summaryrefslogtreecommitdiff
path: root/serverloop.c
blob: 1ffa4dbfb99ac60b0e1b06249df3eaab41a9139a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Server main loop for handling the interactive session.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 *
 * SSH2 support by Markus Friedl.
 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"
RCSID("$OpenBSD: serverloop.c,v 1.70 2001/06/23 15:12:19 itojun Exp $");

#include "xmalloc.h"
#include "packet.h"
#include "buffer.h"
#include "log.h"
#include "servconf.h"
#include "sshpty.h"
#include "channels.h"
#include "compat.h"
#include "ssh1.h"
#include "ssh2.h"
#include "auth.h"
#include "session.h"
#include "dispatch.h"
#include "auth-options.h"
#include "serverloop.h"
#include "misc.h"
#include "kex.h"

extern ServerOptions options;

/* XXX */
extern Kex *xxx_kex;

static Buffer stdin_buffer;	/* Buffer for stdin data. */
static Buffer stdout_buffer;	/* Buffer for stdout data. */
static Buffer stderr_buffer;	/* Buffer for stderr data. */
static int fdin;		/* Descriptor for stdin (for writing) */
static int fdout;		/* Descriptor for stdout (for reading);
				   May be same number as fdin. */
static int fderr;		/* Descriptor for stderr.  May be -1. */
static long stdin_bytes = 0;	/* Number of bytes written to stdin. */
static long stdout_bytes = 0;	/* Number of stdout bytes sent to client. */
static long stderr_bytes = 0;	/* Number of stderr bytes sent to client. */
static long fdout_bytes = 0;	/* Number of stdout bytes read from program. */
static int stdin_eof = 0;	/* EOF message received from client. */
static int fdout_eof = 0;	/* EOF encountered reading from fdout. */
static int fderr_eof = 0;	/* EOF encountered readung from fderr. */
static int fdin_is_tty = 0;	/* fdin points to a tty. */
static int connection_in;	/* Connection to client (input). */
static int connection_out;	/* Connection to client (output). */
static int connection_closed = 0;	/* Connection to client closed. */
static u_int buffer_high;	/* "Soft" max buffer size. */

/*
 * This SIGCHLD kludge is used to detect when the child exits.  The server
 * will exit after that, as soon as forwarded connections have terminated.
 */

static volatile int child_terminated;	/* The child has terminated. */

/* prototypes */
static void server_init_dispatch(void);

int client_alive_timeouts = 0;

static void
sigchld_handler(int sig)
{
	int save_errno = errno;
	debug("Received SIGCHLD.");
	child_terminated = 1;
	mysignal(SIGCHLD, sigchld_handler);
	errno = save_errno;
}

/*
 * Make packets from buffered stderr data, and buffer it for sending
 * to the client.
 */
static void
make_packets_from_stderr_data(void)
{
	int len;

	/* Send buffered stderr data to the client. */
	while (buffer_len(&stderr_buffer) > 0 &&
	    packet_not_very_much_data_to_write()) {
		len = buffer_len(&stderr_buffer);
		if (packet_is_interactive()) {
			if (len > 512)
				len = 512;
		} else {
			/* Keep the packets at reasonable size. */
			if (len > packet_get_maxsize())
				len = packet_get_maxsize();
		}
		packet_start(SSH_SMSG_STDERR_DATA);
		packet_put_string(buffer_ptr(&stderr_buffer), len);
		packet_send();
		buffer_consume(&stderr_buffer, len);
		stderr_bytes += len;
	}
}

/*
 * Make packets from buffered stdout data, and buffer it for sending to the
 * client.
 */
static void
make_packets_from_stdout_data(void)
{
	int len;

	/* Send buffered stdout data to the client. */
	while (buffer_len(&stdout_buffer) > 0 &&
	    packet_not_very_much_data_to_write()) {
		len = buffer_len(&stdout_buffer);
		if (packet_is_interactive()) {
			if (len > 512)
				len = 512;
		} else {
			/* Keep the packets at reasonable size. */
			if (len > packet_get_maxsize())
				len = packet_get_maxsize();
		}
		packet_start(SSH_SMSG_STDOUT_DATA);
		packet_put_string(buffer_ptr(&stdout_buffer), len);
		packet_send();
		buffer_consume(&stdout_buffer, len);
		stdout_bytes += len;
	}
}

/*
 * Sleep in select() until we can do something.  This will initialize the
 * select masks.  Upon return, the masks will indicate which descriptors
 * have data or can accept data.  Optionally, a maximum time can be specified
 * for the duration of the wait (0 = infinite).
 */
static void
wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
    u_int max_time_milliseconds)
{
	struct timeval tv, *tvp;
	int ret;
	int client_alive_scheduled = 0;

	/*
	 * if using client_alive, set the max timeout accordingly, 
	 * and indicate that this particular timeout was for client
	 * alive by setting the client_alive_scheduled flag.
	 *
	 * this could be randomized somewhat to make traffic
	 * analysis more difficult, but we're not doing it yet.  
	 */
	if (max_time_milliseconds == 0 && options.client_alive_interval) {
		client_alive_scheduled = 1;
		max_time_milliseconds = options.client_alive_interval * 1000;
	} else 
		client_alive_scheduled = 0;

	/* When select fails we restart from here. */
retry_select:

	/* Allocate and update select() masks for channel descriptors. */
	channel_prepare_select(readsetp, writesetp, maxfdp, 0);

	if (compat20) {
		/* wrong: bad condition XXX */
		if (channel_not_very_much_buffered_data())
			FD_SET(connection_in, *readsetp);
	} else {
		/*
		 * Read packets from the client unless we have too much
		 * buffered stdin or channel data.
		 */
		if (buffer_len(&stdin_buffer) < buffer_high &&
		    channel_not_very_much_buffered_data())
			FD_SET(connection_in, *readsetp);
		/*
		 * If there is not too much data already buffered going to
		 * the client, try to get some more data from the program.
		 */
		if (packet_not_very_much_data_to_write()) {
			if (!fdout_eof)
				FD_SET(fdout, *readsetp);
			if (!fderr_eof)
				FD_SET(fderr, *readsetp);
		}
		/*
		 * If we have buffered data, try to write some of that data
		 * to the program.
		 */
		if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
			FD_SET(fdin, *writesetp);
	}

	/*
	 * If we have buffered packet data going to the client, mark that
	 * descriptor.
	 */
	if (packet_have_data_to_write())
		FD_SET(connection_out, *writesetp);

	/*
	 * If child has terminated and there is enough buffer space to read
	 * from it, then read as much as is available and exit.
	 */
	if (child_terminated && packet_not_very_much_data_to_write())
		if (max_time_milliseconds == 0 || client_alive_scheduled)
			max_time_milliseconds = 100;

	if (max_time_milliseconds == 0)
		tvp = NULL;
	else {
		tv.tv_sec = max_time_milliseconds / 1000;
		tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
		tvp = &tv;
	}
	if (tvp!=NULL)
		debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds);

	/* Wait for something to happen, or the timeout to expire. */
	ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);

	if (ret == -1) {
		if (errno != EINTR)
			error("select: %.100s", strerror(errno));
		else
			goto retry_select;
	}
	if (ret == 0 && client_alive_scheduled) {
		/* timeout, check to see how many we have had */
		client_alive_timeouts++;

		if (client_alive_timeouts > options.client_alive_count_max ) {
			packet_disconnect(
				"Timeout, your session not responding.");
		} else {
			/*
			 * send a bogus channel request with "wantreply" 
			 * we should get back a failure
			 */
			int id;
			
			id = channel_find_open();
			if (id != -1) {
				channel_request_start(id,
				  "keepalive@openssh.com", 1);
				packet_send();
			} else 
				packet_disconnect(
					"No open channels after timeout!");
		}
	} 
}

/*
 * Processes input from the client and the program.  Input data is stored
 * in buffers and processed later.
 */
static void
process_input(fd_set * readset)
{
	int len;
	char buf[16384];

	/* Read and buffer any input data from the client. */
	if (FD_ISSET(connection_in, readset)) {
		len = read(connection_in, buf, sizeof(buf));
		if (len == 0) {
			verbose("Connection closed by remote host.");
			connection_closed = 1;
			if (compat20)
				return;
			fatal_cleanup();
		} else if (len < 0) {
			if (errno != EINTR && errno != EAGAIN) {
				verbose("Read error from remote host: %.100s", strerror(errno));
				fatal_cleanup();
			}
		} else {
			/* Buffer any received data. */
			packet_process_incoming(buf, len);
		}
	}
	if (compat20)
		return;

	/* Read and buffer any available stdout data from the program. */
	if (!fdout_eof && FD_ISSET(fdout, readset)) {
		len = read(fdout, buf, sizeof(buf));
		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
			/* do nothing */
		} else if (len <= 0) {
			fdout_eof = 1;
		} else {
			buffer_append(&stdout_buffer, buf, len);
			fdout_bytes += len;
		}
	}
	/* Read and buffer any available stderr data from the program. */
	if (!fderr_eof && FD_ISSET(fderr, readset)) {
		len = read(fderr, buf, sizeof(buf));
		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
			/* do nothing */
		} else if (len <= 0) {
			fderr_eof = 1;
		} else {
			buffer_append(&stderr_buffer, buf, len);
		}
	}
}

/*
 * Sends data from internal buffers to client program stdin.
 */
static void
process_output(fd_set * writeset)
{
	struct termios tio;
	int len;

	/* Write buffered data to program stdin. */
	if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
		len = write(fdin, buffer_ptr(&stdin_buffer),
		    buffer_len(&stdin_buffer));
		if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
			/* do nothing */
		} else if (len <= 0) {
#ifdef USE_PIPES
			close(fdin);
#else
			if (fdin != fdout)
				close(fdin);
			else
				shutdown(fdin, SHUT_WR); /* We will no longer send. */
#endif
			fdin = -1;
		} else {
			/* Successful write. */
			if (fdin_is_tty && tcgetattr(fdin, &tio) == 0 &&
			    !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
				/*
				 * Simulate echo to reduce the impact of
				 * traffic analysis
				 */
				packet_send_ignore(len);
				packet_send();
			}
			/* Consume the data from the buffer. */
			buffer_consume(&stdin_buffer, len);
			/* Update the count of bytes written to the program. */
			stdin_bytes += len;
		}
	}
	/* Send any buffered packet data to the client. */
	if (FD_ISSET(connection_out, writeset))
		packet_write_poll();
}

/*
 * Wait until all buffered output has been sent to the client.
 * This is used when the program terminates.
 */
static void
drain_output(void)
{
	/* Send any buffered stdout data to the client. */
	if (buffer_len(&stdout_buffer) > 0) {
		packet_start(SSH_SMSG_STDOUT_DATA);
		packet_put_string(buffer_ptr(&stdout_buffer),
				  buffer_len(&stdout_buffer));
		packet_send();
		/* Update the count of sent bytes. */
		stdout_bytes += buffer_len(&stdout_buffer);
	}
	/* Send any buffered stderr data to the client. */
	if (buffer_len(&stderr_buffer) > 0) {
		packet_start(SSH_SMSG_STDERR_DATA);
		packet_put_string(buffer_ptr(&stderr_buffer),
				  buffer_len(&stderr_buffer));
		packet_send();
		/* Update the count of sent bytes. */
		stderr_bytes += buffer_len(&stderr_buffer);
	}
	/* Wait until all buffered data has been written to the client. */
	packet_write_wait();
}

static void
process_buffered_input_packets(void)
{
	dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL);
}

/*
 * Performs the interactive session.  This handles data transmission between
 * the client and the program.  Note that the notion of stdin, stdout, and
 * stderr in this function is sort of reversed: this function writes to
 * stdin (of the child program), and reads from stdout and stderr (of the
 * child program).
 */
void
server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
{
	fd_set *readset = NULL, *writeset = NULL;
	int max_fd;
	int wait_status;	/* Status returned by wait(). */
	pid_t wait_pid;		/* pid returned by wait(). */
	int waiting_termination = 0;	/* Have displayed waiting close message. */
	u_int max_time_milliseconds;
	u_int previous_stdout_buffer_bytes;
	u_int stdout_buffer_bytes;
	int type;

	debug("Entering interactive session.");

	/* Initialize the SIGCHLD kludge. */
	child_terminated = 0;
	signal(SIGCHLD, sigchld_handler);

	/* Initialize our global variables. */
	fdin = fdin_arg;
	fdout = fdout_arg;
	fderr = fderr_arg;

	/* nonblocking IO */
	set_nonblock(fdin);
	set_nonblock(fdout);
	/* we don't have stderr for interactive terminal sessions, see below */
	if (fderr != -1)
		set_nonblock(fderr);

	if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
		fdin_is_tty = 1;

	connection_in = packet_get_connection_in();
	connection_out = packet_get_connection_out();

	previous_stdout_buffer_bytes = 0;

	/* Set approximate I/O buffer size. */
	if (packet_is_interactive())
		buffer_high = 4096;
	else
		buffer_high = 64 * 1024;

	/* Initialize max_fd to the maximum of the known file descriptors. */
	max_fd = MAX(fdin, fdout);
	if (fderr != -1)
		max_fd = MAX(max_fd, fderr);
	max_fd = MAX(max_fd, connection_in);
	max_fd = MAX(max_fd, connection_out);

	/* Initialize Initialize buffers. */
	buffer_init(&stdin_buffer);
	buffer_init(&stdout_buffer);
	buffer_init(&stderr_buffer);

	/*
	 * If we have no separate fderr (which is the case when we have a pty
	 * - there we cannot make difference between data sent to stdout and
	 * stderr), indicate that we have seen an EOF from stderr.  This way
	 * we don\'t need to check the descriptor everywhere.
	 */
	if (fderr == -1)
		fderr_eof = 1;

	server_init_dispatch();

	/* Main loop of the server for the interactive session mode. */
	for (;;) {

		/* Process buffered packets from the client. */
		process_buffered_input_packets();

		/*
		 * If we have received eof, and there is no more pending
		 * input data, cause a real eof by closing fdin.
		 */
		if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
#ifdef USE_PIPES
			close(fdin);
#else
			if (fdin != fdout)
				close(fdin);
			else
				shutdown(fdin, SHUT_WR); /* We will no longer send. */
#endif
			fdin = -1;
		}
		/* Make packets from buffered stderr data to send to the client. */
		make_packets_from_stderr_data();

		/*
		 * Make packets from buffered stdout data to send to the
		 * client. If there is very little to send, this arranges to
		 * not send them now, but to wait a short while to see if we
		 * are getting more data. This is necessary, as some systems
		 * wake up readers from a pty after each separate character.
		 */
		max_time_milliseconds = 0;
		stdout_buffer_bytes = buffer_len(&stdout_buffer);
		if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
		    stdout_buffer_bytes != previous_stdout_buffer_bytes) {
			/* try again after a while */
			max_time_milliseconds = 10;
		} else {
			/* Send it now. */
			make_packets_from_stdout_data();
		}
		previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);

		/* Send channel data to the client. */
		if (packet_not_very_much_data_to_write())
			channel_output_poll();

		/*
		 * Bail out of the loop if the program has closed its output
		 * descriptors, and we have no more data to send to the
		 * client, and there is no pending buffered data.
		 */
		if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
		    buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
			if (!channel_still_open())
				break;
			if (!waiting_termination) {
				const char *s = "Waiting for forwarded connections to terminate...\r\n";
				char *cp;
				waiting_termination = 1;
				buffer_append(&stderr_buffer, s, strlen(s));

				/* Display list of open channels. */
				cp = channel_open_message();
				buffer_append(&stderr_buffer, cp, strlen(cp));
				xfree(cp);
			}
		}
		/* Sleep in select() until we can do something. */
		wait_until_can_do_something(&readset, &writeset, &max_fd,
		    max_time_milliseconds);

		/* Process any channel events. */
		channel_after_select(readset, writeset);

		/* Process input from the client and from program stdout/stderr. */
		process_input(readset);

		/* Process output to the client and to program stdin. */
		process_output(writeset);
	}
	if (readset)
		xfree(readset);
	if (writeset)
		xfree(writeset);

	/* Cleanup and termination code. */

	/* Wait until all output has been sent to the client. */
	drain_output();

	debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
	      stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);

	/* Free and clear the buffers. */
	buffer_free(&stdin_buffer);
	buffer_free(&stdout_buffer);
	buffer_free(&stderr_buffer);

	/* Close the file descriptors. */
	if (fdout != -1)
		close(fdout);
	fdout = -1;
	fdout_eof = 1;
	if (fderr != -1)
		close(fderr);
	fderr = -1;
	fderr_eof = 1;
	if (fdin != -1)
		close(fdin);
	fdin = -1;

	channel_free_all();

	/* We no longer want our SIGCHLD handler to be called. */
	signal(SIGCHLD, SIG_DFL);

	wait_pid = waitpid(-1, &wait_status, child_terminated ? WNOHANG : 0);
	if (wait_pid == -1)
		packet_disconnect("wait: %.100s", strerror(errno));
	else if (wait_pid != pid)
		error("Strange, wait returned pid %d, expected %d",
		    wait_pid, pid);

	/* Check if it exited normally. */
	if (WIFEXITED(wait_status)) {
		/* Yes, normal exit.  Get exit status and send it to the client. */
		debug("Command exited with status %d.", WEXITSTATUS(wait_status));
		packet_start(SSH_SMSG_EXITSTATUS);
		packet_put_int(WEXITSTATUS(wait_status));
		packet_send();
		packet_write_wait();

		/*
		 * Wait for exit confirmation.  Note that there might be
		 * other packets coming before it; however, the program has
		 * already died so we just ignore them.  The client is
		 * supposed to respond with the confirmation when it receives
		 * the exit status.
		 */
		do {
			int plen;
			type = packet_read(&plen);
		}
		while (type != SSH_CMSG_EXIT_CONFIRMATION);

		debug("Received exit confirmation.");
		return;
	}
	/* Check if the program terminated due to a signal. */
	if (WIFSIGNALED(wait_status))
		packet_disconnect("Command terminated on signal %d.",
				  WTERMSIG(wait_status));

	/* Some weird exit cause.  Just exit. */
	packet_disconnect("wait returned status %04x.", wait_status);
	/* NOTREACHED */
}

void
server_loop2(void)
{
	fd_set *readset = NULL, *writeset = NULL;
	int rekeying = 0, max_fd, status;
	pid_t pid;

	debug("Entering interactive session for SSH2.");

	mysignal(SIGCHLD, sigchld_handler);
	child_terminated = 0;
	connection_in = packet_get_connection_in();
	connection_out = packet_get_connection_out();

	max_fd = MAX(connection_in, connection_out);

	server_init_dispatch();

	for (;;) {
		process_buffered_input_packets();

		rekeying = (xxx_kex != NULL && !xxx_kex->done);

		if (!rekeying && packet_not_very_much_data_to_write())
			channel_output_poll();
		wait_until_can_do_something(&readset, &writeset, &max_fd,
		    rekeying);
		if (child_terminated) {
			while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
				session_close_by_pid(pid, status);
			child_terminated = 0;
		}
		if (!rekeying)
			channel_after_select(readset, writeset);
		process_input(readset);
		if (connection_closed)
			break;
		process_output(writeset);
	}
	if (readset)
		xfree(readset);
	if (writeset)
		xfree(writeset);

	channel_free_all();

	signal(SIGCHLD, SIG_DFL);
	while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
		session_close_by_pid(pid, status);
}

static void
server_input_channel_failure(int type, int plen, void *ctxt)
{
	debug("Got CHANNEL_FAILURE for keepalive");
	/* 
	 * reset timeout, since we got a sane answer from the client.
	 * even if this was generated by something other than
	 * the bogus CHANNEL_REQUEST we send for keepalives.
	 */
	client_alive_timeouts = 0; 
}


static void
server_input_stdin_data(int type, int plen, void *ctxt)
{
	char *data;
	u_int data_len;

	/* Stdin data from the client.  Append it to the buffer. */
	/* Ignore any data if the client has closed stdin. */
	if (fdin == -1)
		return;
	data = packet_get_string(&data_len);
	packet_integrity_check(plen, (4 + data_len), type);
	buffer_append(&stdin_buffer, data, data_len);
	memset(data, 0, data_len);
	xfree(data);
}

static void
server_input_eof(int type, int plen, void *ctxt)
{
	/*
	 * Eof from the client.  The stdin descriptor to the
	 * program will be closed when all buffered data has
	 * drained.
	 */
	debug("EOF received for stdin.");
	packet_integrity_check(plen, 0, type);
	stdin_eof = 1;
}

static void
server_input_window_size(int type, int plen, void *ctxt)
{
	int row = packet_get_int();
	int col = packet_get_int();
	int xpixel = packet_get_int();
	int ypixel = packet_get_int();

	debug("Window change received.");
	packet_integrity_check(plen, 4 * 4, type);
	if (fdin != -1)
		pty_change_window_size(fdin, row, col, xpixel, ypixel);
}

static Channel *
server_request_direct_tcpip(char *ctype)
{
	Channel *c;
	int sock;
	char *target, *originator;
	int target_port, originator_port;

	target = packet_get_string(NULL);
	target_port = packet_get_int();
	originator = packet_get_string(NULL);
	originator_port = packet_get_int();
	packet_done();

	debug("server_request_direct_tcpip: originator %s port %d, target %s port %d",
	   originator, originator_port, target, target_port);

	/* XXX check permission */
	sock = channel_connect_to(target, target_port);
	xfree(target);
	xfree(originator);
	if (sock < 0)
		return NULL;
	c = channel_new(ctype, SSH_CHANNEL_CONNECTING,
	    sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT,
	    CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1);
	if (c == NULL) {
		error("server_request_direct_tcpip: channel_new failed");
		close(sock);
	}
	return c;
}

static Channel *
server_request_session(char *ctype)
{
	Channel *c;

	debug("input_session_request");
	packet_done();
	/*
	 * A server session has no fd to read or write until a
	 * CHANNEL_REQUEST for a shell is made, so we set the type to
	 * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
	 * CHANNEL_REQUEST messages is registered.
	 */
	c = channel_new(ctype, SSH_CHANNEL_LARVAL,
	    -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
	    0, xstrdup("server-session"), 1);
	if (c == NULL) {
		error("server_request_session: channel_new failed");
		return NULL;
	}
	if (session_open(c->self) != 1) {
		debug("session open failed, free channel %d", c->self);
		channel_free(c);
		return NULL;
	}
	channel_register_callback(c->self, SSH2_MSG_CHANNEL_REQUEST,
	    session_input_channel_req, (void *)0);
	channel_register_cleanup(c->self, session_close_by_channel);
	return c;
}

static void
server_input_channel_open(int type, int plen, void *ctxt)
{
	Channel *c = NULL;
	char *ctype;
	u_int len;
	int rchan;
	int rmaxpack;
	int rwindow;

	ctype = packet_get_string(&len);
	rchan = packet_get_int();
	rwindow = packet_get_int();
	rmaxpack = packet_get_int();

	debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
	    ctype, rchan, rwindow, rmaxpack);

	if (strcmp(ctype, "session") == 0) {
		c = server_request_session(ctype);
	} else if (strcmp(ctype, "direct-tcpip") == 0) {
		c = server_request_direct_tcpip(ctype);
	}
	if (c != NULL) {
		debug("server_input_channel_open: confirm %s", ctype);
		c->remote_id = rchan;
		c->remote_window = rwindow;
		c->remote_maxpacket = rmaxpack;
		if (c->type != SSH_CHANNEL_CONNECTING) {
			packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
			packet_put_int(c->remote_id);
			packet_put_int(c->self);
			packet_put_int(c->local_window);
			packet_put_int(c->local_maxpacket);
			packet_send();
		}
	} else {
		debug("server_input_channel_open: failure %s", ctype);
		packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
		packet_put_int(rchan);
		packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
		if (!(datafellows & SSH_BUG_OPENFAILURE)) {
			packet_put_cstring("open failed");
			packet_put_cstring("");
		}
		packet_send();
	}
	xfree(ctype);
}

static void
server_input_global_request(int type, int plen, void *ctxt)
{
	char *rtype;
	int want_reply;
	int success = 0;

	rtype = packet_get_string(NULL);
	want_reply = packet_get_char();
	debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);

	/* -R style forwarding */
	if (strcmp(rtype, "tcpip-forward") == 0) {
		struct passwd *pw;
		char *listen_address;
		u_short listen_port;

		pw = auth_get_user();
		if (pw == NULL)
			fatal("server_input_global_request: no user");
		listen_address = packet_get_string(NULL); /* XXX currently ignored */
		listen_port = (u_short)packet_get_int();
		debug("server_input_global_request: tcpip-forward listen %s port %d",
		    listen_address, listen_port);

		/* check permissions */
		if (!options.allow_tcp_forwarding ||
		    no_port_forwarding_flag ||
		    (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) {
			success = 0;
			packet_send_debug("Server has disabled port forwarding.");
		} else {
			/* Start listening on the port */
			success = channel_request_forwarding(
			    listen_address, listen_port,
			    /*unspec host_to_connect*/ "<unspec host>",
			    /*unspec port_to_connect*/ 0,
			    options.gateway_ports, /*remote*/ 1);
		}
		xfree(listen_address);
	}
	if (want_reply) {
		packet_start(success ?
		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
		packet_send();
		packet_write_wait();
	}
	xfree(rtype);
}

static void
server_init_dispatch_20(void)
{
	debug("server_init_dispatch_20");
	dispatch_init(&dispatch_protocol_error);
	dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
	dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
	dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
	dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
	dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
	dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request);
	dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
	dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
	/* client_alive */
	dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure);
	/* rekeying */
	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
}
static void
server_init_dispatch_13(void)
{
	debug("server_init_dispatch_13");
	dispatch_init(NULL);
	dispatch_set(SSH_CMSG_EOF, &server_input_eof);
	dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
	dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
	dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
	dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
	dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
	dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
}
static void
server_init_dispatch_15(void)
{
	server_init_dispatch_13();
	debug("server_init_dispatch_15");
	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
}
static void
server_init_dispatch(void)
{
	if (compat20)
		server_init_dispatch_20();
	else if (compat13)
		server_init_dispatch_13();
	else
		server_init_dispatch_15();
}