public void SendToRaw(IPAddress rawAddress, byte id, byte[] buf, int offset, int size)
{
var headerList = new ArrayList();
var icmpHeader = new IcmpHeader();
icmpHeader.Id = 123;
icmpHeader.Sequence = 24;
icmpHeader.Type = IcmpHeader.EchoReplyType;
icmpHeader.Code = IcmpHeader.EchoReplyCode;
headerList.Add(icmpHeader);
var myheader = new MyProtocol();
myheader.Id = (byte)(byte.MaxValue - id);
headerList.Add(myheader);
byte[] sub = new byte[size];
Array.Copy(buf, offset, sub, 0, size);
var rawpacket = ProtocolHeader.BuildPacket(headerList, sub);
RawSocket.BeginSendTo(rawpacket, 0, rawpacket.Length, SocketFlags.None,
new IPEndPoint(rawAddress, 0),
new AsyncCallback(TransportLayer.Instance().OnRawWriteComplete), rawpacket.Length);
}
private void OnRawReadComplete(IAsyncResult ia)
{
byte[] buf = (byte[])ia.AsyncState;
int readed = RawSocket.EndReceive(ia);
if (readed <= PAYLOAD_OFFSET_IP_HEADER)
{
Log.D("raw bytes {0} <= ip+icmp header length,removed", readed);
return;
}
var ipLength = (ushort)(buf[2] * 256 + buf[3]);
var srcAddr = new IPAddress(new byte[] { buf[12], buf[13], buf[14], buf[15] });
var icmpWithPayloadLength = ipLength - Ipv4Header.Ipv4HeaderLength;
Log.D("receiving from {0} ,icmp with payload should be {1} bytes", srcAddr, icmpWithPayloadLength);
//now buf contains whole packet
ushort checksum = IcmpHeader.ComputeChecksum(buf, Ipv4Header.Ipv4HeaderLength, icmpWithPayloadLength);
if (checksum != 0)
{
Log.E("icmp checksum {0} error, removed", checksum);
//invalid pack
return;
}
var crc = new Crc();
var payloadLength = ipLength - PAYLOAD_OFFSET_IP_HEADER;
byte crc8 = crc.Update(buf, MY_HEADER_OFFSET_IP_HEADER + 1, payloadLength + 1);
byte packetCrc8 = buf[MY_HEADER_OFFSET_IP_HEADER];
if (crc8 != packetCrc8)
{
Log.E("calced crc {0}!= {1} failed, removed", crc8, packetCrc8);
return;
}
// all ok
foreach (var l in Listeners)
{
l.OnRawRead(srcAddr, buf[MY_HEADER_OFFSET_IP_HEADER + 1], buf, PAYLOAD_OFFSET_IP_HEADER, payloadLength);
}
}
/// <summary>
/// This routine creates an instance of the IcmpHeader class from a byte
/// array that is a received IGMP packet. This is useful when a packet
/// is received from the network and the header object needs to be
/// constructed from those values.
/// </summary>
/// <param name="icmpPacket">Byte array containing the binary ICMP header</param>
/// <param name="bytesCopied">Number of bytes used in header</param>
/// <returns>Returns the IcmpHeader object created from the byte array</returns>
static public IcmpHeader Create(byte[] icmpPacket, ref int bytesCopied)
{
IcmpHeader icmpHeader = new IcmpHeader();
int offset = 0;
// Make sure byte array is large enough to contain an ICMP header
if (icmpPacket.Length < IcmpHeader.IcmpHeaderLength)
{
return(null);
}
icmpHeader.icmpType = icmpPacket[offset++];
icmpHeader.icmpCode = icmpPacket[offset++];
icmpHeader.icmpChecksum = BitConverter.ToUInt16(icmpPacket, offset);
offset += 2;
icmpHeader.icmpId = BitConverter.ToUInt16(icmpPacket, offset);
offset += 2;
icmpHeader.icmpSequence = BitConverter.ToUInt16(icmpPacket, offset);
bytesCopied = IcmpHeader.IcmpHeaderLength;
return(icmpHeader);
}