b229b6b3d5
Moved all public/ to docs/ so that github pages can be hosted on docs/ alone - Moved floGlobals.js, lib.js, floCrypto.js, floBlockchainAPI.js, tokenAPI.js, KBucket.js to docs/scripts/ - Renamed api.js to exchangeAPI.js and moved to docs/scripts/ - Moved index.html to docs/ - Moved css components to docs/css - Updated all imports for the above changes. - User pages (index.html) uses floCrypto.js and floBlockchainAPI.js in docs/script dir instead of fetching from cdn
463 lines
18 KiB
JavaScript
463 lines
18 KiB
JavaScript
'use strict';
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(function(){
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/*Kademlia DHT K-bucket implementation as a binary tree.*/
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/**
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* Implementation of a Kademlia DHT k-bucket used for storing
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* contact (peer node) information.
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*
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* @extends EventEmitter
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*/
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function BuildKBucket(options = {}) {
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/**
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* `options`:
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* `distance`: Function
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* `function (firstId, secondId) { return distance }` An optional
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* `distance` function that gets two `id` Uint8Arrays
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* and return distance (as number) between them.
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* `arbiter`: Function (Default: vectorClock arbiter)
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* `function (incumbent, candidate) { return contact; }` An optional
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* `arbiter` function that givent two `contact` objects with the same `id`
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* returns the desired object to be used for updating the k-bucket. For
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* more details, see [arbiter function](#arbiter-function).
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* `localNodeId`: Uint8Array An optional Uint8Array representing the local node id.
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* If not provided, a local node id will be created via `randomBytes(20)`.
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* `metadata`: Object (Default: {}) Optional satellite data to include
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* with the k-bucket. `metadata` property is guaranteed not be altered by,
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* it is provided as an explicit container for users of k-bucket to store
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* implementation-specific data.
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* `numberOfNodesPerKBucket`: Integer (Default: 20) The number of nodes
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* that a k-bucket can contain before being full or split.
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* `numberOfNodesToPing`: Integer (Default: 3) The number of nodes to
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* ping when a bucket that should not be split becomes full. KBucket will
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* emit a `ping` event that contains `numberOfNodesToPing` nodes that have
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* not been contacted the longest.
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*
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* @param {Object=} options optional
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*/
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this.localNodeId = options.localNodeId || window.crypto.getRandomValues(new Uint8Array(20))
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this.numberOfNodesPerKBucket = options.numberOfNodesPerKBucket || 20
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this.numberOfNodesToPing = options.numberOfNodesToPing || 3
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this.distance = options.distance || this.distance
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// use an arbiter from options or vectorClock arbiter by default
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this.arbiter = options.arbiter || this.arbiter
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this.metadata = Object.assign({}, options.metadata)
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this.createNode = function() {
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return {
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contacts: [],
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dontSplit: false,
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left: null,
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right: null
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}
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}
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this.ensureInt8 = function(name, val) {
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if (!(val instanceof Uint8Array)) {
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throw new TypeError(name + ' is not a Uint8Array')
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}
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}
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/**
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* @param {Uint8Array} array1
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* @param {Uint8Array} array2
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* @return {Boolean}
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*/
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this.arrayEquals = function(array1, array2) {
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if (array1 === array2) {
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return true
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}
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if (array1.length !== array2.length) {
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return false
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}
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for (let i = 0, length = array1.length; i < length; ++i) {
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if (array1[i] !== array2[i]) {
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return false
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}
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}
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return true
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}
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this.ensureInt8('option.localNodeId as parameter 1', this.localNodeId)
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this.root = this.createNode()
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/**
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* Default arbiter function for contacts with the same id. Uses
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* contact.vectorClock to select which contact to update the k-bucket with.
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* Contact with larger vectorClock field will be selected. If vectorClock is
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* the same, candidat will be selected.
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*
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* @param {Object} incumbent Contact currently stored in the k-bucket.
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* @param {Object} candidate Contact being added to the k-bucket.
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* @return {Object} Contact to updated the k-bucket with.
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*/
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this.arbiter = function(incumbent, candidate) {
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return incumbent.vectorClock > candidate.vectorClock ? incumbent : candidate
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}
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/**
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* Default distance function. Finds the XOR
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* distance between firstId and secondId.
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*
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* @param {Uint8Array} firstId Uint8Array containing first id.
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* @param {Uint8Array} secondId Uint8Array containing second id.
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* @return {Number} Integer The XOR distance between firstId
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* and secondId.
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*/
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this.distance = function(firstId, secondId) {
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let distance = 0
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let i = 0
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const min = Math.min(firstId.length, secondId.length)
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const max = Math.max(firstId.length, secondId.length)
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for (; i < min; ++i) {
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distance = distance * 256 + (firstId[i] ^ secondId[i])
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}
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for (; i < max; ++i) distance = distance * 256 + 255
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return distance
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}
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/**
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* Adds a contact to the k-bucket.
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*
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* @param {Object} contact the contact object to add
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*/
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this.add = function(contact) {
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this.ensureInt8('contact.id', (contact || {}).id)
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let bitIndex = 0
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let node = this.root
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while (node.contacts === null) {
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// this is not a leaf node but an inner node with 'low' and 'high'
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// branches; we will check the appropriate bit of the identifier and
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// delegate to the appropriate node for further processing
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node = this._determineNode(node, contact.id, bitIndex++)
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}
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// check if the contact already exists
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const index = this._indexOf(node, contact.id)
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if (index >= 0) {
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this._update(node, index, contact)
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return this
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}
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if (node.contacts.length < this.numberOfNodesPerKBucket) {
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node.contacts.push(contact)
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return this
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}
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// the bucket is full
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if (node.dontSplit) {
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// we are not allowed to split the bucket
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// we need to ping the first this.numberOfNodesToPing
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// in order to determine if they are alive
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// only if one of the pinged nodes does not respond, can the new contact
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// be added (this prevents DoS flodding with new invalid contacts)
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return this
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}
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this._split(node, bitIndex)
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return this.add(contact)
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}
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/**
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* Get the n closest contacts to the provided node id. "Closest" here means:
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* closest according to the XOR metric of the contact node id.
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*
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* @param {Uint8Array} id Contact node id
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* @param {Number=} n Integer (Default: Infinity) The maximum number of
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* closest contacts to return
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* @return {Array} Array Maximum of n closest contacts to the node id
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*/
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this.closest = function(id, n = Infinity) {
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this.ensureInt8('id', id)
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if ((!Number.isInteger(n) && n !== Infinity) || n <= 0) {
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throw new TypeError('n is not positive number')
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}
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let contacts = []
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for (let nodes = [this.root], bitIndex = 0; nodes.length > 0 && contacts.length < n;) {
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const node = nodes.pop()
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if (node.contacts === null) {
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const detNode = this._determineNode(node, id, bitIndex++)
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nodes.push(node.left === detNode ? node.right : node.left)
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nodes.push(detNode)
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} else {
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contacts = contacts.concat(node.contacts)
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}
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}
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return contacts
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.map(a => [this.distance(a.id, id), a])
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.sort((a, b) => a[0] - b[0])
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.slice(0, n)
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.map(a => a[1])
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}
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/**
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* Counts the total number of contacts in the tree.
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*
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* @return {Number} The number of contacts held in the tree
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*/
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this.count = function() {
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// return this.toArray().length
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let count = 0
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for (const nodes = [this.root]; nodes.length > 0;) {
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const node = nodes.pop()
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if (node.contacts === null) nodes.push(node.right, node.left)
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else count += node.contacts.length
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}
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return count
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}
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/**
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* Determines whether the id at the bitIndex is 0 or 1.
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* Return left leaf if `id` at `bitIndex` is 0, right leaf otherwise
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*
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* @param {Object} node internal object that has 2 leafs: left and right
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* @param {Uint8Array} id Id to compare localNodeId with.
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* @param {Number} bitIndex Integer (Default: 0) The bit index to which bit
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* to check in the id Uint8Array.
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* @return {Object} left leaf if id at bitIndex is 0, right leaf otherwise.
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*/
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this._determineNode = function(node, id, bitIndex) {
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// *NOTE* remember that id is a Uint8Array and has granularity of
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// bytes (8 bits), whereas the bitIndex is the bit index (not byte)
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// id's that are too short are put in low bucket (1 byte = 8 bits)
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// (bitIndex >> 3) finds how many bytes the bitIndex describes
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// bitIndex % 8 checks if we have extra bits beyond byte multiples
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// if number of bytes is <= no. of bytes described by bitIndex and there
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// are extra bits to consider, this means id has less bits than what
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// bitIndex describes, id therefore is too short, and will be put in low
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// bucket
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const bytesDescribedByBitIndex = bitIndex >> 3
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const bitIndexWithinByte = bitIndex % 8
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if ((id.length <= bytesDescribedByBitIndex) && (bitIndexWithinByte !== 0)) {
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return node.left
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}
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const byteUnderConsideration = id[bytesDescribedByBitIndex]
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// byteUnderConsideration is an integer from 0 to 255 represented by 8 bits
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// where 255 is 11111111 and 0 is 00000000
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// in order to find out whether the bit at bitIndexWithinByte is set
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// we construct (1 << (7 - bitIndexWithinByte)) which will consist
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// of all bits being 0, with only one bit set to 1
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// for example, if bitIndexWithinByte is 3, we will construct 00010000 by
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// (1 << (7 - 3)) -> (1 << 4) -> 16
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if (byteUnderConsideration & (1 << (7 - bitIndexWithinByte))) {
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return node.right
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}
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return node.left
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}
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/**
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* Get a contact by its exact ID.
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* If this is a leaf, loop through the bucket contents and return the correct
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* contact if we have it or null if not. If this is an inner node, determine
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* which branch of the tree to traverse and repeat.
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*
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* @param {Uint8Array} id The ID of the contact to fetch.
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* @return {Object|Null} The contact if available, otherwise null
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*/
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this.get = function(id) {
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this.ensureInt8('id', id)
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let bitIndex = 0
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let node = this.root
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while (node.contacts === null) {
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node = this._determineNode(node, id, bitIndex++)
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}
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// index of uses contact id for matching
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const index = this._indexOf(node, id)
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return index >= 0 ? node.contacts[index] : null
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}
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/**
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* Returns the index of the contact with provided
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* id if it exists, returns -1 otherwise.
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*
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* @param {Object} node internal object that has 2 leafs: left and right
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* @param {Uint8Array} id Contact node id.
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* @return {Number} Integer Index of contact with provided id if it
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* exists, -1 otherwise.
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*/
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this._indexOf = function(node, id) {
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for (let i = 0; i < node.contacts.length; ++i) {
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if (this.arrayEquals(node.contacts[i].id, id)) return i
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}
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return -1
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}
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/**
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* Removes contact with the provided id.
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*
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* @param {Uint8Array} id The ID of the contact to remove.
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* @return {Object} The k-bucket itself.
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*/
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this.remove = function(id) {
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this.ensureInt8('the id as parameter 1', id)
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let bitIndex = 0
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let node = this.root
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while (node.contacts === null) {
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node = this._determineNode(node, id, bitIndex++)
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}
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const index = this._indexOf(node, id)
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if (index >= 0) {
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const contact = node.contacts.splice(index, 1)[0]
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}
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return this
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}
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/**
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* Splits the node, redistributes contacts to the new nodes, and marks the
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* node that was split as an inner node of the binary tree of nodes by
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* setting this.root.contacts = null
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*
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* @param {Object} node node for splitting
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* @param {Number} bitIndex the bitIndex to which byte to check in the
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* Uint8Array for navigating the binary tree
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*/
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this._split = function(node, bitIndex) {
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node.left = this.createNode()
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node.right = this.createNode()
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// redistribute existing contacts amongst the two newly created nodes
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for (const contact of node.contacts) {
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this._determineNode(node, contact.id, bitIndex).contacts.push(contact)
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}
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node.contacts = null // mark as inner tree node
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// don't split the "far away" node
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// we check where the local node would end up and mark the other one as
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// "dontSplit" (i.e. "far away")
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const detNode = this._determineNode(node, this.localNodeId, bitIndex)
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const otherNode = node.left === detNode ? node.right : node.left
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otherNode.dontSplit = true
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}
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/**
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* Returns all the contacts contained in the tree as an array.
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* If this is a leaf, return a copy of the bucket. `slice` is used so that we
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* don't accidentally leak an internal reference out that might be
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* accidentally misused. If this is not a leaf, return the union of the low
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* and high branches (themselves also as arrays).
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*
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* @return {Array} All of the contacts in the tree, as an array
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*/
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this.toArray = function() {
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let result = []
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for (const nodes = [this.root]; nodes.length > 0;) {
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const node = nodes.pop()
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if (node.contacts === null) nodes.push(node.right, node.left)
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else result = result.concat(node.contacts)
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}
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return result
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}
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/**
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* Updates the contact selected by the arbiter.
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* If the selection is our old contact and the candidate is some new contact
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* then the new contact is abandoned (not added).
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* If the selection is our old contact and the candidate is our old contact
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* then we are refreshing the contact and it is marked as most recently
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* contacted (by being moved to the right/end of the bucket array).
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* If the selection is our new contact, the old contact is removed and the new
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* contact is marked as most recently contacted.
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*
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* @param {Object} node internal object that has 2 leafs: left and right
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* @param {Number} index the index in the bucket where contact exists
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* (index has already been computed in a previous
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* calculation)
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* @param {Object} contact The contact object to update.
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*/
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this._update = function(node, index, contact) {
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// sanity check
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if (!this.arrayEquals(node.contacts[index].id, contact.id)) {
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throw new Error('wrong index for _update')
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}
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const incumbent = node.contacts[index]
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const selection = this.arbiter(incumbent, contact)
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// if the selection is our old contact and the candidate is some new
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// contact, then there is nothing to do
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if (selection === incumbent && incumbent !== contact) return
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node.contacts.splice(index, 1) // remove old contact
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node.contacts.push(selection) // add more recent contact version
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}
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}
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function K_Bucket(masterID, backupList) {
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const decodeID = function(floID) {
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let k = bitjs.Base58.decode(floID);
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k.shift();
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k.splice(-4, 4);
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const decodedId = Crypto.util.bytesToHex(k);
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const nodeIdBigInt = new BigInteger(decodedId, 16);
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const nodeIdBytes = nodeIdBigInt.toByteArrayUnsigned();
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const nodeIdNewInt8Array = new Uint8Array(nodeIdBytes);
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return nodeIdNewInt8Array;
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};
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const _KB = new BuildKBucket({
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localNodeId: decodeID(masterID)
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});
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backupList.forEach(id => _KB.add({
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id: decodeID(id),
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floID: id
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}));
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const orderedList = backupList.map(sn => [_KB.distance(decodeID(masterID), decodeID(sn)), sn])
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.sort((a, b) => a[0] - b[0])
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.map(a => a[1]);
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const self = this;
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Object.defineProperty(self, 'order', {
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get: () => Array.from(orderedList)
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});
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self.closestNode = function(id, N = 1) {
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let decodedId = decodeID(id);
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let n = N || orderedList.length;
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let cNodes = _KB.closest(decodedId, n)
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.map(k => k.floID);
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return (N == 1 ? cNodes[0] : cNodes);
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};
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self.isBefore = (source, target) => orderedList.indexOf(target) < orderedList.indexOf(source);
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self.isAfter = (source, target) => orderedList.indexOf(target) > orderedList.indexOf(source);
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self.isPrev = (source, target) => orderedList.indexOf(target) === orderedList.indexOf(source) - 1;
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self.isNext = (source, target) => orderedList.indexOf(target) === orderedList.indexOf(source) + 1;
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self.prevNode = function(id, N = 1) {
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let n = N || orderedList.length;
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if (!orderedList.includes(id))
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throw Error(`${id} is not in KB list`);
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let pNodes = orderedList.slice(0, orderedList.indexOf(id)).slice(-n);
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return (N == 1 ? pNodes[0] : pNodes);
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};
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self.nextNode = function(id, N = 1) {
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let n = N || orderedList.length;
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if (!orderedList.includes(id))
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throw Error(`${id} is not in KB list`);
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let nNodes = orderedList.slice(orderedList.indexOf(id) + 1).slice(0, n);
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return (N == 1 ? nNodes[0] : nNodes);
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};
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};
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('object' === typeof module) ? module.exports = K_Bucket : window.K_Bucket = K_Bucket;
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})(); |