[0.0.123] Don't attempt to resume channels if we already exchanged funding

[TheBlueMatt]

ddf75af introduced the ability to re-exchange our ChannelOpen after a peer disconnects if we didn't complete funding on our end. It did not implement nor consider what would happen if we re-connected after we created our own funding transactions, and currently it panics (and even if it did not it would replay the FundingTransactionGenerated event to users).

This addresses this in a temporary fashion to fix the immediate panic for 0.0.123, allowing us to fix the issue more fully later.

Note that this branch is not targeting upstream but rather the 0.0.123 branch.

[valentinewallace]

Is this method necessary? It seems like have_received_message() should cover it, I don't see how we could be beyond the initial commitment number if we've only just sent our init 🤔 I'm ok with it because it makes the callsite more readable, though.

[TheBlueMatt]

Yea, I think they're redundant, I just figured we should do the thing that matches the two panics below exactly rather than trying to avoid the extra check. I also like having the callsites be more readable so went with a new method :).

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.44%. Comparing base (d25d55a) to head (21ab2dc).
Report is 22 commits behind head on 0.0.123.

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Additional details and impacted files

@@             Coverage Diff             @@
##           0.0.123    #3034      +/-   ##
===========================================
+ Coverage    89.15%   89.44%   +0.29%     
===========================================
  Files          118      118              
  Lines        97521    99738    +2217     
  Branches     97521    99738    +2217     
===========================================
+ Hits         86941    89211    +2270     
+ Misses        8343     8272      -71     
- Partials      2237     2255      +18     

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[TheBlueMatt]

Squash-pushed comment fix:

$ git diff-tree -U2 4c1019fd 21ab2dc2
diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs
index 43abe62d3..e45e4320a 100644
--- a/lightning/src/ln/functional_tests.rs
+++ b/lightning/src/ln/functional_tests.rs
@@ -3767,7 +3767,7 @@ fn test_peer_disconnected_before_funding_broadcasted() {
 	}

-	// Ensure that the channel is closed with `ClosureReason::HolderForceClosed`
-	// when the peers are disconnected and do not reconnect before the funding
-	// transaction is broadcasted.
+	// Ensure that the channel is closed with `ClosureReason::DisconnectedPeer` and a
+	// `DiscardFunding` event when the peers are disconnected and do not reconnect before the
+	// funding transaction is broadcasted.
 	check_closed_event!(&nodes[0], 2, ClosureReason::DisconnectedPeer, true
 		, [nodes[1].node.get_our_node_id()], 1000000);

[shaavan]

Looks like a reasonable fix until we can get the #2983 working!
Hopefully, I will get that running properly very soon!

[valentinewallace]

Just checked and CI failures look unrelated. Gonna land this since it's a trivial patch, looks good to @shaavan, and the test coverage repros the bug on main as expected.