select the right null AEAD algorithm depending on the version

crypto/null_aead.go

@@ -0,0 +1,14 @@
+package crypto
+
+import "github.com/lucas-clemente/quic-go/internal/protocol"
+
+// NewNullAEAD creates a NullAEAD
+func NewNullAEAD(p protocol.Perspective, v protocol.VersionNumber) AEAD {
+	if v == protocol.VersionTLS {
+		return &nullAEADFNV64a{}
+	}
+	return &nullAEADFNV128a{
+		perspective: p,
+		version:     v,
+	}
+}

crypto/null_aead_fnv128a.go

@@ -16,14 +16,6 @@ type nullAEADFNV128a struct {
 
 var _ AEAD = &nullAEADFNV128a{}
 
-// NewNullAEAD creates a NullAEAD
-func NewNullAEAD(p protocol.Perspective, v protocol.VersionNumber) AEAD {
-	return &nullAEADFNV128a{
-		perspective: p,
-		version:     v,
-	}
-}
-
 // Open and verify the ciphertext
 func (n *nullAEADFNV128a) Open(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) ([]byte, error) {
 	if len(src) < 12 {

crypto/null_aead_test.go

@@ -0,0 +1,17 @@
+package crypto
+
+import (
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("NullAEAD", func() {
+	It("selects the right FVN variant", func() {
+		Expect(NewNullAEAD(protocol.PerspectiveClient, protocol.Version39)).To(Equal(&nullAEADFNV128a{
+			perspective: protocol.PerspectiveClient,
+			version:     protocol.Version39,
+		}))
+		Expect(NewNullAEAD(protocol.PerspectiveClient, protocol.VersionTLS)).To(Equal(&nullAEADFNV64a{}))
+	})
+})

internal/protocol/version.go

@@ -10,6 +10,7 @@ const (
 	Version37
 	Version38
 	Version39
+	VersionTLS         VersionNumber = 101
 	VersionWhatever    VersionNumber = 0 // for when the version doesn't matter
 	VersionUnsupported VersionNumber = -1
 	VersionUnknown     VersionNumber = -2