/// <summary>
///
/// Begins the receive operation on the socket.
/// Takes a callback Action that will receive the parsed packet
///
/// </summary>
public static void StartSniffer(Action <IPv4PacketModel> callback)
{
try
{
parsePackets = true;
Action <IAsyncResult> OnPacketReceive = null;
OnPacketReceive = (asyncResult) =>
{
try
{
if (parsePackets)
{
IPv4PacketModel ipv4PacketModel = IPv4PacketParser.ParseIpv4Packet(packetData);
callback(ipv4PacketModel);
socket.BeginReceive(packetData, 0, packetData.Length, SocketFlags.None, new AsyncCallback(OnPacketReceive), null);
}
}
catch (Exception ex)
{
throw new Exception($"OnPacketReceive > {ex.Message}");
}
};
socket.BeginReceive(packetData, 0, packetData.Length, SocketFlags.None, new AsyncCallback(OnPacketReceive), null);
}
catch (Exception ex)
{
throw new Exception($"StartSniffer > {ex.Message}");
}
}
public static IPv4PacketModel ParseIpv4Packet(byte[] packet)
{
try
{
IPv4PacketModel ipv4PacketModel = new IPv4PacketModel()
{
SourceIP = new IPAddress(Tools.GetSubArray(packet, 12, 4)),
SourcePort = 0,
DestinationIP = new IPAddress(Tools.GetSubArray(packet, 16, 4)),
DestinationPort = 0,
PacketSizeInBytes = BitConverter.ToUInt16(Tools.GetSubArray(packet, 2, 2)),
Protocol = Convert.ToUInt16(packet[9]),
ProtocolAsString = "Other"
};
// If protocol is TCP or UDP
if (ipv4PacketModel.Protocol == 6 || ipv4PacketModel.Protocol == 17)
{
// Get protocol display name
ipv4PacketModel.ProtocolAsString = (ipv4PacketModel.Protocol == 6) ? "TCP" : "UDP";
// Get IPv4 header length to parse child packet
int ipv4HeaderLengthInBytes = 4 * Convert.ToUInt16(packet[0] & 0x0F);
ipv4PacketModel.SourcePort = BitConverter.ToUInt16(Tools.GetSubArray(packet, ipv4HeaderLengthInBytes, 2));
ipv4PacketModel.DestinationPort = BitConverter.ToUInt16(Tools.GetSubArray(packet, (ipv4HeaderLengthInBytes + 2), 2));
// Get child packet header length to parse packet data
int childPacketHeaderLengthInBytes = 8; // UDP header is always 8 bytes
if (ipv4PacketModel.Protocol == 6)
{
childPacketHeaderLengthInBytes = 4 * (Convert.ToUInt16(packet[(ipv4HeaderLengthInBytes + 12)]) >> 4);
}
int dataStart = ipv4HeaderLengthInBytes + childPacketHeaderLengthInBytes;
// Sometimes total packet length is set to 0
if (ipv4PacketModel.PacketSizeInBytes - dataStart > 0)
{
ipv4PacketModel.Data = Tools.GetSubArray(packet, dataStart, (ipv4PacketModel.PacketSizeInBytes - dataStart));
}
}
return(ipv4PacketModel);
}
catch (Exception ex)
{
throw new Exception($"ParseIpv4Packet > {ex.Message}");
}
}
