                         channel_free(channels[i]);
 426 }
 427
 428 /*
 429  * Closes the sockets/fds of all channels.  This is used to close extra file
 430  * descriptors after a fork.
 431  */
 432 void
 433 channel_close_all(void)
 434 {
 435         u_int i;
 436
 437         for (i = 0; i < channels_alloc; i++)
 438                 if (channels[i] != NULL)
 439                         channel_close_fds(channels[i]);
 440 }
 441
 442 /*
 443  * Stop listening to channels.
 444  */
 445 void
 446 channel_stop_listening(void)
 447 {
 448         u_int i;
 449         Channel *c;
 450
 451         for (i = 0; i < channels_alloc; i++) {
 452                 c = channels[i];
 453                 if (c != NULL) {
 454                         switch (c->type) {
 455                         case SSH_CHANNEL_AUTH_SOCKET:
 456                         case SSH_CHANNEL_PORT_LISTENER:
 457                         case SSH_CHANNEL_RPORT_LISTENER:
 458                         case SSH_CHANNEL_X11_LISTENER:
 459                                 channel_close_fd(&c->sock);
 460                                 channel_free(c);
 461                                 break;
 462                         }
 463                 }
 464         }
 465 }
 466
 467 /*
 468  * Returns true if no channel has too much buffered data, and false if one or
 469  * more channel is overfull.
 470  */
 471 int
 472 channel_not_very_much_buffered_data(void)
 473 {
 474         u_int i;
 475         Channel *c;
 476
 477         for (i = 0; i < channels_alloc; i++) {
 478                 c = channels[i];
 479                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
 480 #if 0
 481                         if (!compat20 &&
 482                             buffer_len(&c->input) > packet_get_maxsize()) {
 483                                 debug2("channel %d: big input buffer %d",
 484                                     c->self, buffer_len(&c->input));
 485                                 return 0;
 486                         }
 487 #endif
 488                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 489                                 debug2("channel %d: big output buffer %u > %u",
 490                                     c->self, buffer_len(&c->output),
 491                                     packet_get_maxsize());
 492                                 return 0;
 493                         }
 494                 }
 495         }
 496         return 1;
 497 }
 498
 499 /* Returns true if any channel is still open. */
 500 int
 501 channel_still_open(void)
 502 {
 503         u_int i;
 504         Channel *c;
 505
 506         for (i = 0; i < channels_alloc; i++) {
 507                 c = channels[i];
 508                 if (c == NULL)
 509                         continue;
 510                 switch (c->type) {
 511                 case SSH_CHANNEL_X11_LISTENER:
 512                 case SSH_CHANNEL_PORT_LISTENER:
 513                 case SSH_CHANNEL_RPORT_LISTENER:
 514                 case SSH_CHANNEL_CLOSED:
 515                 case SSH_CHANNEL_AUTH_SOCKET:
 516                 case SSH_CHANNEL_DYNAMIC:
 517                 case SSH_CHANNEL_CONNECTING:
 518                 case SSH_CHANNEL_ZOMBIE:
 519                         continue;
 520                 case SSH_CHANNEL_LARVAL:
 521                         if (!compat20)
 522                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 523                         continue;
 524                 case SSH_CHANNEL_OPENING:
 525                 case SSH_CHANNEL_OPEN:
 526                 case SSH_CHANNEL_X11_OPEN:
 527                         return 1;
 528                 case SSH_CHANNEL_INPUT_DRAINING:
 529                 case SSH_CHANNEL_OUTPUT_DRAINING:
 530                         if (!compat13)
 531                                 fatal("cannot happen: OUT_DRAIN");
 532                         return 1;
 533                 default:
 534                         fatal("channel_still_open: bad channel type %d", c->type);
 535                         /* NOTREACHED */
 536                 }
 537         }
 538         return 0;
 539 }
 540
 541 /* Returns the id of an open channel suitable for keepaliving */
 542 int
 543 channel_find_open(void)
 544 {
 545         u_int i;
 546         Channel *c;
 547
 548         for (i = 0; i < channels_alloc; i++) {
 549                 c = channels[i];
 550                 if (c == NULL || c->remote_id < 0)
 551                         continue;
 552                 switch (c->type) {
 553                 case SSH_CHANNEL_CLOSED:
 554                 case SSH_CHANNEL_DYNAMIC:
 555                 case SSH_CHANNEL_X11_LISTENER:
 556                 case SSH_CHANNEL_PORT_LISTENER:
 557                 case SSH_CHANNEL_RPORT_LISTENER:
 558                 case SSH_CHANNEL_OPENING:
 559                 case SSH_CHANNEL_CONNECTING:
 560                 case SSH_CHANNEL_ZOMBIE:
 561                         continue;
 562                 case SSH_CHANNEL_LARVAL:
 563                 case SSH_CHANNEL_AUTH_SOCKET:
 564                 case SSH_CHANNEL_OPEN:
 565                 case SSH_CHANNEL_X11_OPEN:
 566                         return i;
 567                 case SSH_CHANNEL_INPUT_DRAINING:
 568                 case SSH_CHANNEL_OUTPUT_DRAINING:
 569                         if (!compat13)
 570                                 fatal("cannot happen: OUT_DRAIN");
 571                         return i;
 572                 default:
 573                         fatal("channel_find_open: bad channel type %d", c->type);
 574                         /* NOTREACHED */
 575                 }
 576         }
 577         return -1;
 578 }
 579
 580
 581 /*
 582  * Returns a message describing the currently open forwarded connections,
 583  * suitable for sending to the client.  The message contains crlf pairs for
 584  * newlines.
 585  */
 586 char *
 587 channel_open_message(void)
 588 {
 589         Buffer buffer;
 590         Channel *c;
 591         char buf[1024], *cp;
 592         u_int i;
 593
 594         buffer_init(&buffer);
 595         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 596         buffer_append(&buffer, buf, strlen(buf));
 597         for (i = 0; i < channels_alloc; i++) {
 598                 c = channels[i];
 599                 if (c == NULL)
 600                         continue;
 601                 switch (c->type) {
 602                 case SSH_CHANNEL_X11_LISTENER:
 603                 case SSH_CHANNEL_PORT_LISTENER:
 604                 case SSH_CHANNEL_RPORT_LISTENER:
 605                 case SSH_CHANNEL_CLOSED:
 606                 case SSH_CHANNEL_AUTH_SOCKET:
 607                 case SSH_CHANNEL_ZOMBIE:
 608                         continue;
 609                 case SSH_CHANNEL_LARVAL:
 610                 case SSH_CHANNEL_OPENING:
 611                 case SSH_CHANNEL_CONNECTING:
 612                 case SSH_CHANNEL_DYNAMIC:
 613                 case SSH_CHANNEL_OPEN:
 614                 case SSH_CHANNEL_X11_OPEN:
 615                 case SSH_CHANNEL_INPUT_DRAINING:
 616                 case SSH_CHANNEL_OUTPUT_DRAINING:
 617                         snprintf(buf, sizeof buf,
 618                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
 619                             c->self, c->remote_name,
 620                             c->type, c->remote_id,
 621                             c->istate, buffer_len(&c->input),
 622                             c->ostate, buffer_len(&c->output),
 623                             c->rfd, c->wfd, c->ctl_fd);
 624                         buffer_append(&buffer, buf, strlen(buf));
 625                         continue;
 626                 default:
 627                         fatal("channel_open_message: bad channel type %d", c->type);
 628                         /* NOTREACHED */
 629                 }
 630         }
 631         buffer_append(&buffer, "\0", 1);
 632         cp = xstrdup(buffer_ptr(&buffer));
 633         buffer_free(&buffer);
 634         return cp;
 635 }
 636
 637 void
 638 channel_send_open(int id)
 639 {
 640         Channel *c = channel_lookup(id);
 641
 642         if (c == NULL) {
 643                 logit("channel_send_open: %d: bad id", id);
 644                 return;
 645         }
 646         debug2("channel %d: send open", id);
 647         packet_start(SSH2_MSG_CHANNEL_OPEN);
 648         packet_put_cstring(c->ctype);
 649         packet_put_int(c->self);
 650         packet_put_int(c->local_window);
 651         packet_put_int(c->local_maxpacket);
 652         packet_send();
 653 }
 654
 655 void
 656 channel_request_start(int id, char *service, int wantconfirm)
 657 {
 658         Channel *c = channel_lookup(id);
 659
 660         if (c == NULL) {
 661                 logit("channel_request_start: %d: unknown channel id", id);
 662                 return;
 663         }
 664         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 665         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 666         packet_put_int(c->remote_id);
 667         packet_put_cstring(service);
 668         packet_put_char(wantconfirm);
 669 }
 670
 671 void
 672 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 673     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 674 {
 675         struct channel_confirm *cc;
 676         Channel *c;
 677
 678         if ((c = channel_lookup(id)) == NULL)
 679                 fatal("channel_register_expect: %d: bad id", id);
 680
 681         cc = xmalloc(sizeof(*cc));
 682         cc->cb = cb;
 683         cc->abandon_cb = abandon_cb;
 684         cc->ctx = ctx;
 685         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 686 }
 687
 688 void
 689 channel_register_open_confirm(int id, channel_callback_fn *fn, void *ctx)
 690 {
 691         Channel *c = channel_lookup(id);
 692
 693         if (c == NULL) {
 694                 logit("channel_register_open_confirm: %d: bad id", id);
 695                 return;
 696         }
 697         c->open_confirm = fn;
 698         c->open_confirm_ctx = ctx;
 699 }
 700
 701 void
 702 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 703 {
 704         Channel *c = channel_by_id(id);
 705
 706         if (c == NULL) {
 707                 logit("channel_register_cleanup: %d: bad id", id);
 708                 return;
 709         }
 710         c->detach_user = fn;
 711         c->detach_close = do_close;
 712 }
 713
 714 void
 715 channel_cancel_cleanup(int id)
 716 {
 717         Channel *c = channel_by_id(id);
 718
 719         if (c == NULL) {
 720                 logit("channel_cancel_cleanup: %d: bad id", id);
 721                 return;
 722         }
 723         c->detach_user = NULL;
 724         c->detach_close = 0;
 725 }
 726
 727 void
 728 channel_register_filter(int id, channel_infilter_fn *ifn,
 729     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 730 {
 731         Channel *c = channel_lookup(id);
 732
 733         if (c == NULL) {
 734                 logit("channel_register_filter: %d: bad id", id);
 735                 return;
 736         }
 737         c->input_filter = ifn;
 738         c->output_filter = ofn;
 739         c->filter_ctx = ctx;
 740         c->filter_cleanup = cfn;
 741 }
 742
 743 void
 744 channel_set_fds(int id, int rfd, int wfd, int efd,
 745     int extusage, int nonblock, int is_tty, u_int window_max)
 746 {
 747         Channel *c = channel_lookup(id);
 748
 749         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 750                 fatal("channel_activate for non-larval channel %d.", id);
 751         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 752         c->type = SSH_CHANNEL_OPEN;
 753         c->local_window = c->local_window_max = window_max;
 754         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 755         packet_put_int(c->remote_id);
 756         packet_put_int(c->local_window);
 757         packet_send();
 758 }
 759
 760 /*
 761  * 'channel_pre*' are called just before select() to add any bits relevant to
 762  * channels in the select bitmasks.
 763  */
 764 /*
 765  * 'channel_post*': perform any appropriate operations for channels which
 766  * have events pending.
 767  */
 768 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 769 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 770 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 771
 772 /* ARGSUSED */
 773 static void
 774 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 775 {
 776         FD_SET(c->sock, readset);
 777 }
 778
 779 /* ARGSUSED */
 780 static void
 781 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 782 {
 783         debug3("channel %d: waiting for connection", c->self);
 784         FD_SET(c->sock, writeset);
 785 }
 786
 787 static void
 788 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 789 {
 790         if (buffer_len(&c->input) < packet_get_maxsize())
 791                 FD_SET(c->sock, readset);
 792         if (buffer_len(&c->output) > 0)
 793                 FD_SET(c->sock, writeset);
 794 }
 795
 796 static void
 797 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 798 {
 799         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 800
 801         if (c->istate == CHAN_INPUT_OPEN &&
 802             limit > 0 &&
 803             buffer_len(&c->input) < limit &&
 804             buffer_check_alloc(&c->input, CHAN_RBUF))
 805                 FD_SET(c->rfd, readset);
 806         if (c->ostate == CHAN_OUTPUT_OPEN ||
 807             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 808                 if (buffer_len(&c->output) > 0) {
 809                         FD_SET(c->wfd, writeset);
 810                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 811                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 812                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 813                                     c->self, c->efd, buffer_len(&c->extended));
 814                         else
 815                                 chan_obuf_empty(c);
 816                 }
 817         }
 818         /** XXX check close conditions, too */
 819         if (compat20 && c->efd != -1 &&
 820             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 821                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 822                     buffer_len(&c->extended) > 0)
 823                         FD_SET(c->efd, writeset);
 824                 else if (!(c->flags & CHAN_EOF_SENT) &&
 825                     c->extended_usage == CHAN_EXTENDED_READ &&
 826                     buffer_len(&c->extended) < c->remote_window)
 827                         FD_SET(c->efd, readset);
 828         }
 829         /* XXX: What about efd? races? */
 830         if (compat20 && c->ctl_fd != -1 &&
 831             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
 832                 FD_SET(c->ctl_fd, readset);
 833 }
 834
 835 /* ARGSUSED */
 836 static void
 837 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 838 {
 839         if (buffer_len(&c->input) == 0) {
 840                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 841                 packet_put_int(c->remote_id);
 842                 packet_send();
 843                 c->type = SSH_CHANNEL_CLOSED;
 844                 debug2("channel %d: closing after input drain.", c->self);
 845         }
 846 }
 847
 848 /* ARGSUSED */
 849 static void
 850 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 851 {
 852         if (buffer_len(&c->output) == 0)
 853                 chan_mark_dead(c);
 854         else
 855                 FD_SET(c->sock, writeset);
 856 }
 857
 858 /*
 859  * This is a special state for X11 authentication spoofing.  An opened X11
 860  * connection (when authentication spoofing is being done) remains in this
 861  * state until the first packet has been completely read.  The authentication
 862  * data in that packet is then substituted by the real data if it matches the
 863  * fake data, and the channel is put into normal mode.
 864  * XXX All this happens at the client side.
 865  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 866  */
 867 static int
 868 x11_open_helper(Buffer *b)
 869 {
 870         u_char *ucp;
 871         u_int proto_len, data_len;
 872
 873         /* Check if the fixed size part of the packet is in buffer. */
 874         if (buffer_len(b) < 12)
 875                 return 0;
 876
 877         /* Parse the lengths of variable-length fields. */
 878         ucp = buffer_ptr(b);
 879         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 880                 proto_len = 256 * ucp[6] + ucp[7];
 881                 data_len = 256 * ucp[8] + ucp[9];
 882         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 883                 proto_len = ucp[6] + 256 * ucp[7];
 884                 data_len = ucp[8] + 256 * ucp[9];
 885         } else {
 886                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 887                     ucp[0]);
 888                 return -1;
 889         }
 890
 891         /* Check if the whole packet is in buffer. */
 892         if (buffer_len(b) <
 893             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 894                 return 0;
 895
 896         /* Check if authentication protocol matches. */
 897         if (proto_len != strlen(x11_saved_proto) ||
 898             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 899                 debug2("X11 connection uses different authentication protocol.");
 900                 return -1;
 901         }
 902         /* Check if authentication data matches our fake data. */
 903         if (data_len != x11_fake_data_len ||
 904             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
 905                 x11_fake_data, x11_fake_data_len) != 0) {
 906                 debug2("X11 auth data does not match fake data.");
 907                 return -1;
 908         }
 909         /* Check fake data length */
 910         if (x11_fake_data_len != x11_saved_data_len) {
 911                 error("X11 fake_data_len %d != saved_data_len %d",
 912                     x11_fake_data_len, x11_saved_data_len);
 913                 return -1;
 914         }
 915         /*
 916          * Received authentication protocol and data match
 917          * our fake data. Substitute the fake data with real
 918          * data.
 919          */
 920         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 921             x11_saved_data, x11_saved_data_len);
 922         return 1;
 923 }
 924
 925 static void
 926 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 927 {
 928         int ret = x11_open_helper(&c->output);
 929
 930         if (ret == 1) {
 931                 /* Start normal processing for the channel. */
 932                 c->type = SSH_CHANNEL_OPEN;
 933                 channel_pre_open_13(c, readset, writeset);
 934         } else if (ret == -1) {
 935                 /*
 936                  * We have received an X11 connection that has bad
 937                  * authentication information.
 938                  */
 939                 logit("X11 connection rejected because of wrong authentication.");
 940                 buffer_clear(&c->input);
 941                 buffer_clear(&c->output);
 942                 channel_close_fd(&c->sock);
 943                 c->sock = -1;
 944                 c->type = SSH_CHANNEL_CLOSED;
 945                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 946                 packet_put_int(c->remote_id);
 947                 packet_send();
 948         }
 949 }
 950
 951 static void
 952 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 953 {
 954         int ret = x11_open_helper(&c->output);
 955
 956         /* c->force_drain = 1; */
 957
 958         if (ret == 1) {
 959                 c->type = SSH_CHANNEL_OPEN;
 960                 channel_pre_open(c, readset, writeset);
 961         } else if (ret == -1) {
 962                 logit("X11 connection rejected because of wrong authentication.");
 963                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
 964                 chan_read_failed(c);
 965                 buffer_clear(&c->input);
 966                 chan_ibuf_empty(c);
 967                 buffer_clear(&c->output);
 968                 /* for proto v1, the peer will send an IEOF */
 969                 if (compat20)
 970                         chan_write_failed(c);
 971                 else
 972                         c->type = SSH_CHANNEL_OPEN;
 973                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
 974         }
 975 }
 976
 977 /* try to decode a socks4 header */
 978 /* ARGSUSED */
 979 static int
 980 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 981 {
 982         char *p, *host;
 983         u_int len, have, i, found, need;
 984         char username[256];
 985         struct {
 986                 u_int8_t version;
 987                 u_int8_t command;
 988                 u_int16_t dest_port;
 989                 struct in_addr dest_addr;
 990         } s4_req, s4_rsp;
 991
 992         debug2("channel %d: decode socks4", c->self);
 993
 994         have = buffer_len(&c->input);
 995         len = sizeof(s4_req);
 996         if (have < len)
 997                 return 0;
 998         p = buffer_ptr(&c->input);
 999
1000         need = 1;
1001         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1002         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1003                 debug2("channel %d: socks4a request", c->self);
1004                 /* ... and needs an extra string (the hostname) */
1005                 need = 2;
1006         }
1007         /* Check for terminating NUL on the string(s) */
1008         for (found = 0, i = len; i < have; i++) {
1009                 if (p[i] == '\0') {
1010                         found++;
1011                         if (found == need)
1012                                 break;
1013                 }
1014                 if (i > 1024) {
1015                         /* the peer is probably sending garbage */
1016                         debug("channel %d: decode socks4: too long",
1017                             c->self);
1018                         return -1;
1019                 }
1020         }
1021         if (found < need)
1022                 return 0;
1023         buffer_get(&c->input, (char *)&s4_req.version, 1);
1024         buffer_get(&c->input, (char *)&s4_req.command, 1);
1025         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1026         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1027         have = buffer_len(&c->input);
1028         p = buffer_ptr(&c->input);
1029         len = strlen(p);
1030         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1031         len++;                                  /* trailing '\0' */
1032         if (len > have)
1033                 fatal("channel %d: decode socks4: len %d > have %d",
1034                     c->self, len, have);
1035         strlcpy(username, p, sizeof(username));
1036         buffer_consume(&c->input, len);
1037
1038         if (need == 1) {                        /* SOCKS4: one string */
1039                 host = inet_ntoa(s4_req.dest_addr);
1040                 strlcpy(c->path, host, sizeof(c->path));
1041         } else {                                /* SOCKS4A: two strings */
1042                 have = buffer_len(&c->input);
1043                 p = buffer_ptr(&c->input);
1044                 len = strlen(p);
1045                 debug2("channel %d: decode socks4a: host %s/%d",
1046                     c->self, p, len);
1047                 len++;                          /* trailing '\0' */
1048                 if (len > have)
1049                         fatal("channel %d: decode socks4a: len %d > have %d",
1050                             c->self, len, have);
1051                 if (strlcpy(c->path, p, sizeof(c->path)) >= sizeof(c->path)) {
1052                         error("channel %d: hostname \"%.100s\" too long",
1053                             c->self, p);
1054                         return -1;
1055                 }
1056                 buffer_consume(&c->input, len);
1057         }
1058         c->host_port = ntohs(s4_req.dest_port);
1059
1060         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1061             c->self, c->path, c->host_port, s4_req.command);
1062
1063         if (s4_req.command != 1) {
1064                 debug("channel %d: cannot handle: %s cn %d",
1065                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1066                 return -1;
1067         }
1068         s4_rsp.version = 0;                     /* vn: 0 for reply */
1069         s4_rsp.command = 90;                    /* cd: req granted */
1070         s4_rsp.dest_port = 0;                   /* ignored */
1071         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1072         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1073         return 1;
1074 }
1075
1076 /* try to decode a socks5 header */
1077 #define SSH_SOCKS5_AUTHDONE     0x1000
1078 #define SSH_SOCKS5_NOAUTH       0x00
1079 #define SSH_SOCKS5_IPV4         0x01
1080 #define SSH_SOCKS5_DOMAIN       0x03
1081 #define SSH_SOCKS5_IPV6         0x04
1082 #define SSH_SOCKS5_CONNECT      0x01
1083 #define SSH_SOCKS5_SUCCESS      0x00
1084
1085 /* ARGSUSED */
1086 static int
1087 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1088 {
1089         struct {
1090                 u_int8_t version;
1091                 u_int8_t command;
1092                 u_int8_t reserved;
1093                 u_int8_t atyp;
1094         } s5_req, s5_rsp;
1095         u_int16_t dest_port;
1096         u_char *p, dest_addr[255+1];
1097         u_int have, need, i, found, nmethods, addrlen, af;
1098
1099         debug2("channel %d: decode socks5", c->self);
1100         p = buffer_ptr(&c->input);
1101         if (p[0] != 0x05)
1102                 return -1;
1103         have = buffer_len(&c->input);
1104         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1105                 /* format: ver | nmethods | methods */
1106                 if (have < 2)
1107                         return 0;
1108                 nmethods = p[1];
1109                 if (have < nmethods + 2)
1110                         return 0;
1111                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1112                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1113                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1114                                 found = 1;
1115                                 break;
1116                         }
1117                 }
1118                 if (!found) {
1119                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1120                             c->self);
1121                         return -1;
1122                 }
1123                 buffer_consume(&c->input, nmethods + 2);
1124                 buffer_put_char(&c->output, 0x05);              /* version */
1125                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1126                 FD_SET(c->sock, writeset);
1127                 c->flags |= SSH_SOCKS5_AUTHDONE;
1128                 debug2("channel %d: socks5 auth done", c->self);
1129                 return 0;                               /* need more */
1130         }
1131         debug2("channel %d: socks5 post auth", c->self);
1132         if (have < sizeof(s5_req)+1)
1133                 return 0;                       /* need more */
1134         memcpy(&s5_req, p, sizeof(s5_req));
1135         if (s5_req.version != 0x05 ||
1136             s5_req.command != SSH_SOCKS5_CONNECT ||
1137             s5_req.reserved != 0x00) {
1138                 debug2("channel %d: only socks5 connect supported", c->self);
1139                 return -1;
1140         }
1141         switch (s5_req.atyp){
1142         case SSH_SOCKS5_IPV4:
1143                 addrlen = 4;
1144                 af = AF_INET;
1145                 break;
1146         case SSH_SOCKS5_DOMAIN:
1147                 addrlen = p[sizeof(s5_req)];
1148                 af = -1;
1149                 break;
1150         case SSH_SOCKS5_IPV6:
1151                 addrlen = 16;
1152                 af = AF_INET6;
1153                 break;
1154         default:
1155                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1156                 return -1;
1157         }
1158         need = sizeof(s5_req) + addrlen + 2;
1159         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1160                 need++;
1161         if (have < need)
1162                 return 0;
1163         buffer_consume(&c->input, sizeof(s5_req));
1164         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1165                 buffer_consume(&c->input, 1);    /* host string length */
1166         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1167         buffer_get(&c->input, (char *)&dest_port, 2);
1168         dest_addr[addrlen] = '\0';
1169         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1170                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1171         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1172                 return -1;
1173         c->host_port = ntohs(dest_port);
1174
1175         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1176             c->self, c->path, c->host_port, s5_req.command);
1177
1178         s5_rsp.version = 0x05;
1179         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1180         s5_rsp.reserved = 0;                    /* ignored */
1181         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1182         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1183         dest_port = 0;                          /* ignored */
1184
1185         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1186         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1187         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1188         return 1;
1189 }
1190
1191 /* dynamic port forwarding */
1192 static void
1193 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1194 {
1195         u_char *p;
1196         u_int have;
1197         int ret;
1198
1199         have = buffer_len(&c->input);
1200         c->delayed = 0;
1201         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1202         /* buffer_dump(&c->input); */
1203         /* check if the fixed size part of the packet is in buffer. */
1204         if (have < 3) {
1205                 /* need more */
1206                 FD_SET(c->sock, readset);
1207                 return;
1208         }
1209         /* try to guess the protocol */
1210         p = buffer_ptr(&c->input);
1211         switch (p[0]) {
1212         case 0x04:
1213                 ret = channel_decode_socks4(c, readset, writeset);
1214                 break;
1215         case 0x05:
1216                 ret = channel_decode_socks5(c, readset, writeset);
1217                 break;
1218         default:
1219                 ret = -1;
1220                 break;
1221         }
1222         if (ret < 0) {
1223                 chan_mark_dead(c);
1224         } else if (ret == 0) {
1225                 debug2("channel %d: pre_dynamic: need more", c->self);
1226                 /* need more */
1227                 FD_SET(c->sock, readset);
1228         } else {
1229                 /* switch to the next state */
1230                 c->type = SSH_CHANNEL_OPENING;
1231                 port_open_helper(c, "direct-tcpip");
1232         }
1233 }
1234
1235 /* This is our fake X11 server socket. */
1236 /* ARGSUSED */
1237 static void
1238 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1239 {
1240         Channel *nc;
1241         struct sockaddr_storage addr;
1242         int newsock;
1243         socklen_t addrlen;
1244         char buf[16384], *remote_ipaddr;
1245         int remote_port;
1246
1247         if (FD_ISSET(c->sock, readset)) {
1248                 debug("X11 connection requested.");
1249                 addrlen = sizeof(addr);
1250                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1251                 if (c->single_connection) {
1252                         debug2("single_connection: closing X11 listener.");
1253                         channel_close_fd(&c->sock);
1254                         chan_mark_dead(c);
1255                 }
1256                 if (newsock < 0) {
1257                         error("accept: %.100s", strerror(errno));
1258                         return;
1259                 }
1260                 set_nodelay(newsock);
1261                 remote_ipaddr = get_peer_ipaddr(newsock);
1262                 remote_port = get_peer_port(newsock);
1263                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1264                     remote_ipaddr, remote_port);
1265
1266                 nc = channel_new("accepted x11 socket",
1267                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1268                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1269                 if (compat20) {
1270                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1271                         packet_put_cstring("x11");
1272                         packet_put_int(nc->self);
1273                         packet_put_int(nc->local_window_max);
1274                         packet_put_int(nc->local_maxpacket);
1275                         /* originator ipaddr and port */
1276                         packet_put_cstring(remote_ipaddr);
1277                         if (datafellows & SSH_BUG_X11FWD) {
1278                                 debug2("ssh2 x11 bug compat mode");
1279                         } else {
1280                                 packet_put_int(remote_port);
1281                         }
1282                         packet_send();
1283                 } else {
1284                         packet_start(SSH_SMSG_X11_OPEN);
1285                         packet_put_int(nc->self);
1286                         if (packet_get_protocol_flags() &
1287                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1288                                 packet_put_cstring(buf);
1289                         packet_send();
1290                 }
1291                 xfree(remote_ipaddr);
1292         }
1293 }
1294
1295 static void
1296 port_open_helper(Channel *c, char *rtype)
1297 {
1298         int direct;
1299         char buf[1024];
1300         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1301         int remote_port = get_peer_port(c->sock);
1302
1303         direct = (strcmp(rtype, "direct-tcpip") == 0);
1304
1305         snprintf(buf, sizeof buf,
1306             "%s: listening port %d for %.100s port %d, "
1307             "connect from %.200s port %d",
1308             rtype, c->listening_port, c->path, c->host_port,
1309             remote_ipaddr, remote_port);
1310
1311         xfree(c->remote_name);
1312         c->remote_name = xstrdup(buf);
1313
1314         if (compat20) {
1315                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1316                 packet_put_cstring(rtype);
1317                 packet_put_int(c->self);
1318                 packet_put_int(c->local_window_max);
1319                 packet_put_int(c->local_maxpacket);
1320                 if (direct) {
1321                         /* target host, port */
1322                         packet_put_cstring(c->path);
1323                         packet_put_int(c->host_port);
1324                 } else {
1325                         /* listen address, port */
1326                         packet_put_cstring(c->path);
1327                         packet_put_int(c->listening_port);
1328                 }
1329                 /* originator host and port */
1330                 packet_put_cstring(remote_ipaddr);
1331                 packet_put_int((u_int)remote_port);
1332                 packet_send();
1333         } else {
1334                 packet_start(SSH_MSG_PORT_OPEN);
1335                 packet_put_int(c->self);
1336                 packet_put_cstring(c->path);
1337                 packet_put_int(c->host_port);
1338                 if (packet_get_protocol_flags() &
1339                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1340                         packet_put_cstring(c->remote_name);
1341                 packet_send();
1342         }
1343         xfree(remote_ipaddr);
1344 }
1345
1346 static void
1347 channel_set_reuseaddr(int fd)
1348 {
1349         int on = 1;
1350
1351         /*
1352          * Set socket options.
1353          * Allow local port reuse in TIME_WAIT.
1354          */
1355         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1356                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1357 }
1358
1359 /*
1360  * This socket is listening for connections to a forwarded TCP/IP port.
1361  */
1362 /* ARGSUSED */
1363 static void
1364 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1365 {
1366         Channel *nc;
1367         struct sockaddr_storage addr;
1368         int newsock, nextstate;
1369         socklen_t addrlen;
1370         char *rtype;
1371
1372         if (FD_ISSET(c->sock, readset)) {
1373                 debug("Connection to port %d forwarding "
1374                     "to %.100s port %d requested.",
1375                     c->listening_port, c->path, c->host_port);
1376
1377                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1378                         nextstate = SSH_CHANNEL_OPENING;
1379                         rtype = "forwarded-tcpip";
1380                 } else {
1381                         if (c->host_port == 0) {
1382                                 nextstate = SSH_CHANNEL_DYNAMIC;
1383                                 rtype = "dynamic-tcpip";
1384                         } else {
1385                                 nextstate = SSH_CHANNEL_OPENING;
1386                                 rtype = "direct-tcpip";
1387                         }
1388                 }
1389
1390                 addrlen = sizeof(addr);
1391                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1392                 if (newsock < 0) {
1393                         error("accept: %.100s", strerror(errno));
1394                         return;
1395                 }
1396                 set_nodelay(newsock);
1397                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1398                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1399                 nc->listening_port = c->listening_port;
1400                 nc->host_port = c->host_port;
1401                 strlcpy(nc->path, c->path, sizeof(nc->path));
1402
1403                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1404                         /*
1405                          * do not call the channel_post handler until
1406                          * this flag has been reset by a pre-handler.
1407                          * otherwise the FD_ISSET calls might overflow
1408                          */
1409                         nc->delayed = 1;
1410                 } else {
1411                         port_open_helper(nc, rtype);
1412                 }
1413         }
1414 }
1415
1416 /*
1417  * This is the authentication agent socket listening for connections from
1418  * clients.
1419  */
1420 /* ARGSUSED */
1421 static void
1422 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1423 {
1424         Channel *nc;
1425         int newsock;
1426         struct sockaddr_storage addr;
1427         socklen_t addrlen;
1428
1429         if (FD_ISSET(c->sock, readset)) {
1430                 addrlen = sizeof(addr);
1431                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1432                 if (newsock < 0) {
1433                         error("accept from auth socket: %.100s", strerror(errno));
1434                         return;
1435                 }
1436                 nc = channel_new("accepted auth socket",
1437                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1438                     c->local_window_max, c->local_maxpacket,
1439                     0, "accepted auth socket", 1);
1440                 if (compat20) {
1441                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1442                         packet_put_cstring("auth-agent@openssh.com");
1443                         packet_put_int(nc->self);
1444                         packet_put_int(c->local_window_max);
1445                         packet_put_int(c->local_maxpacket);
1446                 } else {
1447                         packet_start(SSH_SMSG_AGENT_OPEN);
1448                         packet_put_int(nc->self);
1449                 }
1450                 packet_send();
1451         }
1452 }
1453
1454 /* ARGSUSED */
1455 static void
1456 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1457 {
1458         int err = 0, sock;
1459         socklen_t sz = sizeof(err);
1460
1461         if (FD_ISSET(c->sock, writeset)) {
1462                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1463                         err = errno;
1464                         error("getsockopt SO_ERROR failed");
1465                 }
1466                 if (err == 0) {
1467                         debug("channel %d: connected to %s port %d",
1468                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1469                         channel_connect_ctx_free(&c->connect_ctx);
1470                         c->type = SSH_CHANNEL_OPEN;
1471                         if (compat20) {
1472                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1473                                 packet_put_int(c->remote_id);
1474                                 packet_put_int(c->self);
1475                                 packet_put_int(c->local_window);
1476                                 packet_put_int(c->local_maxpacket);
1477                         } else {
1478                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1479                                 packet_put_int(c->remote_id);
1480                                 packet_put_int(c->self);
1481                         }
1482                 } else {
1483                         debug("channel %d: connection failed: %s",
1484                             c->self, strerror(err));
1485                         /* Try next address, if any */
1486                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1487                                 close(c->sock);
1488                                 c->sock = c->rfd = c->wfd = sock;
1489                                 channel_max_fd = channel_find_maxfd();
1490                                 return;
1491                         }
1492                         /* Exhausted all addresses */
1493                         error("connect_to %.100s port %d: failed.",
1494                             c->connect_ctx.host, c->connect_ctx.port);
1495                         channel_connect_ctx_free(&c->connect_ctx);
1496                         if (compat20) {
1497                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1498                                 packet_put_int(c->remote_id);
1499                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1500                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1501                                         packet_put_cstring(strerror(err));
1502                                         packet_put_cstring("");
1503                                 }
1504                         } else {
1505                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1506                                 packet_put_int(c->remote_id);
1507                         }
1508                         chan_mark_dead(c);
1509                 }
1510                 packet_send();
1511         }
1512 }
1513
1514 /* ARGSUSED */
1515 static int
1516 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1517 {
1518         char buf[CHAN_RBUF];
1519         int len, force;
1520
1521         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1522         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1523                 errno = 0;
1524                 len = read(c->rfd, buf, sizeof(buf));
1525                 if (len < 0 && (errno == EINTR ||
1526                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1527                         return 1;
1528 #ifndef PTY_ZEROREAD
1529                 if (len <= 0) {
1530 #else
1531                 if ((!c->isatty && len <= 0) ||
1532                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1533 #endif
1534                         debug2("channel %d: read<=0 rfd %d len %d",
1535                             c->self, c->rfd, len);
1536                         if (c->type != SSH_CHANNEL_OPEN) {
1537                                 debug2("channel %d: not open", c->self);
1538                                 chan_mark_dead(c);
1539                                 return -1;
1540                         } else if (compat13) {
1541                                 buffer_clear(&c->output);
1542                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1543                                 debug2("channel %d: input draining.", c->self);
1544                         } else {
1545                                 chan_read_failed(c);
1546                         }
1547                         return -1;
1548                 }
1549                 if (c->input_filter != NULL) {
1550                         if (c->input_filter(c, buf, len) == -1) {
1551                                 debug2("channel %d: filter stops", c->self);
1552                                 chan_read_failed(c);
1553                         }
1554                 } else if (c->datagram) {
1555                         buffer_put_string(&c->input, buf, len);
1556                 } else {
1557                         buffer_append(&c->input, buf, len);
1558                 }
1559         }
1560         return 1;
1561 }
1562
1563 /* ARGSUSED */
1564 static int
1565 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1566 {
1567         struct termios tio;
1568         u_char *data = NULL, *buf;
1569         u_int dlen;
1570         int len;
1571
1572         /* Send buffered output data to the socket. */
1573         if (c->wfd != -1 &&
1574             FD_ISSET(c->wfd, writeset) &&
1575             buffer_len(&c->output) > 0) {
1576                 if (c->output_filter != NULL) {
1577                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1578                                 debug2("channel %d: filter stops", c->self);
1579                                 if (c->type != SSH_CHANNEL_OPEN)
1580                                         chan_mark_dead(c);
1581                                 else
1582                                         chan_write_failed(c);
1583                                 return -1;
1584                         }
1585                 } else if (c->datagram) {
1586                         buf = data = buffer_get_string(&c->output, &dlen);
1587                 } else {
1588                         buf = data = buffer_ptr(&c->output);
1589                         dlen = buffer_len(&c->output);
1590                 }
1591
1592                 if (c->datagram) {
1593                         /* ignore truncated writes, datagrams might get lost */
1594                         c->local_consumed += dlen + 4;
1595                         len = write(c->wfd, buf, dlen);
1596                         xfree(data);
1597                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1598                             errno == EWOULDBLOCK))
1599                                 return 1;
1600                         if (len <= 0) {
1601                                 if (c->type != SSH_CHANNEL_OPEN)
1602                                         chan_mark_dead(c);
1603                                 else
1604                                         chan_write_failed(c);
1605                                 return -1;
1606                         }
1607                         return 1;
1608                 }
1609 #ifdef _AIX
1610                 /* XXX: Later AIX versions can't push as much data to tty */
1611                 if (compat20 && c->wfd_isatty)
1612                         dlen = MIN(dlen, 8*1024);
1613 #endif
1614
1615                 len = write(c->wfd, buf, dlen);
1616                 if (len < 0 &&
1617                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1618                         return 1;
1619                 if (len <= 0) {
1620                         if (c->type != SSH_CHANNEL_OPEN) {
1621                                 debug2("channel %d: not open", c->self);
1622                                 chan_mark_dead(c);
1623                                 return -1;
1624                         } else if (compat13) {
1625                                 buffer_clear(&c->output);
1626                                 debug2("channel %d: input draining.", c->self);
1627                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1628                         } else {
1629                                 chan_write_failed(c);
1630                         }
1631                         return -1;
1632                 }
1633                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1634                         if (tcgetattr(c->wfd, &tio) == 0 &&
1635                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1636                                 /*
1637                                  * Simulate echo to reduce the impact of
1638                                  * traffic analysis. We need to match the
1639                                  * size of a SSH2_MSG_CHANNEL_DATA message
1640                                  * (4 byte channel id + buf)
1641                                  */
1642                                 packet_send_ignore(4 + len);
1643                                 packet_send();
1644                         }
1645                 }
1646                 buffer_consume(&c->output, len);
1647                 if (compat20 && len > 0) {
1648                         c->local_consumed += len;
1649                 }
1650         }
1651         return 1;
1652 }
1653
1654 static int
1655 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1656 {
1657         char buf[CHAN_RBUF];
1658         int len;
1659
1660 /** XXX handle drain efd, too */
1661         if (c->efd != -1) {
1662                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1663                     FD_ISSET(c->efd, writeset) &&
1664                     buffer_len(&c->extended) > 0) {
1665                         len = write(c->efd, buffer_ptr(&c->extended),
1666                             buffer_len(&c->extended));
1667                         debug2("channel %d: written %d to efd %d",
1668                             c->self, len, c->efd);
1669                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1670                             errno == EWOULDBLOCK))
1671                                 return 1;
1672                         if (len <= 0) {
1673                                 debug2("channel %d: closing write-efd %d",
1674                                     c->self, c->efd);
1675                                 channel_close_fd(&c->efd);
1676                         } else {
1677                                 buffer_consume(&c->extended, len);
1678                                 c->local_consumed += len;
1679                         }
1680                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1681                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1682                         len = read(c->efd, buf, sizeof(buf));
1683                         debug2("channel %d: read %d from efd %d",
1684                             c->self, len, c->efd);
1685                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1686                             errno == EWOULDBLOCK) && !c->detach_close)))
1687                                 return 1;
1688                         if (len <= 0) {
1689                                 debug2("channel %d: closing read-efd %d",
1690                                     c->self, c->efd);
1691                                 channel_close_fd(&c->efd);
1692                         } else {
1693                                 buffer_append(&c->extended, buf, len);
1694                         }
1695                 }
1696         }
1697         return 1;
1698 }
1699
1700 /* ARGSUSED */
1701 static int
1702 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1703 {
1704         char buf[16];
1705         int len;
1706
1707         /* Monitor control fd to detect if the slave client exits */
1708         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1709                 len = read(c->ctl_fd, buf, sizeof(buf));
1710                 if (len < 0 &&
1711                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1712                         return 1;
1713                 if (len <= 0) {
1714                         debug2("channel %d: ctl read<=0", c->self);
1715                         if (c->type != SSH_CHANNEL_OPEN) {
1716                                 debug2("channel %d: not open", c->self);
1717                                 chan_mark_dead(c);
1718                                 return -1;
1719                         } else {
1720                                 chan_read_failed(c);
1721                                 chan_write_failed(c);
1722                         }
1723                         return -1;
1724                 } else
1725                         fatal("%s: unexpected data on ctl fd", __func__);
1726         }
1727         return 1;
1728 }
1729
1730 static int
1731 channel_check_window(Channel *c)
1732 {
1733         if (c->type == SSH_CHANNEL_OPEN &&
1734             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1735             ((c->local_window_max - c->local_window >
1736             c->local_maxpacket*3) ||
1737             c->local_window < c->local_window_max/2) &&
1738             c->local_consumed > 0) {
1739                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1740                 packet_put_int(c->remote_id);
1741                 packet_put_int(c->local_consumed);
1742                 packet_send();
1743                 debug2("channel %d: window %d sent adjust %d",
1744                     c->self, c->local_window,
1745                     c->local_consumed);
1746                 c->local_window += c->local_consumed;
1747                 c->local_consumed = 0;
1748         }
1749         return 1;
1750 }
1751
1752 static void
1753 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1754 {
1755         if (c->delayed)
1756                 return;
1757         channel_handle_rfd(c, readset, writeset);
1758         channel_handle_wfd(c, readset, writeset);
1759         if (!compat20)
1760                 return;
1761         channel_handle_efd(c, readset, writeset);
1762         channel_handle_ctl(c, readset, writeset);
1763         channel_check_window(c);
1764 }
1765
1766 /* ARGSUSED */
1767 static void
1768 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1769 {
1770         int len;
1771
1772         /* Send buffered output data to the socket. */
1773         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1774                 len = write(c->sock, buffer_ptr(&c->output),
1775                             buffer_len(&c->output));
1776                 if (len <= 0)
1777                         buffer_clear(&c->output);
1778                 else
1779                         buffer_consume(&c->output, len);
1780         }
1781 }
1782
1783 static void
1784 channel_handler_init_20(void)
1785 {
1786         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1787         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1788         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1789         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1790         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1791         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1792         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1793         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1794
1795         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1796         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1797         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1798         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1799         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1800         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1801         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1802 }
1803
1804 static void
1805 channel_handler_init_13(void)
1806 {
1807         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1808         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1809         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1810         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1811         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1812         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1813         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1814         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1815         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1816
1817         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1818         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1819         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1820         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1821         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1822         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1823         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1824 }
1825
1826 static void
1827 channel_handler_init_15(void)
1828 {
1829         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1830         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1831         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1832         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1833         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1834         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1835         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1836
1837         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1838         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1839         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1840         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1841         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1842         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1843 }
1844
1845 static void
1846 channel_handler_init(void)
1847 {
1848         int i;
1849
1850         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1851                 channel_pre[i] = NULL;
1852                 channel_post[i] = NULL;
1853         }
1854         if (compat20)
1855                 channel_handler_init_20();
1856         else if (compat13)
1857                 channel_handler_init_13();
1858         else
1859                 channel_handler_init_15();
1860 }
1861
1862 /* gc dead channels */
1863 static void
1864 channel_garbage_collect(Channel *c)
1865 {
1866         if (c == NULL)
1867                 return;
1868         if (c->detach_user != NULL) {
1869                 if (!chan_is_dead(c, c->detach_close))
1870                         return;
1871                 debug2("channel %d: gc: notify user", c->self);
1872                 c->detach_user(c->self, NULL);
1873                 /* if we still have a callback */
1874                 if (c->detach_user != NULL)
1875                         return;
1876                 debug2("channel %d: gc: user detached", c->self);
1877         }
1878         if (!chan_is_dead(c, 1))
1879                 return;
1880         debug2("channel %d: garbage collecting", c->self);
1881         channel_free(c);
1882 }
1883
1884 static void
1885 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1886 {
1887         static int did_init = 0;
1888         u_int i;
1889         Channel *c;
1890
1891         if (!did_init) {
1892                 channel_handler_init();
1893                 did_init = 1;
1894         }
1895         for (i = 0; i < channels_alloc; i++) {
1896                 c = channels[i];
1897                 if (c == NULL)
1898                         continue;
1899                 if (ftab[c->type] != NULL)
1900                         (*ftab[c->type])(c, readset, writeset);
1901                 channel_garbage_collect(c);
1902         }
1903 }
1904
1905 /*
1906  * Allocate/update select bitmasks and add any bits relevant to channels in
1907  * select bitmasks.
1908  */
1909 void
1910 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1911     u_int *nallocp, int rekeying)
1912 {
1913         u_int n, sz, nfdset;
1914
1915         n = MAX(*maxfdp, channel_max_fd);
1916
1917         nfdset = howmany(n+1, NFDBITS);
1918         /* Explicitly test here, because xrealloc isn't always called */
1919         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1920                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1921         sz = nfdset * sizeof(fd_mask);
1922
1923         /* perhaps check sz < nalloc/2 and shrink? */
1924         if (*readsetp == NULL || sz > *nallocp) {
1925                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1926                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1927                 *nallocp = sz;
1928         }
1929         *maxfdp = n;
1930         memset(*readsetp, 0, sz);
1931         memset(*writesetp, 0, sz);
1932
1933         if (!rekeying)
1934                 channel_handler(channel_pre, *readsetp, *writesetp);
1935 }
1936
1937 /*
1938  * After select, perform any appropriate operations for channels which have
1939  * events pending.
1940  */
1941 void
1942 channel_after_select(fd_set *readset, fd_set *writeset)
1943 {
1944         channel_handler(channel_post, readset, writeset);
1945 }
1946
1947
1948 /* If there is data to send to the connection, enqueue some of it now. */
1949 void
1950 channel_output_poll(void)
1951 {
1952         Channel *c;
1953         u_int i, len;
1954
1955         for (i = 0; i < channels_alloc; i++) {
1956                 c = channels[i];
1957                 if (c == NULL)
1958                         continue;
1959
1960                 /*
1961                  * We are only interested in channels that can have buffered
1962                  * incoming data.
1963                  */
1964                 if (compat13) {
1965                         if (c->type != SSH_CHANNEL_OPEN &&
1966                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1967                                 continue;
1968                 } else {
1969                         if (c->type != SSH_CHANNEL_OPEN)
1970                                 continue;
1971                 }
1972                 if (compat20 &&
1973                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1974                         /* XXX is this true? */
1975                         debug3("channel %d: will not send data after close", c->self);
1976                         continue;
1977                 }
1978
1979                 /* Get the amount of buffered data for this channel. */
1980                 if ((c->istate == CHAN_INPUT_OPEN ||
1981                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1982                     (len = buffer_len(&c->input)) > 0) {
1983                         if (c->datagram) {
1984                                 if (len > 0) {
1985                                         u_char *data;
1986                                         u_int dlen;
1987
1988                                         data = buffer_get_string(&c->input,
1989                                             &dlen);
1990                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1991                                         packet_put_int(c->remote_id);
1992                                         packet_put_string(data, dlen);
1993                                         packet_send();
1994                                         c->remote_window -= dlen + 4;
1995                                         xfree(data);
1996                                 }
1997                                 continue;
1998                         }
1999                         /*
2000                          * Send some data for the other side over the secure
2001                          * connection.
2002                          */
2003                         if (compat20) {
2004                                 if (len > c->remote_window)
2005                                         len = c->remote_window;
2006                                 if (len > c->remote_maxpacket)
2007                                         len = c->remote_maxpacket;
2008                         } else {
2009                                 if (packet_is_interactive()) {
2010                                         if (len > 1024)
2011                                                 len = 512;
2012                                 } else {
2013                                         /* Keep the packets at reasonable size. */
2014                                         if (len > packet_get_maxsize()/2)
2015                                                 len = packet_get_maxsize()/2;
2016                                 }
2017                         }
2018                         if (len > 0) {
2019                                 packet_start(compat20 ?
2020                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2021                                 packet_put_int(c->remote_id);
2022                                 packet_put_string(buffer_ptr(&c->input), len);
2023                                 packet_send();
2024                                 buffer_consume(&c->input, len);
2025                                 c->remote_window -= len;
2026                         }
2027                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2028                         if (compat13)
2029                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2030                         /*
2031                          * input-buffer is empty and read-socket shutdown:
2032                          * tell peer, that we will not send more data: send IEOF.
2033                          * hack for extended data: delay EOF if EFD still in use.
2034                          */
2035                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2036                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2037                                     c->self, c->efd, buffer_len(&c->extended));
2038                         else
2039                                 chan_ibuf_empty(c);
2040                 }
2041                 /* Send extended data, i.e. stderr */
2042                 if (compat20 &&
2043                     !(c->flags & CHAN_EOF_SENT) &&
2044                     c->remote_window > 0 &&
2045                     (len = buffer_len(&c->extended)) > 0 &&
2046                     c->extended_usage == CHAN_EXTENDED_READ) {
2047                         debug2("channel %d: rwin %u elen %u euse %d",
2048                             c->self, c->remote_window, buffer_len(&c->extended),
2049                             c->extended_usage);
2050                         if (len > c->remote_window)
2051                                 len = c->remote_window;
2052                         if (len > c->remote_maxpacket)
2053                                 len = c->remote_maxpacket;
2054                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2055                         packet_put_int(c->remote_id);
2056                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2057                         packet_put_string(buffer_ptr(&c->extended), len);
2058                         packet_send();
2059                         buffer_consume(&c->extended, len);
2060                         c->remote_window -= len;
2061                         debug2("channel %d: sent ext data %d", c->self, len);
2062                 }
2063         }
2064 }
2065
2066
2067 /* -- protocol input */
2068
2069 /* ARGSUSED */
2070 void
2071 channel_input_data(int type, u_int32_t seq, void *ctxt)
2072 {
2073         int id;
2074         char *data;
2075         u_int data_len;
2076         Channel *c;
2077
2078         /* Get the channel number and verify it. */
2079         id = packet_get_int();
2080         c = channel_lookup(id);
2081         if (c == NULL)
2082                 packet_disconnect("Received data for nonexistent channel %d.", id);
2083
2084         /* Ignore any data for non-open channels (might happen on close) */
2085         if (c->type != SSH_CHANNEL_OPEN &&
2086             c->type != SSH_CHANNEL_X11_OPEN)
2087                 return;
2088
2089         /* Get the data. */
2090         data = packet_get_string_ptr(&data_len);
2091
2092         /*
2093          * Ignore data for protocol > 1.3 if output end is no longer open.
2094          * For protocol 2 the sending side is reducing its window as it sends
2095          * data, so we must 'fake' consumption of the data in order to ensure
2096          * that window updates are sent back.  Otherwise the connection might
2097          * deadlock.
2098          */
2099         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2100                 if (compat20) {
2101                         c->local_window -= data_len;
2102                         c->local_consumed += data_len;
2103                 }
2104                 return;
2105         }
2106
2107         if (compat20) {
2108                 if (data_len > c->local_maxpacket) {
2109                         logit("channel %d: rcvd big packet %d, maxpack %d",
2110                             c->self, data_len, c->local_maxpacket);
2111                 }
2112                 if (data_len > c->local_window) {
2113                         logit("channel %d: rcvd too much data %d, win %d",
2114                             c->self, data_len, c->local_window);
2115                         return;
2116                 }
2117                 c->local_window -= data_len;
2118         }
2119         if (c->datagram)
2120                 buffer_put_string(&c->output, data, data_len);
2121         else
2122                 buffer_append(&c->output, data, data_len);
2123         packet_check_eom();
2124 }
2125
2126 /* ARGSUSED */
2127 void
2128 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2129 {
2130         int id;
2131         char *data;
2132         u_int data_len, tcode;
2133         Channel *c;
2134
2135         /* Get the channel number and verify it. */
2136         id = packet_get_int();
2137         c = channel_lookup(id);
2138
2139         if (c == NULL)
2140                 packet_disconnect("Received extended_data for bad channel %d.", id);
2141         if (c->type != SSH_CHANNEL_OPEN) {
2142                 logit("channel %d: ext data for non open", id);
2143                 return;
2144         }
2145         if (c->flags & CHAN_EOF_RCVD) {
2146                 if (datafellows & SSH_BUG_EXTEOF)
2147                         debug("channel %d: accepting ext data after eof", id);
2148                 else
2149                         packet_disconnect("Received extended_data after EOF "
2150                             "on channel %d.", id);
2151         }
2152         tcode = packet_get_int();
2153         if (c->efd == -1 ||
2154             c->extended_usage != CHAN_EXTENDED_WRITE ||
2155             tcode != SSH2_EXTENDED_DATA_STDERR) {
2156                 logit("channel %d: bad ext data", c->self);
2157                 return;
2158         }
2159         data = packet_get_string(&data_len);
2160         packet_check_eom();
2161         if (data_len > c->local_window) {
2162                 logit("channel %d: rcvd too much extended_data %d, win %d",
2163                     c->self, data_len, c->local_window);
2164                 xfree(data);
2165                 return;
2166         }
2167         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2168         c->local_window -= data_len;
2169         buffer_append(&c->extended, data, data_len);
2170         xfree(data);
2171 }
2172
2173 /* ARGSUSED */
2174 void
2175 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2176 {
2177         int id;
2178         Channel *c;
2179
2180         id = packet_get_int();
2181         packet_check_eom();
2182         c = channel_lookup(id);
2183         if (c == NULL)
2184                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2185         chan_rcvd_ieof(c);
2186
2187         /* XXX force input close */
2188         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2189                 debug("channel %d: FORCE input drain", c->self);
2190                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2191                 if (buffer_len(&c->input) == 0)
2192                         chan_ibuf_empty(c);
2193         }
2194
2195 }
2196
2197 /* ARGSUSED */
2198 void
2199 channel_input_close(int type, u_int32_t seq, void *ctxt)
2200 {
2201         int id;
2202         Channel *c;
2203
2204         id = packet_get_int();
2205         packet_check_eom();
2206         c = channel_lookup(id);
2207         if (c == NULL)
2208                 packet_disconnect("Received close for nonexistent channel %d.", id);
2209
2210         /*
2211          * Send a confirmation that we have closed the channel and no more
2212          * data is coming for it.
2213          */
2214         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2215         packet_put_int(c->remote_id);
2216         packet_send();
2217
2218         /*
2219          * If the channel is in closed state, we have sent a close request,
2220          * and the other side will eventually respond with a confirmation.
2221          * Thus, we cannot free the channel here, because then there would be
2222          * no-one to receive the confirmation.  The channel gets freed when
2223          * the confirmation arrives.
2224          */
2225         if (c->type != SSH_CHANNEL_CLOSED) {
2226                 /*
2227                  * Not a closed channel - mark it as draining, which will
2228                  * cause it to be freed later.
2229                  */
2230                 buffer_clear(&c->input);
2231                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2232         }
2233 }
2234
2235 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2236 /* ARGSUSED */
2237 void
2238 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2239 {
2240         int id = packet_get_int();
2241         Channel *c = channel_lookup(id);
2242
2243         packet_check_eom();
2244         if (c == NULL)
2245                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2246         chan_rcvd_oclose(c);
2247 }
2248
2249 /* ARGSUSED */
2250 void
2251 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2252 {
2253         int id = packet_get_int();
2254         Channel *c = channel_lookup(id);
2255
2256         packet_check_eom();
2257         if (c == NULL)
2258                 packet_disconnect("Received close confirmation for "
2259                     "out-of-range channel %d.", id);
2260         if (c->type != SSH_CHANNEL_CLOSED)
2261                 packet_disconnect("Received close confirmation for "
2262                     "non-closed channel %d (type %d).", id, c->type);
2263         channel_free(c);
2264 }
2265
2266 /* ARGSUSED */
2267 void
2268 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2269 {
2270         int id, remote_id;
2271         Channel *c;
2272
2273         id = packet_get_int();
2274         c = channel_lookup(id);
2275
2276         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2277                 packet_disconnect("Received open confirmation for "
2278                     "non-opening channel %d.", id);
2279         remote_id = packet_get_int();
2280         /* Record the remote channel number and mark that the channel is now open. */
2281         c->remote_id = remote_id;
2282         c->type = SSH_CHANNEL_OPEN;
2283
2284         if (compat20) {
2285                 c->remote_window = packet_get_int();
2286                 c->remote_maxpacket = packet_get_int();
2287                 if (c->open_confirm) {
2288                         debug2("callback start");
2289                         c->open_confirm(c->self, c->open_confirm_ctx);
2290                         debug2("callback done");
2291                 }
2292                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2293                     c->remote_window, c->remote_maxpacket);
2294         }
2295         packet_check_eom();
2296 }
2297
2298 static char *
2299 reason2txt(int reason)
2300 {
2301         switch (reason) {
2302         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2303                 return "administratively prohibited";
2304         case SSH2_OPEN_CONNECT_FAILED:
2305                 return "connect failed";
2306         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2307                 return "unknown channel type";
2308         case SSH2_OPEN_RESOURCE_SHORTAGE:
2309                 return "resource shortage";
2310         }
2311         return "unknown reason";
2312 }
2313
2314 /* ARGSUSED */
2315 void
2316 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2317 {
2318         int id, reason;
2319         char *msg = NULL, *lang = NULL;
2320         Channel *c;
2321
2322         id = packet_get_int();
2323         c = channel_lookup(id);
2324
2325         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2326                 packet_disconnect("Received open failure for "
2327                     "non-opening channel %d.", id);
2328         if (compat20) {
2329                 reason = packet_get_int();
2330                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2331                         msg  = packet_get_string(NULL);
2332                         lang = packet_get_string(NULL);
2333                 }
2334                 logit("channel %d: open failed: %s%s%s", id,
2335                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2336                 if (msg != NULL)
2337                         xfree(msg);
2338                 if (lang != NULL)
2339                         xfree(lang);
2340         }
2341         packet_check_eom();
2342         /* Schedule the channel for cleanup/deletion. */
2343         chan_mark_dead(c);
2344 }
2345
2346 /* ARGSUSED */
2347 void
2348 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2349 {
2350         Channel *c;
2351         int id;
2352         u_int adjust;
2353
2354         if (!compat20)
2355                 return;
2356
2357         /* Get the channel number and verify it. */
2358         id = packet_get_int();
2359         c = channel_lookup(id);
2360
2361         if (c == NULL) {
2362                 logit("Received window adjust for non-open channel %d.", id);
2363                 return;
2364         }
2365         adjust = packet_get_int();
2366         packet_check_eom();
2367         debug2("channel %d: rcvd adjust %u", id, adjust);
2368         c->remote_window += adjust;
2369 }
2370
2371 /* ARGSUSED */
2372 void
2373 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2374 {
2375         Channel *c = NULL;
2376         u_short host_port;
2377         char *host, *originator_string;
2378         int remote_id;
2379
2380         remote_id = packet_get_int();
2381         host = packet_get_string(NULL);
2382         host_port = packet_get_int();
2383
2384         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2385                 originator_string = packet_get_string(NULL);
2386         } else {
2387                 originator_string = xstrdup("unknown (remote did not supply name)");
2388         }
2389         packet_check_eom();
2390         c = channel_connect_to(host, host_port,
2391             "connected socket", originator_string);
2392         xfree(originator_string);
2393         xfree(host);
2394         if (c == NULL) {
2395                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2396                 packet_put_int(remote_id);
2397                 packet_send();
2398         } else
2399                 c->remote_id = remote_id;
2400 }
2401
2402 /* ARGSUSED */
2403 void
2404 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2405 {
2406         Channel *c;
2407         struct channel_confirm *cc;
2408         int id;
2409
2410         /* Reset keepalive timeout */
2411         keep_alive_timeouts = 0;
2412
2413         id = packet_get_int();
2414         packet_check_eom();
2415
2416         debug2("channel_input_status_confirm: type %d id %d", type, id);
2417
2418         if ((c = channel_lookup(id)) == NULL) {
2419                 logit("channel_input_status_confirm: %d: unknown", id);
2420                 return;
2421         }
2422         ;
2423         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2424                 return;
2425         cc->cb(type, c, cc->ctx);
2426         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2427         bzero(cc, sizeof(*cc));
2428         xfree(cc);
2429 }
2430
2431 /* -- tcp forwarding */
2432
2433 void
2434 channel_set_af(int af)
2435 {
2436         IPv4or6 = af;
2437 }
2438
2439 static int
2440 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2441     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2442 {
2443         Channel *c;
2444         int sock, r, success = 0, wildcard = 0, is_client;
2445         struct addrinfo hints, *ai, *aitop;
2446         const char *host, *addr;
2447         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2448
2449         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2450             listen_addr : host_to_connect;
2451         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2452
2453         if (host == NULL) {
2454                 error("No forward host name.");
2455                 return 0;
2456         }
2457         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2458                 error("Forward host name too long.");
2459                 return 0;
2460         }
2461
2462         /*
2463          * Determine whether or not a port forward listens to loopback,
2464          * specified address or wildcard. On the client, a specified bind
2465          * address will always override gateway_ports. On the server, a
2466          * gateway_ports of 1 (``yes'') will override the client's
2467          * specification and force a wildcard bind, whereas a value of 2
2468          * (``clientspecified'') will bind to whatever address the client
2469          * asked for.
2470          *
2471          * Special-case listen_addrs are:
2472          *
2473          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2474          * "" (empty string), "*"  -> wildcard v4/v6
2475          * "localhost"             -> loopback v4/v6
2476          */
2477         addr = NULL;
2478         if (listen_addr == NULL) {
2479                 /* No address specified: default to gateway_ports setting */
2480                 if (gateway_ports)
2481                         wildcard = 1;
2482         } else if (gateway_ports || is_client) {
2483                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2484                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2485                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2486                     (!is_client && gateway_ports == 1))
2487                         wildcard = 1;
2488                 else if (strcmp(listen_addr, "localhost") != 0)
2489                         addr = listen_addr;
2490         }
2491
2492         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2493             type, wildcard, (addr == NULL) ? "NULL" : addr);
2494
2495         /*
2496          * getaddrinfo returns a loopback address if the hostname is
2497          * set to NULL and hints.ai_flags is not AI_PASSIVE
2498          */
2499         memset(&hints, 0, sizeof(hints));
2500         hints.ai_family = IPv4or6;
2501         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2502         hints.ai_socktype = SOCK_STREAM;
2503         snprintf(strport, sizeof strport, "%d", listen_port);
2504         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2505                 if (addr == NULL) {
2506                         /* This really shouldn't happen */
2507                         packet_disconnect("getaddrinfo: fatal error: %s",
2508                             ssh_gai_strerror(r));
2509                 } else {
2510                         error("channel_setup_fwd_listener: "
2511                             "getaddrinfo(%.64s): %s", addr,
2512                             ssh_gai_strerror(r));
2513                 }
2514                 return 0;
2515         }
2516
2517         for (ai = aitop; ai; ai = ai->ai_next) {
2518                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2519                         continue;
2520                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2521                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2522                         error("channel_setup_fwd_listener: getnameinfo failed");
2523                         continue;
2524                 }
2525                 /* Create a port to listen for the host. */
2526                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2527                 if (sock < 0) {
2528                         /* this is no error since kernel may not support ipv6 */
2529                         verbose("socket: %.100s", strerror(errno));
2530                         continue;
2531                 }
2532
2533                 channel_set_reuseaddr(sock);
2534
2535                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2536
2537                 /* Bind the socket to the address. */
2538                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2539                         /* address can be in use ipv6 address is already bound */
2540                         if (!ai->ai_next)
2541                                 error("bind: %.100s", strerror(errno));
2542                         else
2543                                 verbose("bind: %.100s", strerror(errno));
2544
2545                         close(sock);
2546                         continue;
2547                 }
2548                 /* Start listening for connections on the socket. */
2549                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2550                         error("listen: %.100s", strerror(errno));
2551                         close(sock);
2552                         continue;
2553                 }
2554                 /* Allocate a channel number for the socket. */
2555                 c = channel_new("port listener", type, sock, sock, -1,
2556                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2557                     0, "port listener", 1);
2558                 strlcpy(c->path, host, sizeof(c->path));
2559                 c->host_port = port_to_connect;
2560                 c->listening_port = listen_port;
2561                 success = 1;
2562         }
2563         if (success == 0)
2564                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2565                     listen_port);
2566         freeaddrinfo(aitop);
2567         return success;
2568 }
2569
2570 int
2571 channel_cancel_rport_listener(const char *host, u_short port)
2572 {
2573         u_int i;
2574         int found = 0;
2575
2576         for (i = 0; i < channels_alloc; i++) {
2577                 Channel *c = channels[i];
2578
2579                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2580                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2581                     c->listening_port == port) {
2582                         debug2("%s: close channel %d", __func__, i);
2583                         channel_free(c);
2584                         found = 1;
2585                 }
2586         }
2587
2588         return (found);
2589 }
2590
2591 /* protocol local port fwd, used by ssh (and sshd in v1) */
2592 int
2593 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2594     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2595 {
2596         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2597             listen_host, listen_port, host_to_connect, port_to_connect,
2598             gateway_ports);
2599 }
2600
2601 /* protocol v2 remote port fwd, used by sshd */
2602 int
2603 channel_setup_remote_fwd_listener(const char *listen_address,
2604     u_short listen_port, int gateway_ports)
2605 {
2606         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2607             listen_address, listen_port, NULL, 0, gateway_ports);
2608 }
2609
2610 /*
2611  * Initiate forwarding of connections to port "port" on remote host through
2612  * the secure channel to host:port from local side.
2613  */
2614
2615 int
2616 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2617     const char *host_to_connect, u_short port_to_connect)
2618 {
2619         int type, success = 0;
2620
2621         /* Record locally that connection to this host/port is permitted. */
2622         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2623                 fatal("channel_request_remote_forwarding: too many forwards");
2624
2625         /* Send the forward request to the remote side. */
2626         if (compat20) {
2627                 const char *address_to_bind;
2628                 if (listen_host == NULL) {
2629                         if (datafellows & SSH_BUG_RFWD_ADDR)
2630                                 address_to_bind = "127.0.0.1";
2631                         else
2632                                 address_to_bind = "localhost";
2633                 } else if (*listen_host == '\0' ||
2634                            strcmp(listen_host, "*") == 0) {
2635                         if (datafellows & SSH_BUG_RFWD_ADDR)
2636                                 address_to_bind = "0.0.0.0";
2637                         else
2638                                 address_to_bind = "";
2639                 } else
2640                         address_to_bind = listen_host;
2641
2642                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2643                 packet_put_cstring("tcpip-forward");
2644                 packet_put_char(1);                     /* boolean: want reply */
2645                 packet_put_cstring(address_to_bind);
2646                 packet_put_int(listen_port);
2647                 packet_send();
2648                 packet_write_wait();
2649                 /* Assume that server accepts the request */
2650                 success = 1;
2651         } else {
2652                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2653                 packet_put_int(listen_port);
2654                 packet_put_cstring(host_to_connect);
2655                 packet_put_int(port_to_connect);
2656                 packet_send();
2657                 packet_write_wait();
2658
2659                 /* Wait for response from the remote side. */
2660                 type = packet_read();
2661                 switch (type) {
2662                 case SSH_SMSG_SUCCESS:
2663                         success = 1;
2664                         break;
2665                 case SSH_SMSG_FAILURE:
2666                         break;
2667                 default:
2668                         /* Unknown packet */
2669                         packet_disconnect("Protocol error for port forward request:"
2670                             "received packet type %d.", type);
2671                 }
2672         }
2673         if (success) {
2674                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2675                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2676                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2677                 num_permitted_opens++;
2678         }
2679         return (success ? 0 : -1);
2680 }
2681
2682 /*
2683  * Request cancellation of remote forwarding of connection host:port from
2684  * local side.
2685  */
2686 void
2687 channel_request_rforward_cancel(const char *host, u_short port)
2688 {
2689         int i;
2690
2691         if (!compat20)
2692                 return;
2693
2694         for (i = 0; i < num_permitted_opens; i++) {
2695                 if (permitted_opens[i].host_to_connect != NULL &&
2696                     permitted_opens[i].listen_port == port)
2697                         break;
2698         }
2699         if (i >= num_permitted_opens) {
2700                 debug("%s: requested forward not found", __func__);
2701                 return;
2702         }
2703         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2704         packet_put_cstring("cancel-tcpip-forward");
2705         packet_put_char(0);
2706         packet_put_cstring(host == NULL ? "" : host);
2707         packet_put_int(port);
2708         packet_send();
2709
2710         permitted_opens[i].listen_port = 0;
2711         permitted_opens[i].port_to_connect = 0;
2712         xfree(permitted_opens[i].host_to_connect);
2713         permitted_opens[i].host_to_connect = NULL;
2714 }
2715
2716 /*
2717  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2718  * listening for the port, and sends back a success reply (or disconnect
2719  * message if there was an error).
2720  */
2721 int
2722 channel_input_port_forward_request(int is_root, int gateway_ports)
2723 {
2724         u_short port, host_port;
2725         int success = 0;
2726         char *hostname;
2727
2728         /* Get arguments from the packet. */
2729         port = packet_get_int();
2730         hostname = packet_get_string(NULL);
2731         host_port = packet_get_int();
2732
2733 #ifndef HAVE_CYGWIN
2734         /*
2735          * Check that an unprivileged user is not trying to forward a
2736          * privileged port.
2737          */
2738         if (port < IPPORT_RESERVED && !is_root)
2739                 packet_disconnect(
2740                     "Requested forwarding of port %d but user is not root.",
2741                     port);
2742         if (host_port == 0)
2743                 packet_disconnect("Dynamic forwarding denied.");
2744 #endif
2745
2746         /* Initiate forwarding */
2747         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2748             host_port, gateway_ports);
2749
2750         /* Free the argument string. */
2751         xfree(hostname);
2752
2753         return (success ? 0 : -1);
2754 }
2755
2756 /*
2757  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2758  * usually called by the server, because the user could connect to any port
2759  * anyway, and the server has no way to know but to trust the client anyway.
2760  */
2761 void
2762 channel_permit_all_opens(void)
2763 {
2764         if (num_permitted_opens == 0)
2765                 all_opens_permitted = 1;
2766 }
2767
2768 void
2769 channel_add_permitted_opens(char *host, int port)
2770 {
2771         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2772                 fatal("channel_add_permitted_opens: too many forwards");
2773         debug("allow port forwarding to host %s port %d", host, port);
2774
2775         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2776         permitted_opens[num_permitted_opens].port_to_connect = port;
2777         num_permitted_opens++;
2778
2779         all_opens_permitted = 0;
2780 }
2781
2782 int
2783 channel_add_adm_permitted_opens(char *host, int port)
2784 {
2785         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2786                 fatal("channel_add_adm_permitted_opens: too many forwards");
2787         debug("config allows port forwarding to host %s port %d", host, port);
2788
2789         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2790              = xstrdup(host);
2791         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2792         return ++num_adm_permitted_opens;
2793 }
2794
2795 void
2796 channel_clear_permitted_opens(void)
2797 {
2798         int i;
2799
2800         for (i = 0; i < num_permitted_opens; i++)
2801                 if (permitted_opens[i].host_to_connect != NULL)
2802                         xfree(permitted_opens[i].host_to_connect);
2803         num_permitted_opens = 0;
2804 }
2805
2806 void
2807 channel_clear_adm_permitted_opens(void)
2808 {
2809         int i;
2810
2811         for (i = 0; i < num_adm_permitted_opens; i++)
2812                 if (permitted_adm_opens[i].host_to_connect != NULL)
2813                         xfree(permitted_adm_opens[i].host_to_connect);
2814         num_adm_permitted_opens = 0;
2815 }
2816
2817 void
2818 channel_print_adm_permitted_opens(void)
2819 {
2820         int i;
2821
2822         printf("permitopen");
2823         if (num_adm_permitted_opens == 0) {
2824                 printf(" any\n");
2825                 return;
2826         }
2827         for (i = 0; i < num_adm_permitted_opens; i++)
2828                 if (permitted_adm_opens[i].host_to_connect != NULL)
2829                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
2830                             permitted_adm_opens[i].port_to_connect);
2831         printf("\n");
2832 }
2833
2834 /* Try to start non-blocking connect to next host in cctx list */
2835 static int
2836 connect_next(struct channel_connect *cctx)
2837 {
2838         int sock, saved_errno;
2839         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2840
2841         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
2842                 if (cctx->ai->ai_family != AF_INET &&
2843                     cctx->ai->ai_family != AF_INET6)
2844                         continue;
2845                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
2846                     ntop, sizeof(ntop), strport, sizeof(strport),
2847                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2848                         error("connect_next: getnameinfo failed");
2849                         continue;
2850                 }
2851                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
2852                     cctx->ai->ai_protocol)) == -1) {
2853                         if (cctx->ai->ai_next == NULL)
2854                                 error("socket: %.100s", strerror(errno));
2855                         else
2856                                 verbose("socket: %.100s", strerror(errno));
2857                         continue;
2858                 }
2859                 if (set_nonblock(sock) == -1)
2860                         fatal("%s: set_nonblock(%d)", __func__, sock);
2861                 if (connect(sock, cctx->ai->ai_addr,
2862                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
2863                         debug("connect_next: host %.100s ([%.100s]:%s): "
2864                             "%.100s", cctx->host, ntop, strport,
2865                             strerror(errno));
2866                         saved_errno = errno;
2867                         close(sock);
2868                         errno = saved_errno;
2869                         continue;       /* fail -- try next */
2870                 }
2871                 debug("connect_next: host %.100s ([%.100s]:%s) "
2872                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
2873                 cctx->ai = cctx->ai->ai_next;
2874                 set_nodelay(sock);
2875                 return sock;
2876         }
2877         return -1;
2878 }
2879
2880 static void
2881 channel_connect_ctx_free(struct channel_connect *cctx)
2882 {
2883         xfree(cctx->host);
2884         if (cctx->aitop)
2885                 freeaddrinfo(cctx->aitop);
2886         bzero(cctx, sizeof(*cctx));
2887         cctx->host = NULL;
2888         cctx->ai = cctx->aitop = NULL;
2889 }
2890
2891 /* Return CONNECTING channel to remote host, port */
2892 static Channel *
2893 connect_to(const char *host, u_short port, char *ctype, char *rname)
2894 {
2895         struct addrinfo hints;
2896         int gaierr;
2897         int sock = -1;
2898         char strport[NI_MAXSERV];
2899         struct channel_connect cctx;
2900         Channel *c;
2901
2902         memset(&cctx, 0, sizeof(cctx));
2903         memset(&hints, 0, sizeof(hints));
2904         hints.ai_family = IPv4or6;
2905         hints.ai_socktype = SOCK_STREAM;
2906         snprintf(strport, sizeof strport, "%d", port);
2907         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
2908                 error("connect_to %.100s: unknown host (%s)", host,
2909                     ssh_gai_strerror(gaierr));
2910                 return NULL;
2911         }
2912
2913         cctx.host = xstrdup(host);
2914         cctx.port = port;
2915         cctx.ai = cctx.aitop;
2916
2917         if ((sock = connect_next(&cctx)) == -1) {
2918                 error("connect to %.100s port %d failed: %s",
2919                     host, port, strerror(errno));
2920                 channel_connect_ctx_free(&cctx);
2921                 return NULL;
2922         }
2923         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
2924             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
2925         c->connect_ctx = cctx;
2926         return c;
2927 }
2928
2929 Channel *
2930 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
2931 {
2932         int i;
2933
2934         for (i = 0; i < num_permitted_opens; i++) {
2935                 if (permitted_opens[i].host_to_connect != NULL &&
2936                     permitted_opens[i].listen_port == listen_port) {
2937                         return connect_to(
2938                             permitted_opens[i].host_to_connect,
2939                             permitted_opens[i].port_to_connect, ctype, rname);
2940                 }
2941         }
2942         error("WARNING: Server requests forwarding for unknown listen_port %d",
2943             listen_port);
2944         return NULL;
2945 }
2946
2947 /* Check if connecting to that port is permitted and connect. */
2948 Channel *
2949 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
2950 {
2951         int i, permit, permit_adm = 1;
2952
2953         permit = all_opens_permitted;
2954         if (!permit) {
2955                 for (i = 0; i < num_permitted_opens; i++)
2956                         if (permitted_opens[i].host_to_connect != NULL &&
2957                             permitted_opens[i].port_to_connect == port &&
2958                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2959                                 permit = 1;
2960         }
2961
2962         if (num_adm_permitted_opens > 0) {
2963                 permit_adm = 0;
2964                 for (i = 0; i < num_adm_permitted_opens; i++)
2965                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2966                             permitted_adm_opens[i].port_to_connect == port &&
2967                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2968                             == 0)
2969                                 permit_adm = 1;
2970         }
2971
2972         if (!permit || !permit_adm) {
2973                 logit("Received request to connect to host %.100s port %d, "
2974                     "but the request was denied.", host, port);
2975                 return NULL;
2976         }
2977         return connect_to(host, port, ctype, rname);
2978 }
2979
2980 void
2981 channel_send_window_changes(void)
2982 {
2983         u_int i;
2984         struct winsize ws;
2985
2986         for (i = 0; i < channels_alloc; i++) {
2987                 if (channels[i] == NULL || !channels[i]->client_tty ||
2988                     channels[i]->type != SSH_CHANNEL_OPEN)
2989                         continue;
2990                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2991                         continue;
2992                 channel_request_start(i, "window-change", 0);
2993                 packet_put_int((u_int)ws.ws_col);
2994                 packet_put_int((u_int)ws.ws_row);
2995                 packet_put_int((u_int)ws.ws_xpixel);
2996                 packet_put_int((u_int)ws.ws_ypixel);
2997                 packet_send();
2998         }
2999 }
3000
3001 /* -- X11 forwarding */
3002
3003 /*
3004  * Creates an internet domain socket for listening for X11 connections.
3005  * Returns 0 and a suitable display number for the DISPLAY variable
3006  * stored in display_numberp , or -1 if an error occurs.
3007  */
3008 int
3009 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3010     int single_connection, u_int *display_numberp, int **chanids)
3011 {
3012         Channel *nc = NULL;
3013         int display_number, sock;
3014         u_short port;
3015         struct addrinfo hints, *ai, *aitop;
3016         char strport[NI_MAXSERV];
3017         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3018
3019         if (chanids == NULL)
3020                 return -1;
3021
3022         for (display_number = x11_display_offset;
3023             display_number < MAX_DISPLAYS;
3024             display_number++) {
3025                 port = 6000 + display_number;
3026                 memset(&hints, 0, sizeof(hints));
3027                 hints.ai_family = IPv4or6;
3028                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3029                 hints.ai_socktype = SOCK_STREAM;
3030                 snprintf(strport, sizeof strport, "%d", port);
3031                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3032                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3033                         return -1;
3034                 }
3035                 for (ai = aitop; ai; ai = ai->ai_next) {
3036                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3037                                 continue;
3038                         sock = socket(ai->ai_family, ai->ai_socktype,
3039                             ai->ai_protocol);
3040                         if (sock < 0) {
3041                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3042                                         error("socket: %.100s", strerror(errno));
3043                                         freeaddrinfo(aitop);
3044                                         return -1;
3045                                 } else {
3046                                         debug("x11_create_display_inet: Socket family %d not supported",
3047                                                  ai->ai_family);
3048                                         continue;
3049                                 }
3050                         }
3051 #ifdef IPV6_V6ONLY
3052                         if (ai->ai_family == AF_INET6) {
3053                                 int on = 1;
3054                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
3055                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
3056                         }
3057 #endif
3058                         if (x11_use_localhost)
3059                                 channel_set_reuseaddr(sock);
3060                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3061                                 debug2("bind port %d: %.100s", port, strerror(errno));
3062                                 close(sock);
3063
3064                                 for (n = 0; n < num_socks; n++) {
3065                                         close(socks[n]);
3066                                 }
3067                                 num_socks = 0;
3068                                 break;
3069                         }
3070                         socks[num_socks++] = sock;
3071                         if (num_socks == NUM_SOCKS)
3072                                 break;
3073                 }
3074                 freeaddrinfo(aitop);
3075                 if (num_socks > 0)
3076                         break;
3077         }
3078         if (display_number >= MAX_DISPLAYS) {
3079                 error("Failed to allocate internet-domain X11 display socket.");
3080                 return -1;
3081         }
3082         /* Start listening for connections on the socket. */
3083         for (n = 0; n < num_socks; n++) {
3084                 sock = socks[n];
3085                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3086                         error("listen: %.100s", strerror(errno));
3087                         close(sock);
3088                         return -1;
3089                 }
3090         }
3091
3092         /* Allocate a channel for each socket. */
3093         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3094         for (n = 0; n < num_socks; n++) {
3095                 sock = socks[n];
3096                 nc = channel_new("x11 listener",
3097                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3098                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3099                     0, "X11 inet listener", 1);
3100                 nc->single_connection = single_connection;
3101                 (*chanids)[n] = nc->self;
3102         }
3103         (*chanids)[n] = -1;
3104
3105         /* Return the display number for the DISPLAY environment variable. */
3106         *display_numberp = display_number;
3107         return (0);
3108 }
3109
3110 static int
3111 connect_local_xsocket_path(const char *pathname)
3112 {
3113         int sock;
3114         struct sockaddr_un addr;
3115
3116         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3117         if (sock < 0)
3118                 error("socket: %.100s", strerror(errno));
3119         memset(&addr, 0, sizeof(addr));
3120         addr.sun_family = AF_UNIX;
3121         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3122         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3123                 return sock;
3124         close(sock);
3125         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3126         return -1;
3127 }
3128
3129 static int
3130 connect_local_xsocket(u_int dnr)
3131 {
3132         char buf[1024];
3133         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3134         return connect_local_xsocket_path(buf);
3135 }
3136
3137 int
3138 x11_connect_display(void)
3139 {
3140         u_int display_number;
3141         const char *display;
3142         char buf[1024], *cp;
3143         struct addrinfo hints, *ai, *aitop;
3144         char strport[NI_MAXSERV];
3145         int gaierr, sock = 0;
3146
3147         /* Try to open a socket for the local X server. */
3148         display = getenv("DISPLAY");
3149         if (!display) {
3150                 error("DISPLAY not set.");
3151                 return -1;
3152         }
3153         /*
3154          * Now we decode the value of the DISPLAY variable and make a
3155          * connection to the real X server.
3156          */
3157
3158         /* Check if the display is from launchd. */
3159 #ifdef __APPLE__
3160         if (strncmp(display, "/tmp/launch", 11) == 0) {
3161                 sock = connect_local_xsocket_path(display);
3162                 if (sock < 0)
3163                         return -1;
3164
3165                 /* OK, we now have a connection to the display. */
3166                 return sock;
3167         }
3168 #endif
3169         /*
3170          * Check if it is a unix domain socket.  Unix domain displays are in
3171          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3172          */
3173         if (strncmp(display, "unix:", 5) == 0 ||
3174             display[0] == ':') {
3175                 /* Connect to the unix domain socket. */
3176                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3177                         error("Could not parse display number from DISPLAY: %.100s",
3178                             display);
3179                         return -1;
3180                 }
3181                 /* Create a socket. */
3182                 sock = connect_local_xsocket(display_number);
3183                 if (sock < 0)
3184                         return -1;
3185
3186                 /* OK, we now have a connection to the display. */
3187                 return sock;
3188         }
3189         /*
3190          * Connect to an inet socket.  The DISPLAY value is supposedly
3191          * hostname:d[.s], where hostname may also be numeric IP address.
3192          */
3193         strlcpy(buf, display, sizeof(buf));
3194         cp = strchr(buf, ':');
3195         if (!cp) {
3196                 error("Could not find ':' in DISPLAY: %.100s", display);
3197                 return -1;
3198         }
3199         *cp = 0;
3200         /* buf now contains the host name.  But first we parse the display number. */
3201         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3202                 error("Could not parse display number from DISPLAY: %.100s",
3203                     display);
3204                 return -1;
3205         }
3206
3207         /* Look up the host address */
3208         memset(&hints, 0, sizeof(hints));
3209         hints.ai_family = IPv4or6;
3210         hints.ai_socktype = SOCK_STREAM;
3211         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3212         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3213                 error("%.100s: unknown host. (%s)", buf,
3214                 ssh_gai_strerror(gaierr));
3215                 return -1;
3216         }
3217         for (ai = aitop; ai; ai = ai->ai_next) {
3218                 /* Create a socket. */
3219                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3220                 if (sock < 0) {
3221                         debug2("socket: %.100s", strerror(errno));
3222                         continue;
3223                 }
3224                 /* Connect it to the display. */
3225                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3226                         debug2("connect %.100s port %u: %.100s", buf,
3227                             6000 + display_number, strerror(errno));
3228                         close(sock);
3229                         continue;
3230                 }
3231                 /* Success */
3232                 break;
3233         }
3234         freeaddrinfo(aitop);
3235         if (!ai) {
3236                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3237                     strerror(errno));
3238                 return -1;
3239         }
3240         set_nodelay(sock);
3241         return sock;
3242 }
3243
3244 /*
3245  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3246  * the remote channel number.  We should do whatever we want, and respond
3247  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3248  */
3249
3250 /* ARGSUSED */
3251 void
3252 x11_input_open(int type, u_int32_t seq, void *ctxt)
3253 {
3254         Channel *c = NULL;
3255         int remote_id, sock = 0;
3256         char *remote_host;
3257
3258         debug("Received X11 open request.");
3259
3260         remote_id = packet_get_int();
3261
3262         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3263                 remote_host = packet_get_string(NULL);
3264         } else {
3265                 remote_host = xstrdup("unknown (remote did not supply name)");
3266         }
3267         packet_check_eom();
3268
3269         /* Obtain a connection to the real X display. */
3270         sock = x11_connect_display();
3271         if (sock != -1) {
3272                 /* Allocate a channel for this connection. */
3273                 c = channel_new("connected x11 socket",
3274                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3275                     remote_host, 1);
3276                 c->remote_id = remote_id;
3277                 c->force_drain = 1;
3278         }
3279         xfree(remote_host);
3280         if (c == NULL) {
3281                 /* Send refusal to the remote host. */
3282                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3283                 packet_put_int(remote_id);
3284         } else {
3285                 /* Send a confirmation to the remote host. */
3286                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3287                 packet_put_int(remote_id);
3288                 packet_put_int(c->self);
3289         }
3290         packet_send();
3291 }
3292
3293 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3294 /* ARGSUSED */
3295 void
3296 deny_input_open(int type, u_int32_t seq, void *ctxt)
3297 {
3298         int rchan = packet_get_int();
3299
3300         switch (type) {
3301         case SSH_SMSG_AGENT_OPEN:
3302                 error("Warning: ssh server tried agent forwarding.");
3303                 break;
3304         case SSH_SMSG_X11_OPEN:
3305                 error("Warning: ssh server tried X11 forwarding.");
3306                 break;
3307         default:
3308                 error("deny_input_open: type %d", type);
3309                 break;
3310         }
3311         error("Warning: this is probably a break-in attempt by a malicious server.");
3312         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3313         packet_put_int(rchan);
3314         packet_send();
3315 }
3316
3317 /*
3318  * Requests forwarding of X11 connections, generates fake authentication
3319  * data, and enables authentication spoofing.
3320  * This should be called in the client only.
3321  */
3322 void
3323 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3324     const char *proto, const char *data)
3325 {
3326         u_int data_len = (u_int) strlen(data) / 2;
3327         u_int i, value;
3328         char *new_data;
3329         int screen_number;
3330         const char *cp;
3331         u_int32_t rnd = 0;
3332
3333         if (x11_saved_display == NULL)
3334                 x11_saved_display = xstrdup(disp);
3335         else if (strcmp(disp, x11_saved_display) != 0) {
3336                 error("x11_request_forwarding_with_spoofing: different "
3337                     "$DISPLAY already forwarded");
3338                 return;
3339         }
3340
3341         cp = strchr(disp, ':');
3342         if (cp)
3343                 cp = strchr(cp, '.');
3344         if (cp)
3345                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3346         else
3347                 screen_number = 0;
3348
3349         if (x11_saved_proto == NULL) {
3350                 /* Save protocol name. */
3351                 x11_saved_proto = xstrdup(proto);
3352                 /*
3353                  * Extract real authentication data and generate fake data
3354                  * of the same length.
3355                  */
3356                 x11_saved_data = xmalloc(data_len);
3357                 x11_fake_data = xmalloc(data_len);
3358                 for (i = 0; i < data_len; i++) {
3359                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3360                                 fatal("x11_request_forwarding: bad "
3361                                     "authentication data: %.100s", data);
3362                         if (i % 4 == 0)
3363                                 rnd = arc4random();
3364                         x11_saved_data[i] = value;
3365                         x11_fake_data[i] = rnd & 0xff;
3366                         rnd >>= 8;
3367                 }
3368                 x11_saved_data_len = data_len;
3369                 x11_fake_data_len = data_len;
3370         }
3371
3372         /* Convert the fake data into hex. */
3373         new_data = tohex(x11_fake_data, data_len);
3374
3375         /* Send the request packet. */
3376         if (compat20) {
3377                 channel_request_start(client_session_id, "x11-req", 0);
3378                 packet_put_char(0);     /* XXX bool single connection */
3379         } else {
3380                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3381         }
3382         packet_put_cstring(proto);
3383         packet_put_cstring(new_data);
3384         packet_put_int(screen_number);
3385         packet_send();
3386         packet_write_wait();
3387         xfree(new_data);
3388 }
3389
3390
3391 /* -- agent forwarding */
3392
3393 /* Sends a message to the server to request authentication fd forwarding. */
3394
3395 void
3396 auth_request_forwarding(void)
3397 {
3398         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3399         packet_send();
3400         packet_write_wait();
3401 }