1 /* $OpenBSD: nchan.c,v 1.73 2021/05/19 01:24:05 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 *ostates[] = { "open", "drain", "wait_ieof", "closed" };
86 static const char *istates[] = { "open", "drain", "wait_oclose", "closed" };
89 chan_set_istate(Channel *c, u_int next)
91 if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED)
92 fatal("chan_set_istate: bad state %d -> %d", c->istate, next);
93 debug2("channel %d: input %s -> %s", c->self, istates[c->istate],
99 chan_set_ostate(Channel *c, u_int next)
101 if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED)
102 fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next);
103 debug2("channel %d: output %s -> %s", c->self, ostates[c->ostate],
109 chan_read_failed(struct ssh *ssh, Channel *c)
111 debug2("channel %d: read failed", c->self);
113 case CHAN_INPUT_OPEN:
114 chan_shutdown_read(ssh, c);
115 chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN);
118 error("channel %d: chan_read_failed for istate %d",
125 chan_ibuf_empty(struct ssh *ssh, Channel *c)
127 debug2("channel %d: ibuf empty", c->self);
128 if (sshbuf_len(c->input)) {
129 error("channel %d: chan_ibuf_empty for non empty buffer",
134 case CHAN_INPUT_WAIT_DRAIN:
135 if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_LOCAL)))
136 chan_send_eof2(ssh, c);
137 chan_set_istate(c, CHAN_INPUT_CLOSED);
140 error("channel %d: chan_ibuf_empty for istate %d",
147 chan_obuf_empty(struct ssh *ssh, Channel *c)
149 debug2("channel %d: obuf empty", c->self);
150 if (sshbuf_len(c->output)) {
151 error("channel %d: chan_obuf_empty for non empty buffer",
156 case CHAN_OUTPUT_WAIT_DRAIN:
157 chan_shutdown_write(ssh, c);
158 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
161 error("channel %d: internal error: obuf_empty for ostate %d",
168 chan_rcvd_eow(struct ssh *ssh, Channel *c)
170 debug2("channel %d: rcvd eow", c->self);
172 case CHAN_INPUT_OPEN:
173 chan_shutdown_read(ssh, c);
174 chan_set_istate(c, CHAN_INPUT_CLOSED);
180 chan_send_eof2(struct ssh *ssh, Channel *c)
184 debug2("channel %d: send eof", c->self);
186 case CHAN_INPUT_WAIT_DRAIN:
187 if (!c->have_remote_id)
188 fatal_f("channel %d: no remote_id", c->self);
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_fr(r, "send CHANNEL_EOF");
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_f("channel %d: no remote_id", c->self);
217 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_CLOSE)) != 0 ||
218 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
219 (r = sshpkt_send(ssh)) != 0)
220 fatal_fr(r, "send CHANNEL_EOF");
221 c->flags |= CHAN_CLOSE_SENT;
226 chan_send_eow2(struct ssh *ssh, Channel *c)
230 debug2("channel %d: send eow", c->self);
231 if (c->ostate == CHAN_OUTPUT_CLOSED) {
232 error("channel %d: must not sent eow on closed output",
236 if (!(ssh->compat & SSH_NEW_OPENSSH))
238 if (!c->have_remote_id)
239 fatal_f("channel %d: no remote_id", c->self);
240 if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 ||
241 (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
242 (r = sshpkt_put_cstring(ssh, "eow@openssh.com")) != 0 ||
243 (r = sshpkt_put_u8(ssh, 0)) != 0 ||
244 (r = sshpkt_send(ssh)) != 0)
245 fatal_fr(r, "send CHANNEL_EOF");
251 chan_rcvd_ieof(struct ssh *ssh, Channel *c)
253 debug2("channel %d: rcvd eof", c->self);
254 c->flags |= CHAN_EOF_RCVD;
255 if (c->ostate == CHAN_OUTPUT_OPEN)
256 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
257 if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN &&
258 sshbuf_len(c->output) == 0 &&
259 !CHANNEL_EFD_OUTPUT_ACTIVE(c))
260 chan_obuf_empty(ssh, c);
264 chan_rcvd_oclose(struct ssh *ssh, Channel *c)
266 debug2("channel %d: rcvd close", c->self);
267 if (!(c->flags & CHAN_LOCAL)) {
268 if (c->flags & CHAN_CLOSE_RCVD)
269 error("channel %d: protocol error: close rcvd twice",
271 c->flags |= CHAN_CLOSE_RCVD;
273 if (c->type == SSH_CHANNEL_LARVAL) {
274 /* tear down larval channels immediately */
275 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
276 chan_set_istate(c, CHAN_INPUT_CLOSED);
280 case CHAN_OUTPUT_OPEN:
282 * wait until a data from the channel is consumed if a CLOSE
285 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
289 case CHAN_INPUT_OPEN:
290 chan_shutdown_read(ssh, c);
291 chan_shutdown_extended_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_shutdown_extended_read(ssh, c);
298 chan_set_istate(c, CHAN_INPUT_CLOSED);
304 chan_write_failed(struct ssh *ssh, Channel *c)
306 debug2("channel %d: write failed", c->self);
308 case CHAN_OUTPUT_OPEN:
309 case CHAN_OUTPUT_WAIT_DRAIN:
310 chan_shutdown_write(ssh, c);
311 if (strcmp(c->ctype, "session") == 0)
312 chan_send_eow2(ssh, c);
313 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
316 error("channel %d: chan_write_failed for ostate %d",
323 chan_mark_dead(struct ssh *ssh, Channel *c)
325 c->type = SSH_CHANNEL_ZOMBIE;
329 chan_is_dead(struct ssh *ssh, Channel *c, int do_send)
331 if (c->type == SSH_CHANNEL_ZOMBIE) {
332 debug2("channel %d: zombie", c->self);
335 if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED)
337 if ((ssh->compat & SSH_BUG_EXTEOF) &&
338 c->extended_usage == CHAN_EXTENDED_WRITE &&
340 sshbuf_len(c->extended) > 0) {
341 debug2("channel %d: active efd: %d len %zu",
342 c->self, c->efd, sshbuf_len(c->extended));
345 if (c->flags & CHAN_LOCAL) {
346 debug2("channel %d: is dead (local)", c->self);
349 if (!(c->flags & CHAN_CLOSE_SENT)) {
351 chan_send_close2(ssh, c);
353 /* channel would be dead if we sent a close */
354 if (c->flags & CHAN_CLOSE_RCVD) {
355 debug2("channel %d: almost dead",
361 if ((c->flags & CHAN_CLOSE_SENT) &&
362 (c->flags & CHAN_CLOSE_RCVD)) {
363 debug2("channel %d: is dead", c->self);
371 chan_shutdown_write(struct ssh *ssh, Channel *c)
373 sshbuf_reset(c->output);
374 if (c->type == SSH_CHANNEL_LARVAL)
376 /* shutdown failure is allowed if write failed already */
377 debug2_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])",
378 c->self, c->istate, c->ostate, c->sock, c->wfd, c->efd,
379 channel_format_extended_usage(c));
381 if (shutdown(c->sock, SHUT_WR) == -1) {
382 debug2_f("channel %d: shutdown() failed for "
383 "fd %d [i%d o%d]: %.100s", c->self, c->sock,
384 c->istate, c->ostate, strerror(errno));
387 if (channel_close_fd(ssh, c, &c->wfd) < 0) {
388 logit_f("channel %d: close() failed for "
389 "fd %d [i%d o%d]: %.100s", c->self, c->wfd,
390 c->istate, c->ostate, strerror(errno));
396 chan_shutdown_read(struct ssh *ssh, Channel *c)
398 if (c->type == SSH_CHANNEL_LARVAL)
400 debug2_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])",
401 c->self, c->istate, c->ostate, c->sock, c->rfd, c->efd,
402 channel_format_extended_usage(c));
405 * shutdown(sock, SHUT_READ) may return ENOTCONN if the
406 * write side has been closed already. (bug on Linux)
407 * HP-UX may return ENOTCONN also.
409 if (shutdown(c->sock, SHUT_RD) == -1 && errno != ENOTCONN) {
410 error_f("channel %d: shutdown() failed for "
411 "fd %d [i%d o%d]: %.100s", c->self, c->sock,
412 c->istate, c->ostate, strerror(errno));
415 if (channel_close_fd(ssh, c, &c->rfd) < 0) {
416 logit_f("channel %d: close() failed for "
417 "fd %d [i%d o%d]: %.100s", c->self, c->rfd,
418 c->istate, c->ostate, strerror(errno));
424 chan_shutdown_extended_read(struct ssh *ssh, Channel *c)
426 if (c->type == SSH_CHANNEL_LARVAL || c->efd == -1)
428 if (c->extended_usage != CHAN_EXTENDED_READ &&
429 c->extended_usage != CHAN_EXTENDED_IGNORE)
431 debug_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])",
432 c->self, c->istate, c->ostate, c->sock, c->rfd, c->efd,
433 channel_format_extended_usage(c));
434 if (channel_close_fd(ssh, c, &c->efd) < 0) {
435 logit_f("channel %d: close() failed for "
436 "extended fd %d [i%d o%d]: %.100s", c->self, c->efd,
437 c->istate, c->ostate, strerror(errno));