nchan.c revision 192595 
1/* $OpenBSD: nchan.c,v 1.62 2008/11/07 18:50:18 stevesk Exp $ */
2/*
3 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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.
13 *
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.
24 */
25
26#include "includes.h"
27
28#include <sys/types.h>
29#include <sys/socket.h>
30
31#include <errno.h>
32#include <string.h>
33#include <stdarg.h>
34
35#include "openbsd-compat/sys-queue.h"
36#include "ssh1.h"
37#include "ssh2.h"
38#include "buffer.h"
39#include "packet.h"
40#include "channels.h"
41#include "compat.h"
42#include "log.h"
43
44/*
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
48 *
49 * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the
50 * tear down of channels:
51 *
52 * 1.3:	strict request-ack-protocol:
53 *	CLOSE	->
54 *		<-  CLOSE_CONFIRM
55 *
56 * 1.5:	uses variations of:
57 *	IEOF	->
58 *		<-  OCLOSE
59 *		<-  IEOF
60 *	OCLOSE	->
61 *	i.e. both sides have to close the channel
62 *
63 * 2.0: the EOF messages are optional
64 *
65 * See the debugging output from 'ssh -v' and 'sshd -d' of
66 * ssh-1.2.27 as an example.
67 *
68 */
69
70/* functions manipulating channel states */
71/*
72 * EVENTS update channel input/output states execute ACTIONS
73 */
74/*
75 * ACTIONS: should never update the channel states
76 */
77static void	chan_send_ieof1(Channel *);
78static void	chan_send_oclose1(Channel *);
79static void	chan_send_close2(Channel *);
80static void	chan_send_eof2(Channel *);
81static void	chan_send_eow2(Channel *);
82
83/* helper */
84static void	chan_shutdown_write(Channel *);
85static void	chan_shutdown_read(Channel *);
86
87static char *ostates[] = { "open", "drain", "wait_ieof", "closed" };
88static char *istates[] = { "open", "drain", "wait_oclose", "closed" };
89
90static void
91chan_set_istate(Channel *c, u_int next)
92{
93	if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED)
94		fatal("chan_set_istate: bad state %d -> %d", c->istate, next);
95	debug2("channel %d: input %s -> %s", c->self, istates[c->istate],
96	    istates[next]);
97	c->istate = next;
98}
99static void
100chan_set_ostate(Channel *c, u_int next)
101{
102	if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED)
103		fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next);
104	debug2("channel %d: output %s -> %s", c->self, ostates[c->ostate],
105	    ostates[next]);
106	c->ostate = next;
107}
108
109/*
110 * SSH1 specific implementation of event functions
111 */
112
113static void
114chan_rcvd_oclose1(Channel *c)
115{
116	debug2("channel %d: rcvd oclose", c->self);
117	switch (c->istate) {
118	case CHAN_INPUT_WAIT_OCLOSE:
119		chan_set_istate(c, CHAN_INPUT_CLOSED);
120		break;
121	case CHAN_INPUT_OPEN:
122		chan_shutdown_read(c);
123		chan_send_ieof1(c);
124		chan_set_istate(c, CHAN_INPUT_CLOSED);
125		break;
126	case CHAN_INPUT_WAIT_DRAIN:
127		/* both local read_failed and remote write_failed  */
128		chan_send_ieof1(c);
129		chan_set_istate(c, CHAN_INPUT_CLOSED);
130		break;
131	default:
132		error("channel %d: protocol error: rcvd_oclose for istate %d",
133		    c->self, c->istate);
134		return;
135	}
136}
137void
138chan_read_failed(Channel *c)
139{
140	debug2("channel %d: read failed", c->self);
141	switch (c->istate) {
142	case CHAN_INPUT_OPEN:
143		chan_shutdown_read(c);
144		chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN);
145		break;
146	default:
147		error("channel %d: chan_read_failed for istate %d",
148		    c->self, c->istate);
149		break;
150	}
151}
152void
153chan_ibuf_empty(Channel *c)
154{
155	debug2("channel %d: ibuf empty", c->self);
156	if (buffer_len(&c->input)) {
157		error("channel %d: chan_ibuf_empty for non empty buffer",
158		    c->self);
159		return;
160	}
161	switch (c->istate) {
162	case CHAN_INPUT_WAIT_DRAIN:
163		if (compat20) {
164			if (!(c->flags & CHAN_CLOSE_SENT))
165				chan_send_eof2(c);
166			chan_set_istate(c, CHAN_INPUT_CLOSED);
167		} else {
168			chan_send_ieof1(c);
169			chan_set_istate(c, CHAN_INPUT_WAIT_OCLOSE);
170		}
171		break;
172	default:
173		error("channel %d: chan_ibuf_empty for istate %d",
174		    c->self, c->istate);
175		break;
176	}
177}
178static void
179chan_rcvd_ieof1(Channel *c)
180{
181	debug2("channel %d: rcvd ieof", c->self);
182	switch (c->ostate) {
183	case CHAN_OUTPUT_OPEN:
184		chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
185		break;
186	case CHAN_OUTPUT_WAIT_IEOF:
187		chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
188		break;
189	default:
190		error("channel %d: protocol error: rcvd_ieof for ostate %d",
191		    c->self, c->ostate);
192		break;
193	}
194}
195static void
196chan_write_failed1(Channel *c)
197{
198	debug2("channel %d: write failed", c->self);
199	switch (c->ostate) {
200	case CHAN_OUTPUT_OPEN:
201		chan_shutdown_write(c);
202		chan_send_oclose1(c);
203		chan_set_ostate(c, CHAN_OUTPUT_WAIT_IEOF);
204		break;
205	case CHAN_OUTPUT_WAIT_DRAIN:
206		chan_shutdown_write(c);
207		chan_send_oclose1(c);
208		chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
209		break;
210	default:
211		error("channel %d: chan_write_failed for ostate %d",
212		    c->self, c->ostate);
213		break;
214	}
215}
216void
217chan_obuf_empty(Channel *c)
218{
219	debug2("channel %d: obuf empty", c->self);
220	if (buffer_len(&c->output)) {
221		error("channel %d: chan_obuf_empty for non empty buffer",
222		    c->self);
223		return;
224	}
225	switch (c->ostate) {
226	case CHAN_OUTPUT_WAIT_DRAIN:
227		chan_shutdown_write(c);
228		if (!compat20)
229			chan_send_oclose1(c);
230		chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
231		break;
232	default:
233		error("channel %d: internal error: obuf_empty for ostate %d",
234		    c->self, c->ostate);
235		break;
236	}
237}
238static void
239chan_send_ieof1(Channel *c)
240{
241	debug2("channel %d: send ieof", c->self);
242	switch (c->istate) {
243	case CHAN_INPUT_OPEN:
244	case CHAN_INPUT_WAIT_DRAIN:
245		packet_start(SSH_MSG_CHANNEL_INPUT_EOF);
246		packet_put_int(c->remote_id);
247		packet_send();
248		break;
249	default:
250		error("channel %d: cannot send ieof for istate %d",
251		    c->self, c->istate);
252		break;
253	}
254}
255static void
256chan_send_oclose1(Channel *c)
257{
258	debug2("channel %d: send oclose", c->self);
259	switch (c->ostate) {
260	case CHAN_OUTPUT_OPEN:
261	case CHAN_OUTPUT_WAIT_DRAIN:
262		buffer_clear(&c->output);
263		packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE);
264		packet_put_int(c->remote_id);
265		packet_send();
266		break;
267	default:
268		error("channel %d: cannot send oclose for ostate %d",
269		    c->self, c->ostate);
270		break;
271	}
272}
273
274/*
275 * the same for SSH2
276 */
277static void
278chan_rcvd_close2(Channel *c)
279{
280	debug2("channel %d: rcvd close", c->self);
281	if (c->flags & CHAN_CLOSE_RCVD)
282		error("channel %d: protocol error: close rcvd twice", c->self);
283	c->flags |= CHAN_CLOSE_RCVD;
284	if (c->type == SSH_CHANNEL_LARVAL) {
285		/* tear down larval channels immediately */
286		chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
287		chan_set_istate(c, CHAN_INPUT_CLOSED);
288		return;
289	}
290	switch (c->ostate) {
291	case CHAN_OUTPUT_OPEN:
292		/*
293		 * wait until a data from the channel is consumed if a CLOSE
294		 * is received
295		 */
296		chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
297		break;
298	}
299	switch (c->istate) {
300	case CHAN_INPUT_OPEN:
301		chan_shutdown_read(c);
302		chan_set_istate(c, CHAN_INPUT_CLOSED);
303		break;
304	case CHAN_INPUT_WAIT_DRAIN:
305		chan_send_eof2(c);
306		chan_set_istate(c, CHAN_INPUT_CLOSED);
307		break;
308	}
309}
310void
311chan_rcvd_eow(Channel *c)
312{
313	debug2("channel %d: rcvd eow", c->self);
314	switch (c->istate) {
315	case CHAN_INPUT_OPEN:
316		chan_shutdown_read(c);
317		chan_set_istate(c, CHAN_INPUT_CLOSED);
318		break;
319	}
320}
321static void
322chan_rcvd_eof2(Channel *c)
323{
324	debug2("channel %d: rcvd eof", c->self);
325	c->flags |= CHAN_EOF_RCVD;
326	if (c->ostate == CHAN_OUTPUT_OPEN)
327		chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
328}
329static void
330chan_write_failed2(Channel *c)
331{
332	debug2("channel %d: write failed", c->self);
333	switch (c->ostate) {
334	case CHAN_OUTPUT_OPEN:
335	case CHAN_OUTPUT_WAIT_DRAIN:
336		chan_shutdown_write(c);
337		if (strcmp(c->ctype, "session") == 0)
338			chan_send_eow2(c);
339		chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
340		break;
341	default:
342		error("channel %d: chan_write_failed for ostate %d",
343		    c->self, c->ostate);
344		break;
345	}
346}
347static void
348chan_send_eof2(Channel *c)
349{
350	debug2("channel %d: send eof", c->self);
351	switch (c->istate) {
352	case CHAN_INPUT_WAIT_DRAIN:
353		packet_start(SSH2_MSG_CHANNEL_EOF);
354		packet_put_int(c->remote_id);
355		packet_send();
356		c->flags |= CHAN_EOF_SENT;
357		break;
358	default:
359		error("channel %d: cannot send eof for istate %d",
360		    c->self, c->istate);
361		break;
362	}
363}
364static void
365chan_send_close2(Channel *c)
366{
367	debug2("channel %d: send close", c->self);
368	if (c->ostate != CHAN_OUTPUT_CLOSED ||
369	    c->istate != CHAN_INPUT_CLOSED) {
370		error("channel %d: cannot send close for istate/ostate %d/%d",
371		    c->self, c->istate, c->ostate);
372	} else if (c->flags & CHAN_CLOSE_SENT) {
373		error("channel %d: already sent close", c->self);
374	} else {
375		packet_start(SSH2_MSG_CHANNEL_CLOSE);
376		packet_put_int(c->remote_id);
377		packet_send();
378		c->flags |= CHAN_CLOSE_SENT;
379	}
380}
381static void
382chan_send_eow2(Channel *c)
383{
384	debug2("channel %d: send eow", c->self);
385	if (c->ostate == CHAN_OUTPUT_CLOSED) {
386		error("channel %d: must not sent eow on closed output",
387		    c->self);
388		return;
389	}
390	if (!(datafellows & SSH_NEW_OPENSSH))
391		return;
392	packet_start(SSH2_MSG_CHANNEL_REQUEST);
393	packet_put_int(c->remote_id);
394	packet_put_cstring("eow@openssh.com");
395	packet_put_char(0);
396	packet_send();
397}
398
399/* shared */
400
401void
402chan_rcvd_ieof(Channel *c)
403{
404	if (compat20)
405		chan_rcvd_eof2(c);
406	else
407		chan_rcvd_ieof1(c);
408	if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN &&
409	    buffer_len(&c->output) == 0 &&
410	    !CHANNEL_EFD_OUTPUT_ACTIVE(c))
411		chan_obuf_empty(c);
412}
413void
414chan_rcvd_oclose(Channel *c)
415{
416	if (compat20)
417		chan_rcvd_close2(c);
418	else
419		chan_rcvd_oclose1(c);
420}
421void
422chan_write_failed(Channel *c)
423{
424	if (compat20)
425		chan_write_failed2(c);
426	else
427		chan_write_failed1(c);
428}
429
430void
431chan_mark_dead(Channel *c)
432{
433	c->type = SSH_CHANNEL_ZOMBIE;
434}
435
436int
437chan_is_dead(Channel *c, int do_send)
438{
439	if (c->type == SSH_CHANNEL_ZOMBIE) {
440		debug2("channel %d: zombie", c->self);
441		return 1;
442	}
443	if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED)
444		return 0;
445	if (!compat20) {
446		debug2("channel %d: is dead", c->self);
447		return 1;
448	}
449	if ((datafellows & SSH_BUG_EXTEOF) &&
450	    c->extended_usage == CHAN_EXTENDED_WRITE &&
451	    c->efd != -1 &&
452	    buffer_len(&c->extended) > 0) {
453		debug2("channel %d: active efd: %d len %d",
454		    c->self, c->efd, buffer_len(&c->extended));
455		return 0;
456	}
457	if (!(c->flags & CHAN_CLOSE_SENT)) {
458		if (do_send) {
459			chan_send_close2(c);
460		} else {
461			/* channel would be dead if we sent a close */
462			if (c->flags & CHAN_CLOSE_RCVD) {
463				debug2("channel %d: almost dead",
464				    c->self);
465				return 1;
466			}
467		}
468	}
469	if ((c->flags & CHAN_CLOSE_SENT) &&
470	    (c->flags & CHAN_CLOSE_RCVD)) {
471		debug2("channel %d: is dead", c->self);
472		return 1;
473	}
474	return 0;
475}
476
477/* helper */
478static void
479chan_shutdown_write(Channel *c)
480{
481	buffer_clear(&c->output);
482	if (compat20 && c->type == SSH_CHANNEL_LARVAL)
483		return;
484	/* shutdown failure is allowed if write failed already */
485	debug2("channel %d: close_write", c->self);
486	if (c->sock != -1) {
487		if (shutdown(c->sock, SHUT_WR) < 0)
488			debug2("channel %d: chan_shutdown_write: "
489			    "shutdown() failed for fd %d: %.100s",
490			    c->self, c->sock, strerror(errno));
491	} else {
492		if (channel_close_fd(&c->wfd) < 0)
493			logit("channel %d: chan_shutdown_write: "
494			    "close() failed for fd %d: %.100s",
495			    c->self, c->wfd, strerror(errno));
496	}
497}
498static void
499chan_shutdown_read(Channel *c)
500{
501	if (compat20 && c->type == SSH_CHANNEL_LARVAL)
502		return;
503	debug2("channel %d: close_read", c->self);
504	if (c->sock != -1) {
505		/*
506		 * shutdown(sock, SHUT_READ) may return ENOTCONN if the
507		 * write side has been closed already. (bug on Linux)
508		 * HP-UX may return ENOTCONN also.
509		 */
510		if (shutdown(c->sock, SHUT_RD) < 0
511		    && errno != ENOTCONN)
512			error("channel %d: chan_shutdown_read: "
513			    "shutdown() failed for fd %d [i%d o%d]: %.100s",
514			    c->self, c->sock, c->istate, c->ostate,
515			    strerror(errno));
516	} else {
517		if (channel_close_fd(&c->rfd) < 0)
518			logit("channel %d: chan_shutdown_read: "
519			    "close() failed for fd %d: %.100s",
520			    c->self, c->rfd, strerror(errno));
521	}
522}
523