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63#!/usr/bin/env -S unshare --user --map-root-user --net -- strace -e %net -- python
"""
Quiz #6
-------
>>> s1 = socket(AF_INET, SOCK_STREAM)
>>> s1.bind(('127.0.0.1', 60_000))
>>> s1.connect(('127.8.8.8', 1234))
>>> s1.getsockname(), s1.getpeername()
(('127.0.0.1', 60000), ('127.8.8.8', 1234))
>>>
>>> s2 = socket(AF_INET, SOCK_STREAM)
>>> s2.bind(('127.0.0.1', 60_000))
Traceback (most recent call last):
...
OSError: [Errno 98] Address already in use
>>>
Outcome: FAILURE. Local (IP, port) can't be shared.
Cleanup:
>>> p1, _ = ln.accept()
>>> p1.close() # TIME-WAIT on server side
>>> s1.close()
>>> s2.close()
>>>
Solution #6
-----------
Use `SO_REUSEADDR` socket option.
>>> s1 = socket(AF_INET, SOCK_STREAM)
>>> s1.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
>>> s1.bind(('127.0.0.1', 60_000))
>>> s1.connect(('127.8.8.8', 1234))
>>> s1.getsockname(), s1.getpeername()
(('127.0.0.1', 60000), ('127.8.8.8', 1234))
>>>
>>> s2 = socket(AF_INET, SOCK_STREAM)
>>> s2.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
>>> s2.bind(('127.0.0.1', 60_000))
>>> s2.connect(('127.9.9.9', 1234))
>>> s2.getsockname(), s2.getpeername()
(('127.0.0.1', 60000), ('127.9.9.9', 1234))
>>>
Outcome: SUCCESS. Local (IP, port) is shared when using `SO_REUSEADDR`.
Cleanup:
>>> s1.close()
>>> s2.close()
"""
from quiz_common import run_doctest
from socket import *
if __name__ == "__main__":
run_doctest(__name__)