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Struct-ify blinded payment path intermediate node info
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@valentinewallace
valentinewallace committed Sep 8, 2023
1 parent 138a5a7 commit f3616e6
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Showing 2 changed files with 149 additions and 107 deletions.
7 changes: 3 additions & 4 deletions lightning/src/blinded_path/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -76,8 +76,7 @@ impl BlindedPath {
})
}

/// 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)`.
/// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`.
///
/// Errors if:
/// * a provided node id is invalid
Expand All @@ -87,7 +86,7 @@ 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<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
intermediate_nodes: &[(PublicKey, payment::ForwardTlvs, u64)], payee_node_id: PublicKey,
intermediate_nodes: &[payment::ForwardNode], payee_node_id: PublicKey,
payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, entropy_source: &ES,
secp_ctx: &Secp256k1<T>
) -> Result<(BlindedPayInfo, Self), ()> {
Expand All @@ -96,7 +95,7 @@ impl BlindedPath {

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),
introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id),
blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
blinded_hops: payment::blinded_hops(
secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret
Expand Down
249 changes: 146 additions & 103 deletions lightning/src/blinded_path/payment.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,18 @@ 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 {
Expand Down Expand Up @@ -150,12 +162,12 @@ impl Readable for BlindedPaymentTlvs {

/// 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, u64)],
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)
}
Expand All @@ -182,13 +194,12 @@ fn amt_to_forward_msat(inbound_amt_msat: u64, payment_relay: &PaymentRelay) -> O
}

pub(super) fn compute_payinfo(
intermediate_nodes: &[(PublicKey, ForwardTlvs, u64)], payee_tlvs: &ReceiveTlvs,
payee_htlc_maximum_msat: u64
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() {
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(()) }
Expand All @@ -215,16 +226,16 @@ pub(super) fn compute_payinfo(

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 (_, tlvs, max_htlc_candidate) in intermediate_nodes.iter() {
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(tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat),
&tlvs.payment_relay
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(*max_htlc_candidate, htlc_maximum_msat), &tlvs.payment_relay
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(
Expand Down Expand Up @@ -257,7 +268,7 @@ impl_writeable_msg!(PaymentConstraints, {
#[cfg(test)]
mod tests {
use bitcoin::secp256k1::PublicKey;
use crate::blinded_path::payment::{ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentRelay};
use crate::blinded_path::payment::{ForwardNode, ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentRelay};
use crate::ln::PaymentSecret;
use crate::ln::features::BlindedHopFeatures;

Expand All @@ -266,31 +277,39 @@ mod tests {
// 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![(dummy_pk, 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,
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(),
},
features: BlindedHopFeatures::empty(),
}, u64::max_value()), (dummy_pk, ForwardTlvs {
short_channel_id: 0,
payment_relay: PaymentRelay {
cltv_expiry_delta: 144,
fee_proportional_millionths: 500,
fee_base_msat: 100,
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(),
},
payment_constraints: PaymentConstraints {
max_cltv_expiry: 0,
htlc_minimum_msat: 1_000,
},
features: BlindedHopFeatures::empty(),
}, u64::max_value())];
htlc_maximum_msat: u64::max_value(),
}];
let recv_tlvs = ReceiveTlvs {
payment_secret: PaymentSecret([0; 32]),
payment_constraints: PaymentConstraints {
Expand Down Expand Up @@ -329,31 +348,39 @@ mod tests {
// 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![(dummy_pk, ForwardTlvs {
short_channel_id: 0,
payment_relay: PaymentRelay {
cltv_expiry_delta: 0,
fee_proportional_millionths: 0,
fee_base_msat: 0,
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(),
},
payment_constraints: PaymentConstraints {
max_cltv_expiry: 0,
htlc_minimum_msat: 1,
},
features: BlindedHopFeatures::empty(),
}, u64::max_value()), (dummy_pk, 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,
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(),
},
features: BlindedHopFeatures::empty(),
}, u64::max_value())];
htlc_maximum_msat: u64::max_value()
}];
let recv_tlvs = ReceiveTlvs {
payment_secret: PaymentSecret([0; 32]),
payment_constraints: PaymentConstraints {
Expand All @@ -371,31 +398,39 @@ mod tests {
// 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![(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: 5_000,
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(),
},
features: BlindedHopFeatures::empty(),
}, u64::max_value()), (dummy_pk, ForwardTlvs {
short_channel_id: 0,
payment_relay: PaymentRelay {
cltv_expiry_delta: 0,
fee_proportional_millionths: 500,
fee_base_msat: 200,
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(),
},
payment_constraints: PaymentConstraints {
max_cltv_expiry: 0,
htlc_minimum_msat: 2_000,
},
features: BlindedHopFeatures::empty(),
}, u64::max_value())];
htlc_maximum_msat: u64::max_value()
}];
let recv_tlvs = ReceiveTlvs {
payment_secret: PaymentSecret([0; 32]),
payment_constraints: PaymentConstraints {
Expand All @@ -417,31 +452,39 @@ mod tests {
// 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,
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(),
},
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,
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(),
},
features: BlindedHopFeatures::empty(),
}, 10_000)];
htlc_maximum_msat: 10_000
}];
let recv_tlvs = ReceiveTlvs {
payment_secret: PaymentSecret([0; 32]),
payment_constraints: PaymentConstraints {
Expand Down

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