//! \brief Generates Bittorrent Guid from Guid, using PeerProject's special signature.
inline BtGuid transformGuid(const Guid& other)
{
BtGuid result;
memcpy( &result[ 0 ], &other[ 0 ], result.byteCount );
*( result.end() - 1 ) = *other.begin() ^ swapEndianess( *( other.end() - 1 ) );
result.validate();
return result;
}
bool CCarProtocol::getBytes(alt_u8 *pPacket)
{
alt_u16 uiLength = (alt_u16) getLength();
alt_u16 uiOffset = 8;
if(!m_bValid)
return m_bValid;
pPacket[0] = 'C'; pPacket[1] = 'A'; pPacket[2] = 'R'; pPacket[3] = 'P';
*((alt_u16*) (pPacket+4)) = m_uiPacketNumber;
swapEndianess(pPacket+4, 2);
*((alt_u16*) (pPacket+6)) = uiLength-8;
swapEndianess(pPacket+6, 2);
for(alt_u32 i = 0; i < m_uiMessageCount; i++)
{
m_bValid &= m_pMessages[i]->getBytes(pPacket+uiOffset);
uiOffset += m_pMessages[i]->getLength();
}
return m_bValid;
}
/*
* Parsing method called by the constructors.
* Important note:
* >>>>>> You have to edit this method if there are new sensors / messages <<<<<
*
* Additional note:
* Even if there are more packets in the byte stream, only the first occurrence is used. All other
* packets will be ignored!
*
* pPacket: byte array containing the byte (network) representation of the packet.
* iLength: length of the byte stream.
*/
void CCarProtocol::parsePacket(alt_u8 *pPacket, int iLength)
{
alt_u16 uiStartIdx; // Index of the 'C' (start of the packet) in byte array
// Will be increment to the current working point!
alt_u16 uiPayloadLength; // Payload length as read out of the byte array
alt_u16 uiPayloadOffset; // Current working point for parsing of the next message
// Will be increment along the message lengths!
// Check Minimum Length 8 (which is the packet-header)
if(iLength < 8)
return;
// Search for 'C' 'A' 'R' 'P'
for(uiStartIdx = 0; uiStartIdx < iLength; uiStartIdx++)
{
if(pPacket[uiStartIdx] == 'C' && pPacket[uiStartIdx+1] == 'A' && pPacket[uiStartIdx+2] == 'R' && pPacket[uiStartIdx+3] == 'P')
break;
}
// Enough space for the header?
if(uiStartIdx + 8 > iLength)
return;
// Here starts the parsing:
// Parse the payload-Length
uiPayloadLength = *((alt_u16*) (pPacket+uiStartIdx+6));
swapEndianess((alt_u8*) &uiPayloadLength, 2);
// Parse the PacketNumber
m_uiPacketNumber = *((alt_u16*) (pPacket+uiStartIdx+4));
swapEndianess((alt_u8*) &m_uiPacketNumber, 2);
// Set the initial member values
m_bValid = true;
m_uiMessageCount = 0;
// Is there a payload?
if(uiPayloadLength > 0)
{
// Enough space for the payload?
if(uiStartIdx+8+uiPayloadLength > iLength)
{
m_bThereIsMore = true;
m_bValid = false;
return;
}
// Increment uiStartIdx to the working point (the first message position)
uiStartIdx += 8;
// Initialize uiPayloadOffset to 0
uiPayloadOffset = 0;
// Do as long there are messages (payload bytes) left and the count of messages dont exceeds 8.
while(uiPayloadOffset < uiPayloadLength && m_uiMessageCount < 8)
{
// Parse the message type and switch along it
switch(pPacket[uiStartIdx + uiPayloadOffset])
{
// The following cases parse the message along there type in different classes.
// TODO: Add new message classes here!!!!!
// WelcomeMessage
case 0x01:
m_pMessages[m_uiMessageCount] = new CWelcomeMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 12;
m_uiMessageCount++;
break;
// MotorVelocity
case 0x04:
m_pMessages[m_uiMessageCount] = new CMotorVelocityMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 8;
m_uiMessageCount++;
break;
// MotorMeasurement
case 0x05:
m_pMessages[m_uiMessageCount] = new CMotorMeasurementMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 16;
m_uiMessageCount++;
break;
// Ultrasound-Sensor
case 0x08:
m_pMessages[m_uiMessageCount] = new CUltrasoundDistanceMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 8;
m_uiMessageCount++;
break;
// Acceleration-Sensor
case 0x09:
m_pMessages[m_uiMessageCount] = new CAccelerationValuesMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 12;
m_uiMessageCount++;
break;
// ADC-Sensor
case 0x0A:
// If subtype is 0 then it's a InfoMessage otherwise a ValuesMessage
if(pPacket[uiStartIdx + uiPayloadOffset+2] == 0)
m_pMessages[m_uiMessageCount] = new CADCInfoMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
else
m_pMessages[m_uiMessageCount] = new CADCValuesMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
// Make sure you add the right length to the offset!
uiPayloadOffset += m_pMessages[m_uiMessageCount]->getLength();
m_uiMessageCount++;
break;
// Velocity msg (incoming)-->other car tells us his velocity
case 0x10: // TODO
{
m_pMessages[m_uiMessageCount] = new CVelocityMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 12;
m_uiMessageCount++;
break;
}
//do emergency braking
case C2X_MSGID_EMERGENCY_BRAKE:
{
m_pMessages[m_uiMessageCount] = new CEmergencyBrakeMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 12;
m_uiMessageCount++;
break;
}
//set motor speeds from external source
case C2X_MSGID_CONTROL: // remote control/autonomous driving mode TODO: implement control function somewhere
{
m_pMessages[m_uiMessageCount] = new CControlMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 12;
m_uiMessageCount++;
break;
}
//tell our state
case C2X_MSGID_INFO_STATE:
{
m_pMessages[m_uiMessageCount] = new CInfoStateMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 12;
m_uiMessageCount++;
break;
}
//tell our sensor data
case C2X_MSGID_INFO_SENSORS:
{
m_pMessages[m_uiMessageCount] = new CInfoSensorMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 12;
m_uiMessageCount++;
break;
}
//set external source as controlling unit
case C2X_MSGID_REMOTE_CONTROL:
{
m_pMessages[m_uiMessageCount] = new CRemoteControlMessage(pPacket+uiStartIdx+uiPayloadOffset, uiPayloadLength-uiPayloadOffset);
uiPayloadOffset += 12;
m_uiMessageCount++;
break;
}
// Message ID is not known, so we also don't know the length of this message.
// We can't parse further, as we don't know the starting point of the next message.
// Set m_bValid false and return immediate!
default:
m_bValid = false;
return;
}
}
}
}
/**
Converts the endianess of the given variable from native to big, if needed.
@param v input value.
@return converted value.
*/
template <class T> static T nativeToBigEndian(T v) {
return !isLittleEndian() ? v : swapEndianess(v);
}
/**
Converts the endianess of the given variable from big to native, if needed.
@param v input value.
@return converted value.
*/
template <class T> static T bigToNativeEndian(T v) {
return !isLittleEndian() ? v : swapEndianess(v);
}
//! \brief Predicate checking if a given Bittorrent Guid uses a
//! special signature to signal it belongs to PeerProject/Shareaza client.
inline bool isExtendedBtGuid(const BtGuid& hash)
{
return hash.isValid() &&
*( hash.end() - 1 ) == ( *hash.begin() ^ swapEndianess( *( hash.end() - 2 ) ) );
}
