def on_block_request(self, messages):
        for message in messages:
            block_id = message.payload.dictionary['block_id']
            self.logger.debug('Got block-request for id %s', b64encode(block_id))

            block = self.data_manager.get_block(block_id)
            if block is not None:
                self.send_message(u'block', (message.candidate,), {'block': block.to_dict()})