Moving from BitcoinHash to Wtxid for Transactions

src/blockdata/block.rs

@@ -24,7 +24,7 @@ use util;
 use util::Error::{BlockBadTarget, BlockBadProofOfWork};
 use util::hash::{BitcoinHash, MerkleRooted, bitcoin_merkle_root};
 use hashes::{Hash, sha256d, HashEngine};
-use hash_types::{Txid, BlockHash, TxMerkleRoot, WitnessMerkleRoot, WitnessCommitment};
+use hash_types::{Txid, Wtxid, BlockHash, TxMerkleRoot, WitnessMerkleRoot, WitnessCommitment};
 use util::uint::Uint256;
 use consensus::encode::Encodable;
 use network::constants::Network;
@@ -103,8 +103,8 @@ impl Block {
 
     /// Merkle root of transactions hashed for witness
     pub fn witness_root(&self) -> WitnessMerkleRoot {
-        let mut txhashes = vec!(Txid::default());
-        txhashes.extend(self.txdata.iter().skip(1).map(|t|t.bitcoin_hash()));
+        let mut txhashes = vec!(Wtxid::default());
+        txhashes.extend(self.txdata.iter().skip(1).map(|t|t.wtxid()));
         let hash_value: sha256d::Hash = bitcoin_merkle_root(txhashes).into();
         hash_value.into()
     }
@@ -112,7 +112,7 @@ impl Block {
 
 impl MerkleRooted for Block {
     fn merkle_root(&self) -> TxMerkleRoot {
-        bitcoin_merkle_root(self.txdata.iter().map(|obj| obj.txid().into()).collect())
+        bitcoin_merkle_root::<Txid>(self.txdata.iter().map(|obj| obj.txid().into()).collect())
     }
 }
 

src/blockdata/constants.rs

@@ -171,7 +171,7 @@ mod test {
         assert_eq!(gen.output[0].value, 50 * COIN_VALUE);
         assert_eq!(gen.lock_time, 0);
 
-        assert_eq!(format!("{:x}", gen.bitcoin_hash()),
+        assert_eq!(format!("{:x}", gen.wtxid()),
                    "4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b".to_string());
     }
 

src/blockdata/transaction.rs

@@ -30,7 +30,6 @@ use hashes::{self, Hash, sha256d};
 use hashes::hex::FromHex;
 
 use util::endian;
-use util::hash::BitcoinHash;
 #[cfg(feature="bitcoinconsensus")] use blockdata::script;
 use blockdata::script::Script;
 use consensus::{encode, serialize, Decodable, Encodable};
@@ -287,12 +286,12 @@ impl Transaction {
             input: self.input.iter().map(|txin| TxIn { script_sig: Script::new(), witness: vec![], .. *txin }).collect(),
             output: self.output.clone(),
         };
-        cloned_tx.bitcoin_hash().into()
+        cloned_tx.txid().into()
     }
 
     /// Computes the txid. For non-segwit transactions this will be identical
-    /// to the output of `BitcoinHash::bitcoin_hash()`, but for segwit transactions,
-    /// this will give the correct txid (not including witnesses) while `bitcoin_hash`
+    /// to the output of `wtxid()`, but for segwit transactions,
+    /// this will give the correct txid (not including witnesses) while `wtxid`
     /// will also hash witnesses.
     pub fn txid(&self) -> Txid {
         let mut enc = Txid::engine();
@@ -303,6 +302,15 @@ impl Transaction {
         Txid::from_engine(enc)
     }
 
+    /// Computes SegWit-version of the transaction id (wtxid). For transaction with the witness
+    /// data this hash includes witness, for pre-witness transaction it is equal to the normal
+    /// value returned by txid() function.
+    pub fn wtxid(&self) -> Wtxid {
+        let mut enc = Wtxid::engine();
+        self.consensus_encode(&mut enc).unwrap();
+        Wtxid::from_engine(enc)
+    }
+
     /// Computes a signature hash for a given input index with a given sighash flag.
     /// To actually produce a scriptSig, this hash needs to be run through an
     /// ECDSA signer, the SigHashType appended to the resulting sig, and a
@@ -438,14 +446,6 @@ impl Transaction {
     }
 }
 
-impl BitcoinHash<Txid> for Transaction {
-    fn bitcoin_hash(&self) -> Txid {
-        let mut enc = Txid::engine();
-        self.consensus_encode(&mut enc).unwrap();
-        Txid::from_engine(enc)
-    }
-}
-
 impl_consensus_encoding!(TxOut, value, script_pubkey);
 
 impl Encodable for OutPoint {
@@ -626,7 +626,6 @@ mod tests {
     use blockdata::script::Script;
     use consensus::encode::serialize;
     use consensus::encode::deserialize;
-    use util::hash::BitcoinHash;
 
     use hashes::Hash;
     use hashes::hex::FromHex;
@@ -712,7 +711,9 @@ mod tests {
         assert_eq!(realtx.output.len(), 1);
         assert_eq!(realtx.lock_time, 0);
 
-        assert_eq!(format!("{:x}", realtx.bitcoin_hash()),
+        assert_eq!(format!("{:x}", realtx.txid()),
+                   "a6eab3c14ab5272a58a5ba91505ba1a4b6d7a3a9fcbd187b6cd99a7b6d548cb7".to_string());
+        assert_eq!(format!("{:x}", realtx.wtxid()),
                    "a6eab3c14ab5272a58a5ba91505ba1a4b6d7a3a9fcbd187b6cd99a7b6d548cb7".to_string());
         assert_eq!(realtx.get_weight(), 193*4);
     }
@@ -781,7 +782,7 @@ mod tests {
         ).unwrap();
         let tx: Transaction = deserialize(&hex_tx).unwrap();
 
-        assert_eq!(format!("{:x}", tx.bitcoin_hash()), "d6ac4a5e61657c4c604dcde855a1db74ec6b3e54f32695d72c5e11c7761ea1b4");
+        assert_eq!(format!("{:x}", tx.wtxid()), "d6ac4a5e61657c4c604dcde855a1db74ec6b3e54f32695d72c5e11c7761ea1b4");
         assert_eq!(format!("{:x}", tx.txid()), "9652aa62b0e748caeec40c4cb7bc17c6792435cc3dfe447dd1ca24f912a1c6ec");
         assert_eq!(tx.get_weight(), 2718);
 
@@ -796,7 +797,7 @@ mod tests {
         ).unwrap();
         let tx: Transaction = deserialize(&hex_tx).unwrap();
 
-        assert_eq!(format!("{:x}", tx.bitcoin_hash()), "971ed48a62c143bbd9c87f4bafa2ef213cfa106c6e140f111931d0be307468dd");
+        assert_eq!(format!("{:x}", tx.wtxid()), "971ed48a62c143bbd9c87f4bafa2ef213cfa106c6e140f111931d0be307468dd");
         assert_eq!(format!("{:x}", tx.txid()), "971ed48a62c143bbd9c87f4bafa2ef213cfa106c6e140f111931d0be307468dd");
     }
 

src/hash_types.rs

@@ -66,3 +66,9 @@ impl_hashencode!(TxMerkleRoot);
 impl_hashencode!(TxMerkleBranch);
 impl_hashencode!(WitnessMerkleRoot);
 impl_hashencode!(FilterHash);
+
+/// Generic trait for functions which may either take a Txid type of Wtxid type as an imput.
+/// For instance, used for Merklization procedure
+pub trait TxidType: Hash<Inner = [u8; 32]> + Encodable + Decodable { }
+impl TxidType for Txid { }
+impl TxidType for Wtxid { }

src/util/hash.rs

@@ -19,9 +19,8 @@ use std::cmp::min;
 use std::default::Default;
 
 use hashes::Hash;
-use hash_types::{Txid, TxMerkleRoot};
+use hash_types::{Txid, TxidType, TxMerkleRoot};
 
-use consensus::encode::Encodable;
 
 /// Any collection of objects for which a merkle root makes sense to calculate
 pub trait MerkleRooted {
@@ -31,7 +30,7 @@ pub trait MerkleRooted {
 }
 
 /// Calculates the merkle root of a list of txids hashes directly
-pub fn bitcoin_merkle_root(data: Vec<Txid>) -> TxMerkleRoot {
+pub fn bitcoin_merkle_root<T: TxidType>(data: Vec<T>) -> TxMerkleRoot {
     // Base case
     if data.len() < 1 {
         return Default::default();

src/util/merkleblock.rs

@@ -61,9 +61,9 @@ use std::io;
 use hashes::Hash;
 use hash_types::{Txid, TxMerkleRoot, TxMerkleBranch};
 
+use blockdata::transaction::Transaction;
 use blockdata::constants::{MAX_BLOCK_WEIGHT, MIN_TRANSACTION_WEIGHT};
 use consensus::encode::{self, Decodable, Encodable};
-use util::hash::BitcoinHash;
 use util::merkleblock::MerkleBlockError::*;
 use {Block, BlockHeader};
 
@@ -445,7 +445,7 @@ impl MerkleBlock {
         let mut matches: Vec<bool> = Vec::with_capacity(block.txdata.len());
         let mut hashes: Vec<Txid> = Vec::with_capacity(block.txdata.len());
 
-        for hash in block.txdata.iter().map(BitcoinHash::bitcoin_hash) {
+        for hash in block.txdata.iter().map(Transaction::txid) {
             matches.push(match_txids.contains(&hash));
             hashes.push(hash);
         }