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Handle receiving payments via Trampoline #3670

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Merged
merged 9 commits into from
Mar 28, 2025
Merged

Handle receiving payments via Trampoline #3670

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4741892
Remove Trampoline config flag
arik-so Mar 26, 2025
0c82cc2
Make Trampoline inbound MPP data optional
arik-so Mar 17, 2025
a293d21
Fix blinded Trampoline TLV IDs
arik-so Mar 17, 2025
313f344
De-macro `return_malformed_err`
arik-so Mar 26, 2025
23b4c80
Propagate Trampoline blinding errors
arik-so Mar 26, 2025
dc14f26
Implement `Writeable` for `TrampolineForwardTlvs`
arik-so Mar 17, 2025
35ff142
Handle Trampoline receives
arik-so Mar 17, 2025
a6f4c7f
Test unblinded Trampoline receives
arik-so Mar 25, 2025
3970f1d
Test rejection of Trampoline forwards
arik-so Mar 26, 2025
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2 changes: 1 addition & 1 deletion lightning/src/ln/onion_payment.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -466,7 +466,7 @@ where
{
let encode_malformed_error = |message: &str, err_code: u16| {
log_info!(logger, "Failed to accept/forward incoming HTLC: {}", message);
let (sha256_of_onion, failure_code) = if msg.blinding_point.is_some() {
let (sha256_of_onion, failure_code) = if msg.blinding_point.is_some() || err_code == INVALID_ONION_BLINDING {
([0; 32], INVALID_ONION_BLINDING)
} else {
(Sha256::hash(&msg.onion_routing_packet.hop_data).to_byte_array(), err_code)
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64 changes: 54 additions & 10 deletions lightning/src/ln/onion_utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1821,16 +1821,60 @@ where
trampoline_shared_secret,
),
}),
Ok((_, None)) => Err(OnionDecodeErr::Malformed {
err_msg: "Non-final Trampoline onion data provided to us as last hop",
// todo: find more suitable error code
err_code: 0x4000 | 22,
}),
Ok((_, Some(_))) => Err(OnionDecodeErr::Malformed {
err_msg: "Final Trampoline onion data provided to us as intermediate hop",
// todo: find more suitable error code
err_code: 0x4000 | 22,
}),
Ok((msgs::InboundTrampolinePayload::BlindedForward(hop_data), None)) => {
if hop_data.intro_node_blinding_point.is_some() {
return Err(OnionDecodeErr::Relay {
err_msg: "Non-final intro node Trampoline onion data provided to us as last hop",
err_code: INVALID_ONION_BLINDING,
Comment on lines +1826 to +1828
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@carlaKC carlaKC Mar 31, 2025 •
edited
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I believe that using the combination of Relay + INVALID_ONION_BLINDING here will result in sending an invalid_onion_blinding message with no sha256_of_onion data attached because the caller always sets empty data for the Relay type.

Although the spec allows zero values here, my understanding is that we still need to include the empty data?

We don't hit an issue in the code today because there isn't an assertion in reason for INVALID_ONION_BLINDING. I ran into this during a rebase for #3601 which adds an assertion that there is 32 bytes of data present for this error code.

Also totally possible that I'm missing some trampoline context, and that check should just not be added in the first place!

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This was ultimately resolved by switching to InvalidOnionPayloadrather than InvalidOnionBlinding.

shared_secret,
trampoline_shared_secret: Some(SharedSecret::from_bytes(
trampoline_shared_secret,
)),
});
}
Err(OnionDecodeErr::Malformed {
err_msg: "Non-final Trampoline onion data provided to us as last hop",
err_code: INVALID_ONION_BLINDING,
})
},
Ok((msgs::InboundTrampolinePayload::BlindedReceive(hop_data), Some(_))) => {
if hop_data.intro_node_blinding_point.is_some() {
return Err(OnionDecodeErr::Relay {
err_msg: "Final Trampoline intro node onion data provided to us as intermediate hop",
err_code: 0x4000 | 22,
shared_secret,
trampoline_shared_secret: Some(SharedSecret::from_bytes(
trampoline_shared_secret,
)),
});
}
Err(OnionDecodeErr::Malformed {
err_msg:
"Final Trampoline onion data provided to us as intermediate hop",
err_code: INVALID_ONION_BLINDING,
})
},
Ok((msgs::InboundTrampolinePayload::Forward(_), None)) => {
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I like that these variants are spelled out explicitly now, reads more obviously correct 👍

Err(OnionDecodeErr::Relay {
err_msg: "Non-final Trampoline onion data provided to us as last hop",
err_code: 0x4000 | 22,
shared_secret,
trampoline_shared_secret: Some(SharedSecret::from_bytes(
trampoline_shared_secret,
)),
})
},
Ok((msgs::InboundTrampolinePayload::Receive(_), Some(_))) => {
Err(OnionDecodeErr::Relay {
err_msg:
"Final Trampoline onion data provided to us as intermediate hop",
err_code: 0x4000 | 22,
shared_secret,
trampoline_shared_secret: Some(SharedSecret::from_bytes(
trampoline_shared_secret,
)),
})
},
Err(e) => Err(e),
}
},
Expand Down