Adding skipped packets correlation.
[pingpong.git] / Code / Projects / PacketLevelSignatureExtractor / src / main / java / edu / uci / iotproject / detection / layer2 / Layer2ClusterMatcher.java
index a3f4d0e..5bf4655 100644 (file)
@@ -28,7 +28,7 @@ public class Layer2ClusterMatcher extends AbstractClusterMatcher implements Laye
      * of {@link #mCluster} and has so far matched {@code j} packets of that particular sequence.
      */
     private final Map<Layer2Flow, Layer2SequenceMatcher[][]> mPerFlowSeqMatchers = new HashMap<>();
-    private final Map<Layer2Flow, Layer2RangeMatcher[]> mPerFlowRangeMatcher = new HashMap<>();
+    private final Map<Layer2Flow, List<Layer2RangeMatcher>> mPerFlowRangeMatcher = new HashMap<>();
 
     private final Function<Layer2Flow, Boolean> mFlowFilter;
 
@@ -44,14 +44,22 @@ public class Layer2ClusterMatcher extends AbstractClusterMatcher implements Laye
 
     private int mInclusionTimeMillis;
 
+    /**
+     * Keeping track of maximum number of skipped packets
+     */
+    private int mMaxSkippedPackets;
+//    private List<Integer> mMaxSkippedPackets;
+
+    private int mLimitSkippedPackets;
+
     /**
      * Create a new {@link Layer2ClusterMatcher} that attempts to find occurrences of {@code cluster}'s members.
      * @param cluster The sequence mutations that the new {@link Layer2ClusterMatcher} should search for.
      */
     public Layer2ClusterMatcher(List<List<PcapPacket>> cluster, int inclusionTimeMillis,
-                                boolean isRangeBased, double eps) {
+                                boolean isRangeBased, double eps, int limitSkippedPackets) {
         // Consider all flows if no flow filter specified.
-        this(cluster, flow -> true, inclusionTimeMillis, isRangeBased, eps);
+        this(cluster, flow -> true, inclusionTimeMillis, isRangeBased, eps, limitSkippedPackets);
     }
 
     /**
@@ -68,13 +76,17 @@ public class Layer2ClusterMatcher extends AbstractClusterMatcher implements Laye
      * @param eps The epsilon value used in the DBSCAN algorithm.
      */
     public Layer2ClusterMatcher(List<List<PcapPacket>> cluster, Function<Layer2Flow, Boolean> flowFilter,
-                                int inclusionTimeMillis, boolean isRangeBased, double eps) {
+                                int inclusionTimeMillis, boolean isRangeBased, double eps, int limitSkippedPackets) {
         super(cluster, isRangeBased);
         mFlowFilter = flowFilter;
         mRangeBased = isRangeBased;
         mEps = eps;
         mInclusionTimeMillis =
                 inclusionTimeMillis == 0 ? TriggerTrafficExtractor.INCLUSION_WINDOW_MILLIS : inclusionTimeMillis;
+        mMaxSkippedPackets = 0;
+//        mMaxSkippedPackets = new ArrayList<>();
+        // Give integer's MAX_VALUE if -1
+        mLimitSkippedPackets = limitSkippedPackets == -1 ? Integer.MAX_VALUE : limitSkippedPackets;
     }
 
     @Override
@@ -117,8 +129,12 @@ public class Layer2ClusterMatcher extends AbstractClusterMatcher implements Laye
                 boolean matched = sm.matchPacket(newPacket);
                 if (matched) {
                     if (sm.getMatchedPacketsCount() == sm.getTargetSequencePacketCount()) {
-                        // Sequence matcher has a match. Report it to observers.
-                        mObservers.forEach(o -> o.onMatch(this, sm.getMatchedPackets()));
+                        // Update maximum skipped packets
+                        boolean stillMatch = checkMaxSkippedPackets(flow.getPackets(), sm.getMatchedPackets());
+                        if (stillMatch) {
+                            // Sequence matcher has a match. Report it to observers.
+                            mObservers.forEach(o -> o.onMatch(this, sm.getMatchedPackets()));
+                        }
                         // Remove the now terminated sequence matcher.
                         matchers[i][j] = null;
                     } else {
@@ -143,54 +159,80 @@ public class Layer2ClusterMatcher extends AbstractClusterMatcher implements Laye
         }
     }
 
+    // Update the maximum number of skipped packets
+    private boolean checkMaxSkippedPackets(List<PcapPacket> flowPackets, List<PcapPacket> matchedPackets) {
+        // Count number of skipped packets by looking into
+        // the difference of indices of two matched packets
+        boolean stillMatch = true;
+        for(int i = 1; i < matchedPackets.size(); ++i) {
+            int currIndex = flowPackets.indexOf(matchedPackets.get(i-1));
+            int nextIndex = flowPackets.indexOf(matchedPackets.get(i));
+            int skippedPackets = nextIndex - currIndex;
+            if (mMaxSkippedPackets < skippedPackets) {
+                mMaxSkippedPackets = skippedPackets;
+                stillMatch = false;
+            }
+//            mMaxSkippedPackets.add(skippedPackets);
+        }
+        return stillMatch;
+    }
+
     private void rangeBasedMatching(Layer2Flow flow, PcapPacket newPacket) {
-        // TODO: For range-based matching, we only care about matching a range; therefore it is a matcher array.
+        // TODO: For range-based matching, we need to create a new matcher every time we see the first element of
+        //  the sequence (between lower and upper bounds).
         if (mPerFlowRangeMatcher.get(flow) == null) {
-            // If this is the first time we encounter this flow, we need to set up a sequence matcher.
-            // All sequences of the cluster have the same length, so we only need to compute the length of the
-            // arrays once. We want to make room for a cluster matcher in each state, including the initial empty state
-            // but excluding the final "full match" state (as there is no point in keeping a terminated sequence matcher
-            // around), so the length of the array is simply the sequence length.
-            Layer2RangeMatcher[] matcher = new Layer2RangeMatcher[mCluster.get(0).size()];
+            // If this is the first time we encounter this flow, we need to set up a list of sequence matchers.
+            List<Layer2RangeMatcher> listMatchers = new ArrayList<>();
             // Prepare a "state 0" sequence matcher.
-            matcher[0] = new Layer2RangeMatcher(mCluster.get(0), mCluster.get(1), mInclusionTimeMillis, mEps);
+            Layer2RangeMatcher matcher = new Layer2RangeMatcher(mCluster.get(0), mCluster.get(1),
+                    mInclusionTimeMillis, mEps);
+            listMatchers.add(matcher);
             // Associate the new sequence matcher table with the new flow.
-            mPerFlowRangeMatcher.put(flow, matcher);
+            mPerFlowRangeMatcher.put(flow, listMatchers);
         }
         // Fetch table that contains sequence matchers for this flow.
-        Layer2RangeMatcher[] matcher = mPerFlowRangeMatcher.get(flow);
-        // Present packet to the sequence matcher.
-        for (int j = matcher.length - 1; j >= 0; j--) {
-            Layer2RangeMatcher sm = matcher[j];
-            if (sm == null) {
-                // There is currently no sequence matcher that has managed to match j packets.
-                continue;
+        List<Layer2RangeMatcher> listMatchers = mPerFlowRangeMatcher.get(flow);
+        // Add a new matcher if all matchers have already advanced to the next stage.
+        // We always need a new matcher to match from NO packets.
+        boolean addOneArray = true;
+        for(Layer2RangeMatcher matcher : listMatchers) {
+            if (matcher.getMatchedPacketsCount() == 0) {
+                addOneArray = false;
             }
-            boolean matched = sm.matchPacket(newPacket);
-            if (matched) {
-                if (sm.getMatchedPacketsCount() == sm.getTargetSequencePacketCount()) {
-                    // Sequence matcher has a match. Report it to observers.
-                    mObservers.forEach(o -> o.onMatch(this, sm.getMatchedPackets()));
-                    // Remove the now terminated sequence matcher.
-                    matcher[j] = null;
-                } else {
-                    // Sequence matcher advanced one step, so move it to its corresponding new position iff the
-                    // packet that advanced it has a later timestamp than that of the last matched packet of the
-                    // sequence matcher at the new index, if any. In most traces, a small amount of the packets
-                    // appear out of order (with regards to their timestamp), which is why this check is required.
-                    // Obviously it would not be needed if packets where guaranteed to be processed in timestamp
-                    // order here.
-                    if (matcher[j+1] == null ||
-                            newPacket.getTimestamp().isAfter(matcher[j+1].getLastPacket().getTimestamp())) {
-                        matcher[j+1] = sm;
+        }
+        // Add the new matcher into the list
+        if (addOneArray) {
+            Layer2RangeMatcher newMatcher = new Layer2RangeMatcher(mCluster.get(0), mCluster.get(1),
+                    mInclusionTimeMillis, mEps);
+            listMatchers.add(newMatcher);
+        }
+        // Present packet to the sequence matchers.
+        // Make a shallow copy of the list so that we can clean up the actual list when a matcher is terminated.
+        // Otherwise, we would get an exception for changing the list while iterating on it.
+        List<Layer2RangeMatcher> listMatchersCopy = new ArrayList<>(listMatchers);
+        for(Layer2RangeMatcher matcher : listMatchersCopy) {
+            Layer2RangeMatcher sm = matcher;
+            // Check if no packets are matched yet or if there are matched packets, the next packet to be matched
+            // has to be later than the last matched packet.
+            // In most traces, a small amount of the packets appear out of order (with regards to their timestamp),
+            // which is why this check is required.
+            // Obviously it would not be needed if packets where guaranteed to be processed in timestamp
+            // order here.
+            if (sm.getMatchedPacketsCount() == 0 ||
+                    newPacket.getTimestamp().isAfter(sm.getLastPacket().getTimestamp())) {
+                boolean matched = sm.matchPacket(newPacket);
+                if (matched) {
+                    if (sm.getMatchedPacketsCount() == sm.getTargetSequencePacketCount()) {
+                        // Update maximum skipped packets
+                        boolean stillMatch = checkMaxSkippedPackets(flow.getPackets(), sm.getMatchedPackets());
+                        if (stillMatch) {
+                            // Sequence matcher has a match. Report it to observers.
+                            mObservers.forEach(o -> o.onMatch(this, sm.getMatchedPackets()));
+                        }
+                        // Terminate sequence matcher since matching is complete.
+                        listMatchers.remove(matcher);
                     }
                 }
-                // We always want to have a sequence matcher in state 0, regardless of if the one that advanced
-                // from state zero completed its matching or if it replaced a different one in state 1 or not.
-                if (sm.getMatchedPacketsCount() == 1) {
-                    matcher[j] = new Layer2RangeMatcher(sm.getTargetLowerBound(), sm.getTargetUpperBound(),
-                            mInclusionTimeMillis, mEps);
-                }
             }
         }
     }
@@ -232,4 +274,14 @@ public class Layer2ClusterMatcher extends AbstractClusterMatcher implements Laye
             System.out.println(">>> IGNORING FLOW: " + newFlow + " <<<");
         }
     }
+
+    /**
+      * Return the maximum number of skipped packets.
+      */
+    public int getMaxSkippedPackets() {
+       return mMaxSkippedPackets;
+    }
+//    public List<Integer> getMaxSkippedPackets() {
+//        return mMaxSkippedPackets;
+//    }
 }