Reject incoming HTLCs with a high cltv_expiry#3323
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We currently reject HTLCs with a `cltv_expiry` higher than 2 weeks in the future when sending them (in the `sendAdd` method). That's because they would lock up our funds for a long period of time if our peer decided to force-close. Also, a large `cltv_expiry` makes slow jamming easier. We now apply the same limits to incoming HTLCs for consistency (since they may differ by `cltv_expiry_delta`). Note that we don't do it in the `receiveAdd` function, which would trigger a force-close. We just accept those HTLCs and then fail them, since it is harmless to have them only temporarily in our commitment as long as we don't relay.
sstone
approved these changes
Jul 7, 2026
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We currently reject HTLCs with a
cltv_expiryhigher than 2 weeks in the future when sending them (in thesendAddmethod). That's because they would lock up our funds for a long period of time if our peer decided to force-close. Also, a largecltv_expirymakes slow jamming easier.We now apply the same limits to incoming HTLCs for consistency (since they may differ by
cltv_expiry_delta). Note that we don't do it in thereceiveAddfunction, which would trigger a force-close. We just accept those HTLCs and then fail them, since it is harmless to have them only temporarily in our commitment as long as we don't relay.