fix. nl.DeserializeRtNexthop return.

Return a full created nl.RtNexthop ptr to avoid the
"converted pointer straddles multiple allocations".

UT by fasaxc.

Co-authored-by: fasaxc
Signed-off-by: Javier Garcia <javier.martin.garcia@ibm.com>

nl/route_linux.go

@@ -48,7 +48,9 @@ type RtNexthop struct {
 }
 
 func DeserializeRtNexthop(b []byte) *RtNexthop {
-	return (*RtNexthop)(unsafe.Pointer(&b[0:unix.SizeofRtNexthop][0]))
+	return &RtNexthop{
+		RtNexthop: *((*unix.RtNexthop)(unsafe.Pointer(&b[0:unix.SizeofRtNexthop][0]))),
+	}
 }
 
 func (msg *RtNexthop) Len() int {

nl/route_linux_test.go

@@ -42,3 +42,26 @@ func TestRtMsgDeserializeSerialize(t *testing.T) {
 	msg := DeserializeRtMsg(orig)
 	testDeserializeSerialize(t, orig, safemsg, msg)
 }
+
+func TestDeserializeRtNexthop(t *testing.T) {
+	buf := make([]byte, unix.SizeofRtNexthop+64)
+	native := NativeEndian()
+	native.PutUint16(buf[0:2], unix.SizeofRtNexthop)
+	buf[2] = 17
+	buf[3] = 1
+	native.PutUint32(buf[4:8], 1234)
+
+	msg := DeserializeRtNexthop(buf)
+	safemsg := &RtNexthop{
+		unix.RtNexthop{
+			Len:     unix.SizeofRtNexthop,
+			Flags:   17,
+			Hops:    1,
+			Ifindex: 1234,
+		},
+		nil,
+	}
+	if msg.Len() != safemsg.Len() || msg.Flags != safemsg.Flags || msg.Hops != safemsg.Hops || msg.Ifindex != safemsg.Ifindex {
+		t.Fatal("Deserialization failed.\nIn:", buf, "\nOut:", msg, "\n", msg.Serialize(), "\nExpected:", safemsg, "\n", safemsg.Serialize())
+	}
+}