S1

light-client/src/client.rs

@@ -858,6 +858,9 @@ mod test {
         mock_consensus_state.insert(Height::new(0, input.trusted_height), trusted_cs.clone());
 
         // Set fork spec boundary timestamp is all[1]
+        // This indicates that target is the HEADER immediately before the HF occurs.
+        // By setting the height of the HF to ClientState here, the next update_client will be able to validate headers after the HF.
+        // In order to validate the header after HF, it is necessary to set the height at which HF occurs in ClientState in advance.
         let mut boundary_fs = fork_spec_after_lorentz();
         boundary_fs.height_or_timestamp =
             HeightOrTimestamp::Time(header.eth_header().all[1].milli_timestamp());

light-client/src/consensus_state.rs

@@ -18,6 +18,7 @@ pub struct ConsensusState {
     /// the storage root of the IBC contract
     pub state_root: Hash,
     /// timestamp from execution payload
+    /// After Lorentz HF, the unit is millisecond. Before that, it was seconds.
     pub timestamp: Time,
     pub current_validators_hash: Hash,
     pub previous_validators_hash: Hash,

light-client/src/fork_spec.rs

@@ -9,10 +9,18 @@ pub enum HeightOrTimestamp {
     Time(u64),
 }
 
+/// ForkSpec defines different parameters for each HF.
+/// The ForkSpec of the supporting HF must be registered at CreateClient
+/// This is a data structure that does not exist in the BSC node and is designed uniquely for the light client.
 #[derive(Clone, Debug, PartialEq, serde::Serialize, serde::Deserialize)]
 pub struct ForkSpec {
+    /// The timestamp or height at which the HF will occur.
+    /// If you set the timestamp, you need to use the value described in bsc's ChainConfig.
+    /// https://github.com/bnb-chain/bsc/blob/5735d8a56540e8f2fb26d5585de0fa3959bb17b4/params/config.go#L192C3-L192C14
     pub height_or_timestamp: HeightOrTimestamp,
     /// Items count after parent_beacon_root
+    /// The number of headers prior to Pascal HF is set to 0.
+    /// For example, the number of headers after Pascal HF is set to 1 because of the addition of the requestsHash.
     pub additional_header_item_count: u64,
     /// Block count in epoch
     pub epoch_length: u64,
@@ -28,34 +36,35 @@ impl ForkSpec {
     /// with the previous fork specification. It calculates the previous last epoch, the current
     /// first epoch, and any intermediate epochs between them.
     ///
-    /// first = previous last epoch
-    /// last = current first epoch
+    /// previous_last: refers to the previous epoch of the height
+    /// current_first refers to the first epoch of the height divisible by the current fork epoch length.
+    /// intermediates: refers to the epochs between the previous last and current first.
     ///
     /// eg) height = 1501
-    /// first = 1400
-    /// mid = [1600, 1800]
-    /// last = 2000
+    /// previous_last = 1400
+    /// intermediates = [1600, 1800]
+    /// current_first = 2000
     ///
     /// in Lorentz HF
     /// eg) height = 1600
-    /// first = 1600
-    /// mid = [1800]
-    /// last = 2000
+    /// previous_last = 1600
+    /// intermediates = [1800]
+    /// current_first = 2000
     ///
     /// eg) height = 1601
-    /// first = 1600
-    /// mid = [1800]
-    /// last = 2000
+    /// previous_last = 1600
+    /// intermediates = [1800]
+    /// current_first = 2000
     ///
     /// eg) height = 1800
-    /// first = 1800
-    /// mid = []
-    /// last = 2000
+    /// previous_last = 1800
+    /// intermediates = []
+    /// current_first = 2000
     ///
     /// eg) height = 2000
-    /// first = 2000
-    /// mid = []
-    /// last = 2000
+    /// previous_last = 2000
+    /// intermediates = []
+    /// current_first = 2000
     pub fn boundary_epochs(&self, prev_fork_spec: &ForkSpec) -> Result<BoundaryEpochs, Error> {
         if let HeightOrTimestamp::Height(height) = self.height_or_timestamp {
             let prev_last = height - (height % prev_fork_spec.epoch_length);
@@ -137,12 +146,11 @@ impl BoundaryEpochs {
         if current_epoch_block_number == 0 {
             return 0;
         }
-        // first or under
+        // Before HF
         if current_epoch_block_number <= self.prev_last {
             return current_epoch_block_number - self.previous_fork_spec.epoch_length;
         }
 
-        // Hit mids eppchs
         for (i, mid) in self.intermediates.iter().enumerate() {
             if current_epoch_block_number == *mid {
                 if i == 0 {
@@ -153,7 +161,6 @@ impl BoundaryEpochs {
             }
         }
 
-        // is just current HF first
         if current_epoch_block_number == self.current_first {
             if self.intermediates.is_empty() {
                 return self.prev_last;
@@ -227,7 +234,6 @@ pub fn get_boundary_epochs(
     current_spec: &ForkSpec,
     fork_specs: &[ForkSpec],
 ) -> Result<BoundaryEpochs, Error> {
-    // find from last to first
     for (i, spec) in fork_specs.iter().enumerate() {
         if spec == current_spec {
             if i == 0 {

light-client/src/header/eth_header.rs

@@ -402,7 +402,7 @@ impl TryFrom<RawETHHeader> for ETHHeader {
     type Error = Error;
 
     /// This includes part of header verification.
-    /// - verifyHeader: https://github.com/bnb-chain/bsc/blob/b4773e8b5080f37e1c65c083b543f60c895abb70/consensus/parlia/parlia.go#L324
+    /// - verifyHeader: https://github.com/bnb-chain/bsc/blob/5735d8a56540e8f2fb26d5585de0fa3959bb17b4/consensus/parlia/parlia.go#L562
     fn try_from(value: RawETHHeader) -> Result<Self, Self::Error> {
         let mut rlp = RlpIterator::new(Rlp::new(value.header.as_slice()));
         let parent_hash: Vec<u8> = rlp.try_next_as_val()?;

proto/definitions/ibc/lightclients/parlia/v1/parlia.proto

@@ -12,8 +12,6 @@ message ForkSpec {
     uint64 height = 1;
     uint64 timestamp = 2;
   }
-  // The number of headers prior to Pascal HF is set to 0.
-  // For example, the number of headers before Pascal HF is set to 1 because of the addition of the requestsHash.
   uint64 additional_header_item_count = 3;
   uint64 epoch_length = 4;
   uint64 max_turn_length = 5;

proto/src/prost/ibc.lightclients.parlia.v1.rs

@@ -1,8 +1,6 @@
 #[allow(clippy::derive_partial_eq_without_eq)]
 #[derive(Clone, PartialEq, ::prost::Message)]
 pub struct ForkSpec {
-    /// The number of headers prior to Pascal HF is set to 0.
-    /// For example, the number of headers before Pascal HF is set to 1 because of the addition of the requestsHash.
     #[prost(uint64, tag = "3")]
     pub additional_header_item_count: u64,
     #[prost(uint64, tag = "4")]