wsdiscovery/daemon.py
def addSourceAddr(self, addr):
        """None means 'system default'"""
        try:
            self._multiInSocket.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, self._makeMreq(addr))
        except socket.error:  # if 1 interface has more than 1 address, exception is raised for the second
            pass

        sock = self._createMulticastOutSocket(addr, self._observer.ttl)
        self._multiOutUniInSockets[addr] = sock
        self._poll.register(sock, select.POLLIN)
def addSourceAddr(self, addr):
        """None means 'system default'"""
        try:
            self._multiInSocket.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, self._makeMreq(addr))
        except socket.error:  # if 1 interface has more than 1 address, exception is raised for the second
            pass

        sock = self._createMulticastOutSocket(addr, self._observer.ttl)
        self._multiOutUniInSockets[addr] = sock
        self._poll.register(sock, select.POLLIN)
None means 'system default