File: webdav.go

package info (click to toggle)
golang-golang-x-net-dev 1%3A0.0%2Bgit20181201.351d144%2Bdfsg-3
  • links: PTS, VCS
  • area: main
  • in suites: buster, buster-backports, buster-backports-sloppy, experimental
  • size: 5,676 kB
  • sloc: makefile: 53; asm: 18
file content (702 lines) | stat: -rw-r--r-- 20,704 bytes parent folder | download | duplicates (2)
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
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package webdav provides a WebDAV server implementation.
package webdav // import "golang.org/x/net/webdav"

import (
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"path"
	"strings"
	"time"
)

type Handler struct {
	// Prefix is the URL path prefix to strip from WebDAV resource paths.
	Prefix string
	// FileSystem is the virtual file system.
	FileSystem FileSystem
	// LockSystem is the lock management system.
	LockSystem LockSystem
	// Logger is an optional error logger. If non-nil, it will be called
	// for all HTTP requests.
	Logger func(*http.Request, error)
}

func (h *Handler) stripPrefix(p string) (string, int, error) {
	if h.Prefix == "" {
		return p, http.StatusOK, nil
	}
	if r := strings.TrimPrefix(p, h.Prefix); len(r) < len(p) {
		return r, http.StatusOK, nil
	}
	return p, http.StatusNotFound, errPrefixMismatch
}

func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	status, err := http.StatusBadRequest, errUnsupportedMethod
	if h.FileSystem == nil {
		status, err = http.StatusInternalServerError, errNoFileSystem
	} else if h.LockSystem == nil {
		status, err = http.StatusInternalServerError, errNoLockSystem
	} else {
		switch r.Method {
		case "OPTIONS":
			status, err = h.handleOptions(w, r)
		case "GET", "HEAD", "POST":
			status, err = h.handleGetHeadPost(w, r)
		case "DELETE":
			status, err = h.handleDelete(w, r)
		case "PUT":
			status, err = h.handlePut(w, r)
		case "MKCOL":
			status, err = h.handleMkcol(w, r)
		case "COPY", "MOVE":
			status, err = h.handleCopyMove(w, r)
		case "LOCK":
			status, err = h.handleLock(w, r)
		case "UNLOCK":
			status, err = h.handleUnlock(w, r)
		case "PROPFIND":
			status, err = h.handlePropfind(w, r)
		case "PROPPATCH":
			status, err = h.handleProppatch(w, r)
		}
	}

	if status != 0 {
		w.WriteHeader(status)
		if status != http.StatusNoContent {
			w.Write([]byte(StatusText(status)))
		}
	}
	if h.Logger != nil {
		h.Logger(r, err)
	}
}

func (h *Handler) lock(now time.Time, root string) (token string, status int, err error) {
	token, err = h.LockSystem.Create(now, LockDetails{
		Root:      root,
		Duration:  infiniteTimeout,
		ZeroDepth: true,
	})
	if err != nil {
		if err == ErrLocked {
			return "", StatusLocked, err
		}
		return "", http.StatusInternalServerError, err
	}
	return token, 0, nil
}

func (h *Handler) confirmLocks(r *http.Request, src, dst string) (release func(), status int, err error) {
	hdr := r.Header.Get("If")
	if hdr == "" {
		// An empty If header means that the client hasn't previously created locks.
		// Even if this client doesn't care about locks, we still need to check that
		// the resources aren't locked by another client, so we create temporary
		// locks that would conflict with another client's locks. These temporary
		// locks are unlocked at the end of the HTTP request.
		now, srcToken, dstToken := time.Now(), "", ""
		if src != "" {
			srcToken, status, err = h.lock(now, src)
			if err != nil {
				return nil, status, err
			}
		}
		if dst != "" {
			dstToken, status, err = h.lock(now, dst)
			if err != nil {
				if srcToken != "" {
					h.LockSystem.Unlock(now, srcToken)
				}
				return nil, status, err
			}
		}

		return func() {
			if dstToken != "" {
				h.LockSystem.Unlock(now, dstToken)
			}
			if srcToken != "" {
				h.LockSystem.Unlock(now, srcToken)
			}
		}, 0, nil
	}

	ih, ok := parseIfHeader(hdr)
	if !ok {
		return nil, http.StatusBadRequest, errInvalidIfHeader
	}
	// ih is a disjunction (OR) of ifLists, so any ifList will do.
	for _, l := range ih.lists {
		lsrc := l.resourceTag
		if lsrc == "" {
			lsrc = src
		} else {
			u, err := url.Parse(lsrc)
			if err != nil {
				continue
			}
			if u.Host != r.Host {
				continue
			}
			lsrc, status, err = h.stripPrefix(u.Path)
			if err != nil {
				return nil, status, err
			}
		}
		release, err = h.LockSystem.Confirm(time.Now(), lsrc, dst, l.conditions...)
		if err == ErrConfirmationFailed {
			continue
		}
		if err != nil {
			return nil, http.StatusInternalServerError, err
		}
		return release, 0, nil
	}
	// Section 10.4.1 says that "If this header is evaluated and all state lists
	// fail, then the request must fail with a 412 (Precondition Failed) status."
	// We follow the spec even though the cond_put_corrupt_token test case from
	// the litmus test warns on seeing a 412 instead of a 423 (Locked).
	return nil, http.StatusPreconditionFailed, ErrLocked
}

func (h *Handler) handleOptions(w http.ResponseWriter, r *http.Request) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path)
	if err != nil {
		return status, err
	}
	ctx := r.Context()
	allow := "OPTIONS, LOCK, PUT, MKCOL"
	if fi, err := h.FileSystem.Stat(ctx, reqPath); err == nil {
		if fi.IsDir() {
			allow = "OPTIONS, LOCK, DELETE, PROPPATCH, COPY, MOVE, UNLOCK, PROPFIND"
		} else {
			allow = "OPTIONS, LOCK, GET, HEAD, POST, DELETE, PROPPATCH, COPY, MOVE, UNLOCK, PROPFIND, PUT"
		}
	}
	w.Header().Set("Allow", allow)
	// http://www.webdav.org/specs/rfc4918.html#dav.compliance.classes
	w.Header().Set("DAV", "1, 2")
	// http://msdn.microsoft.com/en-au/library/cc250217.aspx
	w.Header().Set("MS-Author-Via", "DAV")
	return 0, nil
}

func (h *Handler) handleGetHeadPost(w http.ResponseWriter, r *http.Request) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path)
	if err != nil {
		return status, err
	}
	// TODO: check locks for read-only access??
	ctx := r.Context()
	f, err := h.FileSystem.OpenFile(ctx, reqPath, os.O_RDONLY, 0)
	if err != nil {
		return http.StatusNotFound, err
	}
	defer f.Close()
	fi, err := f.Stat()
	if err != nil {
		return http.StatusNotFound, err
	}
	if fi.IsDir() {
		return http.StatusMethodNotAllowed, nil
	}
	etag, err := findETag(ctx, h.FileSystem, h.LockSystem, reqPath, fi)
	if err != nil {
		return http.StatusInternalServerError, err
	}
	w.Header().Set("ETag", etag)
	// Let ServeContent determine the Content-Type header.
	http.ServeContent(w, r, reqPath, fi.ModTime(), f)
	return 0, nil
}

func (h *Handler) handleDelete(w http.ResponseWriter, r *http.Request) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path)
	if err != nil {
		return status, err
	}
	release, status, err := h.confirmLocks(r, reqPath, "")
	if err != nil {
		return status, err
	}
	defer release()

	ctx := r.Context()

	// TODO: return MultiStatus where appropriate.

	// "godoc os RemoveAll" says that "If the path does not exist, RemoveAll
	// returns nil (no error)." WebDAV semantics are that it should return a
	// "404 Not Found". We therefore have to Stat before we RemoveAll.
	if _, err := h.FileSystem.Stat(ctx, reqPath); err != nil {
		if os.IsNotExist(err) {
			return http.StatusNotFound, err
		}
		return http.StatusMethodNotAllowed, err
	}
	if err := h.FileSystem.RemoveAll(ctx, reqPath); err != nil {
		return http.StatusMethodNotAllowed, err
	}
	return http.StatusNoContent, nil
}

func (h *Handler) handlePut(w http.ResponseWriter, r *http.Request) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path)
	if err != nil {
		return status, err
	}
	release, status, err := h.confirmLocks(r, reqPath, "")
	if err != nil {
		return status, err
	}
	defer release()
	// TODO(rost): Support the If-Match, If-None-Match headers? See bradfitz'
	// comments in http.checkEtag.
	ctx := r.Context()

	f, err := h.FileSystem.OpenFile(ctx, reqPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
	if err != nil {
		return http.StatusNotFound, err
	}
	_, copyErr := io.Copy(f, r.Body)
	fi, statErr := f.Stat()
	closeErr := f.Close()
	// TODO(rost): Returning 405 Method Not Allowed might not be appropriate.
	if copyErr != nil {
		return http.StatusMethodNotAllowed, copyErr
	}
	if statErr != nil {
		return http.StatusMethodNotAllowed, statErr
	}
	if closeErr != nil {
		return http.StatusMethodNotAllowed, closeErr
	}
	etag, err := findETag(ctx, h.FileSystem, h.LockSystem, reqPath, fi)
	if err != nil {
		return http.StatusInternalServerError, err
	}
	w.Header().Set("ETag", etag)
	return http.StatusCreated, nil
}

func (h *Handler) handleMkcol(w http.ResponseWriter, r *http.Request) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path)
	if err != nil {
		return status, err
	}
	release, status, err := h.confirmLocks(r, reqPath, "")
	if err != nil {
		return status, err
	}
	defer release()

	ctx := r.Context()

	if r.ContentLength > 0 {
		return http.StatusUnsupportedMediaType, nil
	}
	if err := h.FileSystem.Mkdir(ctx, reqPath, 0777); err != nil {
		if os.IsNotExist(err) {
			return http.StatusConflict, err
		}
		return http.StatusMethodNotAllowed, err
	}
	return http.StatusCreated, nil
}

func (h *Handler) handleCopyMove(w http.ResponseWriter, r *http.Request) (status int, err error) {
	hdr := r.Header.Get("Destination")
	if hdr == "" {
		return http.StatusBadRequest, errInvalidDestination
	}
	u, err := url.Parse(hdr)
	if err != nil {
		return http.StatusBadRequest, errInvalidDestination
	}
	if u.Host != r.Host {
		return http.StatusBadGateway, errInvalidDestination
	}

	src, status, err := h.stripPrefix(r.URL.Path)
	if err != nil {
		return status, err
	}

	dst, status, err := h.stripPrefix(u.Path)
	if err != nil {
		return status, err
	}

	if dst == "" {
		return http.StatusBadGateway, errInvalidDestination
	}
	if dst == src {
		return http.StatusForbidden, errDestinationEqualsSource
	}

	ctx := r.Context()

	if r.Method == "COPY" {
		// Section 7.5.1 says that a COPY only needs to lock the destination,
		// not both destination and source. Strictly speaking, this is racy,
		// even though a COPY doesn't modify the source, if a concurrent
		// operation modifies the source. However, the litmus test explicitly
		// checks that COPYing a locked-by-another source is OK.
		release, status, err := h.confirmLocks(r, "", dst)
		if err != nil {
			return status, err
		}
		defer release()

		// Section 9.8.3 says that "The COPY method on a collection without a Depth
		// header must act as if a Depth header with value "infinity" was included".
		depth := infiniteDepth
		if hdr := r.Header.Get("Depth"); hdr != "" {
			depth = parseDepth(hdr)
			if depth != 0 && depth != infiniteDepth {
				// Section 9.8.3 says that "A client may submit a Depth header on a
				// COPY on a collection with a value of "0" or "infinity"."
				return http.StatusBadRequest, errInvalidDepth
			}
		}
		return copyFiles(ctx, h.FileSystem, src, dst, r.Header.Get("Overwrite") != "F", depth, 0)
	}

	release, status, err := h.confirmLocks(r, src, dst)
	if err != nil {
		return status, err
	}
	defer release()

	// Section 9.9.2 says that "The MOVE method on a collection must act as if
	// a "Depth: infinity" header was used on it. A client must not submit a
	// Depth header on a MOVE on a collection with any value but "infinity"."
	if hdr := r.Header.Get("Depth"); hdr != "" {
		if parseDepth(hdr) != infiniteDepth {
			return http.StatusBadRequest, errInvalidDepth
		}
	}
	return moveFiles(ctx, h.FileSystem, src, dst, r.Header.Get("Overwrite") == "T")
}

func (h *Handler) handleLock(w http.ResponseWriter, r *http.Request) (retStatus int, retErr error) {
	duration, err := parseTimeout(r.Header.Get("Timeout"))
	if err != nil {
		return http.StatusBadRequest, err
	}
	li, status, err := readLockInfo(r.Body)
	if err != nil {
		return status, err
	}

	ctx := r.Context()
	token, ld, now, created := "", LockDetails{}, time.Now(), false
	if li == (lockInfo{}) {
		// An empty lockInfo means to refresh the lock.
		ih, ok := parseIfHeader(r.Header.Get("If"))
		if !ok {
			return http.StatusBadRequest, errInvalidIfHeader
		}
		if len(ih.lists) == 1 && len(ih.lists[0].conditions) == 1 {
			token = ih.lists[0].conditions[0].Token
		}
		if token == "" {
			return http.StatusBadRequest, errInvalidLockToken
		}
		ld, err = h.LockSystem.Refresh(now, token, duration)
		if err != nil {
			if err == ErrNoSuchLock {
				return http.StatusPreconditionFailed, err
			}
			return http.StatusInternalServerError, err
		}

	} else {
		// Section 9.10.3 says that "If no Depth header is submitted on a LOCK request,
		// then the request MUST act as if a "Depth:infinity" had been submitted."
		depth := infiniteDepth
		if hdr := r.Header.Get("Depth"); hdr != "" {
			depth = parseDepth(hdr)
			if depth != 0 && depth != infiniteDepth {
				// Section 9.10.3 says that "Values other than 0 or infinity must not be
				// used with the Depth header on a LOCK method".
				return http.StatusBadRequest, errInvalidDepth
			}
		}
		reqPath, status, err := h.stripPrefix(r.URL.Path)
		if err != nil {
			return status, err
		}
		ld = LockDetails{
			Root:      reqPath,
			Duration:  duration,
			OwnerXML:  li.Owner.InnerXML,
			ZeroDepth: depth == 0,
		}
		token, err = h.LockSystem.Create(now, ld)
		if err != nil {
			if err == ErrLocked {
				return StatusLocked, err
			}
			return http.StatusInternalServerError, err
		}
		defer func() {
			if retErr != nil {
				h.LockSystem.Unlock(now, token)
			}
		}()

		// Create the resource if it didn't previously exist.
		if _, err := h.FileSystem.Stat(ctx, reqPath); err != nil {
			f, err := h.FileSystem.OpenFile(ctx, reqPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
			if err != nil {
				// TODO: detect missing intermediate dirs and return http.StatusConflict?
				return http.StatusInternalServerError, err
			}
			f.Close()
			created = true
		}

		// http://www.webdav.org/specs/rfc4918.html#HEADER_Lock-Token says that the
		// Lock-Token value is a Coded-URL. We add angle brackets.
		w.Header().Set("Lock-Token", "<"+token+">")
	}

	w.Header().Set("Content-Type", "application/xml; charset=utf-8")
	if created {
		// This is "w.WriteHeader(http.StatusCreated)" and not "return
		// http.StatusCreated, nil" because we write our own (XML) response to w
		// and Handler.ServeHTTP would otherwise write "Created".
		w.WriteHeader(http.StatusCreated)
	}
	writeLockInfo(w, token, ld)
	return 0, nil
}

func (h *Handler) handleUnlock(w http.ResponseWriter, r *http.Request) (status int, err error) {
	// http://www.webdav.org/specs/rfc4918.html#HEADER_Lock-Token says that the
	// Lock-Token value is a Coded-URL. We strip its angle brackets.
	t := r.Header.Get("Lock-Token")
	if len(t) < 2 || t[0] != '<' || t[len(t)-1] != '>' {
		return http.StatusBadRequest, errInvalidLockToken
	}
	t = t[1 : len(t)-1]

	switch err = h.LockSystem.Unlock(time.Now(), t); err {
	case nil:
		return http.StatusNoContent, err
	case ErrForbidden:
		return http.StatusForbidden, err
	case ErrLocked:
		return StatusLocked, err
	case ErrNoSuchLock:
		return http.StatusConflict, err
	default:
		return http.StatusInternalServerError, err
	}
}

func (h *Handler) handlePropfind(w http.ResponseWriter, r *http.Request) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path)
	if err != nil {
		return status, err
	}
	ctx := r.Context()
	fi, err := h.FileSystem.Stat(ctx, reqPath)
	if err != nil {
		if os.IsNotExist(err) {
			return http.StatusNotFound, err
		}
		return http.StatusMethodNotAllowed, err
	}
	depth := infiniteDepth
	if hdr := r.Header.Get("Depth"); hdr != "" {
		depth = parseDepth(hdr)
		if depth == invalidDepth {
			return http.StatusBadRequest, errInvalidDepth
		}
	}
	pf, status, err := readPropfind(r.Body)
	if err != nil {
		return status, err
	}

	mw := multistatusWriter{w: w}

	walkFn := func(reqPath string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		var pstats []Propstat
		if pf.Propname != nil {
			pnames, err := propnames(ctx, h.FileSystem, h.LockSystem, reqPath)
			if err != nil {
				return err
			}
			pstat := Propstat{Status: http.StatusOK}
			for _, xmlname := range pnames {
				pstat.Props = append(pstat.Props, Property{XMLName: xmlname})
			}
			pstats = append(pstats, pstat)
		} else if pf.Allprop != nil {
			pstats, err = allprop(ctx, h.FileSystem, h.LockSystem, reqPath, pf.Prop)
		} else {
			pstats, err = props(ctx, h.FileSystem, h.LockSystem, reqPath, pf.Prop)
		}
		if err != nil {
			return err
		}
		return mw.write(makePropstatResponse(path.Join(h.Prefix, reqPath), pstats))
	}

	walkErr := walkFS(ctx, h.FileSystem, depth, reqPath, fi, walkFn)
	closeErr := mw.close()
	if walkErr != nil {
		return http.StatusInternalServerError, walkErr
	}
	if closeErr != nil {
		return http.StatusInternalServerError, closeErr
	}
	return 0, nil
}

func (h *Handler) handleProppatch(w http.ResponseWriter, r *http.Request) (status int, err error) {
	reqPath, status, err := h.stripPrefix(r.URL.Path)
	if err != nil {
		return status, err
	}
	release, status, err := h.confirmLocks(r, reqPath, "")
	if err != nil {
		return status, err
	}
	defer release()

	ctx := r.Context()

	if _, err := h.FileSystem.Stat(ctx, reqPath); err != nil {
		if os.IsNotExist(err) {
			return http.StatusNotFound, err
		}
		return http.StatusMethodNotAllowed, err
	}
	patches, status, err := readProppatch(r.Body)
	if err != nil {
		return status, err
	}
	pstats, err := patch(ctx, h.FileSystem, h.LockSystem, reqPath, patches)
	if err != nil {
		return http.StatusInternalServerError, err
	}
	mw := multistatusWriter{w: w}
	writeErr := mw.write(makePropstatResponse(r.URL.Path, pstats))
	closeErr := mw.close()
	if writeErr != nil {
		return http.StatusInternalServerError, writeErr
	}
	if closeErr != nil {
		return http.StatusInternalServerError, closeErr
	}
	return 0, nil
}

func makePropstatResponse(href string, pstats []Propstat) *response {
	resp := response{
		Href:     []string{(&url.URL{Path: href}).EscapedPath()},
		Propstat: make([]propstat, 0, len(pstats)),
	}
	for _, p := range pstats {
		var xmlErr *xmlError
		if p.XMLError != "" {
			xmlErr = &xmlError{InnerXML: []byte(p.XMLError)}
		}
		resp.Propstat = append(resp.Propstat, propstat{
			Status:              fmt.Sprintf("HTTP/1.1 %d %s", p.Status, StatusText(p.Status)),
			Prop:                p.Props,
			ResponseDescription: p.ResponseDescription,
			Error:               xmlErr,
		})
	}
	return &resp
}

const (
	infiniteDepth = -1
	invalidDepth  = -2
)

// parseDepth maps the strings "0", "1" and "infinity" to 0, 1 and
// infiniteDepth. Parsing any other string returns invalidDepth.
//
// Different WebDAV methods have further constraints on valid depths:
//	- PROPFIND has no further restrictions, as per section 9.1.
//	- COPY accepts only "0" or "infinity", as per section 9.8.3.
//	- MOVE accepts only "infinity", as per section 9.9.2.
//	- LOCK accepts only "0" or "infinity", as per section 9.10.3.
// These constraints are enforced by the handleXxx methods.
func parseDepth(s string) int {
	switch s {
	case "0":
		return 0
	case "1":
		return 1
	case "infinity":
		return infiniteDepth
	}
	return invalidDepth
}

// http://www.webdav.org/specs/rfc4918.html#status.code.extensions.to.http11
const (
	StatusMulti               = 207
	StatusUnprocessableEntity = 422
	StatusLocked              = 423
	StatusFailedDependency    = 424
	StatusInsufficientStorage = 507
)

func StatusText(code int) string {
	switch code {
	case StatusMulti:
		return "Multi-Status"
	case StatusUnprocessableEntity:
		return "Unprocessable Entity"
	case StatusLocked:
		return "Locked"
	case StatusFailedDependency:
		return "Failed Dependency"
	case StatusInsufficientStorage:
		return "Insufficient Storage"
	}
	return http.StatusText(code)
}

var (
	errDestinationEqualsSource = errors.New("webdav: destination equals source")
	errDirectoryNotEmpty       = errors.New("webdav: directory not empty")
	errInvalidDepth            = errors.New("webdav: invalid depth")
	errInvalidDestination      = errors.New("webdav: invalid destination")
	errInvalidIfHeader         = errors.New("webdav: invalid If header")
	errInvalidLockInfo         = errors.New("webdav: invalid lock info")
	errInvalidLockToken        = errors.New("webdav: invalid lock token")
	errInvalidPropfind         = errors.New("webdav: invalid propfind")
	errInvalidProppatch        = errors.New("webdav: invalid proppatch")
	errInvalidResponse         = errors.New("webdav: invalid response")
	errInvalidTimeout          = errors.New("webdav: invalid timeout")
	errNoFileSystem            = errors.New("webdav: no file system")
	errNoLockSystem            = errors.New("webdav: no lock system")
	errNotADirectory           = errors.New("webdav: not a directory")
	errPrefixMismatch          = errors.New("webdav: prefix mismatch")
	errRecursionTooDeep        = errors.New("webdav: recursion too deep")
	errUnsupportedLockInfo     = errors.New("webdav: unsupported lock info")
	errUnsupportedMethod       = errors.New("webdav: unsupported method")
)