icmp: don't fail test on big endian machine

Change-Id: I5ceede6cf0aa4fcdbf59c39e1aff9826874f2710
Reviewed-on: https://go-review.googlesource.com/22677
Reviewed-by: Ian Lance Taylor <iant@golang.org>

icmp/ipv4_test.go

@@ -5,6 +5,7 @@
 package icmp
 
 import (
+	"encoding/binary"
 	"net"
 	"reflect"
 	"runtime"
@@ -13,25 +14,30 @@ import (
 	"golang.org/x/net/ipv4"
 )
 
-var (
-	wireHeaderFromKernel = [ipv4.HeaderLen]byte{
+type ipv4HeaderTest struct {
+	wireHeaderFromKernel        [ipv4.HeaderLen]byte
+	wireHeaderFromTradBSDKernel [ipv4.HeaderLen]byte
+	Header                      *ipv4.Header
+}
+
+var ipv4HeaderLittleEndianTest = ipv4HeaderTest{
+	// TODO(mikio): Add platform dependent wire header formats when
+	// we support new platforms.
+	wireHeaderFromKernel: [ipv4.HeaderLen]byte{
 		0x45, 0x01, 0xbe, 0xef,
 		0xca, 0xfe, 0x45, 0xdc,
 		0xff, 0x01, 0xde, 0xad,
 		172, 16, 254, 254,
 		192, 168, 0, 1,
-	}
-	wireHeaderFromTradBSDKernel = [ipv4.HeaderLen]byte{
+	},
+	wireHeaderFromTradBSDKernel: [ipv4.HeaderLen]byte{
 		0x45, 0x01, 0xef, 0xbe,
 		0xca, 0xfe, 0x45, 0xdc,
 		0xff, 0x01, 0xde, 0xad,
 		172, 16, 254, 254,
 		192, 168, 0, 1,
-	}
-	// TODO(mikio): Add platform dependent wire header formats when
-	// we support new platforms.
-
-	testHeader = &ipv4.Header{
+	},
+	Header: &ipv4.Header{
 		Version:  ipv4.Version,
 		Len:      ipv4.HeaderLen,
 		TOS:      1,
@@ -44,28 +50,33 @@ var (
 		Checksum: 0xdead,
 		Src:      net.IPv4(172, 16, 254, 254),
 		Dst:      net.IPv4(192, 168, 0, 1),
-	}
-)
+	},
+}
 
 func TestParseIPv4Header(t *testing.T) {
+	tt := &ipv4HeaderLittleEndianTest
+	if nativeEndian != binary.LittleEndian {
+		t.Skip("no test for non-little endian machine yet")
+	}
+
 	var wh []byte
 	switch runtime.GOOS {
 	case "darwin":
-		wh = wireHeaderFromTradBSDKernel[:]
+		wh = tt.wireHeaderFromTradBSDKernel[:]
 	case "freebsd":
 		if freebsdVersion >= 1000000 {
-			wh = wireHeaderFromKernel[:]
+			wh = tt.wireHeaderFromKernel[:]
 		} else {
-			wh = wireHeaderFromTradBSDKernel[:]
+			wh = tt.wireHeaderFromTradBSDKernel[:]
 		}
 	default:
-		wh = wireHeaderFromKernel[:]
+		wh = tt.wireHeaderFromKernel[:]
 	}
 	h, err := ParseIPv4Header(wh)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !reflect.DeepEqual(h, testHeader) {
-		t.Fatalf("got %#v; want %#v", h, testHeader)
+	if !reflect.DeepEqual(h, tt.Header) {
+		t.Fatalf("got %#v; want %#v", h, tt.Header)
 	}
 }