-//! Utilities for channelmanager.rs
+//! Utilities to decode payment onions and do contextless validation of incoming payments.
//!
-//! Includes a public [`peel_payment_onion`] function for use by external projects or libraries.
+//! Primarily features [`peel_payment_onion`], which allows the decoding of an onion statelessly
+//! and can be used to predict whether we'd accept a payment.
-use bitcoin::hashes::Hash;
+use bitcoin::hashes::{Hash, HashEngine};
+use bitcoin::hashes::hmac::{Hmac, HmacEngine};
use bitcoin::hashes::sha256::Hash as Sha256;
-use bitcoin::secp256k1::{self, Secp256k1, PublicKey};
+use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1};
+use crate::blinded_path;
+use crate::blinded_path::payment::{PaymentConstraints, PaymentRelay};
use crate::chain::channelmonitor::{HTLC_FAIL_BACK_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS};
use crate::ln::PaymentHash;
-use crate::ln::channelmanager::{CLTV_FAR_FAR_AWAY, HTLCFailureMsg, MIN_CLTV_EXPIRY_DELTA, PendingHTLCInfo, PendingHTLCRouting};
+use crate::ln::channelmanager::{BlindedFailure, BlindedForward, CLTV_FAR_FAR_AWAY, HTLCFailureMsg, MIN_CLTV_EXPIRY_DELTA, PendingHTLCInfo, PendingHTLCRouting};
+use crate::ln::features::BlindedHopFeatures;
use crate::ln::msgs;
use crate::ln::onion_utils;
-use crate::ln::onion_utils::HTLCFailReason;
+use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
use crate::sign::{NodeSigner, Recipient};
use crate::util::logger::Logger;
+#[allow(unused_imports)]
use crate::prelude::*;
+
use core::ops::Deref;
/// Invalid inbound onion payment.
-pub struct InboundOnionErr {
+#[derive(Debug)]
+pub struct InboundHTLCErr {
/// BOLT 4 error code.
pub err_code: u16,
/// Data attached to this error.
pub msg: &'static str,
}
+fn check_blinded_payment_constraints(
+ amt_msat: u64, cltv_expiry: u32, constraints: &PaymentConstraints
+) -> Result<(), ()> {
+ if amt_msat < constraints.htlc_minimum_msat ||
+ cltv_expiry > constraints.max_cltv_expiry
+ { return Err(()) }
+ Ok(())
+}
+
+fn check_blinded_forward(
+ inbound_amt_msat: u64, inbound_cltv_expiry: u32, payment_relay: &PaymentRelay,
+ payment_constraints: &PaymentConstraints, features: &BlindedHopFeatures
+) -> Result<(u64, u32), ()> {
+ let amt_to_forward = blinded_path::payment::amt_to_forward_msat(
+ inbound_amt_msat, payment_relay
+ ).ok_or(())?;
+ let outgoing_cltv_value = inbound_cltv_expiry.checked_sub(
+ payment_relay.cltv_expiry_delta as u32
+ ).ok_or(())?;
+ check_blinded_payment_constraints(inbound_amt_msat, outgoing_cltv_value, payment_constraints)?;
+
+ if features.requires_unknown_bits_from(&BlindedHopFeatures::empty()) { return Err(()) }
+ Ok((amt_to_forward, outgoing_cltv_value))
+}
+
pub(super) fn create_fwd_pending_htlc_info(
msg: &msgs::UpdateAddHTLC, hop_data: msgs::InboundOnionPayload, hop_hmac: [u8; 32],
new_packet_bytes: [u8; onion_utils::ONION_DATA_LEN], shared_secret: [u8; 32],
next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
-) -> Result<PendingHTLCInfo, InboundOnionErr> {
+) -> Result<PendingHTLCInfo, InboundHTLCErr> {
debug_assert!(next_packet_pubkey_opt.is_some());
let outgoing_packet = msgs::OnionPacket {
version: 0,
hmac: hop_hmac,
};
- let (short_channel_id, amt_to_forward, outgoing_cltv_value) = match hop_data {
+ let (
+ short_channel_id, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point
+ ) = match hop_data {
msgs::InboundOnionPayload::Forward { short_channel_id, amt_to_forward, outgoing_cltv_value } =>
- (short_channel_id, amt_to_forward, outgoing_cltv_value),
+ (short_channel_id, amt_to_forward, outgoing_cltv_value, None),
+ msgs::InboundOnionPayload::BlindedForward {
+ short_channel_id, payment_relay, payment_constraints, intro_node_blinding_point, features,
+ } => {
+ let (amt_to_forward, outgoing_cltv_value) = check_blinded_forward(
+ msg.amount_msat, msg.cltv_expiry, &payment_relay, &payment_constraints, &features
+ ).map_err(|()| {
+ // We should be returning malformed here if `msg.blinding_point` is set, but this is
+ // unreachable right now since we checked it in `decode_update_add_htlc_onion`.
+ InboundHTLCErr {
+ msg: "Underflow calculating outbound amount or cltv value for blinded forward",
+ err_code: INVALID_ONION_BLINDING,
+ err_data: vec![0; 32],
+ }
+ })?;
+ (short_channel_id, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point)
+ },
msgs::InboundOnionPayload::Receive { .. } | msgs::InboundOnionPayload::BlindedReceive { .. } =>
- return Err(InboundOnionErr {
+ return Err(InboundHTLCErr {
msg: "Final Node OnionHopData provided for us as an intermediary node",
err_code: 0x4000 | 22,
err_data: Vec::new(),
routing: PendingHTLCRouting::Forward {
onion_packet: outgoing_packet,
short_channel_id,
+ blinded: intro_node_blinding_point.or(msg.blinding_point)
+ .map(|bp| BlindedForward {
+ inbound_blinding_point: bp,
+ failure: intro_node_blinding_point
+ .map(|_| BlindedFailure::FromIntroductionNode)
+ .unwrap_or(BlindedFailure::FromBlindedNode),
+ }),
},
payment_hash: msg.payment_hash,
incoming_shared_secret: shared_secret,
hop_data: msgs::InboundOnionPayload, shared_secret: [u8; 32], payment_hash: PaymentHash,
amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>, allow_underpay: bool,
counterparty_skimmed_fee_msat: Option<u64>, current_height: u32, accept_mpp_keysend: bool,
-) -> Result<PendingHTLCInfo, InboundOnionErr> {
- let (payment_data, keysend_preimage, custom_tlvs, onion_amt_msat, outgoing_cltv_value, payment_metadata) = match hop_data {
+) -> Result<PendingHTLCInfo, InboundHTLCErr> {
+ let (
+ payment_data, keysend_preimage, custom_tlvs, onion_amt_msat, onion_cltv_expiry,
+ payment_metadata, payment_context, requires_blinded_error
+ ) = match hop_data {
msgs::InboundOnionPayload::Receive {
- payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata, ..
+ payment_data, keysend_preimage, custom_tlvs, sender_intended_htlc_amt_msat,
+ cltv_expiry_height, payment_metadata, ..
} =>
- (payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata),
+ (payment_data, keysend_preimage, custom_tlvs, sender_intended_htlc_amt_msat,
+ cltv_expiry_height, payment_metadata, None, false),
msgs::InboundOnionPayload::BlindedReceive {
- amt_msat, total_msat, outgoing_cltv_value, payment_secret, ..
+ sender_intended_htlc_amt_msat, total_msat, cltv_expiry_height, payment_secret,
+ intro_node_blinding_point, payment_constraints, payment_context, keysend_preimage,
+ custom_tlvs
} => {
+ check_blinded_payment_constraints(
+ sender_intended_htlc_amt_msat, cltv_expiry, &payment_constraints
+ )
+ .map_err(|()| {
+ InboundHTLCErr {
+ err_code: INVALID_ONION_BLINDING,
+ err_data: vec![0; 32],
+ msg: "Amount or cltv_expiry violated blinded payment constraints",
+ }
+ })?;
let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
- (Some(payment_data), None, Vec::new(), amt_msat, outgoing_cltv_value, None)
+ (Some(payment_data), keysend_preimage, custom_tlvs,
+ sender_intended_htlc_amt_msat, cltv_expiry_height, None, Some(payment_context),
+ intro_node_blinding_point.is_none())
}
msgs::InboundOnionPayload::Forward { .. } => {
- return Err(InboundOnionErr {
+ return Err(InboundHTLCErr {
err_code: 0x4000|22,
err_data: Vec::new(),
msg: "Got non final data with an HMAC of 0",
})
},
+ msgs::InboundOnionPayload::BlindedForward { .. } => {
+ return Err(InboundHTLCErr {
+ err_code: INVALID_ONION_BLINDING,
+ err_data: vec![0; 32],
+ msg: "Got blinded non final data with an HMAC of 0",
+ })
+ }
};
// final_incorrect_cltv_expiry
- if outgoing_cltv_value > cltv_expiry {
- return Err(InboundOnionErr {
+ if onion_cltv_expiry > cltv_expiry {
+ return Err(InboundHTLCErr {
msg: "Upstream node set CLTV to less than the CLTV set by the sender",
err_code: 18,
err_data: cltv_expiry.to_be_bytes().to_vec()
let mut err_data = Vec::with_capacity(12);
err_data.extend_from_slice(&amt_msat.to_be_bytes());
err_data.extend_from_slice(¤t_height.to_be_bytes());
- return Err(InboundOnionErr {
+ return Err(InboundHTLCErr {
err_code: 0x4000 | 15, err_data,
msg: "The final CLTV expiry is too soon to handle",
});
(allow_underpay && onion_amt_msat >
amt_msat.saturating_add(counterparty_skimmed_fee_msat.unwrap_or(0)))
{
- return Err(InboundOnionErr {
+ return Err(InboundHTLCErr {
err_code: 19,
err_data: amt_msat.to_be_bytes().to_vec(),
msg: "Upstream node sent less than we were supposed to receive in payment",
// time discrepancies due to a hash collision with X.
let hashed_preimage = PaymentHash(Sha256::hash(&payment_preimage.0).to_byte_array());
if hashed_preimage != payment_hash {
- return Err(InboundOnionErr {
+ return Err(InboundHTLCErr {
err_code: 0x4000|22,
err_data: Vec::new(),
msg: "Payment preimage didn't match payment hash",
});
}
if !accept_mpp_keysend && payment_data.is_some() {
- return Err(InboundOnionErr {
+ return Err(InboundHTLCErr {
err_code: 0x4000|22,
err_data: Vec::new(),
msg: "We don't support MPP keysend payments",
payment_data,
payment_preimage,
payment_metadata,
- incoming_cltv_expiry: outgoing_cltv_value,
+ incoming_cltv_expiry: onion_cltv_expiry,
custom_tlvs,
+ requires_blinded_error,
}
} else if let Some(data) = payment_data {
PendingHTLCRouting::Receive {
payment_data: data,
payment_metadata,
- incoming_cltv_expiry: outgoing_cltv_value,
+ payment_context,
+ incoming_cltv_expiry: onion_cltv_expiry,
phantom_shared_secret,
custom_tlvs,
+ requires_blinded_error,
}
} else {
- return Err(InboundOnionErr {
+ return Err(InboundHTLCErr {
err_code: 0x4000|0x2000|3,
err_data: Vec::new(),
msg: "We require payment_secrets",
incoming_shared_secret: shared_secret,
incoming_amt_msat: Some(amt_msat),
outgoing_amt_msat: onion_amt_msat,
- outgoing_cltv_value,
+ outgoing_cltv_value: onion_cltv_expiry,
skimmed_fee_msat: counterparty_skimmed_fee_msat,
})
}
-/// Peel one layer off an incoming onion, returning [`PendingHTLCInfo`] (either Forward or Receive).
+/// Peel one layer off an incoming onion, returning a [`PendingHTLCInfo`] that contains information
+/// about the intended next-hop for the HTLC.
+///
/// This does all the relevant context-free checks that LDK requires for payment relay or
/// acceptance. If the payment is to be received, and the amount matches the expected amount for
/// a given invoice, this indicates the [`msgs::UpdateAddHTLC`], once fully committed in the
/// [`Event::PaymentClaimable`]: crate::events::Event::PaymentClaimable
pub fn peel_payment_onion<NS: Deref, L: Deref, T: secp256k1::Verification>(
msg: &msgs::UpdateAddHTLC, node_signer: &NS, logger: &L, secp_ctx: &Secp256k1<T>,
- cur_height: u32, accept_mpp_keysend: bool,
-) -> Result<PendingHTLCInfo, InboundOnionErr>
+ cur_height: u32, accept_mpp_keysend: bool, allow_skimmed_fees: bool,
+) -> Result<PendingHTLCInfo, InboundHTLCErr>
where
NS::Target: NodeSigner,
L::Target: Logger,
HTLCFailureMsg::Relay(r) => (0x4000 | 22, r.reason.data),
};
let msg = "Failed to decode update add htlc onion";
- InboundOnionErr { msg, err_code, err_data }
+ InboundHTLCErr { msg, err_code, err_data }
})?;
Ok(match hop {
onion_utils::Hop::Forward { next_hop_data, next_hop_hmac, new_packet_bytes } => {
} = match next_packet_details_opt {
Some(next_packet_details) => next_packet_details,
// Forward should always include the next hop details
- None => return Err(InboundOnionErr {
+ None => return Err(InboundHTLCErr {
msg: "Failed to decode update add htlc onion",
err_code: 0x4000 | 22,
err_data: Vec::new(),
if let Err((err_msg, code)) = check_incoming_htlc_cltv(
cur_height, outgoing_cltv_value, msg.cltv_expiry
) {
- return Err(InboundOnionErr {
+ return Err(InboundHTLCErr {
msg: err_msg,
err_code: code,
err_data: Vec::new(),
});
}
+
+ // TODO: If this is potentially a phantom payment we should decode the phantom payment
+ // onion here and check it.
+
create_fwd_pending_htlc_info(
msg, next_hop_data, next_hop_hmac, new_packet_bytes, shared_secret,
Some(next_packet_pubkey)
onion_utils::Hop::Receive(received_data) => {
create_recv_pending_htlc_info(
received_data, shared_secret, msg.payment_hash, msg.amount_msat, msg.cltv_expiry,
- None, false, msg.skimmed_fee_msat, cur_height, accept_mpp_keysend,
+ None, allow_skimmed_fees, msg.skimmed_fee_msat, cur_height, accept_mpp_keysend,
)?
}
})
($msg: expr, $err_code: expr) => {
{
log_info!(logger, "Failed to accept/forward incoming HTLC: {}", $msg);
+ let (sha256_of_onion, failure_code) = if msg.blinding_point.is_some() {
+ ([0; 32], INVALID_ONION_BLINDING)
+ } else {
+ (Sha256::hash(&msg.onion_routing_packet.hop_data).to_byte_array(), $err_code)
+ };
return Err(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
channel_id: msg.channel_id,
htlc_id: msg.htlc_id,
- sha256_of_onion: Sha256::hash(&msg.onion_routing_packet.hop_data).to_byte_array(),
- failure_code: $err_code,
+ sha256_of_onion,
+ failure_code,
}));
}
}
return_malformed_err!("invalid ephemeral pubkey", 0x8000 | 0x4000 | 6);
}
+ let blinded_node_id_tweak = msg.blinding_point.map(|bp| {
+ let blinded_tlvs_ss = node_signer.ecdh(Recipient::Node, &bp, None).unwrap().secret_bytes();
+ let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
+ hmac.input(blinded_tlvs_ss.as_ref());
+ Scalar::from_be_bytes(Hmac::from_engine(hmac).to_byte_array()).unwrap()
+ });
let shared_secret = node_signer.ecdh(
- Recipient::Node, &msg.onion_routing_packet.public_key.unwrap(), None
+ Recipient::Node, &msg.onion_routing_packet.public_key.unwrap(), blinded_node_id_tweak.as_ref()
).unwrap().secret_bytes();
if msg.onion_routing_packet.version != 0 {
macro_rules! return_err {
($msg: expr, $err_code: expr, $data: expr) => {
{
+ if msg.blinding_point.is_some() {
+ return_malformed_err!($msg, INVALID_ONION_BLINDING)
+ }
+
log_info!(logger, "Failed to accept/forward incoming HTLC: {}", $msg);
return Err(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
channel_id: msg.channel_id,
let next_hop = match onion_utils::decode_next_payment_hop(
shared_secret, &msg.onion_routing_packet.hop_data[..], msg.onion_routing_packet.hmac,
- msg.payment_hash, node_signer
+ msg.payment_hash, msg.blinding_point, node_signer
) {
Ok(res) => res,
Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
outgoing_amt_msat: amt_to_forward, outgoing_cltv_value
}
},
+ onion_utils::Hop::Forward {
+ next_hop_data: msgs::InboundOnionPayload::BlindedForward {
+ short_channel_id, ref payment_relay, ref payment_constraints, ref features, ..
+ }, ..
+ } => {
+ let (amt_to_forward, outgoing_cltv_value) = match check_blinded_forward(
+ msg.amount_msat, msg.cltv_expiry, &payment_relay, &payment_constraints, &features
+ ) {
+ Ok((amt, cltv)) => (amt, cltv),
+ Err(()) => {
+ return_err!("Underflow calculating outbound amount or cltv value for blinded forward",
+ INVALID_ONION_BLINDING, &[0; 32]);
+ }
+ };
+ let next_packet_pubkey = onion_utils::next_hop_pubkey(&secp_ctx,
+ msg.onion_routing_packet.public_key.unwrap(), &shared_secret);
+ NextPacketDetails {
+ next_packet_pubkey, outgoing_scid: short_channel_id, outgoing_amt_msat: amt_to_forward,
+ outgoing_cltv_value
+ }
+ },
onion_utils::Hop::Receive { .. } => return Ok((next_hop, shared_secret, None)),
onion_utils::Hop::Forward { next_hop_data: msgs::InboundOnionPayload::Receive { .. }, .. } |
onion_utils::Hop::Forward { next_hop_data: msgs::InboundOnionPayload::BlindedReceive { .. }, .. } =>
mod tests {
use bitcoin::hashes::Hash;
use bitcoin::hashes::sha256::Hash as Sha256;
- use bitcoin::secp256k1::{PublicKey, SecretKey};
+ use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
use crate::ln::ChannelId;
use crate::ln::channelmanager::RecipientOnionFields;
use crate::routing::router::{Path, RouteHop};
use crate::util::test_utils;
+ #[test]
+ fn fail_construct_onion_on_too_big_payloads() {
+ // Ensure that if we call `construct_onion_packet` and friends where payloads are too large for
+ // the allotted packet length, we'll fail to construct. Previously, senders would happily
+ // construct invalid packets by array-shifting the final node's HMAC out of the packet when
+ // adding an intermediate onion layer, causing the receiver to error with "final payload
+ // provided for us as an intermediate node."
+ let secp_ctx = Secp256k1::new();
+ let bob = crate::sign::KeysManager::new(&[2; 32], 42, 42);
+ let bob_pk = PublicKey::from_secret_key(&secp_ctx, &bob.get_node_secret_key());
+ let charlie = crate::sign::KeysManager::new(&[3; 32], 42, 42);
+ let charlie_pk = PublicKey::from_secret_key(&secp_ctx, &charlie.get_node_secret_key());
+
+ let (
+ session_priv, total_amt_msat, cur_height, mut recipient_onion, keysend_preimage, payment_hash,
+ prng_seed, hops, ..
+ ) = payment_onion_args(bob_pk, charlie_pk);
+
+ // Ensure the onion will not fit all the payloads by adding a large custom TLV.
+ recipient_onion.custom_tlvs.push((13377331, vec![0; 1156]));
+
+ let path = Path { hops, blinded_tail: None, };
+ let onion_keys = super::onion_utils::construct_onion_keys(&secp_ctx, &path, &session_priv).unwrap();
+ let (onion_payloads, ..) = super::onion_utils::build_onion_payloads(
+ &path, total_amt_msat, recipient_onion, cur_height + 1, &Some(keysend_preimage)
+ ).unwrap();
+
+ assert!(super::onion_utils::construct_onion_packet(
+ onion_payloads, onion_keys, prng_seed, &payment_hash
+ ).is_err());
+ }
+
#[test]
fn test_peel_payment_onion() {
use super::*;
let msg = make_update_add_msg(amount_msat, cltv_expiry, payment_hash, onion);
let logger = test_utils::TestLogger::with_id("bob".to_string());
- let peeled = peel_payment_onion(&msg, &&bob, &&logger, &secp_ctx, cur_height, true)
+ let peeled = peel_payment_onion(&msg, &&bob, &&logger, &secp_ctx, cur_height, true, false)
.map_err(|e| e.msg).unwrap();
let next_onion = match peeled.routing {
- PendingHTLCRouting::Forward { onion_packet, short_channel_id: _ } => {
+ PendingHTLCRouting::Forward { onion_packet, .. } => {
onion_packet
},
_ => panic!("expected a forwarded onion"),
};
let msg2 = make_update_add_msg(amount_msat, cltv_expiry, payment_hash, next_onion);
- let peeled2 = peel_payment_onion(&msg2, &&charlie, &&logger, &secp_ctx, cur_height, true)
+ let peeled2 = peel_payment_onion(&msg2, &&charlie, &&logger, &secp_ctx, cur_height, true, false)
.map_err(|e| e.msg).unwrap();
match peeled2.routing {
projects / rust-lightning / blobdiff