TestHandshake_SimultaneousConnect and congestion test

[laddersky]

1. in TestHandshake_SimultaneousConnect, do client and server send packet to myself? if so, how it can be possible although listen() does not exist.
2. In PA2 documentation, test_congestion and test_transfer is not graded. So, I do not have to implement read() and write()? if so, what does meaning of existence of read() and write() and test_congestion, test_transfer?
3. in testclose(),

what does meaning of above code?
why sleep_time(=close time - current time) should be greater or equal than zero??

[lgm9]

1. In the real cases, multiple clients might try to connect to the server. This test simulate those cases. Server could make a handshake if ready.
2. Isn't it unreliable cases? If so, it's PA3.
3. It prevents pre-closing.