* @return A handle for the channel, or NULL in case of an error.
*/
channel *channel_open(node *node, uint16_t port, channel_receive_cb_t cb, const void *data, size_t len) {
* @return A handle for the channel, or NULL in case of an error.
*/
channel *channel_open(node *node, uint16_t port, channel_receive_cb_t cb, const void *data, size_t len) {