96 lines
2.3 KiB
JavaScript
96 lines
2.3 KiB
JavaScript
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'use strict'
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var Buffer = require('safe-buffer').Buffer
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var Transform = require('stream').Transform
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var inherits = require('inherits')
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function throwIfNotStringOrBuffer (val, prefix) {
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if (!Buffer.isBuffer(val) && typeof val !== 'string') {
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throw new TypeError(prefix + ' must be a string or a buffer')
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}
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}
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function HashBase (blockSize) {
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Transform.call(this)
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this._block = Buffer.allocUnsafe(blockSize)
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this._blockSize = blockSize
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this._blockOffset = 0
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this._length = [0, 0, 0, 0]
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this._finalized = false
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}
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inherits(HashBase, Transform)
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HashBase.prototype._transform = function (chunk, encoding, callback) {
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var error = null
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try {
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this.update(chunk, encoding)
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} catch (err) {
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error = err
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}
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callback(error)
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}
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HashBase.prototype._flush = function (callback) {
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var error = null
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try {
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this.push(this.digest())
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} catch (err) {
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error = err
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}
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callback(error)
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}
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HashBase.prototype.update = function (data, encoding) {
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throwIfNotStringOrBuffer(data, 'Data')
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if (this._finalized) throw new Error('Digest already called')
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if (!Buffer.isBuffer(data)) data = Buffer.from(data, encoding)
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// consume data
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var block = this._block
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var offset = 0
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while (this._blockOffset + data.length - offset >= this._blockSize) {
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for (var i = this._blockOffset; i < this._blockSize;) block[i++] = data[offset++]
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this._update()
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this._blockOffset = 0
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}
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while (offset < data.length) block[this._blockOffset++] = data[offset++]
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// update length
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for (var j = 0, carry = data.length * 8; carry > 0; ++j) {
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this._length[j] += carry
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carry = (this._length[j] / 0x0100000000) | 0
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if (carry > 0) this._length[j] -= 0x0100000000 * carry
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}
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return this
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}
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HashBase.prototype._update = function () {
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throw new Error('_update is not implemented')
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}
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HashBase.prototype.digest = function (encoding) {
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if (this._finalized) throw new Error('Digest already called')
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this._finalized = true
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var digest = this._digest()
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if (encoding !== undefined) digest = digest.toString(encoding)
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// reset state
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this._block.fill(0)
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this._blockOffset = 0
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for (var i = 0; i < 4; ++i) this._length[i] = 0
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return digest
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}
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HashBase.prototype._digest = function () {
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throw new Error('_digest is not implemented')
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}
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module.exports = HashBase
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