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1 | /* $OpenBSD: nchan.c,v 1.58 2008/05/08 12:02:23 djm 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 | */ | |
77 | static void chan_send_ieof1(Channel *); | |
78 | static void chan_send_oclose1(Channel *); | |
79 | static void chan_send_close2(Channel *); | |
80 | static void chan_send_eof2(Channel *); | |
81 | ||
82 | /* helper */ | |
83 | static void chan_shutdown_write(Channel *); | |
84 | static void chan_shutdown_read(Channel *); | |
85 | ||
86 | static char *ostates[] = { "open", "drain", "wait_ieof", "closed" }; | |
87 | static char *istates[] = { "open", "drain", "wait_oclose", "closed" }; | |
88 | ||
89 | static void | |
90 | chan_set_istate(Channel *c, u_int next) | |
91 | { | |
92 | if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED) | |
93 | fatal("chan_set_istate: bad state %d -> %d", c->istate, next); | |
94 | debug2("channel %d: input %s -> %s", c->self, istates[c->istate], | |
95 | istates[next]); | |
96 | c->istate = next; | |
97 | } | |
98 | static void | |
99 | chan_set_ostate(Channel *c, u_int next) | |
100 | { | |
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], | |
104 | ostates[next]); | |
105 | c->ostate = next; | |
106 | } | |
107 | ||
108 | /* | |
109 | * SSH1 specific implementation of event functions | |
110 | */ | |
111 | ||
112 | static void | |
113 | chan_rcvd_oclose1(Channel *c) | |
114 | { | |
115 | debug2("channel %d: rcvd oclose", c->self); | |
116 | switch (c->istate) { | |
117 | case CHAN_INPUT_WAIT_OCLOSE: | |
118 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
119 | break; | |
120 | case CHAN_INPUT_OPEN: | |
121 | chan_shutdown_read(c); | |
122 | chan_send_ieof1(c); | |
123 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
124 | break; | |
125 | case CHAN_INPUT_WAIT_DRAIN: | |
126 | /* both local read_failed and remote write_failed */ | |
127 | chan_send_ieof1(c); | |
128 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
129 | break; | |
130 | default: | |
131 | error("channel %d: protocol error: rcvd_oclose for istate %d", | |
132 | c->self, c->istate); | |
133 | return; | |
134 | } | |
135 | } | |
136 | void | |
137 | chan_read_failed(Channel *c) | |
138 | { | |
139 | debug2("channel %d: read failed", c->self); | |
140 | switch (c->istate) { | |
141 | case CHAN_INPUT_OPEN: | |
142 | chan_shutdown_read(c); | |
143 | chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN); | |
144 | break; | |
145 | default: | |
146 | error("channel %d: chan_read_failed for istate %d", | |
147 | c->self, c->istate); | |
148 | break; | |
149 | } | |
150 | } | |
151 | void | |
152 | chan_ibuf_empty(Channel *c) | |
153 | { | |
154 | debug2("channel %d: ibuf empty", c->self); | |
155 | if (buffer_len(&c->input)) { | |
156 | error("channel %d: chan_ibuf_empty for non empty buffer", | |
157 | c->self); | |
158 | return; | |
159 | } | |
160 | switch (c->istate) { | |
161 | case CHAN_INPUT_WAIT_DRAIN: | |
162 | if (compat20) { | |
163 | if (!(c->flags & CHAN_CLOSE_SENT)) | |
164 | chan_send_eof2(c); | |
165 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
166 | } else { | |
167 | chan_send_ieof1(c); | |
168 | chan_set_istate(c, CHAN_INPUT_WAIT_OCLOSE); | |
169 | } | |
170 | break; | |
171 | default: | |
172 | error("channel %d: chan_ibuf_empty for istate %d", | |
173 | c->self, c->istate); | |
174 | break; | |
175 | } | |
176 | } | |
177 | static void | |
178 | chan_rcvd_ieof1(Channel *c) | |
179 | { | |
180 | debug2("channel %d: rcvd ieof", c->self); | |
181 | switch (c->ostate) { | |
182 | case CHAN_OUTPUT_OPEN: | |
183 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
184 | break; | |
185 | case CHAN_OUTPUT_WAIT_IEOF: | |
186 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
187 | break; | |
188 | default: | |
189 | error("channel %d: protocol error: rcvd_ieof for ostate %d", | |
190 | c->self, c->ostate); | |
191 | break; | |
192 | } | |
193 | } | |
194 | static void | |
195 | chan_write_failed1(Channel *c) | |
196 | { | |
197 | debug2("channel %d: write failed", c->self); | |
198 | switch (c->ostate) { | |
199 | case CHAN_OUTPUT_OPEN: | |
200 | chan_shutdown_write(c); | |
201 | chan_send_oclose1(c); | |
202 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_IEOF); | |
203 | break; | |
204 | case CHAN_OUTPUT_WAIT_DRAIN: | |
205 | chan_shutdown_write(c); | |
206 | chan_send_oclose1(c); | |
207 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
208 | break; | |
209 | default: | |
210 | error("channel %d: chan_write_failed for ostate %d", | |
211 | c->self, c->ostate); | |
212 | break; | |
213 | } | |
214 | } | |
215 | void | |
216 | chan_obuf_empty(Channel *c) | |
217 | { | |
218 | debug2("channel %d: obuf empty", c->self); | |
219 | if (buffer_len(&c->output)) { | |
220 | error("channel %d: chan_obuf_empty for non empty buffer", | |
221 | c->self); | |
222 | return; | |
223 | } | |
224 | switch (c->ostate) { | |
225 | case CHAN_OUTPUT_WAIT_DRAIN: | |
226 | chan_shutdown_write(c); | |
227 | if (!compat20) | |
228 | chan_send_oclose1(c); | |
229 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
230 | break; | |
231 | default: | |
232 | error("channel %d: internal error: obuf_empty for ostate %d", | |
233 | c->self, c->ostate); | |
234 | break; | |
235 | } | |
236 | } | |
237 | static void | |
238 | chan_send_ieof1(Channel *c) | |
239 | { | |
240 | debug2("channel %d: send ieof", c->self); | |
241 | switch (c->istate) { | |
242 | case CHAN_INPUT_OPEN: | |
243 | case CHAN_INPUT_WAIT_DRAIN: | |
244 | packet_start(SSH_MSG_CHANNEL_INPUT_EOF); | |
245 | packet_put_int(c->remote_id); | |
246 | packet_send(); | |
247 | break; | |
248 | default: | |
249 | error("channel %d: cannot send ieof for istate %d", | |
250 | c->self, c->istate); | |
251 | break; | |
252 | } | |
253 | } | |
254 | static void | |
255 | chan_send_oclose1(Channel *c) | |
256 | { | |
257 | debug2("channel %d: send oclose", c->self); | |
258 | switch (c->ostate) { | |
259 | case CHAN_OUTPUT_OPEN: | |
260 | case CHAN_OUTPUT_WAIT_DRAIN: | |
261 | buffer_clear(&c->output); | |
262 | packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE); | |
263 | packet_put_int(c->remote_id); | |
264 | packet_send(); | |
265 | break; | |
266 | default: | |
267 | error("channel %d: cannot send oclose for ostate %d", | |
268 | c->self, c->ostate); | |
269 | break; | |
270 | } | |
271 | } | |
272 | ||
273 | /* | |
274 | * the same for SSH2 | |
275 | */ | |
276 | static void | |
277 | chan_rcvd_close2(Channel *c) | |
278 | { | |
279 | debug2("channel %d: rcvd close", c->self); | |
280 | if (c->flags & CHAN_CLOSE_RCVD) | |
281 | error("channel %d: protocol error: close rcvd twice", c->self); | |
282 | c->flags |= CHAN_CLOSE_RCVD; | |
283 | if (c->type == SSH_CHANNEL_LARVAL) { | |
284 | /* tear down larval channels immediately */ | |
285 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
286 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
287 | return; | |
288 | } | |
289 | switch (c->ostate) { | |
290 | case CHAN_OUTPUT_OPEN: | |
291 | /* | |
292 | * wait until a data from the channel is consumed if a CLOSE | |
293 | * is received | |
294 | */ | |
295 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
296 | break; | |
297 | } | |
298 | switch (c->istate) { | |
299 | case CHAN_INPUT_OPEN: | |
300 | chan_shutdown_read(c); | |
301 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
302 | break; | |
303 | case CHAN_INPUT_WAIT_DRAIN: | |
304 | chan_send_eof2(c); | |
305 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
306 | break; | |
307 | } | |
308 | } | |
309 | static void | |
310 | chan_rcvd_eof2(Channel *c) | |
311 | { | |
312 | debug2("channel %d: rcvd eof", c->self); | |
313 | c->flags |= CHAN_EOF_RCVD; | |
314 | if (c->ostate == CHAN_OUTPUT_OPEN) | |
315 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
316 | } | |
317 | static void | |
318 | chan_write_failed2(Channel *c) | |
319 | { | |
320 | debug2("channel %d: write failed", c->self); | |
321 | switch (c->ostate) { | |
322 | case CHAN_OUTPUT_OPEN: | |
323 | case CHAN_OUTPUT_WAIT_DRAIN: | |
324 | chan_shutdown_write(c); | |
325 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
326 | break; | |
327 | default: | |
328 | error("channel %d: chan_write_failed for ostate %d", | |
329 | c->self, c->ostate); | |
330 | break; | |
331 | } | |
332 | } | |
333 | static void | |
334 | chan_send_eof2(Channel *c) | |
335 | { | |
336 | debug2("channel %d: send eof", c->self); | |
337 | switch (c->istate) { | |
338 | case CHAN_INPUT_WAIT_DRAIN: | |
339 | packet_start(SSH2_MSG_CHANNEL_EOF); | |
340 | packet_put_int(c->remote_id); | |
341 | packet_send(); | |
342 | c->flags |= CHAN_EOF_SENT; | |
343 | break; | |
344 | default: | |
345 | error("channel %d: cannot send eof for istate %d", | |
346 | c->self, c->istate); | |
347 | break; | |
348 | } | |
349 | } | |
350 | static void | |
351 | chan_send_close2(Channel *c) | |
352 | { | |
353 | debug2("channel %d: send close", c->self); | |
354 | if (c->ostate != CHAN_OUTPUT_CLOSED || | |
355 | c->istate != CHAN_INPUT_CLOSED) { | |
356 | error("channel %d: cannot send close for istate/ostate %d/%d", | |
357 | c->self, c->istate, c->ostate); | |
358 | } else if (c->flags & CHAN_CLOSE_SENT) { | |
359 | error("channel %d: already sent close", c->self); | |
360 | } else { | |
361 | packet_start(SSH2_MSG_CHANNEL_CLOSE); | |
362 | packet_put_int(c->remote_id); | |
363 | packet_send(); | |
364 | c->flags |= CHAN_CLOSE_SENT; | |
365 | } | |
366 | } | |
367 | ||
368 | /* shared */ | |
369 | ||
370 | void | |
371 | chan_rcvd_ieof(Channel *c) | |
372 | { | |
373 | if (compat20) | |
374 | chan_rcvd_eof2(c); | |
375 | else | |
376 | chan_rcvd_ieof1(c); | |
377 | if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN && | |
378 | buffer_len(&c->output) == 0 && | |
379 | !CHANNEL_EFD_OUTPUT_ACTIVE(c)) | |
380 | chan_obuf_empty(c); | |
381 | } | |
382 | void | |
383 | chan_rcvd_oclose(Channel *c) | |
384 | { | |
385 | if (compat20) | |
386 | chan_rcvd_close2(c); | |
387 | else | |
388 | chan_rcvd_oclose1(c); | |
389 | } | |
390 | void | |
391 | chan_write_failed(Channel *c) | |
392 | { | |
393 | if (compat20) | |
394 | chan_write_failed2(c); | |
395 | else | |
396 | chan_write_failed1(c); | |
397 | } | |
398 | ||
399 | void | |
400 | chan_mark_dead(Channel *c) | |
401 | { | |
402 | c->type = SSH_CHANNEL_ZOMBIE; | |
403 | } | |
404 | ||
405 | int | |
406 | chan_is_dead(Channel *c, int do_send) | |
407 | { | |
408 | if (c->type == SSH_CHANNEL_ZOMBIE) { | |
409 | debug2("channel %d: zombie", c->self); | |
410 | return 1; | |
411 | } | |
412 | if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) | |
413 | return 0; | |
414 | if (!compat20) { | |
415 | debug2("channel %d: is dead", c->self); | |
416 | return 1; | |
417 | } | |
418 | if ((datafellows & SSH_BUG_EXTEOF) && | |
419 | c->extended_usage == CHAN_EXTENDED_WRITE && | |
420 | c->efd != -1 && | |
421 | buffer_len(&c->extended) > 0) { | |
422 | debug2("channel %d: active efd: %d len %d", | |
423 | c->self, c->efd, buffer_len(&c->extended)); | |
424 | return 0; | |
425 | } | |
426 | if (!(c->flags & CHAN_CLOSE_SENT)) { | |
427 | if (do_send) { | |
428 | chan_send_close2(c); | |
429 | } else { | |
430 | /* channel would be dead if we sent a close */ | |
431 | if (c->flags & CHAN_CLOSE_RCVD) { | |
432 | debug2("channel %d: almost dead", | |
433 | c->self); | |
434 | return 1; | |
435 | } | |
436 | } | |
437 | } | |
438 | if ((c->flags & CHAN_CLOSE_SENT) && | |
439 | (c->flags & CHAN_CLOSE_RCVD)) { | |
440 | debug2("channel %d: is dead", c->self); | |
441 | return 1; | |
442 | } | |
443 | return 0; | |
444 | } | |
445 | ||
446 | /* helper */ | |
447 | static void | |
448 | chan_shutdown_write(Channel *c) | |
449 | { | |
450 | buffer_clear(&c->output); | |
451 | if (compat20 && c->type == SSH_CHANNEL_LARVAL) | |
452 | return; | |
453 | /* shutdown failure is allowed if write failed already */ | |
454 | debug2("channel %d: close_write", c->self); | |
455 | if (c->sock != -1) { | |
456 | if (shutdown(c->sock, SHUT_WR) < 0) | |
457 | debug2("channel %d: chan_shutdown_write: " | |
458 | "shutdown() failed for fd%d: %.100s", | |
459 | c->self, c->sock, strerror(errno)); | |
460 | } else { | |
461 | if (channel_close_fd(&c->wfd) < 0) | |
462 | logit("channel %d: chan_shutdown_write: " | |
463 | "close() failed for fd%d: %.100s", | |
464 | c->self, c->wfd, strerror(errno)); | |
465 | } | |
466 | } | |
467 | static void | |
468 | chan_shutdown_read(Channel *c) | |
469 | { | |
470 | if (compat20 && c->type == SSH_CHANNEL_LARVAL) | |
471 | return; | |
472 | debug2("channel %d: close_read", c->self); | |
473 | if (c->sock != -1) { | |
474 | /* | |
475 | * shutdown(sock, SHUT_READ) may return ENOTCONN if the | |
476 | * write side has been closed already. (bug on Linux) | |
477 | * HP-UX may return ENOTCONN also. | |
478 | */ | |
479 | if (shutdown(c->sock, SHUT_RD) < 0 | |
480 | && errno != ENOTCONN) | |
481 | error("channel %d: chan_shutdown_read: " | |
482 | "shutdown() failed for fd%d [i%d o%d]: %.100s", | |
483 | c->self, c->sock, c->istate, c->ostate, | |
484 | strerror(errno)); | |
485 | } else { | |
486 | if (channel_close_fd(&c->rfd) < 0) | |
487 | logit("channel %d: chan_shutdown_read: " | |
488 | "close() failed for fd%d: %.100s", | |
489 | c->self, c->rfd, strerror(errno)); | |
490 | } | |
491 | } |