From 318eea05e32bcb7ae1331b4c7cd07836a7470369 Mon Sep 17 00:00:00 2001 From: Jean-Paul Calderone Date: Wed, 23 May 2018 10:59:42 -0400 Subject: [PATCH] docs --- src/allmydata/test/test_introducer.py | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/src/allmydata/test/test_introducer.py b/src/allmydata/test/test_introducer.py index 1653b1d04..8b35aca03 100644 --- a/src/allmydata/test/test_introducer.py +++ b/src/allmydata/test/test_introducer.py @@ -315,10 +315,23 @@ class Server(unittest.TestCase): NICKNAME = u"n\u00EDickname-%s" # LATIN SMALL LETTER I WITH ACUTE def foolscapEndpointForPortNumber(portnum): + """ + Create an endpoint that can be passed to ``Tub.listen``. + + :param portnum: Either an integer port number indicating which TCP/IPv4 + port number the endpoint should bind or ``None`` to automatically + allocate such a port number. + + :return: A two-tuple of the integer port number allocated and a + Foolscap-compatible endpoint object. + """ if portnum is None: from twisted.internet import reactor from twisted.internet.interfaces import IReactorSocket if IReactorSocket.providedBy(reactor): + # On POSIX we can take this very safe approach of binding the + # actual socket to an address. Once the bind succeeds here, we're + # no longer subject to any future EADDRINUSE problems. import fcntl from socket import socket, AF_INET from twisted.internet.endpoints import AdoptedStreamServerEndpoint @@ -338,7 +351,10 @@ def foolscapEndpointForPortNumber(portnum): finally: s.close() else: - # Get a random port number and fall through. + # Get a random port number and fall through. This is necessary on + # Windows where Twisted doesn't offer IReactorSocket. This + # approach is error prone for the reasons described on + # https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2787 portnum = iputil.allocate_tcp_port() return (portnum, "tcp:%d" % (portnum,))