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
+}