psbt: add helpers for creating + adding input/outputs

5 years ago · 251cde3514
2 changed files with 147 additions and 2 deletions
--- a/bitcoin/psbt.c
+++ b/bitcoin/psbt.c
@ -21,6 +21,36 @@ void psbt_destroy(struct wally_psbt *psbt)
 	wally_psbt_free(psbt);
 }

+static struct wally_psbt *init_psbt(const tal_t *ctx, size_t num_inputs, size_t num_outputs)
+{
+	int wally_err;
+	struct wally_psbt *psbt;
+
+	if (is_elements(chainparams))
+		wally_err = wally_psbt_elements_init_alloc(0, num_inputs, num_outputs, 0, &psbt);
+	else
+		wally_err = wally_psbt_init_alloc(0, num_inputs, num_outputs, 0, &psbt);
+	assert(wally_err == WALLY_OK);
+	tal_add_destructor(psbt, psbt_destroy);
+	return tal_steal(ctx, psbt);
+}
+
+struct wally_psbt *create_psbt(const tal_t *ctx, size_t num_inputs, size_t num_outputs)
+{
+	int wally_err;
+	struct wally_tx *wtx;
+	struct wally_psbt *psbt;
+
+	if (wally_tx_init_alloc(WALLY_TX_VERSION_2, 0, num_inputs, num_outputs, &wtx) != WALLY_OK)
+		abort();
+
+	psbt = init_psbt(ctx, num_inputs, num_outputs);
+
+	wally_err = wally_psbt_set_global_tx(psbt, wtx);
+	assert(wally_err == WALLY_OK);
+	return psbt;
+}
+
 struct wally_psbt *new_psbt(const tal_t *ctx, const struct wally_tx *wtx)
 {
 	struct wally_psbt *psbt;
@ -80,6 +110,28 @@ struct wally_psbt_input *psbt_add_input(struct wally_psbt *psbt,
 	return &psbt->inputs[insert_at];
 }

+struct wally_psbt_input *psbt_append_input(struct wally_psbt *psbt,
+					   const struct bitcoin_txid *txid,
+					   u32 outnum, u32 sequence)
+{
+	struct wally_tx_input *tx_in;
+	struct wally_psbt_input *input;
+	size_t insert_at;
+
+	insert_at = psbt->num_inputs;
+
+	if (wally_tx_input_init_alloc(txid->shad.sha.u.u8,
+				      sizeof(struct bitcoin_txid),
+				      outnum, sequence, NULL, 0, NULL,
+				      &tx_in) != WALLY_OK)
+		abort();
+
+	tx_in->features = chainparams->is_elements ? WALLY_TX_IS_ELEMENTS : 0;
+	input = psbt_add_input(psbt, tx_in, insert_at);
+	wally_tx_input_free(tx_in);
+	return input;
+}
+
 void psbt_rm_input(struct wally_psbt *psbt,
 		   size_t remove_at)
 {
@ -96,6 +148,18 @@ struct wally_psbt_output *psbt_add_output(struct wally_psbt *psbt,
 	return &psbt->outputs[insert_at];
 }

+struct wally_psbt_output *psbt_append_out(struct wally_psbt *psbt,
+					  const u8 *script,
+					  struct amount_sat amount)
+{
+	struct wally_psbt_output *out;
+	struct wally_tx_output *tx_out = wally_tx_output(script, amount);
+
+	out = psbt_add_output(psbt, tx_out, psbt->tx->num_outputs);
+	wally_tx_output_free(tx_out);
+	return out;
+}
+
 void psbt_rm_output(struct wally_psbt *psbt,
 		    size_t remove_at)
 {
@ -298,6 +362,24 @@ void psbt_elements_input_init(struct wally_psbt *psbt, size_t in,
 		abort();
 }

+bool psbt_has_input(struct wally_psbt *psbt,
+		    struct bitcoin_txid *txid,
+		    u32 outnum)
+{
+	for (size_t i = 0; i < psbt->num_inputs; i++) {
+		struct bitcoin_txid in_txid;
+		struct wally_tx_input *in = &psbt->tx->inputs[i];
+
+		if (outnum != in->index)
+			continue;
+
+		wally_tx_input_get_txid(in, &in_txid);
+		if (bitcoin_txid_eq(txid, &in_txid))
+			return true;
+	}
+	return false;
+}
+
 bool psbt_input_set_redeemscript(struct wally_psbt *psbt, size_t in,
 				 const u8 *redeemscript)
 {
@ -329,6 +411,15 @@ struct amount_sat psbt_input_get_amount(struct wally_psbt *psbt,
 	return val;
 }

+struct amount_sat psbt_output_get_amount(struct wally_psbt *psbt,
+					 size_t out)
+{
+	struct amount_asset asset;
+	assert(out < psbt->num_outputs);
+	asset = wally_tx_output_get_amount(&psbt->tx->outputs[out]);
+	assert(amount_asset_is_main(&asset));
+	return amount_asset_to_sat(&asset);
+}
 struct wally_tx *psbt_finalize(struct wally_psbt *psbt, bool finalize_in_place)
 {
 	struct wally_psbt *tmppsbt;
--- a/bitcoin/psbt.h
+++ b/bitcoin/psbt.h
@ -5,11 +5,11 @@
 #include <ccan/tal/tal.h>
 #include <stddef.h>

-struct wally_tx_input;
-struct wally_tx_output;
 struct wally_psbt;
 struct wally_psbt_input;
 struct wally_tx;
+struct wally_tx_input;
+struct wally_tx_output;
 struct amount_asset;
 struct amount_sat;
 struct bitcoin_signature;
@ -18,6 +18,22 @@ struct pubkey;

 void psbt_destroy(struct wally_psbt *psbt);

+/**
+ * create_psbt - Create a new psbt object
+ *
+ * @ctx - allocation context
+ * @num_inputs - number of inputs to allocate
+ * @num_outputs - number of outputs to allocate
+ */
+struct wally_psbt *create_psbt(const tal_t *ctx, size_t num_inputs, size_t num_outputs);
+
+/*
+ * new_psbt - Create a PSBT, using the passed in tx
+ * 	      as the global_tx
+ *
+ * @ctx - allocation context
+ * @wtx - global_tx starter kit
+ */
 struct wally_psbt *new_psbt(const tal_t *ctx,
 			    const struct wally_tx *wtx);

@ -47,6 +63,10 @@ struct wally_psbt_input *psbt_add_input(struct wally_psbt *psbt,
 					struct wally_tx_input *input,
 					size_t insert_at);

+struct wally_psbt_input *psbt_append_input(struct wally_psbt *psbt,
+					   const struct bitcoin_txid *txid,
+					   u32 outnum, u32 sequence);
+
 void psbt_rm_input(struct wally_psbt *psbt,
 		   size_t remove_at);

@ -54,6 +74,17 @@ struct wally_psbt_output *psbt_add_output(struct wally_psbt *psbt,
 					  struct wally_tx_output *output,
 					  size_t insert_at);

+/**
+ * wally_psbt_output - Append a new output to the PSBT
+ *
+ * @psbt - PSBT to append output to
+ * @script - scriptPubKey of the output
+ * @amount - value of the output
+ */
+struct wally_psbt_output *psbt_append_out(struct wally_psbt *psbt,
+					  const u8 *script,
+					  struct amount_sat amount);
+
 void psbt_rm_output(struct wally_psbt *psbt,
 		    size_t remove_at);

@ -81,9 +112,32 @@ void psbt_elements_input_init_witness(struct wally_psbt *psbt, size_t in,
 				      const u8 *nonce);
 bool psbt_input_set_redeemscript(struct wally_psbt *psbt, size_t in,
 				 const u8 *redeemscript);
+/* psbt_input_get_amount - Returns the value of this input
+ *
+ * @psbt - psbt
+ * @in - index of input whose value you're returning
+ * */
 struct amount_sat psbt_input_get_amount(struct wally_psbt *psbt,
 					size_t in);

+/* psbt_output_get_amount - Returns the value of this output
+ *
+ * @psbt - psbt
+ * @out -index of output whose value you're returning
+ */
+struct amount_sat psbt_output_get_amount(struct wally_psbt *psbt,
+					 size_t out);
+
+/* psbt_has_input - Is this input present on this psbt
+ *
+ * @psbt - psbt
+ * @txid - txid of input
+ * @outnum - output index of input
+ */
+bool psbt_has_input(struct wally_psbt *psbt,
+		    struct bitcoin_txid *txid,
+		    u32 outnum);
+
 struct wally_psbt *psbt_from_b64(const tal_t *ctx,
 				 const char *b64,
 				 size_t b64len);