From 2384164ab8b110d9bfac5fddfd53844862c13ca9 Mon Sep 17 00:00:00 2001
From: Braydon Fuller <courier@braydon.com>
Date: Mon, 7 Mar 2016 20:49:55 -0500
Subject: [PATCH] transaction: start to implement segwit serialization

---
 lib/transaction/transaction.js     | 37 +++++++++++++++++++++++++-----
 test/data/bitcoind/tx_invalid.json |  3 ---
 test/transaction/transaction.js    | 17 ++++++++++++++
 3 files changed, 48 insertions(+), 9 deletions(-)

diff --git a/lib/transaction/transaction.js b/lib/transaction/transaction.js
index 276b7fb..3b6eb52 100644
--- a/lib/transaction/transaction.js
+++ b/lib/transaction/transaction.js
@@ -38,6 +38,8 @@ function Transaction(serialized) {
   }
   this.inputs = [];
   this.outputs = [];
+  this.witness = [];
+  this._hasWitness = false;
   this._inputAmount = undefined;
   this._outputAmount = undefined;
 
@@ -57,7 +59,7 @@ function Transaction(serialized) {
     this._newTransaction();
   }
 }
-
+var SERIALIZE_TRANSACTION_WITNESS = 0x40000000;
 var CURRENT_VERSION = 1;
 var DEFAULT_NLOCKTIME = 0;
 var MAX_BLOCK_SIZE = 1000000;
@@ -299,22 +301,45 @@ Transaction.prototype.fromBuffer = function(buffer) {
 
 Transaction.prototype.fromBufferReader = function(reader) {
   $.checkArgument(!reader.finished(), 'No transaction data received');
-  var i, sizeTxIns, sizeTxOuts;
 
   this.version = reader.readInt32LE();
-  sizeTxIns = reader.readVarintNum();
-  for (i = 0; i < sizeTxIns; i++) {
+  var sizeTxIns = reader.readVarintNum();
+
+  // check for segwit
+  this._hasWitness = false;
+  if (sizeTxIns === 0 && reader.buf[reader.pos] !== 0) {
+    reader.pos += 1;
+    this._hasWitness = true;
+    sizeTxIns = reader.readVarintNum();
+  }
+
+  for (var i = 0; i < sizeTxIns; i++) {
     var input = Input.fromBufferReader(reader);
     this.inputs.push(input);
   }
-  sizeTxOuts = reader.readVarintNum();
-  for (i = 0; i < sizeTxOuts; i++) {
+
+  var sizeTxOuts = reader.readVarintNum();
+  for (var j = 0; j < sizeTxOuts; j++) {
     this.outputs.push(Output.fromBufferReader(reader));
   }
+
+  if (this._hasWitness) {
+    this._fromBufferReaderScriptWitnesses(reader);
+  }
+
   this.nLockTime = reader.readUInt32LE();
   return this;
 };
 
+Transaction.prototype._fromBufferReaderScriptWitnesses = function(reader) {
+  var itemCount = reader.readVarintNum();
+  for (var i = 0; i < itemCount; i++) {
+    var size = reader.readVarintNum();
+    var item = reader.read(size);
+    this.witness.push(item);
+  }
+};
+
 Transaction.prototype.toObject = Transaction.prototype.toJSON = function toObject() {
   var inputs = [];
   this.inputs.forEach(function(input) {
diff --git a/test/data/bitcoind/tx_invalid.json b/test/data/bitcoind/tx_invalid.json
index a9f5ff0..e304985 100644
--- a/test/data/bitcoind/tx_invalid.json
+++ b/test/data/bitcoind/tx_invalid.json
@@ -24,9 +24,6 @@
 "010000000100010000000000000000000000000000000000000000000000000000000000000000000009085768617420697320ffffffff010000000000000000015100000000", "P2SH"],
 
 ["Tests for CheckTransaction()"],
-["No inputs"],
-[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "HASH160 0x14 0x7a052c840ba73af26755de42cf01cc9e0a49fef0 EQUAL"]],
-"0100000000010000000000000000015100000000", "P2SH"],
 
 ["No outputs"],
 [[["0000000000000000000000000000000000000000000000000000000000000100", 0, "HASH160 0x14 0x05ab9e14d983742513f0f451e105ffb4198d1dd4 EQUAL"]],
diff --git a/test/transaction/transaction.js b/test/transaction/transaction.js
index 994150d..0504b5c 100644
--- a/test/transaction/transaction.js
+++ b/test/transaction/transaction.js
@@ -1226,6 +1226,23 @@ describe('Transaction', function() {
       });
     });
   });
+
+  describe('Segregated Witness', function() {
+    it('identify as segwit transaction', function() {
+      // https://github.com/bitcoin/bips/blob/master/bip-0144.mediawiki
+      var version = new Buffer('01000000', 'hex');
+      var marker = new Buffer('00', 'hex'); //always zero
+      var flag = new Buffer('01', 'hex'); //non zero
+      var inputCount = new Buffer('00', 'hex');
+      var outputCount = new Buffer('00', 'hex');
+      var witness = new Buffer('00', 'hex');
+      var locktime = new Buffer('00000000', 'hex');
+      var txBuffer = Buffer.concat([version, marker, flag, inputCount, outputCount, witness, locktime]);
+      var tx = bitcore.Transaction().fromBuffer(txBuffer);
+      tx._hasWitness.should.equal(true);
+    });
+  });
+
 });