use crate::ln::PaymentSecret;
use crate::ln::features::BlindedHopFeatures;
use crate::ln::msgs::DecodeError;
+use crate::offers::invoice::BlindedPayInfo;
use crate::prelude::*;
use crate::util::ser::{Readable, Writeable, Writer};
+use core::convert::TryFrom;
+
+/// 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,
}
/// Data to construct a [`BlindedHop`] for sending a payment over.
/// 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
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),
-});
+impl Writeable for ForwardTlvs {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ encode_tlv_stream!(w, {
+ (2, self.short_channel_id, required),
+ (10, self.payment_relay, required),
+ (12, self.payment_constraints, required),
+ (14, self.features, required)
+ });
+ Ok(())
+ }
+}
-impl_writeable_tlv_based!(ReceiveTlvs, {
- (12, payment_constraints, required),
- (65536, payment_secret, required),
-});
+impl Writeable for ReceiveTlvs {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ encode_tlv_stream!(w, {
+ (12, self.payment_constraints, required),
+ (65536, self.payment_secret, required)
+ });
+ Ok(())
+ }
+}
impl<'a> Writeable for BlindedPaymentTlvsRef<'a> {
fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
/// Construct blinded payment hops for the given `intermediate_nodes` and payee info.
pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
- secp_ctx: &Secp256k1<T>, intermediate_nodes: &[(PublicKey, ForwardTlvs)],
+ secp_ctx: &Secp256k1<T>, intermediate_nodes: &[ForwardNode],
payee_node_id: PublicKey, payee_tlvs: ReceiveTlvs, session_priv: &SecretKey
) -> Result<Vec<BlindedHop>, 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)
}
+/// `None` if underflow occurs.
+fn amt_to_forward_msat(inbound_amt_msat: u64, payment_relay: &PaymentRelay) -> Option<u64> {
+ 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
+) -> Result<BlindedPayInfo, ()> {
+ let mut curr_base_fee: u64 = 0;
+ let mut curr_prop_mil: u64 = 0;
+ let mut cltv_expiry_delta: u16 = 0;
+ 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(()) }
+
+ 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_msg!(PaymentRelay, {
cltv_expiry_delta,
fee_proportional_millionths,
max_cltv_expiry,
htlc_minimum_msat
}, {});
+
+#[cfg(test)]
+mod tests {
+ use bitcoin::secp256k1::PublicKey;
+ use crate::blinded_path::payment::{ForwardNode, ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentRelay};
+ use crate::ln::PaymentSecret;
+ use crate::ln::features::BlindedHopFeatures;
+
+ #[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,
+ },
+ };
+ let htlc_maximum_msat = 100_000;
+ let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
+ assert_eq!(blinded_payinfo.fee_base_msat, 201);
+ assert_eq!(blinded_payinfo.fee_proportional_millionths, 1001);
+ assert_eq!(blinded_payinfo.cltv_expiry_delta, 288);
+ 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,
+ },
+ };
+ let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs, 4242).unwrap();
+ assert_eq!(blinded_payinfo.fee_base_msat, 0);
+ assert_eq!(blinded_payinfo.fee_proportional_millionths, 0);
+ assert_eq!(blinded_payinfo.cltv_expiry_delta, 0);
+ 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,
+ },
+ };
+ let htlc_maximum_msat = 100_000;
+ let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).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,
+ },
+ };
+ let htlc_minimum_msat = 3798;
+ assert!(super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_minimum_msat - 1).is_err());
+
+ let htlc_maximum_msat = htlc_minimum_msat + 1;
+ let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).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,
+ },
+ };
+
+ let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, 10_000).unwrap();
+ assert_eq!(blinded_payinfo.htlc_maximum_msat, 3997);
+ }
+}
projects / rust-lightning / commitdiff