HttpParser.h

/*
 *  Copyright (C) 2011-2018 Team Kodi
 *  This file is part of Kodi - https://kodi.tv
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 *  See LICENSES/README.md for more information.
 *
 *  This code implements parsing of HTTP requests.
 *  This code was written by Steve Hanov in 2009, no copyright is claimed.
 *  This code is in the public domain.
 *  Code was taken from http://refactormycode.com/codes/778-an-efficient-http-parser
 */

#pragma once

#include <stdlib.h>
#include <string.h>
#include <string>
#include <vector>

// A class to incrementally parse an HTTP header as it comes in. It
// lets you know when it has received all required bytes, as specified
// by the content-length header (if present). If there is no content-length,
// it will stop reading after the final "\n\r".
//
// Example usage:
//
//    HttpParser parser;
//    HttpParser::status_t status;
//
//    for( ;; ) {
//        // read bytes from socket into buffer, break on error
//        status = parser.addBytes( buffer, length );
//        if ( status != HttpParser::Incomplete ) break;
//    }
//
//    if ( status == HttpParser::Done ) {
//        // parse fully formed http message.
//    }


class HttpParser
{
public:
    ~HttpParser();

    enum status_t {
        Done,
        Error,
        Incomplete
    };

    status_t addBytes( const char* bytes, unsigned len );

    const char* getMethod() const;
    const char* getUri() const;
    const char* getQueryString() const;
    const char* getBody() const;
    // key should be in lower case when looking up.
    const char* getValue( const char* key ) const;
    unsigned getContentLength() const;

private:
    void parseHeader();
    bool parseRequestLine();

    std::string _data;
    unsigned _headerStart = 0;
    unsigned _parsedTo =  0 ;
    int _state =  0 ;
    unsigned _keyIndex = 0;
    unsigned _valueIndex = 0;
    unsigned _contentLength = 0;
    unsigned _contentStart = 0;
    unsigned _uriIndex = 0;

    typedef std::vector<unsigned> IntArray;
    IntArray _keys;

    enum State {
        p_request_line=0,
        p_request_line_cr=1,
        p_request_line_crlf=2,
        p_request_line_crlfcr=3,
        p_key=4,
        p_key_colon=5,
        p_key_colon_sp=6,
        p_value=7,
        p_value_cr=8,
        p_value_crlf=9,
        p_value_crlfcr=10,
        p_content=11, // here we are done parsing the header.
        p_error=12 // here an error has occurred and the parse failed.
    };

    status_t _status =  Incomplete ;
};