/**
* Deserializer function for ARP packets.
*
* @return deserializer function
*/
public static Deserializer<ARP> deserializer() {
return (data, offset, length) -> {
checkInput(data, offset, length, INITIAL_HEADER_LENGTH);
ARP arp = new ARP();
final ByteBuffer bb = ByteBuffer.wrap(data, offset, length);
arp.setHardwareType(bb.getShort());
arp.setProtocolType(bb.getShort());
byte hwAddressLength = bb.get();
arp.setHardwareAddressLength(hwAddressLength);
byte protocolAddressLength = bb.get();
arp.setProtocolAddressLength(protocolAddressLength);
arp.setOpCode(bb.getShort());
// Check we have enough space for the addresses
checkHeaderLength(
length, INITIAL_HEADER_LENGTH + 2 * hwAddressLength + 2 * protocolAddressLength);
arp.senderHardwareAddress = new byte[0xff & hwAddressLength];
bb.get(arp.senderHardwareAddress, 0, arp.senderHardwareAddress.length);
arp.senderProtocolAddress = new byte[0xff & protocolAddressLength];
bb.get(arp.senderProtocolAddress, 0, arp.senderProtocolAddress.length);
arp.targetHardwareAddress = new byte[0xff & hwAddressLength];
bb.get(arp.targetHardwareAddress, 0, arp.targetHardwareAddress.length);
arp.targetProtocolAddress = new byte[0xff & protocolAddressLength];
bb.get(arp.targetProtocolAddress, 0, arp.targetProtocolAddress.length);
return arp;
};
}
/**
* Builds an ARP reply based on a request.
*
* @param srcIp the IP address to use as the reply source
* @param srcMac the MAC address to use as the reply source
* @param request the ARP request we got
* @return an Ethernet frame containing the ARP reply
*/
public static Ethernet buildArpReply(Ip4Address srcIp, MacAddress srcMac, Ethernet request) {
Ethernet eth = new Ethernet();
eth.setDestinationMACAddress(request.getSourceMAC());
eth.setSourceMACAddress(srcMac);
eth.setEtherType(Ethernet.TYPE_ARP);
eth.setVlanID(request.getVlanID());
ARP arp = new ARP();
arp.setOpCode(ARP.OP_REPLY);
arp.setProtocolType(ARP.PROTO_TYPE_IP);
arp.setHardwareType(ARP.HW_TYPE_ETHERNET);
arp.setProtocolAddressLength((byte) Ip4Address.BYTE_LENGTH);
arp.setHardwareAddressLength((byte) Ethernet.DATALAYER_ADDRESS_LENGTH);
arp.setSenderHardwareAddress(srcMac.toBytes());
arp.setTargetHardwareAddress(request.getSourceMACAddress());
arp.setTargetProtocolAddress(((ARP) request.getPayload()).getSenderProtocolAddress());
arp.setSenderProtocolAddress(srcIp.toInt());
eth.setPayload(arp);
return eth;
}
