1/*
2 * Copyright (C) 2010 Google Inc. All Rights Reserved.
3 * Copyright (C) 2015-2017 Apple Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include "config.h"
28#include "HTMLMetaCharsetParser.h"
29
30#include "HTMLNames.h"
31#include "HTMLParserIdioms.h"
32#include "TextCodec.h"
33#include "TextEncodingRegistry.h"
34
35namespace WebCore {
36
37using namespace HTMLNames;
38
39HTMLMetaCharsetParser::HTMLMetaCharsetParser()
40 : m_codec(newTextCodec(Latin1Encoding()))
41{
42}
43
44static StringView extractCharset(const String& value)
45{
46 unsigned length = value.length();
47 for (size_t pos = 0; pos < length; ) {
48 pos = value.findIgnoringASCIICase("charset", pos);
49 if (pos == notFound)
50 break;
51
52 static const size_t charsetLength = sizeof("charset") - 1;
53 pos += charsetLength;
54
55 // Skip whitespace.
56 while (pos < length && value[pos] <= ' ')
57 ++pos;
58
59 if (value[pos] != '=')
60 continue;
61
62 ++pos;
63
64 while (pos < length && value[pos] <= ' ')
65 ++pos;
66
67 UChar quoteMark = 0;
68 if (pos < length && (value[pos] == '"' || value[pos] == '\''))
69 quoteMark = value[pos++];
70
71 if (pos == length)
72 break;
73
74 unsigned end = pos;
75 while (end < length && ((quoteMark && value[end] != quoteMark) || (!quoteMark && value[end] > ' ' && value[end] != '"' && value[end] != '\'' && value[end] != ';')))
76 ++end;
77
78 if (quoteMark && (end == length))
79 break; // Close quote not found.
80
81 return StringView(value).substring(pos, end - pos);
82 }
83 return StringView();
84}
85
86bool HTMLMetaCharsetParser::processMeta(HTMLToken& token)
87{
88 AttributeList attributes;
89 for (auto& attribute : token.attributes()) {
90 String attributeName = StringImpl::create8BitIfPossible(attribute.name);
91 String attributeValue = StringImpl::create8BitIfPossible(attribute.value);
92 attributes.append(std::make_pair(attributeName, attributeValue));
93 }
94
95 m_encoding = encodingFromMetaAttributes(attributes);
96 return m_encoding.isValid();
97}
98
99TextEncoding HTMLMetaCharsetParser::encodingFromMetaAttributes(const AttributeList& attributes)
100{
101 bool gotPragma = false;
102 enum { None, Charset, Pragma } mode = None;
103 StringView charset;
104
105 for (auto& attribute : attributes) {
106 const String& attributeName = attribute.first;
107 const String& attributeValue = attribute.second;
108
109 if (attributeName == http_equivAttr) {
110 if (equalLettersIgnoringASCIICase(attributeValue, "content-type"))
111 gotPragma = true;
112 } else if (charset.isEmpty()) {
113 if (attributeName == charsetAttr) {
114 charset = attributeValue;
115 mode = Charset;
116 } else if (attributeName == contentAttr) {
117 charset = extractCharset(attributeValue);
118 if (charset.length())
119 mode = Pragma;
120 }
121 }
122 }
123
124 if (mode == Charset || (mode == Pragma && gotPragma))
125 return TextEncoding(stripLeadingAndTrailingHTMLSpaces(charset.toStringWithoutCopying()));
126
127 return TextEncoding();
128}
129
130bool HTMLMetaCharsetParser::checkForMetaCharset(const char* data, size_t length)
131{
132 if (m_doneChecking)
133 return true;
134
135 ASSERT(!m_encoding.isValid());
136
137 // We still don't have an encoding, and are in the head.
138 // The following tags are allowed in <head>:
139 // SCRIPT|STYLE|META|LINK|OBJECT|TITLE|BASE
140 //
141 // We stop scanning when a tag that is not permitted in <head>
142 // is seen, rather when </head> is seen, because that more closely
143 // matches behavior in other browsers; more details in
144 // <http://bugs.webkit.org/show_bug.cgi?id=3590>.
145 //
146 // Additionally, we ignore things that looks like tags in <title>, <script>
147 // and <noscript>; see <http://bugs.webkit.org/show_bug.cgi?id=4560>,
148 // <http://bugs.webkit.org/show_bug.cgi?id=12165> and
149 // <http://bugs.webkit.org/show_bug.cgi?id=12389>.
150 //
151 // Since many sites have charset declarations after <body> or other tags
152 // that are disallowed in <head>, we don't bail out until we've checked at
153 // least bytesToCheckUnconditionally bytes of input.
154
155 constexpr int bytesToCheckUnconditionally = 1024;
156
157 bool ignoredSawErrorFlag;
158 m_input.append(m_codec->decode(data, length, false, false, ignoredSawErrorFlag));
159
160 while (auto token = m_tokenizer.nextToken(m_input)) {
161 bool isEnd = token->type() == HTMLToken::EndTag;
162 if (isEnd || token->type() == HTMLToken::StartTag) {
163 AtomicString tagName(token->name());
164 if (!isEnd) {
165 m_tokenizer.updateStateFor(tagName);
166 if (tagName == metaTag && processMeta(*token)) {
167 m_doneChecking = true;
168 return true;
169 }
170 }
171
172 if (tagName != scriptTag && tagName != noscriptTag
173 && tagName != styleTag && tagName != linkTag
174 && tagName != metaTag && tagName != objectTag
175 && tagName != titleTag && tagName != baseTag
176 && (isEnd || tagName != htmlTag)
177 && (isEnd || tagName != headTag)) {
178 m_inHeadSection = false;
179 }
180 }
181
182 if (!m_inHeadSection && m_input.numberOfCharactersConsumed() >= bytesToCheckUnconditionally) {
183 m_doneChecking = true;
184 return true;
185 }
186 }
187
188 return false;
189}
190
191}
192