[GitHub] [incubator-nuttx] v01d opened a new issue #3384: TCP ISSUES WITH QUICK CLOSE

[GitBox <gi...@apache.org>]

v01d opened a new issue #3384:
URL: https://github.com/apache/incubator-nuttx/issues/3384


   ```
     Description: This failure has been reported in the accept() logic:
   
                  - psock_tcp_accept() waits on net_lockedwait() below
                  - The accept operation completes, the socket is in the connected
                    state and psock_accept() is awakened.  It cannot run,
                    however, because its priority is low and so it is blocked
                    from execution.
                  - In the mean time, the remote host sends a
                    packet which is presumably caught in the read-ahead buffer.
                 - Then the remote host closes the socket.  Nothing happens on
                    the target side because net_start_monitor() has not yet been
                    called.
                  - Then accept() finally runs, but not with a connected but
                    rather with a disconnected socket.  This fails when it
                    attempts to start the network monitor on the disconnected
                   socket below.
                  - It is also impossible to read the buffered TCP data from a
                    disconnected socket.  The TCP recvfrom() logic would also
                    need to permit reading buffered data from a disconnected
                    socket.
   
                  This problem was report when the target hosted an FTP server
                  and files were being accessed by FileZilla.
   
                  connect() most likely has this same issue.
   
                  A work-around might be to raise the priority of the thread
                  that calls accept().  accept() might also need to check the
                  tcpstateflags in the connection structure before returning
                  in order to assure that the socket truly is connected.
     Status:      Open
     Priority:    Medium.  I have never heard of this problem being reported
                  before, so I suspect it might not be so prevalent as one
                  might expect.
   ```


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