Randomize new MAC [Close #15]

proxy/main.go

@@ -28,7 +28,7 @@ func main() {
 	oldip := flag.String("oldip", "", "IP before change")
 	newip := flag.String("newip", "10.0.0.15", "IP after change")
 	oldmac := flag.String("oldmac", "", "MAC before change")
-	newmac := flag.String("newmac", "52:54:00:12:34:aa", "MAC after change")
+	newmac := flag.String("newmac", "", "MAC after change")
 	passthrough := flag.Bool("passthrough", false, "Whether to pass every traffic through")
 	proxy := flag.String("proxy", "1", "Number of the proxy switch")
 	pidfile := flag.String("pidfile", "", "Location to write the pid to")
@@ -36,7 +36,7 @@ func main() {
 	flag.Parse()
 	log.SetLevel(log.Level(*logLvl))
 	OldMac, _ = net.ParseMAC(*oldmac)
-	NewMac, _ = net.ParseMAC(*newmac)
+	NewMac = util.GenerateMac(*newmac)
 	OldIP = net.ParseIP(*oldip).To4()
 	NewIP = net.ParseIP(*newip).To4()
 	log.SetFormatter(&log.TextFormatter{

proxy/util/util.go

@@ -1,11 +1,13 @@
 package util
 
 import (
+	"crypto/rand"
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
 	"github.com/google/gopacket/pcapgo"
 	log "github.com/sirupsen/logrus"
 	"io/ioutil"
+	"net"
 	"os"
 	"strconv"
 )
@@ -38,7 +40,25 @@ func WritePIDFile(filename string) {
 	if filename == "" {
 		return
 	}
-	if err := ioutil.WriteFile(filename, []byte(strconv.Itoa(os.Getpid())), 0644); err != nil {
+	if err := ioutil.WriteFile(filename, []byte(strconv.Itoa(os.Getpid()) + "\n"), 0644); err != nil {
 		log.Errorf("Error writing PID file %s", filename)
 	}
 }
+
+func GenerateMac(customMAC string) net.HardwareAddr {
+	if customMAC != "" {
+		ret, _ := net.ParseMAC("52:54:00:12:34:aa")
+		return ret
+	}
+	buf := make([]byte, 6)
+	var mac net.HardwareAddr
+	if _, err := rand.Read(buf); err != nil {
+		log.Error("Error generating random mac")
+		ret, _ := net.ParseMAC("52:54:00:12:34:aa")
+		return ret
+	}
+	// Set local bit, ensure unicast address
+	buf[0] = (buf[0] | 2) & 0xfe
+	mac = append(mac, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5])
+	return mac
+}