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Add FundingNeeded event for splicing #4290

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Add FundingNeeded event for splicing #4290

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3e57ec4
Use struct instead of enum for SpliceContribution
jkczyz Dec 2, 2025
2244a31
Use Amount in calculate_change_output_value
jkczyz Dec 4, 2025
f34cec3
Check change value in test_splice_in
jkczyz Dec 4, 2025
175bf79
Mixed mode splicing
jkczyz Dec 4, 2025
3448da2
f - calculate net_value
jkczyz Dec 10, 2025
f5933e5
WIP: Add FundingNeeded event for splicing
jkczyz Dec 18, 2025
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68 changes: 24 additions & 44 deletions fuzz/src/chanmon_consistency.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1860,11 +1860,8 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {

0xa0 => {
let input = FundingTxInput::new_p2wpkh(coinbase_tx.clone(), 0).unwrap();
let contribution = SpliceContribution::SpliceIn {
value: Amount::from_sat(10_000),
inputs: vec![input],
change_script: None,
};
let contribution =
SpliceContribution::splice_in(Amount::from_sat(10_000), vec![input], None);
let funding_feerate_sat_per_kw = fee_est_a.ret_val.load(atomic::Ordering::Acquire);
if let Err(e) = nodes[0].splice_channel(
&chan_a_id,
Expand All @@ -1882,11 +1879,8 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
},
0xa1 => {
let input = FundingTxInput::new_p2wpkh(coinbase_tx.clone(), 1).unwrap();
let contribution = SpliceContribution::SpliceIn {
value: Amount::from_sat(10_000),
inputs: vec![input],
change_script: None,
};
let contribution =
SpliceContribution::splice_in(Amount::from_sat(10_000), vec![input], None);
let funding_feerate_sat_per_kw = fee_est_b.ret_val.load(atomic::Ordering::Acquire);
if let Err(e) = nodes[1].splice_channel(
&chan_a_id,
Expand All @@ -1904,11 +1898,8 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
},
0xa2 => {
let input = FundingTxInput::new_p2wpkh(coinbase_tx.clone(), 0).unwrap();
let contribution = SpliceContribution::SpliceIn {
value: Amount::from_sat(10_000),
inputs: vec![input],
change_script: None,
};
let contribution =
SpliceContribution::splice_in(Amount::from_sat(10_000), vec![input], None);
let funding_feerate_sat_per_kw = fee_est_b.ret_val.load(atomic::Ordering::Acquire);
if let Err(e) = nodes[1].splice_channel(
&chan_b_id,
Expand All @@ -1926,11 +1917,8 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
},
0xa3 => {
let input = FundingTxInput::new_p2wpkh(coinbase_tx.clone(), 1).unwrap();
let contribution = SpliceContribution::SpliceIn {
value: Amount::from_sat(10_000),
inputs: vec![input],
change_script: None,
};
let contribution =
SpliceContribution::splice_in(Amount::from_sat(10_000), vec![input], None);
let funding_feerate_sat_per_kw = fee_est_c.ret_val.load(atomic::Ordering::Acquire);
if let Err(e) = nodes[2].splice_channel(
&chan_b_id,
Expand Down Expand Up @@ -1958,12 +1946,10 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
.map(|chan| chan.outbound_capacity_msat)
.unwrap();
if outbound_capacity_msat >= 20_000_000 {
let contribution = SpliceContribution::SpliceOut {
outputs: vec![TxOut {
value: Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS),
script_pubkey: coinbase_tx.output[0].script_pubkey.clone(),
}],
};
let contribution = SpliceContribution::splice_out(vec![TxOut {
value: Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS),
script_pubkey: coinbase_tx.output[0].script_pubkey.clone(),
}]);
let funding_feerate_sat_per_kw =
fee_est_a.ret_val.load(atomic::Ordering::Acquire);
if let Err(e) = nodes[0].splice_channel(
Expand All @@ -1989,12 +1975,10 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
.map(|chan| chan.outbound_capacity_msat)
.unwrap();
if outbound_capacity_msat >= 20_000_000 {
let contribution = SpliceContribution::SpliceOut {
outputs: vec![TxOut {
value: Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS),
script_pubkey: coinbase_tx.output[1].script_pubkey.clone(),
}],
};
let contribution = SpliceContribution::splice_out(vec![TxOut {
value: Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS),
script_pubkey: coinbase_tx.output[1].script_pubkey.clone(),
}]);
let funding_feerate_sat_per_kw =
fee_est_b.ret_val.load(atomic::Ordering::Acquire);
if let Err(e) = nodes[1].splice_channel(
Expand All @@ -2020,12 +2004,10 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
.map(|chan| chan.outbound_capacity_msat)
.unwrap();
if outbound_capacity_msat >= 20_000_000 {
let contribution = SpliceContribution::SpliceOut {
outputs: vec![TxOut {
value: Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS),
script_pubkey: coinbase_tx.output[1].script_pubkey.clone(),
}],
};
let contribution = SpliceContribution::splice_out(vec![TxOut {
value: Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS),
script_pubkey: coinbase_tx.output[1].script_pubkey.clone(),
}]);
let funding_feerate_sat_per_kw =
fee_est_b.ret_val.load(atomic::Ordering::Acquire);
if let Err(e) = nodes[1].splice_channel(
Expand All @@ -2051,12 +2033,10 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
.map(|chan| chan.outbound_capacity_msat)
.unwrap();
if outbound_capacity_msat >= 20_000_000 {
let contribution = SpliceContribution::SpliceOut {
outputs: vec![TxOut {
value: Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS),
script_pubkey: coinbase_tx.output[2].script_pubkey.clone(),
}],
};
let contribution = SpliceContribution::splice_out(vec![TxOut {
value: Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS),
script_pubkey: coinbase_tx.output[2].script_pubkey.clone(),
}]);
let funding_feerate_sat_per_kw =
fee_est_c.ret_val.load(atomic::Ordering::Acquire);
if let Err(e) = nodes[2].splice_channel(
Expand Down
10 changes: 4 additions & 6 deletions lightning-tests/src/upgrade_downgrade_tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -441,12 +441,10 @@ fn do_test_0_1_htlc_forward_after_splice(fail_htlc: bool) {
reconnect_b_c_args.send_announcement_sigs = (true, true);
reconnect_nodes(reconnect_b_c_args);

let contribution = SpliceContribution::SpliceOut {
outputs: vec![TxOut {
value: Amount::from_sat(1_000),
script_pubkey: nodes[0].wallet_source.get_change_script().unwrap(),
}],
};
let contribution = SpliceContribution::splice_out(vec![TxOut {
value: Amount::from_sat(1_000),
script_pubkey: nodes[0].wallet_source.get_change_script().unwrap(),
}]);
let splice_tx = splice_channel(&nodes[0], &nodes[1], ChannelId(chan_id_bytes_a), contribution);
for node in nodes.iter() {
mine_transaction(node, &splice_tx);
Expand Down
28 changes: 28 additions & 0 deletions lightning/src/events/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ use crate::blinded_path::payment::{
use crate::chain::transaction;
use crate::ln::channel::FUNDING_CONF_DEADLINE_BLOCKS;
use crate::ln::channelmanager::{InterceptId, PaymentId, RecipientOnionFields};
use crate::ln::funding::FundingContribution;
use crate::ln::types::ChannelId;
use crate::ln::{msgs, LocalHTLCFailureReason};
use crate::offers::invoice::Bolt12Invoice;
Expand Down Expand Up @@ -1816,6 +1817,28 @@ pub enum Event {
/// [`ChannelManager::respond_to_static_invoice_request`]: crate::ln::channelmanager::ChannelManager::respond_to_static_invoice_request
invoice_request: InvoiceRequest,
},
///
FundingNeeded {
/// The `channel_id` of the channel which you'll need to pass back into
/// [`ChannelManager::funding_contributed`].
///
/// [`ChannelManager::funding_contributed`]: crate::ln::channelmanager::ChannelManager::funding_contributed
channel_id: ChannelId,
/// The counterparty's `node_id`, which you'll need to pass back into
/// [`ChannelManager::funding_contributed`].
///
/// [`ChannelManager::funding_contributed`]: crate::ln::channelmanager::ChannelManager::funding_contributed
counterparty_node_id: PublicKey,
/// The `user_channel_id` value passed in for outbound channels, or for inbound channels if
/// [`UserConfig::manually_accept_inbound_channels`] config flag is set to true. Otherwise
/// `user_channel_id` will be randomized for inbound channels.
///
/// [`UserConfig::manually_accept_inbound_channels`]: crate::util::config::UserConfig::manually_accept_inbound_channels
user_channel_id: u128,

///
contribution: FundingContribution,
},
/// Indicates that a channel funding transaction constructed interactively is ready to be
/// signed. This event will only be triggered if at least one input was contributed.
///
Expand Down Expand Up @@ -2347,6 +2370,10 @@ impl Writeable for Event {
(13, *contributed_outputs, optional_vec),
});
},
&Event::FundingNeeded { .. } => {
54u8.write(writer)?;
todo!();
},
// Note that, going forward, all new events must only write data inside of
// `write_tlv_fields`. Versions 0.0.101+ will ignore odd-numbered events that write
// data via `write_tlv_fields`.
Expand Down Expand Up @@ -2978,6 +3005,7 @@ impl MaybeReadable for Event {
};
f()
},
54u8 => todo!(),
// Versions prior to 0.0.100 did not ignore odd types, instead returning InvalidValue.
// Version 0.0.100 failed to properly ignore odd types, possibly resulting in corrupt
// reads.
Expand Down
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