Remove support for the legacy splicing protocol used by Phoenix#3262
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Remove support for the legacy splicing protocol used by Phoenix#3262
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We replace our experimental version of `splice_init`, `splice_ack` and `splice_locked` by their official version. If our peer is using the experimental feature bit, we convert our outgoing messages to use the experimental encoding and incoming messages to the official messages. We also change the TLV fields added to `tx_add_input`, `tx_signatures` and `splice_locked` to match the spec version. We always write both the official and experimental TLV to updated nodes (because the experimental one is odd and will be ignored) but we drop the official TLV if our peer is using the experimental feature, because it won't understand the even TLV field. We do the same thing for the `commit_sig` TLV. For peers who support the official splicing version, we insert the `start_batch` message before the batch of `commit_sig` messages. This guarantees backwards-compatibility with peers who only support the experimental feature.
We introduce a `retransmit_flags` field to `my_current_funding_locked` and `next_funding` to ask our peer to retransmit `commitment_signed` or `announcement_signatures` if we're expecting them. With this change, we don't need to retransmit `splice_locked` on reconnection anymore to trigger the exchange of `announcement_signatures`. We don't need to retransmit it to let our peer know that we've seen enough confirmations for the splice either, since `my_current_funding_locked` implies that. This allows us to completely remove retransmission of `splice_locked` on reconnection, and also get rid of the `your_last_funding_locked` TLV, which greatly simplifies the reconnection logic. We do keep them for backwards-compatibility with existing Phoenix users though, but we'll be able to clean it up once they have updated. Note that this works with taproot channels since we will simply provide nonces in `channel_reestablish` when we need our peer to send announcement signatures (not supported yet since taproot channels are never announced). We rollback using the `next_commitment_number` to let our peer know that we haven't received their `commit_sig` and instead use the retransmit flags added to the `next_funding` TLV, unless our peer is using the legacy splicing protocol.
We remove support for the legacy splicing protocol used by older Phoenix wallets. Phoenix users can simply update their app to get the latest version that supports the official splicing protocol.
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We remove support for the legacy splicing protocol used by older Phoenix wallets. Before merging this PR, we must:
phoenixandphoenixdthat includes Use official splice messages lightning-kmp#768Users that don't upgrade will not be able to reconnect once we deploy this change.
Builds on top of #2887