From fc0d15136e4668486356dde21d80587218cdedb0 Mon Sep 17 00:00:00 2001 From: Valentine Wallace Date: Sat, 19 Aug 2023 17:56:33 -0400 Subject: [PATCH] Support aggregating htlc_maximum_msat for BlindedPayInfo --- lightning/src/blinded_path/mod.rs | 10 +-- lightning/src/blinded_path/payment.rs | 91 ++++++++++++++++++++++----- 2 files changed, 80 insertions(+), 21 deletions(-) diff --git a/lightning/src/blinded_path/mod.rs b/lightning/src/blinded_path/mod.rs index 4a8f111be..82d50546d 100644 --- a/lightning/src/blinded_path/mod.rs +++ b/lightning/src/blinded_path/mod.rs @@ -76,7 +76,8 @@ impl BlindedPath { }) } - /// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`. + /// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`, where each + /// node is composed of `(node_id, tlvs, htlc_maximum_msat)`. /// /// Errors if: /// * a provided node id is invalid @@ -86,13 +87,14 @@ impl BlindedPath { /// [`ForwardTlvs`]: crate::blinded_path::payment::ForwardTlvs // TODO: make all payloads the same size with padding + add dummy hops pub fn new_for_payment( - intermediate_nodes: &[(PublicKey, payment::ForwardTlvs)], payee_node_id: PublicKey, - payee_tlvs: payment::ReceiveTlvs, entropy_source: &ES, secp_ctx: &Secp256k1 + intermediate_nodes: &[(PublicKey, payment::ForwardTlvs, u64)], payee_node_id: PublicKey, + payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, entropy_source: &ES, + secp_ctx: &Secp256k1 ) -> Result<(BlindedPayInfo, Self), ()> { let blinding_secret_bytes = entropy_source.get_secure_random_bytes(); let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted"); - let blinded_payinfo = payment::compute_payinfo(intermediate_nodes, &payee_tlvs)?; + let blinded_payinfo = payment::compute_payinfo(intermediate_nodes, &payee_tlvs, htlc_maximum_msat)?; Ok((blinded_payinfo, BlindedPath { introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.0), blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret), diff --git a/lightning/src/blinded_path/payment.rs b/lightning/src/blinded_path/payment.rs index 488bdfee6..779b121ca 100644 --- a/lightning/src/blinded_path/payment.rs +++ b/lightning/src/blinded_path/payment.rs @@ -144,12 +144,12 @@ 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: &[(PublicKey, ForwardTlvs, u64)], 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(|(pk, _, _)| pk) .chain(core::iter::once(&payee_node_id)); - let tlvs = intermediate_nodes.iter().map(|(_, tlvs)| BlindedPaymentTlvsRef::Forward(tlvs)) + let tlvs = intermediate_nodes.iter().map(|(_, tlvs, _)| BlindedPaymentTlvsRef::Forward(tlvs)) .chain(core::iter::once(BlindedPaymentTlvsRef::Receive(&payee_tlvs))); utils::construct_blinded_hops(secp_ctx, pks, tlvs, session_priv) } @@ -176,12 +176,13 @@ fn amt_to_forward_msat(inbound_amt_msat: u64, payment_relay: &PaymentRelay) -> O } pub(super) fn compute_payinfo( - intermediate_nodes: &[(PublicKey, ForwardTlvs)], payee_tlvs: &ReceiveTlvs + intermediate_nodes: &[(PublicKey, ForwardTlvs, u64)], payee_tlvs: &ReceiveTlvs, + payee_htlc_maximum_msat: u64 ) -> Result { 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() { + for (_, tlvs, _) in intermediate_nodes.iter().rev() { // 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(()) } @@ -207,7 +208,8 @@ pub(super) fn compute_payinfo( } let mut htlc_minimum_msat: u64 = 1; - for (_, tlvs) in intermediate_nodes.iter() { + let mut htlc_maximum_msat: u64 = 21_000_000 * 100_000_000 * 1_000; // Total bitcoin supply + for (_, tlvs, max_htlc_candidate) 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. @@ -215,17 +217,22 @@ pub(super) fn compute_payinfo( core::cmp::max(tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat), &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(*max_htlc_candidate, htlc_maximum_msat), &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: 21_000_000 * 100_000_000 * 1_000, // TODO + htlc_maximum_msat, features: BlindedHopFeatures::empty(), }) } @@ -265,7 +272,7 @@ mod tests { htlc_minimum_msat: 100, }, features: BlindedHopFeatures::empty(), - }), (dummy_pk, ForwardTlvs { + }, u64::max_value()), (dummy_pk, ForwardTlvs { short_channel_id: 0, payment_relay: PaymentRelay { cltv_expiry_delta: 144, @@ -277,7 +284,7 @@ mod tests { htlc_minimum_msat: 1_000, }, features: BlindedHopFeatures::empty(), - })]; + }, u64::max_value())]; let recv_tlvs = ReceiveTlvs { payment_secret: PaymentSecret([0; 32]), payment_constraints: PaymentConstraints { @@ -285,11 +292,13 @@ mod tests { htlc_minimum_msat: 1, }, }; - let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs).unwrap(); + 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] @@ -301,11 +310,12 @@ mod tests { htlc_minimum_msat: 1, }, }; - let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs).unwrap(); + 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] @@ -325,7 +335,7 @@ mod tests { htlc_minimum_msat: 1, }, features: BlindedHopFeatures::empty(), - }), (dummy_pk, ForwardTlvs { + }, u64::max_value()), (dummy_pk, ForwardTlvs { short_channel_id: 0, payment_relay: PaymentRelay { cltv_expiry_delta: 0, @@ -337,7 +347,7 @@ mod tests { htlc_minimum_msat: 2_000, }, features: BlindedHopFeatures::empty(), - })]; + }, u64::max_value())]; let recv_tlvs = ReceiveTlvs { payment_secret: PaymentSecret([0; 32]), payment_constraints: PaymentConstraints { @@ -345,7 +355,8 @@ mod tests { htlc_minimum_msat: 3, }, }; - let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs).unwrap(); + 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); } @@ -366,7 +377,7 @@ mod tests { htlc_minimum_msat: 5_000, }, features: BlindedHopFeatures::empty(), - }), (dummy_pk, ForwardTlvs { + }, u64::max_value()), (dummy_pk, ForwardTlvs { short_channel_id: 0, payment_relay: PaymentRelay { cltv_expiry_delta: 0, @@ -378,7 +389,7 @@ mod tests { htlc_minimum_msat: 2_000, }, features: BlindedHopFeatures::empty(), - })]; + }, u64::max_value())]; let recv_tlvs = ReceiveTlvs { payment_secret: PaymentSecret([0; 32]), payment_constraints: PaymentConstraints { @@ -387,7 +398,53 @@ mod tests { }, }; let htlc_minimum_msat = 3798; - let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs).unwrap(); + 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![(dummy_pk, 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(), + }, 5_000), (dummy_pk, 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(), + }, 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); } } -- 2.39.5