1/*
2 * Copyright (C) 2010 Google Inc. All Rights Reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "core/html/parser/HTMLMetaCharsetParser.h"
28
29#include "core/HTMLNames.h"
30#include "core/html/parser/HTMLParserIdioms.h"
31#include "core/html/parser/HTMLParserOptions.h"
32#include "core/html/parser/HTMLTokenizer.h"
33#include "wtf/text/TextEncodingRegistry.h"
34#include "wtf/text/WTFString.h"
35
36using namespace WTF;
37
38namespace blink {
39
40using namespace HTMLNames;
41
42HTMLMetaCharsetParser::HTMLMetaCharsetParser()
43    : m_tokenizer(HTMLTokenizer::create(HTMLParserOptions(0)))
44    , m_assumedCodec(newTextCodec(Latin1Encoding()))
45    , m_inHeadSection(true)
46    , m_doneChecking(false)
47{
48}
49
50HTMLMetaCharsetParser::~HTMLMetaCharsetParser()
51{
52}
53
54bool HTMLMetaCharsetParser::processMeta()
55{
56    const HTMLToken::AttributeList& tokenAttributes = m_token.attributes();
57    HTMLAttributeList attributes;
58    for (HTMLToken::AttributeList::const_iterator iter = tokenAttributes.begin(); iter != tokenAttributes.end(); ++iter) {
59        String attributeName = attemptStaticStringCreation(iter->name, Likely8Bit);
60        String attributeValue = StringImpl::create8BitIfPossible(iter->value);
61        attributes.append(std::make_pair(attributeName, attributeValue));
62    }
63
64    m_encoding = encodingFromMetaAttributes(attributes);
65    return m_encoding.isValid();
66}
67
68static const int bytesToCheckUnconditionally = 1024; // That many input bytes will be checked for meta charset even if <head> section is over.
69
70bool HTMLMetaCharsetParser::checkForMetaCharset(const char* data, size_t length)
71{
72    if (m_doneChecking)
73        return true;
74
75    ASSERT(!m_encoding.isValid());
76
77    // We still don't have an encoding, and are in the head.
78    // The following tags are allowed in <head>:
79    // SCRIPT|STYLE|META|LINK|OBJECT|TITLE|BASE
80
81    // We stop scanning when a tag that is not permitted in <head>
82    // is seen, rather when </head> is seen, because that more closely
83    // matches behavior in other browsers; more details in
84    // <http://bugs.webkit.org/show_bug.cgi?id=3590>.
85
86    // Additionally, we ignore things that looks like tags in <title>, <script>
87    // and <noscript>; see <http://bugs.webkit.org/show_bug.cgi?id=4560>,
88    // <http://bugs.webkit.org/show_bug.cgi?id=12165> and
89    // <http://bugs.webkit.org/show_bug.cgi?id=12389>.
90
91    // Since many sites have charset declarations after <body> or other tags
92    // that are disallowed in <head>, we don't bail out until we've checked at
93    // least bytesToCheckUnconditionally bytes of input.
94
95    m_input.append(SegmentedString(m_assumedCodec->decode(data, length)));
96
97    while (m_tokenizer->nextToken(m_input, m_token)) {
98        bool end = m_token.type() == HTMLToken::EndTag;
99        if (end || m_token.type() == HTMLToken::StartTag) {
100            String tagName = attemptStaticStringCreation(m_token.name(), Likely8Bit);
101            if (!end) {
102                m_tokenizer->updateStateFor(tagName);
103                if (threadSafeMatch(tagName, metaTag) && processMeta()) {
104                    m_doneChecking = true;
105                    return true;
106                }
107            }
108
109            if (!threadSafeMatch(tagName, scriptTag) && !threadSafeMatch(tagName, noscriptTag)
110                && !threadSafeMatch(tagName, styleTag) && !threadSafeMatch(tagName, linkTag)
111                && !threadSafeMatch(tagName, metaTag) && !threadSafeMatch(tagName, objectTag)
112                && !threadSafeMatch(tagName, titleTag) && !threadSafeMatch(tagName, baseTag)
113                && (end || !threadSafeMatch(tagName, htmlTag)) && (end || !threadSafeMatch(tagName, headTag))) {
114                m_inHeadSection = false;
115            }
116        }
117
118        if (!m_inHeadSection && m_input.numberOfCharactersConsumed() >= bytesToCheckUnconditionally) {
119            m_doneChecking = true;
120            return true;
121        }
122
123        m_token.clear();
124    }
125
126    return false;
127}
128
129}
130