X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fblinded_path%2Fpayment.rs;h=ec441c18c986ed4788948dcf09465e07233878d8;hb=8367e021103493b811b9366e2355bd09e91b4836;hp=0f6cf01858dc5666411ca6f1d6fe10cfc3f9a323;hpb=32d6e91fd6547241a04dc7827e11efe0ed7e5f4f;p=rust-lightning diff --git a/lightning/src/blinded_path/payment.rs b/lightning/src/blinded_path/payment.rs index 0f6cf018..ec441c18 100644 --- a/lightning/src/blinded_path/payment.rs +++ b/lightning/src/blinded_path/payment.rs @@ -8,33 +8,55 @@ use crate::blinded_path::BlindedHop; use crate::blinded_path::utils; use crate::io; use crate::ln::PaymentSecret; +use crate::ln::channelmanager::CounterpartyForwardingInfo; use crate::ln::features::BlindedHopFeatures; use crate::ln::msgs::DecodeError; +use crate::offers::invoice::BlindedPayInfo; +use crate::offers::invoice_request::InvoiceRequestFields; +use crate::offers::offer::OfferId; +use crate::util::ser::{HighZeroBytesDroppedBigSize, Readable, Writeable, Writer}; + +#[allow(unused_imports)] use crate::prelude::*; -use crate::util::ser::{Readable, Writeable, Writer}; + +/// An intermediate node, its outbound channel, and relay parameters. +#[derive(Clone, Debug)] +pub struct ForwardNode { + /// The TLVs for this node's [`BlindedHop`], where the fee parameters contained within are also + /// used for [`BlindedPayInfo`] construction. + pub tlvs: ForwardTlvs, + /// This node's pubkey. + pub node_id: PublicKey, + /// The maximum value, in msat, that may be accepted by this node. + pub htlc_maximum_msat: u64, +} /// Data to construct a [`BlindedHop`] for forwarding a payment. +#[derive(Clone, Debug)] pub struct ForwardTlvs { /// The short channel id this payment should be forwarded out over. - short_channel_id: u64, + pub short_channel_id: u64, /// Payment parameters for relaying over [`Self::short_channel_id`]. - payment_relay: PaymentRelay, + pub payment_relay: PaymentRelay, /// Payment constraints for relaying over [`Self::short_channel_id`]. - payment_constraints: PaymentConstraints, + pub payment_constraints: PaymentConstraints, /// Supported and required features when relaying a payment onion containing this object's /// corresponding [`BlindedHop::encrypted_payload`]. /// /// [`BlindedHop::encrypted_payload`]: crate::blinded_path::BlindedHop::encrypted_payload - features: BlindedHopFeatures, + pub features: BlindedHopFeatures, } /// Data to construct a [`BlindedHop`] for receiving a payment. This payload is custom to LDK and /// may not be valid if received by another lightning implementation. +#[derive(Clone, Debug)] pub struct ReceiveTlvs { /// Used to authenticate the sender of a payment to the receiver and tie MPP HTLCs together. - payment_secret: PaymentSecret, + pub payment_secret: PaymentSecret, /// Constraints for the receiver of this payment. - payment_constraints: PaymentConstraints, + pub payment_constraints: PaymentConstraints, + /// Context for the receiver of this payment. + pub payment_context: PaymentContext, } /// Data to construct a [`BlindedHop`] for sending a payment over. @@ -56,46 +78,135 @@ enum BlindedPaymentTlvsRef<'a> { /// Parameters for relaying over a given [`BlindedHop`]. /// /// [`BlindedHop`]: crate::blinded_path::BlindedHop +#[derive(Clone, Debug)] pub struct PaymentRelay { /// Number of blocks subtracted from an incoming HTLC's `cltv_expiry` for this [`BlindedHop`]. - /// - ///[`BlindedHop`]: crate::blinded_path::BlindedHop pub cltv_expiry_delta: u16, /// Liquidity fee charged (in millionths of the amount transferred) for relaying a payment over /// this [`BlindedHop`], (i.e., 10,000 is 1%). - /// - ///[`BlindedHop`]: crate::blinded_path::BlindedHop pub fee_proportional_millionths: u32, /// Base fee charged (in millisatoshi) for relaying a payment over this [`BlindedHop`]. - /// - ///[`BlindedHop`]: crate::blinded_path::BlindedHop pub fee_base_msat: u32, } /// Constraints for relaying over a given [`BlindedHop`]. /// /// [`BlindedHop`]: crate::blinded_path::BlindedHop +#[derive(Clone, Debug)] pub struct PaymentConstraints { - /// The maximum total CLTV delta that is acceptable when relaying a payment over this - /// [`BlindedHop`]. - /// - ///[`BlindedHop`]: crate::blinded_path::BlindedHop + /// The maximum total CLTV that is acceptable when relaying a payment over this [`BlindedHop`]. pub max_cltv_expiry: u32, - /// The minimum value, in msat, that may be relayed over this [`BlindedHop`]. + /// The minimum value, in msat, that may be accepted by the node corresponding to this + /// [`BlindedHop`]. pub htlc_minimum_msat: u64, } -impl_writeable_tlv_based!(ForwardTlvs, { - (2, short_channel_id, required), - (10, payment_relay, required), - (12, payment_constraints, required), - (14, features, required), -}); +/// The context of an inbound payment, which is included in a [`BlindedPath`] via [`ReceiveTlvs`] +/// and surfaced in [`PaymentPurpose`]. +/// +/// [`BlindedPath`]: crate::blinded_path::BlindedPath +/// [`PaymentPurpose`]: crate::events::PaymentPurpose +#[derive(Clone, Debug, Eq, PartialEq)] +pub enum PaymentContext { + /// The payment context was unknown. + Unknown(UnknownPaymentContext), -impl_writeable_tlv_based!(ReceiveTlvs, { - (12, payment_constraints, required), - (65536, payment_secret, required), -}); + /// The payment was made for an invoice requested from a BOLT 12 [`Offer`]. + /// + /// [`Offer`]: crate::offers::offer::Offer + Bolt12Offer(Bolt12OfferContext), + + /// The payment was made for an invoice sent for a BOLT 12 [`Refund`]. + /// + /// [`Refund`]: crate::offers::refund::Refund + Bolt12Refund(Bolt12RefundContext), +} + +// Used when writing PaymentContext in Event::PaymentClaimable to avoid cloning. +pub(crate) enum PaymentContextRef<'a> { + Bolt12Offer(&'a Bolt12OfferContext), + Bolt12Refund(&'a Bolt12RefundContext), +} + +/// An unknown payment context. +#[derive(Clone, Debug, Eq, PartialEq)] +pub struct UnknownPaymentContext(()); + +/// The context of a payment made for an invoice requested from a BOLT 12 [`Offer`]. +/// +/// [`Offer`]: crate::offers::offer::Offer +#[derive(Clone, Debug, Eq, PartialEq)] +pub struct Bolt12OfferContext { + /// The identifier of the [`Offer`]. + /// + /// [`Offer`]: crate::offers::offer::Offer + pub offer_id: OfferId, + + /// Fields from an [`InvoiceRequest`] sent for a [`Bolt12Invoice`]. + /// + /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest + /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice + pub invoice_request: InvoiceRequestFields, +} + +/// The context of a payment made for an invoice sent for a BOLT 12 [`Refund`]. +/// +/// [`Refund`]: crate::offers::refund::Refund +#[derive(Clone, Debug, Eq, PartialEq)] +pub struct Bolt12RefundContext {} + +impl PaymentContext { + pub(crate) fn unknown() -> Self { + PaymentContext::Unknown(UnknownPaymentContext(())) + } +} + +impl TryFrom for PaymentRelay { + type Error = (); + + fn try_from(info: CounterpartyForwardingInfo) -> Result { + let CounterpartyForwardingInfo { + fee_base_msat, fee_proportional_millionths, cltv_expiry_delta + } = info; + + // Avoid exposing esoteric CLTV expiry deltas + let cltv_expiry_delta = match cltv_expiry_delta { + 0..=40 => 40, + 41..=80 => 80, + 81..=144 => 144, + 145..=216 => 216, + _ => return Err(()), + }; + + Ok(Self { cltv_expiry_delta, fee_proportional_millionths, fee_base_msat }) + } +} + +impl Writeable for ForwardTlvs { + fn write(&self, w: &mut W) -> Result<(), io::Error> { + let features_opt = + if self.features == BlindedHopFeatures::empty() { None } + else { Some(&self.features) }; + encode_tlv_stream!(w, { + (2, self.short_channel_id, required), + (10, self.payment_relay, required), + (12, self.payment_constraints, required), + (14, features_opt, option) + }); + Ok(()) + } +} + +impl Writeable for ReceiveTlvs { + fn write(&self, w: &mut W) -> Result<(), io::Error> { + encode_tlv_stream!(w, { + (12, self.payment_constraints, required), + (65536, self.payment_secret, required), + (65537, self.payment_context, required) + }); + Ok(()) + } +} impl<'a> Writeable for BlindedPaymentTlvsRef<'a> { fn write(&self, w: &mut W) -> Result<(), io::Error> { @@ -117,22 +228,26 @@ impl Readable for BlindedPaymentTlvs { (12, payment_constraints, required), (14, features, option), (65536, payment_secret, option), + (65537, payment_context, (default_value, PaymentContext::unknown())), }); let _padding: Option = _padding; if let Some(short_channel_id) = scid { - if payment_secret.is_some() { return Err(DecodeError::InvalidValue) } + if payment_secret.is_some() { + return Err(DecodeError::InvalidValue) + } Ok(BlindedPaymentTlvs::Forward(ForwardTlvs { short_channel_id, payment_relay: payment_relay.ok_or(DecodeError::InvalidValue)?, payment_constraints: payment_constraints.0.unwrap(), - features: features.ok_or(DecodeError::InvalidValue)?, + features: features.unwrap_or_else(BlindedHopFeatures::empty), })) } else { if payment_relay.is_some() || features.is_some() { return Err(DecodeError::InvalidValue) } Ok(BlindedPaymentTlvs::Receive(ReceiveTlvs { payment_secret: payment_secret.ok_or(DecodeError::InvalidValue)?, payment_constraints: payment_constraints.0.unwrap(), + payment_context: payment_context.0.unwrap(), })) } } @@ -140,23 +255,407 @@ impl Readable for BlindedPaymentTlvs { /// Construct blinded payment hops for the given `intermediate_nodes` and payee info. pub(super) fn blinded_hops( - secp_ctx: &Secp256k1, intermediate_nodes: &[(PublicKey, ForwardTlvs)], + secp_ctx: &Secp256k1, intermediate_nodes: &[ForwardNode], payee_node_id: PublicKey, payee_tlvs: ReceiveTlvs, session_priv: &SecretKey ) -> Result, secp256k1::Error> { - let pks = intermediate_nodes.iter().map(|(pk, _)| pk) + let pks = intermediate_nodes.iter().map(|node| &node.node_id) .chain(core::iter::once(&payee_node_id)); - let tlvs = intermediate_nodes.iter().map(|(_, tlvs)| BlindedPaymentTlvsRef::Forward(tlvs)) + let tlvs = intermediate_nodes.iter().map(|node| BlindedPaymentTlvsRef::Forward(&node.tlvs)) .chain(core::iter::once(BlindedPaymentTlvsRef::Receive(&payee_tlvs))); utils::construct_blinded_hops(secp_ctx, pks, tlvs, session_priv) } -impl_writeable_msg!(PaymentRelay, { - cltv_expiry_delta, - fee_proportional_millionths, - fee_base_msat -}, {}); +/// `None` if underflow occurs. +pub(crate) fn amt_to_forward_msat(inbound_amt_msat: u64, payment_relay: &PaymentRelay) -> Option { + let inbound_amt = inbound_amt_msat as u128; + let base = payment_relay.fee_base_msat as u128; + let prop = payment_relay.fee_proportional_millionths as u128; + + let post_base_fee_inbound_amt = + if let Some(amt) = inbound_amt.checked_sub(base) { amt } else { return None }; + let mut amt_to_forward = + (post_base_fee_inbound_amt * 1_000_000 + 1_000_000 + prop - 1) / (prop + 1_000_000); + + let fee = ((amt_to_forward * prop) / 1_000_000) + base; + if inbound_amt - fee < amt_to_forward { + // Rounding up the forwarded amount resulted in underpaying this node, so take an extra 1 msat + // in fee to compensate. + amt_to_forward -= 1; + } + debug_assert_eq!(amt_to_forward + fee, inbound_amt); + u64::try_from(amt_to_forward).ok() +} + +pub(super) fn compute_payinfo( + intermediate_nodes: &[ForwardNode], payee_tlvs: &ReceiveTlvs, payee_htlc_maximum_msat: u64, + min_final_cltv_expiry_delta: u16 +) -> Result { + let mut curr_base_fee: u64 = 0; + let mut curr_prop_mil: u64 = 0; + let mut cltv_expiry_delta: u16 = min_final_cltv_expiry_delta; + for tlvs in intermediate_nodes.iter().rev().map(|n| &n.tlvs) { + // In the future, we'll want to take the intersection of all supported features for the + // `BlindedPayInfo`, but there are no features in that context right now. + if tlvs.features.requires_unknown_bits_from(&BlindedHopFeatures::empty()) { return Err(()) } -impl_writeable_msg!(PaymentConstraints, { - max_cltv_expiry, - htlc_minimum_msat -}, {}); + let next_base_fee = tlvs.payment_relay.fee_base_msat as u64; + let next_prop_mil = tlvs.payment_relay.fee_proportional_millionths as u64; + // Use integer arithmetic to compute `ceil(a/b)` as `(a+b-1)/b` + // ((curr_base_fee * (1_000_000 + next_prop_mil)) / 1_000_000) + next_base_fee + curr_base_fee = curr_base_fee.checked_mul(1_000_000 + next_prop_mil) + .and_then(|f| f.checked_add(1_000_000 - 1)) + .map(|f| f / 1_000_000) + .and_then(|f| f.checked_add(next_base_fee)) + .ok_or(())?; + // ceil(((curr_prop_mil + 1_000_000) * (next_prop_mil + 1_000_000)) / 1_000_000) - 1_000_000 + curr_prop_mil = curr_prop_mil.checked_add(1_000_000) + .and_then(|f1| next_prop_mil.checked_add(1_000_000).and_then(|f2| f2.checked_mul(f1))) + .and_then(|f| f.checked_add(1_000_000 - 1)) + .map(|f| f / 1_000_000) + .and_then(|f| f.checked_sub(1_000_000)) + .ok_or(())?; + + cltv_expiry_delta = cltv_expiry_delta.checked_add(tlvs.payment_relay.cltv_expiry_delta).ok_or(())?; + } + + let mut htlc_minimum_msat: u64 = 1; + let mut htlc_maximum_msat: u64 = 21_000_000 * 100_000_000 * 1_000; // Total bitcoin supply + for node in intermediate_nodes.iter() { + // The min htlc for an intermediate node is that node's min minus the fees charged by all of the + // following hops for forwarding that min, since that fee amount will automatically be included + // in the amount that this node receives and contribute towards reaching its min. + htlc_minimum_msat = amt_to_forward_msat( + core::cmp::max(node.tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat), + &node.tlvs.payment_relay + ).unwrap_or(1); // If underflow occurs, we definitely reached this node's min + htlc_maximum_msat = amt_to_forward_msat( + core::cmp::min(node.htlc_maximum_msat, htlc_maximum_msat), &node.tlvs.payment_relay + ).ok_or(())?; // If underflow occurs, we cannot send to this hop without exceeding their max + } + htlc_minimum_msat = core::cmp::max( + payee_tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat + ); + htlc_maximum_msat = core::cmp::min(payee_htlc_maximum_msat, htlc_maximum_msat); + + if htlc_maximum_msat < htlc_minimum_msat { return Err(()) } + Ok(BlindedPayInfo { + fee_base_msat: u32::try_from(curr_base_fee).map_err(|_| ())?, + fee_proportional_millionths: u32::try_from(curr_prop_mil).map_err(|_| ())?, + cltv_expiry_delta, + htlc_minimum_msat, + htlc_maximum_msat, + features: BlindedHopFeatures::empty(), + }) +} + +impl Writeable for PaymentRelay { + fn write(&self, w: &mut W) -> Result<(), io::Error> { + self.cltv_expiry_delta.write(w)?; + self.fee_proportional_millionths.write(w)?; + HighZeroBytesDroppedBigSize(self.fee_base_msat).write(w) + } +} +impl Readable for PaymentRelay { + fn read(r: &mut R) -> Result { + let cltv_expiry_delta: u16 = Readable::read(r)?; + let fee_proportional_millionths: u32 = Readable::read(r)?; + let fee_base_msat: HighZeroBytesDroppedBigSize = Readable::read(r)?; + Ok(Self { cltv_expiry_delta, fee_proportional_millionths, fee_base_msat: fee_base_msat.0 }) + } +} + +impl Writeable for PaymentConstraints { + fn write(&self, w: &mut W) -> Result<(), io::Error> { + self.max_cltv_expiry.write(w)?; + HighZeroBytesDroppedBigSize(self.htlc_minimum_msat).write(w) + } +} +impl Readable for PaymentConstraints { + fn read(r: &mut R) -> Result { + let max_cltv_expiry: u32 = Readable::read(r)?; + let htlc_minimum_msat: HighZeroBytesDroppedBigSize = Readable::read(r)?; + Ok(Self { max_cltv_expiry, htlc_minimum_msat: htlc_minimum_msat.0 }) + } +} + +impl_writeable_tlv_based_enum!(PaymentContext, + ; + (0, Unknown), + (1, Bolt12Offer), + (2, Bolt12Refund), +); + +impl<'a> Writeable for PaymentContextRef<'a> { + fn write(&self, w: &mut W) -> Result<(), io::Error> { + match self { + PaymentContextRef::Bolt12Offer(context) => { + 1u8.write(w)?; + context.write(w)?; + }, + PaymentContextRef::Bolt12Refund(context) => { + 2u8.write(w)?; + context.write(w)?; + }, + } + + Ok(()) + } +} + +impl Writeable for UnknownPaymentContext { + fn write(&self, _w: &mut W) -> Result<(), io::Error> { + Ok(()) + } +} + +impl Readable for UnknownPaymentContext { + fn read(_r: &mut R) -> Result { + Ok(UnknownPaymentContext(())) + } +} + +impl_writeable_tlv_based!(Bolt12OfferContext, { + (0, offer_id, required), + (2, invoice_request, required), +}); + +impl_writeable_tlv_based!(Bolt12RefundContext, {}); + +#[cfg(test)] +mod tests { + use bitcoin::secp256k1::PublicKey; + use crate::blinded_path::payment::{ForwardNode, ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentContext, PaymentRelay}; + use crate::ln::PaymentSecret; + use crate::ln::features::BlindedHopFeatures; + use crate::ln::functional_test_utils::TEST_FINAL_CLTV; + + #[test] + fn compute_payinfo() { + // Taken from the spec example for aggregating blinded payment info. See + // https://github.com/lightning/bolts/blob/master/proposals/route-blinding.md#blinded-payments + let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap(); + let intermediate_nodes = vec![ForwardNode { + node_id: dummy_pk, + tlvs: ForwardTlvs { + short_channel_id: 0, + payment_relay: PaymentRelay { + cltv_expiry_delta: 144, + fee_proportional_millionths: 500, + fee_base_msat: 100, + }, + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 100, + }, + features: BlindedHopFeatures::empty(), + }, + htlc_maximum_msat: u64::max_value(), + }, ForwardNode { + node_id: dummy_pk, + tlvs: ForwardTlvs { + short_channel_id: 0, + payment_relay: PaymentRelay { + cltv_expiry_delta: 144, + fee_proportional_millionths: 500, + fee_base_msat: 100, + }, + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 1_000, + }, + features: BlindedHopFeatures::empty(), + }, + htlc_maximum_msat: u64::max_value(), + }]; + let recv_tlvs = ReceiveTlvs { + payment_secret: PaymentSecret([0; 32]), + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 1, + }, + payment_context: PaymentContext::unknown(), + }; + let htlc_maximum_msat = 100_000; + let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, 12).unwrap(); + assert_eq!(blinded_payinfo.fee_base_msat, 201); + assert_eq!(blinded_payinfo.fee_proportional_millionths, 1001); + assert_eq!(blinded_payinfo.cltv_expiry_delta, 300); + assert_eq!(blinded_payinfo.htlc_minimum_msat, 900); + assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat); + } + + #[test] + fn compute_payinfo_1_hop() { + let recv_tlvs = ReceiveTlvs { + payment_secret: PaymentSecret([0; 32]), + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 1, + }, + payment_context: PaymentContext::unknown(), + }; + let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs, 4242, TEST_FINAL_CLTV as u16).unwrap(); + assert_eq!(blinded_payinfo.fee_base_msat, 0); + assert_eq!(blinded_payinfo.fee_proportional_millionths, 0); + assert_eq!(blinded_payinfo.cltv_expiry_delta, TEST_FINAL_CLTV as u16); + assert_eq!(blinded_payinfo.htlc_minimum_msat, 1); + assert_eq!(blinded_payinfo.htlc_maximum_msat, 4242); + } + + #[test] + fn simple_aggregated_htlc_min() { + // If no hops charge fees, the htlc_minimum_msat should just be the maximum htlc_minimum_msat + // along the path. + let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap(); + let intermediate_nodes = vec![ForwardNode { + node_id: dummy_pk, + tlvs: ForwardTlvs { + short_channel_id: 0, + payment_relay: PaymentRelay { + cltv_expiry_delta: 0, + fee_proportional_millionths: 0, + fee_base_msat: 0, + }, + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 1, + }, + features: BlindedHopFeatures::empty(), + }, + htlc_maximum_msat: u64::max_value() + }, ForwardNode { + node_id: dummy_pk, + tlvs: ForwardTlvs { + short_channel_id: 0, + payment_relay: PaymentRelay { + cltv_expiry_delta: 0, + fee_proportional_millionths: 0, + fee_base_msat: 0, + }, + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 2_000, + }, + features: BlindedHopFeatures::empty(), + }, + htlc_maximum_msat: u64::max_value() + }]; + let recv_tlvs = ReceiveTlvs { + payment_secret: PaymentSecret([0; 32]), + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 3, + }, + payment_context: PaymentContext::unknown(), + }; + let htlc_maximum_msat = 100_000; + let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, TEST_FINAL_CLTV as u16).unwrap(); + assert_eq!(blinded_payinfo.htlc_minimum_msat, 2_000); + } + + #[test] + fn aggregated_htlc_min() { + // Create a path with varying fees and htlc_mins, and make sure htlc_minimum_msat ends up as the + // max (htlc_min - following_fees) along the path. + let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap(); + let intermediate_nodes = vec![ForwardNode { + node_id: dummy_pk, + tlvs: ForwardTlvs { + short_channel_id: 0, + payment_relay: PaymentRelay { + cltv_expiry_delta: 0, + fee_proportional_millionths: 500, + fee_base_msat: 1_000, + }, + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 5_000, + }, + features: BlindedHopFeatures::empty(), + }, + htlc_maximum_msat: u64::max_value() + }, ForwardNode { + node_id: dummy_pk, + tlvs: ForwardTlvs { + short_channel_id: 0, + payment_relay: PaymentRelay { + cltv_expiry_delta: 0, + fee_proportional_millionths: 500, + fee_base_msat: 200, + }, + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 2_000, + }, + features: BlindedHopFeatures::empty(), + }, + htlc_maximum_msat: u64::max_value() + }]; + let recv_tlvs = ReceiveTlvs { + payment_secret: PaymentSecret([0; 32]), + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 1, + }, + payment_context: PaymentContext::unknown(), + }; + let htlc_minimum_msat = 3798; + assert!(super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_minimum_msat - 1, TEST_FINAL_CLTV as u16).is_err()); + + let htlc_maximum_msat = htlc_minimum_msat + 1; + let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, TEST_FINAL_CLTV as u16).unwrap(); + assert_eq!(blinded_payinfo.htlc_minimum_msat, htlc_minimum_msat); + assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat); + } + + #[test] + fn aggregated_htlc_max() { + // Create a path with varying fees and `htlc_maximum_msat`s, and make sure the aggregated max + // htlc ends up as the min (htlc_max - following_fees) along the path. + let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap(); + let intermediate_nodes = vec![ForwardNode { + node_id: dummy_pk, + tlvs: ForwardTlvs { + short_channel_id: 0, + payment_relay: PaymentRelay { + cltv_expiry_delta: 0, + fee_proportional_millionths: 500, + fee_base_msat: 1_000, + }, + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 1, + }, + features: BlindedHopFeatures::empty(), + }, + htlc_maximum_msat: 5_000, + }, ForwardNode { + node_id: dummy_pk, + tlvs: ForwardTlvs { + short_channel_id: 0, + payment_relay: PaymentRelay { + cltv_expiry_delta: 0, + fee_proportional_millionths: 500, + fee_base_msat: 1, + }, + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 1, + }, + features: BlindedHopFeatures::empty(), + }, + htlc_maximum_msat: 10_000 + }]; + let recv_tlvs = ReceiveTlvs { + payment_secret: PaymentSecret([0; 32]), + payment_constraints: PaymentConstraints { + max_cltv_expiry: 0, + htlc_minimum_msat: 1, + }, + payment_context: PaymentContext::unknown(), + }; + + let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, 10_000, TEST_FINAL_CLTV as u16).unwrap(); + assert_eq!(blinded_payinfo.htlc_maximum_msat, 3997); + } +}