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
|
// Copyright 2011 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 template
import (
"strings"
)
// attrTypeMap[n] describes the value of the given attribute.
// If an attribute affects (or can mask) the encoding or interpretation of
// other content, or affects the contents, idempotency, or credentials of a
// network message, then the value in this map is contentTypeUnsafe.
// This map is derived from HTML5, specifically
// http://www.w3.org/TR/html5/Overview.html#attributes-1
// as well as "%URI"-typed attributes from
// http://www.w3.org/TR/html4/index/attributes.html
var attrTypeMap = map[string]contentType{
"accept": contentTypePlain,
"accept-charset": contentTypeUnsafe,
"action": contentTypeURL,
"alt": contentTypePlain,
"archive": contentTypeURL,
"async": contentTypeUnsafe,
"autocomplete": contentTypePlain,
"autofocus": contentTypePlain,
"autoplay": contentTypePlain,
"background": contentTypeURL,
"border": contentTypePlain,
"checked": contentTypePlain,
"cite": contentTypeURL,
"challenge": contentTypeUnsafe,
"charset": contentTypeUnsafe,
"class": contentTypePlain,
"classid": contentTypeURL,
"codebase": contentTypeURL,
"cols": contentTypePlain,
"colspan": contentTypePlain,
"content": contentTypeUnsafe,
"contenteditable": contentTypePlain,
"contextmenu": contentTypePlain,
"controls": contentTypePlain,
"coords": contentTypePlain,
"crossorigin": contentTypeUnsafe,
"data": contentTypeURL,
"datetime": contentTypePlain,
"default": contentTypePlain,
"defer": contentTypeUnsafe,
"dir": contentTypePlain,
"dirname": contentTypePlain,
"disabled": contentTypePlain,
"draggable": contentTypePlain,
"dropzone": contentTypePlain,
"enctype": contentTypeUnsafe,
"for": contentTypePlain,
"form": contentTypeUnsafe,
"formaction": contentTypeURL,
"formenctype": contentTypeUnsafe,
"formmethod": contentTypeUnsafe,
"formnovalidate": contentTypeUnsafe,
"formtarget": contentTypePlain,
"headers": contentTypePlain,
"height": contentTypePlain,
"hidden": contentTypePlain,
"high": contentTypePlain,
"href": contentTypeURL,
"hreflang": contentTypePlain,
"http-equiv": contentTypeUnsafe,
"icon": contentTypeURL,
"id": contentTypePlain,
"ismap": contentTypePlain,
"keytype": contentTypeUnsafe,
"kind": contentTypePlain,
"label": contentTypePlain,
"lang": contentTypePlain,
"language": contentTypeUnsafe,
"list": contentTypePlain,
"longdesc": contentTypeURL,
"loop": contentTypePlain,
"low": contentTypePlain,
"manifest": contentTypeURL,
"max": contentTypePlain,
"maxlength": contentTypePlain,
"media": contentTypePlain,
"mediagroup": contentTypePlain,
"method": contentTypeUnsafe,
"min": contentTypePlain,
"multiple": contentTypePlain,
"name": contentTypePlain,
"novalidate": contentTypeUnsafe,
// Skip handler names from
// http://www.w3.org/TR/html5/webappapis.html#event-handlers-on-elements,-document-objects,-and-window-objects
// since we have special handling in attrType.
"open": contentTypePlain,
"optimum": contentTypePlain,
"pattern": contentTypeUnsafe,
"placeholder": contentTypePlain,
"poster": contentTypeURL,
"profile": contentTypeURL,
"preload": contentTypePlain,
"pubdate": contentTypePlain,
"radiogroup": contentTypePlain,
"readonly": contentTypePlain,
"rel": contentTypeUnsafe,
"required": contentTypePlain,
"reversed": contentTypePlain,
"rows": contentTypePlain,
"rowspan": contentTypePlain,
"sandbox": contentTypeUnsafe,
"spellcheck": contentTypePlain,
"scope": contentTypePlain,
"scoped": contentTypePlain,
"seamless": contentTypePlain,
"selected": contentTypePlain,
"shape": contentTypePlain,
"size": contentTypePlain,
"sizes": contentTypePlain,
"span": contentTypePlain,
"src": contentTypeURL,
"srcdoc": contentTypeHTML,
"srclang": contentTypePlain,
"srcset": contentTypeSrcset,
"start": contentTypePlain,
"step": contentTypePlain,
"style": contentTypeCSS,
"tabindex": contentTypePlain,
"target": contentTypePlain,
"title": contentTypePlain,
"type": contentTypeUnsafe,
"usemap": contentTypeURL,
"value": contentTypeUnsafe,
"width": contentTypePlain,
"wrap": contentTypePlain,
"xmlns": contentTypeURL,
}
// attrType returns a conservative (upper-bound on authority) guess at the
// type of the lowercase named attribute.
func attrType(name string) contentType {
if strings.HasPrefix(name, "data-") {
// Strip data- so that custom attribute heuristics below are
// widely applied.
// Treat data-action as URL below.
name = name[5:]
} else if colon := strings.IndexRune(name, ':'); colon != -1 {
if name[:colon] == "xmlns" {
return contentTypeURL
}
// Treat svg:href and xlink:href as href below.
name = name[colon+1:]
}
if t, ok := attrTypeMap[name]; ok {
return t
}
// Treat partial event handler names as script.
if strings.HasPrefix(name, "on") {
return contentTypeJS
}
// Heuristics to prevent "javascript:..." injection in custom
// data attributes and custom attributes like g:tweetUrl.
// http://www.w3.org/TR/html5/dom.html#embedding-custom-non-visible-data-with-the-data-*-attributes
// "Custom data attributes are intended to store custom data
// private to the page or application, for which there are no
// more appropriate attributes or elements."
// Developers seem to store URL content in data URLs that start
// or end with "URI" or "URL".
if strings.Contains(name, "src") ||
strings.Contains(name, "uri") ||
strings.Contains(name, "url") {
return contentTypeURL
}
return contentTypePlain
}
|
