[lnwallet] Only Forward Committed Settles and Fails #1293
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Roasbeef
requested changes
May 28, 2018
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Nice! This is definitely a bug that has been lingering for some time. I've modified this patch locally to remove the initial "fix" commit and confirmed that the added test does indeed fail at the proper location.
Noted one minor aspect: in that we can make our assertion on forwarded fails more accurate to ensure the correct HTLC failure is forwarded, and not just any failure.
lnwallet/channel_test.go
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| t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+ | ||
| "forward %v htlcs", len(fwdPkg.Adds)) | ||
| } | ||
| if len(fwdPkg.SettleFails) != 1 { |
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We can strengthen this check a bit by ensuring the _proper failed HTLC is what's being forwarded.
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This PR fixes an issue that would cause us to forward a settle or fail prematurely, i.e. we would forward a settle or fail before it was fully committed by both commitment transactions.
Previously, we had such a check for
Addhtlcs, and ensure that neither theaddCommitHeightRemoteandaddCommitHeightLocalwere both non-zero. Here, we add the same constraints toremoveCommitHeightRemoteandremoveCommitHeightLocal.We also change the logic around when an
FailorSettleshould be forwarded by requiring equality between the remote height andremoveCommitHeightRemote. Currently, we use>=to determine when we should forward an HTLC in order to mimic the logic forAdds.This change is more minor, and shouldn't result in any observed difference in behavior, but should provide an additional protection against forwarding the same settle or fail twice. The difference lies in that
Addupdates can persist in the log across multiple commitments after being added, whileSettles andFails are always removed immediately after being locked in.Fixes #1124.
Fixes #1053.
Fixes #977.