From e364e2b619a102cddf7e974e2f485fb2cda8a496 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Thu, 30 Jun 2016 08:17:04 -0700
Subject: [PATCH] refactor sighash.

---
 lib/bcoin/coin.js |  4 ++--
 lib/bcoin/tx.js   | 35 +++++++++++++----------------------
 2 files changed, 15 insertions(+), 24 deletions(-)

diff --git a/lib/bcoin/coin.js b/lib/bcoin/coin.js
index 31449ad0..0838447d 100644
--- a/lib/bcoin/coin.js
+++ b/lib/bcoin/coin.js
@@ -61,8 +61,8 @@ Coin.prototype.fromOptions = function fromOptions(options) {
   assert(utils.isNumber(options.height));
   assert(utils.isNumber(options.value));
   assert(typeof options.coinbase === 'boolean');
-  assert(!options.hash || typeof options.hash === 'string');
-  assert(!options.index || utils.isNumber(options.index));
+  assert(options.hash == null || typeof options.hash === 'string');
+  assert(options.index == null || utils.isNumber(options.index));
 
   this.version = options.version;
   this.height = options.height;
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index 6327feb3..606dbd37 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -460,6 +460,15 @@ TX.prototype.hasWitness = function hasWitness() {
  */
 
 TX.prototype.signatureHash = function signatureHash(index, prev, type, version) {
+  if (typeof index !== 'number')
+    index = this.inputs.indexOf(index);
+
+  if (typeof type === 'string')
+    type = constants.hashType[type.toUpperCase()];
+
+  assert(index >= 0 && index < this.inputs.length);
+  assert(prev instanceof Script);
+
   // Traditional sighashing
   if (version === 0)
     return this.signatureHashV0(index, prev, type);
@@ -483,19 +492,7 @@ TX.prototype.signatureHash = function signatureHash(index, prev, type, version)
 TX.prototype.signatureHashV0 = function signatureHashV0(index, prev, type) {
   var i, input, output;
   var p = new BufferWriter();
-  var hashType;
-
-  if (typeof index !== 'number')
-    index = this.inputs.indexOf(index);
-
-  if (typeof type === 'string')
-    type = constants.hashType[type.toUpperCase()];
-
-  assert(index >= 0 && index < this.inputs.length);
-  assert(prev instanceof Script);
-
-  // Get the unmasked hash type.
-  hashType = type & 0x1f;
+  var hashType = type & 0x1f;
 
   if (hashType === constants.hashType.SINGLE) {
     // Bitcoind used to return 1 as an error code:
@@ -610,15 +607,6 @@ TX.prototype.signatureHashV1 = function signatureHashV1(index, prev, type) {
   var p = new BufferWriter();
   var i, hashPrevouts, hashSequence, hashOutputs;
 
-  if (typeof index !== 'number')
-    index = this.inputs.indexOf(index);
-
-  if (typeof type === 'string')
-    type = constants.hashType[type.toUpperCase()];
-
-  assert(index >= 0 && index < this.inputs.length);
-  assert(prev instanceof Script);
-
   if (!(type & constants.hashType.ANYONECANPAY)) {
     if (this._hashPrevouts) {
       hashPrevouts = this._hashPrevouts;
@@ -2206,6 +2194,9 @@ TX.prototype.frameWitness = function frameWitness(writer) {
 
   p.writeU32(this.locktime);
 
+  if (witnessSize === this.inputs.length)
+    throw new Error('Cannot serialize empty-witness tx.');
+
   this._lastWitnessSize = witnessSize + 2;
 
   if (!writer)