endpoints requiring no body reply 408 on timeout

src/web_api/requests.pl

@@ -62,6 +62,8 @@ read_json_body_(Request, Payload) :-
 % @throws invalid_header_value(content_length, Value) if a Content-Length header 
 %         has been sent but the given value Value is invalid (no nonnegative 
 %         integer).
+% @throws `request_timeout` if discarded the body timed out (less bytes on the
+%         streem than promised by a Content-Length header).
 purge_input_stream(Request) :-
     memberchk(input(StreamIn), Request),
     memberchk(content_length(Len), Request),
@@ -69,13 +71,18 @@ purge_input_stream(Request) :-
     integer(Len),
     (   Len >= 0
     ->  setup_call_cleanup(open_null_stream(StreamOut),
-                            copy_stream_data(StreamIn, StreamOut, Len),
+                            purge_input_stream_(StreamIn, StreamOut, Len),
                             close(StreamOut)
     );  throw(invalid_header_value(content_length, Len))
     )
 .
 purge_input_stream(_).
 
+purge_input_stream_(StreamIn, StreamOut, Len) :-
+    catch(copy_stream_data(StreamIn, StreamOut, Len),
+          error(timeout_error(read, _Stream),_),
+          throw(request_timeout)
+    ).
 
 %! parse_parameters(+In, ++Type, -Out) is det.
 %