implement version-dependent parsing of the Public Header

internal/utils/byteorder_test.go

@@ -0,0 +1,18 @@
+package utils
+
+import (
+	"github.com/lucas-clemente/quic-go/protocol"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Byte Order", func() {
+	It("says little Little Endian before QUIC 39", func() {
+		Expect(GetByteOrder(protocol.Version36)).To(Equal(LittleEndian))
+		Expect(GetByteOrder(protocol.Version37)).To(Equal(LittleEndian))
+	})
+
+	It("says little Little Endian for QUIC 39", func() {
+		Expect(GetByteOrder(protocol.Version39)).To(Equal(BigEndian))
+	})
+})