chaintopology: free outstanding requests so we don't get responses wh…

…ile shutting down.

I've never seen this, but the race looks possible so we should close it.

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

lightningd/chaintopology.c

@@ -565,7 +565,7 @@ static void start_fee_estimate(struct chain_topology *topo)
 {
 	topo->updatefee_timer = NULL;
 	/* Based on timer, update fee estimates. */
-	bitcoind_estimate_fees(topo, topo->bitcoind, update_feerates_repeat, NULL);
+	bitcoind_estimate_fees(topo->request_ctx, topo->bitcoind, update_feerates_repeat, NULL);
 }
 
 struct rate_conversion {
@@ -1076,7 +1076,7 @@ static void try_extend_tip(struct chain_topology *topo)
 {
 	topo->extend_timer = NULL;
 	trace_span_start("extend_tip", topo);
-	bitcoind_getrawblockbyheight(topo, topo->bitcoind, topo->tip->height + 1,
+	bitcoind_getrawblockbyheight(topo->request_ctx, topo->bitcoind, topo->tip->height + 1,
 				     get_new_block, topo);
 }
 
@@ -1218,6 +1218,7 @@ struct chain_topology *new_topology(struct lightningd *ld, struct logger *log)
 	topo->extend_timer = NULL;
 	topo->rebroadcast_timer = NULL;
 	topo->checkchain_timer = NULL;
+	topo->request_ctx = tal(topo, char);
 	list_head_init(topo->sync_waiters);
 
 	return topo;
@@ -1276,7 +1277,7 @@ static void retry_sync_getchaininfo_done(struct bitcoind *bitcoind, const char *
 static void retry_sync(struct chain_topology *topo)
 {
 	topo->checkchain_timer = NULL;
-	bitcoind_getchaininfo(topo, topo->bitcoind, get_block_height(topo),
+	bitcoind_getchaininfo(topo->request_ctx, topo->bitcoind, get_block_height(topo),
 			      retry_sync_getchaininfo_done, topo);
 }
 
@@ -1499,4 +1500,7 @@ void stop_topology(struct chain_topology *topo)
 	tal_free(topo->checkchain_timer);
 	tal_free(topo->extend_timer);
 	tal_free(topo->updatefee_timer);
+
+	/* Don't handle responses to any existing requests. */
+	tal_free(topo->request_ctx);
 }

lightningd/chaintopology.h

@@ -130,6 +130,9 @@ struct chain_topology {
 	/* Timers we're running. */
 	struct oneshot *checkchain_timer, *extend_timer, *updatefee_timer, *rebroadcast_timer;
 
+	/* Parent context for requests (to bcli plugin) we have outstanding. */
+	tal_t *request_ctx;
+
 	/* Bitcoin transactions we're broadcasting */
 	struct outgoing_tx_map *outgoing_txs;