Checkpoint

internal/netutil/arp/arp.go

@@ -0,0 +1,63 @@
+package arp
+
+import (
+	"net"
+	"sync"
+	"time"
+
+	"github.com/sirupsen/logrus"
+)
+
+func init() {
+	go func() {
+		t := time.NewTicker(time.Second * 5)
+		for {
+			refresh()
+			<-t.C
+		}
+	}()
+}
+
+var table sync.Map
+
+func refresh() {
+	t, err := lookup()
+	if err != nil {
+		logrus.StandardLogger().WithError(err).Warn("arp cache refresh failed")
+	} else {
+		for k, v := range t {
+			logrus.StandardLogger().WithFields(logrus.Fields{
+				"mac": v,
+				"ip":  k,
+			}).Debug("Updating ARP cache")
+			table.Store(k, v)
+		}
+	}
+}
+
+func Get(addr net.Addr) net.HardwareAddr {
+	if addr == nil {
+		logrus.StandardLogger().Trace("No address found, can't lookup IP for MAC")
+		return nil
+	}
+
+	var ip net.IP
+	switch addr := addr.(type) {
+	case *net.TCPAddr:
+		ip = addr.IP
+	case *net.UDPAddr:
+		ip = addr.IP
+	}
+	if ip == nil {
+		logrus.StandardLogger().WithField("addr", addr.String()).Trace("No IP address found, can't lookup MAC")
+		return nil
+	}
+
+	if v, ok := table.Load(ip.String()); ok {
+		logrus.StandardLogger().WithField("ip", ip.String()).Tracef("%s is at %s", ip, v.(net.HardwareAddr).String())
+		return v.(net.HardwareAddr)
+	}
+
+	logrus.StandardLogger().WithField("ip", ip.String()).Trace("No MAC address found")
+	return nil
+}