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fuzz: add chanmon holder signer fuzz ops #4660

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fuzz: add chanmon holder signer fuzz ops #4660

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33 changes: 30 additions & 3 deletions fuzz/src/chanmon_consistency.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -718,13 +718,16 @@ impl SignerProvider for KeyProvider {
}
}

// Since this fuzzer is only concerned with live-channel operations, we don't need to worry about
// any signer operations that come after a force close.
const SUPPORTED_SIGNER_OPS: [SignerOp; 4] = [
// These signer operations can be blocked by fuzz bytes. The first four cover
// live-channel and splice signing, while the holder-side operations cover local
// on-chain claim signing after LDK has moved a channel to chain handling.
const SUPPORTED_SIGNER_OPS: [SignerOp; 6] = [
SignerOp::SignCounterpartyCommitment,
SignerOp::GetPerCommitmentPoint,
SignerOp::ReleaseCommitmentSecret,
SignerOp::SignSpliceSharedInput,
SignerOp::SignHolderCommitment,
SignerOp::SignHolderHtlcTransaction,
];

impl KeyProvider {
Expand Down Expand Up @@ -1024,6 +1027,18 @@ impl<'a> HarnessNode<'a> {
self.node.timer_tick_occurred();
}

// Re-enables holder-side signer operations and asks the chain monitor to
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@valentinewallace valentinewallace Jun 5, 2026

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I think the commit message could be improved. It references a larger refactor, which I'm not sure is helpful as someone without much context, and I don't think it explains the "why" of the diff as it is stand-alone.

// retry pending claim transactions. Holder signing becomes relevant after
// on-chain close handling starts.
fn enable_holder_signer_ops(&self) {
// Holder-side signing is requested when a node needs to build local
// on-chain claim transactions. Keep it separate from live-channel
// signing so fuzz inputs can choose when those requests unblock.
self.keys_manager.enable_op_for_all_signers(SignerOp::SignHolderCommitment);
self.keys_manager.enable_op_for_all_signers(SignerOp::SignHolderHtlcTransaction);
self.monitor.signer_unblocked(None);
}

fn current_feerate_sat_per_kw(&self) -> FeeRate {
self.fee_estimator.feerate_sat_per_kw()
}
Expand Down Expand Up @@ -2959,9 +2974,14 @@ impl<'a, Out: Output + MaybeSend + MaybeSync> Harness<'a, Out> {
self.nodes[1].keys_manager.enable_op_for_all_signers(op);
self.nodes[2].keys_manager.enable_op_for_all_signers(op);
}
// Live-channel signer work retries through the manager, while
// on-chain holder claims retry through the chain monitor.
self.nodes[0].signer_unblocked(None);
self.nodes[1].signer_unblocked(None);
self.nodes[2].signer_unblocked(None);
self.nodes[0].monitor.signer_unblocked(None);
self.nodes[1].monitor.signer_unblocked(None);
self.nodes[2].monitor.signer_unblocked(None);

self.process_all_events();

Expand Down Expand Up @@ -3383,6 +3403,13 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(data: &[u8], out: Out) {
.enable_op_for_all_signers(SignerOp::SignSpliceSharedInput);
harness.nodes[2].signer_unblocked(None);
},
// Keep holder signer unblocks adjacent to the existing signer op
// bytes. The helper re-enables both holder-side operations for
Comment on lines +3406 to +3407
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@valentinewallace valentinewallace Jun 5, 2026

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"Adjacent" makes me think these bytes should be 0xd3..d5, so I find that a bit confusing.

// every signer owned by the selected node, matching the existing
// key-manager-wide blocking model.
0xe4 => harness.nodes[0].enable_holder_signer_ops(),
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@valentinewallace valentinewallace Jun 5, 2026

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Other bytes of this fuzzer seem much more granular and enable/unblock on a per-op and per-channel basis. Maybe we could document why we're taking a more sweeping approach here? Also "the existing key-manager-wide blocking model" -- what does that mean?

0xe5 => harness.nodes[1].enable_holder_signer_ops(),
0xe6 => harness.nodes[2].enable_holder_signer_ops(),

0xf0 => harness.ab_link.complete_monitor_updates_for_node(
0,
Expand Down
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