add `expiry_time` to `PendingOutboundPayment::StaticInvoiceReceived` by a-mpch · Pull Request #3918 · lightningdevkit/rust-lightning

a-mpch · 2025-07-08T19:49:47Z

Context

This is a follow up to Matt's comment from #3140

Whenever paying to an often-offline node and invoice has an expiration time of weeks / months / years and node does not come online soonish we would hold the HTLC for the entire time until "we remember that have to do something about it"

Solution

This sets a expiry_time to StaticInvoiceReceived using StaleExpiration that is defaulted (hardcoded) to one week. Then is used to time out any HTLC pending after that expiration time.

Some decisions over the way:

I thought that this flag is too scoped to async payments, so adding it to a router config would be more noise than actually useful.
Is not configurable. Like expiration time while waiting offers is not configurable, this one neither.

Not really sure about not being configurable but maybe is worth changing it in a follow up when being used.

ldk-reviews-bot · 2025-07-08T19:49:50Z

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a-mpch · 2025-07-09T18:49:24Z

It is weird that mutants modify the constant to check for tests. Is it because we want to test based on the constant ? 🤔

fuzz failed because of a memory issue on the vm

valentinewallace · 2025-07-09T18:59:06Z

 (6, route_params, required),
 (8, invoice_request, required),
 (10, static_invoice, required),
+ (12, expiry_time, required),


This variant probably hasn't been written, but IMO we should still set the TLV type to an odd value to support downgrading from 0.2+ to 0.1. We can also set a default_value of 0, I think, so downgrading to 0.1 then upgrading would result in immediately timing out the payment, though it would be good to include a release note for that.
Suggestion:
Suggested change
(12, expiry_time,required),
(11, expiry_time,(default_value,StaleExpiration::AbsoluteTimeout(Duration::from_secs(0))),
+ a release note for the downgrade/upgrade behavior. Let me know if that doesn't make sense.

oh would that mean that when upgrading from 0.1 to 0.2+ and default value is zero, everything from previous version would be timed out too?
Maybe being optional is better in this case and manage the None case as no expiry_time 🤔

Added a commit using None I'm not loving it but kinda of works

No one's using this feature yet almost certainly, so honestly I'd prefer to just time out payments when going from 0.1 to 0.2+ and having a release note noting that this will happen, so we can avoid the Option.

ldk-reviews-bot · 2025-07-09T18:59:34Z

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a-mpch · 2025-07-09T22:41:01Z

So I rebased it and added fixups for all comments beside the TLVs. That probable the default value being None is better.
My second thought on that issue is how can we tests these upgrade/downgrade mechanisms 🤔

valentinewallace · 2025-07-10T15:41:33Z

My second thought on that issue is how can we tests these upgrade/downgrade mechanisms 🤔

IMO we're alright on upgrade/downgrade tests, I don't think anyone's using this feature

a-mpch · 2025-07-10T16:54:55Z

great, all comments should be addressed. I leave the fixup so changes are clear.

ldk-reviews-bot · 2025-07-14T00:01:02Z

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ldk-reviews-bot · 2025-07-16T00:01:41Z

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Please take a look when you have a chance. If you're unable to review, please let us know so we can find another reviewer.

valentinewallace

Sorry for the delay, feel free to squash!

Previous this commit if the StaticInvoice has an expiration time of months or years would make our HTLC to hold for that time until is abandoned. This patch adds a defaults of 1 week of expiry time that the HTLC will be held waiting for the often-offline node comes online.

a-mpch · 2025-07-18T05:07:30Z

thanks! rebased with all changes

codecov · 2025-07-18T05:16:19Z

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.00%. Comparing base (eae2bb1) to head (11ceee8).
Report is 32 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #3918 +/- ##
==========================================
- Coverage 89.02% 89.00% -0.02% 
==========================================
Files 166 166 Lines 121374 121377 +3 Branches 121374 121377 +3 ==========================================
- Hits 108049 108034 -15 - Misses 10927 10935 +8 - Partials 2398 2408 +10

Flag	Coverage Δ
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valentinewallace

LGTM, landing with 1 review

ldk-reviews-bot requested a review from valentinewallace July 8, 2025 20:00

valentinewallace reviewed Jul 9, 2025
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a-mpch force-pushed the 2025-07-expiry-time-static-invoice-received branch from 9b282a4 to 58b51a5Compare July 9, 2025 22:38

a-mpch force-pushed the 2025-07-expiry-time-static-invoice-received branch 2 times, most recently from 2a7c9a2 to e3bc8c3Compare July 10, 2025 16:48

graphite-appBot reviewed Jul 10, 2025
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Comment threadlightning/src/ln/async_payments_tests.rs Outdated

a-mpch requested a review from valentinewallace July 11, 2025 16:10

valentinewallace reviewed Jul 17, 2025
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Comment threadlightning/src/ln/outbound_payment.rs Outdated
Comment threadlightning/src/ln/outbound_payment.rs Outdated
Comment threadlightning/src/ln/outbound_payment.rs Outdated

a-mpch force-pushed the 2025-07-expiry-time-static-invoice-received branch from 9b548bc to 11ceee8Compare July 18, 2025 05:06

a-mpch requested a review from valentinewallace July 18, 2025 05:07

graphite-appBot reviewed Jul 18, 2025
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Comment threadlightning/src/ln/async_payments_tests.rs
Comment threadlightning/src/ln/outbound_payment.rs

valentinewallace approved these changes Jul 18, 2025
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valentinewallace merged commit 2f9898c into lightningdevkit:mainJul 18, 2025
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valentinewallace mentioned this pull request Jul 1, 2025
Async Payments #2298
Closed
45 tasks

	(12, expiry_time,required),
	(11, expiry_time,(default_value,StaleExpiration::AbsoluteTimeout(Duration::from_secs(0))),

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a-mpch commented Jul 8, 2025

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