Ensure that all form data is read to content-length

phew/server.py

@@ -243,7 +243,14 @@ async def _handle_request(self, reader, writer):
       if request.headers["content-type"].startswith("application/json"):
         request.data = await _parse_json_body(reader, request.headers)
       if request.headers["content-type"].startswith("application/x-www-form-urlencoded"):
-        form_data = await reader.read(int(request.headers["content-length"]))
+        form_data = b""
+        content_length = int(request.headers["content-length"])
+        while content_length > 0:
+            data = await reader.read(content_length)
+            if len(data) == 0:
+              break
+            content_length -= len(data)
+            form_data += data
         request.form = _parse_query_string(form_data.decode())
 
     route = self._match_route(request)