MINOR: protocol: add a ->drain() function at the connection control layer
This is what we need to drain pending incoming data from an connection.
The code was taken from conn_sock_drain() without the connection-specific
stuff. It still takes a connection for now for API simplicity.
diff --git a/src/proto_uxst.c b/src/proto_uxst.c
index 1c6ea77..9b1fc38 100644
--- a/src/proto_uxst.c
+++ b/src/proto_uxst.c
@@ -63,6 +63,7 @@
.ctrl_init = sock_conn_ctrl_init,
.ctrl_close = sock_conn_ctrl_close,
.connect = uxst_connect_server,
+ .drain = sock_drain,
/* binding layer */
.rx_suspend = uxst_suspend_receiver,