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Transaction: re-work hashForSignature for readability

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This commit is contained in:
Daniel Cousens 2016-06-22 13:54:55 +10:00
parent 4898cc7b67
commit 697f2da1bc
1 changed files with 33 additions and 35 deletions
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64
src/transaction.js
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@ -168,6 +168,10 @@ Transaction.prototype.clone = function () {
var ONE = new Buffer('0000000000000000000000000000000000000000000000000000000000000001', 'hex')
var VALUE_UINT64_MAX = new Buffer('ffffffffffffffff', 'hex')
var BLANK_OUTPUT = {
script: EMPTY_SCRIPT,
valueBuffer: VALUE_UINT64_MAX
}
/**
* Hash transaction for signing a specific input.
@ -183,61 +187,55 @@ Transaction.prototype.hashForSignature = function (inIndex, prevOutScript, hashT
// https://github.com/bitcoin/bitcoin/blob/master/src/test/sighash_tests.cpp#L29
if (inIndex >= this.ins.length) return ONE
var txTmp = this.clone()
// in case concatenating two scripts ends up with two codeseparators,
// or an extra one at the end, this prevents all those possible incompatibilities.
var hashScript = bscript.compile(bscript.decompile(prevOutScript).filter(function (x) {
// ignore OP_CODESEPARATOR
var ourScript = bscript.compile(bscript.decompile(prevOutScript).filter(function (x) {
return x !== opcodes.OP_CODESEPARATOR
}))
var i
// blank out other inputs' signatures
txTmp.ins.forEach(function (input) { input.script = EMPTY_SCRIPT })
txTmp.ins[inIndex].script = hashScript
var txTmp = this.clone()
// blank out some of the inputs
// SIGHASH_NONE: ignore all outputs? (wildcard payee)
if ((hashType & 0x1f) === Transaction.SIGHASH_NONE) {
// wildcard payee
txTmp.outs = []
// let the others update at will
// ignore sequence numbers (except at inIndex)
txTmp.ins.forEach(function (input, i) {
if (i !== inIndex) {
if (i === inIndex) return
input.sequence = 0
}
})
// SIGHASH_SINGLE: ignore all outputs, except at the same index?
} else if ((hashType & 0x1f) === Transaction.SIGHASH_SINGLE) {
var nOut = inIndex
// only lock-in the txOut payee at same index as txIn
// https://github.com/bitcoin/bitcoin/blob/master/src/test/sighash_tests.cpp#L60
if (nOut >= this.outs.length) return ONE
if (inIndex >= this.outs.length) return ONE
txTmp.outs = txTmp.outs.slice(0, nOut + 1)
// truncate outputs after
txTmp.outs.length = inIndex + 1
// blank all other outputs (clear scriptPubKey, value === -1)
var stubOut = {
script: EMPTY_SCRIPT,
valueBuffer: VALUE_UINT64_MAX
// "blank" outputs before
for (var i = 0; i < inIndex; i++) {
txTmp.outs[i] = BLANK_OUTPUT
}
for (i = 0; i < nOut; i++) {
txTmp.outs[i] = stubOut
}
// let the others update at will
// ignore sequence numbers (except at inIndex)
txTmp.ins.forEach(function (input, i) {
if (i !== inIndex) {
if (i === inIndex) return
input.sequence = 0
}
})
}
// blank out other inputs completely, not recommended for open transactions
// SIGHASH_ANYONECANPAY: ignore inputs entirely?
if (hashType & Transaction.SIGHASH_ANYONECANPAY) {
txTmp.ins[0] = txTmp.ins[inIndex]
txTmp.ins = txTmp.ins.slice(0, 1)
txTmp.ins = [txTmp.ins[inIndex]]
txTmp.ins[0].script = ourScript
// SIGHASH_ALL: only ignore input scripts
} else {
// "blank" others input scripts
txTmp.ins.forEach(function (input) { input.script = EMPTY_SCRIPT })
txTmp.ins[inIndex].script = ourScript
}
// serialize and hash