Add more robust value comparison

upnp/utils_binary.go

@@ -0,0 +1,33 @@
+package upnp
+
+import (
+	"encoding/base64"
+	"encoding/hex"
+	"fmt"
+)
+
+// toBinary tries to convert v into a []byte.
+// - if v is []byte, returns it directly
+// - if v is string, attempts base64 decode, then hex decode
+func toBinary(v interface{}) ([]byte, error) {
+	switch val := v.(type) {
+	case []byte:
+		return val, nil
+
+	case string:
+		// Try base64 first
+		if data, err := base64.StdEncoding.DecodeString(val); err == nil {
+			return data, nil
+		}
+
+		// Try hex next
+		if data, err := hex.DecodeString(val); err == nil {
+			return data, nil
+		}
+
+		return nil, fmt.Errorf("cannot parse string as base64 or hex: %q", val)
+
+	default:
+		return nil, fmt.Errorf("cannot convert type %T to binary", v)
+	}
+}