Channeld: init channel with remote announcement info when restart

1. Add remote_ann_node_sigs and remote_bitcoin_sigs fields in channel_init message;
2. Master add announcement signatures into channel_init message, and send this message to Channeld.
Channeld will initial the channel with this signatures when it reenables the channel.

CHANGELOG.md

@@ -18,6 +18,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Protocol: we now enforce `option_upfront_shutdown_script` if a peer negotiates it.
 - JSON API: `listforwards` now includes the local_failed forwards with failcode (Issue [#2435](https://github.com/ElementsProject/lightning/issues/2435), PR [#2524](https://github.com/ElementsProject/lightning/pull/2524))
 - Config: Added a default plugin directory : `lightning_dir/plugins`. Each plugin directory it contains will be added to lightningd on startup.
+- DB: Store the signatures of channel announcement sent from remote peer into DB, and init channel with signatures from DB directly when reenable the channel.
+(Issue [#2409](https://github.com/ElementsProject/lightning/issues/2409))
 
 ### Changed
 

channeld/channel_wire.csv

@@ -64,6 +64,8 @@ channel_init,,lflen,u16
 channel_init,,localfeatures,lflen*u8
 channel_init,,upfront_shutdown_script_len,u16
 channel_init,,upfront_shutdown_script,upfront_shutdown_script_len*u8
+channel_init,,remote_ann_node_sig,?secp256k1_ecdsa_signature
+channel_init,,remote_ann_bitcoin_sig,?secp256k1_ecdsa_signature
 
 # master->channeld funding hit new depth(funding locked if >= lock depth)
 channel_funding_depth,1002

channeld/channeld.c

@@ -2842,6 +2842,8 @@ static void init_channel(struct peer *peer)
 	u32 feerate_per_kw[NUM_SIDES];
 	u32 minimum_depth;
 	struct secret last_remote_per_commit_secret;
+	secp256k1_ecdsa_signature *remote_ann_node_sig;
+	secp256k1_ecdsa_signature *remote_ann_bitcoin_sig;
 
 	assert(!(fcntl(MASTER_FD, F_GETFL) & O_NONBLOCK));
 
@@ -2896,7 +2898,9 @@ static void init_channel(struct peer *peer)
 				   &peer->announce_depth_reached,
 				   &last_remote_per_commit_secret,
 				   &peer->localfeatures,
-				   &peer->remote_upfront_shutdown_script)) {
+				   &peer->remote_upfront_shutdown_script,
+				   &remote_ann_node_sig,
+				   &remote_ann_bitcoin_sig)) {
 					   master_badmsg(WIRE_CHANNEL_INIT, msg);
 	}
 
@@ -2915,6 +2919,18 @@ static void init_channel(struct peer *peer)
 		     feerate_per_kw[LOCAL], feerate_per_kw[REMOTE],
 		     peer->feerate_min, peer->feerate_max);
 
+	if(remote_ann_node_sig && remote_ann_bitcoin_sig) {
+		peer->announcement_node_sigs[REMOTE] = *remote_ann_node_sig;
+		peer->announcement_bitcoin_sigs[REMOTE] = *remote_ann_bitcoin_sig;
+		peer->have_sigs[REMOTE] = true;
+
+		/* Before we store announcement into DB, we have made sure
+		 * remote short_channel_id matched the local. Now we initial
+		 * it directly!
+		 */
+		peer->short_channel_ids[REMOTE] = peer->short_channel_ids[LOCAL];
+	}
+
 	/* First commit is used for opening: if we've sent 0, we're on
 	 * index 1. */
 	assert(peer->next_index[LOCAL] > 0);
@@ -2959,6 +2975,8 @@ static void init_channel(struct peer *peer)
 	tal_free(fulfilled_sides);
 	tal_free(failed);
 	tal_free(failed_sides);
+	tal_free(remote_ann_node_sig);
+	tal_free(remote_ann_bitcoin_sig);
 
 	peer->channel_direction = node_id_idx(&peer->node_ids[LOCAL],
 					      &peer->node_ids[REMOTE]);

lightningd/channel_control.c

@@ -297,6 +297,7 @@ void peer_start_channeld(struct channel *channel,
 	const struct config *cfg = &ld->config;
 	bool reached_announce_depth;
 	struct secret last_remote_per_commit_secret;
+	secp256k1_ecdsa_signature *remote_ann_node_sig, *remote_ann_bitcoin_sig;
 
 	hsmfd = hsm_get_client_fd(ld, &channel->peer->id,
 				  channel->dbid,
@@ -370,6 +371,13 @@ void peer_start_channeld(struct channel *channel,
 	if (ld->config.ignore_fee_limits)
 		log_debug(channel->log, "Ignoring fee limits!");
 
+	if(!wallet_remote_ann_sigs_load(tmpctx, channel->peer->ld->wallet, channel->dbid,
+				       &remote_ann_node_sig, &remote_ann_bitcoin_sig)) {
+		channel_internal_error(channel,
+				       "Could not load remote announcement signatures");
+		return;
+	}
+
 	initmsg = towire_channel_init(tmpctx,
 				      &get_chainparams(ld)->genesis_blockhash,
 				      &channel->funding_txid,
@@ -419,7 +427,9 @@ void peer_start_channeld(struct channel *channel,
 				      reached_announce_depth,
 				      &last_remote_per_commit_secret,
 				      channel->peer->localfeatures,
-				      channel->remote_upfront_shutdown_script);
+				      channel->remote_upfront_shutdown_script,
+				      remote_ann_node_sig,
+				      remote_ann_bitcoin_sig);
 
 	/* We don't expect a response: we are triggered by funding_depth_cb. */
 	subd_send_msg(channel->owner, take(initmsg));