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));