connectd: send our own gossip, even if peer hasn't sent timestamp_filter.

We seem to have made node_announcement propagation *worse*, not
better.  Explorers don't see my nodes updates.

At least some LND nodes never send us timestamp_filter, so we are
never actually stream *any* gossip.  We should send gossip about
ourselves, even if they haven't set a filter (yet).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: Protocol: we more aggressively send our own gossip, to improve propagation chances.

connectd/multiplex.c

@@ -356,7 +356,27 @@ static u8 *maybe_from_gossip_store(const tal_t *ctx, struct peer *peer)
 {
 	u8 *msg;
 
-	/* Not streaming yet? */
+	/* dev-mode can suppress all gossip */
+	if (IFDEV(peer->daemon->dev_suppress_gossip, false))
+		return NULL;
+
+	/* BOLT #7:
+	 *   - if the `gossip_queries` feature is negotiated:
+	 *     - MUST NOT relay any gossip messages it did not generate itself,
+	 *       unless explicitly requested.
+	 */
+
+	/* So, even if they didn't send us a timestamp_filter message,
+	 * we *still* send our own gossip. */
+	if (!peer->gs.gossip_timer) {
+		return gossip_store_next(ctx, &peer->daemon->gossip_store_fd,
+					 0, 0xFFFFFFFF,
+					 true,
+					 &peer->gs.off,
+					 &peer->daemon->gossip_store_end);
+	}
+
+	/* Not streaming right now? */
 	if (!peer->gs.active)
 		return NULL;