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// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This file defines utility functions for working with html.
#include <string>
#include <vector>
#include "base/basictypes.h"
#include "base/gtest_prod_util.h"
#include "net/http/http_util.h"
// Forward declarations
class HtmlUtilUnittest;
// Class designed to take a string of HTML and extract from it named
// attribute values from named tags.
// Caveat: this class currently doesn't handle multi-word UTF-16 encoded
// characters. Doesn't handle implies that any data following such a
// character could possibly be misinterpreted.
class HTMLScanner {
typedef std::wstring::const_iterator StrPos;
// Structure maintaining const_iterators into html_string_.
class StringRange {
friend class HTMLScanner;
StringRange(StrPos start, StrPos end);
bool LowerCaseEqualsASCII(const char* other) const;
bool Equals(const wchar_t* other) const;
// Copies the data described by StringRange into destination.
std::wstring Copy() const;
// If this StringRange represents a tag, this method extracts the name of
// the tag and sticks it in tag_name.
// Returns true if the tag name was successfully extracted.
// Returns false if this string doesn't look like a valid tag.
bool GetTagName(std::wstring* tag_name) const;
// From a given string range, uses a string tokenizer to extract the value
// of the named attribute if a simple scan finds that the attribute name is
// present.
// Returns true if the named attribute can be located and it has a value
// which has been placed in attribute_value.
// Note that the attribute value is unquoted here as well, so that
// GetTagAttribute(*<foo bar="baz">*, L"bar", *out_value*) will stick
// 'bar' in out_value and not '"bar"'.
// Returns false if the named attribute is not present in the tag or if it
// did not have a value.
bool GetTagAttribute(const wchar_t* attribute_name,
StringRange* attribute_value) const;
// Unquotes a StringRange by removing a matching pair of either ' or "
// characters from the beginning and end of the string if present.
// Returns true if string was modified, false otherwise.
bool UnQuote();
StrPos start_;
StrPos end_;
typedef std::vector<StringRange> StringRangeList;
// html_string must be a null-terminated string containing the HTML
// to be scanned.
explicit HTMLScanner(const wchar_t* html_string);
// Returns the set of ranges denoting HTML tags that match the given name.
// If stop_tag_name is given, then as soon as a tag with this name is
// encountered this method will return.
void GetTagsByName(const wchar_t* name, StringRangeList* tag_list,
const wchar_t* stop_tag_name);
friend class HtmlUtilUnittest;
FRIEND_TEST_ALL_PREFIXES(HtmlUtilUnittest, BasicTest);
// Given html_string which represents the remaining html range, this method
// returns the next tag in tag and advances html_string to one character after
// the end of tag. This method is intended to be called repeatedly to extract
// all of the tags in sequence.
// Returns true if another tag was found and 'tag' was populated with a valid
// range.
// Returns false if we have reached the end of the html data.
bool NextTag(StringRange* html_string, StringRange* tag);
// Returns true if c can be found in quotes_, false otherwise
bool IsQuote(wchar_t c);
// Returns true if pos refers to the last character in an HTML comment in a
// string described by html_string, false otherwise.
// For example with html_string describing <!-- foo> -->, pos must refer to
// the last > for this method to return true.
bool IsHTMLCommentClose(const StringRange* html_string, StrPos pos);
// Returns true if pos refers to the last character in the terminator of the
// opening tag of a downlevel-hidden conditional comment in IE as per
// For example with html_string describing <![if booga >wooga]>, pos must
// refer to the last > for this method to return true.
bool IsIEConditionalCommentClose(const StringRange* html_string, StrPos pos);
// We store a (CollapsedWhitespace'd) copy of the html data.
const std::wstring html_string_;
// Store the string of quote characters to avoid repeated construction.
const std::wstring quotes_;
namespace http_utils {
// Adds "chromeframe/x.y" to the end of the User-Agent string (x.y is the
// version). If the cf tag has already been added to the string,
// the original string is returned.
std::string AddChromeFrameToUserAgentValue(const std::string& value);
// Fetches the user agent from urlmon and adds chrome frame to the
// comment section.
// NOTE: The returned string includes the "User-Agent: " header name.
std::string GetDefaultUserAgentHeaderWithCFTag();
// Returns the User-Agent header as would be used by Chrome itself.
const char* GetChromeUserAgent();
// Fetches the default user agent string from urlmon.
// This value does not include the "User-Agent:" header name.
std::string GetDefaultUserAgent();
// Returns the Chrome Frame user agent. E.g. "chromeframe/1.0".
// Note that in unit tests this will be "chromeframe/0.0" due to the version
// table not being present in the unit test executable.
const char* GetChromeFrameUserAgent();
// Returns true if there is a frame busting header (other than the do-nothing
// "X-Frame-Options: ALLOWALL") in the provided header block. Note that there
// may be multiple X-Frame-Options values specified; if there is one anywhere in
// the list with a value other than ALLOWALL, this returns true.
bool HasFrameBustingHeader(const std::string& http_headers);
// Returns the header passed in from the headers list.
std::string GetHttpHeaderFromHeaderList(const std::string& header_name,
const std::string& headers);
} // namespace http_utils