/// <summary>
/// Resolves the specified IPv4 address to a Layer-2 (MAC-48)
/// physical address.
/// </summary>
/// <param name="ifc">The interface to look an address up for.</param>
/// <param name="ipAddress">The IPv4 address to resolve.</param>
/// <exception cref="ArgumentNullException">Thrown if either of the
/// arguments is null.</exception>
/// <remarks>This API is exposed to the next higher-up layer. In other
/// words, it is called by the Network layer to resolve an IPv4 address
/// to the corresponding MAC-48 address.</remarks>
public void Resolve(Interface ifc, IpAddress ipAddress)
{
ifc.ThrowIfNull("ifc");
ipAddress.ThrowIfNull("ipAddress");
// If there's already a pending ARP request for the IP, don't
// issue another one.
if (arpInProgress.Contains(ipAddress))
{
return;
}
// Output an ARP request to physical broadcast address
// FF:FF:FF:FF:FF:FF.
arpInProgress.Add(ipAddress);
ArpPacket packet = new ArpPacket(ifc.Nic.MacAddress, ifc.IpAddress,
ipAddress);
WriteLine(ifc.FullName + " is constructing an ARP request for " +
ipAddress + ".");
output(ifc, broadcastAddress, packet);
}
/// <summary>
/// Examines and processes the ARP message contained in the specified byte
/// array.
/// </summary>
/// <param name="ifc">The interface through which the data was
/// received.</param>
/// <param name="data">A sequence of bytes containing an ARP packet.</param>
/// <exception cref="ArgumentNullException">Thrown if either parameter
/// is null.</exception>
/// <exception cref="SerializationException">Thrown if the data array does
/// not contain a valid ARP packet.</exception>
public void OnInput(Interface ifc, byte[] data)
{
ifc.ThrowIfNull("ifc");
data.ThrowIfNull("data");
WriteLine(ifc.FullName + " has received an ARP message.");
var packet = ArpPacket.Deserialize(data);
// If it's our own packet, don't do anything with it.
if (packet.MacAddressSender == ifc.Nic.MacAddress)
{
return;
}
// Update our ARP cache with the sender's information.
if (!cache.ContainsKey(ifc.Name))
{
cache.Add(ifc.Name, new ArpCache());
}
cache[ifc.Name].Add(packet.IpAddressSender,
new ArpEntry(packet.IpAddressSender, packet.MacAddressSender));
if (packet.IsResponse)
{
WriteLine(ifc.FullName + " is updating its ARP table with [" +
packet.IpAddressSender + ", " + packet.MacAddressSender + "]");
}
// Remove IP address from pending list, if present.
arpInProgress.Remove(packet.IpAddressSender);
if (packet.IsRequest)
{
// It's an ARP request and we are the recipient, so send an ARP reply
// back to the sender.
if (packet.IpAddressTarget == ifc.IpAddress)
{
var response = new ArpPacket(ifc.Nic.MacAddress,
packet.IpAddressTarget, packet.MacAddressSender,
packet.IpAddressSender);
WriteLine(ifc.FullName + " is constructing an ARP response for " +
packet.IpAddressSender + ".");
output(ifc, packet.MacAddressSender, response);
}
}
}
/// <summary>
/// Resolves the specified IPv4 address to a Layer-2 (MAC-48)
/// physical address.
/// </summary>
/// <param name="ifc">The interface to look an address up for.</param>
/// <param name="ipAddress">The IPv4 address to resolve.</param>
/// <exception cref="ArgumentNullException">Thrown if either of the
/// arguments is null.</exception>
/// <remarks>This API is exposed to the next higher-up layer. In other
/// words, it is called by the Network layer to resolve an IPv4 address
/// to the corresponding MAC-48 address.</remarks>
public void Resolve(Interface ifc, IpAddress ipAddress) {
ifc.ThrowIfNull("ifc");
ipAddress.ThrowIfNull("ipAddress");
// If there's already a pending ARP request for the IP, don't
// issue another one.
if (arpInProgress.Contains(ipAddress))
return;
// Output an ARP request to physical broadcast address
// FF:FF:FF:FF:FF:FF.
arpInProgress.Add(ipAddress);
ArpPacket packet = new ArpPacket(ifc.Nic.MacAddress, ifc.IpAddress,
ipAddress);
WriteLine(ifc.FullName + " is constructing an ARP request for " +
ipAddress + ".");
output(ifc, broadcastAddress, packet);
}
/// <summary>
/// Examines and processes the ARP message contained in the specified byte
/// array.
/// </summary>
/// <param name="ifc">The interface through which the data was
/// received.</param>
/// <param name="data">A sequence of bytes containing an ARP packet.</param>
/// <exception cref="ArgumentNullException">Thrown if either parameter
/// is null.</exception>
/// <exception cref="SerializationException">Thrown if the data array does
/// not contain a valid ARP packet.</exception>
public void OnInput(Interface ifc, byte[] data) {
ifc.ThrowIfNull("ifc");
data.ThrowIfNull("data");
WriteLine(ifc.FullName + " has received an ARP message.");
var packet = ArpPacket.Deserialize(data);
// If it's our own packet, don't do anything with it.
if (packet.MacAddressSender == ifc.Nic.MacAddress)
return;
// Update our ARP cache with the sender's information.
if (!cache.ContainsKey(ifc.Name))
cache.Add(ifc.Name, new ArpCache());
cache[ifc.Name].Add(packet.IpAddressSender,
new ArpEntry(packet.IpAddressSender, packet.MacAddressSender));
if(packet.IsResponse)
WriteLine(ifc.FullName + " is updating its ARP table with [" +
packet.IpAddressSender + ", " + packet.MacAddressSender + "]");
// Remove IP address from pending list, if present.
arpInProgress.Remove(packet.IpAddressSender);
if (packet.IsRequest) {
// It's an ARP request and we are the recipient, so send an ARP reply
// back to the sender.
if (packet.IpAddressTarget == ifc.IpAddress) {
var response = new ArpPacket(ifc.Nic.MacAddress,
packet.IpAddressTarget, packet.MacAddressSender,
packet.IpAddressSender);
WriteLine(ifc.FullName + " is constructing an ARP response for " +
packet.IpAddressSender + ".");
output(ifc, packet.MacAddressSender, response);
}
}
}