move connection ID generation from the utils to the protocol package

internal/protocol/connection_id.go

@@ -0,0 +1,19 @@
+package protocol
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+)
+
+// A ConnectionID in QUIC
+type ConnectionID uint64
+
+// GenerateConnectionID generates a connection ID using cryptographic random
+func GenerateConnectionID() (ConnectionID, error) {
+	b := make([]byte, 8)
+	_, err := rand.Read(b)
+	if err != nil {
+		return 0, err
+	}
+	return ConnectionID(binary.LittleEndian.Uint64(b)), nil
+}

internal/protocol/connection_id_test.go

@@ -0,0 +1,17 @@
+package protocol
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Connection ID generation", func() {
+	It("generates random connection IDs", func() {
+		c1, err := GenerateConnectionID()
+		Expect(err).ToNot(HaveOccurred())
+		Expect(c1).ToNot(BeZero())
+		c2, err := GenerateConnectionID()
+		Expect(err).ToNot(HaveOccurred())
+		Expect(c1).ToNot(Equal(c2))
+	})
+})

internal/protocol/protocol.go

@@ -52,9 +52,6 @@ func (t PacketType) String() string {
 	}
 }
 
-// A ConnectionID in QUIC
-type ConnectionID uint64
-
 // A ByteCount in QUIC
 type ByteCount uint64