core-lightning/common/psbt_keypath.c

#include "config.h"
#include <bitcoin/tx.h>
#include <common/psbt_keypath.h>
#include <common/utils.h>
#include <wally_bip32.h>

void psbt_output_set_keypath(u32 index, const struct ext_key *ext, bool is_taproot, struct wally_psbt_output *output) {
	u8 fingerprint[BIP32_KEY_FINGERPRINT_LEN];
	if (bip32_key_get_fingerprint(
		    (struct ext_key *) ext, fingerprint, sizeof(fingerprint)) != WALLY_OK)
		abort();

	u32 path[1];
	path[0] = index;

	if (is_taproot) {
		if (wally_psbt_output_taproot_keypath_add(output,
							  ext->pub_key + 1, sizeof(ext->pub_key) - 1,
							  NULL, 0,
							  fingerprint, sizeof(fingerprint),
							  path, 1) != WALLY_OK)
			abort();
	} else {
		if (wally_psbt_output_keypath_add(output,
						  ext->pub_key, sizeof(ext->pub_key),
						  fingerprint, sizeof(fingerprint),
						  path, 1) != WALLY_OK)
			abort();
	}

}

void psbt_add_keypath_to_last_output(struct bitcoin_tx *tx,
				     u32 key_index,
					 const struct ext_key *ext,
					 bool is_taproot) {
	size_t outndx = tx->psbt->num_outputs - 1;

	tal_wally_start();
	psbt_output_set_keypath(key_index, ext, is_taproot, &tx->psbt->outputs[outndx]);
	tal_wally_end(tx->psbt);
}