Reestablish partially signed splice with current remote_commitment_number
#2965
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…umber` As pointed out in lightning/bolts#1214, when reconnecting a partially signed `interactive-tx` session, we should set `next_commitment_number` to the current commitment number if we haven't received our peer's `commit_sig`, which tells them they need to retransmit it. That's not what we're currently doing: we're currently setting this value to the next commitment number, regardless of whether or not we have received our peer's `commit_sig`. And we always retransmit our `commit_sig` if our peer is setting `next_funding_txid`, even if they have already received it. More importantly, if our peer behaves correctly and sends us the current commitment number, we will think that they're late and will halt, waiting for them to send `error`. This commit fixes that by allowing our peers to use the current commitment number when they set `next_funding_txid`. Note that this doesn't yet make us spec-compliant, but in order to guarantee backwards-compatibility, we must first deploy that change before we can start removing spurious `commit_sig` retransmissions.
This was referenced Dec 13, 2024
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As pointed out in lightning/bolts#1214, when reconnecting a partially signed
interactive-txsession, we should setnext_commitment_numberto the current commitment number if we haven't received our peer'scommit_sig, which tells them they need to retransmit it.That's not what we're currently doing: we're currently setting this value to the next commitment number, regardless of whether or not we have received our peer's
commit_sig. And we always retransmit ourcommit_sigif our peer is settingnext_funding_txid, even if they have already received it.More importantly, if our peer behaves correctly and sends us the current commitment number, we will think that they're late and will halt, waiting for them to send
error. This commit fixes that by allowing our peers to use the current commitment number when they setnext_funding_txid.Note that this doesn't yet make us spec-compliant, but in order to guarantee backwards-compatibility, we must first deploy that change before we can start removing spurious
commit_sigretransmissions.