crypto/openssh-5/channels.c

   1 /* $OpenBSD: channels.c,v 1.286 2008/07/16 11:52:19 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_comfirm: %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;
 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         for (found = 0, i = len; i < have; i++) {
1000                 if (p[i] == '\0') {
1001                         found = 1;
1002                         break;
1003                 }
1004                 if (i > 1024) {
1005                         /* the peer is probably sending garbage */
1006                         debug("channel %d: decode socks4: too long",
1007                             c->self);
1008                         return -1;
1009                 }
1010         }
1011         if (!found)
1012                 return 0;
1013         buffer_get(&c->input, (char *)&s4_req.version, 1);
1014         buffer_get(&c->input, (char *)&s4_req.command, 1);
1015         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1016         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1017         have = buffer_len(&c->input);
1018         p = buffer_ptr(&c->input);
1019         len = strlen(p);
1020         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1021         if (len > have)
1022                 fatal("channel %d: decode socks4: len %d > have %d",
1023                     c->self, len, have);
1024         strlcpy(username, p, sizeof(username));
1025         buffer_consume(&c->input, len);
1026         buffer_consume(&c->input, 1);           /* trailing '\0' */
1027
1028         host = inet_ntoa(s4_req.dest_addr);
1029         strlcpy(c->path, host, sizeof(c->path));
1030         c->host_port = ntohs(s4_req.dest_port);
1031
1032         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1033             c->self, host, c->host_port, s4_req.command);
1034
1035         if (s4_req.command != 1) {
1036                 debug("channel %d: cannot handle: socks4 cn %d",
1037                     c->self, s4_req.command);
1038                 return -1;
1039         }
1040         s4_rsp.version = 0;                     /* vn: 0 for reply */
1041         s4_rsp.command = 90;                    /* cd: req granted */
1042         s4_rsp.dest_port = 0;                   /* ignored */
1043         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1044         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1045         return 1;
1046 }
1047
1048 /* try to decode a socks5 header */
1049 #define SSH_SOCKS5_AUTHDONE     0x1000
1050 #define SSH_SOCKS5_NOAUTH       0x00
1051 #define SSH_SOCKS5_IPV4         0x01
1052 #define SSH_SOCKS5_DOMAIN       0x03
1053 #define SSH_SOCKS5_IPV6         0x04
1054 #define SSH_SOCKS5_CONNECT      0x01
1055 #define SSH_SOCKS5_SUCCESS      0x00
1056
1057 /* ARGSUSED */
1058 static int
1059 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1060 {
1061         struct {
1062                 u_int8_t version;
1063                 u_int8_t command;
1064                 u_int8_t reserved;
1065                 u_int8_t atyp;
1066         } s5_req, s5_rsp;
1067         u_int16_t dest_port;
1068         u_char *p, dest_addr[255+1];
1069         u_int have, need, i, found, nmethods, addrlen, af;
1070
1071         debug2("channel %d: decode socks5", c->self);
1072         p = buffer_ptr(&c->input);
1073         if (p[0] != 0x05)
1074                 return -1;
1075         have = buffer_len(&c->input);
1076         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1077                 /* format: ver | nmethods | methods */
1078                 if (have < 2)
1079                         return 0;
1080                 nmethods = p[1];
1081                 if (have < nmethods + 2)
1082                         return 0;
1083                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1084                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1085                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1086                                 found = 1;
1087                                 break;
1088                         }
1089                 }
1090                 if (!found) {
1091                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1092                             c->self);
1093                         return -1;
1094                 }
1095                 buffer_consume(&c->input, nmethods + 2);
1096                 buffer_put_char(&c->output, 0x05);              /* version */
1097                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1098                 FD_SET(c->sock, writeset);
1099                 c->flags |= SSH_SOCKS5_AUTHDONE;
1100                 debug2("channel %d: socks5 auth done", c->self);
1101                 return 0;                               /* need more */
1102         }
1103         debug2("channel %d: socks5 post auth", c->self);
1104         if (have < sizeof(s5_req)+1)
1105                 return 0;                       /* need more */
1106         memcpy(&s5_req, p, sizeof(s5_req));
1107         if (s5_req.version != 0x05 ||
1108             s5_req.command != SSH_SOCKS5_CONNECT ||
1109             s5_req.reserved != 0x00) {
1110                 debug2("channel %d: only socks5 connect supported", c->self);
1111                 return -1;
1112         }
1113         switch (s5_req.atyp){
1114         case SSH_SOCKS5_IPV4:
1115                 addrlen = 4;
1116                 af = AF_INET;
1117                 break;
1118         case SSH_SOCKS5_DOMAIN:
1119                 addrlen = p[sizeof(s5_req)];
1120                 af = -1;
1121                 break;
1122         case SSH_SOCKS5_IPV6:
1123                 addrlen = 16;
1124                 af = AF_INET6;
1125                 break;
1126         default:
1127                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1128                 return -1;
1129         }
1130         need = sizeof(s5_req) + addrlen + 2;
1131         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1132                 need++;
1133         if (have < need)
1134                 return 0;
1135         buffer_consume(&c->input, sizeof(s5_req));
1136         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1137                 buffer_consume(&c->input, 1);    /* host string length */
1138         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1139         buffer_get(&c->input, (char *)&dest_port, 2);
1140         dest_addr[addrlen] = '\0';
1141         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1142                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1143         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1144                 return -1;
1145         c->host_port = ntohs(dest_port);
1146
1147         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1148             c->self, c->path, c->host_port, s5_req.command);
1149
1150         s5_rsp.version = 0x05;
1151         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1152         s5_rsp.reserved = 0;                    /* ignored */
1153         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1154         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1155         dest_port = 0;                          /* ignored */
1156
1157         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1158         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1159         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1160         return 1;
1161 }
1162
1163 /* dynamic port forwarding */
1164 static void
1165 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1166 {
1167         u_char *p;
1168         u_int have;
1169         int ret;
1170
1171         have = buffer_len(&c->input);
1172         c->delayed = 0;
1173         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1174         /* buffer_dump(&c->input); */
1175         /* check if the fixed size part of the packet is in buffer. */
1176         if (have < 3) {
1177                 /* need more */
1178                 FD_SET(c->sock, readset);
1179                 return;
1180         }
1181         /* try to guess the protocol */
1182         p = buffer_ptr(&c->input);
1183         switch (p[0]) {
1184         case 0x04:
1185                 ret = channel_decode_socks4(c, readset, writeset);
1186                 break;
1187         case 0x05:
1188                 ret = channel_decode_socks5(c, readset, writeset);
1189                 break;
1190         default:
1191                 ret = -1;
1192                 break;
1193         }
1194         if (ret < 0) {
1195                 chan_mark_dead(c);
1196         } else if (ret == 0) {
1197                 debug2("channel %d: pre_dynamic: need more", c->self);
1198                 /* need more */
1199                 FD_SET(c->sock, readset);
1200         } else {
1201                 /* switch to the next state */
1202                 c->type = SSH_CHANNEL_OPENING;
1203                 port_open_helper(c, "direct-tcpip");
1204         }
1205 }
1206
1207 /* This is our fake X11 server socket. */
1208 /* ARGSUSED */
1209 static void
1210 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1211 {
1212         Channel *nc;
1213         struct sockaddr_storage addr;
1214         int newsock;
1215         socklen_t addrlen;
1216         char buf[16384], *remote_ipaddr;
1217         int remote_port;
1218
1219         if (FD_ISSET(c->sock, readset)) {
1220                 debug("X11 connection requested.");
1221                 addrlen = sizeof(addr);
1222                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1223                 if (c->single_connection) {
1224                         debug2("single_connection: closing X11 listener.");
1225                         channel_close_fd(&c->sock);
1226                         chan_mark_dead(c);
1227                 }
1228                 if (newsock < 0) {
1229                         error("accept: %.100s", strerror(errno));
1230                         return;
1231                 }
1232                 set_nodelay(newsock);
1233                 remote_ipaddr = get_peer_ipaddr(newsock);
1234                 remote_port = get_peer_port(newsock);
1235                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1236                     remote_ipaddr, remote_port);
1237
1238                 nc = channel_new("accepted x11 socket",
1239                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1240                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1241                 if (compat20) {
1242                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1243                         packet_put_cstring("x11");
1244                         packet_put_int(nc->self);
1245                         packet_put_int(nc->local_window_max);
1246                         packet_put_int(nc->local_maxpacket);
1247                         /* originator ipaddr and port */
1248                         packet_put_cstring(remote_ipaddr);
1249                         if (datafellows & SSH_BUG_X11FWD) {
1250                                 debug2("ssh2 x11 bug compat mode");
1251                         } else {
1252                                 packet_put_int(remote_port);
1253                         }
1254                         packet_send();
1255                 } else {
1256                         packet_start(SSH_SMSG_X11_OPEN);
1257                         packet_put_int(nc->self);
1258                         if (packet_get_protocol_flags() &
1259                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1260                                 packet_put_cstring(buf);
1261                         packet_send();
1262                 }
1263                 xfree(remote_ipaddr);
1264         }
1265 }
1266
1267 static void
1268 port_open_helper(Channel *c, char *rtype)
1269 {
1270         int direct;
1271         char buf[1024];
1272         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1273         int remote_port = get_peer_port(c->sock);
1274
1275         direct = (strcmp(rtype, "direct-tcpip") == 0);
1276
1277         snprintf(buf, sizeof buf,
1278             "%s: listening port %d for %.100s port %d, "
1279             "connect from %.200s port %d",
1280             rtype, c->listening_port, c->path, c->host_port,
1281             remote_ipaddr, remote_port);
1282
1283         xfree(c->remote_name);
1284         c->remote_name = xstrdup(buf);
1285
1286         if (compat20) {
1287                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1288                 packet_put_cstring(rtype);
1289                 packet_put_int(c->self);
1290                 packet_put_int(c->local_window_max);
1291                 packet_put_int(c->local_maxpacket);
1292                 if (direct) {
1293                         /* target host, port */
1294                         packet_put_cstring(c->path);
1295                         packet_put_int(c->host_port);
1296                 } else {
1297                         /* listen address, port */
1298                         packet_put_cstring(c->path);
1299                         packet_put_int(c->listening_port);
1300                 }
1301                 /* originator host and port */
1302                 packet_put_cstring(remote_ipaddr);
1303                 packet_put_int((u_int)remote_port);
1304                 packet_send();
1305         } else {
1306                 packet_start(SSH_MSG_PORT_OPEN);
1307                 packet_put_int(c->self);
1308                 packet_put_cstring(c->path);
1309                 packet_put_int(c->host_port);
1310                 if (packet_get_protocol_flags() &
1311                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1312                         packet_put_cstring(c->remote_name);
1313                 packet_send();
1314         }
1315         xfree(remote_ipaddr);
1316 }
1317
1318 static void
1319 channel_set_reuseaddr(int fd)
1320 {
1321         int on = 1;
1322
1323         /*
1324          * Set socket options.
1325          * Allow local port reuse in TIME_WAIT.
1326          */
1327         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1328                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1329 }
1330
1331 /*
1332  * This socket is listening for connections to a forwarded TCP/IP port.
1333  */
1334 /* ARGSUSED */
1335 static void
1336 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1337 {
1338         Channel *nc;
1339         struct sockaddr_storage addr;
1340         int newsock, nextstate;
1341         socklen_t addrlen;
1342         char *rtype;
1343
1344         if (FD_ISSET(c->sock, readset)) {
1345                 debug("Connection to port %d forwarding "
1346                     "to %.100s port %d requested.",
1347                     c->listening_port, c->path, c->host_port);
1348
1349                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1350                         nextstate = SSH_CHANNEL_OPENING;
1351                         rtype = "forwarded-tcpip";
1352                 } else {
1353                         if (c->host_port == 0) {
1354                                 nextstate = SSH_CHANNEL_DYNAMIC;
1355                                 rtype = "dynamic-tcpip";
1356                         } else {
1357                                 nextstate = SSH_CHANNEL_OPENING;
1358                                 rtype = "direct-tcpip";
1359                         }
1360                 }
1361
1362                 addrlen = sizeof(addr);
1363                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1364                 if (newsock < 0) {
1365                         error("accept: %.100s", strerror(errno));
1366                         return;
1367                 }
1368                 set_nodelay(newsock);
1369                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1370                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1371                 nc->listening_port = c->listening_port;
1372                 nc->host_port = c->host_port;
1373                 strlcpy(nc->path, c->path, sizeof(nc->path));
1374
1375                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1376                         /*
1377                          * do not call the channel_post handler until
1378                          * this flag has been reset by a pre-handler.
1379                          * otherwise the FD_ISSET calls might overflow
1380                          */
1381                         nc->delayed = 1;
1382                 } else {
1383                         port_open_helper(nc, rtype);
1384                 }
1385         }
1386 }
1387
1388 /*
1389  * This is the authentication agent socket listening for connections from
1390  * clients.
1391  */
1392 /* ARGSUSED */
1393 static void
1394 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1395 {
1396         Channel *nc;
1397         int newsock;
1398         struct sockaddr_storage addr;
1399         socklen_t addrlen;
1400
1401         if (FD_ISSET(c->sock, readset)) {
1402                 addrlen = sizeof(addr);
1403                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1404                 if (newsock < 0) {
1405                         error("accept from auth socket: %.100s", strerror(errno));
1406                         return;
1407                 }
1408                 nc = channel_new("accepted auth socket",
1409                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1410                     c->local_window_max, c->local_maxpacket,
1411                     0, "accepted auth socket", 1);
1412                 if (compat20) {
1413                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1414                         packet_put_cstring("auth-agent@openssh.com");
1415                         packet_put_int(nc->self);
1416                         packet_put_int(c->local_window_max);
1417                         packet_put_int(c->local_maxpacket);
1418                 } else {
1419                         packet_start(SSH_SMSG_AGENT_OPEN);
1420                         packet_put_int(nc->self);
1421                 }
1422                 packet_send();
1423         }
1424 }
1425
1426 /* ARGSUSED */
1427 static void
1428 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1429 {
1430         int err = 0, sock;
1431         socklen_t sz = sizeof(err);
1432
1433         if (FD_ISSET(c->sock, writeset)) {
1434                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1435                         err = errno;
1436                         error("getsockopt SO_ERROR failed");
1437                 }
1438                 if (err == 0) {
1439                         debug("channel %d: connected to %s port %d",
1440                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1441                         channel_connect_ctx_free(&c->connect_ctx);
1442                         c->type = SSH_CHANNEL_OPEN;
1443                         if (compat20) {
1444                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1445                                 packet_put_int(c->remote_id);
1446                                 packet_put_int(c->self);
1447                                 packet_put_int(c->local_window);
1448                                 packet_put_int(c->local_maxpacket);
1449                         } else {
1450                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1451                                 packet_put_int(c->remote_id);
1452                                 packet_put_int(c->self);
1453                         }
1454                 } else {
1455                         debug("channel %d: connection failed: %s",
1456                             c->self, strerror(err));
1457                         /* Try next address, if any */
1458                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1459                                 close(c->sock);
1460                                 c->sock = c->rfd = c->wfd = sock;
1461                                 channel_max_fd = channel_find_maxfd();
1462                                 return;
1463                         }
1464                         /* Exhausted all addresses */
1465                         error("connect_to %.100s port %d: failed.",
1466                             c->connect_ctx.host, c->connect_ctx.port);
1467                         channel_connect_ctx_free(&c->connect_ctx);
1468                         if (compat20) {
1469                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1470                                 packet_put_int(c->remote_id);
1471                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1472                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1473                                         packet_put_cstring(strerror(err));
1474                                         packet_put_cstring("");
1475                                 }
1476                         } else {
1477                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1478                                 packet_put_int(c->remote_id);
1479                         }
1480                         chan_mark_dead(c);
1481                 }
1482                 packet_send();
1483         }
1484 }
1485
1486 /* ARGSUSED */
1487 static int
1488 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1489 {
1490         char buf[CHAN_RBUF];
1491         int len, force;
1492
1493         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1494         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1495                 errno = 0;
1496                 len = read(c->rfd, buf, sizeof(buf));
1497                 if (len < 0 && (errno == EINTR ||
1498                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1499                         return 1;
1500 #ifndef PTY_ZEROREAD
1501                 if (len <= 0) {
1502 #else
1503                 if ((!c->isatty && len <= 0) ||
1504                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1505 #endif
1506                         debug2("channel %d: read<=0 rfd %d len %d",
1507                             c->self, c->rfd, len);
1508                         if (c->type != SSH_CHANNEL_OPEN) {
1509                                 debug2("channel %d: not open", c->self);
1510                                 chan_mark_dead(c);
1511                                 return -1;
1512                         } else if (compat13) {
1513                                 buffer_clear(&c->output);
1514                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1515                                 debug2("channel %d: input draining.", c->self);
1516                         } else {
1517                                 chan_read_failed(c);
1518                         }
1519                         return -1;
1520                 }
1521                 if (c->input_filter != NULL) {
1522                         if (c->input_filter(c, buf, len) == -1) {
1523                                 debug2("channel %d: filter stops", c->self);
1524                                 chan_read_failed(c);
1525                         }
1526                 } else if (c->datagram) {
1527                         buffer_put_string(&c->input, buf, len);
1528                 } else {
1529                         buffer_append(&c->input, buf, len);
1530                 }
1531         }
1532         return 1;
1533 }
1534
1535 /* ARGSUSED */
1536 static int
1537 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1538 {
1539         struct termios tio;
1540         u_char *data = NULL, *buf;
1541         u_int dlen;
1542         int len;
1543
1544         /* Send buffered output data to the socket. */
1545         if (c->wfd != -1 &&
1546             FD_ISSET(c->wfd, writeset) &&
1547             buffer_len(&c->output) > 0) {
1548                 if (c->output_filter != NULL) {
1549                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1550                                 debug2("channel %d: filter stops", c->self);
1551                                 if (c->type != SSH_CHANNEL_OPEN)
1552                                         chan_mark_dead(c);
1553                                 else
1554                                         chan_write_failed(c);
1555                                 return -1;
1556                         }
1557                 } else if (c->datagram) {
1558                         buf = data = buffer_get_string(&c->output, &dlen);
1559                 } else {
1560                         buf = data = buffer_ptr(&c->output);
1561                         dlen = buffer_len(&c->output);
1562                 }
1563
1564                 if (c->datagram) {
1565                         /* ignore truncated writes, datagrams might get lost */
1566                         c->local_consumed += dlen + 4;
1567                         len = write(c->wfd, buf, dlen);
1568                         xfree(data);
1569                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1570                             errno == EWOULDBLOCK))
1571                                 return 1;
1572                         if (len <= 0) {
1573                                 if (c->type != SSH_CHANNEL_OPEN)
1574                                         chan_mark_dead(c);
1575                                 else
1576                                         chan_write_failed(c);
1577                                 return -1;
1578                         }
1579                         return 1;
1580                 }
1581 #ifdef _AIX
1582                 /* XXX: Later AIX versions can't push as much data to tty */
1583                 if (compat20 && c->wfd_isatty)
1584                         dlen = MIN(dlen, 8*1024);
1585 #endif
1586
1587                 len = write(c->wfd, buf, dlen);
1588                 if (len < 0 &&
1589                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1590                         return 1;
1591                 if (len <= 0) {
1592                         if (c->type != SSH_CHANNEL_OPEN) {
1593                                 debug2("channel %d: not open", c->self);
1594                                 chan_mark_dead(c);
1595                                 return -1;
1596                         } else if (compat13) {
1597                                 buffer_clear(&c->output);
1598                                 debug2("channel %d: input draining.", c->self);
1599                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1600                         } else {
1601                                 chan_write_failed(c);
1602                         }
1603                         return -1;
1604                 }
1605                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1606                         if (tcgetattr(c->wfd, &tio) == 0 &&
1607                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1608                                 /*
1609                                  * Simulate echo to reduce the impact of
1610                                  * traffic analysis. We need to match the
1611                                  * size of a SSH2_MSG_CHANNEL_DATA message
1612                                  * (4 byte channel id + buf)
1613                                  */
1614                                 packet_send_ignore(4 + len);
1615                                 packet_send();
1616                         }
1617                 }
1618                 buffer_consume(&c->output, len);
1619                 if (compat20 && len > 0) {
1620                         c->local_consumed += len;
1621                 }
1622         }
1623         return 1;
1624 }
1625
1626 static int
1627 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1628 {
1629         char buf[CHAN_RBUF];
1630         int len;
1631
1632 /** XXX handle drain efd, too */
1633         if (c->efd != -1) {
1634                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1635                     FD_ISSET(c->efd, writeset) &&
1636                     buffer_len(&c->extended) > 0) {
1637                         len = write(c->efd, buffer_ptr(&c->extended),
1638                             buffer_len(&c->extended));
1639                         debug2("channel %d: written %d to efd %d",
1640                             c->self, len, c->efd);
1641                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1642                             errno == EWOULDBLOCK))
1643                                 return 1;
1644                         if (len <= 0) {
1645                                 debug2("channel %d: closing write-efd %d",
1646                                     c->self, c->efd);
1647                                 channel_close_fd(&c->efd);
1648                         } else {
1649                                 buffer_consume(&c->extended, len);
1650                                 c->local_consumed += len;
1651                         }
1652                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1653                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1654                         len = read(c->efd, buf, sizeof(buf));
1655                         debug2("channel %d: read %d from efd %d",
1656                             c->self, len, c->efd);
1657                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1658                             errno == EWOULDBLOCK) && !c->detach_close)))
1659                                 return 1;
1660                         if (len <= 0) {
1661                                 debug2("channel %d: closing read-efd %d",
1662                                     c->self, c->efd);
1663                                 channel_close_fd(&c->efd);
1664                         } else {
1665                                 buffer_append(&c->extended, buf, len);
1666                         }
1667                 }
1668         }
1669         return 1;
1670 }
1671
1672 /* ARGSUSED */
1673 static int
1674 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1675 {
1676         char buf[16];
1677         int len;
1678
1679         /* Monitor control fd to detect if the slave client exits */
1680         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1681                 len = read(c->ctl_fd, buf, sizeof(buf));
1682                 if (len < 0 &&
1683                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1684                         return 1;
1685                 if (len <= 0) {
1686                         debug2("channel %d: ctl read<=0", c->self);
1687                         if (c->type != SSH_CHANNEL_OPEN) {
1688                                 debug2("channel %d: not open", c->self);
1689                                 chan_mark_dead(c);
1690                                 return -1;
1691                         } else {
1692                                 chan_read_failed(c);
1693                                 chan_write_failed(c);
1694                         }
1695                         return -1;
1696                 } else
1697                         fatal("%s: unexpected data on ctl fd", __func__);
1698         }
1699         return 1;
1700 }
1701
1702 static int
1703 channel_check_window(Channel *c)
1704 {
1705         if (c->type == SSH_CHANNEL_OPEN &&
1706             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1707             ((c->local_window_max - c->local_window >
1708             c->local_maxpacket*3) ||
1709             c->local_window < c->local_window_max/2) &&
1710             c->local_consumed > 0) {
1711                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1712                 packet_put_int(c->remote_id);
1713                 packet_put_int(c->local_consumed);
1714                 packet_send();
1715                 debug2("channel %d: window %d sent adjust %d",
1716                     c->self, c->local_window,
1717                     c->local_consumed);
1718                 c->local_window += c->local_consumed;
1719                 c->local_consumed = 0;
1720         }
1721         return 1;
1722 }
1723
1724 static void
1725 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1726 {
1727         if (c->delayed)
1728                 return;
1729         channel_handle_rfd(c, readset, writeset);
1730         channel_handle_wfd(c, readset, writeset);
1731         if (!compat20)
1732                 return;
1733         channel_handle_efd(c, readset, writeset);
1734         channel_handle_ctl(c, readset, writeset);
1735         channel_check_window(c);
1736 }
1737
1738 /* ARGSUSED */
1739 static void
1740 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1741 {
1742         int len;
1743
1744         /* Send buffered output data to the socket. */
1745         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1746                 len = write(c->sock, buffer_ptr(&c->output),
1747                             buffer_len(&c->output));
1748                 if (len <= 0)
1749                         buffer_clear(&c->output);
1750                 else
1751                         buffer_consume(&c->output, len);
1752         }
1753 }
1754
1755 static void
1756 channel_handler_init_20(void)
1757 {
1758         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1759         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1760         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1761         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1762         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1763         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1764         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1765         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1766
1767         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1768         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1769         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1770         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1771         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1772         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1773         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1774 }
1775
1776 static void
1777 channel_handler_init_13(void)
1778 {
1779         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1780         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1781         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1782         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1783         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1784         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1785         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1786         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1787         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1788
1789         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1790         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1791         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1792         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1793         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1794         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1795         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1796 }
1797
1798 static void
1799 channel_handler_init_15(void)
1800 {
1801         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1802         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1803         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1804         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1805         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1806         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1807         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1808
1809         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1810         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1811         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1812         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1813         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1814         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1815 }
1816
1817 static void
1818 channel_handler_init(void)
1819 {
1820         int i;
1821
1822         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1823                 channel_pre[i] = NULL;
1824                 channel_post[i] = NULL;
1825         }
1826         if (compat20)
1827                 channel_handler_init_20();
1828         else if (compat13)
1829                 channel_handler_init_13();
1830         else
1831                 channel_handler_init_15();
1832 }
1833
1834 /* gc dead channels */
1835 static void
1836 channel_garbage_collect(Channel *c)
1837 {
1838         if (c == NULL)
1839                 return;
1840         if (c->detach_user != NULL) {
1841                 if (!chan_is_dead(c, c->detach_close))
1842                         return;
1843                 debug2("channel %d: gc: notify user", c->self);
1844                 c->detach_user(c->self, NULL);
1845                 /* if we still have a callback */
1846                 if (c->detach_user != NULL)
1847                         return;
1848                 debug2("channel %d: gc: user detached", c->self);
1849         }
1850         if (!chan_is_dead(c, 1))
1851                 return;
1852         debug2("channel %d: garbage collecting", c->self);
1853         channel_free(c);
1854 }
1855
1856 static void
1857 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1858 {
1859         static int did_init = 0;
1860         u_int i;
1861         Channel *c;
1862
1863         if (!did_init) {
1864                 channel_handler_init();
1865                 did_init = 1;
1866         }
1867         for (i = 0; i < channels_alloc; i++) {
1868                 c = channels[i];
1869                 if (c == NULL)
1870                         continue;
1871                 if (ftab[c->type] != NULL)
1872                         (*ftab[c->type])(c, readset, writeset);
1873                 channel_garbage_collect(c);
1874         }
1875 }
1876
1877 /*
1878  * Allocate/update select bitmasks and add any bits relevant to channels in
1879  * select bitmasks.
1880  */
1881 void
1882 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1883     u_int *nallocp, int rekeying)
1884 {
1885         u_int n, sz, nfdset;
1886
1887         n = MAX(*maxfdp, channel_max_fd);
1888
1889         nfdset = howmany(n+1, NFDBITS);
1890         /* Explicitly test here, because xrealloc isn't always called */
1891         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1892                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1893         sz = nfdset * sizeof(fd_mask);
1894
1895         /* perhaps check sz < nalloc/2 and shrink? */
1896         if (*readsetp == NULL || sz > *nallocp) {
1897                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1898                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1899                 *nallocp = sz;
1900         }
1901         *maxfdp = n;
1902         memset(*readsetp, 0, sz);
1903         memset(*writesetp, 0, sz);
1904
1905         if (!rekeying)
1906                 channel_handler(channel_pre, *readsetp, *writesetp);
1907 }
1908
1909 /*
1910  * After select, perform any appropriate operations for channels which have
1911  * events pending.
1912  */
1913 void
1914 channel_after_select(fd_set *readset, fd_set *writeset)
1915 {
1916         channel_handler(channel_post, readset, writeset);
1917 }
1918
1919
1920 /* If there is data to send to the connection, enqueue some of it now. */
1921 void
1922 channel_output_poll(void)
1923 {
1924         Channel *c;
1925         u_int i, len;
1926
1927         for (i = 0; i < channels_alloc; i++) {
1928                 c = channels[i];
1929                 if (c == NULL)
1930                         continue;
1931
1932                 /*
1933                  * We are only interested in channels that can have buffered
1934                  * incoming data.
1935                  */
1936                 if (compat13) {
1937                         if (c->type != SSH_CHANNEL_OPEN &&
1938                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1939                                 continue;
1940                 } else {
1941                         if (c->type != SSH_CHANNEL_OPEN)
1942                                 continue;
1943                 }
1944                 if (compat20 &&
1945                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1946                         /* XXX is this true? */
1947                         debug3("channel %d: will not send data after close", c->self);
1948                         continue;
1949                 }
1950
1951                 /* Get the amount of buffered data for this channel. */
1952                 if ((c->istate == CHAN_INPUT_OPEN ||
1953                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1954                     (len = buffer_len(&c->input)) > 0) {
1955                         if (c->datagram) {
1956                                 if (len > 0) {
1957                                         u_char *data;
1958                                         u_int dlen;
1959
1960                                         data = buffer_get_string(&c->input,
1961                                             &dlen);
1962                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1963                                         packet_put_int(c->remote_id);
1964                                         packet_put_string(data, dlen);
1965                                         packet_send();
1966                                         c->remote_window -= dlen + 4;
1967                                         xfree(data);
1968                                 }
1969                                 continue;
1970                         }
1971                         /*
1972                          * Send some data for the other side over the secure
1973                          * connection.
1974                          */
1975                         if (compat20) {
1976                                 if (len > c->remote_window)
1977                                         len = c->remote_window;
1978                                 if (len > c->remote_maxpacket)
1979                                         len = c->remote_maxpacket;
1980                         } else {
1981                                 if (packet_is_interactive()) {
1982                                         if (len > 1024)
1983                                                 len = 512;
1984                                 } else {
1985                                         /* Keep the packets at reasonable size. */
1986                                         if (len > packet_get_maxsize()/2)
1987                                                 len = packet_get_maxsize()/2;
1988                                 }
1989                         }
1990                         if (len > 0) {
1991                                 packet_start(compat20 ?
1992                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1993                                 packet_put_int(c->remote_id);
1994                                 packet_put_string(buffer_ptr(&c->input), len);
1995                                 packet_send();
1996                                 buffer_consume(&c->input, len);
1997                                 c->remote_window -= len;
1998                         }
1999                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2000                         if (compat13)
2001                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2002                         /*
2003                          * input-buffer is empty and read-socket shutdown:
2004                          * tell peer, that we will not send more data: send IEOF.
2005                          * hack for extended data: delay EOF if EFD still in use.
2006                          */
2007                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2008                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2009                                     c->self, c->efd, buffer_len(&c->extended));
2010                         else
2011                                 chan_ibuf_empty(c);
2012                 }
2013                 /* Send extended data, i.e. stderr */
2014                 if (compat20 &&
2015                     !(c->flags & CHAN_EOF_SENT) &&
2016                     c->remote_window > 0 &&
2017                     (len = buffer_len(&c->extended)) > 0 &&
2018                     c->extended_usage == CHAN_EXTENDED_READ) {
2019                         debug2("channel %d: rwin %u elen %u euse %d",
2020                             c->self, c->remote_window, buffer_len(&c->extended),
2021                             c->extended_usage);
2022                         if (len > c->remote_window)
2023                                 len = c->remote_window;
2024                         if (len > c->remote_maxpacket)
2025                                 len = c->remote_maxpacket;
2026                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2027                         packet_put_int(c->remote_id);
2028                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2029                         packet_put_string(buffer_ptr(&c->extended), len);
2030                         packet_send();
2031                         buffer_consume(&c->extended, len);
2032                         c->remote_window -= len;
2033                         debug2("channel %d: sent ext data %d", c->self, len);
2034                 }
2035         }
2036 }
2037
2038
2039 /* -- protocol input */
2040
2041 /* ARGSUSED */
2042 void
2043 channel_input_data(int type, u_int32_t seq, void *ctxt)
2044 {
2045         int id;
2046         char *data;
2047         u_int data_len;
2048         Channel *c;
2049
2050         /* Get the channel number and verify it. */
2051         id = packet_get_int();
2052         c = channel_lookup(id);
2053         if (c == NULL)
2054                 packet_disconnect("Received data for nonexistent channel %d.", id);
2055
2056         /* Ignore any data for non-open channels (might happen on close) */
2057         if (c->type != SSH_CHANNEL_OPEN &&
2058             c->type != SSH_CHANNEL_X11_OPEN)
2059                 return;
2060
2061         /* Get the data. */
2062         data = packet_get_string_ptr(&data_len);
2063
2064         /*
2065          * Ignore data for protocol > 1.3 if output end is no longer open.
2066          * For protocol 2 the sending side is reducing its window as it sends
2067          * data, so we must 'fake' consumption of the data in order to ensure
2068          * that window updates are sent back.  Otherwise the connection might
2069          * deadlock.
2070          */
2071         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2072                 if (compat20) {
2073                         c->local_window -= data_len;
2074                         c->local_consumed += data_len;
2075                 }
2076                 return;
2077         }
2078
2079         if (compat20) {
2080                 if (data_len > c->local_maxpacket) {
2081                         logit("channel %d: rcvd big packet %d, maxpack %d",
2082                             c->self, data_len, c->local_maxpacket);
2083                 }
2084                 if (data_len > c->local_window) {
2085                         logit("channel %d: rcvd too much data %d, win %d",
2086                             c->self, data_len, c->local_window);
2087                         return;
2088                 }
2089                 c->local_window -= data_len;
2090         }
2091         if (c->datagram)
2092                 buffer_put_string(&c->output, data, data_len);
2093         else
2094                 buffer_append(&c->output, data, data_len);
2095         packet_check_eom();
2096 }
2097
2098 /* ARGSUSED */
2099 void
2100 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2101 {
2102         int id;
2103         char *data;
2104         u_int data_len, tcode;
2105         Channel *c;
2106
2107         /* Get the channel number and verify it. */
2108         id = packet_get_int();
2109         c = channel_lookup(id);
2110
2111         if (c == NULL)
2112                 packet_disconnect("Received extended_data for bad channel %d.", id);
2113         if (c->type != SSH_CHANNEL_OPEN) {
2114                 logit("channel %d: ext data for non open", id);
2115                 return;
2116         }
2117         if (c->flags & CHAN_EOF_RCVD) {
2118                 if (datafellows & SSH_BUG_EXTEOF)
2119                         debug("channel %d: accepting ext data after eof", id);
2120                 else
2121                         packet_disconnect("Received extended_data after EOF "
2122                             "on channel %d.", id);
2123         }
2124         tcode = packet_get_int();
2125         if (c->efd == -1 ||
2126             c->extended_usage != CHAN_EXTENDED_WRITE ||
2127             tcode != SSH2_EXTENDED_DATA_STDERR) {
2128                 logit("channel %d: bad ext data", c->self);
2129                 return;
2130         }
2131         data = packet_get_string(&data_len);
2132         packet_check_eom();
2133         if (data_len > c->local_window) {
2134                 logit("channel %d: rcvd too much extended_data %d, win %d",
2135                     c->self, data_len, c->local_window);
2136                 xfree(data);
2137                 return;
2138         }
2139         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2140         c->local_window -= data_len;
2141         buffer_append(&c->extended, data, data_len);
2142         xfree(data);
2143 }
2144
2145 /* ARGSUSED */
2146 void
2147 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2148 {
2149         int id;
2150         Channel *c;
2151
2152         id = packet_get_int();
2153         packet_check_eom();
2154         c = channel_lookup(id);
2155         if (c == NULL)
2156                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2157         chan_rcvd_ieof(c);
2158
2159         /* XXX force input close */
2160         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2161                 debug("channel %d: FORCE input drain", c->self);
2162                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2163                 if (buffer_len(&c->input) == 0)
2164                         chan_ibuf_empty(c);
2165         }
2166
2167 }
2168
2169 /* ARGSUSED */
2170 void
2171 channel_input_close(int type, u_int32_t seq, void *ctxt)
2172 {
2173         int id;
2174         Channel *c;
2175
2176         id = packet_get_int();
2177         packet_check_eom();
2178         c = channel_lookup(id);
2179         if (c == NULL)
2180                 packet_disconnect("Received close for nonexistent channel %d.", id);
2181
2182         /*
2183          * Send a confirmation that we have closed the channel and no more
2184          * data is coming for it.
2185          */
2186         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2187         packet_put_int(c->remote_id);
2188         packet_send();
2189
2190         /*
2191          * If the channel is in closed state, we have sent a close request,
2192          * and the other side will eventually respond with a confirmation.
2193          * Thus, we cannot free the channel here, because then there would be
2194          * no-one to receive the confirmation.  The channel gets freed when
2195          * the confirmation arrives.
2196          */
2197         if (c->type != SSH_CHANNEL_CLOSED) {
2198                 /*
2199                  * Not a closed channel - mark it as draining, which will
2200                  * cause it to be freed later.
2201                  */
2202                 buffer_clear(&c->input);
2203                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2204         }
2205 }
2206
2207 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2208 /* ARGSUSED */
2209 void
2210 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2211 {
2212         int id = packet_get_int();
2213         Channel *c = channel_lookup(id);
2214
2215         packet_check_eom();
2216         if (c == NULL)
2217                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2218         chan_rcvd_oclose(c);
2219 }
2220
2221 /* ARGSUSED */
2222 void
2223 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2224 {
2225         int id = packet_get_int();
2226         Channel *c = channel_lookup(id);
2227
2228         packet_check_eom();
2229         if (c == NULL)
2230                 packet_disconnect("Received close confirmation for "
2231                     "out-of-range channel %d.", id);
2232         if (c->type != SSH_CHANNEL_CLOSED)
2233                 packet_disconnect("Received close confirmation for "
2234                     "non-closed channel %d (type %d).", id, c->type);
2235         channel_free(c);
2236 }
2237
2238 /* ARGSUSED */
2239 void
2240 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2241 {
2242         int id, remote_id;
2243         Channel *c;
2244
2245         id = packet_get_int();
2246         c = channel_lookup(id);
2247
2248         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2249                 packet_disconnect("Received open confirmation for "
2250                     "non-opening channel %d.", id);
2251         remote_id = packet_get_int();
2252         /* Record the remote channel number and mark that the channel is now open. */
2253         c->remote_id = remote_id;
2254         c->type = SSH_CHANNEL_OPEN;
2255
2256         if (compat20) {
2257                 c->remote_window = packet_get_int();
2258                 c->remote_maxpacket = packet_get_int();
2259                 if (c->open_confirm) {
2260                         debug2("callback start");
2261                         c->open_confirm(c->self, c->open_confirm_ctx);
2262                         debug2("callback done");
2263                 }
2264                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2265                     c->remote_window, c->remote_maxpacket);
2266         }
2267         packet_check_eom();
2268 }
2269
2270 static char *
2271 reason2txt(int reason)
2272 {
2273         switch (reason) {
2274         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2275                 return "administratively prohibited";
2276         case SSH2_OPEN_CONNECT_FAILED:
2277                 return "connect failed";
2278         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2279                 return "unknown channel type";
2280         case SSH2_OPEN_RESOURCE_SHORTAGE:
2281                 return "resource shortage";
2282         }
2283         return "unknown reason";
2284 }
2285
2286 /* ARGSUSED */
2287 void
2288 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2289 {
2290         int id, reason;
2291         char *msg = NULL, *lang = NULL;
2292         Channel *c;
2293
2294         id = packet_get_int();
2295         c = channel_lookup(id);
2296
2297         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2298                 packet_disconnect("Received open failure for "
2299                     "non-opening channel %d.", id);
2300         if (compat20) {
2301                 reason = packet_get_int();
2302                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2303                         msg  = packet_get_string(NULL);
2304                         lang = packet_get_string(NULL);
2305                 }
2306                 logit("channel %d: open failed: %s%s%s", id,
2307                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2308                 if (msg != NULL)
2309                         xfree(msg);
2310                 if (lang != NULL)
2311                         xfree(lang);
2312         }
2313         packet_check_eom();
2314         /* Free the channel.  This will also close the socket. */
2315         channel_free(c);
2316 }
2317
2318 /* ARGSUSED */
2319 void
2320 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2321 {
2322         Channel *c;
2323         int id;
2324         u_int adjust;
2325
2326         if (!compat20)
2327                 return;
2328
2329         /* Get the channel number and verify it. */
2330         id = packet_get_int();
2331         c = channel_lookup(id);
2332
2333         if (c == NULL) {
2334                 logit("Received window adjust for non-open channel %d.", id);
2335                 return;
2336         }
2337         adjust = packet_get_int();
2338         packet_check_eom();
2339         debug2("channel %d: rcvd adjust %u", id, adjust);
2340         c->remote_window += adjust;
2341 }
2342
2343 /* ARGSUSED */
2344 void
2345 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2346 {
2347         Channel *c = NULL;
2348         u_short host_port;
2349         char *host, *originator_string;
2350         int remote_id;
2351
2352         remote_id = packet_get_int();
2353         host = packet_get_string(NULL);
2354         host_port = packet_get_int();
2355
2356         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2357                 originator_string = packet_get_string(NULL);
2358         } else {
2359                 originator_string = xstrdup("unknown (remote did not supply name)");
2360         }
2361         packet_check_eom();
2362         c = channel_connect_to(host, host_port,
2363             "connected socket", originator_string);
2364         xfree(originator_string);
2365         xfree(host);
2366         if (c == NULL) {
2367                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2368                 packet_put_int(remote_id);
2369                 packet_send();
2370         } else
2371                 c->remote_id = remote_id;
2372 }
2373
2374 /* ARGSUSED */
2375 void
2376 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2377 {
2378         Channel *c;
2379         struct channel_confirm *cc;
2380         int remote_id;
2381
2382         /* Reset keepalive timeout */
2383         keep_alive_timeouts = 0;
2384
2385         remote_id = packet_get_int();
2386         packet_check_eom();
2387
2388         debug2("channel_input_confirm: type %d id %d", type, remote_id);
2389
2390         if ((c = channel_lookup(remote_id)) == NULL) {
2391                 logit("channel_input_success_failure: %d: unknown", remote_id);
2392                 return;
2393         }
2394         ;
2395         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2396                 return;
2397         cc->cb(type, c, cc->ctx);
2398         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2399         bzero(cc, sizeof(*cc));
2400         xfree(cc);
2401 }
2402
2403 /* -- tcp forwarding */
2404
2405 void
2406 channel_set_af(int af)
2407 {
2408         IPv4or6 = af;
2409 }
2410
2411 static int
2412 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2413     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2414 {
2415         Channel *c;
2416         int sock, r, success = 0, wildcard = 0, is_client;
2417         struct addrinfo hints, *ai, *aitop;
2418         const char *host, *addr;
2419         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2420
2421         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2422             listen_addr : host_to_connect;
2423         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2424
2425         if (host == NULL) {
2426                 error("No forward host name.");
2427                 return 0;
2428         }
2429         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2430                 error("Forward host name too long.");
2431                 return 0;
2432         }
2433
2434         /*
2435          * Determine whether or not a port forward listens to loopback,
2436          * specified address or wildcard. On the client, a specified bind
2437          * address will always override gateway_ports. On the server, a
2438          * gateway_ports of 1 (``yes'') will override the client's
2439          * specification and force a wildcard bind, whereas a value of 2
2440          * (``clientspecified'') will bind to whatever address the client
2441          * asked for.
2442          *
2443          * Special-case listen_addrs are:
2444          *
2445          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2446          * "" (empty string), "*"  -> wildcard v4/v6
2447          * "localhost"             -> loopback v4/v6
2448          */
2449         addr = NULL;
2450         if (listen_addr == NULL) {
2451                 /* No address specified: default to gateway_ports setting */
2452                 if (gateway_ports)
2453                         wildcard = 1;
2454         } else if (gateway_ports || is_client) {
2455                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2456                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2457                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2458                     (!is_client && gateway_ports == 1))
2459                         wildcard = 1;
2460                 else if (strcmp(listen_addr, "localhost") != 0)
2461                         addr = listen_addr;
2462         }
2463
2464         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2465             type, wildcard, (addr == NULL) ? "NULL" : addr);
2466
2467         /*
2468          * getaddrinfo returns a loopback address if the hostname is
2469          * set to NULL and hints.ai_flags is not AI_PASSIVE
2470          */
2471         memset(&hints, 0, sizeof(hints));
2472         hints.ai_family = IPv4or6;
2473         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2474         hints.ai_socktype = SOCK_STREAM;
2475         snprintf(strport, sizeof strport, "%d", listen_port);
2476         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2477                 if (addr == NULL) {
2478                         /* This really shouldn't happen */
2479                         packet_disconnect("getaddrinfo: fatal error: %s",
2480                             ssh_gai_strerror(r));
2481                 } else {
2482                         error("channel_setup_fwd_listener: "
2483                             "getaddrinfo(%.64s): %s", addr,
2484                             ssh_gai_strerror(r));
2485                 }
2486                 return 0;
2487         }
2488
2489         for (ai = aitop; ai; ai = ai->ai_next) {
2490                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2491                         continue;
2492                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2493                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2494                         error("channel_setup_fwd_listener: getnameinfo failed");
2495                         continue;
2496                 }
2497                 /* Create a port to listen for the host. */
2498                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2499                 if (sock < 0) {
2500                         /* this is no error since kernel may not support ipv6 */
2501                         verbose("socket: %.100s", strerror(errno));
2502                         continue;
2503                 }
2504
2505                 channel_set_reuseaddr(sock);
2506
2507                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2508
2509                 /* Bind the socket to the address. */
2510                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2511                         /* address can be in use ipv6 address is already bound */
2512                         if (!ai->ai_next)
2513                                 error("bind: %.100s", strerror(errno));
2514                         else
2515                                 verbose("bind: %.100s", strerror(errno));
2516
2517                         close(sock);
2518                         continue;
2519                 }
2520                 /* Start listening for connections on the socket. */
2521                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2522                         error("listen: %.100s", strerror(errno));
2523                         close(sock);
2524                         continue;
2525                 }
2526                 /* Allocate a channel number for the socket. */
2527                 c = channel_new("port listener", type, sock, sock, -1,
2528                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2529                     0, "port listener", 1);
2530                 strlcpy(c->path, host, sizeof(c->path));
2531                 c->host_port = port_to_connect;
2532                 c->listening_port = listen_port;
2533                 success = 1;
2534         }
2535         if (success == 0)
2536                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2537                     listen_port);
2538         freeaddrinfo(aitop);
2539         return success;
2540 }
2541
2542 int
2543 channel_cancel_rport_listener(const char *host, u_short port)
2544 {
2545         u_int i;
2546         int found = 0;
2547
2548         for (i = 0; i < channels_alloc; i++) {
2549                 Channel *c = channels[i];
2550
2551                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2552                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2553                     c->listening_port == port) {
2554                         debug2("%s: close channel %d", __func__, i);
2555                         channel_free(c);
2556                         found = 1;
2557                 }
2558         }
2559
2560         return (found);
2561 }
2562
2563 /* protocol local port fwd, used by ssh (and sshd in v1) */
2564 int
2565 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2566     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2567 {
2568         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2569             listen_host, listen_port, host_to_connect, port_to_connect,
2570             gateway_ports);
2571 }
2572
2573 /* protocol v2 remote port fwd, used by sshd */
2574 int
2575 channel_setup_remote_fwd_listener(const char *listen_address,
2576     u_short listen_port, int gateway_ports)
2577 {
2578         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2579             listen_address, listen_port, NULL, 0, gateway_ports);
2580 }
2581
2582 /*
2583  * Initiate forwarding of connections to port "port" on remote host through
2584  * the secure channel to host:port from local side.
2585  */
2586
2587 int
2588 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2589     const char *host_to_connect, u_short port_to_connect)
2590 {
2591         int type, success = 0;
2592
2593         /* Record locally that connection to this host/port is permitted. */
2594         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2595                 fatal("channel_request_remote_forwarding: too many forwards");
2596
2597         /* Send the forward request to the remote side. */
2598         if (compat20) {
2599                 const char *address_to_bind;
2600                 if (listen_host == NULL) {
2601                         if (datafellows & SSH_BUG_RFWD_ADDR)
2602                                 address_to_bind = "127.0.0.1";
2603                         else
2604                                 address_to_bind = "localhost";
2605                 } else if (*listen_host == '\0' ||
2606                            strcmp(listen_host, "*") == 0) {
2607                         if (datafellows & SSH_BUG_RFWD_ADDR)
2608                                 address_to_bind = "0.0.0.0";
2609                         else
2610                                 address_to_bind = "";
2611                 } else
2612                         address_to_bind = listen_host;
2613
2614                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2615                 packet_put_cstring("tcpip-forward");
2616                 packet_put_char(1);                     /* boolean: want reply */
2617                 packet_put_cstring(address_to_bind);
2618                 packet_put_int(listen_port);
2619                 packet_send();
2620                 packet_write_wait();
2621                 /* Assume that server accepts the request */
2622                 success = 1;
2623         } else {
2624                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2625                 packet_put_int(listen_port);
2626                 packet_put_cstring(host_to_connect);
2627                 packet_put_int(port_to_connect);
2628                 packet_send();
2629                 packet_write_wait();
2630
2631                 /* Wait for response from the remote side. */
2632                 type = packet_read();
2633                 switch (type) {
2634                 case SSH_SMSG_SUCCESS:
2635                         success = 1;
2636                         break;
2637                 case SSH_SMSG_FAILURE:
2638                         break;
2639                 default:
2640                         /* Unknown packet */
2641                         packet_disconnect("Protocol error for port forward request:"
2642                             "received packet type %d.", type);
2643                 }
2644         }
2645         if (success) {
2646                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2647                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2648                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2649                 num_permitted_opens++;
2650         }
2651         return (success ? 0 : -1);
2652 }
2653
2654 /*
2655  * Request cancellation of remote forwarding of connection host:port from
2656  * local side.
2657  */
2658 void
2659 channel_request_rforward_cancel(const char *host, u_short port)
2660 {
2661         int i;
2662
2663         if (!compat20)
2664                 return;
2665
2666         for (i = 0; i < num_permitted_opens; i++) {
2667                 if (permitted_opens[i].host_to_connect != NULL &&
2668                     permitted_opens[i].listen_port == port)
2669                         break;
2670         }
2671         if (i >= num_permitted_opens) {
2672                 debug("%s: requested forward not found", __func__);
2673                 return;
2674         }
2675         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2676         packet_put_cstring("cancel-tcpip-forward");
2677         packet_put_char(0);
2678         packet_put_cstring(host == NULL ? "" : host);
2679         packet_put_int(port);
2680         packet_send();
2681
2682         permitted_opens[i].listen_port = 0;
2683         permitted_opens[i].port_to_connect = 0;
2684         xfree(permitted_opens[i].host_to_connect);
2685         permitted_opens[i].host_to_connect = NULL;
2686 }
2687
2688 /*
2689  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2690  * listening for the port, and sends back a success reply (or disconnect
2691  * message if there was an error).
2692  */
2693 int
2694 channel_input_port_forward_request(int is_root, int gateway_ports)
2695 {
2696         u_short port, host_port;
2697         int success = 0;
2698         char *hostname;
2699
2700         /* Get arguments from the packet. */
2701         port = packet_get_int();
2702         hostname = packet_get_string(NULL);
2703         host_port = packet_get_int();
2704
2705 #ifndef HAVE_CYGWIN
2706         /*
2707          * Check that an unprivileged user is not trying to forward a
2708          * privileged port.
2709          */
2710         if (port < IPPORT_RESERVED && !is_root)
2711                 packet_disconnect(
2712                     "Requested forwarding of port %d but user is not root.",
2713                     port);
2714         if (host_port == 0)
2715                 packet_disconnect("Dynamic forwarding denied.");
2716 #endif
2717
2718         /* Initiate forwarding */
2719         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2720             host_port, gateway_ports);
2721
2722         /* Free the argument string. */
2723         xfree(hostname);
2724
2725         return (success ? 0 : -1);
2726 }
2727
2728 /*
2729  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2730  * usually called by the server, because the user could connect to any port
2731  * anyway, and the server has no way to know but to trust the client anyway.
2732  */
2733 void
2734 channel_permit_all_opens(void)
2735 {
2736         if (num_permitted_opens == 0)
2737                 all_opens_permitted = 1;
2738 }
2739
2740 void
2741 channel_add_permitted_opens(char *host, int port)
2742 {
2743         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2744                 fatal("channel_add_permitted_opens: too many forwards");
2745         debug("allow port forwarding to host %s port %d", host, port);
2746
2747         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2748         permitted_opens[num_permitted_opens].port_to_connect = port;
2749         num_permitted_opens++;
2750
2751         all_opens_permitted = 0;
2752 }
2753
2754 int
2755 channel_add_adm_permitted_opens(char *host, int port)
2756 {
2757         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2758                 fatal("channel_add_adm_permitted_opens: too many forwards");
2759         debug("config allows port forwarding to host %s port %d", host, port);
2760
2761         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2762              = xstrdup(host);
2763         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2764         return ++num_adm_permitted_opens;
2765 }
2766
2767 void
2768 channel_clear_permitted_opens(void)
2769 {
2770         int i;
2771
2772         for (i = 0; i < num_permitted_opens; i++)
2773                 if (permitted_opens[i].host_to_connect != NULL)
2774                         xfree(permitted_opens[i].host_to_connect);
2775         num_permitted_opens = 0;
2776 }
2777
2778 void
2779 channel_clear_adm_permitted_opens(void)
2780 {
2781         int i;
2782
2783         for (i = 0; i < num_adm_permitted_opens; i++)
2784                 if (permitted_adm_opens[i].host_to_connect != NULL)
2785                         xfree(permitted_adm_opens[i].host_to_connect);
2786         num_adm_permitted_opens = 0;
2787 }
2788
2789 void
2790 channel_print_adm_permitted_opens(void)
2791 {
2792         int i;
2793
2794         for (i = 0; i < num_adm_permitted_opens; i++)
2795                 if (permitted_adm_opens[i].host_to_connect != NULL)
2796                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
2797                             permitted_adm_opens[i].port_to_connect);
2798 }
2799
2800 /* Try to start non-blocking connect to next host in cctx list */
2801 static int
2802 connect_next(struct channel_connect *cctx)
2803 {
2804         int sock, saved_errno;
2805         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2806
2807         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
2808                 if (cctx->ai->ai_family != AF_INET &&
2809                     cctx->ai->ai_family != AF_INET6)
2810                         continue;
2811                 if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
2812                     ntop, sizeof(ntop), strport, sizeof(strport),
2813                     NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2814                         error("connect_next: getnameinfo failed");
2815                         continue;
2816                 }
2817                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
2818                     cctx->ai->ai_protocol)) == -1) {
2819                         if (cctx->ai->ai_next == NULL)
2820                                 error("socket: %.100s", strerror(errno));
2821                         else
2822                                 verbose("socket: %.100s", strerror(errno));
2823                         continue;
2824                 }
2825                 if (set_nonblock(sock) == -1)
2826                         fatal("%s: set_nonblock(%d)", __func__, sock);
2827                 if (connect(sock, cctx->ai->ai_addr,
2828                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
2829                         debug("connect_next: host %.100s ([%.100s]:%s): "
2830                             "%.100s", cctx->host, ntop, strport,
2831                             strerror(errno));
2832                         saved_errno = errno;
2833                         close(sock);
2834                         errno = saved_errno;
2835                         continue;       /* fail -- try next */
2836                 }
2837                 debug("connect_next: host %.100s ([%.100s]:%s) "
2838                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
2839                 cctx->ai = cctx->ai->ai_next;
2840                 set_nodelay(sock);
2841                 return sock;
2842         }
2843         return -1;
2844 }
2845
2846 static void
2847 channel_connect_ctx_free(struct channel_connect *cctx)
2848 {
2849         xfree(cctx->host);
2850         if (cctx->aitop)
2851                 freeaddrinfo(cctx->aitop);
2852         bzero(cctx, sizeof(*cctx));
2853         cctx->host = NULL;
2854         cctx->ai = cctx->aitop = NULL;
2855 }
2856
2857 /* Return CONNECTING channel to remote host, port */
2858 static Channel *
2859 connect_to(const char *host, u_short port, char *ctype, char *rname)
2860 {
2861         struct addrinfo hints;
2862         int gaierr;
2863         int sock = -1;
2864         char strport[NI_MAXSERV];
2865         struct channel_connect cctx;
2866         Channel *c;
2867
2868         memset(&cctx, 0, sizeof(cctx));
2869         memset(&hints, 0, sizeof(hints));
2870         hints.ai_family = IPv4or6;
2871         hints.ai_socktype = SOCK_STREAM;
2872         snprintf(strport, sizeof strport, "%d", port);
2873         if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
2874                 error("connect_to %.100s: unknown host (%s)", host,
2875                     ssh_gai_strerror(gaierr));
2876                 return NULL;
2877         }
2878
2879         cctx.host = xstrdup(host);
2880         cctx.port = port;
2881         cctx.ai = cctx.aitop;
2882
2883         if ((sock = connect_next(&cctx)) == -1) {
2884                 error("connect to %.100s port %d failed: %s",
2885                     host, port, strerror(errno));
2886                 channel_connect_ctx_free(&cctx);
2887                 return NULL;
2888         }
2889         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
2890             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
2891         c->connect_ctx = cctx;
2892         return c;
2893 }
2894
2895 Channel *
2896 channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
2897 {
2898         int i;
2899
2900         for (i = 0; i < num_permitted_opens; i++) {
2901                 if (permitted_opens[i].host_to_connect != NULL &&
2902                     permitted_opens[i].listen_port == listen_port) {
2903                         return connect_to(
2904                             permitted_opens[i].host_to_connect,
2905                             permitted_opens[i].port_to_connect, ctype, rname);
2906                 }
2907         }
2908         error("WARNING: Server requests forwarding for unknown listen_port %d",
2909             listen_port);
2910         return NULL;
2911 }
2912
2913 /* Check if connecting to that port is permitted and connect. */
2914 Channel *
2915 channel_connect_to(const char *host, u_short port, char *ctype, char *rname)
2916 {
2917         int i, permit, permit_adm = 1;
2918
2919         permit = all_opens_permitted;
2920         if (!permit) {
2921                 for (i = 0; i < num_permitted_opens; i++)
2922                         if (permitted_opens[i].host_to_connect != NULL &&
2923                             permitted_opens[i].port_to_connect == port &&
2924                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2925                                 permit = 1;
2926         }
2927
2928         if (num_adm_permitted_opens > 0) {
2929                 permit_adm = 0;
2930                 for (i = 0; i < num_adm_permitted_opens; i++)
2931                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2932                             permitted_adm_opens[i].port_to_connect == port &&
2933                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2934                             == 0)
2935                                 permit_adm = 1;
2936         }
2937
2938         if (!permit || !permit_adm) {
2939                 logit("Received request to connect to host %.100s port %d, "
2940                     "but the request was denied.", host, port);
2941                 return NULL;
2942         }
2943         return connect_to(host, port, ctype, rname);
2944 }
2945
2946 void
2947 channel_send_window_changes(void)
2948 {
2949         u_int i;
2950         struct winsize ws;
2951
2952         for (i = 0; i < channels_alloc; i++) {
2953                 if (channels[i] == NULL || !channels[i]->client_tty ||
2954                     channels[i]->type != SSH_CHANNEL_OPEN)
2955                         continue;
2956                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2957                         continue;
2958                 channel_request_start(i, "window-change", 0);
2959                 packet_put_int((u_int)ws.ws_col);
2960                 packet_put_int((u_int)ws.ws_row);
2961                 packet_put_int((u_int)ws.ws_xpixel);
2962                 packet_put_int((u_int)ws.ws_ypixel);
2963                 packet_send();
2964         }
2965 }
2966
2967 /* -- X11 forwarding */
2968
2969 /*
2970  * Creates an internet domain socket for listening for X11 connections.
2971  * Returns 0 and a suitable display number for the DISPLAY variable
2972  * stored in display_numberp , or -1 if an error occurs.
2973  */
2974 int
2975 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2976     int single_connection, u_int *display_numberp, int **chanids)
2977 {
2978         Channel *nc = NULL;
2979         int display_number, sock;
2980         u_short port;
2981         struct addrinfo hints, *ai, *aitop;
2982         char strport[NI_MAXSERV];
2983         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2984
2985         if (chanids == NULL)
2986                 return -1;
2987
2988         for (display_number = x11_display_offset;
2989             display_number < MAX_DISPLAYS;
2990             display_number++) {
2991                 port = 6000 + display_number;
2992                 memset(&hints, 0, sizeof(hints));
2993                 hints.ai_family = IPv4or6;
2994                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2995                 hints.ai_socktype = SOCK_STREAM;
2996                 snprintf(strport, sizeof strport, "%d", port);
2997                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2998                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
2999                         return -1;
3000                 }
3001                 for (ai = aitop; ai; ai = ai->ai_next) {
3002                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3003                                 continue;
3004                         sock = socket(ai->ai_family, ai->ai_socktype,
3005                             ai->ai_protocol);
3006                         if (sock < 0) {
3007                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
3008                                         error("socket: %.100s", strerror(errno));
3009                                         freeaddrinfo(aitop);
3010                                         return -1;
3011                                 } else {
3012                                         debug("x11_create_display_inet: Socket family %d not supported",
3013                                                  ai->ai_family);
3014                                         continue;
3015                                 }
3016                         }
3017 #ifdef IPV6_V6ONLY
3018                         if (ai->ai_family == AF_INET6) {
3019                                 int on = 1;
3020                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
3021                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
3022                         }
3023 #endif
3024                         if (x11_use_localhost)
3025                                 channel_set_reuseaddr(sock);
3026                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3027                                 debug2("bind port %d: %.100s", port, strerror(errno));
3028                                 close(sock);
3029
3030                                 for (n = 0; n < num_socks; n++) {
3031                                         close(socks[n]);
3032                                 }
3033                                 num_socks = 0;
3034                                 break;
3035                         }
3036                         socks[num_socks++] = sock;
3037                         if (num_socks == NUM_SOCKS)
3038                                 break;
3039                 }
3040                 freeaddrinfo(aitop);
3041                 if (num_socks > 0)
3042                         break;
3043         }
3044         if (display_number >= MAX_DISPLAYS) {
3045                 error("Failed to allocate internet-domain X11 display socket.");
3046                 return -1;
3047         }
3048         /* Start listening for connections on the socket. */
3049         for (n = 0; n < num_socks; n++) {
3050                 sock = socks[n];
3051                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3052                         error("listen: %.100s", strerror(errno));
3053                         close(sock);
3054                         return -1;
3055                 }
3056         }
3057
3058         /* Allocate a channel for each socket. */
3059         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3060         for (n = 0; n < num_socks; n++) {
3061                 sock = socks[n];
3062                 nc = channel_new("x11 listener",
3063                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3064                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3065                     0, "X11 inet listener", 1);
3066                 nc->single_connection = single_connection;
3067                 (*chanids)[n] = nc->self;
3068         }
3069         (*chanids)[n] = -1;
3070
3071         /* Return the display number for the DISPLAY environment variable. */
3072         *display_numberp = display_number;
3073         return (0);
3074 }
3075
3076 static int
3077 connect_local_xsocket(u_int dnr)
3078 {
3079         int sock;
3080         struct sockaddr_un addr;
3081
3082         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3083         if (sock < 0)
3084                 error("socket: %.100s", strerror(errno));
3085         memset(&addr, 0, sizeof(addr));
3086         addr.sun_family = AF_UNIX;
3087         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
3088         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3089                 return sock;
3090         close(sock);
3091         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3092         return -1;
3093 }
3094
3095 int
3096 x11_connect_display(void)
3097 {
3098         u_int display_number;
3099         const char *display;
3100         char buf[1024], *cp;
3101         struct addrinfo hints, *ai, *aitop;
3102         char strport[NI_MAXSERV];
3103         int gaierr, sock = 0;
3104
3105         /* Try to open a socket for the local X server. */
3106         display = getenv("DISPLAY");
3107         if (!display) {
3108                 error("DISPLAY not set.");
3109                 return -1;
3110         }
3111         /*
3112          * Now we decode the value of the DISPLAY variable and make a
3113          * connection to the real X server.
3114          */
3115
3116         /*
3117          * Check if it is a unix domain socket.  Unix domain displays are in
3118          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
3119          */
3120         if (strncmp(display, "unix:", 5) == 0 ||
3121             display[0] == ':') {
3122                 /* Connect to the unix domain socket. */
3123                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3124                         error("Could not parse display number from DISPLAY: %.100s",
3125                             display);
3126                         return -1;
3127                 }
3128                 /* Create a socket. */
3129                 sock = connect_local_xsocket(display_number);
3130                 if (sock < 0)
3131                         return -1;
3132
3133                 /* OK, we now have a connection to the display. */
3134                 return sock;
3135         }
3136         /*
3137          * Connect to an inet socket.  The DISPLAY value is supposedly
3138          * hostname:d[.s], where hostname may also be numeric IP address.
3139          */
3140         strlcpy(buf, display, sizeof(buf));
3141         cp = strchr(buf, ':');
3142         if (!cp) {
3143                 error("Could not find ':' in DISPLAY: %.100s", display);
3144                 return -1;
3145         }
3146         *cp = 0;
3147         /* buf now contains the host name.  But first we parse the display number. */
3148         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3149                 error("Could not parse display number from DISPLAY: %.100s",
3150                     display);
3151                 return -1;
3152         }
3153
3154         /* Look up the host address */
3155         memset(&hints, 0, sizeof(hints));
3156         hints.ai_family = IPv4or6;
3157         hints.ai_socktype = SOCK_STREAM;
3158         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3159         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3160                 error("%.100s: unknown host. (%s)", buf,
3161                 ssh_gai_strerror(gaierr));
3162                 return -1;
3163         }
3164         for (ai = aitop; ai; ai = ai->ai_next) {
3165                 /* Create a socket. */
3166                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3167                 if (sock < 0) {
3168                         debug2("socket: %.100s", strerror(errno));
3169                         continue;
3170                 }
3171                 /* Connect it to the display. */
3172                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3173                         debug2("connect %.100s port %u: %.100s", buf,
3174                             6000 + display_number, strerror(errno));
3175                         close(sock);
3176                         continue;
3177                 }
3178                 /* Success */
3179                 break;
3180         }
3181         freeaddrinfo(aitop);
3182         if (!ai) {
3183                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3184                     strerror(errno));
3185                 return -1;
3186         }
3187         set_nodelay(sock);
3188         return sock;
3189 }
3190
3191 /*
3192  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3193  * the remote channel number.  We should do whatever we want, and respond
3194  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3195  */
3196
3197 /* ARGSUSED */
3198 void
3199 x11_input_open(int type, u_int32_t seq, void *ctxt)
3200 {
3201         Channel *c = NULL;
3202         int remote_id, sock = 0;
3203         char *remote_host;
3204
3205         debug("Received X11 open request.");
3206
3207         remote_id = packet_get_int();
3208
3209         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3210                 remote_host = packet_get_string(NULL);
3211         } else {
3212                 remote_host = xstrdup("unknown (remote did not supply name)");
3213         }
3214         packet_check_eom();
3215
3216         /* Obtain a connection to the real X display. */
3217         sock = x11_connect_display();
3218         if (sock != -1) {
3219                 /* Allocate a channel for this connection. */
3220                 c = channel_new("connected x11 socket",
3221                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3222                     remote_host, 1);
3223                 c->remote_id = remote_id;
3224                 c->force_drain = 1;
3225         }
3226         xfree(remote_host);
3227         if (c == NULL) {
3228                 /* Send refusal to the remote host. */
3229                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3230                 packet_put_int(remote_id);
3231         } else {
3232                 /* Send a confirmation to the remote host. */
3233                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3234                 packet_put_int(remote_id);
3235                 packet_put_int(c->self);
3236         }
3237         packet_send();
3238 }
3239
3240 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3241 /* ARGSUSED */
3242 void
3243 deny_input_open(int type, u_int32_t seq, void *ctxt)
3244 {
3245         int rchan = packet_get_int();
3246
3247         switch (type) {
3248         case SSH_SMSG_AGENT_OPEN:
3249                 error("Warning: ssh server tried agent forwarding.");
3250                 break;
3251         case SSH_SMSG_X11_OPEN:
3252                 error("Warning: ssh server tried X11 forwarding.");
3253                 break;
3254         default:
3255                 error("deny_input_open: type %d", type);
3256                 break;
3257         }
3258         error("Warning: this is probably a break-in attempt by a malicious server.");
3259         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3260         packet_put_int(rchan);
3261         packet_send();
3262 }
3263
3264 /*
3265  * Requests forwarding of X11 connections, generates fake authentication
3266  * data, and enables authentication spoofing.
3267  * This should be called in the client only.
3268  */
3269 void
3270 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3271     const char *proto, const char *data)
3272 {
3273         u_int data_len = (u_int) strlen(data) / 2;
3274         u_int i, value;
3275         char *new_data;
3276         int screen_number;
3277         const char *cp;
3278         u_int32_t rnd = 0;
3279
3280         if (x11_saved_display == NULL)
3281                 x11_saved_display = xstrdup(disp);
3282         else if (strcmp(disp, x11_saved_display) != 0) {
3283                 error("x11_request_forwarding_with_spoofing: different "
3284                     "$DISPLAY already forwarded");
3285                 return;
3286         }
3287
3288         cp = strchr(disp, ':');
3289         if (cp)
3290                 cp = strchr(cp, '.');
3291         if (cp)
3292                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3293         else
3294                 screen_number = 0;
3295
3296         if (x11_saved_proto == NULL) {
3297                 /* Save protocol name. */
3298                 x11_saved_proto = xstrdup(proto);
3299                 /*
3300                  * Extract real authentication data and generate fake data
3301                  * of the same length.
3302                  */
3303                 x11_saved_data = xmalloc(data_len);
3304                 x11_fake_data = xmalloc(data_len);
3305                 for (i = 0; i < data_len; i++) {
3306                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3307                                 fatal("x11_request_forwarding: bad "
3308                                     "authentication data: %.100s", data);
3309                         if (i % 4 == 0)
3310                                 rnd = arc4random();
3311                         x11_saved_data[i] = value;
3312                         x11_fake_data[i] = rnd & 0xff;
3313                         rnd >>= 8;
3314                 }
3315                 x11_saved_data_len = data_len;
3316                 x11_fake_data_len = data_len;
3317         }
3318
3319         /* Convert the fake data into hex. */
3320         new_data = tohex(x11_fake_data, data_len);
3321
3322         /* Send the request packet. */
3323         if (compat20) {
3324                 channel_request_start(client_session_id, "x11-req", 0);
3325                 packet_put_char(0);     /* XXX bool single connection */
3326         } else {
3327                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3328         }
3329         packet_put_cstring(proto);
3330         packet_put_cstring(new_data);
3331         packet_put_int(screen_number);
3332         packet_send();
3333         packet_write_wait();
3334         xfree(new_data);
3335 }
3336
3337
3338 /* -- agent forwarding */
3339
3340 /* Sends a message to the server to request authentication fd forwarding. */
3341
3342 void
3343 auth_request_forwarding(void)
3344 {
3345         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3346         packet_send();
3347         packet_write_wait();
3348 }