1 /* $OpenBSD: nchan.c,v 1.67 2017/09/12 06:35:32 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
*);
84 static const char *ostates
[] = { "open", "drain", "wait_ieof", "closed" };
85 static const char *istates
[] = { "open", "drain", "wait_oclose", "closed" };
88 chan_set_istate(Channel
*c
, u_int next
)
90 if (c
->istate
> CHAN_INPUT_CLOSED
|| next
> CHAN_INPUT_CLOSED
)
91 fatal("chan_set_istate: bad state %d -> %d", c
->istate
, next
);
92 debug2("channel %d: input %s -> %s", c
->self
, istates
[c
->istate
],
98 chan_set_ostate(Channel
*c
, u_int next
)
100 if (c
->ostate
> CHAN_OUTPUT_CLOSED
|| next
> CHAN_OUTPUT_CLOSED
)
101 fatal("chan_set_ostate: bad state %d -> %d", c
->ostate
, next
);
102 debug2("channel %d: output %s -> %s", c
->self
, ostates
[c
->ostate
],
108 chan_read_failed(struct ssh
*ssh
, Channel
*c
)
110 debug2("channel %d: read failed", c
->self
);
112 case CHAN_INPUT_OPEN
:
113 chan_shutdown_read(ssh
, c
);
114 chan_set_istate(c
, CHAN_INPUT_WAIT_DRAIN
);
117 error("channel %d: chan_read_failed for istate %d",
124 chan_ibuf_empty(struct ssh
*ssh
, Channel
*c
)
126 debug2("channel %d: ibuf empty", c
->self
);
127 if (sshbuf_len(c
->input
)) {
128 error("channel %d: chan_ibuf_empty for non empty buffer",
133 case CHAN_INPUT_WAIT_DRAIN
:
134 if (!(c
->flags
& (CHAN_CLOSE_SENT
|CHAN_LOCAL
)))
135 chan_send_eof2(ssh
, c
);
136 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
139 error("channel %d: chan_ibuf_empty for istate %d",
146 chan_obuf_empty(struct ssh
*ssh
, Channel
*c
)
148 debug2("channel %d: obuf empty", c
->self
);
149 if (sshbuf_len(c
->output
)) {
150 error("channel %d: chan_obuf_empty for non empty buffer",
155 case CHAN_OUTPUT_WAIT_DRAIN
:
156 chan_shutdown_write(ssh
, c
);
157 chan_set_ostate(c
, CHAN_OUTPUT_CLOSED
);
160 error("channel %d: internal error: obuf_empty for ostate %d",
167 chan_rcvd_eow(struct ssh
*ssh
, Channel
*c
)
169 debug2("channel %d: rcvd eow", c
->self
);
171 case CHAN_INPUT_OPEN
:
172 chan_shutdown_read(ssh
, c
);
173 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
179 chan_send_eof2(struct ssh
*ssh
, Channel
*c
)
183 debug2("channel %d: send eof", c
->self
);
185 case CHAN_INPUT_WAIT_DRAIN
:
186 if (!c
->have_remote_id
)
187 fatal("%s: channel %d: no remote_id",
189 if ((r
= sshpkt_start(ssh
, SSH2_MSG_CHANNEL_EOF
)) != 0 ||
190 (r
= sshpkt_put_u32(ssh
, c
->remote_id
)) != 0 ||
191 (r
= sshpkt_send(ssh
)) != 0)
192 fatal("%s: send CHANNEL_EOF: %s", __func__
, ssh_err(r
));
193 c
->flags
|= CHAN_EOF_SENT
;
196 error("channel %d: cannot send eof for istate %d",
203 chan_send_close2(struct ssh
*ssh
, Channel
*c
)
207 debug2("channel %d: send close", c
->self
);
208 if (c
->ostate
!= CHAN_OUTPUT_CLOSED
||
209 c
->istate
!= CHAN_INPUT_CLOSED
) {
210 error("channel %d: cannot send close for istate/ostate %d/%d",
211 c
->self
, c
->istate
, c
->ostate
);
212 } else if (c
->flags
& CHAN_CLOSE_SENT
) {
213 error("channel %d: already sent close", c
->self
);
215 if (!c
->have_remote_id
)
216 fatal("%s: channel %d: no remote_id",
218 if ((r
= sshpkt_start(ssh
, SSH2_MSG_CHANNEL_CLOSE
)) != 0 ||
219 (r
= sshpkt_put_u32(ssh
, c
->remote_id
)) != 0 ||
220 (r
= sshpkt_send(ssh
)) != 0)
221 fatal("%s: send CHANNEL_EOF: %s", __func__
, ssh_err(r
));
222 c
->flags
|= CHAN_CLOSE_SENT
;
227 chan_send_eow2(struct ssh
*ssh
, Channel
*c
)
231 debug2("channel %d: send eow", c
->self
);
232 if (c
->ostate
== CHAN_OUTPUT_CLOSED
) {
233 error("channel %d: must not sent eow on closed output",
237 if (!(datafellows
& SSH_NEW_OPENSSH
))
239 if (!c
->have_remote_id
)
240 fatal("%s: channel %d: no remote_id", __func__
, c
->self
);
241 if ((r
= sshpkt_start(ssh
, SSH2_MSG_CHANNEL_REQUEST
)) != 0 ||
242 (r
= sshpkt_put_u32(ssh
, c
->remote_id
)) != 0 ||
243 (r
= sshpkt_put_cstring(ssh
, "eow@openssh.com")) != 0 ||
244 (r
= sshpkt_put_u8(ssh
, 0)) != 0 ||
245 (r
= sshpkt_send(ssh
)) != 0)
246 fatal("%s: send CHANNEL_EOF: %s", __func__
, ssh_err(r
));
252 chan_rcvd_ieof(struct ssh
*ssh
, Channel
*c
)
254 debug2("channel %d: rcvd eof", c
->self
);
255 c
->flags
|= CHAN_EOF_RCVD
;
256 if (c
->ostate
== CHAN_OUTPUT_OPEN
)
257 chan_set_ostate(c
, CHAN_OUTPUT_WAIT_DRAIN
);
258 if (c
->ostate
== CHAN_OUTPUT_WAIT_DRAIN
&&
259 sshbuf_len(c
->output
) == 0 &&
260 !CHANNEL_EFD_OUTPUT_ACTIVE(c
))
261 chan_obuf_empty(ssh
, c
);
265 chan_rcvd_oclose(struct ssh
*ssh
, Channel
*c
)
267 debug2("channel %d: rcvd close", c
->self
);
268 if (!(c
->flags
& CHAN_LOCAL
)) {
269 if (c
->flags
& CHAN_CLOSE_RCVD
)
270 error("channel %d: protocol error: close rcvd twice",
272 c
->flags
|= CHAN_CLOSE_RCVD
;
274 if (c
->type
== SSH_CHANNEL_LARVAL
) {
275 /* tear down larval channels immediately */
276 chan_set_ostate(c
, CHAN_OUTPUT_CLOSED
);
277 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
281 case CHAN_OUTPUT_OPEN
:
283 * wait until a data from the channel is consumed if a CLOSE
286 chan_set_ostate(c
, CHAN_OUTPUT_WAIT_DRAIN
);
290 case CHAN_INPUT_OPEN
:
291 chan_shutdown_read(ssh
, c
);
292 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
294 case CHAN_INPUT_WAIT_DRAIN
:
295 if (!(c
->flags
& CHAN_LOCAL
))
296 chan_send_eof2(ssh
, c
);
297 chan_set_istate(c
, CHAN_INPUT_CLOSED
);
303 chan_write_failed(struct ssh
*ssh
, Channel
*c
)
305 debug2("channel %d: write failed", c
->self
);
307 case CHAN_OUTPUT_OPEN
:
308 case CHAN_OUTPUT_WAIT_DRAIN
:
309 chan_shutdown_write(ssh
, c
);
310 if (strcmp(c
->ctype
, "session") == 0)
311 chan_send_eow2(ssh
, c
);
312 chan_set_ostate(c
, CHAN_OUTPUT_CLOSED
);
315 error("channel %d: chan_write_failed for ostate %d",
322 chan_mark_dead(struct ssh
*ssh
, Channel
*c
)
324 c
->type
= SSH_CHANNEL_ZOMBIE
;
328 chan_is_dead(struct ssh
*ssh
, Channel
*c
, int do_send
)
330 if (c
->type
== SSH_CHANNEL_ZOMBIE
) {
331 debug2("channel %d: zombie", c
->self
);
334 if (c
->istate
!= CHAN_INPUT_CLOSED
|| c
->ostate
!= CHAN_OUTPUT_CLOSED
)
336 if ((datafellows
& SSH_BUG_EXTEOF
) &&
337 c
->extended_usage
== CHAN_EXTENDED_WRITE
&&
339 sshbuf_len(c
->extended
) > 0) {
340 debug2("channel %d: active efd: %d len %zu",
341 c
->self
, c
->efd
, sshbuf_len(c
->extended
));
344 if (c
->flags
& CHAN_LOCAL
) {
345 debug2("channel %d: is dead (local)", c
->self
);
348 if (!(c
->flags
& CHAN_CLOSE_SENT
)) {
350 chan_send_close2(ssh
, c
);
352 /* channel would be dead if we sent a close */
353 if (c
->flags
& CHAN_CLOSE_RCVD
) {
354 debug2("channel %d: almost dead",
360 if ((c
->flags
& CHAN_CLOSE_SENT
) &&
361 (c
->flags
& CHAN_CLOSE_RCVD
)) {
362 debug2("channel %d: is dead", c
->self
);
370 chan_shutdown_write(struct ssh
*ssh
, Channel
*c
)
372 sshbuf_reset(c
->output
);
373 if (c
->type
== SSH_CHANNEL_LARVAL
)
375 /* shutdown failure is allowed if write failed already */
376 debug2("channel %d: close_write", c
->self
);
378 if (shutdown(c
->sock
, SHUT_WR
) < 0)
379 debug2("channel %d: chan_shutdown_write: "
380 "shutdown() failed for fd %d: %.100s",
381 c
->self
, c
->sock
, strerror(errno
));
383 if (channel_close_fd(ssh
, &c
->wfd
) < 0)
384 logit("channel %d: chan_shutdown_write: "
385 "close() failed for fd %d: %.100s",
386 c
->self
, c
->wfd
, strerror(errno
));
391 chan_shutdown_read(struct ssh
*ssh
, Channel
*c
)
393 if (c
->type
== SSH_CHANNEL_LARVAL
)
395 debug2("channel %d: close_read", c
->self
);
398 * shutdown(sock, SHUT_READ) may return ENOTCONN if the
399 * write side has been closed already. (bug on Linux)
400 * HP-UX may return ENOTCONN also.
402 if (shutdown(c
->sock
, SHUT_RD
) < 0
403 && errno
!= ENOTCONN
)
404 error("channel %d: chan_shutdown_read: "
405 "shutdown() failed for fd %d [i%d o%d]: %.100s",
406 c
->self
, c
->sock
, c
->istate
, c
->ostate
,
409 if (channel_close_fd(ssh
, &c
->rfd
) < 0)
410 logit("channel %d: chan_shutdown_read: "
411 "close() failed for fd %d: %.100s",
412 c
->self
, c
->rfd
, strerror(errno
));