From: Janus Varmarken <varmarken@gmail.com>
Date: Sun, 29 Apr 2018 07:49:12 +0000 (-0700)
Subject: Filter out retransmissions when reconstructing TCP flows. Now able to detect all... 
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=384a838085fb80075c9da1cecef542ff31ff9f43;p=pingpong.git

Filter out retransmissions when reconstructing TCP flows. Now able to detect all local ON events in wlan1.local.dns.pcap.
---

diff --git a/Code/Projects/SmartPlugDetector/src/main/java/edu/uci/iotproject/FlowPatternFinder.java b/Code/Projects/SmartPlugDetector/src/main/java/edu/uci/iotproject/FlowPatternFinder.java
index c8f8fe2..8c7d41e 100644
--- a/Code/Projects/SmartPlugDetector/src/main/java/edu/uci/iotproject/FlowPatternFinder.java
+++ b/Code/Projects/SmartPlugDetector/src/main/java/edu/uci/iotproject/FlowPatternFinder.java
@@ -69,7 +69,13 @@ public class FlowPatternFinder {
                 listWrappedPacket.add(packet);
                 // Create new conversation entry, or append packet to existing.
                 connections.merge(conversation, listWrappedPacket, (v1, v2) -> {
-                    v1.addAll(v2);
+                    // TODO: in theory, this is insufficient to detect retransmissions due to TCP seq.no. rollover.
+                    // TODO: bad for performance, O(n) for each packet added to flow (n being length of the flow).
+                    boolean retransmission = v1.stream().anyMatch(p -> p.get(TcpPacket.class).getHeader().getSequenceNumber() == v2.get(0).get(TcpPacket.class).getHeader().getSequenceNumber());
+                    if (!retransmission) {
+                        // Do not add if retransmission -> avoid duplicate packets in flow
+                        v1.addAll(v2);
+                    }
                     return v1;
                 });
             }