Check if tx is final

crates/sc-consensus-nakamoto/src/verification.rs

@@ -1,5 +1,6 @@
 mod header_verifier;
 
+use bitcoin::absolute::{LockTime, LOCK_TIME_THRESHOLD};
 use bitcoin::blockdata::constants::MAX_BLOCK_SIGOPS_COST;
 use bitcoin::blockdata::weight::WITNESS_SCALE_FACTOR;
 use bitcoin::consensus::Params;
@@ -58,8 +59,14 @@ pub enum Error {
     FirstTransactionIsNotCoinbase,
     #[error("Block contains multiple coinbase transactions")]
     MultipleCoinbase,
-    #[error("Transaction script contains too many sigops (max: {MAX_BLOCK_SIGOPS_COST})")]
-    TooManySigOps { block_number: u32, tx_index: usize },
+    #[error("Transaction input script contains too many sigops (max: {MAX_BLOCK_SIGOPS_COST})")]
+    TooManySigOps {
+        block_number: u32,
+        txid: Txid,
+        index: usize,
+    },
+    #[error("Transaction is not finalized")]
+    TransactionNotFinal,
     #[error("Block contains duplicate transaction at index {0}")]
     DuplicateTransaction(usize),
     #[error("Transaction contains duplicate inputs at index {0}")]
@@ -140,8 +147,8 @@ where
 
         match self.block_verification {
             BlockVerification::Full => {
-                self.header_verifier.verify_header(&block.header)?;
-                self.verify_transactions(block_number, block, txids)?;
+                let time = self.header_verifier.verify_header(&block.header)?;
+                self.verify_transactions(block_number, block, txids, time)?;
             }
             BlockVerification::HeaderOnly => {
                 self.header_verifier.verify_header(&block.header)?;
@@ -208,7 +215,8 @@ where
             {
                 return Err(Error::TooManySigOps {
                     block_number,
-                    tx_index: index,
+                    txid,
+                    index,
                 });
             }
 
@@ -242,6 +250,7 @@ where
         block_number: u32,
         block: &BitcoinBlock,
         txids: HashMap<usize, Txid>,
+        time: u32,
     ) -> Result<(), Error> {
         let transactions = &block.txdata;
 
@@ -305,6 +314,10 @@ where
                 continue;
             }
 
+            if !is_final(tx, block_number, time) {
+                return Err(Error::TransactionNotFinal);
+            }
+
             let tx_fee = verify_transaction(index, tx)?;
 
             block_fee += tx_fee;
@@ -394,6 +407,24 @@ fn tx_serialize_size_no_witness(tx: &Transaction) -> usize {
         + VarInt(tx.output.len() as u64).size() + output_size // Vec<TxOut>
 }
 
+fn is_final(tx: &Transaction, height: u32, block_time: u32) -> bool {
+    if tx.lock_time == LockTime::ZERO {
+        return true;
+    }
+
+    let lock_time = if tx.lock_time.to_consensus_u32() < LOCK_TIME_THRESHOLD {
+        height
+    } else {
+        block_time
+    };
+
+    if tx.lock_time.to_consensus_u32() < lock_time {
+        return true;
+    }
+
+    tx.input.iter().all(|txin| txin.sequence.is_final())
+}
+
 // Find a UTXO from the previous transactions in current block.
 fn find_utxo_in_current_block(
     block: &BitcoinBlock,

crates/sc-consensus-nakamoto/src/verification/header_verifier.rs

@@ -57,13 +57,14 @@ where
     Block: BlockT,
     Client: HeaderBackend<Block> + AuxStore,
 {
-    /// Verifies the validity of header.
+    /// Verifies the validity of header and returns the block time for verifying the finality of
+    /// transactions.
     ///
     /// - Check proof of work.
     /// - Check the timestamp of the block is in the range:
     ///     - Time is not greater than 2 hours from now.
     ///     - Time is not the median time of last 11 blocks or before.
-    pub fn verify_header(&self, header: &BitcoinHeader) -> Result<(), Error> {
+    pub fn verify_header(&self, header: &BitcoinHeader) -> Result<u32, Error> {
         let last_block_header = self.client.block_header(header.prev_blockhash).ok_or(
             sp_blockchain::Error::MissingHeader(header.prev_blockhash.to_string()),
         )?;
@@ -104,14 +105,17 @@ where
 
         // TODO: check deployment state properly.
         const MAINNET_CSV_HEIGHT: u32 = 419328;
+
         if block_number >= MAINNET_CSV_HEIGHT {
             let median_time = self.calculate_median_time_past(header);
             if header.time <= median_time {
                 return Err(Error::TimeTooOld);
             }
-        }
 
-        Ok(())
+            Ok(median_time)
+        } else {
+            Ok(header.time)
+        }
     }
 
     /// Calculates the median time of the previous few blocks prior to the header (inclusive).