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arik-so wants to merge 4 commits into from
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WIP: Decrypt inbound Trampoline onions #3585

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5cc6bb1
Add TrampolineForward variant to PendingHTLCRouting
arik-so Feb 10, 2025
51cecfc
Introduce HopConnector enum
arik-so Feb 3, 2025
0e61db7
Parse inbound TrampolineEntrypoint payload
arik-so Feb 10, 2025
63608c2
Decrypt inbound Trampoline packets
arik-so Feb 10, 2025
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65 changes: 54 additions & 11 deletions lightning/src/ln/channelmanager.rs
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Original file line numberDiff line numberDiff line change
Expand Up@@ -56,7 +56,7 @@ use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelType
#[cfg(any(feature = "_test_utils", test))]
use crate::types::features::Bolt11InvoiceFeatures;
use crate::routing::router::{BlindedTail, FixedRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails, HopConnector};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
Expand DownExpand Up@@ -131,7 +131,7 @@ pub use crate::ln::outbound_payment::{Bolt12PaymentError, ProbeSendFailure, Retr
#[cfg(test)]
pub(crate) use crate::ln::outbound_payment::PaymentSendFailure;
use crate::ln::script::ShutdownScript;

use crate::routing::gossip::NodeId;
// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
Expand DownExpand Up@@ -169,6 +169,25 @@ pub enum PendingHTLCRouting {
/// The absolute CLTV of the inbound HTLC
incoming_cltv_expiry: Option<u32>,
},

/// An HTLC which should be forwarded on to another Trampoline node.
TrampolineForward {
/// The onion shared secret we build with the sender (or the preceding Trampoline node) used
/// to decrypt the onion.
///
/// This is later used to encrypt failure packets in the event that the HTLC is failed.
incoming_shared_secret: [u8; 32],
/// The onion which should be included in the forwarded HTLC, telling the next hop what to
/// do with the HTLC.
onion_packet: msgs::TrampolineOnionPacket,
/// The node ID of the Trampoline node which we need to route this HTLC to.
node_id: NodeId, // This should be NonZero<u64> eventually when we bump MSRV
/// Set if this HTLC is being forwarded within a blinded path.
blinded: Option<BlindedForward>,
/// The absolute CLTV of the inbound HTLC
incoming_cltv_expiry: Option<u32>,
},

/// The onion indicates that this is a payment for an invoice (supposedly) generated by us.
///
/// Note that at this point, we have not checked that the invoice being paid was actually
Expand DownExpand Up@@ -279,6 +298,7 @@ impl PendingHTLCRouting {
fn incoming_cltv_expiry(&self) -> Option<u32> {
match self {
Self::Forward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
Self::TrampolineForward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
Self::Receive { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
Self::ReceiveKeysend { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
}
Expand DownExpand Up@@ -4242,11 +4262,15 @@ where
// we don't allow forwards outbound over them.
return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10));
}
if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
// `option_scid_alias` (referred to in LDK as `scid_privacy`) means
// "refuse to forward unless the SCID alias was used", so we pretend
// we don't have the channel here.
return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
// `option_scid_alias` (referred to in LDK as `scid_privacy`) means
// "refuse to forward unless the SCID alias was used", so we pretend
// we don't have the channel here.
return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
}
} else {
return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
}

// Note that we could technically not return an error yet here and just hope
Expand DownExpand Up@@ -4298,7 +4322,13 @@ where
fn can_forward_htlc(
&self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
) -> Result<(), (&'static str, u16)> {
match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut FundedChannel<SP>| {
let outgoing_scid = match next_packet_details.outgoing_connector {
HopConnector::ShortChannelId(scid) => scid,
HopConnector::Trampoline { .. } => {
return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
}
};
match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
}) {
Some(Ok(())) => {},
Expand All@@ -4307,8 +4337,8 @@ where
// If we couldn't find the channel info for the scid, it may be a phantom or
// intercept forward.
if (self.default_configuration.accept_intercept_htlcs &&
fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
{} else {
return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10));
}
Expand DownExpand Up@@ -5660,7 +5690,12 @@ where
};

let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
let outgoing_scid_opt = next_packet_details_opt.as_ref().and_then(|d| {
match d.outgoing_connector {
HopConnector::ShortChannelId(scid) => { Some(scid) }
HopConnector::Trampoline { .. } => { None }
}
});

// Process the HTLC on the incoming channel.
match self.do_funded_channel_callback(incoming_scid, |chan: &mut FundedChannel<SP>| {
Expand DownExpand Up@@ -8909,6 +8944,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
let scid = match forward_info.routing {
PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
PendingHTLCRouting::TrampolineForward { .. } => 0,
PendingHTLCRouting::Receive { .. } => 0,
PendingHTLCRouting::ReceiveKeysend { .. } => 0,
};
Expand DownExpand Up@@ -12476,6 +12512,13 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
(9, payment_context, option),
(11, invoice_request, option),
},
(3, TrampolineForward) => {
(0, incoming_shared_secret, required),
(1, onion_packet, required),
(2, blinded, option),
(3, node_id, required),
(4, incoming_cltv_expiry, option),
}
);

impl_writeable_tlv_based!(PendingHTLCInfo, {
Expand Down
157 changes: 157 additions & 0 deletions lightning/src/ln/msgs.rs
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Original file line numberDiff line numberDiff line change
Expand Up@@ -1775,6 +1775,13 @@ mod fuzzy_internal_msgs {
amt_to_forward: u64,
outgoing_cltv_value: u32,
},
#[allow(unused)]
TrampolineEntrypoint {
amt_to_forward: u64,
outgoing_cltv_value: u32,
multipath_trampoline_data: Option<FinalOnionHopData>,
trampoline_packet: TrampolineOnionPacket,
},
Receive {
payment_data: Option<FinalOnionHopData>,
payment_metadata: Option<Vec<u8>>,
Expand DownExpand Up@@ -1805,6 +1812,36 @@ mod fuzzy_internal_msgs {
}
}

#[allow(unused)]
pub enum InboundTrampolinePayload {
Forward {
/// The value, in msat, of the payment after this hop's fee is deducted.
amt_to_forward: u64,
outgoing_cltv_value: u32,
/// The node id to which the trampoline node must find a route.
outgoing_node_id: PublicKey,
},
BlindedForward {
short_channel_id: u64,
payment_relay: PaymentRelay,
payment_constraints: PaymentConstraints,
features: BlindedHopFeatures,
intro_node_blinding_point: Option<PublicKey>,
next_blinding_override: Option<PublicKey>,
},
BlindedReceive {
sender_intended_htlc_amt_msat: u64,
total_msat: u64,
cltv_expiry_height: u32,
payment_secret: PaymentSecret,
payment_constraints: PaymentConstraints,
payment_context: PaymentContext,
intro_node_blinding_point: Option<PublicKey>,
keysend_preimage: Option<PaymentPreimage>,
custom_tlvs: Vec<(u64, Vec<u8>)>,
}
}

pub(crate) enum OutboundOnionPayload<'a> {
Forward {
short_channel_id: u64,
Expand DownExpand Up@@ -2858,6 +2895,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
let mut total_msat = None;
let mut keysend_preimage: Option<PaymentPreimage> = None;
let mut trampoline_onion_packet: Option<TrampolineOnionPacket> = None;
let mut invoice_request: Option<InvoiceRequest> = None;
let mut custom_tlvs = Vec::new();

Expand All@@ -2872,6 +2910,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
(12, intro_node_blinding_point, option),
(16, payment_metadata, option),
(18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
(20, trampoline_onion_packet, option),
(77_777, invoice_request, option),
// See https://github.com/lightning/blips/blob/master/blip-0003.md
(5482373484, keysend_preimage, option)
Expand DownExpand Up@@ -2950,6 +2989,16 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
})
} else if let Some(trampoline_onion_packet) = trampoline_onion_packet {
if payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
total_msat.is_some()
{ return Err(DecodeError::InvalidValue) }
Ok(Self::TrampolineEntrypoint {
amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
multipath_trampoline_data: payment_data,
trampoline_packet: trampoline_onion_packet,
})
} else {
if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
return Err(DecodeError::InvalidValue)
Expand All@@ -2971,6 +3020,114 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
}
}

impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundTrampolinePayload where NS::Target: NodeSigner {
fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, NS)) -> Result<Self, DecodeError> {
let (update_add_blinding_point, node_signer) = args;

let mut amt = None;
let mut cltv_value = None;
let mut payment_data: Option<FinalOnionHopData> = None;
let mut encrypted_tlvs_opt: Option<WithoutLength<Vec<u8>>> = None;
let mut intro_node_blinding_point = None;
let mut outgoing_node_id: Option<PublicKey> = None;
let mut total_msat = None;
let mut keysend_preimage: Option<PaymentPreimage> = None;
let mut custom_tlvs = Vec::new();

let tlv_len = <BigSize as Readable>::read(r)?;
let mut rd = FixedLengthReader::new(r, tlv_len.0);
decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
(2, amt, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
(4, cltv_value, (option, encoding: (u32, HighZeroBytesDroppedBigSize))),
(8, payment_data, option),
(10, encrypted_tlvs_opt, option),
(12, intro_node_blinding_point, option),
(14, outgoing_node_id, option),
(18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
// See https://github.com/lightning/blips/blob/master/blip-0003.md
(5482373484, keysend_preimage, option)
}, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
if msg_type < 1 << 16 { return Ok(false) }
let mut value = Vec::new();
msg_reader.read_to_limit(&mut value, u64::MAX)?;
custom_tlvs.push((msg_type, value));
Ok(true)
});

if amt.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
if intro_node_blinding_point.is_some() && update_add_blinding_point.is_some() {
return Err(DecodeError::InvalidValue)
}

if let Some(blinding_point) = intro_node_blinding_point.or(update_add_blinding_point) {
if payment_data.is_some() {
return Err(DecodeError::InvalidValue)
}
let enc_tlvs = encrypted_tlvs_opt.ok_or(DecodeError::InvalidValue)?.0;
let enc_tlvs_ss = node_signer.ecdh(Recipient::Node, &blinding_point, None)
.map_err(|_| DecodeError::InvalidValue)?;
let rho = onion_utils::gen_rho_from_shared_secret(&enc_tlvs_ss.secret_bytes());
let mut s = Cursor::new(&enc_tlvs);
let mut reader = FixedLengthReader::new(&mut s, enc_tlvs.len() as u64);
match ChaChaPolyReadAdapter::read(&mut reader, rho)? {
ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Forward(ForwardTlvs {
short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
})} => {
if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
keysend_preimage.is_some()
{
return Err(DecodeError::InvalidValue)
}
Ok(Self::BlindedForward {
short_channel_id,
payment_relay,
payment_constraints,
features,
intro_node_blinding_point,
next_blinding_override,
})
},
ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
let expanded_key = node_signer.get_inbound_payment_key();
if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
return Err(DecodeError::InvalidValue);
}

let UnauthenticatedReceiveTlvs {
payment_secret, payment_constraints, payment_context,
} = tlvs;
if total_msat.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
Ok(Self::BlindedReceive {
sender_intended_htlc_amt_msat: amt.ok_or(DecodeError::InvalidValue)?,
total_msat: total_msat.ok_or(DecodeError::InvalidValue)?,
cltv_expiry_height: cltv_value.ok_or(DecodeError::InvalidValue)?,
payment_secret,
payment_constraints,
payment_context,
intro_node_blinding_point,
keysend_preimage,
custom_tlvs,
})
},
}
} else if let Some(outgoing_node_id) = outgoing_node_id {
if payment_data.is_some() || encrypted_tlvs_opt.is_some() ||
total_msat.is_some()
{ return Err(DecodeError::InvalidValue) }
Ok(Self::Forward {
outgoing_node_id,
amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
})
} else {
// unblinded Trampoline receives are not supported
return Err(DecodeError::InvalidValue);
}
}
}


impl Writeable for Ping {
fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
self.ponglen.write(w)?;
Expand Down
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WIP: Decrypt inbound Trampoline onions by arik-so · Pull Request #3585 · lightningdevkit/rust-lightning · GitHub
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WIP: Decrypt inbound Trampoline onions#3585

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arik-so
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WIP: Decrypt inbound Trampoline onions
#3585
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5cc6bb1

Add TrampolineForward variant to PendingHTLCRouting


arik-so Feb 10, 2025
51cecfc

Introduce HopConnector enum


arik-so Feb 3, 2025
0e61db7

Parse inbound TrampolineEntrypoint payload


arik-so Feb 10, 2025
63608c2

Decrypt inbound Trampoline packets


arik-so Feb 10, 2025

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65 changes: 54 additions & 11 deletions
lightning/src/ln/channelmanager.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -56,7 +56,7 @@ use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelType
#[cfg(any(feature = "_test_utils", test))]
use crate::types::features::Bolt11InvoiceFeatures;
use crate::routing::router::{BlindedTail, FixedRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails, HopConnector};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
Expand DownExpand Up@@ -131,7 +131,7 @@ pub use crate::ln::outbound_payment::{Bolt12PaymentError, ProbeSendFailure, Retr
#[cfg(test)]
pub(crate) use crate::ln::outbound_payment::PaymentSendFailure;
use crate::ln::script::ShutdownScript;

use crate::routing::gossip::NodeId;
// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
Expand DownExpand Up@@ -169,6 +169,25 @@ pub enum PendingHTLCRouting {
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// An HTLC which should be forwarded on to another Trampoline node.
	TrampolineForward {
 /// The onion shared secret we build with the sender (or the preceding Trampoline node) used
 /// to decrypt the onion.
 ///
 /// This is later used to encrypt failure packets in the event that the HTLC is failed.
 incoming_shared_secret: [u8; 32],
 /// The onion which should be included in the forwarded HTLC, telling the next hop what to
 /// do with the HTLC.
 onion_packet: msgs::TrampolineOnionPacket,
 /// The node ID of the Trampoline node which we need to route this HTLC to.
 node_id: NodeId, // This should be NonZero<u64> eventually when we bump MSRV
 /// Set if this HTLC is being forwarded within a blinded path.
 blinded: Option<BlindedForward>,
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// The onion indicates that this is a payment for an invoice (supposedly) generated by us.
	///
	/// Note that at this point, we have not checked that the invoice being paid was actually
Expand DownExpand Up@@ -279,6 +298,7 @@ impl PendingHTLCRouting {
	fn incoming_cltv_expiry(&self) -> Option<u32> {
 match self {
 Self::Forward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::TrampolineForward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::Receive { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 Self::ReceiveKeysend { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 }
Expand DownExpand Up@@ -4242,11 +4262,15 @@ where
 // we don't allow forwards outbound over them.
 return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10));
 }
 if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
 if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 }
 } else {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }

 // Note that we could technically not return an error yet here and just hope
Expand DownExpand Up@@ -4298,7 +4322,13 @@ where
	fn can_forward_htlc(
 &self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
	) -> Result<(), (&'static str, u16)> {
 match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut FundedChannel<SP>| {
 let outgoing_scid = match next_packet_details.outgoing_connector {
 HopConnector::ShortChannelId(scid) => scid,
 HopConnector::Trampoline { .. } => {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }
 };
 match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
 self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
 }) {
 Some(Ok(())) => {},
Expand All@@ -4307,8 +4337,8 @@ where
 // If we couldn't find the channel info for the scid, it may be a phantom or
 // intercept forward.
 if (self.default_configuration.accept_intercept_htlcs &&
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
 {} else {
 return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10));
 }
Expand DownExpand Up@@ -5660,7 +5690,12 @@ where
 };

 let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
 let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
 let outgoing_scid_opt = next_packet_details_opt.as_ref().and_then(|d| {
 match d.outgoing_connector {
 HopConnector::ShortChannelId(scid) => { Some(scid) }
 HopConnector::Trampoline { .. } => { None }
 }
 });

 // Process the HTLC on the incoming channel.
 match self.do_funded_channel_callback(incoming_scid, |chan: &mut FundedChannel<SP>| {
Expand DownExpand Up@@ -8909,6 +8944,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
 let scid = match forward_info.routing {
 PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
 PendingHTLCRouting::TrampolineForward { .. } => 0,
 PendingHTLCRouting::Receive { .. } => 0,
 PendingHTLCRouting::ReceiveKeysend { .. } => 0,
 };
Expand DownExpand Up@@ -12476,6 +12512,13 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 (9, payment_context, option),
 (11, invoice_request, option),
	},
	(3, TrampolineForward) => {
 (0, incoming_shared_secret, required),
 (1, onion_packet, required),
 (2, blinded, option),
 (3, node_id, required),
 (4, incoming_cltv_expiry, option),
	}
);

impl_writeable_tlv_based!(PendingHTLCInfo, {
Expand Down

157 changes: 157 additions & 0 deletions
lightning/src/ln/msgs.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1775,6 +1775,13 @@ mod fuzzy_internal_msgs {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 },
 #[allow(unused)]
 TrampolineEntrypoint {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 multipath_trampoline_data: Option<FinalOnionHopData>,
 trampoline_packet: TrampolineOnionPacket,
 },
 Receive {
 payment_data: Option<FinalOnionHopData>,
 payment_metadata: Option<Vec<u8>>,
Expand DownExpand Up@@ -1805,6 +1812,36 @@ mod fuzzy_internal_msgs {
 }
	}

	#[allow(unused)]
	pub enum InboundTrampolinePayload {
 Forward {
 /// The value, in msat, of the payment after this hop's fee is deducted.
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 /// The node id to which the trampoline node must find a route.
 outgoing_node_id: PublicKey,
 },
 BlindedForward {
 short_channel_id: u64,
 payment_relay: PaymentRelay,
 payment_constraints: PaymentConstraints,
 features: BlindedHopFeatures,
 intro_node_blinding_point: Option<PublicKey>,
 next_blinding_override: Option<PublicKey>,
 },
 BlindedReceive {
 sender_intended_htlc_amt_msat: u64,
 total_msat: u64,
 cltv_expiry_height: u32,
 payment_secret: PaymentSecret,
 payment_constraints: PaymentConstraints,
 payment_context: PaymentContext,
 intro_node_blinding_point: Option<PublicKey>,
 keysend_preimage: Option<PaymentPreimage>,
 custom_tlvs: Vec<(u64, Vec<u8>)>,
 }
	}

	pub(crate) enum OutboundOnionPayload<'a> {
 Forward {
 short_channel_id: u64,
Expand DownExpand Up@@ -2858,6 +2895,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut trampoline_onion_packet: Option<TrampolineOnionPacket> = None;
 let mut invoice_request: Option<InvoiceRequest> = None;
 let mut custom_tlvs = Vec::new();

Expand All@@ -2872,6 +2910,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 (12, intro_node_blinding_point, option),
 (16, payment_metadata, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (20, trampoline_onion_packet, option),
 (77_777, invoice_request, option),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
Expand DownExpand Up@@ -2950,6 +2989,16 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else if let Some(trampoline_onion_packet) = trampoline_onion_packet {
 if payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::TrampolineEntrypoint {
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 multipath_trampoline_data: payment_data,
 trampoline_packet: trampoline_onion_packet,
 })
 } else {
 if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
 return Err(DecodeError::InvalidValue)
Expand All@@ -2971,6 +3020,114 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
	}
}

impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundTrampolinePayload where NS::Target: NodeSigner {
	fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, NS)) -> Result<Self, DecodeError> {
 let (update_add_blinding_point, node_signer) = args;

 let mut amt = None;
 let mut cltv_value = None;
 let mut payment_data: Option<FinalOnionHopData> = None;
 let mut encrypted_tlvs_opt: Option<WithoutLength<Vec<u8>>> = None;
 let mut intro_node_blinding_point = None;
 let mut outgoing_node_id: Option<PublicKey> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut custom_tlvs = Vec::new();

 let tlv_len = <BigSize as Readable>::read(r)?;
 let mut rd = FixedLengthReader::new(r, tlv_len.0);
 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 (2, amt, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (4, cltv_value, (option, encoding: (u32, HighZeroBytesDroppedBigSize))),
 (8, payment_data, option),
 (10, encrypted_tlvs_opt, option),
 (12, intro_node_blinding_point, option),
 (14, outgoing_node_id, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
 }, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
 if msg_type < 1 << 16 { return Ok(false) }
 let mut value = Vec::new();
 msg_reader.read_to_limit(&mut value, u64::MAX)?;
 custom_tlvs.push((msg_type, value));
 Ok(true)
 });

 if amt.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 if intro_node_blinding_point.is_some() && update_add_blinding_point.is_some() {
 return Err(DecodeError::InvalidValue)
 }

 if let Some(blinding_point) = intro_node_blinding_point.or(update_add_blinding_point) {
 if payment_data.is_some() {
 return Err(DecodeError::InvalidValue)
 }
 let enc_tlvs = encrypted_tlvs_opt.ok_or(DecodeError::InvalidValue)?.0;
 let enc_tlvs_ss = node_signer.ecdh(Recipient::Node, &blinding_point, None)
 .map_err(|_| DecodeError::InvalidValue)?;
 let rho = onion_utils::gen_rho_from_shared_secret(&enc_tlvs_ss.secret_bytes());
 let mut s = Cursor::new(&enc_tlvs);
 let mut reader = FixedLengthReader::new(&mut s, enc_tlvs.len() as u64);
 match ChaChaPolyReadAdapter::read(&mut reader, rho)? {
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Forward(ForwardTlvs {
 short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
 })} => {
 if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
 keysend_preimage.is_some()
 {
 return Err(DecodeError::InvalidValue)
 }
 Ok(Self::BlindedForward {
 short_channel_id,
 payment_relay,
 payment_constraints,
 features,
 intro_node_blinding_point,
 next_blinding_override,
 })
 },
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
 let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
 let expanded_key = node_signer.get_inbound_payment_key();
 if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
 return Err(DecodeError::InvalidValue);
 }

 let UnauthenticatedReceiveTlvs {
 payment_secret, payment_constraints, payment_context,
 } = tlvs;
 if total_msat.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 Ok(Self::BlindedReceive {
 sender_intended_htlc_amt_msat: amt.ok_or(DecodeError::InvalidValue)?,
 total_msat: total_msat.ok_or(DecodeError::InvalidValue)?,
 cltv_expiry_height: cltv_value.ok_or(DecodeError::InvalidValue)?,
 payment_secret,
 payment_constraints,
 payment_context,
 intro_node_blinding_point,
 keysend_preimage,
 custom_tlvs,
 })
 },
 }
 } else if let Some(outgoing_node_id) = outgoing_node_id {
 if payment_data.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::Forward {
 outgoing_node_id,
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else {
 // unblinded Trampoline receives are not supported
 return Err(DecodeError::InvalidValue);
 }
	}
}


impl Writeable for Ping {
	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 self.ponglen.write(w)?;
Expand Down
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WIP: Decrypt inbound Trampoline onions by arik-so · Pull Request #3585 · lightningdevkit/rust-lightning · GitHub
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WIP: Decrypt inbound Trampoline onions
#3585
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5cc6bb1

Add TrampolineForward variant to PendingHTLCRouting


arik-so Feb 10, 2025
51cecfc

Introduce HopConnector enum


arik-so Feb 3, 2025
0e61db7

Parse inbound TrampolineEntrypoint payload


arik-so Feb 10, 2025
63608c2

Decrypt inbound Trampoline packets


arik-so Feb 10, 2025

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65 changes: 54 additions & 11 deletions
lightning/src/ln/channelmanager.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,7 +56,7 @@ use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelType
#[cfg(any(feature = "_test_utils", test))]
use crate::types::features::Bolt11InvoiceFeatures;
use crate::routing::router::{BlindedTail, FixedRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails, HopConnector};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
Expand DownExpand Up@@ -131,7 +131,7 @@ pub use crate::ln::outbound_payment::{Bolt12PaymentError, ProbeSendFailure, Retr
#[cfg(test)]
pub(crate) use crate::ln::outbound_payment::PaymentSendFailure;
use crate::ln::script::ShutdownScript;

use crate::routing::gossip::NodeId;
// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
Expand DownExpand Up@@ -169,6 +169,25 @@ pub enum PendingHTLCRouting {
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// An HTLC which should be forwarded on to another Trampoline node.
	TrampolineForward {
 /// The onion shared secret we build with the sender (or the preceding Trampoline node) used
 /// to decrypt the onion.
 ///
 /// This is later used to encrypt failure packets in the event that the HTLC is failed.
 incoming_shared_secret: [u8; 32],
 /// The onion which should be included in the forwarded HTLC, telling the next hop what to
 /// do with the HTLC.
 onion_packet: msgs::TrampolineOnionPacket,
 /// The node ID of the Trampoline node which we need to route this HTLC to.
 node_id: NodeId, // This should be NonZero<u64> eventually when we bump MSRV
 /// Set if this HTLC is being forwarded within a blinded path.
 blinded: Option<BlindedForward>,
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// The onion indicates that this is a payment for an invoice (supposedly) generated by us.
	///
	/// Note that at this point, we have not checked that the invoice being paid was actually
Expand DownExpand Up@@ -279,6 +298,7 @@ impl PendingHTLCRouting {
	fn incoming_cltv_expiry(&self) -> Option<u32> {
 match self {
 Self::Forward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::TrampolineForward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::Receive { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 Self::ReceiveKeysend { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 }
Expand DownExpand Up@@ -4242,11 +4262,15 @@ where
 // we don't allow forwards outbound over them.
 return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10));
 }
 if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
 if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 }
 } else {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }

 // Note that we could technically not return an error yet here and just hope
Expand DownExpand Up@@ -4298,7 +4322,13 @@ where
	fn can_forward_htlc(
 &self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
	) -> Result<(), (&'static str, u16)> {
 match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut FundedChannel<SP>| {
 let outgoing_scid = match next_packet_details.outgoing_connector {
 HopConnector::ShortChannelId(scid) => scid,
 HopConnector::Trampoline { .. } => {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }
 };
 match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
 self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
 }) {
 Some(Ok(())) => {},
Expand All@@ -4307,8 +4337,8 @@ where
 // If we couldn't find the channel info for the scid, it may be a phantom or
 // intercept forward.
 if (self.default_configuration.accept_intercept_htlcs &&
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
 {} else {
 return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10));
 }
Expand DownExpand Up@@ -5660,7 +5690,12 @@ where
 };

 let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
 let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
 let outgoing_scid_opt = next_packet_details_opt.as_ref().and_then(|d| {
 match d.outgoing_connector {
 HopConnector::ShortChannelId(scid) => { Some(scid) }
 HopConnector::Trampoline { .. } => { None }
 }
 });

 // Process the HTLC on the incoming channel.
 match self.do_funded_channel_callback(incoming_scid, |chan: &mut FundedChannel<SP>| {
Expand DownExpand Up@@ -8909,6 +8944,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
 let scid = match forward_info.routing {
 PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
 PendingHTLCRouting::TrampolineForward { .. } => 0,
 PendingHTLCRouting::Receive { .. } => 0,
 PendingHTLCRouting::ReceiveKeysend { .. } => 0,
 };
Expand DownExpand Up@@ -12476,6 +12512,13 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 (9, payment_context, option),
 (11, invoice_request, option),
	},
	(3, TrampolineForward) => {
 (0, incoming_shared_secret, required),
 (1, onion_packet, required),
 (2, blinded, option),
 (3, node_id, required),
 (4, incoming_cltv_expiry, option),
	}
);

impl_writeable_tlv_based!(PendingHTLCInfo, {
Expand Down

157 changes: 157 additions & 0 deletions
lightning/src/ln/msgs.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1775,6 +1775,13 @@ mod fuzzy_internal_msgs {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 },
 #[allow(unused)]
 TrampolineEntrypoint {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 multipath_trampoline_data: Option<FinalOnionHopData>,
 trampoline_packet: TrampolineOnionPacket,
 },
 Receive {
 payment_data: Option<FinalOnionHopData>,
 payment_metadata: Option<Vec<u8>>,
Expand DownExpand Up@@ -1805,6 +1812,36 @@ mod fuzzy_internal_msgs {
 }
	}

	#[allow(unused)]
	pub enum InboundTrampolinePayload {
 Forward {
 /// The value, in msat, of the payment after this hop's fee is deducted.
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 /// The node id to which the trampoline node must find a route.
 outgoing_node_id: PublicKey,
 },
 BlindedForward {
 short_channel_id: u64,
 payment_relay: PaymentRelay,
 payment_constraints: PaymentConstraints,
 features: BlindedHopFeatures,
 intro_node_blinding_point: Option<PublicKey>,
 next_blinding_override: Option<PublicKey>,
 },
 BlindedReceive {
 sender_intended_htlc_amt_msat: u64,
 total_msat: u64,
 cltv_expiry_height: u32,
 payment_secret: PaymentSecret,
 payment_constraints: PaymentConstraints,
 payment_context: PaymentContext,
 intro_node_blinding_point: Option<PublicKey>,
 keysend_preimage: Option<PaymentPreimage>,
 custom_tlvs: Vec<(u64, Vec<u8>)>,
 }
	}

	pub(crate) enum OutboundOnionPayload<'a> {
 Forward {
 short_channel_id: u64,
Expand DownExpand Up@@ -2858,6 +2895,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut trampoline_onion_packet: Option<TrampolineOnionPacket> = None;
 let mut invoice_request: Option<InvoiceRequest> = None;
 let mut custom_tlvs = Vec::new();

Expand All@@ -2872,6 +2910,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 (12, intro_node_blinding_point, option),
 (16, payment_metadata, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (20, trampoline_onion_packet, option),
 (77_777, invoice_request, option),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
Expand DownExpand Up@@ -2950,6 +2989,16 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else if let Some(trampoline_onion_packet) = trampoline_onion_packet {
 if payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::TrampolineEntrypoint {
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 multipath_trampoline_data: payment_data,
 trampoline_packet: trampoline_onion_packet,
 })
 } else {
 if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
 return Err(DecodeError::InvalidValue)
Expand All@@ -2971,6 +3020,114 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
	}
}

impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundTrampolinePayload where NS::Target: NodeSigner {
	fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, NS)) -> Result<Self, DecodeError> {
 let (update_add_blinding_point, node_signer) = args;

 let mut amt = None;
 let mut cltv_value = None;
 let mut payment_data: Option<FinalOnionHopData> = None;
 let mut encrypted_tlvs_opt: Option<WithoutLength<Vec<u8>>> = None;
 let mut intro_node_blinding_point = None;
 let mut outgoing_node_id: Option<PublicKey> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut custom_tlvs = Vec::new();

 let tlv_len = <BigSize as Readable>::read(r)?;
 let mut rd = FixedLengthReader::new(r, tlv_len.0);
 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 (2, amt, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (4, cltv_value, (option, encoding: (u32, HighZeroBytesDroppedBigSize))),
 (8, payment_data, option),
 (10, encrypted_tlvs_opt, option),
 (12, intro_node_blinding_point, option),
 (14, outgoing_node_id, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
 }, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
 if msg_type < 1 << 16 { return Ok(false) }
 let mut value = Vec::new();
 msg_reader.read_to_limit(&mut value, u64::MAX)?;
 custom_tlvs.push((msg_type, value));
 Ok(true)
 });

 if amt.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 if intro_node_blinding_point.is_some() && update_add_blinding_point.is_some() {
 return Err(DecodeError::InvalidValue)
 }

 if let Some(blinding_point) = intro_node_blinding_point.or(update_add_blinding_point) {
 if payment_data.is_some() {
 return Err(DecodeError::InvalidValue)
 }
 let enc_tlvs = encrypted_tlvs_opt.ok_or(DecodeError::InvalidValue)?.0;
 let enc_tlvs_ss = node_signer.ecdh(Recipient::Node, &blinding_point, None)
 .map_err(|_| DecodeError::InvalidValue)?;
 let rho = onion_utils::gen_rho_from_shared_secret(&enc_tlvs_ss.secret_bytes());
 let mut s = Cursor::new(&enc_tlvs);
 let mut reader = FixedLengthReader::new(&mut s, enc_tlvs.len() as u64);
 match ChaChaPolyReadAdapter::read(&mut reader, rho)? {
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Forward(ForwardTlvs {
 short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
 })} => {
 if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
 keysend_preimage.is_some()
 {
 return Err(DecodeError::InvalidValue)
 }
 Ok(Self::BlindedForward {
 short_channel_id,
 payment_relay,
 payment_constraints,
 features,
 intro_node_blinding_point,
 next_blinding_override,
 })
 },
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
 let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
 let expanded_key = node_signer.get_inbound_payment_key();
 if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
 return Err(DecodeError::InvalidValue);
 }

 let UnauthenticatedReceiveTlvs {
 payment_secret, payment_constraints, payment_context,
 } = tlvs;
 if total_msat.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 Ok(Self::BlindedReceive {
 sender_intended_htlc_amt_msat: amt.ok_or(DecodeError::InvalidValue)?,
 total_msat: total_msat.ok_or(DecodeError::InvalidValue)?,
 cltv_expiry_height: cltv_value.ok_or(DecodeError::InvalidValue)?,
 payment_secret,
 payment_constraints,
 payment_context,
 intro_node_blinding_point,
 keysend_preimage,
 custom_tlvs,
 })
 },
 }
 } else if let Some(outgoing_node_id) = outgoing_node_id {
 if payment_data.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::Forward {
 outgoing_node_id,
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else {
 // unblinded Trampoline receives are not supported
 return Err(DecodeError::InvalidValue);
 }
	}
}


impl Writeable for Ping {
	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 self.ponglen.write(w)?;
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WIP: Decrypt inbound Trampoline onions by arik-so · Pull Request #3585 · lightningdevkit/rust-lightning · GitHub
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WIP: Decrypt inbound Trampoline onions
#3585
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5cc6bb1

Add TrampolineForward variant to PendingHTLCRouting


arik-so Feb 10, 2025
51cecfc

Introduce HopConnector enum


arik-so Feb 3, 2025
0e61db7

Parse inbound TrampolineEntrypoint payload


arik-so Feb 10, 2025
63608c2

Decrypt inbound Trampoline packets


arik-so Feb 10, 2025

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65 changes: 54 additions & 11 deletions
lightning/src/ln/channelmanager.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -56,7 +56,7 @@ use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelType
#[cfg(any(feature = "_test_utils", test))]
use crate::types::features::Bolt11InvoiceFeatures;
use crate::routing::router::{BlindedTail, FixedRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails, HopConnector};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
Expand DownExpand Up@@ -131,7 +131,7 @@ pub use crate::ln::outbound_payment::{Bolt12PaymentError, ProbeSendFailure, Retr
#[cfg(test)]
pub(crate) use crate::ln::outbound_payment::PaymentSendFailure;
use crate::ln::script::ShutdownScript;

use crate::routing::gossip::NodeId;
// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
Expand DownExpand Up@@ -169,6 +169,25 @@ pub enum PendingHTLCRouting {
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// An HTLC which should be forwarded on to another Trampoline node.
	TrampolineForward {
 /// The onion shared secret we build with the sender (or the preceding Trampoline node) used
 /// to decrypt the onion.
 ///
 /// This is later used to encrypt failure packets in the event that the HTLC is failed.
 incoming_shared_secret: [u8; 32],
 /// The onion which should be included in the forwarded HTLC, telling the next hop what to
 /// do with the HTLC.
 onion_packet: msgs::TrampolineOnionPacket,
 /// The node ID of the Trampoline node which we need to route this HTLC to.
 node_id: NodeId, // This should be NonZero<u64> eventually when we bump MSRV
 /// Set if this HTLC is being forwarded within a blinded path.
 blinded: Option<BlindedForward>,
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// The onion indicates that this is a payment for an invoice (supposedly) generated by us.
	///
	/// Note that at this point, we have not checked that the invoice being paid was actually
Expand DownExpand Up@@ -279,6 +298,7 @@ impl PendingHTLCRouting {
	fn incoming_cltv_expiry(&self) -> Option<u32> {
 match self {
 Self::Forward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::TrampolineForward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::Receive { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 Self::ReceiveKeysend { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 }
Expand DownExpand Up@@ -4242,11 +4262,15 @@ where
 // we don't allow forwards outbound over them.
 return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10));
 }
 if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
 if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 }
 } else {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }

 // Note that we could technically not return an error yet here and just hope
Expand DownExpand Up@@ -4298,7 +4322,13 @@ where
	fn can_forward_htlc(
 &self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
	) -> Result<(), (&'static str, u16)> {
 match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut FundedChannel<SP>| {
 let outgoing_scid = match next_packet_details.outgoing_connector {
 HopConnector::ShortChannelId(scid) => scid,
 HopConnector::Trampoline { .. } => {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }
 };
 match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
 self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
 }) {
 Some(Ok(())) => {},
Expand All@@ -4307,8 +4337,8 @@ where
 // If we couldn't find the channel info for the scid, it may be a phantom or
 // intercept forward.
 if (self.default_configuration.accept_intercept_htlcs &&
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
 {} else {
 return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10));
 }
Expand DownExpand Up@@ -5660,7 +5690,12 @@ where
 };

 let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
 let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
 let outgoing_scid_opt = next_packet_details_opt.as_ref().and_then(|d| {
 match d.outgoing_connector {
 HopConnector::ShortChannelId(scid) => { Some(scid) }
 HopConnector::Trampoline { .. } => { None }
 }
 });

 // Process the HTLC on the incoming channel.
 match self.do_funded_channel_callback(incoming_scid, |chan: &mut FundedChannel<SP>| {
Expand DownExpand Up@@ -8909,6 +8944,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
 let scid = match forward_info.routing {
 PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
 PendingHTLCRouting::TrampolineForward { .. } => 0,
 PendingHTLCRouting::Receive { .. } => 0,
 PendingHTLCRouting::ReceiveKeysend { .. } => 0,
 };
Expand DownExpand Up@@ -12476,6 +12512,13 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 (9, payment_context, option),
 (11, invoice_request, option),
	},
	(3, TrampolineForward) => {
 (0, incoming_shared_secret, required),
 (1, onion_packet, required),
 (2, blinded, option),
 (3, node_id, required),
 (4, incoming_cltv_expiry, option),
	}
);

impl_writeable_tlv_based!(PendingHTLCInfo, {
Expand Down

157 changes: 157 additions & 0 deletions
lightning/src/ln/msgs.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1775,6 +1775,13 @@ mod fuzzy_internal_msgs {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 },
 #[allow(unused)]
 TrampolineEntrypoint {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 multipath_trampoline_data: Option<FinalOnionHopData>,
 trampoline_packet: TrampolineOnionPacket,
 },
 Receive {
 payment_data: Option<FinalOnionHopData>,
 payment_metadata: Option<Vec<u8>>,
Expand DownExpand Up@@ -1805,6 +1812,36 @@ mod fuzzy_internal_msgs {
 }
	}

	#[allow(unused)]
	pub enum InboundTrampolinePayload {
 Forward {
 /// The value, in msat, of the payment after this hop's fee is deducted.
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 /// The node id to which the trampoline node must find a route.
 outgoing_node_id: PublicKey,
 },
 BlindedForward {
 short_channel_id: u64,
 payment_relay: PaymentRelay,
 payment_constraints: PaymentConstraints,
 features: BlindedHopFeatures,
 intro_node_blinding_point: Option<PublicKey>,
 next_blinding_override: Option<PublicKey>,
 },
 BlindedReceive {
 sender_intended_htlc_amt_msat: u64,
 total_msat: u64,
 cltv_expiry_height: u32,
 payment_secret: PaymentSecret,
 payment_constraints: PaymentConstraints,
 payment_context: PaymentContext,
 intro_node_blinding_point: Option<PublicKey>,
 keysend_preimage: Option<PaymentPreimage>,
 custom_tlvs: Vec<(u64, Vec<u8>)>,
 }
	}

	pub(crate) enum OutboundOnionPayload<'a> {
 Forward {
 short_channel_id: u64,
Expand DownExpand Up@@ -2858,6 +2895,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut trampoline_onion_packet: Option<TrampolineOnionPacket> = None;
 let mut invoice_request: Option<InvoiceRequest> = None;
 let mut custom_tlvs = Vec::new();

Expand All@@ -2872,6 +2910,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 (12, intro_node_blinding_point, option),
 (16, payment_metadata, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (20, trampoline_onion_packet, option),
 (77_777, invoice_request, option),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
Expand DownExpand Up@@ -2950,6 +2989,16 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else if let Some(trampoline_onion_packet) = trampoline_onion_packet {
 if payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::TrampolineEntrypoint {
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 multipath_trampoline_data: payment_data,
 trampoline_packet: trampoline_onion_packet,
 })
 } else {
 if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
 return Err(DecodeError::InvalidValue)
Expand All@@ -2971,6 +3020,114 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
	}
}

impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundTrampolinePayload where NS::Target: NodeSigner {
	fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, NS)) -> Result<Self, DecodeError> {
 let (update_add_blinding_point, node_signer) = args;

 let mut amt = None;
 let mut cltv_value = None;
 let mut payment_data: Option<FinalOnionHopData> = None;
 let mut encrypted_tlvs_opt: Option<WithoutLength<Vec<u8>>> = None;
 let mut intro_node_blinding_point = None;
 let mut outgoing_node_id: Option<PublicKey> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut custom_tlvs = Vec::new();

 let tlv_len = <BigSize as Readable>::read(r)?;
 let mut rd = FixedLengthReader::new(r, tlv_len.0);
 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 (2, amt, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (4, cltv_value, (option, encoding: (u32, HighZeroBytesDroppedBigSize))),
 (8, payment_data, option),
 (10, encrypted_tlvs_opt, option),
 (12, intro_node_blinding_point, option),
 (14, outgoing_node_id, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
 }, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
 if msg_type < 1 << 16 { return Ok(false) }
 let mut value = Vec::new();
 msg_reader.read_to_limit(&mut value, u64::MAX)?;
 custom_tlvs.push((msg_type, value));
 Ok(true)
 });

 if amt.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 if intro_node_blinding_point.is_some() && update_add_blinding_point.is_some() {
 return Err(DecodeError::InvalidValue)
 }

 if let Some(blinding_point) = intro_node_blinding_point.or(update_add_blinding_point) {
 if payment_data.is_some() {
 return Err(DecodeError::InvalidValue)
 }
 let enc_tlvs = encrypted_tlvs_opt.ok_or(DecodeError::InvalidValue)?.0;
 let enc_tlvs_ss = node_signer.ecdh(Recipient::Node, &blinding_point, None)
 .map_err(|_| DecodeError::InvalidValue)?;
 let rho = onion_utils::gen_rho_from_shared_secret(&enc_tlvs_ss.secret_bytes());
 let mut s = Cursor::new(&enc_tlvs);
 let mut reader = FixedLengthReader::new(&mut s, enc_tlvs.len() as u64);
 match ChaChaPolyReadAdapter::read(&mut reader, rho)? {
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Forward(ForwardTlvs {
 short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
 })} => {
 if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
 keysend_preimage.is_some()
 {
 return Err(DecodeError::InvalidValue)
 }
 Ok(Self::BlindedForward {
 short_channel_id,
 payment_relay,
 payment_constraints,
 features,
 intro_node_blinding_point,
 next_blinding_override,
 })
 },
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
 let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
 let expanded_key = node_signer.get_inbound_payment_key();
 if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
 return Err(DecodeError::InvalidValue);
 }

 let UnauthenticatedReceiveTlvs {
 payment_secret, payment_constraints, payment_context,
 } = tlvs;
 if total_msat.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 Ok(Self::BlindedReceive {
 sender_intended_htlc_amt_msat: amt.ok_or(DecodeError::InvalidValue)?,
 total_msat: total_msat.ok_or(DecodeError::InvalidValue)?,
 cltv_expiry_height: cltv_value.ok_or(DecodeError::InvalidValue)?,
 payment_secret,
 payment_constraints,
 payment_context,
 intro_node_blinding_point,
 keysend_preimage,
 custom_tlvs,
 })
 },
 }
 } else if let Some(outgoing_node_id) = outgoing_node_id {
 if payment_data.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::Forward {
 outgoing_node_id,
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else {
 // unblinded Trampoline receives are not supported
 return Err(DecodeError::InvalidValue);
 }
	}
}


impl Writeable for Ping {
	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 self.ponglen.write(w)?;
Expand Down
Loading

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WIP: Decrypt inbound Trampoline onions by arik-so · Pull Request #3585 · lightningdevkit/rust-lightning · GitHub
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WIP: Decrypt inbound Trampoline onions#3585

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WIP: Decrypt inbound Trampoline onions
#3585
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5cc6bb1

Add TrampolineForward variant to PendingHTLCRouting


arik-so Feb 10, 2025
51cecfc

Introduce HopConnector enum


arik-so Feb 3, 2025
0e61db7

Parse inbound TrampolineEntrypoint payload


arik-so Feb 10, 2025
63608c2

Decrypt inbound Trampoline packets


arik-so Feb 10, 2025

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65 changes: 54 additions & 11 deletions
lightning/src/ln/channelmanager.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -56,7 +56,7 @@ use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelType
#[cfg(any(feature = "_test_utils", test))]
use crate::types::features::Bolt11InvoiceFeatures;
use crate::routing::router::{BlindedTail, FixedRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails, HopConnector};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
Expand DownExpand Up@@ -131,7 +131,7 @@ pub use crate::ln::outbound_payment::{Bolt12PaymentError, ProbeSendFailure, Retr
#[cfg(test)]
pub(crate) use crate::ln::outbound_payment::PaymentSendFailure;
use crate::ln::script::ShutdownScript;

use crate::routing::gossip::NodeId;
// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
Expand DownExpand Up@@ -169,6 +169,25 @@ pub enum PendingHTLCRouting {
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// An HTLC which should be forwarded on to another Trampoline node.
	TrampolineForward {
 /// The onion shared secret we build with the sender (or the preceding Trampoline node) used
 /// to decrypt the onion.
 ///
 /// This is later used to encrypt failure packets in the event that the HTLC is failed.
 incoming_shared_secret: [u8; 32],
 /// The onion which should be included in the forwarded HTLC, telling the next hop what to
 /// do with the HTLC.
 onion_packet: msgs::TrampolineOnionPacket,
 /// The node ID of the Trampoline node which we need to route this HTLC to.
 node_id: NodeId, // This should be NonZero<u64> eventually when we bump MSRV
 /// Set if this HTLC is being forwarded within a blinded path.
 blinded: Option<BlindedForward>,
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// The onion indicates that this is a payment for an invoice (supposedly) generated by us.
	///
	/// Note that at this point, we have not checked that the invoice being paid was actually
Expand DownExpand Up@@ -279,6 +298,7 @@ impl PendingHTLCRouting {
	fn incoming_cltv_expiry(&self) -> Option<u32> {
 match self {
 Self::Forward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::TrampolineForward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::Receive { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 Self::ReceiveKeysend { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 }
Expand DownExpand Up@@ -4242,11 +4262,15 @@ where
 // we don't allow forwards outbound over them.
 return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10));
 }
 if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
 if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 }
 } else {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }

 // Note that we could technically not return an error yet here and just hope
Expand DownExpand Up@@ -4298,7 +4322,13 @@ where
	fn can_forward_htlc(
 &self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
	) -> Result<(), (&'static str, u16)> {
 match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut FundedChannel<SP>| {
 let outgoing_scid = match next_packet_details.outgoing_connector {
 HopConnector::ShortChannelId(scid) => scid,
 HopConnector::Trampoline { .. } => {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }
 };
 match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
 self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
 }) {
 Some(Ok(())) => {},
Expand All@@ -4307,8 +4337,8 @@ where
 // If we couldn't find the channel info for the scid, it may be a phantom or
 // intercept forward.
 if (self.default_configuration.accept_intercept_htlcs &&
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
 {} else {
 return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10));
 }
Expand DownExpand Up@@ -5660,7 +5690,12 @@ where
 };

 let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
 let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
 let outgoing_scid_opt = next_packet_details_opt.as_ref().and_then(|d| {
 match d.outgoing_connector {
 HopConnector::ShortChannelId(scid) => { Some(scid) }
 HopConnector::Trampoline { .. } => { None }
 }
 });

 // Process the HTLC on the incoming channel.
 match self.do_funded_channel_callback(incoming_scid, |chan: &mut FundedChannel<SP>| {
Expand DownExpand Up@@ -8909,6 +8944,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
 let scid = match forward_info.routing {
 PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
 PendingHTLCRouting::TrampolineForward { .. } => 0,
 PendingHTLCRouting::Receive { .. } => 0,
 PendingHTLCRouting::ReceiveKeysend { .. } => 0,
 };
Expand DownExpand Up@@ -12476,6 +12512,13 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 (9, payment_context, option),
 (11, invoice_request, option),
	},
	(3, TrampolineForward) => {
 (0, incoming_shared_secret, required),
 (1, onion_packet, required),
 (2, blinded, option),
 (3, node_id, required),
 (4, incoming_cltv_expiry, option),
	}
);

impl_writeable_tlv_based!(PendingHTLCInfo, {
Expand Down

157 changes: 157 additions & 0 deletions
lightning/src/ln/msgs.rs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1775,6 +1775,13 @@ mod fuzzy_internal_msgs {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 },
 #[allow(unused)]
 TrampolineEntrypoint {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 multipath_trampoline_data: Option<FinalOnionHopData>,
 trampoline_packet: TrampolineOnionPacket,
 },
 Receive {
 payment_data: Option<FinalOnionHopData>,
 payment_metadata: Option<Vec<u8>>,
Expand DownExpand Up@@ -1805,6 +1812,36 @@ mod fuzzy_internal_msgs {
 }
	}

	#[allow(unused)]
	pub enum InboundTrampolinePayload {
 Forward {
 /// The value, in msat, of the payment after this hop's fee is deducted.
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 /// The node id to which the trampoline node must find a route.
 outgoing_node_id: PublicKey,
 },
 BlindedForward {
 short_channel_id: u64,
 payment_relay: PaymentRelay,
 payment_constraints: PaymentConstraints,
 features: BlindedHopFeatures,
 intro_node_blinding_point: Option<PublicKey>,
 next_blinding_override: Option<PublicKey>,
 },
 BlindedReceive {
 sender_intended_htlc_amt_msat: u64,
 total_msat: u64,
 cltv_expiry_height: u32,
 payment_secret: PaymentSecret,
 payment_constraints: PaymentConstraints,
 payment_context: PaymentContext,
 intro_node_blinding_point: Option<PublicKey>,
 keysend_preimage: Option<PaymentPreimage>,
 custom_tlvs: Vec<(u64, Vec<u8>)>,
 }
	}

	pub(crate) enum OutboundOnionPayload<'a> {
 Forward {
 short_channel_id: u64,
Expand DownExpand Up@@ -2858,6 +2895,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut trampoline_onion_packet: Option<TrampolineOnionPacket> = None;
 let mut invoice_request: Option<InvoiceRequest> = None;
 let mut custom_tlvs = Vec::new();

Expand All@@ -2872,6 +2910,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 (12, intro_node_blinding_point, option),
 (16, payment_metadata, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (20, trampoline_onion_packet, option),
 (77_777, invoice_request, option),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
Expand DownExpand Up@@ -2950,6 +2989,16 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else if let Some(trampoline_onion_packet) = trampoline_onion_packet {
 if payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::TrampolineEntrypoint {
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 multipath_trampoline_data: payment_data,
 trampoline_packet: trampoline_onion_packet,
 })
 } else {
 if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
 return Err(DecodeError::InvalidValue)
Expand All@@ -2971,6 +3020,114 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
	}
}

impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundTrampolinePayload where NS::Target: NodeSigner {
	fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, NS)) -> Result<Self, DecodeError> {
 let (update_add_blinding_point, node_signer) = args;

 let mut amt = None;
 let mut cltv_value = None;
 let mut payment_data: Option<FinalOnionHopData> = None;
 let mut encrypted_tlvs_opt: Option<WithoutLength<Vec<u8>>> = None;
 let mut intro_node_blinding_point = None;
 let mut outgoing_node_id: Option<PublicKey> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut custom_tlvs = Vec::new();

 let tlv_len = <BigSize as Readable>::read(r)?;
 let mut rd = FixedLengthReader::new(r, tlv_len.0);
 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 (2, amt, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (4, cltv_value, (option, encoding: (u32, HighZeroBytesDroppedBigSize))),
 (8, payment_data, option),
 (10, encrypted_tlvs_opt, option),
 (12, intro_node_blinding_point, option),
 (14, outgoing_node_id, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
 }, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
 if msg_type < 1 << 16 { return Ok(false) }
 let mut value = Vec::new();
 msg_reader.read_to_limit(&mut value, u64::MAX)?;
 custom_tlvs.push((msg_type, value));
 Ok(true)
 });

 if amt.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 if intro_node_blinding_point.is_some() && update_add_blinding_point.is_some() {
 return Err(DecodeError::InvalidValue)
 }

 if let Some(blinding_point) = intro_node_blinding_point.or(update_add_blinding_point) {
 if payment_data.is_some() {
 return Err(DecodeError::InvalidValue)
 }
 let enc_tlvs = encrypted_tlvs_opt.ok_or(DecodeError::InvalidValue)?.0;
 let enc_tlvs_ss = node_signer.ecdh(Recipient::Node, &blinding_point, None)
 .map_err(|_| DecodeError::InvalidValue)?;
 let rho = onion_utils::gen_rho_from_shared_secret(&enc_tlvs_ss.secret_bytes());
 let mut s = Cursor::new(&enc_tlvs);
 let mut reader = FixedLengthReader::new(&mut s, enc_tlvs.len() as u64);
 match ChaChaPolyReadAdapter::read(&mut reader, rho)? {
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Forward(ForwardTlvs {
 short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
 })} => {
 if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
 keysend_preimage.is_some()
 {
 return Err(DecodeError::InvalidValue)
 }
 Ok(Self::BlindedForward {
 short_channel_id,
 payment_relay,
 payment_constraints,
 features,
 intro_node_blinding_point,
 next_blinding_override,
 })
 },
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
 let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
 let expanded_key = node_signer.get_inbound_payment_key();
 if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
 return Err(DecodeError::InvalidValue);
 }

 let UnauthenticatedReceiveTlvs {
 payment_secret, payment_constraints, payment_context,
 } = tlvs;
 if total_msat.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 Ok(Self::BlindedReceive {
 sender_intended_htlc_amt_msat: amt.ok_or(DecodeError::InvalidValue)?,
 total_msat: total_msat.ok_or(DecodeError::InvalidValue)?,
 cltv_expiry_height: cltv_value.ok_or(DecodeError::InvalidValue)?,
 payment_secret,
 payment_constraints,
 payment_context,
 intro_node_blinding_point,
 keysend_preimage,
 custom_tlvs,
 })
 },
 }
 } else if let Some(outgoing_node_id) = outgoing_node_id {
 if payment_data.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::Forward {
 outgoing_node_id,
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else {
 // unblinded Trampoline receives are not supported
 return Err(DecodeError::InvalidValue);
 }
	}
}


impl Writeable for Ping {
	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 self.ponglen.write(w)?;
Expand Down
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(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
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// Try immediately
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// Try after navigation (SPA)
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})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
WIP: Decrypt inbound Trampoline onions by arik-so · Pull Request #3585 · lightningdevkit/rust-lightning · GitHub
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WIP: Decrypt inbound Trampoline onions#3585

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WIP: Decrypt inbound Trampoline onions
#3585
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5cc6bb1

Add TrampolineForward variant to PendingHTLCRouting


arik-so Feb 10, 2025
51cecfc

Introduce HopConnector enum


arik-so Feb 3, 2025
0e61db7

Parse inbound TrampolineEntrypoint payload


arik-so Feb 10, 2025
63608c2

Decrypt inbound Trampoline packets


arik-so Feb 10, 2025

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65 changes: 54 additions & 11 deletions
lightning/src/ln/channelmanager.rs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,7 +56,7 @@ use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelType
#[cfg(any(feature = "_test_utils", test))]
use crate::types::features::Bolt11InvoiceFeatures;
use crate::routing::router::{BlindedTail, FixedRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails, HopConnector};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
Expand DownExpand Up@@ -131,7 +131,7 @@ pub use crate::ln::outbound_payment::{Bolt12PaymentError, ProbeSendFailure, Retr
#[cfg(test)]
pub(crate) use crate::ln::outbound_payment::PaymentSendFailure;
use crate::ln::script::ShutdownScript;

use crate::routing::gossip::NodeId;
// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
Expand DownExpand Up@@ -169,6 +169,25 @@ pub enum PendingHTLCRouting {
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// An HTLC which should be forwarded on to another Trampoline node.
	TrampolineForward {
 /// The onion shared secret we build with the sender (or the preceding Trampoline node) used
 /// to decrypt the onion.
 ///
 /// This is later used to encrypt failure packets in the event that the HTLC is failed.
 incoming_shared_secret: [u8; 32],
 /// The onion which should be included in the forwarded HTLC, telling the next hop what to
 /// do with the HTLC.
 onion_packet: msgs::TrampolineOnionPacket,
 /// The node ID of the Trampoline node which we need to route this HTLC to.
 node_id: NodeId, // This should be NonZero<u64> eventually when we bump MSRV
 /// Set if this HTLC is being forwarded within a blinded path.
 blinded: Option<BlindedForward>,
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// The onion indicates that this is a payment for an invoice (supposedly) generated by us.
	///
	/// Note that at this point, we have not checked that the invoice being paid was actually
Expand DownExpand Up@@ -279,6 +298,7 @@ impl PendingHTLCRouting {
	fn incoming_cltv_expiry(&self) -> Option<u32> {
 match self {
 Self::Forward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::TrampolineForward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::Receive { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 Self::ReceiveKeysend { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 }
Expand DownExpand Up@@ -4242,11 +4262,15 @@ where
 // we don't allow forwards outbound over them.
 return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10));
 }
 if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
 if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 }
 } else {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }

 // Note that we could technically not return an error yet here and just hope
Expand DownExpand Up@@ -4298,7 +4322,13 @@ where
	fn can_forward_htlc(
 &self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
	) -> Result<(), (&'static str, u16)> {
 match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut FundedChannel<SP>| {
 let outgoing_scid = match next_packet_details.outgoing_connector {
 HopConnector::ShortChannelId(scid) => scid,
 HopConnector::Trampoline { .. } => {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }
 };
 match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
 self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
 }) {
 Some(Ok(())) => {},
Expand All@@ -4307,8 +4337,8 @@ where
 // If we couldn't find the channel info for the scid, it may be a phantom or
 // intercept forward.
 if (self.default_configuration.accept_intercept_htlcs &&
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
 {} else {
 return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10));
 }
Expand DownExpand Up@@ -5660,7 +5690,12 @@ where
 };

 let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
 let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
 let outgoing_scid_opt = next_packet_details_opt.as_ref().and_then(|d| {
 match d.outgoing_connector {
 HopConnector::ShortChannelId(scid) => { Some(scid) }
 HopConnector::Trampoline { .. } => { None }
 }
 });

 // Process the HTLC on the incoming channel.
 match self.do_funded_channel_callback(incoming_scid, |chan: &mut FundedChannel<SP>| {
Expand DownExpand Up@@ -8909,6 +8944,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
 let scid = match forward_info.routing {
 PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
 PendingHTLCRouting::TrampolineForward { .. } => 0,
 PendingHTLCRouting::Receive { .. } => 0,
 PendingHTLCRouting::ReceiveKeysend { .. } => 0,
 };
Expand DownExpand Up@@ -12476,6 +12512,13 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 (9, payment_context, option),
 (11, invoice_request, option),
	},
	(3, TrampolineForward) => {
 (0, incoming_shared_secret, required),
 (1, onion_packet, required),
 (2, blinded, option),
 (3, node_id, required),
 (4, incoming_cltv_expiry, option),
	}
);

impl_writeable_tlv_based!(PendingHTLCInfo, {
Expand Down

157 changes: 157 additions & 0 deletions
lightning/src/ln/msgs.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1775,6 +1775,13 @@ mod fuzzy_internal_msgs {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 },
 #[allow(unused)]
 TrampolineEntrypoint {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 multipath_trampoline_data: Option<FinalOnionHopData>,
 trampoline_packet: TrampolineOnionPacket,
 },
 Receive {
 payment_data: Option<FinalOnionHopData>,
 payment_metadata: Option<Vec<u8>>,
Expand DownExpand Up@@ -1805,6 +1812,36 @@ mod fuzzy_internal_msgs {
 }
	}

	#[allow(unused)]
	pub enum InboundTrampolinePayload {
 Forward {
 /// The value, in msat, of the payment after this hop's fee is deducted.
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 /// The node id to which the trampoline node must find a route.
 outgoing_node_id: PublicKey,
 },
 BlindedForward {
 short_channel_id: u64,
 payment_relay: PaymentRelay,
 payment_constraints: PaymentConstraints,
 features: BlindedHopFeatures,
 intro_node_blinding_point: Option<PublicKey>,
 next_blinding_override: Option<PublicKey>,
 },
 BlindedReceive {
 sender_intended_htlc_amt_msat: u64,
 total_msat: u64,
 cltv_expiry_height: u32,
 payment_secret: PaymentSecret,
 payment_constraints: PaymentConstraints,
 payment_context: PaymentContext,
 intro_node_blinding_point: Option<PublicKey>,
 keysend_preimage: Option<PaymentPreimage>,
 custom_tlvs: Vec<(u64, Vec<u8>)>,
 }
	}

	pub(crate) enum OutboundOnionPayload<'a> {
 Forward {
 short_channel_id: u64,
Expand DownExpand Up@@ -2858,6 +2895,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut trampoline_onion_packet: Option<TrampolineOnionPacket> = None;
 let mut invoice_request: Option<InvoiceRequest> = None;
 let mut custom_tlvs = Vec::new();

Expand All@@ -2872,6 +2910,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 (12, intro_node_blinding_point, option),
 (16, payment_metadata, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (20, trampoline_onion_packet, option),
 (77_777, invoice_request, option),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
Expand DownExpand Up@@ -2950,6 +2989,16 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else if let Some(trampoline_onion_packet) = trampoline_onion_packet {
 if payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::TrampolineEntrypoint {
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 multipath_trampoline_data: payment_data,
 trampoline_packet: trampoline_onion_packet,
 })
 } else {
 if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
 return Err(DecodeError::InvalidValue)
Expand All@@ -2971,6 +3020,114 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
	}
}

impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundTrampolinePayload where NS::Target: NodeSigner {
	fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, NS)) -> Result<Self, DecodeError> {
 let (update_add_blinding_point, node_signer) = args;

 let mut amt = None;
 let mut cltv_value = None;
 let mut payment_data: Option<FinalOnionHopData> = None;
 let mut encrypted_tlvs_opt: Option<WithoutLength<Vec<u8>>> = None;
 let mut intro_node_blinding_point = None;
 let mut outgoing_node_id: Option<PublicKey> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut custom_tlvs = Vec::new();

 let tlv_len = <BigSize as Readable>::read(r)?;
 let mut rd = FixedLengthReader::new(r, tlv_len.0);
 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 (2, amt, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (4, cltv_value, (option, encoding: (u32, HighZeroBytesDroppedBigSize))),
 (8, payment_data, option),
 (10, encrypted_tlvs_opt, option),
 (12, intro_node_blinding_point, option),
 (14, outgoing_node_id, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
 }, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
 if msg_type < 1 << 16 { return Ok(false) }
 let mut value = Vec::new();
 msg_reader.read_to_limit(&mut value, u64::MAX)?;
 custom_tlvs.push((msg_type, value));
 Ok(true)
 });

 if amt.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 if intro_node_blinding_point.is_some() && update_add_blinding_point.is_some() {
 return Err(DecodeError::InvalidValue)
 }

 if let Some(blinding_point) = intro_node_blinding_point.or(update_add_blinding_point) {
 if payment_data.is_some() {
 return Err(DecodeError::InvalidValue)
 }
 let enc_tlvs = encrypted_tlvs_opt.ok_or(DecodeError::InvalidValue)?.0;
 let enc_tlvs_ss = node_signer.ecdh(Recipient::Node, &blinding_point, None)
 .map_err(|_| DecodeError::InvalidValue)?;
 let rho = onion_utils::gen_rho_from_shared_secret(&enc_tlvs_ss.secret_bytes());
 let mut s = Cursor::new(&enc_tlvs);
 let mut reader = FixedLengthReader::new(&mut s, enc_tlvs.len() as u64);
 match ChaChaPolyReadAdapter::read(&mut reader, rho)? {
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Forward(ForwardTlvs {
 short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
 })} => {
 if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
 keysend_preimage.is_some()
 {
 return Err(DecodeError::InvalidValue)
 }
 Ok(Self::BlindedForward {
 short_channel_id,
 payment_relay,
 payment_constraints,
 features,
 intro_node_blinding_point,
 next_blinding_override,
 })
 },
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
 let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
 let expanded_key = node_signer.get_inbound_payment_key();
 if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
 return Err(DecodeError::InvalidValue);
 }

 let UnauthenticatedReceiveTlvs {
 payment_secret, payment_constraints, payment_context,
 } = tlvs;
 if total_msat.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 Ok(Self::BlindedReceive {
 sender_intended_htlc_amt_msat: amt.ok_or(DecodeError::InvalidValue)?,
 total_msat: total_msat.ok_or(DecodeError::InvalidValue)?,
 cltv_expiry_height: cltv_value.ok_or(DecodeError::InvalidValue)?,
 payment_secret,
 payment_constraints,
 payment_context,
 intro_node_blinding_point,
 keysend_preimage,
 custom_tlvs,
 })
 },
 }
 } else if let Some(outgoing_node_id) = outgoing_node_id {
 if payment_data.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::Forward {
 outgoing_node_id,
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else {
 // unblinded Trampoline receives are not supported
 return Err(DecodeError::InvalidValue);
 }
	}
}


impl Writeable for Ping {
	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 self.ponglen.write(w)?;
Expand Down
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
WIP: Decrypt inbound Trampoline onions by arik-so · Pull Request #3585 · lightningdevkit/rust-lightning · GitHub
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WIP: Decrypt inbound Trampoline onions
#3585
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5cc6bb1

Add TrampolineForward variant to PendingHTLCRouting


arik-so Feb 10, 2025
51cecfc

Introduce HopConnector enum


arik-so Feb 3, 2025
0e61db7

Parse inbound TrampolineEntrypoint payload


arik-so Feb 10, 2025
63608c2

Decrypt inbound Trampoline packets


arik-so Feb 10, 2025

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65 changes: 54 additions & 11 deletions
lightning/src/ln/channelmanager.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,7 +56,7 @@ use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelType
#[cfg(any(feature = "_test_utils", test))]
use crate::types::features::Bolt11InvoiceFeatures;
use crate::routing::router::{BlindedTail, FixedRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails, HopConnector};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
Expand DownExpand Up@@ -131,7 +131,7 @@ pub use crate::ln::outbound_payment::{Bolt12PaymentError, ProbeSendFailure, Retr
#[cfg(test)]
pub(crate) use crate::ln::outbound_payment::PaymentSendFailure;
use crate::ln::script::ShutdownScript;

use crate::routing::gossip::NodeId;
// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
Expand DownExpand Up@@ -169,6 +169,25 @@ pub enum PendingHTLCRouting {
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// An HTLC which should be forwarded on to another Trampoline node.
	TrampolineForward {
 /// The onion shared secret we build with the sender (or the preceding Trampoline node) used
 /// to decrypt the onion.
 ///
 /// This is later used to encrypt failure packets in the event that the HTLC is failed.
 incoming_shared_secret: [u8; 32],
 /// The onion which should be included in the forwarded HTLC, telling the next hop what to
 /// do with the HTLC.
 onion_packet: msgs::TrampolineOnionPacket,
 /// The node ID of the Trampoline node which we need to route this HTLC to.
 node_id: NodeId, // This should be NonZero<u64> eventually when we bump MSRV
 /// Set if this HTLC is being forwarded within a blinded path.
 blinded: Option<BlindedForward>,
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// The onion indicates that this is a payment for an invoice (supposedly) generated by us.
	///
	/// Note that at this point, we have not checked that the invoice being paid was actually
Expand DownExpand Up@@ -279,6 +298,7 @@ impl PendingHTLCRouting {
	fn incoming_cltv_expiry(&self) -> Option<u32> {
 match self {
 Self::Forward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::TrampolineForward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::Receive { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 Self::ReceiveKeysend { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 }
Expand DownExpand Up@@ -4242,11 +4262,15 @@ where
 // we don't allow forwards outbound over them.
 return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10));
 }
 if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
 if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 }
 } else {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }

 // Note that we could technically not return an error yet here and just hope
Expand DownExpand Up@@ -4298,7 +4322,13 @@ where
	fn can_forward_htlc(
 &self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
	) -> Result<(), (&'static str, u16)> {
 match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut FundedChannel<SP>| {
 let outgoing_scid = match next_packet_details.outgoing_connector {
 HopConnector::ShortChannelId(scid) => scid,
 HopConnector::Trampoline { .. } => {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }
 };
 match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
 self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
 }) {
 Some(Ok(())) => {},
Expand All@@ -4307,8 +4337,8 @@ where
 // If we couldn't find the channel info for the scid, it may be a phantom or
 // intercept forward.
 if (self.default_configuration.accept_intercept_htlcs &&
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
 {} else {
 return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10));
 }
Expand DownExpand Up@@ -5660,7 +5690,12 @@ where
 };

 let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
 let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
 let outgoing_scid_opt = next_packet_details_opt.as_ref().and_then(|d| {
 match d.outgoing_connector {
 HopConnector::ShortChannelId(scid) => { Some(scid) }
 HopConnector::Trampoline { .. } => { None }
 }
 });

 // Process the HTLC on the incoming channel.
 match self.do_funded_channel_callback(incoming_scid, |chan: &mut FundedChannel<SP>| {
Expand DownExpand Up@@ -8909,6 +8944,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
 let scid = match forward_info.routing {
 PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
 PendingHTLCRouting::TrampolineForward { .. } => 0,
 PendingHTLCRouting::Receive { .. } => 0,
 PendingHTLCRouting::ReceiveKeysend { .. } => 0,
 };
Expand DownExpand Up@@ -12476,6 +12512,13 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 (9, payment_context, option),
 (11, invoice_request, option),
	},
	(3, TrampolineForward) => {
 (0, incoming_shared_secret, required),
 (1, onion_packet, required),
 (2, blinded, option),
 (3, node_id, required),
 (4, incoming_cltv_expiry, option),
	}
);

impl_writeable_tlv_based!(PendingHTLCInfo, {
Expand Down

157 changes: 157 additions & 0 deletions
lightning/src/ln/msgs.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1775,6 +1775,13 @@ mod fuzzy_internal_msgs {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 },
 #[allow(unused)]
 TrampolineEntrypoint {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 multipath_trampoline_data: Option<FinalOnionHopData>,
 trampoline_packet: TrampolineOnionPacket,
 },
 Receive {
 payment_data: Option<FinalOnionHopData>,
 payment_metadata: Option<Vec<u8>>,
Expand DownExpand Up@@ -1805,6 +1812,36 @@ mod fuzzy_internal_msgs {
 }
	}

	#[allow(unused)]
	pub enum InboundTrampolinePayload {
 Forward {
 /// The value, in msat, of the payment after this hop's fee is deducted.
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 /// The node id to which the trampoline node must find a route.
 outgoing_node_id: PublicKey,
 },
 BlindedForward {
 short_channel_id: u64,
 payment_relay: PaymentRelay,
 payment_constraints: PaymentConstraints,
 features: BlindedHopFeatures,
 intro_node_blinding_point: Option<PublicKey>,
 next_blinding_override: Option<PublicKey>,
 },
 BlindedReceive {
 sender_intended_htlc_amt_msat: u64,
 total_msat: u64,
 cltv_expiry_height: u32,
 payment_secret: PaymentSecret,
 payment_constraints: PaymentConstraints,
 payment_context: PaymentContext,
 intro_node_blinding_point: Option<PublicKey>,
 keysend_preimage: Option<PaymentPreimage>,
 custom_tlvs: Vec<(u64, Vec<u8>)>,
 }
	}

	pub(crate) enum OutboundOnionPayload<'a> {
 Forward {
 short_channel_id: u64,
Expand DownExpand Up@@ -2858,6 +2895,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut trampoline_onion_packet: Option<TrampolineOnionPacket> = None;
 let mut invoice_request: Option<InvoiceRequest> = None;
 let mut custom_tlvs = Vec::new();

Expand All@@ -2872,6 +2910,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 (12, intro_node_blinding_point, option),
 (16, payment_metadata, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (20, trampoline_onion_packet, option),
 (77_777, invoice_request, option),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
Expand DownExpand Up@@ -2950,6 +2989,16 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else if let Some(trampoline_onion_packet) = trampoline_onion_packet {
 if payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::TrampolineEntrypoint {
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 multipath_trampoline_data: payment_data,
 trampoline_packet: trampoline_onion_packet,
 })
 } else {
 if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
 return Err(DecodeError::InvalidValue)
Expand All@@ -2971,6 +3020,114 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
	}
}

impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundTrampolinePayload where NS::Target: NodeSigner {
	fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, NS)) -> Result<Self, DecodeError> {
 let (update_add_blinding_point, node_signer) = args;

 let mut amt = None;
 let mut cltv_value = None;
 let mut payment_data: Option<FinalOnionHopData> = None;
 let mut encrypted_tlvs_opt: Option<WithoutLength<Vec<u8>>> = None;
 let mut intro_node_blinding_point = None;
 let mut outgoing_node_id: Option<PublicKey> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut custom_tlvs = Vec::new();

 let tlv_len = <BigSize as Readable>::read(r)?;
 let mut rd = FixedLengthReader::new(r, tlv_len.0);
 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 (2, amt, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (4, cltv_value, (option, encoding: (u32, HighZeroBytesDroppedBigSize))),
 (8, payment_data, option),
 (10, encrypted_tlvs_opt, option),
 (12, intro_node_blinding_point, option),
 (14, outgoing_node_id, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
 }, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
 if msg_type < 1 << 16 { return Ok(false) }
 let mut value = Vec::new();
 msg_reader.read_to_limit(&mut value, u64::MAX)?;
 custom_tlvs.push((msg_type, value));
 Ok(true)
 });

 if amt.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 if intro_node_blinding_point.is_some() && update_add_blinding_point.is_some() {
 return Err(DecodeError::InvalidValue)
 }

 if let Some(blinding_point) = intro_node_blinding_point.or(update_add_blinding_point) {
 if payment_data.is_some() {
 return Err(DecodeError::InvalidValue)
 }
 let enc_tlvs = encrypted_tlvs_opt.ok_or(DecodeError::InvalidValue)?.0;
 let enc_tlvs_ss = node_signer.ecdh(Recipient::Node, &blinding_point, None)
 .map_err(|_| DecodeError::InvalidValue)?;
 let rho = onion_utils::gen_rho_from_shared_secret(&enc_tlvs_ss.secret_bytes());
 let mut s = Cursor::new(&enc_tlvs);
 let mut reader = FixedLengthReader::new(&mut s, enc_tlvs.len() as u64);
 match ChaChaPolyReadAdapter::read(&mut reader, rho)? {
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Forward(ForwardTlvs {
 short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
 })} => {
 if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
 keysend_preimage.is_some()
 {
 return Err(DecodeError::InvalidValue)
 }
 Ok(Self::BlindedForward {
 short_channel_id,
 payment_relay,
 payment_constraints,
 features,
 intro_node_blinding_point,
 next_blinding_override,
 })
 },
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
 let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
 let expanded_key = node_signer.get_inbound_payment_key();
 if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
 return Err(DecodeError::InvalidValue);
 }

 let UnauthenticatedReceiveTlvs {
 payment_secret, payment_constraints, payment_context,
 } = tlvs;
 if total_msat.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 Ok(Self::BlindedReceive {
 sender_intended_htlc_amt_msat: amt.ok_or(DecodeError::InvalidValue)?,
 total_msat: total_msat.ok_or(DecodeError::InvalidValue)?,
 cltv_expiry_height: cltv_value.ok_or(DecodeError::InvalidValue)?,
 payment_secret,
 payment_constraints,
 payment_context,
 intro_node_blinding_point,
 keysend_preimage,
 custom_tlvs,
 })
 },
 }
 } else if let Some(outgoing_node_id) = outgoing_node_id {
 if payment_data.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::Forward {
 outgoing_node_id,
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else {
 // unblinded Trampoline receives are not supported
 return Err(DecodeError::InvalidValue);
 }
	}
}


impl Writeable for Ping {
	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 self.ponglen.write(w)?;
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
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var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
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}
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pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
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/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
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removeDarkMode();
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WIP: Decrypt inbound Trampoline onions by arik-so · Pull Request #3585 · lightningdevkit/rust-lightning · GitHub
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WIP: Decrypt inbound Trampoline onions
#3585
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5cc6bb1

Add TrampolineForward variant to PendingHTLCRouting


arik-so Feb 10, 2025
51cecfc

Introduce HopConnector enum


arik-so Feb 3, 2025
0e61db7

Parse inbound TrampolineEntrypoint payload


arik-so Feb 10, 2025
63608c2

Decrypt inbound Trampoline packets


arik-so Feb 10, 2025

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65 changes: 54 additions & 11 deletions
lightning/src/ln/channelmanager.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,7 +56,7 @@ use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelType
#[cfg(any(feature = "_test_utils", test))]
use crate::types::features::Bolt11InvoiceFeatures;
use crate::routing::router::{BlindedTail, FixedRouter, InFlightHtlcs, Path, Payee, PaymentParameters, Route, RouteParameters, Router};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails};
use crate::ln::onion_payment::{check_incoming_htlc_cltv, create_recv_pending_htlc_info, create_fwd_pending_htlc_info, decode_incoming_update_add_htlc_onion, InboundHTLCErr, NextPacketDetails, HopConnector};
use crate::ln::msgs;
use crate::ln::onion_utils;
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
Expand DownExpand Up@@ -131,7 +131,7 @@ pub use crate::ln::outbound_payment::{Bolt12PaymentError, ProbeSendFailure, Retr
#[cfg(test)]
pub(crate) use crate::ln::outbound_payment::PaymentSendFailure;
use crate::ln::script::ShutdownScript;

use crate::routing::gossip::NodeId;
// We hold various information about HTLC relay in the HTLC objects in Channel itself:
//
// Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
Expand DownExpand Up@@ -169,6 +169,25 @@ pub enum PendingHTLCRouting {
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// An HTLC which should be forwarded on to another Trampoline node.
	TrampolineForward {
 /// The onion shared secret we build with the sender (or the preceding Trampoline node) used
 /// to decrypt the onion.
 ///
 /// This is later used to encrypt failure packets in the event that the HTLC is failed.
 incoming_shared_secret: [u8; 32],
 /// The onion which should be included in the forwarded HTLC, telling the next hop what to
 /// do with the HTLC.
 onion_packet: msgs::TrampolineOnionPacket,
 /// The node ID of the Trampoline node which we need to route this HTLC to.
 node_id: NodeId, // This should be NonZero<u64> eventually when we bump MSRV
 /// Set if this HTLC is being forwarded within a blinded path.
 blinded: Option<BlindedForward>,
 /// The absolute CLTV of the inbound HTLC
 incoming_cltv_expiry: Option<u32>,
	},

	/// The onion indicates that this is a payment for an invoice (supposedly) generated by us.
	///
	/// Note that at this point, we have not checked that the invoice being paid was actually
Expand DownExpand Up@@ -279,6 +298,7 @@ impl PendingHTLCRouting {
	fn incoming_cltv_expiry(&self) -> Option<u32> {
 match self {
 Self::Forward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::TrampolineForward { incoming_cltv_expiry, .. } => *incoming_cltv_expiry,
 Self::Receive { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 Self::ReceiveKeysend { incoming_cltv_expiry, .. } => Some(*incoming_cltv_expiry),
 }
Expand DownExpand Up@@ -4242,11 +4262,15 @@ where
 // we don't allow forwards outbound over them.
 return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10));
 }
 if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
 if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
 // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 // "refuse to forward unless the SCID alias was used", so we pretend
 // we don't have the channel here.
 return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10));
 }
 } else {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }

 // Note that we could technically not return an error yet here and just hope
Expand DownExpand Up@@ -4298,7 +4322,13 @@ where
	fn can_forward_htlc(
 &self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
	) -> Result<(), (&'static str, u16)> {
 match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut FundedChannel<SP>| {
 let outgoing_scid = match next_packet_details.outgoing_connector {
 HopConnector::ShortChannelId(scid) => scid,
 HopConnector::Trampoline { .. } => {
 return Err(("Cannot forward by Node ID without SCID.", 0x4000 | 10));
 }
 };
 match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
 self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
 }) {
 Some(Ok(())) => {},
Expand All@@ -4307,8 +4337,8 @@ where
 // If we couldn't find the channel info for the scid, it may be a phantom or
 // intercept forward.
 if (self.default_configuration.accept_intercept_htlcs &&
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
 fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
 fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
 {} else {
 return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10));
 }
Expand DownExpand Up@@ -5660,7 +5690,12 @@ where
 };

 let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
 let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
 let outgoing_scid_opt = next_packet_details_opt.as_ref().and_then(|d| {
 match d.outgoing_connector {
 HopConnector::ShortChannelId(scid) => { Some(scid) }
 HopConnector::Trampoline { .. } => { None }
 }
 });

 // Process the HTLC on the incoming channel.
 match self.do_funded_channel_callback(incoming_scid, |chan: &mut FundedChannel<SP>| {
Expand DownExpand Up@@ -8909,6 +8944,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
 let scid = match forward_info.routing {
 PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
 PendingHTLCRouting::TrampolineForward { .. } => 0,
 PendingHTLCRouting::Receive { .. } => 0,
 PendingHTLCRouting::ReceiveKeysend { .. } => 0,
 };
Expand DownExpand Up@@ -12476,6 +12512,13 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 (9, payment_context, option),
 (11, invoice_request, option),
	},
	(3, TrampolineForward) => {
 (0, incoming_shared_secret, required),
 (1, onion_packet, required),
 (2, blinded, option),
 (3, node_id, required),
 (4, incoming_cltv_expiry, option),
	}
);

impl_writeable_tlv_based!(PendingHTLCInfo, {
Expand Down

157 changes: 157 additions & 0 deletions
lightning/src/ln/msgs.rs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1775,6 +1775,13 @@ mod fuzzy_internal_msgs {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 },
 #[allow(unused)]
 TrampolineEntrypoint {
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 multipath_trampoline_data: Option<FinalOnionHopData>,
 trampoline_packet: TrampolineOnionPacket,
 },
 Receive {
 payment_data: Option<FinalOnionHopData>,
 payment_metadata: Option<Vec<u8>>,
Expand DownExpand Up@@ -1805,6 +1812,36 @@ mod fuzzy_internal_msgs {
 }
	}

	#[allow(unused)]
	pub enum InboundTrampolinePayload {
 Forward {
 /// The value, in msat, of the payment after this hop's fee is deducted.
 amt_to_forward: u64,
 outgoing_cltv_value: u32,
 /// The node id to which the trampoline node must find a route.
 outgoing_node_id: PublicKey,
 },
 BlindedForward {
 short_channel_id: u64,
 payment_relay: PaymentRelay,
 payment_constraints: PaymentConstraints,
 features: BlindedHopFeatures,
 intro_node_blinding_point: Option<PublicKey>,
 next_blinding_override: Option<PublicKey>,
 },
 BlindedReceive {
 sender_intended_htlc_amt_msat: u64,
 total_msat: u64,
 cltv_expiry_height: u32,
 payment_secret: PaymentSecret,
 payment_constraints: PaymentConstraints,
 payment_context: PaymentContext,
 intro_node_blinding_point: Option<PublicKey>,
 keysend_preimage: Option<PaymentPreimage>,
 custom_tlvs: Vec<(u64, Vec<u8>)>,
 }
	}

	pub(crate) enum OutboundOnionPayload<'a> {
 Forward {
 short_channel_id: u64,
Expand DownExpand Up@@ -2858,6 +2895,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut trampoline_onion_packet: Option<TrampolineOnionPacket> = None;
 let mut invoice_request: Option<InvoiceRequest> = None;
 let mut custom_tlvs = Vec::new();

Expand All@@ -2872,6 +2910,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 (12, intro_node_blinding_point, option),
 (16, payment_metadata, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (20, trampoline_onion_packet, option),
 (77_777, invoice_request, option),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
Expand DownExpand Up@@ -2950,6 +2989,16 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else if let Some(trampoline_onion_packet) = trampoline_onion_packet {
 if payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::TrampolineEntrypoint {
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 multipath_trampoline_data: payment_data,
 trampoline_packet: trampoline_onion_packet,
 })
 } else {
 if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
 return Err(DecodeError::InvalidValue)
Expand All@@ -2971,6 +3020,114 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
	}
}

impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundTrampolinePayload where NS::Target: NodeSigner {
	fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, NS)) -> Result<Self, DecodeError> {
 let (update_add_blinding_point, node_signer) = args;

 let mut amt = None;
 let mut cltv_value = None;
 let mut payment_data: Option<FinalOnionHopData> = None;
 let mut encrypted_tlvs_opt: Option<WithoutLength<Vec<u8>>> = None;
 let mut intro_node_blinding_point = None;
 let mut outgoing_node_id: Option<PublicKey> = None;
 let mut total_msat = None;
 let mut keysend_preimage: Option<PaymentPreimage> = None;
 let mut custom_tlvs = Vec::new();

 let tlv_len = <BigSize as Readable>::read(r)?;
 let mut rd = FixedLengthReader::new(r, tlv_len.0);
 decode_tlv_stream_with_custom_tlv_decode!(&mut rd, {
 (2, amt, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 (4, cltv_value, (option, encoding: (u32, HighZeroBytesDroppedBigSize))),
 (8, payment_data, option),
 (10, encrypted_tlvs_opt, option),
 (12, intro_node_blinding_point, option),
 (14, outgoing_node_id, option),
 (18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
 // See https://github.com/lightning/blips/blob/master/blip-0003.md
 (5482373484, keysend_preimage, option)
 }, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
 if msg_type < 1 << 16 { return Ok(false) }
 let mut value = Vec::new();
 msg_reader.read_to_limit(&mut value, u64::MAX)?;
 custom_tlvs.push((msg_type, value));
 Ok(true)
 });

 if amt.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 if intro_node_blinding_point.is_some() && update_add_blinding_point.is_some() {
 return Err(DecodeError::InvalidValue)
 }

 if let Some(blinding_point) = intro_node_blinding_point.or(update_add_blinding_point) {
 if payment_data.is_some() {
 return Err(DecodeError::InvalidValue)
 }
 let enc_tlvs = encrypted_tlvs_opt.ok_or(DecodeError::InvalidValue)?.0;
 let enc_tlvs_ss = node_signer.ecdh(Recipient::Node, &blinding_point, None)
 .map_err(|_| DecodeError::InvalidValue)?;
 let rho = onion_utils::gen_rho_from_shared_secret(&enc_tlvs_ss.secret_bytes());
 let mut s = Cursor::new(&enc_tlvs);
 let mut reader = FixedLengthReader::new(&mut s, enc_tlvs.len() as u64);
 match ChaChaPolyReadAdapter::read(&mut reader, rho)? {
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Forward(ForwardTlvs {
 short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
 })} => {
 if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
 keysend_preimage.is_some()
 {
 return Err(DecodeError::InvalidValue)
 }
 Ok(Self::BlindedForward {
 short_channel_id,
 payment_relay,
 payment_constraints,
 features,
 intro_node_blinding_point,
 next_blinding_override,
 })
 },
 ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
 let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
 let expanded_key = node_signer.get_inbound_payment_key();
 if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
 return Err(DecodeError::InvalidValue);
 }

 let UnauthenticatedReceiveTlvs {
 payment_secret, payment_constraints, payment_context,
 } = tlvs;
 if total_msat.unwrap_or(0) > MAX_VALUE_MSAT { return Err(DecodeError::InvalidValue) }
 Ok(Self::BlindedReceive {
 sender_intended_htlc_amt_msat: amt.ok_or(DecodeError::InvalidValue)?,
 total_msat: total_msat.ok_or(DecodeError::InvalidValue)?,
 cltv_expiry_height: cltv_value.ok_or(DecodeError::InvalidValue)?,
 payment_secret,
 payment_constraints,
 payment_context,
 intro_node_blinding_point,
 keysend_preimage,
 custom_tlvs,
 })
 },
 }
 } else if let Some(outgoing_node_id) = outgoing_node_id {
 if payment_data.is_some() || encrypted_tlvs_opt.is_some() ||
 total_msat.is_some()
 { return Err(DecodeError::InvalidValue) }
 Ok(Self::Forward {
 outgoing_node_id,
 amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 })
 } else {
 // unblinded Trampoline receives are not supported
 return Err(DecodeError::InvalidValue);
 }
	}
}


impl Writeable for Ping {
	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 self.ponglen.write(w)?;
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