add ipv4 broadcast test

ipv4_test.go

@@ -0,0 +1,89 @@
+package water
+
+import (
+	"net"
+	"os/exec"
+	"testing"
+	"time"
+
+	"github.com/songgao/water/waterutil"
+)
+
+const BUFFERSIZE = 1522
+
+func startTimeout(ch chan<- bool, t time.Duration) {
+	go func() {
+		time.Sleep(t)
+		ch <- true
+	}()
+}
+
+func startRead(ch chan<- []byte, ifce *Interface) {
+	go func() {
+		for {
+			buffer := make([]byte, BUFFERSIZE)
+			_, err := ifce.Read(buffer)
+			if err == nil {
+				ch <- buffer
+			}
+		}
+	}()
+}
+
+func startBroadcast(t *testing.T, dst net.IP) {
+	if err := exec.Command("ping", "-b", "-c", "2", dst.String()).Start(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestBroadcast(t *testing.T) {
+	var (
+		self = net.IPv4(10, 0, 42, 1)
+		mask = net.IPv4Mask(255, 255, 255, 0)
+		brd  = net.IPv4(10, 0, 42, 255)
+	)
+
+	ifce, err := NewTAP("test")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	setupIfce(t, net.IPNet{IP: self, Mask: mask}, ifce.Name())
+	startBroadcast(t, brd)
+
+	dataCh := make(chan []byte, 8)
+	startRead(dataCh, ifce)
+
+	timeout := make(chan bool, 1)
+	startTimeout(timeout, time.Second*8)
+
+readFrame:
+	for {
+		select {
+		case buffer := <-dataCh:
+			ethertype := waterutil.MACEthertype(buffer)
+			if ethertype != waterutil.IPv4 {
+				continue readFrame
+			}
+			if !waterutil.IsBroadcast(waterutil.MACDestination(buffer)) {
+				continue readFrame
+			}
+			packet := waterutil.MACPayload(buffer)
+			if !waterutil.IsIPv4(packet) {
+				continue readFrame
+			}
+			if !waterutil.IPv4Source(packet).Equal(self) {
+				continue readFrame
+			}
+			if !waterutil.IPv4Destination(packet).Equal(brd) {
+				continue readFrame
+			}
+			if waterutil.IPv4Protocol(packet) != waterutil.ICMP {
+				continue readFrame
+			}
+			break readFrame
+		case <-timeout:
+			t.Fatal("Waiting for broadcast packet timeout")
+		}
+	}
+}