channels.c

   1 /* $OpenBSD: channels.c,v 1.341 2015/02/06 23:21:59 millert 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/param.h>  /* MIN MAX */
  46 #include <sys/stat.h>
  47 #include <sys/ioctl.h>
  48 #include <sys/un.h>
  49 #include <sys/socket.h>
  50 #ifdef HAVE_SYS_TIME_H
  51 # include <sys/time.h>
  52 #endif
  53
  54 #include <netinet/in.h>
  55 #include <arpa/inet.h>
  56
  57 #include <errno.h>
  58 #include <fcntl.h>
  59 #include <netdb.h>
  60 #ifdef HAVE_STDINT_H
  61 #include <stdint.h>
  62 #endif
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <string.h>
  66 #include <termios.h>
  67 #include <unistd.h>
  68 #include <stdarg.h>
  69
  70 #include "openbsd-compat/sys-queue.h"
  71 #include "xmalloc.h"
  72 #include "ssh.h"
  73 #include "ssh1.h"
  74 #include "ssh2.h"
  75 #include "packet.h"
  76 #include "log.h"
  77 #include "misc.h"
  78 #include "buffer.h"
  79 #include "channels.h"
  80 #include "compat.h"
  81 #include "canohost.h"
  82 #include "key.h"
  83 #include "authfd.h"
  84 #include "pathnames.h"
  85
  86 /* -- channel core */
  87
  88 /*
  89  * Pointer to an array containing all allocated channels.  The array is
  90  * dynamically extended as needed.
  91  */
  92 static Channel **channels = NULL;
  93
  94 /*
  95  * Size of the channel array.  All slots of the array must always be
  96  * initialized (at least the type field); unused slots set to NULL
  97  */
  98 static u_int channels_alloc = 0;
  99
 100 /*
 101  * Maximum file descriptor value used in any of the channels.  This is
 102  * updated in channel_new.
 103  */
 104 static int channel_max_fd = 0;
 105
 106
 107 /* -- tcp forwarding */
 108
 109 /*
 110  * Data structure for storing which hosts are permitted for forward requests.
 111  * The local sides of any remote forwards are stored in this array to prevent
 112  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
 113  * network (which might be behind a firewall).
 114  */
 115 /* XXX: streamlocal wants a path instead of host:port */
 116 /*      Overload host_to_connect; we could just make this match Forward */
 117 /*      XXX - can we use listen_host instead of listen_path? */
 118 typedef struct {
 119         char *host_to_connect;          /* Connect to 'host'. */
 120         int port_to_connect;            /* Connect to 'port'. */
 121         char *listen_host;              /* Remote side should listen address. */
 122         char *listen_path;              /* Remote side should listen path. */
 123         int listen_port;                /* Remote side should listen port. */
 124 } ForwardPermission;
 125
 126 /* List of all permitted host/port pairs to connect by the user. */
 127 static ForwardPermission *permitted_opens = NULL;
 128
 129 /* List of all permitted host/port pairs to connect by the admin. */
 130 static ForwardPermission *permitted_adm_opens = NULL;
 131
 132 /* Number of permitted host/port pairs in the array permitted by the user. */
 133 static int num_permitted_opens = 0;
 134
 135 /* Number of permitted host/port pair in the array permitted by the admin. */
 136 static int num_adm_permitted_opens = 0;
 137
 138 /* special-case port number meaning allow any port */
 139 #define FWD_PERMIT_ANY_PORT     0
 140
 141 /*
 142  * If this is true, all opens are permitted.  This is the case on the server
 143  * on which we have to trust the client anyway, and the user could do
 144  * anything after logging in anyway.
 145  */
 146 static int all_opens_permitted = 0;
 147
 148
 149 /* -- X11 forwarding */
 150
 151 /* Maximum number of fake X11 displays to try. */
 152 #define MAX_DISPLAYS  1000
 153
 154 /* Saved X11 local (client) display. */
 155 static char *x11_saved_display = NULL;
 156
 157 /* Saved X11 authentication protocol name. */
 158 static char *x11_saved_proto = NULL;
 159
 160 /* Saved X11 authentication data.  This is the real data. */
 161 static char *x11_saved_data = NULL;
 162 static u_int x11_saved_data_len = 0;
 163
 164 /*
 165  * Fake X11 authentication data.  This is what the server will be sending us;
 166  * we should replace any occurrences of this by the real data.
 167  */
 168 static u_char *x11_fake_data = NULL;
 169 static u_int x11_fake_data_len;
 170
 171
 172 /* -- agent forwarding */
 173
 174 #define NUM_SOCKS       10
 175
 176 /* AF_UNSPEC or AF_INET or AF_INET6 */
 177 static int IPv4or6 = AF_UNSPEC;
 178
 179 /* helper */
 180 static void port_open_helper(Channel *c, char *rtype);
 181
 182 /* non-blocking connect helpers */
 183 static int connect_next(struct channel_connect *);
 184 static void channel_connect_ctx_free(struct channel_connect *);
 185
 186 /* -- channel core */
 187
 188 Channel *
 189 channel_by_id(int id)
 190 {
 191         Channel *c;
 192
 193         if (id < 0 || (u_int)id >= channels_alloc) {
 194                 logit("channel_by_id: %d: bad id", id);
 195                 return NULL;
 196         }
 197         c = channels[id];
 198         if (c == NULL) {
 199                 logit("channel_by_id: %d: bad id: channel free", id);
 200                 return NULL;
 201         }
 202         return c;
 203 }
 204
 205 /*
 206  * Returns the channel if it is allowed to receive protocol messages.
 207  * Private channels, like listening sockets, may not receive messages.
 208  */
 209 Channel *
 210 channel_lookup(int id)
 211 {
 212         Channel *c;
 213
 214         if ((c = channel_by_id(id)) == NULL)
 215                 return (NULL);
 216
 217         switch (c->type) {
 218         case SSH_CHANNEL_X11_OPEN:
 219         case SSH_CHANNEL_LARVAL:
 220         case SSH_CHANNEL_CONNECTING:
 221         case SSH_CHANNEL_DYNAMIC:
 222         case SSH_CHANNEL_OPENING:
 223         case SSH_CHANNEL_OPEN:
 224         case SSH_CHANNEL_INPUT_DRAINING:
 225         case SSH_CHANNEL_OUTPUT_DRAINING:
 226         case SSH_CHANNEL_ABANDONED:
 227                 return (c);
 228         }
 229         logit("Non-public channel %d, type %d.", id, c->type);
 230         return (NULL);
 231 }
 232
 233 /*
 234  * Register filedescriptors for a channel, used when allocating a channel or
 235  * when the channel consumer/producer is ready, e.g. shell exec'd
 236  */
 237 static void
 238 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
 239     int extusage, int nonblock, int is_tty)
 240 {
 241         /* Update the maximum file descriptor value. */
 242         channel_max_fd = MAX(channel_max_fd, rfd);
 243         channel_max_fd = MAX(channel_max_fd, wfd);
 244         channel_max_fd = MAX(channel_max_fd, efd);
 245
 246         if (rfd != -1)
 247                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
 248         if (wfd != -1 && wfd != rfd)
 249                 fcntl(wfd, F_SETFD, FD_CLOEXEC);
 250         if (efd != -1 && efd != rfd && efd != wfd)
 251                 fcntl(efd, F_SETFD, FD_CLOEXEC);
 252
 253         c->rfd = rfd;
 254         c->wfd = wfd;
 255         c->sock = (rfd == wfd) ? rfd : -1;
 256         c->efd = efd;
 257         c->extended_usage = extusage;
 258
 259         if ((c->isatty = is_tty) != 0)
 260                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
 261 #ifdef _AIX
 262         /* XXX: Later AIX versions can't push as much data to tty */
 263         c->wfd_isatty = is_tty || isatty(c->wfd);
 264 #endif
 265
 266         /* enable nonblocking mode */
 267         if (nonblock) {
 268                 if (rfd != -1)
 269                         set_nonblock(rfd);
 270                 if (wfd != -1)
 271                         set_nonblock(wfd);
 272                 if (efd != -1)
 273                         set_nonblock(efd);
 274         }
 275 }
 276
 277 /*
 278  * Allocate a new channel object and set its type and socket. This will cause
 279  * remote_name to be freed.
 280  */
 281 Channel *
 282 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
 283     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 284 {
 285         int found;
 286         u_int i;
 287         Channel *c;
 288
 289         /* Do initial allocation if this is the first call. */
 290         if (channels_alloc == 0) {
 291                 channels_alloc = 10;
 292                 channels = xcalloc(channels_alloc, sizeof(Channel *));
 293                 for (i = 0; i < channels_alloc; i++)
 294                         channels[i] = NULL;
 295         }
 296         /* Try to find a free slot where to put the new channel. */
 297         for (found = -1, i = 0; i < channels_alloc; i++)
 298                 if (channels[i] == NULL) {
 299                         /* Found a free slot. */
 300                         found = (int)i;
 301                         break;
 302                 }
 303         if (found < 0) {
 304                 /* There are no free slots.  Take last+1 slot and expand the array.  */
 305                 found = channels_alloc;
 306                 if (channels_alloc > 10000)
 307                         fatal("channel_new: internal error: channels_alloc %d "
 308                             "too big.", channels_alloc);
 309                 channels = xrealloc(channels, channels_alloc + 10,
 310                     sizeof(Channel *));
 311                 channels_alloc += 10;
 312                 debug2("channel: expanding %d", channels_alloc);
 313                 for (i = found; i < channels_alloc; i++)
 314                         channels[i] = NULL;
 315         }
 316         /* Initialize and return new channel. */
 317         c = channels[found] = xcalloc(1, sizeof(Channel));
 318         buffer_init(&c->input);
 319         buffer_init(&c->output);
 320         buffer_init(&c->extended);
 321         c->path = NULL;
 322         c->listening_addr = NULL;
 323         c->listening_port = 0;
 324         c->ostate = CHAN_OUTPUT_OPEN;
 325         c->istate = CHAN_INPUT_OPEN;
 326         c->flags = 0;
 327         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
 328         c->notbefore = 0;
 329         c->self = found;
 330         c->type = type;
 331         c->ctype = ctype;
 332         c->local_window = window;
 333         c->local_window_max = window;
 334         c->local_consumed = 0;
 335         c->local_maxpacket = maxpack;
 336         c->remote_id = -1;
 337         c->remote_name = xstrdup(remote_name);
 338         c->remote_window = 0;
 339         c->remote_maxpacket = 0;
 340         c->force_drain = 0;
 341         c->single_connection = 0;
 342         c->detach_user = NULL;
 343         c->detach_close = 0;
 344         c->open_confirm = NULL;
 345         c->open_confirm_ctx = NULL;
 346         c->input_filter = NULL;
 347         c->output_filter = NULL;
 348         c->filter_ctx = NULL;
 349         c->filter_cleanup = NULL;
 350         c->ctl_chan = -1;
 351         c->mux_rcb = NULL;
 352         c->mux_ctx = NULL;
 353         c->mux_pause = 0;
 354         c->delayed = 1;         /* prevent call to channel_post handler */
 355         TAILQ_INIT(&c->status_confirms);
 356         debug("channel %d: new [%s]", found, remote_name);
 357         return c;
 358 }
 359
 360 static int
 361 channel_find_maxfd(void)
 362 {
 363         u_int i;
 364         int max = 0;
 365         Channel *c;
 366
 367         for (i = 0; i < channels_alloc; i++) {
 368                 c = channels[i];
 369                 if (c != NULL) {
 370                         max = MAX(max, c->rfd);
 371                         max = MAX(max, c->wfd);
 372                         max = MAX(max, c->efd);
 373                 }
 374         }
 375         return max;
 376 }
 377
 378 int
 379 channel_close_fd(int *fdp)
 380 {
 381         int ret = 0, fd = *fdp;
 382
 383         if (fd != -1) {
 384                 ret = close(fd);
 385                 *fdp = -1;
 386                 if (fd == channel_max_fd)
 387                         channel_max_fd = channel_find_maxfd();
 388         }
 389         return ret;
 390 }
 391
 392 /* Close all channel fd/socket. */
 393 static void
 394 channel_close_fds(Channel *c)
 395 {
 396         channel_close_fd(&c->sock);
 397         channel_close_fd(&c->rfd);
 398         channel_close_fd(&c->wfd);
 399         channel_close_fd(&c->efd);
 400 }
 401
 402 /* Free the channel and close its fd/socket. */
 403 void
 404 channel_free(Channel *c)
 405 {
 406         char *s;
 407         u_int i, n;
 408         struct channel_confirm *cc;
 409
 410         for (n = 0, i = 0; i < channels_alloc; i++)
 411                 if (channels[i])
 412                         n++;
 413         debug("channel %d: free: %s, nchannels %u", c->self,
 414             c->remote_name ? c->remote_name : "???", n);
 415
 416         s = channel_open_message();
 417         debug3("channel %d: status: %s", c->self, s);
 418         free(s);
 419
 420         if (c->sock != -1)
 421                 shutdown(c->sock, SHUT_RDWR);
 422         channel_close_fds(c);
 423         buffer_free(&c->input);
 424         buffer_free(&c->output);
 425         buffer_free(&c->extended);
 426         free(c->remote_name);
 427         c->remote_name = NULL;
 428         free(c->path);
 429         c->path = NULL;
 430         free(c->listening_addr);
 431         c->listening_addr = NULL;
 432         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 433                 if (cc->abandon_cb != NULL)
 434                         cc->abandon_cb(c, cc->ctx);
 435                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
 436                 explicit_bzero(cc, sizeof(*cc));
 437                 free(cc);
 438         }
 439         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
 440                 c->filter_cleanup(c->self, c->filter_ctx);
 441         channels[c->self] = NULL;
 442         free(c);
 443 }
 444
 445 void
 446 channel_free_all(void)
 447 {
 448         u_int i;
 449
 450         for (i = 0; i < channels_alloc; i++)
 451                 if (channels[i] != NULL)
 452                         channel_free(channels[i]);
 453 }
 454
 455 /*
 456  * Closes the sockets/fds of all channels.  This is used to close extra file
 457  * descriptors after a fork.
 458  */
 459 void
 460 channel_close_all(void)
 461 {
 462         u_int i;
 463
 464         for (i = 0; i < channels_alloc; i++)
 465                 if (channels[i] != NULL)
 466                         channel_close_fds(channels[i]);
 467 }
 468
 469 /*
 470  * Stop listening to channels.
 471  */
 472 void
 473 channel_stop_listening(void)
 474 {
 475         u_int i;
 476         Channel *c;
 477
 478         for (i = 0; i < channels_alloc; i++) {
 479                 c = channels[i];
 480                 if (c != NULL) {
 481                         switch (c->type) {
 482                         case SSH_CHANNEL_AUTH_SOCKET:
 483                         case SSH_CHANNEL_PORT_LISTENER:
 484                         case SSH_CHANNEL_RPORT_LISTENER:
 485                         case SSH_CHANNEL_X11_LISTENER:
 486                         case SSH_CHANNEL_UNIX_LISTENER:
 487                         case SSH_CHANNEL_RUNIX_LISTENER:
 488                                 channel_close_fd(&c->sock);
 489                                 channel_free(c);
 490                                 break;
 491                         }
 492                 }
 493         }
 494 }
 495
 496 /*
 497  * Returns true if no channel has too much buffered data, and false if one or
 498  * more channel is overfull.
 499  */
 500 int
 501 channel_not_very_much_buffered_data(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 && c->type == SSH_CHANNEL_OPEN) {
 509 #if 0
 510                         if (!compat20 &&
 511                             buffer_len(&c->input) > packet_get_maxsize()) {
 512                                 debug2("channel %d: big input buffer %d",
 513                                     c->self, buffer_len(&c->input));
 514                                 return 0;
 515                         }
 516 #endif
 517                         if (buffer_len(&c->output) > packet_get_maxsize()) {
 518                                 debug2("channel %d: big output buffer %u > %u",
 519                                     c->self, buffer_len(&c->output),
 520                                     packet_get_maxsize());
 521                                 return 0;
 522                         }
 523                 }
 524         }
 525         return 1;
 526 }
 527
 528 /* Returns true if any channel is still open. */
 529 int
 530 channel_still_open(void)
 531 {
 532         u_int i;
 533         Channel *c;
 534
 535         for (i = 0; i < channels_alloc; i++) {
 536                 c = channels[i];
 537                 if (c == NULL)
 538                         continue;
 539                 switch (c->type) {
 540                 case SSH_CHANNEL_X11_LISTENER:
 541                 case SSH_CHANNEL_PORT_LISTENER:
 542                 case SSH_CHANNEL_RPORT_LISTENER:
 543                 case SSH_CHANNEL_MUX_LISTENER:
 544                 case SSH_CHANNEL_CLOSED:
 545                 case SSH_CHANNEL_AUTH_SOCKET:
 546                 case SSH_CHANNEL_DYNAMIC:
 547                 case SSH_CHANNEL_CONNECTING:
 548                 case SSH_CHANNEL_ZOMBIE:
 549                 case SSH_CHANNEL_ABANDONED:
 550                 case SSH_CHANNEL_UNIX_LISTENER:
 551                 case SSH_CHANNEL_RUNIX_LISTENER:
 552                         continue;
 553                 case SSH_CHANNEL_LARVAL:
 554                         if (!compat20)
 555                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
 556                         continue;
 557                 case SSH_CHANNEL_OPENING:
 558                 case SSH_CHANNEL_OPEN:
 559                 case SSH_CHANNEL_X11_OPEN:
 560                 case SSH_CHANNEL_MUX_CLIENT:
 561                         return 1;
 562                 case SSH_CHANNEL_INPUT_DRAINING:
 563                 case SSH_CHANNEL_OUTPUT_DRAINING:
 564                         if (!compat13)
 565                                 fatal("cannot happen: OUT_DRAIN");
 566                         return 1;
 567                 default:
 568                         fatal("channel_still_open: bad channel type %d", c->type);
 569                         /* NOTREACHED */
 570                 }
 571         }
 572         return 0;
 573 }
 574
 575 /* Returns the id of an open channel suitable for keepaliving */
 576 int
 577 channel_find_open(void)
 578 {
 579         u_int i;
 580         Channel *c;
 581
 582         for (i = 0; i < channels_alloc; i++) {
 583                 c = channels[i];
 584                 if (c == NULL || c->remote_id < 0)
 585                         continue;
 586                 switch (c->type) {
 587                 case SSH_CHANNEL_CLOSED:
 588                 case SSH_CHANNEL_DYNAMIC:
 589                 case SSH_CHANNEL_X11_LISTENER:
 590                 case SSH_CHANNEL_PORT_LISTENER:
 591                 case SSH_CHANNEL_RPORT_LISTENER:
 592                 case SSH_CHANNEL_MUX_LISTENER:
 593                 case SSH_CHANNEL_MUX_CLIENT:
 594                 case SSH_CHANNEL_OPENING:
 595                 case SSH_CHANNEL_CONNECTING:
 596                 case SSH_CHANNEL_ZOMBIE:
 597                 case SSH_CHANNEL_ABANDONED:
 598                 case SSH_CHANNEL_UNIX_LISTENER:
 599                 case SSH_CHANNEL_RUNIX_LISTENER:
 600                         continue;
 601                 case SSH_CHANNEL_LARVAL:
 602                 case SSH_CHANNEL_AUTH_SOCKET:
 603                 case SSH_CHANNEL_OPEN:
 604                 case SSH_CHANNEL_X11_OPEN:
 605                         return i;
 606                 case SSH_CHANNEL_INPUT_DRAINING:
 607                 case SSH_CHANNEL_OUTPUT_DRAINING:
 608                         if (!compat13)
 609                                 fatal("cannot happen: OUT_DRAIN");
 610                         return i;
 611                 default:
 612                         fatal("channel_find_open: bad channel type %d", c->type);
 613                         /* NOTREACHED */
 614                 }
 615         }
 616         return -1;
 617 }
 618
 619
 620 /*
 621  * Returns a message describing the currently open forwarded connections,
 622  * suitable for sending to the client.  The message contains crlf pairs for
 623  * newlines.
 624  */
 625 char *
 626 channel_open_message(void)
 627 {
 628         Buffer buffer;
 629         Channel *c;
 630         char buf[1024], *cp;
 631         u_int i;
 632
 633         buffer_init(&buffer);
 634         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
 635         buffer_append(&buffer, buf, strlen(buf));
 636         for (i = 0; i < channels_alloc; i++) {
 637                 c = channels[i];
 638                 if (c == NULL)
 639                         continue;
 640                 switch (c->type) {
 641                 case SSH_CHANNEL_X11_LISTENER:
 642                 case SSH_CHANNEL_PORT_LISTENER:
 643                 case SSH_CHANNEL_RPORT_LISTENER:
 644                 case SSH_CHANNEL_CLOSED:
 645                 case SSH_CHANNEL_AUTH_SOCKET:
 646                 case SSH_CHANNEL_ZOMBIE:
 647                 case SSH_CHANNEL_ABANDONED:
 648                 case SSH_CHANNEL_MUX_CLIENT:
 649                 case SSH_CHANNEL_MUX_LISTENER:
 650                 case SSH_CHANNEL_UNIX_LISTENER:
 651                 case SSH_CHANNEL_RUNIX_LISTENER:
 652                         continue;
 653                 case SSH_CHANNEL_LARVAL:
 654                 case SSH_CHANNEL_OPENING:
 655                 case SSH_CHANNEL_CONNECTING:
 656                 case SSH_CHANNEL_DYNAMIC:
 657                 case SSH_CHANNEL_OPEN:
 658                 case SSH_CHANNEL_X11_OPEN:
 659                 case SSH_CHANNEL_INPUT_DRAINING:
 660                 case SSH_CHANNEL_OUTPUT_DRAINING:
 661                         snprintf(buf, sizeof buf,
 662                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cc %d)\r\n",
 663                             c->self, c->remote_name,
 664                             c->type, c->remote_id,
 665                             c->istate, buffer_len(&c->input),
 666                             c->ostate, buffer_len(&c->output),
 667                             c->rfd, c->wfd, c->ctl_chan);
 668                         buffer_append(&buffer, buf, strlen(buf));
 669                         continue;
 670                 default:
 671                         fatal("channel_open_message: bad channel type %d", c->type);
 672                         /* NOTREACHED */
 673                 }
 674         }
 675         buffer_append(&buffer, "\0", 1);
 676         cp = xstrdup((char *)buffer_ptr(&buffer));
 677         buffer_free(&buffer);
 678         return cp;
 679 }
 680
 681 void
 682 channel_send_open(int id)
 683 {
 684         Channel *c = channel_lookup(id);
 685
 686         if (c == NULL) {
 687                 logit("channel_send_open: %d: bad id", id);
 688                 return;
 689         }
 690         debug2("channel %d: send open", id);
 691         packet_start(SSH2_MSG_CHANNEL_OPEN);
 692         packet_put_cstring(c->ctype);
 693         packet_put_int(c->self);
 694         packet_put_int(c->local_window);
 695         packet_put_int(c->local_maxpacket);
 696         packet_send();
 697 }
 698
 699 void
 700 channel_request_start(int id, char *service, int wantconfirm)
 701 {
 702         Channel *c = channel_lookup(id);
 703
 704         if (c == NULL) {
 705                 logit("channel_request_start: %d: unknown channel id", id);
 706                 return;
 707         }
 708         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
 709         packet_start(SSH2_MSG_CHANNEL_REQUEST);
 710         packet_put_int(c->remote_id);
 711         packet_put_cstring(service);
 712         packet_put_char(wantconfirm);
 713 }
 714
 715 void
 716 channel_register_status_confirm(int id, channel_confirm_cb *cb,
 717     channel_confirm_abandon_cb *abandon_cb, void *ctx)
 718 {
 719         struct channel_confirm *cc;
 720         Channel *c;
 721
 722         if ((c = channel_lookup(id)) == NULL)
 723                 fatal("channel_register_expect: %d: bad id", id);
 724
 725         cc = xcalloc(1, sizeof(*cc));
 726         cc->cb = cb;
 727         cc->abandon_cb = abandon_cb;
 728         cc->ctx = ctx;
 729         TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
 730 }
 731
 732 void
 733 channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
 734 {
 735         Channel *c = channel_lookup(id);
 736
 737         if (c == NULL) {
 738                 logit("channel_register_open_confirm: %d: bad id", id);
 739                 return;
 740         }
 741         c->open_confirm = fn;
 742         c->open_confirm_ctx = ctx;
 743 }
 744
 745 void
 746 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 747 {
 748         Channel *c = channel_by_id(id);
 749
 750         if (c == NULL) {
 751                 logit("channel_register_cleanup: %d: bad id", id);
 752                 return;
 753         }
 754         c->detach_user = fn;
 755         c->detach_close = do_close;
 756 }
 757
 758 void
 759 channel_cancel_cleanup(int id)
 760 {
 761         Channel *c = channel_by_id(id);
 762
 763         if (c == NULL) {
 764                 logit("channel_cancel_cleanup: %d: bad id", id);
 765                 return;
 766         }
 767         c->detach_user = NULL;
 768         c->detach_close = 0;
 769 }
 770
 771 void
 772 channel_register_filter(int id, channel_infilter_fn *ifn,
 773     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 774 {
 775         Channel *c = channel_lookup(id);
 776
 777         if (c == NULL) {
 778                 logit("channel_register_filter: %d: bad id", id);
 779                 return;
 780         }
 781         c->input_filter = ifn;
 782         c->output_filter = ofn;
 783         c->filter_ctx = ctx;
 784         c->filter_cleanup = cfn;
 785 }
 786
 787 void
 788 channel_set_fds(int id, int rfd, int wfd, int efd,
 789     int extusage, int nonblock, int is_tty, u_int window_max)
 790 {
 791         Channel *c = channel_lookup(id);
 792
 793         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
 794                 fatal("channel_activate for non-larval channel %d.", id);
 795         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
 796         c->type = SSH_CHANNEL_OPEN;
 797         c->local_window = c->local_window_max = window_max;
 798         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
 799         packet_put_int(c->remote_id);
 800         packet_put_int(c->local_window);
 801         packet_send();
 802 }
 803
 804 /*
 805  * 'channel_pre*' are called just before select() to add any bits relevant to
 806  * channels in the select bitmasks.
 807  */
 808 /*
 809  * 'channel_post*': perform any appropriate operations for channels which
 810  * have events pending.
 811  */
 812 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
 813 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
 814 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
 815
 816 /* ARGSUSED */
 817 static void
 818 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
 819 {
 820         FD_SET(c->sock, readset);
 821 }
 822
 823 /* ARGSUSED */
 824 static void
 825 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
 826 {
 827         debug3("channel %d: waiting for connection", c->self);
 828         FD_SET(c->sock, writeset);
 829 }
 830
 831 static void
 832 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 833 {
 834         if (buffer_len(&c->input) < packet_get_maxsize())
 835                 FD_SET(c->sock, readset);
 836         if (buffer_len(&c->output) > 0)
 837                 FD_SET(c->sock, writeset);
 838 }
 839
 840 static void
 841 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
 842 {
 843         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
 844
 845         if (c->istate == CHAN_INPUT_OPEN &&
 846             limit > 0 &&
 847             buffer_len(&c->input) < limit &&
 848             buffer_check_alloc(&c->input, CHAN_RBUF))
 849                 FD_SET(c->rfd, readset);
 850         if (c->ostate == CHAN_OUTPUT_OPEN ||
 851             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 852                 if (buffer_len(&c->output) > 0) {
 853                         FD_SET(c->wfd, writeset);
 854                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
 855                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
 856                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
 857                                     c->self, c->efd, buffer_len(&c->extended));
 858                         else
 859                                 chan_obuf_empty(c);
 860                 }
 861         }
 862         /** XXX check close conditions, too */
 863         if (compat20 && c->efd != -1 &&
 864             !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
 865                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
 866                     buffer_len(&c->extended) > 0)
 867                         FD_SET(c->efd, writeset);
 868                 else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
 869                     (c->extended_usage == CHAN_EXTENDED_READ ||
 870                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
 871                     buffer_len(&c->extended) < c->remote_window)
 872                         FD_SET(c->efd, readset);
 873         }
 874         /* XXX: What about efd? races? */
 875 }
 876
 877 /* ARGSUSED */
 878 static void
 879 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
 880 {
 881         if (buffer_len(&c->input) == 0) {
 882                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 883                 packet_put_int(c->remote_id);
 884                 packet_send();
 885                 c->type = SSH_CHANNEL_CLOSED;
 886                 debug2("channel %d: closing after input drain.", c->self);
 887         }
 888 }
 889
 890 /* ARGSUSED */
 891 static void
 892 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
 893 {
 894         if (buffer_len(&c->output) == 0)
 895                 chan_mark_dead(c);
 896         else
 897                 FD_SET(c->sock, writeset);
 898 }
 899
 900 /*
 901  * This is a special state for X11 authentication spoofing.  An opened X11
 902  * connection (when authentication spoofing is being done) remains in this
 903  * state until the first packet has been completely read.  The authentication
 904  * data in that packet is then substituted by the real data if it matches the
 905  * fake data, and the channel is put into normal mode.
 906  * XXX All this happens at the client side.
 907  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
 908  */
 909 static int
 910 x11_open_helper(Buffer *b)
 911 {
 912         u_char *ucp;
 913         u_int proto_len, data_len;
 914
 915         /* Check if the fixed size part of the packet is in buffer. */
 916         if (buffer_len(b) < 12)
 917                 return 0;
 918
 919         /* Parse the lengths of variable-length fields. */
 920         ucp = buffer_ptr(b);
 921         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
 922                 proto_len = 256 * ucp[6] + ucp[7];
 923                 data_len = 256 * ucp[8] + ucp[9];
 924         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
 925                 proto_len = ucp[6] + 256 * ucp[7];
 926                 data_len = ucp[8] + 256 * ucp[9];
 927         } else {
 928                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
 929                     ucp[0]);
 930                 return -1;
 931         }
 932
 933         /* Check if the whole packet is in buffer. */
 934         if (buffer_len(b) <
 935             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
 936                 return 0;
 937
 938         /* Check if authentication protocol matches. */
 939         if (proto_len != strlen(x11_saved_proto) ||
 940             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
 941                 debug2("X11 connection uses different authentication protocol.");
 942                 return -1;
 943         }
 944         /* Check if authentication data matches our fake data. */
 945         if (data_len != x11_fake_data_len ||
 946             timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
 947                 x11_fake_data, x11_fake_data_len) != 0) {
 948                 debug2("X11 auth data does not match fake data.");
 949                 return -1;
 950         }
 951         /* Check fake data length */
 952         if (x11_fake_data_len != x11_saved_data_len) {
 953                 error("X11 fake_data_len %d != saved_data_len %d",
 954                     x11_fake_data_len, x11_saved_data_len);
 955                 return -1;
 956         }
 957         /*
 958          * Received authentication protocol and data match
 959          * our fake data. Substitute the fake data with real
 960          * data.
 961          */
 962         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
 963             x11_saved_data, x11_saved_data_len);
 964         return 1;
 965 }
 966
 967 static void
 968 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
 969 {
 970         int ret = x11_open_helper(&c->output);
 971
 972         if (ret == 1) {
 973                 /* Start normal processing for the channel. */
 974                 c->type = SSH_CHANNEL_OPEN;
 975                 channel_pre_open_13(c, readset, writeset);
 976         } else if (ret == -1) {
 977                 /*
 978                  * We have received an X11 connection that has bad
 979                  * authentication information.
 980                  */
 981                 logit("X11 connection rejected because of wrong authentication.");
 982                 buffer_clear(&c->input);
 983                 buffer_clear(&c->output);
 984                 channel_close_fd(&c->sock);
 985                 c->sock = -1;
 986                 c->type = SSH_CHANNEL_CLOSED;
 987                 packet_start(SSH_MSG_CHANNEL_CLOSE);
 988                 packet_put_int(c->remote_id);
 989                 packet_send();
 990         }
 991 }
 992
 993 static void
 994 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
 995 {
 996         int ret = x11_open_helper(&c->output);
 997
 998         /* c->force_drain = 1; */
 999
1000         if (ret == 1) {
1001                 c->type = SSH_CHANNEL_OPEN;
1002                 channel_pre_open(c, readset, writeset);
1003         } else if (ret == -1) {
1004                 logit("X11 connection rejected because of wrong authentication.");
1005                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
1006                 chan_read_failed(c);
1007                 buffer_clear(&c->input);
1008                 chan_ibuf_empty(c);
1009                 buffer_clear(&c->output);
1010                 /* for proto v1, the peer will send an IEOF */
1011                 if (compat20)
1012                         chan_write_failed(c);
1013                 else
1014                         c->type = SSH_CHANNEL_OPEN;
1015                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
1016         }
1017 }
1018
1019 static void
1020 channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1021 {
1022         if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
1023             buffer_check_alloc(&c->input, CHAN_RBUF))
1024                 FD_SET(c->rfd, readset);
1025         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1026                 /* clear buffer immediately (discard any partial packet) */
1027                 buffer_clear(&c->input);
1028                 chan_ibuf_empty(c);
1029                 /* Start output drain. XXX just kill chan? */
1030                 chan_rcvd_oclose(c);
1031         }
1032         if (c->ostate == CHAN_OUTPUT_OPEN ||
1033             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
1034                 if (buffer_len(&c->output) > 0)
1035                         FD_SET(c->wfd, writeset);
1036                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
1037                         chan_obuf_empty(c);
1038         }
1039 }
1040
1041 /* try to decode a socks4 header */
1042 /* ARGSUSED */
1043 static int
1044 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
1045 {
1046         char *p, *host;
1047         u_int len, have, i, found, need;
1048         char username[256];
1049         struct {
1050                 u_int8_t version;
1051                 u_int8_t command;
1052                 u_int16_t dest_port;
1053                 struct in_addr dest_addr;
1054         } s4_req, s4_rsp;
1055
1056         debug2("channel %d: decode socks4", c->self);
1057
1058         have = buffer_len(&c->input);
1059         len = sizeof(s4_req);
1060         if (have < len)
1061                 return 0;
1062         p = (char *)buffer_ptr(&c->input);
1063
1064         need = 1;
1065         /* SOCKS4A uses an invalid IP address 0.0.0.x */
1066         if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
1067                 debug2("channel %d: socks4a request", c->self);
1068                 /* ... and needs an extra string (the hostname) */
1069                 need = 2;
1070         }
1071         /* Check for terminating NUL on the string(s) */
1072         for (found = 0, i = len; i < have; i++) {
1073                 if (p[i] == '\0') {
1074                         found++;
1075                         if (found == need)
1076                                 break;
1077                 }
1078                 if (i > 1024) {
1079                         /* the peer is probably sending garbage */
1080                         debug("channel %d: decode socks4: too long",
1081                             c->self);
1082                         return -1;
1083                 }
1084         }
1085         if (found < need)
1086                 return 0;
1087         buffer_get(&c->input, (char *)&s4_req.version, 1);
1088         buffer_get(&c->input, (char *)&s4_req.command, 1);
1089         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
1090         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
1091         have = buffer_len(&c->input);
1092         p = (char *)buffer_ptr(&c->input);
1093         if (memchr(p, '\0', have) == NULL)
1094                 fatal("channel %d: decode socks4: user not nul terminated",
1095                     c->self);
1096         len = strlen(p);
1097         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
1098         len++;                                  /* trailing '\0' */
1099         if (len > have)
1100                 fatal("channel %d: decode socks4: len %d > have %d",
1101                     c->self, len, have);
1102         strlcpy(username, p, sizeof(username));
1103         buffer_consume(&c->input, len);
1104
1105         free(c->path);
1106         c->path = NULL;
1107         if (need == 1) {                        /* SOCKS4: one string */
1108                 host = inet_ntoa(s4_req.dest_addr);
1109                 c->path = xstrdup(host);
1110         } else {                                /* SOCKS4A: two strings */
1111                 have = buffer_len(&c->input);
1112                 p = (char *)buffer_ptr(&c->input);
1113                 len = strlen(p);
1114                 debug2("channel %d: decode socks4a: host %s/%d",
1115                     c->self, p, len);
1116                 len++;                          /* trailing '\0' */
1117                 if (len > have)
1118                         fatal("channel %d: decode socks4a: len %d > have %d",
1119                             c->self, len, have);
1120                 if (len > NI_MAXHOST) {
1121                         error("channel %d: hostname \"%.100s\" too long",
1122                             c->self, p);
1123                         return -1;
1124                 }
1125                 c->path = xstrdup(p);
1126                 buffer_consume(&c->input, len);
1127         }
1128         c->host_port = ntohs(s4_req.dest_port);
1129
1130         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1131             c->self, c->path, c->host_port, s4_req.command);
1132
1133         if (s4_req.command != 1) {
1134                 debug("channel %d: cannot handle: %s cn %d",
1135                     c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command);
1136                 return -1;
1137         }
1138         s4_rsp.version = 0;                     /* vn: 0 for reply */
1139         s4_rsp.command = 90;                    /* cd: req granted */
1140         s4_rsp.dest_port = 0;                   /* ignored */
1141         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1142         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1143         return 1;
1144 }
1145
1146 /* try to decode a socks5 header */
1147 #define SSH_SOCKS5_AUTHDONE     0x1000
1148 #define SSH_SOCKS5_NOAUTH       0x00
1149 #define SSH_SOCKS5_IPV4         0x01
1150 #define SSH_SOCKS5_DOMAIN       0x03
1151 #define SSH_SOCKS5_IPV6         0x04
1152 #define SSH_SOCKS5_CONNECT      0x01
1153 #define SSH_SOCKS5_SUCCESS      0x00
1154
1155 /* ARGSUSED */
1156 static int
1157 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1158 {
1159         struct {
1160                 u_int8_t version;
1161                 u_int8_t command;
1162                 u_int8_t reserved;
1163                 u_int8_t atyp;
1164         } s5_req, s5_rsp;
1165         u_int16_t dest_port;
1166         char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
1167         u_char *p;
1168         u_int have, need, i, found, nmethods, addrlen, af;
1169
1170         debug2("channel %d: decode socks5", c->self);
1171         p = buffer_ptr(&c->input);
1172         if (p[0] != 0x05)
1173                 return -1;
1174         have = buffer_len(&c->input);
1175         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1176                 /* format: ver | nmethods | methods */
1177                 if (have < 2)
1178                         return 0;
1179                 nmethods = p[1];
1180                 if (have < nmethods + 2)
1181                         return 0;
1182                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1183                 for (found = 0, i = 2; i < nmethods + 2; i++) {
1184                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1185                                 found = 1;
1186                                 break;
1187                         }
1188                 }
1189                 if (!found) {
1190                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1191                             c->self);
1192                         return -1;
1193                 }
1194                 buffer_consume(&c->input, nmethods + 2);
1195                 buffer_put_char(&c->output, 0x05);              /* version */
1196                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1197                 FD_SET(c->sock, writeset);
1198                 c->flags |= SSH_SOCKS5_AUTHDONE;
1199                 debug2("channel %d: socks5 auth done", c->self);
1200                 return 0;                               /* need more */
1201         }
1202         debug2("channel %d: socks5 post auth", c->self);
1203         if (have < sizeof(s5_req)+1)
1204                 return 0;                       /* need more */
1205         memcpy(&s5_req, p, sizeof(s5_req));
1206         if (s5_req.version != 0x05 ||
1207             s5_req.command != SSH_SOCKS5_CONNECT ||
1208             s5_req.reserved != 0x00) {
1209                 debug2("channel %d: only socks5 connect supported", c->self);
1210                 return -1;
1211         }
1212         switch (s5_req.atyp){
1213         case SSH_SOCKS5_IPV4:
1214                 addrlen = 4;
1215                 af = AF_INET;
1216                 break;
1217         case SSH_SOCKS5_DOMAIN:
1218                 addrlen = p[sizeof(s5_req)];
1219                 af = -1;
1220                 break;
1221         case SSH_SOCKS5_IPV6:
1222                 addrlen = 16;
1223                 af = AF_INET6;
1224                 break;
1225         default:
1226                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1227                 return -1;
1228         }
1229         need = sizeof(s5_req) + addrlen + 2;
1230         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1231                 need++;
1232         if (have < need)
1233                 return 0;
1234         buffer_consume(&c->input, sizeof(s5_req));
1235         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1236                 buffer_consume(&c->input, 1);    /* host string length */
1237         buffer_get(&c->input, &dest_addr, addrlen);
1238         buffer_get(&c->input, (char *)&dest_port, 2);
1239         dest_addr[addrlen] = '\0';
1240         free(c->path);
1241         c->path = NULL;
1242         if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
1243                 if (addrlen >= NI_MAXHOST) {
1244                         error("channel %d: dynamic request: socks5 hostname "
1245                             "\"%.100s\" too long", c->self, dest_addr);
1246                         return -1;
1247                 }
1248                 c->path = xstrdup(dest_addr);
1249         } else {
1250                 if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
1251                         return -1;
1252                 c->path = xstrdup(ntop);
1253         }
1254         c->host_port = ntohs(dest_port);
1255
1256         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1257             c->self, c->path, c->host_port, s5_req.command);
1258
1259         s5_rsp.version = 0x05;
1260         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1261         s5_rsp.reserved = 0;                    /* ignored */
1262         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1263         dest_port = 0;                          /* ignored */
1264
1265         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1266         buffer_put_int(&c->output, ntohl(INADDR_ANY)); /* bind address */
1267         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1268         return 1;
1269 }
1270
1271 Channel *
1272 channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
1273     int in, int out)
1274 {
1275         Channel *c;
1276
1277         debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
1278             port_to_connect);
1279
1280         c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
1281             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
1282             0, "stdio-forward", /*nonblock*/0);
1283
1284         c->path = xstrdup(host_to_connect);
1285         c->host_port = port_to_connect;
1286         c->listening_port = 0;
1287         c->force_drain = 1;
1288
1289         channel_register_fds(c, in, out, -1, 0, 1, 0);
1290         port_open_helper(c, "direct-tcpip");
1291
1292         return c;
1293 }
1294
1295 /* dynamic port forwarding */
1296 static void
1297 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1298 {
1299         u_char *p;
1300         u_int have;
1301         int ret;
1302
1303         have = buffer_len(&c->input);
1304         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1305         /* buffer_dump(&c->input); */
1306         /* check if the fixed size part of the packet is in buffer. */
1307         if (have < 3) {
1308                 /* need more */
1309                 FD_SET(c->sock, readset);
1310                 return;
1311         }
1312         /* try to guess the protocol */
1313         p = buffer_ptr(&c->input);
1314         switch (p[0]) {
1315         case 0x04:
1316                 ret = channel_decode_socks4(c, readset, writeset);
1317                 break;
1318         case 0x05:
1319                 ret = channel_decode_socks5(c, readset, writeset);
1320                 break;
1321         default:
1322                 ret = -1;
1323                 break;
1324         }
1325         if (ret < 0) {
1326                 chan_mark_dead(c);
1327         } else if (ret == 0) {
1328                 debug2("channel %d: pre_dynamic: need more", c->self);
1329                 /* need more */
1330                 FD_SET(c->sock, readset);
1331         } else {
1332                 /* switch to the next state */
1333                 c->type = SSH_CHANNEL_OPENING;
1334                 port_open_helper(c, "direct-tcpip");
1335         }
1336 }
1337
1338 /* This is our fake X11 server socket. */
1339 /* ARGSUSED */
1340 static void
1341 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1342 {
1343         Channel *nc;
1344         struct sockaddr_storage addr;
1345         int newsock, oerrno;
1346         socklen_t addrlen;
1347         char buf[16384], *remote_ipaddr;
1348         int remote_port;
1349
1350         if (FD_ISSET(c->sock, readset)) {
1351                 debug("X11 connection requested.");
1352                 addrlen = sizeof(addr);
1353                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1354                 if (c->single_connection) {
1355                         oerrno = errno;
1356                         debug2("single_connection: closing X11 listener.");
1357                         channel_close_fd(&c->sock);
1358                         chan_mark_dead(c);
1359                         errno = oerrno;
1360                 }
1361                 if (newsock < 0) {
1362                         if (errno != EINTR && errno != EWOULDBLOCK &&
1363                             errno != ECONNABORTED)
1364                                 error("accept: %.100s", strerror(errno));
1365                         if (errno == EMFILE || errno == ENFILE)
1366                                 c->notbefore = monotime() + 1;
1367                         return;
1368                 }
1369                 set_nodelay(newsock);
1370                 remote_ipaddr = get_peer_ipaddr(newsock);
1371                 remote_port = get_peer_port(newsock);
1372                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1373                     remote_ipaddr, remote_port);
1374
1375                 nc = channel_new("accepted x11 socket",
1376                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1377                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1378                 if (compat20) {
1379                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1380                         packet_put_cstring("x11");
1381                         packet_put_int(nc->self);
1382                         packet_put_int(nc->local_window_max);
1383                         packet_put_int(nc->local_maxpacket);
1384                         /* originator ipaddr and port */
1385                         packet_put_cstring(remote_ipaddr);
1386                         if (datafellows & SSH_BUG_X11FWD) {
1387                                 debug2("ssh2 x11 bug compat mode");
1388                         } else {
1389                                 packet_put_int(remote_port);
1390                         }
1391                         packet_send();
1392                 } else {
1393                         packet_start(SSH_SMSG_X11_OPEN);
1394                         packet_put_int(nc->self);
1395                         if (packet_get_protocol_flags() &
1396                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1397                                 packet_put_cstring(buf);
1398                         packet_send();
1399                 }
1400                 free(remote_ipaddr);
1401         }
1402 }
1403
1404 static void
1405 port_open_helper(Channel *c, char *rtype)
1406 {
1407         char buf[1024];
1408         char *local_ipaddr = get_local_ipaddr(c->sock);
1409         int local_port = c->sock == -1 ? 65536 : get_sock_port(c->sock, 1);
1410         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1411         int remote_port = get_peer_port(c->sock);
1412
1413         if (remote_port == -1) {
1414                 /* Fake addr/port to appease peers that validate it (Tectia) */
1415                 free(remote_ipaddr);
1416                 remote_ipaddr = xstrdup("127.0.0.1");
1417                 remote_port = 65535;
1418         }
1419
1420         snprintf(buf, sizeof buf,
1421             "%s: listening port %d for %.100s port %d, "
1422             "connect from %.200s port %d to %.100s port %d",
1423             rtype, c->listening_port, c->path, c->host_port,
1424             remote_ipaddr, remote_port, local_ipaddr, local_port);
1425
1426         free(c->remote_name);
1427         c->remote_name = xstrdup(buf);
1428
1429         if (compat20) {
1430                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1431                 packet_put_cstring(rtype);
1432                 packet_put_int(c->self);
1433                 packet_put_int(c->local_window_max);
1434                 packet_put_int(c->local_maxpacket);
1435                 if (strcmp(rtype, "direct-tcpip") == 0) {
1436                         /* target host, port */
1437                         packet_put_cstring(c->path);
1438                         packet_put_int(c->host_port);
1439                 } else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) {
1440                         /* target path */
1441                         packet_put_cstring(c->path);
1442                 } else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
1443                         /* listen path */
1444                         packet_put_cstring(c->path);
1445                 } else {
1446                         /* listen address, port */
1447                         packet_put_cstring(c->path);
1448                         packet_put_int(local_port);
1449                 }
1450                 if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
1451                         /* reserved for future owner/mode info */
1452                         packet_put_cstring("");
1453                 } else {
1454                         /* originator host and port */
1455                         packet_put_cstring(remote_ipaddr);
1456                         packet_put_int((u_int)remote_port);
1457                 }
1458                 packet_send();
1459         } else {
1460                 packet_start(SSH_MSG_PORT_OPEN);
1461                 packet_put_int(c->self);
1462                 packet_put_cstring(c->path);
1463                 packet_put_int(c->host_port);
1464                 if (packet_get_protocol_flags() &
1465                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1466                         packet_put_cstring(c->remote_name);
1467                 packet_send();
1468         }
1469         free(remote_ipaddr);
1470         free(local_ipaddr);
1471 }
1472
1473 static void
1474 channel_set_reuseaddr(int fd)
1475 {
1476         int on = 1;
1477
1478         /*
1479          * Set socket options.
1480          * Allow local port reuse in TIME_WAIT.
1481          */
1482         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1483                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1484 }
1485
1486 /*
1487  * This socket is listening for connections to a forwarded TCP/IP port.
1488  */
1489 /* ARGSUSED */
1490 static void
1491 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1492 {
1493         Channel *nc;
1494         struct sockaddr_storage addr;
1495         int newsock, nextstate;
1496         socklen_t addrlen;
1497         char *rtype;
1498
1499         if (FD_ISSET(c->sock, readset)) {
1500                 debug("Connection to port %d forwarding "
1501                     "to %.100s port %d requested.",
1502                     c->listening_port, c->path, c->host_port);
1503
1504                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1505                         nextstate = SSH_CHANNEL_OPENING;
1506                         rtype = "forwarded-tcpip";
1507                 } else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) {
1508                         nextstate = SSH_CHANNEL_OPENING;
1509                         rtype = "forwarded-streamlocal@openssh.com";
1510                 } else if (c->host_port == PORT_STREAMLOCAL) {
1511                         nextstate = SSH_CHANNEL_OPENING;
1512                         rtype = "direct-streamlocal@openssh.com";
1513                 } else if (c->host_port == 0) {
1514                         nextstate = SSH_CHANNEL_DYNAMIC;
1515                         rtype = "dynamic-tcpip";
1516                 } else {
1517                         nextstate = SSH_CHANNEL_OPENING;
1518                         rtype = "direct-tcpip";
1519                 }
1520
1521                 addrlen = sizeof(addr);
1522                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1523                 if (newsock < 0) {
1524                         if (errno != EINTR && errno != EWOULDBLOCK &&
1525                             errno != ECONNABORTED)
1526                                 error("accept: %.100s", strerror(errno));
1527                         if (errno == EMFILE || errno == ENFILE)
1528                                 c->notbefore = monotime() + 1;
1529                         return;
1530                 }
1531                 if (c->host_port != PORT_STREAMLOCAL)
1532                         set_nodelay(newsock);
1533                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1534                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1535                 nc->listening_port = c->listening_port;
1536                 nc->host_port = c->host_port;
1537                 if (c->path != NULL)
1538                         nc->path = xstrdup(c->path);
1539
1540                 if (nextstate != SSH_CHANNEL_DYNAMIC)
1541                         port_open_helper(nc, rtype);
1542         }
1543 }
1544
1545 /*
1546  * This is the authentication agent socket listening for connections from
1547  * clients.
1548  */
1549 /* ARGSUSED */
1550 static void
1551 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1552 {
1553         Channel *nc;
1554         int newsock;
1555         struct sockaddr_storage addr;
1556         socklen_t addrlen;
1557
1558         if (FD_ISSET(c->sock, readset)) {
1559                 addrlen = sizeof(addr);
1560                 newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
1561                 if (newsock < 0) {
1562                         error("accept from auth socket: %.100s",
1563                             strerror(errno));
1564                         if (errno == EMFILE || errno == ENFILE)
1565                                 c->notbefore = monotime() + 1;
1566                         return;
1567                 }
1568                 nc = channel_new("accepted auth socket",
1569                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1570                     c->local_window_max, c->local_maxpacket,
1571                     0, "accepted auth socket", 1);
1572                 if (compat20) {
1573                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1574                         packet_put_cstring("auth-agent@openssh.com");
1575                         packet_put_int(nc->self);
1576                         packet_put_int(c->local_window_max);
1577                         packet_put_int(c->local_maxpacket);
1578                 } else {
1579                         packet_start(SSH_SMSG_AGENT_OPEN);
1580                         packet_put_int(nc->self);
1581                 }
1582                 packet_send();
1583         }
1584 }
1585
1586 /* ARGSUSED */
1587 static void
1588 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1589 {
1590         int err = 0, sock;
1591         socklen_t sz = sizeof(err);
1592
1593         if (FD_ISSET(c->sock, writeset)) {
1594                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1595                         err = errno;
1596                         error("getsockopt SO_ERROR failed");
1597                 }
1598                 if (err == 0) {
1599                         debug("channel %d: connected to %s port %d",
1600                             c->self, c->connect_ctx.host, c->connect_ctx.port);
1601                         channel_connect_ctx_free(&c->connect_ctx);
1602                         c->type = SSH_CHANNEL_OPEN;
1603                         if (compat20) {
1604                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1605                                 packet_put_int(c->remote_id);
1606                                 packet_put_int(c->self);
1607                                 packet_put_int(c->local_window);
1608                                 packet_put_int(c->local_maxpacket);
1609                         } else {
1610                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1611                                 packet_put_int(c->remote_id);
1612                                 packet_put_int(c->self);
1613                         }
1614                 } else {
1615                         debug("channel %d: connection failed: %s",
1616                             c->self, strerror(err));
1617                         /* Try next address, if any */
1618                         if ((sock = connect_next(&c->connect_ctx)) > 0) {
1619                                 close(c->sock);
1620                                 c->sock = c->rfd = c->wfd = sock;
1621                                 channel_max_fd = channel_find_maxfd();
1622                                 return;
1623                         }
1624                         /* Exhausted all addresses */
1625                         error("connect_to %.100s port %d: failed.",
1626                             c->connect_ctx.host, c->connect_ctx.port);
1627                         channel_connect_ctx_free(&c->connect_ctx);
1628                         if (compat20) {
1629                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1630                                 packet_put_int(c->remote_id);
1631                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1632                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1633                                         packet_put_cstring(strerror(err));
1634                                         packet_put_cstring("");
1635                                 }
1636                         } else {
1637                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1638                                 packet_put_int(c->remote_id);
1639                         }
1640                         chan_mark_dead(c);
1641                 }
1642                 packet_send();
1643         }
1644 }
1645
1646 /* ARGSUSED */
1647 static int
1648 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1649 {
1650         char buf[CHAN_RBUF];
1651         int len, force;
1652
1653         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
1654         if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
1655                 errno = 0;
1656                 len = read(c->rfd, buf, sizeof(buf));
1657                 if (len < 0 && (errno == EINTR ||
1658                     ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
1659                         return 1;
1660 #ifndef PTY_ZEROREAD
1661                 if (len <= 0) {
1662 #else
1663                 if ((!c->isatty && len <= 0) ||
1664                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1665 #endif
1666                         debug2("channel %d: read<=0 rfd %d len %d",
1667                             c->self, c->rfd, len);
1668                         if (c->type != SSH_CHANNEL_OPEN) {
1669                                 debug2("channel %d: not open", c->self);
1670                                 chan_mark_dead(c);
1671                                 return -1;
1672                         } else if (compat13) {
1673                                 buffer_clear(&c->output);
1674                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1675                                 debug2("channel %d: input draining.", c->self);
1676                         } else {
1677                                 chan_read_failed(c);
1678                         }
1679                         return -1;
1680                 }
1681                 if (c->input_filter != NULL) {
1682                         if (c->input_filter(c, buf, len) == -1) {
1683                                 debug2("channel %d: filter stops", c->self);
1684                                 chan_read_failed(c);
1685                         }
1686                 } else if (c->datagram) {
1687                         buffer_put_string(&c->input, buf, len);
1688                 } else {
1689                         buffer_append(&c->input, buf, len);
1690                 }
1691         }
1692         return 1;
1693 }
1694
1695 /* ARGSUSED */
1696 static int
1697 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1698 {
1699         struct termios tio;
1700         u_char *data = NULL, *buf;
1701         u_int dlen, olen = 0;
1702         int len;
1703
1704         /* Send buffered output data to the socket. */
1705         if (c->wfd != -1 &&
1706             FD_ISSET(c->wfd, writeset) &&
1707             buffer_len(&c->output) > 0) {
1708                 olen = buffer_len(&c->output);
1709                 if (c->output_filter != NULL) {
1710                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1711                                 debug2("channel %d: filter stops", c->self);
1712                                 if (c->type != SSH_CHANNEL_OPEN)
1713                                         chan_mark_dead(c);
1714                                 else
1715                                         chan_write_failed(c);
1716                                 return -1;
1717                         }
1718                 } else if (c->datagram) {
1719                         buf = data = buffer_get_string(&c->output, &dlen);
1720                 } else {
1721                         buf = data = buffer_ptr(&c->output);
1722                         dlen = buffer_len(&c->output);
1723                 }
1724
1725                 if (c->datagram) {
1726                         /* ignore truncated writes, datagrams might get lost */
1727                         len = write(c->wfd, buf, dlen);
1728                         free(data);
1729                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1730                             errno == EWOULDBLOCK))
1731                                 return 1;
1732                         if (len <= 0) {
1733                                 if (c->type != SSH_CHANNEL_OPEN)
1734                                         chan_mark_dead(c);
1735                                 else
1736                                         chan_write_failed(c);
1737                                 return -1;
1738                         }
1739                         goto out;
1740                 }
1741 #ifdef _AIX
1742                 /* XXX: Later AIX versions can't push as much data to tty */
1743                 if (compat20 && c->wfd_isatty)
1744                         dlen = MIN(dlen, 8*1024);
1745 #endif
1746
1747                 len = write(c->wfd, buf, dlen);
1748                 if (len < 0 &&
1749                     (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
1750                         return 1;
1751                 if (len <= 0) {
1752                         if (c->type != SSH_CHANNEL_OPEN) {
1753                                 debug2("channel %d: not open", c->self);
1754                                 chan_mark_dead(c);
1755                                 return -1;
1756                         } else if (compat13) {
1757                                 buffer_clear(&c->output);
1758                                 debug2("channel %d: input draining.", c->self);
1759                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1760                         } else {
1761                                 chan_write_failed(c);
1762                         }
1763                         return -1;
1764                 }
1765 #ifndef BROKEN_TCGETATTR_ICANON
1766                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1767                         if (tcgetattr(c->wfd, &tio) == 0 &&
1768                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1769                                 /*
1770                                  * Simulate echo to reduce the impact of
1771                                  * traffic analysis. We need to match the
1772                                  * size of a SSH2_MSG_CHANNEL_DATA message
1773                                  * (4 byte channel id + buf)
1774                                  */
1775                                 packet_send_ignore(4 + len);
1776                                 packet_send();
1777                         }
1778                 }
1779 #endif
1780                 buffer_consume(&c->output, len);
1781         }
1782  out:
1783         if (compat20 && olen > 0)
1784                 c->local_consumed += olen - buffer_len(&c->output);
1785         return 1;
1786 }
1787
1788 static int
1789 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1790 {
1791         char buf[CHAN_RBUF];
1792         int len;
1793
1794 /** XXX handle drain efd, too */
1795         if (c->efd != -1) {
1796                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1797                     FD_ISSET(c->efd, writeset) &&
1798                     buffer_len(&c->extended) > 0) {
1799                         len = write(c->efd, buffer_ptr(&c->extended),
1800                             buffer_len(&c->extended));
1801                         debug2("channel %d: written %d to efd %d",
1802                             c->self, len, c->efd);
1803                         if (len < 0 && (errno == EINTR || errno == EAGAIN ||
1804                             errno == EWOULDBLOCK))
1805                                 return 1;
1806                         if (len <= 0) {
1807                                 debug2("channel %d: closing write-efd %d",
1808                                     c->self, c->efd);
1809                                 channel_close_fd(&c->efd);
1810                         } else {
1811                                 buffer_consume(&c->extended, len);
1812                                 c->local_consumed += len;
1813                         }
1814                 } else if (c->efd != -1 &&
1815                     (c->extended_usage == CHAN_EXTENDED_READ ||
1816                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
1817                     (c->detach_close || FD_ISSET(c->efd, readset))) {
1818                         len = read(c->efd, buf, sizeof(buf));
1819                         debug2("channel %d: read %d from efd %d",
1820                             c->self, len, c->efd);
1821                         if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
1822                             errno == EWOULDBLOCK) && !c->detach_close)))
1823                                 return 1;
1824                         if (len <= 0) {
1825                                 debug2("channel %d: closing read-efd %d",
1826                                     c->self, c->efd);
1827                                 channel_close_fd(&c->efd);
1828                         } else {
1829                                 if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
1830                                         debug3("channel %d: discard efd",
1831                                             c->self);
1832                                 } else
1833                                         buffer_append(&c->extended, buf, len);
1834                         }
1835                 }
1836         }
1837         return 1;
1838 }
1839
1840 static int
1841 channel_check_window(Channel *c)
1842 {
1843         if (c->type == SSH_CHANNEL_OPEN &&
1844             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1845             ((c->local_window_max - c->local_window >
1846             c->local_maxpacket*3) ||
1847             c->local_window < c->local_window_max/2) &&
1848             c->local_consumed > 0) {
1849                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1850                 packet_put_int(c->remote_id);
1851                 packet_put_int(c->local_consumed);
1852                 packet_send();
1853                 debug2("channel %d: window %d sent adjust %d",
1854                     c->self, c->local_window,
1855                     c->local_consumed);
1856                 c->local_window += c->local_consumed;
1857                 c->local_consumed = 0;
1858         }
1859         return 1;
1860 }
1861
1862 static void
1863 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1864 {
1865         channel_handle_rfd(c, readset, writeset);
1866         channel_handle_wfd(c, readset, writeset);
1867         if (!compat20)
1868                 return;
1869         channel_handle_efd(c, readset, writeset);
1870         channel_check_window(c);
1871 }
1872
1873 static u_int
1874 read_mux(Channel *c, u_int need)
1875 {
1876         char buf[CHAN_RBUF];
1877         int len;
1878         u_int rlen;
1879
1880         if (buffer_len(&c->input) < need) {
1881                 rlen = need - buffer_len(&c->input);
1882                 len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
1883                 if (len <= 0) {
1884                         if (errno != EINTR && errno != EAGAIN) {
1885                                 debug2("channel %d: ctl read<=0 rfd %d len %d",
1886                                     c->self, c->rfd, len);
1887                                 chan_read_failed(c);
1888                                 return 0;
1889                         }
1890                 } else
1891                         buffer_append(&c->input, buf, len);
1892         }
1893         return buffer_len(&c->input);
1894 }
1895
1896 static void
1897 channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
1898 {
1899         u_int need;
1900         ssize_t len;
1901
1902         if (!compat20)
1903                 fatal("%s: entered with !compat20", __func__);
1904
1905         if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
1906             (c->istate == CHAN_INPUT_OPEN ||
1907             c->istate == CHAN_INPUT_WAIT_DRAIN)) {
1908                 /*
1909                  * Don't not read past the precise end of packets to
1910                  * avoid disrupting fd passing.
1911                  */
1912                 if (read_mux(c, 4) < 4) /* read header */
1913                         return;
1914                 need = get_u32(buffer_ptr(&c->input));
1915 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
1916                 if (need > CHANNEL_MUX_MAX_PACKET) {
1917                         debug2("channel %d: packet too big %u > %u",
1918                             c->self, CHANNEL_MUX_MAX_PACKET, need);
1919                         chan_rcvd_oclose(c);
1920                         return;
1921                 }
1922                 if (read_mux(c, need + 4) < need + 4) /* read body */
1923                         return;
1924                 if (c->mux_rcb(c) != 0) {
1925                         debug("channel %d: mux_rcb failed", c->self);
1926                         chan_mark_dead(c);
1927                         return;
1928                 }
1929         }
1930
1931         if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
1932             buffer_len(&c->output) > 0) {
1933                 len = write(c->wfd, buffer_ptr(&c->output),
1934                     buffer_len(&c->output));
1935                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1936                         return;
1937                 if (len <= 0) {
1938                         chan_mark_dead(c);
1939                         return;
1940                 }
1941                 buffer_consume(&c->output, len);
1942         }
1943 }
1944
1945 static void
1946 channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
1947 {
1948         Channel *nc;
1949         struct sockaddr_storage addr;
1950         socklen_t addrlen;
1951         int newsock;
1952         uid_t euid;
1953         gid_t egid;
1954
1955         if (!FD_ISSET(c->sock, readset))
1956                 return;
1957
1958         debug("multiplexing control connection");
1959
1960         /*
1961          * Accept connection on control socket
1962          */
1963         memset(&addr, 0, sizeof(addr));
1964         addrlen = sizeof(addr);
1965         if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
1966             &addrlen)) == -1) {
1967                 error("%s accept: %s", __func__, strerror(errno));
1968                 if (errno == EMFILE || errno == ENFILE)
1969                         c->notbefore = monotime() + 1;
1970                 return;
1971         }
1972
1973         if (getpeereid(newsock, &euid, &egid) < 0) {
1974                 error("%s getpeereid failed: %s", __func__,
1975                     strerror(errno));
1976                 close(newsock);
1977                 return;
1978         }
1979         if ((euid != 0) && (getuid() != euid)) {
1980                 error("multiplex uid mismatch: peer euid %u != uid %u",
1981                     (u_int)euid, (u_int)getuid());
1982                 close(newsock);
1983                 return;
1984         }
1985         nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
1986             newsock, newsock, -1, c->local_window_max,
1987             c->local_maxpacket, 0, "mux-control", 1);
1988         nc->mux_rcb = c->mux_rcb;
1989         debug3("%s: new mux channel %d fd %d", __func__,
1990             nc->self, nc->sock);
1991         /* establish state */
1992         nc->mux_rcb(nc);
1993         /* mux state transitions must not elicit protocol messages */
1994         nc->flags |= CHAN_LOCAL;
1995 }
1996
1997 /* ARGSUSED */
1998 static void
1999 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
2000 {
2001         int len;
2002
2003         /* Send buffered output data to the socket. */
2004         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
2005                 len = write(c->sock, buffer_ptr(&c->output),
2006                             buffer_len(&c->output));
2007                 if (len <= 0)
2008                         buffer_clear(&c->output);
2009                 else
2010                         buffer_consume(&c->output, len);
2011         }
2012 }
2013
2014 static void
2015 channel_handler_init_20(void)
2016 {
2017         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2018         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2019         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2020         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
2021         channel_pre[SSH_CHANNEL_UNIX_LISTENER] =        &channel_pre_listener;
2022         channel_pre[SSH_CHANNEL_RUNIX_LISTENER] =       &channel_pre_listener;
2023         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2024         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2025         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2026         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2027         channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
2028         channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
2029
2030         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2031         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2032         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
2033         channel_post[SSH_CHANNEL_UNIX_LISTENER] =       &channel_post_port_listener;
2034         channel_post[SSH_CHANNEL_RUNIX_LISTENER] =      &channel_post_port_listener;
2035         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2036         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2037         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2038         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2039         channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
2040         channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
2041 }
2042
2043 static void
2044 channel_handler_init_13(void)
2045 {
2046         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
2047         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
2048         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2049         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2050         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2051         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
2052         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
2053         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2054         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2055
2056         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2057         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2058         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2059         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2060         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
2061         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2062         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2063 }
2064
2065 static void
2066 channel_handler_init_15(void)
2067 {
2068         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
2069         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
2070         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
2071         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
2072         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
2073         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
2074         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
2075
2076         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
2077         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
2078         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
2079         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
2080         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
2081         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
2082 }
2083
2084 static void
2085 channel_handler_init(void)
2086 {
2087         int i;
2088
2089         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
2090                 channel_pre[i] = NULL;
2091                 channel_post[i] = NULL;
2092         }
2093         if (compat20)
2094                 channel_handler_init_20();
2095         else if (compat13)
2096                 channel_handler_init_13();
2097         else
2098                 channel_handler_init_15();
2099 }
2100
2101 /* gc dead channels */
2102 static void
2103 channel_garbage_collect(Channel *c)
2104 {
2105         if (c == NULL)
2106                 return;
2107         if (c->detach_user != NULL) {
2108                 if (!chan_is_dead(c, c->detach_close))
2109                         return;
2110                 debug2("channel %d: gc: notify user", c->self);
2111                 c->detach_user(c->self, NULL);
2112                 /* if we still have a callback */
2113                 if (c->detach_user != NULL)
2114                         return;
2115                 debug2("channel %d: gc: user detached", c->self);
2116         }
2117         if (!chan_is_dead(c, 1))
2118                 return;
2119         debug2("channel %d: garbage collecting", c->self);
2120         channel_free(c);
2121 }
2122
2123 static void
2124 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
2125     time_t *unpause_secs)
2126 {
2127         static int did_init = 0;
2128         u_int i, oalloc;
2129         Channel *c;
2130         time_t now;
2131
2132         if (!did_init) {
2133                 channel_handler_init();
2134                 did_init = 1;
2135         }
2136         now = monotime();
2137         if (unpause_secs != NULL)
2138                 *unpause_secs = 0;
2139         for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
2140                 c = channels[i];
2141                 if (c == NULL)
2142                         continue;
2143                 if (c->delayed) {
2144                         if (ftab == channel_pre)
2145                                 c->delayed = 0;
2146                         else
2147                                 continue;
2148                 }
2149                 if (ftab[c->type] != NULL) {
2150                         /*
2151                          * Run handlers that are not paused.
2152                          */
2153                         if (c->notbefore <= now)
2154                                 (*ftab[c->type])(c, readset, writeset);
2155                         else if (unpause_secs != NULL) {
2156                                 /*
2157                                  * Collect the time that the earliest
2158                                  * channel comes off pause.
2159                                  */
2160                                 debug3("%s: chan %d: skip for %d more seconds",
2161                                     __func__, c->self,
2162                                     (int)(c->notbefore - now));
2163                                 if (*unpause_secs == 0 ||
2164                                     (c->notbefore - now) < *unpause_secs)
2165                                         *unpause_secs = c->notbefore - now;
2166                         }
2167                 }
2168                 channel_garbage_collect(c);
2169         }
2170         if (unpause_secs != NULL && *unpause_secs != 0)
2171                 debug3("%s: first channel unpauses in %d seconds",
2172                     __func__, (int)*unpause_secs);
2173 }
2174
2175 /*
2176  * Allocate/update select bitmasks and add any bits relevant to channels in
2177  * select bitmasks.
2178  */
2179 void
2180 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
2181     u_int *nallocp, time_t *minwait_secs, int rekeying)
2182 {
2183         u_int n, sz, nfdset;
2184
2185         n = MAX(*maxfdp, channel_max_fd);
2186
2187         nfdset = howmany(n+1, NFDBITS);
2188         /* Explicitly test here, because xrealloc isn't always called */
2189         if (nfdset && SIZE_MAX / nfdset < sizeof(fd_mask))
2190                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
2191         sz = nfdset * sizeof(fd_mask);
2192
2193         /* perhaps check sz < nalloc/2 and shrink? */
2194         if (*readsetp == NULL || sz > *nallocp) {
2195                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
2196                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
2197                 *nallocp = sz;
2198         }
2199         *maxfdp = n;
2200         memset(*readsetp, 0, sz);
2201         memset(*writesetp, 0, sz);
2202
2203         if (!rekeying)
2204                 channel_handler(channel_pre, *readsetp, *writesetp,
2205                     minwait_secs);
2206 }
2207
2208 /*
2209  * After select, perform any appropriate operations for channels which have
2210  * events pending.
2211  */
2212 void
2213 channel_after_select(fd_set *readset, fd_set *writeset)
2214 {
2215         channel_handler(channel_post, readset, writeset, NULL);
2216 }
2217
2218
2219 /* If there is data to send to the connection, enqueue some of it now. */
2220 void
2221 channel_output_poll(void)
2222 {
2223         Channel *c;
2224         u_int i, len;
2225
2226         for (i = 0; i < channels_alloc; i++) {
2227                 c = channels[i];
2228                 if (c == NULL)
2229                         continue;
2230
2231                 /*
2232                  * We are only interested in channels that can have buffered
2233                  * incoming data.
2234                  */
2235                 if (compat13) {
2236                         if (c->type != SSH_CHANNEL_OPEN &&
2237                             c->type != SSH_CHANNEL_INPUT_DRAINING)
2238                                 continue;
2239                 } else {
2240                         if (c->type != SSH_CHANNEL_OPEN)
2241                                 continue;
2242                 }
2243                 if (compat20 &&
2244                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
2245                         /* XXX is this true? */
2246                         debug3("channel %d: will not send data after close", c->self);
2247                         continue;
2248                 }
2249
2250                 /* Get the amount of buffered data for this channel. */
2251                 if ((c->istate == CHAN_INPUT_OPEN ||
2252                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
2253                     (len = buffer_len(&c->input)) > 0) {
2254                         if (c->datagram) {
2255                                 if (len > 0) {
2256                                         u_char *data;
2257                                         u_int dlen;
2258
2259                                         data = buffer_get_string(&c->input,
2260                                             &dlen);
2261                                         if (dlen > c->remote_window ||
2262                                             dlen > c->remote_maxpacket) {
2263                                                 debug("channel %d: datagram "
2264                                                     "too big for channel",
2265                                                     c->self);
2266                                                 free(data);
2267                                                 continue;
2268                                         }
2269                                         packet_start(SSH2_MSG_CHANNEL_DATA);
2270                                         packet_put_int(c->remote_id);
2271                                         packet_put_string(data, dlen);
2272                                         packet_send();
2273                                         c->remote_window -= dlen + 4;
2274                                         free(data);
2275                                 }
2276                                 continue;
2277                         }
2278                         /*
2279                          * Send some data for the other side over the secure
2280                          * connection.
2281                          */
2282                         if (compat20) {
2283                                 if (len > c->remote_window)
2284                                         len = c->remote_window;
2285                                 if (len > c->remote_maxpacket)
2286                                         len = c->remote_maxpacket;
2287                         } else {
2288                                 if (packet_is_interactive()) {
2289                                         if (len > 1024)
2290                                                 len = 512;
2291                                 } else {
2292                                         /* Keep the packets at reasonable size. */
2293                                         if (len > packet_get_maxsize()/2)
2294                                                 len = packet_get_maxsize()/2;
2295                                 }
2296                         }
2297                         if (len > 0) {
2298                                 packet_start(compat20 ?
2299                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
2300                                 packet_put_int(c->remote_id);
2301                                 packet_put_string(buffer_ptr(&c->input), len);
2302                                 packet_send();
2303                                 buffer_consume(&c->input, len);
2304                                 c->remote_window -= len;
2305                         }
2306                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
2307                         if (compat13)
2308                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
2309                         /*
2310                          * input-buffer is empty and read-socket shutdown:
2311                          * tell peer, that we will not send more data: send IEOF.
2312                          * hack for extended data: delay EOF if EFD still in use.
2313                          */
2314                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
2315                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
2316                                     c->self, c->efd, buffer_len(&c->extended));
2317                         else
2318                                 chan_ibuf_empty(c);
2319                 }
2320                 /* Send extended data, i.e. stderr */
2321                 if (compat20 &&
2322                     !(c->flags & CHAN_EOF_SENT) &&
2323                     c->remote_window > 0 &&
2324                     (len = buffer_len(&c->extended)) > 0 &&
2325                     c->extended_usage == CHAN_EXTENDED_READ) {
2326                         debug2("channel %d: rwin %u elen %u euse %d",
2327                             c->self, c->remote_window, buffer_len(&c->extended),
2328                             c->extended_usage);
2329                         if (len > c->remote_window)
2330                                 len = c->remote_window;
2331                         if (len > c->remote_maxpacket)
2332                                 len = c->remote_maxpacket;
2333                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
2334                         packet_put_int(c->remote_id);
2335                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
2336                         packet_put_string(buffer_ptr(&c->extended), len);
2337                         packet_send();
2338                         buffer_consume(&c->extended, len);
2339                         c->remote_window -= len;
2340                         debug2("channel %d: sent ext data %d", c->self, len);
2341                 }
2342         }
2343 }
2344
2345
2346 /* -- protocol input */
2347
2348 /* ARGSUSED */
2349 int
2350 channel_input_data(int type, u_int32_t seq, void *ctxt)
2351 {
2352         int id;
2353         const u_char *data;
2354         u_int data_len, win_len;
2355         Channel *c;
2356
2357         /* Get the channel number and verify it. */
2358         id = packet_get_int();
2359         c = channel_lookup(id);
2360         if (c == NULL)
2361                 packet_disconnect("Received data for nonexistent channel %d.", id);
2362
2363         /* Ignore any data for non-open channels (might happen on close) */
2364         if (c->type != SSH_CHANNEL_OPEN &&
2365             c->type != SSH_CHANNEL_X11_OPEN)
2366                 return 0;
2367
2368         /* Get the data. */
2369         data = packet_get_string_ptr(&data_len);
2370         win_len = data_len;
2371         if (c->datagram)
2372                 win_len += 4;  /* string length header */
2373
2374         /*
2375          * Ignore data for protocol > 1.3 if output end is no longer open.
2376          * For protocol 2 the sending side is reducing its window as it sends
2377          * data, so we must 'fake' consumption of the data in order to ensure
2378          * that window updates are sent back.  Otherwise the connection might
2379          * deadlock.
2380          */
2381         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2382                 if (compat20) {
2383                         c->local_window -= win_len;
2384                         c->local_consumed += win_len;
2385                 }
2386                 return 0;
2387         }
2388
2389         if (compat20) {
2390                 if (win_len > c->local_maxpacket) {
2391                         logit("channel %d: rcvd big packet %d, maxpack %d",
2392                             c->self, win_len, c->local_maxpacket);
2393                 }
2394                 if (win_len > c->local_window) {
2395                         logit("channel %d: rcvd too much data %d, win %d",
2396                             c->self, win_len, c->local_window);
2397                         return 0;
2398                 }
2399                 c->local_window -= win_len;
2400         }
2401         if (c->datagram)
2402                 buffer_put_string(&c->output, data, data_len);
2403         else
2404                 buffer_append(&c->output, data, data_len);
2405         packet_check_eom();
2406         return 0;
2407 }
2408
2409 /* ARGSUSED */
2410 int
2411 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2412 {
2413         int id;
2414         char *data;
2415         u_int data_len, tcode;
2416         Channel *c;
2417
2418         /* Get the channel number and verify it. */
2419         id = packet_get_int();
2420         c = channel_lookup(id);
2421
2422         if (c == NULL)
2423                 packet_disconnect("Received extended_data for bad channel %d.", id);
2424         if (c->type != SSH_CHANNEL_OPEN) {
2425                 logit("channel %d: ext data for non open", id);
2426                 return 0;
2427         }
2428         if (c->flags & CHAN_EOF_RCVD) {
2429                 if (datafellows & SSH_BUG_EXTEOF)
2430                         debug("channel %d: accepting ext data after eof", id);
2431                 else
2432                         packet_disconnect("Received extended_data after EOF "
2433                             "on channel %d.", id);
2434         }
2435         tcode = packet_get_int();
2436         if (c->efd == -1 ||
2437             c->extended_usage != CHAN_EXTENDED_WRITE ||
2438             tcode != SSH2_EXTENDED_DATA_STDERR) {
2439                 logit("channel %d: bad ext data", c->self);
2440                 return 0;
2441         }
2442         data = packet_get_string(&data_len);
2443         packet_check_eom();
2444         if (data_len > c->local_window) {
2445                 logit("channel %d: rcvd too much extended_data %d, win %d",
2446                     c->self, data_len, c->local_window);
2447                 free(data);
2448                 return 0;
2449         }
2450         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2451         c->local_window -= data_len;
2452         buffer_append(&c->extended, data, data_len);
2453         free(data);
2454         return 0;
2455 }
2456
2457 /* ARGSUSED */
2458 int
2459 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2460 {
2461         int id;
2462         Channel *c;
2463
2464         id = packet_get_int();
2465         packet_check_eom();
2466         c = channel_lookup(id);
2467         if (c == NULL)
2468                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2469         chan_rcvd_ieof(c);
2470
2471         /* XXX force input close */
2472         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2473                 debug("channel %d: FORCE input drain", c->self);
2474                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2475                 if (buffer_len(&c->input) == 0)
2476                         chan_ibuf_empty(c);
2477         }
2478         return 0;
2479 }
2480
2481 /* ARGSUSED */
2482 int
2483 channel_input_close(int type, u_int32_t seq, void *ctxt)
2484 {
2485         int id;
2486         Channel *c;
2487
2488         id = packet_get_int();
2489         packet_check_eom();
2490         c = channel_lookup(id);
2491         if (c == NULL)
2492                 packet_disconnect("Received close for nonexistent channel %d.", id);
2493
2494         /*
2495          * Send a confirmation that we have closed the channel and no more
2496          * data is coming for it.
2497          */
2498         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2499         packet_put_int(c->remote_id);
2500         packet_send();
2501
2502         /*
2503          * If the channel is in closed state, we have sent a close request,
2504          * and the other side will eventually respond with a confirmation.
2505          * Thus, we cannot free the channel here, because then there would be
2506          * no-one to receive the confirmation.  The channel gets freed when
2507          * the confirmation arrives.
2508          */
2509         if (c->type != SSH_CHANNEL_CLOSED) {
2510                 /*
2511                  * Not a closed channel - mark it as draining, which will
2512                  * cause it to be freed later.
2513                  */
2514                 buffer_clear(&c->input);
2515                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2516         }
2517         return 0;
2518 }
2519
2520 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2521 /* ARGSUSED */
2522 int
2523 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2524 {
2525         int id = packet_get_int();
2526         Channel *c = channel_lookup(id);
2527
2528         packet_check_eom();
2529         if (c == NULL)
2530                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2531         chan_rcvd_oclose(c);
2532         return 0;
2533 }
2534
2535 /* ARGSUSED */
2536 int
2537 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2538 {
2539         int id = packet_get_int();
2540         Channel *c = channel_lookup(id);
2541
2542         packet_check_eom();
2543         if (c == NULL)
2544                 packet_disconnect("Received close confirmation for "
2545                     "out-of-range channel %d.", id);
2546         if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
2547                 packet_disconnect("Received close confirmation for "
2548                     "non-closed channel %d (type %d).", id, c->type);
2549         channel_free(c);
2550         return 0;
2551 }
2552
2553 /* ARGSUSED */
2554 int
2555 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2556 {
2557         int id, remote_id;
2558         Channel *c;
2559
2560         id = packet_get_int();
2561         c = channel_lookup(id);
2562
2563         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2564                 packet_disconnect("Received open confirmation for "
2565                     "non-opening channel %d.", id);
2566         remote_id = packet_get_int();
2567         /* Record the remote channel number and mark that the channel is now open. */
2568         c->remote_id = remote_id;
2569         c->type = SSH_CHANNEL_OPEN;
2570
2571         if (compat20) {
2572                 c->remote_window = packet_get_int();
2573                 c->remote_maxpacket = packet_get_int();
2574                 if (c->open_confirm) {
2575                         debug2("callback start");
2576                         c->open_confirm(c->self, 1, c->open_confirm_ctx);
2577                         debug2("callback done");
2578                 }
2579                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2580                     c->remote_window, c->remote_maxpacket);
2581         }
2582         packet_check_eom();
2583         return 0;
2584 }
2585
2586 static char *
2587 reason2txt(int reason)
2588 {
2589         switch (reason) {
2590         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2591                 return "administratively prohibited";
2592         case SSH2_OPEN_CONNECT_FAILED:
2593                 return "connect failed";
2594         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2595                 return "unknown channel type";
2596         case SSH2_OPEN_RESOURCE_SHORTAGE:
2597                 return "resource shortage";
2598         }
2599         return "unknown reason";
2600 }
2601
2602 /* ARGSUSED */
2603 int
2604 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2605 {
2606         int id, reason;
2607         char *msg = NULL, *lang = NULL;
2608         Channel *c;
2609
2610         id = packet_get_int();
2611         c = channel_lookup(id);
2612
2613         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2614                 packet_disconnect("Received open failure for "
2615                     "non-opening channel %d.", id);
2616         if (compat20) {
2617                 reason = packet_get_int();
2618                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2619                         msg  = packet_get_string(NULL);
2620                         lang = packet_get_string(NULL);
2621                 }
2622                 logit("channel %d: open failed: %s%s%s", id,
2623                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2624                 free(msg);
2625                 free(lang);
2626                 if (c->open_confirm) {
2627                         debug2("callback start");
2628                         c->open_confirm(c->self, 0, c->open_confirm_ctx);
2629                         debug2("callback done");
2630                 }
2631         }
2632         packet_check_eom();
2633         /* Schedule the channel for cleanup/deletion. */
2634         chan_mark_dead(c);
2635         return 0;
2636 }
2637
2638 /* ARGSUSED */
2639 int
2640 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2641 {
2642         Channel *c;
2643         int id;
2644         u_int adjust;
2645
2646         if (!compat20)
2647                 return 0;
2648
2649         /* Get the channel number and verify it. */
2650         id = packet_get_int();
2651         c = channel_lookup(id);
2652
2653         if (c == NULL) {
2654                 logit("Received window adjust for non-open channel %d.", id);
2655                 return 0;
2656         }
2657         adjust = packet_get_int();
2658         packet_check_eom();
2659         debug2("channel %d: rcvd adjust %u", id, adjust);
2660         c->remote_window += adjust;
2661         return 0;
2662 }
2663
2664 /* ARGSUSED */
2665 int
2666 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2667 {
2668         Channel *c = NULL;
2669         u_short host_port;
2670         char *host, *originator_string;
2671         int remote_id;
2672
2673         remote_id = packet_get_int();
2674         host = packet_get_string(NULL);
2675         host_port = packet_get_int();
2676
2677         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2678                 originator_string = packet_get_string(NULL);
2679         } else {
2680                 originator_string = xstrdup("unknown (remote did not supply name)");
2681         }
2682         packet_check_eom();
2683         c = channel_connect_to_port(host, host_port,
2684             "connected socket", originator_string);
2685         free(originator_string);
2686         free(host);
2687         if (c == NULL) {
2688                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2689                 packet_put_int(remote_id);
2690                 packet_send();
2691         } else
2692                 c->remote_id = remote_id;
2693         return 0;
2694 }
2695
2696 /* ARGSUSED */
2697 int
2698 channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
2699 {
2700         Channel *c;
2701         struct channel_confirm *cc;
2702         int id;
2703
2704         /* Reset keepalive timeout */
2705         packet_set_alive_timeouts(0);
2706
2707         id = packet_get_int();
2708         packet_check_eom();
2709
2710         debug2("channel_input_status_confirm: type %d id %d", type, id);
2711
2712         if ((c = channel_lookup(id)) == NULL) {
2713                 logit("channel_input_status_confirm: %d: unknown", id);
2714                 return 0;
2715         }
2716         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
2717                 return 0;
2718         cc->cb(type, c, cc->ctx);
2719         TAILQ_REMOVE(&c->status_confirms, cc, entry);
2720         explicit_bzero(cc, sizeof(*cc));
2721         free(cc);
2722         return 0;
2723 }
2724
2725 /* -- tcp forwarding */
2726
2727 void
2728 channel_set_af(int af)
2729 {
2730         IPv4or6 = af;
2731 }
2732
2733
2734 /*
2735  * Determine whether or not a port forward listens to loopback, the
2736  * specified address or wildcard. On the client, a specified bind
2737  * address will always override gateway_ports. On the server, a
2738  * gateway_ports of 1 (``yes'') will override the client's specification
2739  * and force a wildcard bind, whereas a value of 2 (``clientspecified'')
2740  * will bind to whatever address the client asked for.
2741  *
2742  * Special-case listen_addrs are:
2743  *
2744  * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2745  * "" (empty string), "*"  -> wildcard v4/v6
2746  * "localhost"             -> loopback v4/v6
2747  * "127.0.0.1" / "::1"     -> accepted even if gateway_ports isn't set
2748  */
2749 static const char *
2750 channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
2751     int is_client, struct ForwardOptions *fwd_opts)
2752 {
2753         const char *addr = NULL;
2754         int wildcard = 0;
2755
2756         if (listen_addr == NULL) {
2757                 /* No address specified: default to gateway_ports setting */
2758                 if (fwd_opts->gateway_ports)
2759                         wildcard = 1;
2760         } else if (fwd_opts->gateway_ports || is_client) {
2761                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2762                     strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
2763                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2764                     (!is_client && fwd_opts->gateway_ports == 1)) {
2765                         wildcard = 1;
2766                         /*
2767                          * Notify client if they requested a specific listen
2768                          * address and it was overridden.
2769                          */
2770                         if (*listen_addr != '\0' &&
2771                             strcmp(listen_addr, "0.0.0.0") != 0 &&
2772                             strcmp(listen_addr, "*") != 0) {
2773                                 packet_send_debug("Forwarding listen address "
2774                                     "\"%s\" overridden by server "
2775                                     "GatewayPorts", listen_addr);
2776                         }
2777                 } else if (strcmp(listen_addr, "localhost") != 0 ||
2778                     strcmp(listen_addr, "127.0.0.1") == 0 ||
2779                     strcmp(listen_addr, "::1") == 0) {
2780                         /* Accept localhost address when GatewayPorts=yes */
2781                         addr = listen_addr;
2782                 }
2783         } else if (strcmp(listen_addr, "127.0.0.1") == 0 ||
2784             strcmp(listen_addr, "::1") == 0) {
2785                 /*
2786                  * If a specific IPv4/IPv6 localhost address has been
2787                  * requested then accept it even if gateway_ports is in
2788                  * effect. This allows the client to prefer IPv4 or IPv6.
2789                  */
2790                 addr = listen_addr;
2791         }
2792         if (wildcardp != NULL)
2793                 *wildcardp = wildcard;
2794         return addr;
2795 }
2796
2797 static int
2798 channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
2799     int *allocated_listen_port, struct ForwardOptions *fwd_opts)
2800 {
2801         Channel *c;
2802         int sock, r, success = 0, wildcard = 0, is_client;
2803         struct addrinfo hints, *ai, *aitop;
2804         const char *host, *addr;
2805         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2806         in_port_t *lport_p;
2807
2808         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2809             fwd->listen_host : fwd->connect_host;
2810         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2811
2812         if (host == NULL) {
2813                 error("No forward host name.");
2814                 return 0;
2815         }
2816         if (strlen(host) >= NI_MAXHOST) {
2817                 error("Forward host name too long.");
2818                 return 0;
2819         }
2820
2821         /* Determine the bind address, cf. channel_fwd_bind_addr() comment */
2822         addr = channel_fwd_bind_addr(fwd->listen_host, &wildcard,
2823             is_client, fwd_opts);
2824         debug3("%s: type %d wildcard %d addr %s", __func__,
2825             type, wildcard, (addr == NULL) ? "NULL" : addr);
2826
2827         /*
2828          * getaddrinfo returns a loopback address if the hostname is
2829          * set to NULL and hints.ai_flags is not AI_PASSIVE
2830          */
2831         memset(&hints, 0, sizeof(hints));
2832         hints.ai_family = IPv4or6;
2833         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2834         hints.ai_socktype = SOCK_STREAM;
2835         snprintf(strport, sizeof strport, "%d", fwd->listen_port);
2836         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2837                 if (addr == NULL) {
2838                         /* This really shouldn't happen */
2839                         packet_disconnect("getaddrinfo: fatal error: %s",
2840                             ssh_gai_strerror(r));
2841                 } else {
2842                         error("%s: getaddrinfo(%.64s): %s", __func__, addr,
2843                             ssh_gai_strerror(r));
2844                 }
2845                 return 0;
2846         }
2847         if (allocated_listen_port != NULL)
2848                 *allocated_listen_port = 0;
2849         for (ai = aitop; ai; ai = ai->ai_next) {
2850                 switch (ai->ai_family) {
2851                 case AF_INET:
2852                         lport_p = &((struct sockaddr_in *)ai->ai_addr)->
2853                             sin_port;
2854                         break;
2855                 case AF_INET6:
2856                         lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
2857                             sin6_port;
2858                         break;
2859                 default:
2860                         continue;
2861                 }
2862                 /*
2863                  * If allocating a port for -R forwards, then use the
2864                  * same port for all address families.
2865                  */
2866                 if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
2867                     allocated_listen_port != NULL && *allocated_listen_port > 0)
2868                         *lport_p = htons(*allocated_listen_port);
2869
2870                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2871                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2872                         error("%s: getnameinfo failed", __func__);
2873                         continue;
2874                 }
2875                 /* Create a port to listen for the host. */
2876                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2877                 if (sock < 0) {
2878                         /* this is no error since kernel may not support ipv6 */
2879                         verbose("socket: %.100s", strerror(errno));
2880                         continue;
2881                 }
2882
2883                 channel_set_reuseaddr(sock);
2884                 if (ai->ai_family == AF_INET6)
2885                         sock_set_v6only(sock);
2886
2887                 debug("Local forwarding listening on %s port %s.",
2888                     ntop, strport);
2889
2890                 /* Bind the socket to the address. */
2891                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2892                         /* address can be in use ipv6 address is already bound */
2893                         if (!ai->ai_next)
2894                                 error("bind: %.100s", strerror(errno));
2895                         else
2896                                 verbose("bind: %.100s", strerror(errno));
2897
2898                         close(sock);
2899                         continue;
2900                 }
2901                 /* Start listening for connections on the socket. */
2902                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2903                         error("listen: %.100s", strerror(errno));
2904                         close(sock);
2905                         continue;
2906                 }
2907
2908                 /*
2909                  * fwd->listen_port == 0 requests a dynamically allocated port -
2910                  * record what we got.
2911                  */
2912                 if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
2913                     allocated_listen_port != NULL &&
2914                     *allocated_listen_port == 0) {
2915                         *allocated_listen_port = get_sock_port(sock, 1);
2916                         debug("Allocated listen port %d",
2917                             *allocated_listen_port);
2918                 }
2919
2920                 /* Allocate a channel number for the socket. */
2921                 c = channel_new("port listener", type, sock, sock, -1,
2922                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2923                     0, "port listener", 1);
2924                 c->path = xstrdup(host);
2925                 c->host_port = fwd->connect_port;
2926                 c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
2927                 if (fwd->listen_port == 0 && allocated_listen_port != NULL &&
2928                     !(datafellows & SSH_BUG_DYNAMIC_RPORT))
2929                         c->listening_port = *allocated_listen_port;
2930                 else
2931                         c->listening_port = fwd->listen_port;
2932                 success = 1;
2933         }
2934         if (success == 0)
2935                 error("%s: cannot listen to port: %d", __func__,
2936                     fwd->listen_port);
2937         freeaddrinfo(aitop);
2938         return success;
2939 }
2940
2941 static int
2942 channel_setup_fwd_listener_streamlocal(int type, struct Forward *fwd,
2943     struct ForwardOptions *fwd_opts)
2944 {
2945         struct sockaddr_un sunaddr;
2946         const char *path;
2947         Channel *c;
2948         int port, sock;
2949         mode_t omask;
2950
2951         switch (type) {
2952         case SSH_CHANNEL_UNIX_LISTENER:
2953                 if (fwd->connect_path != NULL) {
2954                         if (strlen(fwd->connect_path) > sizeof(sunaddr.sun_path)) {
2955                                 error("Local connecting path too long: %s",
2956                                     fwd->connect_path);
2957                                 return 0;
2958                         }
2959                         path = fwd->connect_path;
2960                         port = PORT_STREAMLOCAL;
2961                 } else {
2962                         if (fwd->connect_host == NULL) {
2963                                 error("No forward host name.");
2964                                 return 0;
2965                         }
2966                         if (strlen(fwd->connect_host) >= NI_MAXHOST) {
2967                                 error("Forward host name too long.");
2968                                 return 0;
2969                         }
2970                         path = fwd->connect_host;
2971                         port = fwd->connect_port;
2972                 }
2973                 break;
2974         case SSH_CHANNEL_RUNIX_LISTENER:
2975                 path = fwd->listen_path;
2976                 port = PORT_STREAMLOCAL;
2977                 break;
2978         default:
2979                 error("%s: unexpected channel type %d", __func__, type);
2980                 return 0;
2981         }
2982
2983         if (fwd->listen_path == NULL) {
2984                 error("No forward path name.");
2985                 return 0;
2986         }
2987         if (strlen(fwd->listen_path) > sizeof(sunaddr.sun_path)) {
2988                 error("Local listening path too long: %s", fwd->listen_path);
2989                 return 0;
2990         }
2991
2992         debug3("%s: type %d path %s", __func__, type, fwd->listen_path);
2993
2994         /* Start a Unix domain listener. */
2995         omask = umask(fwd_opts->streamlocal_bind_mask);
2996         sock = unix_listener(fwd->listen_path, SSH_LISTEN_BACKLOG,
2997             fwd_opts->streamlocal_bind_unlink);
2998         umask(omask);
2999         if (sock < 0)
3000                 return 0;
3001
3002         debug("Local forwarding listening on path %s.", fwd->listen_path);
3003
3004         /* Allocate a channel number for the socket. */
3005         c = channel_new("unix listener", type, sock, sock, -1,
3006             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
3007             0, "unix listener", 1);
3008         c->path = xstrdup(path);
3009         c->host_port = port;
3010         c->listening_port = PORT_STREAMLOCAL;
3011         c->listening_addr = xstrdup(fwd->listen_path);
3012         return 1;
3013 }
3014
3015 static int
3016 channel_cancel_rport_listener_tcpip(const char *host, u_short port)
3017 {
3018         u_int i;
3019         int found = 0;
3020
3021         for (i = 0; i < channels_alloc; i++) {
3022                 Channel *c = channels[i];
3023                 if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
3024                         continue;
3025                 if (strcmp(c->path, host) == 0 && c->listening_port == port) {
3026                         debug2("%s: close channel %d", __func__, i);
3027                         channel_free(c);
3028                         found = 1;
3029                 }
3030         }
3031
3032         return (found);
3033 }
3034
3035 static int
3036 channel_cancel_rport_listener_streamlocal(const char *path)
3037 {
3038         u_int i;
3039         int found = 0;
3040
3041         for (i = 0; i < channels_alloc; i++) {
3042                 Channel *c = channels[i];
3043                 if (c == NULL || c->type != SSH_CHANNEL_RUNIX_LISTENER)
3044                         continue;
3045                 if (c->path == NULL)
3046                         continue;
3047                 if (strcmp(c->path, path) == 0) {
3048                         debug2("%s: close channel %d", __func__, i);
3049                         channel_free(c);
3050                         found = 1;
3051                 }
3052         }
3053
3054         return (found);
3055 }
3056
3057 int
3058 channel_cancel_rport_listener(struct Forward *fwd)
3059 {
3060         if (fwd->listen_path != NULL)
3061                 return channel_cancel_rport_listener_streamlocal(fwd->listen_path);
3062         else
3063                 return channel_cancel_rport_listener_tcpip(fwd->listen_host, fwd->listen_port);
3064 }
3065
3066 static int
3067 channel_cancel_lport_listener_tcpip(const char *lhost, u_short lport,
3068     int cport, struct ForwardOptions *fwd_opts)
3069 {
3070         u_int i;
3071         int found = 0;
3072         const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, fwd_opts);
3073
3074         for (i = 0; i < channels_alloc; i++) {
3075                 Channel *c = channels[i];
3076                 if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
3077                         continue;
3078                 if (c->listening_port != lport)
3079                         continue;
3080                 if (cport == CHANNEL_CANCEL_PORT_STATIC) {
3081                         /* skip dynamic forwardings */
3082                         if (c->host_port == 0)
3083                                 continue;
3084                 } else {
3085                         if (c->host_port != cport)
3086                                 continue;
3087                 }
3088                 if ((c->listening_addr == NULL && addr != NULL) ||
3089                     (c->listening_addr != NULL && addr == NULL))
3090                         continue;
3091                 if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
3092                         debug2("%s: close channel %d", __func__, i);
3093                         channel_free(c);
3094                         found = 1;
3095                 }
3096         }
3097
3098         return (found);
3099 }
3100
3101 static int
3102 channel_cancel_lport_listener_streamlocal(const char *path)
3103 {
3104         u_int i;
3105         int found = 0;
3106
3107         if (path == NULL) {
3108                 error("%s: no path specified.", __func__);
3109                 return 0;
3110         }
3111
3112         for (i = 0; i < channels_alloc; i++) {
3113                 Channel *c = channels[i];
3114                 if (c == NULL || c->type != SSH_CHANNEL_UNIX_LISTENER)
3115                         continue;
3116                 if (c->listening_addr == NULL)
3117                         continue;
3118                 if (strcmp(c->listening_addr, path) == 0) {
3119                         debug2("%s: close channel %d", __func__, i);
3120                         channel_free(c);
3121                         found = 1;
3122                 }
3123         }
3124
3125         return (found);
3126 }
3127
3128 int
3129 channel_cancel_lport_listener(struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
3130 {
3131         if (fwd->listen_path != NULL)
3132                 return channel_cancel_lport_listener_streamlocal(fwd->listen_path);
3133         else
3134                 return channel_cancel_lport_listener_tcpip(fwd->listen_host, fwd->listen_port, cport, fwd_opts);
3135 }
3136
3137 /* protocol local port fwd, used by ssh (and sshd in v1) */
3138 int
3139 channel_setup_local_fwd_listener(struct Forward *fwd, struct ForwardOptions *fwd_opts)
3140 {
3141         if (fwd->listen_path != NULL) {
3142                 return channel_setup_fwd_listener_streamlocal(
3143                     SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts);
3144         } else {
3145                 return channel_setup_fwd_listener_tcpip(SSH_CHANNEL_PORT_LISTENER,
3146                     fwd, NULL, fwd_opts);
3147         }
3148 }
3149
3150 /* protocol v2 remote port fwd, used by sshd */
3151 int
3152 channel_setup_remote_fwd_listener(struct Forward *fwd,
3153     int *allocated_listen_port, struct ForwardOptions *fwd_opts)
3154 {
3155         if (fwd->listen_path != NULL) {
3156                 return channel_setup_fwd_listener_streamlocal(
3157                     SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts);
3158         } else {
3159                 return channel_setup_fwd_listener_tcpip(
3160                     SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port,
3161                     fwd_opts);
3162         }
3163 }
3164
3165 /*
3166  * Translate the requested rfwd listen host to something usable for
3167  * this server.
3168  */
3169 static const char *
3170 channel_rfwd_bind_host(const char *listen_host)
3171 {
3172         if (listen_host == NULL) {
3173                 if (datafellows & SSH_BUG_RFWD_ADDR)
3174                         return "127.0.0.1";
3175                 else
3176                         return "localhost";
3177         } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
3178                 if (datafellows & SSH_BUG_RFWD_ADDR)
3179                         return "0.0.0.0";
3180                 else
3181                         return "";
3182         } else
3183                 return listen_host;
3184 }
3185
3186 /*
3187  * Initiate forwarding of connections to port "port" on remote host through
3188  * the secure channel to host:port from local side.
3189  * Returns handle (index) for updating the dynamic listen port with
3190  * channel_update_permitted_opens().
3191  */
3192 int
3193 channel_request_remote_forwarding(struct Forward *fwd)
3194 {
3195         int type, success = 0, idx = -1;
3196
3197         /* Send the forward request to the remote side. */
3198         if (compat20) {
3199                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
3200                 if (fwd->listen_path != NULL) {
3201                     packet_put_cstring("streamlocal-forward@openssh.com");
3202                     packet_put_char(1);         /* boolean: want reply */
3203                     packet_put_cstring(fwd->listen_path);
3204                 } else {
3205                     packet_put_cstring("tcpip-forward");
3206                     packet_put_char(1);         /* boolean: want reply */
3207                     packet_put_cstring(channel_rfwd_bind_host(fwd->listen_host));
3208                     packet_put_int(fwd->listen_port);
3209                 }
3210                 packet_send();
3211                 packet_write_wait();
3212                 /* Assume that server accepts the request */
3213                 success = 1;
3214         } else if (fwd->listen_path == NULL) {
3215                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
3216                 packet_put_int(fwd->listen_port);
3217                 packet_put_cstring(fwd->connect_host);
3218                 packet_put_int(fwd->connect_port);
3219                 packet_send();
3220                 packet_write_wait();
3221
3222                 /* Wait for response from the remote side. */
3223                 type = packet_read();
3224                 switch (type) {
3225                 case SSH_SMSG_SUCCESS:
3226                         success = 1;
3227                         break;
3228                 case SSH_SMSG_FAILURE:
3229                         break;
3230                 default:
3231                         /* Unknown packet */
3232                         packet_disconnect("Protocol error for port forward request:"
3233                             "received packet type %d.", type);
3234                 }
3235         } else {
3236                 logit("Warning: Server does not support remote stream local forwarding.");
3237         }
3238         if (success) {
3239                 /* Record that connection to this host/port is permitted. */
3240                 permitted_opens = xrealloc(permitted_opens,
3241                     num_permitted_opens + 1, sizeof(*permitted_opens));
3242                 idx = num_permitted_opens++;
3243                 if (fwd->connect_path != NULL) {
3244                         permitted_opens[idx].host_to_connect =
3245                             xstrdup(fwd->connect_path);
3246                         permitted_opens[idx].port_to_connect =
3247                             PORT_STREAMLOCAL;
3248                 } else {
3249                         permitted_opens[idx].host_to_connect =
3250                             xstrdup(fwd->connect_host);
3251                         permitted_opens[idx].port_to_connect =
3252                             fwd->connect_port;
3253                 }
3254                 if (fwd->listen_path != NULL) {
3255                         permitted_opens[idx].listen_host = NULL;
3256                         permitted_opens[idx].listen_path =
3257                             xstrdup(fwd->listen_path);
3258                         permitted_opens[idx].listen_port = PORT_STREAMLOCAL;
3259                 } else {
3260                         permitted_opens[idx].listen_host =
3261                             fwd->listen_host ? xstrdup(fwd->listen_host) : NULL;
3262                         permitted_opens[idx].listen_path = NULL;
3263                         permitted_opens[idx].listen_port = fwd->listen_port;
3264                 }
3265         }
3266         return (idx);
3267 }
3268
3269 static int
3270 open_match(ForwardPermission *allowed_open, const char *requestedhost,
3271     int requestedport)
3272 {
3273         if (allowed_open->host_to_connect == NULL)
3274                 return 0;
3275         if (allowed_open->port_to_connect != FWD_PERMIT_ANY_PORT &&
3276             allowed_open->port_to_connect != requestedport)
3277                 return 0;
3278         if (strcmp(allowed_open->host_to_connect, requestedhost) != 0)
3279                 return 0;
3280         return 1;
3281 }
3282
3283 /*
3284  * Note that in the listen host/port case
3285  * we don't support FWD_PERMIT_ANY_PORT and
3286  * need to translate between the configured-host (listen_host)
3287  * and what we've sent to the remote server (channel_rfwd_bind_host)
3288  */
3289 static int
3290 open_listen_match_tcpip(ForwardPermission *allowed_open,
3291     const char *requestedhost, u_short requestedport, int translate)
3292 {
3293         const char *allowed_host;
3294
3295         if (allowed_open->host_to_connect == NULL)
3296                 return 0;
3297         if (allowed_open->listen_port != requestedport)
3298                 return 0;
3299         if (!translate && allowed_open->listen_host == NULL &&
3300             requestedhost == NULL)
3301                 return 1;
3302         allowed_host = translate ?
3303             channel_rfwd_bind_host(allowed_open->listen_host) :
3304             allowed_open->listen_host;
3305         if (allowed_host == NULL ||
3306             strcmp(allowed_host, requestedhost) != 0)
3307                 return 0;
3308         return 1;
3309 }
3310
3311 static int
3312 open_listen_match_streamlocal(ForwardPermission *allowed_open,
3313     const char *requestedpath)
3314 {
3315         if (allowed_open->host_to_connect == NULL)
3316                 return 0;
3317         if (allowed_open->listen_port != PORT_STREAMLOCAL)
3318                 return 0;
3319         if (allowed_open->listen_path == NULL ||
3320             strcmp(allowed_open->listen_path, requestedpath) != 0)
3321                 return 0;
3322         return 1;
3323 }
3324
3325 /*
3326  * Request cancellation of remote forwarding of connection host:port from
3327  * local side.
3328  */
3329 static int
3330 channel_request_rforward_cancel_tcpip(const char *host, u_short port)
3331 {
3332         int i;
3333
3334         if (!compat20)
3335                 return -1;
3336
3337         for (i = 0; i < num_permitted_opens; i++) {
3338                 if (open_listen_match_tcpip(&permitted_opens[i], host, port, 0))
3339                         break;
3340         }
3341         if (i >= num_permitted_opens) {
3342                 debug("%s: requested forward not found", __func__);
3343                 return -1;
3344         }
3345         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3346         packet_put_cstring("cancel-tcpip-forward");
3347         packet_put_char(0);
3348         packet_put_cstring(channel_rfwd_bind_host(host));
3349         packet_put_int(port);
3350         packet_send();
3351
3352         permitted_opens[i].listen_port = 0;
3353         permitted_opens[i].port_to_connect = 0;
3354         free(permitted_opens[i].host_to_connect);
3355         permitted_opens[i].host_to_connect = NULL;
3356         free(permitted_opens[i].listen_host);
3357         permitted_opens[i].listen_host = NULL;
3358         permitted_opens[i].listen_path = NULL;
3359
3360         return 0;
3361 }
3362
3363 /*
3364  * Request cancellation of remote forwarding of Unix domain socket
3365  * path from local side.
3366  */
3367 static int
3368 channel_request_rforward_cancel_streamlocal(const char *path)
3369 {
3370         int i;
3371
3372         if (!compat20)
3373                 return -1;
3374
3375         for (i = 0; i < num_permitted_opens; i++) {
3376                 if (open_listen_match_streamlocal(&permitted_opens[i], path))
3377                         break;
3378         }
3379         if (i >= num_permitted_opens) {
3380                 debug("%s: requested forward not found", __func__);
3381                 return -1;
3382         }
3383         packet_start(SSH2_MSG_GLOBAL_REQUEST);
3384         packet_put_cstring("cancel-streamlocal-forward@openssh.com");
3385         packet_put_char(0);
3386         packet_put_cstring(path);
3387         packet_send();
3388
3389         permitted_opens[i].listen_port = 0;
3390         permitted_opens[i].port_to_connect = 0;
3391         free(permitted_opens[i].host_to_connect);
3392         permitted_opens[i].host_to_connect = NULL;
3393         permitted_opens[i].listen_host = NULL;
3394         free(permitted_opens[i].listen_path);
3395         permitted_opens[i].listen_path = NULL;
3396
3397         return 0;
3398 }
3399
3400 /*
3401  * Request cancellation of remote forwarding of a connection from local side.
3402  */
3403 int
3404 channel_request_rforward_cancel(struct Forward *fwd)
3405 {
3406         if (fwd->listen_path != NULL) {
3407                 return (channel_request_rforward_cancel_streamlocal(
3408                     fwd->listen_path));
3409         } else {
3410                 return (channel_request_rforward_cancel_tcpip(fwd->listen_host,
3411                     fwd->listen_port ? fwd->listen_port : fwd->allocated_port));
3412         }
3413 }
3414
3415 /*
3416  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
3417  * listening for the port, and sends back a success reply (or disconnect
3418  * message if there was an error).
3419  */
3420 int
3421 channel_input_port_forward_request(int is_root, struct ForwardOptions *fwd_opts)
3422 {
3423         int success = 0;
3424         struct Forward fwd;
3425
3426         /* Get arguments from the packet. */
3427         memset(&fwd, 0, sizeof(fwd));
3428         fwd.listen_port = packet_get_int();
3429         fwd.connect_host = packet_get_string(NULL);
3430         fwd.connect_port = packet_get_int();
3431
3432 #ifndef HAVE_CYGWIN
3433         /*
3434          * Check that an unprivileged user is not trying to forward a
3435          * privileged port.
3436          */
3437         if (fwd.listen_port < IPPORT_RESERVED && !is_root)
3438                 packet_disconnect(
3439                     "Requested forwarding of port %d but user is not root.",
3440                     fwd.listen_port);
3441         if (fwd.connect_port == 0)
3442                 packet_disconnect("Dynamic forwarding denied.");
3443 #endif
3444
3445         /* Initiate forwarding */
3446         success = channel_setup_local_fwd_listener(&fwd, fwd_opts);
3447
3448         /* Free the argument string. */
3449         free(fwd.connect_host);
3450
3451         return (success ? 0 : -1);
3452 }
3453
3454 /*
3455  * Permits opening to any host/port if permitted_opens[] is empty.  This is
3456  * usually called by the server, because the user could connect to any port
3457  * anyway, and the server has no way to know but to trust the client anyway.
3458  */
3459 void
3460 channel_permit_all_opens(void)
3461 {
3462         if (num_permitted_opens == 0)
3463                 all_opens_permitted = 1;
3464 }
3465
3466 void
3467 channel_add_permitted_opens(char *host, int port)
3468 {
3469         debug("allow port forwarding to host %s port %d", host, port);
3470
3471         permitted_opens = xrealloc(permitted_opens,
3472             num_permitted_opens + 1, sizeof(*permitted_opens));
3473         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
3474         permitted_opens[num_permitted_opens].port_to_connect = port;
3475         permitted_opens[num_permitted_opens].listen_host = NULL;
3476         permitted_opens[num_permitted_opens].listen_path = NULL;
3477         permitted_opens[num_permitted_opens].listen_port = 0;
3478         num_permitted_opens++;
3479
3480         all_opens_permitted = 0;
3481 }
3482
3483 /*
3484  * Update the listen port for a dynamic remote forward, after
3485  * the actual 'newport' has been allocated. If 'newport' < 0 is
3486  * passed then they entry will be invalidated.
3487  */
3488 void
3489 channel_update_permitted_opens(int idx, int newport)
3490 {
3491         if (idx < 0 || idx >= num_permitted_opens) {
3492                 debug("channel_update_permitted_opens: index out of range:"
3493                     " %d num_permitted_opens %d", idx, num_permitted_opens);
3494                 return;
3495         }
3496         debug("%s allowed port %d for forwarding to host %s port %d",
3497             newport > 0 ? "Updating" : "Removing",
3498             newport,
3499             permitted_opens[idx].host_to_connect,
3500             permitted_opens[idx].port_to_connect);
3501         if (newport >= 0)  {
3502                 permitted_opens[idx].listen_port =
3503                     (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
3504         } else {
3505                 permitted_opens[idx].listen_port = 0;
3506                 permitted_opens[idx].port_to_connect = 0;
3507                 free(permitted_opens[idx].host_to_connect);
3508                 permitted_opens[idx].host_to_connect = NULL;
3509                 free(permitted_opens[idx].listen_host);
3510                 permitted_opens[idx].listen_host = NULL;
3511                 free(permitted_opens[idx].listen_path);
3512                 permitted_opens[idx].listen_path = NULL;
3513         }
3514 }
3515
3516 int
3517 channel_add_adm_permitted_opens(char *host, int port)
3518 {
3519         debug("config allows port forwarding to host %s port %d", host, port);
3520
3521         permitted_adm_opens = xrealloc(permitted_adm_opens,
3522             num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
3523         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
3524              = xstrdup(host);
3525         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
3526         permitted_adm_opens[num_adm_permitted_opens].listen_host = NULL;
3527         permitted_adm_opens[num_adm_permitted_opens].listen_path = NULL;
3528         permitted_adm_opens[num_adm_permitted_opens].listen_port = 0;
3529         return ++num_adm_permitted_opens;
3530 }
3531
3532 void
3533 channel_disable_adm_local_opens(void)
3534 {
3535         channel_clear_adm_permitted_opens();
3536         permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
3537         permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
3538         num_adm_permitted_opens = 1;
3539 }
3540
3541 void
3542 channel_clear_permitted_opens(void)
3543 {
3544         int i;
3545
3546         for (i = 0; i < num_permitted_opens; i++) {
3547                 free(permitted_opens[i].host_to_connect);
3548                 free(permitted_opens[i].listen_host);
3549                 free(permitted_opens[i].listen_path);
3550         }
3551         free(permitted_opens);
3552         permitted_opens = NULL;
3553         num_permitted_opens = 0;
3554 }
3555
3556 void
3557 channel_clear_adm_permitted_opens(void)
3558 {
3559         int i;
3560
3561         for (i = 0; i < num_adm_permitted_opens; i++) {
3562                 free(permitted_adm_opens[i].host_to_connect);
3563                 free(permitted_adm_opens[i].listen_host);
3564                 free(permitted_adm_opens[i].listen_path);
3565         }
3566         free(permitted_adm_opens);
3567         permitted_adm_opens = NULL;
3568         num_adm_permitted_opens = 0;
3569 }
3570
3571 void
3572 channel_print_adm_permitted_opens(void)
3573 {
3574         int i;
3575
3576         printf("permitopen");
3577         if (num_adm_permitted_opens == 0) {
3578                 printf(" any\n");
3579                 return;
3580         }
3581         for (i = 0; i < num_adm_permitted_opens; i++)
3582                 if (permitted_adm_opens[i].host_to_connect == NULL)
3583                         printf(" none");
3584                 else
3585                         printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
3586                             permitted_adm_opens[i].port_to_connect);
3587         printf("\n");
3588 }
3589
3590 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
3591 int
3592 permitopen_port(const char *p)
3593 {
3594         int port;
3595
3596         if (strcmp(p, "*") == 0)
3597                 return FWD_PERMIT_ANY_PORT;
3598         if ((port = a2port(p)) > 0)
3599                 return port;
3600         return -1;
3601 }
3602
3603 /* Try to start non-blocking connect to next host in cctx list */
3604 static int
3605 connect_next(struct channel_connect *cctx)
3606 {
3607         int sock, saved_errno;
3608         struct sockaddr_un *sunaddr;
3609         char ntop[NI_MAXHOST], strport[MAX(NI_MAXSERV,sizeof(sunaddr->sun_path))];
3610
3611         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
3612                 switch (cctx->ai->ai_family) {
3613                 case AF_UNIX:
3614                         /* unix:pathname instead of host:port */
3615                         sunaddr = (struct sockaddr_un *)cctx->ai->ai_addr;
3616                         strlcpy(ntop, "unix", sizeof(ntop));
3617                         strlcpy(strport, sunaddr->sun_path, sizeof(strport));
3618                         break;
3619                 case AF_INET:
3620                 case AF_INET6:
3621                         if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
3622                             ntop, sizeof(ntop), strport, sizeof(strport),
3623                             NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
3624                                 error("connect_next: getnameinfo failed");
3625                                 continue;
3626                         }
3627                         break;
3628                 default:
3629                         continue;
3630                 }
3631                 if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
3632                     cctx->ai->ai_protocol)) == -1) {
3633                         if (cctx->ai->ai_next == NULL)
3634                                 error("socket: %.100s", strerror(errno));
3635                         else
3636                                 verbose("socket: %.100s", strerror(errno));
3637                         continue;
3638                 }
3639                 if (set_nonblock(sock) == -1)
3640                         fatal("%s: set_nonblock(%d)", __func__, sock);
3641                 if (connect(sock, cctx->ai->ai_addr,
3642                     cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
3643                         debug("connect_next: host %.100s ([%.100s]:%s): "
3644                             "%.100s", cctx->host, ntop, strport,
3645                             strerror(errno));
3646                         saved_errno = errno;
3647                         close(sock);
3648                         errno = saved_errno;
3649                         continue;       /* fail -- try next */
3650                 }
3651                 if (cctx->ai->ai_family != AF_UNIX)
3652                         set_nodelay(sock);
3653                 debug("connect_next: host %.100s ([%.100s]:%s) "
3654                     "in progress, fd=%d", cctx->host, ntop, strport, sock);
3655                 cctx->ai = cctx->ai->ai_next;
3656                 return sock;
3657         }
3658         return -1;
3659 }
3660
3661 static void
3662 channel_connect_ctx_free(struct channel_connect *cctx)
3663 {
3664         free(cctx->host);
3665         if (cctx->aitop) {
3666                 if (cctx->aitop->ai_family == AF_UNIX)
3667                         free(cctx->aitop);
3668                 else
3669                         freeaddrinfo(cctx->aitop);
3670         }
3671         memset(cctx, 0, sizeof(*cctx));
3672 }
3673
3674 /* Return CONNECTING channel to remote host:port or local socket path */
3675 static Channel *
3676 connect_to(const char *name, int port, char *ctype, char *rname)
3677 {
3678         struct addrinfo hints;
3679         int gaierr;
3680         int sock = -1;
3681         char strport[NI_MAXSERV];
3682         struct channel_connect cctx;
3683         Channel *c;
3684
3685         memset(&cctx, 0, sizeof(cctx));
3686
3687         if (port == PORT_STREAMLOCAL) {
3688                 struct sockaddr_un *sunaddr;
3689                 struct addrinfo *ai;
3690
3691                 if (strlen(name) > sizeof(sunaddr->sun_path)) {
3692                         error("%.100s: %.100s", name, strerror(ENAMETOOLONG));
3693                         return (NULL);
3694                 }
3695
3696                 /*
3697                  * Fake up a struct addrinfo for AF_UNIX connections.
3698                  * channel_connect_ctx_free() must check ai_family
3699                  * and use free() not freeaddirinfo() for AF_UNIX.
3700                  */
3701                 ai = xmalloc(sizeof(*ai) + sizeof(*sunaddr));
3702                 memset(ai, 0, sizeof(*ai) + sizeof(*sunaddr));
3703                 ai->ai_addr = (struct sockaddr *)(ai + 1);
3704                 ai->ai_addrlen = sizeof(*sunaddr);
3705                 ai->ai_family = AF_UNIX;
3706                 ai->ai_socktype = SOCK_STREAM;
3707                 ai->ai_protocol = PF_UNSPEC;
3708                 sunaddr = (struct sockaddr_un *)ai->ai_addr;
3709                 sunaddr->sun_family = AF_UNIX;
3710                 strlcpy(sunaddr->sun_path, name, sizeof(sunaddr->sun_path));
3711                 cctx.aitop = ai;
3712         } else {
3713                 memset(&hints, 0, sizeof(hints));
3714                 hints.ai_family = IPv4or6;
3715                 hints.ai_socktype = SOCK_STREAM;
3716                 snprintf(strport, sizeof strport, "%d", port);
3717                 if ((gaierr = getaddrinfo(name, strport, &hints, &cctx.aitop)) != 0) {
3718                         error("connect_to %.100s: unknown host (%s)", name,
3719                             ssh_gai_strerror(gaierr));
3720                         return NULL;
3721                 }
3722         }
3723
3724         cctx.host = xstrdup(name);
3725         cctx.port = port;
3726         cctx.ai = cctx.aitop;
3727
3728         if ((sock = connect_next(&cctx)) == -1) {
3729                 error("connect to %.100s port %d failed: %s",
3730                     name, port, strerror(errno));
3731                 channel_connect_ctx_free(&cctx);
3732                 return NULL;
3733         }
3734         c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
3735             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
3736         c->connect_ctx = cctx;
3737         return c;
3738 }
3739
3740 Channel *
3741 channel_connect_by_listen_address(const char *listen_host,
3742     u_short listen_port, char *ctype, char *rname)
3743 {
3744         int i;
3745
3746         for (i = 0; i < num_permitted_opens; i++) {
3747                 if (open_listen_match_tcpip(&permitted_opens[i], listen_host,
3748                     listen_port, 1)) {
3749                         return connect_to(
3750                             permitted_opens[i].host_to_connect,
3751                             permitted_opens[i].port_to_connect, ctype, rname);
3752                 }
3753         }
3754         error("WARNING: Server requests forwarding for unknown listen_port %d",
3755             listen_port);
3756         return NULL;
3757 }
3758
3759 Channel *
3760 channel_connect_by_listen_path(const char *path, char *ctype, char *rname)
3761 {
3762         int i;
3763
3764         for (i = 0; i < num_permitted_opens; i++) {
3765                 if (open_listen_match_streamlocal(&permitted_opens[i], path)) {
3766                         return connect_to(
3767                             permitted_opens[i].host_to_connect,
3768                             permitted_opens[i].port_to_connect, ctype, rname);
3769                 }
3770         }
3771         error("WARNING: Server requests forwarding for unknown path %.100s",
3772             path);
3773         return NULL;
3774 }
3775
3776 /* Check if connecting to that port is permitted and connect. */
3777 Channel *
3778 channel_connect_to_port(const char *host, u_short port, char *ctype, char *rname)
3779 {
3780         int i, permit, permit_adm = 1;
3781
3782         permit = all_opens_permitted;
3783         if (!permit) {
3784                 for (i = 0; i < num_permitted_opens; i++)
3785                         if (open_match(&permitted_opens[i], host, port)) {
3786                                 permit = 1;
3787                                 break;
3788                         }
3789         }
3790
3791         if (num_adm_permitted_opens > 0) {
3792                 permit_adm = 0;
3793                 for (i = 0; i < num_adm_permitted_opens; i++)
3794                         if (open_match(&permitted_adm_opens[i], host, port)) {
3795                                 permit_adm = 1;
3796                                 break;
3797                         }
3798         }
3799
3800         if (!permit || !permit_adm) {
3801                 logit("Received request to connect to host %.100s port %d, "
3802                     "but the request was denied.", host, port);
3803                 return NULL;
3804         }
3805         return connect_to(host, port, ctype, rname);
3806 }
3807
3808 /* Check if connecting to that path is permitted and connect. */
3809 Channel *
3810 channel_connect_to_path(const char *path, char *ctype, char *rname)
3811 {
3812         int i, permit, permit_adm = 1;
3813
3814         permit = all_opens_permitted;
3815         if (!permit) {
3816                 for (i = 0; i < num_permitted_opens; i++)
3817                         if (open_match(&permitted_opens[i], path, PORT_STREAMLOCAL)) {
3818                                 permit = 1;
3819                                 break;
3820                         }
3821         }
3822
3823         if (num_adm_permitted_opens > 0) {
3824                 permit_adm = 0;
3825                 for (i = 0; i < num_adm_permitted_opens; i++)
3826                         if (open_match(&permitted_adm_opens[i], path, PORT_STREAMLOCAL)) {
3827                                 permit_adm = 1;
3828                                 break;
3829                         }
3830         }
3831
3832         if (!permit || !permit_adm) {
3833                 logit("Received request to connect to path %.100s, "
3834                     "but the request was denied.", path);
3835                 return NULL;
3836         }
3837         return connect_to(path, PORT_STREAMLOCAL, ctype, rname);
3838 }
3839
3840 void
3841 channel_send_window_changes(void)
3842 {
3843         u_int i;
3844         struct winsize ws;
3845
3846         for (i = 0; i < channels_alloc; i++) {
3847                 if (channels[i] == NULL || !channels[i]->client_tty ||
3848                     channels[i]->type != SSH_CHANNEL_OPEN)
3849                         continue;
3850                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
3851                         continue;
3852                 channel_request_start(i, "window-change", 0);
3853                 packet_put_int((u_int)ws.ws_col);
3854                 packet_put_int((u_int)ws.ws_row);
3855                 packet_put_int((u_int)ws.ws_xpixel);
3856                 packet_put_int((u_int)ws.ws_ypixel);
3857                 packet_send();
3858         }
3859 }
3860
3861 /* -- X11 forwarding */
3862
3863 /*
3864  * Creates an internet domain socket for listening for X11 connections.
3865  * Returns 0 and a suitable display number for the DISPLAY variable
3866  * stored in display_numberp , or -1 if an error occurs.
3867  */
3868 int
3869 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
3870     int single_connection, u_int *display_numberp, int **chanids)
3871 {
3872         Channel *nc = NULL;
3873         int display_number, sock;
3874         u_short port;
3875         struct addrinfo hints, *ai, *aitop;
3876         char strport[NI_MAXSERV];
3877         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
3878
3879         if (chanids == NULL)
3880                 return -1;
3881
3882         for (display_number = x11_display_offset;
3883             display_number < MAX_DISPLAYS;
3884             display_number++) {
3885                 port = 6000 + display_number;
3886                 memset(&hints, 0, sizeof(hints));
3887                 hints.ai_family = IPv4or6;
3888                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
3889                 hints.ai_socktype = SOCK_STREAM;
3890                 snprintf(strport, sizeof strport, "%d", port);
3891                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
3892                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
3893                         return -1;
3894                 }
3895                 for (ai = aitop; ai; ai = ai->ai_next) {
3896                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
3897                                 continue;
3898                         sock = socket(ai->ai_family, ai->ai_socktype,
3899                             ai->ai_protocol);
3900                         if (sock < 0) {
3901                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
3902 #ifdef EPFNOSUPPORT
3903                                     && (errno != EPFNOSUPPORT)
3904 #endif
3905                                     ) {
3906                                         error("socket: %.100s", strerror(errno));
3907                                         freeaddrinfo(aitop);
3908                                         return -1;
3909                                 } else {
3910                                         debug("x11_create_display_inet: Socket family %d not supported",
3911                                                  ai->ai_family);
3912                                         continue;
3913                                 }
3914                         }
3915                         if (ai->ai_family == AF_INET6)
3916                                 sock_set_v6only(sock);
3917                         if (x11_use_localhost)
3918                                 channel_set_reuseaddr(sock);
3919                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3920                                 debug2("bind port %d: %.100s", port, strerror(errno));
3921                                 close(sock);
3922
3923                                 for (n = 0; n < num_socks; n++) {
3924                                         close(socks[n]);
3925                                 }
3926                                 num_socks = 0;
3927                                 break;
3928                         }
3929                         socks[num_socks++] = sock;
3930                         if (num_socks == NUM_SOCKS)
3931                                 break;
3932                 }
3933                 freeaddrinfo(aitop);
3934                 if (num_socks > 0)
3935                         break;
3936         }
3937         if (display_number >= MAX_DISPLAYS) {
3938                 error("Failed to allocate internet-domain X11 display socket.");
3939                 return -1;
3940         }
3941         /* Start listening for connections on the socket. */
3942         for (n = 0; n < num_socks; n++) {
3943                 sock = socks[n];
3944                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
3945                         error("listen: %.100s", strerror(errno));
3946                         close(sock);
3947                         return -1;
3948                 }
3949         }
3950
3951         /* Allocate a channel for each socket. */
3952         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
3953         for (n = 0; n < num_socks; n++) {
3954                 sock = socks[n];
3955                 nc = channel_new("x11 listener",
3956                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
3957                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
3958                     0, "X11 inet listener", 1);
3959                 nc->single_connection = single_connection;
3960                 (*chanids)[n] = nc->self;
3961         }
3962         (*chanids)[n] = -1;
3963
3964         /* Return the display number for the DISPLAY environment variable. */
3965         *display_numberp = display_number;
3966         return (0);
3967 }
3968
3969 static int
3970 connect_local_xsocket_path(const char *pathname)
3971 {
3972         int sock;
3973         struct sockaddr_un addr;
3974
3975         sock = socket(AF_UNIX, SOCK_STREAM, 0);
3976         if (sock < 0)
3977                 error("socket: %.100s", strerror(errno));
3978         memset(&addr, 0, sizeof(addr));
3979         addr.sun_family = AF_UNIX;
3980         strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
3981         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
3982                 return sock;
3983         close(sock);
3984         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
3985         return -1;
3986 }
3987
3988 static int
3989 connect_local_xsocket(u_int dnr)
3990 {
3991         char buf[1024];
3992         snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
3993         return connect_local_xsocket_path(buf);
3994 }
3995
3996 int
3997 x11_connect_display(void)
3998 {
3999         u_int display_number;
4000         const char *display;
4001         char buf[1024], *cp;
4002         struct addrinfo hints, *ai, *aitop;
4003         char strport[NI_MAXSERV];
4004         int gaierr, sock = 0;
4005
4006         /* Try to open a socket for the local X server. */
4007         display = getenv("DISPLAY");
4008         if (!display) {
4009                 error("DISPLAY not set.");
4010                 return -1;
4011         }
4012         /*
4013          * Now we decode the value of the DISPLAY variable and make a
4014          * connection to the real X server.
4015          */
4016
4017         /* Check if the display is from launchd. */
4018 #ifdef __APPLE__
4019         if (strncmp(display, "/tmp/launch", 11) == 0) {
4020                 sock = connect_local_xsocket_path(display);
4021                 if (sock < 0)
4022                         return -1;
4023
4024                 /* OK, we now have a connection to the display. */
4025                 return sock;
4026         }
4027 #endif
4028         /*
4029          * Check if it is a unix domain socket.  Unix domain displays are in
4030          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
4031          */
4032         if (strncmp(display, "unix:", 5) == 0 ||
4033             display[0] == ':') {
4034                 /* Connect to the unix domain socket. */
4035                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
4036                         error("Could not parse display number from DISPLAY: %.100s",
4037                             display);
4038                         return -1;
4039                 }
4040                 /* Create a socket. */
4041                 sock = connect_local_xsocket(display_number);
4042                 if (sock < 0)
4043                         return -1;
4044
4045                 /* OK, we now have a connection to the display. */
4046                 return sock;
4047         }
4048         /*
4049          * Connect to an inet socket.  The DISPLAY value is supposedly
4050          * hostname:d[.s], where hostname may also be numeric IP address.
4051          */
4052         strlcpy(buf, display, sizeof(buf));
4053         cp = strchr(buf, ':');
4054         if (!cp) {
4055                 error("Could not find ':' in DISPLAY: %.100s", display);
4056                 return -1;
4057         }
4058         *cp = 0;
4059         /* buf now contains the host name.  But first we parse the display number. */
4060         if (sscanf(cp + 1, "%u", &display_number) != 1) {
4061                 error("Could not parse display number from DISPLAY: %.100s",
4062                     display);
4063                 return -1;
4064         }
4065
4066         /* Look up the host address */
4067         memset(&hints, 0, sizeof(hints));
4068         hints.ai_family = IPv4or6;
4069         hints.ai_socktype = SOCK_STREAM;
4070         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
4071         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
4072                 error("%.100s: unknown host. (%s)", buf,
4073                 ssh_gai_strerror(gaierr));
4074                 return -1;
4075         }
4076         for (ai = aitop; ai; ai = ai->ai_next) {
4077                 /* Create a socket. */
4078                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
4079                 if (sock < 0) {
4080                         debug2("socket: %.100s", strerror(errno));
4081                         continue;
4082                 }
4083                 /* Connect it to the display. */
4084                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
4085                         debug2("connect %.100s port %u: %.100s", buf,
4086                             6000 + display_number, strerror(errno));
4087                         close(sock);
4088                         continue;
4089                 }
4090                 /* Success */
4091                 break;
4092         }
4093         freeaddrinfo(aitop);
4094         if (!ai) {
4095                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
4096                     strerror(errno));
4097                 return -1;
4098         }
4099         set_nodelay(sock);
4100         return sock;
4101 }
4102
4103 /*
4104  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
4105  * the remote channel number.  We should do whatever we want, and respond
4106  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
4107  */
4108
4109 /* ARGSUSED */
4110 int
4111 x11_input_open(int type, u_int32_t seq, void *ctxt)
4112 {
4113         Channel *c = NULL;
4114         int remote_id, sock = 0;
4115         char *remote_host;
4116
4117         debug("Received X11 open request.");
4118
4119         remote_id = packet_get_int();
4120
4121         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
4122                 remote_host = packet_get_string(NULL);
4123         } else {
4124                 remote_host = xstrdup("unknown (remote did not supply name)");
4125         }
4126         packet_check_eom();
4127
4128         /* Obtain a connection to the real X display. */
4129         sock = x11_connect_display();
4130         if (sock != -1) {
4131                 /* Allocate a channel for this connection. */
4132                 c = channel_new("connected x11 socket",
4133                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
4134                     remote_host, 1);
4135                 c->remote_id = remote_id;
4136                 c->force_drain = 1;
4137         }
4138         free(remote_host);
4139         if (c == NULL) {
4140                 /* Send refusal to the remote host. */
4141                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
4142                 packet_put_int(remote_id);
4143         } else {
4144                 /* Send a confirmation to the remote host. */
4145                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
4146                 packet_put_int(remote_id);
4147                 packet_put_int(c->self);
4148         }
4149         packet_send();
4150         return 0;
4151 }
4152
4153 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
4154 /* ARGSUSED */
4155 int
4156 deny_input_open(int type, u_int32_t seq, void *ctxt)
4157 {
4158         int rchan = packet_get_int();
4159
4160         switch (type) {
4161         case SSH_SMSG_AGENT_OPEN:
4162                 error("Warning: ssh server tried agent forwarding.");
4163                 break;
4164         case SSH_SMSG_X11_OPEN:
4165                 error("Warning: ssh server tried X11 forwarding.");
4166                 break;
4167         default:
4168                 error("deny_input_open: type %d", type);
4169                 break;
4170         }
4171         error("Warning: this is probably a break-in attempt by a malicious server.");
4172         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
4173         packet_put_int(rchan);
4174         packet_send();
4175         return 0;
4176 }
4177
4178 /*
4179  * Requests forwarding of X11 connections, generates fake authentication
4180  * data, and enables authentication spoofing.
4181  * This should be called in the client only.
4182  */
4183 void
4184 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
4185     const char *proto, const char *data, int want_reply)
4186 {
4187         u_int data_len = (u_int) strlen(data) / 2;
4188         u_int i, value;
4189         char *new_data;
4190         int screen_number;
4191         const char *cp;
4192         u_int32_t rnd = 0;
4193
4194         if (x11_saved_display == NULL)
4195                 x11_saved_display = xstrdup(disp);
4196         else if (strcmp(disp, x11_saved_display) != 0) {
4197                 error("x11_request_forwarding_with_spoofing: different "
4198                     "$DISPLAY already forwarded");
4199                 return;
4200         }
4201
4202         cp = strchr(disp, ':');
4203         if (cp)
4204                 cp = strchr(cp, '.');
4205         if (cp)
4206                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
4207         else
4208                 screen_number = 0;
4209
4210         if (x11_saved_proto == NULL) {
4211                 /* Save protocol name. */
4212                 x11_saved_proto = xstrdup(proto);
4213                 /*
4214                  * Extract real authentication data and generate fake data
4215                  * of the same length.
4216                  */
4217                 x11_saved_data = xmalloc(data_len);
4218                 x11_fake_data = xmalloc(data_len);
4219                 for (i = 0; i < data_len; i++) {
4220                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
4221                                 fatal("x11_request_forwarding: bad "
4222                                     "authentication data: %.100s", data);
4223                         if (i % 4 == 0)
4224                                 rnd = arc4random();
4225                         x11_saved_data[i] = value;
4226                         x11_fake_data[i] = rnd & 0xff;
4227                         rnd >>= 8;
4228                 }
4229                 x11_saved_data_len = data_len;
4230                 x11_fake_data_len = data_len;
4231         }
4232
4233         /* Convert the fake data into hex. */
4234         new_data = tohex(x11_fake_data, data_len);
4235
4236         /* Send the request packet. */
4237         if (compat20) {
4238                 channel_request_start(client_session_id, "x11-req", want_reply);
4239                 packet_put_char(0);     /* XXX bool single connection */
4240         } else {
4241                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
4242         }
4243         packet_put_cstring(proto);
4244         packet_put_cstring(new_data);
4245         packet_put_int(screen_number);
4246         packet_send();
4247         packet_write_wait();
4248         free(new_data);
4249 }
4250
4251
4252 /* -- agent forwarding */
4253
4254 /* Sends a message to the server to request authentication fd forwarding. */
4255
4256 void
4257 auth_request_forwarding(void)
4258 {
4259         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
4260         packet_send();
4261         packet_write_wait();
4262 }