Fix debug panic in the case where a first hop has a channel with an introduction node #2503
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TheBlueMatt
previously approved these changes
Aug 17, 2023
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Fuzzer disagrees with you, it definitely knows how to get this :). |
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Well you're running the main fuzzers, so I won't know if it gets it unless you tell me lol. Lmk if it got anything else. |
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I mean you can run it too, there's nothing special about me :) |
valentinewallace
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Added another fix and test for this failing fuzz input: https://pastebin.com/GtCUpwEd |
This previously led to a debug panic in the router because we wouldn't account for the blinded path fee when calculating first_hop<>intro_node hop's available liquidity and construct an invalid path that forwarded more over said hop than was actually available. This also led to us hitting unreachable code, see direct_to_matching_intro_nodes test description.
valentinewallace
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TheBlueMatt
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Aug 24, 2023
tnull
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Aug 25, 2023
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Previously, we wouldn't account for the blinded path fee when calculating a
first_hop<>intro_nodehop's available liquidity, and construct an invalid path that forwarded more over said hop than was actually available, leading to a debug panic.I'm not sure why the fuzzer didn't catch this. I don't see anything stopping it from generating routes where we have a direct channel between a first hop and an intro node? But I also don't have the strongest understanding of the art of our fuzzing framework. Seems like a candidate for the post-BOLT12 "let's focus on paying down tech debt" quarter.<- the fuzzer did catch it actually