public static void SetUdpChecksum(Bytes buffer,
Bytes payload,
int ipOffset,
ushort udplength)
{
// sum IP pseudo
ushort ipPayloadSize = 0;
ushort headerSum = IpHeader.SumPseudoHeader(buffer, ipOffset,
ref ipPayloadSize);
DebugStub.Assert(udplength == ipPayloadSize);
// now add it to the udp header + data
int ipHeaderSize = (buffer[ipOffset] & 0xf) * 4;
int udpOffset = ipOffset + ipHeaderSize;
ushort udpsum = IpHeader.SumShortValues(buffer, ipOffset + IpHeader.Size, UDPHeader.Size);
DebugStub.Assert(buffer[udpOffset + 6] == 0);
DebugStub.Assert(buffer[udpOffset + 7] == 0);
ushort payloadSum = IpHeader.SumShortValues(payload, 0,
payload.Length);
ushort hdrSum = IpHeader.SumShortValues(headerSum, udpsum);
ushort chksum;
chksum = (ushort)~(
IpHeader.SumShortValues(hdrSum, payloadSum)
);
buffer[udpOffset + 6] = (byte)(chksum >> 8);
buffer[udpOffset + 7] = (byte)(chksum & 0xff);
}
//process incoming packet
public static bool ProcessIncomingPacket(Bytes packet, IpHeader ipHeader)
{
int offset = EthernetHeader.Size + IpHeader.Size; //14 byte ethernet header + 20 byte IP header
VTable.Assert(offset == 34);
UDPHeader udpHeader = new UDPHeader(packet, offset);
DebugPrint("ProcessIncomingPacket: Received packet from address {0} port {1}\n",
ipHeader.srcAddress.ToString(), udpHeader.srcPort);
UDP udp = GetUDPSession(udpHeader.dstPort);
//now we check to see whether the udp session wants to packet
//XXX review this logic...
//todo: check if udp is bound to local IP that dest IP matches.
//UDP header?
if ((udp != null) &&
((udp.LocalAddress == IPv4.Any) ||
(udp.RemoteAddress == ipHeader.srcAddress && udp.RemotePort == udpHeader.srcPort) ||
(udp.RemotePort == 0)))
{
offset += UDPHeader.Size;
Bytes data = Bitter.SplitOff(ref packet, offset);
//delete packet;
udp.PushPacket(data);
udp.udpWaitEvent.Set();
return(true);
}
DebugPrint("Received packe destined for inactive UDP port {0}" +
" source address {1} source port {2}\n",
udpHeader.dstPort, ipHeader.srcAddress.ToString(), udpHeader.srcPort);
//delete packet;
return(false);
}
//assume ethernet
//we have to expose this for the DhcpClient
//Once we move the Dhcp client into an app this can be hidden again
public void WriteCompleteUDPHeader(Bytes header, Bytes data, int payloadLength)
{
int totalLength = IpHeader.Size + UDPHeader.Size + payloadLength;
//write ip header
int offset = EthernetHeader.Size;
int o = EthernetHeader.Size;
DebugStub.Assert(payloadLength < 0xffff);
header[o++] = 0x45; //default version 4, header_len 5
header[o++] = 0; //tos
header[o++] = (byte)(((ushort)totalLength) >> 8); //total length of the ip header
header[o++] = (byte)(((ushort)totalLength) & 0xff);
header[o++] = (byte)(((ushort)0) >> 8); //fragment id
header[o++] = (byte)(((ushort)0) & 0xff); //fragment id
header[o++] = (byte)(((ushort)0) >> 8); //fragment offset
header[o++] = (byte)(((ushort)0) & 0xff); //fragment offset
header[o++] = 128; //default ttl
header[o++] = 17; // protocol ID --> udp
header[o++] = 0; //ipchecksum (fill it in later)
header[o++] = 0; //ipchecksum
// set the ip addresses
localIPAddress.CopyOut(header.Array, header.Start + o);
o += IPv4.Length;
remoteIPAddress.CopyOut(header.Array, header.Start + o);
o += IPv4.Length;
// calculate checksum
ushort chk = IpHeader.CalculateChecksum(header, offset, IpHeader.Size);
header[offset + 10] = (byte)(((ushort)chk) >> 8);
header[offset + 11] = (byte)(((ushort)chk) & 0xff);
//write the udp header
header[o++] = (byte)(((ushort)localPort) >> 8);
header[o++] = (byte)(((ushort)localPort) & 0xff);
header[o++] = (byte)(((ushort)remotePort) >> 8);
header[o++] = (byte)(((ushort)remotePort) & 0xff);
ushort udpLength = (ushort)(UDPHeader.Size + payloadLength);
header[o++] = (byte)(((ushort)udpLength) >> 8);
header[o++] = (byte)(((ushort)udpLength) & 0xff);
// udp checksum (forget for now)
header[o++] = 0;
header[o++] = 0;
UDPHeader.SetUdpChecksum(header, data, EthernetHeader.Size, udpLength);
}
//dirt simple is the name of the game
public static void ProcessIncomingPacket(Bytes packet, IAdapter adapter)
{
IpHeader ipHeader = new IpHeader(packet, EthernetHeader.Size);
//since we apparently don't support fragments yet.
if (ipHeader.MoreFragmentsFollowing() == true)
{
DebugPrint("ACK! ip fragmentation!\n");
return;
}
// DebugStub.Assert(ipHeader.MoreFragmentsFollowing() == false);
//VTable.Assert(ipHeader.MoreFragmentsFollowing() == false);
if (ipHeader.IsChecksumValid() == false)
{
DebugPrint("ProcessIncomingPacket: bad checksum...dropping packets\n");
//delete packet;
return;
}
//make sure the address is 'local'
if (hostConfiguration == null)
{
DebugPrint("ACK hostConfiguration is NULL\n");
return;
}
if ((hostConfiguration.IsLocalAddress(ipHeader.destAddress) == false) &&
(ipHeader.destAddress != IPv4.Broadcast))
{
// DebugPrint("ProcessIncomingPacket: wrong address ...dropping packets\n");
// DebugPrint("Dest address {0}\n", ipHeader.destAddress);
//delete packet;
return;
}
try {
//figure out to which protocol the packet belongs
switch (ipHeader.protocol)
{
case IpHeader.TCP:
DebugPrint("ProcessIncomingPacket: Got TCP packet\n");
//TCP.ProcessIncomingPacket(packet, ipHeader);
break;
case IpHeader.UDP:
//DebugPrint("ProcessIncomingPacket: Got UDP packet\n");
UDP.ProcessIncomingPacket(packet, ipHeader);
break;
case IpHeader.ICMP:
DebugPrint("ProcessIncomingPacket: Got ICMP packet\n");
//delete packet;
break;
default:
DebugPrint("Got unexpected packet!!\n");
//delete packet;
DebugStub.Break();
break;
}
}
catch (Exception e) {
DebugStub.Print("Caught exception {0}\n", DebugStub.ArgList(e));
DebugStub.Break();
}
}