chore: introduce endianness BytesBitIterator

Signed-off-by: aeryz <[email protected]>

Author: aeryz

Cargo.lock

@@ -20,7 +20,7 @@ use unionlabs::{
         validator_verifier::ValidatorVerifier,
     },
     primitives::{encoding::HexPrefixed, H256, H384, H768},
-    BytesBitIterator,
+    BytesBitIteratorBE,
 };
 
 pub(crate) const MAX_ACCUMULATOR_PROOF_DEPTH: usize = 63;
@@ -41,9 +41,9 @@ pub trait BlsVerify {
 ///
 /// * `current_validator_verifier`: The validator verifier for the current(trusted) epoch.
 /// * `trusted_state`: Currently trusted `LedgerInfo`. Note that if there's any epoch change, it **MUST** start
-/// from the current epoch + 1.
+///    from the current epoch + 1.
 /// * `state_proof`: Proof of state transition. Note that the function expects epoch changes to be in an ascending
-/// order respective to the epoch number.
+///    order respective to the epoch number.
 /// * `bls_verifier`: BLS verifier
 pub fn verify_state_proof<V: BlsVerify>(
     current_validator_verifier: &ValidatorVerifier,
@@ -88,7 +88,7 @@ pub fn verify_ledger_info<V: BlsVerify>(
     bls_verifier: &V,
 ) -> Result<(), Error> {
     // Self::check_num_of_voters(self.len() as u16, multi_signature.get_signers_bitvec())?;
-    let (pub_keys, _) = BytesBitIterator::new(&ledger_info.signatures.validator_bitmask.inner)
+    let (pub_keys, _) = BytesBitIteratorBE::new(&ledger_info.signatures.validator_bitmask.inner)
         .enumerate()
         .filter(|(_, is_true)| *is_true)
         .map(|(i, _)| {
@@ -214,7 +214,7 @@ pub fn verify_existence_proof(
         .iter()
         .rev()
         .zip(
-            BytesBitIterator::new(&element_key)
+            BytesBitIteratorBE::new(&element_key)
                 .rev()
                 .skip(256 - proof.siblings.len()),
         )

lib/aptos-verifier/src/lib.rs

@@ -19,7 +19,7 @@ use typenum::Unsigned;
 use unionlabs::{
     ensure,
     primitives::{H256, H384, H768},
-    BytesBitIterator,
+    BytesBitIteratorLE,
 };
 
 use crate::{
@@ -73,7 +73,7 @@ pub fn validate_light_client_update<C: ChainSpec, V: BlsVerify>(
 ) -> Result<(), Error> {
     // verify that the sync committee has sufficient participants
     let sync_aggregate = &update.sync_aggregate;
-    let set_bits = BytesBitIterator::new(&sync_aggregate.sync_committee_bits)
+    let set_bits = BytesBitIteratorLE::new(&sync_aggregate.sync_committee_bits)
         .filter(|included| *included)
         .count();
     ensure(
@@ -209,7 +209,7 @@ pub fn validate_light_client_update<C: ChainSpec, V: BlsVerify>(
 
     // It's not mandatory for all of the members of the sync committee to participate. So we are extracting the
     // public keys of the ones who participated.
-    let participant_pubkeys = BytesBitIterator::new(&sync_aggregate.sync_committee_bits)
+    let participant_pubkeys = BytesBitIteratorLE::new(&sync_aggregate.sync_committee_bits)
         .zip(sync_committee.pubkeys.iter())
         .filter_map(|(included, pubkey)| if included { Some(pubkey) } else { None })
         .collect::<Vec<_>>();

lib/ethereum-sync-protocol/src/lib.rs

@@ -15,11 +15,13 @@ pub enum LedgerInfoWithSignatures {
 }
 
 impl LedgerInfoWithSignatures {
+    #[must_use]
     pub fn ledger_info(&self) -> &LedgerInfo {
         let Self::V0(ledger_info) = self;
         &ledger_info.ledger_info
     }
 
+    #[must_use]
     pub fn signatures(&self) -> &AggregateSignature {
         let Self::V0(ledger_info) = self;
         &ledger_info.signatures

lib/unionlabs/src/aptos/ledger_info.rs

@@ -17,6 +17,7 @@ extern crate alloc;
 use core::{
     fmt::{self, Debug, Display},
     iter,
+    marker::PhantomData,
     ptr::addr_of,
     str::FromStr,
 };
@@ -260,17 +261,43 @@ impl<T: core::error::Error> Display for ErrorReporter<T> {
     }
 }
 
+pub trait BitIndex {
+    /// Get the 'i'th bit
+    fn index_of(i: usize) -> usize;
+}
+
+pub struct LittleEndianBitIndex;
+
+impl BitIndex for LittleEndianBitIndex {
+    fn index_of(i: usize) -> usize {
+        i % 8
+    }
+}
+
+pub struct BigEndianBitIndex;
+
+impl BitIndex for BigEndianBitIndex {
+    fn index_of(i: usize) -> usize {
+        7 - i % 8
+    }
+}
+
+pub type BytesBitIteratorLE<'a> = BytesBitIterator<'a, LittleEndianBitIndex>;
+pub type BytesBitIteratorBE<'a> = BytesBitIterator<'a, BigEndianBitIndex>;
+
 #[must_use = "constructing an iterator has no effect"]
-pub struct BytesBitIterator<'a> {
+pub struct BytesBitIterator<'a, E: BitIndex> {
     bz: &'a [u8],
     pos: core::ops::Range<usize>,
+    _marker: PhantomData<E>,
 }
 
-impl<'a> BytesBitIterator<'a> {
+impl<'a, E: BitIndex> BytesBitIterator<'a, E> {
     pub fn new(bz: &'a impl AsRef<[u8]>) -> Self {
         BytesBitIterator {
             bz: bz.as_ref(),
             pos: (0..bz.as_ref().len() * 8),
+            _marker: PhantomData,
         }
     }
 
@@ -279,12 +306,12 @@ impl<'a> BytesBitIterator<'a> {
         // debug_assert_eq!(self.hash_bytes.len(), Hash::LENGTH); // invariant
         // debug_assert_lt!(index, Hash::LENGTH_IN_BITS); // assumed precondition
         let pos = index / 8;
-        let bit = index % 8;
+        let bit = E::index_of(index);
         (self.bz[pos] >> bit) & 1 != 0
     }
 }
 
-impl core::iter::Iterator for BytesBitIterator<'_> {
+impl<E: BitIndex> core::iter::Iterator for BytesBitIterator<'_, E> {
     type Item = bool;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -296,7 +323,7 @@ impl core::iter::Iterator for BytesBitIterator<'_> {
     }
 }
 
-impl core::iter::DoubleEndedIterator for BytesBitIterator<'_> {
+impl<E: BitIndex> core::iter::DoubleEndedIterator for BytesBitIterator<'_, E> {
     fn next_back(&mut self) -> Option<Self::Item> {
         self.pos.next_back().map(|x| self.get_bit(x))
     }