summaryrefslogtreecommitdiff
path: root/modules/caddyhttp/matchers.go
blob: f5f9a0f66ad0ac89afd3de4fd57d5deaced6b550 (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
// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package caddyhttp

import (
	"encoding/json"
	"errors"
	"fmt"
	"net"
	"net/http"
	"net/textproto"
	"net/url"
	"path"
	"reflect"
	"regexp"
	"sort"
	"strconv"
	"strings"

	"github.com/caddyserver/caddy/v2"
	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
	"github.com/google/cel-go/cel"
	"github.com/google/cel-go/common/types"
	"github.com/google/cel-go/common/types/ref"
)

type (
	// MatchHost matches requests by the Host value (case-insensitive).
	//
	// When used in a top-level HTTP route,
	// [qualifying domain names](/docs/automatic-https#hostname-requirements)
	// may trigger [automatic HTTPS](/docs/automatic-https), which automatically
	// provisions and renews certificates for you. Before doing this, you
	// should ensure that DNS records for these domains are properly configured,
	// especially A/AAAA pointed at your server.
	//
	// Automatic HTTPS can be
	// [customized or disabled](/docs/modules/http#servers/automatic_https).
	//
	// Wildcards (`*`) may be used to represent exactly one label of the
	// hostname, in accordance with RFC 1034 (because host matchers are also
	// used for automatic HTTPS which influences TLS certificates). Thus,
	// a host of `*` matches hosts like `localhost` or `internal` but not
	// `example.com`. To catch all hosts, omit the host matcher entirely.
	//
	// The wildcard can be useful for matching all subdomains, for example:
	// `*.example.com` matches `foo.example.com` but not `foo.bar.example.com`.
	//
	// Duplicate entries will return an error.
	MatchHost []string

	// MatchPath case-insensitively matches requests by the URI's path. Path
	// matching is exact, not prefix-based, giving you more control and clarity
	// over matching. Wildcards (`*`) may be used:
	//
	// - At the end only, for a prefix match (`/prefix/*`)
	// - At the beginning only, for a suffix match (`*.suffix`)
	// - On both sides only, for a substring match (`*/contains/*`)
	// - In the middle, for a globular match (`/accounts/*/info`)
	//
	// Slashes are significant; i.e. `/foo*` matches `/foo`, `/foo/`, `/foo/bar`,
	// and `/foobar`; but `/foo/*` does not match `/foo` or `/foobar`. Valid
	// paths start with a slash `/`.
	//
	// Because there are, in general, multiple possible escaped forms of any
	// path, path matchers operate in unescaped space; that is, path matchers
	// should be written in their unescaped form to prevent ambiguities and
	// possible security issues, as all request paths will be normalized to
	// their unescaped forms before matcher evaluation.
	//
	// However, escape sequences in a match pattern are supported; they are
	// compared with the request's raw/escaped path for those bytes only.
	// In other words, a matcher of `/foo%2Fbar` will match a request path
	// of precisely `/foo%2Fbar`, but not `/foo/bar`. It follows that matching
	// the literal percent sign (%) in normalized space can be done using the
	// escaped form, `%25`.
	//
	// Even though wildcards (`*`) operate in the normalized space, the special
	// escaped wildcard (`%*`), which is not a valid escape sequence, may be
	// used in place of a span that should NOT be decoded; that is, `/bands/%*`
	// will match `/bands/AC%2fDC` whereas `/bands/*` will not.
	//
	// Even though path matching is done in normalized space, the special
	// wildcard `%*` may be used in place of a span that should NOT be decoded;
	// that is, `/bands/%*/` will match `/bands/AC%2fDC/` whereas `/bands/*/`
	// will not.
	//
	// This matcher is fast, so it does not support regular expressions or
	// capture groups. For slower but more powerful matching, use the
	// path_regexp matcher. (Note that due to the special treatment of
	// escape sequences in matcher patterns, they may perform slightly slower
	// in high-traffic environments.)
	MatchPath []string

	// MatchPathRE matches requests by a regular expression on the URI's path.
	// Path matching is performed in the unescaped (decoded) form of the path.
	//
	// Upon a match, it adds placeholders to the request: `{http.regexp.name.capture_group}`
	// where `name` is the regular expression's name, and `capture_group` is either
	// the named or positional capture group from the expression itself. If no name
	// is given, then the placeholder omits the name: `{http.regexp.capture_group}`
	// (potentially leading to collisions).
	MatchPathRE struct{ MatchRegexp }

	// MatchMethod matches requests by the method.
	MatchMethod []string

	// MatchQuery matches requests by the URI's query string. It takes a JSON object
	// keyed by the query keys, with an array of string values to match for that key.
	// Query key matches are exact, but wildcards may be used for value matches. Both
	// keys and values may be placeholders.
	//
	// An example of the structure to match `?key=value&topic=api&query=something` is:
	//
	// ```json
	// {
	// 	"key": ["value"],
	//	"topic": ["api"],
	//	"query": ["*"]
	// }
	// ```
	//
	// Invalid query strings, including those with bad escapings or illegal characters
	// like semicolons, will fail to parse and thus fail to match.
	//
	// **NOTE:** Notice that query string values are arrays, not singular values. This is
	// because repeated keys are valid in query strings, and each one may have a
	// different value. This matcher will match for a key if any one of its configured
	// values is assigned in the query string. Backend applications relying on query
	// strings MUST take into consideration that query string values are arrays and can
	// have multiple values.
	MatchQuery url.Values

	// MatchHeader matches requests by header fields. The key is the field
	// name and the array is the list of field values. It performs fast,
	// exact string comparisons of the field values. Fast prefix, suffix,
	// and substring matches can also be done by suffixing, prefixing, or
	// surrounding the value with the wildcard `*` character, respectively.
	// If a list is null, the header must not exist. If the list is empty,
	// the field must simply exist, regardless of its value.
	//
	// **NOTE:** Notice that header values are arrays, not singular values. This is
	// because repeated fields are valid in headers, and each one may have a
	// different value. This matcher will match for a field if any one of its configured
	// values matches in the header. Backend applications relying on headers MUST take
	// into consideration that header field values are arrays and can have multiple
	// values.
	MatchHeader http.Header

	// MatchHeaderRE matches requests by a regular expression on header fields.
	//
	// Upon a match, it adds placeholders to the request: `{http.regexp.name.capture_group}`
	// where `name` is the regular expression's name, and `capture_group` is either
	// the named or positional capture group from the expression itself. If no name
	// is given, then the placeholder omits the name: `{http.regexp.capture_group}`
	// (potentially leading to collisions).
	MatchHeaderRE map[string]*MatchRegexp

	// MatchProtocol matches requests by protocol. Recognized values are
	// "http", "https", and "grpc" for broad protocol matches, or specific
	// HTTP versions can be specified like so: "http/1", "http/1.1",
	// "http/2", "http/3", or minimum versions: "http/2+", etc.
	MatchProtocol string

	// MatchNot matches requests by negating the results of its matcher
	// sets. A single "not" matcher takes one or more matcher sets. Each
	// matcher set is OR'ed; in other words, if any matcher set returns
	// true, the final result of the "not" matcher is false. Individual
	// matchers within a set work the same (i.e. different matchers in
	// the same set are AND'ed).
	//
	// NOTE: The generated docs which describe the structure of this
	// module are wrong because of how this type unmarshals JSON in a
	// custom way. The correct structure is:
	//
	// ```json
	// [
	// 	{},
	// 	{}
	// ]
	// ```
	//
	// where each of the array elements is a matcher set, i.e. an
	// object keyed by matcher name.
	MatchNot struct {
		MatcherSetsRaw []caddy.ModuleMap `json:"-" caddy:"namespace=http.matchers"`
		MatcherSets    []MatcherSet      `json:"-"`
	}
)

func init() {
	caddy.RegisterModule(MatchHost{})
	caddy.RegisterModule(MatchPath{})
	caddy.RegisterModule(MatchPathRE{})
	caddy.RegisterModule(MatchMethod{})
	caddy.RegisterModule(MatchQuery{})
	caddy.RegisterModule(MatchHeader{})
	caddy.RegisterModule(MatchHeaderRE{})
	caddy.RegisterModule(new(MatchProtocol))
	caddy.RegisterModule(MatchNot{})
}

// CaddyModule returns the Caddy module information.
func (MatchHost) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.host",
		New: func() caddy.Module { return new(MatchHost) },
	}
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchHost) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	for d.Next() {
		*m = append(*m, d.RemainingArgs()...)
		if d.NextBlock(0) {
			return d.Err("malformed host matcher: blocks are not supported")
		}
	}
	return nil
}

// Provision sets up and validates m, including making it more efficient for large lists.
func (m MatchHost) Provision(_ caddy.Context) error {
	// check for duplicates; they are nonsensical and reduce efficiency
	// (we could just remove them, but the user should know their config is erroneous)
	seen := make(map[string]int)
	for i, h := range m {
		h = strings.ToLower(h)
		if firstI, ok := seen[h]; ok {
			return fmt.Errorf("host at index %d is repeated at index %d: %s", firstI, i, h)
		}
		seen[h] = i
	}

	if m.large() {
		// sort the slice lexicographically, grouping "fuzzy" entries (wildcards and placeholders)
		// at the front of the list; this allows us to use binary search for exact matches, which
		// we have seen from experience is the most common kind of value in large lists; and any
		// other kinds of values (wildcards and placeholders) are grouped in front so the linear
		// search should find a match fairly quickly
		sort.Slice(m, func(i, j int) bool {
			iInexact, jInexact := m.fuzzy(m[i]), m.fuzzy(m[j])
			if iInexact && !jInexact {
				return true
			}
			if !iInexact && jInexact {
				return false
			}
			return m[i] < m[j]
		})
	}

	return nil
}

// Match returns true if r matches m.
func (m MatchHost) Match(r *http.Request) bool {
	reqHost, _, err := net.SplitHostPort(r.Host)
	if err != nil {
		// OK; probably didn't have a port
		reqHost = r.Host

		// make sure we strip the brackets from IPv6 addresses
		reqHost = strings.TrimPrefix(reqHost, "[")
		reqHost = strings.TrimSuffix(reqHost, "]")
	}

	if m.large() {
		// fast path: locate exact match using binary search (about 100-1000x faster for large lists)
		pos := sort.Search(len(m), func(i int) bool {
			if m.fuzzy(m[i]) {
				return false
			}
			return m[i] >= reqHost
		})
		if pos < len(m) && m[pos] == reqHost {
			return true
		}
	}

	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)

outer:
	for _, host := range m {
		// fast path: if matcher is large, we already know we don't have an exact
		// match, so we're only looking for fuzzy match now, which should be at the
		// front of the list; if we have reached a value that is not fuzzy, there
		// will be no match and we can short-circuit for efficiency
		if m.large() && !m.fuzzy(host) {
			break
		}

		host = repl.ReplaceAll(host, "")
		if strings.Contains(host, "*") {
			patternParts := strings.Split(host, ".")
			incomingParts := strings.Split(reqHost, ".")
			if len(patternParts) != len(incomingParts) {
				continue
			}
			for i := range patternParts {
				if patternParts[i] == "*" {
					continue
				}
				if !strings.EqualFold(patternParts[i], incomingParts[i]) {
					continue outer
				}
			}
			return true
		} else if strings.EqualFold(reqHost, host) {
			return true
		}
	}

	return false
}

// CELLibrary produces options that expose this matcher for use in CEL
// expression matchers.
//
// Example:
//
//	expression host('localhost')
func (MatchHost) CELLibrary(ctx caddy.Context) (cel.Library, error) {
	return CELMatcherImpl(
		"host",
		"host_match_request_list",
		[]*cel.Type{cel.ListType(cel.StringType)},
		func(data ref.Val) (RequestMatcher, error) {
			refStringList := reflect.TypeOf([]string{})
			strList, err := data.ConvertToNative(refStringList)
			if err != nil {
				return nil, err
			}
			matcher := MatchHost(strList.([]string))
			err = matcher.Provision(ctx)
			return matcher, err
		},
	)
}

// fuzzy returns true if the given hostname h is not a specific
// hostname, e.g. has placeholders or wildcards.
func (MatchHost) fuzzy(h string) bool { return strings.ContainsAny(h, "{*") }

// large returns true if m is considered to be large. Optimizing
// the matcher for smaller lists has diminishing returns.
// See related benchmark function in test file to conduct experiments.
func (m MatchHost) large() bool { return len(m) > 100 }

// CaddyModule returns the Caddy module information.
func (MatchPath) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.path",
		New: func() caddy.Module { return new(MatchPath) },
	}
}

// Provision lower-cases the paths in m to ensure case-insensitive matching.
func (m MatchPath) Provision(_ caddy.Context) error {
	for i := range m {
		if m[i] == "*" && i > 0 {
			// will always match, so just put it first
			m[0] = m[i]
			break
		}
		m[i] = strings.ToLower(m[i])
	}
	return nil
}

// Match returns true if r matches m.
func (m MatchPath) Match(r *http.Request) bool {
	// Even though RFC 9110 says that path matching is case-sensitive
	// (https://www.rfc-editor.org/rfc/rfc9110.html#section-4.2.3),
	// we do case-insensitive matching to mitigate security issues
	// related to differences between operating systems, applications,
	// etc; if case-sensitive matching is needed, the regex matcher
	// can be used instead.
	reqPath := strings.ToLower(r.URL.Path)

	// See #2917; Windows ignores trailing dots and spaces
	// when accessing files (sigh), potentially causing a
	// security risk (cry) if PHP files end up being served
	// as static files, exposing the source code, instead of
	// being matched by *.php to be treated as PHP scripts.
	reqPath = strings.TrimRight(reqPath, ". ")

	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)

	for _, matchPattern := range m {
		matchPattern = repl.ReplaceAll(matchPattern, "")

		// special case: whole path is wildcard; this is unnecessary
		// as it matches all requests, which is the same as no matcher
		if matchPattern == "*" {
			return true
		}

		// Clean the path, merge doubled slashes, etc.
		// This ensures maliciously crafted requests can't bypass
		// the path matcher. See #4407. Good security posture
		// requires that we should do all we can to reduce any
		// funny-looking paths into "normalized" forms such that
		// weird variants can't sneak by.
		//
		// How we clean the path depends on the kind of pattern:
		// we either merge slashes or we don't. If the pattern
		// has double slashes, we preserve them in the path.
		//
		// TODO: Despite the fact that the *vast* majority of path
		// matchers have only 1 pattern, a possible optimization is
		// to remember the cleaned form of the path for future
		// iterations; it's just that the way we clean depends on
		// the kind of pattern.

		mergeSlashes := !strings.Contains(matchPattern, "//")

		// if '%' appears in the match pattern, we interpret that to mean
		// the intent is to compare that part of the path in raw/escaped
		// space; i.e. "%40"=="%40", not "@", and "%2F"=="%2F", not "/"
		if strings.Contains(matchPattern, "%") {
			reqPathForPattern := CleanPath(r.URL.EscapedPath(), mergeSlashes)
			if m.matchPatternWithEscapeSequence(reqPathForPattern, matchPattern) {
				return true
			}

			// doing prefix/suffix/substring matches doesn't make sense
			continue
		}

		reqPathForPattern := CleanPath(reqPath, mergeSlashes)

		// for substring, prefix, and suffix matching, only perform those
		// special, fast matches if they are the only wildcards in the pattern;
		// otherwise we assume a globular match if any * appears in the middle

		// special case: first and last characters are wildcard,
		// treat it as a fast substring match
		if strings.Count(matchPattern, "*") == 2 &&
			strings.HasPrefix(matchPattern, "*") &&
			strings.HasSuffix(matchPattern, "*") &&
			strings.Count(matchPattern, "*") == 2 {
			if strings.Contains(reqPathForPattern, matchPattern[1:len(matchPattern)-1]) {
				return true
			}
			continue
		}

		// only perform prefix/suffix match if it is the only wildcard...
		// I think that is more correct most of the time
		if strings.Count(matchPattern, "*") == 1 {
			// special case: first character is a wildcard,
			// treat it as a fast suffix match
			if strings.HasPrefix(matchPattern, "*") {
				if strings.HasSuffix(reqPathForPattern, matchPattern[1:]) {
					return true
				}
				continue
			}

			// special case: last character is a wildcard,
			// treat it as a fast prefix match
			if strings.HasSuffix(matchPattern, "*") {
				if strings.HasPrefix(reqPathForPattern, matchPattern[:len(matchPattern)-1]) {
					return true
				}
				continue
			}
		}

		// at last, use globular matching, which also is exact matching
		// if there are no glob/wildcard chars; we ignore the error here
		// because we can't handle it anyway
		matches, _ := path.Match(matchPattern, reqPathForPattern)
		if matches {
			return true
		}
	}
	return false
}

func (MatchPath) matchPatternWithEscapeSequence(escapedPath, matchPath string) bool {
	// We would just compare the pattern against r.URL.Path,
	// but the pattern contains %, indicating that we should
	// compare at least some part of the path in raw/escaped
	// space, not normalized space; so we build the string we
	// will compare against by adding the normalized parts
	// of the path, then switching to the escaped parts where
	// the pattern hints to us wherever % is present.
	var sb strings.Builder

	// iterate the pattern and escaped path in lock-step;
	// increment iPattern every time we consume a char from the pattern,
	// increment iPath every time we consume a char from the path;
	// iPattern and iPath are our cursors/iterator positions for each string
	var iPattern, iPath int
	for {
		if iPattern >= len(matchPath) || iPath >= len(escapedPath) {
			break
		}

		// get the next character from the request path

		pathCh := string(escapedPath[iPath])
		var escapedPathCh string

		// normalize (decode) escape sequences
		if pathCh == "%" && len(escapedPath) >= iPath+3 {
			// hold onto this in case we find out the intent is to match in escaped space here;
			// we lowercase it even though technically the spec says: "For consistency, URI
			// producers and normalizers should use uppercase hexadecimal digits for all percent-
			// encodings" (RFC 3986 section 2.1) - we lowercased the matcher pattern earlier in
			// provisioning so we do the same here to gain case-insensitivity in equivalence;
			// besides, this string is never shown visibly
			escapedPathCh = strings.ToLower(escapedPath[iPath : iPath+3])

			var err error
			pathCh, err = url.PathUnescape(escapedPathCh)
			if err != nil {
				// should be impossible unless EscapedPath() is giving us an invalid sequence!
				return false
			}
			iPath += 2 // escape sequence is 2 bytes longer than normal char
		}

		// now get the next character from the pattern

		normalize := true
		switch matchPath[iPattern] {
		case '%':
			// escape sequence

			// if not a wildcard ("%*"), compare literally; consume next two bytes of pattern
			if len(matchPath) >= iPattern+3 && matchPath[iPattern+1] != '*' {
				sb.WriteString(escapedPathCh)
				iPath++
				iPattern += 2
				break
			}

			// escaped wildcard sequence; consume next byte only ('*')
			iPattern++
			normalize = false

			fallthrough
		case '*':
			// wildcard, so consume until next matching character
			remaining := escapedPath[iPath:]
			until := len(escapedPath) - iPath // go until end of string...
			if iPattern < len(matchPath)-1 {  // ...unless the * is not at the end
				nextCh := matchPath[iPattern+1]
				until = strings.IndexByte(remaining, nextCh)
				if until == -1 {
					// terminating char of wildcard span not found, so definitely no match
					return false
				}
			}
			if until == 0 {
				// empty span; nothing to add on this iteration
				break
			}
			next := remaining[:until]
			if normalize {
				var err error
				next, err = url.PathUnescape(next)
				if err != nil {
					return false // should be impossible anyway
				}
			}
			sb.WriteString(next)
			iPath += until
		default:
			sb.WriteString(pathCh)
			iPath++
		}

		iPattern++
	}

	// we can now treat rawpath globs (%*) as regular globs (*)
	matchPath = strings.ReplaceAll(matchPath, "%*", "*")

	// ignore error here because we can't handle it anyway=
	matches, _ := path.Match(matchPath, sb.String())
	return matches
}

// CELLibrary produces options that expose this matcher for use in CEL
// expression matchers.
//
// Example:
//
//	expression path('*substring*', '*suffix')
func (MatchPath) CELLibrary(ctx caddy.Context) (cel.Library, error) {
	return CELMatcherImpl(
		// name of the macro, this is the function name that users see when writing expressions.
		"path",
		// name of the function that the macro will be rewritten to call.
		"path_match_request_list",
		// internal data type of the MatchPath value.
		[]*cel.Type{cel.ListType(cel.StringType)},
		// function to convert a constant list of strings to a MatchPath instance.
		func(data ref.Val) (RequestMatcher, error) {
			refStringList := reflect.TypeOf([]string{})
			strList, err := data.ConvertToNative(refStringList)
			if err != nil {
				return nil, err
			}
			matcher := MatchPath(strList.([]string))
			err = matcher.Provision(ctx)
			return matcher, err
		},
	)
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchPath) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	for d.Next() {
		*m = append(*m, d.RemainingArgs()...)
		if d.NextBlock(0) {
			return d.Err("malformed path matcher: blocks are not supported")
		}
	}
	return nil
}

// CaddyModule returns the Caddy module information.
func (MatchPathRE) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.path_regexp",
		New: func() caddy.Module { return new(MatchPathRE) },
	}
}

// Match returns true if r matches m.
func (m MatchPathRE) Match(r *http.Request) bool {
	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)

	// Clean the path, merges doubled slashes, etc.
	// This ensures maliciously crafted requests can't bypass
	// the path matcher. See #4407
	cleanedPath := cleanPath(r.URL.Path)

	return m.MatchRegexp.Match(cleanedPath, repl)
}

// CELLibrary produces options that expose this matcher for use in CEL
// expression matchers.
//
// Example:
//
//	expression path_regexp('^/bar')
func (MatchPathRE) CELLibrary(ctx caddy.Context) (cel.Library, error) {
	unnamedPattern, err := CELMatcherImpl(
		"path_regexp",
		"path_regexp_request_string",
		[]*cel.Type{cel.StringType},
		func(data ref.Val) (RequestMatcher, error) {
			pattern := data.(types.String)
			matcher := MatchPathRE{MatchRegexp{Pattern: string(pattern)}}
			err := matcher.Provision(ctx)
			return matcher, err
		},
	)
	if err != nil {
		return nil, err
	}
	namedPattern, err := CELMatcherImpl(
		"path_regexp",
		"path_regexp_request_string_string",
		[]*cel.Type{cel.StringType, cel.StringType},
		func(data ref.Val) (RequestMatcher, error) {
			refStringList := reflect.TypeOf([]string{})
			params, err := data.ConvertToNative(refStringList)
			if err != nil {
				return nil, err
			}
			strParams := params.([]string)
			matcher := MatchPathRE{MatchRegexp{Name: strParams[0], Pattern: strParams[1]}}
			err = matcher.Provision(ctx)
			return matcher, err
		},
	)
	if err != nil {
		return nil, err
	}
	envOpts := append(unnamedPattern.CompileOptions(), namedPattern.CompileOptions()...)
	prgOpts := append(unnamedPattern.ProgramOptions(), namedPattern.ProgramOptions()...)
	return NewMatcherCELLibrary(envOpts, prgOpts), nil
}

// CaddyModule returns the Caddy module information.
func (MatchMethod) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.method",
		New: func() caddy.Module { return new(MatchMethod) },
	}
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchMethod) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	for d.Next() {
		*m = append(*m, d.RemainingArgs()...)
		if d.NextBlock(0) {
			return d.Err("malformed method matcher: blocks are not supported")
		}
	}
	return nil
}

// Match returns true if r matches m.
func (m MatchMethod) Match(r *http.Request) bool {
	for _, method := range m {
		if r.Method == method {
			return true
		}
	}
	return false
}

// CELLibrary produces options that expose this matcher for use in CEL
// expression matchers.
//
// Example:
//
//	expression method('PUT', 'POST')
func (MatchMethod) CELLibrary(_ caddy.Context) (cel.Library, error) {
	return CELMatcherImpl(
		"method",
		"method_request_list",
		[]*cel.Type{cel.ListType(cel.StringType)},
		func(data ref.Val) (RequestMatcher, error) {
			refStringList := reflect.TypeOf([]string{})
			strList, err := data.ConvertToNative(refStringList)
			if err != nil {
				return nil, err
			}
			return MatchMethod(strList.([]string)), nil
		},
	)
}

// CaddyModule returns the Caddy module information.
func (MatchQuery) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.query",
		New: func() caddy.Module { return new(MatchQuery) },
	}
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchQuery) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	if *m == nil {
		*m = make(map[string][]string)
	}
	for d.Next() {
		for _, query := range d.RemainingArgs() {
			if query == "" {
				continue
			}
			before, after, found := strings.Cut(query, "=")
			if !found {
				return d.Errf("malformed query matcher token: %s; must be in param=val format", d.Val())
			}
			url.Values(*m).Add(before, after)
		}
		if d.NextBlock(0) {
			return d.Err("malformed query matcher: blocks are not supported")
		}
	}
	return nil
}

// Match returns true if r matches m. An empty m matches an empty query string.
func (m MatchQuery) Match(r *http.Request) bool {
	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)

	// parse query string just once, for efficiency
	parsed, err := url.ParseQuery(r.URL.RawQuery)
	if err != nil {
		// Illegal query string. Likely bad escape sequence or unescaped literals.
		// Note that semicolons in query string have a controversial history. Summaries:
		// - https://github.com/golang/go/issues/50034
		// - https://github.com/golang/go/issues/25192
		// Despite the URL WHATWG spec mandating the use of & separators for query strings,
		// every URL parser implementation is different, and Filippo Valsorda rightly wrote:
		// "Relying on parser alignment for security is doomed." Overall conclusion is that
		// splitting on & and rejecting ; in key=value pairs is safer than accepting raw ;.
		// We regard the Go team's decision as sound and thus reject malformed query strings.
		return false
	}

	for param, vals := range m {
		param = repl.ReplaceAll(param, "")
		paramVal, found := parsed[param]
		if found {
			for _, v := range vals {
				v = repl.ReplaceAll(v, "")
				if paramVal[0] == v || v == "*" {
					return true
				}
			}
		}
	}
	return len(m) == 0 && len(r.URL.Query()) == 0
}

// CELLibrary produces options that expose this matcher for use in CEL
// expression matchers.
//
// Example:
//
//	expression query({'sort': 'asc'}) || query({'foo': ['*bar*', 'baz']})
func (MatchQuery) CELLibrary(_ caddy.Context) (cel.Library, error) {
	return CELMatcherImpl(
		"query",
		"query_matcher_request_map",
		[]*cel.Type{CELTypeJSON},
		func(data ref.Val) (RequestMatcher, error) {
			mapStrListStr, err := CELValueToMapStrList(data)
			if err != nil {
				return nil, err
			}
			return MatchQuery(url.Values(mapStrListStr)), nil
		},
	)
}

// CaddyModule returns the Caddy module information.
func (MatchHeader) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.header",
		New: func() caddy.Module { return new(MatchHeader) },
	}
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchHeader) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	if *m == nil {
		*m = make(map[string][]string)
	}
	for d.Next() {
		var field, val string
		if !d.Args(&field) {
			return d.Errf("malformed header matcher: expected field")
		}

		if strings.HasPrefix(field, "!") {
			if len(field) == 1 {
				return d.Errf("malformed header matcher: must have field name following ! character")
			}

			field = field[1:]
			headers := *m
			headers[field] = nil
			m = &headers
			if d.NextArg() {
				return d.Errf("malformed header matcher: null matching headers cannot have a field value")
			}
		} else {
			if !d.NextArg() {
				return d.Errf("malformed header matcher: expected both field and value")
			}

			// If multiple header matchers with the same header field are defined,
			// we want to add the existing to the list of headers (will be OR'ed)
			val = d.Val()
			http.Header(*m).Add(field, val)
		}

		if d.NextBlock(0) {
			return d.Err("malformed header matcher: blocks are not supported")
		}
	}
	return nil
}

// Match returns true if r matches m.
func (m MatchHeader) Match(r *http.Request) bool {
	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
	return matchHeaders(r.Header, http.Header(m), r.Host, repl)
}

// CELLibrary produces options that expose this matcher for use in CEL
// expression matchers.
//
// Example:
//
//	expression header({'content-type': 'image/png'})
//	expression header({'foo': ['bar', 'baz']}) // match bar or baz
func (MatchHeader) CELLibrary(_ caddy.Context) (cel.Library, error) {
	return CELMatcherImpl(
		"header",
		"header_matcher_request_map",
		[]*cel.Type{CELTypeJSON},
		func(data ref.Val) (RequestMatcher, error) {
			mapStrListStr, err := CELValueToMapStrList(data)
			if err != nil {
				return nil, err
			}
			return MatchHeader(http.Header(mapStrListStr)), nil
		},
	)
}

// getHeaderFieldVals returns the field values for the given fieldName from input.
// The host parameter should be obtained from the http.Request.Host field since
// net/http removes it from the header map.
func getHeaderFieldVals(input http.Header, fieldName, host string) []string {
	fieldName = textproto.CanonicalMIMEHeaderKey(fieldName)
	if fieldName == "Host" && host != "" {
		return []string{host}
	}
	return input[fieldName]
}

// matchHeaders returns true if input matches the criteria in against without regex.
// The host parameter should be obtained from the http.Request.Host field since
// net/http removes it from the header map.
func matchHeaders(input, against http.Header, host string, repl *caddy.Replacer) bool {
	for field, allowedFieldVals := range against {
		actualFieldVals := getHeaderFieldVals(input, field, host)
		if allowedFieldVals != nil && len(allowedFieldVals) == 0 && actualFieldVals != nil {
			// a non-nil but empty list of allowed values means
			// match if the header field exists at all
			continue
		}
		if allowedFieldVals == nil && actualFieldVals == nil {
			// a nil list means match if the header does not exist at all
			continue
		}
		var match bool
	fieldVals:
		for _, actualFieldVal := range actualFieldVals {
			for _, allowedFieldVal := range allowedFieldVals {
				if repl != nil {
					allowedFieldVal = repl.ReplaceAll(allowedFieldVal, "")
				}
				switch {
				case allowedFieldVal == "*":
					match = true
				case strings.HasPrefix(allowedFieldVal, "*") && strings.HasSuffix(allowedFieldVal, "*"):
					match = strings.Contains(actualFieldVal, allowedFieldVal[1:len(allowedFieldVal)-1])
				case strings.HasPrefix(allowedFieldVal, "*"):
					match = strings.HasSuffix(actualFieldVal, allowedFieldVal[1:])
				case strings.HasSuffix(allowedFieldVal, "*"):
					match = strings.HasPrefix(actualFieldVal, allowedFieldVal[:len(allowedFieldVal)-1])
				default:
					match = actualFieldVal == allowedFieldVal
				}
				if match {
					break fieldVals
				}
			}
		}
		if !match {
			return false
		}
	}
	return true
}

// CaddyModule returns the Caddy module information.
func (MatchHeaderRE) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.header_regexp",
		New: func() caddy.Module { return new(MatchHeaderRE) },
	}
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchHeaderRE) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	if *m == nil {
		*m = make(map[string]*MatchRegexp)
	}
	for d.Next() {
		var first, second, third string
		if !d.Args(&first, &second) {
			return d.ArgErr()
		}

		var name, field, val string
		if d.Args(&third) {
			name = first
			field = second
			val = third
		} else {
			field = first
			val = second
		}

		// If there's already a pattern for this field
		// then we would end up overwriting the old one
		if (*m)[field] != nil {
			return d.Errf("header_regexp matcher can only be used once per named matcher, per header field: %s", field)
		}

		(*m)[field] = &MatchRegexp{Pattern: val, Name: name}

		if d.NextBlock(0) {
			return d.Err("malformed header_regexp matcher: blocks are not supported")
		}
	}
	return nil
}

// Match returns true if r matches m.
func (m MatchHeaderRE) Match(r *http.Request) bool {
	for field, rm := range m {
		actualFieldVals := getHeaderFieldVals(r.Header, field, r.Host)
		match := false
	fieldVal:
		for _, actualFieldVal := range actualFieldVals {
			repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
			if rm.Match(actualFieldVal, repl) {
				match = true
				break fieldVal
			}
		}
		if !match {
			return false
		}
	}
	return true
}

// Provision compiles m's regular expressions.
func (m MatchHeaderRE) Provision(ctx caddy.Context) error {
	for _, rm := range m {
		err := rm.Provision(ctx)
		if err != nil {
			return err
		}
	}
	return nil
}

// Validate validates m's regular expressions.
func (m MatchHeaderRE) Validate() error {
	for _, rm := range m {
		err := rm.Validate()
		if err != nil {
			return err
		}
	}
	return nil
}

// CELLibrary produces options that expose this matcher for use in CEL
// expression matchers.
//
// Example:
//
//	expression header_regexp('foo', 'Field', 'fo+')
func (MatchHeaderRE) CELLibrary(ctx caddy.Context) (cel.Library, error) {
	unnamedPattern, err := CELMatcherImpl(
		"header_regexp",
		"header_regexp_request_string_string",
		[]*cel.Type{cel.StringType, cel.StringType},
		func(data ref.Val) (RequestMatcher, error) {
			refStringList := reflect.TypeOf([]string{})
			params, err := data.ConvertToNative(refStringList)
			if err != nil {
				return nil, err
			}
			strParams := params.([]string)
			matcher := MatchHeaderRE{}
			matcher[strParams[0]] = &MatchRegexp{Pattern: strParams[1], Name: ""}
			err = matcher.Provision(ctx)
			return matcher, err
		},
	)
	if err != nil {
		return nil, err
	}
	namedPattern, err := CELMatcherImpl(
		"header_regexp",
		"header_regexp_request_string_string_string",
		[]*cel.Type{cel.StringType, cel.StringType, cel.StringType},
		func(data ref.Val) (RequestMatcher, error) {
			refStringList := reflect.TypeOf([]string{})
			params, err := data.ConvertToNative(refStringList)
			if err != nil {
				return nil, err
			}
			strParams := params.([]string)
			matcher := MatchHeaderRE{}
			matcher[strParams[1]] = &MatchRegexp{Pattern: strParams[2], Name: strParams[0]}
			err = matcher.Provision(ctx)
			return matcher, err
		},
	)
	if err != nil {
		return nil, err
	}
	envOpts := append(unnamedPattern.CompileOptions(), namedPattern.CompileOptions()...)
	prgOpts := append(unnamedPattern.ProgramOptions(), namedPattern.ProgramOptions()...)
	return NewMatcherCELLibrary(envOpts, prgOpts), nil
}

// CaddyModule returns the Caddy module information.
func (MatchProtocol) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.protocol",
		New: func() caddy.Module { return new(MatchProtocol) },
	}
}

// Match returns true if r matches m.
func (m MatchProtocol) Match(r *http.Request) bool {
	switch string(m) {
	case "grpc":
		return strings.HasPrefix(r.Header.Get("content-type"), "application/grpc")
	case "https":
		return r.TLS != nil
	case "http":
		return r.TLS == nil
	case "http/1.0":
		return r.ProtoMajor == 1 && r.ProtoMinor == 0
	case "http/1.0+":
		return r.ProtoAtLeast(1, 0)
	case "http/1.1":
		return r.ProtoMajor == 1 && r.ProtoMinor == 1
	case "http/1.1+":
		return r.ProtoAtLeast(1, 1)
	case "http/2":
		return r.ProtoMajor == 2
	case "http/2+":
		return r.ProtoAtLeast(2, 0)
	case "http/3":
		return r.ProtoMajor == 3
	case "http/3+":
		return r.ProtoAtLeast(3, 0)
	}
	return false
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchProtocol) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	for d.Next() {
		var proto string
		if !d.Args(&proto) {
			return d.Err("expected exactly one protocol")
		}
		*m = MatchProtocol(proto)
	}
	return nil
}

// CELLibrary produces options that expose this matcher for use in CEL
// expression matchers.
//
// Example:
//
//	expression protocol('https')
func (MatchProtocol) CELLibrary(_ caddy.Context) (cel.Library, error) {
	return CELMatcherImpl(
		"protocol",
		"protocol_request_string",
		[]*cel.Type{cel.StringType},
		func(data ref.Val) (RequestMatcher, error) {
			protocolStr, ok := data.(types.String)
			if !ok {
				return nil, errors.New("protocol argument was not a string")
			}
			return MatchProtocol(strings.ToLower(string(protocolStr))), nil
		},
	)
}

// CaddyModule returns the Caddy module information.
func (MatchNot) CaddyModule() caddy.ModuleInfo {
	return caddy.ModuleInfo{
		ID:  "http.matchers.not",
		New: func() caddy.Module { return new(MatchNot) },
	}
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (m *MatchNot) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	for d.Next() {
		matcherSet, err := ParseCaddyfileNestedMatcherSet(d)
		if err != nil {
			return err
		}
		m.MatcherSetsRaw = append(m.MatcherSetsRaw, matcherSet)
	}
	return nil
}

// UnmarshalJSON satisfies json.Unmarshaler. It puts the JSON
// bytes directly into m's MatcherSetsRaw field.
func (m *MatchNot) UnmarshalJSON(data []byte) error {
	return json.Unmarshal(data, &m.MatcherSetsRaw)
}

// MarshalJSON satisfies json.Marshaler by marshaling
// m's raw matcher sets.
func (m MatchNot) MarshalJSON() ([]byte, error) {
	return json.Marshal(m.MatcherSetsRaw)
}

// Provision loads the matcher modules to be negated.
func (m *MatchNot) Provision(ctx caddy.Context) error {
	matcherSets, err := ctx.LoadModule(m, "MatcherSetsRaw")
	if err != nil {
		return fmt.Errorf("loading matcher sets: %v", err)
	}
	for _, modMap := range matcherSets.([]map[string]any) {
		var ms MatcherSet
		for _, modIface := range modMap {
			ms = append(ms, modIface.(RequestMatcher))
		}
		m.MatcherSets = append(m.MatcherSets, ms)
	}
	return nil
}

// Match returns true if r matches m. Since this matcher negates
// the embedded matchers, false is returned if any of its matcher
// sets return true.
func (m MatchNot) Match(r *http.Request) bool {
	for _, ms := range m.MatcherSets {
		if ms.Match(r) {
			return false
		}
	}
	return true
}

// MatchRegexp is an embedable type for matching
// using regular expressions. It adds placeholders
// to the request's replacer.
type MatchRegexp struct {
	// A unique name for this regular expression. Optional,
	// but useful to prevent overwriting captures from other
	// regexp matchers.
	Name string `json:"name,omitempty"`

	// The regular expression to evaluate, in RE2 syntax,
	// which is the same general syntax used by Go, Perl,
	// and Python. For details, see
	// [Go's regexp package](https://golang.org/pkg/regexp/).
	// Captures are accessible via placeholders. Unnamed
	// capture groups are exposed as their numeric, 1-based
	// index, while named capture groups are available by
	// the capture group name.
	Pattern string `json:"pattern"`

	compiled *regexp.Regexp
	phPrefix string
}

// Provision compiles the regular expression.
func (mre *MatchRegexp) Provision(caddy.Context) error {
	re, err := regexp.Compile(mre.Pattern)
	if err != nil {
		return fmt.Errorf("compiling matcher regexp %s: %v", mre.Pattern, err)
	}
	mre.compiled = re
	mre.phPrefix = regexpPlaceholderPrefix
	if mre.Name != "" {
		mre.phPrefix += "." + mre.Name
	}
	return nil
}

// Validate ensures mre is set up correctly.
func (mre *MatchRegexp) Validate() error {
	if mre.Name != "" && !wordRE.MatchString(mre.Name) {
		return fmt.Errorf("invalid regexp name (must contain only word characters): %s", mre.Name)
	}
	return nil
}

// Match returns true if input matches the compiled regular
// expression in mre. It sets values on the replacer repl
// associated with capture groups, using the given scope
// (namespace).
func (mre *MatchRegexp) Match(input string, repl *caddy.Replacer) bool {
	matches := mre.compiled.FindStringSubmatch(input)
	if matches == nil {
		return false
	}

	// save all capture groups, first by index
	for i, match := range matches {
		key := mre.phPrefix + "." + strconv.Itoa(i)
		repl.Set(key, match)
	}

	// then by name
	for i, name := range mre.compiled.SubexpNames() {
		if i != 0 && name != "" {
			key := mre.phPrefix + "." + name
			repl.Set(key, matches[i])
		}
	}

	return true
}

// UnmarshalCaddyfile implements caddyfile.Unmarshaler.
func (mre *MatchRegexp) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
	for d.Next() {
		// If this is the second iteration of the loop
		// then there's more than one path_regexp matcher
		// and we would end up overwriting the old one
		if mre.Pattern != "" {
			return d.Err("regular expression can only be used once per named matcher")
		}

		args := d.RemainingArgs()
		switch len(args) {
		case 1:
			mre.Pattern = args[0]
		case 2:
			mre.Name = args[0]
			mre.Pattern = args[1]
		default:
			return d.ArgErr()
		}
		if d.NextBlock(0) {
			return d.Err("malformed path_regexp matcher: blocks are not supported")
		}
	}
	return nil
}

// ParseCaddyfileNestedMatcher parses the Caddyfile tokens for a nested
// matcher set, and returns its raw module map value.
func ParseCaddyfileNestedMatcherSet(d *caddyfile.Dispenser) (caddy.ModuleMap, error) {
	matcherMap := make(map[string]RequestMatcher)

	// in case there are multiple instances of the same matcher, concatenate
	// their tokens (we expect that UnmarshalCaddyfile should be able to
	// handle more than one segment); otherwise, we'd overwrite other
	// instances of the matcher in this set
	tokensByMatcherName := make(map[string][]caddyfile.Token)
	for nesting := d.Nesting(); d.NextArg() || d.NextBlock(nesting); {
		matcherName := d.Val()
		tokensByMatcherName[matcherName] = append(tokensByMatcherName[matcherName], d.NextSegment()...)
	}

	for matcherName, tokens := range tokensByMatcherName {
		mod, err := caddy.GetModule("http.matchers." + matcherName)
		if err != nil {
			return nil, d.Errf("getting matcher module '%s': %v", matcherName, err)
		}
		unm, ok := mod.New().(caddyfile.Unmarshaler)
		if !ok {
			return nil, d.Errf("matcher module '%s' is not a Caddyfile unmarshaler", matcherName)
		}
		err = unm.UnmarshalCaddyfile(caddyfile.NewDispenser(tokens))
		if err != nil {
			return nil, err
		}
		rm, ok := unm.(RequestMatcher)
		if !ok {
			return nil, fmt.Errorf("matcher module '%s' is not a request matcher", matcherName)
		}
		matcherMap[matcherName] = rm
	}

	// we should now have a functional matcher, but we also
	// need to be able to marshal as JSON, otherwise config
	// adaptation will be missing the matchers!
	matcherSet := make(caddy.ModuleMap)
	for name, matcher := range matcherMap {
		jsonBytes, err := json.Marshal(matcher)
		if err != nil {
			return nil, fmt.Errorf("marshaling %T matcher: %v", matcher, err)
		}
		matcherSet[name] = jsonBytes
	}

	return matcherSet, nil
}

var (
	wordRE = regexp.MustCompile(`\w+`)
)

const regexpPlaceholderPrefix = "http.regexp"

// MatcherErrorVarKey is the key used for the variable that
// holds an optional error emitted from a request matcher,
// to short-circuit the handler chain, since matchers cannot
// return errors via the RequestMatcher interface.
const MatcherErrorVarKey = "matchers.error"

// Interface guards
var (
	_ RequestMatcher    = (*MatchHost)(nil)
	_ caddy.Provisioner = (*MatchHost)(nil)
	_ RequestMatcher    = (*MatchPath)(nil)
	_ RequestMatcher    = (*MatchPathRE)(nil)
	_ caddy.Provisioner = (*MatchPathRE)(nil)
	_ RequestMatcher    = (*MatchMethod)(nil)
	_ RequestMatcher    = (*MatchQuery)(nil)
	_ RequestMatcher    = (*MatchHeader)(nil)
	_ RequestMatcher    = (*MatchHeaderRE)(nil)
	_ caddy.Provisioner = (*MatchHeaderRE)(nil)
	_ RequestMatcher    = (*MatchProtocol)(nil)
	_ RequestMatcher    = (*MatchNot)(nil)
	_ caddy.Provisioner = (*MatchNot)(nil)
	_ caddy.Provisioner = (*MatchRegexp)(nil)

	_ caddyfile.Unmarshaler = (*MatchHost)(nil)
	_ caddyfile.Unmarshaler = (*MatchPath)(nil)
	_ caddyfile.Unmarshaler = (*MatchPathRE)(nil)
	_ caddyfile.Unmarshaler = (*MatchMethod)(nil)
	_ caddyfile.Unmarshaler = (*MatchQuery)(nil)
	_ caddyfile.Unmarshaler = (*MatchHeader)(nil)
	_ caddyfile.Unmarshaler = (*MatchHeaderRE)(nil)
	_ caddyfile.Unmarshaler = (*MatchProtocol)(nil)
	_ caddyfile.Unmarshaler = (*VarsMatcher)(nil)
	_ caddyfile.Unmarshaler = (*MatchVarsRE)(nil)

	_ CELLibraryProducer = (*MatchHost)(nil)
	_ CELLibraryProducer = (*MatchPath)(nil)
	_ CELLibraryProducer = (*MatchPathRE)(nil)
	_ CELLibraryProducer = (*MatchMethod)(nil)
	_ CELLibraryProducer = (*MatchQuery)(nil)
	_ CELLibraryProducer = (*MatchHeader)(nil)
	_ CELLibraryProducer = (*MatchHeaderRE)(nil)
	_ CELLibraryProducer = (*MatchProtocol)(nil)
	// _ CELLibraryProducer = (*VarsMatcher)(nil)
	// _ CELLibraryProducer = (*MatchVarsRE)(nil)

	_ json.Marshaler   = (*MatchNot)(nil)
	_ json.Unmarshaler = (*MatchNot)(nil)
)