-
Notifications
You must be signed in to change notification settings - Fork 57
/
morty.go
1120 lines (992 loc) · 31.5 KB
/
morty.go
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
package main
import (
"bytes"
"crypto/hmac"
"crypto/sha256"
"encoding/base64"
"encoding/hex"
"errors"
"flag"
"fmt"
"html/template"
"io"
"log"
"mime"
"net/url"
"os"
"path/filepath"
"regexp"
"strings"
"time"
"unicode/utf8"
"github.com/valyala/fasthttp"
"github.com/valyala/fasthttp/fasthttpproxy"
"golang.org/x/net/html"
"golang.org/x/net/html/charset"
"golang.org/x/text/encoding"
"github.com/asciimoo/morty/config"
"github.com/asciimoo/morty/contenttype"
)
const (
STATE_DEFAULT int = 0
STATE_IN_STYLE int = 1
STATE_IN_NOSCRIPT int = 2
)
const VERSION = "v0.2.1"
const MAX_REDIRECT_COUNT = 5
var CLIENT *fasthttp.Client = &fasthttp.Client{
MaxResponseBodySize: 10 * 1024 * 1024, // 10M
ReadBufferSize: 16 * 1024, // 16K
}
var cfg *config.Config = config.DefaultConfig
var ALLOWED_CONTENTTYPE_FILTER contenttype.Filter = contenttype.NewFilterOr([]contenttype.Filter{
// html
contenttype.NewFilterEquals("text", "html", ""),
contenttype.NewFilterEquals("application", "xhtml", "xml"),
// css
contenttype.NewFilterEquals("text", "css", ""),
// images
contenttype.NewFilterEquals("image", "gif", ""),
contenttype.NewFilterEquals("image", "png", ""),
contenttype.NewFilterEquals("image", "jpeg", ""),
contenttype.NewFilterEquals("image", "pjpeg", ""),
contenttype.NewFilterEquals("image", "webp", ""),
contenttype.NewFilterEquals("image", "tiff", ""),
contenttype.NewFilterEquals("image", "vnd.microsoft.icon", ""),
contenttype.NewFilterEquals("image", "bmp", ""),
contenttype.NewFilterEquals("image", "x-ms-bmp", ""),
contenttype.NewFilterEquals("image", "x-icon", ""),
// fonts
contenttype.NewFilterEquals("application", "font-otf", ""),
contenttype.NewFilterEquals("application", "font-ttf", ""),
contenttype.NewFilterEquals("application", "font-woff", ""),
contenttype.NewFilterEquals("application", "vnd.ms-fontobject", ""),
})
var ALLOWED_CONTENTTYPE_ATTACHMENT_FILTER contenttype.Filter = contenttype.NewFilterOr([]contenttype.Filter{
// texts
contenttype.NewFilterEquals("text", "csv", ""),
contenttype.NewFilterEquals("text", "tab-separated-values", ""),
contenttype.NewFilterEquals("text", "plain", ""),
// API
contenttype.NewFilterEquals("application", "json", ""),
// Documents
contenttype.NewFilterEquals("application", "x-latex", ""),
contenttype.NewFilterEquals("application", "pdf", ""),
contenttype.NewFilterEquals("application", "vnd.oasis.opendocument.text", ""),
contenttype.NewFilterEquals("application", "vnd.oasis.opendocument.spreadsheet", ""),
contenttype.NewFilterEquals("application", "vnd.oasis.opendocument.presentation", ""),
contenttype.NewFilterEquals("application", "vnd.oasis.opendocument.graphics", ""),
// Compressed archives
contenttype.NewFilterEquals("application", "zip", ""),
contenttype.NewFilterEquals("application", "gzip", ""),
contenttype.NewFilterEquals("application", "x-compressed", ""),
contenttype.NewFilterEquals("application", "x-gtar", ""),
contenttype.NewFilterEquals("application", "x-compress", ""),
// Generic binary
contenttype.NewFilterEquals("application", "octet-stream", ""),
})
var ALLOWED_CONTENTTYPE_PARAMETERS map[string]bool = map[string]bool{
"charset": true,
}
var UNSAFE_ELEMENTS [][]byte = [][]byte{
[]byte("applet"),
[]byte("canvas"),
[]byte("embed"),
//[]byte("iframe"),
[]byte("math"),
[]byte("script"),
[]byte("svg"),
}
var SAFE_ATTRIBUTES [][]byte = [][]byte{
[]byte("abbr"),
[]byte("accesskey"),
[]byte("align"),
[]byte("alt"),
[]byte("as"),
[]byte("autocomplete"),
[]byte("charset"),
[]byte("checked"),
[]byte("class"),
[]byte("content"),
[]byte("contenteditable"),
[]byte("contextmenu"),
[]byte("dir"),
[]byte("for"),
[]byte("height"),
[]byte("hidden"),
[]byte("hreflang"),
[]byte("id"),
[]byte("lang"),
[]byte("media"),
[]byte("method"),
[]byte("name"),
[]byte("nowrap"),
[]byte("placeholder"),
[]byte("property"),
[]byte("rel"),
[]byte("spellcheck"),
[]byte("tabindex"),
[]byte("target"),
[]byte("title"),
[]byte("translate"),
[]byte("type"),
[]byte("value"),
[]byte("width"),
}
var LINK_REL_SAFE_VALUES [][]byte = [][]byte{
[]byte("alternate"),
[]byte("archives"),
[]byte("author"),
[]byte("copyright"),
[]byte("first"),
[]byte("help"),
[]byte("icon"),
[]byte("index"),
[]byte("last"),
[]byte("license"),
[]byte("manifest"),
[]byte("next"),
[]byte("pingback"),
[]byte("prev"),
[]byte("publisher"),
[]byte("search"),
[]byte("shortcut icon"),
[]byte("stylesheet"),
[]byte("up"),
}
var LINK_HTTP_EQUIV_SAFE_VALUES [][]byte = [][]byte{
// X-UA-Compatible will be added automaticaly, so it can be skipped
[]byte("date"),
[]byte("last-modified"),
[]byte("refresh"), // URL rewrite
// []byte("location"), TODO URL rewrite
[]byte("content-language"),
}
var CSS_URL_REGEXP *regexp.Regexp = regexp.MustCompile("url\\((['\"]?)[ \\t\\f]*([\u0009\u0021\u0023-\u0026\u0028\u002a-\u007E]+)(['\"]?)\\)?")
type Proxy struct {
Key []byte
RequestTimeout time.Duration
FollowRedirect bool
}
type RequestConfig struct {
Key []byte
BaseURL *url.URL
BodyInjected bool
}
type HTMLBodyExtParam struct {
BaseURL string
HasMortyKey bool
}
type HTMLFormExtParam struct {
BaseURL string
MortyHash string
}
var HTML_FORM_EXTENSION *template.Template
var HTML_BODY_EXTENSION *template.Template
var HTML_HEAD_CONTENT_TYPE string = `<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="referrer" content="no-referrer">
`
var MORTY_HTML_PAGE_START string = `<!doctype html>
<html>
<head>
<title>MortyProxy</title>
<meta name="viewport" content="width=device-width, initial-scale=1 , maximum-scale=1.0, user-scalable=1" />
<style>
html { height: 100%; }
body { min-height : 100%; display: flex; flex-direction:column; font-family: 'Garamond', 'Georgia', serif; text-align: center; color: #444; background: #FAFAFA; margin: 0; padding: 0; font-size: 1.1em; }
input { border: 1px solid #888; padding: 0.3em; color: #444; background: #FFF; font-size: 1.1em; }
input[placeholder] { width:80%; }
a { text-decoration: none; #2980b9; }
h1, h2 { font-weight: 200; margin-bottom: 2rem; }
h1 { font-size: 3em; }
.container { flex:1; min-height: 100%; margin-bottom: 1em; }
.footer { margin: 1em; }
.footer p { font-size: 0.8em; }
</style>
</head>
<body>
<div class="container">
<h1>MortyProxy</h1>
`
var MORTY_HTML_PAGE_END string = `
</div>
<div class="footer">
<p>Morty rewrites web pages to exclude malicious HTML tags and CSS/HTML attributes. It also replaces external resource references to prevent third-party information leaks.<br />
<a href="https://github.com/asciimoo/morty">view on github</a>
</p>
</div>
</body>
</html>`
var FAVICON_BYTES []byte
func init() {
FaviconBase64 := "iVBORw0KGgoAAAANSUhEUgAAABAAAAAQEAYAAABPYyMiAAAABmJLR0T///////8JWPfcAAAACXBIWXMAAABIAAAASABGyWs+AAAAF0lEQVRIx2NgGAWjYBSMglEwCkbBSAcACBAAAeaR9cIAAAAASUVORK5CYII"
FAVICON_BYTES, _ = base64.StdEncoding.DecodeString(FaviconBase64)
var err error
HTML_FORM_EXTENSION, err = template.New("html_form_extension").Parse(
`<input type="hidden" name="mortyurl" value="{{.BaseURL}}" />{{if .MortyHash}}<input type="hidden" name="mortyhash" value="{{.MortyHash}}" />{{end}}`)
if err != nil {
panic(err)
}
HTML_BODY_EXTENSION, err = template.New("html_body_extension").Parse(`
<input type="checkbox" id="mortytoggle" autocomplete="off" />
<div id="mortyheader">
<form method="get">
<label for="mortytoggle">hide</label>
<span><a href="/">Morty Proxy</a></span>
<input type="url" value="{{.BaseURL}}" name="mortyurl" {{if .HasMortyKey }}readonly="true"{{end}} />
This is a <a href="https://github.com/asciimoo/morty">proxified and sanitized</a> view of the page, visit <a href="{{.BaseURL}}" rel="noreferrer">original site</a>.
</form>
</div>
<style>
body{ position: absolute !important; top: 42px !important; left: 0 !important; right: 0 !important; bottom: 0 !important; }
#mortyheader { position: fixed; margin: 0; box-sizing: border-box; -webkit-box-sizing: border-box; top: 0; left: 0; right: 0; z-index: 2147483647 !important; font-size: 12px; line-height: normal; border-width: 0px 0px 2px 0; border-style: solid; border-color: #AAAAAA; background: #FFF; padding: 4px; color: #444; height: 42px; }
#mortyheader * { padding: 0; margin: 0; }
#mortyheader p { padding: 0 0 0.7em 0; display: block; }
#mortyheader a { color: #3498db; font-weight: bold; display: inline; }
#mortyheader label { text-align: right; cursor: pointer; position: fixed; right: 4px; top: 4px; display: block; color: #444; }
#mortyheader > form > span { font-size: 24px; font-weight: bold; margin-right: 20px; margin-left: 20px; }
input[type=checkbox]#mortytoggle { display: none; }
input[type=checkbox]#mortytoggle:checked ~ div { display: none; visibility: hidden; }
#mortyheader input[type=url] { width: 50%; padding: 4px; font-size: 16px; }
</style>
`)
if err != nil {
panic(err)
}
}
func (p *Proxy) RequestHandler(ctx *fasthttp.RequestCtx) {
if appRequestHandler(ctx) {
return
}
requestHash := popRequestParam(ctx, []byte("mortyhash"))
requestURI := popRequestParam(ctx, []byte("mortyurl"))
if requestURI == nil {
p.serveMainPage(ctx, 200, nil)
return
}
if p.Key != nil {
if !verifyRequestURI(requestURI, requestHash, p.Key) {
// HTTP status code 403 : Forbidden
p.serveMainPage(ctx, 403, errors.New(`invalid "mortyhash" parameter`))
return
}
}
requestURIQuery := ctx.QueryArgs().QueryString()
if len(requestURIQuery) > 0 {
if bytes.ContainsRune(requestURI, '?') {
requestURI = append(requestURI, '&')
} else {
requestURI = append(requestURI, '?')
}
requestURI = append(requestURI, requestURIQuery...)
}
p.ProcessUri(ctx, string(requestURI), 0)
}
func (p *Proxy) ProcessUri(ctx *fasthttp.RequestCtx, requestURIStr string, redirectCount int) {
parsedURI, err := url.Parse(requestURIStr)
if err != nil {
// HTTP status code 500 : Internal Server Error
p.serveMainPage(ctx, 500, err)
return
}
if parsedURI.Scheme == "" {
requestURIStr = "https://" + requestURIStr
parsedURI, err = url.Parse(requestURIStr)
if err != nil {
p.serveMainPage(ctx, 500, err)
return
}
}
// Serve an intermediate page for protocols other than HTTP(S)
if (parsedURI.Scheme != "http" && parsedURI.Scheme != "https") || strings.HasSuffix(parsedURI.Host, ".onion") {
p.serveExitMortyPage(ctx, parsedURI)
return
}
req := fasthttp.AcquireRequest()
defer fasthttp.ReleaseRequest(req)
req.SetConnectionClose()
if cfg.Debug {
log.Println(string(ctx.Method()), requestURIStr)
}
req.SetRequestURI(requestURIStr)
req.Header.SetUserAgentBytes([]byte("Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0"))
resp := fasthttp.AcquireResponse()
defer fasthttp.ReleaseResponse(resp)
req.Header.SetMethodBytes(ctx.Method())
if ctx.IsPost() || ctx.IsPut() {
req.SetBody(ctx.PostBody())
}
err = CLIENT.DoTimeout(req, resp, p.RequestTimeout)
if err != nil {
if err == fasthttp.ErrTimeout {
// HTTP status code 504 : Gateway Time-Out
p.serveMainPage(ctx, 504, err)
} else {
// HTTP status code 500 : Internal Server Error
p.serveMainPage(ctx, 500, err)
}
return
}
if resp.StatusCode() != 200 {
switch resp.StatusCode() {
case 301, 302, 303, 307, 308:
loc := resp.Header.Peek("Location")
if loc != nil {
if p.FollowRedirect && ctx.IsGet() {
// GET method: Morty follows the redirect
if redirectCount < MAX_REDIRECT_COUNT {
if cfg.Debug {
log.Println("follow redirect to", string(loc))
}
p.ProcessUri(ctx, string(loc), redirectCount+1)
} else {
p.serveMainPage(ctx, 310, errors.New("Too many redirects"))
}
return
} else {
// Other HTTP methods: Morty does NOT follow the redirect
rc := &RequestConfig{Key: p.Key, BaseURL: parsedURI}
url, err := rc.ProxifyURI(loc)
if err == nil {
ctx.SetStatusCode(resp.StatusCode())
ctx.Response.Header.Add("Location", url)
if cfg.Debug {
log.Println("redirect to", string(loc))
}
return
}
}
}
}
error_message := fmt.Sprintf("invalid response: %d (%s)", resp.StatusCode(), requestURIStr)
p.serveMainPage(ctx, resp.StatusCode(), errors.New(error_message))
return
}
contentTypeBytes := resp.Header.Peek("Content-Type")
if contentTypeBytes == nil {
// HTTP status code 503 : Service Unavailable
p.serveMainPage(ctx, 503, errors.New("invalid content type"))
return
}
contentTypeString := string(contentTypeBytes)
// decode Content-Type header
contentType, error := contenttype.ParseContentType(contentTypeString)
if error != nil {
// HTTP status code 503 : Service Unavailable
p.serveMainPage(ctx, 503, errors.New("invalid content type"))
return
}
// content-disposition
contentDispositionBytes := ctx.Request.Header.Peek("Content-Disposition")
// check content type
if !ALLOWED_CONTENTTYPE_FILTER(contentType) {
// it is not a usual content type
if ALLOWED_CONTENTTYPE_ATTACHMENT_FILTER(contentType) {
// force attachment for allowed content type
contentDispositionBytes = contentDispositionForceAttachment(contentDispositionBytes, parsedURI)
} else {
// deny access to forbidden content type
// HTTP status code 403 : Forbidden
p.serveMainPage(ctx, 403, errors.New("forbidden content type "+parsedURI.String()))
return
}
}
// HACK : replace */xhtml by text/html
if contentType.SubType == "xhtml" {
contentType.TopLevelType = "text"
contentType.SubType = "html"
contentType.Suffix = ""
}
// conversion to UTF-8
var responseBody []byte
if contentType.TopLevelType == "text" {
e, ename, _ := charset.DetermineEncoding(resp.Body(), contentTypeString)
if (e != encoding.Nop) && (!strings.EqualFold("utf-8", ename)) {
responseBody, err = e.NewDecoder().Bytes(resp.Body())
if err != nil {
// HTTP status code 503 : Service Unavailable
p.serveMainPage(ctx, 503, err)
return
}
} else {
responseBody = resp.Body()
}
// update the charset or specify it
contentType.Parameters["charset"] = "UTF-8"
} else {
responseBody = resp.Body()
}
//
contentType.FilterParameters(ALLOWED_CONTENTTYPE_PARAMETERS)
// set the content type
ctx.SetContentType(contentType.String())
// output according to MIME type
switch {
case contentType.SubType == "css" && contentType.Suffix == "":
sanitizeCSS(&RequestConfig{Key: p.Key, BaseURL: parsedURI}, ctx, responseBody)
case contentType.SubType == "html" && contentType.Suffix == "":
rc := &RequestConfig{Key: p.Key, BaseURL: parsedURI}
sanitizeHTML(rc, ctx, responseBody)
if !rc.BodyInjected {
p := HTMLBodyExtParam{rc.BaseURL.String(), false}
if len(rc.Key) > 0 {
p.HasMortyKey = true
}
err := HTML_BODY_EXTENSION.Execute(ctx, p)
if err != nil {
if cfg.Debug {
fmt.Println("failed to inject body extension", err)
}
}
}
default:
if contentDispositionBytes != nil {
ctx.Response.Header.AddBytesV("Content-Disposition", contentDispositionBytes)
}
ctx.Write(responseBody)
}
}
// force content-disposition to attachment
func contentDispositionForceAttachment(contentDispositionBytes []byte, url *url.URL) []byte {
var contentDispositionParams map[string]string
if contentDispositionBytes != nil {
var err error
_, contentDispositionParams, err = mime.ParseMediaType(string(contentDispositionBytes))
if err != nil {
contentDispositionParams = make(map[string]string)
}
} else {
contentDispositionParams = make(map[string]string)
}
_, fileNameDefined := contentDispositionParams["filename"]
if !fileNameDefined {
// TODO : sanitize filename
contentDispositionParams["fileName"] = filepath.Base(url.Path)
}
return []byte(mime.FormatMediaType("attachment", contentDispositionParams))
}
func appRequestHandler(ctx *fasthttp.RequestCtx) bool {
// serve robots.txt
if bytes.Equal(ctx.Path(), []byte("/robots.txt")) {
ctx.SetContentType("text/plain")
ctx.Write([]byte("User-Agent: *\nDisallow: /\n"))
return true
}
// server favicon.ico
if bytes.Equal(ctx.Path(), []byte("/favicon.ico")) {
ctx.SetContentType("image/png")
ctx.Write(FAVICON_BYTES)
return true
}
return false
}
func popRequestParam(ctx *fasthttp.RequestCtx, paramName []byte) []byte {
param := ctx.QueryArgs().PeekBytes(paramName)
if param == nil {
param = ctx.PostArgs().PeekBytes(paramName)
ctx.PostArgs().DelBytes(paramName)
}
ctx.QueryArgs().DelBytes(paramName)
return param
}
func sanitizeCSS(rc *RequestConfig, out io.Writer, css []byte) {
// TODO
urlSlices := CSS_URL_REGEXP.FindAllSubmatchIndex(css, -1)
if urlSlices == nil {
out.Write(css)
return
}
startIndex := 0
for _, s := range urlSlices {
urlStart := s[4]
urlEnd := s[5]
if uri, err := rc.ProxifyURI(css[urlStart:urlEnd]); err == nil {
out.Write(css[startIndex:urlStart])
out.Write([]byte(uri))
startIndex = urlEnd
} else if cfg.Debug {
log.Println("cannot proxify css uri:", string(css[urlStart:urlEnd]))
}
}
if startIndex < len(css) {
out.Write(css[startIndex:len(css)])
}
}
func sanitizeHTML(rc *RequestConfig, out io.Writer, htmlDoc []byte) {
r := bytes.NewReader(htmlDoc)
decoder := html.NewTokenizer(r)
decoder.AllowCDATA(true)
unsafeElements := make([][]byte, 0, 8)
state := STATE_DEFAULT
for {
token := decoder.Next()
if token == html.ErrorToken {
err := decoder.Err()
if err != io.EOF {
log.Println("failed to parse HTML")
}
break
}
if len(unsafeElements) == 0 {
switch token {
case html.StartTagToken, html.SelfClosingTagToken:
tag, hasAttrs := decoder.TagName()
safe := !inArray(tag, UNSAFE_ELEMENTS)
if !safe {
if token != html.SelfClosingTagToken {
var unsafeTag []byte = make([]byte, len(tag))
copy(unsafeTag, tag)
unsafeElements = append(unsafeElements, unsafeTag)
}
break
}
if bytes.Equal(tag, []byte("base")) {
for {
attrName, attrValue, moreAttr := decoder.TagAttr()
if bytes.Equal(attrName, []byte("href")) {
parsedURI, err := url.Parse(string(attrValue))
if err == nil {
rc.BaseURL = parsedURI
}
}
if !moreAttr {
break
}
}
break
}
if bytes.Equal(tag, []byte("noscript")) {
state = STATE_IN_NOSCRIPT
break
}
var attrs [][][]byte
if hasAttrs {
for {
attrName, attrValue, moreAttr := decoder.TagAttr()
attrs = append(attrs, [][]byte{
attrName,
attrValue,
[]byte(html.EscapeString(string(attrValue))),
})
if !moreAttr {
break
}
}
}
if bytes.Equal(tag, []byte("link")) {
sanitizeLinkTag(rc, out, attrs)
break
}
if bytes.Equal(tag, []byte("meta")) {
sanitizeMetaTag(rc, out, attrs)
break
}
fmt.Fprintf(out, "<%s", tag)
if hasAttrs {
sanitizeAttrs(rc, out, attrs)
}
if token == html.SelfClosingTagToken {
fmt.Fprintf(out, " />")
} else {
fmt.Fprintf(out, ">")
if bytes.Equal(tag, []byte("style")) {
state = STATE_IN_STYLE
}
}
if bytes.Equal(tag, []byte("head")) {
fmt.Fprintf(out, HTML_HEAD_CONTENT_TYPE)
}
if bytes.Equal(tag, []byte("form")) {
var formURL *url.URL
for _, attr := range attrs {
if bytes.Equal(attr[0], []byte("action")) {
formURL, _ = url.Parse(string(attr[1]))
formURL = mergeURIs(rc.BaseURL, formURL)
break
}
}
if formURL == nil {
formURL = rc.BaseURL
}
urlStr := formURL.String()
var key string
if rc.Key != nil {
key = hash(urlStr, rc.Key)
}
err := HTML_FORM_EXTENSION.Execute(out, HTMLFormExtParam{urlStr, key})
if err != nil {
if cfg.Debug {
fmt.Println("failed to inject body extension", err)
}
}
}
case html.EndTagToken:
tag, _ := decoder.TagName()
writeEndTag := true
switch string(tag) {
case "body":
p := HTMLBodyExtParam{rc.BaseURL.String(), false}
if len(rc.Key) > 0 {
p.HasMortyKey = true
}
err := HTML_BODY_EXTENSION.Execute(out, p)
if err != nil {
if cfg.Debug {
fmt.Println("failed to inject body extension", err)
}
}
rc.BodyInjected = true
case "style":
state = STATE_DEFAULT
case "noscript":
state = STATE_DEFAULT
writeEndTag = false
}
// skip noscript tags - only the tag, not the content, because javascript is sanitized
if writeEndTag {
fmt.Fprintf(out, "</%s>", tag)
}
case html.TextToken:
switch state {
case STATE_DEFAULT:
fmt.Fprintf(out, "%s", decoder.Raw())
case STATE_IN_STYLE:
sanitizeCSS(rc, out, decoder.Raw())
case STATE_IN_NOSCRIPT:
sanitizeHTML(rc, out, decoder.Raw())
}
case html.CommentToken:
// ignore comment. TODO : parse IE conditional comment
case html.DoctypeToken:
out.Write(decoder.Raw())
}
} else {
switch token {
case html.StartTagToken, html.SelfClosingTagToken:
tag, _ := decoder.TagName()
if inArray(tag, UNSAFE_ELEMENTS) {
unsafeElements = append(unsafeElements, tag)
}
case html.EndTagToken:
tag, _ := decoder.TagName()
if bytes.Equal(unsafeElements[len(unsafeElements)-1], tag) {
unsafeElements = unsafeElements[:len(unsafeElements)-1]
}
}
}
}
}
func sanitizeLinkTag(rc *RequestConfig, out io.Writer, attrs [][][]byte) {
exclude := false
for _, attr := range attrs {
attrName := attr[0]
attrValue := attr[1]
if bytes.Equal(attrName, []byte("rel")) {
if !inArray(attrValue, LINK_REL_SAFE_VALUES) {
exclude = true
break
}
}
if bytes.Equal(attrName, []byte("as")) {
if bytes.Equal(attrValue, []byte("script")) {
exclude = true
break
}
}
}
if !exclude {
out.Write([]byte("<link"))
for _, attr := range attrs {
sanitizeAttr(rc, out, attr[0], attr[1], attr[2])
}
out.Write([]byte(">"))
}
}
func sanitizeMetaTag(rc *RequestConfig, out io.Writer, attrs [][][]byte) {
var http_equiv []byte
var content []byte
for _, attr := range attrs {
attrName := attr[0]
attrValue := attr[1]
if bytes.Equal(attrName, []byte("http-equiv")) {
http_equiv = bytes.ToLower(attrValue)
// exclude some <meta http-equiv="..." ..>
if !inArray(http_equiv, LINK_HTTP_EQUIV_SAFE_VALUES) {
return
}
}
if bytes.Equal(attrName, []byte("content")) {
content = attrValue
}
if bytes.Equal(attrName, []byte("charset")) {
// exclude <meta charset="...">
return
}
}
out.Write([]byte("<meta"))
urlIndex := bytes.Index(bytes.ToLower(content), []byte("url="))
if bytes.Equal(http_equiv, []byte("refresh")) && urlIndex != -1 {
contentUrl := content[urlIndex+4:]
// special case of <meta http-equiv="refresh" content="0; url='example.com/url.with.quote.outside'">
if len(contentUrl) >= 2 && (contentUrl[0] == byte('\'') || contentUrl[0] == byte('"')) {
if contentUrl[0] == contentUrl[len(contentUrl)-1] {
contentUrl = contentUrl[1 : len(contentUrl)-1]
}
}
// output proxify result
if uri, err := rc.ProxifyURI(contentUrl); err == nil {
fmt.Fprintf(out, ` http-equiv="refresh" content="%surl=%s"`, content[:urlIndex], uri)
}
} else {
if len(http_equiv) > 0 {
fmt.Fprintf(out, ` http-equiv="%s"`, http_equiv)
}
sanitizeAttrs(rc, out, attrs)
}
out.Write([]byte(">"))
}
func sanitizeAttrs(rc *RequestConfig, out io.Writer, attrs [][][]byte) {
for _, attr := range attrs {
sanitizeAttr(rc, out, attr[0], attr[1], attr[2])
}
}
func sanitizeAttr(rc *RequestConfig, out io.Writer, attrName, attrValue, escapedAttrValue []byte) {
if inArray(attrName, SAFE_ATTRIBUTES) {
fmt.Fprintf(out, " %s=\"%s\"", attrName, escapedAttrValue)
return
}
switch string(attrName) {
case "src", "href", "action":
if uri, err := rc.ProxifyURI(attrValue); err == nil {
fmt.Fprintf(out, " %s=\"%s\"", attrName, uri)
} else if cfg.Debug {
log.Println("cannot proxify uri:", string(attrValue))
}
case "style":
cssAttr := bytes.NewBuffer(nil)
sanitizeCSS(rc, cssAttr, attrValue)
fmt.Fprintf(out, " %s=\"%s\"", attrName, html.EscapeString(string(cssAttr.Bytes())))
}
}
func mergeURIs(u1, u2 *url.URL) *url.URL {
if u2 == nil {
return u1
}
return u1.ResolveReference(u2)
}
// Sanitized URI : removes all runes bellow 32 (included) as the begining and end of URI, and lower case the scheme.
// avoid memory allocation (except for the scheme)
func sanitizeURI(uri []byte) ([]byte, string) {
first_rune_index := 0
first_rune_seen := false
scheme_last_index := -1
buffer := bytes.NewBuffer(make([]byte, 0, 10))
// remove trailing space and special characters
uri = bytes.TrimRight(uri, "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F\x20")
// loop over byte by byte
for i, c := range uri {
// ignore special characters and space (c <= 32)
if c > 32 {
// append to the lower case of the rune to buffer
if c < utf8.RuneSelf && 'A' <= c && c <= 'Z' {
c = c + 'a' - 'A'
}
buffer.WriteByte(c)
// update the first rune index that is not a special rune
if !first_rune_seen {
first_rune_index = i
first_rune_seen = true
}
if c == ':' {
// colon rune found, we have found the scheme
scheme_last_index = i
break
} else if c == '/' || c == '?' || c == '\\' || c == '#' {
// special case : most probably a relative URI
break
}
}
}
if scheme_last_index != -1 {
// scheme found
// copy the "lower case without special runes scheme" before the ":" rune
scheme_start_index := scheme_last_index - buffer.Len() + 1
copy(uri[scheme_start_index:], buffer.Bytes())
// and return the result
return uri[scheme_start_index:], buffer.String()
} else {
// scheme NOT found
return uri[first_rune_index:], ""
}
}
func (rc *RequestConfig) ProxifyURI(uri []byte) (string, error) {
// sanitize URI
uri, scheme := sanitizeURI(uri)
// remove javascript protocol
if scheme == "javascript:" {
return "", nil
}
// TODO check malicious data: - e.g. data:script
if scheme == "data:" {
if bytes.HasPrefix(uri, []byte("data:image/png")) ||
bytes.HasPrefix(uri, []byte("data:image/jpeg")) ||
bytes.HasPrefix(uri, []byte("data:image/pjpeg")) ||
bytes.HasPrefix(uri, []byte("data:image/gif")) ||
bytes.HasPrefix(uri, []byte("data:image/webp")) {
// should be safe
return string(uri), nil
} else {
// unsafe data
return "", nil
}
}
// parse the uri
u, err := url.Parse(string(uri))
if err != nil {
return "", err
}
// get the fragment (with the prefix "#")
fragment := ""
if len(u.Fragment) > 0 {
fragment = "#" + u.Fragment
}
// reset the fragment: it is not included in the mortyurl
u.Fragment = ""
// merge the URI with the document URI
u = mergeURIs(rc.BaseURL, u)
// simple internal link ?
// some web pages describe the whole link https://same:[email protected]/same.path?same.query#new.fragment
if u.Scheme == rc.BaseURL.Scheme &&
(rc.BaseURL.User == nil || (u.User != nil && u.User.String() == rc.BaseURL.User.String())) &&
u.Host == rc.BaseURL.Host &&
u.Path == rc.BaseURL.Path &&
u.RawQuery == rc.BaseURL.RawQuery {
// the fragment is the only difference between the document URI and the uri parameter
return fragment, nil
}
// return full URI and fragment (if not empty)
morty_uri := u.String()
if rc.Key == nil {
return fmt.Sprintf("./?mortyurl=%s%s", url.QueryEscape(morty_uri), fragment), nil
}
return fmt.Sprintf("./?mortyhash=%s&mortyurl=%s%s", hash(morty_uri, rc.Key), url.QueryEscape(morty_uri), fragment), nil
}
func inArray(b []byte, a [][]byte) bool {
for _, b2 := range a {
if bytes.Equal(b, b2) {
return true
}
}
return false
}
func hash(msg string, key []byte) string {
mac := hmac.New(sha256.New, key)