trace arbitrary length Connection IDs for Version Negotiation packets

internal/protocol/connection_id.go

@@ -20,6 +20,13 @@ func (c ArbitraryLenConnectionID) Bytes() []byte {
 	return c
 }
 
+func (c ArbitraryLenConnectionID) String() string {
+	if c.Len() == 0 {
+		return "(empty)"
+	}
+	return fmt.Sprintf("%x", c.Bytes())
+}
+
 // A ConnectionID in QUIC
 type ConnectionID []byte
 

internal/protocol/connection_id_test.go

@@ -119,5 +119,15 @@ var _ = Describe("Connection ID generation", func() {
 			c := ArbitraryLenConnectionID(make([]byte, 156))
 			Expect(c.Len()).To(Equal(156))
 		})
+
+		It("has a string representation", func() {
+			c := ArbitraryLenConnectionID([]byte{0xde, 0xad, 0xbe, 0xef, 0x42})
+			Expect(c.String()).To(Equal("deadbeef42"))
+		})
+
+		It("has a string representation for the default value", func() {
+			var c ArbitraryLenConnectionID
+			Expect(c.String()).To(Equal("(empty)"))
+		})
 	})
 })