- Add stge(4) for Sundance/Tamarack TC9021 Gigabit Ethernet chip.
[dragonfly.git] / crypto / openssh-4 / channels.c
1 /* $OpenBSD: channels.c,v 1.266 2006/08/29 10:40:18 djm Exp $ */
2 /*
3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5  *                    All rights reserved
6  * This file contains functions for generic socket connection forwarding.
7  * There is also code for initiating connection forwarding for X11 connections,
8  * arbitrary tcp/ip connections, and the authentication agent connection.
9  *
10  * As far as I am concerned, the code I have written for this software
11  * can be used freely for any purpose.  Any derived versions of this
12  * software must be clearly marked as such, and if the derived work is
13  * incompatible with the protocol description in the RFC file, it must be
14  * called by a name other than "ssh" or "Secure Shell".
15  *
16  * SSH2 support added by Markus Friedl.
17  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
18  * Copyright (c) 1999 Dug Song.  All rights reserved.
19  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
20  *
21  * Redistribution and use in source and binary forms, with or without
22  * modification, are permitted provided that the following conditions
23  * are met:
24  * 1. Redistributions of source code must retain the above copyright
25  *    notice, this list of conditions and the following disclaimer.
26  * 2. Redistributions in binary form must reproduce the above copyright
27  *    notice, this list of conditions and the following disclaimer in the
28  *    documentation and/or other materials provided with the distribution.
29  *
30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40  */
41
42 #include "includes.h"
43
44 #include <sys/types.h>
45 #include <sys/ioctl.h>
46 #include <sys/un.h>
47 #include <sys/socket.h>
48 #ifdef HAVE_SYS_TIME_H
49 # include <sys/time.h>
50 #endif
51
52 #include <netinet/in.h>
53 #include <arpa/inet.h>
54
55 #include <errno.h>
56 #include <netdb.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <termios.h>
61 #include <unistd.h>
62 #include <stdarg.h>
63
64 #include "xmalloc.h"
65 #include "ssh.h"
66 #include "ssh1.h"
67 #include "ssh2.h"
68 #include "packet.h"
69 #include "log.h"
70 #include "misc.h"
71 #include "buffer.h"
72 #include "channels.h"
73 #include "compat.h"
74 #include "canohost.h"
75 #include "key.h"
76 #include "authfd.h"
77 #include "pathnames.h"
78
79 /* -- channel core */
80
81 /*
82  * Pointer to an array containing all allocated channels.  The array is
83  * dynamically extended as needed.
84  */
85 static Channel **channels = NULL;
86
87 /*
88  * Size of the channel array.  All slots of the array must always be
89  * initialized (at least the type field); unused slots set to NULL
90  */
91 static u_int channels_alloc = 0;
92
93 /*
94  * Maximum file descriptor value used in any of the channels.  This is
95  * updated in channel_new.
96  */
97 static int channel_max_fd = 0;
98
99
100 /* -- tcp forwarding */
101
102 /*
103  * Data structure for storing which hosts are permitted for forward requests.
104  * The local sides of any remote forwards are stored in this array to prevent
105  * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
106  * network (which might be behind a firewall).
107  */
108 typedef struct {
109         char *host_to_connect;          /* Connect to 'host'. */
110         u_short port_to_connect;        /* Connect to 'port'. */
111         u_short listen_port;            /* Remote side should listen port number. */
112 } ForwardPermission;
113
114 /* List of all permitted host/port pairs to connect by the user. */
115 static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
116
117 /* List of all permitted host/port pairs to connect by the admin. */
118 static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
119
120 /* Number of permitted host/port pairs in the array permitted by the user. */
121 static int num_permitted_opens = 0;
122
123 /* Number of permitted host/port pair in the array permitted by the admin. */
124 static int num_adm_permitted_opens = 0;
125
126 /*
127  * If this is true, all opens are permitted.  This is the case on the server
128  * on which we have to trust the client anyway, and the user could do
129  * anything after logging in anyway.
130  */
131 static int all_opens_permitted = 0;
132
133
134 /* -- X11 forwarding */
135
136 /* Maximum number of fake X11 displays to try. */
137 #define MAX_DISPLAYS  1000
138
139 /* Saved X11 local (client) display. */
140 static char *x11_saved_display = NULL;
141
142 /* Saved X11 authentication protocol name. */
143 static char *x11_saved_proto = NULL;
144
145 /* Saved X11 authentication data.  This is the real data. */
146 static char *x11_saved_data = NULL;
147 static u_int x11_saved_data_len = 0;
148
149 /*
150  * Fake X11 authentication data.  This is what the server will be sending us;
151  * we should replace any occurrences of this by the real data.
152  */
153 static u_char *x11_fake_data = NULL;
154 static u_int x11_fake_data_len;
155
156
157 /* -- agent forwarding */
158
159 #define NUM_SOCKS       10
160
161 /* AF_UNSPEC or AF_INET or AF_INET6 */
162 static int IPv4or6 = AF_UNSPEC;
163
164 /* helper */
165 static void port_open_helper(Channel *c, char *rtype);
166
167 /* -- channel core */
168
169 Channel *
170 channel_by_id(int id)
171 {
172         Channel *c;
173
174         if (id < 0 || (u_int)id >= channels_alloc) {
175                 logit("channel_by_id: %d: bad id", id);
176                 return NULL;
177         }
178         c = channels[id];
179         if (c == NULL) {
180                 logit("channel_by_id: %d: bad id: channel free", id);
181                 return NULL;
182         }
183         return c;
184 }
185
186 /*
187  * Returns the channel if it is allowed to receive protocol messages.
188  * Private channels, like listening sockets, may not receive messages.
189  */
190 Channel *
191 channel_lookup(int id)
192 {
193         Channel *c;
194
195         if ((c = channel_by_id(id)) == NULL)
196                 return (NULL);
197
198         switch (c->type) {
199         case SSH_CHANNEL_X11_OPEN:
200         case SSH_CHANNEL_LARVAL:
201         case SSH_CHANNEL_CONNECTING:
202         case SSH_CHANNEL_DYNAMIC:
203         case SSH_CHANNEL_OPENING:
204         case SSH_CHANNEL_OPEN:
205         case SSH_CHANNEL_INPUT_DRAINING:
206         case SSH_CHANNEL_OUTPUT_DRAINING:
207                 return (c);
208         }
209         logit("Non-public channel %d, type %d.", id, c->type);
210         return (NULL);
211 }
212
213 /*
214  * Register filedescriptors for a channel, used when allocating a channel or
215  * when the channel consumer/producer is ready, e.g. shell exec'd
216  */
217 static void
218 channel_register_fds(Channel *c, int rfd, int wfd, int efd,
219     int extusage, int nonblock)
220 {
221         /* Update the maximum file descriptor value. */
222         channel_max_fd = MAX(channel_max_fd, rfd);
223         channel_max_fd = MAX(channel_max_fd, wfd);
224         channel_max_fd = MAX(channel_max_fd, efd);
225
226         /* XXX set close-on-exec -markus */
227
228         c->rfd = rfd;
229         c->wfd = wfd;
230         c->sock = (rfd == wfd) ? rfd : -1;
231         c->ctl_fd = -1; /* XXX: set elsewhere */
232         c->efd = efd;
233         c->extended_usage = extusage;
234
235         /* XXX ugly hack: nonblock is only set by the server */
236         if (nonblock && isatty(c->rfd)) {
237                 debug2("channel %d: rfd %d isatty", c->self, c->rfd);
238                 c->isatty = 1;
239                 if (!isatty(c->wfd)) {
240                         error("channel %d: wfd %d is not a tty?",
241                             c->self, c->wfd);
242                 }
243         } else {
244                 c->isatty = 0;
245         }
246         c->wfd_isatty = isatty(c->wfd);
247
248         /* enable nonblocking mode */
249         if (nonblock) {
250                 if (rfd != -1)
251                         set_nonblock(rfd);
252                 if (wfd != -1)
253                         set_nonblock(wfd);
254                 if (efd != -1)
255                         set_nonblock(efd);
256         }
257 }
258
259 /*
260  * Allocate a new channel object and set its type and socket. This will cause
261  * remote_name to be freed.
262  */
263 Channel *
264 channel_new(char *ctype, int type, int rfd, int wfd, int efd,
265     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
266 {
267         int found;
268         u_int i;
269         Channel *c;
270
271         /* Do initial allocation if this is the first call. */
272         if (channels_alloc == 0) {
273                 channels_alloc = 10;
274                 channels = xcalloc(channels_alloc, sizeof(Channel *));
275                 for (i = 0; i < channels_alloc; i++)
276                         channels[i] = NULL;
277         }
278         /* Try to find a free slot where to put the new channel. */
279         for (found = -1, i = 0; i < channels_alloc; i++)
280                 if (channels[i] == NULL) {
281                         /* Found a free slot. */
282                         found = (int)i;
283                         break;
284                 }
285         if (found < 0) {
286                 /* There are no free slots.  Take last+1 slot and expand the array.  */
287                 found = channels_alloc;
288                 if (channels_alloc > 10000)
289                         fatal("channel_new: internal error: channels_alloc %d "
290                             "too big.", channels_alloc);
291                 channels = xrealloc(channels, channels_alloc + 10,
292                     sizeof(Channel *));
293                 channels_alloc += 10;
294                 debug2("channel: expanding %d", channels_alloc);
295                 for (i = found; i < channels_alloc; i++)
296                         channels[i] = NULL;
297         }
298         /* Initialize and return new channel. */
299         c = channels[found] = xcalloc(1, sizeof(Channel));
300         buffer_init(&c->input);
301         buffer_init(&c->output);
302         buffer_init(&c->extended);
303         c->ostate = CHAN_OUTPUT_OPEN;
304         c->istate = CHAN_INPUT_OPEN;
305         c->flags = 0;
306         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
307         c->self = found;
308         c->type = type;
309         c->ctype = ctype;
310         c->local_window = window;
311         c->local_window_max = window;
312         c->local_consumed = 0;
313         c->local_maxpacket = maxpack;
314         c->remote_id = -1;
315         c->remote_name = xstrdup(remote_name);
316         c->remote_window = 0;
317         c->remote_maxpacket = 0;
318         c->force_drain = 0;
319         c->single_connection = 0;
320         c->detach_user = NULL;
321         c->detach_close = 0;
322         c->confirm = NULL;
323         c->confirm_ctx = NULL;
324         c->input_filter = NULL;
325         c->output_filter = NULL;
326         debug("channel %d: new [%s]", found, remote_name);
327         return c;
328 }
329
330 static int
331 channel_find_maxfd(void)
332 {
333         u_int i;
334         int max = 0;
335         Channel *c;
336
337         for (i = 0; i < channels_alloc; i++) {
338                 c = channels[i];
339                 if (c != NULL) {
340                         max = MAX(max, c->rfd);
341                         max = MAX(max, c->wfd);
342                         max = MAX(max, c->efd);
343                 }
344         }
345         return max;
346 }
347
348 int
349 channel_close_fd(int *fdp)
350 {
351         int ret = 0, fd = *fdp;
352
353         if (fd != -1) {
354                 ret = close(fd);
355                 *fdp = -1;
356                 if (fd == channel_max_fd)
357                         channel_max_fd = channel_find_maxfd();
358         }
359         return ret;
360 }
361
362 /* Close all channel fd/socket. */
363 static void
364 channel_close_fds(Channel *c)
365 {
366         debug3("channel %d: close_fds r %d w %d e %d c %d",
367             c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
368
369         channel_close_fd(&c->sock);
370         channel_close_fd(&c->ctl_fd);
371         channel_close_fd(&c->rfd);
372         channel_close_fd(&c->wfd);
373         channel_close_fd(&c->efd);
374 }
375
376 /* Free the channel and close its fd/socket. */
377 void
378 channel_free(Channel *c)
379 {
380         char *s;
381         u_int i, n;
382
383         for (n = 0, i = 0; i < channels_alloc; i++)
384                 if (channels[i])
385                         n++;
386         debug("channel %d: free: %s, nchannels %u", c->self,
387             c->remote_name ? c->remote_name : "???", n);
388
389         s = channel_open_message();
390         debug3("channel %d: status: %s", c->self, s);
391         xfree(s);
392
393         if (c->sock != -1)
394                 shutdown(c->sock, SHUT_RDWR);
395         if (c->ctl_fd != -1)
396                 shutdown(c->ctl_fd, SHUT_RDWR);
397         channel_close_fds(c);
398         buffer_free(&c->input);
399         buffer_free(&c->output);
400         buffer_free(&c->extended);
401         if (c->remote_name) {
402                 xfree(c->remote_name);
403                 c->remote_name = NULL;
404         }
405         channels[c->self] = NULL;
406         xfree(c);
407 }
408
409 void
410 channel_free_all(void)
411 {
412         u_int i;
413
414         for (i = 0; i < channels_alloc; i++)
415                 if (channels[i] != NULL)
416                         channel_free(channels[i]);
417 }
418
419 /*
420  * Closes the sockets/fds of all channels.  This is used to close extra file
421  * descriptors after a fork.
422  */
423 void
424 channel_close_all(void)
425 {
426         u_int i;
427
428         for (i = 0; i < channels_alloc; i++)
429                 if (channels[i] != NULL)
430                         channel_close_fds(channels[i]);
431 }
432
433 /*
434  * Stop listening to channels.
435  */
436 void
437 channel_stop_listening(void)
438 {
439         u_int i;
440         Channel *c;
441
442         for (i = 0; i < channels_alloc; i++) {
443                 c = channels[i];
444                 if (c != NULL) {
445                         switch (c->type) {
446                         case SSH_CHANNEL_AUTH_SOCKET:
447                         case SSH_CHANNEL_PORT_LISTENER:
448                         case SSH_CHANNEL_RPORT_LISTENER:
449                         case SSH_CHANNEL_X11_LISTENER:
450                                 channel_close_fd(&c->sock);
451                                 channel_free(c);
452                                 break;
453                         }
454                 }
455         }
456 }
457
458 /*
459  * Returns true if no channel has too much buffered data, and false if one or
460  * more channel is overfull.
461  */
462 int
463 channel_not_very_much_buffered_data(void)
464 {
465         u_int i;
466         Channel *c;
467
468         for (i = 0; i < channels_alloc; i++) {
469                 c = channels[i];
470                 if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
471 #if 0
472                         if (!compat20 &&
473                             buffer_len(&c->input) > packet_get_maxsize()) {
474                                 debug2("channel %d: big input buffer %d",
475                                     c->self, buffer_len(&c->input));
476                                 return 0;
477                         }
478 #endif
479                         if (buffer_len(&c->output) > packet_get_maxsize()) {
480                                 debug2("channel %d: big output buffer %u > %u",
481                                     c->self, buffer_len(&c->output),
482                                     packet_get_maxsize());
483                                 return 0;
484                         }
485                 }
486         }
487         return 1;
488 }
489
490 /* Returns true if any channel is still open. */
491 int
492 channel_still_open(void)
493 {
494         u_int i;
495         Channel *c;
496
497         for (i = 0; i < channels_alloc; i++) {
498                 c = channels[i];
499                 if (c == NULL)
500                         continue;
501                 switch (c->type) {
502                 case SSH_CHANNEL_X11_LISTENER:
503                 case SSH_CHANNEL_PORT_LISTENER:
504                 case SSH_CHANNEL_RPORT_LISTENER:
505                 case SSH_CHANNEL_CLOSED:
506                 case SSH_CHANNEL_AUTH_SOCKET:
507                 case SSH_CHANNEL_DYNAMIC:
508                 case SSH_CHANNEL_CONNECTING:
509                 case SSH_CHANNEL_ZOMBIE:
510                         continue;
511                 case SSH_CHANNEL_LARVAL:
512                         if (!compat20)
513                                 fatal("cannot happen: SSH_CHANNEL_LARVAL");
514                         continue;
515                 case SSH_CHANNEL_OPENING:
516                 case SSH_CHANNEL_OPEN:
517                 case SSH_CHANNEL_X11_OPEN:
518                         return 1;
519                 case SSH_CHANNEL_INPUT_DRAINING:
520                 case SSH_CHANNEL_OUTPUT_DRAINING:
521                         if (!compat13)
522                                 fatal("cannot happen: OUT_DRAIN");
523                         return 1;
524                 default:
525                         fatal("channel_still_open: bad channel type %d", c->type);
526                         /* NOTREACHED */
527                 }
528         }
529         return 0;
530 }
531
532 /* Returns the id of an open channel suitable for keepaliving */
533 int
534 channel_find_open(void)
535 {
536         u_int i;
537         Channel *c;
538
539         for (i = 0; i < channels_alloc; i++) {
540                 c = channels[i];
541                 if (c == NULL || c->remote_id < 0)
542                         continue;
543                 switch (c->type) {
544                 case SSH_CHANNEL_CLOSED:
545                 case SSH_CHANNEL_DYNAMIC:
546                 case SSH_CHANNEL_X11_LISTENER:
547                 case SSH_CHANNEL_PORT_LISTENER:
548                 case SSH_CHANNEL_RPORT_LISTENER:
549                 case SSH_CHANNEL_OPENING:
550                 case SSH_CHANNEL_CONNECTING:
551                 case SSH_CHANNEL_ZOMBIE:
552                         continue;
553                 case SSH_CHANNEL_LARVAL:
554                 case SSH_CHANNEL_AUTH_SOCKET:
555                 case SSH_CHANNEL_OPEN:
556                 case SSH_CHANNEL_X11_OPEN:
557                         return i;
558                 case SSH_CHANNEL_INPUT_DRAINING:
559                 case SSH_CHANNEL_OUTPUT_DRAINING:
560                         if (!compat13)
561                                 fatal("cannot happen: OUT_DRAIN");
562                         return i;
563                 default:
564                         fatal("channel_find_open: bad channel type %d", c->type);
565                         /* NOTREACHED */
566                 }
567         }
568         return -1;
569 }
570
571
572 /*
573  * Returns a message describing the currently open forwarded connections,
574  * suitable for sending to the client.  The message contains crlf pairs for
575  * newlines.
576  */
577 char *
578 channel_open_message(void)
579 {
580         Buffer buffer;
581         Channel *c;
582         char buf[1024], *cp;
583         u_int i;
584
585         buffer_init(&buffer);
586         snprintf(buf, sizeof buf, "The following connections are open:\r\n");
587         buffer_append(&buffer, buf, strlen(buf));
588         for (i = 0; i < channels_alloc; i++) {
589                 c = channels[i];
590                 if (c == NULL)
591                         continue;
592                 switch (c->type) {
593                 case SSH_CHANNEL_X11_LISTENER:
594                 case SSH_CHANNEL_PORT_LISTENER:
595                 case SSH_CHANNEL_RPORT_LISTENER:
596                 case SSH_CHANNEL_CLOSED:
597                 case SSH_CHANNEL_AUTH_SOCKET:
598                 case SSH_CHANNEL_ZOMBIE:
599                         continue;
600                 case SSH_CHANNEL_LARVAL:
601                 case SSH_CHANNEL_OPENING:
602                 case SSH_CHANNEL_CONNECTING:
603                 case SSH_CHANNEL_DYNAMIC:
604                 case SSH_CHANNEL_OPEN:
605                 case SSH_CHANNEL_X11_OPEN:
606                 case SSH_CHANNEL_INPUT_DRAINING:
607                 case SSH_CHANNEL_OUTPUT_DRAINING:
608                         snprintf(buf, sizeof buf,
609                             "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n",
610                             c->self, c->remote_name,
611                             c->type, c->remote_id,
612                             c->istate, buffer_len(&c->input),
613                             c->ostate, buffer_len(&c->output),
614                             c->rfd, c->wfd, c->ctl_fd);
615                         buffer_append(&buffer, buf, strlen(buf));
616                         continue;
617                 default:
618                         fatal("channel_open_message: bad channel type %d", c->type);
619                         /* NOTREACHED */
620                 }
621         }
622         buffer_append(&buffer, "\0", 1);
623         cp = xstrdup(buffer_ptr(&buffer));
624         buffer_free(&buffer);
625         return cp;
626 }
627
628 void
629 channel_send_open(int id)
630 {
631         Channel *c = channel_lookup(id);
632
633         if (c == NULL) {
634                 logit("channel_send_open: %d: bad id", id);
635                 return;
636         }
637         debug2("channel %d: send open", id);
638         packet_start(SSH2_MSG_CHANNEL_OPEN);
639         packet_put_cstring(c->ctype);
640         packet_put_int(c->self);
641         packet_put_int(c->local_window);
642         packet_put_int(c->local_maxpacket);
643         packet_send();
644 }
645
646 void
647 channel_request_start(int id, char *service, int wantconfirm)
648 {
649         Channel *c = channel_lookup(id);
650
651         if (c == NULL) {
652                 logit("channel_request_start: %d: unknown channel id", id);
653                 return;
654         }
655         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
656         packet_start(SSH2_MSG_CHANNEL_REQUEST);
657         packet_put_int(c->remote_id);
658         packet_put_cstring(service);
659         packet_put_char(wantconfirm);
660 }
661
662 void
663 channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
664 {
665         Channel *c = channel_lookup(id);
666
667         if (c == NULL) {
668                 logit("channel_register_comfirm: %d: bad id", id);
669                 return;
670         }
671         c->confirm = fn;
672         c->confirm_ctx = ctx;
673 }
674
675 void
676 channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
677 {
678         Channel *c = channel_by_id(id);
679
680         if (c == NULL) {
681                 logit("channel_register_cleanup: %d: bad id", id);
682                 return;
683         }
684         c->detach_user = fn;
685         c->detach_close = do_close;
686 }
687
688 void
689 channel_cancel_cleanup(int id)
690 {
691         Channel *c = channel_by_id(id);
692
693         if (c == NULL) {
694                 logit("channel_cancel_cleanup: %d: bad id", id);
695                 return;
696         }
697         c->detach_user = NULL;
698         c->detach_close = 0;
699 }
700
701 void
702 channel_register_filter(int id, channel_infilter_fn *ifn,
703     channel_outfilter_fn *ofn)
704 {
705         Channel *c = channel_lookup(id);
706
707         if (c == NULL) {
708                 logit("channel_register_filter: %d: bad id", id);
709                 return;
710         }
711         c->input_filter = ifn;
712         c->output_filter = ofn;
713 }
714
715 void
716 channel_set_fds(int id, int rfd, int wfd, int efd,
717     int extusage, int nonblock, u_int window_max)
718 {
719         Channel *c = channel_lookup(id);
720
721         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
722                 fatal("channel_activate for non-larval channel %d.", id);
723         channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
724         c->type = SSH_CHANNEL_OPEN;
725         c->local_window = c->local_window_max = window_max;
726         packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
727         packet_put_int(c->remote_id);
728         packet_put_int(c->local_window);
729         packet_send();
730 }
731
732 /*
733  * 'channel_pre*' are called just before select() to add any bits relevant to
734  * channels in the select bitmasks.
735  */
736 /*
737  * 'channel_post*': perform any appropriate operations for channels which
738  * have events pending.
739  */
740 typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
741 chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
742 chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
743
744 /* ARGSUSED */
745 static void
746 channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
747 {
748         FD_SET(c->sock, readset);
749 }
750
751 /* ARGSUSED */
752 static void
753 channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
754 {
755         debug3("channel %d: waiting for connection", c->self);
756         FD_SET(c->sock, writeset);
757 }
758
759 static void
760 channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
761 {
762         if (buffer_len(&c->input) < packet_get_maxsize())
763                 FD_SET(c->sock, readset);
764         if (buffer_len(&c->output) > 0)
765                 FD_SET(c->sock, writeset);
766 }
767
768 static void
769 channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
770 {
771         u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
772
773         if (c->istate == CHAN_INPUT_OPEN &&
774             limit > 0 &&
775             buffer_len(&c->input) < limit &&
776             buffer_check_alloc(&c->input, CHAN_RBUF))
777                 FD_SET(c->rfd, readset);
778         if (c->ostate == CHAN_OUTPUT_OPEN ||
779             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
780                 if (buffer_len(&c->output) > 0) {
781                         FD_SET(c->wfd, writeset);
782                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
783                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
784                                 debug2("channel %d: obuf_empty delayed efd %d/(%d)",
785                                     c->self, c->efd, buffer_len(&c->extended));
786                         else
787                                 chan_obuf_empty(c);
788                 }
789         }
790         /** XXX check close conditions, too */
791         if (compat20 && c->efd != -1) {
792                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
793                     buffer_len(&c->extended) > 0)
794                         FD_SET(c->efd, writeset);
795                 else if (!(c->flags & CHAN_EOF_SENT) &&
796                     c->extended_usage == CHAN_EXTENDED_READ &&
797                     buffer_len(&c->extended) < c->remote_window)
798                         FD_SET(c->efd, readset);
799         }
800         /* XXX: What about efd? races? */
801         if (compat20 && c->ctl_fd != -1 &&
802             c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
803                 FD_SET(c->ctl_fd, readset);
804 }
805
806 /* ARGSUSED */
807 static void
808 channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
809 {
810         if (buffer_len(&c->input) == 0) {
811                 packet_start(SSH_MSG_CHANNEL_CLOSE);
812                 packet_put_int(c->remote_id);
813                 packet_send();
814                 c->type = SSH_CHANNEL_CLOSED;
815                 debug2("channel %d: closing after input drain.", c->self);
816         }
817 }
818
819 /* ARGSUSED */
820 static void
821 channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
822 {
823         if (buffer_len(&c->output) == 0)
824                 chan_mark_dead(c);
825         else
826                 FD_SET(c->sock, writeset);
827 }
828
829 /*
830  * This is a special state for X11 authentication spoofing.  An opened X11
831  * connection (when authentication spoofing is being done) remains in this
832  * state until the first packet has been completely read.  The authentication
833  * data in that packet is then substituted by the real data if it matches the
834  * fake data, and the channel is put into normal mode.
835  * XXX All this happens at the client side.
836  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
837  */
838 static int
839 x11_open_helper(Buffer *b)
840 {
841         u_char *ucp;
842         u_int proto_len, data_len;
843
844         /* Check if the fixed size part of the packet is in buffer. */
845         if (buffer_len(b) < 12)
846                 return 0;
847
848         /* Parse the lengths of variable-length fields. */
849         ucp = buffer_ptr(b);
850         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
851                 proto_len = 256 * ucp[6] + ucp[7];
852                 data_len = 256 * ucp[8] + ucp[9];
853         } else if (ucp[0] == 0x6c) {    /* Byte order LSB first. */
854                 proto_len = ucp[6] + 256 * ucp[7];
855                 data_len = ucp[8] + 256 * ucp[9];
856         } else {
857                 debug2("Initial X11 packet contains bad byte order byte: 0x%x",
858                     ucp[0]);
859                 return -1;
860         }
861
862         /* Check if the whole packet is in buffer. */
863         if (buffer_len(b) <
864             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
865                 return 0;
866
867         /* Check if authentication protocol matches. */
868         if (proto_len != strlen(x11_saved_proto) ||
869             memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
870                 debug2("X11 connection uses different authentication protocol.");
871                 return -1;
872         }
873         /* Check if authentication data matches our fake data. */
874         if (data_len != x11_fake_data_len ||
875             memcmp(ucp + 12 + ((proto_len + 3) & ~3),
876                 x11_fake_data, x11_fake_data_len) != 0) {
877                 debug2("X11 auth data does not match fake data.");
878                 return -1;
879         }
880         /* Check fake data length */
881         if (x11_fake_data_len != x11_saved_data_len) {
882                 error("X11 fake_data_len %d != saved_data_len %d",
883                     x11_fake_data_len, x11_saved_data_len);
884                 return -1;
885         }
886         /*
887          * Received authentication protocol and data match
888          * our fake data. Substitute the fake data with real
889          * data.
890          */
891         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
892             x11_saved_data, x11_saved_data_len);
893         return 1;
894 }
895
896 static void
897 channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
898 {
899         int ret = x11_open_helper(&c->output);
900
901         if (ret == 1) {
902                 /* Start normal processing for the channel. */
903                 c->type = SSH_CHANNEL_OPEN;
904                 channel_pre_open_13(c, readset, writeset);
905         } else if (ret == -1) {
906                 /*
907                  * We have received an X11 connection that has bad
908                  * authentication information.
909                  */
910                 logit("X11 connection rejected because of wrong authentication.");
911                 buffer_clear(&c->input);
912                 buffer_clear(&c->output);
913                 channel_close_fd(&c->sock);
914                 c->sock = -1;
915                 c->type = SSH_CHANNEL_CLOSED;
916                 packet_start(SSH_MSG_CHANNEL_CLOSE);
917                 packet_put_int(c->remote_id);
918                 packet_send();
919         }
920 }
921
922 static void
923 channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
924 {
925         int ret = x11_open_helper(&c->output);
926
927         /* c->force_drain = 1; */
928
929         if (ret == 1) {
930                 c->type = SSH_CHANNEL_OPEN;
931                 channel_pre_open(c, readset, writeset);
932         } else if (ret == -1) {
933                 logit("X11 connection rejected because of wrong authentication.");
934                 debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
935                 chan_read_failed(c);
936                 buffer_clear(&c->input);
937                 chan_ibuf_empty(c);
938                 buffer_clear(&c->output);
939                 /* for proto v1, the peer will send an IEOF */
940                 if (compat20)
941                         chan_write_failed(c);
942                 else
943                         c->type = SSH_CHANNEL_OPEN;
944                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
945         }
946 }
947
948 /* try to decode a socks4 header */
949 /* ARGSUSED */
950 static int
951 channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
952 {
953         char *p, *host;
954         u_int len, have, i, found;
955         char username[256];
956         struct {
957                 u_int8_t version;
958                 u_int8_t command;
959                 u_int16_t dest_port;
960                 struct in_addr dest_addr;
961         } s4_req, s4_rsp;
962
963         debug2("channel %d: decode socks4", c->self);
964
965         have = buffer_len(&c->input);
966         len = sizeof(s4_req);
967         if (have < len)
968                 return 0;
969         p = buffer_ptr(&c->input);
970         for (found = 0, i = len; i < have; i++) {
971                 if (p[i] == '\0') {
972                         found = 1;
973                         break;
974                 }
975                 if (i > 1024) {
976                         /* the peer is probably sending garbage */
977                         debug("channel %d: decode socks4: too long",
978                             c->self);
979                         return -1;
980                 }
981         }
982         if (!found)
983                 return 0;
984         buffer_get(&c->input, (char *)&s4_req.version, 1);
985         buffer_get(&c->input, (char *)&s4_req.command, 1);
986         buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
987         buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
988         have = buffer_len(&c->input);
989         p = buffer_ptr(&c->input);
990         len = strlen(p);
991         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
992         if (len > have)
993                 fatal("channel %d: decode socks4: len %d > have %d",
994                     c->self, len, have);
995         strlcpy(username, p, sizeof(username));
996         buffer_consume(&c->input, len);
997         buffer_consume(&c->input, 1);           /* trailing '\0' */
998
999         host = inet_ntoa(s4_req.dest_addr);
1000         strlcpy(c->path, host, sizeof(c->path));
1001         c->host_port = ntohs(s4_req.dest_port);
1002
1003         debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
1004             c->self, host, c->host_port, s4_req.command);
1005
1006         if (s4_req.command != 1) {
1007                 debug("channel %d: cannot handle: socks4 cn %d",
1008                     c->self, s4_req.command);
1009                 return -1;
1010         }
1011         s4_rsp.version = 0;                     /* vn: 0 for reply */
1012         s4_rsp.command = 90;                    /* cd: req granted */
1013         s4_rsp.dest_port = 0;                   /* ignored */
1014         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
1015         buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
1016         return 1;
1017 }
1018
1019 /* try to decode a socks5 header */
1020 #define SSH_SOCKS5_AUTHDONE     0x1000
1021 #define SSH_SOCKS5_NOAUTH       0x00
1022 #define SSH_SOCKS5_IPV4         0x01
1023 #define SSH_SOCKS5_DOMAIN       0x03
1024 #define SSH_SOCKS5_IPV6         0x04
1025 #define SSH_SOCKS5_CONNECT      0x01
1026 #define SSH_SOCKS5_SUCCESS      0x00
1027
1028 /* ARGSUSED */
1029 static int
1030 channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
1031 {
1032         struct {
1033                 u_int8_t version;
1034                 u_int8_t command;
1035                 u_int8_t reserved;
1036                 u_int8_t atyp;
1037         } s5_req, s5_rsp;
1038         u_int16_t dest_port;
1039         u_char *p, dest_addr[255+1];
1040         u_int have, need, i, found, nmethods, addrlen, af;
1041
1042         debug2("channel %d: decode socks5", c->self);
1043         p = buffer_ptr(&c->input);
1044         if (p[0] != 0x05)
1045                 return -1;
1046         have = buffer_len(&c->input);
1047         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
1048                 /* format: ver | nmethods | methods */
1049                 if (have < 2)
1050                         return 0;
1051                 nmethods = p[1];
1052                 if (have < nmethods + 2)
1053                         return 0;
1054                 /* look for method: "NO AUTHENTICATION REQUIRED" */
1055                 for (found = 0, i = 2 ; i < nmethods + 2; i++) {
1056                         if (p[i] == SSH_SOCKS5_NOAUTH) {
1057                                 found = 1;
1058                                 break;
1059                         }
1060                 }
1061                 if (!found) {
1062                         debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
1063                             c->self);
1064                         return -1;
1065                 }
1066                 buffer_consume(&c->input, nmethods + 2);
1067                 buffer_put_char(&c->output, 0x05);              /* version */
1068                 buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
1069                 FD_SET(c->sock, writeset);
1070                 c->flags |= SSH_SOCKS5_AUTHDONE;
1071                 debug2("channel %d: socks5 auth done", c->self);
1072                 return 0;                               /* need more */
1073         }
1074         debug2("channel %d: socks5 post auth", c->self);
1075         if (have < sizeof(s5_req)+1)
1076                 return 0;                       /* need more */
1077         memcpy(&s5_req, p, sizeof(s5_req));
1078         if (s5_req.version != 0x05 ||
1079             s5_req.command != SSH_SOCKS5_CONNECT ||
1080             s5_req.reserved != 0x00) {
1081                 debug2("channel %d: only socks5 connect supported", c->self);
1082                 return -1;
1083         }
1084         switch (s5_req.atyp){
1085         case SSH_SOCKS5_IPV4:
1086                 addrlen = 4;
1087                 af = AF_INET;
1088                 break;
1089         case SSH_SOCKS5_DOMAIN:
1090                 addrlen = p[sizeof(s5_req)];
1091                 af = -1;
1092                 break;
1093         case SSH_SOCKS5_IPV6:
1094                 addrlen = 16;
1095                 af = AF_INET6;
1096                 break;
1097         default:
1098                 debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
1099                 return -1;
1100         }
1101         need = sizeof(s5_req) + addrlen + 2;
1102         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1103                 need++;
1104         if (have < need)
1105                 return 0;
1106         buffer_consume(&c->input, sizeof(s5_req));
1107         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1108                 buffer_consume(&c->input, 1);    /* host string length */
1109         buffer_get(&c->input, (char *)&dest_addr, addrlen);
1110         buffer_get(&c->input, (char *)&dest_port, 2);
1111         dest_addr[addrlen] = '\0';
1112         if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
1113                 strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
1114         else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
1115                 return -1;
1116         c->host_port = ntohs(dest_port);
1117
1118         debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
1119             c->self, c->path, c->host_port, s5_req.command);
1120
1121         s5_rsp.version = 0x05;
1122         s5_rsp.command = SSH_SOCKS5_SUCCESS;
1123         s5_rsp.reserved = 0;                    /* ignored */
1124         s5_rsp.atyp = SSH_SOCKS5_IPV4;
1125         ((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
1126         dest_port = 0;                          /* ignored */
1127
1128         buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
1129         buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
1130         buffer_append(&c->output, &dest_port, sizeof(dest_port));
1131         return 1;
1132 }
1133
1134 /* dynamic port forwarding */
1135 static void
1136 channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
1137 {
1138         u_char *p;
1139         u_int have;
1140         int ret;
1141
1142         have = buffer_len(&c->input);
1143         c->delayed = 0;
1144         debug2("channel %d: pre_dynamic: have %d", c->self, have);
1145         /* buffer_dump(&c->input); */
1146         /* check if the fixed size part of the packet is in buffer. */
1147         if (have < 3) {
1148                 /* need more */
1149                 FD_SET(c->sock, readset);
1150                 return;
1151         }
1152         /* try to guess the protocol */
1153         p = buffer_ptr(&c->input);
1154         switch (p[0]) {
1155         case 0x04:
1156                 ret = channel_decode_socks4(c, readset, writeset);
1157                 break;
1158         case 0x05:
1159                 ret = channel_decode_socks5(c, readset, writeset);
1160                 break;
1161         default:
1162                 ret = -1;
1163                 break;
1164         }
1165         if (ret < 0) {
1166                 chan_mark_dead(c);
1167         } else if (ret == 0) {
1168                 debug2("channel %d: pre_dynamic: need more", c->self);
1169                 /* need more */
1170                 FD_SET(c->sock, readset);
1171         } else {
1172                 /* switch to the next state */
1173                 c->type = SSH_CHANNEL_OPENING;
1174                 port_open_helper(c, "direct-tcpip");
1175         }
1176 }
1177
1178 /* This is our fake X11 server socket. */
1179 /* ARGSUSED */
1180 static void
1181 channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
1182 {
1183         Channel *nc;
1184         struct sockaddr addr;
1185         int newsock;
1186         socklen_t addrlen;
1187         char buf[16384], *remote_ipaddr;
1188         int remote_port;
1189
1190         if (FD_ISSET(c->sock, readset)) {
1191                 debug("X11 connection requested.");
1192                 addrlen = sizeof(addr);
1193                 newsock = accept(c->sock, &addr, &addrlen);
1194                 if (c->single_connection) {
1195                         debug2("single_connection: closing X11 listener.");
1196                         channel_close_fd(&c->sock);
1197                         chan_mark_dead(c);
1198                 }
1199                 if (newsock < 0) {
1200                         error("accept: %.100s", strerror(errno));
1201                         return;
1202                 }
1203                 set_nodelay(newsock);
1204                 remote_ipaddr = get_peer_ipaddr(newsock);
1205                 remote_port = get_peer_port(newsock);
1206                 snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
1207                     remote_ipaddr, remote_port);
1208
1209                 nc = channel_new("accepted x11 socket",
1210                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1211                     c->local_window_max, c->local_maxpacket, 0, buf, 1);
1212                 if (compat20) {
1213                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1214                         packet_put_cstring("x11");
1215                         packet_put_int(nc->self);
1216                         packet_put_int(nc->local_window_max);
1217                         packet_put_int(nc->local_maxpacket);
1218                         /* originator ipaddr and port */
1219                         packet_put_cstring(remote_ipaddr);
1220                         if (datafellows & SSH_BUG_X11FWD) {
1221                                 debug2("ssh2 x11 bug compat mode");
1222                         } else {
1223                                 packet_put_int(remote_port);
1224                         }
1225                         packet_send();
1226                 } else {
1227                         packet_start(SSH_SMSG_X11_OPEN);
1228                         packet_put_int(nc->self);
1229                         if (packet_get_protocol_flags() &
1230                             SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1231                                 packet_put_cstring(buf);
1232                         packet_send();
1233                 }
1234                 xfree(remote_ipaddr);
1235         }
1236 }
1237
1238 static void
1239 port_open_helper(Channel *c, char *rtype)
1240 {
1241         int direct;
1242         char buf[1024];
1243         char *remote_ipaddr = get_peer_ipaddr(c->sock);
1244         int remote_port = get_peer_port(c->sock);
1245
1246         direct = (strcmp(rtype, "direct-tcpip") == 0);
1247
1248         snprintf(buf, sizeof buf,
1249             "%s: listening port %d for %.100s port %d, "
1250             "connect from %.200s port %d",
1251             rtype, c->listening_port, c->path, c->host_port,
1252             remote_ipaddr, remote_port);
1253
1254         xfree(c->remote_name);
1255         c->remote_name = xstrdup(buf);
1256
1257         if (compat20) {
1258                 packet_start(SSH2_MSG_CHANNEL_OPEN);
1259                 packet_put_cstring(rtype);
1260                 packet_put_int(c->self);
1261                 packet_put_int(c->local_window_max);
1262                 packet_put_int(c->local_maxpacket);
1263                 if (direct) {
1264                         /* target host, port */
1265                         packet_put_cstring(c->path);
1266                         packet_put_int(c->host_port);
1267                 } else {
1268                         /* listen address, port */
1269                         packet_put_cstring(c->path);
1270                         packet_put_int(c->listening_port);
1271                 }
1272                 /* originator host and port */
1273                 packet_put_cstring(remote_ipaddr);
1274                 packet_put_int((u_int)remote_port);
1275                 packet_send();
1276         } else {
1277                 packet_start(SSH_MSG_PORT_OPEN);
1278                 packet_put_int(c->self);
1279                 packet_put_cstring(c->path);
1280                 packet_put_int(c->host_port);
1281                 if (packet_get_protocol_flags() &
1282                     SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
1283                         packet_put_cstring(c->remote_name);
1284                 packet_send();
1285         }
1286         xfree(remote_ipaddr);
1287 }
1288
1289 static void
1290 channel_set_reuseaddr(int fd)
1291 {
1292         int on = 1;
1293
1294         /*
1295          * Set socket options.
1296          * Allow local port reuse in TIME_WAIT.
1297          */
1298         if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
1299                 error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
1300 }
1301
1302 /*
1303  * This socket is listening for connections to a forwarded TCP/IP port.
1304  */
1305 /* ARGSUSED */
1306 static void
1307 channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
1308 {
1309         Channel *nc;
1310         struct sockaddr addr;
1311         int newsock, nextstate;
1312         socklen_t addrlen;
1313         char *rtype;
1314
1315         if (FD_ISSET(c->sock, readset)) {
1316                 debug("Connection to port %d forwarding "
1317                     "to %.100s port %d requested.",
1318                     c->listening_port, c->path, c->host_port);
1319
1320                 if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
1321                         nextstate = SSH_CHANNEL_OPENING;
1322                         rtype = "forwarded-tcpip";
1323                 } else {
1324                         if (c->host_port == 0) {
1325                                 nextstate = SSH_CHANNEL_DYNAMIC;
1326                                 rtype = "dynamic-tcpip";
1327                         } else {
1328                                 nextstate = SSH_CHANNEL_OPENING;
1329                                 rtype = "direct-tcpip";
1330                         }
1331                 }
1332
1333                 addrlen = sizeof(addr);
1334                 newsock = accept(c->sock, &addr, &addrlen);
1335                 if (newsock < 0) {
1336                         error("accept: %.100s", strerror(errno));
1337                         return;
1338                 }
1339                 set_nodelay(newsock);
1340                 nc = channel_new(rtype, nextstate, newsock, newsock, -1,
1341                     c->local_window_max, c->local_maxpacket, 0, rtype, 1);
1342                 nc->listening_port = c->listening_port;
1343                 nc->host_port = c->host_port;
1344                 strlcpy(nc->path, c->path, sizeof(nc->path));
1345
1346                 if (nextstate == SSH_CHANNEL_DYNAMIC) {
1347                         /*
1348                          * do not call the channel_post handler until
1349                          * this flag has been reset by a pre-handler.
1350                          * otherwise the FD_ISSET calls might overflow
1351                          */
1352                         nc->delayed = 1;
1353                 } else {
1354                         port_open_helper(nc, rtype);
1355                 }
1356         }
1357 }
1358
1359 /*
1360  * This is the authentication agent socket listening for connections from
1361  * clients.
1362  */
1363 /* ARGSUSED */
1364 static void
1365 channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
1366 {
1367         Channel *nc;
1368         int newsock;
1369         struct sockaddr addr;
1370         socklen_t addrlen;
1371
1372         if (FD_ISSET(c->sock, readset)) {
1373                 addrlen = sizeof(addr);
1374                 newsock = accept(c->sock, &addr, &addrlen);
1375                 if (newsock < 0) {
1376                         error("accept from auth socket: %.100s", strerror(errno));
1377                         return;
1378                 }
1379                 nc = channel_new("accepted auth socket",
1380                     SSH_CHANNEL_OPENING, newsock, newsock, -1,
1381                     c->local_window_max, c->local_maxpacket,
1382                     0, "accepted auth socket", 1);
1383                 if (compat20) {
1384                         packet_start(SSH2_MSG_CHANNEL_OPEN);
1385                         packet_put_cstring("auth-agent@openssh.com");
1386                         packet_put_int(nc->self);
1387                         packet_put_int(c->local_window_max);
1388                         packet_put_int(c->local_maxpacket);
1389                 } else {
1390                         packet_start(SSH_SMSG_AGENT_OPEN);
1391                         packet_put_int(nc->self);
1392                 }
1393                 packet_send();
1394         }
1395 }
1396
1397 /* ARGSUSED */
1398 static void
1399 channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
1400 {
1401         int err = 0;
1402         socklen_t sz = sizeof(err);
1403
1404         if (FD_ISSET(c->sock, writeset)) {
1405                 if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
1406                         err = errno;
1407                         error("getsockopt SO_ERROR failed");
1408                 }
1409                 if (err == 0) {
1410                         debug("channel %d: connected", c->self);
1411                         c->type = SSH_CHANNEL_OPEN;
1412                         if (compat20) {
1413                                 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1414                                 packet_put_int(c->remote_id);
1415                                 packet_put_int(c->self);
1416                                 packet_put_int(c->local_window);
1417                                 packet_put_int(c->local_maxpacket);
1418                         } else {
1419                                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1420                                 packet_put_int(c->remote_id);
1421                                 packet_put_int(c->self);
1422                         }
1423                 } else {
1424                         debug("channel %d: not connected: %s",
1425                             c->self, strerror(err));
1426                         if (compat20) {
1427                                 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1428                                 packet_put_int(c->remote_id);
1429                                 packet_put_int(SSH2_OPEN_CONNECT_FAILED);
1430                                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1431                                         packet_put_cstring(strerror(err));
1432                                         packet_put_cstring("");
1433                                 }
1434                         } else {
1435                                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1436                                 packet_put_int(c->remote_id);
1437                         }
1438                         chan_mark_dead(c);
1439                 }
1440                 packet_send();
1441         }
1442 }
1443
1444 /* ARGSUSED */
1445 static int
1446 channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
1447 {
1448         char buf[CHAN_RBUF];
1449         int len;
1450
1451         if (c->rfd != -1 &&
1452             FD_ISSET(c->rfd, readset)) {
1453                 errno = 0;
1454                 len = read(c->rfd, buf, sizeof(buf));
1455                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1456                         return 1;
1457 #ifndef PTY_ZEROREAD
1458                 if (len <= 0) {
1459 #else
1460                 if ((!c->isatty && len <= 0) ||
1461                     (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
1462 #endif
1463                         debug2("channel %d: read<=0 rfd %d len %d",
1464                             c->self, c->rfd, len);
1465                         if (c->type != SSH_CHANNEL_OPEN) {
1466                                 debug2("channel %d: not open", c->self);
1467                                 chan_mark_dead(c);
1468                                 return -1;
1469                         } else if (compat13) {
1470                                 buffer_clear(&c->output);
1471                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1472                                 debug2("channel %d: input draining.", c->self);
1473                         } else {
1474                                 chan_read_failed(c);
1475                         }
1476                         return -1;
1477                 }
1478                 if (c->input_filter != NULL) {
1479                         if (c->input_filter(c, buf, len) == -1) {
1480                                 debug2("channel %d: filter stops", c->self);
1481                                 chan_read_failed(c);
1482                         }
1483                 } else if (c->datagram) {
1484                         buffer_put_string(&c->input, buf, len);
1485                 } else {
1486                         buffer_append(&c->input, buf, len);
1487                 }
1488         }
1489         return 1;
1490 }
1491
1492 /* ARGSUSED */
1493 static int
1494 channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
1495 {
1496         struct termios tio;
1497         u_char *data = NULL, *buf;
1498         u_int dlen;
1499         int len;
1500
1501         /* Send buffered output data to the socket. */
1502         if (c->wfd != -1 &&
1503             FD_ISSET(c->wfd, writeset) &&
1504             buffer_len(&c->output) > 0) {
1505                 if (c->output_filter != NULL) {
1506                         if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
1507                                 debug2("channel %d: filter stops", c->self);
1508                                 if (c->type != SSH_CHANNEL_OPEN)
1509                                         chan_mark_dead(c);
1510                                 else
1511                                         chan_write_failed(c);
1512                                 return -1;
1513                         }
1514                 } else if (c->datagram) {
1515                         buf = data = buffer_get_string(&c->output, &dlen);
1516                 } else {
1517                         buf = data = buffer_ptr(&c->output);
1518                         dlen = buffer_len(&c->output);
1519                 }
1520
1521                 if (c->datagram) {
1522                         /* ignore truncated writes, datagrams might get lost */
1523                         c->local_consumed += dlen + 4;
1524                         len = write(c->wfd, buf, dlen);
1525                         xfree(data);
1526                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1527                                 return 1;
1528                         if (len <= 0) {
1529                                 if (c->type != SSH_CHANNEL_OPEN)
1530                                         chan_mark_dead(c);
1531                                 else
1532                                         chan_write_failed(c);
1533                                 return -1;
1534                         }
1535                         return 1;
1536                 }
1537 #ifdef _AIX
1538                 /* XXX: Later AIX versions can't push as much data to tty */
1539                 if (compat20 && c->wfd_isatty)
1540                         dlen = MIN(dlen, 8*1024);
1541 #endif
1542
1543                 len = write(c->wfd, buf, dlen);
1544                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1545                         return 1;
1546                 if (len <= 0) {
1547                         if (c->type != SSH_CHANNEL_OPEN) {
1548                                 debug2("channel %d: not open", c->self);
1549                                 chan_mark_dead(c);
1550                                 return -1;
1551                         } else if (compat13) {
1552                                 buffer_clear(&c->output);
1553                                 debug2("channel %d: input draining.", c->self);
1554                                 c->type = SSH_CHANNEL_INPUT_DRAINING;
1555                         } else {
1556                                 chan_write_failed(c);
1557                         }
1558                         return -1;
1559                 }
1560                 if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
1561                         if (tcgetattr(c->wfd, &tio) == 0 &&
1562                             !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
1563                                 /*
1564                                  * Simulate echo to reduce the impact of
1565                                  * traffic analysis. We need to match the
1566                                  * size of a SSH2_MSG_CHANNEL_DATA message
1567                                  * (4 byte channel id + buf)
1568                                  */
1569                                 packet_send_ignore(4 + len);
1570                                 packet_send();
1571                         }
1572                 }
1573                 buffer_consume(&c->output, len);
1574                 if (compat20 && len > 0) {
1575                         c->local_consumed += len;
1576                 }
1577         }
1578         return 1;
1579 }
1580
1581 static int
1582 channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
1583 {
1584         char buf[CHAN_RBUF];
1585         int len;
1586
1587 /** XXX handle drain efd, too */
1588         if (c->efd != -1) {
1589                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
1590                     FD_ISSET(c->efd, writeset) &&
1591                     buffer_len(&c->extended) > 0) {
1592                         len = write(c->efd, buffer_ptr(&c->extended),
1593                             buffer_len(&c->extended));
1594                         debug2("channel %d: written %d to efd %d",
1595                             c->self, len, c->efd);
1596                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1597                                 return 1;
1598                         if (len <= 0) {
1599                                 debug2("channel %d: closing write-efd %d",
1600                                     c->self, c->efd);
1601                                 channel_close_fd(&c->efd);
1602                         } else {
1603                                 buffer_consume(&c->extended, len);
1604                                 c->local_consumed += len;
1605                         }
1606                 } else if (c->extended_usage == CHAN_EXTENDED_READ &&
1607                     FD_ISSET(c->efd, readset)) {
1608                         len = read(c->efd, buf, sizeof(buf));
1609                         debug2("channel %d: read %d from efd %d",
1610                             c->self, len, c->efd);
1611                         if (len < 0 && (errno == EINTR || errno == EAGAIN))
1612                                 return 1;
1613                         if (len <= 0) {
1614                                 debug2("channel %d: closing read-efd %d",
1615                                     c->self, c->efd);
1616                                 channel_close_fd(&c->efd);
1617                         } else {
1618                                 buffer_append(&c->extended, buf, len);
1619                         }
1620                 }
1621         }
1622         return 1;
1623 }
1624
1625 /* ARGSUSED */
1626 static int
1627 channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
1628 {
1629         char buf[16];
1630         int len;
1631
1632         /* Monitor control fd to detect if the slave client exits */
1633         if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
1634                 len = read(c->ctl_fd, buf, sizeof(buf));
1635                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
1636                         return 1;
1637                 if (len <= 0) {
1638                         debug2("channel %d: ctl read<=0", c->self);
1639                         if (c->type != SSH_CHANNEL_OPEN) {
1640                                 debug2("channel %d: not open", c->self);
1641                                 chan_mark_dead(c);
1642                                 return -1;
1643                         } else {
1644                                 chan_read_failed(c);
1645                                 chan_write_failed(c);
1646                         }
1647                         return -1;
1648                 } else
1649                         fatal("%s: unexpected data on ctl fd", __func__);
1650         }
1651         return 1;
1652 }
1653
1654 static int
1655 channel_check_window(Channel *c)
1656 {
1657         if (c->type == SSH_CHANNEL_OPEN &&
1658             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
1659             c->local_window < c->local_window_max/2 &&
1660             c->local_consumed > 0) {
1661                 packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
1662                 packet_put_int(c->remote_id);
1663                 packet_put_int(c->local_consumed);
1664                 packet_send();
1665                 debug2("channel %d: window %d sent adjust %d",
1666                     c->self, c->local_window,
1667                     c->local_consumed);
1668                 c->local_window += c->local_consumed;
1669                 c->local_consumed = 0;
1670         }
1671         return 1;
1672 }
1673
1674 static void
1675 channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
1676 {
1677         if (c->delayed)
1678                 return;
1679         channel_handle_rfd(c, readset, writeset);
1680         channel_handle_wfd(c, readset, writeset);
1681         if (!compat20)
1682                 return;
1683         channel_handle_efd(c, readset, writeset);
1684         channel_handle_ctl(c, readset, writeset);
1685         channel_check_window(c);
1686 }
1687
1688 /* ARGSUSED */
1689 static void
1690 channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
1691 {
1692         int len;
1693
1694         /* Send buffered output data to the socket. */
1695         if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
1696                 len = write(c->sock, buffer_ptr(&c->output),
1697                             buffer_len(&c->output));
1698                 if (len <= 0)
1699                         buffer_clear(&c->output);
1700                 else
1701                         buffer_consume(&c->output, len);
1702         }
1703 }
1704
1705 static void
1706 channel_handler_init_20(void)
1707 {
1708         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1709         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1710         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1711         channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
1712         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1713         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1714         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1715         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1716
1717         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1718         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1719         channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
1720         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1721         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1722         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1723         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1724 }
1725
1726 static void
1727 channel_handler_init_13(void)
1728 {
1729         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
1730         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
1731         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1732         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1733         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1734         channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
1735         channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
1736         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1737         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1738
1739         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1740         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1741         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1742         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1743         channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
1744         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1745         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1746 }
1747
1748 static void
1749 channel_handler_init_15(void)
1750 {
1751         channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
1752         channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
1753         channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
1754         channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
1755         channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
1756         channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
1757         channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
1758
1759         channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
1760         channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
1761         channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
1762         channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
1763         channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
1764         channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
1765 }
1766
1767 static void
1768 channel_handler_init(void)
1769 {
1770         int i;
1771
1772         for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
1773                 channel_pre[i] = NULL;
1774                 channel_post[i] = NULL;
1775         }
1776         if (compat20)
1777                 channel_handler_init_20();
1778         else if (compat13)
1779                 channel_handler_init_13();
1780         else
1781                 channel_handler_init_15();
1782 }
1783
1784 /* gc dead channels */
1785 static void
1786 channel_garbage_collect(Channel *c)
1787 {
1788         if (c == NULL)
1789                 return;
1790         if (c->detach_user != NULL) {
1791                 if (!chan_is_dead(c, c->detach_close))
1792                         return;
1793                 debug2("channel %d: gc: notify user", c->self);
1794                 c->detach_user(c->self, NULL);
1795                 /* if we still have a callback */
1796                 if (c->detach_user != NULL)
1797                         return;
1798                 debug2("channel %d: gc: user detached", c->self);
1799         }
1800         if (!chan_is_dead(c, 1))
1801                 return;
1802         debug2("channel %d: garbage collecting", c->self);
1803         channel_free(c);
1804 }
1805
1806 static void
1807 channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
1808 {
1809         static int did_init = 0;
1810         u_int i;
1811         Channel *c;
1812
1813         if (!did_init) {
1814                 channel_handler_init();
1815                 did_init = 1;
1816         }
1817         for (i = 0; i < channels_alloc; i++) {
1818                 c = channels[i];
1819                 if (c == NULL)
1820                         continue;
1821                 if (ftab[c->type] != NULL)
1822                         (*ftab[c->type])(c, readset, writeset);
1823                 channel_garbage_collect(c);
1824         }
1825 }
1826
1827 /*
1828  * Allocate/update select bitmasks and add any bits relevant to channels in
1829  * select bitmasks.
1830  */
1831 void
1832 channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
1833     u_int *nallocp, int rekeying)
1834 {
1835         u_int n, sz, nfdset;
1836
1837         n = MAX(*maxfdp, channel_max_fd);
1838
1839         nfdset = howmany(n+1, NFDBITS);
1840         /* Explicitly test here, because xrealloc isn't always called */
1841         if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
1842                 fatal("channel_prepare_select: max_fd (%d) is too large", n);
1843         sz = nfdset * sizeof(fd_mask);
1844
1845         /* perhaps check sz < nalloc/2 and shrink? */
1846         if (*readsetp == NULL || sz > *nallocp) {
1847                 *readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
1848                 *writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
1849                 *nallocp = sz;
1850         }
1851         *maxfdp = n;
1852         memset(*readsetp, 0, sz);
1853         memset(*writesetp, 0, sz);
1854
1855         if (!rekeying)
1856                 channel_handler(channel_pre, *readsetp, *writesetp);
1857 }
1858
1859 /*
1860  * After select, perform any appropriate operations for channels which have
1861  * events pending.
1862  */
1863 void
1864 channel_after_select(fd_set *readset, fd_set *writeset)
1865 {
1866         channel_handler(channel_post, readset, writeset);
1867 }
1868
1869
1870 /* If there is data to send to the connection, enqueue some of it now. */
1871 void
1872 channel_output_poll(void)
1873 {
1874         Channel *c;
1875         u_int i, len;
1876
1877         for (i = 0; i < channels_alloc; i++) {
1878                 c = channels[i];
1879                 if (c == NULL)
1880                         continue;
1881
1882                 /*
1883                  * We are only interested in channels that can have buffered
1884                  * incoming data.
1885                  */
1886                 if (compat13) {
1887                         if (c->type != SSH_CHANNEL_OPEN &&
1888                             c->type != SSH_CHANNEL_INPUT_DRAINING)
1889                                 continue;
1890                 } else {
1891                         if (c->type != SSH_CHANNEL_OPEN)
1892                                 continue;
1893                 }
1894                 if (compat20 &&
1895                     (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
1896                         /* XXX is this true? */
1897                         debug3("channel %d: will not send data after close", c->self);
1898                         continue;
1899                 }
1900
1901                 /* Get the amount of buffered data for this channel. */
1902                 if ((c->istate == CHAN_INPUT_OPEN ||
1903                     c->istate == CHAN_INPUT_WAIT_DRAIN) &&
1904                     (len = buffer_len(&c->input)) > 0) {
1905                         if (c->datagram) {
1906                                 if (len > 0) {
1907                                         u_char *data;
1908                                         u_int dlen;
1909
1910                                         data = buffer_get_string(&c->input,
1911                                             &dlen);
1912                                         packet_start(SSH2_MSG_CHANNEL_DATA);
1913                                         packet_put_int(c->remote_id);
1914                                         packet_put_string(data, dlen);
1915                                         packet_send();
1916                                         c->remote_window -= dlen + 4;
1917                                         xfree(data);
1918                                 }
1919                                 continue;
1920                         }
1921                         /*
1922                          * Send some data for the other side over the secure
1923                          * connection.
1924                          */
1925                         if (compat20) {
1926                                 if (len > c->remote_window)
1927                                         len = c->remote_window;
1928                                 if (len > c->remote_maxpacket)
1929                                         len = c->remote_maxpacket;
1930                         } else {
1931                                 if (packet_is_interactive()) {
1932                                         if (len > 1024)
1933                                                 len = 512;
1934                                 } else {
1935                                         /* Keep the packets at reasonable size. */
1936                                         if (len > packet_get_maxsize()/2)
1937                                                 len = packet_get_maxsize()/2;
1938                                 }
1939                         }
1940                         if (len > 0) {
1941                                 packet_start(compat20 ?
1942                                     SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
1943                                 packet_put_int(c->remote_id);
1944                                 packet_put_string(buffer_ptr(&c->input), len);
1945                                 packet_send();
1946                                 buffer_consume(&c->input, len);
1947                                 c->remote_window -= len;
1948                         }
1949                 } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
1950                         if (compat13)
1951                                 fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
1952                         /*
1953                          * input-buffer is empty and read-socket shutdown:
1954                          * tell peer, that we will not send more data: send IEOF.
1955                          * hack for extended data: delay EOF if EFD still in use.
1956                          */
1957                         if (CHANNEL_EFD_INPUT_ACTIVE(c))
1958                                 debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
1959                                     c->self, c->efd, buffer_len(&c->extended));
1960                         else
1961                                 chan_ibuf_empty(c);
1962                 }
1963                 /* Send extended data, i.e. stderr */
1964                 if (compat20 &&
1965                     !(c->flags & CHAN_EOF_SENT) &&
1966                     c->remote_window > 0 &&
1967                     (len = buffer_len(&c->extended)) > 0 &&
1968                     c->extended_usage == CHAN_EXTENDED_READ) {
1969                         debug2("channel %d: rwin %u elen %u euse %d",
1970                             c->self, c->remote_window, buffer_len(&c->extended),
1971                             c->extended_usage);
1972                         if (len > c->remote_window)
1973                                 len = c->remote_window;
1974                         if (len > c->remote_maxpacket)
1975                                 len = c->remote_maxpacket;
1976                         packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
1977                         packet_put_int(c->remote_id);
1978                         packet_put_int(SSH2_EXTENDED_DATA_STDERR);
1979                         packet_put_string(buffer_ptr(&c->extended), len);
1980                         packet_send();
1981                         buffer_consume(&c->extended, len);
1982                         c->remote_window -= len;
1983                         debug2("channel %d: sent ext data %d", c->self, len);
1984                 }
1985         }
1986 }
1987
1988
1989 /* -- protocol input */
1990
1991 /* ARGSUSED */
1992 void
1993 channel_input_data(int type, u_int32_t seq, void *ctxt)
1994 {
1995         int id;
1996         char *data;
1997         u_int data_len;
1998         Channel *c;
1999
2000         /* Get the channel number and verify it. */
2001         id = packet_get_int();
2002         c = channel_lookup(id);
2003         if (c == NULL)
2004                 packet_disconnect("Received data for nonexistent channel %d.", id);
2005
2006         /* Ignore any data for non-open channels (might happen on close) */
2007         if (c->type != SSH_CHANNEL_OPEN &&
2008             c->type != SSH_CHANNEL_X11_OPEN)
2009                 return;
2010
2011         /* Get the data. */
2012         data = packet_get_string(&data_len);
2013
2014         /*
2015          * Ignore data for protocol > 1.3 if output end is no longer open.
2016          * For protocol 2 the sending side is reducing its window as it sends
2017          * data, so we must 'fake' consumption of the data in order to ensure
2018          * that window updates are sent back.  Otherwise the connection might
2019          * deadlock.
2020          */
2021         if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
2022                 if (compat20) {
2023                         c->local_window -= data_len;
2024                         c->local_consumed += data_len;
2025                 }
2026                 xfree(data);
2027                 return;
2028         }
2029
2030         if (compat20) {
2031                 if (data_len > c->local_maxpacket) {
2032                         logit("channel %d: rcvd big packet %d, maxpack %d",
2033                             c->self, data_len, c->local_maxpacket);
2034                 }
2035                 if (data_len > c->local_window) {
2036                         logit("channel %d: rcvd too much data %d, win %d",
2037                             c->self, data_len, c->local_window);
2038                         xfree(data);
2039                         return;
2040                 }
2041                 c->local_window -= data_len;
2042         }
2043         packet_check_eom();
2044         if (c->datagram)
2045                 buffer_put_string(&c->output, data, data_len);
2046         else
2047                 buffer_append(&c->output, data, data_len);
2048         xfree(data);
2049 }
2050
2051 /* ARGSUSED */
2052 void
2053 channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
2054 {
2055         int id;
2056         char *data;
2057         u_int data_len, tcode;
2058         Channel *c;
2059
2060         /* Get the channel number and verify it. */
2061         id = packet_get_int();
2062         c = channel_lookup(id);
2063
2064         if (c == NULL)
2065                 packet_disconnect("Received extended_data for bad channel %d.", id);
2066         if (c->type != SSH_CHANNEL_OPEN) {
2067                 logit("channel %d: ext data for non open", id);
2068                 return;
2069         }
2070         if (c->flags & CHAN_EOF_RCVD) {
2071                 if (datafellows & SSH_BUG_EXTEOF)
2072                         debug("channel %d: accepting ext data after eof", id);
2073                 else
2074                         packet_disconnect("Received extended_data after EOF "
2075                             "on channel %d.", id);
2076         }
2077         tcode = packet_get_int();
2078         if (c->efd == -1 ||
2079             c->extended_usage != CHAN_EXTENDED_WRITE ||
2080             tcode != SSH2_EXTENDED_DATA_STDERR) {
2081                 logit("channel %d: bad ext data", c->self);
2082                 return;
2083         }
2084         data = packet_get_string(&data_len);
2085         packet_check_eom();
2086         if (data_len > c->local_window) {
2087                 logit("channel %d: rcvd too much extended_data %d, win %d",
2088                     c->self, data_len, c->local_window);
2089                 xfree(data);
2090                 return;
2091         }
2092         debug2("channel %d: rcvd ext data %d", c->self, data_len);
2093         c->local_window -= data_len;
2094         buffer_append(&c->extended, data, data_len);
2095         xfree(data);
2096 }
2097
2098 /* ARGSUSED */
2099 void
2100 channel_input_ieof(int type, u_int32_t seq, void *ctxt)
2101 {
2102         int id;
2103         Channel *c;
2104
2105         id = packet_get_int();
2106         packet_check_eom();
2107         c = channel_lookup(id);
2108         if (c == NULL)
2109                 packet_disconnect("Received ieof for nonexistent channel %d.", id);
2110         chan_rcvd_ieof(c);
2111
2112         /* XXX force input close */
2113         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
2114                 debug("channel %d: FORCE input drain", c->self);
2115                 c->istate = CHAN_INPUT_WAIT_DRAIN;
2116                 if (buffer_len(&c->input) == 0)
2117                         chan_ibuf_empty(c);
2118         }
2119
2120 }
2121
2122 /* ARGSUSED */
2123 void
2124 channel_input_close(int type, u_int32_t seq, void *ctxt)
2125 {
2126         int id;
2127         Channel *c;
2128
2129         id = packet_get_int();
2130         packet_check_eom();
2131         c = channel_lookup(id);
2132         if (c == NULL)
2133                 packet_disconnect("Received close for nonexistent channel %d.", id);
2134
2135         /*
2136          * Send a confirmation that we have closed the channel and no more
2137          * data is coming for it.
2138          */
2139         packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
2140         packet_put_int(c->remote_id);
2141         packet_send();
2142
2143         /*
2144          * If the channel is in closed state, we have sent a close request,
2145          * and the other side will eventually respond with a confirmation.
2146          * Thus, we cannot free the channel here, because then there would be
2147          * no-one to receive the confirmation.  The channel gets freed when
2148          * the confirmation arrives.
2149          */
2150         if (c->type != SSH_CHANNEL_CLOSED) {
2151                 /*
2152                  * Not a closed channel - mark it as draining, which will
2153                  * cause it to be freed later.
2154                  */
2155                 buffer_clear(&c->input);
2156                 c->type = SSH_CHANNEL_OUTPUT_DRAINING;
2157         }
2158 }
2159
2160 /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
2161 /* ARGSUSED */
2162 void
2163 channel_input_oclose(int type, u_int32_t seq, void *ctxt)
2164 {
2165         int id = packet_get_int();
2166         Channel *c = channel_lookup(id);
2167
2168         packet_check_eom();
2169         if (c == NULL)
2170                 packet_disconnect("Received oclose for nonexistent channel %d.", id);
2171         chan_rcvd_oclose(c);
2172 }
2173
2174 /* ARGSUSED */
2175 void
2176 channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
2177 {
2178         int id = packet_get_int();
2179         Channel *c = channel_lookup(id);
2180
2181         packet_check_eom();
2182         if (c == NULL)
2183                 packet_disconnect("Received close confirmation for "
2184                     "out-of-range channel %d.", id);
2185         if (c->type != SSH_CHANNEL_CLOSED)
2186                 packet_disconnect("Received close confirmation for "
2187                     "non-closed channel %d (type %d).", id, c->type);
2188         channel_free(c);
2189 }
2190
2191 /* ARGSUSED */
2192 void
2193 channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
2194 {
2195         int id, remote_id;
2196         Channel *c;
2197
2198         id = packet_get_int();
2199         c = channel_lookup(id);
2200
2201         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2202                 packet_disconnect("Received open confirmation for "
2203                     "non-opening channel %d.", id);
2204         remote_id = packet_get_int();
2205         /* Record the remote channel number and mark that the channel is now open. */
2206         c->remote_id = remote_id;
2207         c->type = SSH_CHANNEL_OPEN;
2208
2209         if (compat20) {
2210                 c->remote_window = packet_get_int();
2211                 c->remote_maxpacket = packet_get_int();
2212                 if (c->confirm) {
2213                         debug2("callback start");
2214                         c->confirm(c->self, c->confirm_ctx);
2215                         debug2("callback done");
2216                 }
2217                 debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
2218                     c->remote_window, c->remote_maxpacket);
2219         }
2220         packet_check_eom();
2221 }
2222
2223 static char *
2224 reason2txt(int reason)
2225 {
2226         switch (reason) {
2227         case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
2228                 return "administratively prohibited";
2229         case SSH2_OPEN_CONNECT_FAILED:
2230                 return "connect failed";
2231         case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
2232                 return "unknown channel type";
2233         case SSH2_OPEN_RESOURCE_SHORTAGE:
2234                 return "resource shortage";
2235         }
2236         return "unknown reason";
2237 }
2238
2239 /* ARGSUSED */
2240 void
2241 channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
2242 {
2243         int id, reason;
2244         char *msg = NULL, *lang = NULL;
2245         Channel *c;
2246
2247         id = packet_get_int();
2248         c = channel_lookup(id);
2249
2250         if (c==NULL || c->type != SSH_CHANNEL_OPENING)
2251                 packet_disconnect("Received open failure for "
2252                     "non-opening channel %d.", id);
2253         if (compat20) {
2254                 reason = packet_get_int();
2255                 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2256                         msg  = packet_get_string(NULL);
2257                         lang = packet_get_string(NULL);
2258                 }
2259                 logit("channel %d: open failed: %s%s%s", id,
2260                     reason2txt(reason), msg ? ": ": "", msg ? msg : "");
2261                 if (msg != NULL)
2262                         xfree(msg);
2263                 if (lang != NULL)
2264                         xfree(lang);
2265         }
2266         packet_check_eom();
2267         /* Free the channel.  This will also close the socket. */
2268         channel_free(c);
2269 }
2270
2271 /* ARGSUSED */
2272 void
2273 channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
2274 {
2275         Channel *c;
2276         int id;
2277         u_int adjust;
2278
2279         if (!compat20)
2280                 return;
2281
2282         /* Get the channel number and verify it. */
2283         id = packet_get_int();
2284         c = channel_lookup(id);
2285
2286         if (c == NULL) {
2287                 logit("Received window adjust for non-open channel %d.", id);
2288                 return;
2289         }
2290         adjust = packet_get_int();
2291         packet_check_eom();
2292         debug2("channel %d: rcvd adjust %u", id, adjust);
2293         c->remote_window += adjust;
2294 }
2295
2296 /* ARGSUSED */
2297 void
2298 channel_input_port_open(int type, u_int32_t seq, void *ctxt)
2299 {
2300         Channel *c = NULL;
2301         u_short host_port;
2302         char *host, *originator_string;
2303         int remote_id, sock = -1;
2304
2305         remote_id = packet_get_int();
2306         host = packet_get_string(NULL);
2307         host_port = packet_get_int();
2308
2309         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
2310                 originator_string = packet_get_string(NULL);
2311         } else {
2312                 originator_string = xstrdup("unknown (remote did not supply name)");
2313         }
2314         packet_check_eom();
2315         sock = channel_connect_to(host, host_port);
2316         if (sock != -1) {
2317                 c = channel_new("connected socket",
2318                     SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
2319                     originator_string, 1);
2320                 c->remote_id = remote_id;
2321         }
2322         xfree(originator_string);
2323         if (c == NULL) {
2324                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
2325                 packet_put_int(remote_id);
2326                 packet_send();
2327         }
2328         xfree(host);
2329 }
2330
2331
2332 /* -- tcp forwarding */
2333
2334 void
2335 channel_set_af(int af)
2336 {
2337         IPv4or6 = af;
2338 }
2339
2340 static int
2341 channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
2342     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2343 {
2344         Channel *c;
2345         int sock, r, success = 0, wildcard = 0, is_client;
2346         struct addrinfo hints, *ai, *aitop;
2347         const char *host, *addr;
2348         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2349
2350         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
2351             listen_addr : host_to_connect;
2352         is_client = (type == SSH_CHANNEL_PORT_LISTENER);
2353
2354         if (host == NULL) {
2355                 error("No forward host name.");
2356                 return 0;
2357         }
2358         if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
2359                 error("Forward host name too long.");
2360                 return 0;
2361         }
2362
2363         /*
2364          * Determine whether or not a port forward listens to loopback,
2365          * specified address or wildcard. On the client, a specified bind
2366          * address will always override gateway_ports. On the server, a
2367          * gateway_ports of 1 (``yes'') will override the client's
2368          * specification and force a wildcard bind, whereas a value of 2
2369          * (``clientspecified'') will bind to whatever address the client
2370          * asked for.
2371          *
2372          * Special-case listen_addrs are:
2373          *
2374          * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
2375          * "" (empty string), "*"  -> wildcard v4/v6
2376          * "localhost"             -> loopback v4/v6
2377          */
2378         addr = NULL;
2379         if (listen_addr == NULL) {
2380                 /* No address specified: default to gateway_ports setting */
2381                 if (gateway_ports)
2382                         wildcard = 1;
2383         } else if (gateway_ports || is_client) {
2384                 if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
2385                     strcmp(listen_addr, "0.0.0.0") == 0) ||
2386                     *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
2387                     (!is_client && gateway_ports == 1))
2388                         wildcard = 1;
2389                 else if (strcmp(listen_addr, "localhost") != 0)
2390                         addr = listen_addr;
2391         }
2392
2393         debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
2394             type, wildcard, (addr == NULL) ? "NULL" : addr);
2395
2396         /*
2397          * getaddrinfo returns a loopback address if the hostname is
2398          * set to NULL and hints.ai_flags is not AI_PASSIVE
2399          */
2400         memset(&hints, 0, sizeof(hints));
2401         hints.ai_family = IPv4or6;
2402         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
2403         hints.ai_socktype = SOCK_STREAM;
2404         snprintf(strport, sizeof strport, "%d", listen_port);
2405         if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
2406                 if (addr == NULL) {
2407                         /* This really shouldn't happen */
2408                         packet_disconnect("getaddrinfo: fatal error: %s",
2409                             gai_strerror(r));
2410                 } else {
2411                         error("channel_setup_fwd_listener: "
2412                             "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
2413                 }
2414                 return 0;
2415         }
2416
2417         for (ai = aitop; ai; ai = ai->ai_next) {
2418                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2419                         continue;
2420                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2421                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2422                         error("channel_setup_fwd_listener: getnameinfo failed");
2423                         continue;
2424                 }
2425                 /* Create a port to listen for the host. */
2426                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2427                 if (sock < 0) {
2428                         /* this is no error since kernel may not support ipv6 */
2429                         verbose("socket: %.100s", strerror(errno));
2430                         continue;
2431                 }
2432
2433                 channel_set_reuseaddr(sock);
2434
2435                 debug("Local forwarding listening on %s port %s.", ntop, strport);
2436
2437                 /* Bind the socket to the address. */
2438                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2439                         /* address can be in use ipv6 address is already bound */
2440                         if (!ai->ai_next)
2441                                 error("bind: %.100s", strerror(errno));
2442                         else
2443                                 verbose("bind: %.100s", strerror(errno));
2444
2445                         close(sock);
2446                         continue;
2447                 }
2448                 /* Start listening for connections on the socket. */
2449                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2450                         error("listen: %.100s", strerror(errno));
2451                         close(sock);
2452                         continue;
2453                 }
2454                 /* Allocate a channel number for the socket. */
2455                 c = channel_new("port listener", type, sock, sock, -1,
2456                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
2457                     0, "port listener", 1);
2458                 strlcpy(c->path, host, sizeof(c->path));
2459                 c->host_port = port_to_connect;
2460                 c->listening_port = listen_port;
2461                 success = 1;
2462         }
2463         if (success == 0)
2464                 error("channel_setup_fwd_listener: cannot listen to port: %d",
2465                     listen_port);
2466         freeaddrinfo(aitop);
2467         return success;
2468 }
2469
2470 int
2471 channel_cancel_rport_listener(const char *host, u_short port)
2472 {
2473         u_int i;
2474         int found = 0;
2475
2476         for (i = 0; i < channels_alloc; i++) {
2477                 Channel *c = channels[i];
2478
2479                 if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
2480                     strncmp(c->path, host, sizeof(c->path)) == 0 &&
2481                     c->listening_port == port) {
2482                         debug2("%s: close channel %d", __func__, i);
2483                         channel_free(c);
2484                         found = 1;
2485                 }
2486         }
2487
2488         return (found);
2489 }
2490
2491 /* protocol local port fwd, used by ssh (and sshd in v1) */
2492 int
2493 channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
2494     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
2495 {
2496         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
2497             listen_host, listen_port, host_to_connect, port_to_connect,
2498             gateway_ports);
2499 }
2500
2501 /* protocol v2 remote port fwd, used by sshd */
2502 int
2503 channel_setup_remote_fwd_listener(const char *listen_address,
2504     u_short listen_port, int gateway_ports)
2505 {
2506         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
2507             listen_address, listen_port, NULL, 0, gateway_ports);
2508 }
2509
2510 /*
2511  * Initiate forwarding of connections to port "port" on remote host through
2512  * the secure channel to host:port from local side.
2513  */
2514
2515 int
2516 channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
2517     const char *host_to_connect, u_short port_to_connect)
2518 {
2519         int type, success = 0;
2520
2521         /* Record locally that connection to this host/port is permitted. */
2522         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2523                 fatal("channel_request_remote_forwarding: too many forwards");
2524
2525         /* Send the forward request to the remote side. */
2526         if (compat20) {
2527                 const char *address_to_bind;
2528                 if (listen_host == NULL)
2529                         address_to_bind = "localhost";
2530                 else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
2531                         address_to_bind = "";
2532                 else
2533                         address_to_bind = listen_host;
2534
2535                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
2536                 packet_put_cstring("tcpip-forward");
2537                 packet_put_char(1);                     /* boolean: want reply */
2538                 packet_put_cstring(address_to_bind);
2539                 packet_put_int(listen_port);
2540                 packet_send();
2541                 packet_write_wait();
2542                 /* Assume that server accepts the request */
2543                 success = 1;
2544         } else {
2545                 packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
2546                 packet_put_int(listen_port);
2547                 packet_put_cstring(host_to_connect);
2548                 packet_put_int(port_to_connect);
2549                 packet_send();
2550                 packet_write_wait();
2551
2552                 /* Wait for response from the remote side. */
2553                 type = packet_read();
2554                 switch (type) {
2555                 case SSH_SMSG_SUCCESS:
2556                         success = 1;
2557                         break;
2558                 case SSH_SMSG_FAILURE:
2559                         break;
2560                 default:
2561                         /* Unknown packet */
2562                         packet_disconnect("Protocol error for port forward request:"
2563                             "received packet type %d.", type);
2564                 }
2565         }
2566         if (success) {
2567                 permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
2568                 permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
2569                 permitted_opens[num_permitted_opens].listen_port = listen_port;
2570                 num_permitted_opens++;
2571         }
2572         return (success ? 0 : -1);
2573 }
2574
2575 /*
2576  * Request cancellation of remote forwarding of connection host:port from
2577  * local side.
2578  */
2579 void
2580 channel_request_rforward_cancel(const char *host, u_short port)
2581 {
2582         int i;
2583
2584         if (!compat20)
2585                 return;
2586
2587         for (i = 0; i < num_permitted_opens; i++) {
2588                 if (permitted_opens[i].host_to_connect != NULL &&
2589                     permitted_opens[i].listen_port == port)
2590                         break;
2591         }
2592         if (i >= num_permitted_opens) {
2593                 debug("%s: requested forward not found", __func__);
2594                 return;
2595         }
2596         packet_start(SSH2_MSG_GLOBAL_REQUEST);
2597         packet_put_cstring("cancel-tcpip-forward");
2598         packet_put_char(0);
2599         packet_put_cstring(host == NULL ? "" : host);
2600         packet_put_int(port);
2601         packet_send();
2602
2603         permitted_opens[i].listen_port = 0;
2604         permitted_opens[i].port_to_connect = 0;
2605         xfree(permitted_opens[i].host_to_connect);
2606         permitted_opens[i].host_to_connect = NULL;
2607 }
2608
2609 /*
2610  * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
2611  * listening for the port, and sends back a success reply (or disconnect
2612  * message if there was an error).
2613  */
2614 int
2615 channel_input_port_forward_request(int is_root, int gateway_ports)
2616 {
2617         u_short port, host_port;
2618         int success = 0;
2619         char *hostname;
2620
2621         /* Get arguments from the packet. */
2622         port = packet_get_int();
2623         hostname = packet_get_string(NULL);
2624         host_port = packet_get_int();
2625
2626 #ifndef HAVE_CYGWIN
2627         /*
2628          * Check that an unprivileged user is not trying to forward a
2629          * privileged port.
2630          */
2631         if (port < IPPORT_RESERVED && !is_root)
2632                 packet_disconnect(
2633                     "Requested forwarding of port %d but user is not root.",
2634                     port);
2635         if (host_port == 0)
2636                 packet_disconnect("Dynamic forwarding denied.");
2637 #endif
2638
2639         /* Initiate forwarding */
2640         success = channel_setup_local_fwd_listener(NULL, port, hostname,
2641             host_port, gateway_ports);
2642
2643         /* Free the argument string. */
2644         xfree(hostname);
2645
2646         return (success ? 0 : -1);
2647 }
2648
2649 /*
2650  * Permits opening to any host/port if permitted_opens[] is empty.  This is
2651  * usually called by the server, because the user could connect to any port
2652  * anyway, and the server has no way to know but to trust the client anyway.
2653  */
2654 void
2655 channel_permit_all_opens(void)
2656 {
2657         if (num_permitted_opens == 0)
2658                 all_opens_permitted = 1;
2659 }
2660
2661 void
2662 channel_add_permitted_opens(char *host, int port)
2663 {
2664         if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2665                 fatal("channel_add_permitted_opens: too many forwards");
2666         debug("allow port forwarding to host %s port %d", host, port);
2667
2668         permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
2669         permitted_opens[num_permitted_opens].port_to_connect = port;
2670         num_permitted_opens++;
2671
2672         all_opens_permitted = 0;
2673 }
2674
2675 int
2676 channel_add_adm_permitted_opens(char *host, int port)
2677 {
2678         if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
2679                 fatal("channel_add_adm_permitted_opens: too many forwards");
2680         debug("config allows port forwarding to host %s port %d", host, port);
2681
2682         permitted_adm_opens[num_adm_permitted_opens].host_to_connect
2683              = xstrdup(host);
2684         permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
2685         return ++num_adm_permitted_opens;
2686 }
2687
2688 void
2689 channel_clear_permitted_opens(void)
2690 {
2691         int i;
2692
2693         for (i = 0; i < num_permitted_opens; i++)
2694                 if (permitted_opens[i].host_to_connect != NULL)
2695                         xfree(permitted_opens[i].host_to_connect);
2696         num_permitted_opens = 0;
2697 }
2698
2699 void
2700 channel_clear_adm_permitted_opens(void)
2701 {
2702         int i;
2703
2704         for (i = 0; i < num_adm_permitted_opens; i++)
2705                 if (permitted_adm_opens[i].host_to_connect != NULL)
2706                         xfree(permitted_adm_opens[i].host_to_connect);
2707         num_adm_permitted_opens = 0;
2708 }
2709
2710 /* return socket to remote host, port */
2711 static int
2712 connect_to(const char *host, u_short port)
2713 {
2714         struct addrinfo hints, *ai, *aitop;
2715         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
2716         int gaierr;
2717         int sock = -1;
2718
2719         memset(&hints, 0, sizeof(hints));
2720         hints.ai_family = IPv4or6;
2721         hints.ai_socktype = SOCK_STREAM;
2722         snprintf(strport, sizeof strport, "%d", port);
2723         if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
2724                 error("connect_to %.100s: unknown host (%s)", host,
2725                     gai_strerror(gaierr));
2726                 return -1;
2727         }
2728         for (ai = aitop; ai; ai = ai->ai_next) {
2729                 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2730                         continue;
2731                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
2732                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
2733                         error("connect_to: getnameinfo failed");
2734                         continue;
2735                 }
2736                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
2737                 if (sock < 0) {
2738                         if (ai->ai_next == NULL)
2739                                 error("socket: %.100s", strerror(errno));
2740                         else
2741                                 verbose("socket: %.100s", strerror(errno));
2742                         continue;
2743                 }
2744                 if (set_nonblock(sock) == -1)
2745                         fatal("%s: set_nonblock(%d)", __func__, sock);
2746                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
2747                     errno != EINPROGRESS) {
2748                         error("connect_to %.100s port %s: %.100s", ntop, strport,
2749                             strerror(errno));
2750                         close(sock);
2751                         continue;       /* fail -- try next */
2752                 }
2753                 break; /* success */
2754
2755         }
2756         freeaddrinfo(aitop);
2757         if (!ai) {
2758                 error("connect_to %.100s port %d: failed.", host, port);
2759                 return -1;
2760         }
2761         /* success */
2762         set_nodelay(sock);
2763         return sock;
2764 }
2765
2766 int
2767 channel_connect_by_listen_address(u_short listen_port)
2768 {
2769         int i;
2770
2771         for (i = 0; i < num_permitted_opens; i++)
2772                 if (permitted_opens[i].host_to_connect != NULL &&
2773                     permitted_opens[i].listen_port == listen_port)
2774                         return connect_to(
2775                             permitted_opens[i].host_to_connect,
2776                             permitted_opens[i].port_to_connect);
2777         error("WARNING: Server requests forwarding for unknown listen_port %d",
2778             listen_port);
2779         return -1;
2780 }
2781
2782 /* Check if connecting to that port is permitted and connect. */
2783 int
2784 channel_connect_to(const char *host, u_short port)
2785 {
2786         int i, permit, permit_adm = 1;
2787
2788         permit = all_opens_permitted;
2789         if (!permit) {
2790                 for (i = 0; i < num_permitted_opens; i++)
2791                         if (permitted_opens[i].host_to_connect != NULL &&
2792                             permitted_opens[i].port_to_connect == port &&
2793                             strcmp(permitted_opens[i].host_to_connect, host) == 0)
2794                                 permit = 1;
2795         }
2796
2797         if (num_adm_permitted_opens > 0) {
2798                 permit_adm = 0;
2799                 for (i = 0; i < num_adm_permitted_opens; i++)
2800                         if (permitted_adm_opens[i].host_to_connect != NULL &&
2801                             permitted_adm_opens[i].port_to_connect == port &&
2802                             strcmp(permitted_adm_opens[i].host_to_connect, host)
2803                             == 0)
2804                                 permit_adm = 1;
2805         }
2806
2807         if (!permit || !permit_adm) {
2808                 logit("Received request to connect to host %.100s port %d, "
2809                     "but the request was denied.", host, port);
2810                 return -1;
2811         }
2812         return connect_to(host, port);
2813 }
2814
2815 void
2816 channel_send_window_changes(void)
2817 {
2818         u_int i;
2819         struct winsize ws;
2820
2821         for (i = 0; i < channels_alloc; i++) {
2822                 if (channels[i] == NULL || !channels[i]->client_tty ||
2823                     channels[i]->type != SSH_CHANNEL_OPEN)
2824                         continue;
2825                 if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
2826                         continue;
2827                 channel_request_start(i, "window-change", 0);
2828                 packet_put_int((u_int)ws.ws_col);
2829                 packet_put_int((u_int)ws.ws_row);
2830                 packet_put_int((u_int)ws.ws_xpixel);
2831                 packet_put_int((u_int)ws.ws_ypixel);
2832                 packet_send();
2833         }
2834 }
2835
2836 /* -- X11 forwarding */
2837
2838 /*
2839  * Creates an internet domain socket for listening for X11 connections.
2840  * Returns 0 and a suitable display number for the DISPLAY variable
2841  * stored in display_numberp , or -1 if an error occurs.
2842  */
2843 int
2844 x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
2845     int single_connection, u_int *display_numberp, int **chanids)
2846 {
2847         Channel *nc = NULL;
2848         int display_number, sock;
2849         u_short port;
2850         struct addrinfo hints, *ai, *aitop;
2851         char strport[NI_MAXSERV];
2852         int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
2853
2854         if (chanids == NULL)
2855                 return -1;
2856
2857         for (display_number = x11_display_offset;
2858             display_number < MAX_DISPLAYS;
2859             display_number++) {
2860                 port = 6000 + display_number;
2861                 memset(&hints, 0, sizeof(hints));
2862                 hints.ai_family = IPv4or6;
2863                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
2864                 hints.ai_socktype = SOCK_STREAM;
2865                 snprintf(strport, sizeof strport, "%d", port);
2866                 if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
2867                         error("getaddrinfo: %.100s", gai_strerror(gaierr));
2868                         return -1;
2869                 }
2870                 for (ai = aitop; ai; ai = ai->ai_next) {
2871                         if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
2872                                 continue;
2873                         sock = socket(ai->ai_family, ai->ai_socktype,
2874                             ai->ai_protocol);
2875                         if (sock < 0) {
2876                                 if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
2877                                         error("socket: %.100s", strerror(errno));
2878                                         freeaddrinfo(aitop);
2879                                         return -1;
2880                                 } else {
2881                                         debug("x11_create_display_inet: Socket family %d not supported",
2882                                                  ai->ai_family);
2883                                         continue;
2884                                 }
2885                         }
2886 #ifdef IPV6_V6ONLY
2887                         if (ai->ai_family == AF_INET6) {
2888                                 int on = 1;
2889                                 if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
2890                                         error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
2891                         }
2892 #endif
2893                         channel_set_reuseaddr(sock);
2894                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
2895                                 debug2("bind port %d: %.100s", port, strerror(errno));
2896                                 close(sock);
2897
2898                                 if (ai->ai_next)
2899                                         continue;
2900
2901                                 for (n = 0; n < num_socks; n++) {
2902                                         close(socks[n]);
2903                                 }
2904                                 num_socks = 0;
2905                                 break;
2906                         }
2907                         socks[num_socks++] = sock;
2908 #ifndef DONT_TRY_OTHER_AF
2909                         if (num_socks == NUM_SOCKS)
2910                                 break;
2911 #else
2912                         if (x11_use_localhost) {
2913                                 if (num_socks == NUM_SOCKS)
2914                                         break;
2915                         } else {
2916                                 break;
2917                         }
2918 #endif
2919                 }
2920                 freeaddrinfo(aitop);
2921                 if (num_socks > 0)
2922                         break;
2923         }
2924         if (display_number >= MAX_DISPLAYS) {
2925                 error("Failed to allocate internet-domain X11 display socket.");
2926                 return -1;
2927         }
2928         /* Start listening for connections on the socket. */
2929         for (n = 0; n < num_socks; n++) {
2930                 sock = socks[n];
2931                 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
2932                         error("listen: %.100s", strerror(errno));
2933                         close(sock);
2934                         return -1;
2935                 }
2936         }
2937
2938         /* Allocate a channel for each socket. */
2939         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
2940         for (n = 0; n < num_socks; n++) {
2941                 sock = socks[n];
2942                 nc = channel_new("x11 listener",
2943                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
2944                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
2945                     0, "X11 inet listener", 1);
2946                 nc->single_connection = single_connection;
2947                 (*chanids)[n] = nc->self;
2948         }
2949         (*chanids)[n] = -1;
2950
2951         /* Return the display number for the DISPLAY environment variable. */
2952         *display_numberp = display_number;
2953         return (0);
2954 }
2955
2956 static int
2957 connect_local_xsocket(u_int dnr)
2958 {
2959         int sock;
2960         struct sockaddr_un addr;
2961
2962         sock = socket(AF_UNIX, SOCK_STREAM, 0);
2963         if (sock < 0)
2964                 error("socket: %.100s", strerror(errno));
2965         memset(&addr, 0, sizeof(addr));
2966         addr.sun_family = AF_UNIX;
2967         snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
2968         if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
2969                 return sock;
2970         close(sock);
2971         error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
2972         return -1;
2973 }
2974
2975 int
2976 x11_connect_display(void)
2977 {
2978         u_int display_number;
2979         const char *display;
2980         char buf[1024], *cp;
2981         struct addrinfo hints, *ai, *aitop;
2982         char strport[NI_MAXSERV];
2983         int gaierr, sock = 0;
2984
2985         /* Try to open a socket for the local X server. */
2986         display = getenv("DISPLAY");
2987         if (!display) {
2988                 error("DISPLAY not set.");
2989                 return -1;
2990         }
2991         /*
2992          * Now we decode the value of the DISPLAY variable and make a
2993          * connection to the real X server.
2994          */
2995
2996         /*
2997          * Check if it is a unix domain socket.  Unix domain displays are in
2998          * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
2999          */
3000         if (strncmp(display, "unix:", 5) == 0 ||
3001             display[0] == ':') {
3002                 /* Connect to the unix domain socket. */
3003                 if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
3004                         error("Could not parse display number from DISPLAY: %.100s",
3005                             display);
3006                         return -1;
3007                 }
3008                 /* Create a socket. */
3009                 sock = connect_local_xsocket(display_number);
3010                 if (sock < 0)
3011                         return -1;
3012
3013                 /* OK, we now have a connection to the display. */
3014                 return sock;
3015         }
3016         /*
3017          * Connect to an inet socket.  The DISPLAY value is supposedly
3018          * hostname:d[.s], where hostname may also be numeric IP address.
3019          */
3020         strlcpy(buf, display, sizeof(buf));
3021         cp = strchr(buf, ':');
3022         if (!cp) {
3023                 error("Could not find ':' in DISPLAY: %.100s", display);
3024                 return -1;
3025         }
3026         *cp = 0;
3027         /* buf now contains the host name.  But first we parse the display number. */
3028         if (sscanf(cp + 1, "%u", &display_number) != 1) {
3029                 error("Could not parse display number from DISPLAY: %.100s",
3030                     display);
3031                 return -1;
3032         }
3033
3034         /* Look up the host address */
3035         memset(&hints, 0, sizeof(hints));
3036         hints.ai_family = IPv4or6;
3037         hints.ai_socktype = SOCK_STREAM;
3038         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
3039         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
3040                 error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
3041                 return -1;
3042         }
3043         for (ai = aitop; ai; ai = ai->ai_next) {
3044                 /* Create a socket. */
3045                 sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
3046                 if (sock < 0) {
3047                         debug2("socket: %.100s", strerror(errno));
3048                         continue;
3049                 }
3050                 /* Connect it to the display. */
3051                 if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
3052                         debug2("connect %.100s port %u: %.100s", buf,
3053                             6000 + display_number, strerror(errno));
3054                         close(sock);
3055                         continue;
3056                 }
3057                 /* Success */
3058                 break;
3059         }
3060         freeaddrinfo(aitop);
3061         if (!ai) {
3062                 error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
3063                     strerror(errno));
3064                 return -1;
3065         }
3066         set_nodelay(sock);
3067         return sock;
3068 }
3069
3070 /*
3071  * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
3072  * the remote channel number.  We should do whatever we want, and respond
3073  * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
3074  */
3075
3076 /* ARGSUSED */
3077 void
3078 x11_input_open(int type, u_int32_t seq, void *ctxt)
3079 {
3080         Channel *c = NULL;
3081         int remote_id, sock = 0;
3082         char *remote_host;
3083
3084         debug("Received X11 open request.");
3085
3086         remote_id = packet_get_int();
3087
3088         if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
3089                 remote_host = packet_get_string(NULL);
3090         } else {
3091                 remote_host = xstrdup("unknown (remote did not supply name)");
3092         }
3093         packet_check_eom();
3094
3095         /* Obtain a connection to the real X display. */
3096         sock = x11_connect_display();
3097         if (sock != -1) {
3098                 /* Allocate a channel for this connection. */
3099                 c = channel_new("connected x11 socket",
3100                     SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
3101                     remote_host, 1);
3102                 c->remote_id = remote_id;
3103                 c->force_drain = 1;
3104         }
3105         xfree(remote_host);
3106         if (c == NULL) {
3107                 /* Send refusal to the remote host. */
3108                 packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3109                 packet_put_int(remote_id);
3110         } else {
3111                 /* Send a confirmation to the remote host. */
3112                 packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
3113                 packet_put_int(remote_id);
3114                 packet_put_int(c->self);
3115         }
3116         packet_send();
3117 }
3118
3119 /* dummy protocol handler that denies SSH-1 requests (agent/x11) */
3120 /* ARGSUSED */
3121 void
3122 deny_input_open(int type, u_int32_t seq, void *ctxt)
3123 {
3124         int rchan = packet_get_int();
3125
3126         switch (type) {
3127         case SSH_SMSG_AGENT_OPEN:
3128                 error("Warning: ssh server tried agent forwarding.");
3129                 break;
3130         case SSH_SMSG_X11_OPEN:
3131                 error("Warning: ssh server tried X11 forwarding.");
3132                 break;
3133         default:
3134                 error("deny_input_open: type %d", type);
3135                 break;
3136         }
3137         error("Warning: this is probably a break-in attempt by a malicious server.");
3138         packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
3139         packet_put_int(rchan);
3140         packet_send();
3141 }
3142
3143 /*
3144  * Requests forwarding of X11 connections, generates fake authentication
3145  * data, and enables authentication spoofing.
3146  * This should be called in the client only.
3147  */
3148 void
3149 x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
3150     const char *proto, const char *data)
3151 {
3152         u_int data_len = (u_int) strlen(data) / 2;
3153         u_int i, value;
3154         char *new_data;
3155         int screen_number;
3156         const char *cp;
3157         u_int32_t rnd = 0;
3158
3159         if (x11_saved_display == NULL)
3160                 x11_saved_display = xstrdup(disp);
3161         else if (strcmp(disp, x11_saved_display) != 0) {
3162                 error("x11_request_forwarding_with_spoofing: different "
3163                     "$DISPLAY already forwarded");
3164                 return;
3165         }
3166
3167         cp = strchr(disp, ':');
3168         if (cp)
3169                 cp = strchr(cp, '.');
3170         if (cp)
3171                 screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
3172         else
3173                 screen_number = 0;
3174
3175         if (x11_saved_proto == NULL) {
3176                 /* Save protocol name. */
3177                 x11_saved_proto = xstrdup(proto);
3178                 /*
3179                  * Extract real authentication data and generate fake data
3180                  * of the same length.
3181                  */
3182                 x11_saved_data = xmalloc(data_len);
3183                 x11_fake_data = xmalloc(data_len);
3184                 for (i = 0; i < data_len; i++) {
3185                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
3186                                 fatal("x11_request_forwarding: bad "
3187                                     "authentication data: %.100s", data);
3188                         if (i % 4 == 0)
3189                                 rnd = arc4random();
3190                         x11_saved_data[i] = value;
3191                         x11_fake_data[i] = rnd & 0xff;
3192                         rnd >>= 8;
3193                 }
3194                 x11_saved_data_len = data_len;
3195                 x11_fake_data_len = data_len;
3196         }
3197
3198         /* Convert the fake data into hex. */
3199         new_data = tohex(x11_fake_data, data_len);
3200
3201         /* Send the request packet. */
3202         if (compat20) {
3203                 channel_request_start(client_session_id, "x11-req", 0);
3204                 packet_put_char(0);     /* XXX bool single connection */
3205         } else {
3206                 packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
3207         }
3208         packet_put_cstring(proto);
3209         packet_put_cstring(new_data);
3210         packet_put_int(screen_number);
3211         packet_send();
3212         packet_write_wait();
3213         xfree(new_data);
3214 }
3215
3216
3217 /* -- agent forwarding */
3218
3219 /* Sends a message to the server to request authentication fd forwarding. */
3220
3221 void
3222 auth_request_forwarding(void)
3223 {
3224         packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
3225         packet_send();
3226         packet_write_wait();
3227 }