public bool DecodeBACnet(byte[] buffer, int totalMessageLength)
{
int offset = 0;
try
{
// this whole section http://www.bacnetwiki.com/wiki/index.php?title=BACnet_Virtual_Link_Control
ADR sadr = null;
if (buffer[offset] != BACnetEnums.BACNET_BVLC_TYPE_BIP)
{
// todo3, panic log
_apm.MessageProtocolError("m0013 - Not a BACnet/IP message");
return(false);
}
// we could receive an original broadcast, a unicast, a forwarded here...
// BVLC Function Types. See http://www.bacnetwiki.com/wiki/index.php?title=BVLC_Function
switch ((BACnetEnums.BACNET_BVLC_FUNCTION)buffer[offset + 1])
{
case BACnetEnums.BACNET_BVLC_FUNCTION.BVLC_FORWARDED_NPDU:
npdu_offset = offset + 10;
break;
case BACnetEnums.BACNET_BVLC_FUNCTION.BVLC_ORIGINAL_UNICAST_NPDU:
case BACnetEnums.BACNET_BVLC_FUNCTION.BVLC_ORIGINAL_BROADCAST_NPDU:
// all these OK
npdu_offset = offset + 4;
break;
default:
BACnetLibraryCL.Panic("m0012 nosuch bvlc function");
break;
}
// Investigate the NPDU
// http://www.bacnetwiki.com/wiki/index.php?title=NPDU
if (buffer[npdu_offset] != BACnetEnums.BACNET_PROTOCOL_VERSION)
{
// we have a major problem, microprotocol version has changed. http://www.bacnetwiki.com/wiki/index.php?title=BACnet_Virtual_Link_Control
BACnetLibraryCL.Panic("m0011 BVLC microprotocol problem");
return(false);
}
// expecting reply?
if ((buffer[npdu_offset + 1] & 0x04) == 0x04)
{
npdu.expectingReply = true;
}
// destination address present?
// http://www.bacnetwiki.com/wiki/index.php?title=NPCI
if ((buffer[npdu_offset + 1] & 0x20) == 0x20)
{
//da_present = true;
dadr = new ADR();
// dnet, dadr and hop count present
int dAddrOffset = npdu_offset + 2;
dadr.Decode(buffer, ref dAddrOffset);
if (dadr.MACaddress.length == 0)
{
npdu.isBroadcast = true;
// broadcast, but check the DNET
if (dadr.networkNumber != 0xffff)
{
throw new Exception("m0010 - Broadcast according to DLEN, but DNET not 0xffff");
// todo, this means directed broadcast, need to deal with this still
}
}
if (dadr.MACaddress.length != 1 && dadr.MACaddress.length != 6 && dadr.MACaddress.length != 0)
{
// panic
throw new Exception("m0009 - Unexpected DADR len");
}
// todo, pick up variable length destination address
}
// Source address present?
// http://www.bacnetwiki.com/wiki/index.php?title=NPCI
if ((buffer[npdu_offset + 1] & 0x08) == 0x08)
{
//sa_present = true;
sadr = new ADR();
int sa_offset = npdu_offset + 2;
// however, if there is a destination address, move the sa_offset up appropriate amount
if (dadr != null)
{
sa_offset = npdu_offset + 2 + 3 + (int)dadr.MACaddress.length;
}
// means SADR, SNET present
sadr.Decode(buffer, ref sa_offset);
// SA exists (included MAC and so this means the received IP address needs to be the fromBIP
}
else
{
// at this point, if SADR not discovered within the NPDU, then the SADR MAC address is the Ethernet/IP fromaddress
// and the device can (must) be considered 'direcly connected'
if (directlyConnectedIPEndPointOfDevice != null)
{
// and even though the device is directly connected, because we are a router, we have an allocated network number to provide
// the network number is available outside this class, and will be filled in by the calling function if it is relevant.
srcDevice.adr = new ADR(0, directlyConnectedIPEndPointOfDevice);
}
else
{
throw new Exception("m0063 - No From-Address can be determined");
}
}
if (dadr != null)
{
if (sadr != null)
{
hopcount = (uint)(buffer[npdu_offset + 2 + 2 + 1 + dadr.MACaddress.length + 2 + 1 + sadr.MACaddress.length]);
}
else
{
hopcount = (uint)(buffer[npdu_offset + 2 + 2 + 1 + dadr.MACaddress.length]);
}
// true broadcast, but check the hopcount
if (hopcount == 0)
{
// out of hops, should never happen to us, so sound a warning
// todo, remove this for a functioning systems
System.Windows.Forms.MessageBox.Show("m0008 Hopcount of 0 detected");
return(false);
}
}
// finished resolving sadr, and dadr. Now populate our devices as required
if (sadr != null)
{
if (srcDevice.adr != null)
{
// means this adr was partially populated elsewhere.
srcDevice.adr.networkNumber = sadr.networkNumber;
srcDevice.adr.MACaddress = sadr.MACaddress;
}
else
{
srcDevice.adr = sadr;
}
}
if ((buffer[npdu_offset + 1] & 0x80) == 0x80) // todo magic number
{
// NSDU contains Network Layer Message
// http://www.bacnetwiki.com/wiki/index.php?title=Network_Layer_Protocol_Control_Information
apdu_present = false;
npdu.isNPDUmessage = true;
// calculate offset to the NSDU
nsdu_offset = npdu_offset + 2;
if (sadr != null)
{
nsdu_offset += 2 + 1 + (int)sadr.MACaddress.length;
}
if (dadr != null)
{
nsdu_offset += 2 + 1 + (int)dadr.MACaddress.length + 1;
}
npdu.function = (BACnetEnums.BACNET_NETWORK_MESSAGE_TYPE)buffer[nsdu_offset];
switch (npdu.function)
{
case BACnetEnums.BACNET_NETWORK_MESSAGE_TYPE.NETWORK_MESSAGE_I_AM_ROUTER_TO_NETWORK:
// there may be a list of network numbers after the header
if ((length - nsdu_offset >= 3))
{
numberList = new List <uint>();
}
for (int i = 0; i < (length - nsdu_offset - 1) / 2; i++)
{
int tref = nsdu_offset + 1 + i * 2;
numberList.Add(BACnetLibraryCL.ExtractUint16(buffer, ref tref));
}
break;
case BACnetEnums.BACNET_NETWORK_MESSAGE_TYPE.NETWORK_MESSAGE_INIT_RT_TABLE_ACK:
int tiptr = nsdu_offset + 1;
int numPorts = buffer[tiptr++];
routerPortList = new List <RouterPort>();
for (int i = 0; i < numPorts; i++)
{
RouterPort rp = new RouterPort();
rp.Decode(buffer, ref tiptr);
routerPortList.Add(rp);
}
break;
default:
// todo
break;
}
}
else
{
// NSDU contains APDU
// http://www.bacnetwiki.com/wiki/index.php?title=Network_Layer_Protocol_Control_Information
// determine if SNET, SLEN, SADR present
apdu_present = true;
apdu_offset = npdu_offset + 2;
if (sadr != null)
{
apdu_offset += 2 + 1 + (int)sadr.MACaddress.length;
}
if (dadr != null)
{
apdu_offset += 2 + 1 + (int)dadr.MACaddress.length + 1;
}
apdu_length = length - apdu_offset;
if (apdu_length < 0)
{
_apm.MessagePanic("m0006 Illegal APDU length");
return(false);
}
// todo - need to extract the apdu for others to refer to. However, APDUs may be customer specific, so extract this as a buffer
// only for now, and do some spot checks for relevant functions such as I-Am and Who-Is.
apdu_buf = new byte[2000];
Buffer.BlockCopy(buffer, apdu_offset, apdu_buf, 0, apdu_length);
// the offset here is the APDU. Start parsing APDU.
// todo, decided to leave the enum values unshifted today 11/27/09
pduType = (BACnetEnums.BACNET_PDU_TYPE)(buffer[apdu_offset] & 0xf0);
// make sure that we can handle the rest of the packet
//if ((buffer[apdu_offset] & 0x0f) != 0 )
//{
// throw new Exception("m0056 - Cannot handle segmented messages yet");
//}
int tptr = apdu_offset + 1;
if (pduType == BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_CONFIRMED_SERVICE_REQUEST)
{
// some PDUs have max segs here
tptr++;
}
//_apm.MessageTodo("Remove apdu++");
//apdu_offset++;
//apdu_offset++;
// now the next byte is the invoke ID
invokeID = buffer[tptr++];
switch (pduType)
{
case BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_UNCONFIRMED_SERVICE_REQUEST:
// todo, offset is not always 1, depends on the flags in the first byte.
DecodeUnconfirmedService(apdu_buf, apdu_length);
break;
case BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_CONFIRMED_SERVICE_REQUEST:
DecodeConfirmedService(apdu_buf);
break;
case BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_SIMPLE_ACK:
break;
case BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_COMPLEX_ACK:
confirmedServiceChoice = (BACnetEnums.BACNET_CONFIRMED_SERVICE)buffer[apdu_offset + 2];
DecodeComplexACK(buffer, apdu_offset);
break;
case BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_SEGMENT_ACK:
_apm.MessageTodo("m0093 - Segment ACK");
errorFlag = true;
break;
case BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_ERROR:
_apm.MessageTodo("m0064 - Error");
errorFlag = true;
break;
case BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_REJECT:
pduRejectReason = (BACnetEnums.BACNET_BACNET_REJECT_REASON)buffer[apdu_offset++];
errorFlag = true;
break;
case BACnetEnums.BACNET_PDU_TYPE.PDU_TYPE_ABORT:
_apm.MessageTodo("m0066 - PDU abort");
errorFlag = true;
break;
default:
throw new Exception("m0003 - Illegal PDU type");
}
}
}
catch (Exception ex)
{
_apm.MessagePanic("m0001 - BACnet Decode Failed " + ex.ToString());
}
return(true);
}
public void DumpException(AppManager apm)
{
apm.MessageProtocolError(message);
}