convert over to unix sockets so we don't have to search for ports...

This is going to be what will be eventually used anyways, so it's
good to test it a bit early...

twistednoise.py

@@ -8,8 +8,11 @@ from twisted.internet import endpoints, reactor, defer, task
 from cryptography.hazmat.primitives.asymmetric import x448
 from cryptography.hazmat.primitives import serialization
 
-import twisted.internet.protocol
 import mock
+import os.path
+import shutil
+import tempfile
+import twisted.internet.protocol
 
 # Notes:
 # Using XK, so that the connecting party's identity is hidden and that the
@@ -95,6 +98,11 @@ class TwistedNoiseServerFactory(Factory):
 class TNServerTest(unittest.TestCase):
 	@defer.inlineCallbacks
 	def setUp(self):
+		d = os.path.realpath(tempfile.mkdtemp())
+		self.basetempdir = d
+		self.tempdir = os.path.join(d, 'subdir')
+		os.mkdir(self.tempdir)
+
 		self.server_key_pair = genkeypair()
 		self.protos = []
 		self.connectionmade = defer.Deferred()
@@ -113,21 +121,16 @@ class TNServerTest(unittest.TestCase):
 				self.__tc.protos.append(r)
 				return r
 
-		for i in range(10000, 20000):
-			ep = endpoints.TCP4ServerEndpoint(reactor, i, interface='127.0.0.1')
-			try:
-				lpobj = yield ep.listen(AccProtFactory(self))
-			except Exception:	# pragma: no cover
-				continue
-			break
-		else:	# pragma: no cover
-			raise RuntimeError('all ports occupied')
+		sockpath = os.path.join(self.tempdir, 'clientsock')
+		ep = endpoints.UNIXServerEndpoint(reactor, sockpath)
+		lpobj = yield ep.listen(AccProtFactory(self))
 
 		self.testserv = ep
 		self.listenportobj = lpobj
-		self.endpoint = 'tcp:host=127.0.0.1:port=%d' % i
+		self.endpoint = 'unix:path=%s' % sockpath
+
 		factory = TwistedNoiseServerFactory(server_key=self.server_key_pair[1], endpoint=self.endpoint)
-		self.proto = factory.buildProtocol(('127.0.0.1', 0))
+		self.proto = factory.buildProtocol(None)
 		self.tr = proto_helpers.StringTransport()
 		self.proto.makeConnection(self.tr)
 
@@ -136,6 +139,9 @@ class TNServerTest(unittest.TestCase):
 	def tearDown(self):
 		self.listenportobj.stopListening()
 
+		shutil.rmtree(self.basetempdir)
+		self.tempdir = None
+
 	@defer.inlineCallbacks
 	def test_testprotocol(self):
 		# Create client