It looks like string's length prefix is 32bit
@@ -35,9 +35,9 @@ The following data types are used in the descriptions:
* - ``byte``
- 8-bit unsigned integer
* - ``string``
- - a UTF-8 encoded text string prefixed with its byte length as ``int16``
+ - a UTF-8 encoded text string prefixed with its byte length as ``int32``
* - ``bytes``
- - a byte string prefixed with its length as ``int16``
+ - a byte string prefixed with its length as ``int32``
* - ``Headers``
- a key-value structure with the following layout:
