gossipd: add flag for locally disabling channel.

We used to just manually set ROUTING_FLAGS_DISABLED, but that means we
then suppressed the real channel_update because we thought it was a
duplicate!

So use a local flag: set it for the channel when the peer disconnects,
and clear it when channeld sends a local update.

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

gossipd/gossip.c

@@ -1188,6 +1188,8 @@ static void handle_local_channel_update(struct peer *peer, const u8 *msg)
 		return;
 	}
 
+	/* channeld has reconnected, remove local disable. */
+	chan->local_disabled = false;
 	queue_local_update(peer->daemon, local_update);
 }
 
@@ -1398,6 +1400,7 @@ static void append_half_channel(struct gossip_getchannels_entry **entries,
 	e->destination = chan->nodes[!idx]->id;
 	e->satoshis = chan->satoshis;
 	e->flags = c->flags;
+	e->local_disabled = chan->local_disabled;
 	e->public = is_chan_public(chan);
 	e->short_channel_id = chan->scid;
 	e->last_update_timestamp = c->last_timestamp;
@@ -1823,9 +1826,9 @@ static void gossip_disable_outgoing_halfchan(struct daemon *daemon,
  *
  * Disables both directions of a local channel as a result of a close or lost
  * connection. A disabling `channel_update` will be queued for the outgoing
- * direction as well. We can't do that for the incoming direction, so we just
+ * direction as well, but that will be a little delayed.  We can't do that for
- * locally flip the flag, and the other endpoint should take care of publicly
+ * the incoming direction, so we set local_disabled and the other endpoint
- * disabling it with a `channel_update`.
+ * should take care of publicly disabling it with a `channel_update`.
  *
  * It is important to disable the incoming edge as well since we might otherwise
  * return that edge as a `contact_point` as part of an invoice.
@@ -1838,8 +1841,7 @@ static void gossip_disable_local_channel(struct daemon *daemon,
 	assert(pubkey_eq(&rstate->local_id, &chan->nodes[0]->id) ||
 	       pubkey_eq(&rstate->local_id, &chan->nodes[1]->id));
 
-	chan->half[0].flags |= ROUTING_FLAGS_DISABLED;
+	chan->local_disabled = true;
-	chan->half[1].flags |= ROUTING_FLAGS_DISABLED;
 	gossip_disable_outgoing_halfchan(daemon, chan);
 }
 

gossipd/routing.c

@@ -307,6 +307,7 @@ struct chan *new_chan(struct routing_state *rstate,
 	chan->channel_announce = NULL;
 	chan->channel_announcement_index = 0;
 	chan->satoshis = 0;
+	chan->local_disabled = false;
 
 	n = tal_count(n2->chans);
 	tal_resize(&n2->chans, n+1);
@@ -420,9 +421,11 @@ static void bfg_one_edge(struct node *node,
 }
 
 /* Determine if the given half_chan is routable */
-static bool hc_is_routable(const struct half_chan *hc, time_t now)
+static bool hc_is_routable(const struct chan *chan, int idx, time_t now)
 {
-	return is_halfchan_enabled(hc) && hc->unroutable_until < now;
+	return !chan->local_disabled
+		&& is_halfchan_enabled(&chan->half[idx])
+		&& chan->half[idx].unroutable_until < now;
 }
 
 /* riskfactor is already scaled to per-block amount */
@@ -491,7 +494,7 @@ find_route(const tal_t *ctx, struct routing_state *rstate,
 							    &n->id),
 					     i, num_edges);
 
-				if (!hc_is_routable(&chan->half[idx], now)) {
+				if (!hc_is_routable(chan, idx, now)) {
 					SUPERVERBOSE("...unroutable");
 					continue;
 				}

gossipd/routing.h

@@ -55,6 +55,9 @@ struct chan {
 	/* Index in broadcast map, if public (otherwise 0) */
 	u64 channel_announcement_index;
 
+	/* Disabled locally (due to peer disconnect) */
+	bool local_disabled;
+
 	u64 satoshis;
 };
 

lightningd/gossip_control.c

@@ -359,7 +359,8 @@ static void json_listchannels_reply(struct subd *gossip UNUSED, const u8 *reply,
 		json_add_u64(response, "satoshis", entries[i].satoshis);
 		json_add_num(response, "flags", entries[i].flags);
 		json_add_bool(response, "active",
-			      !(entries[i].flags & ROUTING_FLAGS_DISABLED));
+			      !(entries[i].flags & ROUTING_FLAGS_DISABLED)
+			      && !entries[i].local_disabled);
 		json_add_num(response, "last_update",
 			     entries[i].last_update_timestamp);
 		json_add_num(response, "base_fee_millisatoshi",

lightningd/gossip_msg.c

@@ -85,6 +85,7 @@ void fromwire_gossip_getchannels_entry(const u8 **pptr, size_t *max,
 	entry->satoshis = fromwire_u64(pptr, max);
 	entry->flags = fromwire_u16(pptr, max);
 	entry->public = fromwire_bool(pptr, max);
+	entry->local_disabled = fromwire_bool(pptr, max);
 	entry->last_update_timestamp = fromwire_u32(pptr, max);
 	entry->base_fee_msat = fromwire_u32(pptr, max);
 	entry->fee_per_millionth = fromwire_u32(pptr, max);
@@ -100,6 +101,7 @@ void towire_gossip_getchannels_entry(u8 **pptr,
 	towire_u64(pptr, entry->satoshis);
 	towire_u16(pptr, entry->flags);
 	towire_bool(pptr, entry->public);
+	towire_bool(pptr, entry->local_disabled);
 	towire_u32(pptr, entry->last_update_timestamp);
 	towire_u32(pptr, entry->base_fee_msat);
 	towire_u32(pptr, entry->fee_per_millionth);

lightningd/gossip_msg.h

@@ -24,6 +24,7 @@ struct gossip_getchannels_entry {
 	struct short_channel_id short_channel_id;
 	u16 flags;
 	bool public;
+	bool local_disabled;
 	u32 last_update_timestamp;
 	u32 delay;
 	u32 base_fee_msat;