Function handle_mfc_change

plugins/spender/multifundchannel.c:1225–1268

}

static struct command_result *
handle_mfc_change(struct multifundchannel_command *mfc)
{
	size_t change_weight;
	struct amount_sat change_fee, fee_paid, total_fee;
	struct amount_sat change_min_limit;

	/* Determine if adding a change output is worth it.
	 * Get the weight of a change output and how much it
	 * costs.
	 */
	change_weight = bitcoin_tx_output_weight(
				BITCOIN_SCRIPTPUBKEY_P2WPKH_LEN);

	/* To avoid 'off-by-one' errors due to rounding down
	 * (which we do in `amount_tx_fee`), we find the total calculated
	 * fees (estimated_weight + change weight @ feerate) and subtract
	 * the originally calculated fees (estimated_weight @ feerate) */
	fee_paid = amount_tx_fee(mfc->feerate_per_kw,
				 mfc->estimated_final_weight);
	total_fee = amount_tx_fee(mfc->feerate_per_kw,
				  mfc->estimated_final_weight + change_weight);
	if (!amount_sat_sub(&change_fee, total_fee, fee_paid))
		abort();

	/* The limit is equal to the change_fee plus the dust limit.  */
	if (!amount_sat_add(&change_min_limit,
			    change_fee, chainparams->dust_limit))
		plugin_err(mfc->cmd->plugin,
			   "Overflow dust limit and change fee.");

	/* Is the excess over the limit?  */
	if (amount_sat_greater(mfc->excess_sat, change_min_limit)) {
		bool ok = amount_sat_sub(&mfc->change_amount,
					 mfc->excess_sat, change_fee);
		assert(ok);
		mfc->change_needed = true;
		if (!mfc->change_scriptpubkey)
			return acquire_change_address(mfc);
	} else
		mfc->change_needed = false;

	return mfc_psbt_acquired(mfc);
}

/* If one of the destinations specified "all", figure out how much that is.  */
static struct command_result *