gossipd: generalize query_short_channel_ids to use a callback.

We currently use a flag, but that's inflexible.

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

gossipd/gossipd.h

@@ -101,9 +101,9 @@ struct peer {
 	struct node_id *scid_query_nodes;
 	size_t scid_query_nodes_idx;
 
-	/* Do we have an scid_query outstanding?  Was it internal? */
+	/* Do we have an scid_query outstanding?  What to call when it's done? */
 	bool scid_query_outstanding;
-	bool scid_query_was_internal;
+	void (*scid_query_cb)(struct peer *peer, bool complete);
 
 	/* How many pongs are we expecting? */
 	size_t num_pings_outstanding;

gossipd/queries.c

@@ -146,7 +146,7 @@ static UNNEEDED bool encoding_end_external_type(u8 **encoded, u8 *type, size_t m
 static bool query_short_channel_ids(struct daemon *daemon,
 				    struct peer *peer,
 				    const struct short_channel_id *scids,
-				    bool internal)
+				    void (*cb)(struct peer *peer, bool complete))
 {
 	u8 *encoded, *msg;
 
@@ -189,7 +189,7 @@ static bool query_short_channel_ids(struct daemon *daemon,
 					     encoded, NULL);
 	queue_peer_msg(peer, take(msg));
 	peer->scid_query_outstanding = true;
-	peer->scid_query_was_internal = internal;
+	peer->scid_query_cb = cb;
 
 	status_debug("%s: sending query for %zu scids",
 		     type_to_string(tmpctx, struct node_id, &peer->id),
@@ -215,7 +215,7 @@ void query_unknown_channel(struct daemon *daemon,
 	tal_arr_expand(&daemon->unknown_scids, *id);
 
 	/* This is best effort: if peer is busy, we'll try next time. */
-	query_short_channel_ids(daemon, peer, daemon->unknown_scids, true);
+	query_short_channel_ids(daemon, peer, daemon->unknown_scids, NULL);
 }
 
 /* The peer can ask about an array of short channel ids: we don't assemble the
@@ -630,6 +630,10 @@ const u8 *handle_reply_channel_range(struct peer *peer, const u8 *msg)
 	struct short_channel_id *scids;
 	size_t n;
 	unsigned long b;
+	void (*cb)(struct peer *peer,
+		   u32 first_blocknum, u32 number_of_blocks,
+		   const struct short_channel_id *scids,
+		   bool complete);
 	struct tlv_reply_channel_range_tlvs *tlvs
 		= tlv_reply_channel_range_tlvs_new(tmpctx);
 
@@ -728,15 +732,16 @@ const u8 *handle_reply_channel_range(struct peer *peer, const u8 *msg)
 	if (peer->range_blocks_remaining)
 		return NULL;
 
-	peer->query_channel_range_cb(peer,
-				     first_blocknum,
-				     number_of_blocks,
-				     peer->query_channel_scids,
-				     complete);
+	/* Clear these immediately in case cb want to queue more */
+	scids = tal_steal(tmpctx, peer->query_channel_scids);
+	cb = peer->query_channel_range_cb;
+	tal_steal(tmpctx, peer->query_channel_blocks);
 
-	peer->query_channel_scids = tal_free(peer->query_channel_scids);
-	peer->query_channel_blocks = tal_free(peer->query_channel_blocks);
+	peer->query_channel_scids = NULL;
+	peer->query_channel_blocks = NULL;
 	peer->query_channel_range_cb = NULL;
+
+	cb(peer, first_blocknum, number_of_blocks, scids, complete);
 	return NULL;
 }
 
@@ -768,13 +773,8 @@ const u8 *handle_reply_short_channel_ids_end(struct peer *peer, const u8 *msg)
 	}
 
 	peer->scid_query_outstanding = false;
-
-	/* If it wasn't generated by us, it's the dev interface from lightningd
-	 */
-	if (!peer->scid_query_was_internal) {
-		msg = towire_gossip_scids_reply(msg, true, complete);
-		daemon_conn_send(peer->daemon->master, take(msg));
-	}
+	if (peer->scid_query_cb)
+		peer->scid_query_cb(peer, complete);
 
 	/* All good, no error. */
 	return NULL;
@@ -998,6 +998,12 @@ bool query_channel_range(struct daemon *daemon,
 }
 
 #if DEVELOPER
+static void query_scids_done(struct peer *peer, bool complete)
+{
+	const u8 *msg = towire_gossip_scids_reply(NULL, true, complete);
+	daemon_conn_send(peer->daemon->master, take(msg));
+}
+
 struct io_plan *query_scids_req(struct io_conn *conn,
 				struct daemon *daemon,
 				const u8 *msg)
@@ -1016,7 +1022,7 @@ struct io_plan *query_scids_req(struct io_conn *conn,
 		daemon_conn_send(daemon->master,
 				 take(towire_gossip_scids_reply(NULL,
 								false, false)));
-	} else if (!query_short_channel_ids(daemon, peer, scids, false))
+	} else if (!query_short_channel_ids(daemon, peer, scids, query_scids_done))
 		daemon_conn_send(daemon->master,
 				 take(towire_gossip_scids_reply(NULL,
 								false, false)));