public void ArpRequest(IPv4 sourceIP,
IPv4 targetIP,
Multiplexer !targetMux,
ArpRequestCallback callback,
object cookie,
TimeSpan timeout)
{
//
//XXXX Check pending request does not already exist!
//
EthernetAddress localMac = targetMux.Adapter.HardwareAddress;
AddPendingRequest(targetIP, callback, cookie, timeout);
// initiate an arp request...
DebugPrint("Initiating request " +
"({0},{1}) --> ({2},{3})\n",
sourceIP, localMac, targetIP, EthernetAddress.Zero);
byte[] data = new byte[ArpFormat.Size + EthernetFormat.Size];
int pos = EthernetFormat.Write(data, 0, localMac,
EthernetAddress.Broadcast,
EthernetFormat.PROTOCOL_ARP);
ArpFormat.Write(data, pos, localMac, sourceIP,
ArpFormat.Type.ARP_REQUEST, EthernetAddress.Zero,
targetIP);
NetPacket pkt = new NetPacket(data);
pkt.Mux = targetMux;
OnProtocolSend(pkt);
}
///
// ARP logic: see RFC 826 http://www.faqs.org/rfcs/rfc826.html
//
public NetStatus OnProtocolReceive(NetPacket !pkt)
{
NetStatus res = NetStatus.Code.PROTOCOL_OK;
Debug.Assert(pkt != null);
ArpFormat.Type opcode;
EthernetAddress senderMAC, targetMAC;
IPv4 senderIP, targetIP;
bool ok = ArpFormat.Read(pkt, out opcode,
out senderMAC, out senderIP,
out targetMAC, out targetIP);
DebugPrint("ARP RESPONSE\n");
// check for problems
if (ok == false)
{
DebugPrint("ARP READ ERROR\n");
return(NetStatus.Code.PROTOCOL_DROP_ERROR);
}
bool merged = false;
bool updated = false;
ArpEntry target = arpTable.Lookup(senderIP);
if (target != null && target.Dynamic == true)
{
DebugPrint("ARP UPDATE\n");
// we have it already - just update the details...
target.MacAddress = senderMAC;
target.EntryAge = arpTable.Age;
merged = true;
updated = true;
}
bool forSelf = ipModule.HostConfiguration.IsLocalAddress(targetIP);
if (forSelf == false)
{
return(NetStatus.Code.PROTOCOL_OK);
}
if (merged == false)
{
DebugPrint("ARP ADDITION\n");
arpTable.AddEntry(new ArpEntry(senderIP, senderMAC, true));
merged = true;
UpdatePendingRequests(senderIP, senderMAC);
}
// now figure out the opcode
if (opcode == ArpFormat.Type.ARP_REQUEST)
{
DebugPrint("Handling request ({0},{1}) ---> ({2},{3})\n",
senderIP, senderMAC, targetIP, targetMAC
);
// send reply...
// we reuse the received packet for sending a fast response
// so we should NOT return it to the Demux's free list!!!
// (we replace it with a new one instead)
// we use the adapter from which the request arrived
// (available in the context)
Multiplexer mux = Core.Instance().GetMuxForAdapter((IAdapter !)pkt.AdapterContext);
if (mux == null)
{
// some internal bug, for now just panic
Core.Panic("At ArpModule.PacketReceive: " +
"context isn't Multiplexer!\n");
assert(false);
}
int dataLength = EthernetFormat.Size + ArpFormat.Size;
if (dataLength < pkt.Length)
{
dataLength = pkt.Length;
}
byte[] !data = new byte[dataLength];
Array.Copy(pkt.GetRawData(), 0, data, 0, pkt.Length);
ArpFormat.CreateArpReply(ref data, targetIP,
mux.Adapter.HardwareAddress);
mux.SendDirect(new NetPacket(data));
}
else
{
// otherwise we are done
DebugPrint(
"Handling reply ({2},{3}) <--- ({0},{1})\n",
senderIP, senderMAC, targetIP, targetMAC
);
}
if (merged && !updated)
{
DebugPrint(arpTable.ToString());
}
return(res);
}
