add tcp test-client too

client.py

@@ -0,0 +1,49 @@
+from __future__ import print_function
+
+from twisted.internet import endpoints
+from twisted.internet.defer import (
+    Deferred,
+)
+from twisted.internet.task import react
+from twisted.internet.error import (
+    ConnectionDone,
+)
+from twisted.internet.protocol import (
+    Protocol,
+    Factory,
+)
+
+
+class RelayEchoClient(Protocol):
+    """
+    Speaks the version1 magic wormhole transit relay protocol (as a client)
+    """
+
+    def connectionMade(self):
+        print(">CONNECT")
+        self.data = b""
+        self.transport.write(u"please relay {}\n".format(self.factory.token).encode("ascii"))
+
+    def dataReceived(self, data):
+        print(">RECV {} bytes".format(len(data)))
+        print(data.decode("ascii"))
+        self.data += data
+        if data == "ok\n":
+            self.transport.write("ding\n")
+
+    def connectionLost(self, reason):
+        if isinstance(reason.value, ConnectionDone):
+            self.factory.done.callback(None)
+        else:
+            print(">DISCONNCT: {}".format(reason))
+            self.factory.done.callback(reason)
+
+
+@react
+def main(reactor):
+    ep = endpoints.clientFromString(reactor, "tcp:localhost:4001")
+    f = Factory.forProtocol(RelayEchoClient)
+    f.token = "a" * 64
+    f.done = Deferred()
+    ep.connect(f)
+    return f.done