rules:
- id: socket-shutdown-close
  patterns:
    - pattern: |
        $SOCK.shutdown(socket.$A)
        $SOCK.close()
    - pattern-not-inside: |
        try:
            ...
        except ...:
            ...
            $SOCK.close()
    - pattern-not-inside: |
        try:
            ...
        finally:
            ...
            $SOCK.close()
  message: >-
      Socket is not closed if shutdown fails. When socket.shutdown fails on an
      OSError, socket.close is not called and the code fails to clean up the socket
      and allow garbage collection to release the memory used for it. The OSError on
      shutdown can occur when the remote side of the connection closes the connection
      first.
  metadata:
    references:
    - https://www.paulsprogrammingnotes.com/2021/12/python-memory-leaks.html
    category: 'correctness'
    technology: 
      - python
  languages: [python]
  severity: WARNING