1 | var bufferutils = require('./bufferutils')
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2 | var bcrypto = require('./crypto')
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3 | var bufferReverse = require('buffer-reverse')
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4 | var fastMerkleRoot = require('merkle-lib/fastRoot')
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5 | var typeforce = require('typeforce')
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6 | var types = require('./types')
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7 |
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8 | var Transaction = require('./transaction')
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9 |
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10 | function Block () {
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11 | this.version = 1
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12 | this.prevHash = null
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13 | this.merkleRoot = null
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14 | this.timestamp = 0
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15 | this.bits = 0
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16 | this.nonce = 0
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17 | }
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18 |
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19 | Block.fromBuffer = function (buffer) {
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20 | if (buffer.length < 80) throw new Error('Buffer too small (< 80 bytes)')
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21 |
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22 | var offset = 0
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23 | function readSlice (n) {
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24 | offset += n
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25 | return buffer.slice(offset - n, offset)
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26 | }
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27 |
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28 | function readUInt32 () {
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29 | var i = buffer.readUInt32LE(offset)
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30 | offset += 4
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31 | return i
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32 | }
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33 |
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34 | function readInt32 () {
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35 | var i = buffer.readInt32LE(offset)
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36 | offset += 4
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37 | return i
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38 | }
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39 |
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40 | var block = new Block()
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41 | block.version = readInt32()
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42 | block.prevHash = readSlice(32)
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43 | block.merkleRoot = readSlice(32)
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44 | block.timestamp = readUInt32()
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45 | block.bits = readUInt32()
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46 | block.nonce = readUInt32()
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47 |
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48 | if (buffer.length === 80) return block
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49 |
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50 | function readVarInt () {
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51 | var vi = bufferutils.readVarInt(buffer, offset)
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52 | offset += vi.size
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53 | return vi.number
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54 | }
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55 |
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56 | function readTransaction () {
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57 | var tx = Transaction.fromBuffer(buffer.slice(offset), true)
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58 |
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59 | offset += tx.byteLength()
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60 | return tx
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61 | }
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62 |
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63 | var nTransactions = readVarInt()
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64 | block.transactions = []
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65 |
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66 | for (var i = 0; i < nTransactions; ++i) {
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67 | var tx = readTransaction()
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68 | block.transactions.push(tx)
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69 | }
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70 |
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71 | return block
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72 | }
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73 |
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74 | Block.fromHex = function (hex) {
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75 | return Block.fromBuffer(new Buffer(hex, 'hex'))
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76 | }
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77 |
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78 | Block.prototype.getHash = function () {
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79 | return bcrypto.hash256(this.toBuffer(true))
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80 | }
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81 |
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82 | Block.prototype.getId = function () {
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83 | return bufferReverse(this.getHash()).toString('hex')
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84 | }
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85 |
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86 | Block.prototype.getUTCDate = function () {
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87 | var date = new Date(0)
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88 | date.setUTCSeconds(this.timestamp)
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89 |
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90 | return date
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91 | }
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92 |
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93 | Block.prototype.toBuffer = function (headersOnly) {
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94 | var buffer = new Buffer(80)
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95 |
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96 | var offset = 0
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97 | function writeSlice (slice) {
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98 | slice.copy(buffer, offset)
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99 | offset += slice.length
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100 | }
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101 |
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102 | function writeInt32 (i) {
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103 | buffer.writeInt32LE(i, offset)
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104 | offset += 4
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105 | }
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106 | function writeUInt32 (i) {
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107 | buffer.writeUInt32LE(i, offset)
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108 | offset += 4
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109 | }
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110 |
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111 | writeInt32(this.version)
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112 | writeSlice(this.prevHash)
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113 | writeSlice(this.merkleRoot)
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114 | writeUInt32(this.timestamp)
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115 | writeUInt32(this.bits)
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116 | writeUInt32(this.nonce)
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117 |
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118 | if (headersOnly || !this.transactions) return buffer
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119 |
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120 | var txLenBuffer = bufferutils.varIntBuffer(this.transactions.length)
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121 | var txBuffers = this.transactions.map(function (tx) {
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122 | return tx.toBuffer()
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123 | })
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124 |
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125 | return Buffer.concat([buffer, txLenBuffer].concat(txBuffers))
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126 | }
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127 |
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128 | Block.prototype.toHex = function (headersOnly) {
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129 | return this.toBuffer(headersOnly).toString('hex')
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130 | }
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131 |
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132 | Block.calculateTarget = function (bits) {
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133 | var exponent = ((bits & 0xff000000) >> 24) - 3
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134 | var mantissa = bits & 0x007fffff
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135 | var i = 31 - exponent
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136 |
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137 | var target = new Buffer(32)
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138 | target.fill(0)
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139 |
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140 | target[i] = mantissa & 0xff
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141 | target[i - 1] = mantissa >> 8
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142 | target[i - 2] = mantissa >> 16
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143 | target[i - 3] = mantissa >> 24
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144 |
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145 | return target
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146 | }
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147 |
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148 | Block.calculateMerkleRoot = function (transactions) {
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149 | typeforce([{ getHash: types.Function }], transactions)
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150 | if (transactions.length === 0) throw TypeError('Cannot compute merkle root for zero transactions')
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151 |
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152 | var hashes = transactions.map(function (transaction) {
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153 | return transaction.getHash()
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154 | })
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155 |
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156 | return fastMerkleRoot(hashes, bcrypto.hash256)
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157 | }
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158 |
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159 | Block.prototype.checkMerkleRoot = function () {
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160 | if (!this.transactions) return false
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161 |
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162 | var actualMerkleRoot = Block.calculateMerkleRoot(this.transactions)
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163 | return this.merkleRoot.compare(actualMerkleRoot) === 0
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164 | }
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165 |
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166 | Block.prototype.checkProofOfWork = function () {
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167 | var hash = bufferReverse(this.getHash())
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168 | var target = Block.calculateTarget(this.bits)
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169 |
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170 | return hash.compare(target) <= 0
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171 | }
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172 |
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173 | module.exports = Block
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