1 /* $OpenBSD: nchan.c,v 1.74 2022/02/01 23:32:51 djm Exp $ */
3 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #include <sys/types.h>
29 #include <sys/socket.h>
35 #include "openbsd-compat/sys-queue.h"
45 * SSH Protocol 1.5 aka New Channel Protocol
46 * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored.
47 * Written by Markus Friedl in October 1999
49 * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the
50 * tear down of channels:
52 * 1.3: strict request-ack-protocol:
56 * 1.5: uses variations of:
61 * i.e. both sides have to close the channel
63 * 2.0: the EOF messages are optional
65 * See the debugging output from 'ssh -v' and 'sshd -d' of
66 * ssh-1.2.27 as an example.
70 /* functions manipulating channel states */
72 * EVENTS update channel input/output states execute ACTIONS
75 * ACTIONS: should never update the channel states
77 static void chan_send_eof2(struct ssh
*, Channel
*);
78 static void chan_send_eow2(struct ssh
*, Channel
*);
81 static void chan_shutdown_write(struct ssh
*, Channel
*);
82 static void chan_shutdown_read(struct ssh
*, Channel
*);
83 static void chan_shutdown_extended_read(struct ssh
*, Channel
*);
85 static const char * const ostates
[] = {
86 "open", "drain", "wait_ieof", "closed",
88 static const char * const istates
[] = {
89 "open", "drain", "wait_oclose", "closed",
93 chan_set_istate(Channel
*c
, u_int next
)
95 if (c
->istate
> CHAN_INPUT_CLOSED
|| next
> CHAN_INPUT_CLOSED
)
96 fatal("chan_set_istate: bad state %d -> %d", c
->istate
, next
);
97 debug2("channel %d: input %s -> %s", c
->self
, istates
[c
->istate
],
103 chan_set_ostate(Channel
*c
, u_int next
)
105 if (c
->ostate
> CHAN_OUTPUT_CLOSED
|| next
> CHAN_OUTPUT_CLOSED
)
106 fatal("chan_set_ostate: bad state %d -> %d", c
->ostate
, next
);
107 debug2("channel %d: output %s -> %s", c
->self
, ostates
[c
->ostate
],
113 chan_read_failed(struct ssh
*ssh
, Channel
*c
)
115 debug2("channel %d: read failed", c
->self
);
117 case CHAN_INPUT_OPEN
:
118 chan_shutdown_read(ssh
, c
);
119 chan_set_istate(c
, CHAN_INPUT_WAIT_DRAIN
);
122 error("channel %d: chan_read_failed for istate %d",
129 chan_ibuf_empty(struct ssh
*ssh
, Channel
*c
)
131 debug2("channel %d: ibuf empty", c
->self
);
132 if (sshbuf_len(c
->input
)) {
133 error("channel %d: chan_ibuf_empty for non empty buffer",
138 case CHAN_INPUT_WAIT_DRAIN
:
139 if (!(c
->flags
& (CHAN_CLOSE_SENT
|CHAN_LOCAL
)))
140 chan_send_eof2(ssh
, c
);
141 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
144 error("channel %d: chan_ibuf_empty for istate %d",
151 chan_obuf_empty(struct ssh
*ssh
, Channel
*c
)
153 debug2("channel %d: obuf empty", c
->self
);
154 if (sshbuf_len(c
->output
)) {
155 error("channel %d: chan_obuf_empty for non empty buffer",
160 case CHAN_OUTPUT_WAIT_DRAIN
:
161 chan_shutdown_write(ssh
, c
);
162 chan_set_ostate(c
, CHAN_OUTPUT_CLOSED
);
165 error("channel %d: internal error: obuf_empty for ostate %d",
172 chan_rcvd_eow(struct ssh
*ssh
, Channel
*c
)
174 debug2("channel %d: rcvd eow", c
->self
);
176 case CHAN_INPUT_OPEN
:
177 chan_shutdown_read(ssh
, c
);
178 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
184 chan_send_eof2(struct ssh
*ssh
, Channel
*c
)
188 debug2("channel %d: send eof", c
->self
);
190 case CHAN_INPUT_WAIT_DRAIN
:
191 if (!c
->have_remote_id
)
192 fatal_f("channel %d: no remote_id", c
->self
);
193 if ((r
= sshpkt_start(ssh
, SSH2_MSG_CHANNEL_EOF
)) != 0 ||
194 (r
= sshpkt_put_u32(ssh
, c
->remote_id
)) != 0 ||
195 (r
= sshpkt_send(ssh
)) != 0)
196 fatal_fr(r
, "send CHANNEL_EOF");
197 c
->flags
|= CHAN_EOF_SENT
;
200 error("channel %d: cannot send eof for istate %d",
207 chan_send_close2(struct ssh
*ssh
, Channel
*c
)
211 debug2("channel %d: send close", c
->self
);
212 if (c
->ostate
!= CHAN_OUTPUT_CLOSED
||
213 c
->istate
!= CHAN_INPUT_CLOSED
) {
214 error("channel %d: cannot send close for istate/ostate %d/%d",
215 c
->self
, c
->istate
, c
->ostate
);
216 } else if (c
->flags
& CHAN_CLOSE_SENT
) {
217 error("channel %d: already sent close", c
->self
);
219 if (!c
->have_remote_id
)
220 fatal_f("channel %d: no remote_id", c
->self
);
221 if ((r
= sshpkt_start(ssh
, SSH2_MSG_CHANNEL_CLOSE
)) != 0 ||
222 (r
= sshpkt_put_u32(ssh
, c
->remote_id
)) != 0 ||
223 (r
= sshpkt_send(ssh
)) != 0)
224 fatal_fr(r
, "send CHANNEL_EOF");
225 c
->flags
|= CHAN_CLOSE_SENT
;
230 chan_send_eow2(struct ssh
*ssh
, Channel
*c
)
234 debug2("channel %d: send eow", c
->self
);
235 if (c
->ostate
== CHAN_OUTPUT_CLOSED
) {
236 error("channel %d: must not sent eow on closed output",
240 if (!(ssh
->compat
& SSH_NEW_OPENSSH
))
242 if (!c
->have_remote_id
)
243 fatal_f("channel %d: no remote_id", c
->self
);
244 if ((r
= sshpkt_start(ssh
, SSH2_MSG_CHANNEL_REQUEST
)) != 0 ||
245 (r
= sshpkt_put_u32(ssh
, c
->remote_id
)) != 0 ||
246 (r
= sshpkt_put_cstring(ssh
, "eow@openssh.com")) != 0 ||
247 (r
= sshpkt_put_u8(ssh
, 0)) != 0 ||
248 (r
= sshpkt_send(ssh
)) != 0)
249 fatal_fr(r
, "send CHANNEL_EOF");
255 chan_rcvd_ieof(struct ssh
*ssh
, Channel
*c
)
257 debug2("channel %d: rcvd eof", c
->self
);
258 c
->flags
|= CHAN_EOF_RCVD
;
259 if (c
->ostate
== CHAN_OUTPUT_OPEN
)
260 chan_set_ostate(c
, CHAN_OUTPUT_WAIT_DRAIN
);
261 if (c
->ostate
== CHAN_OUTPUT_WAIT_DRAIN
&&
262 sshbuf_len(c
->output
) == 0 &&
263 !CHANNEL_EFD_OUTPUT_ACTIVE(c
))
264 chan_obuf_empty(ssh
, c
);
268 chan_rcvd_oclose(struct ssh
*ssh
, Channel
*c
)
270 debug2("channel %d: rcvd close", c
->self
);
271 if (!(c
->flags
& CHAN_LOCAL
)) {
272 if (c
->flags
& CHAN_CLOSE_RCVD
)
273 error("channel %d: protocol error: close rcvd twice",
275 c
->flags
|= CHAN_CLOSE_RCVD
;
277 if (c
->type
== SSH_CHANNEL_LARVAL
) {
278 /* tear down larval channels immediately */
279 chan_set_ostate(c
, CHAN_OUTPUT_CLOSED
);
280 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
284 case CHAN_OUTPUT_OPEN
:
286 * wait until a data from the channel is consumed if a CLOSE
289 chan_set_ostate(c
, CHAN_OUTPUT_WAIT_DRAIN
);
293 case CHAN_INPUT_OPEN
:
294 chan_shutdown_read(ssh
, c
);
295 chan_shutdown_extended_read(ssh
, c
);
296 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
298 case CHAN_INPUT_WAIT_DRAIN
:
299 if (!(c
->flags
& CHAN_LOCAL
))
300 chan_send_eof2(ssh
, c
);
301 chan_shutdown_extended_read(ssh
, c
);
302 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
308 chan_write_failed(struct ssh
*ssh
, Channel
*c
)
310 debug2("channel %d: write failed", c
->self
);
312 case CHAN_OUTPUT_OPEN
:
313 case CHAN_OUTPUT_WAIT_DRAIN
:
314 chan_shutdown_write(ssh
, c
);
315 if (strcmp(c
->ctype
, "session") == 0)
316 chan_send_eow2(ssh
, c
);
317 chan_set_ostate(c
, CHAN_OUTPUT_CLOSED
);
320 error("channel %d: chan_write_failed for ostate %d",
327 chan_mark_dead(struct ssh
*ssh
, Channel
*c
)
329 c
->type
= SSH_CHANNEL_ZOMBIE
;
333 chan_is_dead(struct ssh
*ssh
, Channel
*c
, int do_send
)
335 if (c
->type
== SSH_CHANNEL_ZOMBIE
) {
336 debug2("channel %d: zombie", c
->self
);
339 if (c
->istate
!= CHAN_INPUT_CLOSED
|| c
->ostate
!= CHAN_OUTPUT_CLOSED
)
341 if ((ssh
->compat
& SSH_BUG_EXTEOF
) &&
342 c
->extended_usage
== CHAN_EXTENDED_WRITE
&&
344 sshbuf_len(c
->extended
) > 0) {
345 debug2("channel %d: active efd: %d len %zu",
346 c
->self
, c
->efd
, sshbuf_len(c
->extended
));
349 if (c
->flags
& CHAN_LOCAL
) {
350 debug2("channel %d: is dead (local)", c
->self
);
353 if (!(c
->flags
& CHAN_CLOSE_SENT
)) {
355 chan_send_close2(ssh
, c
);
357 /* channel would be dead if we sent a close */
358 if (c
->flags
& CHAN_CLOSE_RCVD
) {
359 debug2("channel %d: almost dead",
365 if ((c
->flags
& CHAN_CLOSE_SENT
) &&
366 (c
->flags
& CHAN_CLOSE_RCVD
)) {
367 debug2("channel %d: is dead", c
->self
);
375 chan_shutdown_write(struct ssh
*ssh
, Channel
*c
)
377 sshbuf_reset(c
->output
);
378 if (c
->type
== SSH_CHANNEL_LARVAL
)
380 /* shutdown failure is allowed if write failed already */
381 debug2_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])",
382 c
->self
, c
->istate
, c
->ostate
, c
->sock
, c
->wfd
, c
->efd
,
383 channel_format_extended_usage(c
));
385 if (shutdown(c
->sock
, SHUT_WR
) == -1) {
386 debug2_f("channel %d: shutdown() failed for "
387 "fd %d [i%d o%d]: %.100s", c
->self
, c
->sock
,
388 c
->istate
, c
->ostate
, strerror(errno
));
391 if (channel_close_fd(ssh
, c
, &c
->wfd
) < 0) {
392 logit_f("channel %d: close() failed for "
393 "fd %d [i%d o%d]: %.100s", c
->self
, c
->wfd
,
394 c
->istate
, c
->ostate
, strerror(errno
));
400 chan_shutdown_read(struct ssh
*ssh
, Channel
*c
)
402 if (c
->type
== SSH_CHANNEL_LARVAL
)
404 debug2_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])",
405 c
->self
, c
->istate
, c
->ostate
, c
->sock
, c
->rfd
, c
->efd
,
406 channel_format_extended_usage(c
));
409 * shutdown(sock, SHUT_READ) may return ENOTCONN if the
410 * write side has been closed already. (bug on Linux)
411 * HP-UX may return ENOTCONN also.
413 if (shutdown(c
->sock
, SHUT_RD
) == -1 && errno
!= ENOTCONN
) {
414 error_f("channel %d: shutdown() failed for "
415 "fd %d [i%d o%d]: %.100s", c
->self
, c
->sock
,
416 c
->istate
, c
->ostate
, strerror(errno
));
419 if (channel_close_fd(ssh
, c
, &c
->rfd
) < 0) {
420 logit_f("channel %d: close() failed for "
421 "fd %d [i%d o%d]: %.100s", c
->self
, c
->rfd
,
422 c
->istate
, c
->ostate
, strerror(errno
));
428 chan_shutdown_extended_read(struct ssh
*ssh
, Channel
*c
)
430 if (c
->type
== SSH_CHANNEL_LARVAL
|| c
->efd
== -1)
432 if (c
->extended_usage
!= CHAN_EXTENDED_READ
&&
433 c
->extended_usage
!= CHAN_EXTENDED_IGNORE
)
435 debug_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])",
436 c
->self
, c
->istate
, c
->ostate
, c
->sock
, c
->rfd
, c
->efd
,
437 channel_format_extended_usage(c
));
438 if (channel_close_fd(ssh
, c
, &c
->efd
) < 0) {
439 logit_f("channel %d: close() failed for "
440 "extended fd %d [i%d o%d]: %.100s", c
->self
, c
->efd
,
441 c
->istate
, c
->ostate
, strerror(errno
));