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Decrypt Trampoline onions
In this commit, we start decrypting the inner onion we receive, and lay some groundwork towards handling the subsequent routing or payment receipt.
1 parent 4a10d2a commit 3013c22

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3 files changed

+302
-33
lines changed

3 files changed

+302
-33
lines changed

‎lightning/src/ln/channelmanager.rs‎

Lines changed: 26 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4479,11 +4479,36 @@ where
44794479
Err(InboundHTLCErr { err_code, err_data, msg }) => return_err!(msg, err_code, &err_data)
44804480
}
44814481
},
4482+
#[cfg(trampoline)]
4483+
onion_utils::Hop::TrampolineReceive { .. } => {
4484+
// OUR PAYMENT!
4485+
let current_height: u32 = self.best_block.read().unwrap().height;
4486+
match create_recv_pending_htlc_info(decoded_hop, shared_secret, msg.payment_hash,
4487+
msg.amount_msat, msg.cltv_expiry, None, allow_underpay, msg.skimmed_fee_msat,
4488+
current_height)
4489+
{
4490+
Ok(info) => {
4491+
// Note that we could obviously respond immediately with an update_fulfill_htlc
4492+
// message, however that would leak that we are the recipient of this payment, so
4493+
// instead we stay symmetric with the forwarding case, only responding (after a
4494+
// delay) once they've sent us a commitment_signed!
4495+
PendingHTLCStatus::Forward(info)
4496+
},
4497+
Err(InboundHTLCErr { err_code, err_data, msg }) => return_err!(msg, err_code, &err_data)
4498+
}
4499+
},
44824500
onion_utils::Hop::Forward { .. } | onion_utils::Hop::BlindedForward { .. } => {
44834501
match create_fwd_pending_htlc_info(msg, decoded_hop, shared_secret, next_packet_pubkey_opt) {
44844502
Ok(info) => PendingHTLCStatus::Forward(info),
44854503
Err(InboundHTLCErr { err_code, err_data, msg }) => return_err!(msg, err_code, &err_data)
44864504
}
4505+
},
4506+
#[cfg(trampoline)]
4507+
onion_utils::Hop::TrampolineForward { .. } | onion_utils::Hop::TrampolineBlindedForward { .. } => {
4508+
match create_fwd_pending_htlc_info(msg, decoded_hop, shared_secret, next_packet_pubkey_opt) {
4509+
Ok(info) => PendingHTLCStatus::Forward(info),
4510+
Err(InboundHTLCErr { err_code, err_data, msg }) => return_err!(msg, err_code, &err_data)
4511+
}
44874512
}
44884513
}
44894514
}
@@ -5895,7 +5920,7 @@ where
58955920
// of the onion.
58965921
failed_payment!(err_msg, err_code, sha256_of_onion.to_vec(), None);
58975922
},
5898-
Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code, shared_secret }) => {
5923+
Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code, shared_secret, .. }) => {
58995924
let phantom_shared_secret = shared_secret.secret_bytes();
59005925
failed_payment!(err_msg, err_code, Vec::new(), Some(phantom_shared_secret));
59015926
},

‎lightning/src/ln/onion_payment.rs‎

Lines changed: 144 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@
55
66
use bitcoin::hashes::Hash;
77
use bitcoin::hashes::sha256::Hash as Sha256;
8-
use bitcoin::secp256k1::{self, PublicKey, Secp256k1};
8+
use bitcoin::secp256k1::{self, PublicKey, Secp256k1, ecdh::SharedSecret};
99

1010
use crate::blinded_path;
1111
use crate::blinded_path::payment::{PaymentConstraints, PaymentRelay};
@@ -15,7 +15,7 @@ use crate::ln::channelmanager::{BlindedFailure, BlindedForward, CLTV_FAR_FAR_AWA
1515
use crate::types::features::BlindedHopFeatures;
1616
use crate::ln::msgs;
1717
use crate::ln::onion_utils;
18-
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
18+
use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING, ONION_DATA_LEN};
1919
use crate::routing::gossip::NodeId;
2020
use crate::sign::{NodeSigner, Recipient};
2121
use crate::util::logger::Logger;
@@ -61,20 +61,36 @@ fn check_blinded_forward(
6161
Ok((amt_to_forward, outgoing_cltv_value))
6262
}
6363

64+
enum RoutingInfo {
65+
Direct {
66+
short_channel_id: u64,
67+
new_packet_bytes: [u8; ONION_DATA_LEN],
68+
next_hop_hmac: [u8; 32]
69+
},
70+
#[cfg(trampoline)]
71+
Trampoline {
72+
outgoing_node_id: NodeId,
73+
// Trampoline onions are currently variable length
74+
new_packet_bytes: Vec<u8>,
75+
next_hop_hmac: [u8; 32],
76+
shared_secret: SharedSecret
77+
}
78+
}
79+
6480
pub(super) fn create_fwd_pending_htlc_info(
6581
msg: &msgs::UpdateAddHTLC, hop_data: onion_utils::Hop, shared_secret: [u8; 32],
6682
next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
6783
) -> Result<PendingHTLCInfo, InboundHTLCErr> {
6884
debug_assert!(next_packet_pubkey_opt.is_some());
6985

7086
let (
71-
short_channel_id, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point,
72-
next_blinding_override, new_packet_bytes, next_hop_hmac
87+
routing_info, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point,
88+
next_blinding_override
7389
) = match hop_data {
7490
onion_utils::Hop::Forward { next_hop_data: msgs::InboundOnionForwardPayload {
7591
short_channel_id, amt_to_forward, outgoing_cltv_value
7692
}, new_packet_bytes, next_hop_hmac, .. } =>
77-
(short_channel_id, amt_to_forward, outgoing_cltv_value, None, None, new_packet_bytes, next_hop_hmac),
93+
(RoutingInfo::Direct { short_channel_id, new_packet_bytes, next_hop_hmac }, amt_to_forward, outgoing_cltv_value, None, None),
7894
onion_utils::Hop::BlindedForward { next_hop_data: msgs::InboundOnionBlindedForwardPayload {
7995
short_channel_id, payment_relay, payment_constraints, intro_node_blinding_point, features,
8096
next_blinding_override,
@@ -90,38 +106,115 @@ pub(super) fn create_fwd_pending_htlc_info(
90106
err_data: vec![0; 32],
91107
}
92108
})?;
93-
(short_channel_id, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point,
94-
next_blinding_override, new_packet_bytes, next_hop_hmac)
109+
(RoutingInfo::Direct { short_channel_id, new_packet_bytes, next_hop_hmac }, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point,
110+
next_blinding_override)
95111
},
96112
onion_utils::Hop::Receive { .. } | onion_utils::Hop::BlindedReceive { .. } =>
97113
return Err(InboundHTLCErr {
98114
msg: "Final Node OnionHopData provided for us as an intermediary node",
99115
err_code: 0x4000 | 22,
100116
err_data: Vec::new(),
101117
}),
118+
#[cfg(trampoline)]
119+
onion_utils::Hop::TrampolineReceive { .. } =>
120+
return Err(InboundHTLCErr {
121+
msg: "Final Node OnionHopData provided for us as an intermediary node",
122+
err_code: 0x4000 | 22,
123+
err_data: Vec::new(),
124+
}),
125+
#[cfg(trampoline)]
126+
onion_utils::Hop::TrampolineForward { next_trampoline_hop_data, next_trampoline_hop_hmac, new_trampoline_packet_bytes, trampoline_shared_secret, .. } => {
127+
(
128+
RoutingInfo::Trampoline {
129+
outgoing_node_id: next_trampoline_hop_data.outgoing_node_id,
130+
new_packet_bytes: new_trampoline_packet_bytes,
131+
next_hop_hmac: next_trampoline_hop_hmac,
132+
shared_secret: trampoline_shared_secret
133+
},
134+
next_trampoline_hop_data.amt_to_forward,
135+
next_trampoline_hop_data.outgoing_cltv_value,
136+
None,
137+
None
138+
)
139+
},
140+
#[cfg(trampoline)]
141+
onion_utils::Hop::TrampolineBlindedForward { next_trampoline_hop_data, next_trampoline_hop_hmac, new_trampoline_packet_bytes, trampoline_shared_secret, .. } => {
142+
let (amt_to_forward, outgoing_cltv_value) = check_blinded_forward(
143+
msg.amount_msat, msg.cltv_expiry, &next_trampoline_hop_data.payment_relay, &next_trampoline_hop_data.payment_constraints, &next_trampoline_hop_data.features
144+
).map_err(|()| {
145+
// We should be returning malformed here if `msg.blinding_point` is set, but this is
146+
// unreachable right now since we checked it in `decode_update_add_htlc_onion`.
147+
InboundHTLCErr {
148+
msg: "Underflow calculating outbound amount or cltv value for blinded forward",
149+
err_code: INVALID_ONION_BLINDING,
150+
err_data: vec![0; 32],
151+
}
152+
})?;
153+
(
154+
RoutingInfo::Trampoline {
155+
outgoing_node_id: next_trampoline_hop_data.outgoing_node_id,
156+
new_packet_bytes: new_trampoline_packet_bytes,
157+
next_hop_hmac: next_trampoline_hop_hmac,
158+
shared_secret: trampoline_shared_secret
159+
},
160+
amt_to_forward,
161+
outgoing_cltv_value,
162+
next_trampoline_hop_data.intro_node_blinding_point,
163+
next_trampoline_hop_data.next_blinding_override
164+
)
165+
},
102166
};
103167

104-
let outgoing_packet = msgs::OnionPacket {
105-
version: 0,
106-
public_key: next_packet_pubkey_opt.unwrap_or(Err(secp256k1::Error::InvalidPublicKey)),
107-
hop_data: new_packet_bytes,
108-
hmac: next_hop_hmac,
168+
let routing = match routing_info {
169+
RoutingInfo::Direct { short_channel_id, new_packet_bytes, next_hop_hmac } => {
170+
let outgoing_packet = msgs::OnionPacket {
171+
version: 0,
172+
public_key: next_packet_pubkey_opt.unwrap_or(Err(secp256k1::Error::InvalidPublicKey)),
173+
hop_data: new_packet_bytes,
174+
hmac: next_hop_hmac,
175+
};
176+
PendingHTLCRouting::Forward {
177+
onion_packet: outgoing_packet,
178+
short_channel_id,
179+
incoming_cltv_expiry: Some(msg.cltv_expiry),
180+
blinded: intro_node_blinding_point.or(msg.blinding_point)
181+
.map(|bp| BlindedForward {
182+
inbound_blinding_point: bp,
183+
next_blinding_override,
184+
failure: intro_node_blinding_point
185+
.map(|_| BlindedFailure::FromIntroductionNode)
186+
.unwrap_or(BlindedFailure::FromBlindedNode),
187+
}),
188+
}
189+
}
190+
#[cfg(trampoline)]
191+
RoutingInfo::Trampoline { outgoing_node_id, new_packet_bytes, next_hop_hmac, shared_secret } => {
192+
let next_trampoline_packet_pubkey = match next_packet_pubkey_opt {
193+
Some(Ok(pubkey)) => pubkey,
194+
_ => return Err(InboundHTLCErr {
195+
msg: "Missing next Trampoline hop pubkey from intermediate Trampoline forwarding data",
196+
err_code: 0x4000 | 22,
197+
err_data: Vec::new(),
198+
}),
199+
};
200+
let outgoing_packet = msgs::TrampolineOnionPacket {
201+
version: 0,
202+
public_key: next_trampoline_packet_pubkey,
203+
hop_data: new_packet_bytes,
204+
hmac: next_hop_hmac,
205+
};
206+
PendingHTLCRouting::TrampolineForward {
207+
incoming_shared_secret: shared_secret.secret_bytes(),
208+
onion_packet: outgoing_packet,
209+
node_id: outgoing_node_id,
210+
incoming_cltv_expiry: msg.cltv_expiry,
211+
blinded: None
212+
}
213+
}
109214
};
110215

111216
Ok(PendingHTLCInfo {
112-
routing: PendingHTLCRouting::Forward {
113-
onion_packet: outgoing_packet,
114-
short_channel_id,
115-
incoming_cltv_expiry: Some(msg.cltv_expiry),
116-
blinded: intro_node_blinding_point.or(msg.blinding_point)
117-
.map(|bp| BlindedForward {
118-
inbound_blinding_point: bp,
119-
next_blinding_override,
120-
failure: intro_node_blinding_point
121-
.map(|_| BlindedFailure::FromIntroductionNode)
122-
.unwrap_or(BlindedFailure::FromBlindedNode),
123-
}),
124-
},
217+
routing,
125218
payment_hash: msg.payment_hash,
126219
incoming_shared_secret: shared_secret,
127220
incoming_amt_msat: Some(msg.amount_msat),
@@ -167,6 +260,8 @@ pub(super) fn create_recv_pending_htlc_info(
167260
sender_intended_htlc_amt_msat, cltv_expiry_height, None, Some(payment_context),
168261
intro_node_blinding_point.is_none(), true, invoice_request)
169262
}
263+
#[cfg(trampoline)]
264+
onion_utils::Hop::TrampolineReceive { .. } => todo!(),
170265
onion_utils::Hop::Forward { .. } => {
171266
return Err(InboundHTLCErr {
172267
err_code: 0x4000|22,
@@ -181,6 +276,14 @@ pub(super) fn create_recv_pending_htlc_info(
181276
msg: "Got blinded non final data with an HMAC of 0",
182277
})
183278
},
279+
#[cfg(trampoline)]
280+
onion_utils::Hop::TrampolineForward { .. } | onion_utils::Hop::TrampolineBlindedForward { .. } => {
281+
return Err(InboundHTLCErr {
282+
err_code: 0x4000|22,
283+
err_data: Vec::new(),
284+
msg: "Got Trampoline non final data with an HMAC of 0",
285+
})
286+
},
184287
};
185288
// final_incorrect_cltv_expiry
186289
if onion_cltv_expiry > cltv_expiry {
@@ -391,7 +494,7 @@ where
391494
return_malformed_err!("Unknown onion packet version", 0x8000 | 0x4000 | 4);
392495
}
393496

394-
let encode_relay_error = |message: &str, err_code: u16, shared_secret: [u8; 32], data: &[u8]| {
497+
let encode_relay_error = |message: &str, err_code: u16, shared_secret: [u8; 32], trampoline_shared_secret: Option<[u8; 32]>, data: &[u8]| {
395498
if msg.blinding_point.is_some() {
396499
return_malformed_err!(message, INVALID_ONION_BLINDING)
397500
}
@@ -401,7 +504,7 @@ where
401504
channel_id: msg.channel_id,
402505
htlc_id: msg.htlc_id,
403506
reason: HTLCFailReason::reason(err_code, data.to_vec())
404-
.get_encrypted_failure_packet(&shared_secret, &None),
507+
.get_encrypted_failure_packet(&shared_secret, &trampoline_shared_secret),
405508
}));
406509
};
407510

@@ -413,8 +516,8 @@ where
413516
Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
414517
return_malformed_err!(err_msg, err_code);
415518
},
416-
Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code, shared_secret }) => {
417-
return encode_relay_error(err_msg, err_code, shared_secret.secret_bytes(), &[0; 0]);
519+
Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code, shared_secret, trampoline_shared_secret }) => {
520+
return encode_relay_error(err_msg, err_code, shared_secret.secret_bytes(), trampoline_shared_secret.map(|tss| tss.secret_bytes()), &[0; 0]);
418521
},
419522
};
420523

@@ -434,7 +537,7 @@ where
434537
Ok((amt, cltv)) => (amt, cltv),
435538
Err(()) => {
436539
return encode_relay_error("Underflow calculating outbound amount or cltv value for blinded forward",
437-
INVALID_ONION_BLINDING, shared_secret.secret_bytes(), &[0; 32]);
540+
INVALID_ONION_BLINDING, shared_secret.secret_bytes(), None, &[0; 32]);
438541
}
439542
};
440543
let next_packet_pubkey = onion_utils::next_hop_pubkey(&secp_ctx,
@@ -444,6 +547,17 @@ where
444547
outgoing_cltv_value
445548
})
446549
}
550+
#[cfg(trampoline)]
551+
onion_utils::Hop::TrampolineForward { next_trampoline_hop_data: msgs::InboundTrampolineForwardPayload { amt_to_forward, outgoing_cltv_value, outgoing_node_id }, trampoline_shared_secret, incoming_trampoline_public_key, .. } => {
552+
let next_trampoline_packet_pubkey = onion_utils::next_hop_pubkey(secp_ctx,
553+
incoming_trampoline_public_key, &trampoline_shared_secret.secret_bytes());
554+
Some(NextPacketDetails {
555+
next_packet_pubkey: next_trampoline_packet_pubkey,
556+
outgoing_connector: HopConnector::Trampoline(outgoing_node_id),
557+
outgoing_amt_msat: amt_to_forward,
558+
outgoing_cltv_value,
559+
})
560+
}
447561
_ => None
448562
};
449563

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