classification
Title: data_received called on protocol after call to pause_reading on ssl transport
Type: behavior Stage:
Components: asyncio Versions: Python 3.10
process
Status: open Resolution:
Dependencies: Superseder:
Assigned To: Nosy List: asvetlov, chrisb2, yselivanov
Priority: normal Keywords:

Created on 2021-09-10 04:23 by chrisb2, last changed 2021-09-10 04:23 by chrisb2.

Messages (1)
msg401553 - (view) Author: Christopher Brichford (chrisb2) Date: 2021-09-10 04:23
An SSL connection created with loop.create_connection may have data_received called on its protocol after pause_reading has been called on the transport.

If an application has a protocol whose data_received method calls pause_reading on the transport then there is a chance that the data_received method will be called again before the application calls resume_reading on the transport.

That existing implementation of pause_reading at:
https://github.com/python/cpython/blob/62fa613f6a6e872723505ee9d56242c31a654a9d/Lib/asyncio/sslproto.py#L335

calls pause_reading on the underlying socket transport, which is correct.  However, there is a loop in the SSLProtocol's data_received method:
https://github.com/python/cpython/blob/62fa613f6a6e872723505ee9d56242c31a654a9d/Lib/asyncio/sslproto.py#L335

If the loop referenced above has more than one iteration then there is a chance that the application protocol's data_received method could call pause_reading on the transport.  If that happens on any iteration of the loop other than the last iteration, then the SSLProtocol's data_received method will call the application protocol's data_received method when it should not.

Stealing uvloop's asyncio ssl implementation would resolve this bug: https://bugs.python.org/issue44011
History
Date User Action Args
2021-09-10 04:23:52chrisb2create