psbt: add type-to-string that prints b64 string

Re-uses code from what was the bitcoin_tx_to_psbt_b64

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>
@@ -310,6 +312,28 @@ struct amount_sat psbt_input_get_amount(struct wally_psbt *psbt,
 	return val;
 }
 
+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)
 {

bitcoin/psbt.h

@@ -60,6 +60,8 @@ void psbt_input_set_prev_utxo_wscript(struct wally_psbt *psbt, size_t in,
 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,

bitcoin/tx.c

@@ -486,15 +486,7 @@ void bitcoin_tx_finalize(struct bitcoin_tx *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;
+	return psbt_to_b64(ctx, tx->psbt);
 }
 
 struct bitcoin_tx *bitcoin_tx_with_psbt(const tal_t *ctx, struct wally_psbt *psbt STEALS)

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)					\