Fix HTLC-output-in-commitment sorting for duplicate-HTLCs #319
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This resolves both an issue that hits fuzzing due to hash collisions as well as implements an update to the BOLT spec.
TheBlueMatt
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Lightning doesn't (currently) do any input sorting at the protocol level, but if we ever need to re-add this its in git history.
TheBlueMatt
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good first issue
ariard
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Mar 12, 2019
| // Note that due to hash collisions, we have to have a fallback comparison | ||
| // here for fuzztarget mode (otherwise at least chanmon_fail_consistency | ||
| // may fail)! | ||
| .then(a_htlc.0.payment_hash.0.cmp(&b_htlc.0.payment_hash.0)) |
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Hmm didn't get you there, if offered HTLC A and offered HTLC B have same pubkey script, isn't it implied that they have same payment hash, as per BOLT-3, hash is part of script and it's the only diff for HTLCs with same per commitment point ?
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Not in fuzztarget, in fuzztarget hashes are just (roughly) the whole input xor'd together, with 31 bytes being set to 0s. Thus, its rather trivial to have different payment hashes have the same script_pubkey.
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This resolves both an issue that hits fuzzing due to hash
collisions as well as implements an update to the BOLT spec.
Also removes the input sorting.