add VersionName present in go tls library (#468)

Co-authored-by: Phillip Stephens <phillip@cs.stanford.edu>

Author: Joey574

tls/common.go

@@ -42,6 +42,26 @@ const (
 	VersionSSL30 = 0x0300
 )
 
+// VersionName returns the name for the provided TLS version number
+// (e.g. "TLS 1.3"), or a fallback representation of the value if the
+// version is not implemented by this package.
+func VersionName(version uint16) string {
+	switch version {
+	case VersionSSL30:
+		return "SSLv3"
+	case VersionTLS10:
+		return "TLS 1.0"
+	case VersionTLS11:
+		return "TLS 1.1"
+	case VersionTLS12:
+		return "TLS 1.2"
+	case VersionTLS13:
+		return "TLS 1.3"
+	default:
+		return fmt.Sprintf("0x%04X", version)
+	}
+}
+
 const (
 	maxPlaintext        = 16384        // maximum plaintext payload length
 	maxCiphertext       = 16384 + 2048 // maximum ciphertext payload length