lightningd: check peers don't leave dangling HTLCs when they die.

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

lightningd/lightningd.c

@@ -198,6 +198,8 @@ static void shutdown_subdaemons(struct lightningd *ld)
 	close(ld->hsm_fd);
 	subd_shutdown(ld->gossip, 10);
 
+	free_htlcs(ld, NULL);
+
 	while ((p = list_top(&ld->peers, struct peer, list)) != NULL)
 		tal_free(p);
 }

lightningd/peer_control.c

@@ -90,6 +90,32 @@ static void peer_set_owner(struct peer *peer, struct subd *owner)
 
 static void destroy_peer(struct peer *peer)
 {
+	/* Must not have any HTLCs! */
+	struct htlc_out_map_iter outi;
+	struct htlc_out *hout;
+	struct htlc_in_map_iter ini;
+	struct htlc_in *hin;
+
+	for (hout = htlc_out_map_first(&peer->ld->htlcs_out, &outi);
+	     hout;
+	     hout = htlc_out_map_next(&peer->ld->htlcs_out, &outi)) {
+		if (hout->key.peer != peer)
+			continue;
+		fatal("Freeing peer %s has hout %s",
+		      peer_state_name(peer->state),
+		      htlc_state_name(hout->hstate));
+	}
+
+	for (hin = htlc_in_map_first(&peer->ld->htlcs_in, &ini);
+	     hin;
+	     hin = htlc_in_map_next(&peer->ld->htlcs_in, &ini)) {
+		if (hin->key.peer != peer)
+			continue;
+		fatal("Freeing peer %s has hin %s",
+		      peer_state_name(peer->state),
+		      htlc_state_name(hin->hstate));
+	}
+
 	/* Free any old owner still hanging around. */
 	peer_set_owner(peer, NULL);
 	list_del_from(&peer->ld->peers, &peer->list);
@@ -1163,7 +1189,8 @@ static void handle_onchain_htlc_timeout(struct peer *peer, const u8 *msg)
 	onchain_failed_our_htlc(peer, &htlc, "timed out");
 }
 
-static void handle_irrevocably_resolved(struct peer *peer, const u8 *msg)
+/* If peer is NULL, free them all (for shutdown) */
+void free_htlcs(struct lightningd *ld, const struct peer *peer)
 {
 	struct htlc_out_map_iter outi;
 	struct htlc_out *hout;
@@ -1175,25 +1202,31 @@ static void handle_irrevocably_resolved(struct peer *peer, const u8 *msg)
 
 	do {
 		deleted = false;
-		for (hout = htlc_out_map_first(&peer->ld->htlcs_out, &outi);
+		for (hout = htlc_out_map_first(&ld->htlcs_out, &outi);
 		     hout;
-		     hout = htlc_out_map_next(&peer->ld->htlcs_out, &outi)) {
-			if (hout->key.peer != peer)
+		     hout = htlc_out_map_next(&ld->htlcs_out, &outi)) {
+			if (peer && hout->key.peer != peer)
 				continue;
 			tal_free(hout);
 			deleted = true;
 		}
 
-		for (hin = htlc_in_map_first(&peer->ld->htlcs_in, &ini);
+		for (hin = htlc_in_map_first(&ld->htlcs_in, &ini);
 		     hin;
-		     hin = htlc_in_map_next(&peer->ld->htlcs_in, &ini)) {
-			if (hin->key.peer != peer)
+		     hin = htlc_in_map_next(&ld->htlcs_in, &ini)) {
+			if (peer && hin->key.peer != peer)
 				continue;
 			tal_free(hin);
 			deleted = true;
 		}
 		/* Can skip over elements due to iterating while deleting. */
 	} while (deleted);
+}
+
+static void handle_irrevocably_resolved(struct peer *peer, const u8 *msg)
+{
+	/* FIXME: Implement check_htlcs to ensure no dangling hout->in ptrs! */
+	free_htlcs(peer->ld, peer);
 
 	/* FIXME: Remove peer from db. */
 	log_info(peer->log, "onchaind complete, forgetting peer");

lightningd/peer_control.h

@@ -210,4 +210,6 @@ const char *peer_state_name(enum peer_state state);
 void peer_set_condition(struct peer *peer, enum peer_state oldstate,
 			enum peer_state state);
 void setup_listeners(struct lightningd *ld);
+
+void free_htlcs(struct lightningd *ld, const struct peer *peer);
 #endif /* LIGHTNING_LIGHTNINGD_PEER_CONTROL_H */

lightningd/test/run-find_my_path.c

@@ -19,6 +19,9 @@ int debug_poll(struct pollfd *fds UNNEEDED, nfds_t nfds UNNEEDED, int timeout UN
 /* Generated stub for fatal */
 void   fatal(const char *fmt UNNEEDED, ...)
 { fprintf(stderr, "fatal called!\n"); abort(); }
+/* Generated stub for free_htlcs */
+void free_htlcs(struct lightningd *ld UNNEEDED, const struct peer *peer UNNEEDED)
+{ fprintf(stderr, "free_htlcs called!\n"); abort(); }
 /* Generated stub for gossip_init */
 void gossip_init(struct lightningd *ld UNNEEDED)
 { fprintf(stderr, "gossip_init called!\n"); abort(); }