xref: /openbsd-src/usr.bin/ssh/serverloop.c (revision 0b7734b3d77bb9b21afec6f4621cae6c805dbd45)
1 /* $OpenBSD: serverloop.c,v 1.184 2016/03/07 19:02:43 djm Exp $ */
2 /*
3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5  *                    All rights reserved
6  * Server main loop for handling the interactive session.
7  *
8  * As far as I am concerned, the code I have written for this software
9  * can be used freely for any purpose.  Any derived versions of this
10  * software must be clearly marked as such, and if the derived work is
11  * incompatible with the protocol description in the RFC file, it must be
12  * called by a name other than "ssh" or "Secure Shell".
13  *
14  * SSH2 support by Markus Friedl.
15  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
16  *
17  * Redistribution and use in source and binary forms, with or without
18  * modification, are permitted provided that the following conditions
19  * are met:
20  * 1. Redistributions of source code must retain the above copyright
21  *    notice, this list of conditions and the following disclaimer.
22  * 2. Redistributions in binary form must reproduce the above copyright
23  *    notice, this list of conditions and the following disclaimer in the
24  *    documentation and/or other materials provided with the distribution.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36  */
37 
38 #include <sys/param.h>	/* MIN MAX */
39 #include <sys/types.h>
40 #include <sys/wait.h>
41 #include <sys/socket.h>
42 #include <sys/time.h>
43 #include <sys/queue.h>
44 
45 #include <netinet/in.h>
46 
47 #include <errno.h>
48 #include <fcntl.h>
49 #include <pwd.h>
50 #include <signal.h>
51 #include <string.h>
52 #include <termios.h>
53 #include <unistd.h>
54 #include <stdarg.h>
55 
56 #include "xmalloc.h"
57 #include "packet.h"
58 #include "buffer.h"
59 #include "log.h"
60 #include "misc.h"
61 #include "servconf.h"
62 #include "canohost.h"
63 #include "sshpty.h"
64 #include "channels.h"
65 #include "compat.h"
66 #include "ssh1.h"
67 #include "ssh2.h"
68 #include "key.h"
69 #include "cipher.h"
70 #include "kex.h"
71 #include "hostfile.h"
72 #include "auth.h"
73 #include "session.h"
74 #include "dispatch.h"
75 #include "auth-options.h"
76 #include "serverloop.h"
77 #include "ssherr.h"
78 
79 extern ServerOptions options;
80 
81 /* XXX */
82 extern Authctxt *the_authctxt;
83 extern int use_privsep;
84 
85 static Buffer stdin_buffer;	/* Buffer for stdin data. */
86 static Buffer stdout_buffer;	/* Buffer for stdout data. */
87 static Buffer stderr_buffer;	/* Buffer for stderr data. */
88 static int fdin;		/* Descriptor for stdin (for writing) */
89 static int fdout;		/* Descriptor for stdout (for reading);
90 				   May be same number as fdin. */
91 static int fderr;		/* Descriptor for stderr.  May be -1. */
92 static long stdin_bytes = 0;	/* Number of bytes written to stdin. */
93 static long stdout_bytes = 0;	/* Number of stdout bytes sent to client. */
94 static long stderr_bytes = 0;	/* Number of stderr bytes sent to client. */
95 static long fdout_bytes = 0;	/* Number of stdout bytes read from program. */
96 static int stdin_eof = 0;	/* EOF message received from client. */
97 static int fdout_eof = 0;	/* EOF encountered reading from fdout. */
98 static int fderr_eof = 0;	/* EOF encountered readung from fderr. */
99 static int fdin_is_tty = 0;	/* fdin points to a tty. */
100 static int connection_in;	/* Connection to client (input). */
101 static int connection_out;	/* Connection to client (output). */
102 static int connection_closed = 0;	/* Connection to client closed. */
103 static u_int buffer_high;	/* "Soft" max buffer size. */
104 static int no_more_sessions = 0; /* Disallow further sessions. */
105 
106 /*
107  * This SIGCHLD kludge is used to detect when the child exits.  The server
108  * will exit after that, as soon as forwarded connections have terminated.
109  */
110 
111 static volatile sig_atomic_t child_terminated = 0;	/* The child has terminated. */
112 
113 /* Cleanup on signals (!use_privsep case only) */
114 static volatile sig_atomic_t received_sigterm = 0;
115 
116 /* prototypes */
117 static void server_init_dispatch(void);
118 
119 /*
120  * we write to this pipe if a SIGCHLD is caught in order to avoid
121  * the race between select() and child_terminated
122  */
123 static int notify_pipe[2];
124 static void
125 notify_setup(void)
126 {
127 	if (pipe(notify_pipe) < 0) {
128 		error("pipe(notify_pipe) failed %s", strerror(errno));
129 	} else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) ||
130 	    (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) {
131 		error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno));
132 		close(notify_pipe[0]);
133 		close(notify_pipe[1]);
134 	} else {
135 		set_nonblock(notify_pipe[0]);
136 		set_nonblock(notify_pipe[1]);
137 		return;
138 	}
139 	notify_pipe[0] = -1;	/* read end */
140 	notify_pipe[1] = -1;	/* write end */
141 }
142 static void
143 notify_parent(void)
144 {
145 	if (notify_pipe[1] != -1)
146 		(void)write(notify_pipe[1], "", 1);
147 }
148 static void
149 notify_prepare(fd_set *readset)
150 {
151 	if (notify_pipe[0] != -1)
152 		FD_SET(notify_pipe[0], readset);
153 }
154 static void
155 notify_done(fd_set *readset)
156 {
157 	char c;
158 
159 	if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
160 		while (read(notify_pipe[0], &c, 1) != -1)
161 			debug2("notify_done: reading");
162 }
163 
164 /*ARGSUSED*/
165 static void
166 sigchld_handler(int sig)
167 {
168 	int save_errno = errno;
169 	child_terminated = 1;
170 	signal(SIGCHLD, sigchld_handler);
171 	notify_parent();
172 	errno = save_errno;
173 }
174 
175 /*ARGSUSED*/
176 static void
177 sigterm_handler(int sig)
178 {
179 	received_sigterm = sig;
180 }
181 
182 /*
183  * Make packets from buffered stderr data, and buffer it for sending
184  * to the client.
185  */
186 static void
187 make_packets_from_stderr_data(void)
188 {
189 	u_int len;
190 
191 	/* Send buffered stderr data to the client. */
192 	while (buffer_len(&stderr_buffer) > 0 &&
193 	    packet_not_very_much_data_to_write()) {
194 		len = buffer_len(&stderr_buffer);
195 		if (packet_is_interactive()) {
196 			if (len > 512)
197 				len = 512;
198 		} else {
199 			/* Keep the packets at reasonable size. */
200 			if (len > packet_get_maxsize())
201 				len = packet_get_maxsize();
202 		}
203 		packet_start(SSH_SMSG_STDERR_DATA);
204 		packet_put_string(buffer_ptr(&stderr_buffer), len);
205 		packet_send();
206 		buffer_consume(&stderr_buffer, len);
207 		stderr_bytes += len;
208 	}
209 }
210 
211 /*
212  * Make packets from buffered stdout data, and buffer it for sending to the
213  * client.
214  */
215 static void
216 make_packets_from_stdout_data(void)
217 {
218 	u_int len;
219 
220 	/* Send buffered stdout data to the client. */
221 	while (buffer_len(&stdout_buffer) > 0 &&
222 	    packet_not_very_much_data_to_write()) {
223 		len = buffer_len(&stdout_buffer);
224 		if (packet_is_interactive()) {
225 			if (len > 512)
226 				len = 512;
227 		} else {
228 			/* Keep the packets at reasonable size. */
229 			if (len > packet_get_maxsize())
230 				len = packet_get_maxsize();
231 		}
232 		packet_start(SSH_SMSG_STDOUT_DATA);
233 		packet_put_string(buffer_ptr(&stdout_buffer), len);
234 		packet_send();
235 		buffer_consume(&stdout_buffer, len);
236 		stdout_bytes += len;
237 	}
238 }
239 
240 static void
241 client_alive_check(void)
242 {
243 	int channel_id;
244 
245 	/* timeout, check to see how many we have had */
246 	if (packet_inc_alive_timeouts() > options.client_alive_count_max) {
247 		logit("Timeout, client not responding.");
248 		cleanup_exit(255);
249 	}
250 
251 	/*
252 	 * send a bogus global/channel request with "wantreply",
253 	 * we should get back a failure
254 	 */
255 	if ((channel_id = channel_find_open()) == -1) {
256 		packet_start(SSH2_MSG_GLOBAL_REQUEST);
257 		packet_put_cstring("keepalive@openssh.com");
258 		packet_put_char(1);	/* boolean: want reply */
259 	} else {
260 		channel_request_start(channel_id, "keepalive@openssh.com", 1);
261 	}
262 	packet_send();
263 }
264 
265 /*
266  * Sleep in select() until we can do something.  This will initialize the
267  * select masks.  Upon return, the masks will indicate which descriptors
268  * have data or can accept data.  Optionally, a maximum time can be specified
269  * for the duration of the wait (0 = infinite).
270  */
271 static void
272 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
273     u_int *nallocp, u_int64_t max_time_ms)
274 {
275 	struct timeval tv, *tvp;
276 	int ret;
277 	time_t minwait_secs = 0;
278 	int client_alive_scheduled = 0;
279 
280 	/* Allocate and update select() masks for channel descriptors. */
281 	channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
282 	    &minwait_secs, 0);
283 
284 	/* XXX need proper deadline system for rekey/client alive */
285 	if (minwait_secs != 0)
286 		max_time_ms = MIN(max_time_ms, (u_int)minwait_secs * 1000);
287 
288 	/*
289 	 * if using client_alive, set the max timeout accordingly,
290 	 * and indicate that this particular timeout was for client
291 	 * alive by setting the client_alive_scheduled flag.
292 	 *
293 	 * this could be randomized somewhat to make traffic
294 	 * analysis more difficult, but we're not doing it yet.
295 	 */
296 	if (compat20 && options.client_alive_interval) {
297 		uint64_t keepalive_ms =
298 		    (uint64_t)options.client_alive_interval * 1000;
299 
300 		client_alive_scheduled = 1;
301 		if (max_time_ms == 0 || max_time_ms > keepalive_ms)
302 			max_time_ms = keepalive_ms;
303 	}
304 
305 	if (compat20) {
306 #if 0
307 		/* wrong: bad condition XXX */
308 		if (channel_not_very_much_buffered_data())
309 #endif
310 		FD_SET(connection_in, *readsetp);
311 	} else {
312 		/*
313 		 * Read packets from the client unless we have too much
314 		 * buffered stdin or channel data.
315 		 */
316 		if (buffer_len(&stdin_buffer) < buffer_high &&
317 		    channel_not_very_much_buffered_data())
318 			FD_SET(connection_in, *readsetp);
319 		/*
320 		 * If there is not too much data already buffered going to
321 		 * the client, try to get some more data from the program.
322 		 */
323 		if (packet_not_very_much_data_to_write()) {
324 			if (!fdout_eof)
325 				FD_SET(fdout, *readsetp);
326 			if (!fderr_eof)
327 				FD_SET(fderr, *readsetp);
328 		}
329 		/*
330 		 * If we have buffered data, try to write some of that data
331 		 * to the program.
332 		 */
333 		if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
334 			FD_SET(fdin, *writesetp);
335 	}
336 	notify_prepare(*readsetp);
337 
338 	/*
339 	 * If we have buffered packet data going to the client, mark that
340 	 * descriptor.
341 	 */
342 	if (packet_have_data_to_write())
343 		FD_SET(connection_out, *writesetp);
344 
345 	/*
346 	 * If child has terminated and there is enough buffer space to read
347 	 * from it, then read as much as is available and exit.
348 	 */
349 	if (child_terminated && packet_not_very_much_data_to_write())
350 		if (max_time_ms == 0 || client_alive_scheduled)
351 			max_time_ms = 100;
352 
353 	if (max_time_ms == 0)
354 		tvp = NULL;
355 	else {
356 		tv.tv_sec = max_time_ms / 1000;
357 		tv.tv_usec = 1000 * (max_time_ms % 1000);
358 		tvp = &tv;
359 	}
360 
361 	/* Wait for something to happen, or the timeout to expire. */
362 	ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
363 
364 	if (ret == -1) {
365 		memset(*readsetp, 0, *nallocp);
366 		memset(*writesetp, 0, *nallocp);
367 		if (errno != EINTR)
368 			error("select: %.100s", strerror(errno));
369 	} else if (ret == 0 && client_alive_scheduled)
370 		client_alive_check();
371 
372 	notify_done(*readsetp);
373 }
374 
375 /*
376  * Processes input from the client and the program.  Input data is stored
377  * in buffers and processed later.
378  */
379 static void
380 process_input(fd_set *readset)
381 {
382 	struct ssh *ssh = active_state; /* XXX */
383 	int len;
384 	char buf[16384];
385 
386 	/* Read and buffer any input data from the client. */
387 	if (FD_ISSET(connection_in, readset)) {
388 		len = read(connection_in, buf, sizeof(buf));
389 		if (len == 0) {
390 			verbose("Connection closed by %.100s port %d",
391 			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
392 			connection_closed = 1;
393 			if (compat20)
394 				return;
395 			cleanup_exit(255);
396 		} else if (len < 0) {
397 			if (errno != EINTR && errno != EAGAIN) {
398 				verbose("Read error from remote host "
399 				    "%.100s port %d: %.100s",
400 				    ssh_remote_ipaddr(ssh),
401 				    ssh_remote_port(ssh), strerror(errno));
402 				cleanup_exit(255);
403 			}
404 		} else {
405 			/* Buffer any received data. */
406 			packet_process_incoming(buf, len);
407 		}
408 	}
409 	if (compat20)
410 		return;
411 
412 	/* Read and buffer any available stdout data from the program. */
413 	if (!fdout_eof && FD_ISSET(fdout, readset)) {
414 		len = read(fdout, buf, sizeof(buf));
415 		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
416 			/* do nothing */
417 		} else if (len <= 0) {
418 			fdout_eof = 1;
419 		} else {
420 			buffer_append(&stdout_buffer, buf, len);
421 			fdout_bytes += len;
422 		}
423 	}
424 	/* Read and buffer any available stderr data from the program. */
425 	if (!fderr_eof && FD_ISSET(fderr, readset)) {
426 		len = read(fderr, buf, sizeof(buf));
427 		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
428 			/* do nothing */
429 		} else if (len <= 0) {
430 			fderr_eof = 1;
431 		} else {
432 			buffer_append(&stderr_buffer, buf, len);
433 		}
434 	}
435 }
436 
437 /*
438  * Sends data from internal buffers to client program stdin.
439  */
440 static void
441 process_output(fd_set *writeset)
442 {
443 	struct termios tio;
444 	u_char *data;
445 	u_int dlen;
446 	int len;
447 
448 	/* Write buffered data to program stdin. */
449 	if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
450 		data = buffer_ptr(&stdin_buffer);
451 		dlen = buffer_len(&stdin_buffer);
452 		len = write(fdin, data, dlen);
453 		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
454 			/* do nothing */
455 		} else if (len <= 0) {
456 			if (fdin != fdout)
457 				close(fdin);
458 			else
459 				shutdown(fdin, SHUT_WR); /* We will no longer send. */
460 			fdin = -1;
461 		} else {
462 			/* Successful write. */
463 			if (fdin_is_tty && dlen >= 1 && data[0] != '\r' &&
464 			    tcgetattr(fdin, &tio) == 0 &&
465 			    !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
466 				/*
467 				 * Simulate echo to reduce the impact of
468 				 * traffic analysis
469 				 */
470 				packet_send_ignore(len);
471 				packet_send();
472 			}
473 			/* Consume the data from the buffer. */
474 			buffer_consume(&stdin_buffer, len);
475 			/* Update the count of bytes written to the program. */
476 			stdin_bytes += len;
477 		}
478 	}
479 	/* Send any buffered packet data to the client. */
480 	if (FD_ISSET(connection_out, writeset))
481 		packet_write_poll();
482 }
483 
484 /*
485  * Wait until all buffered output has been sent to the client.
486  * This is used when the program terminates.
487  */
488 static void
489 drain_output(void)
490 {
491 	/* Send any buffered stdout data to the client. */
492 	if (buffer_len(&stdout_buffer) > 0) {
493 		packet_start(SSH_SMSG_STDOUT_DATA);
494 		packet_put_string(buffer_ptr(&stdout_buffer),
495 				  buffer_len(&stdout_buffer));
496 		packet_send();
497 		/* Update the count of sent bytes. */
498 		stdout_bytes += buffer_len(&stdout_buffer);
499 	}
500 	/* Send any buffered stderr data to the client. */
501 	if (buffer_len(&stderr_buffer) > 0) {
502 		packet_start(SSH_SMSG_STDERR_DATA);
503 		packet_put_string(buffer_ptr(&stderr_buffer),
504 				  buffer_len(&stderr_buffer));
505 		packet_send();
506 		/* Update the count of sent bytes. */
507 		stderr_bytes += buffer_len(&stderr_buffer);
508 	}
509 	/* Wait until all buffered data has been written to the client. */
510 	packet_write_wait();
511 }
512 
513 static void
514 process_buffered_input_packets(void)
515 {
516 	dispatch_run(DISPATCH_NONBLOCK, NULL, active_state);
517 }
518 
519 /*
520  * Performs the interactive session.  This handles data transmission between
521  * the client and the program.  Note that the notion of stdin, stdout, and
522  * stderr in this function is sort of reversed: this function writes to
523  * stdin (of the child program), and reads from stdout and stderr (of the
524  * child program).
525  */
526 void
527 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
528 {
529 	fd_set *readset = NULL, *writeset = NULL;
530 	int max_fd = 0;
531 	u_int nalloc = 0;
532 	int wait_status;	/* Status returned by wait(). */
533 	pid_t wait_pid;		/* pid returned by wait(). */
534 	int waiting_termination = 0;	/* Have displayed waiting close message. */
535 	u_int64_t max_time_milliseconds;
536 	u_int previous_stdout_buffer_bytes;
537 	u_int stdout_buffer_bytes;
538 	int type;
539 
540 	debug("Entering interactive session.");
541 
542 	/* Initialize the SIGCHLD kludge. */
543 	child_terminated = 0;
544 	signal(SIGCHLD, sigchld_handler);
545 
546 	if (!use_privsep) {
547 		signal(SIGTERM, sigterm_handler);
548 		signal(SIGINT, sigterm_handler);
549 		signal(SIGQUIT, sigterm_handler);
550 	}
551 
552 	/* Initialize our global variables. */
553 	fdin = fdin_arg;
554 	fdout = fdout_arg;
555 	fderr = fderr_arg;
556 
557 	/* nonblocking IO */
558 	set_nonblock(fdin);
559 	set_nonblock(fdout);
560 	/* we don't have stderr for interactive terminal sessions, see below */
561 	if (fderr != -1)
562 		set_nonblock(fderr);
563 
564 	if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
565 		fdin_is_tty = 1;
566 
567 	connection_in = packet_get_connection_in();
568 	connection_out = packet_get_connection_out();
569 
570 	notify_setup();
571 
572 	previous_stdout_buffer_bytes = 0;
573 
574 	/* Set approximate I/O buffer size. */
575 	if (packet_is_interactive())
576 		buffer_high = 4096;
577 	else
578 		buffer_high = 64 * 1024;
579 
580 #if 0
581 	/* Initialize max_fd to the maximum of the known file descriptors. */
582 	max_fd = MAX(connection_in, connection_out);
583 	max_fd = MAX(max_fd, fdin);
584 	max_fd = MAX(max_fd, fdout);
585 	if (fderr != -1)
586 		max_fd = MAX(max_fd, fderr);
587 #endif
588 
589 	/* Initialize Initialize buffers. */
590 	buffer_init(&stdin_buffer);
591 	buffer_init(&stdout_buffer);
592 	buffer_init(&stderr_buffer);
593 
594 	/*
595 	 * If we have no separate fderr (which is the case when we have a pty
596 	 * - there we cannot make difference between data sent to stdout and
597 	 * stderr), indicate that we have seen an EOF from stderr.  This way
598 	 * we don't need to check the descriptor everywhere.
599 	 */
600 	if (fderr == -1)
601 		fderr_eof = 1;
602 
603 	server_init_dispatch();
604 
605 	/* Main loop of the server for the interactive session mode. */
606 	for (;;) {
607 
608 		/* Process buffered packets from the client. */
609 		process_buffered_input_packets();
610 
611 		/*
612 		 * If we have received eof, and there is no more pending
613 		 * input data, cause a real eof by closing fdin.
614 		 */
615 		if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
616 			if (fdin != fdout)
617 				close(fdin);
618 			else
619 				shutdown(fdin, SHUT_WR); /* We will no longer send. */
620 			fdin = -1;
621 		}
622 		/* Make packets from buffered stderr data to send to the client. */
623 		make_packets_from_stderr_data();
624 
625 		/*
626 		 * Make packets from buffered stdout data to send to the
627 		 * client. If there is very little to send, this arranges to
628 		 * not send them now, but to wait a short while to see if we
629 		 * are getting more data. This is necessary, as some systems
630 		 * wake up readers from a pty after each separate character.
631 		 */
632 		max_time_milliseconds = 0;
633 		stdout_buffer_bytes = buffer_len(&stdout_buffer);
634 		if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
635 		    stdout_buffer_bytes != previous_stdout_buffer_bytes) {
636 			/* try again after a while */
637 			max_time_milliseconds = 10;
638 		} else {
639 			/* Send it now. */
640 			make_packets_from_stdout_data();
641 		}
642 		previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
643 
644 		/* Send channel data to the client. */
645 		if (packet_not_very_much_data_to_write())
646 			channel_output_poll();
647 
648 		/*
649 		 * Bail out of the loop if the program has closed its output
650 		 * descriptors, and we have no more data to send to the
651 		 * client, and there is no pending buffered data.
652 		 */
653 		if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
654 		    buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
655 			if (!channel_still_open())
656 				break;
657 			if (!waiting_termination) {
658 				const char *s = "Waiting for forwarded connections to terminate...\r\n";
659 				char *cp;
660 				waiting_termination = 1;
661 				buffer_append(&stderr_buffer, s, strlen(s));
662 
663 				/* Display list of open channels. */
664 				cp = channel_open_message();
665 				buffer_append(&stderr_buffer, cp, strlen(cp));
666 				free(cp);
667 			}
668 		}
669 		max_fd = MAX(connection_in, connection_out);
670 		max_fd = MAX(max_fd, fdin);
671 		max_fd = MAX(max_fd, fdout);
672 		max_fd = MAX(max_fd, fderr);
673 		max_fd = MAX(max_fd, notify_pipe[0]);
674 
675 		/* Sleep in select() until we can do something. */
676 		wait_until_can_do_something(&readset, &writeset, &max_fd,
677 		    &nalloc, max_time_milliseconds);
678 
679 		if (received_sigterm) {
680 			logit("Exiting on signal %d", (int)received_sigterm);
681 			/* Clean up sessions, utmp, etc. */
682 			cleanup_exit(255);
683 		}
684 
685 		/* Process any channel events. */
686 		channel_after_select(readset, writeset);
687 
688 		/* Process input from the client and from program stdout/stderr. */
689 		process_input(readset);
690 
691 		/* Process output to the client and to program stdin. */
692 		process_output(writeset);
693 	}
694 	free(readset);
695 	free(writeset);
696 
697 	/* Cleanup and termination code. */
698 
699 	/* Wait until all output has been sent to the client. */
700 	drain_output();
701 
702 	debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
703 	    stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
704 
705 	/* Free and clear the buffers. */
706 	buffer_free(&stdin_buffer);
707 	buffer_free(&stdout_buffer);
708 	buffer_free(&stderr_buffer);
709 
710 	/* Close the file descriptors. */
711 	if (fdout != -1)
712 		close(fdout);
713 	fdout = -1;
714 	fdout_eof = 1;
715 	if (fderr != -1)
716 		close(fderr);
717 	fderr = -1;
718 	fderr_eof = 1;
719 	if (fdin != -1)
720 		close(fdin);
721 	fdin = -1;
722 
723 	channel_free_all();
724 
725 	/* We no longer want our SIGCHLD handler to be called. */
726 	signal(SIGCHLD, SIG_DFL);
727 
728 	while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0)
729 		if (errno != EINTR)
730 			packet_disconnect("wait: %.100s", strerror(errno));
731 	if (wait_pid != pid)
732 		error("Strange, wait returned pid %ld, expected %ld",
733 		    (long)wait_pid, (long)pid);
734 
735 	/* Check if it exited normally. */
736 	if (WIFEXITED(wait_status)) {
737 		/* Yes, normal exit.  Get exit status and send it to the client. */
738 		debug("Command exited with status %d.", WEXITSTATUS(wait_status));
739 		packet_start(SSH_SMSG_EXITSTATUS);
740 		packet_put_int(WEXITSTATUS(wait_status));
741 		packet_send();
742 		packet_write_wait();
743 
744 		/*
745 		 * Wait for exit confirmation.  Note that there might be
746 		 * other packets coming before it; however, the program has
747 		 * already died so we just ignore them.  The client is
748 		 * supposed to respond with the confirmation when it receives
749 		 * the exit status.
750 		 */
751 		do {
752 			type = packet_read();
753 		}
754 		while (type != SSH_CMSG_EXIT_CONFIRMATION);
755 
756 		debug("Received exit confirmation.");
757 		return;
758 	}
759 	/* Check if the program terminated due to a signal. */
760 	if (WIFSIGNALED(wait_status))
761 		packet_disconnect("Command terminated on signal %d.",
762 				  WTERMSIG(wait_status));
763 
764 	/* Some weird exit cause.  Just exit. */
765 	packet_disconnect("wait returned status %04x.", wait_status);
766 	/* NOTREACHED */
767 }
768 
769 static void
770 collect_children(void)
771 {
772 	pid_t pid;
773 	sigset_t oset, nset;
774 	int status;
775 
776 	/* block SIGCHLD while we check for dead children */
777 	sigemptyset(&nset);
778 	sigaddset(&nset, SIGCHLD);
779 	sigprocmask(SIG_BLOCK, &nset, &oset);
780 	if (child_terminated) {
781 		debug("Received SIGCHLD.");
782 		while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
783 		    (pid < 0 && errno == EINTR))
784 			if (pid > 0)
785 				session_close_by_pid(pid, status);
786 		child_terminated = 0;
787 	}
788 	sigprocmask(SIG_SETMASK, &oset, NULL);
789 }
790 
791 void
792 server_loop2(Authctxt *authctxt)
793 {
794 	fd_set *readset = NULL, *writeset = NULL;
795 	int max_fd;
796 	u_int nalloc = 0;
797 	u_int64_t rekey_timeout_ms = 0;
798 
799 	debug("Entering interactive session for SSH2.");
800 
801 	signal(SIGCHLD, sigchld_handler);
802 	child_terminated = 0;
803 	connection_in = packet_get_connection_in();
804 	connection_out = packet_get_connection_out();
805 
806 	if (!use_privsep) {
807 		signal(SIGTERM, sigterm_handler);
808 		signal(SIGINT, sigterm_handler);
809 		signal(SIGQUIT, sigterm_handler);
810 	}
811 
812 	notify_setup();
813 
814 	max_fd = MAX(connection_in, connection_out);
815 	max_fd = MAX(max_fd, notify_pipe[0]);
816 
817 	server_init_dispatch();
818 
819 	for (;;) {
820 		process_buffered_input_packets();
821 
822 		if (!ssh_packet_is_rekeying(active_state) &&
823 		    packet_not_very_much_data_to_write())
824 			channel_output_poll();
825 		if (options.rekey_interval > 0 && compat20 &&
826 		    !ssh_packet_is_rekeying(active_state))
827 			rekey_timeout_ms = packet_get_rekey_timeout() * 1000;
828 		else
829 			rekey_timeout_ms = 0;
830 
831 		wait_until_can_do_something(&readset, &writeset, &max_fd,
832 		    &nalloc, rekey_timeout_ms);
833 
834 		if (received_sigterm) {
835 			logit("Exiting on signal %d", (int)received_sigterm);
836 			/* Clean up sessions, utmp, etc. */
837 			cleanup_exit(255);
838 		}
839 
840 		collect_children();
841 		if (!ssh_packet_is_rekeying(active_state))
842 			channel_after_select(readset, writeset);
843 		process_input(readset);
844 		if (connection_closed)
845 			break;
846 		process_output(writeset);
847 	}
848 	collect_children();
849 
850 	free(readset);
851 	free(writeset);
852 
853 	/* free all channels, no more reads and writes */
854 	channel_free_all();
855 
856 	/* free remaining sessions, e.g. remove wtmp entries */
857 	session_destroy_all(NULL);
858 }
859 
860 static int
861 server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
862 {
863 	debug("Got %d/%u for keepalive", type, seq);
864 	/*
865 	 * reset timeout, since we got a sane answer from the client.
866 	 * even if this was generated by something other than
867 	 * the bogus CHANNEL_REQUEST we send for keepalives.
868 	 */
869 	packet_set_alive_timeouts(0);
870 	return 0;
871 }
872 
873 static int
874 server_input_stdin_data(int type, u_int32_t seq, void *ctxt)
875 {
876 	char *data;
877 	u_int data_len;
878 
879 	/* Stdin data from the client.  Append it to the buffer. */
880 	/* Ignore any data if the client has closed stdin. */
881 	if (fdin == -1)
882 		return 0;
883 	data = packet_get_string(&data_len);
884 	packet_check_eom();
885 	buffer_append(&stdin_buffer, data, data_len);
886 	explicit_bzero(data, data_len);
887 	free(data);
888 	return 0;
889 }
890 
891 static int
892 server_input_eof(int type, u_int32_t seq, void *ctxt)
893 {
894 	/*
895 	 * Eof from the client.  The stdin descriptor to the
896 	 * program will be closed when all buffered data has
897 	 * drained.
898 	 */
899 	debug("EOF received for stdin.");
900 	packet_check_eom();
901 	stdin_eof = 1;
902 	return 0;
903 }
904 
905 static int
906 server_input_window_size(int type, u_int32_t seq, void *ctxt)
907 {
908 	u_int row = packet_get_int();
909 	u_int col = packet_get_int();
910 	u_int xpixel = packet_get_int();
911 	u_int ypixel = packet_get_int();
912 
913 	debug("Window change received.");
914 	packet_check_eom();
915 	if (fdin != -1)
916 		pty_change_window_size(fdin, row, col, xpixel, ypixel);
917 	return 0;
918 }
919 
920 static Channel *
921 server_request_direct_tcpip(void)
922 {
923 	Channel *c = NULL;
924 	char *target, *originator;
925 	u_short target_port, originator_port;
926 
927 	target = packet_get_string(NULL);
928 	target_port = packet_get_int();
929 	originator = packet_get_string(NULL);
930 	originator_port = packet_get_int();
931 	packet_check_eom();
932 
933 	debug("server_request_direct_tcpip: originator %s port %d, target %s "
934 	    "port %d", originator, originator_port, target, target_port);
935 
936 	/* XXX fine grained permissions */
937 	if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
938 	    !no_port_forwarding_flag) {
939 		c = channel_connect_to_port(target, target_port,
940 		    "direct-tcpip", "direct-tcpip");
941 	} else {
942 		logit("refused local port forward: "
943 		    "originator %s port %d, target %s port %d",
944 		    originator, originator_port, target, target_port);
945 	}
946 
947 	free(originator);
948 	free(target);
949 
950 	return c;
951 }
952 
953 static Channel *
954 server_request_direct_streamlocal(void)
955 {
956 	Channel *c = NULL;
957 	char *target, *originator;
958 	u_short originator_port;
959 
960 	target = packet_get_string(NULL);
961 	originator = packet_get_string(NULL);
962 	originator_port = packet_get_int();
963 	packet_check_eom();
964 
965 	debug("server_request_direct_streamlocal: originator %s port %d, target %s",
966 	    originator, originator_port, target);
967 
968 	/* XXX fine grained permissions */
969 	if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
970 	    !no_port_forwarding_flag) {
971 		c = channel_connect_to_path(target,
972 		    "direct-streamlocal@openssh.com", "direct-streamlocal");
973 	} else {
974 		logit("refused streamlocal port forward: "
975 		    "originator %s port %d, target %s",
976 		    originator, originator_port, target);
977 	}
978 
979 	free(originator);
980 	free(target);
981 
982 	return c;
983 }
984 
985 static Channel *
986 server_request_tun(void)
987 {
988 	Channel *c = NULL;
989 	int mode, tun;
990 	int sock;
991 
992 	mode = packet_get_int();
993 	switch (mode) {
994 	case SSH_TUNMODE_POINTOPOINT:
995 	case SSH_TUNMODE_ETHERNET:
996 		break;
997 	default:
998 		packet_send_debug("Unsupported tunnel device mode.");
999 		return NULL;
1000 	}
1001 	if ((options.permit_tun & mode) == 0) {
1002 		packet_send_debug("Server has rejected tunnel device "
1003 		    "forwarding");
1004 		return NULL;
1005 	}
1006 
1007 	tun = packet_get_int();
1008 	if (forced_tun_device != -1) {
1009 		if (tun != SSH_TUNID_ANY && forced_tun_device != tun)
1010 			goto done;
1011 		tun = forced_tun_device;
1012 	}
1013 	sock = tun_open(tun, mode);
1014 	if (sock < 0)
1015 		goto done;
1016 	c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
1017 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
1018 	c->datagram = 1;
1019 
1020  done:
1021 	if (c == NULL)
1022 		packet_send_debug("Failed to open the tunnel device.");
1023 	return c;
1024 }
1025 
1026 static Channel *
1027 server_request_session(void)
1028 {
1029 	Channel *c;
1030 
1031 	debug("input_session_request");
1032 	packet_check_eom();
1033 
1034 	if (no_more_sessions) {
1035 		packet_disconnect("Possible attack: attempt to open a session "
1036 		    "after additional sessions disabled");
1037 	}
1038 
1039 	/*
1040 	 * A server session has no fd to read or write until a
1041 	 * CHANNEL_REQUEST for a shell is made, so we set the type to
1042 	 * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
1043 	 * CHANNEL_REQUEST messages is registered.
1044 	 */
1045 	c = channel_new("session", SSH_CHANNEL_LARVAL,
1046 	    -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
1047 	    0, "server-session", 1);
1048 	if (session_open(the_authctxt, c->self) != 1) {
1049 		debug("session open failed, free channel %d", c->self);
1050 		channel_free(c);
1051 		return NULL;
1052 	}
1053 	channel_register_cleanup(c->self, session_close_by_channel, 0);
1054 	return c;
1055 }
1056 
1057 static int
1058 server_input_channel_open(int type, u_int32_t seq, void *ctxt)
1059 {
1060 	Channel *c = NULL;
1061 	char *ctype;
1062 	int rchan;
1063 	u_int rmaxpack, rwindow, len;
1064 
1065 	ctype = packet_get_string(&len);
1066 	rchan = packet_get_int();
1067 	rwindow = packet_get_int();
1068 	rmaxpack = packet_get_int();
1069 
1070 	debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
1071 	    ctype, rchan, rwindow, rmaxpack);
1072 
1073 	if (strcmp(ctype, "session") == 0) {
1074 		c = server_request_session();
1075 	} else if (strcmp(ctype, "direct-tcpip") == 0) {
1076 		c = server_request_direct_tcpip();
1077 	} else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
1078 		c = server_request_direct_streamlocal();
1079 	} else if (strcmp(ctype, "tun@openssh.com") == 0) {
1080 		c = server_request_tun();
1081 	}
1082 	if (c != NULL) {
1083 		debug("server_input_channel_open: confirm %s", ctype);
1084 		c->remote_id = rchan;
1085 		c->remote_window = rwindow;
1086 		c->remote_maxpacket = rmaxpack;
1087 		if (c->type != SSH_CHANNEL_CONNECTING) {
1088 			packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1089 			packet_put_int(c->remote_id);
1090 			packet_put_int(c->self);
1091 			packet_put_int(c->local_window);
1092 			packet_put_int(c->local_maxpacket);
1093 			packet_send();
1094 		}
1095 	} else {
1096 		debug("server_input_channel_open: failure %s", ctype);
1097 		packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1098 		packet_put_int(rchan);
1099 		packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
1100 		if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1101 			packet_put_cstring("open failed");
1102 			packet_put_cstring("");
1103 		}
1104 		packet_send();
1105 	}
1106 	free(ctype);
1107 	return 0;
1108 }
1109 
1110 static int
1111 server_input_hostkeys_prove(struct sshbuf **respp)
1112 {
1113 	struct ssh *ssh = active_state; /* XXX */
1114 	struct sshbuf *resp = NULL;
1115 	struct sshbuf *sigbuf = NULL;
1116 	struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
1117 	int r, ndx, success = 0;
1118 	const u_char *blob;
1119 	u_char *sig = 0;
1120 	size_t blen, slen;
1121 
1122 	if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
1123 		fatal("%s: sshbuf_new", __func__);
1124 
1125 	while (ssh_packet_remaining(ssh) > 0) {
1126 		sshkey_free(key);
1127 		key = NULL;
1128 		if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
1129 		    (r = sshkey_from_blob(blob, blen, &key)) != 0) {
1130 			error("%s: couldn't parse key: %s",
1131 			    __func__, ssh_err(r));
1132 			goto out;
1133 		}
1134 		/*
1135 		 * Better check that this is actually one of our hostkeys
1136 		 * before attempting to sign anything with it.
1137 		 */
1138 		if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
1139 			error("%s: unknown host %s key",
1140 			    __func__, sshkey_type(key));
1141 			goto out;
1142 		}
1143 		/*
1144 		 * XXX refactor: make kex->sign just use an index rather
1145 		 * than passing in public and private keys
1146 		 */
1147 		if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
1148 		    (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
1149 			error("%s: can't retrieve hostkey %d", __func__, ndx);
1150 			goto out;
1151 		}
1152 		sshbuf_reset(sigbuf);
1153 		free(sig);
1154 		sig = NULL;
1155 		if ((r = sshbuf_put_cstring(sigbuf,
1156 		    "hostkeys-prove-00@openssh.com")) != 0 ||
1157 		    (r = sshbuf_put_string(sigbuf,
1158 		    ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
1159 		    (r = sshkey_puts(key, sigbuf)) != 0 ||
1160 		    (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen,
1161 		    sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 ||
1162 		    (r = sshbuf_put_string(resp, sig, slen)) != 0) {
1163 			error("%s: couldn't prepare signature: %s",
1164 			    __func__, ssh_err(r));
1165 			goto out;
1166 		}
1167 	}
1168 	/* Success */
1169 	*respp = resp;
1170 	resp = NULL; /* don't free it */
1171 	success = 1;
1172  out:
1173 	free(sig);
1174 	sshbuf_free(resp);
1175 	sshbuf_free(sigbuf);
1176 	sshkey_free(key);
1177 	return success;
1178 }
1179 
1180 static int
1181 server_input_global_request(int type, u_int32_t seq, void *ctxt)
1182 {
1183 	char *rtype;
1184 	int want_reply;
1185 	int r, success = 0, allocated_listen_port = 0;
1186 	struct sshbuf *resp = NULL;
1187 
1188 	rtype = packet_get_string(NULL);
1189 	want_reply = packet_get_char();
1190 	debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
1191 
1192 	/* -R style forwarding */
1193 	if (strcmp(rtype, "tcpip-forward") == 0) {
1194 		struct passwd *pw;
1195 		struct Forward fwd;
1196 
1197 		pw = the_authctxt->pw;
1198 		if (pw == NULL || !the_authctxt->valid)
1199 			fatal("server_input_global_request: no/invalid user");
1200 		memset(&fwd, 0, sizeof(fwd));
1201 		fwd.listen_host = packet_get_string(NULL);
1202 		fwd.listen_port = (u_short)packet_get_int();
1203 		debug("server_input_global_request: tcpip-forward listen %s port %d",
1204 		    fwd.listen_host, fwd.listen_port);
1205 
1206 		/* check permissions */
1207 		if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
1208 		    no_port_forwarding_flag ||
1209 		    (!want_reply && fwd.listen_port == 0) ||
1210 		    (fwd.listen_port != 0 && fwd.listen_port < IPPORT_RESERVED &&
1211 		    pw->pw_uid != 0)) {
1212 			success = 0;
1213 			packet_send_debug("Server has disabled port forwarding.");
1214 		} else {
1215 			/* Start listening on the port */
1216 			success = channel_setup_remote_fwd_listener(&fwd,
1217 			    &allocated_listen_port, &options.fwd_opts);
1218 		}
1219 		free(fwd.listen_host);
1220 		if ((resp = sshbuf_new()) == NULL)
1221 			fatal("%s: sshbuf_new", __func__);
1222 		if (allocated_listen_port != 0 &&
1223 		    (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
1224 			fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
1225 	} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
1226 		struct Forward fwd;
1227 
1228 		memset(&fwd, 0, sizeof(fwd));
1229 		fwd.listen_host = packet_get_string(NULL);
1230 		fwd.listen_port = (u_short)packet_get_int();
1231 		debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
1232 		    fwd.listen_host, fwd.listen_port);
1233 
1234 		success = channel_cancel_rport_listener(&fwd);
1235 		free(fwd.listen_host);
1236 	} else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
1237 		struct Forward fwd;
1238 
1239 		memset(&fwd, 0, sizeof(fwd));
1240 		fwd.listen_path = packet_get_string(NULL);
1241 		debug("server_input_global_request: streamlocal-forward listen path %s",
1242 		    fwd.listen_path);
1243 
1244 		/* check permissions */
1245 		if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
1246 		    || no_port_forwarding_flag) {
1247 			success = 0;
1248 			packet_send_debug("Server has disabled port forwarding.");
1249 		} else {
1250 			/* Start listening on the socket */
1251 			success = channel_setup_remote_fwd_listener(
1252 			    &fwd, NULL, &options.fwd_opts);
1253 		}
1254 		free(fwd.listen_path);
1255 	} else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
1256 		struct Forward fwd;
1257 
1258 		memset(&fwd, 0, sizeof(fwd));
1259 		fwd.listen_path = packet_get_string(NULL);
1260 		debug("%s: cancel-streamlocal-forward path %s", __func__,
1261 		    fwd.listen_path);
1262 
1263 		success = channel_cancel_rport_listener(&fwd);
1264 		free(fwd.listen_path);
1265 	} else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
1266 		no_more_sessions = 1;
1267 		success = 1;
1268 	} else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
1269 		success = server_input_hostkeys_prove(&resp);
1270 	}
1271 	if (want_reply) {
1272 		packet_start(success ?
1273 		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
1274 		if (success && resp != NULL)
1275 			ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
1276 			    sshbuf_len(resp));
1277 		packet_send();
1278 		packet_write_wait();
1279 	}
1280 	free(rtype);
1281 	sshbuf_free(resp);
1282 	return 0;
1283 }
1284 
1285 static int
1286 server_input_channel_req(int type, u_int32_t seq, void *ctxt)
1287 {
1288 	Channel *c;
1289 	int id, reply, success = 0;
1290 	char *rtype;
1291 
1292 	id = packet_get_int();
1293 	rtype = packet_get_string(NULL);
1294 	reply = packet_get_char();
1295 
1296 	debug("server_input_channel_req: channel %d request %s reply %d",
1297 	    id, rtype, reply);
1298 
1299 	if ((c = channel_lookup(id)) == NULL)
1300 		packet_disconnect("server_input_channel_req: "
1301 		    "unknown channel %d", id);
1302 	if (!strcmp(rtype, "eow@openssh.com")) {
1303 		packet_check_eom();
1304 		chan_rcvd_eow(c);
1305 	} else if ((c->type == SSH_CHANNEL_LARVAL ||
1306 	    c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
1307 		success = session_input_channel_req(c, rtype);
1308 	if (reply && !(c->flags & CHAN_CLOSE_SENT)) {
1309 		packet_start(success ?
1310 		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1311 		packet_put_int(c->remote_id);
1312 		packet_send();
1313 	}
1314 	free(rtype);
1315 	return 0;
1316 }
1317 
1318 static void
1319 server_init_dispatch_20(void)
1320 {
1321 	debug("server_init_dispatch_20");
1322 	dispatch_init(&dispatch_protocol_error);
1323 	dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
1324 	dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
1325 	dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
1326 	dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
1327 	dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
1328 	dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1329 	dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1330 	dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
1331 	dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
1332 	dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
1333 	/* client_alive */
1334 	dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
1335 	dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
1336 	dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
1337 	dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
1338 	/* rekeying */
1339 	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1340 }
1341 static void
1342 server_init_dispatch_13(void)
1343 {
1344 	debug("server_init_dispatch_13");
1345 	dispatch_init(NULL);
1346 	dispatch_set(SSH_CMSG_EOF, &server_input_eof);
1347 	dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
1348 	dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
1349 	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
1350 	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
1351 	dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
1352 	dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1353 	dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1354 	dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
1355 }
1356 static void
1357 server_init_dispatch_15(void)
1358 {
1359 	server_init_dispatch_13();
1360 	debug("server_init_dispatch_15");
1361 	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
1362 	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
1363 }
1364 static void
1365 server_init_dispatch(void)
1366 {
1367 	if (compat20)
1368 		server_init_dispatch_20();
1369 	else if (compat13)
1370 		server_init_dispatch_13();
1371 	else
1372 		server_init_dispatch_15();
1373 }
1374