summaryrefslogtreecommitdiff
path: root/common.c
blob: 951055cc59c1fd910dc3202f365b5a53c018342e (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
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
/*
 * 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))

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

#define LIST_INSERT_WITH_TAIL(head, tail, link, following)                     \
	BLOCK_START                                                                \
		if (following)                                                         \
			LIST_APPEND_WITH_TAIL ((head), (following)->prev, (link));         \
		else                                                                   \
			LIST_APPEND_WITH_TAIL ((head), (tail), (link));                    \
		(link)->next = (following);                                            \
	BLOCK_END

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);
}

static ssize_t
str_vector_find (const struct str_vector *v, const char *s)
{
	for (size_t i = 0; i < v->len; i++)
		if (!strcmp (v->vector[i], s))
			return i;
	return -1;
}

static int
strncasecmp_ascii (const char *a, const char *b, size_t n)
{
	int x;
	while (n-- && (*a || *b))
		if ((x = tolower_ascii (*(const unsigned char *) a++)
			- tolower_ascii (*(const unsigned char *) b++)))
			return x;
	return 0;
}

static char *
resolve_relative_runtime_filename (const char *filename)
{
	struct str path;
	str_init (&path);

	const char *runtime_dir = getenv ("XDG_RUNTIME_DIR");
	if (runtime_dir && *runtime_dir == '/')
		str_append (&path, runtime_dir);
	else
		get_xdg_home_dir (&path, "XDG_DATA_HOME", ".local/share");
	str_append_printf (&path, "/%s/%s", PROGRAM_NAME, filename);

	// Try to create the file's ancestors
	const char *last_slash = strrchr (path.str, '/');
	if (last_slash && last_slash != path.str)
	{
		char *copy = xstrndup (path.str, last_slash - path.str);
		(void) mkdir_with_parents (copy, NULL);
		free (copy);
	}
	return str_steal (&path);
}

static char *
resolve_filename (const char *filename, char *(*relative_cb) (const char *))
{
	// Absolute path is absolute
	if (*filename == '/')
		return xstrdup (filename);

	// We don't want to use wordexp() for this as it may execute /bin/sh
	if (*filename == '~')
	{
		// Paths to home directories ought to be absolute
		char *expanded = try_expand_tilde (filename + 1);
		if (expanded)
			return expanded;
		print_debug ("failed to expand the home directory in `%s'", filename);
	}
	return relative_cb (filename);
}

// --- 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);
}

// --- Connector ---------------------------------------------------------------

// This is a helper that tries to establish a connection with any address on
// a given list.  Sadly it also introduces a bit of a callback hell.

struct connector_target
{
	LIST_HEADER (struct connector_target)

	char *hostname;                     ///< Target hostname or address
	char *service;                      ///< Target service name or port

	struct addrinfo *results;           ///< Resolved target
	struct addrinfo *iter;              ///< Current endpoint
};

static struct connector_target *
connector_target_new (void)
{
	struct connector_target *self = xmalloc (sizeof *self);
	return self;
}

static void
connector_target_destroy (struct connector_target *self)
{
	free (self->hostname);
	free (self->service);
	freeaddrinfo (self->results);
	free (self);
}

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

struct connector
{
	int socket;                         ///< Socket FD for the connection
	struct poller_fd connected_event;   ///< We've connected or failed
	struct connector_target *targets;   ///< Targets
	struct connector_target *targets_t; ///< Tail of targets

	void *user_data;                    ///< User data for callbacks

	// You may destroy the connector object in these two main callbacks:

	/// Connection has been successfully established
	void (*on_connected) (void *user_data, int socket);
	/// Failed to establish a connection to either target
	void (*on_failure) (void *user_data);

	// Optional:

	/// Connecting to a new address
	void (*on_connecting) (void *user_data, const char *address);
	/// Connecting to the last address has failed
	void (*on_error) (void *user_data, const char *error);
};

static void
connector_notify_connecting (struct connector *self,
	struct connector_target *target, struct addrinfo *gai_iter)
{
	if (!self->on_connecting)
		return;

	const char *real_host = target->hostname;

	// We don't really need this, so we can let it quietly fail
	char buf[NI_MAXHOST];
	int err = getnameinfo (gai_iter->ai_addr, gai_iter->ai_addrlen,
		buf, sizeof buf, NULL, 0, NI_NUMERICHOST);
	if (err)
		LOG_FUNC_FAILURE ("getnameinfo", gai_strerror (err));
	else
		real_host = buf;

	char *address = format_host_port_pair (real_host, target->service);
	self->on_connecting (self->user_data, address);
	free (address);
}

static void
connector_notify_error (struct connector *self, const char *error)
{
	if (self->on_error)
		self->on_error (self->user_data, error);
}

static void
connector_prepare_next (struct connector *self)
{
	struct connector_target *target = self->targets;
	if (!(target->iter = target->iter->ai_next))
	{
		LIST_UNLINK_WITH_TAIL (self->targets, self->targets_t, target);
		connector_target_destroy (target);
	}
}

static void
connector_step (struct connector *self)
{
	struct connector_target *target = self->targets;
	if (!target)
	{
		// Total failure, none of the targets has succeeded
		self->on_failure (self->user_data);
		return;
	}

	struct addrinfo *gai_iter = target->iter;
	hard_assert (gai_iter != NULL);

	connector_notify_connecting (self, target, gai_iter);

	int fd = self->socket = socket (gai_iter->ai_family,
		gai_iter->ai_socktype, gai_iter->ai_protocol);
	if (fd == -1)
	{
		connector_notify_error (self, strerror (errno));

		connector_prepare_next (self);
		connector_step (self);
		return;
	}

	set_cloexec (fd);
	set_blocking (fd, false);

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

	if (!connect (fd, gai_iter->ai_addr, gai_iter->ai_addrlen))
	{
		set_blocking (fd, true);
		self->on_connected (self->user_data, fd);
		return;
	}
	else if (errno != EINPROGRESS)
	{
		connector_notify_error (self, strerror (errno));
		xclose (fd);

		connector_prepare_next (self);
		connector_step (self);
		return;
	}

	self->connected_event.fd = self->socket = fd;
	poller_fd_set (&self->connected_event, POLLOUT);

	connector_prepare_next (self);
}

static void
connector_on_ready (const struct pollfd *pfd, struct connector *self)
{
	// See http://cr.yp.to/docs/connect.html if this doesn't work.
	// The second connect() method doesn't work with DragonflyBSD.

	int error = 0;
	socklen_t error_len = sizeof error;
	hard_assert (!getsockopt (pfd->fd,
		SOL_SOCKET, SO_ERROR, &error, &error_len));

	if (error)
	{
		connector_notify_error (self, strerror (error));

		poller_fd_reset (&self->connected_event);
		xclose (self->socket);
		self->socket = -1;

		connector_step (self);
	}
	else
	{
		poller_fd_reset (&self->connected_event);
		self->socket = -1;

		set_blocking (pfd->fd, true);
		self->on_connected (self->user_data, pfd->fd);
	}
}

static void
connector_init (struct connector *self, struct poller *poller)
{
	memset (self, 0, sizeof *self);
	self->socket = -1;
	poller_fd_init (&self->connected_event, poller, self->socket);
	self->connected_event.user_data = self;
	self->connected_event.dispatcher = (poller_fd_fn) connector_on_ready;
}

static void
connector_free (struct connector *self)
{
	poller_fd_reset (&self->connected_event);
	if (self->socket != -1)
		xclose (self->socket);

	LIST_FOR_EACH (struct connector_target, iter, self->targets)
		connector_target_destroy (iter);
}

static bool
connector_add_target (struct connector *self,
	const char *hostname, const char *service, struct error **e)
{
	struct addrinfo hints, *results;
	memset (&hints, 0, sizeof hints);
	hints.ai_socktype = SOCK_STREAM;

	// TODO: even this should be done asynchronously, most likely in
	//   a thread pool, similarly to how libuv does it
	int err = getaddrinfo (hostname, service, &hints, &results);
	if (err)
	{
		error_set (e, "%s: %s", "getaddrinfo", gai_strerror (err));
		return false;
	}

	struct connector_target *target = connector_target_new ();
	target->hostname = xstrdup (hostname);
	target->service = xstrdup (service);
	target->results = results;
	target->iter = target->results;

	LIST_APPEND_WITH_TAIL (self->targets, self->targets_t, target);
	return true;
}

// --- 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;
}

// --- CTCP decoding -----------------------------------------------------------

#define CTCP_M_QUOTE '\020'
#define CTCP_X_DELIM '\001'
#define CTCP_X_QUOTE '\\'

struct ctcp_chunk
{
	LIST_HEADER (struct ctcp_chunk)

	bool is_extended;                   ///< Is this a tagged extended message?
	struct str tag;                     ///< The tag, if any
	struct str text;                    ///< Message contents
};

static struct ctcp_chunk *
ctcp_chunk_new (void)
{
	struct ctcp_chunk *self = xcalloc (1, sizeof *self);
	str_init (&self->tag);
	str_init (&self->text);
	return self;
}

static void
ctcp_chunk_destroy (struct ctcp_chunk *self)
{
	str_free (&self->tag);
	str_free (&self->text);
	free (self);
}

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

static void
ctcp_low_level_decode (const char *message, struct str *output)
{
	bool escape = false;
	for (const char *p = message; *p; p++)
	{
		if (escape)
		{
			switch (*p)
			{
			case '0': str_append_c (output, '\0'); break;
			case 'r': str_append_c (output, '\r'); break;
			case 'n': str_append_c (output, '\n'); break;
			default:  str_append_c (output, *p);
			}
			escape = false;
		}
		else if (*p == CTCP_M_QUOTE)
			escape = true;
		else
			str_append_c (output, *p);
	}
}

static void
ctcp_intra_decode (const char *chunk, size_t len, struct str *output)
{
	bool escape = false;
	for (size_t i = 0; i < len; i++)
	{
		char c = chunk[i];
		if (escape)
		{
			if (c == 'a')
				str_append_c (output, CTCP_X_DELIM);
			else
				str_append_c (output, c);
			escape = false;
		}
		else if (c == CTCP_X_QUOTE)
			escape = true;
		else
			str_append_c (output, c);
	}
}

static void
ctcp_parse_tagged (const char *chunk, size_t len, struct ctcp_chunk *output)
{
	// We may search for the space before doing the higher level decoding,
	// as it doesn't concern space characters at all
	size_t tag_end = len;
	for (size_t i = 0; i < len; i++)
		if (chunk[i] == ' ')
		{
			tag_end = i;
			break;
		}

	output->is_extended = true;
	ctcp_intra_decode (chunk, tag_end, &output->tag);
	if (tag_end++ != len)
		ctcp_intra_decode (chunk + tag_end, len - tag_end, &output->text);
}

static struct ctcp_chunk *
ctcp_parse (const char *message)
{
	struct str m;
	str_init (&m);
	ctcp_low_level_decode (message, &m);

	struct ctcp_chunk *result = NULL, *result_tail = NULL;

	size_t start = 0;
	bool in_ctcp = false;
	for (size_t i = 0; i < m.len; i++)
	{
		char c = m.str[i];
		if (c != CTCP_X_DELIM)
			continue;

		// Remember the current state
		size_t my_start = start;
		bool my_is_ctcp = in_ctcp;

		start = i + 1;
		in_ctcp = !in_ctcp;

		// Skip empty chunks
		if (my_start == i)
			continue;

		struct ctcp_chunk *chunk = ctcp_chunk_new ();
		if (my_is_ctcp)
			ctcp_parse_tagged (m.str + my_start, i - my_start, chunk);
		else
			str_append_data (&chunk->text, m.str + my_start, i - my_start);
		LIST_APPEND_WITH_TAIL (result, result_tail, chunk);
	}

	// Finish the last text part.  We ignore unended tagged chunks.
	// TODO: don't ignore them, e.g. a /me may get cut off
	if (!in_ctcp && start != m.len)
	{
		struct ctcp_chunk *chunk = ctcp_chunk_new ();
		// According to the original CTCP specification we should use
		// ctcp_intra_decode() but no one seems to use that and it breaks
		// normal text with backslashes
		str_append_data (&chunk->text, m.str + start, m.len - start);
		LIST_APPEND_WITH_TAIL (result, result_tail, chunk);
	}

	str_free (&m);
	return result;
}

static void
ctcp_destroy (struct ctcp_chunk *list)
{
	LIST_FOR_EACH (struct ctcp_chunk, iter, list)
		ctcp_chunk_destroy (iter);
}

// --- 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.
	/// In addition to this, "type" and having a default is considered.
	bool (*validate) (const struct config_item_ *, struct error **e);

	/// The value has changed
	void (*on_change) (struct config_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)
{
	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);
	hard_assert (utf8_validate
		(self->value.string.str, self->value.string.len));
	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_OBJECT);
	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_validate_by_schema (struct config_item_ *self,
	struct config_schema *schema, struct error **e)
{
	struct error *error = NULL;
	if (!config_schema_accepts_type (schema, self->type))
		error_set (e, "invalid type of value, expected: %s%s",
			config_item_type_name (schema->type),
			!schema->default_ ? " (or null)" : "");
	else if (schema->validate && !schema->validate (self, &error))
	{
		error_set (e, "%s: %s", "invalid value", error->message);
		error_free (error);
	}
	else
		return true;
	return false;
}

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;
	}

	if (!config_item_validate_by_schema (source, schema, e))
		return false;

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

	config_item_move (self, source);

	// Notify owner about the change so that they can apply it
	if (schema->on_change)
		schema->on_change (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_string (struct str *output, const struct str *s)
{
	str_append_c (output, '"');
	for (size_t i = 0; i < s->len; i++)
	{
		unsigned char c = s->str[i];
		if      (c == '\n')  str_append        (output, "\\n");
		else if (c == '\r')  str_append        (output, "\\r");
		else if (c == '\t')  str_append        (output, "\\t");
		else if (c == '\\')  str_append        (output, "\\\\");
		else if (c == '"')   str_append        (output, "\\\"");
		else if (c < 32)     str_append_printf (output, "\\x%02x", c);
		else                 str_append_c      (output, c);
	}
	str_append_c (output, '"');
}

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:
		config_item_write_string (self->output, &value->value.string);
		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);
}

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

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");
		return NULL;
	}
}

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

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

	str_free (&description);
}

static bool
config_tokenizer_hexa_escape (struct config_tokenizer *self, struct str *output)
{
	int i;
	unsigned char code = 0;

	for (i = 0; self->len && i < 2; i++)
	{
		unsigned char c = tolower_ascii (*self->p);
		if (c >= '0' && c <= '9')
			code = (code << 4) | (c - '0');
		else if (c >= 'a' && c <= 'f')
			code = (code << 4) | (c - 'a' + 10);
		else
			break;

		config_tokenizer_advance (self);
	}

	if (!i)
		return false;

	str_append_c (output, code);
	return true;
}

static bool
config_tokenizer_octal_escape
	(struct config_tokenizer *self, struct str *output)
{
	int i;
	unsigned char code = 0;

	for (i = 0; self->len && i < 3; i++)
	{
		unsigned char c = *self->p;
		if (c >= '0' && c <= '7')
			code = (code << 3) | (c - '0');
		else
			break;

		config_tokenizer_advance (self);
	}

	if (!i)
		return false;

	str_append_c (output, code);
	return true;
}

static bool
config_tokenizer_escape_sequence
	(struct config_tokenizer *self, struct str *output, struct error **e)
{
	if (!self->len)
	{
		config_tokenizer_error (self, e, "premature end of escape sequence");
		return false;
	}

	unsigned char c;
	switch ((c = *self->p))
	{
	case '"':              break;
	case '\\':             break;
	case 'a':   c = '\a';  break;
	case 'b':   c = '\b';  break;
	case 'f':   c = '\f';  break;
	case 'n':   c = '\n';  break;
	case 'r':   c = '\r';  break;
	case 't':   c = '\t';  break;
	case 'v':   c = '\v';  break;

	case 'x':
	case 'X':
		config_tokenizer_advance (self);
		if (config_tokenizer_hexa_escape (self, output))
			return true;

		config_tokenizer_error (self, e, "invalid hexadecimal escape");
		return false;

	default:
		if (config_tokenizer_octal_escape (self, output))
			return true;

		config_tokenizer_error (self, e, "unknown escape sequence");
		return false;
	}

	str_append_c (output, c);
	config_tokenizer_advance (self);
	return true;
}

static bool
config_tokenizer_string
	(struct config_tokenizer *self, struct str *output, struct error **e)
{
	unsigned char c;
	while (self->len)
	{
		if ((c = config_tokenizer_advance (self)) == '"')
			return true;
		if (c != '\\')
			str_append_c (output, c);
		else if (!config_tokenizer_escape_sequence (self, output, e))
			return false;
	}
	config_tokenizer_error (self, e, "premature end of string");
	return false;
}

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 '"':
		config_tokenizer_advance (self);
		str_reset (&self->string);
		if (!config_tokenizer_string (self, &self->string, e))
			return CONFIG_T_ABORT;
		if (!utf8_validate (self->string.str, self->string.len))
		{
			config_tokenizer_error (self, e, "not a valid UTF-8 string");
			return CONFIG_T_ABORT;
		}
		return CONFIG_T_STRING;
	}

	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;
	}

	if (!config_tokenizer_is_word_char (*self->p))
	{
		config_tokenizer_error (self, e, "invalid input");
		return CONFIG_T_ABORT;
	}

	str_reset (&self->string);
	do
		str_append_c (&self->string, config_tokenizer_advance (self));
	while (config_tokenizer_is_word_char (*self->p));

	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;
}

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

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;
}

/// Clone an item.  Schema assignments aren't retained.
struct config_item_ *
config_item_clone (struct config_item_ *self)
{
	// Oh well, it saves code
	struct str tmp;
	str_init (&tmp);
	config_item_write (self, false, &tmp);
	struct config_item_ *result =
		config_item_parse (tmp.str, tmp.len, true, NULL);
	str_free (&tmp);
	return result;
}

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

// TODO: maybe also make it possible to assign the "user_data" pointer

static void
config_schema_fix_value
	(struct config_schema *schema, struct config_item_ *object)
{
	struct config_item_ *item =
		str_map_find (&object->value.object, schema->name);

	bool replace = true;
	if (item)
	{
		// FIXME: either do this silently or tell about it via a callback
		//   or just store it in an output vector; don't print it directly
		struct error *e = NULL;
		replace = !config_item_validate_by_schema (item, schema, &e);
		if (e)
		{
			print_error ("resetting configuration item "
				"`%s' to default: %s", schema->name, e->message);
			error_free (e);
		}
	}

	if (replace)
	{
		struct error *e = NULL;
		if (schema->default_)
			item = config_item_parse
				(schema->default_, strlen (schema->default_), true, &e);
		else
			item = config_item_null ();

		if (e || !config_item_validate_by_schema (item, schema, &e))
			exit_fatal ("invalid default for `%s': %s",
				schema->name, e->message);

		// This will free the old item if there was any
		str_map_set (&object->value.object, schema->name, item);
	}

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

	item->schema = schema;
	if (schema->on_change)
		schema->on_change (item);
}

static void
config_schema_apply_to_object
	(struct config_schema *schema_array, struct config_item_ *object)
{
	hard_assert (object->type == CONFIG_ITEM_OBJECT);
	while (schema_array->name)
		config_schema_fix_value (schema_array++, object);
}

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

// XXX: this doesn't necessarily have to be well designed at all

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
};

static struct config_module *
config_module_new ()
{
	struct config_module *self = xcalloc (1, sizeof *self);
	return self;
}

static void
config_module_destroy (struct config_module *self)
{
	free (self->name);
	free (self);
}

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

static void
config_init (struct config *self)
{
	memset (self, 0, sizeof *self);
	str_map_init (&self->modules);
	self->modules.free = (void (*) (void *)) config_module_destroy;
}

static void
config_free (struct config *self)
{
	str_map_free (&self->modules);
	if (self->root)
		config_item_destroy (self->root);
}

static void
config_register_module (struct config *self,
	const char *name, config_module_load_fn loader, void *user_data)
{
	struct config_module *module = config_module_new ();
	module->name = xstrdup (name);
	module->loader = loader;
	module->user_data = user_data;

	str_map_set (&self->modules, name, module);
}

static void
config_load (struct config *self, struct config_item_ *root)
{
	hard_assert (root->type == CONFIG_ITEM_OBJECT);
	self->root = root;

	struct str_map_iter iter;
	str_map_iter_init (&iter, &self->modules);

	struct config_module *module;
	while ((module = str_map_iter_next (&iter)))
	{
		struct config_item_ *subtree = str_map_find
			(&root->value.object, module->name);
		// Silently fix inputs that only a lunatic user could create
		if (!subtree || subtree->type != CONFIG_ITEM_OBJECT)
		{
			subtree = config_item_object ();
			str_map_set (&root->value.object, module->name, subtree);
		}
		module->loader (subtree, module->user_data);
	}
}