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1 | /* $OpenBSD: nchan.c,v 1.55 2006/07/11 20:07:25 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 | ||
33 | #include "ssh1.h" | |
34 | #include "ssh2.h" | |
35 | #include "buffer.h" | |
36 | #include "packet.h" | |
37 | #include "channels.h" | |
38 | #include "compat.h" | |
39 | #include "log.h" | |
40 | ||
41 | /* | |
42 | * SSH Protocol 1.5 aka New Channel Protocol | |
43 | * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored. | |
44 | * Written by Markus Friedl in October 1999 | |
45 | * | |
46 | * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the | |
47 | * tear down of channels: | |
48 | * | |
49 | * 1.3: strict request-ack-protocol: | |
50 | * CLOSE -> | |
51 | * <- CLOSE_CONFIRM | |
52 | * | |
53 | * 1.5: uses variations of: | |
54 | * IEOF -> | |
55 | * <- OCLOSE | |
56 | * <- IEOF | |
57 | * OCLOSE -> | |
58 | * i.e. both sides have to close the channel | |
59 | * | |
60 | * 2.0: the EOF messages are optional | |
61 | * | |
62 | * See the debugging output from 'ssh -v' and 'sshd -d' of | |
63 | * ssh-1.2.27 as an example. | |
64 | * | |
65 | */ | |
66 | ||
67 | /* functions manipulating channel states */ | |
68 | /* | |
69 | * EVENTS update channel input/output states execute ACTIONS | |
70 | */ | |
71 | /* | |
72 | * ACTIONS: should never update the channel states | |
73 | */ | |
74 | static void chan_send_ieof1(Channel *); | |
75 | static void chan_send_oclose1(Channel *); | |
76 | static void chan_send_close2(Channel *); | |
77 | static void chan_send_eof2(Channel *); | |
78 | ||
79 | /* helper */ | |
80 | static void chan_shutdown_write(Channel *); | |
81 | static void chan_shutdown_read(Channel *); | |
82 | ||
83 | static char *ostates[] = { "open", "drain", "wait_ieof", "closed" }; | |
84 | static char *istates[] = { "open", "drain", "wait_oclose", "closed" }; | |
85 | ||
86 | static void | |
87 | chan_set_istate(Channel *c, u_int next) | |
88 | { | |
89 | if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED) | |
90 | fatal("chan_set_istate: bad state %d -> %d", c->istate, next); | |
91 | debug2("channel %d: input %s -> %s", c->self, istates[c->istate], | |
92 | istates[next]); | |
93 | c->istate = next; | |
94 | } | |
95 | static void | |
96 | chan_set_ostate(Channel *c, u_int next) | |
97 | { | |
98 | if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED) | |
99 | fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next); | |
100 | debug2("channel %d: output %s -> %s", c->self, ostates[c->ostate], | |
101 | ostates[next]); | |
102 | c->ostate = next; | |
103 | } | |
104 | ||
105 | /* | |
106 | * SSH1 specific implementation of event functions | |
107 | */ | |
108 | ||
109 | static void | |
110 | chan_rcvd_oclose1(Channel *c) | |
111 | { | |
112 | debug2("channel %d: rcvd oclose", c->self); | |
113 | switch (c->istate) { | |
114 | case CHAN_INPUT_WAIT_OCLOSE: | |
115 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
116 | break; | |
117 | case CHAN_INPUT_OPEN: | |
118 | chan_shutdown_read(c); | |
119 | chan_send_ieof1(c); | |
120 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
121 | break; | |
122 | case CHAN_INPUT_WAIT_DRAIN: | |
123 | /* both local read_failed and remote write_failed */ | |
124 | chan_send_ieof1(c); | |
125 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
126 | break; | |
127 | default: | |
128 | error("channel %d: protocol error: rcvd_oclose for istate %d", | |
129 | c->self, c->istate); | |
130 | return; | |
131 | } | |
132 | } | |
133 | void | |
134 | chan_read_failed(Channel *c) | |
135 | { | |
136 | debug2("channel %d: read failed", c->self); | |
137 | switch (c->istate) { | |
138 | case CHAN_INPUT_OPEN: | |
139 | chan_shutdown_read(c); | |
140 | chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN); | |
141 | break; | |
142 | default: | |
143 | error("channel %d: chan_read_failed for istate %d", | |
144 | c->self, c->istate); | |
145 | break; | |
146 | } | |
147 | } | |
148 | void | |
149 | chan_ibuf_empty(Channel *c) | |
150 | { | |
151 | debug2("channel %d: ibuf empty", c->self); | |
152 | if (buffer_len(&c->input)) { | |
153 | error("channel %d: chan_ibuf_empty for non empty buffer", | |
154 | c->self); | |
155 | return; | |
156 | } | |
157 | switch (c->istate) { | |
158 | case CHAN_INPUT_WAIT_DRAIN: | |
159 | if (compat20) { | |
160 | if (!(c->flags & CHAN_CLOSE_SENT)) | |
161 | chan_send_eof2(c); | |
162 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
163 | } else { | |
164 | chan_send_ieof1(c); | |
165 | chan_set_istate(c, CHAN_INPUT_WAIT_OCLOSE); | |
166 | } | |
167 | break; | |
168 | default: | |
169 | error("channel %d: chan_ibuf_empty for istate %d", | |
170 | c->self, c->istate); | |
171 | break; | |
172 | } | |
173 | } | |
174 | static void | |
175 | chan_rcvd_ieof1(Channel *c) | |
176 | { | |
177 | debug2("channel %d: rcvd ieof", c->self); | |
178 | switch (c->ostate) { | |
179 | case CHAN_OUTPUT_OPEN: | |
180 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
181 | break; | |
182 | case CHAN_OUTPUT_WAIT_IEOF: | |
183 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
184 | break; | |
185 | default: | |
186 | error("channel %d: protocol error: rcvd_ieof for ostate %d", | |
187 | c->self, c->ostate); | |
188 | break; | |
189 | } | |
190 | } | |
191 | static void | |
192 | chan_write_failed1(Channel *c) | |
193 | { | |
194 | debug2("channel %d: write failed", c->self); | |
195 | switch (c->ostate) { | |
196 | case CHAN_OUTPUT_OPEN: | |
197 | chan_shutdown_write(c); | |
198 | chan_send_oclose1(c); | |
199 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_IEOF); | |
200 | break; | |
201 | case CHAN_OUTPUT_WAIT_DRAIN: | |
202 | chan_shutdown_write(c); | |
203 | chan_send_oclose1(c); | |
204 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
205 | break; | |
206 | default: | |
207 | error("channel %d: chan_write_failed for ostate %d", | |
208 | c->self, c->ostate); | |
209 | break; | |
210 | } | |
211 | } | |
212 | void | |
213 | chan_obuf_empty(Channel *c) | |
214 | { | |
215 | debug2("channel %d: obuf empty", c->self); | |
216 | if (buffer_len(&c->output)) { | |
217 | error("channel %d: chan_obuf_empty for non empty buffer", | |
218 | c->self); | |
219 | return; | |
220 | } | |
221 | switch (c->ostate) { | |
222 | case CHAN_OUTPUT_WAIT_DRAIN: | |
223 | chan_shutdown_write(c); | |
224 | if (!compat20) | |
225 | chan_send_oclose1(c); | |
226 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
227 | break; | |
228 | default: | |
229 | error("channel %d: internal error: obuf_empty for ostate %d", | |
230 | c->self, c->ostate); | |
231 | break; | |
232 | } | |
233 | } | |
234 | static void | |
235 | chan_send_ieof1(Channel *c) | |
236 | { | |
237 | debug2("channel %d: send ieof", c->self); | |
238 | switch (c->istate) { | |
239 | case CHAN_INPUT_OPEN: | |
240 | case CHAN_INPUT_WAIT_DRAIN: | |
241 | packet_start(SSH_MSG_CHANNEL_INPUT_EOF); | |
242 | packet_put_int(c->remote_id); | |
243 | packet_send(); | |
244 | break; | |
245 | default: | |
246 | error("channel %d: cannot send ieof for istate %d", | |
247 | c->self, c->istate); | |
248 | break; | |
249 | } | |
250 | } | |
251 | static void | |
252 | chan_send_oclose1(Channel *c) | |
253 | { | |
254 | debug2("channel %d: send oclose", c->self); | |
255 | switch (c->ostate) { | |
256 | case CHAN_OUTPUT_OPEN: | |
257 | case CHAN_OUTPUT_WAIT_DRAIN: | |
258 | buffer_clear(&c->output); | |
259 | packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE); | |
260 | packet_put_int(c->remote_id); | |
261 | packet_send(); | |
262 | break; | |
263 | default: | |
264 | error("channel %d: cannot send oclose for ostate %d", | |
265 | c->self, c->ostate); | |
266 | break; | |
267 | } | |
268 | } | |
269 | ||
270 | /* | |
271 | * the same for SSH2 | |
272 | */ | |
273 | static void | |
274 | chan_rcvd_close2(Channel *c) | |
275 | { | |
276 | debug2("channel %d: rcvd close", c->self); | |
277 | if (c->flags & CHAN_CLOSE_RCVD) | |
278 | error("channel %d: protocol error: close rcvd twice", c->self); | |
279 | c->flags |= CHAN_CLOSE_RCVD; | |
280 | if (c->type == SSH_CHANNEL_LARVAL) { | |
281 | /* tear down larval channels immediately */ | |
282 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
283 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
284 | return; | |
285 | } | |
286 | switch (c->ostate) { | |
287 | case CHAN_OUTPUT_OPEN: | |
288 | /* | |
289 | * wait until a data from the channel is consumed if a CLOSE | |
290 | * is received | |
291 | */ | |
292 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
293 | break; | |
294 | } | |
295 | switch (c->istate) { | |
296 | case CHAN_INPUT_OPEN: | |
297 | chan_shutdown_read(c); | |
298 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
299 | break; | |
300 | case CHAN_INPUT_WAIT_DRAIN: | |
301 | chan_send_eof2(c); | |
302 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
303 | break; | |
304 | } | |
305 | } | |
306 | static void | |
307 | chan_rcvd_eof2(Channel *c) | |
308 | { | |
309 | debug2("channel %d: rcvd eof", c->self); | |
310 | c->flags |= CHAN_EOF_RCVD; | |
311 | if (c->ostate == CHAN_OUTPUT_OPEN) | |
312 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
313 | } | |
314 | static void | |
315 | chan_write_failed2(Channel *c) | |
316 | { | |
317 | debug2("channel %d: write failed", c->self); | |
318 | switch (c->ostate) { | |
319 | case CHAN_OUTPUT_OPEN: | |
320 | case CHAN_OUTPUT_WAIT_DRAIN: | |
321 | chan_shutdown_write(c); | |
322 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
323 | break; | |
324 | default: | |
325 | error("channel %d: chan_write_failed for ostate %d", | |
326 | c->self, c->ostate); | |
327 | break; | |
328 | } | |
329 | } | |
330 | static void | |
331 | chan_send_eof2(Channel *c) | |
332 | { | |
333 | debug2("channel %d: send eof", c->self); | |
334 | switch (c->istate) { | |
335 | case CHAN_INPUT_WAIT_DRAIN: | |
336 | packet_start(SSH2_MSG_CHANNEL_EOF); | |
337 | packet_put_int(c->remote_id); | |
338 | packet_send(); | |
339 | c->flags |= CHAN_EOF_SENT; | |
340 | break; | |
341 | default: | |
342 | error("channel %d: cannot send eof for istate %d", | |
343 | c->self, c->istate); | |
344 | break; | |
345 | } | |
346 | } | |
347 | static void | |
348 | chan_send_close2(Channel *c) | |
349 | { | |
350 | debug2("channel %d: send close", c->self); | |
351 | if (c->ostate != CHAN_OUTPUT_CLOSED || | |
352 | c->istate != CHAN_INPUT_CLOSED) { | |
353 | error("channel %d: cannot send close for istate/ostate %d/%d", | |
354 | c->self, c->istate, c->ostate); | |
355 | } else if (c->flags & CHAN_CLOSE_SENT) { | |
356 | error("channel %d: already sent close", c->self); | |
357 | } else { | |
358 | packet_start(SSH2_MSG_CHANNEL_CLOSE); | |
359 | packet_put_int(c->remote_id); | |
360 | packet_send(); | |
361 | c->flags |= CHAN_CLOSE_SENT; | |
362 | } | |
363 | } | |
364 | ||
365 | /* shared */ | |
366 | ||
367 | void | |
368 | chan_rcvd_ieof(Channel *c) | |
369 | { | |
370 | if (compat20) | |
371 | chan_rcvd_eof2(c); | |
372 | else | |
373 | chan_rcvd_ieof1(c); | |
374 | if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN && | |
375 | buffer_len(&c->output) == 0 && | |
376 | !CHANNEL_EFD_OUTPUT_ACTIVE(c)) | |
377 | chan_obuf_empty(c); | |
378 | } | |
379 | void | |
380 | chan_rcvd_oclose(Channel *c) | |
381 | { | |
382 | if (compat20) | |
383 | chan_rcvd_close2(c); | |
384 | else | |
385 | chan_rcvd_oclose1(c); | |
386 | } | |
387 | void | |
388 | chan_write_failed(Channel *c) | |
389 | { | |
390 | if (compat20) | |
391 | chan_write_failed2(c); | |
392 | else | |
393 | chan_write_failed1(c); | |
394 | } | |
395 | ||
396 | void | |
397 | chan_mark_dead(Channel *c) | |
398 | { | |
399 | c->type = SSH_CHANNEL_ZOMBIE; | |
400 | } | |
401 | ||
402 | int | |
403 | chan_is_dead(Channel *c, int do_send) | |
404 | { | |
405 | if (c->type == SSH_CHANNEL_ZOMBIE) { | |
406 | debug2("channel %d: zombie", c->self); | |
407 | return 1; | |
408 | } | |
409 | if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) | |
410 | return 0; | |
411 | if (!compat20) { | |
412 | debug2("channel %d: is dead", c->self); | |
413 | return 1; | |
414 | } | |
415 | if ((datafellows & SSH_BUG_EXTEOF) && | |
416 | c->extended_usage == CHAN_EXTENDED_WRITE && | |
417 | c->efd != -1 && | |
418 | buffer_len(&c->extended) > 0) { | |
419 | debug2("channel %d: active efd: %d len %d", | |
420 | c->self, c->efd, buffer_len(&c->extended)); | |
421 | return 0; | |
422 | } | |
423 | if (!(c->flags & CHAN_CLOSE_SENT)) { | |
424 | if (do_send) { | |
425 | chan_send_close2(c); | |
426 | } else { | |
427 | /* channel would be dead if we sent a close */ | |
428 | if (c->flags & CHAN_CLOSE_RCVD) { | |
429 | debug2("channel %d: almost dead", | |
430 | c->self); | |
431 | return 1; | |
432 | } | |
433 | } | |
434 | } | |
435 | if ((c->flags & CHAN_CLOSE_SENT) && | |
436 | (c->flags & CHAN_CLOSE_RCVD)) { | |
437 | debug2("channel %d: is dead", c->self); | |
438 | return 1; | |
439 | } | |
440 | return 0; | |
441 | } | |
442 | ||
443 | /* helper */ | |
444 | static void | |
445 | chan_shutdown_write(Channel *c) | |
446 | { | |
447 | buffer_clear(&c->output); | |
448 | if (compat20 && c->type == SSH_CHANNEL_LARVAL) | |
449 | return; | |
450 | /* shutdown failure is allowed if write failed already */ | |
451 | debug2("channel %d: close_write", c->self); | |
452 | if (c->sock != -1) { | |
453 | if (shutdown(c->sock, SHUT_WR) < 0) | |
454 | debug2("channel %d: chan_shutdown_write: " | |
455 | "shutdown() failed for fd%d: %.100s", | |
456 | c->self, c->sock, strerror(errno)); | |
457 | } else { | |
458 | if (channel_close_fd(&c->wfd) < 0) | |
459 | logit("channel %d: chan_shutdown_write: " | |
460 | "close() failed for fd%d: %.100s", | |
461 | c->self, c->wfd, strerror(errno)); | |
462 | } | |
463 | } | |
464 | static void | |
465 | chan_shutdown_read(Channel *c) | |
466 | { | |
467 | if (compat20 && c->type == SSH_CHANNEL_LARVAL) | |
468 | return; | |
469 | debug2("channel %d: close_read", c->self); | |
470 | if (c->sock != -1) { | |
471 | /* | |
472 | * shutdown(sock, SHUT_READ) may return ENOTCONN if the | |
473 | * write side has been closed already. (bug on Linux) | |
474 | * HP-UX may return ENOTCONN also. | |
475 | */ | |
476 | if (shutdown(c->sock, SHUT_RD) < 0 | |
477 | && errno != ENOTCONN) | |
478 | error("channel %d: chan_shutdown_read: " | |
479 | "shutdown() failed for fd%d [i%d o%d]: %.100s", | |
480 | c->self, c->sock, c->istate, c->ostate, | |
481 | strerror(errno)); | |
482 | } else { | |
483 | if (channel_close_fd(&c->rfd) < 0) | |
484 | logit("channel %d: chan_shutdown_read: " | |
485 | "close() failed for fd%d: %.100s", | |
486 | c->self, c->rfd, strerror(errno)); | |
487 | } | |
488 | } |