refactor: generate sessions manually

Session generation has been moved to `core/SessionBuilder.js`, which retrieves & generates all the required data to create a valid session. This should also decrease initialization time by over 600 milliseconds!

lib/Innertube.js

@@ -7,9 +7,9 @@ const CancelToken = Axios.CancelToken;
 const EventEmitter = require('events');
 
 const OAuth = require('./core/OAuth');
-const Player = require('./core/Player');
 const Actions = require('./core/Actions');
 const Livechat = require('./core/Livechat');
+const SessionBuilder = require('./core/SessionBuilder');
 
 const Utils = require('./utils/Utils');
 const Request = require('./utils/Request');
@@ -44,56 +44,41 @@ class Innertube {
     this.#retry_count = 0;
     return this.#init();
   }
-
+  
   async #init() {
-    const response = await Axios.get(Constants.URLS.YT_BASE, Constants.DEFAULT_HEADERS(this.config)).catch((error) => error);
-    if (response instanceof Error) throw new Utils.InnertubeError('Could not retrieve Innertube session', { message: response.message, status_code: response.status || 0 });
-
-    const data = JSON.parse(`{${Utils.getStringBetweenStrings(response.data, 'ytcfg.set({', '});') || ''}}`);
-    if (data.INNERTUBE_CONTEXT) {
-      this.key = data.INNERTUBE_API_KEY;
-      this.version = data.INNERTUBE_API_VERSION;
-      this.context = data.INNERTUBE_CONTEXT;
-
-      this.player_url = data.PLAYER_JS_URL;
-      this.logged_in = data.LOGGED_IN;
-      this.sts = data.STS;
-
-      this.context.client.hl = 'en';
-      this.context.client.gl = this.config.gl || 'US';
-
-      /**
-       * @event Innertube#auth - fired when signing in to an account.
-       * @event Innertube#update-credentials - fired when the access token is no longer valid.
-       * @type {EventEmitter}
-       */
-      this.ev = new EventEmitter();
-      this.#oauth = new OAuth(this.ev);
-
-      this.#player = new Player(this);
-      await this.#player.init();
-
-      if (this.logged_in && this.config.cookie) {
-        this.auth_apisid = Utils.getStringBetweenStrings(this.config.cookie, 'PAPISID=', ';');
-        this.auth_apisid = Utils.generateSidAuth(this.auth_apisid);
-      }
-
-      this.request = new Request(this);
-      this.actions = new Actions(this);
-
-      this.#initMethods();
-    } else {
-      this.#retry_count += 1;
-      if (this.#retry_count >= 10)
-        throw new Utils.ParsingError('No InnerTubeContext shell provided in ytconfig.', {
-          data_snippet: response.data.slice(0, 300),
-          status_code: response.status || 0
-        });
-      return this.#init();
+    const session = await new SessionBuilder(this.config).build();
+  
+    this.key = session.key;
+    this.version = session.api_version;
+    this.context = session.context;
+    
+    this.logged_in = false;
+    this.player_url = session.player.url;
+    this.sts = session.player.sts;
+    
+    this.#player = session.player;
+    
+    /**
+     * @fires Innertube#auth - fired when signing in to an account.
+     * @fires Innertube#update-credentials - fired when the access token is no longer valid.
+     * @type {EventEmitter}
+     */
+    this.ev = new EventEmitter();
+    this.#oauth = new OAuth(this.ev);
+    
+    if (this.config.cookie) {
+      this.auth_apisid = Utils.getStringBetweenStrings(this.config.cookie, 'PAPISID=', ';');
+      this.auth_apisid = Utils.generateSidAuth(this.auth_apisid);
     }
+    
+    this.request = new Request(this);
+    this.actions = new Actions(this);
+    
+    this.#initMethods();
+    
     return this;
   }
-
+  
   #initMethods() {
     this.account = {
       info: () => this.getAccountInfo(),
@@ -705,7 +690,7 @@ class Innertube {
       format.url = format.url || format.signatureCipher || format.cipher;
 
       if (format.signatureCipher || format.cipher) {
-        format.url = new Signature(format.url, this.#player).decipher();
+        format.url = new Signature(format.url, this.#player.signature_decipher).decipher();
       }
 
       const url_components = new URL(format.url);
@@ -713,7 +698,7 @@ class Innertube {
       url_components.searchParams.set('ratebypass', 'yes');
 
       if (url_components.searchParams.get('n')) {
-        url_components.searchParams.set('n', new NToken(this.#player.ntoken_sc, url_components.searchParams.get('n')).transform());
+        url_components.searchParams.set('n', new NToken(this.#player.ntoken_decipher, url_components.searchParams.get('n')).transform());
       }
 
       format.url = url_components.toString();
@@ -796,7 +781,7 @@ class Innertube {
     let cancel;
     let cancelled = false;
     
-    const cpn = Utils.generateContentPlaybackNonce();
+    const cpn = Utils.generateRandomString(16);
           
     const stream = new Stream.PassThrough();
     this.actions.getVideoInfo(id, cpn).then(async (video_data) => {

lib/core/OAuth.js

@@ -197,7 +197,7 @@ class OAuth {
     const url_body = Constants.OAUTH.REGEX.AUTH_SCRIPT.exec(yttv_response.data)[1];
     const script_url = `${Constants.URLS.YT_BASE}/${url_body}`;
 
-    const response = await Axios.get(script_url, Constants.DEFAULT_HEADERS()).catch((error) => error);
+    const response = await Axios.get(script_url).catch((error) => error);
     if (response instanceof Error) throw new Error(`Could not extract client identity: ${response.message}`);
 
     const client_identity = response.data.replace(/\n/g, '').match(Constants.OAUTH.REGEX.CLIENT_IDENTITY);

lib/core/SessionBuilder.js

@@ -0,0 +1,119 @@
+'use strict';
+
+const Axios = require('axios');
+const Player = require('./Player');
+const Proto = require('../proto');
+const Utils = require('../utils/Utils');
+const Constants = require('../utils/Constants');
+const UserAgent = require('user-agents');
+
+class SessionBuilder {
+  #config;
+  
+  #key;
+  #client_name;
+  #client_version;
+  #api_version;
+  #context;
+  #player;
+  
+  constructor(config) {
+    this.#config = config;
+  }
+  
+  async build() {
+    const data = await Promise.all([
+      this.#getYtConfig(), 
+      this.#getPlayerId() 
+    ]);
+    
+    const ytcfg = data[0];
+    
+    this.#key = ytcfg.INNERTUBE_API_KEY;
+    this.#client_name = ytcfg.INNERTUBE_CLIENT_NAME;
+    this.#client_version = ytcfg.INNERTUBE_CLIENT_VERSION;
+    this.#api_version = ytcfg.INNERTUBE_API_VERSION;
+    this.#player = await new Player(data[1]).init();
+    
+    this.#context = this.#buildContext();
+    
+    return this;
+  }
+  
+  #buildContext() {
+    const user_agent = new UserAgent({ deviceCategory: 'desktop' });
+    
+    const id = Utils.generateRandomString(11);
+    const timestamp = new Date().getTime();
+    
+    const visitor_data = Proto.encodeVisitorData(id, timestamp);
+    
+    const context = {
+      client: {
+        hl: 'en',
+        gl: this.#config.gl || 'US',
+        deviceMake: user_agent.vendor,
+        deviceModel: user_agent.platform,
+        visitorData: visitor_data,
+        userAgent: user_agent.toString(),
+        clientName: this.#client_name,
+        clientVersion: this.#client_version,
+        originalUrl: Constants.URLS.YT_BASE
+      },
+      user: { lockedSafetyMode: false },
+      request: { useSsl: true }
+    }
+    
+    return context;
+  }
+  
+  async #getYtConfig() {
+    const response = await Axios.get(`${Constants.URLS.YT_BASE}/sw.js`).catch((err) => err);
+  
+    if (response instanceof Error) 
+      throw new Utils.InnertubeError('Could not retrieve session data', {
+        status_code: response?.response?.status || 0, 
+        message: response.message 
+      });
+      
+    return JSON.parse(Utils.getStringBetweenStrings(response.data, 'ytcfg.set(', ')'));
+  }
+  
+  async #getPlayerId() {
+    const response = await Axios.get(`${Constants.URLS.YT_BASE}/iframe_api`).catch((err) => err);
+  
+    if (response instanceof Error)
+      throw new Utils.InnertubeError('Could not retrieve js player id', { 
+        status_code: response?.response?.status || 0,
+        message: response.message
+      });
+      
+    return Utils.getStringBetweenStrings(response.data, 'player\\/', '\\/');
+  }
+  
+  get key() {
+    return this.#key;
+  }
+  
+  get context() {
+    return this.#context;
+  }
+  
+  get api_version() {
+    return this.#api_version;
+  }
+  
+  get client_version() {
+    return this.#client_version;
+  }
+  
+  get client_name() {
+    return this.#client_name;
+  }
+  
+  get player() {
+    return this.#player;
+  }
+}
+
+module.exports = SessionBuilder;

lib/utils/Request.js

@@ -77,4 +77,4 @@ class Request {
   }
 }
 
-module.exports = Request;
+module.exports = Request;

lib/utils/Utils.js

@@ -86,11 +86,11 @@ function generateSidAuth(sid) {
   return ['SAPISIDHASH', [timestamp, gen_hash].join('_')].join(' ');
 }
 
-function generateContentPlaybackNonce() {
+function generateRandomString(length) {
   const result = [];
-  const alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+  const alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_';
 
-  for (let i = 0; i < 16; i++) {
+  for (let i = 0; i < length; i++) {
     result.push(alphabet.charAt(Math.floor(Math.random() * alphabet.length)));
   }
   
@@ -139,6 +139,6 @@ function refineNTokenData(data) {
 }
 
 const errors = { UnavailableContentError, ParsingError, DownloadError, InnertubeError, MissingParamError, NoStreamingDataError };
-const functions = { findNode, getRandomUserAgent, generateSidAuth, generateContentPlaybackNonce, getStringBetweenStrings, camelToSnake, timeToSeconds, refineNTokenData };
+const functions = { findNode, getRandomUserAgent, generateSidAuth, generateRandomString, getStringBetweenStrings, camelToSnake, timeToSeconds, refineNTokenData };
 
 module.exports = { ...functions, ...errors };