diamond front running resistance: applying the transaction shuffeling for

DMDcoin#89

Author: SurfingNerd

crates/ethcore/src/engines/hbbft/hbbft_engine.rs

@@ -503,7 +503,7 @@ impl HoneyBadgerBFT {
         trace!(target: "consensus", "Batch received for epoch {}, creating new Block.", batch.epoch);
 
         // Decode and de-duplicate transactions
-        let batch_txns: Vec<_> = batch
+        let mut batch_txns: Vec<_> = batch
             .contributions
             .iter()
             .flat_map(|(_, c)| &c.transactions)
@@ -564,6 +564,9 @@ impl HoneyBadgerBFT {
             .write()
             .insert(batch.epoch, random_number);
 
+        // Shuffelin transactions deterministically based on the random number.
+        batch_txns = crate::engines::hbbft::utils::transactions_shuffling::deterministic_transactions_shuffling(batch_txns, random_number);
+
         if let Some(header) = client.create_pending_block_at(batch_txns, timestamp, batch.epoch) {
             let block_num = header.number();
             let hash = header.bare_hash();

crates/ethcore/src/engines/hbbft/utils/mod.rs

@@ -1,2 +1,2 @@
 pub mod bound_contract;
-mod transactions_shuffling;
+pub mod transactions_shuffling;

crates/ethcore/src/engines/hbbft/utils/transactions_shuffling.rs

@@ -25,8 +25,7 @@ fn address_xor_u256(address: &Address, seed: U256) -> Address {
 }
 
 /// The list of transactions is expected to be free of duplicates.
-#[allow(dead_code)]
-fn deterministic_transactions_shuffling(
+pub fn deterministic_transactions_shuffling(
     transactions: Vec<SignedTransaction>,
     seed: U256,
 ) -> Vec<SignedTransaction> {