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1 | /* | |
2 | * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
26 | RCSID("$OpenBSD: nchan.c,v 1.47 2002/06/19 00:27:55 deraadt Exp $"); | |
27 | ||
28 | #include "ssh1.h" | |
29 | #include "ssh2.h" | |
30 | #include "buffer.h" | |
31 | #include "packet.h" | |
32 | #include "channels.h" | |
33 | #include "compat.h" | |
34 | #include "log.h" | |
35 | ||
36 | /* | |
37 | * SSH Protocol 1.5 aka New Channel Protocol | |
38 | * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored. | |
39 | * Written by Markus Friedl in October 1999 | |
40 | * | |
41 | * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the | |
42 | * tear down of channels: | |
43 | * | |
44 | * 1.3: strict request-ack-protocol: | |
45 | * CLOSE -> | |
46 | * <- CLOSE_CONFIRM | |
47 | * | |
48 | * 1.5: uses variations of: | |
49 | * IEOF -> | |
50 | * <- OCLOSE | |
51 | * <- IEOF | |
52 | * OCLOSE -> | |
53 | * i.e. both sides have to close the channel | |
54 | * | |
55 | * 2.0: the EOF messages are optional | |
56 | * | |
57 | * See the debugging output from 'ssh -v' and 'sshd -d' of | |
58 | * ssh-1.2.27 as an example. | |
59 | * | |
60 | */ | |
61 | ||
62 | /* functions manipulating channel states */ | |
63 | /* | |
64 | * EVENTS update channel input/output states execute ACTIONS | |
65 | */ | |
66 | /* | |
67 | * ACTIONS: should never update the channel states | |
68 | */ | |
69 | static void chan_send_ieof1(Channel *); | |
70 | static void chan_send_oclose1(Channel *); | |
71 | static void chan_send_close2(Channel *); | |
72 | static void chan_send_eof2(Channel *); | |
73 | ||
74 | /* helper */ | |
75 | static void chan_shutdown_write(Channel *); | |
76 | static void chan_shutdown_read(Channel *); | |
77 | ||
78 | static char *ostates[] = { "open", "drain", "wait_ieof", "closed" }; | |
79 | static char *istates[] = { "open", "drain", "wait_oclose", "closed" }; | |
80 | ||
81 | static void | |
82 | chan_set_istate(Channel *c, u_int next) | |
83 | { | |
84 | if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED) | |
85 | fatal("chan_set_istate: bad state %d -> %d", c->istate, next); | |
86 | debug("channel %d: input %s -> %s", c->self, istates[c->istate], | |
87 | istates[next]); | |
88 | c->istate = next; | |
89 | } | |
90 | static void | |
91 | chan_set_ostate(Channel *c, u_int next) | |
92 | { | |
93 | if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED) | |
94 | fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next); | |
95 | debug("channel %d: output %s -> %s", c->self, ostates[c->ostate], | |
96 | ostates[next]); | |
97 | c->ostate = next; | |
98 | } | |
99 | ||
100 | /* | |
101 | * SSH1 specific implementation of event functions | |
102 | */ | |
103 | ||
104 | static void | |
105 | chan_rcvd_oclose1(Channel *c) | |
106 | { | |
107 | debug("channel %d: rcvd oclose", c->self); | |
108 | switch (c->istate) { | |
109 | case CHAN_INPUT_WAIT_OCLOSE: | |
110 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
111 | break; | |
112 | case CHAN_INPUT_OPEN: | |
113 | chan_shutdown_read(c); | |
114 | chan_send_ieof1(c); | |
115 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
116 | break; | |
117 | case CHAN_INPUT_WAIT_DRAIN: | |
118 | /* both local read_failed and remote write_failed */ | |
119 | chan_send_ieof1(c); | |
120 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
121 | break; | |
122 | default: | |
123 | error("channel %d: protocol error: rcvd_oclose for istate %d", | |
124 | c->self, c->istate); | |
125 | return; | |
126 | } | |
127 | } | |
128 | void | |
129 | chan_read_failed(Channel *c) | |
130 | { | |
131 | debug("channel %d: read failed", c->self); | |
132 | switch (c->istate) { | |
133 | case CHAN_INPUT_OPEN: | |
134 | chan_shutdown_read(c); | |
135 | chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN); | |
136 | break; | |
137 | default: | |
138 | error("channel %d: chan_read_failed for istate %d", | |
139 | c->self, c->istate); | |
140 | break; | |
141 | } | |
142 | } | |
143 | void | |
144 | chan_ibuf_empty(Channel *c) | |
145 | { | |
146 | debug("channel %d: ibuf empty", c->self); | |
147 | if (buffer_len(&c->input)) { | |
148 | error("channel %d: chan_ibuf_empty for non empty buffer", | |
149 | c->self); | |
150 | return; | |
151 | } | |
152 | switch (c->istate) { | |
153 | case CHAN_INPUT_WAIT_DRAIN: | |
154 | if (compat20) { | |
155 | if (!(c->flags & CHAN_CLOSE_SENT)) | |
156 | chan_send_eof2(c); | |
157 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
158 | } else { | |
159 | chan_send_ieof1(c); | |
160 | chan_set_istate(c, CHAN_INPUT_WAIT_OCLOSE); | |
161 | } | |
162 | break; | |
163 | default: | |
164 | error("channel %d: chan_ibuf_empty for istate %d", | |
165 | c->self, c->istate); | |
166 | break; | |
167 | } | |
168 | } | |
169 | static void | |
170 | chan_rcvd_ieof1(Channel *c) | |
171 | { | |
172 | debug("channel %d: rcvd ieof", c->self); | |
173 | switch (c->ostate) { | |
174 | case CHAN_OUTPUT_OPEN: | |
175 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
176 | break; | |
177 | case CHAN_OUTPUT_WAIT_IEOF: | |
178 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
179 | break; | |
180 | default: | |
181 | error("channel %d: protocol error: rcvd_ieof for ostate %d", | |
182 | c->self, c->ostate); | |
183 | break; | |
184 | } | |
185 | } | |
186 | static void | |
187 | chan_write_failed1(Channel *c) | |
188 | { | |
189 | debug("channel %d: write failed", c->self); | |
190 | switch (c->ostate) { | |
191 | case CHAN_OUTPUT_OPEN: | |
192 | chan_shutdown_write(c); | |
193 | chan_send_oclose1(c); | |
194 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_IEOF); | |
195 | break; | |
196 | case CHAN_OUTPUT_WAIT_DRAIN: | |
197 | chan_shutdown_write(c); | |
198 | chan_send_oclose1(c); | |
199 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
200 | break; | |
201 | default: | |
202 | error("channel %d: chan_write_failed for ostate %d", | |
203 | c->self, c->ostate); | |
204 | break; | |
205 | } | |
206 | } | |
207 | void | |
208 | chan_obuf_empty(Channel *c) | |
209 | { | |
210 | debug("channel %d: obuf empty", c->self); | |
211 | if (buffer_len(&c->output)) { | |
212 | error("channel %d: chan_obuf_empty for non empty buffer", | |
213 | c->self); | |
214 | return; | |
215 | } | |
216 | switch (c->ostate) { | |
217 | case CHAN_OUTPUT_WAIT_DRAIN: | |
218 | chan_shutdown_write(c); | |
219 | if (!compat20) | |
220 | chan_send_oclose1(c); | |
221 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
222 | break; | |
223 | default: | |
224 | error("channel %d: internal error: obuf_empty for ostate %d", | |
225 | c->self, c->ostate); | |
226 | break; | |
227 | } | |
228 | } | |
229 | static void | |
230 | chan_send_ieof1(Channel *c) | |
231 | { | |
232 | debug("channel %d: send ieof", c->self); | |
233 | switch (c->istate) { | |
234 | case CHAN_INPUT_OPEN: | |
235 | case CHAN_INPUT_WAIT_DRAIN: | |
236 | packet_start(SSH_MSG_CHANNEL_INPUT_EOF); | |
237 | packet_put_int(c->remote_id); | |
238 | packet_send(); | |
239 | break; | |
240 | default: | |
241 | error("channel %d: cannot send ieof for istate %d", | |
242 | c->self, c->istate); | |
243 | break; | |
244 | } | |
245 | } | |
246 | static void | |
247 | chan_send_oclose1(Channel *c) | |
248 | { | |
249 | debug("channel %d: send oclose", c->self); | |
250 | switch (c->ostate) { | |
251 | case CHAN_OUTPUT_OPEN: | |
252 | case CHAN_OUTPUT_WAIT_DRAIN: | |
253 | buffer_clear(&c->output); | |
254 | packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE); | |
255 | packet_put_int(c->remote_id); | |
256 | packet_send(); | |
257 | break; | |
258 | default: | |
259 | error("channel %d: cannot send oclose for ostate %d", | |
260 | c->self, c->ostate); | |
261 | break; | |
262 | } | |
263 | } | |
264 | ||
265 | /* | |
266 | * the same for SSH2 | |
267 | */ | |
268 | static void | |
269 | chan_rcvd_close2(Channel *c) | |
270 | { | |
271 | debug("channel %d: rcvd close", c->self); | |
272 | if (c->flags & CHAN_CLOSE_RCVD) | |
273 | error("channel %d: protocol error: close rcvd twice", c->self); | |
274 | c->flags |= CHAN_CLOSE_RCVD; | |
275 | if (c->type == SSH_CHANNEL_LARVAL) { | |
276 | /* tear down larval channels immediately */ | |
277 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
278 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
279 | return; | |
280 | } | |
281 | switch (c->ostate) { | |
282 | case CHAN_OUTPUT_OPEN: | |
283 | /* | |
284 | * wait until a data from the channel is consumed if a CLOSE | |
285 | * is received | |
286 | */ | |
287 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
288 | break; | |
289 | } | |
290 | switch (c->istate) { | |
291 | case CHAN_INPUT_OPEN: | |
292 | chan_shutdown_read(c); | |
293 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
294 | break; | |
295 | case CHAN_INPUT_WAIT_DRAIN: | |
296 | chan_send_eof2(c); | |
297 | chan_set_istate(c, CHAN_INPUT_CLOSED); | |
298 | break; | |
299 | } | |
300 | } | |
301 | static void | |
302 | chan_rcvd_eof2(Channel *c) | |
303 | { | |
304 | debug("channel %d: rcvd eof", c->self); | |
305 | c->flags |= CHAN_EOF_RCVD; | |
306 | if (c->ostate == CHAN_OUTPUT_OPEN) | |
307 | chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); | |
308 | } | |
309 | static void | |
310 | chan_write_failed2(Channel *c) | |
311 | { | |
312 | debug("channel %d: write failed", c->self); | |
313 | switch (c->ostate) { | |
314 | case CHAN_OUTPUT_OPEN: | |
315 | case CHAN_OUTPUT_WAIT_DRAIN: | |
316 | chan_shutdown_write(c); | |
317 | chan_set_ostate(c, CHAN_OUTPUT_CLOSED); | |
318 | break; | |
319 | default: | |
320 | error("channel %d: chan_write_failed for ostate %d", | |
321 | c->self, c->ostate); | |
322 | break; | |
323 | } | |
324 | } | |
325 | static void | |
326 | chan_send_eof2(Channel *c) | |
327 | { | |
328 | debug("channel %d: send eof", c->self); | |
329 | switch (c->istate) { | |
330 | case CHAN_INPUT_WAIT_DRAIN: | |
331 | packet_start(SSH2_MSG_CHANNEL_EOF); | |
332 | packet_put_int(c->remote_id); | |
333 | packet_send(); | |
334 | c->flags |= CHAN_EOF_SENT; | |
335 | break; | |
336 | default: | |
337 | error("channel %d: cannot send eof for istate %d", | |
338 | c->self, c->istate); | |
339 | break; | |
340 | } | |
341 | } | |
342 | static void | |
343 | chan_send_close2(Channel *c) | |
344 | { | |
345 | debug("channel %d: send close", c->self); | |
346 | if (c->ostate != CHAN_OUTPUT_CLOSED || | |
347 | c->istate != CHAN_INPUT_CLOSED) { | |
348 | error("channel %d: cannot send close for istate/ostate %d/%d", | |
349 | c->self, c->istate, c->ostate); | |
350 | } else if (c->flags & CHAN_CLOSE_SENT) { | |
351 | error("channel %d: already sent close", c->self); | |
352 | } else { | |
353 | packet_start(SSH2_MSG_CHANNEL_CLOSE); | |
354 | packet_put_int(c->remote_id); | |
355 | packet_send(); | |
356 | c->flags |= CHAN_CLOSE_SENT; | |
357 | } | |
358 | } | |
359 | ||
360 | /* shared */ | |
361 | ||
362 | void | |
363 | chan_rcvd_ieof(Channel *c) | |
364 | { | |
365 | if (compat20) | |
366 | chan_rcvd_eof2(c); | |
367 | else | |
368 | chan_rcvd_ieof1(c); | |
369 | if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN && | |
370 | buffer_len(&c->output) == 0 && | |
371 | !CHANNEL_EFD_OUTPUT_ACTIVE(c)) | |
372 | chan_obuf_empty(c); | |
373 | } | |
374 | void | |
375 | chan_rcvd_oclose(Channel *c) | |
376 | { | |
377 | if (compat20) | |
378 | chan_rcvd_close2(c); | |
379 | else | |
380 | chan_rcvd_oclose1(c); | |
381 | } | |
382 | void | |
383 | chan_write_failed(Channel *c) | |
384 | { | |
385 | if (compat20) | |
386 | chan_write_failed2(c); | |
387 | else | |
388 | chan_write_failed1(c); | |
389 | } | |
390 | ||
391 | void | |
392 | chan_mark_dead(Channel *c) | |
393 | { | |
394 | c->type = SSH_CHANNEL_ZOMBIE; | |
395 | } | |
396 | ||
397 | int | |
398 | chan_is_dead(Channel *c, int send) | |
399 | { | |
400 | if (c->type == SSH_CHANNEL_ZOMBIE) { | |
401 | debug("channel %d: zombie", c->self); | |
402 | return 1; | |
403 | } | |
404 | if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) | |
405 | return 0; | |
406 | if (!compat20) { | |
407 | debug("channel %d: is dead", c->self); | |
408 | return 1; | |
409 | } | |
410 | if ((datafellows & SSH_BUG_EXTEOF) && | |
411 | c->extended_usage == CHAN_EXTENDED_WRITE && | |
412 | c->efd != -1 && | |
413 | buffer_len(&c->extended) > 0) { | |
414 | debug2("channel %d: active efd: %d len %d", | |
415 | c->self, c->efd, buffer_len(&c->extended)); | |
416 | return 0; | |
417 | } | |
418 | if (!(c->flags & CHAN_CLOSE_SENT)) { | |
419 | if (send) { | |
420 | chan_send_close2(c); | |
421 | } else { | |
422 | /* channel would be dead if we sent a close */ | |
423 | if (c->flags & CHAN_CLOSE_RCVD) { | |
424 | debug("channel %d: almost dead", | |
425 | c->self); | |
426 | return 1; | |
427 | } | |
428 | } | |
429 | } | |
430 | if ((c->flags & CHAN_CLOSE_SENT) && | |
431 | (c->flags & CHAN_CLOSE_RCVD)) { | |
432 | debug("channel %d: is dead", c->self); | |
433 | return 1; | |
434 | } | |
435 | return 0; | |
436 | } | |
437 | ||
438 | /* helper */ | |
439 | static void | |
440 | chan_shutdown_write(Channel *c) | |
441 | { | |
442 | buffer_clear(&c->output); | |
443 | if (compat20 && c->type == SSH_CHANNEL_LARVAL) | |
444 | return; | |
445 | /* shutdown failure is allowed if write failed already */ | |
446 | debug("channel %d: close_write", c->self); | |
447 | if (c->sock != -1) { | |
448 | if (shutdown(c->sock, SHUT_WR) < 0) | |
449 | debug("channel %d: chan_shutdown_write: " | |
450 | "shutdown() failed for fd%d: %.100s", | |
451 | c->self, c->sock, strerror(errno)); | |
452 | } else { | |
453 | if (channel_close_fd(&c->wfd) < 0) | |
454 | log("channel %d: chan_shutdown_write: " | |
455 | "close() failed for fd%d: %.100s", | |
456 | c->self, c->wfd, strerror(errno)); | |
457 | } | |
458 | } | |
459 | static void | |
460 | chan_shutdown_read(Channel *c) | |
461 | { | |
462 | if (compat20 && c->type == SSH_CHANNEL_LARVAL) | |
463 | return; | |
464 | debug("channel %d: close_read", c->self); | |
465 | if (c->sock != -1) { | |
466 | /* | |
467 | * shutdown(sock, SHUT_READ) may return ENOTCONN if the | |
468 | * write side has been closed already. (bug on Linux) | |
469 | * HP-UX may return ENOTCONN also. | |
470 | */ | |
471 | if (shutdown(c->sock, SHUT_RD) < 0 | |
472 | && errno != ENOTCONN) | |
473 | error("channel %d: chan_shutdown_read: " | |
474 | "shutdown() failed for fd%d [i%d o%d]: %.100s", | |
475 | c->self, c->sock, c->istate, c->ostate, | |
476 | strerror(errno)); | |
477 | } else { | |
478 | if (channel_close_fd(&c->rfd) < 0) | |
479 | log("channel %d: chan_shutdown_read: " | |
480 | "close() failed for fd%d: %.100s", | |
481 | c->self, c->rfd, strerror(errno)); | |
482 | } | |
483 | } |