@yipsec/kdns

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page</span><div id="eed4d2a0bfd64539bb9df78095dec881"></div></div></div><div class="body-wrapper"><div class="main-content"><div class="main-wrapper"><section id="source-page" class="source-page"><header><h1 id="title" class="has-anchor">protocol.js</h1></header><article><pre class="prettyprint source lang-js"><code>/** * Kademlia RPC handlers and protocol logic. * @module kdns/protocol */ 'use strict'; const { Contact } = require('./contact'); const { EventEmitter } = require('node:events'); const { Router } = require('./router'); const { keyStringIsValid, hash160 } = require('./keys'); class Protocol { /** * The final argument passed to any protocol handler is a callback function. * @callback HandlerResponse * @param {Error|null} err - Instance of an error that prevents the handler from completing * @param {Object|Array} results - Output of the RPC operation to respond with */ /** * * * @event module:kdns/protocol~Protocol#storage_get */ /** * * * @event module:kdns/protocol~Protocol#storage_put */ /** * @constructor * @param {module:kdns/router~Router} router - Routing table to use * @param {Object.<string, function>} [extensions] - Additional custom RPC handlers to include */ constructor(router, extensions = {}) { /** * Exposes events arising from handling protocol messages. Some of these * events may require handling if they pass a {@link Protocol~HandlerResponse} * @property {EventEmitter} events */ this.events = new EventEmitter(); /** * @property {module:kdns/router~Router} router */ this.router = router || new Router(); for (let method in extensions) { this[method] = extensions[method].bind(this); } } /** * This RPC involves one node sending a PING message to another, which * presumably replies with a PONG. This has a two-fold effect: the * recipient of the PING must update the bucket corresponding to the * sender; and, if there is a reply, the sender must update the bucket * appropriate to the recipient. * @param {module:kdns/contacts~Contact} contact - The peer who originated this RPC * @param {module:kdns/protocol~HandlerResponse} respond - Callback function for responding to RPC */ PING(contact, respond) { this.router.addContactByNodeId(contact.fingerprint, contact); respond(null, [Date.now()]); } /** * The sender of the STORE RPC provides a key and a block of data and * requires that the recipient store the data and make it available for * later retrieval by that key. * @fires module:kdns/protocol~Protocol#storage_put * @param {string} key - 160 bit ID to address this blob by * @param {module:kdns/node~StoredItem} item - Blob and metadata to store * @param {module:kdns/contacts~Contact} contact - The peer who originated this RPC * @param {module:kdns/protocol~HandlerResponse} respond - Callback function for responding to RPC */ STORE(key, { meta, blob }, contact, respond) { this.router.addContactByNodeId(contact.fingerprint, contact); const kbuf = Buffer.from(key, 'hex'); const hash = hash160(Buffer.from(blob)); const isContentAddressable = Buffer.compare(kbuf, hash) === 0; if (!isContentAddressable) { return respond(new Error('Key does not match value hash')); } this.events.emit('storage_put', key, { meta, blob }, respond); } /** * The FIND_NODE RPC includes a 160-bit key. The recipient of the RPC returns * up to K contacts that it knows to be closest to the key. The recipient * must return K contacts if at all possible. It may only return fewer than K * if it is returning all of the contacts that it has knowledge of. * @param {string} key - 160 bit ID to search for * @param {module:kdns/contacts~Contact} contact - The peer who originated this RPC * @param {module:kdns/protocol~HandlerResponse} respond - Callback function for responding to RPC */ FIND_NODE(key, contact, respond) { this.router.addContactByNodeId(contact.fingerprint, new Contact(contact.address, contact.fingerprint)); if (!keyStringIsValid(key)) { return respond(new Error('Invalid lookup key supplied')); } const result = [ ...this.router.getClosestContactsToKey(key).entries() ].map(([,_contact]) => { return new Contact(_contact.address, _contact.fingerprint); }); respond(null, result); } /** * A FIND_VALUE RPC includes a B=160-bit key. If a corresponding value is * present on the recipient, the associated data is returned. Otherwise the * RPC is equivalent to a FIND_NODE and a set of K contacts is returned. * @fires module:kdns/protocol~Protocol#storage_get * @param {string} key - 160 bit ID to search for * @param {module:kdns/contacts~Contact} contact - The peer who originated this RPC * @param {module:kdns/protocol~HandlerResponse} respond - Callback function for responding to RPC */ FIND_VALUE(key, contact, respond) { this.router.addContactByNodeId(contact.fingerprint, contact); if (!keyStringIsValid(key)) { return respond(new Error('Invalid lookup key supplied')); } this.events.emit('storage_get', key, (err, item) => { if (err) { return this.FIND_NODE(key, contact, respond); } respond(null, item); }); } } module.exports.Protocol = Protocol; </code></pre></article></section></div></div></div><div class="search-container" id="PkfLWpAbet" style="display:none"><div class="wrapper" id="iCxFxjkHbP"><button class="icon-button search-close-button" id="VjLlGakifb" aria-label="close search"><svg><use 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