Code/Projects/PacketLevelSignatureExtractor/src/main/java/edu/uci/iotproject/detection/layer2/Layer2RangeMatcher.java

   1 package edu.uci.iotproject.detection.layer2;
   2
   3 import edu.uci.iotproject.analysis.TriggerTrafficExtractor;
   4 import edu.uci.iotproject.util.PcapPacketUtils;
   5 import org.pcap4j.core.PcapPacket;
   6 import org.pcap4j.util.MacAddress;
   7
   8 import java.util.ArrayList;
   9 import java.util.List;
  10
  11 /**
  12  * Attempts to detect the presence of a specific packet sequence in the set of packets provided through multiple calls
  13  * to {@link #matchPacket(PcapPacket)}, considering only layer 2 information. This class has the same flavor as the
  14  * {@link Layer2SequenceMatcher} class.
  15  *
  16  * @author Janus Varmarken {@literal <jvarmark@uci.edu>}
  17  * @author Rahmadi Trimananda {@literal <rtrimana@uci.edu>}
  18  */
  19 public class Layer2RangeMatcher extends Layer2AbstractMatcher {
  20     /**
  21      * The range this {@link Layer2RangeMatcher} is searching for.
  22      */
  23     private final List<PcapPacket> mLowerBound;
  24     private final List<PcapPacket> mUpperBound;
  25     private final double mEps;
  26
  27     /**
  28      * Create a {@code Layer2RangeMatcher}.
  29      * @param lowerBound The lower bound of the sequence to match against (search for).
  30      * @param upperBound The upper bound of the sequence to match against (search for).
  31      * @param eps The epsilon value used in the DBSCAN algorithm.
  32      */
  33     public Layer2RangeMatcher(List<PcapPacket> lowerBound, List<PcapPacket> upperBound, double eps) {
  34         // TODO: Just use the lower bound since both lower and upper bounds' packets essentially have the same direction
  35         // TODO: for the same position in the array. Both arrays also have the same length.
  36         super(lowerBound);
  37         mLowerBound = lowerBound;
  38         mUpperBound = upperBound;
  39         mEps = eps;
  40     }
  41
  42     /**
  43      * Attempt to advance this {@code Layer2RangeMatcher} by matching {@code packet} against the packet that this
  44      * {@code Layer2RangeMatcher} expects as the next packet of the sequence it is searching for.
  45      * @param packet
  46      * @return {@code true} if this {@code Layer2SequenceMatcher} could advance by adding {@code packet} to its set of
  47      *         matched packets, {@code false} otherwise.
  48      */
  49     public boolean matchPacket(PcapPacket packet) {
  50         if (getMatchedPacketsCount() == getTargetSequencePacketCount()) {
  51             // We already matched the entire sequence, so we can't match any more packets.
  52             return false;
  53         }
  54
  55         // Verify that new packet pertains to same flow as previously matched packets, if any.
  56         if (getMatchedPacketsCount() > 0) {
  57             MacAddress pktSrc = PcapPacketUtils.getEthSrcAddr(packet);
  58             MacAddress pktDst = PcapPacketUtils.getEthDstAddr(packet);
  59             MacAddress earlierPktSrc = PcapPacketUtils.getEthSrcAddr(mMatchedPackets.get(0));
  60             MacAddress earlierPktDst = PcapPacketUtils.getEthDstAddr(mMatchedPackets.get(0));
  61             if (!(pktSrc.equals(earlierPktSrc) && pktDst.equals(earlierPktDst) ||
  62                     pktSrc.equals(earlierPktDst) && pktDst.equals(earlierPktSrc))) {
  63                 return false;
  64             }
  65         }
  66
  67         // Get representative of the packet we expect to match next.
  68         PcapPacket expectedLowerBound = mLowerBound.get(mMatchedPackets.size());
  69         PcapPacket expectedUpperBound = mUpperBound.get(mMatchedPackets.size());
  70         // First verify if the received packet has the length we're looking for (the length should be within the range).
  71         if (expectedLowerBound.getOriginalLength() - (int) mEps <= packet.getOriginalLength() &&
  72                 packet.getOriginalLength() <= expectedUpperBound.getOriginalLength() + (int) mEps){
  73             // If this is the first packet, we only need to verify that its length is correct. Time constraints are
  74             // obviously satisfied as there are no previous packets. Furthermore, direction matches by definition as we
  75             // don't know the MAC of the device (or phone) in advance, so we can't enforce a rule saying "first packet
  76             // must originate from this particular MAC".
  77             if (getMatchedPacketsCount() == 0) {
  78                 // Store packet as matched and advance.
  79                 mMatchedPackets.add(packet);
  80                 return true;
  81             }
  82             // Check if direction of packet matches expected direction.
  83             boolean actualDirection = getPacketDirection(mMatchedPackets.get(getMatchedPacketsCount()-1),
  84                     mPacketDirections[getMatchedPacketsCount()-1], packet);
  85             boolean expectedDirection = mPacketDirections[getMatchedPacketsCount()];
  86             if (actualDirection != expectedDirection) {
  87                 return false;
  88             }
  89             // Next apply timing constraints:
  90             // 1: to be a match, the packet must have a later timestamp than any other packet currently matched
  91             // 2: does adding the packet cause the max allowed time between first packet and last packet to be exceeded?
  92             if (!packet.getTimestamp().isAfter(mMatchedPackets.get(getMatchedPacketsCount()-1).getTimestamp())) {
  93                 return false;
  94             }
  95             if (packet.getTimestamp().isAfter(mMatchedPackets.get(0).getTimestamp().
  96                     plusMillis(TriggerTrafficExtractor.INCLUSION_WINDOW_MILLIS))) {
  97                 return false;
  98             }
  99             // If we made it here, it means that this packet has the expected length, direction, and obeys the timing
 100             // constraints, so we store it and advance.
 101             mMatchedPackets.add(packet);
 102             if (mMatchedPackets.size() == mLowerBound.size()) {
 103                 // TODO report (to observers?) that we are done?
 104             }
 105             return true;
 106         }
 107         return false;
 108     }
 109
 110     public int getTargetSequencePacketCount() {
 111         return mLowerBound.size();
 112     }
 113
 114     public List<PcapPacket> getTargetLowerBound() {
 115         return mLowerBound;
 116     }
 117
 118     public List<PcapPacket> getTargetUpperBound() {
 119         return mLowerBound;
 120     }
 121 }