experimental: dual-funding (II of IV)

CHANGELOG.md

@@ -12,6 +12,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - JSON API: `fundchannel_start` now includes field `scriptpubkey`
 - JSON API: `txprepare` and `withdraw` now accept an optional parameter `utxos`, a list of utxos to include in the prepared transaction
 - JSON_API: `close` now accepts an optional parameter `destination`, to which the to-local output will be sent.
+- JSON API: `txprepare` includes a parameter `zero_out_change`, which if true leaves the change value as zero. Useful for designating change output for dual-funded transactions. Defaults to false.
+- JSON API: `fundchannel_start` now includes `open_channel_version`, a string which indicates
+the protocol version used to open the channel.
+- Plugin: `openchannel` hook includes fields for v2 channel establishment
 
 - bolt11: support for parsing feature bits (field `9`).
 

bitcoin/tx.c

@@ -14,6 +14,16 @@
 
 #define SEGREGATED_WITNESS_FLAG 0x1
 
+struct bitcoin_tx_output *new_tx_output(const tal_t *ctx,
+					struct amount_sat amount,
+					const u8 *script)
+{
+	struct bitcoin_tx_output *output = tal(ctx, struct bitcoin_tx_output);
+	output->amount = amount;
+	output->script = tal_dup_arr(output, u8, script, tal_count(script), 0);
+	return output;
+}
+
 int bitcoin_tx_add_output(struct bitcoin_tx *tx, const u8 *script,
 			  struct amount_sat amount)
 {

bitcoin/tx.h

@@ -39,10 +39,16 @@ struct bitcoin_tx_input {
 	u8 *script;
 	u32 sequence_number;
 
-	/* Only if BIP141 used. */
+	/* If BIP141 used, or is external input */
 	u8 **witness;
+
+	/* Needed for external inputs */
+	struct amount_sat amount;
 };
 
+struct bitcoin_tx_output *new_tx_output(const tal_t *ctx,
+					struct amount_sat amount,
+					const u8 *script);
 
 /* SHA256^2 the tx: simpler than sha256_tx */
 void bitcoin_txid(const struct bitcoin_tx *tx, struct bitcoin_txid *txid);

channeld/channel_wire.csv

@@ -22,7 +22,8 @@ msgdata,channel_init,remote_fundingkey,pubkey,
 msgdata,channel_init,remote_basepoints,basepoints,
 msgdata,channel_init,remote_per_commit,pubkey,
 msgdata,channel_init,old_remote_per_commit,pubkey,
-msgdata,channel_init,funder,enum side,
+msgdata,channel_init,opener,enum side,
+msgdata,channel_init,local_funded,bool,
 msgdata,channel_init,fee_base,u32,
 msgdata,channel_init,fee_proportional,u32,
 msgdata,channel_init,local_msatoshi,amount_msat,

channeld/channeld.c

@@ -669,10 +669,10 @@ static void handle_peer_feechange(struct peer *peer, const u8 *msg)
 	 *  - if the sender is not responsible for paying the Bitcoin fee:
 	 *    - MUST fail the channel.
 	 */
-	if (peer->channel->funder != REMOTE)
+	if (peer->channel->opener != REMOTE)
 		peer_failed(peer->pps,
 			    &peer->channel_id,
-			    "update_fee from non-funder?");
+			    "update_fee from non-opener?");
 
 	status_debug("update_fee %u, range %u-%u",
 		     feerate, peer->feerate_min, peer->feerate_max);
@@ -1128,7 +1128,7 @@ static void send_commit(struct peer *peer)
 	}
 
 	/* If we wanted to update fees, do it now. */
-	if (peer->channel->funder == LOCAL) {
+	if (peer->channel->opener == LOCAL) {
 		u32 feerate, max = approx_max_feerate(peer->channel);
 
 		feerate = peer->desired_feerate;
@@ -1386,11 +1386,11 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 	}
 
 	/* We were supposed to check this was affordable as we go. */
-	if (peer->channel->funder == REMOTE) {
+	if (peer->channel->opener == REMOTE) {
 		status_debug("Feerates are %u/%u",
 			     peer->channel->view[LOCAL].feerate_per_kw,
 			     peer->channel->view[REMOTE].feerate_per_kw);
-		assert(can_funder_afford_feerate(peer->channel,
+		assert(can_opener_afford_feerate(peer->channel,
 						 peer->channel->view[LOCAL]
 						 .feerate_per_kw));
 	}
@@ -1584,7 +1584,7 @@ static void handle_peer_revoke_and_ack(struct peer *peer, const u8 *msg)
 	peer->old_remote_per_commit = peer->remote_per_commit;
 	peer->remote_per_commit = next_per_commit;
 	status_debug("revoke_and_ack %s: remote_per_commit = %s, old_remote_per_commit = %s",
-		     side_to_str(peer->channel->funder),
+		     side_to_str(peer->channel->opener),
 		     type_to_string(tmpctx, struct pubkey,
 				    &peer->remote_per_commit),
 		     type_to_string(tmpctx, struct pubkey,
@@ -1863,6 +1863,14 @@ static void peer_in(struct peer *peer, const u8 *msg)
 	case WIRE_FUNDING_SIGNED:
 	case WIRE_CHANNEL_REESTABLISH:
 	case WIRE_CLOSING_SIGNED:
+#if EXPERIMENTAL_FEATURES
+	case WIRE_OPEN_CHANNEL2:
+	case WIRE_ACCEPT_CHANNEL2:
+	case WIRE_FUNDING_COMPOSE:
+	case WIRE_ACCEPTER_SIGS:
+	case WIRE_INIT_RBF:
+	case WIRE_ACK_RBF:
+#endif /* EXPERIMENTAL_FEATURES */
 		break;
 
 	/* These are all swallowed by handle_peer_gossip_or_error */
@@ -1992,7 +2000,7 @@ static void resend_commitment(struct peer *peer, const struct changed_htlc *last
 	}
 
 	/* Make sure they have the correct fee. */
-	if (peer->channel->funder == LOCAL) {
+	if (peer->channel->opener == LOCAL) {
 		msg = towire_update_fee(NULL, &peer->channel_id,
 					channel_feerate(peer->channel, REMOTE));
 		sync_crypto_write(peer->pps, take(msg));
@@ -2519,7 +2527,7 @@ static void peer_reconnect(struct peer *peer,
 	 * even tell by seeing if fees are different (short of saving full fee
 	 * state in database) since it could be a tiny feechange, or two
 	 * feechanges which cancelled out. */
-	if (peer->channel->funder == LOCAL)
+	if (peer->channel->opener == LOCAL)
 		peer->channel->changes_pending[LOCAL] = true;
 
 	peer_billboard(true, "Reconnected, and reestablished.");
@@ -2687,7 +2695,7 @@ static void handle_feerates(struct peer *peer, const u8 *inmsg)
 	 *    sufficient (by a significant margin) for timely processing of the
 	 *     commitment transaction.
 	 */
-	if (peer->channel->funder == LOCAL) {
+	if (peer->channel->opener == LOCAL) {
 		peer->desired_feerate = feerate;
 		start_commit_timer(peer);
 	} else {
@@ -2928,22 +2936,22 @@ static void init_channel(struct peer *peer)
 	struct pubkey funding_pubkey[NUM_SIDES];
 	struct channel_config conf[NUM_SIDES];
 	struct bitcoin_txid funding_txid;
-	enum side funder;
+	enum side opener;
 	enum htlc_state *hstates;
 	struct fulfilled_htlc *fulfilled;
 	enum side *fulfilled_sides;
 	struct failed_htlc **failed;
 	enum side *failed_sides;
 	struct added_htlc *htlcs;
 	bool reconnected;
-	u8 *funding_signed;
+	u8 *sigs_msg;
 	const u8 *msg;
 	u32 feerate_per_kw[NUM_SIDES];
 	u32 minimum_depth, failheight;
 	struct secret last_remote_per_commit_secret;
 	secp256k1_ecdsa_signature *remote_ann_node_sig;
 	secp256k1_ecdsa_signature *remote_ann_bitcoin_sig;
-	bool option_static_remotekey;
+	bool option_static_remotekey, local_funded;
 
 	assert(!(fcntl(MASTER_FD, F_GETFL) & O_NONBLOCK));
 
@@ -2964,7 +2972,8 @@ static void init_channel(struct peer *peer)
 				   &points[REMOTE],
 				   &peer->remote_per_commit,
 				   &peer->old_remote_per_commit,
-				   &funder,
+				   &opener,
+				   &local_funded,
 				   &peer->fee_base,
 				   &peer->fee_per_satoshi,
 				   &local_msat,
@@ -2995,7 +3004,7 @@ static void init_channel(struct peer *peer)
 				   &peer->shutdown_sent[REMOTE],
 				   &peer->final_scriptpubkey,
 				   &peer->channel_flags,
-				   &funding_signed,
+				   &sigs_msg,
 				   &peer->announce_depth_reached,
 				   &last_remote_per_commit_secret,
 				   &peer->localfeatures,
@@ -3015,7 +3024,7 @@ static void init_channel(struct peer *peer)
 		     " next_idx_remote = %"PRIu64
 		     " revocations_received = %"PRIu64
 		     " feerates %u/%u (range %u-%u)",
-		     side_to_str(funder),
+		     side_to_str(opener),
 		     type_to_string(tmpctx, struct pubkey,
 				    &peer->remote_per_commit),
 		     type_to_string(tmpctx, struct pubkey,
@@ -3063,7 +3072,8 @@ static void init_channel(struct peer *peer)
 					 &funding_pubkey[LOCAL],
 					 &funding_pubkey[REMOTE],
 					 option_static_remotekey,
-					 funder);
+					 local_funded,
+					 opener);
 
 	if (!channel_force_htlcs(peer->channel, htlcs, hstates,
 				 fulfilled, fulfilled_sides,
@@ -3091,7 +3101,7 @@ static void init_channel(struct peer *peer)
 					      &peer->node_ids[REMOTE]);
 
 	/* Default desired feerate is the feerate we set for them last. */
-	if (peer->channel->funder == LOCAL)
+	if (peer->channel->opener == LOCAL)
 		peer->desired_feerate = feerate_per_kw[REMOTE];
 
 	/* from now we need keep watch over WIRE_CHANNEL_FUNDING_DEPTH */
@@ -3101,9 +3111,9 @@ static void init_channel(struct peer *peer)
 	if (reconnected)
 		peer_reconnect(peer, &last_remote_per_commit_secret);
 
-	/* If we have a funding_signed message, send that immediately */
-	if (funding_signed)
-		sync_crypto_write(peer->pps, take(funding_signed));
+	/* If we have a final sigs message, send that immediately */
+	if (sigs_msg)
+		sync_crypto_write(peer->pps, take(sigs_msg));
 
 	/* Reenable channel */
 	channel_announcement_negotiate(peer);

channeld/commit_tx.c

@@ -80,7 +80,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 			     const struct bitcoin_txid *funding_txid,
 			     unsigned int funding_txout,
 			     struct amount_sat funding,
-			     enum side funder,
+			     enum side opener,
 			     u16 to_self_delay,
 			     const struct keyset *keyset,
 			     u32 feerate_per_kw,
@@ -126,7 +126,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 	 * 3. Subtract this base fee from the funder (either `to_local` or
 	 * `to_remote`), with a floor of 0 (see [Fee Payment](#fee-payment)).
 	 */
-	try_subtract_fee(funder, side, base_fee, &self_pay, &other_pay);
+	try_subtract_fee(opener, side, base_fee, &self_pay, &other_pay);
 
 #ifdef PRINT_ACTUAL_FEE
 	{

channeld/commit_tx.h

@@ -28,7 +28,7 @@ size_t commit_tx_num_untrimmed(const struct htlc **htlcs,
  * commit_tx: create (unsigned) commitment tx to spend the funding tx output
  * @ctx: context to allocate transaction and @htlc_map from.
  * @funding_txid, @funding_out, @funding: funding outpoint.
- * @funder: is the LOCAL or REMOTE paying the fee?
+ * @opener: is the LOCAL or REMOTE paying the fee?
  * @keyset: keys derived for this commit tx.
  * @feerate_per_kw: feerate to use
  * @dust_limit: dust limit below which to trim outputs.
@@ -48,7 +48,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 			     const struct bitcoin_txid *funding_txid,
 			     unsigned int funding_txout,
 			     struct amount_sat funding,
-			     enum side funder,
+			     enum side opener,
 			     u16 to_self_delay,
 			     const struct keyset *keyset,
 			     u32 feerate_per_kw,