+ /**
+ * Merge signatures in {@code List} of {@code List} of {@code List} of {@code PcapPacket} objects.
+ * We cross-check these with {@code List} of {@code Conversation} objects to see
+ * if two {@code List} of {@code PcapPacket} objects actually belong to the same {@code Conversation}.
+ * @param signatures A {@link List} of {@link List} of {@link List} of
+ * {@link PcapPacket} objects that needs to be checked and merged.
+ * @param conversations A {@link List} of {@link Conversation} objects as reference for merging.
+ * @return A {@link List} of {@link List} of {@link List} of
+ * {@link PcapPacket} objects as the result of the merging.
+ */
+ public static List<List<List<PcapPacket>>>
+ mergeSignatures(List<List<List<PcapPacket>>> signatures, List<Conversation> conversations) {
+
+ // TODO: THIS IS NOT A DEEP COPY; IT BASICALLY CREATES A REFERENCE TO THE SAME LIST OBJECT
+ // List<List<List<PcapPacket>>> copySignatures = new ArrayList<>(signatures);
+ // Make a deep copy first.
+ List<List<List<PcapPacket>>> copySignatures = new ArrayList<>();
+ listDeepCopy(copySignatures, signatures);
+ // Traverse and look into the pairs of signatures.
+ for (int first = 0; first < signatures.size(); first++) {
+ List<List<PcapPacket>> firstList = signatures.get(first);
+ for (int second = first+1; second < signatures.size(); second++) {
+ int maxSignatureEl = 0; // Number of maximum signature elements.
+ List<List<PcapPacket>> secondList = signatures.get(second);
+ int initialSecondListMembers = secondList.size();
+ // Iterate over the signatures in the first list.
+ for (List<PcapPacket> signature : firstList) {
+ signature.removeIf(el -> el == null); // Clean up null elements.
+ // Return the Conversation that the signature is part of.
+ Conversation conv = TcpConversationUtils.returnConversation(signature, conversations);
+ // Find the element of the second list that is a match for that Conversation.
+ for (List<PcapPacket> ppList : secondList) {
+ ppList.removeIf(el -> el == null); // Clean up null elements.
+ // Check if they are part of a Conversation and are adjacent to the first signature.
+ // If yes then merge into the first list.
+ TcpConversationUtils.SignaturePosition position =
+ TcpConversationUtils.isPartOfConversationAndAdjacent(signature, ppList, conv);
+ if (position == TcpConversationUtils.SignaturePosition.LEFT_ADJACENT) {
+ // Merge to the left side of the first signature.
+ ppList.addAll(signature);
+ signature = ppList;
+ maxSignatureEl = signature.size() > maxSignatureEl ? signature.size() : maxSignatureEl;
+ secondList.remove(ppList); // Remove as we merge.
+ break;
+ } else if (position == TcpConversationUtils.SignaturePosition.RIGHT_ADJACENT) {
+ // Merge to the right side of the first signature.
+ signature.addAll(ppList);
+ maxSignatureEl = signature.size() > maxSignatureEl ? signature.size() : maxSignatureEl;
+ secondList.remove(ppList); // Remove as we merge.
+ break;
+ } // TcpConversationUtils.SignaturePosition.NOT_ADJACENT.
+ }
+ }
+ // Call it a successful merging if there are only less than 5 elements from the second list that
+ // cannot be merged.
+ if (secondList.size() < SIGNATURE_MERGE_THRESHOLD) {
+ // Prune the unsuccessfully merged signatures (i.e., these will have size() < maxSignatureEl).
+ final int maxNumOfEl = maxSignatureEl;
+ // TODO: DOUBLE CHECK IF WE REALLY NEED TO PRUNE FAILED BINDINGS
+ // TODO: SOMETIMES THE SEQUENCES ARE JUST INCOMPLETE
+ // TODO: AND BOTH THE COMPLETE AND INCOMPLETE SEQUENCES ARE VALID SIGNATURES!
+ firstList.removeIf(el -> el.size() < maxNumOfEl);
+ // Remove the merged set of signatures when successful.
+ signatures.remove(secondList);
+ } else if (secondList.size() < initialSecondListMembers) {
+ // If only some of the signatures from the second list are merged, this means UNSUCCESSFUL merging.
+ // Return the original copy of the signatures object.
+ return copySignatures;
+ }
+ }
+ }
+ return signatures;
+ }
+
+ /**
+ * Deep copy to create an entirely new {@link List} of {@link List} of {@link List} of {@link PcapPacket} objects.
+ * @param destList A {@link List} of {@link List} of {@link List} of
+ * {@link PcapPacket} objects that will be the final container of the deep copy
+ * @param sourceList A {@link List} of {@link List} of {@link List} of
+ * {@link PcapPacket} objects that will be the source of the deep copy.
+ */
+ private static void listDeepCopy(List<List<List<PcapPacket>>> destList, List<List<List<PcapPacket>>> sourceList) {
+
+ for(List<List<PcapPacket>> llPcapPacket : sourceList) {
+ List<List<PcapPacket>> tmpListOfList = new ArrayList<>();
+ for(List<PcapPacket> lPcapPacket : llPcapPacket) {
+ List<PcapPacket> tmpList = new ArrayList<>();
+ for(PcapPacket pcapPacket : lPcapPacket) {
+ tmpList.add(pcapPacket);
+ }
+ tmpListOfList.add(tmpList);
+ }
+ destList.add(tmpListOfList);
+ }
+ }
+
+ /**
+ * Sort the signatures in the {@code List} of {@code List} of {@code List} of {@code PcapPacket} objects.
+ * The purpose of this is to sort the order of signatures in the signature list. For detection purposes, we need
+ * to know if one signature occurs earlier/later in time with respect to the other signatures for more confidence
+ * in detecting the occurrence of an event.
+ * @param signatures A {@code List} of {@code List} of {@code List} of {@code PcapPacket} objects that needs sorting.
+ * We assume that innermost {@code List} of {@code PcapPacket} objects have been sorted ascending
+ * by timestamps. By the time we use this method, we should have sorted it when calling the
+ * {@code clusterToListOfPcapPackets} method.
+ * @return A sorted {@code List} of {@code List} of {@code List} of {@code PcapPacket} objects.
+ */
+ public static List<List<List<PcapPacket>>> sortSignatures(List<List<List<PcapPacket>>> signatures) {
+ // TODO: This is the simplest solution!!! Might not cover all corner cases.
+ // TODO: Sort the list of lists based on the first packet's timestamps!
+ //Collections.sort(signatures, (p1, p2) -> {
+ // return p1.get(0).get(0).getTimestamp().compareTo(p2.get(0).get(0).getTimestamp());
+ //});
+ // TODO: The following is a more complete solution that covers corner cases.
+ // Sort the list of lists based on one-to-one comparison between timestamps of signatures on both lists.
+ // This also takes into account the fact that the number of signatures in the two lists could be different.
+ // Additionally, this code forces the comparison between two signatures only if they occur in the
+ // INCLUSION_WINDOW_MILLIS window; otherwise, it tries to find the right pair of signatures in the time window.
+ Collections.sort(signatures, (p1, p2) -> {
+ int compare = 0;
+ int comparePrev = 0;
+ int count1 = 0;
+ int count2 = 0;
+ // Need to make sure that both are not out of bound!
+ while (count1 + 1 < p1.size() && count2 + 1 < p2.size()) {
+ long timestamp1 = p1.get(count1).get(0).getTimestamp().toEpochMilli();
+ long timestamp2 = p2.get(count2).get(0).getTimestamp().toEpochMilli();
+ // The two timestamps have to be within a 15-second window!
+ if (Math.abs(timestamp1 - timestamp2) < TriggerTrafficExtractor.INCLUSION_WINDOW_MILLIS) {
+ // If these two are within INCLUSION_WINDOW_MILLIS window then compare!
+ compare = p1.get(count1).get(0).getTimestamp().compareTo(p2.get(count2).get(0).getTimestamp());
+ if (comparePrev != 0) { // First time since it is 0
+ if (Integer.signum(compare) != Integer.signum(comparePrev)) {
+ // Throw an exception if the order of the two signatures is not consistent,
+ // E.g., 111, 222, 333 in one occassion and 222, 333, 111 in the other.
+ throw new Error("For some reason, the order of signatures are not always consistent!" +
+ "Returning the original data structure of signatures...");
+ }
+ }
+ comparePrev = compare;
+ count1++;
+ count2++;
+ } else {
+ // If not within INCLUSION_WINDOW_MILLIS window then find the correct pair
+ // by incrementing one of them.
+ if (timestamp1 < timestamp2)
+ count1++;
+ else
+ count2++;
+ }
+ }
+ return compare;
+ });
+ return signatures;
+ }
+
+ /**
+ * Gets the {@link IpV4Packet} contained in {@code packet}, or throws a {@link NullPointerException} if
+ * {@code packet} does not contain an {@link IpV4Packet}.
+ * @param packet A {@link PcapPacket} that is expected to contain a {@link IpV4Packet}.
+ * @return The {@link IpV4Packet} contained in {@code packet}.
+ * @throws NullPointerException if {@code packet} does not encapsulate an {@link IpV4Packet}.
+ */
+ private static IpV4Packet getIpV4PacketOrThrow(PcapPacket packet) {
+ return Objects.requireNonNull(packet.get(IpV4Packet.class), "not an IPv4 packet");
+ }
+
+ /**
+ * Print signatures in {@code List} of {@code List} of {@code List} of {@code PcapPacket} objects.
+ *
+ * @param signatures A {@link List} of {@link List} of {@link List} of
+ * {@link PcapPacket} objects that needs to be printed.
+ */
+ public static void printSignatures(List<List<List<PcapPacket>>> signatures) {
+
+ // Iterate over the list of all clusters/sequences
+ int sequenceCounter = 0;
+ for(List<List<PcapPacket>> listListPcapPacket : signatures) {
+ // Iterate over every member of a cluster/sequence
+ System.out.print("====== SEQUENCE " + sequenceCounter++);
+ System.out.println(" - " + listListPcapPacket.size() + " MEMBERS ======");
+ for(List<PcapPacket> listPcapPacket : listListPcapPacket) {
+ // Print out packet lengths in a sequence
+ int packetCounter = 0;
+ for(PcapPacket pcapPacket : listPcapPacket) {
+ if(pcapPacket != null) {
+ System.out.print(pcapPacket.length());
+ }
+ if(packetCounter < listPcapPacket.size() - 1) {
+ System.out.print(" "); // Provide space if not last packet
+ } else {
+ System.out.println(); // Newline if last packet
+ }
+ packetCounter++;
+ }
+ }
+ }
+ }
+
+ /**
+ * Remove a sequence in a signature object.
+ *
+ * @param signatures A {@link List} of {@link List} of {@link List} of
+ * {@link PcapPacket} objects.
+ * @param sequenceIndex An index for a sequence that consists of {{@link List} of {@link List} of
+ * {@link PcapPacket} objects.
+ */
+ public static void removeSequenceFromSignature(List<List<List<PcapPacket>>> signatures, int sequenceIndex) {
+
+ // Sequence index starts from 0
+ signatures.remove(sequenceIndex);
+ }