Add support for Overwinter transactions.

lib/transaction/transaction.js

@@ -282,7 +282,19 @@ Transaction.prototype.toBuffer = function() {
 };
 
 Transaction.prototype.toBufferWriter = function(writer) {
-  writer.writeUInt32LE(this.version);
+  if (!this.fOverwintered) {
+    writer.writeUInt32LE(this.version);
+  } else {
+    // We don't use bitwise operators which expect 32 bit operands and return a 32 bit signed integer.
+    // For example, var header = 0x80000000 | this.version; returns -7fffffff (-2147483645).
+    var header = 0x80000000 + this.version;
+    writer.writeUInt32LE(header);
+  }
+
+  if (this.fOverwintered) {
+    writer.writeUInt32LE(this.nVersionGroupId);
+  }
+
   writer.writeVarintNum(this.inputs.length);
   _.each(this.inputs, function(input) {
     input.toBufferWriter(writer);
@@ -292,6 +304,11 @@ Transaction.prototype.toBufferWriter = function(writer) {
     output.toBufferWriter(writer);
   });
   writer.writeUInt32LE(this.nLockTime);
+
+  if (this.fOverwintered) {
+    writer.writeUInt32LE(this.nExpiryHeight);
+  }
+
   if (this.version >= 2) {
     writer.writeVarintNum(this.joinSplits.length);
     _.each(this.joinSplits, function(jsdesc) {
@@ -314,15 +331,15 @@ Transaction.prototype.fromBufferReader = function(reader) {
   $.checkArgument(!reader.finished(), 'No transaction data received');
   var i, sizeTxIns, sizeTxOuts, sizeJSDescs;
   var header = reader.readUInt32LE();
-  this.fOverwintered = header & 0x80000000;
 
-  if ( this.fOverwintered == true ) {
+  this.fOverwintered = ((header >>> 31) == 1);
-      this.version = header & 0x7fffffff;
+  if (this.fOverwintered == true) {
+    this.version = header & 0x7fffffff;
   } else {
-      this.version = header;
+    this.version = header;
   }
 
-  if ( this.version >= 3 ){
+  if (this.version >= 3 ){
     this.nVersionGroupId = reader.readUInt32LE();
   }
 
@@ -335,10 +352,13 @@ Transaction.prototype.fromBufferReader = function(reader) {
   for (i = 0; i < sizeTxOuts; i++) {
     this.outputs.push(Output.fromBufferReader(reader));
   }
+
   this.nLockTime = reader.readUInt32LE();
+
   if (this.version >= 3) {
       this.nExpiryHeight = reader.readUInt32LE();
   }
+
   if (this.version >= 2) {
     sizeJSDescs = reader.readVarintNum();
     for (i = 0; i < sizeJSDescs; i++) {
@@ -363,12 +383,19 @@ Transaction.prototype.toObject = Transaction.prototype.toJSON = function toObjec
   });
   var obj = {
     hash: this.hash,
+    fOverwintered: this.fOverwintered,
     version: this.version,
     inputs: inputs,
     outputs: outputs,
     nLockTime: this.nLockTime
   };
-  if (this.version >= 3) {
+
+  if (this.fOverwintered) {
+    obj.nVersionGroupId = this.nVersionGroupId;
+    obj.nExpiryHeight = this.nExpiryHeight;
+  }
+
+  if (this.version >= 2) {
     var joinSplits = [];
     this.joinSplits.forEach(function(joinSplit) {
       joinSplits.push(joinSplit.toObject());
@@ -435,6 +462,17 @@ Transaction.prototype.fromObject = function fromObject(arg) {
   }
   this.nLockTime = transaction.nLockTime;
   this.version = transaction.version;
+
+
+  this.fOverwintered = transaction.fOverwintered;
+  if (this.fOverwintered) {
+    this.nExpiryHeight = transaction.nExpiryHeight;
+    this.nVersionGroupId = transaction.nVersionGroupId;
+  }
+
+
+
+
   if (this.version >= 2) {
     _.each(transaction.joinSplits, function(joinSplit) {
       self.joinSplits.push(new JSDescription(joinSplit));