aboutsummaryrefslogtreecommitdiff
path: root/openssl/demos/tunala/tunala.c
blob: ec49d3e943e3c2e276d624cdbd6b8ac97b41ce22 (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
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
#if defined(NO_BUFFER) || defined(NO_IP) || defined(NO_OPENSSL)
#error "Badness, NO_BUFFER, NO_IP or NO_OPENSSL is defined, turn them *off*"
#endif

/* Include our bits'n'pieces */
#include "tunala.h"


/********************************************/
/* Our local types that specify our "world" */
/********************************************/

/* These represent running "tunnels". Eg. if you wanted to do SSL in a
 * "message-passing" scanario, the "int" file-descriptors might be replaced by
 * thread or process IDs, and the "select" code might be replaced by message
 * handling code. Whatever. */
typedef struct _tunala_item_t {
	/* The underlying SSL state machine. This is a data-only processing unit
	 * and we communicate with it by talking to its four "buffers". */
	state_machine_t sm;
	/* The file-descriptors for the "dirty" (encrypted) side of the SSL
	 * setup. In actuality, this is typically a socket and both values are
	 * identical. */
	int dirty_read, dirty_send;
	/* The file-descriptors for the "clean" (unencrypted) side of the SSL
	 * setup. These could be stdin/stdout, a socket (both values the same),
	 * or whatever you like. */
	int clean_read, clean_send;
} tunala_item_t;

/* This structure is used as the data for running the main loop. Namely, in a
 * network format such as this, it is stuff for select() - but as pointed out,
 * when moving the real-world to somewhere else, this might be replaced by
 * something entirely different. It's basically the stuff that controls when
 * it's time to do some "work". */
typedef struct _select_sets_t {
	int max; /* As required as the first argument to select() */
	fd_set reads, sends, excepts; /* As passed to select() */
} select_sets_t;
typedef struct _tunala_selector_t {
	select_sets_t last_selected; /* Results of the last select() */
	select_sets_t next_select; /* What we'll next select on */
} tunala_selector_t;

/* This structure is *everything*. We do it to avoid the use of globals so that,
 * for example, it would be easier to shift things around between async-IO,
 * thread-based, or multi-fork()ed (or combinations thereof). */
typedef struct _tunala_world_t {
	/* The file-descriptor we "listen" on for new connections */
	int listen_fd;
	/* The array of tunnels */
	tunala_item_t *tunnels;
	/* the number of tunnels in use and allocated, respectively */
	unsigned int tunnels_used, tunnels_size;
	/* Our outside "loop" context stuff */
	tunala_selector_t selector;
	/* Our SSL_CTX, which is configured as the SSL client or server and has
	 * the various cert-settings and callbacks configured. */
	SSL_CTX *ssl_ctx;
	/* Simple flag with complex logic :-) Indicates whether we're an SSL
	 * server or an SSL client. */
	int server_mode;
} tunala_world_t;

/*****************************/
/* Internal static functions */
/*****************************/

static SSL_CTX *initialise_ssl_ctx(int server_mode, const char *engine_id,
		const char *CAfile, const char *cert, const char *key,
		const char *dcert, const char *dkey, const char *cipher_list,
		const char *dh_file, const char *dh_special, int tmp_rsa,
		int ctx_options, int out_state, int out_verify, int verify_mode,
		unsigned int verify_depth);
static void selector_init(tunala_selector_t *selector);
static void selector_add_listener(tunala_selector_t *selector, int fd);
static void selector_add_tunala(tunala_selector_t *selector, tunala_item_t *t);
static int selector_select(tunala_selector_t *selector);
/* This returns -1 for error, 0 for no new connections, or 1 for success, in
 * which case *newfd is populated. */
static int selector_get_listener(tunala_selector_t *selector, int fd, int *newfd);
static int tunala_world_new_item(tunala_world_t *world, int fd,
		const char *ip, unsigned short port, int flipped);
static void tunala_world_del_item(tunala_world_t *world, unsigned int idx);
static int tunala_item_io(tunala_selector_t *selector, tunala_item_t *item);

/*********************************************/
/* MAIN FUNCTION (and its utility functions) */
/*********************************************/

static const char *def_proxyhost = "127.0.0.1:443";
static const char *def_listenhost = "127.0.0.1:8080";
static int def_max_tunnels = 50;
static const char *def_cacert = NULL;
static const char *def_cert = NULL;
static const char *def_key = NULL;
static const char *def_dcert = NULL;
static const char *def_dkey = NULL;
static const char *def_engine_id = NULL;
static int def_server_mode = 0;
static int def_flipped = 0;
static const char *def_cipher_list = NULL;
static const char *def_dh_file = NULL;
static const char *def_dh_special = NULL;
static int def_tmp_rsa = 1;
static int def_ctx_options = 0;
static int def_verify_mode = 0;
static unsigned int def_verify_depth = 10;
static int def_out_state = 0;
static unsigned int def_out_verify = 0;
static int def_out_totals = 0;
static int def_out_conns = 0;

static const char *helpstring =
"\n'Tunala' (A tunneler with a New Zealand accent)\n"
"Usage: tunala [options], where options are from;\n"
" -listen [host:]<port>  (default = 127.0.0.1:8080)\n"
" -proxy <host>:<port>   (default = 127.0.0.1:443)\n"
" -maxtunnels <num>      (default = 50)\n"
" -cacert <path|NULL>    (default = NULL)\n"
" -cert <path|NULL>      (default = NULL)\n"
" -key <path|NULL>       (default = whatever '-cert' is)\n"
" -dcert <path|NULL>     (usually for DSA, default = NULL)\n"
" -dkey <path|NULL>      (usually for DSA, default = whatever '-dcert' is)\n"
" -engine <id|NULL>      (default = NULL)\n"
" -server <0|1>          (default = 0, ie. an SSL client)\n"
" -flipped <0|1>         (makes SSL servers be network clients, and vice versa)\n"
" -cipher <list>         (specifies cipher list to use)\n"
" -dh_file <path>        (a PEM file containing DH parameters to use)\n"
" -dh_special <NULL|generate|standard> (see below: def=NULL)\n"
" -no_tmp_rsa            (don't generate temporary RSA keys)\n"
" -no_ssl2               (disable SSLv2)\n"
" -no_ssl3               (disable SSLv3)\n"
" -no_tls1               (disable TLSv1)\n"
" -v_peer                (verify the peer certificate)\n"
" -v_strict              (do not continue if peer doesn't authenticate)\n"
" -v_once                (no verification in renegotiates)\n"
" -v_depth <num>         (limit certificate chain depth, default = 10)\n"
" -out_conns             (prints client connections and disconnections)\n"
" -out_state             (prints SSL handshake states)\n"
" -out_verify <0|1|2|3>  (prints certificate verification states: def=1)\n"
" -out_totals            (prints out byte-totals when a tunnel closes)\n"
" -<h|help|?>            (displays this help screen)\n"
"Notes:\n"
"(1) It is recommended to specify a cert+key when operating as an SSL server.\n"
"    If you only specify '-cert', the same file must contain a matching\n"
"    private key.\n"
"(2) Either dh_file or dh_special can be used to specify where DH parameters\n"
"    will be obtained from (or '-dh_special NULL' for the default choice) but\n"
"    you cannot specify both. For dh_special, 'generate' will create new DH\n"
"    parameters on startup, and 'standard' will use embedded parameters\n"
"    instead.\n"
"(3) Normally an ssl client connects to an ssl server - so that an 'ssl client\n"
"    tunala' listens for 'clean' client connections and proxies ssl, and an\n"
"    'ssl server tunala' listens for ssl connections and proxies 'clean'. With\n"
"    '-flipped 1', this behaviour is reversed so that an 'ssl server tunala'\n"
"    listens for clean client connections and proxies ssl (but participating\n"
"    as an ssl *server* in the SSL/TLS protocol), and an 'ssl client tunala'\n"
"    listens for ssl connections (participating as an ssl *client* in the\n"
"    SSL/TLS protocol) and proxies 'clean' to the end destination. This can\n"
"    be useful for allowing network access to 'servers' where only the server\n"
"    needs to authenticate the client (ie. the other way is not required).\n"
"    Even with client and server authentication, this 'technique' mitigates\n"
"    some DoS (denial-of-service) potential as it will be the network client\n"
"    having to perform the first private key operation rather than the other\n"
"    way round.\n"
"(4) The 'technique' used by setting '-flipped 1' is probably compatible with\n"
"    absolutely nothing except another complimentary instance of 'tunala'\n"
"    running with '-flipped 1'. :-)\n";

/* Default DH parameters for use with "-dh_special standard" ... stolen striaght
 * from s_server. */
static unsigned char dh512_p[]={
	0xDA,0x58,0x3C,0x16,0xD9,0x85,0x22,0x89,0xD0,0xE4,0xAF,0x75,
	0x6F,0x4C,0xCA,0x92,0xDD,0x4B,0xE5,0x33,0xB8,0x04,0xFB,0x0F,
	0xED,0x94,0xEF,0x9C,0x8A,0x44,0x03,0xED,0x57,0x46,0x50,0xD3,
	0x69,0x99,0xDB,0x29,0xD7,0x76,0x27,0x6B,0xA2,0xD3,0xD4,0x12,
	0xE2,0x18,0xF4,0xDD,0x1E,0x08,0x4C,0xF6,0xD8,0x00,0x3E,0x7C,
	0x47,0x74,0xE8,0x33,
	};
static unsigned char dh512_g[]={
	0x02,
	};

/* And the function that parses the above "standard" parameters, again, straight
 * out of s_server. */
static DH *get_dh512(void)
	{
	DH *dh=NULL;

	if ((dh=DH_new()) == NULL) return(NULL);
	dh->p=BN_bin2bn(dh512_p,sizeof(dh512_p),NULL);
	dh->g=BN_bin2bn(dh512_g,sizeof(dh512_g),NULL);
	if ((dh->p == NULL) || (dh->g == NULL))
		return(NULL);
	return(dh);
	}

/* Various help/error messages used by main() */
static int usage(const char *errstr, int isunknownarg)
{
	if(isunknownarg)
		fprintf(stderr, "Error: unknown argument '%s'\n", errstr);
	else
		fprintf(stderr, "Error: %s\n", errstr);
	fprintf(stderr, "%s\n", helpstring);
	return 1;
}

static int err_str0(const char *str0)
{
	fprintf(stderr, "%s\n", str0);
	return 1;
}

static int err_str1(const char *fmt, const char *str1)
{
	fprintf(stderr, fmt, str1);
	fprintf(stderr, "\n");
	return 1;
}

static int parse_max_tunnels(const char *s, unsigned int *maxtunnels)
{
	unsigned long l;
	if(!int_strtoul(s, &l) || (l < 1) || (l > 1024)) {
		fprintf(stderr, "Error, '%s' is an invalid value for "
				"maxtunnels\n", s);
		return 0;
	}
	*maxtunnels = (unsigned int)l;
	return 1;
}

static int parse_server_mode(const char *s, int *servermode)
{
	unsigned long l;
	if(!int_strtoul(s, &l) || (l > 1)) {
		fprintf(stderr, "Error, '%s' is an invalid value for the "
				"server mode\n", s);
		return 0;
	}
	*servermode = (int)l;
	return 1;
}

static int parse_dh_special(const char *s, const char **dh_special)
{
	if((strcmp(s, "NULL") == 0) || (strcmp(s, "generate") == 0) ||
			(strcmp(s, "standard") == 0)) {
		*dh_special = s;
		return 1;
	}
	fprintf(stderr, "Error, '%s' is an invalid value for 'dh_special'\n", s);
	return 0;
}

static int parse_verify_level(const char *s, unsigned int *verify_level)
{
	unsigned long l;
	if(!int_strtoul(s, &l) || (l > 3)) {
		fprintf(stderr, "Error, '%s' is an invalid value for "
				"out_verify\n", s);
		return 0;
	}
	*verify_level = (unsigned int)l;
	return 1;
}

static int parse_verify_depth(const char *s, unsigned int *verify_depth)
{
	unsigned long l;
	if(!int_strtoul(s, &l) || (l < 1) || (l > 50)) {
		fprintf(stderr, "Error, '%s' is an invalid value for "
				"verify_depth\n", s);
		return 0;
	}
	*verify_depth = (unsigned int)l;
	return 1;
}

/* Some fprintf format strings used when tunnels close */
static const char *io_stats_dirty =
"    SSL traffic;   %8lu bytes in, %8lu bytes out\n";
static const char *io_stats_clean =
"    clear traffic; %8lu bytes in, %8lu bytes out\n";

int main(int argc, char *argv[])
{
	unsigned int loop;
	int newfd;
	tunala_world_t world;
	tunala_item_t *t_item;
	const char *proxy_ip;
	unsigned short proxy_port;
	/* Overridables */
	const char *proxyhost = def_proxyhost;
	const char *listenhost = def_listenhost;
	unsigned int max_tunnels = def_max_tunnels;
	const char *cacert = def_cacert;
	const char *cert = def_cert;
	const char *key = def_key;
	const char *dcert = def_dcert;
	const char *dkey = def_dkey;
	const char *engine_id = def_engine_id;
	int server_mode = def_server_mode;
	int flipped = def_flipped;
	const char *cipher_list = def_cipher_list;
	const char *dh_file = def_dh_file;
	const char *dh_special = def_dh_special;
	int tmp_rsa = def_tmp_rsa;
	int ctx_options = def_ctx_options;
	int verify_mode = def_verify_mode;
	unsigned int verify_depth = def_verify_depth;
	int out_state = def_out_state;
	unsigned int out_verify = def_out_verify;
	int out_totals = def_out_totals;
	int out_conns = def_out_conns;

/* Parse command-line arguments */
next_arg:
	argc--; argv++;
	if(argc > 0) {
		if(strcmp(*argv, "-listen") == 0) {
			if(argc < 2)
				return usage("-listen requires an argument", 0);
			argc--; argv++;
			listenhost = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-proxy") == 0) {
			if(argc < 2)
				return usage("-proxy requires an argument", 0);
			argc--; argv++;
			proxyhost = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-maxtunnels") == 0) {
			if(argc < 2)
				return usage("-maxtunnels requires an argument", 0);
			argc--; argv++;
			if(!parse_max_tunnels(*argv, &max_tunnels))
				return 1;
			goto next_arg;
		} else if(strcmp(*argv, "-cacert") == 0) {
			if(argc < 2)
				return usage("-cacert requires an argument", 0);
			argc--; argv++;
			if(strcmp(*argv, "NULL") == 0)
				cacert = NULL;
			else
				cacert = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-cert") == 0) {
			if(argc < 2)
				return usage("-cert requires an argument", 0);
			argc--; argv++;
			if(strcmp(*argv, "NULL") == 0)
				cert = NULL;
			else
				cert = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-key") == 0) {
			if(argc < 2)
				return usage("-key requires an argument", 0);
			argc--; argv++;
			if(strcmp(*argv, "NULL") == 0)
				key = NULL;
			else
				key = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-dcert") == 0) {
			if(argc < 2)
				return usage("-dcert requires an argument", 0);
			argc--; argv++;
			if(strcmp(*argv, "NULL") == 0)
				dcert = NULL;
			else
				dcert = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-dkey") == 0) {
			if(argc < 2)
				return usage("-dkey requires an argument", 0);
			argc--; argv++;
			if(strcmp(*argv, "NULL") == 0)
				dkey = NULL;
			else
				dkey = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-engine") == 0) {
			if(argc < 2)
				return usage("-engine requires an argument", 0);
			argc--; argv++;
			engine_id = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-server") == 0) {
			if(argc < 2)
				return usage("-server requires an argument", 0);
			argc--; argv++;
			if(!parse_server_mode(*argv, &server_mode))
				return 1;
			goto next_arg;
		} else if(strcmp(*argv, "-flipped") == 0) {
			if(argc < 2)
				return usage("-flipped requires an argument", 0);
			argc--; argv++;
			if(!parse_server_mode(*argv, &flipped))
				return 1;
			goto next_arg;
		} else if(strcmp(*argv, "-cipher") == 0) {
			if(argc < 2)
				return usage("-cipher requires an argument", 0);
			argc--; argv++;
			cipher_list = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-dh_file") == 0) {
			if(argc < 2)
				return usage("-dh_file requires an argument", 0);
			if(dh_special)
				return usage("cannot mix -dh_file with "
						"-dh_special", 0);
			argc--; argv++;
			dh_file = *argv;
			goto next_arg;
		} else if(strcmp(*argv, "-dh_special") == 0) {
			if(argc < 2)
				return usage("-dh_special requires an argument", 0);
			if(dh_file)
				return usage("cannot mix -dh_file with "
						"-dh_special", 0);
			argc--; argv++;
			if(!parse_dh_special(*argv, &dh_special))
				return 1;
			goto next_arg;
		} else if(strcmp(*argv, "-no_tmp_rsa") == 0) {
			tmp_rsa = 0;
			goto next_arg;
		} else if(strcmp(*argv, "-no_ssl2") == 0) {
			ctx_options |= SSL_OP_NO_SSLv2;
			goto next_arg;
		} else if(strcmp(*argv, "-no_ssl3") == 0) {
			ctx_options |= SSL_OP_NO_SSLv3;
			goto next_arg;
		} else if(strcmp(*argv, "-no_tls1") == 0) {
			ctx_options |= SSL_OP_NO_TLSv1;
			goto next_arg;
		} else if(strcmp(*argv, "-v_peer") == 0) {
			verify_mode |= SSL_VERIFY_PEER;
			goto next_arg;
		} else if(strcmp(*argv, "-v_strict") == 0) {
			verify_mode |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
			goto next_arg;
		} else if(strcmp(*argv, "-v_once") == 0) {
			verify_mode |= SSL_VERIFY_CLIENT_ONCE;
			goto next_arg;
		} else if(strcmp(*argv, "-v_depth") == 0) {
			if(argc < 2)
				return usage("-v_depth requires an argument", 0);
			argc--; argv++;
			if(!parse_verify_depth(*argv, &verify_depth))
				return 1;
			goto next_arg;
		} else if(strcmp(*argv, "-out_state") == 0) {
			out_state = 1;
			goto next_arg;
		} else if(strcmp(*argv, "-out_verify") == 0) {
			if(argc < 2)
				return usage("-out_verify requires an argument", 0);
			argc--; argv++;
			if(!parse_verify_level(*argv, &out_verify))
				return 1;
			goto next_arg;
		} else if(strcmp(*argv, "-out_totals") == 0) {
			out_totals = 1;
			goto next_arg;
		} else if(strcmp(*argv, "-out_conns") == 0) {
			out_conns = 1;
			goto next_arg;
		} else if((strcmp(*argv, "-h") == 0) ||
				(strcmp(*argv, "-help") == 0) ||
				(strcmp(*argv, "-?") == 0)) {
			fprintf(stderr, "%s\n", helpstring);
			return 0;
		} else
			return usage(*argv, 1);
	}
	/* Run any sanity checks we want here */
	if(!cert && !dcert && server_mode)
		fprintf(stderr, "WARNING: you are running an SSL server without "
				"a certificate - this may not work!\n");

	/* Initialise network stuff */
	if(!ip_initialise())
		return err_str0("ip_initialise failed");
	/* Create the SSL_CTX */
	if((world.ssl_ctx = initialise_ssl_ctx(server_mode, engine_id,
			cacert, cert, key, dcert, dkey, cipher_list, dh_file,
			dh_special, tmp_rsa, ctx_options, out_state, out_verify,
			verify_mode, verify_depth)) == NULL)
		return err_str1("initialise_ssl_ctx(engine_id=%s) failed",
			(engine_id == NULL) ? "NULL" : engine_id);
	if(engine_id)
		fprintf(stderr, "Info, engine '%s' initialised\n", engine_id);
	/* Create the listener */
	if((world.listen_fd = ip_create_listener(listenhost)) == -1)
		return err_str1("ip_create_listener(%s) failed", listenhost);
	fprintf(stderr, "Info, listening on '%s'\n", listenhost);
	if(!ip_parse_address(proxyhost, &proxy_ip, &proxy_port, 0))
		return err_str1("ip_parse_address(%s) failed", proxyhost);
	fprintf(stderr, "Info, proxying to '%s' (%d.%d.%d.%d:%d)\n", proxyhost,
			(int)proxy_ip[0], (int)proxy_ip[1],
			(int)proxy_ip[2], (int)proxy_ip[3], (int)proxy_port);
	fprintf(stderr, "Info, set maxtunnels to %d\n", (int)max_tunnels);
	fprintf(stderr, "Info, set to operate as an SSL %s\n",
			(server_mode ? "server" : "client"));
	/* Initialise the rest of the stuff */
	world.tunnels_used = world.tunnels_size = 0;
	world.tunnels = NULL;
	world.server_mode = server_mode;
	selector_init(&world.selector);

/* We're ready to loop */
main_loop:
	/* Should we listen for *new* tunnels? */
	if(world.tunnels_used < max_tunnels)
		selector_add_listener(&world.selector, world.listen_fd);
	/* We should add in our existing tunnels */
	for(loop = 0; loop < world.tunnels_used; loop++)
		selector_add_tunala(&world.selector, world.tunnels + loop);
	/* Now do the select */
	switch(selector_select(&world.selector)) {
	case -1:
		if(errno != EINTR) {
			fprintf(stderr, "selector_select returned a "
					"badness error.\n");
			goto shouldnt_happen;
		}
		fprintf(stderr, "Warn, selector interrupted by a signal\n");
		goto main_loop;
	case 0:
		fprintf(stderr, "Warn, selector_select returned 0 - signal?""?\n");
		goto main_loop;
	default:
		break;
	}
	/* Accept new connection if we should and can */
	if((world.tunnels_used < max_tunnels) && (selector_get_listener(
					&world.selector, world.listen_fd,
					&newfd) == 1)) {
		/* We have a new connection */
		if(!tunala_world_new_item(&world, newfd, proxy_ip,
						proxy_port, flipped))
			fprintf(stderr, "tunala_world_new_item failed\n");
		else if(out_conns)
			fprintf(stderr, "Info, new tunnel opened, now up to "
					"%d\n", world.tunnels_used);
	}
	/* Give each tunnel its moment, note the while loop is because it makes
	 * the logic easier than with "for" to deal with an array that may shift
	 * because of deletes. */
	loop = 0;
	t_item = world.tunnels;
	while(loop < world.tunnels_used) {
		if(!tunala_item_io(&world.selector, t_item)) {
			/* We're closing whether for reasons of an error or a
			 * natural close. Don't increment loop or t_item because
			 * the next item is moving to us! */
			if(!out_totals)
				goto skip_totals;
			fprintf(stderr, "Tunnel closing, traffic stats follow\n");
			/* Display the encrypted (over the network) stats */
			fprintf(stderr, io_stats_dirty,
				buffer_total_in(state_machine_get_buffer(
						&t_item->sm,SM_DIRTY_IN)),
				buffer_total_out(state_machine_get_buffer(
						&t_item->sm,SM_DIRTY_OUT)));
			/* Display the local (tunnelled) stats. NB: Data we
			 * *receive* is data sent *out* of the state_machine on
			 * its 'clean' side. Hence the apparent back-to-front
			 * OUT/IN mixup here :-) */
			fprintf(stderr, io_stats_clean,
				buffer_total_out(state_machine_get_buffer(
						&t_item->sm,SM_CLEAN_OUT)),
				buffer_total_in(state_machine_get_buffer(
						&t_item->sm,SM_CLEAN_IN)));
skip_totals:
			tunala_world_del_item(&world, loop);
			if(out_conns)
				fprintf(stderr, "Info, tunnel closed, down to %d\n",
					world.tunnels_used);
		}
		else {
			/* Move to the next item */
			loop++;
			t_item++;
		}
	}
	goto main_loop;
	/* Should never get here */
shouldnt_happen:
	abort();
	return 1;
}

/****************/
/* OpenSSL bits */
/****************/

static int ctx_set_cert(SSL_CTX *ctx, const char *cert, const char *key)
{
	FILE *fp = NULL;
	X509 *x509 = NULL;
	EVP_PKEY *pkey = NULL;
	int toret = 0; /* Assume an error */

	/* cert */
	if(cert) {
		if((fp = fopen(cert, "r")) == NULL) {
			fprintf(stderr, "Error opening cert file '%s'\n", cert);
			goto err;
		}
		if(!PEM_read_X509(fp, &x509, NULL, NULL)) {
			fprintf(stderr, "Error reading PEM cert from '%s'\n",
					cert);
			goto err;
		}
		if(!SSL_CTX_use_certificate(ctx, x509)) {
			fprintf(stderr, "Error, cert in '%s' can not be used\n",
					cert);
			goto err;
		}
		/* Clear the FILE* for reuse in the "key" code */
		fclose(fp);
		fp = NULL;
		fprintf(stderr, "Info, operating with cert in '%s'\n", cert);
		/* If a cert was given without matching key, we assume the same
		 * file contains the required key. */
		if(!key)
			key = cert;
	} else {
		if(key)
			fprintf(stderr, "Error, can't specify a key without a "
					"corresponding certificate\n");
		else
			fprintf(stderr, "Error, ctx_set_cert called with "
					"NULLs!\n");
		goto err;
	}
	/* key */
	if(key) {
		if((fp = fopen(key, "r")) == NULL) {
			fprintf(stderr, "Error opening key file '%s'\n", key);
			goto err;
		}
		if(!PEM_read_PrivateKey(fp, &pkey, NULL, NULL)) {
			fprintf(stderr, "Error reading PEM key from '%s'\n",
					key);
			goto err;
		}
		if(!SSL_CTX_use_PrivateKey(ctx, pkey)) {
			fprintf(stderr, "Error, key in '%s' can not be used\n",
					key);
			goto err;
		}
		fprintf(stderr, "Info, operating with key in '%s'\n", key);
	} else
		fprintf(stderr, "Info, operating without a cert or key\n");
	/* Success */
	toret = 1; err:
	if(x509)
		X509_free(x509);
	if(pkey)
		EVP_PKEY_free(pkey);
	if(fp)
		fclose(fp);
	return toret;
}

static int ctx_set_dh(SSL_CTX *ctx, const char *dh_file, const char *dh_special)
{
	DH *dh = NULL;
	FILE *fp = NULL;

	if(dh_special) {
		if(strcmp(dh_special, "NULL") == 0)
			return 1;
		if(strcmp(dh_special, "standard") == 0) {
			if((dh = get_dh512()) == NULL) {
				fprintf(stderr, "Error, can't parse 'standard'"
						" DH parameters\n");
				return 0;
			}
			fprintf(stderr, "Info, using 'standard' DH parameters\n");
			goto do_it;
		}
		if(strcmp(dh_special, "generate") != 0)
			/* This shouldn't happen - screening values is handled
			 * in main(). */
			abort();
		fprintf(stderr, "Info, generating DH parameters ... ");
		fflush(stderr);
		if(!(dh = DH_new()) || !DH_generate_parameters_ex(dh, 512,
					DH_GENERATOR_5, NULL)) {
			fprintf(stderr, "error!\n");
			if(dh)
				DH_free(dh);
			return 0;
		}
		fprintf(stderr, "complete\n");
		goto do_it;
	}
	/* So, we're loading dh_file */
	if((fp = fopen(dh_file, "r")) == NULL) {
		fprintf(stderr, "Error, couldn't open '%s' for DH parameters\n",
				dh_file);
		return 0;
	}
	dh = PEM_read_DHparams(fp, NULL, NULL, NULL);
	fclose(fp);
	if(dh == NULL) {
		fprintf(stderr, "Error, could not parse DH parameters from '%s'\n",
				dh_file);
		return 0;
	}
	fprintf(stderr, "Info, using DH parameters from file '%s'\n", dh_file);
do_it:
	SSL_CTX_set_tmp_dh(ctx, dh);
	DH_free(dh);
	return 1;
}

static SSL_CTX *initialise_ssl_ctx(int server_mode, const char *engine_id,
		const char *CAfile, const char *cert, const char *key,
		const char *dcert, const char *dkey, const char *cipher_list,
		const char *dh_file, const char *dh_special, int tmp_rsa,
		int ctx_options, int out_state, int out_verify, int verify_mode,
		unsigned int verify_depth)
{
	SSL_CTX *ctx = NULL, *ret = NULL;
	const SSL_METHOD *meth;
	ENGINE *e = NULL;

        OpenSSL_add_ssl_algorithms();
        SSL_load_error_strings();

	meth = (server_mode ? SSLv23_server_method() : SSLv23_client_method());
	if(meth == NULL)
		goto err;
	if(engine_id) {
		ENGINE_load_builtin_engines();
		if((e = ENGINE_by_id(engine_id)) == NULL) {
			fprintf(stderr, "Error obtaining '%s' engine, openssl "
					"errors follow\n", engine_id);
			goto err;
		}
		if(!ENGINE_set_default(e, ENGINE_METHOD_ALL)) {
			fprintf(stderr, "Error assigning '%s' engine, openssl "
					"errors follow\n", engine_id);
			goto err;
		}
		ENGINE_free(e);
	}
	if((ctx = SSL_CTX_new(meth)) == NULL)
		goto err;
	/* cacert */
	if(CAfile) {
		if(!X509_STORE_load_locations(SSL_CTX_get_cert_store(ctx),
					CAfile, NULL)) {
			fprintf(stderr, "Error loading CA cert(s) in '%s'\n",
					CAfile);
			goto err;
		}
		fprintf(stderr, "Info, operating with CA cert(s) in '%s'\n",
				CAfile);
	} else
		fprintf(stderr, "Info, operating without a CA cert(-list)\n");
	if(!SSL_CTX_set_default_verify_paths(ctx)) {
		fprintf(stderr, "Error setting default verify paths\n");
		goto err;
	}

	/* cert and key */
	if((cert || key) && !ctx_set_cert(ctx, cert, key))
		goto err;
	/* dcert and dkey */
	if((dcert || dkey) && !ctx_set_cert(ctx, dcert, dkey))
		goto err;
	/* temporary RSA key generation */
	if(tmp_rsa)
		SSL_CTX_set_tmp_rsa_callback(ctx, cb_generate_tmp_rsa);

	/* cipher_list */
	if(cipher_list) {
		if(!SSL_CTX_set_cipher_list(ctx, cipher_list)) {
			fprintf(stderr, "Error setting cipher list '%s'\n",
					cipher_list);
			goto err;
		}
		fprintf(stderr, "Info, set cipher list '%s'\n", cipher_list);
	} else
		fprintf(stderr, "Info, operating with default cipher list\n");

	/* dh_file & dh_special */
	if((dh_file || dh_special) && !ctx_set_dh(ctx, dh_file, dh_special))
		goto err;

	/* ctx_options */
	SSL_CTX_set_options(ctx, ctx_options);

	/* out_state (output of SSL handshake states to screen). */
	if(out_state)
		cb_ssl_info_set_output(stderr);

	/* out_verify */
	if(out_verify > 0) {
		cb_ssl_verify_set_output(stderr);
		cb_ssl_verify_set_level(out_verify);
	}

	/* verify_depth */
	cb_ssl_verify_set_depth(verify_depth);

	/* Success! (includes setting verify_mode) */
	SSL_CTX_set_info_callback(ctx, cb_ssl_info);
	SSL_CTX_set_verify(ctx, verify_mode, cb_ssl_verify);
	ret = ctx;
err:
	if(!ret) {
		ERR_print_errors_fp(stderr);
		if(ctx)
			SSL_CTX_free(ctx);
	}
	return ret;
}

/*****************/
/* Selector bits */
/*****************/

static void selector_sets_init(select_sets_t *s)
{
	s->max = 0;
	FD_ZERO(&s->reads);
	FD_ZERO(&s->sends);
	FD_ZERO(&s->excepts);
}
static void selector_init(tunala_selector_t *selector)
{
	selector_sets_init(&selector->last_selected);
	selector_sets_init(&selector->next_select);
}

#define SEL_EXCEPTS 0x00
#define SEL_READS   0x01
#define SEL_SENDS   0x02
static void selector_add_raw_fd(tunala_selector_t *s, int fd, int flags)
{
	FD_SET(fd, &s->next_select.excepts);
	if(flags & SEL_READS)
		FD_SET(fd, &s->next_select.reads);
	if(flags & SEL_SENDS)
		FD_SET(fd, &s->next_select.sends);
	/* Adjust "max" */
	if(s->next_select.max < (fd + 1))
		s->next_select.max = fd + 1;
}

static void selector_add_listener(tunala_selector_t *selector, int fd)
{
	selector_add_raw_fd(selector, fd, SEL_READS);
}

static void selector_add_tunala(tunala_selector_t *s, tunala_item_t *t)
{
	/* Set clean read if sm.clean_in is not full */
	if(t->clean_read != -1) {
		selector_add_raw_fd(s, t->clean_read,
			(buffer_full(state_machine_get_buffer(&t->sm,
				SM_CLEAN_IN)) ? SEL_EXCEPTS : SEL_READS));
	}
	/* Set clean send if sm.clean_out is not empty */
	if(t->clean_send != -1) {
		selector_add_raw_fd(s, t->clean_send,
			(buffer_empty(state_machine_get_buffer(&t->sm,
				SM_CLEAN_OUT)) ? SEL_EXCEPTS : SEL_SENDS));
	}
	/* Set dirty read if sm.dirty_in is not full */
	if(t->dirty_read != -1) {
		selector_add_raw_fd(s, t->dirty_read,
			(buffer_full(state_machine_get_buffer(&t->sm,
				SM_DIRTY_IN)) ? SEL_EXCEPTS : SEL_READS));
	}
	/* Set dirty send if sm.dirty_out is not empty */
	if(t->dirty_send != -1) {
		selector_add_raw_fd(s, t->dirty_send,
			(buffer_empty(state_machine_get_buffer(&t->sm,
				SM_DIRTY_OUT)) ? SEL_EXCEPTS : SEL_SENDS));
	}
}

static int selector_select(tunala_selector_t *selector)
{
	memcpy(&selector->last_selected, &selector->next_select,
			sizeof(select_sets_t));
	selector_sets_init(&selector->next_select);
	return select(selector->last_selected.max,
			&selector->last_selected.reads,
			&selector->last_selected.sends,
			&selector->last_selected.excepts, NULL);
}

/* This returns -1 for error, 0 for no new connections, or 1 for success, in
 * which case *newfd is populated. */
static int selector_get_listener(tunala_selector_t *selector, int fd, int *newfd)
{
	if(FD_ISSET(fd, &selector->last_selected.excepts))
		return -1;
	if(!FD_ISSET(fd, &selector->last_selected.reads))
		return 0;
	if((*newfd = ip_accept_connection(fd)) == -1)
		return -1;
	return 1;
}

/************************/
/* "Tunala" world stuff */
/************************/

static int tunala_world_make_room(tunala_world_t *world)
{
	unsigned int newsize;
	tunala_item_t *newarray;

	if(world->tunnels_used < world->tunnels_size)
		return 1;
	newsize = (world->tunnels_size == 0 ? 16 :
			((world->tunnels_size * 3) / 2));
	if((newarray = malloc(newsize * sizeof(tunala_item_t))) == NULL)
		return 0;
	memset(newarray, 0, newsize * sizeof(tunala_item_t));
	if(world->tunnels_used > 0)
		memcpy(newarray, world->tunnels,
			world->tunnels_used * sizeof(tunala_item_t));
	if(world->tunnels_size > 0)
		free(world->tunnels);
	/* migrate */
	world->tunnels = newarray;
	world->tunnels_size = newsize;
	return 1;
}

static int tunala_world_new_item(tunala_world_t *world, int fd,
		const char *ip, unsigned short port, int flipped)
{
	tunala_item_t *item;
	int newfd;
	SSL *new_ssl = NULL;

	if(!tunala_world_make_room(world))
		return 0;
	if((new_ssl = SSL_new(world->ssl_ctx)) == NULL) {
		fprintf(stderr, "Error creating new SSL\n");
		ERR_print_errors_fp(stderr);
		return 0;
	}
	item = world->tunnels + (world->tunnels_used++);
	state_machine_init(&item->sm);
	item->clean_read = item->clean_send =
		item->dirty_read = item->dirty_send = -1;
	if((newfd = ip_create_connection_split(ip, port)) == -1)
		goto err;
	/* Which way round? If we're a server, "fd" is the dirty side and the
	 * connection we open is the clean one. For a client, it's the other way
	 * around. Unless, of course, we're "flipped" in which case everything
	 * gets reversed. :-) */
	if((world->server_mode && !flipped) ||
			(!world->server_mode && flipped)) {
		item->dirty_read = item->dirty_send = fd;
		item->clean_read = item->clean_send = newfd;
	} else {
		item->clean_read = item->clean_send = fd;
		item->dirty_read = item->dirty_send = newfd;
	}
	/* We use the SSL's "app_data" to indicate a call-back induced "kill" */
	SSL_set_app_data(new_ssl, NULL);
	if(!state_machine_set_SSL(&item->sm, new_ssl, world->server_mode))
		goto err;
	return 1;
err:
	tunala_world_del_item(world, world->tunnels_used - 1);
	return 0;

}

static void tunala_world_del_item(tunala_world_t *world, unsigned int idx)
{
	tunala_item_t *item = world->tunnels + idx;
	if(item->clean_read != -1)
		close(item->clean_read);
	if(item->clean_send != item->clean_read)
		close(item->clean_send);
	item->clean_read = item->clean_send = -1;
	if(item->dirty_read != -1)
		close(item->dirty_read);
	if(item->dirty_send != item->dirty_read)
		close(item->dirty_send);
	item->dirty_read = item->dirty_send = -1;
	state_machine_close(&item->sm);
	/* OK, now we fix the item array */
	if(idx + 1 < world->tunnels_used)
		/* We need to scroll entries to the left */
		memmove(world->tunnels + idx,
				world->tunnels + (idx + 1),
				(world->tunnels_used - (idx + 1)) *
					sizeof(tunala_item_t));
	world->tunnels_used--;
}

static int tunala_item_io(tunala_selector_t *selector, tunala_item_t *item)
{
	int c_r, c_s, d_r, d_s; /* Four boolean flags */

	/* Take ourselves out of the gene-pool if there was an except */
	if((item->clean_read != -1) && FD_ISSET(item->clean_read,
				&selector->last_selected.excepts))
		return 0;
	if((item->clean_send != -1) && FD_ISSET(item->clean_send,
				&selector->last_selected.excepts))
		return 0;
	if((item->dirty_read != -1) && FD_ISSET(item->dirty_read,
				&selector->last_selected.excepts))
		return 0;
	if((item->dirty_send != -1) && FD_ISSET(item->dirty_send,
				&selector->last_selected.excepts))
		return 0;
	/* Grab our 4 IO flags */
	c_r = c_s = d_r = d_s = 0;
	if(item->clean_read != -1)
		c_r = FD_ISSET(item->clean_read, &selector->last_selected.reads);
	if(item->clean_send != -1)
		c_s = FD_ISSET(item->clean_send, &selector->last_selected.sends);
	if(item->dirty_read != -1)
		d_r = FD_ISSET(item->dirty_read, &selector->last_selected.reads);
	if(item->dirty_send != -1)
		d_s = FD_ISSET(item->dirty_send, &selector->last_selected.sends);
	/* If no IO has happened for us, skip needless data looping */
	if(!c_r && !c_s && !d_r && !d_s)
		return 1;
	if(c_r)
		c_r = (buffer_from_fd(state_machine_get_buffer(&item->sm,
				SM_CLEAN_IN), item->clean_read) <= 0);
	if(c_s)
		c_s = (buffer_to_fd(state_machine_get_buffer(&item->sm,
				SM_CLEAN_OUT), item->clean_send) <= 0);
	if(d_r)
		d_r = (buffer_from_fd(state_machine_get_buffer(&item->sm,
				SM_DIRTY_IN), item->dirty_read) <= 0);
	if(d_s)
		d_s = (buffer_to_fd(state_machine_get_buffer(&item->sm,
				SM_DIRTY_OUT), item->dirty_send) <= 0);
	/* If any of the flags is non-zero, that means they need closing */
	if(c_r) {
		close(item->clean_read);
		if(item->clean_send == item->clean_read)
			item->clean_send = -1;
		item->clean_read = -1;
	}
	if(c_s && (item->clean_send != -1)) {
		close(item->clean_send);
		if(item->clean_send == item->clean_read)
			item->clean_read = -1;
		item->clean_send = -1;
	}
	if(d_r) {
		close(item->dirty_read);
		if(item->dirty_send == item->dirty_read)
			item->dirty_send = -1;
		item->dirty_read = -1;
	}
	if(d_s && (item->dirty_send != -1)) {
		close(item->dirty_send);
		if(item->dirty_send == item->dirty_read)
			item->dirty_read = -1;
		item->dirty_send = -1;
	}
	/* This function name is attributed to the term donated by David
	 * Schwartz on openssl-dev, message-ID:
	 * <NCBBLIEPOCNJOAEKBEAKEEDGLIAA.davids@webmaster.com>. :-) */
	if(!state_machine_churn(&item->sm))
		/* If the SSL closes, it will also zero-out the _in buffers
		 * and will in future process just outgoing data. As and
		 * when the outgoing data has gone, it will return zero
		 * here to tell us to bail out. */
		return 0;
	/* Otherwise, we return zero if both sides are dead. */
	if(((item->clean_read == -1) || (item->clean_send == -1)) &&
			((item->dirty_read == -1) || (item->dirty_send == -1)))
		return 0;
	/* If only one side closed, notify the SSL of this so it can take
	 * appropriate action. */
	if((item->clean_read == -1) || (item->clean_send == -1)) {
		if(!state_machine_close_clean(&item->sm))
			return 0;
	}
	if((item->dirty_read == -1) || (item->dirty_send == -1)) {
		if(!state_machine_close_dirty(&item->sm))
			return 0;
	}
	return 1;
}