Consider currently confirmed FundingScope when claiming commitments by wpaulino · Pull Request #3980 · lightningdevkit/rust-lightning

wpaulino · 2025-07-31T18:20:18Z

Once a commitment transaction confirms, we may have outputs to claim. To determine whom the commitment transaction belongs to, we generally compare its txid against what we know be ours and the counterparty's. This, however, relies on being able to match on the expected FundingScope, such that we can produce the necessary output claims. Since a commitment transaction confirming implies that the funding transaction it spends has also confirmed, we rely on alternative_funding_confirmed to obtain the corresponding FundingScope.

ldk-reviews-bot · 2025-07-31T18:20:21Z

👋 Thanks for assigning @tankyleo as a reviewer!
I'll wait for their review and will help manage the review process.
Once they submit their review, I'll check if a second reviewer would be helpful.

codecov · 2025-07-31T18:29:30Z

Codecov Report

❌ Patch coverage is 82.82209% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.91%. Comparing base (de2005a) to head (775f3d9).
⚠️ Report is 37 commits behind head on main.

Files with missing lines	Patch %	Lines
lightning/src/chain/channelmonitor.rs	82.60%	23 Missing and 5 partials ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #3980 +/- ##
==========================================
- Coverage 88.93% 88.91% -0.03% 
==========================================
Files 174 174 Lines 124539 125065 +526 Branches 124539 125065 +526 ==========================================
+ Hits 110758 111196 +438 - Misses 11287 11361 +74 - Partials 2494 2508 +14

Flag	Coverage Δ
fuzzing	`22.13% <44.17%> (-0.06%)`	⬇️
tests	`88.73% <82.82%> (-0.03%)`	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

ldk-reviews-bot · 2025-08-04T00:01:02Z

🔔 1st Reminder

Hey @TheBlueMatt! This PR has been waiting for your review.
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.

ldk-reviews-bot · 2025-08-05T15:27:22Z

👋 The first review has been submitted!

Do you think this PR is ready for a second reviewer? If so, click here to assign a second reviewer.

ldk-reviews-bot · 2025-08-05T22:26:28Z

✅ Added second reviewer: @tankyleo

TheBlueMatt

Generally fine, at least once the parent PR lands, but I'm still confused on #3980 (comment)

TheBlueMatt · 2025-08-06T17:17:15Z

Needs rebase, also might be worth addressing #3939 (comment) here but up to you.

TheBlueMatt

Does load_outputs_to_watch need to look at alternative fundings?

TheBlueMatt · 2025-08-07T13:31:23Z

Oh, also we'll need to do something with build_counterparty_commitment_tx/counterparty_commitment_txs_from_update and sign_to_local_justice_tx

ldk-reviews-bot · 2025-08-07T22:27:23Z

🔔 1st Reminder

Hey @tankyleo! This PR has been waiting for your review.
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.

wpaulino · 2025-08-07T23:06:28Z

Does load_outputs_to_watch need to look at alternative fundings?

It already does for register_tx calls. For register_output calls, outputs are not directly associated with the FundingScope they originated from (though there's no reason why they shouldn't, can do if you think it's worth it), so we're tracking them all even for FundingScopes no longer relevant.

build_counterparty_commitment_tx/counterparty_commitment_txs_from_update

Given their current usage, it's not required to change them but definitely worth changing. I already have the change in a separate branch. build_counterparty_commitment_tx is currently only used when we expect to have one FundingScope, so using self.funding is always safe. For the multi-commitment counterparty updates, the commitment transactions already included the scope specific data when they were built.

sign_to_local_justice_tx

Already had this change as well, just didn't include it here.

tankyleo

LGTM on first pass, will take another pass first thing tomorrow :) Thanks for the cleanup in check_spend_holder_transaction

tankyleo · 2025-08-08T19:13:59Z

 if *conf_height == height {
 self.alternative_funding_confirmed.take();
- if self.holder_tx_signed {
+ if self.holder_tx_signed || self.funding_spend_seen {


When the alternative_funding_confirmed gets reorged out, in which cases would we not broadcast the holder commitment ?

We could be lockdown_from_offchain from a ChannelForceClosed update where should_broadcast is false, but that means we never attempted to broadcast the funding transaction.

Do we also not broadcast if we haven't given a holder tx to OnchainTxHandler AND we haven't seen a commitment transaction hit the chain ?

Also if should_broadcast is false, then is_funding_broadcast back in channel is false, then not sure how alternative_funding_confirmed can be Some ?

Not sure I'm following your line of questioning here. We only want to broadcast if we already did, or if we've seen a commitment transaction confirm. In any other cases, either we're not supposed to broadcast because we were told not to or alternative_funding_confirmed is not relevant at all and the code here is unreachable.

Right ok thank you !
Want to confirm: if the funding gets reorged out, but we haven't signed a holder tx, and we haven't seen a commit tx hit the chain, we do NOT broadcast :)

tankyleo · 2025-08-08T22:17:57Z

Finished second pass

We generally want to hard assert on cases that could cause us to lose money.

We can't rely waiting on another (or the same) renegotiated funding transaction to confirm, since it may never happen. We also don't want to rely on the counterparty to broadcast for us, or require manual intervention from the user, so we choose to broadcast the new holder commitment immediately. This ensures we're able to claim funds from an already force closed channel after an alternative funding reorg.

ldk-reviews-bot · 2025-08-11T00:00:22Z

🔔 1st Reminder

Hey @TheBlueMatt! This PR has been waiting for your review.
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.

Once a commitment transaction confirms, we may have outputs to claim. To determine whom the commitment transaction belongs to, we generally compare its `txid` against what we know be ours and the counterparty's. This, however, relies on being able to match on the expected `FundingScope`, such that we can produce the necessary output claims. Since a commitment transaction confirming implies that the funding transaction it spends has also confirmed, we rely on `alternative_funding_confirmed` to obtain the corresponding `FundingScope`.

It's best to let the caller decide what the appropriate `ChannelTransactionParameters` are as it has the most context.

Since there may be multiple counterparty commitment transactions for the same commitment number due to splicing, we have to locate the matching `FundingScope::channel_parameters` to provide the signer. Since this is intended to be called during `Persist::update_persisted_channel`, the monitor should have already had the update applied.

wpaulino requested a review from TheBlueMatt July 31, 2025 18:20

wpaulino self-assigned this Jul 31, 2025

wpaulino mentioned this pull request Jul 31, 2025
Broadcast holder commitment for currently confirmed funding #3939
Merged

TheBlueMatt reviewed Aug 5, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs Outdated
Comment threadlightning/src/chain/channelmonitor.rs Outdated
Comment threadlightning/src/chain/channelmonitor.rs Outdated
Comment threadlightning/src/chain/channelmonitor.rs Outdated

wpaulino force-pushed the splice-commitment-claims branch from 5ecc866 to 379edfcCompare August 5, 2025 18:53

wpaulino requested a review from TheBlueMatt August 5, 2025 18:54

TheBlueMatt reviewed Aug 5, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs Outdated

wpaulino force-pushed the splice-commitment-claims branch from 379edfc to 4e03e45Compare August 5, 2025 22:25

ldk-reviews-bot requested a review from tankyleo August 5, 2025 22:26

graphite-appBot reviewed Aug 5, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs

wpaulino requested a review from TheBlueMatt August 5, 2025 22:55

TheBlueMatt reviewed Aug 5, 2025
View reviewed changes

wpaulino force-pushed the splice-commitment-claims branch from 4e03e45 to 53e1c59Compare August 7, 2025 03:12

wpaulino requested a review from TheBlueMatt August 7, 2025 03:13

TheBlueMatt reviewed Aug 7, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs Outdated
Comment threadlightning/src/chain/channelmonitor.rs Outdated

wpaulino added this to Weekly Goals Aug 7, 2025

tankyleo reviewed Aug 8, 2025
View reviewed changes

wpaulino force-pushed the splice-commitment-claims branch from 53e1c59 to e15e131Compare August 8, 2025 17:47

wpaulino requested review from TheBlueMatt and tankyleo August 8, 2025 17:47

tankyleo reviewed Aug 8, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs

tankyleo reviewed Aug 8, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs Outdated

tankyleo reviewed Aug 8, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs Outdated

wpaulino added 3 commits August 8, 2025 15:29

Add note for alternative_funding_confirmed assertion in promote_funding
c5763db

Make splice-funding confirmation assertions non-debug
5d7a3f2
We generally want to hard assert on cases that could cause us to lose money.

wpaulino force-pushed the splice-commitment-claims branch from e15e131 to c5c1e22Compare August 8, 2025 22:30

wpaulino requested a review from tankyleo August 8, 2025 22:30

tankyleo reviewed Aug 8, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs Outdated

tankyleo reviewed Aug 8, 2025
View reviewed changes

Comment threadlightning/src/chain/channelmonitor.rs Outdated

wpaulino force-pushed the splice-commitment-claims branch from c5c1e22 to 110e424Compare August 11, 2025 15:20

wpaulino added 3 commits August 11, 2025 08:23

Make channel_parameters explicit to build_counterparty_commitment_tx
08892b5
It's best to let the caller decide what the appropriate `ChannelTransactionParameters` are as it has the most context.

wpaulino requested a review from tankyleo August 11, 2025 15:23

wpaulino force-pushed the splice-commitment-claims branch from 110e424 to 775f3d9Compare August 11, 2025 15:23

TheBlueMatt approved these changes Aug 11, 2025
View reviewed changes

tankyleo approved these changes Aug 11, 2025
View reviewed changes

TheBlueMatt merged commit 6a4169d into lightningdevkit:mainAug 11, 2025
25 checks passed

github-project-automationBot moved this to Done in Weekly Goals Aug 11, 2025

wpaulino deleted the splice-commitment-claims branch August 11, 2025 20:51

Uh oh!

Conversation

wpaulino commented Jul 31, 2025• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

ldk-reviews-bot commented Jul 31, 2025• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

codecovBot commented Jul 31, 2025• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

ldk-reviews-bot commented Aug 4, 2025

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

ldk-reviews-bot commented Aug 5, 2025

Uh oh!

Uh oh!

ldk-reviews-bot commented Aug 5, 2025

Uh oh!

Uh oh!

TheBlueMatt left a comment

Choose a reason for hiding this comment

Uh oh!

TheBlueMatt commented Aug 6, 2025

Uh oh!

TheBlueMatt left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

TheBlueMatt commented Aug 7, 2025

Uh oh!

ldk-reviews-bot commented Aug 7, 2025

Uh oh!

wpaulino commented Aug 7, 2025

Uh oh!

tankyleo left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

tankyleoAug 8, 2025

Choose a reason for hiding this comment

Uh oh!

wpaulinoAug 8, 2025

Choose a reason for hiding this comment

Uh oh!

tankyleoAug 11, 2025• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

tankyleoAug 11, 2025

Choose a reason for hiding this comment

Uh oh!

wpaulinoAug 11, 2025

Choose a reason for hiding this comment

Uh oh!

tankyleoAug 11, 2025

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

tankyleo commented Aug 8, 2025

Uh oh!

Uh oh!

Uh oh!

ldk-reviews-bot commented Aug 11, 2025

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

wpaulino commented Jul 31, 2025•
edited
Loading

ldk-reviews-bot commented Jul 31, 2025•
edited
Loading

codecovBot commented Jul 31, 2025•
edited
Loading

tankyleo left a comment •
edited
Loading

tankyleoAug 11, 2025•
edited
Loading