mirror of https://github.com/kiwix/libkiwix.git
136 lines
3.3 KiB
C++
136 lines
3.3 KiB
C++
/*
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* Copyright 2020 Veloman Yunkan <veloman.yunkan@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#include "etag.h"
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#include "tools/stringTools.h"
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#include <algorithm>
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#include <sstream>
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namespace kiwix {
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namespace {
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// Characters in the options part of the ETag could in principle be picked up
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// from the latin alphabet in natural order (the character corresponding to
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// ETag::Option opt would be 'a'+opt; that would somewhat simplify the code in
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// this file). However it is better to have some mnemonics in the option names,
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// hence below variable: all_options[opt] corresponds to the character going
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// into the ETag for ETag::Option opt.
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// IMPORTANT: The characters in all_options must come in sorted order (so that
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// IMPORTANT: isValidOptionsString() works correctly).
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const char all_options[] = "Zz";
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static_assert(ETag::OPTION_COUNT == sizeof(all_options) - 1, "");
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bool isValidETagBody(const std::string& s)
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{
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return !s.empty() && s.find_first_of("\"/") == std::string::npos;
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}
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bool isSubsequenceOf(const std::string& s, const std::string& sortedString)
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{
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std::string::size_type i = 0;
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for ( const char c : s )
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{
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const std::string::size_type j = sortedString.find(c, i);
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if ( j == std::string::npos )
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return false;
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i = j+1;
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}
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return true;
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}
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bool isValidOptionsString(const std::string& s)
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{
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return isSubsequenceOf(s, all_options);
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}
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} // namespace
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void ETag::set_option(Option opt)
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{
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if ( ! get_option(opt) )
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{
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m_options.push_back(all_options[opt]);
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std::sort(m_options.begin(), m_options.end());
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}
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}
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bool ETag::get_option(Option opt) const
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{
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return m_options.find(all_options[opt]) != std::string::npos;
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}
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std::string ETag::get_etag() const
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{
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if ( m_body.empty() )
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return std::string();
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return "\"" + m_body + "/" + m_options + "\"";
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}
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ETag::ETag(const std::string& body, const std::string& options)
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{
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if ( isValidETagBody(body) && isValidOptionsString(options) )
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{
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m_body = body;
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m_options = options;
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}
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}
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ETag ETag::parse(std::string s)
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{
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if ( kiwix::startsWith("W/", s) )
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s = s.substr(2);
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if ( s.front() != '"' || s.back() != '"' )
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return ETag();
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s = s.substr(1, s.size()-2);
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const std::string::size_type i = s.find('/');
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if ( i == std::string::npos )
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return ETag();
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return ETag(s.substr(0, i), s.substr(i+1));
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}
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ETag ETag::match(const std::string& etags, const std::string& body)
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{
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std::istringstream ss(etags);
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std::string etag_str;
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while ( ss >> etag_str )
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{
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if ( etag_str.back() == ',' )
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etag_str.pop_back();
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const ETag etag = parse(etag_str);
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if ( etag && etag.m_body == body )
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return etag;
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}
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return ETag();
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}
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} // namespace kiwix
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