Added destination wallet keypath to justice sweeps.

Author: ksedgwic

channeld/channeld.c

@@ -42,6 +42,7 @@
 #include <gossipd/gossip_store_wiregen.h>
 #include <gossipd/gossipd_peerd_wiregen.h>
 #include <hsmd/hsmd_wiregen.h>
+#include <wally_bip32.h>
 #include <wire/common_wiregen.h>
 #include <wire/peer_wire.h>
 #include <wire/wire_sync.h>
@@ -138,6 +139,8 @@ struct peer {
 	u32 fee_per_satoshi;
 
 	/* The scriptpubkey to use for shutting down. */
+	u32 final_index;
+	struct ext_key final_ext_key;
 	u8 *final_scriptpubkey;
 
 	/* If master told us to shut down */
@@ -1845,6 +1848,7 @@ static u8 *got_revoke_msg(struct peer *peer, u64 revoke_num,
 	if (pbase) {
 		ptx = penalty_tx_create(
 		    NULL, peer->channel, peer->feerate_penalty,
+		    peer->final_index, &peer->final_ext_key,
 		    peer->final_scriptpubkey, per_commitment_secret,
 		    &pbase->txid, pbase->outnum, pbase->amount,
 		    HSM_FD);
@@ -3653,7 +3657,10 @@ static void handle_shutdown_cmd(struct peer *peer, const u8 *inmsg)
 {
 	u8 *local_shutdown_script;
 
-	if (!fromwire_channeld_send_shutdown(peer, inmsg, &local_shutdown_script,
+	if (!fromwire_channeld_send_shutdown(peer, inmsg,
+					     &peer->final_index,
+					     &peer->final_ext_key,
+					     &local_shutdown_script,
 					     &peer->shutdown_wrong_funding))
 		master_badmsg(WIRE_CHANNELD_SEND_SHUTDOWN, inmsg);
 
@@ -3957,6 +3964,8 @@ static void init_channel(struct peer *peer)
 				   &reconnected,
 				   &peer->send_shutdown,
 				   &peer->shutdown_sent[REMOTE],
+				   &peer->final_index,
+				   &peer->final_ext_key,
 				   &peer->final_scriptpubkey,
 				   &peer->channel_flags,
 				   &fwd_msg,

channeld/channeld_wire.csv

@@ -1,5 +1,6 @@
 #include <bitcoin/psbt.h>
 #include <bitcoin/tx.h>
+#include <common/bip32.h>
 #include <common/blockheight_states.h>
 #include <common/cryptomsg.h>
 #include <common/channel_config.h>
@@ -58,6 +59,8 @@ msgdata,channeld_init,funding_short_id,short_channel_id,
 msgdata,channeld_init,reestablish,bool,
 msgdata,channeld_init,send_shutdown,bool,
 msgdata,channeld_init,remote_shutdown_received,bool,
+msgdata,channeld_init,final_index,u32,
+msgdata,channeld_init,final_ext_key,ext_key,
 msgdata,channeld_init,final_scriptpubkey_len,u16,
 msgdata,channeld_init,final_scriptpubkey,u8,final_scriptpubkey_len
 msgdata,channeld_init,flags,u8,
@@ -174,6 +177,8 @@ msgtype,channeld_got_revoke_reply,1122
 
 # Tell peer to shut down channel.
 msgtype,channeld_send_shutdown,1023
+msgdata,channeld_send_shutdown,final_index,u32,
+msgdata,channeld_send_shutdown,final_ext_key,ext_key,
 msgdata,channeld_send_shutdown,shutdown_len,u16,
 msgdata,channeld_send_shutdown,shutdown_scriptpubkey,u8,shutdown_len
 msgdata,channeld_send_shutdown,wrong_funding,?bitcoin_outpoint,

channeld/watchtower.c

@@ -12,10 +12,41 @@
 
 static const u8 ONE = 0x1;
 
+static void add_keypath_item_to_last_output(struct bitcoin_tx *tx,
+					    u32 index,
+					    const struct ext_key *ext) {
+	// Skip if there is no wallet keypath for this output.
+	if (index == UINT32_MAX)
+		return;
+
+	size_t outndx = tx->psbt->num_outputs - 1;
+	struct wally_map *map_in = &tx->psbt->outputs[outndx].keypaths;
+
+	u8 fingerprint[BIP32_KEY_FINGERPRINT_LEN];
+	if (bip32_key_get_fingerprint(
+		    (struct ext_key *) ext, fingerprint, sizeof(fingerprint)) != WALLY_OK) {
+		abort();
+	}
+
+	u32 path[1];
+	path[0] = index;
+
+	tal_wally_start();
+	if (wally_map_add_keypath_item(map_in,
+				       ext->pub_key, sizeof(ext->pub_key),
+				       fingerprint, sizeof(fingerprint),
+				       path, 1) != WALLY_OK) {
+		abort();
+	}
+	tal_wally_end(tx->psbt);
+}
+
 const struct bitcoin_tx *
 penalty_tx_create(const tal_t *ctx,
 		  const struct channel *channel,
 		  u32 penalty_feerate,
+		  u32 final_index,
+		  struct ext_key *final_ext_key,
 		  u8 *final_scriptpubkey,
 		  const struct secret *revocation_preimage,
 		  const struct bitcoin_txid *commitment_txid,
@@ -75,6 +106,7 @@ penalty_tx_create(const tal_t *ctx,
 			     NULL, to_them_sats, NULL, wscript);
 
 	bitcoin_tx_add_output(tx, final_scriptpubkey, NULL, to_them_sats);
+	add_keypath_item_to_last_output(tx, final_index, final_ext_key);
 
 	/* Worst-case sig is 73 bytes */
 	weight = bitcoin_tx_weight(tx) + 1 + 3 + 73 + 0 + tal_count(wscript);

channeld/watchtower.h

@@ -3,10 +3,14 @@
 #include "config.h"
 #include <common/initial_channel.h>
 
+struct ext_key;
+
 const struct bitcoin_tx *
 penalty_tx_create(const tal_t *ctx,
 		  const struct channel *channel,
 		  u32 penalty_feerate,
+		  u32 final_index,
+		  struct ext_key *final_ext_key,
 		  u8 *final_scriptpubkey,
 		  const struct secret *revocation_preimage,
 		  const struct bitcoin_txid *commitment_txid,

lightningd/channel_control.c

@@ -21,6 +21,7 @@
 #include <lightningd/notification.h>
 #include <lightningd/peer_control.h>
 #include <lightningd/ping.h>
+#include <wally_bip32.h>
 #include <wire/common_wiregen.h>
 
 static void update_feerates(struct lightningd *ld, struct channel *channel)
@@ -645,6 +646,18 @@ void peer_start_channeld(struct channel *channel,
 	pbases = wallet_penalty_base_load_for_channel(
 	    tmpctx, channel->peer->ld->wallet, channel->dbid);
 
+	struct ext_key final_ext_key;
+	if (bip32_key_from_parent(
+		    ld->wallet->bip32_base,
+		    channel->final_key_idx,
+		    BIP32_FLAG_KEY_PUBLIC,
+		    &final_ext_key) != WALLY_OK) {
+		channel_internal_error(channel,
+				       "Could not derive onchain ext key %"PRIu64,
+				       channel->final_key_idx);
+		return;
+	}
+
 	initmsg = towire_channeld_init(tmpctx,
 				      chainparams,
  				      ld->our_features,
@@ -694,6 +707,8 @@ void peer_start_channeld(struct channel *channel,
 				       || channel->state == CLOSINGD_SIGEXCHANGE
 				       || channel_closed(channel),
 				      channel->shutdown_scriptpubkey[REMOTE] != NULL,
+				      channel->final_key_idx,
+				      &final_ext_key,
 				      channel->shutdown_scriptpubkey[LOCAL],
 				      channel->channel_flags,
 				      fwd_msg,

lightningd/closing_control.c

@@ -776,11 +776,24 @@ static struct command_result *json_close(struct command *cmd,
 					msg = towire_dualopend_send_shutdown(
 						NULL,
 						channel->shutdown_scriptpubkey[LOCAL]);
-				} else
+				} else {
+					struct ext_key final_ext_key;
+					if (bip32_key_from_parent(
+						    channel->peer->ld->wallet->bip32_base,
+						    channel->final_key_idx,
+						    BIP32_FLAG_KEY_PUBLIC,
+						    &final_ext_key) != WALLY_OK) {
+						return command_fail(
+							cmd, LIGHTNINGD,
+							"Could not derive onchain ext key");
+					}
 					msg = towire_channeld_send_shutdown(
 						NULL,
+						channel->final_key_idx,
+						&final_ext_key,
 						channel->shutdown_scriptpubkey[LOCAL],
 						channel->shutdown_wrong_funding);
+				}
 				subd_send_msg(channel->owner, take(msg));
 			}
 

lightningd/peer_control.c

@@ -178,15 +178,9 @@ u8 *p2wpkh_for_keyidx(const tal_t *ctx, struct lightningd *ld, u64 keyidx)
 
 static struct simple_htlc **collect_htlcs(struct channel *channel, u32 local_feerate) {
 	// Collect the htlcs for call to hsmd.
-	//
-	// We use the existing_htlc to_wire routines, it's unfortunate that
-	// we have to send a dummy onion_routing_packet ...
-	//
 	struct htlc_in_map *htlcs_in = &channel->peer->ld->htlcs_in;
 	struct htlc_out_map *htlcs_out = &channel->peer->ld->htlcs_out;
 	struct simple_htlc **htlcs = tal_arr(tmpctx, struct simple_htlc *, 0);
-	u8 dummy_onion_routing_packet[TOTAL_PACKET_SIZE(ROUTING_INFO_SIZE)];
-	memset(dummy_onion_routing_packet, 0, sizeof(dummy_onion_routing_packet));
 
 	const struct htlc_in *hin;
 	struct htlc_in_map_iter ini;