+++ /dev/null
-package edu.uci.iotproject.trafficreassembly.layer3;
-
-import org.pcap4j.core.PcapPacket;
-import org.pcap4j.packet.IpV4Packet;
-import org.pcap4j.packet.TcpPacket;
-
-/**
- * Groups a FIN packet and its corresponding ACK packet. <b>Immutable and thread safe</b>.
- *
- * @author Janus Varmarken {@literal <jvarmark@uci.edu>}
- * @author Rahmadi Trimananda {@literal <rtrimana@uci.edu>}
- */
-public class FinAckPair {
-
- private final PcapPacket mFinPacket;
- private final PcapPacket mCorrespondingAckPacket;
-
- /**
- * Constructs a {@code FinAckPair} given a FIN packet.
- * The corresponding ACK packet field is set to {@code null}.
- * @param finPacket A FIN packet.
- */
- public FinAckPair(PcapPacket finPacket) {
- if (!finPacket.get(TcpPacket.class).getHeader().getFin()) {
- throw new IllegalArgumentException("not a FIN packet");
- }
- mFinPacket = finPacket;
- mCorrespondingAckPacket = null;
- }
-
- /**
- * Constructs a {@code FinAckPair} given a FIN and an ACK packet.
- * @param finPacket A FIN packet.
- * @param correspondingAckPacket The ACK packet corresponding to {@code finPacket}.
- */
- public FinAckPair(PcapPacket finPacket, PcapPacket correspondingAckPacket) {
- // Enforce class invariant, i.e. that the FIN and ACK are related.
- // Note that it is indirectly checked whether finPacket is indeed a FIN packet
- // as isCorrespondingAckPacket calls the single parameter constructor.
- if (!FinAckPair.isCorrespondingAckPacket(finPacket, correspondingAckPacket)) {
- throw new IllegalArgumentException("FIN and ACK not related");
- }
- mFinPacket = finPacket;
- mCorrespondingAckPacket = correspondingAckPacket;
- }
-
- /**
- * Get the FIN packet of this pair.
- * @return the FIN packet of this pair.
- */
- public PcapPacket getFinPacket() {
- return mFinPacket;
- }
-
- /**
- * Get the corresponding ACK packet of this pair, if any.
- * @return the corresponding ACK packet of this pair, if any.
- */
- public PcapPacket getCorrespondingAckPacket() {
- return mCorrespondingAckPacket;
- }
-
- /**
- * Was the FIN in this {@code FinAckPair} acknowledged?
- *
- * @return {@code true} if the corresponding ACK has been set in this {@code FinAckPair}.
- */
- public boolean isAcknowledged() {
- return mFinPacket != null && mCorrespondingAckPacket != null;
- }
-
- /**
- * Checks if a given packet is an ACK corresponding to the FIN packet in this {@code FinAckPair}.
- * @return {@code true} if {@code packet} is an ACK that corresponds to the FIN in this pair, {@code false} otherwise.
- */
- public boolean isCorrespondingAckPacket(PcapPacket packet) {
- IpV4Packet inputIpPacket = packet.get(IpV4Packet.class);
- TcpPacket inputTcpPacket = packet.get(TcpPacket.class);
- if (inputIpPacket == null || inputTcpPacket == null || !inputTcpPacket.getHeader().getAck()) {
- return false;
- }
-
- IpV4Packet finIpPacket = mFinPacket.get(IpV4Packet.class);
- TcpPacket finTcpPacket = mFinPacket.get(TcpPacket.class);
-
- // Extract (srcIp:port,dstIp:port) for input and member (FIN) packets.
- String inputPacketIpSrc = inputIpPacket.getHeader().getSrcAddr().getHostAddress();
- String inputPacketIpDst = inputIpPacket.getHeader().getDstAddr().getHostAddress();
- int inputPacketPortSrc = inputTcpPacket.getHeader().getSrcPort().valueAsInt();
- int inputPacketPortDst = inputTcpPacket.getHeader().getDstPort().valueAsInt();
- String finPacketIpSrc = finIpPacket.getHeader().getSrcAddr().getHostAddress();
- String finPacketIpDst = finIpPacket.getHeader().getDstAddr().getHostAddress();
- int finPacketPortSrc = finTcpPacket.getHeader().getSrcPort().valueAsInt();
- int finPacketPortDst = finTcpPacket.getHeader().getDstPort().valueAsInt();
-
- // For the two packets to be related, the dst of one must be the src of the other.
- // Split into multiple if statements for readability. First check IP fields, then ports.
- if (!(inputPacketIpDst.equals(finPacketIpSrc) && finPacketIpDst.equals(inputPacketIpSrc))) {
- return false;
- }
- if (!(inputPacketPortDst == finPacketPortSrc && finPacketPortDst == inputPacketPortSrc)) {
- return false;
- }
-
- // Packets are (most likely) related (part of same conversation/stream).
- // Now all that is left for us to check is if the sequence numbers match.
- // Note: recall that the FIN packet advances the seq numbers by 1,
- // so the ACK number will be one larger than the seq. number in the FIN packet.
- return inputTcpPacket.getHeader().getAcknowledgmentNumber() == finTcpPacket.getHeader().getSequenceNumber() + 1;
- }
-
- /**
- * Static method to check if two given packets are a FIN and the corresponding ACK packet.
- * The purpose of this method is a workaround to enforce the class invariant in the two parameter constructor.
- * Specifically, the following should be avoided:
- * <pre>
- * public FinAckPair(PcapPacket finPacket, PcapPacket correspondingAckPacket) {
- * mFinPacket = finPacket;
- * // Below line is considered bad practice as the object has not been fully initialized at this stage.
- * if (!this.isCorrespondingAckPacket(correspondingAckPacket)) {
- * // ... throw exception
- * }
- * }
- * </pre>
- * @param finPacket The FIN packet.
- * @param ackPacket The ACK packet that is to be checked if it corresponds to the given FIN packet.
- * @return {@code true} if the ACK corresponds to the FIN, {@code false} otherwise.
- */
- private static boolean isCorrespondingAckPacket(PcapPacket finPacket, PcapPacket ackPacket) {
- FinAckPair tmp = new FinAckPair(finPacket);
- return tmp.isCorrespondingAckPacket(ackPacket);
- }
-
-}
projects / pingpong.git / blobdiff