func main() { defer util.Run()() var handle *pcap.Handle var err error // Set up pcap packet capture if *fname != "" { log.Printf("Reading from pcap dump %q", *fname) handle, err = pcap.OpenOffline(*fname) } else { log.Printf("Starting capture on interface %q", *iface) handle, err = pcap.OpenLive(*iface, int32(*snaplen), true, pcap.BlockForever) } if err != nil { log.Fatal(err) } if err := handle.SetBPFFilter(*filter); err != nil { log.Fatal(err) } // Set up assembly streamFactory := &httpStreamFactory{} streamPool := tcpassembly.NewStreamPool(streamFactory) assembler := tcpassembly.NewAssembler(streamPool) log.Println("reading in packets") // Read in packets, pass to assembler. packetSource := gopacket.NewPacketSource(handle, handle.LinkType()) packets := packetSource.Packets() ticker := time.Tick(time.Minute) for { select { case packet := <-packets: // A nil packet indicates the end of a pcap file. if packet == nil { return } if *logAllPackets { log.Println(packet) } if packet.NetworkLayer() == nil || packet.TransportLayer() == nil || packet.TransportLayer().LayerType() != layers.LayerTypeTCP { log.Println("Unusable packet") continue } tcp := packet.TransportLayer().(*layers.TCP) assembler.AssembleWithTimestamp(packet.NetworkLayer().NetworkFlow(), tcp, packet.Metadata().Timestamp) case <-ticker: // Every minute, flush connections that haven't seen activity in the past 2 minutes. assembler.FlushOlderThan(time.Now().Add(time.Minute * -2)) } } }