summaryrefslogtreecommitdiff
path: root/common.c
blob: 6320afd396e50f26f9238c2bdb9c01363baea9cb (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
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
/*
 * common.c: common functionality
 *
 * Copyright (c) 2014 - 2015, Přemysl Janouch <p.janouch@gmail.com>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

#define LIBERTY_WANT_SSL
#define LIBERTY_WANT_POLLER
#define LIBERTY_WANT_PROTO_IRC

#ifdef WANT_SYSLOG_LOGGING
	#define print_fatal_data    ((void *) LOG_ERR)
	#define print_error_data    ((void *) LOG_ERR)
	#define print_warning_data  ((void *) LOG_WARNING)
	#define print_status_data   ((void *) LOG_INFO)
	#define print_debug_data    ((void *) LOG_DEBUG)
#endif // WANT_SYSLOG_LOGGING

#include "liberty/liberty.c"
#include <setjmp.h>
#include <inttypes.h>
#include <arpa/inet.h>

/// Shorthand to set an error and return failure from the function
#define FAIL(...)                                                              \
	BLOCK_START                                                                \
		error_set (e, __VA_ARGS__);                                            \
		return false;                                                          \
	BLOCK_END

// A few other debugging shorthands
#define LOG_FUNC_FAILURE(name, desc)                                           \
	print_debug ("%s: %s: %s", __func__, (name), (desc))
#define LOG_LIBC_FAILURE(name)                                                 \
	print_debug ("%s: %s: %s", __func__, (name), strerror (errno))

// --- Logging -----------------------------------------------------------------

static void
log_message_syslog (void *user_data, const char *quote, const char *fmt,
	va_list ap)
{
	int prio = (int) (intptr_t) user_data;

	va_list va;
	va_copy (va, ap);
	int size = vsnprintf (NULL, 0, fmt, va);
	va_end (va);
	if (size < 0)
		return;

	char buf[size + 1];
	if (vsnprintf (buf, sizeof buf, fmt, ap) >= 0)
		syslog (prio, "%s%s", quote, buf);
}

// --- SOCKS 5/4a (blocking implementation) ------------------------------------

// These are awkward protocols.  Note that the `username' is used differently
// in SOCKS 4a and 5.  In the former version, it is the username that you can
// get ident'ed against.  In the latter version, it forms a pair with the
// password field and doesn't need to be an actual user on your machine.

// TODO: make a non-blocking poller-based version of this;
//   either use c-ares or (even better) start another thread to do resolution

struct socks_addr
{
	enum socks_addr_type
	{
		SOCKS_IPV4 = 1,                 ///< IPv4 address
		SOCKS_DOMAIN = 3,               ///< Domain name to be resolved
		SOCKS_IPV6 = 4                  ///< IPv6 address
	}
	type;                               ///< The type of this address
	union
	{
		uint8_t ipv4[4];                ///< IPv4 address, network octet order
		const char *domain;             ///< Domain name
		uint8_t ipv6[16];               ///< IPv6 address, network octet order
	}
	data;                               ///< The address itself
};

struct socks_data
{
	struct socks_addr address;          ///< Target address
	uint16_t port;                      ///< Target port
	const char *username;               ///< Authentication username
	const char *password;               ///< Authentication password

	struct socks_addr bound_address;    ///< Bound address at the server
	uint16_t bound_port;                ///< Bound port at the server
};

static bool
socks_get_socket (struct addrinfo *addresses, int *fd, struct error **e)
{
	int sockfd;
	for (; addresses; addresses = addresses->ai_next)
	{
		sockfd = socket (addresses->ai_family,
			addresses->ai_socktype, addresses->ai_protocol);
		if (sockfd == -1)
			continue;
		set_cloexec (sockfd);

		int yes = 1;
		soft_assert (setsockopt (sockfd, SOL_SOCKET, SO_KEEPALIVE,
			&yes, sizeof yes) != -1);

		if (!connect (sockfd, addresses->ai_addr, addresses->ai_addrlen))
			break;
		xclose (sockfd);
	}
	if (!addresses)
	{
		error_set (e, "couldn't connect to the SOCKS server");
		return false;
	}
	*fd = sockfd;
	return true;
}

#define SOCKS_FAIL(...)                                                        \
	BLOCK_START                                                                \
		error_set (e, __VA_ARGS__);                                            \
		goto fail;                                                             \
	BLOCK_END
#define SOCKS_RECV(buf, len)                                                   \
	BLOCK_START                                                                \
		if ((n = recv (sockfd, (buf), (len), 0)) == -1)                        \
			SOCKS_FAIL ("%s: %s", "recv", strerror (errno));                   \
		if (n != (len))                                                        \
			SOCKS_FAIL ("%s: %s", "protocol error", "unexpected EOF");         \
	BLOCK_END

static bool
socks_4a_connect (struct addrinfo *addresses, struct socks_data *data,
	int *fd, struct error **e)
{
	int sockfd;
	if (!socks_get_socket (addresses, &sockfd, e))
		return false;

	const void *dest_ipv4 = "\x00\x00\x00\x01";
	const char *dest_domain = NULL;

	char buf[INET6_ADDRSTRLEN];
	switch (data->address.type)
	{
	case SOCKS_IPV4:
		dest_ipv4 = data->address.data.ipv4;
		break;
	case SOCKS_IPV6:
		// About the best thing we can do, not sure if it works anywhere at all
		if (!inet_ntop (AF_INET6, &data->address.data.ipv6, buf, sizeof buf))
			SOCKS_FAIL ("%s: %s", "inet_ntop", strerror (errno));
		dest_domain = buf;
		break;
	case SOCKS_DOMAIN:
		dest_domain = data->address.data.domain;
	}

	struct str req;
	str_init (&req);
	str_append_c (&req, 4);                // version
	str_append_c (&req, 1);                // connect

	str_append_c (&req, data->port >> 8);  // higher bits of port
	str_append_c (&req, data->port);       // lower bits of port
	str_append_data (&req, dest_ipv4, 4);  // destination address

	if (data->username)
		str_append (&req, data->username);
	str_append_c (&req, '\0');

	if (dest_domain)
	{
		str_append (&req, dest_domain);
		str_append_c (&req, '\0');
	}

	ssize_t n = send (sockfd, req.str, req.len, 0);
	str_free (&req);
	if (n == -1)
		SOCKS_FAIL ("%s: %s", "send", strerror (errno));

	uint8_t resp[8];
	SOCKS_RECV (resp, sizeof resp);
	if (resp[0] != 0)
		SOCKS_FAIL ("protocol error");

	switch (resp[1])
	{
	case 90:
		break;
	case 91:
		SOCKS_FAIL ("request rejected or failed");
	case 92:
		SOCKS_FAIL ("%s: %s", "request rejected",
			"SOCKS server cannot connect to identd on the client");
	case 93:
		SOCKS_FAIL ("%s: %s", "request rejected",
			"identd reports different user-id");
	default:
		SOCKS_FAIL ("protocol error");
	}

	*fd = sockfd;
	return true;

fail:
	xclose (sockfd);
	return false;
}

#undef SOCKS_FAIL
#define SOCKS_FAIL(...)                                                        \
	BLOCK_START                                                                \
		error_set (e, __VA_ARGS__);                                            \
		return false;                                                          \
	BLOCK_END

static bool
socks_5_userpass_auth (int sockfd, struct socks_data *data, struct error **e)
{
	size_t ulen = strlen (data->username);
	if (ulen > 255)
		ulen = 255;

	size_t plen = strlen (data->password);
	if (plen > 255)
		plen = 255;

	uint8_t req[3 + ulen + plen], *p = req;
	*p++ = 0x01;  // version
	*p++ = ulen;  // username length
	memcpy (p, data->username, ulen);
	p += ulen;
	*p++ = plen;  // password length
	memcpy (p, data->password, plen);
	p += plen;

	ssize_t n = send (sockfd, req, p - req, 0);
	if (n == -1)
		SOCKS_FAIL ("%s: %s", "send", strerror (errno));

	uint8_t resp[2];
	SOCKS_RECV (resp, sizeof resp);
	if (resp[0] != 0x01)
		SOCKS_FAIL ("protocol error");
	if (resp[1] != 0x00)
		SOCKS_FAIL ("authentication failure");
	return true;
}

static bool
socks_5_auth (int sockfd, struct socks_data *data, struct error **e)
{
	bool can_auth = data->username && data->password;

	uint8_t hello[4];
	hello[0] = 0x05;          // version
	hello[1] = 1 + can_auth;  // number of authentication methods
	hello[2] = 0x00;          // no authentication required
	hello[3] = 0x02;          // username/password

	ssize_t n = send (sockfd, hello, 3 + can_auth, 0);
	if (n == -1)
		SOCKS_FAIL ("%s: %s", "send", strerror (errno));

	uint8_t resp[2];
	SOCKS_RECV (resp, sizeof resp);
	if (resp[0] != 0x05)
		SOCKS_FAIL ("protocol error");

	switch (resp[1])
	{
	case 0x02:
		if (!can_auth)
			SOCKS_FAIL ("protocol error");
		if (!socks_5_userpass_auth (sockfd, data, e))
			return false;
	case 0x00:
		break;
	case 0xFF:
		SOCKS_FAIL ("no acceptable authentication methods");
	default:
		SOCKS_FAIL ("protocol error");
	}
	return true;
}

static bool
socks_5_send_req (int sockfd, struct socks_data *data, struct error **e)
{
	uint8_t req[4 + 256 + 2], *p = req;
	*p++ = 0x05;  // version
	*p++ = 0x01;  // connect
	*p++ = 0x00;  // reserved
	*p++ = data->address.type;

	switch (data->address.type)
	{
	case SOCKS_IPV4:
		memcpy (p, data->address.data.ipv4, sizeof data->address.data.ipv4);
		p += sizeof data->address.data.ipv4;
		break;
	case SOCKS_DOMAIN:
	{
		size_t dlen = strlen (data->address.data.domain);
		if (dlen > 255)
			dlen = 255;

		*p++ = dlen;
		memcpy (p, data->address.data.domain, dlen);
		p += dlen;
		break;
	}
	case SOCKS_IPV6:
		memcpy (p, data->address.data.ipv6, sizeof data->address.data.ipv6);
		p += sizeof data->address.data.ipv6;
		break;
	}
	*p++ = data->port >> 8;
	*p++ = data->port;

	if (send (sockfd, req, p - req, 0) == -1)
		SOCKS_FAIL ("%s: %s", "send", strerror (errno));
	return true;
}

static bool
socks_5_process_resp (int sockfd, struct socks_data *data, struct error **e)
{
	uint8_t resp_header[4];
	ssize_t n;
	SOCKS_RECV (resp_header, sizeof resp_header);
	if (resp_header[0] != 0x05)
		SOCKS_FAIL ("protocol error");

	switch (resp_header[1])
	{
	case 0x00:
		break;
	case 0x01:  SOCKS_FAIL ("general SOCKS server failure");
	case 0x02:  SOCKS_FAIL ("connection not allowed by ruleset");
	case 0x03:  SOCKS_FAIL ("network unreachable");
	case 0x04:  SOCKS_FAIL ("host unreachable");
	case 0x05:  SOCKS_FAIL ("connection refused");
	case 0x06:  SOCKS_FAIL ("TTL expired");
	case 0x07:  SOCKS_FAIL ("command not supported");
	case 0x08:  SOCKS_FAIL ("address type not supported");
	default:    SOCKS_FAIL ("protocol error");
	}

	switch ((data->bound_address.type = resp_header[3]))
	{
	case SOCKS_IPV4:
		SOCKS_RECV (data->bound_address.data.ipv4,
			sizeof data->bound_address.data.ipv4);
		break;
	case SOCKS_IPV6:
		SOCKS_RECV (data->bound_address.data.ipv6,
			sizeof data->bound_address.data.ipv6);
		break;
	case SOCKS_DOMAIN:
	{
		uint8_t len;
		SOCKS_RECV (&len, sizeof len);

		char domain[len + 1];
		SOCKS_RECV (domain, len);
		domain[len] = '\0';

		data->bound_address.data.domain = xstrdup (domain);
		break;
	}
	default:
		SOCKS_FAIL ("protocol error");
	}

	uint16_t port;
	SOCKS_RECV (&port, sizeof port);
	data->bound_port = ntohs (port);
	return true;
}

#undef SOCKS_FAIL
#undef SOCKS_RECV

static bool
socks_5_connect (struct addrinfo *addresses, struct socks_data *data,
	int *fd, struct error **e)
{
	int sockfd;
	if (!socks_get_socket (addresses, &sockfd, e))
		return false;

	if (!socks_5_auth (sockfd, data, e)
	 || !socks_5_send_req (sockfd, data, e)
	 || !socks_5_process_resp (sockfd, data, e))
	{
		xclose (sockfd);
		return false;
	}

	*fd = sockfd;
	return true;
}

static int
socks_connect (const char *socks_host, const char *socks_port,
	const char *host, const char *port,
	const char *username, const char *password, struct error **e)
{
	int result = -1;
	struct addrinfo gai_hints, *gai_result;
	memset (&gai_hints, 0, sizeof gai_hints);
	gai_hints.ai_socktype = SOCK_STREAM;

	unsigned long port_no;
	const struct servent *serv;
	if ((serv = getservbyname (port, "tcp")))
		port_no = (uint16_t) ntohs (serv->s_port);
	else if (!xstrtoul (&port_no, port, 10) || !port_no || port_no > UINT16_MAX)
	{
		error_set (e, "invalid port number");
		goto fail;
	}

	int err = getaddrinfo (socks_host, socks_port, &gai_hints, &gai_result);
	if (err)
	{
		error_set (e, "%s: %s", "getaddrinfo", gai_strerror (err));
		goto fail;
	}

	struct socks_data data =
		{ .username = username, .password = password, .port = port_no };

	if      (inet_pton (AF_INET,  host, &data.address.data.ipv4) == 1)
		data.address.type = SOCKS_IPV4;
	else if (inet_pton (AF_INET6, host, &data.address.data.ipv6) == 1)
		data.address.type = SOCKS_IPV6;
	else
	{
		data.address.type = SOCKS_DOMAIN;
		data.address.data.domain = host;
	}

	if (!socks_5_connect (gai_result, &data, &result, NULL))
		socks_4a_connect (gai_result, &data, &result, e);

	if (data.bound_address.type == SOCKS_DOMAIN)
		free ((char *) data.bound_address.data.domain);
	freeaddrinfo (gai_result);
fail:
	return result;
}

// --- To be moved to liberty --------------------------------------------------

static bool
isalpha_ascii (int c)
{
	c &= ~32;
	return c >= 'A' && c <= 'Z';
}

static bool
isdigit_ascii (int c)
{
	return c >= '0' && c <= '9';
}

static bool
isalnum_ascii (int c)
{
	return isalpha_ascii (c) || isdigit_ascii (c);
}

static int
toupper_ascii (int c)
{
	return c >= 'A' && c <= 'Z' ? c : c - ('a' - 'A');
}

static void
split_str (const char *s, char delimiter, struct str_vector *out)
{
	const char *begin = s, *end;
	while ((end = strchr (begin, delimiter)))
	{
		str_vector_add_owned (out, xstrndup (begin, end - begin));
		begin = ++end;
	}
	str_vector_add (out, begin);
}

// --- Advanced configuration --------------------------------------------------

// This is a new configuration format, superseding the one currently present
// in liberty.  It's just a lot more complicated and allows key-value maps.
// We need it in degesch to provide non-sucking user experience.

enum config_item_type
{
	CONFIG_ITEM_NULL,                   ///< No value
	CONFIG_ITEM_OBJECT,                 ///< Key-value map
	CONFIG_ITEM_BOOLEAN,                ///< Truth value
	CONFIG_ITEM_INTEGER,                ///< Integer
	CONFIG_ITEM_STRING,                 ///< Arbitrary string of characters
	CONFIG_ITEM_STRING_ARRAY            ///< Comma-separated list of strings
};

struct config_item_
{
	enum config_item_type type;         ///< Type of the item
	union
	{
		struct str_map object;          ///< Key-value data
		bool boolean;                   ///< Boolean data
		int64_t integer;                ///< Integer data
		struct str string;              ///< String data
	}
	value;                              ///< The value of this item

	struct config_schema *schema;       ///< Schema describing this value
	void *user_data;                    ///< User value attached by schema owner
};

struct config_schema
{
	const char *name;                   ///< Name of the item
	const char *comment;                ///< User-readable description

	enum config_item_type type;         ///< Required type
	const char *default_;               ///< Default as a configuration snippet

	/// Check if the new value can be accepted.
	/// If this is not defined, only "type" and having a default is considered.
	bool (*validate) (struct config_item_ *, const struct config_item_ *);

	/// The value has changed. Only appliable to objects.
	void (*on_changed) (struct config_item_ *);

	/// Free any resources located in "item->user_data"
	void (*on_destroy) (struct config_item_ *item);
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static const char *
config_item_type_name (enum config_item_type type)
{
	switch (type)
	{
	case CONFIG_ITEM_NULL:          return "null";
	case CONFIG_ITEM_BOOLEAN:       return "boolean";
	case CONFIG_ITEM_INTEGER:       return "integer";
	case CONFIG_ITEM_STRING:        return "string";
	case CONFIG_ITEM_STRING_ARRAY:  return "string array";

	default:
		hard_assert (!"invalid config item type value");
		return NULL;
	}
}

static bool
config_item_type_is_string (enum config_item_type type)
{
	return type == CONFIG_ITEM_STRING
		|| type == CONFIG_ITEM_STRING_ARRAY;
}

static void
config_item_free (struct config_item_ *self)
{
	switch (self->type)
	{
	case CONFIG_ITEM_STRING:
	case CONFIG_ITEM_STRING_ARRAY:
		str_free (&self->value.string);
		break;
	case CONFIG_ITEM_OBJECT:
		str_map_free (&self->value.object);
	default:
		break;
	}
}

static void
config_item_destroy (struct config_item_ *self)
{
	if (self->schema && self->schema->on_destroy)
		self->schema->on_destroy (self);

	config_item_free (self);
	free (self);
}

/// Doesn't do any validations or handle schemas, just moves source data
/// to the target item and destroys the source item
static void
config_item_move (struct config_item_ *self, struct config_item_ *source)
{
	// Not quite sure how to handle that
	hard_assert (!source->schema);

	config_item_free (self);
	self->type = source->type;
	memcpy (&self->value, &source->value, sizeof source->value);
	free (source);
}

static struct config_item_ *
config_item_new (enum config_item_type type)
{
	struct config_item_ *self = xcalloc (1, sizeof *self);
	self->type = type;
	return self;
}

static struct config_item_ *
config_item_null (void)
{
	return config_item_new (CONFIG_ITEM_NULL);
}

static struct config_item_ *
config_item_boolean (bool b)
{
	struct config_item_ *self = config_item_new (CONFIG_ITEM_BOOLEAN);
	self->value.boolean = b;
	return self;
}

static struct config_item_ *
config_item_integer (int64_t i)
{
	struct config_item_ *self = config_item_new (CONFIG_ITEM_INTEGER);
	self->value.integer = i;
	return self;
}

static struct config_item_ *
config_item_string (const struct str *s)
{
	struct config_item_ *self = config_item_new (CONFIG_ITEM_STRING);
	str_init (&self->value.string);
	if (s) str_append_str (&self->value.string, s);
	return self;
}

static struct config_item_ *
config_item_string_array (const struct str *s)
{
	struct config_item_ *self = config_item_string (s);
	self->type = CONFIG_ITEM_STRING_ARRAY;
	return self;
}

static struct config_item_ *
config_item_object (void)
{
	struct config_item_ *self = config_item_new (CONFIG_ITEM_BOOLEAN);
	str_map_init (&self->value.object);
	self->value.object.free = (void (*)(void *)) config_item_destroy;
	return self;
}

static bool
config_schema_accepts_type
	(struct config_schema *self, enum config_item_type type)
{
	if (self->type == type)
		return true;
	// This is a bit messy but it has its purpose
	if (config_item_type_is_string (self->type)
	 && config_item_type_is_string (type))
		return true;
	return !self->default_ && type == CONFIG_ITEM_NULL;

}

static bool
config_item_set_from (struct config_item_ *self, struct config_item_ *source,
	struct error **e)
{
	struct config_schema *schema = self->schema;
	if (!schema)
	{
		// Easy, we don't know what this item is
		config_item_move (self, source);
		return true;
	}

	// Otherwise we check the type and validate the item
	if (!config_schema_accepts_type (schema, source->type))
	{
		error_set (e, "invalid type of value, expected: %s%s",
			config_item_type_name (schema->type),
			!schema->default_ ? " (or null)" : "");
		return false;
	}

	if (schema->validate && !schema->validate (self, source))
	{
		// XXX: perhaps "schema->validate" could provide a message for us?
		error_set (e, "invalid value");
		return false;
	}

	// Make sure the string subtype fits the schema
	if (config_item_type_is_string (self->type)
	 && config_item_type_is_string (source->type))
		source->type = self->type;

	config_item_move (self, source);

	// Notify owner about the change so that they can apply it
	if (schema->on_changed)
		schema->on_changed (self);
	return true;
}

static struct config_item_ *
config_item_get (struct config_item_ *self, const char *path, struct error **e)
{
	hard_assert (self->type == CONFIG_ITEM_OBJECT);

	struct str_vector v;
	str_vector_init (&v);
	split_str (path, '.', &v);

	struct config_item_ *result = NULL;
	size_t i = 0;
	while (true)
	{
		const char *key = v.vector[i];
		if (!*key)
			error_set (e, "empty path element");
		else if (!(self = str_map_find (&self->value.object, key)))
			error_set (e, "`%s' not found in object", key);
		else if (++i == v.len)
			result = self;
		else if (self->type != CONFIG_ITEM_OBJECT)
			error_set (e, "`%s' is not an object", key);
		else
			continue;
		break;
	}
	str_vector_free (&v);
	return result;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct config_writer
{
	struct str *output;
	unsigned indent;
};

static void config_item_write_object_innards
	(struct config_writer *self, struct config_item_ *object);

static void
config_item_write_value (struct config_writer *self, struct config_item_ *value)
{
	switch (value->type)
	{
	case CONFIG_ITEM_NULL:
		str_append (self->output, "null");
		break;
	case CONFIG_ITEM_BOOLEAN:
		str_append (self->output, value->value.boolean ? "on" : "off");
		break;
	case CONFIG_ITEM_INTEGER:
		str_append_printf (self->output, "%" PRIi64, value->value.integer);
		break;
	case CONFIG_ITEM_STRING:
	case CONFIG_ITEM_STRING_ARRAY:
		// TODO
		break;
	case CONFIG_ITEM_OBJECT:
	{
		char indent[self->indent + 1];
		memset (indent, '\t', self->indent);
		indent[self->indent] = 0;

		str_append (self->output, "{\n");

		self->indent++;
		config_item_write_object_innards (self, value);
		self->indent--;

		str_append_printf (self->output, "%s}", indent);
		break;
	}
	default:
		hard_assert (!"invalid item type");
	}
}

static void
config_item_write_kv_pair (struct config_writer *self,
	const char *key, struct config_item_ *value)
{
	char indent[self->indent + 1];
	memset (indent, '\t', self->indent);
	indent[self->indent] = 0;

	if (value->schema && value->schema->comment)
		str_append_printf (self->output,
			"%s# %s\n", indent, value->schema->comment);

	str_append_printf (self->output, "%s%s = ", indent, key);
	config_item_write_value (self, value);
	str_append_c (self->output, '\n');
}

static void
config_item_write_object_innards
	(struct config_writer *self, struct config_item_ *object)
{
	hard_assert (object->type == CONFIG_ITEM_OBJECT);

	struct str_map_iter iter;
	str_map_iter_init (&iter, &object->value.object);

	struct config_item_ *value;
	while ((value = str_map_iter_next (&iter)))
		config_item_write_kv_pair (self, iter.link->key, value);
}

static void
config_item_write (struct config_item_ *value,
	bool object_innards, struct str *output)
{
	struct config_writer writer = { .output = output, .indent = 0 };
	if (object_innards)
		config_item_write_object_innards (&writer, value);
	else
		config_item_write_value (&writer, value);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
config_schema_apply_to_object
	(struct config_schema *schema_array, struct config_item_ *object)
{
	hard_assert (object->type == CONFIG_ITEM_OBJECT);
	// TODO
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

enum config_token
{
	CONFIG_T_ABORT,                     ///< EOF or error

	CONFIG_T_WORD,                      ///< [a-zA-Z0-9_]+
	CONFIG_T_EQUALS,                    ///< Equal sign
	CONFIG_T_LBRACE,                    ///< Left curly bracket
	CONFIG_T_RBRACE,                    ///< Right curly bracket
	CONFIG_T_NEWLINE,                   ///< New line

	CONFIG_T_NULL,                      ///< CONFIG_ITEM_NULL
	CONFIG_T_BOOLEAN,                   ///< CONFIG_ITEM_BOOLEAN
	CONFIG_T_INTEGER,                   ///< CONFIG_ITEM_INTEGER
	CONFIG_T_STRING                     ///< CONFIG_ITEM_STRING{,_LIST}
};

static const char *
config_token_name (enum config_token token)
{
	switch (token)
	{
	case CONFIG_T_ABORT:    return "end of input";

	case CONFIG_T_WORD:     return "word";
	case CONFIG_T_EQUALS:   return "equal sign";
	case CONFIG_T_LBRACE:   return "left brace";
	case CONFIG_T_RBRACE:   return "right brace";
	case CONFIG_T_NEWLINE:  return "newline";

	case CONFIG_T_NULL:     return "null value";
	case CONFIG_T_BOOLEAN:  return "boolean";
	case CONFIG_T_INTEGER:  return "integer";
	case CONFIG_T_STRING:   return "string";

	default:
		hard_assert (!"invalid token value");
	}
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct config_tokenizer
{
	const char *p;                      ///< Current position in input
	size_t len;                         ///< How many bytes of input are left

	bool report_line;                   ///< Whether to count lines at all
	unsigned line;                      ///< Current line
	unsigned column;                    ///< Current column

	int64_t integer;                    ///< Parsed boolean or integer value
	struct str string;                  ///< Parsed string value
};

/// Input has to be null-terminated anyway
static void
config_tokenizer_init (struct config_tokenizer *self, const char *p, size_t len)
{
	memset (self, 0, sizeof *self);
	self->p = p;
	self->len = len;
	self->report_line = true;
	str_init (&self->string);
}

static void
config_tokenizer_free (struct config_tokenizer *self)
{
	str_free (&self->string);
}

static bool
config_tokenizer_is_word_char (int c)
{
	return isalnum_ascii (c) || c == '_';
}

static int
config_tokenizer_advance (struct config_tokenizer *self)
{
	int c = *self->p++;
	if (c == '\n' && self->report_line)
	{
		self->column = 0;
		self->line++;
	}
	else
		self->column++;

	self->len--;
	return c;
}

static void config_tokenizer_error (struct config_tokenizer *self,
	struct error **e, const char *format, ...) ATTRIBUTE_PRINTF (3, 4);

static void
config_tokenizer_error (struct config_tokenizer *self,
	struct error **e, const char *format, ...)
{
	struct str description;
	str_init (&description);

	va_list ap;
	va_start (ap, format);
	str_append_vprintf (&description, format, ap);
	va_end (ap);

	if (self->report_line)
		error_set (e, "near line %u, column %u: %s",
			self->line + 1, self->column + 1, description.str);
	else
		error_set (e, "near character %u: %s",
			self->column + 1, description.str);

	str_free (&description);
}

static enum config_token
config_tokenizer_next (struct config_tokenizer *self, struct error **e)
{
	// Skip over any whitespace between tokens
	while (self->len && isspace_ascii (*self->p) && *self->p != '\n')
		config_tokenizer_advance (self);
	if (!self->len)
		return CONFIG_T_ABORT;

	switch (*self->p)
	{
	case '\n':  config_tokenizer_advance (self);  return CONFIG_T_NEWLINE;
	case '=':   config_tokenizer_advance (self);  return CONFIG_T_EQUALS;
	case '{':   config_tokenizer_advance (self);  return CONFIG_T_LBRACE;
	case '}':   config_tokenizer_advance (self);  return CONFIG_T_RBRACE;

	case '#':
		// Comments go until newline
		while (self->len)
			if (config_tokenizer_advance (self) == '\n')
				return CONFIG_T_NEWLINE;
		return CONFIG_T_ABORT;

	case '"':
		// TODO: string, validate as UTF-8
		break;
	}

	bool is_word = false;
	while (config_tokenizer_is_word_char (*self->p))
	{
		is_word = true;
		str_reset (&self->string);
		str_append_c (&self->string, config_tokenizer_advance (self));
	}
	if (is_word)
	{
		if (!strcmp (self->string.str, "null"))
			return CONFIG_T_NULL;

		bool boolean;
		if (!set_boolean_if_valid (&boolean, self->string.str))
			return CONFIG_T_WORD;

		self->integer = boolean;
		return CONFIG_T_BOOLEAN;
	}

	char *end;
	errno = 0;
	self->integer = strtoll (self->p, &end, 10);
	if (errno == ERANGE)
	{
		config_tokenizer_error (self, e, "integer out of range");
		return CONFIG_T_ABORT;
	}
	if (end != self->p)
	{
		self->len -= end - self->p;
		self->p = end;
		return CONFIG_T_INTEGER;
	}

	config_tokenizer_error (self, e, "invalid input");
	return CONFIG_T_ABORT;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct config_parser
{
	struct config_tokenizer tokenizer;  ///< Tokenizer

	struct error *error;                ///< Tokenizer error
	enum config_token token;            ///< Current token in the tokenizer
	bool replace_token;                 ///< Replace the token
};

static void
config_parser_init (struct config_parser *self, const char *script, size_t len)
{
	memset (self, 0, sizeof *self);
	config_tokenizer_init (&self->tokenizer, script, len);

	// As reading in tokens may cause exceptions, we wait for the first peek()
	// to replace the initial CONFIG_T_ABORT.
	self->replace_token = true;
}

static void
config_parser_free (struct config_parser *self)
{
	config_tokenizer_free (&self->tokenizer);
	if (self->error)
		error_free (self->error);
}

static enum config_token
config_parser_peek (struct config_parser *self, jmp_buf out)
{
	if (self->replace_token)
	{
		self->token = config_tokenizer_next (&self->tokenizer, &self->error);
		if (self->error)
			longjmp (out, 1);
		self->replace_token = false;
	}
	return self->token;
}

static bool
config_parser_accept
	(struct config_parser *self, enum config_token token, jmp_buf out)
{
	return self->replace_token = (config_parser_peek (self, out) == token);
}

static void
config_parser_expect
	(struct config_parser *self, enum config_token token, jmp_buf out)
{
	if (config_parser_accept (self, token, out))
		return;

	config_tokenizer_error (&self->tokenizer, &self->error,
		"unexpected `%s', expected `%s'",
		config_token_name (self->token),
		config_token_name (token));
	longjmp (out, 1);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// We don't need no generator, but a few macros will come in handy.
// From time to time C just doesn't have the right features.

#define PEEK()         config_parser_peek   (self, err)
#define ACCEPT(token)  config_parser_accept (self, token, err)
#define EXPECT(token)  config_parser_expect (self, token, err)
#define SKIP_NL()      do {} while (ACCEPT (CONFIG_T_NEWLINE))

static struct config_item_ *config_parser_parse_object
	(struct config_parser *self, jmp_buf out);

static struct config_item_ *
config_parser_parse_value (struct config_parser *self, jmp_buf out)
{
	struct config_item_ *volatile result = NULL;
	jmp_buf err;

	if (setjmp (err))
	{
		if (result)
			config_item_destroy (result);
		longjmp (out, 1);
	}

	if (ACCEPT (CONFIG_T_LBRACE))
	{
		result = config_parser_parse_object (self, out);
		SKIP_NL ();
		EXPECT (CONFIG_T_RBRACE);
		return result;
	}
	if (ACCEPT (CONFIG_T_NULL))
		return config_item_null ();
	if (ACCEPT (CONFIG_T_BOOLEAN))
		return config_item_boolean (self->tokenizer.integer);
	if (ACCEPT (CONFIG_T_INTEGER))
		return config_item_integer (self->tokenizer.integer);
	if (ACCEPT (CONFIG_T_STRING))
		return config_item_string (&self->tokenizer.string);

	config_tokenizer_error (&self->tokenizer, &self->error,
		"unexpected `%s', expected a value",
		config_token_name (self->token));
	longjmp (out, 1);
}

/// Parse a single "key = value" assignment into @a object
static bool
config_parser_parse_kv_pair (struct config_parser *self,
	struct config_item_ *object, jmp_buf out)
{
	char *volatile key = NULL;
	jmp_buf err;

	if (setjmp (err))
	{
		free (key);
		longjmp (out, 1);
	}

	SKIP_NL ();

	// Either this object's closing right brace if called recursively,
	// or end of file when called on a whole configuration file
	if (PEEK () == CONFIG_T_RBRACE
	 || PEEK () == CONFIG_T_ABORT)
		return false;

	EXPECT (CONFIG_T_WORD);
	key = xstrdup (self->tokenizer.string.str);
	SKIP_NL ();

	EXPECT (CONFIG_T_EQUALS);
	SKIP_NL ();

	str_map_set (&object->value.object, key,
		config_parser_parse_value (self, err));

	free (key);
	key = NULL;

	if (PEEK () == CONFIG_T_RBRACE
	 || PEEK () == CONFIG_T_ABORT)
		return false;

	EXPECT (CONFIG_T_NEWLINE);
	return true;
}

/// Parse the inside of an object definition
static struct config_item_ *
config_parser_parse_object (struct config_parser *self, jmp_buf out)
{
	struct config_item_ *volatile object = config_item_object ();
	jmp_buf err;

	if (setjmp (err))
	{
		config_item_destroy (object);
		longjmp (out, 1);
	}

	while (config_parser_parse_kv_pair (self, object, err))
		;
	return object;
}

#undef PEEK
#undef ACCEPT
#undef EXPECT
#undef SKIP_NL

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

/// Parse a configuration snippet either as an object or a bare value.
/// If it's the latter (@a single_value_only), no newlines may follow.
static struct config_item_ *
config_item_parse (const char *script, size_t len,
	bool single_value_only, struct error **e)
{
	struct config_parser parser;
	config_parser_init (&parser, script, len);

	struct config_item_ *volatile object = NULL;
	jmp_buf err;

	if (setjmp (err))
	{
		if (object)
		{
			config_item_destroy (object);
			object = NULL;
		}

		error_propagate (e, parser.error);
		parser.error = NULL;
		goto end;
	}

	if (single_value_only)
	{
		// This is really only intended for in-program configuration
		// and telling the line number would look awkward
		parser.tokenizer.report_line = false;
		object = config_parser_parse_value (&parser, err);
	}
	else
		object = config_parser_parse_object (&parser, err);
	config_parser_expect (&parser, CONFIG_T_ABORT, err);
end:
	config_parser_free (&parser);
	return object;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

typedef void (*config_module_load_fn)
	(struct config_item_ *subtree, void *user_data);

struct config_module
{
	char *name;                         ///< Name of the subtree
	config_module_load_fn loader;       ///< Module config subtree loader
	void *user_data;                    ///< User data
};

struct config
{
	struct str_map modules;             ///< Toplevel modules
	struct config_item_ *root;          ///< CONFIG_ITEM_OBJECT
};

static void
config_init (struct config *self)
{
	// TODO
}

static void
config_free (struct config *self)
{
	// TODO
}

static bool
config_register_module (const char *name,
	config_module_load_fn loader, void *user_data)
{
	// TODO
}

static bool
config_load (struct config_item_ *root, struct error **e)
{
	// TODO
}