Remote Access Control

createrxhex.cpp

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// This file has been prepared for Doxygen automatic documentation generation.
#include "hexfile.h"
#include <sstream>
#include <iomanip>
#include <string>
#include <stdexcept>
#include <vector>
#include <fstream>



class ParameterParser
{
private:
        std::string m_filename; 
        size_t m_keySize; 
        size_t m_serialNoSize; 
        size_t m_counterSize; 
        std::vector< byte > m_sharedKey; 
        size_t m_maxTransmitters; 

        std::vector< byte > ParseHexString( const std::string & hexString ) const;
        std::string CreateHexString( const std::vector< byte > & byteVector ) const;

public:
        ParameterParser( size_t argc, const char * * argv );
        ~ParameterParser() {}

        //
        // Query methods.
        //
        const std::string & GetFilename() const { return m_filename; }
        size_t GetKeySize() const { return m_keySize; }
        size_t GetSerialNoSize() const { return m_serialNoSize; }
        size_t GetCounterSize() const { return m_counterSize; }
        const std::vector< byte > & GetSharedKey() const { return m_sharedKey; }
        size_t GetMaxTransmitters() const { return m_maxTransmitters; }

        std::string GetSharedKeyString() const { return CreateHexString( GetSharedKey() ); }
};



std::vector< byte > ParameterParser::ParseHexString( const std::string & hexString ) const
{
        // String must be even number of hex digits.
        if( hexString.size() % 2 != 0 ) {
                throw std::runtime_error( "Hex string does not have even character count" );
        }

        //
        // Parse hex digit pairs and insert into byte vector.
        //
        std::vector< byte > bytes;
        for( size_t idx = 0; idx < hexString.size(); idx += 2 ) {
                std::istringstream iss( hexString.substr( idx, 2 ) );
                byte data;
                iss >> std::hex >> data;
                if( !iss ) {
                        throw std::runtime_error( "Error parsing hex string \"" + hexString + "\"" );
                }
                bytes.push_back( data );
        }
        return bytes;
}



std::string ParameterParser::CreateHexString( const std::vector< byte > & byteVector ) const
{
        std::ostringstream oss;
        oss << std::setfill('0') << std::hex;

        // Add all byte last byte with spaces in between.
        for( size_t idx = 0; idx < byteVector.size() - 1; ++idx ) {
                oss << std::setw(2) << byteVector.at( idx ) << ' ';
        }

        // Add last byte.
        if( byteVector.size() > 0 ) {
                oss << std::setw(2) << byteVector.at( byteVector.size()-1 );
        }

        return oss.str();
}



ParameterParser::ParameterParser( size_t argc, const char * * argv )
{
        // Check that argument count is valid.
        if( argc != 7 ) {
                std::cout << "Parameters:\n"
                        "  filename        - Filename for resulting Intel HEX file\n"
                        "  keysize         - Size in bits of the AES secret and shared keys (128, 192 or 256)\n"
                        "  serialnosize    - Size in bytes of the serial number (1, 2 or 4)\n"
                        "  countersize     - Size in bytes of the sequential counter (1, 2 or 4)\n"
                        "  sharedkey       - Hex representation of the shared key (32, 48 or 64 digits)\n"
                        "  maxtransmitters - Maximum number of associated transmitters\n"
                        << std::endl;
                throw std::runtime_error( "Not exactly 6 parameters" );
        }

        //
        // Create strings or string streams from argument character arrays.
        //
        std::string arg1( argv[1] ); // Filename
        std::istringstream arg2( argv[2] ); // Key size
        std::istringstream arg3( argv[3] ); // Serial no size
        std::istringstream arg4( argv[4] ); // Counter size
        std::string arg5( argv[5] ); // Shared key
        std::istringstream arg6( argv[6] ); // Max transmitters

        //
        // Copy string arguments and parse non-string arguments.
        //
        m_filename = arg1;

        arg2 >> m_keySize;
        if( !arg2 ) {
                throw std::runtime_error( "Error parsing key size argument" );
        }

        arg3 >> m_serialNoSize;
        if( !arg3 ) {
                throw std::runtime_error( "Error parsing serial no size argument" );
        }

        arg4 >> m_counterSize;
        if( !arg4 ) {
                throw std::runtime_error( "Error parsing counter size argument" );
        }

        m_sharedKey = ParseHexString( arg5 );

        arg6 >> m_maxTransmitters;
        if( !arg6 ) {
                throw std::runtime_error( "Error parsing max transmitters argument" );
        }

        //
        // Check argument validity.
        //
        if( m_keySize != 128 && m_keySize != 192 && m_keySize != 256 ) {
                throw std::runtime_error( "Key size is not 128, 192 or 256 bits" );
        }

        if( m_serialNoSize != 1 && m_serialNoSize != 2 && m_serialNoSize != 4 ) {
                throw std::runtime_error( "Serial no is not 1, 2 or 4 bytes" );
        }

        if( m_counterSize != 1 && m_counterSize != 2 && m_counterSize != 4 ) {
                throw std::runtime_error( "Counter is not 1, 2 or 4 bytes" );
        }

        if( m_sharedKey.size() != m_keySize / 8 ) {
                throw std::runtime_error( "Shared key has invalid length" );
        }
}



void CreateHEXFile( const ParameterParser & parser )
{
        HEXFile hexData;
        std::ofstream outFile( parser.GetFilename().c_str() );

        // Prepare shared key bytes.
        HEXRecord sharedKey;
        sharedKey << parser.GetSharedKey();

        // Prepare transmitter count byte.
        HEXRecord transmitterCount;
        transmitterCount << ((byte) 0x00);

        // Prepare empty transmitter table entry.
        HEXRecord transmitterTableEntry;
        const size_t entrySize =
                (parser.GetKeySize() / 8) +
                parser.GetSerialNoSize() +
                parser.GetCounterSize();
        for( size_t idx = 0; idx < entrySize; ++idx ) {
                transmitterTableEntry << ((byte) 0xff); // Erased EEPROM cells.
        }

        // Add records to HEX file.
        hexData << sharedKey << transmitterCount;
        for( size_t idx = 0; idx < parser.GetMaxTransmitters(); ++idx ) {
                hexData << transmitterTableEntry;
        }

        // Write to disk.
        outFile << hexData;
}



int main( size_t argc, const char * * argv )
{
        try {
                ParameterParser parser( argc, argv );
                std::cout << "Filename        : " << parser.GetFilename() << std::endl
                        << "Key size        : " << parser.GetKeySize() << std::endl
                        << "Serial no size  : " << parser.GetSerialNoSize() << std::endl
                        << "Counter size    : " << parser.GetCounterSize() << std::endl
                        << "Shared key      : " << parser.GetSharedKeyString() << std::endl
                        << "Max transmitters: " << parser.GetMaxTransmitters() << std::endl;

                CreateHEXFile( parser );
                std::cout << std::endl << parser.GetFilename() << " created!" << std::endl;

        } catch( const std::exception & e ) {
                std::cout << "Error: " << e.what() << std::endl;
        } catch(...) {
                std::cout << "Unknown error" << std::endl;
        }
}