libkiwix/src/server/etag.h

86 lines
2.5 KiB
C++

/*
* Copyright 2020 Veloman Yunkan <veloman.yunkan@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#ifndef KIWIXLIB_SERVER_ETAG_H
#define KIWIXLIB_SERVER_ETAG_H
#include <string>
namespace kiwix {
// The ETag string used by Kiwix server (more precisely, its value inside the
// double quotes) consists of two parts:
//
// 1. ServerId - The string obtained on server start up
//
// 2. Options - Zero or more characters encoding the values of some of the
// headers of the response
//
// The two parts are separated with a slash (/) symbol (which is always present,
// even when the the options part is empty). Neither portion of a Kiwix ETag
// may contain the slash symbol.
// Examples of valid Kiwix server ETags (including the double quotes):
//
// "abcdefghijklmn/"
// "1234567890/z"
// "1234567890/cz"
//
// The options part of the Kiwix ETag allows to correctly set the required
// headers when responding to a conditional If-None-Match request with a 304
// (Not Modified) response without following the full code path that would
// discover the necessary options.
class ETag
{
public: // types
enum Option {
CACHEABLE_ENTITY,
COMPRESSED_CONTENT,
OPTION_COUNT
};
public: // functions
ETag() {}
void set_server_id(const std::string& id) { m_serverId = id; }
void set_option(Option opt);
explicit operator bool() const { return !m_serverId.empty(); }
bool get_option(Option opt) const;
std::string get_etag() const;
static ETag match(const std::string& etags, const std::string& server_id);
private: // functions
ETag(const std::string& serverId, const std::string& options);
static ETag parse(std::string s);
private: // data
std::string m_serverId;
std::string m_options;
};
} // namespace kiwix
#endif // KIWIXLIB_SERVER_ETAG_H