Fix possible dust HTLC sweep tx when feerate remains unchanged during a bump

[whfuyn]

Fix #3831

[ldk-reviews-bot]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.90%. Comparing base (97f0e4b) to head (ab132ab).
Report is 29 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3832      +/-   ##
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- Coverage   89.91%   89.90%   -0.01%     
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  Files         160      160              
  Lines      129307   129581     +274     
  Branches   129307   129581     +274     
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+ Hits       116270   116505     +235     
- Misses      10349    10383      +34     
- Partials     2688     2693       +5     

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[wpaulino]

Thanks! Do you mind updating the commit message to follow these guidelines?

[whfuyn]

Hi, @wpaulino.
Thanks for the feedback. I've revised the commit message according to the guideline. Let me know if any further revisions are needed.

[ldk-reviews-bot]

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[TheBlueMatt]

Hmm, yea, I guess this makes sense. I mean if we think we don't have enough value in an HTLC output for it to be worth claiming at the feerate we need I'm not entirely sure its worth bothering, but I guess better to build the valid transaction that we think won't get confirmed than not.

The patch itself is trivial so gonna go ahead and land.

[whfuyn]

Hmm, yea, I guess this makes sense. I mean if we think we don't have enough value in an HTLC output for it to be worth claiming at the feerate we need I'm not entirely sure its worth bothering, but I guess better to build the valid transaction that we think won't get confirmed than not.

The patch itself is trivial so gonna go ahead and land.

In my case, the HTLC output might contain RGB assets, so it's crucial to get it back.

I've also observed that HTLCs claimed by the remote party aren't removed from the transaction until node restart. This causes HTLC sweep transactions to be rejected due to spent inputs, which consequently results in repeated failed feerate bumps. I'm working to identify the issue.

[TheBlueMatt]

In my case, the HTLC output might contain RGB assets, so it's crucial to get it back.

Then this patch definitely doesn't suffice. You need to bring in additional fees to ensure you pay for the "invisible" value - probably want to move to anchor channels where you can that more easily.

I've also observed that HTLCs claimed by the remote party aren't removed from the transaction until node restart. This causes HTLC sweep transactions to be rejected due to spent inputs, which consequently results in repeated failed feerate bumps. I'm working to identify the issue.

Hmm, weird. Definitely let us know how it goes.