public TPDUConnection(byte[] packet)
{
int pos;
int li = packet[0];
TPDU.TPDU_TYPES type = (TPDU.TPDU_TYPES)(packet[1] >> 4);
if ((type != TPDU.TPDU_TYPES.CR) && (type != TPDU.TPDU_TYPES.CC))
{
throw new ApplicationException("TPDU: This can only handle CC/CR TDPUs");
}
if (BitConverter.IsLittleEndian)
{
DstRef = ByteConvert.DoReverseEndian(BitConverter.ToUInt16(packet, 2));
SrcRef = ByteConvert.DoReverseEndian(BitConverter.ToUInt16(packet, 4));
}
else
{
DstRef = BitConverter.ToUInt16(packet, 2);
SrcRef = BitConverter.ToUInt16(packet, 4);
}
ClassOption = ((packet[6] & 0xf0) >> 4);
if (ClassOption > 4)
{
throw new Exception("TPDU: Class option number not allowed.");
}
pos = 7;
// read variable part
Varpart = new ArrayList();
try
{
while (pos < li)
{
VarParam vp = new VarParam();
vp.code = packet[pos];
pos += 1;
vp.length = packet[pos];
pos += 1;
vp.value = new byte[vp.length];
Array.Copy(packet, pos, vp.value, 0, vp.length);
pos += vp.length;
Varpart.Add(vp);
}
}
catch (Exception)
{
throw new Exception("TPDU: Error parsing variable part of CR/CC PDU.");
}
}
// Handle connect request and build a connect confirm packet
public TPDUConnection HandleConnectRequest(List <byte[]> LocalTsaps, int maxTPDUSize, bool enableTsapCheck)
{
ArrayList varpart = new ArrayList();
TPDUConnection ccpdu = new TPDUConnection();
Random random = new Random();
this.MaxTPDUSize = maxTPDUSize;
ccpdu.DstRef = SrcRef;
ccpdu.SrcRef = Convert.ToUInt16(random.Next(1, 32766));
ccpdu.ClassOption = 0;
// Compare Destination TSAP
int indDstTsap = Varpart.IndexOf((byte)VP.DST_TSAP);
if (indDstTsap < 0)
{
throw new Exception("TPDU: Missing destination tsap in connect request.");
}
if (enableTsapCheck)
{
bool validTsapFound = false;
foreach (byte[] tsap in LocalTsaps)
{
// Check length
if (((VarParam)Varpart[indDstTsap]).length == tsap.Length)
{
for (int i = 0; i < tsap.Length; i++)
{
if (((VarParam)Varpart[indDstTsap]).value[i] == tsap[i])
{
if (i == tsap.Length - 1)
{
validTsapFound = true;
break;
}
}
else
{
break;
}
}
}
if (validTsapFound)
{
break;
}
}
if (validTsapFound == false)
{
throw new Exception("TPDU: Destination tsap mismatch.");
}
}
int indSrcTsap = Varpart.IndexOf((byte)VP.SRC_TSAP);
if (indSrcTsap < 0)
{
throw new Exception("TPDU: Missing source tsap in connect request.");
}
// Add parameters
VarParam vp = new VarParam();
ccpdu.Varpart = new ArrayList();
vp.code = (byte)VP.SRC_TSAP;
vp.length = ((VarParam)Varpart[indSrcTsap]).length;
vp.value = new byte[vp.length];
Array.Copy(((VarParam)Varpart[indSrcTsap]).value, vp.value, vp.length);
ccpdu.Varpart.Add(vp);
vp.code = (byte)VP.DST_TSAP;
vp.length = ((VarParam)Varpart[indDstTsap]).length;
vp.value = new byte[vp.length];
Array.Copy(((VarParam)Varpart[indDstTsap]).value, vp.value, vp.length);
ccpdu.Varpart.Add(vp);
int indPduSize = Varpart.IndexOf((byte)VP.TPDU_SIZE);
int TPDUSizeId = GetTPDUSizeIdFromOctetCount(MaxTPDUSize);
if (indPduSize >= 0)
{
if (((VarParam)Varpart[indPduSize]).value[0] < TPDUSizeId)
{
TPDUSizeId = ((VarParam)Varpart[indPduSize]).value[0];
}
}
ccpdu.MaxTPDUSize = GetTPDUOctetCountFromSizeId(TPDUSizeId);
vp.code = (byte)VP.TPDU_SIZE;
vp.length = 1;
vp.value = new byte[1];
vp.value[0] = Convert.ToByte(TPDUSizeId);
ccpdu.Varpart.Add(vp);
return(ccpdu);
}
