bitcoinjs-lib/src/transaction.js

// FIXME: To all ye that enter here, be weary of Buffers, Arrays and Hex interchanging between the outpoints

var assert = require('assert')
var Address = require('./address')
var BigInteger = require('./bigi')
var Script = require('./script')
var convert = require('./convert')
var crypto = require('./crypto')
var ECKey = require('./eckey').ECKey
var ecdsa = require('./ecdsa')
var Network = require('./network')

var Transaction = function (doc) {
  if (!(this instanceof Transaction)) { return new Transaction(doc) }
  this.version = 1
  this.locktime = 0
  this.ins = []
  this.outs = []
  this.defaultSequence = [255, 255, 255, 255] // 0xFFFFFFFF

  if (doc) {
    if (typeof doc == "string" || Array.isArray(doc)) {
      doc = Transaction.deserialize(doc)
    }

    if (doc.hash) this.hash = doc.hash;
    if (doc.version) this.version = doc.version;
    if (doc.locktime) this.locktime = doc.locktime;
    if (doc.ins && doc.ins.length) {
      doc.ins.forEach(function(input) {
        this.addInput(new TransactionIn(input))
      }, this)
    }

    if (doc.outs && doc.outs.length) {
      doc.outs.forEach(function(output) {
        this.addOutput(new TransactionOut(output))
      }, this)
    }

    this.hash = this.hash || this.getHash()
  }
}

/**
 * Create a new txin.
 *
 * Can be called with any of:
 *
 * - An existing TransactionIn object
 * - A transaction and an index
 * - A transaction hash and an index
 * - A single string argument of the form txhash:index
 *
 * Note that this method does not sign the created input.
 */
Transaction.prototype.addInput = function (tx, outIndex) {
  if (arguments[0] instanceof TransactionIn) {
    this.ins.push(arguments[0])
  }
  else if (arguments[0].length > 65) {
    var args = arguments[0].split(':')
    return this.addInput(args[0], args[1])
  }
  else {
    var hash = typeof tx === "string" ? tx : tx.hash
    hash = Array.isArray(hash) ? convert.bytesToHex(hash) : hash

    this.ins.push(new TransactionIn({
      outpoint: {
        hash: hash,
        index: outIndex
      },
      script: new Script(),
      sequence: this.defaultSequence
    }))
  }
}

/**
 * Create a new txout.
 *
 * Can be called with:
 *
 * i) An existing TransactionOut object
 * ii) An address object or an address and a value
 * iii) An address:value string
 * iv) Either ii), iii) with an optional network argument
 *
 * FIXME: This is a bit convoluted
 */
Transaction.prototype.addOutput = function (address, value, network) {
  if (arguments[0] instanceof TransactionOut) {
    this.outs.push(arguments[0])
    return
  }

  if (arguments[0].indexOf(':') >= 0) {
    network = value

    var args = arguments[0].split(':')
    address = args[0]
    value = parseInt(args[1])
  }

  network = network || Network.bitcoin

  if (typeof address === 'string') {
    address = Address.fromBase58Check(address)
  }

  this.outs.push(new TransactionOut({
    value: value,
    script: Script.createOutputScript(address, network)
  }))
}

/**
 * Serialize this transaction.
 *
 * Returns the transaction as a byte array in the standard Bitcoin binary
 * format. This method is byte-perfect, i.e. the resulting byte array can
 * be hashed to get the transaction's standard Bitcoin hash.
 */
Transaction.prototype.serialize = function () {
  var buffer = []
  buffer = buffer.concat(convert.numToBytes(parseInt(this.version), 4))
  buffer = buffer.concat(convert.numToVarInt(this.ins.length))

  this.ins.forEach(function(txin) {
    // Why do blockchain.info, blockexplorer.com, sx and just about everybody
    // else use little-endian hashes? No idea...
    buffer = buffer.concat(convert.hexToBytes(txin.outpoint.hash).reverse())

    buffer = buffer.concat(convert.numToBytes(parseInt(txin.outpoint.index), 4))

    var scriptBytes = txin.script.buffer
    buffer = buffer.concat(convert.numToVarInt(scriptBytes.length))
    buffer = buffer.concat(scriptBytes)
    buffer = buffer.concat(txin.sequence)
  })

  buffer = buffer.concat(convert.numToVarInt(this.outs.length))

  this.outs.forEach(function(txout) {
    buffer = buffer.concat(convert.numToBytes(txout.value,8))

    var scriptBytes = txout.script.buffer
    buffer = buffer.concat(convert.numToVarInt(scriptBytes.length))
    buffer = buffer.concat(scriptBytes)
  })

  buffer = buffer.concat(convert.numToBytes(parseInt(this.locktime), 4))

  return buffer
}

Transaction.prototype.serializeHex = function() {
  return convert.bytesToHex(this.serialize())
}

//var OP_CODESEPARATOR = 171

var SIGHASH_ALL = 1
var SIGHASH_NONE = 2
var SIGHASH_SINGLE = 3
var SIGHASH_ANYONECANPAY = 80

/**
 * Hash transaction for signing a specific input.
 *
 * Bitcoin uses a different hash for each signed transaction input. This
 * method copies the transaction, makes the necessary changes based on the
 * hashType, serializes and finally hashes the result. This hash can then be
 * used to sign the transaction input in question.
 */
Transaction.prototype.hashTransactionForSignature =
  function (connectedScript, inIndex, hashType)
{
  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.
  /*scriptCode = scriptCode.filter(function (val) {
    return val !== OP_CODESEPARATOR
    });*/

  // Blank out other inputs' signatures
  txTmp.ins.forEach(function(txin) {
    txin.script = new Script()
  })

  txTmp.ins[inIndex].script = connectedScript

  // Blank out some of the outputs
  if ((hashType & 0x1f) == SIGHASH_NONE) {
    txTmp.outs = []

    // Let the others update at will
    txTmp.ins.forEach(function(txin, i) {
      if (i != inIndex) {
        txTmp.ins[i].sequence = 0
      }
    })

  } else if ((hashType & 0x1f) == SIGHASH_SINGLE) {
    // TODO: Implement
  }

  // Blank out other inputs completely, not recommended for open transactions
  if (hashType & SIGHASH_ANYONECANPAY) {
    txTmp.ins = [txTmp.ins[inIndex]]
  }

  var buffer = txTmp.serialize()
  buffer = buffer.concat(convert.numToBytes(parseInt(hashType), 4))

  return crypto.hash256(buffer)
}

/**
 * Calculate and return the transaction's hash.
 * Reverses hash since blockchain.info, blockexplorer.com and others
 * use little-endian hashes for some stupid reason
 */
Transaction.prototype.getHash = function ()
{
  var buffer = this.serialize()
  var hash = crypto.hash256(buffer)

  return Array.prototype.slice.call(hash).reverse()
}

Transaction.prototype.clone = function ()
{
  var newTx = new Transaction()
  newTx.version = this.version
  newTx.locktime = this.locktime

  this.ins.forEach(function(txin) {
    newTx.addInput(txin.clone())
  })

  this.outs.forEach(function(txout) {
    newTx.addOutput(txout.clone())
  })

  return newTx
}

Transaction.deserialize = function(buffer) {
  if (typeof buffer == "string") {
    buffer = convert.hexToBytes(buffer)
  }
  var pos = 0
  var readAsInt = function(bytes) {
    if (bytes === 0) return 0;
    pos++;
    return buffer[pos-1] + readAsInt(bytes-1) * 256
  }
  var readVarInt = function() {
    var bytes = buffer.slice(pos, pos + 9) // maximum possible number of bytes to read
    var result = convert.varIntToNum(bytes)

    pos += result.bytes.length
    return result.number
  }
  var readBytes = function(bytes) {
    pos += bytes
    return buffer.slice(pos - bytes, pos)
  }
  var readVarString = function() {
    var size = readVarInt()
    return readBytes(size)
  }
  var obj = {
    ins: [],
    outs: []
  }
  obj.version = readAsInt(4)
  var ins = readVarInt()
  var i

  for (i = 0; i < ins; i++) {
    obj.ins.push({
      outpoint: {
        hash: convert.bytesToHex(readBytes(32).reverse()),
        index: readAsInt(4)
      },
      script: new Script(readVarString()),
      sequence: readBytes(4)
    })
  }
  var outs = readVarInt()

  for (i = 0; i < outs; i++) {
    obj.outs.push({
      value: convert.bytesToNum(readBytes(8)),
      script: new Script(readVarString())
    })
  }

  obj.locktime = readAsInt(4)

  return new Transaction(obj)
}

/**
 * Signs a standard output at some index with the given key
 * FIXME: network support is ugly
 */
Transaction.prototype.sign = function(index, key, type, network) {
  assert(key instanceof ECKey)
  type = type || SIGHASH_ALL
  network = network || Network.bitcoin

  var address = key.pub.getAddress(network.pubKeyHash)
  var script = Script.createOutputScript(address, network)
  var hash = this.hashTransactionForSignature(script, index, type)
  var sig = key.sign(hash).concat([type])
  var scriptSig = Script.createInputScript(sig, key.pub)

  this.setScriptSig(index, scriptSig)
}

// Takes outputs of the form [{ output: 'txhash:index', address: 'address' },...]
Transaction.prototype.signWithKeys = function(keys, outputs, type) {
  type = type || SIGHASH_ALL

  var addrdata = keys.map(function(key) {
    assert(key instanceof ECKey)

    return {
      key: key,
      address: key.getAddress().toString()
    }
  })

  var hmap = {}
  outputs.forEach(function(o) {
    hmap[o.output] = o
  })

  for (var i = 0; i < this.ins.length; i++) {
    var outpoint = this.ins[i].outpoint.hash + ':' + this.ins[i].outpoint.index
    var histItem = hmap[outpoint]

    if (!histItem) continue;

    var thisInputAddrdata = addrdata.filter(function(a) {
      return a.address == histItem.address
    })

    if (thisInputAddrdata.length === 0) continue;

    this.sign(i,thisInputAddrdata[0].key)
  }
}

/**
 * Signs a P2SH output at some index with the given key
 */
Transaction.prototype.p2shsign = function(index, script, key, type) {
  type = type || SIGHASH_ALL
  var hash = this.hashTransactionForSignature(script, index, type)
  return key.sign(hash).concat([type])
}

Transaction.prototype.setScriptSig = function(index, script) {
  this.ins[index].script = script
}

Transaction.prototype.validateSig = function(index, script, pub, sig, type) {
  type = type || SIGHASH_ALL
  var hash = this.hashTransactionForSignature(script, index, type)

  return pub.verify(hash, sig)
}

Transaction.feePerKb = 20000
Transaction.prototype.estimateFee = function(feePerKb){
  var uncompressedInSize = 180
  var outSize = 34
  var fixedPadding = 34

  if(feePerKb == undefined) feePerKb = Transaction.feePerKb;
  var size = this.ins.length * uncompressedInSize + this.outs.length * outSize + fixedPadding

  return feePerKb * Math.ceil(size / 1000)
}

var TransactionIn = function (data) {
  if (typeof data == "string") {
    this.outpoint = { hash: data.split(':')[0], index: data.split(':')[1] }
  } else if (data.outpoint) {
    this.outpoint = data.outpoint
  } else {
    this.outpoint = { hash: data.hash, index: data.index }
  }

  if (data.scriptSig) {
    this.script = Script.fromScriptSig(data.scriptSig)
  } else if (data.script) {
    this.script = data.script
  } else {
    this.script = new Script(data.script)
  }

  this.sequence = data.sequence || this.defaultSequence
}

TransactionIn.prototype.clone = function () {
  return new TransactionIn({
    outpoint: {
      hash: this.outpoint.hash,
      index: this.outpoint.index
    },
    script: this.script.clone(),
    sequence: this.sequence
  })
}

// FIXME: Support for alternate networks
var TransactionOut = function (data) {
  this.script =
      data.script instanceof Script    ? data.script.clone()
    : Array.isArray(data.script)       ? new Script(data.script)
    : typeof data.script == "string"   ? new Script(convert.hexToBytes(data.script))
    : data.scriptPubKey                ? Script.fromScriptSig(data.scriptPubKey)
    : data.address                     ? Script.createOutputScript(data.address)
    : new Script()

  if (this.script.buffer.length > 0) this.address = this.script.getToAddress();

  this.value =
      Array.isArray(data.value)        ? convert.bytesToNum(data.value)
    : "string" == typeof data.value    ? parseInt(data.value)
    : data.value instanceof BigInteger ? parseInt(data.value.toString())
    : data.value
}

TransactionOut.prototype.clone = function() {
  var newTxout = new TransactionOut({
    script: this.script.clone(),
    value: this.value
  })
  return newTxout
}

TransactionOut.prototype.scriptPubKey = function() {
  return convert.bytesToHex(this.script.buffer)
}

module.exports = {
  Transaction: Transaction,
  TransactionIn: TransactionIn,
  TransactionOut: TransactionOut
}