channeld: Collect signatures before sending announcements

We now have two partially overlapping state-machines: the channel
state and the announcement state. We need to request signatures from
the HSM to exchange them with the peer, and we need to have both sets
of signatures before we can proceed and send the actual announcements.

lightningd/channel/channel.c

@@ -91,6 +91,7 @@ struct peer {
 	struct short_channel_id short_channel_ids[NUM_SIDES];
 	secp256k1_ecdsa_signature announcement_node_sigs[NUM_SIDES];
 	secp256k1_ecdsa_signature announcement_bitcoin_sigs[NUM_SIDES];
+	bool have_sigs[NUM_SIDES];
 
 	/* Which direction of the channel do we control? */
 	u16 channel_direction;
@@ -150,6 +151,8 @@ static void send_announcement_signatures(struct peer *peer)
 	sign_hash(&peer->our_secrets.funding_privkey, &hash,
 		  &peer->announcement_bitcoin_sigs[LOCAL]);
 
+	peer->have_sigs[LOCAL] = true;
+
 	msg = towire_announcement_signatures(
 	    tmpctx, &peer->channel_id, &peer->short_channel_ids[LOCAL],
 	    &peer->announcement_node_sigs[LOCAL],
@@ -285,7 +288,10 @@ static void handle_peer_announcement_signatures(struct peer *peer, const u8 *msg
 					 sizeof(struct short_channel_id)));
 	}
 
-	if (peer->funding_locked[LOCAL]) {
+	peer->have_sigs[REMOTE] = true;
+
+	/* We have the remote sigs, do we have the local ones as well? */
+	if (peer->funding_locked[LOCAL] && peer->have_sigs[LOCAL]) {
 		send_channel_announcement(peer);
 		send_channel_update(peer, false);
 	}
@@ -979,8 +985,6 @@ static void handle_funding_locked(struct peer *peer, const u8 *msg)
 	peer->funding_locked[LOCAL] = true;
 
 	if (peer->funding_locked[REMOTE]) {
-		send_channel_announcement(peer);
-		send_channel_update(peer, false);
 		daemon_conn_send(&peer->master,
 				 take(towire_channel_normal_operation(peer)));
 	}
@@ -990,6 +994,13 @@ static void handle_funding_announce_depth(struct peer *peer, const u8 *msg)
 {
 	status_trace("Exchanging announcement signatures.");
 	send_announcement_signatures(peer);
+
+	/* Only send the announcement and update if the other end gave
+	 * us its sig */
+	if (peer->have_sigs[REMOTE]) {
+		send_channel_announcement(peer);
+		send_channel_update(peer, false);
+	}
 }
 
 static void handle_offer_htlc(struct peer *peer, const u8 *inmsg)
@@ -1205,6 +1216,7 @@ int main(int argc, char *argv[])
 	timers_init(&peer->timers, time_mono());
 	peer->commit_timer = NULL;
 	peer->commit_index[LOCAL] = peer->commit_index[REMOTE] = 0;
+	peer->have_sigs[LOCAL] = peer->have_sigs[REMOTE] = false;
 	shachain_init(&peer->their_shachain);
 
 	status_setup_async(&peer->master);