daemon_conn: helper to release daemon_conn.

We'll want this for the next change, where gossipd migrates remote peers
back to local ones.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

common/daemon_conn.c

@@ -87,6 +87,12 @@ void daemon_conn_init(tal_t *ctx, struct daemon_conn *dc, int fd,
 		io_set_finish(conn, finish, dc);
 }
 
+void daemon_conn_clear(struct daemon_conn *dc)
+{
+	io_set_finish(dc->conn, NULL, NULL);
+	io_close(dc->conn);
+}
+
 void daemon_conn_send(struct daemon_conn *dc, const u8 *msg)
 {
 	msg_enqueue(&dc->out, msg);

common/daemon_conn.h

@@ -43,6 +43,16 @@ void daemon_conn_init(tal_t *ctx, struct daemon_conn *dc, int fd,
 		      struct io_plan *(*daemon_conn_recv)(
 			  struct io_conn *, struct daemon_conn *),
 		      void (*finish)(struct io_conn *, struct daemon_conn *));
+
+/**
+ * daemon_conn_clear - discard a daemon conn without triggering finish.
+ * @dc: the daemon_conn to clean up.
+ *
+ * This is used by gossipd when a peer is handed back, and we no longer
+ * want to deal with it via daemon_conn.  @dc must not be used after this!
+ */
+void daemon_conn_clear(struct daemon_conn *dc);
+
 /**
  * daemon_conn_send - Enqueue an outgoing message to be sent
  */