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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 06a4828

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3 files changed

+312
-33
lines changed

3 files changed

+312
-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: 154 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 +61,37 @@ 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+
current_path_key: Option<PublicKey>
78+
}
79+
}
80+
6481
pub(super) fn create_fwd_pending_htlc_info(
6582
msg: &msgs::UpdateAddHTLC, hop_data: onion_utils::Hop, shared_secret: [u8; 32],
6683
next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
6784
) -> Result<PendingHTLCInfo, InboundHTLCErr> {
6885
debug_assert!(next_packet_pubkey_opt.is_some());
6986

7087
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
88+
routing_info, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point,
89+
next_blinding_override
7390
) = match hop_data {
7491
onion_utils::Hop::Forward { next_hop_data: msgs::InboundOnionForwardPayload {
7592
short_channel_id, amt_to_forward, outgoing_cltv_value
7693
}, new_packet_bytes, next_hop_hmac, .. } =>
77-
(short_channel_id, amt_to_forward, outgoing_cltv_value, None, None, new_packet_bytes, next_hop_hmac),
94+
(RoutingInfo::Direct { short_channel_id, new_packet_bytes, next_hop_hmac }, amt_to_forward, outgoing_cltv_value, None, None),
7895
onion_utils::Hop::BlindedForward { next_hop_data: msgs::InboundOnionBlindedForwardPayload {
7996
short_channel_id, payment_relay, payment_constraints, intro_node_blinding_point, features,
8097
next_blinding_override,
@@ -90,38 +107,124 @@ pub(super) fn create_fwd_pending_htlc_info(
90107
err_data: vec![0; 32],
91108
}
92109
})?;
93-
(short_channel_id, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point,
94-
next_blinding_override, new_packet_bytes, next_hop_hmac)
110+
(RoutingInfo::Direct { short_channel_id, new_packet_bytes, next_hop_hmac }, amt_to_forward, outgoing_cltv_value, intro_node_blinding_point,
111+
next_blinding_override)
95112
},
96113
onion_utils::Hop::Receive { .. } | onion_utils::Hop::BlindedReceive { .. } =>
97114
return Err(InboundHTLCErr {
98115
msg: "Final Node OnionHopData provided for us as an intermediary node",
99116
err_code: 0x4000 | 22,
100117
err_data: Vec::new(),
101118
}),
119+
#[cfg(trampoline)]
120+
onion_utils::Hop::TrampolineReceive { .. } =>
121+
return Err(InboundHTLCErr {
122+
msg: "Final Node OnionHopData provided for us as an intermediary node",
123+
err_code: 0x4000 | 22,
124+
err_data: Vec::new(),
125+
}),
126+
#[cfg(trampoline)]
127+
onion_utils::Hop::TrampolineForward { next_trampoline_hop_data, next_trampoline_hop_hmac, new_trampoline_packet_bytes, trampoline_shared_secret, .. } => {
128+
(
129+
RoutingInfo::Trampoline {
130+
outgoing_node_id: next_trampoline_hop_data.outgoing_node_id,
131+
new_packet_bytes: new_trampoline_packet_bytes,
132+
next_hop_hmac: next_trampoline_hop_hmac,
133+
shared_secret: trampoline_shared_secret,
134+
current_path_key: None
135+
},
136+
next_trampoline_hop_data.amt_to_forward,
137+
next_trampoline_hop_data.outgoing_cltv_value,
138+
None,
139+
None
140+
)
141+
},
142+
#[cfg(trampoline)]
143+
onion_utils::Hop::TrampolineBlindedForward { outer_hop_data, next_trampoline_hop_data, next_trampoline_hop_hmac, new_trampoline_packet_bytes, trampoline_shared_secret, .. } => {
144+
let (amt_to_forward, outgoing_cltv_value) = check_blinded_forward(
145+
msg.amount_msat, msg.cltv_expiry, &next_trampoline_hop_data.payment_relay, &next_trampoline_hop_data.payment_constraints, &next_trampoline_hop_data.features
146+
).map_err(|()| {
147+
// We should be returning malformed here if `msg.blinding_point` is set, but this is
148+
// unreachable right now since we checked it in `decode_update_add_htlc_onion`.
149+
InboundHTLCErr {
150+
msg: "Underflow calculating outbound amount or cltv value for blinded forward",
151+
err_code: INVALID_ONION_BLINDING,
152+
err_data: vec![0; 32],
153+
}
154+
})?;
155+
(
156+
RoutingInfo::Trampoline {
157+
outgoing_node_id: next_trampoline_hop_data.outgoing_node_id,
158+
new_packet_bytes: new_trampoline_packet_bytes,
159+
next_hop_hmac: next_trampoline_hop_hmac,
160+
shared_secret: trampoline_shared_secret,
161+
current_path_key: outer_hop_data.current_path_key
162+
},
163+
amt_to_forward,
164+
outgoing_cltv_value,
165+
next_trampoline_hop_data.intro_node_blinding_point,
166+
next_trampoline_hop_data.next_blinding_override
167+
)
168+
},
102169
};
103170

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,
171+
let routing = match routing_info {
172+
RoutingInfo::Direct { short_channel_id, new_packet_bytes, next_hop_hmac } => {
173+
let outgoing_packet = msgs::OnionPacket {
174+
version: 0,
175+
public_key: next_packet_pubkey_opt.unwrap_or(Err(secp256k1::Error::InvalidPublicKey)),
176+
hop_data: new_packet_bytes,
177+
hmac: next_hop_hmac,
178+
};
179+
PendingHTLCRouting::Forward {
180+
onion_packet: outgoing_packet,
181+
short_channel_id,
182+
incoming_cltv_expiry: Some(msg.cltv_expiry),
183+
blinded: intro_node_blinding_point.or(msg.blinding_point)
184+
.map(|bp| BlindedForward {
185+
inbound_blinding_point: bp,
186+
next_blinding_override,
187+
failure: intro_node_blinding_point
188+
.map(|_| BlindedFailure::FromIntroductionNode)
189+
.unwrap_or(BlindedFailure::FromBlindedNode),
190+
}),
191+
}
192+
}
193+
#[cfg(trampoline)]
194+
RoutingInfo::Trampoline { outgoing_node_id, new_packet_bytes, next_hop_hmac, shared_secret, current_path_key } => {
195+
let next_trampoline_packet_pubkey = match next_packet_pubkey_opt {
196+
Some(Ok(pubkey)) => pubkey,
197+
_ => return Err(InboundHTLCErr {
198+
msg: "Missing next Trampoline hop pubkey from intermediate Trampoline forwarding data",
199+
err_code: 0x4000 | 22,
200+
err_data: Vec::new(),
201+
}),
202+
};
203+
let outgoing_packet = msgs::TrampolineOnionPacket {
204+
version: 0,
205+
public_key: next_trampoline_packet_pubkey,
206+
hop_data: new_packet_bytes,
207+
hmac: next_hop_hmac,
208+
};
209+
PendingHTLCRouting::TrampolineForward {
210+
incoming_shared_secret: shared_secret.secret_bytes(),
211+
onion_packet: outgoing_packet,
212+
node_id: outgoing_node_id,
213+
incoming_cltv_expiry: msg.cltv_expiry,
214+
blinded: intro_node_blinding_point.or(current_path_key)
215+
.map(|bp| BlindedForward {
216+
inbound_blinding_point: bp,
217+
next_blinding_override,
218+
failure: intro_node_blinding_point
219+
.map(|_| BlindedFailure::FromIntroductionNode)
220+
.unwrap_or(BlindedFailure::FromBlindedNode),
221+
})
222+
}
223+
}
109224
};
110225

111226
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-
},
227+
routing,
125228
payment_hash: msg.payment_hash,
126229
incoming_shared_secret: shared_secret,
127230
incoming_amt_msat: Some(msg.amount_msat),
@@ -167,6 +270,8 @@ pub(super) fn create_recv_pending_htlc_info(
167270
sender_intended_htlc_amt_msat, cltv_expiry_height, None, Some(payment_context),
168271
intro_node_blinding_point.is_none(), true, invoice_request)
169272
}
273+
#[cfg(trampoline)]
274+
onion_utils::Hop::TrampolineReceive { .. } => todo!(),
170275
onion_utils::Hop::Forward { .. } => {
171276
return Err(InboundHTLCErr {
172277
err_code: 0x4000|22,
@@ -181,6 +286,14 @@ pub(super) fn create_recv_pending_htlc_info(
181286
msg: "Got blinded non final data with an HMAC of 0",
182287
})
183288
},
289+
#[cfg(trampoline)]
290+
onion_utils::Hop::TrampolineForward { .. } | onion_utils::Hop::TrampolineBlindedForward { .. } => {
291+
return Err(InboundHTLCErr {
292+
err_code: 0x4000|22,
293+
err_data: Vec::new(),
294+
msg: "Got Trampoline non final data with an HMAC of 0",
295+
})
296+
},
184297
};
185298
// final_incorrect_cltv_expiry
186299
if onion_cltv_expiry > cltv_expiry {
@@ -391,7 +504,7 @@ where
391504
return_malformed_err!("Unknown onion packet version", 0x8000 | 0x4000 | 4);
392505
}
393506

394-
let encode_relay_error = |message: &str, err_code: u16, shared_secret: [u8; 32], data: &[u8]| {
507+
let encode_relay_error = |message: &str, err_code: u16, shared_secret: [u8; 32], trampoline_shared_secret: Option<[u8; 32]>, data: &[u8]| {
395508
if msg.blinding_point.is_some() {
396509
return_malformed_err!(message, INVALID_ONION_BLINDING)
397510
}
@@ -401,7 +514,7 @@ where
401514
channel_id: msg.channel_id,
402515
htlc_id: msg.htlc_id,
403516
reason: HTLCFailReason::reason(err_code, data.to_vec())
404-
.get_encrypted_failure_packet(&shared_secret, &None),
517+
.get_encrypted_failure_packet(&shared_secret, &trampoline_shared_secret),
405518
}));
406519
};
407520

@@ -413,8 +526,8 @@ where
413526
Err(onion_utils::OnionDecodeErr::Malformed { err_msg, err_code }) => {
414527
return_malformed_err!(err_msg, err_code);
415528
},
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]);
529+
Err(onion_utils::OnionDecodeErr::Relay { err_msg, err_code, shared_secret, trampoline_shared_secret }) => {
530+
return encode_relay_error(err_msg, err_code, shared_secret.secret_bytes(), trampoline_shared_secret.map(|tss| tss.secret_bytes()), &[0; 0]);
418531
},
419532
};
420533

@@ -434,7 +547,7 @@ where
434547
Ok((amt, cltv)) => (amt, cltv),
435548
Err(()) => {
436549
return encode_relay_error("Underflow calculating outbound amount or cltv value for blinded forward",
437-
INVALID_ONION_BLINDING, shared_secret.secret_bytes(), &[0; 32]);
550+
INVALID_ONION_BLINDING, shared_secret.secret_bytes(), None, &[0; 32]);
438551
}
439552
};
440553
let next_packet_pubkey = onion_utils::next_hop_pubkey(&secp_ctx,
@@ -444,6 +557,17 @@ where
444557
outgoing_cltv_value
445558
})
446559
}
560+
#[cfg(trampoline)]
561+
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, .. } => {
562+
let next_trampoline_packet_pubkey = onion_utils::next_hop_pubkey(secp_ctx,
563+
incoming_trampoline_public_key, &trampoline_shared_secret.secret_bytes());
564+
Some(NextPacketDetails {
565+
next_packet_pubkey: next_trampoline_packet_pubkey,
566+
outgoing_connector: HopConnector::Trampoline(outgoing_node_id),
567+
outgoing_amt_msat: amt_to_forward,
568+
outgoing_cltv_value,
569+
})
570+
}
447571
_ => None
448572
};
449573

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