[Twisted-Python] listenTCP & listenSSL failing silently?

[Matthew Pounsett]

I’ve bumped into a weird one, and can’t figure out what I’m missing.  

    for iface in interfaces:
        for port in ports:
            logger.debug("Listening on {}:{}".format(iface, port))
            if use_ssl:
                reactor.listenSSL(port, factory,
                    ssl.DefaultOpenSSLContextFactory(ssl_key, ssl_cert),
                    interface=iface)
            else:
                reactor.listenTCP(port, factory, interface=iface)

In the above code block, listenSSL() and listenTCP() both fail silently.  They do not raise an exception, and netstat reports nothing listening on the appropriate port.  

Even weirder, if I assign the results of listenSSL() and listenTCP(), then then a v6 connection will succeed but v4 still fails (silently).

I get the same behaviour for both (so, regardless of the value of use_ssl in this code).

    for iface in interfaces:
        for port in ports:
            logger.debug("Listening on {}:{}".format(iface, port))
            if use_ssl:
                connector = reactor.listenSSL(port, factory,
                    ssl.DefaultOpenSSLContextFactory(ssl_key, ssl_cert),
                    interface=iface)
            else:
                connector = reactor.listenTCP(port, factory, interface=iface)
            logger.debug( "Connected with connector: {}".format(connector))
            logger.debug( "Connector on host {}".format(connector.getHost()))


19:33:43 http       Listening on 127.0.0.1:1812
19:33:43 http       Connected with connector: <<class 'twisted.internet.tcp.Port'> of twisted.protocols.tls.TLSMemoryBIOFactory on 1812>
19:33:43 http       Connector on host IPv4Address(TCP, '127.0.0.1', 1812)
19:33:43 http       Listening on ::1:1812
19:33:43 http       Connected with connector: <<class 'twisted.internet.tcp.Port'> of twisted.protocols.tls.TLSMemoryBIOFactory on 1812>
19:33:43 http       Connector on host IPv6Address(TCP, '::1', 1812)
19:33:43 http       Listening on 10.0.2.4:1812
19:33:43 http       Connected with connector: <<class 'twisted.internet.tcp.Port'> of twisted.protocols.tls.TLSMemoryBIOFactory on 1812>
19:33:43 http       Connector on host IPv4Address(TCP, '10.0.2.4', 1812)

> netstat -an | egrep '\.1812.*LISTEN'
tcp6       0      0 ::1.1812               *.*                    LISTEN

I’ve used this exact recipe before without any trouble (the first block, with unassigned results from reactor.listen*).. I can’t figure out what I’m missing this time.   Does anything stand out to anyone?

Using py27-twisted-13.2.0 port on FreeBSD 9.2.