//Helper function which returns the information contained in the TCP header as a
//tree node
private TreeNode MakeTCPTreeNode(TCPHeader tcpHeader)
{
TreeNode tcpNode = new TreeNode();
tcpNode.Text = "TCP";
tcpNode.Nodes.Add("Source Port: " + tcpHeader.SourcePort);
tcpNode.Nodes.Add("Destination Port: " + tcpHeader.DestinationPort);
tcpNode.Nodes.Add("Sequence Number: " + tcpHeader.SequenceNumber);
if (tcpHeader.AcknowledgementNumber != "")
{
tcpNode.Nodes.Add("Acknowledgement Number: " + tcpHeader.AcknowledgementNumber);
}
tcpNode.Nodes.Add("Header Length: " + tcpHeader.HeaderLength);
tcpNode.Nodes.Add("Flags: " + tcpHeader.Flags);
tcpNode.Nodes.Add("Window Size: " + tcpHeader.WindowSize);
tcpNode.Nodes.Add("Checksum: " + tcpHeader.Checksum);
if (tcpHeader.UrgentPointer != "")
{
tcpNode.Nodes.Add("Urgent Pointer: " + tcpHeader.UrgentPointer);
}
return(tcpNode);
}
private void ParseData(byte[] byteData, int nReceived)
{
TreeNode rootNode = new TreeNode();
//Since all protocol packets are encapsulated in the IP datagram
//so we start by parsing the IP header and see what protocol data
//is being carried by it
IPHeader ipHeader = new IPHeader(byteData, nReceived);
TreeNode ipNode = MakeIPTreeNode(ipHeader);
rootNode.Nodes.Add(ipNode);
//Now according to the protocol being carried by the IP datagram we parse
//the data field of the datagram
switch (ipHeader.ProtocolType)
{
case Protocol.TCP:
TCPHeader tcpHeader = new TCPHeader(ipHeader.Data, //IPHeader.Data stores the data being
//carried by the IP datagram
ipHeader.MessageLength); //Length of the data field
TreeNode tcpNode = MakeTCPTreeNode(tcpHeader);
rootNode.Nodes.Add(tcpNode);
//If the port is equal to 53 then the underlying protocol is DNS
//Note: DNS can use either TCP or UDP thats why the check is done twice
if (tcpHeader.DestinationPort == "53" || tcpHeader.SourcePort == "53")
{
TreeNode dnsNode = MakeDNSTreeNode(tcpHeader.Data, (int)tcpHeader.MessageLength);
rootNode.Nodes.Add(dnsNode);
}
break;
case Protocol.UDP:
UDPHeader udpHeader = new UDPHeader(ipHeader.Data, //IPHeader.Data stores the data being
//carried by the IP datagram
(int)ipHeader.MessageLength); //Length of the data field
TreeNode udpNode = MakeUDPTreeNode(udpHeader);
rootNode.Nodes.Add(udpNode);
//If the port is equal to 53 then the underlying protocol is DNS
//Note: DNS can use either TCP or UDP thats why the check is done twice
if (udpHeader.DestinationPort == "53" || udpHeader.SourcePort == "53")
{
TreeNode dnsNode = MakeDNSTreeNode(udpHeader.Data,
//Length of UDP header is always eight bytes so we subtract that out of the total
//length to find the length of the data
Convert.ToInt32(udpHeader.Length) - 8);
rootNode.Nodes.Add(dnsNode);
}
break;
case Protocol.Unknown:
break;
}
AddTreeNode addTreeNode = new AddTreeNode(OnAddTreeNode);
rootNode.Text = ipHeader.SourceAddress.ToString() + "-" +
ipHeader.DestinationAddress.ToString();
//Thread safe adding of the nodes
treeView.Invoke(addTreeNode, new object[] { rootNode });
}
