public async Task <List <byte> > processDPDU(List <byte> dnpPkt)
{
Console.Write("processDPDU" + Environment.NewLine);
//Check the start bytes first
List <byte> tpduExtract = new List <byte>();
if (dnpPkt[0] == 0x05)
{
if (dnpPkt[1] == 0x64)
{
//Check control byte function code
int controlByte = dnpPkt[2];
int fnCodeMask = 0x0000000F;
int fnCode = controlByte & fnCodeMask; //last 4 bits
if ((DPDU.functionCode)fnCode == DPDU.functionCode.ISP)
{
ispPkt = true;
stationConsole.Text += "Recvd DS Request" + Environment.NewLine;
}
int userDatalength = dnpPkt[2];
userDatalength -= 5; //reduce 5 for header,i.e. CTRL(1)+DST(2)+SRC(2)
//Now calculate the header CRC, the length excludes the 2 CRC bytes at the very end
//Calculate header CRC
byte[] hdrCRC = dpdu.makeCRC(ref dnpPkt, 0, 7);
if (dnpPkt[8] == hdrCRC[0] && dnpPkt[9] == hdrCRC[1])
{
//Now we can proceed to the Block CRC
//We are limiting ourselves to <= 16 bytes but it could be greater so check it
//first block starts at dnpPkt[10]
if (userDatalength > 16)
{
byte lenBlock2 = (byte)(userDatalength - (byte)16);
//we need two blocks each with its own CRC bytes
byte[] crcBlock1 = dpdu.makeCRC(ref dnpPkt, 10, ((10 + 16) - 1));
byte[] crcBlock2 = dpdu.makeCRC(ref dnpPkt, (10 + 16), (dnpPkt.Count() - 1));
}
else
{
byte[] crcBlock = dpdu.makeCRC(ref dnpPkt, 10, (dnpPkt.Count() - 3));
int crcIndex1 = dnpPkt.Count - 2;
int crcIndex2 = dnpPkt.Count - 1;
if (crcBlock[0] == dnpPkt[crcIndex1] && crcBlock[1] == dnpPkt[crcIndex2])
{
//we can now proceed with processing the data link function code
Console.WriteLine("Datalink CRC correct!");
//now we can extract the TPDU from the DPDU
for (int i = 0; i < (int)userDatalength; i++)
{
tpduExtract.Add(dnpPkt[i + 10]);
}
}
}
}
}
}
return(tpduExtract);
}
public async Task <List <byte> > processDPDU(List <byte> dnpPkt)
{
Console.Write("processDPDU" + Environment.NewLine);
//Check the start bytes first
List <byte> tpduExtract = new List <byte>();
List <byte> correctedPkt = new List <byte>();
correctedPkt = checkDuplicates(dnpPkt);
byte lenBlock2;
if (correctedPkt[0] == 0x05)
{
//Lets extract only one DNP3 packet here
//Check control byte function code
int controlByte = correctedPkt[3];
int fnCodeMask = 0x0000000F;
int fnCode = controlByte & fnCodeMask; //last 4 bits
if ((DPDU.functionCode)fnCode == DPDU.functionCode.ISP)
{
ispPkt = true;
stationConsole.Text += "Recvd DS Request" + Environment.NewLine;
}
int userDatalength = correctedPkt[2];
userDatalength -= 5; //reduce 5 for header,i.e. CTRL(1)+DST(2)+SRC(2)
//Now calculate the header CRC, the length excludes the 2 CRC bytes at the very end
//Calculate header CRC
byte[] hdrCRC = dpdu.makeCRC(ref correctedPkt, 0, 7);
if (correctedPkt[8] == hdrCRC[0] && correctedPkt[9] == hdrCRC[1])
{
//Now we can proceed to the Block CRC
//We are limiting ourselves to <= 16 bytes but it could be greater so check it
//first block starts at dnpPkt[10]
if (userDatalength > 16)
{
lenBlock2 = (byte)(userDatalength - (byte)16);
//we need two blocks each with its own CRC bytes
byte[] crcBlock1 = dpdu.makeCRC(ref correctedPkt, 10, ((10 + 16) - 1));
byte[] crcBlock2 = dpdu.makeCRC(ref correctedPkt, (10 + 16 + 2), (correctedPkt.Count() - 3));
int crcIndex3 = correctedPkt.Count - 2;
int crcIndex4 = correctedPkt.Count - 1;
int crcIndex1 = correctedPkt.Count - (lenBlock2 + 2 + 2); //2 for CRC of 2nd block and 2 for 1st block CRC
int crcIndex2 = crcIndex1 + 1;
if ((crcBlock1[0] == correctedPkt[crcIndex1]) && (crcBlock1[1] == correctedPkt[crcIndex2]) &&
(crcBlock2[0] == correctedPkt[crcIndex3]) && (crcBlock2[1] == correctedPkt[crcIndex4]))
{
//we can now proceed with processing the data link function code
Console.WriteLine("Datalink CRC correct!");
//now we can extract the TPDU from the DPDU
for (int i = 10; i < (correctedPkt.Count - 2); i++) //start from 10 since first 10 bytes is header
{
if (i == crcIndex1)
{
i = i + 2; //skip over first block CRC
}
tpduExtract.Add(correctedPkt[i]);
}
}
}
else
{
byte[] crcBlock = dpdu.makeCRC(ref correctedPkt, 10, (correctedPkt.Count() - 3));
int crcIndex1 = correctedPkt.Count - 2;
int crcIndex2 = correctedPkt.Count - 1;
if (crcBlock[0] == correctedPkt[crcIndex1] && crcBlock[1] == correctedPkt[crcIndex2])
{
//we can now proceed with processing the data link function code
Console.WriteLine("Datalink CRC correct!");
//now we can extract the TPDU from the DPDU
for (int i = 10; i <= (correctedPkt.Count - 2); i++)
{
tpduExtract.Add(correctedPkt[i]);
}
}
else
{
MessageBox.Show("CRC ERROR");
}
}
}
}
if (tpduExtract.Count == 0)
{
MessageBox.Show("CRC ERROR");
}
return(tpduExtract);
}