channel: Wait for 6 confirmations before sending announcement sigs

The protocol specifies that in order for an announcement to be valid,
the channel has to have at least 6 confirmations.

lightningd/channel/channel.c

@@ -203,7 +203,6 @@ static struct io_plan *peer_in(struct io_conn *conn, struct peer *peer, u8 *msg)
 	return peer_read_message(conn, &peer->pcs, peer_in);
 }
 
-
 static struct io_plan *setup_peer_conn(struct io_conn *conn, struct peer *peer)
 {
 	return io_duplex(conn, peer_read_message(conn, &peer->pcs, peer_in),
@@ -273,13 +272,15 @@ static struct io_plan *req_in(struct io_conn *conn, struct daemon_conn *master)
 						&peer->next_per_commit[LOCAL]);
 		msg_enqueue(&peer->peer_out, take(msg));
 		peer->funding_locked[LOCAL] = true;
-		send_announcement_signatures(peer);
 
 		if (peer->funding_locked[REMOTE]) {
 			announce_channel(peer);
 			daemon_conn_send(master,
 				 take(towire_channel_normal_operation(peer)));
 		}
+	} else if(fromwire_channel_funding_announce_depth(master->msg_in, NULL)) {
+		status_trace("Exchanging announcement signatures.");
+		send_announcement_signatures(peer);
 	} else
 		status_failed(WIRE_CHANNEL_BAD_COMMAND, "%s", strerror(errno));
 

lightningd/channel/channel_wire.csv

@@ -41,3 +41,6 @@ channel_init,562,remote_node_id,struct pubkey
 # Tx is deep enough, go!
 channel_funding_locked,2
 channel_funding_locked,0,short_channel_id,struct short_channel_id
+
+# Tell the channel that we may announce the channel's existence
+channel_funding_announce_depth,3

lightningd/peer_control.c

@@ -65,6 +65,7 @@ static struct peer *new_peer(struct lightningd *ld,
 	peer->connect_cmd = cmd;
 	peer->funding_txid = NULL;
 	peer->seed = NULL;
+	peer->locked = false;
 
 	/* Max 128k per peer. */
 	peer->log_book = new_log_book(peer, 128*1024,
@@ -555,8 +556,19 @@ static enum watch_result funding_depth_cb(struct peer *peer,
 		return KEEP_WATCHING;
 	}
 
-	peer_set_condition(peer, "Funding tx reached depth %u", depth);
+	/* Make sure we notify `channeld` just once. */
-	subd_send_msg(peer->owner, take(towire_channel_funding_locked(peer, &scid)));
+	if (!peer->locked) {
+		peer_set_condition(peer, "Funding tx reached depth %u", depth);
+		subd_send_msg(peer->owner, take(towire_channel_funding_locked(peer, &scid)));
+		peer->locked = true;
+	}
+
+	/* With the above this is max(funding_depth, 6) before
+	 * announcing the channel */
+	if (depth < ANNOUNCE_MIN_DEPTH) {
+		return KEEP_WATCHING;
+	}
+	subd_send_msg(peer->owner, take(towire_channel_funding_announce_depth(peer)));
 	return DELETE_WATCH;
 }
 
@@ -626,6 +638,7 @@ static size_t update_channel_status(struct subd *sd,
 	/* And we never get these from channeld. */
 	case WIRE_CHANNEL_INIT:
 	case WIRE_CHANNEL_FUNDING_LOCKED:
+	case WIRE_CHANNEL_FUNDING_ANNOUNCE_DEPTH:
 		break;
 	}
 

lightningd/peer_control.h

@@ -6,6 +6,8 @@
 #include <lightningd/channel_config.h>
 #include <stdbool.h>
 
+#define ANNOUNCE_MIN_DEPTH 6
+
 struct crypto_state;
 
 struct peer {
@@ -52,6 +54,7 @@ struct peer {
 
 	/* Gossip client fd, forwarded to the respective owner */
 	int gossip_client_fd;
+	bool locked;
 };
 
 struct peer *peer_by_unique_id(struct lightningd *ld, u64 unique_id);