Handler that implements HTTP/HTTPS connections with Basic Auth.

    Sets auth headers using supplied 'username' and 'password', if set.
    Used by the push_to_gateway functions. Can be re-used by other handlers.

def basic_auth_handler(url, method, timeout, headers, data, username=None, password=None):
    """Handler that implements HTTP/HTTPS connections with Basic Auth.

    Sets auth headers using supplied 'username' and 'password', if set.
    Used by the push_to_gateway functions. Can be re-used by other handlers."""

    def handle():
        """Handler that implements HTTP Basic Auth.
        """
        if username is not None and password is not None:
            auth_value = '{0}:{1}'.format(username, password).encode('utf-8')
            auth_token = base64.b64encode(auth_value)
            auth_header = b'Basic ' + auth_token
            headers.append(['Authorization', auth_header])
        default_handler(url, method, timeout, headers, data)()

    return handle