Removing duplicated wscript generation for channel txs

channeld/channeld.c

@@ -810,14 +810,14 @@ static secp256k1_ecdsa_signature *calc_commitsigs(const tal_t *ctx,
 {
 	size_t i;
 	struct bitcoin_tx **txs;
-	const u8 **wscripts;
+	const u8 *funding_wscript;
 	const struct htlc **htlc_map;
 	struct pubkey local_htlckey;
 	const u8 *msg;
 	secp256k1_ecdsa_signature *htlc_sigs;
 
 	txs = channel_txs(tmpctx, &htlc_map,
-			  &wscripts, peer->channel, &peer->remote_per_commit,
+			  &funding_wscript, peer->channel, &peer->remote_per_commit,
 			  commit_index, REMOTE);
 
 	msg = towire_hsm_sign_remote_commitment_tx(NULL, txs[0],
@@ -838,7 +838,7 @@ static secp256k1_ecdsa_signature *calc_commitsigs(const tal_t *ctx,
 		     type_to_string(tmpctx, struct bitcoin_signature,
 				    commit_sig),
 		     type_to_string(tmpctx, struct bitcoin_tx, txs[0]),
-		     tal_hex(tmpctx, wscripts[0]),
+		     tal_hex(tmpctx, funding_wscript),
 		     type_to_string(tmpctx, struct pubkey,
 				    &peer->channel->funding_pubkey[LOCAL]));
 	dump_htlcs(peer->channel, "Sending commit_sig");
@@ -861,7 +861,7 @@ static secp256k1_ecdsa_signature *calc_commitsigs(const tal_t *ctx,
 	for (i = 0; i < tal_count(htlc_sigs); i++) {
 		struct bitcoin_signature sig;
 		msg = towire_hsm_sign_remote_htlc_tx(NULL, txs[i + 1],
-						     wscripts[i + 1],
+						     txs[i+1]->output_witscripts[0]->ptr,
 						     *txs[i+1]->input_amounts[0],
 						     &peer->remote_per_commit);
 
@@ -876,10 +876,11 @@ static secp256k1_ecdsa_signature *calc_commitsigs(const tal_t *ctx,
 			     type_to_string(tmpctx, struct bitcoin_signature,
 					    &sig),
 			     type_to_string(tmpctx, struct bitcoin_tx, txs[1+i]),
-			     tal_hex(tmpctx, wscripts[1+i]),
+			     tal_hex(tmpctx, txs[i+1]->output_witscripts[0]->ptr),
 			     type_to_string(tmpctx, struct pubkey,
 					    &local_htlckey));
-		assert(check_tx_sig(txs[1+i], 0, NULL, wscripts[1+i],
+		assert(check_tx_sig(txs[1+i], 0, NULL,
+				    txs[i+1]->output_witscripts[0]->ptr,
 				    &local_htlckey,
 				    &sig));
 	}
@@ -1201,7 +1202,7 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 	struct pubkey remote_htlckey;
 	struct bitcoin_tx **txs;
 	const struct htlc **htlc_map, **changed_htlcs;
-	const u8 **wscripts;
+	const u8 *funding_wscript;
 	size_t i;
 
 	changed_htlcs = tal_arr(msg, const struct htlc *, 0);
@@ -1241,7 +1242,7 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 
 	txs =
 	    channel_txs(tmpctx, &htlc_map,
-			&wscripts, peer->channel, &peer->next_local_per_commit,
+			&funding_wscript, peer->channel, &peer->next_local_per_commit,
 			peer->next_index[LOCAL], LOCAL);
 
 	if (!derive_simple_key(&peer->channel->basepoints[REMOTE].htlc,
@@ -1261,7 +1262,7 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 	 *    - if `signature` is not valid for its local commitment transaction:
 	 *      - MUST fail the channel.
 	 */
-	if (!check_tx_sig(txs[0], 0, NULL, wscripts[0],
+	if (!check_tx_sig(txs[0], 0, NULL, funding_wscript,
 			  &peer->channel->funding_pubkey[REMOTE], &commit_sig)) {
 		dump_htlcs(peer->channel, "receiving commit_sig");
 		peer_failed(peer->pps,
@@ -1271,7 +1272,7 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 			    type_to_string(msg, struct bitcoin_signature,
 					   &commit_sig),
 			    type_to_string(msg, struct bitcoin_tx, txs[0]),
-			    tal_hex(msg, wscripts[0]),
+			    tal_hex(msg, funding_wscript),
 			    type_to_string(msg, struct pubkey,
 					   &peer->channel->funding_pubkey
 					   [REMOTE]),
@@ -1305,14 +1306,14 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 		sig.s = htlc_sigs[i];
 		sig.sighash_type = SIGHASH_ALL;
 
-		if (!check_tx_sig(txs[1+i], 0, NULL, wscripts[1+i],
+		if (!check_tx_sig(txs[1+i], 0, NULL, txs[1+i]->output_witscripts[0]->ptr,
 				  &remote_htlckey, &sig))
 			peer_failed(peer->pps,
 				    &peer->channel_id,
 				    "Bad commit_sig signature %s for htlc %s wscript %s key %s",
 				    type_to_string(msg, struct bitcoin_signature, &sig),
 				    type_to_string(msg, struct bitcoin_tx, txs[1+i]),
-				    tal_hex(msg, wscripts[1+i]),
+				    tal_hex(msg, txs[1+i]->output_witscripts[0]->ptr),
 				    type_to_string(msg, struct pubkey,
 						   &remote_htlckey));
 	}

channeld/full_channel.c

@@ -222,7 +222,6 @@ static bool sum_offered_msatoshis(struct amount_msat *total,
 }
 
 static void add_htlcs(struct bitcoin_tx ***txs,
-		      const u8 ***wscripts,
 		      const struct htlc **htlcmap,
 		      const struct channel *channel,
 		      const struct keyset *keyset,
@@ -238,7 +237,7 @@ static void add_htlcs(struct bitcoin_tx ***txs,
 	for (i = 0; i < tal_count(htlcmap); i++) {
 		const struct htlc *htlc = htlcmap[i];
 		struct bitcoin_tx *tx;
-		u8 *wscript;
+		struct witscript *witscript;
 
 		if (!htlc)
 			continue;
@@ -250,29 +249,22 @@ static void add_htlcs(struct bitcoin_tx ***txs,
 					     channel->config[!side].to_self_delay,
 					     feerate_per_kw,
 					     keyset);
-			wscript	= bitcoin_wscript_htlc_offer(*wscripts,
-						     &keyset->self_htlc_key,
-						     &keyset->other_htlc_key,
-						     &htlc->rhash,
-						     &keyset->self_revocation_key);
 		} else {
 			tx = htlc_success_tx(*txs, chainparams, &txid, i,
 					     htlc->amount,
 					     channel->config[!side].to_self_delay,
 					     feerate_per_kw,
 					     keyset);
-			wscript	= bitcoin_wscript_htlc_receive(*wscripts,
-						       &htlc->expiry,
-						       &keyset->self_htlc_key,
-						       &keyset->other_htlc_key,
-						       &htlc->rhash,
-						       &keyset->self_revocation_key);
 		}
+		/* Re-use the previously-generated witness script */
+		witscript = (*txs)[0]->output_witscripts[i];
+		tx->output_witscripts[0] =
+		        tal(tx->output_witscripts, struct witscript);
+		tx->output_witscripts[0]->ptr =
+			tal_dup_arr(tx->output_witscripts[0], u8,
+				    witscript->ptr, tal_count(witscript->ptr), 0);
 
 		/* Append to array. */
-		assert(tal_count(*txs) == tal_count(*wscripts));
-
-		tal_arr_expand(wscripts, wscript);
 		tal_arr_expand(txs, tx);
 	}
 }
@@ -280,7 +272,7 @@ static void add_htlcs(struct bitcoin_tx ***txs,
 /* FIXME: We could cache these. */
 struct bitcoin_tx **channel_txs(const tal_t *ctx,
 				const struct htlc ***htlcmap,
-				const u8 ***wscripts,
+				const u8 **funding_wscript,
 				const struct channel *channel,
 				const struct pubkey *per_commitment_point,
 				u64 commitment_number,
@@ -310,12 +302,13 @@ struct bitcoin_tx **channel_txs(const tal_t *ctx,
 	    channel->view[side].owed[!side], committed, htlcmap,
 	    commitment_number ^ channel->commitment_number_obscurer, side);
 
-	*wscripts = tal_arr(ctx, const u8 *, 1);
+	/* Generating and saving witness script required to spend
-	(*wscripts)[0] = bitcoin_redeem_2of2(*wscripts,
+	 * the funding output */
+	*funding_wscript = bitcoin_redeem_2of2(*funding_wscript,
 					      &channel->funding_pubkey[side],
 					      &channel->funding_pubkey[!side]);
 
-	add_htlcs(&txs, wscripts, *htlcmap, channel, &keyset, side);
+	add_htlcs(&txs, *htlcmap, channel, &keyset, side);
 
 	tal_free(committed);
 	return txs;

channeld/full_channel.h

@@ -50,7 +50,7 @@ struct channel *new_full_channel(const tal_t *ctx,
  * @ctx: tal context to allocate return value from.
  * @channel: The channel to evaluate
  * @htlc_map: Pointer to htlcs for each tx output (allocated off @ctx).
- * @wscripts: Pointer to array of wscript for each tx returned (alloced off @ctx)
+ * @funding_wscript: Pointer to wscript for the funding tx output
  * @per_commitment_point: Per-commitment point to determine keys
  * @commitment_number: The index of this commitment.
  * @side: which side to get the commitment transaction for
@@ -61,7 +61,7 @@ struct channel *new_full_channel(const tal_t *ctx,
  */
 struct bitcoin_tx **channel_txs(const tal_t *ctx,
 				const struct htlc ***htlcmap,
-				const u8 ***wscripts,
+				const u8 **funding_wscript,
 				const struct channel *channel,
 				const struct pubkey *per_commitment_point,
 				u64 commitment_number,

channeld/test/run-full_channel.c

@@ -355,7 +355,7 @@ int main(void)
 	struct channel_config *local_config, *remote_config;
 	struct amount_msat to_local, to_remote;
 	const struct htlc **htlc_map, **htlcs;
-	const u8 *funding_wscript, **wscripts;
+	const u8 *funding_wscript, *funding_wscript_alt;
 	size_t i;
 
 	wally_init(0);
@@ -521,16 +521,15 @@ int main(void)
 			   NULL, &htlc_map, 0x2bb038521914 ^ 42, LOCAL);
 
 	txs = channel_txs(tmpctx,
-			  &htlc_map, &wscripts,
+			  &htlc_map, &funding_wscript_alt,
 			  lchannel, &local_per_commitment_point, 42, LOCAL);
 	assert(tal_count(txs) == 1);
 	assert(tal_count(htlc_map) == 2);
-	assert(tal_count(wscripts) == 1);
+	assert(scripteq(funding_wscript_alt, funding_wscript));
-	assert(scripteq(wscripts[0], funding_wscript));
 	tx_must_be_eq(txs[0], raw_tx);
 
 	txs2 = channel_txs(tmpctx,
-			   &htlc_map, &wscripts,
+			   &htlc_map, &funding_wscript,
 			   rchannel, &local_per_commitment_point, 42, REMOTE);
 	txs_must_be_eq(txs, txs2);
 
@@ -557,10 +556,10 @@ int main(void)
 	assert(lchannel->view[REMOTE].owed[REMOTE].millisatoshis
 	       == rchannel->view[LOCAL].owed[LOCAL].millisatoshis);
 
-	txs = channel_txs(tmpctx, &htlc_map, &wscripts,
+	txs = channel_txs(tmpctx, &htlc_map, &funding_wscript,
 			  lchannel, &local_per_commitment_point, 42, LOCAL);
 	assert(tal_count(txs) == 1);
-	txs2 = channel_txs(tmpctx, &htlc_map, &wscripts,
+	txs2 = channel_txs(tmpctx, &htlc_map, &funding_wscript,
 			   rchannel, &local_per_commitment_point, 42, REMOTE);
 	txs_must_be_eq(txs, txs2);
 
@@ -575,10 +574,10 @@ int main(void)
 	assert(lchannel->view[REMOTE].owed[REMOTE].millisatoshis
 	       == rchannel->view[LOCAL].owed[LOCAL].millisatoshis);
 
-	txs = channel_txs(tmpctx, &htlc_map, &wscripts,
+	txs = channel_txs(tmpctx, &htlc_map, &funding_wscript,
 			  lchannel, &local_per_commitment_point, 42, LOCAL);
 	assert(tal_count(txs) == 6);
-	txs2 = channel_txs(tmpctx, &htlc_map, &wscripts,
+	txs2 = channel_txs(tmpctx, &htlc_map, &funding_wscript,
 			   rchannel, &local_per_commitment_point, 42, REMOTE);
 	txs_must_be_eq(txs, txs2);
 
@@ -644,12 +643,12 @@ int main(void)
 		    to_local, to_remote, htlcs, &htlc_map, 0x2bb038521914 ^ 42,
 		    LOCAL);
 
-		txs = channel_txs(tmpctx, &htlc_map, &wscripts,
+		txs = channel_txs(tmpctx, &htlc_map, &funding_wscript,
 				  lchannel, &local_per_commitment_point, 42,
 				  LOCAL);
 		tx_must_be_eq(txs[0], raw_tx);
 
-		txs2 = channel_txs(tmpctx, &htlc_map, &wscripts,
+		txs2 = channel_txs(tmpctx, &htlc_map, &funding_wscript,
 				   rchannel, &local_per_commitment_point,
 				   42, REMOTE);
 		txs_must_be_eq(txs, txs2);

common/htlc_tx.c

@@ -65,6 +65,12 @@ static struct bitcoin_tx *htlc_tx(const tal_t *ctx,
 	bitcoin_tx_finalize(tx);
 	assert(bitcoin_tx_check(tx));
 
+	tx->output_witscripts[0] =
+			tal(tx->output_witscripts, struct witscript);
+	tx->output_witscripts[0]->ptr =
+			tal_dup_arr(tx->output_witscripts[0], u8,
+				    wscript, tal_count(wscript), 0);
+
 	tal_free(wscript);
 
 	return tx;

devtools/mkcommit.c

@@ -259,7 +259,7 @@ int main(int argc, char *argv[])
 	struct bitcoin_tx **local_txs, **remote_txs;
 	enum side fee_payer;
 	u8 **witness;
-	const u8 **wscripts;
+	const u8 *funding_wscript;
 	struct channel *channel;
 	struct existing_htlc **htlcs = tal_arr(NULL, struct existing_htlc *, 0);
 	const struct htlc **htlcmap;
@@ -393,15 +393,11 @@ int main(int argc, char *argv[])
 			 cast_const2(const struct existing_htlc **, htlcs)))
 		errx(1, "Cannot add HTLCs");
 
-	u8 *funding_wscript = bitcoin_redeem_2of2(NULL,
-						  &funding_localkey,
-						  &funding_remotekey);
-
 	/* Create the local commitment_tx */
 	if (!per_commit_point(&localseed, &local_per_commit_point, commitnum))
 		errx(1, "Bad deriving local per-commitment-point");
 
-	local_txs = channel_txs(NULL, &htlcmap, &wscripts, channel,
+	local_txs = channel_txs(NULL, &htlcmap, &funding_wscript, channel,
 				&local_per_commit_point, commitnum, LOCAL);
 
 	printf("## local_commitment\n"
@@ -477,14 +473,17 @@ int main(int argc, char *argv[])
 		local_txs[1+i]->input_amounts[0]
 			= tal_dup(local_txs[1+i], struct amount_sat, &amt);
 
-		printf("# wscript: %s\n", tal_hex(NULL, wscripts[1+i]));
+		printf("# wscript: %s\n", tal_hex(NULL, local_txs[1+i]->output_witscripts[1+i]->ptr));
 
-		bitcoin_tx_hash_for_sig(local_txs[1+i], 0, wscripts[1+i],
+		bitcoin_tx_hash_for_sig(local_txs[1+i], 0,
+					local_txs[1+i]->output_witscripts[1+i]->ptr,
 					SIGHASH_ALL, &hash);
-		sign_tx_input(local_txs[1+i], 0, NULL, wscripts[1+i],
+		sign_tx_input(local_txs[1+i], 0, NULL,
+			      local_txs[1+i]->output_witscripts[1+i]->ptr,
 			      &local_htlc_privkey, &local_htlc_pubkey,
 			      SIGHASH_ALL, &local_htlc_sig);
-		sign_tx_input(local_txs[1+i], 0, NULL, wscripts[1+i],
+		sign_tx_input(local_txs[1+i], 0, NULL,
+			      local_txs[1+i]->output_witscripts[1+i]->ptr,
 			      &remote_htlc_privkey, &remote_htlc_pubkey,
 			      SIGHASH_ALL, &remote_htlc_sig);
 		printf("localsig_on_local output %zu: %s\n",
@@ -496,13 +495,13 @@ int main(int argc, char *argv[])
 			witness = bitcoin_witness_htlc_timeout_tx(NULL,
 								  &local_htlc_sig,
 								  &remote_htlc_sig,
-								  wscripts[1+i]);
+								  local_txs[1+i]->output_witscripts[1+i]->ptr);
 		else
 			witness = bitcoin_witness_htlc_success_tx(NULL,
 								  &local_htlc_sig,
 								  &remote_htlc_sig,
 								  preimage_of(&htlcmap[i]->rhash, cast_const2(const struct existing_htlc **, htlcs)),
-								  wscripts[1+i]);
+								  local_txs[1+i]->output_witscripts[1+i]->ptr);
 		bitcoin_tx_input_set_witness(local_txs[1+i], 0, witness);
 		printf("htlc tx for output %zu: %s\n",
 		       i, tal_hex(NULL, linearize_tx(NULL, local_txs[1+i])));
@@ -512,7 +511,7 @@ int main(int argc, char *argv[])
 	/* Create the remote commitment tx */
 	if (!per_commit_point(&remoteseed, &remote_per_commit_point, commitnum))
 		errx(1, "Bad deriving remote per-commitment-point");
-	remote_txs = channel_txs(NULL, &htlcmap, &wscripts, channel,
+	remote_txs = channel_txs(NULL, &htlcmap, &funding_wscript, channel,
 				 &remote_per_commit_point, commitnum, REMOTE);
 	remote_txs[0]->input_amounts[0]
 		= tal_dup(remote_txs[0], struct amount_sat, &funding_amount);
@@ -589,13 +588,16 @@ int main(int argc, char *argv[])
 		remote_txs[1+i]->input_amounts[0]
 			= tal_dup(remote_txs[1+i], struct amount_sat, &amt);
 
-		printf("# wscript: %s\n", tal_hex(NULL, wscripts[1+i]));
+		printf("# wscript: %s\n", tal_hex(NULL, remote_txs[1+i]->output_witscripts[1+i]->ptr));
-		bitcoin_tx_hash_for_sig(remote_txs[1+i], 0, wscripts[1+i],
+		bitcoin_tx_hash_for_sig(remote_txs[1+i], 0,
+					remote_txs[1+i]->output_witscripts[1+i]->ptr,
 					SIGHASH_ALL, &hash);
-		sign_tx_input(remote_txs[1+i], 0, NULL, wscripts[1+i],
+		sign_tx_input(remote_txs[1+i], 0, NULL,
+			      remote_txs[1+i]->output_witscripts[1+i]->ptr,
 			      &local_htlc_privkey, &local_htlc_pubkey,
 			      SIGHASH_ALL, &local_htlc_sig);
-		sign_tx_input(remote_txs[1+i], 0, NULL, wscripts[1+i],
+		sign_tx_input(remote_txs[1+i], 0, NULL,
+			      remote_txs[1+i]->output_witscripts[1+i]->ptr,
 			      &remote_htlc_privkey, &remote_htlc_pubkey,
 			      SIGHASH_ALL, &remote_htlc_sig);
 		printf("localsig_on_remote output %zu: %s\n",
@@ -607,13 +609,13 @@ int main(int argc, char *argv[])
 			witness = bitcoin_witness_htlc_timeout_tx(NULL,
 								  &remote_htlc_sig,
 								  &local_htlc_sig,
-								  wscripts[1+i]);
+								  remote_txs[1+i]->output_witscripts[1+i]->ptr);
 		else
 			witness = bitcoin_witness_htlc_success_tx(NULL,
 								  &remote_htlc_sig,
 								  &local_htlc_sig,
 								  preimage_of(&htlcmap[i]->rhash, cast_const2(const struct existing_htlc **, htlcs)),
-								  wscripts[1+i]);
+								  remote_txs[1+i]->output_witscripts[1+i]->ptr);
 		bitcoin_tx_input_set_witness(remote_txs[1+i], 0, witness);
 		printf("htlc tx for output %zu: %s\n",
 		       i, tal_hex(NULL, linearize_tx(NULL, remote_txs[1+i])));