From 965ca414a683f3a1efbc21041d534715f8fc9e8d Mon Sep 17 00:00:00 2001
From: Song Gao <song@gao.io>
Date: Sun, 8 Nov 2015 21:54:47 +0000
Subject: [PATCH 1/3] add ipv4 broadcast test

---
 ipv4_test.go       | 89 ++++++++++++++++++++++++++++++++++++++++++++++
 ipv4_test_linux.go | 16 +++++++++
 ipv4_test_other.go | 12 +++++++
 3 files changed, 117 insertions(+)
 create mode 100644 ipv4_test.go
 create mode 100644 ipv4_test_linux.go
 create mode 100644 ipv4_test_other.go

diff --git a/ipv4_test.go b/ipv4_test.go
new file mode 100644
index 0000000..5c38901
--- /dev/null
+++ b/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")
+		}
+	}
+}
diff --git a/ipv4_test_linux.go b/ipv4_test_linux.go
new file mode 100644
index 0000000..b5b680c
--- /dev/null
+++ b/ipv4_test_linux.go
@@ -0,0 +1,16 @@
+package water
+
+import (
+	"net"
+	"os/exec"
+	"testing"
+)
+
+func setupIfce(t *testing.T, ipNet net.IPNet, dev string) {
+	if err := exec.Command("ip", "link", "set", dev, "up").Run(); err != nil {
+		t.Fatal(err)
+	}
+	if err := exec.Command("ip", "addr", "add", ipNet.String(), "dev", dev).Run(); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/ipv4_test_other.go b/ipv4_test_other.go
new file mode 100644
index 0000000..d70a50f
--- /dev/null
+++ b/ipv4_test_other.go
@@ -0,0 +1,12 @@
+// +build !linux
+
+package water
+
+import (
+	"net"
+	"testing"
+)
+
+func setupIfce(t *testing.T, ipNet net.IPNet, dev string) {
+	t.Fatal("unsupported platform")
+}

From d8e4f41ac8da9c1133cadaeed61bdef703ca8f51 Mon Sep 17 00:00:00 2001
From: Song Gao <song@gao.io>
Date: Wed, 11 Nov 2015 22:12:44 +0000
Subject: [PATCH 2/3] use time.Timer

---
 ipv4_test.go | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/ipv4_test.go b/ipv4_test.go
index 5c38901..84cb523 100644
--- a/ipv4_test.go
+++ b/ipv4_test.go
@@ -11,13 +11,6 @@ import (
 
 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 {
@@ -54,8 +47,7 @@ func TestBroadcast(t *testing.T) {
 	dataCh := make(chan []byte, 8)
 	startRead(dataCh, ifce)
 
-	timeout := make(chan bool, 1)
-	startTimeout(timeout, time.Second*8)
+	timeout := time.NewTimer(8 * time.Second).C
 
 readFrame:
 	for {

From acc2c8967a6ba6b45035155a6403292bf311e394 Mon Sep 17 00:00:00 2001
From: Song Gao <song@gao.io>
Date: Thu, 19 Nov 2015 19:24:13 +0000
Subject: [PATCH 3/3] return error instead of panic()

---
 ipv4_test.go      | 2 +-
 syscalls_other.go | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/ipv4_test.go b/ipv4_test.go
index 84cb523..f855521 100644
--- a/ipv4_test.go
+++ b/ipv4_test.go
@@ -38,7 +38,7 @@ func TestBroadcast(t *testing.T) {
 
 	ifce, err := NewTAP("test")
 	if err != nil {
-		t.Fatal(err)
+		t.Fatalf("creating TAP error: %v\n", err)
 	}
 
 	setupIfce(t, net.IPNet{IP: self, Mask: mask}, ifce.Name())
diff --git a/syscalls_other.go b/syscalls_other.go
index a38ce85..ace8c3c 100644
--- a/syscalls_other.go
+++ b/syscalls_other.go
@@ -2,10 +2,12 @@
 
 package water
 
+import "errors"
+
 func newTAP(ifName string) (ifce *Interface, err error) {
-	panic("water: tap interface not implemented on this platform")
+	return nil, errors.New("tap interface not implemented on this platform")
 }
 
 func newTUN(ifName string) (ifce *Interface, err error) {
-	panic("water: tap interface not implemented on this platform")
+	return nil, errors.New("tap interface not implemented on this platform")
 }