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3c0ef626 | 1 | /* |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Server main loop for handling the interactive session. | |
6 | * | |
7 | * As far as I am concerned, the code I have written for this software | |
8 | * can be used freely for any purpose. Any derived versions of this | |
9 | * software must be clearly marked as such, and if the derived work is | |
10 | * incompatible with the protocol description in the RFC file, it must be | |
11 | * called by a name other than "ssh" or "Secure Shell". | |
12 | * | |
13 | * SSH2 support by Markus Friedl. | |
14 | * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. | |
15 | * | |
16 | * Redistribution and use in source and binary forms, with or without | |
17 | * modification, are permitted provided that the following conditions | |
18 | * are met: | |
19 | * 1. Redistributions of source code must retain the above copyright | |
20 | * notice, this list of conditions and the following disclaimer. | |
21 | * 2. Redistributions in binary form must reproduce the above copyright | |
22 | * notice, this list of conditions and the following disclaimer in the | |
23 | * documentation and/or other materials provided with the distribution. | |
24 | * | |
25 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
26 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
27 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
28 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
29 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
30 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
31 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
32 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
33 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
34 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
35 | */ | |
36 | ||
37 | #include "includes.h" | |
1e608e42 | 38 | RCSID("$OpenBSD: serverloop.c,v 1.98 2002/02/06 14:55:16 markus Exp $"); |
3c0ef626 | 39 | |
40 | #include "xmalloc.h" | |
41 | #include "packet.h" | |
42 | #include "buffer.h" | |
43 | #include "log.h" | |
44 | #include "servconf.h" | |
45 | #include "sshpty.h" | |
46 | #include "channels.h" | |
47 | #include "compat.h" | |
48 | #include "ssh1.h" | |
49 | #include "ssh2.h" | |
50 | #include "auth.h" | |
51 | #include "session.h" | |
52 | #include "dispatch.h" | |
53 | #include "auth-options.h" | |
54 | #include "serverloop.h" | |
55 | #include "misc.h" | |
56 | #include "kex.h" | |
57 | ||
58 | extern ServerOptions options; | |
59 | ||
60 | /* XXX */ | |
61 | extern Kex *xxx_kex; | |
62 | static Authctxt *xxx_authctxt; | |
63 | ||
64 | static Buffer stdin_buffer; /* Buffer for stdin data. */ | |
65 | static Buffer stdout_buffer; /* Buffer for stdout data. */ | |
66 | static Buffer stderr_buffer; /* Buffer for stderr data. */ | |
67 | static int fdin; /* Descriptor for stdin (for writing) */ | |
68 | static int fdout; /* Descriptor for stdout (for reading); | |
69 | May be same number as fdin. */ | |
70 | static int fderr; /* Descriptor for stderr. May be -1. */ | |
71 | static long stdin_bytes = 0; /* Number of bytes written to stdin. */ | |
72 | static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ | |
73 | static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ | |
74 | static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ | |
75 | static int stdin_eof = 0; /* EOF message received from client. */ | |
76 | static int fdout_eof = 0; /* EOF encountered reading from fdout. */ | |
77 | static int fderr_eof = 0; /* EOF encountered readung from fderr. */ | |
78 | static int fdin_is_tty = 0; /* fdin points to a tty. */ | |
79 | static int connection_in; /* Connection to client (input). */ | |
80 | static int connection_out; /* Connection to client (output). */ | |
81 | static int connection_closed = 0; /* Connection to client closed. */ | |
82 | static u_int buffer_high; /* "Soft" max buffer size. */ | |
83 | static int client_alive_timeouts = 0; | |
84 | ||
85 | /* | |
86 | * This SIGCHLD kludge is used to detect when the child exits. The server | |
87 | * will exit after that, as soon as forwarded connections have terminated. | |
88 | */ | |
89 | ||
1e608e42 | 90 | static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ |
3c0ef626 | 91 | |
92 | /* prototypes */ | |
93 | static void server_init_dispatch(void); | |
94 | ||
1e608e42 | 95 | /* |
96 | * we write to this pipe if a SIGCHLD is caught in order to avoid | |
97 | * the race between select() and child_terminated | |
98 | */ | |
99 | static int notify_pipe[2]; | |
100 | static void | |
101 | notify_setup(void) | |
102 | { | |
103 | if (pipe(notify_pipe) < 0) { | |
104 | error("pipe(notify_pipe) failed %s", strerror(errno)); | |
105 | } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || | |
106 | (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { | |
107 | error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); | |
108 | close(notify_pipe[0]); | |
109 | close(notify_pipe[1]); | |
110 | } else { | |
111 | set_nonblock(notify_pipe[0]); | |
112 | set_nonblock(notify_pipe[1]); | |
113 | return; | |
114 | } | |
115 | notify_pipe[0] = -1; /* read end */ | |
116 | notify_pipe[1] = -1; /* write end */ | |
117 | } | |
118 | static void | |
119 | notify_parent(void) | |
120 | { | |
121 | if (notify_pipe[1] != -1) | |
122 | write(notify_pipe[1], "", 1); | |
123 | } | |
124 | static void | |
125 | notify_prepare(fd_set *readset) | |
126 | { | |
127 | if (notify_pipe[0] != -1) | |
128 | FD_SET(notify_pipe[0], readset); | |
129 | } | |
130 | static void | |
131 | notify_done(fd_set *readset) | |
132 | { | |
133 | char c; | |
134 | ||
135 | if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) | |
136 | while (read(notify_pipe[0], &c, 1) != -1) | |
137 | debug2("notify_done: reading"); | |
138 | } | |
139 | ||
3c0ef626 | 140 | static void |
141 | sigchld_handler(int sig) | |
142 | { | |
143 | int save_errno = errno; | |
144 | debug("Received SIGCHLD."); | |
145 | child_terminated = 1; | |
146 | mysignal(SIGCHLD, sigchld_handler); | |
1e608e42 | 147 | notify_parent(); |
3c0ef626 | 148 | errno = save_errno; |
149 | } | |
150 | ||
151 | /* | |
152 | * Make packets from buffered stderr data, and buffer it for sending | |
153 | * to the client. | |
154 | */ | |
155 | static void | |
156 | make_packets_from_stderr_data(void) | |
157 | { | |
158 | int len; | |
159 | ||
160 | /* Send buffered stderr data to the client. */ | |
161 | while (buffer_len(&stderr_buffer) > 0 && | |
162 | packet_not_very_much_data_to_write()) { | |
163 | len = buffer_len(&stderr_buffer); | |
164 | if (packet_is_interactive()) { | |
165 | if (len > 512) | |
166 | len = 512; | |
167 | } else { | |
168 | /* Keep the packets at reasonable size. */ | |
169 | if (len > packet_get_maxsize()) | |
170 | len = packet_get_maxsize(); | |
171 | } | |
172 | packet_start(SSH_SMSG_STDERR_DATA); | |
173 | packet_put_string(buffer_ptr(&stderr_buffer), len); | |
174 | packet_send(); | |
175 | buffer_consume(&stderr_buffer, len); | |
176 | stderr_bytes += len; | |
177 | } | |
178 | } | |
179 | ||
180 | /* | |
181 | * Make packets from buffered stdout data, and buffer it for sending to the | |
182 | * client. | |
183 | */ | |
184 | static void | |
185 | make_packets_from_stdout_data(void) | |
186 | { | |
187 | int len; | |
188 | ||
189 | /* Send buffered stdout data to the client. */ | |
190 | while (buffer_len(&stdout_buffer) > 0 && | |
191 | packet_not_very_much_data_to_write()) { | |
192 | len = buffer_len(&stdout_buffer); | |
193 | if (packet_is_interactive()) { | |
194 | if (len > 512) | |
195 | len = 512; | |
196 | } else { | |
197 | /* Keep the packets at reasonable size. */ | |
198 | if (len > packet_get_maxsize()) | |
199 | len = packet_get_maxsize(); | |
200 | } | |
201 | packet_start(SSH_SMSG_STDOUT_DATA); | |
202 | packet_put_string(buffer_ptr(&stdout_buffer), len); | |
203 | packet_send(); | |
204 | buffer_consume(&stdout_buffer, len); | |
205 | stdout_bytes += len; | |
206 | } | |
207 | } | |
208 | ||
209 | static void | |
210 | client_alive_check(void) | |
211 | { | |
1e608e42 | 212 | static int had_channel = 0; |
3c0ef626 | 213 | int id; |
214 | ||
1e608e42 | 215 | id = channel_find_open(); |
216 | if (id == -1) { | |
217 | if (!had_channel) | |
218 | return; | |
219 | packet_disconnect("No open channels after timeout!"); | |
220 | } | |
221 | had_channel = 1; | |
222 | ||
3c0ef626 | 223 | /* timeout, check to see how many we have had */ |
224 | if (++client_alive_timeouts > options.client_alive_count_max) | |
225 | packet_disconnect("Timeout, your session not responding."); | |
226 | ||
3c0ef626 | 227 | /* |
228 | * send a bogus channel request with "wantreply", | |
229 | * we should get back a failure | |
230 | */ | |
231 | channel_request_start(id, "keepalive@openssh.com", 1); | |
232 | packet_send(); | |
233 | } | |
234 | ||
235 | /* | |
236 | * Sleep in select() until we can do something. This will initialize the | |
237 | * select masks. Upon return, the masks will indicate which descriptors | |
238 | * have data or can accept data. Optionally, a maximum time can be specified | |
239 | * for the duration of the wait (0 = infinite). | |
240 | */ | |
241 | static void | |
242 | wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, | |
243 | int *nallocp, u_int max_time_milliseconds) | |
244 | { | |
245 | struct timeval tv, *tvp; | |
246 | int ret; | |
247 | int client_alive_scheduled = 0; | |
248 | ||
249 | /* | |
1e608e42 | 250 | * if using client_alive, set the max timeout accordingly, |
3c0ef626 | 251 | * and indicate that this particular timeout was for client |
252 | * alive by setting the client_alive_scheduled flag. | |
253 | * | |
254 | * this could be randomized somewhat to make traffic | |
1e608e42 | 255 | * analysis more difficult, but we're not doing it yet. |
3c0ef626 | 256 | */ |
257 | if (compat20 && | |
258 | max_time_milliseconds == 0 && options.client_alive_interval) { | |
259 | client_alive_scheduled = 1; | |
260 | max_time_milliseconds = options.client_alive_interval * 1000; | |
261 | } | |
262 | ||
263 | /* Allocate and update select() masks for channel descriptors. */ | |
264 | channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); | |
265 | ||
266 | if (compat20) { | |
267 | #if 0 | |
268 | /* wrong: bad condition XXX */ | |
269 | if (channel_not_very_much_buffered_data()) | |
270 | #endif | |
271 | FD_SET(connection_in, *readsetp); | |
272 | } else { | |
273 | /* | |
274 | * Read packets from the client unless we have too much | |
275 | * buffered stdin or channel data. | |
276 | */ | |
277 | if (buffer_len(&stdin_buffer) < buffer_high && | |
278 | channel_not_very_much_buffered_data()) | |
279 | FD_SET(connection_in, *readsetp); | |
280 | /* | |
281 | * If there is not too much data already buffered going to | |
282 | * the client, try to get some more data from the program. | |
283 | */ | |
284 | if (packet_not_very_much_data_to_write()) { | |
285 | if (!fdout_eof) | |
286 | FD_SET(fdout, *readsetp); | |
287 | if (!fderr_eof) | |
288 | FD_SET(fderr, *readsetp); | |
289 | } | |
290 | /* | |
291 | * If we have buffered data, try to write some of that data | |
292 | * to the program. | |
293 | */ | |
294 | if (fdin != -1 && buffer_len(&stdin_buffer) > 0) | |
295 | FD_SET(fdin, *writesetp); | |
296 | } | |
1e608e42 | 297 | notify_prepare(*readsetp); |
3c0ef626 | 298 | |
299 | /* | |
300 | * If we have buffered packet data going to the client, mark that | |
301 | * descriptor. | |
302 | */ | |
303 | if (packet_have_data_to_write()) | |
304 | FD_SET(connection_out, *writesetp); | |
305 | ||
306 | /* | |
307 | * If child has terminated and there is enough buffer space to read | |
308 | * from it, then read as much as is available and exit. | |
309 | */ | |
310 | if (child_terminated && packet_not_very_much_data_to_write()) | |
311 | if (max_time_milliseconds == 0 || client_alive_scheduled) | |
312 | max_time_milliseconds = 100; | |
313 | ||
314 | if (max_time_milliseconds == 0) | |
315 | tvp = NULL; | |
316 | else { | |
317 | tv.tv_sec = max_time_milliseconds / 1000; | |
318 | tv.tv_usec = 1000 * (max_time_milliseconds % 1000); | |
319 | tvp = &tv; | |
320 | } | |
321 | if (tvp!=NULL) | |
1e608e42 | 322 | debug3("tvp!=NULL kid %d mili %d", (int) child_terminated, |
323 | max_time_milliseconds); | |
3c0ef626 | 324 | |
325 | /* Wait for something to happen, or the timeout to expire. */ | |
326 | ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); | |
327 | ||
328 | if (ret == -1) { | |
329 | memset(*readsetp, 0, *nallocp); | |
330 | memset(*writesetp, 0, *nallocp); | |
331 | if (errno != EINTR) | |
332 | error("select: %.100s", strerror(errno)); | |
333 | } else if (ret == 0 && client_alive_scheduled) | |
334 | client_alive_check(); | |
1e608e42 | 335 | |
336 | notify_done(*readsetp); | |
3c0ef626 | 337 | } |
338 | ||
339 | /* | |
340 | * Processes input from the client and the program. Input data is stored | |
341 | * in buffers and processed later. | |
342 | */ | |
343 | static void | |
344 | process_input(fd_set * readset) | |
345 | { | |
346 | int len; | |
347 | char buf[16384]; | |
348 | ||
349 | /* Read and buffer any input data from the client. */ | |
350 | if (FD_ISSET(connection_in, readset)) { | |
351 | len = read(connection_in, buf, sizeof(buf)); | |
352 | if (len == 0) { | |
353 | verbose("Connection closed by remote host."); | |
354 | connection_closed = 1; | |
355 | if (compat20) | |
356 | return; | |
357 | fatal_cleanup(); | |
358 | } else if (len < 0) { | |
359 | if (errno != EINTR && errno != EAGAIN) { | |
360 | verbose("Read error from remote host: %.100s", strerror(errno)); | |
361 | fatal_cleanup(); | |
362 | } | |
363 | } else { | |
364 | /* Buffer any received data. */ | |
365 | packet_process_incoming(buf, len); | |
366 | } | |
367 | } | |
368 | if (compat20) | |
369 | return; | |
370 | ||
371 | /* Read and buffer any available stdout data from the program. */ | |
372 | if (!fdout_eof && FD_ISSET(fdout, readset)) { | |
373 | len = read(fdout, buf, sizeof(buf)); | |
374 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
375 | /* do nothing */ | |
376 | } else if (len <= 0) { | |
377 | fdout_eof = 1; | |
378 | } else { | |
379 | buffer_append(&stdout_buffer, buf, len); | |
380 | fdout_bytes += len; | |
381 | } | |
382 | } | |
383 | /* Read and buffer any available stderr data from the program. */ | |
384 | if (!fderr_eof && FD_ISSET(fderr, readset)) { | |
385 | len = read(fderr, buf, sizeof(buf)); | |
386 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
387 | /* do nothing */ | |
388 | } else if (len <= 0) { | |
389 | fderr_eof = 1; | |
390 | } else { | |
391 | buffer_append(&stderr_buffer, buf, len); | |
392 | } | |
393 | } | |
394 | } | |
395 | ||
396 | /* | |
397 | * Sends data from internal buffers to client program stdin. | |
398 | */ | |
399 | static void | |
400 | process_output(fd_set * writeset) | |
401 | { | |
402 | struct termios tio; | |
403 | u_char *data; | |
404 | u_int dlen; | |
405 | int len; | |
406 | ||
407 | /* Write buffered data to program stdin. */ | |
408 | if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { | |
409 | data = buffer_ptr(&stdin_buffer); | |
410 | dlen = buffer_len(&stdin_buffer); | |
411 | len = write(fdin, data, dlen); | |
412 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
413 | /* do nothing */ | |
414 | } else if (len <= 0) { | |
3c0ef626 | 415 | if (fdin != fdout) |
416 | close(fdin); | |
417 | else | |
418 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ | |
3c0ef626 | 419 | fdin = -1; |
420 | } else { | |
421 | /* Successful write. */ | |
422 | if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && | |
423 | tcgetattr(fdin, &tio) == 0 && | |
424 | !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { | |
425 | /* | |
426 | * Simulate echo to reduce the impact of | |
427 | * traffic analysis | |
428 | */ | |
429 | packet_send_ignore(len); | |
430 | packet_send(); | |
431 | } | |
432 | /* Consume the data from the buffer. */ | |
433 | buffer_consume(&stdin_buffer, len); | |
434 | /* Update the count of bytes written to the program. */ | |
435 | stdin_bytes += len; | |
436 | } | |
437 | } | |
438 | /* Send any buffered packet data to the client. */ | |
439 | if (FD_ISSET(connection_out, writeset)) | |
440 | packet_write_poll(); | |
441 | } | |
442 | ||
443 | /* | |
444 | * Wait until all buffered output has been sent to the client. | |
445 | * This is used when the program terminates. | |
446 | */ | |
447 | static void | |
448 | drain_output(void) | |
449 | { | |
450 | /* Send any buffered stdout data to the client. */ | |
451 | if (buffer_len(&stdout_buffer) > 0) { | |
452 | packet_start(SSH_SMSG_STDOUT_DATA); | |
453 | packet_put_string(buffer_ptr(&stdout_buffer), | |
454 | buffer_len(&stdout_buffer)); | |
455 | packet_send(); | |
456 | /* Update the count of sent bytes. */ | |
457 | stdout_bytes += buffer_len(&stdout_buffer); | |
458 | } | |
459 | /* Send any buffered stderr data to the client. */ | |
460 | if (buffer_len(&stderr_buffer) > 0) { | |
461 | packet_start(SSH_SMSG_STDERR_DATA); | |
462 | packet_put_string(buffer_ptr(&stderr_buffer), | |
463 | buffer_len(&stderr_buffer)); | |
464 | packet_send(); | |
465 | /* Update the count of sent bytes. */ | |
466 | stderr_bytes += buffer_len(&stderr_buffer); | |
467 | } | |
468 | /* Wait until all buffered data has been written to the client. */ | |
469 | packet_write_wait(); | |
470 | } | |
471 | ||
472 | static void | |
473 | process_buffered_input_packets(void) | |
474 | { | |
475 | dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); | |
476 | } | |
477 | ||
478 | /* | |
479 | * Performs the interactive session. This handles data transmission between | |
480 | * the client and the program. Note that the notion of stdin, stdout, and | |
481 | * stderr in this function is sort of reversed: this function writes to | |
482 | * stdin (of the child program), and reads from stdout and stderr (of the | |
483 | * child program). | |
484 | */ | |
485 | void | |
486 | server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) | |
487 | { | |
488 | fd_set *readset = NULL, *writeset = NULL; | |
489 | int max_fd = 0, nalloc = 0; | |
490 | int wait_status; /* Status returned by wait(). */ | |
491 | pid_t wait_pid; /* pid returned by wait(). */ | |
492 | int waiting_termination = 0; /* Have displayed waiting close message. */ | |
493 | u_int max_time_milliseconds; | |
494 | u_int previous_stdout_buffer_bytes; | |
495 | u_int stdout_buffer_bytes; | |
496 | int type; | |
497 | ||
498 | debug("Entering interactive session."); | |
499 | ||
500 | /* Initialize the SIGCHLD kludge. */ | |
501 | child_terminated = 0; | |
502 | mysignal(SIGCHLD, sigchld_handler); | |
503 | ||
504 | /* Initialize our global variables. */ | |
505 | fdin = fdin_arg; | |
506 | fdout = fdout_arg; | |
507 | fderr = fderr_arg; | |
508 | ||
509 | /* nonblocking IO */ | |
510 | set_nonblock(fdin); | |
511 | set_nonblock(fdout); | |
512 | /* we don't have stderr for interactive terminal sessions, see below */ | |
513 | if (fderr != -1) | |
514 | set_nonblock(fderr); | |
515 | ||
516 | if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) | |
517 | fdin_is_tty = 1; | |
518 | ||
519 | connection_in = packet_get_connection_in(); | |
520 | connection_out = packet_get_connection_out(); | |
521 | ||
1e608e42 | 522 | notify_setup(); |
523 | ||
3c0ef626 | 524 | previous_stdout_buffer_bytes = 0; |
525 | ||
526 | /* Set approximate I/O buffer size. */ | |
527 | if (packet_is_interactive()) | |
528 | buffer_high = 4096; | |
529 | else | |
530 | buffer_high = 64 * 1024; | |
531 | ||
532 | #if 0 | |
533 | /* Initialize max_fd to the maximum of the known file descriptors. */ | |
534 | max_fd = MAX(connection_in, connection_out); | |
535 | max_fd = MAX(max_fd, fdin); | |
536 | max_fd = MAX(max_fd, fdout); | |
537 | if (fderr != -1) | |
538 | max_fd = MAX(max_fd, fderr); | |
539 | #endif | |
540 | ||
541 | /* Initialize Initialize buffers. */ | |
542 | buffer_init(&stdin_buffer); | |
543 | buffer_init(&stdout_buffer); | |
544 | buffer_init(&stderr_buffer); | |
545 | ||
546 | /* | |
547 | * If we have no separate fderr (which is the case when we have a pty | |
548 | * - there we cannot make difference between data sent to stdout and | |
549 | * stderr), indicate that we have seen an EOF from stderr. This way | |
550 | * we don\'t need to check the descriptor everywhere. | |
551 | */ | |
552 | if (fderr == -1) | |
553 | fderr_eof = 1; | |
554 | ||
555 | server_init_dispatch(); | |
556 | ||
557 | /* Main loop of the server for the interactive session mode. */ | |
558 | for (;;) { | |
559 | ||
560 | /* Process buffered packets from the client. */ | |
561 | process_buffered_input_packets(); | |
562 | ||
563 | /* | |
564 | * If we have received eof, and there is no more pending | |
565 | * input data, cause a real eof by closing fdin. | |
566 | */ | |
567 | if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { | |
3c0ef626 | 568 | if (fdin != fdout) |
569 | close(fdin); | |
570 | else | |
571 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ | |
3c0ef626 | 572 | fdin = -1; |
573 | } | |
574 | /* Make packets from buffered stderr data to send to the client. */ | |
575 | make_packets_from_stderr_data(); | |
576 | ||
577 | /* | |
578 | * Make packets from buffered stdout data to send to the | |
579 | * client. If there is very little to send, this arranges to | |
580 | * not send them now, but to wait a short while to see if we | |
581 | * are getting more data. This is necessary, as some systems | |
582 | * wake up readers from a pty after each separate character. | |
583 | */ | |
584 | max_time_milliseconds = 0; | |
585 | stdout_buffer_bytes = buffer_len(&stdout_buffer); | |
586 | if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && | |
587 | stdout_buffer_bytes != previous_stdout_buffer_bytes) { | |
588 | /* try again after a while */ | |
589 | max_time_milliseconds = 10; | |
590 | } else { | |
591 | /* Send it now. */ | |
592 | make_packets_from_stdout_data(); | |
593 | } | |
594 | previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); | |
595 | ||
596 | /* Send channel data to the client. */ | |
597 | if (packet_not_very_much_data_to_write()) | |
598 | channel_output_poll(); | |
599 | ||
600 | /* | |
601 | * Bail out of the loop if the program has closed its output | |
602 | * descriptors, and we have no more data to send to the | |
603 | * client, and there is no pending buffered data. | |
604 | */ | |
605 | if (fdout_eof && fderr_eof && !packet_have_data_to_write() && | |
606 | buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { | |
607 | if (!channel_still_open()) | |
608 | break; | |
609 | if (!waiting_termination) { | |
610 | const char *s = "Waiting for forwarded connections to terminate...\r\n"; | |
611 | char *cp; | |
612 | waiting_termination = 1; | |
613 | buffer_append(&stderr_buffer, s, strlen(s)); | |
614 | ||
615 | /* Display list of open channels. */ | |
616 | cp = channel_open_message(); | |
617 | buffer_append(&stderr_buffer, cp, strlen(cp)); | |
618 | xfree(cp); | |
619 | } | |
620 | } | |
621 | max_fd = MAX(connection_in, connection_out); | |
622 | max_fd = MAX(max_fd, fdin); | |
623 | max_fd = MAX(max_fd, fdout); | |
624 | max_fd = MAX(max_fd, fderr); | |
1e608e42 | 625 | max_fd = MAX(max_fd, notify_pipe[0]); |
3c0ef626 | 626 | |
627 | /* Sleep in select() until we can do something. */ | |
628 | wait_until_can_do_something(&readset, &writeset, &max_fd, | |
629 | &nalloc, max_time_milliseconds); | |
630 | ||
631 | /* Process any channel events. */ | |
632 | channel_after_select(readset, writeset); | |
633 | ||
634 | /* Process input from the client and from program stdout/stderr. */ | |
635 | process_input(readset); | |
636 | ||
637 | /* Process output to the client and to program stdin. */ | |
638 | process_output(writeset); | |
639 | } | |
640 | if (readset) | |
641 | xfree(readset); | |
642 | if (writeset) | |
643 | xfree(writeset); | |
644 | ||
645 | /* Cleanup and termination code. */ | |
646 | ||
647 | /* Wait until all output has been sent to the client. */ | |
648 | drain_output(); | |
649 | ||
650 | debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", | |
1e608e42 | 651 | stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); |
3c0ef626 | 652 | |
653 | /* Free and clear the buffers. */ | |
654 | buffer_free(&stdin_buffer); | |
655 | buffer_free(&stdout_buffer); | |
656 | buffer_free(&stderr_buffer); | |
657 | ||
658 | /* Close the file descriptors. */ | |
659 | if (fdout != -1) | |
660 | close(fdout); | |
661 | fdout = -1; | |
662 | fdout_eof = 1; | |
663 | if (fderr != -1) | |
664 | close(fderr); | |
665 | fderr = -1; | |
666 | fderr_eof = 1; | |
667 | if (fdin != -1) | |
668 | close(fdin); | |
669 | fdin = -1; | |
670 | ||
671 | channel_free_all(); | |
672 | ||
673 | /* We no longer want our SIGCHLD handler to be called. */ | |
674 | mysignal(SIGCHLD, SIG_DFL); | |
675 | ||
1e608e42 | 676 | wait_pid = waitpid(-1, &wait_status, 0); |
3c0ef626 | 677 | if (wait_pid == -1) |
678 | packet_disconnect("wait: %.100s", strerror(errno)); | |
679 | else if (wait_pid != pid) | |
680 | error("Strange, wait returned pid %d, expected %d", | |
681 | wait_pid, pid); | |
682 | ||
683 | /* Check if it exited normally. */ | |
684 | if (WIFEXITED(wait_status)) { | |
685 | /* Yes, normal exit. Get exit status and send it to the client. */ | |
686 | debug("Command exited with status %d.", WEXITSTATUS(wait_status)); | |
687 | packet_start(SSH_SMSG_EXITSTATUS); | |
688 | packet_put_int(WEXITSTATUS(wait_status)); | |
689 | packet_send(); | |
690 | packet_write_wait(); | |
691 | ||
692 | /* | |
693 | * Wait for exit confirmation. Note that there might be | |
694 | * other packets coming before it; however, the program has | |
695 | * already died so we just ignore them. The client is | |
696 | * supposed to respond with the confirmation when it receives | |
697 | * the exit status. | |
698 | */ | |
699 | do { | |
1e608e42 | 700 | type = packet_read(); |
3c0ef626 | 701 | } |
702 | while (type != SSH_CMSG_EXIT_CONFIRMATION); | |
703 | ||
704 | debug("Received exit confirmation."); | |
705 | return; | |
706 | } | |
707 | /* Check if the program terminated due to a signal. */ | |
708 | if (WIFSIGNALED(wait_status)) | |
709 | packet_disconnect("Command terminated on signal %d.", | |
710 | WTERMSIG(wait_status)); | |
711 | ||
712 | /* Some weird exit cause. Just exit. */ | |
713 | packet_disconnect("wait returned status %04x.", wait_status); | |
714 | /* NOTREACHED */ | |
715 | } | |
716 | ||
717 | static void | |
718 | collect_children(void) | |
719 | { | |
720 | pid_t pid; | |
721 | sigset_t oset, nset; | |
722 | int status; | |
723 | ||
724 | /* block SIGCHLD while we check for dead children */ | |
725 | sigemptyset(&nset); | |
726 | sigaddset(&nset, SIGCHLD); | |
727 | sigprocmask(SIG_BLOCK, &nset, &oset); | |
728 | if (child_terminated) { | |
729 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0) | |
730 | session_close_by_pid(pid, status); | |
731 | child_terminated = 0; | |
732 | } | |
733 | sigprocmask(SIG_SETMASK, &oset, NULL); | |
734 | } | |
735 | ||
736 | void | |
737 | server_loop2(Authctxt *authctxt) | |
738 | { | |
739 | fd_set *readset = NULL, *writeset = NULL; | |
740 | int rekeying = 0, max_fd, nalloc = 0; | |
741 | ||
742 | debug("Entering interactive session for SSH2."); | |
743 | ||
744 | mysignal(SIGCHLD, sigchld_handler); | |
745 | child_terminated = 0; | |
746 | connection_in = packet_get_connection_in(); | |
747 | connection_out = packet_get_connection_out(); | |
748 | ||
1e608e42 | 749 | notify_setup(); |
750 | ||
3c0ef626 | 751 | max_fd = MAX(connection_in, connection_out); |
1e608e42 | 752 | max_fd = MAX(max_fd, notify_pipe[0]); |
753 | ||
3c0ef626 | 754 | xxx_authctxt = authctxt; |
755 | ||
756 | server_init_dispatch(); | |
757 | ||
758 | for (;;) { | |
759 | process_buffered_input_packets(); | |
760 | ||
761 | rekeying = (xxx_kex != NULL && !xxx_kex->done); | |
762 | ||
763 | if (!rekeying && packet_not_very_much_data_to_write()) | |
764 | channel_output_poll(); | |
765 | wait_until_can_do_something(&readset, &writeset, &max_fd, | |
766 | &nalloc, 0); | |
767 | ||
768 | collect_children(); | |
769 | if (!rekeying) | |
770 | channel_after_select(readset, writeset); | |
771 | process_input(readset); | |
772 | if (connection_closed) | |
773 | break; | |
774 | process_output(writeset); | |
775 | } | |
776 | collect_children(); | |
777 | ||
778 | if (readset) | |
779 | xfree(readset); | |
780 | if (writeset) | |
781 | xfree(writeset); | |
782 | ||
783 | /* free all channels, no more reads and writes */ | |
784 | channel_free_all(); | |
785 | ||
786 | /* free remaining sessions, e.g. remove wtmp entries */ | |
787 | session_destroy_all(); | |
788 | } | |
789 | ||
790 | static void | |
1e608e42 | 791 | server_input_channel_failure(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 792 | { |
793 | debug("Got CHANNEL_FAILURE for keepalive"); | |
1e608e42 | 794 | /* |
3c0ef626 | 795 | * reset timeout, since we got a sane answer from the client. |
796 | * even if this was generated by something other than | |
797 | * the bogus CHANNEL_REQUEST we send for keepalives. | |
798 | */ | |
1e608e42 | 799 | client_alive_timeouts = 0; |
3c0ef626 | 800 | } |
801 | ||
802 | ||
803 | static void | |
1e608e42 | 804 | server_input_stdin_data(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 805 | { |
806 | char *data; | |
807 | u_int data_len; | |
808 | ||
809 | /* Stdin data from the client. Append it to the buffer. */ | |
810 | /* Ignore any data if the client has closed stdin. */ | |
811 | if (fdin == -1) | |
812 | return; | |
813 | data = packet_get_string(&data_len); | |
1e608e42 | 814 | packet_check_eom(); |
3c0ef626 | 815 | buffer_append(&stdin_buffer, data, data_len); |
816 | memset(data, 0, data_len); | |
817 | xfree(data); | |
818 | } | |
819 | ||
820 | static void | |
1e608e42 | 821 | server_input_eof(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 822 | { |
823 | /* | |
824 | * Eof from the client. The stdin descriptor to the | |
825 | * program will be closed when all buffered data has | |
826 | * drained. | |
827 | */ | |
828 | debug("EOF received for stdin."); | |
1e608e42 | 829 | packet_check_eom(); |
3c0ef626 | 830 | stdin_eof = 1; |
831 | } | |
832 | ||
833 | static void | |
1e608e42 | 834 | server_input_window_size(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 835 | { |
836 | int row = packet_get_int(); | |
837 | int col = packet_get_int(); | |
838 | int xpixel = packet_get_int(); | |
839 | int ypixel = packet_get_int(); | |
840 | ||
841 | debug("Window change received."); | |
1e608e42 | 842 | packet_check_eom(); |
3c0ef626 | 843 | if (fdin != -1) |
844 | pty_change_window_size(fdin, row, col, xpixel, ypixel); | |
845 | } | |
846 | ||
847 | static Channel * | |
848 | server_request_direct_tcpip(char *ctype) | |
849 | { | |
850 | Channel *c; | |
851 | int sock; | |
852 | char *target, *originator; | |
853 | int target_port, originator_port; | |
854 | ||
855 | target = packet_get_string(NULL); | |
856 | target_port = packet_get_int(); | |
857 | originator = packet_get_string(NULL); | |
858 | originator_port = packet_get_int(); | |
1e608e42 | 859 | packet_check_eom(); |
3c0ef626 | 860 | |
861 | debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", | |
862 | originator, originator_port, target, target_port); | |
863 | ||
864 | /* XXX check permission */ | |
865 | sock = channel_connect_to(target, target_port); | |
866 | xfree(target); | |
867 | xfree(originator); | |
868 | if (sock < 0) | |
869 | return NULL; | |
870 | c = channel_new(ctype, SSH_CHANNEL_CONNECTING, | |
871 | sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, | |
872 | CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); | |
3c0ef626 | 873 | return c; |
874 | } | |
875 | ||
876 | static Channel * | |
877 | server_request_session(char *ctype) | |
878 | { | |
879 | Channel *c; | |
880 | ||
881 | debug("input_session_request"); | |
1e608e42 | 882 | packet_check_eom(); |
3c0ef626 | 883 | /* |
884 | * A server session has no fd to read or write until a | |
885 | * CHANNEL_REQUEST for a shell is made, so we set the type to | |
886 | * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all | |
887 | * CHANNEL_REQUEST messages is registered. | |
888 | */ | |
889 | c = channel_new(ctype, SSH_CHANNEL_LARVAL, | |
890 | -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, | |
891 | 0, xstrdup("server-session"), 1); | |
3c0ef626 | 892 | if (session_open(xxx_authctxt, c->self) != 1) { |
893 | debug("session open failed, free channel %d", c->self); | |
894 | channel_free(c); | |
895 | return NULL; | |
896 | } | |
3c0ef626 | 897 | channel_register_cleanup(c->self, session_close_by_channel); |
898 | return c; | |
899 | } | |
900 | ||
901 | static void | |
1e608e42 | 902 | server_input_channel_open(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 903 | { |
904 | Channel *c = NULL; | |
905 | char *ctype; | |
906 | u_int len; | |
907 | int rchan; | |
908 | int rmaxpack; | |
909 | int rwindow; | |
910 | ||
911 | ctype = packet_get_string(&len); | |
912 | rchan = packet_get_int(); | |
913 | rwindow = packet_get_int(); | |
914 | rmaxpack = packet_get_int(); | |
915 | ||
916 | debug("server_input_channel_open: ctype %s rchan %d win %d max %d", | |
917 | ctype, rchan, rwindow, rmaxpack); | |
918 | ||
919 | if (strcmp(ctype, "session") == 0) { | |
920 | c = server_request_session(ctype); | |
921 | } else if (strcmp(ctype, "direct-tcpip") == 0) { | |
922 | c = server_request_direct_tcpip(ctype); | |
923 | } | |
924 | if (c != NULL) { | |
925 | debug("server_input_channel_open: confirm %s", ctype); | |
926 | c->remote_id = rchan; | |
927 | c->remote_window = rwindow; | |
928 | c->remote_maxpacket = rmaxpack; | |
929 | if (c->type != SSH_CHANNEL_CONNECTING) { | |
930 | packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); | |
931 | packet_put_int(c->remote_id); | |
932 | packet_put_int(c->self); | |
933 | packet_put_int(c->local_window); | |
934 | packet_put_int(c->local_maxpacket); | |
935 | packet_send(); | |
936 | } | |
937 | } else { | |
938 | debug("server_input_channel_open: failure %s", ctype); | |
939 | packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); | |
940 | packet_put_int(rchan); | |
941 | packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); | |
942 | if (!(datafellows & SSH_BUG_OPENFAILURE)) { | |
943 | packet_put_cstring("open failed"); | |
944 | packet_put_cstring(""); | |
945 | } | |
946 | packet_send(); | |
947 | } | |
948 | xfree(ctype); | |
949 | } | |
950 | ||
951 | static void | |
1e608e42 | 952 | server_input_global_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 953 | { |
954 | char *rtype; | |
955 | int want_reply; | |
956 | int success = 0; | |
957 | ||
958 | rtype = packet_get_string(NULL); | |
959 | want_reply = packet_get_char(); | |
960 | debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); | |
961 | ||
962 | /* -R style forwarding */ | |
963 | if (strcmp(rtype, "tcpip-forward") == 0) { | |
964 | struct passwd *pw; | |
965 | char *listen_address; | |
966 | u_short listen_port; | |
967 | ||
968 | pw = auth_get_user(); | |
969 | if (pw == NULL) | |
970 | fatal("server_input_global_request: no user"); | |
971 | listen_address = packet_get_string(NULL); /* XXX currently ignored */ | |
972 | listen_port = (u_short)packet_get_int(); | |
973 | debug("server_input_global_request: tcpip-forward listen %s port %d", | |
974 | listen_address, listen_port); | |
975 | ||
976 | /* check permissions */ | |
977 | if (!options.allow_tcp_forwarding || | |
978 | no_port_forwarding_flag || | |
979 | (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { | |
980 | success = 0; | |
981 | packet_send_debug("Server has disabled port forwarding."); | |
982 | } else { | |
983 | /* Start listening on the port */ | |
1e608e42 | 984 | success = channel_setup_remote_fwd_listener( |
985 | listen_address, listen_port, options.gateway_ports); | |
3c0ef626 | 986 | } |
987 | xfree(listen_address); | |
988 | } | |
989 | if (want_reply) { | |
990 | packet_start(success ? | |
991 | SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); | |
992 | packet_send(); | |
993 | packet_write_wait(); | |
994 | } | |
995 | xfree(rtype); | |
996 | } | |
1e608e42 | 997 | static void |
998 | server_input_channel_req(int type, u_int32_t seq, void *ctxt) | |
999 | { | |
1000 | Channel *c; | |
1001 | int id, reply, success = 0; | |
1002 | char *rtype; | |
1003 | ||
1004 | id = packet_get_int(); | |
1005 | rtype = packet_get_string(NULL); | |
1006 | reply = packet_get_char(); | |
1007 | ||
1008 | debug("server_input_channel_req: channel %d request %s reply %d", | |
1009 | id, rtype, reply); | |
1010 | ||
1011 | if ((c = channel_lookup(id)) == NULL) | |
1012 | packet_disconnect("server_input_channel_req: " | |
1013 | "unknown channel %d", id); | |
1014 | if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) | |
1015 | success = session_input_channel_req(c, rtype); | |
1016 | if (reply) { | |
1017 | packet_start(success ? | |
1018 | SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); | |
1019 | packet_put_int(c->remote_id); | |
1020 | packet_send(); | |
1021 | } | |
1022 | xfree(rtype); | |
1023 | } | |
3c0ef626 | 1024 | |
1025 | static void | |
1026 | server_init_dispatch_20(void) | |
1027 | { | |
1028 | debug("server_init_dispatch_20"); | |
1029 | dispatch_init(&dispatch_protocol_error); | |
1030 | dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); | |
1031 | dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); | |
1032 | dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); | |
1033 | dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); | |
1034 | dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); | |
1035 | dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); | |
1036 | dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); | |
1e608e42 | 1037 | dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); |
3c0ef626 | 1038 | dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); |
1039 | dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); | |
1040 | /* client_alive */ | |
1041 | dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); | |
1042 | /* rekeying */ | |
1043 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); | |
1044 | } | |
1045 | static void | |
1046 | server_init_dispatch_13(void) | |
1047 | { | |
1048 | debug("server_init_dispatch_13"); | |
1049 | dispatch_init(NULL); | |
1050 | dispatch_set(SSH_CMSG_EOF, &server_input_eof); | |
1051 | dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); | |
1052 | dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); | |
1053 | dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); | |
1054 | dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); | |
1055 | dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); | |
1056 | dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); | |
1057 | dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); | |
1058 | dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); | |
1059 | } | |
1060 | static void | |
1061 | server_init_dispatch_15(void) | |
1062 | { | |
1063 | server_init_dispatch_13(); | |
1064 | debug("server_init_dispatch_15"); | |
1065 | dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); | |
1066 | dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); | |
1067 | } | |
1068 | static void | |
1069 | server_init_dispatch(void) | |
1070 | { | |
1071 | if (compat20) | |
1072 | server_init_dispatch_20(); | |
1073 | else if (compat13) | |
1074 | server_init_dispatch_13(); | |
1075 | else | |
1076 | server_init_dispatch_15(); | |
1077 | } |