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Support aggregating htlc_maximum_msat for BlindedPayInfo

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Valentine Wallace 2023-08-19 17:56:33 -04:00
parent 02990cad80
commit fc0d15136e
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2 changed files with 80 additions and 21 deletions
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10
lightning/src/blinded_path/mod.rs
View file

@ -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<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
intermediate_nodes: &[(PublicKey, payment::ForwardTlvs)], payee_node_id: PublicKey,
payee_tlvs: payment::ReceiveTlvs, entropy_source: &ES, secp_ctx: &Secp256k1<T>
intermediate_nodes: &[(PublicKey, payment::ForwardTlvs, u64)], payee_node_id: PublicKey,
payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, entropy_source: &ES,
secp_ctx: &Secp256k1<T>
) -> 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),

91
lightning/src/blinded_path/payment.rs
View file

@ -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<T: secp256k1::Signing + secp256k1::Verification>(
secp_ctx: &Secp256k1<T>, intermediate_nodes: &[(PublicKey, ForwardTlvs)],
secp_ctx: &Secp256k1<T>, intermediate_nodes: &[(PublicKey, ForwardTlvs, u64)],
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(|(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<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() {
// 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);
}
}