Function set_htlc_timeout_fee

onchaind/onchaind.c:478–524

}

static bool set_htlc_timeout_fee(struct bitcoin_tx *tx,
				 const struct bitcoin_signature *remotesig,
				 const u8 *wscript)
{
	static struct amount_sat amount, fee = AMOUNT_SAT_INIT(UINT64_MAX);
	struct amount_asset asset = bitcoin_tx_output_get_amount(tx, 0);
	size_t weight;

	/* BOLT #3:
	 *
	 * The fee for an HTLC-timeout transaction:
	 *  - If `option_anchors_zero_fee_htlc_tx` applies:
	 *    1. MUST be 0.
	 *  - Otherwise, MUST be calculated to match:
	 *    1. Multiply `feerate_per_kw` by 663 (666 if `option_anchor_outputs`
	 *       applies) and divide by 1000 (rounding down).
	 */
	if (option_anchor_outputs)
		weight = 666;
	else
		weight = 663;
	weight += elements_tx_overhead(chainparams, 1, 1);

	assert(amount_asset_is_main(&asset));
	amount = amount_asset_to_sat(&asset);

	if (amount_sat_eq(fee, AMOUNT_SAT(UINT64_MAX))) {
		struct amount_sat grindfee;
		if (grind_htlc_tx_fee(&grindfee, tx, remotesig, wscript, weight)) {
			/* Cache this for next time */
			fee = grindfee;
			return true;
		}
		return false;
	}

	if (!amount_sat_sub(&amount, amount, fee))
		status_failed(STATUS_FAIL_INTERNAL_ERROR,
			      "Cannot deduct htlc-timeout fee %s from tx %s",
			      type_to_string(tmpctx, struct amount_sat, &fee),
			      type_to_string(tmpctx, struct bitcoin_tx, tx));

	bitcoin_tx_output_set_amount(tx, 0, amount);
	bitcoin_tx_finalize(tx);
	return check_tx_sig(tx, 0, NULL, wscript,
			    &keyset->other_htlc_key, remotesig);
}

static void set_htlc_success_fee(struct bitcoin_tx *tx,
				 const struct bitcoin_signature *remotesig,