Make SplitLabels faster

don't allocate a new string at all, it does not matter is the given
string is not fully qualified.

labels.go

@@ -129,13 +129,13 @@ func LenLabels(s string) int {
 }
 
 // Split splits a name s into its label indexes.
-// www.miek.nl. returns []int{0, 4, 9}. The root name (.) returns nil.
+// www.miek.nl. returns []int{0, 4, 9}, www.miek.nl also returns []int{0, 4, 9}
+// The root name (.) returns nil.
 func Split(s string) []int {
 	if s == "." {
 		return nil
 	}
-	s = Fqdn(s)     // Grrr!
-	idx := []int{0} // TODO(miek): could allocate more (10) and then extend when needed
+	idx := []int{0}
 	off := 0
 	end := false
 

labels_test.go

@@ -64,6 +64,20 @@ func TestSplit(t *testing.T) {
 	}
 }
 
+func TestSplit2(t *testing.T) {
+	splitter := map[string][]int{
+		"www.miek.nl.": []int{0, 4, 9},
+		"www.miek.nl":  []int{0, 4, 9},
+	}
+	for s, i := range splitter {
+		x := Split(s)
+		if x[0] != i[0] || x[1] != i[1] || x[2] != i[2] {
+			t.Logf("Labels should be %v, got %v: %s\n", i, x, s)
+			t.Fail()
+		}
+	}
+}
+
 func TestSplitDomainName(t *testing.T) {
 	labels := map[string][]string{
 		"miek.nl":       []string{"miek", "nl"},