xref: /freebsd/crypto/openssh/serverloop.c (revision 86c9d9918f1db7cdd968b60f8902466887bcd9e9)
1 /* $OpenBSD: serverloop.c,v 1.182 2016/02/08 10:57:07 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 "includes.h"
39 
40 #include <sys/param.h>	/* MIN MAX */
41 #include <sys/types.h>
42 #include <sys/wait.h>
43 #include <sys/socket.h>
44 #ifdef HAVE_SYS_TIME_H
45 # include <sys/time.h>
46 #endif
47 
48 #include <netinet/in.h>
49 
50 #include <errno.h>
51 #include <fcntl.h>
52 #include <pwd.h>
53 #include <signal.h>
54 #include <string.h>
55 #include <termios.h>
56 #include <unistd.h>
57 #include <stdarg.h>
58 
59 #include "openbsd-compat/sys-queue.h"
60 #include "xmalloc.h"
61 #include "packet.h"
62 #include "buffer.h"
63 #include "log.h"
64 #include "misc.h"
65 #include "servconf.h"
66 #include "canohost.h"
67 #include "sshpty.h"
68 #include "channels.h"
69 #include "compat.h"
70 #include "ssh1.h"
71 #include "ssh2.h"
72 #include "key.h"
73 #include "cipher.h"
74 #include "kex.h"
75 #include "hostfile.h"
76 #include "auth.h"
77 #include "session.h"
78 #include "dispatch.h"
79 #include "auth-options.h"
80 #include "serverloop.h"
81 #include "ssherr.h"
82 
83 extern ServerOptions options;
84 
85 /* XXX */
86 extern Authctxt *the_authctxt;
87 extern int use_privsep;
88 
89 static Buffer stdin_buffer;	/* Buffer for stdin data. */
90 static Buffer stdout_buffer;	/* Buffer for stdout data. */
91 static Buffer stderr_buffer;	/* Buffer for stderr data. */
92 static int fdin;		/* Descriptor for stdin (for writing) */
93 static int fdout;		/* Descriptor for stdout (for reading);
94 				   May be same number as fdin. */
95 static int fderr;		/* Descriptor for stderr.  May be -1. */
96 static long stdin_bytes = 0;	/* Number of bytes written to stdin. */
97 static long stdout_bytes = 0;	/* Number of stdout bytes sent to client. */
98 static long stderr_bytes = 0;	/* Number of stderr bytes sent to client. */
99 static long fdout_bytes = 0;	/* Number of stdout bytes read from program. */
100 static int stdin_eof = 0;	/* EOF message received from client. */
101 static int fdout_eof = 0;	/* EOF encountered reading from fdout. */
102 static int fderr_eof = 0;	/* EOF encountered readung from fderr. */
103 static int fdin_is_tty = 0;	/* fdin points to a tty. */
104 static int connection_in;	/* Connection to client (input). */
105 static int connection_out;	/* Connection to client (output). */
106 static int connection_closed = 0;	/* Connection to client closed. */
107 static u_int buffer_high;	/* "Soft" max buffer size. */
108 static int no_more_sessions = 0; /* Disallow further sessions. */
109 
110 /*
111  * This SIGCHLD kludge is used to detect when the child exits.  The server
112  * will exit after that, as soon as forwarded connections have terminated.
113  */
114 
115 static volatile sig_atomic_t child_terminated = 0;	/* The child has terminated. */
116 
117 /* Cleanup on signals (!use_privsep case only) */
118 static volatile sig_atomic_t received_sigterm = 0;
119 
120 /* prototypes */
121 static void server_init_dispatch(void);
122 
123 /*
124  * we write to this pipe if a SIGCHLD is caught in order to avoid
125  * the race between select() and child_terminated
126  */
127 static int notify_pipe[2];
128 static void
129 notify_setup(void)
130 {
131 	if (pipe(notify_pipe) < 0) {
132 		error("pipe(notify_pipe) failed %s", strerror(errno));
133 	} else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) ||
134 	    (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) {
135 		error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno));
136 		close(notify_pipe[0]);
137 		close(notify_pipe[1]);
138 	} else {
139 		set_nonblock(notify_pipe[0]);
140 		set_nonblock(notify_pipe[1]);
141 		return;
142 	}
143 	notify_pipe[0] = -1;	/* read end */
144 	notify_pipe[1] = -1;	/* write end */
145 }
146 static void
147 notify_parent(void)
148 {
149 	if (notify_pipe[1] != -1)
150 		(void)write(notify_pipe[1], "", 1);
151 }
152 static void
153 notify_prepare(fd_set *readset)
154 {
155 	if (notify_pipe[0] != -1)
156 		FD_SET(notify_pipe[0], readset);
157 }
158 static void
159 notify_done(fd_set *readset)
160 {
161 	char c;
162 
163 	if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
164 		while (read(notify_pipe[0], &c, 1) != -1)
165 			debug2("notify_done: reading");
166 }
167 
168 /*ARGSUSED*/
169 static void
170 sigchld_handler(int sig)
171 {
172 	int save_errno = errno;
173 	child_terminated = 1;
174 #ifndef _UNICOS
175 	mysignal(SIGCHLD, sigchld_handler);
176 #endif
177 	notify_parent();
178 	errno = save_errno;
179 }
180 
181 /*ARGSUSED*/
182 static void
183 sigterm_handler(int sig)
184 {
185 	received_sigterm = sig;
186 }
187 
188 /*
189  * Make packets from buffered stderr data, and buffer it for sending
190  * to the client.
191  */
192 static void
193 make_packets_from_stderr_data(void)
194 {
195 	u_int len;
196 
197 	/* Send buffered stderr data to the client. */
198 	while (buffer_len(&stderr_buffer) > 0 &&
199 	    packet_not_very_much_data_to_write()) {
200 		len = buffer_len(&stderr_buffer);
201 		if (packet_is_interactive()) {
202 			if (len > 512)
203 				len = 512;
204 		} else {
205 			/* Keep the packets at reasonable size. */
206 			if (len > packet_get_maxsize())
207 				len = packet_get_maxsize();
208 		}
209 		packet_start(SSH_SMSG_STDERR_DATA);
210 		packet_put_string(buffer_ptr(&stderr_buffer), len);
211 		packet_send();
212 		buffer_consume(&stderr_buffer, len);
213 		stderr_bytes += len;
214 	}
215 }
216 
217 /*
218  * Make packets from buffered stdout data, and buffer it for sending to the
219  * client.
220  */
221 static void
222 make_packets_from_stdout_data(void)
223 {
224 	u_int len;
225 
226 	/* Send buffered stdout data to the client. */
227 	while (buffer_len(&stdout_buffer) > 0 &&
228 	    packet_not_very_much_data_to_write()) {
229 		len = buffer_len(&stdout_buffer);
230 		if (packet_is_interactive()) {
231 			if (len > 512)
232 				len = 512;
233 		} else {
234 			/* Keep the packets at reasonable size. */
235 			if (len > packet_get_maxsize())
236 				len = packet_get_maxsize();
237 		}
238 		packet_start(SSH_SMSG_STDOUT_DATA);
239 		packet_put_string(buffer_ptr(&stdout_buffer), len);
240 		packet_send();
241 		buffer_consume(&stdout_buffer, len);
242 		stdout_bytes += len;
243 	}
244 }
245 
246 static void
247 client_alive_check(void)
248 {
249 	int channel_id;
250 
251 	/* timeout, check to see how many we have had */
252 	if (packet_inc_alive_timeouts() > options.client_alive_count_max) {
253 		logit("Timeout, client not responding.");
254 		cleanup_exit(255);
255 	}
256 
257 	/*
258 	 * send a bogus global/channel request with "wantreply",
259 	 * we should get back a failure
260 	 */
261 	if ((channel_id = channel_find_open()) == -1) {
262 		packet_start(SSH2_MSG_GLOBAL_REQUEST);
263 		packet_put_cstring("keepalive@openssh.com");
264 		packet_put_char(1);	/* boolean: want reply */
265 	} else {
266 		channel_request_start(channel_id, "keepalive@openssh.com", 1);
267 	}
268 	packet_send();
269 }
270 
271 /*
272  * Sleep in select() until we can do something.  This will initialize the
273  * select masks.  Upon return, the masks will indicate which descriptors
274  * have data or can accept data.  Optionally, a maximum time can be specified
275  * for the duration of the wait (0 = infinite).
276  */
277 static void
278 wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
279     u_int *nallocp, u_int64_t max_time_milliseconds)
280 {
281 	struct timeval tv, *tvp;
282 	int ret;
283 	time_t minwait_secs = 0;
284 	int client_alive_scheduled = 0;
285 	int program_alive_scheduled = 0;
286 
287 	/* Allocate and update select() masks for channel descriptors. */
288 	channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
289 	    &minwait_secs, 0);
290 
291 	if (minwait_secs != 0)
292 		max_time_milliseconds = MIN(max_time_milliseconds,
293 		    (u_int)minwait_secs * 1000);
294 
295 	/*
296 	 * if using client_alive, set the max timeout accordingly,
297 	 * and indicate that this particular timeout was for client
298 	 * alive by setting the client_alive_scheduled flag.
299 	 *
300 	 * this could be randomized somewhat to make traffic
301 	 * analysis more difficult, but we're not doing it yet.
302 	 */
303 	if (compat20 &&
304 	    max_time_milliseconds == 0 && options.client_alive_interval) {
305 		client_alive_scheduled = 1;
306 		max_time_milliseconds =
307 		    (u_int64_t)options.client_alive_interval * 1000;
308 	}
309 
310 	if (compat20) {
311 #if 0
312 		/* wrong: bad condition XXX */
313 		if (channel_not_very_much_buffered_data())
314 #endif
315 		FD_SET(connection_in, *readsetp);
316 	} else {
317 		/*
318 		 * Read packets from the client unless we have too much
319 		 * buffered stdin or channel data.
320 		 */
321 		if (buffer_len(&stdin_buffer) < buffer_high &&
322 		    channel_not_very_much_buffered_data())
323 			FD_SET(connection_in, *readsetp);
324 		/*
325 		 * If there is not too much data already buffered going to
326 		 * the client, try to get some more data from the program.
327 		 */
328 		if (packet_not_very_much_data_to_write()) {
329 			program_alive_scheduled = child_terminated;
330 			if (!fdout_eof)
331 				FD_SET(fdout, *readsetp);
332 			if (!fderr_eof)
333 				FD_SET(fderr, *readsetp);
334 		}
335 		/*
336 		 * If we have buffered data, try to write some of that data
337 		 * to the program.
338 		 */
339 		if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
340 			FD_SET(fdin, *writesetp);
341 	}
342 	notify_prepare(*readsetp);
343 
344 	/*
345 	 * If we have buffered packet data going to the client, mark that
346 	 * descriptor.
347 	 */
348 	if (packet_have_data_to_write())
349 		FD_SET(connection_out, *writesetp);
350 
351 	/*
352 	 * If child has terminated and there is enough buffer space to read
353 	 * from it, then read as much as is available and exit.
354 	 */
355 	if (child_terminated && packet_not_very_much_data_to_write())
356 		if (max_time_milliseconds == 0 || client_alive_scheduled)
357 			max_time_milliseconds = 100;
358 
359 	if (max_time_milliseconds == 0)
360 		tvp = NULL;
361 	else {
362 		tv.tv_sec = max_time_milliseconds / 1000;
363 		tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
364 		tvp = &tv;
365 	}
366 
367 	/* Wait for something to happen, or the timeout to expire. */
368 	ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
369 
370 	if (ret == -1) {
371 		memset(*readsetp, 0, *nallocp);
372 		memset(*writesetp, 0, *nallocp);
373 		if (errno != EINTR)
374 			error("select: %.100s", strerror(errno));
375 	} else {
376 		if (ret == 0 && client_alive_scheduled)
377 			client_alive_check();
378 		if (!compat20 && program_alive_scheduled && fdin_is_tty) {
379 			if (!fdout_eof)
380 				FD_SET(fdout, *readsetp);
381 			if (!fderr_eof)
382 				FD_SET(fderr, *readsetp);
383 		}
384 	}
385 
386 	notify_done(*readsetp);
387 }
388 
389 /*
390  * Processes input from the client and the program.  Input data is stored
391  * in buffers and processed later.
392  */
393 static void
394 process_input(fd_set *readset)
395 {
396 	int len;
397 	char buf[16384];
398 
399 	/* Read and buffer any input data from the client. */
400 	if (FD_ISSET(connection_in, readset)) {
401 		len = read(connection_in, buf, sizeof(buf));
402 		if (len == 0) {
403 			verbose("Connection closed by %.100s",
404 			    get_remote_ipaddr());
405 			connection_closed = 1;
406 			if (compat20)
407 				return;
408 			cleanup_exit(255);
409 		} else if (len < 0) {
410 			if (errno != EINTR && errno != EAGAIN &&
411 			    errno != EWOULDBLOCK) {
412 				verbose("Read error from remote host "
413 				    "%.100s: %.100s",
414 				    get_remote_ipaddr(), strerror(errno));
415 				cleanup_exit(255);
416 			}
417 		} else {
418 			/* Buffer any received data. */
419 			packet_process_incoming(buf, len);
420 		}
421 	}
422 	if (compat20)
423 		return;
424 
425 	/* Read and buffer any available stdout data from the program. */
426 	if (!fdout_eof && FD_ISSET(fdout, readset)) {
427 		errno = 0;
428 		len = read(fdout, buf, sizeof(buf));
429 		if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
430 		    errno == EWOULDBLOCK) && !child_terminated))) {
431 			/* do nothing */
432 #ifndef PTY_ZEROREAD
433 		} else if (len <= 0) {
434 #else
435 		} else if ((!isatty(fdout) && len <= 0) ||
436 		    (isatty(fdout) && (len < 0 || (len == 0 && errno != 0)))) {
437 #endif
438 			fdout_eof = 1;
439 		} else {
440 			buffer_append(&stdout_buffer, buf, len);
441 			fdout_bytes += len;
442 		}
443 	}
444 	/* Read and buffer any available stderr data from the program. */
445 	if (!fderr_eof && FD_ISSET(fderr, readset)) {
446 		errno = 0;
447 		len = read(fderr, buf, sizeof(buf));
448 		if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
449 		    errno == EWOULDBLOCK) && !child_terminated))) {
450 			/* do nothing */
451 #ifndef PTY_ZEROREAD
452 		} else if (len <= 0) {
453 #else
454 		} else if ((!isatty(fderr) && len <= 0) ||
455 		    (isatty(fderr) && (len < 0 || (len == 0 && errno != 0)))) {
456 #endif
457 			fderr_eof = 1;
458 		} else {
459 			buffer_append(&stderr_buffer, buf, len);
460 		}
461 	}
462 }
463 
464 /*
465  * Sends data from internal buffers to client program stdin.
466  */
467 static void
468 process_output(fd_set *writeset)
469 {
470 	struct termios tio;
471 	u_char *data;
472 	u_int dlen;
473 	int len;
474 
475 	/* Write buffered data to program stdin. */
476 	if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
477 		data = buffer_ptr(&stdin_buffer);
478 		dlen = buffer_len(&stdin_buffer);
479 		len = write(fdin, data, dlen);
480 		if (len < 0 &&
481 		    (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) {
482 			/* do nothing */
483 		} else if (len <= 0) {
484 			if (fdin != fdout)
485 				close(fdin);
486 			else
487 				shutdown(fdin, SHUT_WR); /* We will no longer send. */
488 			fdin = -1;
489 		} else {
490 			/* Successful write. */
491 			if (fdin_is_tty && dlen >= 1 && data[0] != '\r' &&
492 			    tcgetattr(fdin, &tio) == 0 &&
493 			    !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
494 				/*
495 				 * Simulate echo to reduce the impact of
496 				 * traffic analysis
497 				 */
498 				packet_send_ignore(len);
499 				packet_send();
500 			}
501 			/* Consume the data from the buffer. */
502 			buffer_consume(&stdin_buffer, len);
503 			/* Update the count of bytes written to the program. */
504 			stdin_bytes += len;
505 		}
506 	}
507 	/* Send any buffered packet data to the client. */
508 	if (FD_ISSET(connection_out, writeset))
509 		packet_write_poll();
510 }
511 
512 /*
513  * Wait until all buffered output has been sent to the client.
514  * This is used when the program terminates.
515  */
516 static void
517 drain_output(void)
518 {
519 	/* Send any buffered stdout data to the client. */
520 	if (buffer_len(&stdout_buffer) > 0) {
521 		packet_start(SSH_SMSG_STDOUT_DATA);
522 		packet_put_string(buffer_ptr(&stdout_buffer),
523 				  buffer_len(&stdout_buffer));
524 		packet_send();
525 		/* Update the count of sent bytes. */
526 		stdout_bytes += buffer_len(&stdout_buffer);
527 	}
528 	/* Send any buffered stderr data to the client. */
529 	if (buffer_len(&stderr_buffer) > 0) {
530 		packet_start(SSH_SMSG_STDERR_DATA);
531 		packet_put_string(buffer_ptr(&stderr_buffer),
532 				  buffer_len(&stderr_buffer));
533 		packet_send();
534 		/* Update the count of sent bytes. */
535 		stderr_bytes += buffer_len(&stderr_buffer);
536 	}
537 	/* Wait until all buffered data has been written to the client. */
538 	packet_write_wait();
539 }
540 
541 static void
542 process_buffered_input_packets(void)
543 {
544 	dispatch_run(DISPATCH_NONBLOCK, NULL, active_state);
545 }
546 
547 /*
548  * Performs the interactive session.  This handles data transmission between
549  * the client and the program.  Note that the notion of stdin, stdout, and
550  * stderr in this function is sort of reversed: this function writes to
551  * stdin (of the child program), and reads from stdout and stderr (of the
552  * child program).
553  */
554 void
555 server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
556 {
557 	fd_set *readset = NULL, *writeset = NULL;
558 	int max_fd = 0;
559 	u_int nalloc = 0;
560 	int wait_status;	/* Status returned by wait(). */
561 	pid_t wait_pid;		/* pid returned by wait(). */
562 	int waiting_termination = 0;	/* Have displayed waiting close message. */
563 	u_int64_t max_time_milliseconds;
564 	u_int previous_stdout_buffer_bytes;
565 	u_int stdout_buffer_bytes;
566 	int type;
567 
568 	debug("Entering interactive session.");
569 
570 	/* Initialize the SIGCHLD kludge. */
571 	child_terminated = 0;
572 	mysignal(SIGCHLD, sigchld_handler);
573 
574 	if (!use_privsep) {
575 		signal(SIGTERM, sigterm_handler);
576 		signal(SIGINT, sigterm_handler);
577 		signal(SIGQUIT, sigterm_handler);
578 	}
579 
580 	/* Initialize our global variables. */
581 	fdin = fdin_arg;
582 	fdout = fdout_arg;
583 	fderr = fderr_arg;
584 
585 	/* nonblocking IO */
586 	set_nonblock(fdin);
587 	set_nonblock(fdout);
588 	/* we don't have stderr for interactive terminal sessions, see below */
589 	if (fderr != -1)
590 		set_nonblock(fderr);
591 
592 	if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
593 		fdin_is_tty = 1;
594 
595 	connection_in = packet_get_connection_in();
596 	connection_out = packet_get_connection_out();
597 
598 	notify_setup();
599 
600 	previous_stdout_buffer_bytes = 0;
601 
602 	/* Set approximate I/O buffer size. */
603 	if (packet_is_interactive())
604 		buffer_high = 4096;
605 	else
606 		buffer_high = 64 * 1024;
607 
608 #if 0
609 	/* Initialize max_fd to the maximum of the known file descriptors. */
610 	max_fd = MAX(connection_in, connection_out);
611 	max_fd = MAX(max_fd, fdin);
612 	max_fd = MAX(max_fd, fdout);
613 	if (fderr != -1)
614 		max_fd = MAX(max_fd, fderr);
615 #endif
616 
617 	/* Initialize Initialize buffers. */
618 	buffer_init(&stdin_buffer);
619 	buffer_init(&stdout_buffer);
620 	buffer_init(&stderr_buffer);
621 
622 	/*
623 	 * If we have no separate fderr (which is the case when we have a pty
624 	 * - there we cannot make difference between data sent to stdout and
625 	 * stderr), indicate that we have seen an EOF from stderr.  This way
626 	 * we don't need to check the descriptor everywhere.
627 	 */
628 	if (fderr == -1)
629 		fderr_eof = 1;
630 
631 	server_init_dispatch();
632 
633 	/* Main loop of the server for the interactive session mode. */
634 	for (;;) {
635 
636 		/* Process buffered packets from the client. */
637 		process_buffered_input_packets();
638 
639 		/*
640 		 * If we have received eof, and there is no more pending
641 		 * input data, cause a real eof by closing fdin.
642 		 */
643 		if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
644 			if (fdin != fdout)
645 				close(fdin);
646 			else
647 				shutdown(fdin, SHUT_WR); /* We will no longer send. */
648 			fdin = -1;
649 		}
650 		/* Make packets from buffered stderr data to send to the client. */
651 		make_packets_from_stderr_data();
652 
653 		/*
654 		 * Make packets from buffered stdout data to send to the
655 		 * client. If there is very little to send, this arranges to
656 		 * not send them now, but to wait a short while to see if we
657 		 * are getting more data. This is necessary, as some systems
658 		 * wake up readers from a pty after each separate character.
659 		 */
660 		max_time_milliseconds = 0;
661 		stdout_buffer_bytes = buffer_len(&stdout_buffer);
662 		if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
663 		    stdout_buffer_bytes != previous_stdout_buffer_bytes) {
664 			/* try again after a while */
665 			max_time_milliseconds = 10;
666 		} else {
667 			/* Send it now. */
668 			make_packets_from_stdout_data();
669 		}
670 		previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
671 
672 		/* Send channel data to the client. */
673 		if (packet_not_very_much_data_to_write())
674 			channel_output_poll();
675 
676 		/*
677 		 * Bail out of the loop if the program has closed its output
678 		 * descriptors, and we have no more data to send to the
679 		 * client, and there is no pending buffered data.
680 		 */
681 		if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
682 		    buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
683 			if (!channel_still_open())
684 				break;
685 			if (!waiting_termination) {
686 				const char *s = "Waiting for forwarded connections to terminate...\r\n";
687 				char *cp;
688 				waiting_termination = 1;
689 				buffer_append(&stderr_buffer, s, strlen(s));
690 
691 				/* Display list of open channels. */
692 				cp = channel_open_message();
693 				buffer_append(&stderr_buffer, cp, strlen(cp));
694 				free(cp);
695 			}
696 		}
697 		max_fd = MAX(connection_in, connection_out);
698 		max_fd = MAX(max_fd, fdin);
699 		max_fd = MAX(max_fd, fdout);
700 		max_fd = MAX(max_fd, fderr);
701 		max_fd = MAX(max_fd, notify_pipe[0]);
702 
703 		/* Sleep in select() until we can do something. */
704 		wait_until_can_do_something(&readset, &writeset, &max_fd,
705 		    &nalloc, max_time_milliseconds);
706 
707 		if (received_sigterm) {
708 			logit("Exiting on signal %d", (int)received_sigterm);
709 			/* Clean up sessions, utmp, etc. */
710 			cleanup_exit(255);
711 		}
712 
713 		/* Process any channel events. */
714 		channel_after_select(readset, writeset);
715 
716 		/* Process input from the client and from program stdout/stderr. */
717 		process_input(readset);
718 
719 		/* Process output to the client and to program stdin. */
720 		process_output(writeset);
721 	}
722 	free(readset);
723 	free(writeset);
724 
725 	/* Cleanup and termination code. */
726 
727 	/* Wait until all output has been sent to the client. */
728 	drain_output();
729 
730 	debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
731 	    stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
732 
733 	/* Free and clear the buffers. */
734 	buffer_free(&stdin_buffer);
735 	buffer_free(&stdout_buffer);
736 	buffer_free(&stderr_buffer);
737 
738 	/* Close the file descriptors. */
739 	if (fdout != -1)
740 		close(fdout);
741 	fdout = -1;
742 	fdout_eof = 1;
743 	if (fderr != -1)
744 		close(fderr);
745 	fderr = -1;
746 	fderr_eof = 1;
747 	if (fdin != -1)
748 		close(fdin);
749 	fdin = -1;
750 
751 	channel_free_all();
752 
753 	/* We no longer want our SIGCHLD handler to be called. */
754 	mysignal(SIGCHLD, SIG_DFL);
755 
756 	while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0)
757 		if (errno != EINTR)
758 			packet_disconnect("wait: %.100s", strerror(errno));
759 	if (wait_pid != pid)
760 		error("Strange, wait returned pid %ld, expected %ld",
761 		    (long)wait_pid, (long)pid);
762 
763 	/* Check if it exited normally. */
764 	if (WIFEXITED(wait_status)) {
765 		/* Yes, normal exit.  Get exit status and send it to the client. */
766 		debug("Command exited with status %d.", WEXITSTATUS(wait_status));
767 		packet_start(SSH_SMSG_EXITSTATUS);
768 		packet_put_int(WEXITSTATUS(wait_status));
769 		packet_send();
770 		packet_write_wait();
771 
772 		/*
773 		 * Wait for exit confirmation.  Note that there might be
774 		 * other packets coming before it; however, the program has
775 		 * already died so we just ignore them.  The client is
776 		 * supposed to respond with the confirmation when it receives
777 		 * the exit status.
778 		 */
779 		do {
780 			type = packet_read();
781 		}
782 		while (type != SSH_CMSG_EXIT_CONFIRMATION);
783 
784 		debug("Received exit confirmation.");
785 		return;
786 	}
787 	/* Check if the program terminated due to a signal. */
788 	if (WIFSIGNALED(wait_status))
789 		packet_disconnect("Command terminated on signal %d.",
790 				  WTERMSIG(wait_status));
791 
792 	/* Some weird exit cause.  Just exit. */
793 	packet_disconnect("wait returned status %04x.", wait_status);
794 	/* NOTREACHED */
795 }
796 
797 static void
798 collect_children(void)
799 {
800 	pid_t pid;
801 	sigset_t oset, nset;
802 	int status;
803 
804 	/* block SIGCHLD while we check for dead children */
805 	sigemptyset(&nset);
806 	sigaddset(&nset, SIGCHLD);
807 	sigprocmask(SIG_BLOCK, &nset, &oset);
808 	if (child_terminated) {
809 		debug("Received SIGCHLD.");
810 		while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
811 		    (pid < 0 && errno == EINTR))
812 			if (pid > 0)
813 				session_close_by_pid(pid, status);
814 		child_terminated = 0;
815 	}
816 	sigprocmask(SIG_SETMASK, &oset, NULL);
817 }
818 
819 void
820 server_loop2(Authctxt *authctxt)
821 {
822 	fd_set *readset = NULL, *writeset = NULL;
823 	int max_fd;
824 	u_int nalloc = 0;
825 	u_int64_t rekey_timeout_ms = 0;
826 
827 	debug("Entering interactive session for SSH2.");
828 
829 	mysignal(SIGCHLD, sigchld_handler);
830 	child_terminated = 0;
831 	connection_in = packet_get_connection_in();
832 	connection_out = packet_get_connection_out();
833 
834 	if (!use_privsep) {
835 		signal(SIGTERM, sigterm_handler);
836 		signal(SIGINT, sigterm_handler);
837 		signal(SIGQUIT, sigterm_handler);
838 	}
839 
840 	notify_setup();
841 
842 	max_fd = MAX(connection_in, connection_out);
843 	max_fd = MAX(max_fd, notify_pipe[0]);
844 
845 	server_init_dispatch();
846 
847 	for (;;) {
848 		process_buffered_input_packets();
849 
850 		if (!ssh_packet_is_rekeying(active_state) &&
851 		    packet_not_very_much_data_to_write())
852 			channel_output_poll();
853 		if (options.rekey_interval > 0 && compat20 &&
854 		    !ssh_packet_is_rekeying(active_state))
855 			rekey_timeout_ms = packet_get_rekey_timeout() * 1000;
856 		else
857 			rekey_timeout_ms = 0;
858 
859 		wait_until_can_do_something(&readset, &writeset, &max_fd,
860 		    &nalloc, rekey_timeout_ms);
861 
862 		if (received_sigterm) {
863 			logit("Exiting on signal %d", (int)received_sigterm);
864 			/* Clean up sessions, utmp, etc. */
865 			cleanup_exit(255);
866 		}
867 
868 		collect_children();
869 		if (!ssh_packet_is_rekeying(active_state))
870 			channel_after_select(readset, writeset);
871 		process_input(readset);
872 		if (connection_closed)
873 			break;
874 		process_output(writeset);
875 	}
876 	collect_children();
877 
878 	free(readset);
879 	free(writeset);
880 
881 	/* free all channels, no more reads and writes */
882 	channel_free_all();
883 
884 	/* free remaining sessions, e.g. remove wtmp entries */
885 	session_destroy_all(NULL);
886 }
887 
888 static int
889 server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
890 {
891 	debug("Got %d/%u for keepalive", type, seq);
892 	/*
893 	 * reset timeout, since we got a sane answer from the client.
894 	 * even if this was generated by something other than
895 	 * the bogus CHANNEL_REQUEST we send for keepalives.
896 	 */
897 	packet_set_alive_timeouts(0);
898 	return 0;
899 }
900 
901 static int
902 server_input_stdin_data(int type, u_int32_t seq, void *ctxt)
903 {
904 	char *data;
905 	u_int data_len;
906 
907 	/* Stdin data from the client.  Append it to the buffer. */
908 	/* Ignore any data if the client has closed stdin. */
909 	if (fdin == -1)
910 		return 0;
911 	data = packet_get_string(&data_len);
912 	packet_check_eom();
913 	buffer_append(&stdin_buffer, data, data_len);
914 	explicit_bzero(data, data_len);
915 	free(data);
916 	return 0;
917 }
918 
919 static int
920 server_input_eof(int type, u_int32_t seq, void *ctxt)
921 {
922 	/*
923 	 * Eof from the client.  The stdin descriptor to the
924 	 * program will be closed when all buffered data has
925 	 * drained.
926 	 */
927 	debug("EOF received for stdin.");
928 	packet_check_eom();
929 	stdin_eof = 1;
930 	return 0;
931 }
932 
933 static int
934 server_input_window_size(int type, u_int32_t seq, void *ctxt)
935 {
936 	u_int row = packet_get_int();
937 	u_int col = packet_get_int();
938 	u_int xpixel = packet_get_int();
939 	u_int ypixel = packet_get_int();
940 
941 	debug("Window change received.");
942 	packet_check_eom();
943 	if (fdin != -1)
944 		pty_change_window_size(fdin, row, col, xpixel, ypixel);
945 	return 0;
946 }
947 
948 static Channel *
949 server_request_direct_tcpip(void)
950 {
951 	Channel *c = NULL;
952 	char *target, *originator;
953 	u_short target_port, originator_port;
954 
955 	target = packet_get_string(NULL);
956 	target_port = packet_get_int();
957 	originator = packet_get_string(NULL);
958 	originator_port = packet_get_int();
959 	packet_check_eom();
960 
961 	debug("server_request_direct_tcpip: originator %s port %d, target %s "
962 	    "port %d", originator, originator_port, target, target_port);
963 
964 	/* XXX fine grained permissions */
965 	if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
966 	    !no_port_forwarding_flag) {
967 		c = channel_connect_to_port(target, target_port,
968 		    "direct-tcpip", "direct-tcpip");
969 	} else {
970 		logit("refused local port forward: "
971 		    "originator %s port %d, target %s port %d",
972 		    originator, originator_port, target, target_port);
973 	}
974 
975 	free(originator);
976 	free(target);
977 
978 	return c;
979 }
980 
981 static Channel *
982 server_request_direct_streamlocal(void)
983 {
984 	Channel *c = NULL;
985 	char *target, *originator;
986 	u_short originator_port;
987 
988 	target = packet_get_string(NULL);
989 	originator = packet_get_string(NULL);
990 	originator_port = packet_get_int();
991 	packet_check_eom();
992 
993 	debug("server_request_direct_streamlocal: originator %s port %d, target %s",
994 	    originator, originator_port, target);
995 
996 	/* XXX fine grained permissions */
997 	if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
998 	    !no_port_forwarding_flag) {
999 		c = channel_connect_to_path(target,
1000 		    "direct-streamlocal@openssh.com", "direct-streamlocal");
1001 	} else {
1002 		logit("refused streamlocal port forward: "
1003 		    "originator %s port %d, target %s",
1004 		    originator, originator_port, target);
1005 	}
1006 
1007 	free(originator);
1008 	free(target);
1009 
1010 	return c;
1011 }
1012 
1013 static Channel *
1014 server_request_tun(void)
1015 {
1016 	Channel *c = NULL;
1017 	int mode, tun;
1018 	int sock;
1019 
1020 	mode = packet_get_int();
1021 	switch (mode) {
1022 	case SSH_TUNMODE_POINTOPOINT:
1023 	case SSH_TUNMODE_ETHERNET:
1024 		break;
1025 	default:
1026 		packet_send_debug("Unsupported tunnel device mode.");
1027 		return NULL;
1028 	}
1029 	if ((options.permit_tun & mode) == 0) {
1030 		packet_send_debug("Server has rejected tunnel device "
1031 		    "forwarding");
1032 		return NULL;
1033 	}
1034 
1035 	tun = packet_get_int();
1036 	if (forced_tun_device != -1) {
1037 		if (tun != SSH_TUNID_ANY && forced_tun_device != tun)
1038 			goto done;
1039 		tun = forced_tun_device;
1040 	}
1041 	sock = tun_open(tun, mode);
1042 	if (sock < 0)
1043 		goto done;
1044 	c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
1045 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
1046 	c->datagram = 1;
1047 #if defined(SSH_TUN_FILTER)
1048 	if (mode == SSH_TUNMODE_POINTOPOINT)
1049 		channel_register_filter(c->self, sys_tun_infilter,
1050 		    sys_tun_outfilter, NULL, NULL);
1051 #endif
1052 
1053  done:
1054 	if (c == NULL)
1055 		packet_send_debug("Failed to open the tunnel device.");
1056 	return c;
1057 }
1058 
1059 static Channel *
1060 server_request_session(void)
1061 {
1062 	Channel *c;
1063 
1064 	debug("input_session_request");
1065 	packet_check_eom();
1066 
1067 	if (no_more_sessions) {
1068 		packet_disconnect("Possible attack: attempt to open a session "
1069 		    "after additional sessions disabled");
1070 	}
1071 
1072 	/*
1073 	 * A server session has no fd to read or write until a
1074 	 * CHANNEL_REQUEST for a shell is made, so we set the type to
1075 	 * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
1076 	 * CHANNEL_REQUEST messages is registered.
1077 	 */
1078 	c = channel_new("session", SSH_CHANNEL_LARVAL,
1079 	    -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
1080 	    0, "server-session", 1);
1081 	if (session_open(the_authctxt, c->self) != 1) {
1082 		debug("session open failed, free channel %d", c->self);
1083 		channel_free(c);
1084 		return NULL;
1085 	}
1086 	channel_register_cleanup(c->self, session_close_by_channel, 0);
1087 	return c;
1088 }
1089 
1090 static int
1091 server_input_channel_open(int type, u_int32_t seq, void *ctxt)
1092 {
1093 	Channel *c = NULL;
1094 	char *ctype;
1095 	int rchan;
1096 	u_int rmaxpack, rwindow, len;
1097 
1098 	ctype = packet_get_string(&len);
1099 	rchan = packet_get_int();
1100 	rwindow = packet_get_int();
1101 	rmaxpack = packet_get_int();
1102 
1103 	debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
1104 	    ctype, rchan, rwindow, rmaxpack);
1105 
1106 	if (strcmp(ctype, "session") == 0) {
1107 		c = server_request_session();
1108 	} else if (strcmp(ctype, "direct-tcpip") == 0) {
1109 		c = server_request_direct_tcpip();
1110 	} else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
1111 		c = server_request_direct_streamlocal();
1112 	} else if (strcmp(ctype, "tun@openssh.com") == 0) {
1113 		c = server_request_tun();
1114 	}
1115 	if (c != NULL) {
1116 		debug("server_input_channel_open: confirm %s", ctype);
1117 		c->remote_id = rchan;
1118 		c->remote_window = rwindow;
1119 		c->remote_maxpacket = rmaxpack;
1120 		if (c->type != SSH_CHANNEL_CONNECTING) {
1121 			packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1122 			packet_put_int(c->remote_id);
1123 			packet_put_int(c->self);
1124 			packet_put_int(c->local_window);
1125 			packet_put_int(c->local_maxpacket);
1126 			packet_send();
1127 		}
1128 	} else {
1129 		debug("server_input_channel_open: failure %s", ctype);
1130 		packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1131 		packet_put_int(rchan);
1132 		packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
1133 		if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1134 			packet_put_cstring("open failed");
1135 			packet_put_cstring("");
1136 		}
1137 		packet_send();
1138 	}
1139 	free(ctype);
1140 	return 0;
1141 }
1142 
1143 static int
1144 server_input_hostkeys_prove(struct sshbuf **respp)
1145 {
1146 	struct ssh *ssh = active_state; /* XXX */
1147 	struct sshbuf *resp = NULL;
1148 	struct sshbuf *sigbuf = NULL;
1149 	struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
1150 	int r, ndx, success = 0;
1151 	const u_char *blob;
1152 	u_char *sig = 0;
1153 	size_t blen, slen;
1154 
1155 	if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
1156 		fatal("%s: sshbuf_new", __func__);
1157 
1158 	while (ssh_packet_remaining(ssh) > 0) {
1159 		sshkey_free(key);
1160 		key = NULL;
1161 		if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
1162 		    (r = sshkey_from_blob(blob, blen, &key)) != 0) {
1163 			error("%s: couldn't parse key: %s",
1164 			    __func__, ssh_err(r));
1165 			goto out;
1166 		}
1167 		/*
1168 		 * Better check that this is actually one of our hostkeys
1169 		 * before attempting to sign anything with it.
1170 		 */
1171 		if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
1172 			error("%s: unknown host %s key",
1173 			    __func__, sshkey_type(key));
1174 			goto out;
1175 		}
1176 		/*
1177 		 * XXX refactor: make kex->sign just use an index rather
1178 		 * than passing in public and private keys
1179 		 */
1180 		if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
1181 		    (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
1182 			error("%s: can't retrieve hostkey %d", __func__, ndx);
1183 			goto out;
1184 		}
1185 		sshbuf_reset(sigbuf);
1186 		free(sig);
1187 		sig = NULL;
1188 		if ((r = sshbuf_put_cstring(sigbuf,
1189 		    "hostkeys-prove-00@openssh.com")) != 0 ||
1190 		    (r = sshbuf_put_string(sigbuf,
1191 		    ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
1192 		    (r = sshkey_puts(key, sigbuf)) != 0 ||
1193 		    (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen,
1194 		    sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), NULL, 0)) != 0 ||
1195 		    (r = sshbuf_put_string(resp, sig, slen)) != 0) {
1196 			error("%s: couldn't prepare signature: %s",
1197 			    __func__, ssh_err(r));
1198 			goto out;
1199 		}
1200 	}
1201 	/* Success */
1202 	*respp = resp;
1203 	resp = NULL; /* don't free it */
1204 	success = 1;
1205  out:
1206 	free(sig);
1207 	sshbuf_free(resp);
1208 	sshbuf_free(sigbuf);
1209 	sshkey_free(key);
1210 	return success;
1211 }
1212 
1213 static int
1214 server_input_global_request(int type, u_int32_t seq, void *ctxt)
1215 {
1216 	char *rtype;
1217 	int want_reply;
1218 	int r, success = 0, allocated_listen_port = 0;
1219 	struct sshbuf *resp = NULL;
1220 
1221 	rtype = packet_get_string(NULL);
1222 	want_reply = packet_get_char();
1223 	debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
1224 
1225 	/* -R style forwarding */
1226 	if (strcmp(rtype, "tcpip-forward") == 0) {
1227 		struct passwd *pw;
1228 		struct Forward fwd;
1229 
1230 		pw = the_authctxt->pw;
1231 		if (pw == NULL || !the_authctxt->valid)
1232 			fatal("server_input_global_request: no/invalid user");
1233 		memset(&fwd, 0, sizeof(fwd));
1234 		fwd.listen_host = packet_get_string(NULL);
1235 		fwd.listen_port = (u_short)packet_get_int();
1236 		debug("server_input_global_request: tcpip-forward listen %s port %d",
1237 		    fwd.listen_host, fwd.listen_port);
1238 
1239 		/* check permissions */
1240 		if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
1241 		    no_port_forwarding_flag ||
1242 		    (!want_reply && fwd.listen_port == 0)
1243 #ifndef NO_IPPORT_RESERVED_CONCEPT
1244 		    || (fwd.listen_port != 0 && fwd.listen_port < IPPORT_RESERVED &&
1245 		    pw->pw_uid != 0)
1246 #endif
1247 		    ) {
1248 			success = 0;
1249 			packet_send_debug("Server has disabled port forwarding.");
1250 		} else {
1251 			/* Start listening on the port */
1252 			success = channel_setup_remote_fwd_listener(&fwd,
1253 			    &allocated_listen_port, &options.fwd_opts);
1254 		}
1255 		free(fwd.listen_host);
1256 		if ((resp = sshbuf_new()) == NULL)
1257 			fatal("%s: sshbuf_new", __func__);
1258 		if (allocated_listen_port != 0 &&
1259 		    (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
1260 			fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
1261 	} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
1262 		struct Forward fwd;
1263 
1264 		memset(&fwd, 0, sizeof(fwd));
1265 		fwd.listen_host = packet_get_string(NULL);
1266 		fwd.listen_port = (u_short)packet_get_int();
1267 		debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
1268 		    fwd.listen_host, fwd.listen_port);
1269 
1270 		success = channel_cancel_rport_listener(&fwd);
1271 		free(fwd.listen_host);
1272 	} else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
1273 		struct Forward fwd;
1274 
1275 		memset(&fwd, 0, sizeof(fwd));
1276 		fwd.listen_path = packet_get_string(NULL);
1277 		debug("server_input_global_request: streamlocal-forward listen path %s",
1278 		    fwd.listen_path);
1279 
1280 		/* check permissions */
1281 		if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
1282 		    || no_port_forwarding_flag) {
1283 			success = 0;
1284 			packet_send_debug("Server has disabled port forwarding.");
1285 		} else {
1286 			/* Start listening on the socket */
1287 			success = channel_setup_remote_fwd_listener(
1288 			    &fwd, NULL, &options.fwd_opts);
1289 		}
1290 		free(fwd.listen_path);
1291 	} else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
1292 		struct Forward fwd;
1293 
1294 		memset(&fwd, 0, sizeof(fwd));
1295 		fwd.listen_path = packet_get_string(NULL);
1296 		debug("%s: cancel-streamlocal-forward path %s", __func__,
1297 		    fwd.listen_path);
1298 
1299 		success = channel_cancel_rport_listener(&fwd);
1300 		free(fwd.listen_path);
1301 	} else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
1302 		no_more_sessions = 1;
1303 		success = 1;
1304 	} else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
1305 		success = server_input_hostkeys_prove(&resp);
1306 	}
1307 	if (want_reply) {
1308 		packet_start(success ?
1309 		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
1310 		if (success && resp != NULL)
1311 			ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
1312 			    sshbuf_len(resp));
1313 		packet_send();
1314 		packet_write_wait();
1315 	}
1316 	free(rtype);
1317 	sshbuf_free(resp);
1318 	return 0;
1319 }
1320 
1321 static int
1322 server_input_channel_req(int type, u_int32_t seq, void *ctxt)
1323 {
1324 	Channel *c;
1325 	int id, reply, success = 0;
1326 	char *rtype;
1327 
1328 	id = packet_get_int();
1329 	rtype = packet_get_string(NULL);
1330 	reply = packet_get_char();
1331 
1332 	debug("server_input_channel_req: channel %d request %s reply %d",
1333 	    id, rtype, reply);
1334 
1335 	if ((c = channel_lookup(id)) == NULL)
1336 		packet_disconnect("server_input_channel_req: "
1337 		    "unknown channel %d", id);
1338 	if (!strcmp(rtype, "eow@openssh.com")) {
1339 		packet_check_eom();
1340 		chan_rcvd_eow(c);
1341 	} else if ((c->type == SSH_CHANNEL_LARVAL ||
1342 	    c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
1343 		success = session_input_channel_req(c, rtype);
1344 	if (reply && !(c->flags & CHAN_CLOSE_SENT)) {
1345 		packet_start(success ?
1346 		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1347 		packet_put_int(c->remote_id);
1348 		packet_send();
1349 	}
1350 	free(rtype);
1351 	return 0;
1352 }
1353 
1354 static void
1355 server_init_dispatch_20(void)
1356 {
1357 	debug("server_init_dispatch_20");
1358 	dispatch_init(&dispatch_protocol_error);
1359 	dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
1360 	dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
1361 	dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
1362 	dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
1363 	dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
1364 	dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1365 	dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1366 	dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
1367 	dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
1368 	dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
1369 	/* client_alive */
1370 	dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
1371 	dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
1372 	dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
1373 	dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
1374 	/* rekeying */
1375 	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1376 }
1377 static void
1378 server_init_dispatch_13(void)
1379 {
1380 	debug("server_init_dispatch_13");
1381 	dispatch_init(NULL);
1382 	dispatch_set(SSH_CMSG_EOF, &server_input_eof);
1383 	dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
1384 	dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
1385 	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
1386 	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
1387 	dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
1388 	dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1389 	dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1390 	dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
1391 }
1392 static void
1393 server_init_dispatch_15(void)
1394 {
1395 	server_init_dispatch_13();
1396 	debug("server_init_dispatch_15");
1397 	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
1398 	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
1399 }
1400 static void
1401 server_init_dispatch(void)
1402 {
1403 	if (compat20)
1404 		server_init_dispatch_20();
1405 	else if (compat13)
1406 		server_init_dispatch_13();
1407 	else
1408 		server_init_dispatch_15();
1409 }
1410