Added wireshark mode, fixed DHCP bug

README.md

@@ -52,6 +52,8 @@ Usage of ./proxy:
         Main switch sock path, - for stdin/out (default "/run/vde/sw_main.sock")
   -sproxy string
         Proxy switch sock path (default "/run/vde/sw_proxy1.sock")
+  -wireshark
+        Whether to write all traffic to /tmp
 ```
 
 ### envctl - control VMs, network etc

proxy/main.go

@@ -35,6 +35,7 @@ var DHCPMask []byte
 var DHCPState dhcp4.MessageType
 var DHCPCandidate net.IP
 var UId string
+var Wireshark bool
 
 // Start the two plugs and run two concurrent forward methods
 func main() {
@@ -49,6 +50,7 @@ func main() {
 	sockProxy := flag.String("sproxy", "/run/vde/sw_proxy1.sock", "Proxy switch sock path")
 	pidFile := flag.String("pidfile", "", "Location to write the pid to")
 	logFile := flag.String("logfile", "", "Location to write output to")
+	wireshark := flag.Bool("wireshark", false, "Whether to write all traffic to /tmp")
 	flag.Parse()
 	log.SetLevel(log.Level(*logLvl))
 	OldMAC, _ = net.ParseMAC(*oldMAC)
@@ -56,6 +58,7 @@ func main() {
 	OldIP = net.ParseIP(*oldIP).To4()
 	NewIP = net.ParseIP(*newIP).To4()
 	Passthrough = *passthrough
+	Wireshark = *wireshark
 	UId = GenerateUId(*sockProxy)
 	log.SetFormatter(&log.TextFormatter{
 		DisableTimestamp: true,
@@ -114,9 +117,12 @@ func pipeForward(prefix string) {
 			log.Fatal(prefix, "Error reading frame data")
 		}
 
+		if Wireshark {
+			WritePcap("/tmp/pkg_"+strconv.FormatInt(time.Now().Unix(), 10)+".pcap", frameBytes)
+		}
+
 		// Convert frame to full stack packet
 		packet := gopacket.NewPacket(frameBytes, layers.LayerTypeEthernet, gopacket.Default)
-		// isInteresting := false // Debug Help
 
 		// Handle Ethernet frame
 		frame := packet.Layer(layers.LayerTypeEthernet).(*layers.Ethernet)
@@ -129,10 +135,12 @@ func pipeForward(prefix string) {
 			log.Debug("IP Protocol ", ipv4Packet.Protocol)
 
 			// Handle DHCPv4 packet (based on IPv4)
-			if dhcpLayer := packet.Layer(layers.LayerTypeDHCPv4); dhcpLayer != nil && !Passthrough {
+			if dhcpLayer := packet.Layer(layers.LayerTypeDHCPv4); dhcpLayer != nil {
+				if !Passthrough {
 					handleDHCP(dhcpLayer.LayerContents(), frame.DstMAC, frame.SrcMAC, prefix)
 					continue
 				}
+			}
 
 			filterIP(prefix, &ipv4Packet.DstIP, &ipv4Packet.SrcIP, ipv4Packet.LayerType())
 
@@ -146,7 +154,15 @@ func pipeForward(prefix string) {
 			if tcpLayer := packet.Layer(layers.LayerTypeTCP); tcpLayer != nil {
 				tcpPacket, _ := tcpLayer.(*layers.TCP)
 				if err := tcpPacket.SetNetworkLayerForChecksum(ipv4Packet); err != nil {
-					log.Error(prefix, "Error setting network layer for checksum", err)
+					log.Error(prefix, "Error setting network layer for TCP checksum", err)
+				}
+			}
+
+			// Handle UDP packet
+			if udpLayer := packet.Layer(layers.LayerTypeUDP); udpLayer != nil {
+				udpPacket, _ := udpLayer.(*layers.UDP)
+				if err := udpPacket.SetNetworkLayerForChecksum(ipv4Packet); err != nil {
+					log.Error(prefix, "Error setting network layer for UDP checksum", err)
 				}
 			}
 		}
@@ -189,13 +205,6 @@ func pipeForward(prefix string) {
 		newFrameLength := make([]byte, 2)
 		binary.BigEndian.PutUint16(newFrameLength, uint16(len(newFrameBytes)))
 
-		// Write interesting things to debug file
-		/*if isInteresting {
-			WriteBinary(fmt.Sprintf("/tmp/pck_%di.dat", time.Now().Unix()), frameBytes)
-			WriteBinary(fmt.Sprintf("/tmp/pck_%do.dat", time.Now().Unix()), newFrameBytes)
-			//WritePcapNg("xyz.pcap", packet.Data(), packet.Metadata().CaptureInfo)
-		}*/
-
 		// Forward modified frame to other plug
 		if _, err := writer.Write(newFrameLength); err != nil {
 			log.Error("Error forwarding packet length", err)
@@ -412,7 +421,7 @@ func sendDHCPReply(req dhcp4.Packet, mt dhcp4.MessageType, lease net.IP, reqOpt
 		TTL:      128,
 		Protocol: layers.IPProtocolUDP,
 		SrcIP:    DHCPIP,
-		DstIP:    lease,
+		DstIP:    net.IPv4bcast,
 	}
 	udp := layers.UDP{
 		SrcPort: 67,
@@ -454,7 +463,7 @@ func sendDHCPRequest(mt dhcp4.MessageType, reqIP net.IP) {
 	}
 	eth := layers.Ethernet{
 		SrcMAC:       NewMAC,
-		DstMAC:       If(mt == dhcp4.Discover).MAC([]byte{255,255,255,255,255,255}, DHCPMAC),
+		DstMAC:       If(mt == dhcp4.Discover).MAC([]byte{255, 255, 255, 255, 255, 255}, DHCPMAC),
 		EthernetType: layers.EthernetTypeIPv4,
 	}
 	ipv4 := layers.IPv4{
@@ -492,7 +501,6 @@ func sendDHCPRequest(mt dhcp4.MessageType, reqIP net.IP) {
 		log.Error("Error serializing DHCP request: ", err)
 	}
 	packetData := buf.Bytes()
-	WritePcap("/tmp/dhcpreq_" +strconv.FormatInt(time.Now().Unix(), 10)+ ".pcap", packetData)
 
 	// Sending layer through VM's pipe
 	packetLength := make([]byte, 2)