Added a log message to catch gaps in packet sequence number - ie. we

didn't get one or more packets from libpcap. I have one trace on
PlanetLab that does this a lot, so it could be a sign of a problem -
like not checking libpcap freqeuently enough. A pcapper process
running at the same time did get the packets...

pelab/magent/PacketSensor.cc

@@ -94,12 +94,26 @@ void PacketSensor::localSend(PacketInfo * packet)
                "PacketSensor::localSend() new record: ss=%u,sl=%u,se=%u,tl=%u",
                record.seqStart, sequenceLength, record.seqEnd,
                record.totalLength);
-      globalSequence.seqEnd = record.seqEnd;
       if (unacked.empty())
       {
         globalSequence.seqStart = record.seqStart;
         globalSequence.seqEnd = record.seqEnd;
       }
+      else
+      {
+        /*
+         * Sanity check - the new packet we're adding should start where the
+         * last one left off
+         */
+        if (record.seqStart != (globalSequence.seqEnd + 1))
+        {
+          logWrite(EXCEPTION,"PacketSensor::localSend() may have missed a "
+                   "packet - last seq seen: %d, new seq: %d (lost %d)",
+                   globalSequence.seqEnd,record.seqStart,
+                   record.seqStart - globalSequence.seqEnd);
+        }
+        globalSequence.seqEnd = record.seqEnd;
+      }
       logWrite(SENSOR,
                "PacketSensor::localSend(): global start = %u, global end = %u",
                globalSequence.seqStart, globalSequence.seqEnd);