Apply a default max fee rather than none when paying for BOLT12

If the user declines to specify a `max_total_routing_fee_msat` in
the new BOLT12 payment methods, rather than defaulting to no limit
on the fee we pay at all, we should default to our "usual default",
ie the one calculated in
`RouteParameters::from_payment_params_and_value`.

We do this here, as well as documenting the behavior on the payment
methods.

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index c9eb534db084a09630cb48b3a38e2fd36b02ac13..4f3caef03e37efb8ca21e2f4d5f1d374c824e887 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -7362,6 +7362,9 @@ where
        /// invoice. If abandoned, or an invoice isn't received before expiration, the payment will fail
        /// with an [`Event::InvoiceRequestFailed`].
        ///
+       /// If `max_total_routing_fee_msat` is not specified, The default from
+       /// [`RouteParameters::from_payment_params_and_value`] is applied.
+       ///
        /// # Privacy
        ///
        /// Uses a one-hop [`BlindedPath`] for the refund with [`ChannelManager::get_our_node_id`] as
@@ -7421,6 +7424,9 @@ where
        /// - `amount_msats` if overpaying what is required for the given `quantity` is desired, and
        /// - `payer_note` for [`InvoiceRequest::payer_note`].
        ///
+       /// If `max_total_routing_fee_msat` is not specified, The default from
+       /// [`RouteParameters::from_payment_params_and_value`] is applied.
+       ///
        /// # Payment
        ///
        /// The provided `payment_id` is used to ensure that only one invoice is paid for the request

diff --git a/lightning/src/ln/outbound_payment.rs b/lightning/src/ln/outbound_payment.rs
index a0aca510574ac6f05fbd22abd40dd8508c475f49..0fbb0f5eaf4ccdeffd32d2a7c9d2aea20888273c 100644 (file)
--- a/lightning/src/ln/outbound_payment.rs
+++ b/lightning/src/ln/outbound_payment.rs
@@ -762,7 +762,6 @@ impl OutboundPayments {
                }
        }
 
-       #[allow(unused)]
        pub(super) fn send_payment_for_bolt12_invoice<R: Deref, ES: Deref, NS: Deref, IH, SP, L: Deref>(
                &self, invoice: &Bolt12Invoice, payment_id: PaymentId, router: &R,
                first_hops: Vec<ChannelDetails>, inflight_htlcs: IH, entropy_source: &ES, node_signer: &NS,
@@ -779,7 +778,7 @@ impl OutboundPayments {
                SP: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
                let payment_hash = invoice.payment_hash();
-               let mut max_total_routing_fee_msat = None;
+               let max_total_routing_fee_msat;
                match self.pending_outbound_payments.lock().unwrap().entry(payment_id) {
                        hash_map::Entry::Occupied(entry) => match entry.get() {
                                PendingOutboundPayment::AwaitingInvoice { retry_strategy, max_total_routing_fee_msat: max_total_fee, .. } => {
@@ -795,11 +794,12 @@ impl OutboundPayments {
                        hash_map::Entry::Vacant(_) => return Err(Bolt12PaymentError::UnexpectedInvoice),
                };
 
-               let route_params = RouteParameters {
-                       payment_params: PaymentParameters::from_bolt12_invoice(&invoice),
-                       final_value_msat: invoice.amount_msats(),
-                       max_total_routing_fee_msat,
-               };
+               let pay_params = PaymentParameters::from_bolt12_invoice(&invoice);
+               let amount_msat = invoice.amount_msats();
+               let mut route_params = RouteParameters::from_payment_params_and_value(pay_params, amount_msat);
+               if let Some(max_fee_msat) = max_total_routing_fee_msat {
+                       route_params.max_total_routing_fee_msat = Some(max_fee_msat);
+               }
 
                self.find_route_and_send_payment(
                        payment_hash, payment_id, route_params, router, first_hops, &inflight_htlcs,