gpsprotocol.cpp

/*

	ent-ghost
	Copyright [2011-2013] [Jack Lu]

	This file is part of the ent-ghost source code.

	ent-ghost 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
	(at your option) any later version.

	ent-ghost source code 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 ent-ghost source code. If not, see <http://www.gnu.org/licenses/>.

	ent-ghost is modified from GHost++ (http://ghostplusplus.googlecode.com/)
	GHost++ is Copyright [2008] [Trevor Hogan]

*/

#include "ghost.h"
#include "util.h"
#include "gpsprotocol.h"

//
// CGPSProtocol
//

CGPSProtocol :: CGPSProtocol( )
{

}

CGPSProtocol :: ~CGPSProtocol( )
{

}

///////////////////////
// RECEIVE FUNCTIONS //
///////////////////////

////////////////////
// SEND FUNCTIONS //
////////////////////

BYTEARRAY CGPSProtocol :: SEND_GPSC_INIT( uint32_t version )
{
	BYTEARRAY packet;
	packet.push_back( GPS_HEADER_CONSTANT );
	packet.push_back( GPS_INIT );
	packet.push_back( 0 );
	packet.push_back( 0 );
	UTIL_AppendByteArray( packet, version, false );
	AssignLength( packet );
	return packet;
}

BYTEARRAY CGPSProtocol :: SEND_GPSC_RECONNECT( unsigned char PID, uint32_t reconnectKey, uint32_t lastPacket )
{
	BYTEARRAY packet;
	packet.push_back( GPS_HEADER_CONSTANT );
	packet.push_back( GPS_RECONNECT );
	packet.push_back( 0 );
	packet.push_back( 0 );
	packet.push_back( PID );
	UTIL_AppendByteArray( packet, reconnectKey, false );
	UTIL_AppendByteArray( packet, lastPacket, false );
	AssignLength( packet );
	return packet;
}

BYTEARRAY CGPSProtocol :: SEND_GPSC_ACK( uint32_t lastPacket )
{
	BYTEARRAY packet;
	packet.push_back( GPS_HEADER_CONSTANT );
	packet.push_back( GPS_ACK );
	packet.push_back( 0 );
	packet.push_back( 0 );
	UTIL_AppendByteArray( packet, lastPacket, false );
	AssignLength( packet );
	return packet;
}

BYTEARRAY CGPSProtocol :: SEND_GPSS_INIT( uint16_t reconnectPort, unsigned char PID, uint32_t reconnectKey, unsigned char numEmptyActions )
{
	BYTEARRAY packet;
	packet.push_back( GPS_HEADER_CONSTANT );
	packet.push_back( GPS_INIT );
	packet.push_back( 0 );
	packet.push_back( 0 );
	UTIL_AppendByteArray( packet, reconnectPort, false );
	packet.push_back( PID );
	UTIL_AppendByteArray( packet, reconnectKey, false );
	packet.push_back( numEmptyActions );
	AssignLength( packet );
	return packet;
}

BYTEARRAY CGPSProtocol :: SEND_GPSS_RECONNECT( uint32_t lastPacket )
{
	BYTEARRAY packet;
	packet.push_back( GPS_HEADER_CONSTANT );
	packet.push_back( GPS_RECONNECT );
	packet.push_back( 0 );
	packet.push_back( 0 );
	UTIL_AppendByteArray( packet, lastPacket, false );
	AssignLength( packet );
	return packet;
}

BYTEARRAY CGPSProtocol :: SEND_GPSS_ACK( uint32_t lastPacket )
{
	BYTEARRAY packet;
	packet.push_back( GPS_HEADER_CONSTANT );
	packet.push_back( GPS_ACK );
	packet.push_back( 0 );
	packet.push_back( 0 );
	UTIL_AppendByteArray( packet, lastPacket, false );
	AssignLength( packet );
	return packet;
}

BYTEARRAY CGPSProtocol :: SEND_GPSS_REJECT( uint32_t reason )
{
	BYTEARRAY packet;
	packet.push_back( GPS_HEADER_CONSTANT );
	packet.push_back( GPS_REJECT );
	packet.push_back( 0 );
	packet.push_back( 0 );
	UTIL_AppendByteArray( packet, reason, false );
	AssignLength( packet );
	return packet;
}

/////////////////////
// OTHER FUNCTIONS //
/////////////////////

bool CGPSProtocol :: AssignLength( BYTEARRAY &content )
{
	// insert the actual length of the content array into bytes 3 and 4 (indices 2 and 3)

	BYTEARRAY LengthBytes;

	if( content.size( ) >= 4 && content.size( ) <= 65535 )
	{
		LengthBytes = UTIL_CreateByteArray( (uint16_t)content.size( ), false );
		content[2] = LengthBytes[0];
		content[3] = LengthBytes[1];
		return true;
	}

	return false;
}

bool CGPSProtocol :: ValidateLength( BYTEARRAY &content )
{
	// verify that bytes 3 and 4 (indices 2 and 3) of the content array describe the length

	uint16_t Length;
	BYTEARRAY LengthBytes;

	if( content.size( ) >= 4 && content.size( ) <= 65535 )
	{
		LengthBytes.push_back( content[2] );
		LengthBytes.push_back( content[3] );
		Length = UTIL_ByteArrayToUInt16( LengthBytes, false );

		if( Length == content.size( ) )
			return true;
	}

	return false;
}