Add test for push_asset_amount underflow DoS on funding acceptor

[0xaudron]

The acceptor computed remote_rgb_amount = channel_rgb_amount - push_amount without checking push_amount <= channel_rgb_amount, so a counterparty sending a larger value underflowed it (release builds have overflow checks off), aborting RGB coloring and panicking the acceptor's event handler.

The REST layer clamps push_asset_amount, so reaching this needs a modified wire client; FORCE_WIRE_PUSH_ASSET_AMOUNT_ON_NODE models that by making the initiator emit an out-of-range value on the wire. The test asserts the acceptor rejects the funding and stays responsive.

Bumps rust-lightning to the commit rejecting out-of-range push_asset_amount in handle_funding.

[zoedberg]

Thank you! I requested some changes, also this branch has conflicts that must be resolved. Finally please do not commit the updated submodule pointer, I first would like to see the CI fail, then I'll push your fix on the upstream remote so you will be able to change the pointer without any change to the .gitmodules file

[0xaudron]

Addressed all review points: FORCE_PUSH_ASSET_AMOUNT_ON_NODE is now a simple on/off flag like IGNORE_INBOUND_CHANNELS_ON_NODE and uses NodeOverrideGuard (custom Drop removed), test and file renamed to push_asset_amount_above_chan_amt, the redundant connect_peer is gone, and the explanation lives only on the constant. Rebased on master and dropped the submodule pointer.

CI should now fail on the new test, ready for you to push the LDK fix upstream.

[zoedberg]

@0xaudron the CI cannot run because the branch has still conflicts that must be resolved. You should rebase this on top of the latest master tip. Please before the rebase also squash the commits into a single one

[0xaudron]

@zoedberg can you check it now ?

[zoedberg]

LGTM, I'm waiting for your rebase in RGB-Tools/rust-lightning#33 , after that I'll push the branch on the public repo so you can add a commit here that updates the submodule pointer

[0xaudron]

done @zoedberg

[zoedberg]

@0xaudron I pushed the branch, you can now add a commit here that updates the submodule pointer

[zoedberg]

@0xaudron I will add the commit myself, so we can then proceed to merging this

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.77%. Comparing base (463b244) to head (ce4a123).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #138      +/-   ##
==========================================
- Coverage   87.78%   87.77%   -0.01%     
==========================================
  Files          13       13              
  Lines        7613     7617       +4     
==========================================
+ Hits         6683     6686       +3     
- Misses        930      931       +1     

Flag	Coverage Δ
rust	87.77% <100.00%> (-0.01%)	⬇️

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