gossip: Add function to notify gossipd about an outpoint spend

Signed-off-by: Christian Decker <decker.christian@gmail.com>

lightningd/chaintopology.c

@@ -16,6 +16,7 @@
 #include <common/timeout.h>
 #include <common/utils.h>
 #include <inttypes.h>
+#include <lightningd/gossip_control.h>
 
 /* Mutual recursion via timer. */
 static void try_extend_tip(struct chain_topology *topo);
@@ -415,6 +416,7 @@ static void topo_update_spends(struct chain_topology *topo, struct block *b)
 						     b->height, &input->txid,
 						     input->index);
 			if (scid) {
+				gossipd_notify_spend(topo->bitcoind->ld, scid);
 				tal_free(scid);
 			}
 		}

lightningd/gossip_control.c

@@ -216,6 +216,13 @@ void gossip_init(struct lightningd *ld)
 	subd_send_msg(ld->gossip, msg);
 }
 
+void gossipd_notify_spend(struct lightningd *ld,
+			  const struct short_channel_id *scid)
+{
+	u8 *msg = towire_gossip_outpoint_spent(tmpctx, scid);
+	subd_send_msg(ld->gossip, msg);
+}
+
 static void json_getnodes_reply(struct subd *gossip UNUSED, const u8 *reply,
 				const int *fds UNUSED,
 				struct command *cmd)

lightningd/gossip_control.h

@@ -1,10 +1,15 @@
 #ifndef LIGHTNING_LIGHTNINGD_GOSSIP_CONTROL_H
 #define LIGHTNING_LIGHTNINGD_GOSSIP_CONTROL_H
 #include "config.h"
+#include <bitcoin/short_channel_id.h>
 #include <ccan/short_types/short_types.h>
 #include <stdbool.h>
 
 struct lightningd;
 
 void gossip_init(struct lightningd *ld);
+
+void gossipd_notify_spend(struct lightningd *ld,
+			  const struct short_channel_id *scid);
+
 #endif /* LIGHTNING_LIGHTNINGD_GOSSIP_CONTROL_H */