Merge pull request #9 from datachainlab/fix-lc-context

Fix `LightClientContext` to get a timestamp instead of slot getter

Signed-off-by: Jun Kimura <[email protected]>

crates/consensus/src/compute.rs

@@ -14,14 +14,21 @@ pub fn compute_timestamp_at_slot<C: ChainContext>(ctx: &C, slot: Slot) -> U64 {
     ctx.genesis_time() + slots_since_genesis * ctx.seconds_per_slot()
 }
 
+/// compute_slot_at_timestamp returns the slot number at the given timestamp.
+pub fn compute_slot_at_timestamp<C: ChainContext>(ctx: &C, timestamp: U64) -> Slot {
+    let slots_since_genesis = (timestamp - ctx.genesis_time()) / ctx.seconds_per_slot();
+    ctx.fork_parameters().genesis_slot() + slots_since_genesis
+}
+
+/// compute_sync_committee_period_at_slot returns the sync committee period at slot
 pub fn compute_sync_committee_period_at_slot<C: ChainContext>(
     ctx: &C,
     slot: Slot,
 ) -> SyncCommitteePeriod {
     compute_sync_committee_period(ctx, compute_epoch_at_slot(ctx, slot))
 }
 
-/// Return the epoch number at ``slot``.
+/// Return the epoch number at slot
 /// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/beacon-chain.md#compute_epoch_at_slot
 pub fn compute_epoch_at_slot<C: ChainContext>(ctx: &C, slot: Slot) -> Epoch {
     slot / ctx.slots_per_epoch()
@@ -76,6 +83,33 @@ pub fn compute_signing_root(header: BeaconBlockHeader, domain: Domain) -> Result
     })?)
 }
 
+/// hash_tree_root returns the hash tree root of the object
 pub fn hash_tree_root<T: ssz_rs::SimpleSerialize>(mut object: T) -> Result<Root, Error> {
     Ok(H256::from_slice(object.hash_tree_root()?.as_bytes()))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{config::Config, context::DefaultChainContext, fork::ForkParameters, preset};
+
+    #[test]
+    fn test_compute_timestamp_at_slot() {
+        let ctx = DefaultChainContext::new_with_config(1729846322.into(), get_minimal_config());
+        assert_eq!(compute_timestamp_at_slot(&ctx, 0.into()), 1729846322.into());
+        assert_eq!(compute_timestamp_at_slot(&ctx, 1.into()), 1729846328.into());
+        assert_eq!(compute_timestamp_at_slot(&ctx, 2.into()), 1729846334.into());
+
+        assert_eq!(compute_slot_at_timestamp(&ctx, 1729846322.into()), 0.into());
+        assert_eq!(compute_slot_at_timestamp(&ctx, 1729846328.into()), 1.into());
+        assert_eq!(compute_slot_at_timestamp(&ctx, 1729846334.into()), 2.into());
+    }
+
+    fn get_minimal_config() -> Config {
+        Config {
+            preset: preset::minimal::PRESET,
+            fork_parameters: ForkParameters::new(Version([0, 0, 0, 1]), vec![]),
+            min_genesis_time: U64(1578009600),
+        }
+    }
+}

crates/light-client-cli/src/client.rs

@@ -24,6 +24,7 @@ use ethereum_light_client_verifier::{
     updates::deneb::ConsensusUpdateInfo,
 };
 use log::*;
+use std::time::SystemTime;
 type Result<T> = core::result::Result<T, Error>;
 
 type Updates<
@@ -296,7 +297,11 @@ impl<
             self.genesis_validators_root.clone(),
             self.genesis_time,
             self.trust_level.clone(),
-            || U64(1000000000000),
+            SystemTime::now()
+                .duration_since(SystemTime::UNIX_EPOCH)
+                .unwrap()
+                .as_secs()
+                .into(),
         )
     }
 }

crates/light-client-verifier/src/consensus.rs

@@ -427,7 +427,7 @@ mod tests_bellatrix {
             // NOTE: this is workaround. we must get the correct timestamp from beacon state.
             minimal::get_config().min_genesis_time,
             Fraction::new(2, 3),
-            || U64(100000000000000u64.into()),
+            1729846322.into(),
         );
 
         let updates = [

crates/light-client-verifier/src/context.rs

@@ -1,5 +1,6 @@
 use ethereum_consensus::{
     beacon::{Epoch, Root, Slot},
+    compute::compute_slot_at_timestamp,
     config::Config,
     context::ChainContext,
     fork::ForkParameters,
@@ -21,16 +22,21 @@ impl Fraction {
 }
 
 pub trait ConsensusVerificationContext {
+    /// The root of the genesis validators corresponding to the target chain
+    /// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/beacon-chain.md#beaconstate
     fn genesis_validators_root(&self) -> Root;
 
+    /// A slot based on verifier's local clock
     fn current_slot(&self) -> Slot;
 
+    /// MIN_SYNC_COMMITTEE_PARTICIPANTS from the spec: https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/light-client/sync-protocol.md#misc
     fn min_sync_committee_participants(&self) -> usize;
 
+    /// The threshold of sync committee participation required for valid update
     fn signature_threshold(&self) -> Fraction;
 }
 
-pub struct LightClientContext<F> {
+pub struct LightClientContext {
     fork_parameters: ForkParameters,
     seconds_per_slot: U64,
     slots_per_epoch: Slot,
@@ -40,10 +46,11 @@ pub struct LightClientContext<F> {
     genesis_validators_root: Root,
     min_sync_committee_participants: usize,
     signature_threshold: Fraction,
-    get_current_slot: F,
+
+    current_timestamp: U64,
 }
 
-impl<F> LightClientContext<F> {
+impl LightClientContext {
     pub fn new(
         fork_parameters: ForkParameters,
         seconds_per_slot: U64,
@@ -54,7 +61,7 @@ impl<F> LightClientContext<F> {
         genesis_validators_root: Root,
         min_sync_committee_participants: usize,
         signature_threshold: Fraction,
-        get_current_slot: F,
+        current_timestamp: U64,
     ) -> Self {
         Self {
             fork_parameters,
@@ -66,7 +73,8 @@ impl<F> LightClientContext<F> {
             genesis_validators_root,
             min_sync_committee_participants,
             signature_threshold,
-            get_current_slot,
+
+            current_timestamp,
         }
     }
 
@@ -75,7 +83,7 @@ impl<F> LightClientContext<F> {
         genesis_validators_root: Root,
         genesis_time: U64,
         signature_threshold: Fraction,
-        get_current_slot: F,
+        current_timestamp: U64,
     ) -> Self {
         Self::new(
             config.fork_parameters,
@@ -86,15 +94,12 @@ impl<F> LightClientContext<F> {
             genesis_validators_root,
             config.preset.MIN_SYNC_COMMITTEE_PARTICIPANTS,
             signature_threshold,
-            get_current_slot,
+            current_timestamp,
         )
     }
 }
 
-impl<F> ConsensusVerificationContext for LightClientContext<F>
-where
-    F: Fn() -> Slot,
-{
+impl ConsensusVerificationContext for LightClientContext {
     fn genesis_validators_root(&self) -> Root {
         self.genesis_validators_root.clone()
     }
@@ -108,11 +113,11 @@ where
     }
 
     fn current_slot(&self) -> Slot {
-        (self.get_current_slot)()
+        compute_slot_at_timestamp(self, self.current_timestamp)
     }
 }
 
-impl<F> ChainContext for LightClientContext<F> {
+impl ChainContext for LightClientContext {
     fn genesis_time(&self) -> U64 {
         self.genesis_time
     }