From weintraub.b at northeastern.edu Tue Dec 13 14:51:17 2022 From: weintraub.b at northeastern.edu (Benjamin Weintraub) Date: Tue, 13 Dec 2022 14:51:17 +0000 Subject: [Lightning-dev] Unclear HTLC scenario Message-ID: Hi list, I have a question about how update_fail_htlcs are handled. Consider this scenario: a node, potentially adversarial, forwards an HTLC along a channel that does not have the funds to support a payment of that size. How does the recipient of the HTLC respond? I see this line in BOLT #2: ?until the corresponding HTLC is irrevocably committed in both sides' commitment transactions: MUST NOT send an update_fulfill_htlc, update_fail_htlc, or update_fail_malformed_htlc" But this seems confusing to me in the context of the scenario I suggested. Is it saying that even though the channel cannot support the payment, the nodes still need to commit to it? I assume that this interpretation is not correct, but then when is it okay for a node to send an update_fail_htlc? Immediately upon receiving an invalid transaction? Any insight you could provide would be great. Thanks in advance, Ben -------------- next part -------------- An HTML attachment was scrubbed... URL: