PSBTs, Meet the HSM

bitcoin/psbt.c

@@ -5,7 +5,9 @@
 #include <bitcoin/signature.h>
 #include <ccan/cast/cast.h>
 #include <ccan/ccan/array_size/array_size.h>
+#include <ccan/tal/str/str.h>
 #include <common/amount.h>
+#include <common/type_to_string.h>
 #include <common/utils.h>
 #include <string.h>
 #include <wally_psbt.h>
@@ -114,10 +116,32 @@ struct wally_psbt_input *psbt_add_input(struct wally_psbt *psbt,
 {
 	struct wally_tx *tx;
 	struct wally_tx_input tmp_in;
+	u8 *script;
+	size_t scriptlen = 0;
+	struct wally_tx_witness_stack *witness = NULL;
 
 	tx = psbt->tx;
 	assert(insert_at <= tx->num_inputs);
+
+	/* Remove any script sig or witness info before adding it ! */
+	if (input->script_len > 0) {
+		scriptlen = input->script_len;
+		input->script_len = 0;
+		script = (u8 *)input->script;
+		input->script = NULL;
+	}
+	if (input->witness) {
+		witness = input->witness;
+		input->witness = NULL;
+	}
 	wally_tx_add_input(tx, input);
+	/* Put the script + witness info back */
+	if (scriptlen > 0) {
+		input->script_len = scriptlen;
+		input->script = script;
+	}
+	if (witness)
+		input->witness = witness;
 
 	tmp_in = tx->inputs[tx->num_inputs - 1];
 	MAKE_ROOM(tx->inputs, insert_at, tx->num_inputs);
@@ -219,29 +243,24 @@ void psbt_input_add_pubkey(struct wally_psbt *psbt, size_t in,
 	assert(wally_err == WALLY_OK);
 }
 
-void psbt_input_set_partial_sig(struct wally_psbt *psbt, size_t in,
+bool psbt_input_set_partial_sig(struct wally_psbt *psbt, size_t in,
 				const struct pubkey *pubkey,
 				const struct bitcoin_signature *sig)
 {
-	int wally_err;
 	u8 pk_der[PUBKEY_CMPR_LEN];
 
 	assert(in < psbt->num_inputs);
 	if (!psbt->inputs[in].partial_sigs)
 		if (wally_partial_sigs_map_init_alloc(1, &psbt->inputs[in].partial_sigs) != WALLY_OK)
-			abort();
+			return false;
 
 	/* we serialize the compressed version of the key, wally likes this */
 	pubkey_to_der(pk_der, pubkey);
-	wally_err = wally_add_new_partial_sig(psbt->inputs[in].partial_sigs,
-					      pk_der, sizeof(pk_der),
-					      cast_const(unsigned char *, sig->s.data),
-					      sizeof(sig->s.data));
-	assert(wally_err == WALLY_OK);
-
-	wally_err = wally_psbt_input_set_sighash_type(&psbt->inputs[in],
-						      sig->sighash_type);
-	assert(wally_err == WALLY_OK);
+	wally_psbt_input_set_sighash_type(&psbt->inputs[in], sig->sighash_type);
+	return wally_add_new_partial_sig(psbt->inputs[in].partial_sigs,
+					 pk_der, sizeof(pk_der),
+					 cast_const(unsigned char *, sig->s.data),
+					 sizeof(sig->s.data)) == WALLY_OK;
 }
 
 void psbt_input_set_prev_utxo(struct wally_psbt *psbt, size_t in,
@@ -293,6 +312,17 @@ void psbt_input_set_prev_utxo_wscript(struct wally_psbt *psbt, size_t in,
 	psbt_input_set_prev_utxo(psbt, in, scriptPubkey, amt);
 }
 
+bool psbt_input_set_redeemscript(struct wally_psbt *psbt, size_t in,
+				 const u8 *redeemscript)
+{
+	int wally_err;
+	assert(psbt->num_inputs > in);
+	wally_err = wally_psbt_input_set_redeem_script(&psbt->inputs[in],
+						       cast_const(u8 *, redeemscript),
+						       tal_bytelen(redeemscript));
+	return wally_err == WALLY_OK;
+}
+
 struct amount_sat psbt_input_get_amount(struct wally_psbt *psbt,
 					size_t in)
 {
@@ -310,6 +340,60 @@ struct amount_sat psbt_input_get_amount(struct wally_psbt *psbt,
 	return val;
 }
 
+struct wally_tx *psbt_finalize(struct wally_psbt *psbt, bool finalize_in_place)
+{
+	struct wally_psbt *tmppsbt;
+	struct wally_tx *wtx;
+
+	/* We want the 'finalized' tx since that includes any signature
+	 * data, not the global tx. But 'finalizing' a tx destroys some fields
+	 * so we 'clone' it first and then finalize it */
+	if (!finalize_in_place) {
+		if (wally_psbt_clone(psbt, &tmppsbt) != WALLY_OK)
+			return NULL;
+	} else
+		tmppsbt = cast_const(struct wally_psbt *, psbt);
+
+	if (wally_finalize_psbt(tmppsbt) != WALLY_OK) {
+		if (!finalize_in_place)
+			wally_psbt_free(tmppsbt);
+		return NULL;
+	}
+
+	if (psbt_is_finalized(tmppsbt)
+		&& wally_extract_psbt(tmppsbt, &wtx) == WALLY_OK) {
+		if (!finalize_in_place)
+			wally_psbt_free(tmppsbt);
+		return wtx;
+	}
+
+	if (!finalize_in_place)
+		wally_psbt_free(tmppsbt);
+	return NULL;
+}
+
+bool psbt_from_b64(const char *b64str, struct wally_psbt **psbt)
+{
+	int wally_err;
+	wally_err = wally_psbt_from_base64(b64str, psbt);
+	return wally_err == WALLY_OK;
+}
+
+char *psbt_to_b64(const tal_t *ctx, const struct wally_psbt *psbt)
+{
+	char *serialized_psbt, *ret_val;
+	int ret;
+
+	ret = wally_psbt_to_base64(cast_const(struct wally_psbt *, psbt),
+				   &serialized_psbt);
+	assert(ret == WALLY_OK);
+
+	ret_val = tal_strdup(ctx, serialized_psbt);
+	wally_free_string(serialized_psbt);
+	return ret_val;
+}
+REGISTER_TYPE_TO_STRING(wally_psbt, psbt_to_b64);
+
 const u8 *psbt_get_bytes(const tal_t *ctx, const struct wally_psbt *psbt,
 			 size_t *bytes_written)
 {
@@ -340,7 +424,7 @@ struct wally_psbt *psbt_from_bytes(const tal_t *ctx, const u8 *bytes,
 	return psbt;
 }
 
-void towire_psbt(u8 **pptr, const struct wally_psbt *psbt)
+void towire_wally_psbt(u8 **pptr, const struct wally_psbt *psbt)
 {
 	/* Let's include the PSBT bytes */
 	size_t bytes_written;
@@ -350,8 +434,8 @@ void towire_psbt(u8 **pptr, const struct wally_psbt *psbt)
 	tal_free(pbt_bytes);
 }
 
-struct wally_psbt *fromwire_psbt(const tal_t *ctx,
-				 const u8 **cursor, size_t *max)
+struct wally_psbt *fromwire_wally_psbt(const tal_t *ctx,
+				       const u8 **cursor, size_t *max)
 {
 	struct wally_psbt *psbt;
 	u32 psbt_byte_len;

bitcoin/psbt.h

@@ -32,6 +32,8 @@ struct wally_psbt *new_psbt(const tal_t *ctx,
  */
 bool psbt_is_finalized(struct wally_psbt *psbt);
 
+struct wally_tx *psbt_finalize(struct wally_psbt *psbt, bool finalize_in_place);
+
 struct wally_psbt_input *psbt_add_input(struct wally_psbt *psbt,
 					struct wally_tx_input *input,
 					size_t insert_at);
@@ -49,22 +51,26 @@ void psbt_rm_output(struct wally_psbt *psbt,
 void psbt_input_add_pubkey(struct wally_psbt *psbt, size_t in,
 			   const struct pubkey *pubkey);
 
-void psbt_input_set_partial_sig(struct wally_psbt *psbt, size_t in,
-				const struct pubkey *pubkey,
-				const struct bitcoin_signature *sig);
+WARN_UNUSED_RESULT bool psbt_input_set_partial_sig(struct wally_psbt *psbt, size_t in,
+						   const struct pubkey *pubkey,
+						   const struct bitcoin_signature *sig);
 
 void psbt_input_set_prev_utxo(struct wally_psbt *psbt, size_t in,
 			      const u8 *wscript, struct amount_sat amt);
 void psbt_input_set_prev_utxo_wscript(struct wally_psbt *psbt, size_t in,
 			              const u8 *wscript, struct amount_sat amt);
+bool psbt_input_set_redeemscript(struct wally_psbt *psbt, size_t in,
+				 const u8 *redeemscript);
 struct amount_sat psbt_input_get_amount(struct wally_psbt *psbt,
 					size_t in);
 
+bool psbt_from_b64(const char *b64str, struct wally_psbt **psbt);
+char *psbt_to_b64(const tal_t *ctx, const struct wally_psbt *psbt);
 const u8 *psbt_get_bytes(const tal_t *ctx, const struct wally_psbt *psbt,
 			 size_t *bytes_written);
 struct wally_psbt *psbt_from_bytes(const tal_t *ctx, const u8 *bytes,
 				   size_t byte_len);
-void towire_psbt(u8 **pptr, const struct wally_psbt *psbt);
-struct wally_psbt *fromwire_psbt(const tal_t *ctx,
-				 const u8 **curosr, size_t *max);
+void towire_wally_psbt(u8 **pptr, const struct wally_psbt *psbt);
+struct wally_psbt *fromwire_wally_psbt(const tal_t *ctx,
+				       const u8 **cursor, size_t *max);
 #endif /* LIGHTNING_BITCOIN_PSBT_H */

bitcoin/tx.c

@@ -32,6 +32,16 @@ int wally_tx_clone(struct wally_tx *tx, struct wally_tx **output)
 	return ret;
 }
 
+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,
 			  u8 *wscript, struct amount_sat amount)
 {
@@ -484,48 +494,20 @@ void bitcoin_tx_finalize(struct bitcoin_tx *tx)
 	assert(bitcoin_tx_check(tx));
 }
 
-char *bitcoin_tx_to_psbt_base64(const tal_t *ctx, struct bitcoin_tx *tx)
-{
-	char *serialized_psbt, *ret_val;
-	int ret;
-
-	ret = wally_psbt_to_base64(tx->psbt, &serialized_psbt);
-	assert(ret == WALLY_OK);
-
-	ret_val = tal_strdup(ctx, serialized_psbt);
-	wally_free_string(serialized_psbt);
-	return ret_val;
-}
-
 struct bitcoin_tx *bitcoin_tx_with_psbt(const tal_t *ctx, struct wally_psbt *psbt STEALS)
 {
-	struct wally_psbt *tmppsbt;
 	struct bitcoin_tx *tx = bitcoin_tx(ctx, chainparams,
 					   psbt->tx->num_inputs,
 					   psbt->tx->num_outputs,
 					   psbt->tx->locktime);
 	wally_tx_free(tx->wtx);
-
-	/* We want the 'finalized' tx since that includes any signature
-	 * data, not the global tx. But 'finalizing' a tx destroys some fields
-	 * so we 'clone' it first and then finalize it */
-	if (wally_psbt_clone(psbt, &tmppsbt) != WALLY_OK)
-		abort();
-
-	if (wally_finalize_psbt(tmppsbt) != WALLY_OK)
-		abort();
-
-	if (psbt_is_finalized(tmppsbt)) {
-		if (wally_extract_psbt(tmppsbt, &tx->wtx) != WALLY_OK)
-			abort();
-	} else if (wally_tx_clone(psbt->tx, &tx->wtx) != WALLY_OK)
-		abort();
-
-
-	wally_psbt_free(tmppsbt);
+	tx->wtx = psbt_finalize(psbt, false);
+	if (!tx->wtx && wally_tx_clone(psbt->tx, &tx->wtx) != WALLY_OK)
+		return NULL;
 
 	tal_free(tx->psbt);
 	tx->psbt = tal_steal(tx, psbt);
+
 	return tx;
 }
 
@@ -665,7 +647,7 @@ struct bitcoin_tx *fromwire_bitcoin_tx(const tal_t *ctx,
 
 	/* pull_bitcoin_tx sets the psbt */
 	tal_free(tx->psbt);
-	tx->psbt = fromwire_psbt(tx, cursor, max);
+	tx->psbt = fromwire_wally_psbt(tx, cursor, max);
 
 	return tx;
 }
@@ -680,7 +662,7 @@ void towire_bitcoin_tx(u8 **pptr, const struct bitcoin_tx *tx)
 	u8 *lin = linearize_tx(tmpctx, tx);
 	towire_u8_array(pptr, lin, tal_count(lin));
 
-	towire_psbt(pptr, tx->psbt);
+	towire_wally_psbt(pptr, tx->psbt);
 }
 
 struct bitcoin_tx_output *fromwire_bitcoin_tx_output(const tal_t *ctx,

bitcoin/tx.h

@@ -35,6 +35,10 @@ struct bitcoin_tx_output {
 	u8 *script;
 };
 
+struct bitcoin_tx_output *new_tx_output(const tal_t *ctx,
+					struct amount_sat amount,
+					const u8 *script);
+
 /* SHA256^2 the tx in legacy format. */
 void bitcoin_txid(const struct bitcoin_tx *tx, struct bitcoin_txid *txid);
 void wally_txid(const struct wally_tx *wtx, struct bitcoin_txid *txid);
@@ -216,10 +220,5 @@ void towire_bitcoin_txid(u8 **pptr, const struct bitcoin_txid *txid);
 void towire_bitcoin_tx(u8 **pptr, const struct bitcoin_tx *tx);
 void towire_bitcoin_tx_output(u8 **pptr, const struct bitcoin_tx_output *output);
 
-/*
- * Get the base64 string encoded PSBT of a bitcoin transaction.
- */
-char *bitcoin_tx_to_psbt_base64(const tal_t *ctx, struct bitcoin_tx *tx);
-
 int wally_tx_clone(struct wally_tx *tx, struct wally_tx **output);
 #endif /* LIGHTNING_BITCOIN_TX_H */

channeld/channeld.c

@@ -1291,8 +1291,11 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 			peer->next_index[LOCAL], LOCAL);
 
 	/* Set the commit_sig on the commitment tx psbt */
-	psbt_input_set_partial_sig(txs[0]->psbt, 0,
-	    &peer->channel->funding_pubkey[REMOTE], &commit_sig);
+	if (!psbt_input_set_partial_sig(txs[0]->psbt, 0,
+					&peer->channel->funding_pubkey[REMOTE],
+					&commit_sig))
+		status_failed(STATUS_FAIL_INTERNAL_ERROR,
+			      "Unable to set signature internally");
 
 	if (!derive_simple_key(&peer->channel->basepoints[REMOTE].htlc,
 			       &peer->next_local_per_commit, &remote_htlckey))

common/json_helpers.c

@@ -1,6 +1,7 @@
 #include <arpa/inet.h>
 #include <bitcoin/preimage.h>
 #include <bitcoin/privkey.h>
+#include <bitcoin/psbt.h>
 #include <bitcoin/pubkey.h>
 #include <bitcoin/short_channel_id.h>
 #include <ccan/ccan/str/hex/hex.h>
@@ -242,10 +243,10 @@ void json_add_tx(struct json_stream *result,
 
 void json_add_psbt(struct json_stream *stream,
 		   const char *fieldname,
-		   struct bitcoin_tx *tx)
+		   struct wally_psbt *psbt)
 {
 	const char *psbt_b64;
-	psbt_b64 = bitcoin_tx_to_psbt_base64(tx, tx);
+	psbt_b64 = psbt_to_b64(NULL, psbt);
 	json_add_string(stream, fieldname, take(psbt_b64));
 }
 

common/json_helpers.h

@@ -141,6 +141,6 @@ void json_add_tx(struct json_stream *result,
 /* '"fieldname" : "cHNidP8BAJoCAAAAAljo..." or "cHNidP8BAJoCAAAAAljo..." if fieldname is NULL */
 void json_add_psbt(struct json_stream *stream,
 		   const char *fieldname,
-		   struct bitcoin_tx *tx);
+		   struct wally_psbt *psbt);
 
 #endif /* LIGHTNING_COMMON_JSON_HELPERS_H */

common/type_to_string.h

@@ -4,6 +4,7 @@
 #include "utils.h"
 #include <ccan/autodata/autodata.h>
 #include <secp256k1.h>
+#include <wally_psbt.h>
 
 /* This must match the type_to_string_ cases. */
 union printable_types {
@@ -35,6 +36,7 @@ union printable_types {
 	const struct amount_sat *amount_sat;
 	const struct fee_states *fee_states;
 	const char *charp_;
+	const struct wally_psbt *wally_psbt;
 };
 
 #define type_to_string(ctx, type, ptr)					\