Revise multicast format to include protocol version, discriminator for TLS roots

src/multicast/advertisement_test.go

@@ -0,0 +1,38 @@
+package multicast
+
+import (
+	"crypto/ed25519"
+	"reflect"
+	"testing"
+)
+
+func TestMulticastAdvertisementRoundTrip(t *testing.T) {
+	pk, sk, err := ed25519.GenerateKey(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	orig := multicastAdvertisement{
+		MajorVersion:  1,
+		MinorVersion:  2,
+		PublicKey:     pk,
+		Port:          3,
+		Discriminator: sk, // any bytes will do
+	}
+
+	ob, err := orig.MarshalBinary()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var new multicastAdvertisement
+	if err := new.UnmarshalBinary(ob); err != nil {
+		t.Fatal(err)
+	}
+
+	if !reflect.DeepEqual(orig, new) {
+		t.Logf("original: %+v", orig)
+		t.Logf("new:      %+v", new)
+		t.Fatalf("differences found after round-trip")
+	}
+}