From 540a6643ac44aec956dd2b99493474171acdd579 Mon Sep 17 00:00:00 2001
From: Daniel Cousens <github@dcousens.com>
Date: Thu, 26 Nov 2015 12:40:26 +1100
Subject: [PATCH] txbuilder: clarify SIGHASH invalidation logic in
addInput/addOutput
---
src/transaction_builder.js | 34 +++++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 11 deletions(-)
diff --git a/src/transaction_builder.js b/src/transaction_builder.js
index 5c94ce6..73fd12b 100644
--- a/src/transaction_builder.js
+++ b/src/transaction_builder.js
@@ -208,13 +208,16 @@ TransactionBuilder.prototype.addInput = function (txHash, vout, sequence, prevOu
input.prevOutType = prevOutType
}
- var valid = this.inputs.every(function (input2) {
- if (input2.hashType === undefined) return true
+ // if signatures exist, adding inputs is only acceptable if SIGHASH_ANYONECANPAY is used
+ // throw if any signatures *didn't* use SIGHASH_ANYONECANPAY
+ if (!this.inputs.every(function (otherInput) {
+ // no signature
+ if (otherInput.hashType === undefined) return true
- return input2.hashType & Transaction.SIGHASH_ANYONECANPAY
- })
-
- if (!valid) throw new Error('No, this would invalidate signatures')
+ return otherInput.hashType & Transaction.SIGHASH_ANYONECANPAY
+ })) {
+ throw new Error('No, this would invalidate signatures')
+ }
var prevOut = txHash.toString('hex') + ':' + vout
if (this.prevTxMap[prevOut]) throw new Error('Transaction is already an input')
@@ -228,15 +231,24 @@ TransactionBuilder.prototype.addInput = function (txHash, vout, sequence, prevOu
TransactionBuilder.prototype.addOutput = function (scriptPubKey, value) {
var nOutputs = this.tx.outs.length
- var valid = this.inputs.every(function (input, index) {
+
+ // if signatures exist, adding outputs is only acceptable if SIGHASH_NONE or SIGHASH_SINGLE is used
+ // throws if any signatures didn't use SIGHASH_NONE|SIGHASH_SINGLE
+ if (!this.inputs.every(function (input, index) {
+ // no signature
if (input.hashType === undefined) return true
var hashTypeMod = input.hashType & 0x1f
- return (hashTypeMod === Transaction.SIGHASH_NONE) ||
- (hashTypeMod === Transaction.SIGHASH_SINGLE && index < nOutputs)
- })
+ if (hashTypeMod === Transaction.SIGHASH_NONE) return true
+ if (hashTypeMod === Transaction.SIGHASH_SINGLE) {
+ // account for SIGHASH_SINGLE signing of a non-existing output, aka the "SIGHASH_SINGLE" bug
+ return index < nOutputs
+ }
- if (!valid) throw new Error('No, this would invalidate signatures')
+ return false
+ })) {
+ throw new Error('No, this would invalidate signatures')
+ }
// Attempt to get a script if it's a base58 address string
if (typeof scriptPubKey === 'string') {