node-gamedig/protocols/epic.js

import Core from './core.js'

export default class Epic extends Core {
  constructor () {
    super()

    /**
     * To get information about game servers using Epic's EOS, you need some credentials to authenticate using OAuth2.
     *
     * https://dev.epicgames.com/docs/web-api-ref/authentication
     *
     * These credentials can be provided by the game developers or extracted from the game's files.
     */
    this.clientId = null
    this.clientSecret = null
    this.deploymentId = null
    this.epicApi = 'https://api.epicgames.dev'
    this.authByExternalToken = false // Some games require a client access token to POST to the matchmaking endpoint.

    this.deviceIdAccessToken = null
    this.accessToken = null

    // Don't use the tcp ping probing
    this.usedTcp = true
  }

  async run (state) {
    if (this.authByExternalToken) {
      await this.getExternalAccessToken()
    } else {
      await this.getClientAccessToken()
    }

    await this.queryInfo(state)
    await this.cleanup(state)
  }

  async getClientAccessToken () {
    this.logger.debug('Requesting client access token ...')

    const url = `${this.epicApi}/auth/v1/oauth/token`
    const body = `grant_type=client_credentials&deployment_id=${this.deploymentId}`
    const headers = {
      Authorization: `Basic ${Buffer.from(`${this.clientId}:${this.clientSecret}`).toString('base64')}`,
      'Content-Type': 'application/x-www-form-urlencoded'
    }

    this.logger.debug(`POST: ${url}`)
    const response = await this.request({ url, body, headers, method: 'POST', responseType: 'json' })

    this.accessToken = response.access_token
  }

  async _getDeviceIdToken () {
    this.logger.debug('Requesting deviceId access token ...')

    const url = `${this.epicApi}/auth/v1/accounts/deviceid`
    const body = 'deviceModel=PC'
    const headers = {
      Authorization: `Basic ${Buffer.from(`${this.clientId}:${this.clientSecret}`).toString('base64')}`,
      'Content-Type': 'application/x-www-form-urlencoded'
    }

    this.logger.debug(`POST: ${url}`)
    const response = await this.request({ url, body, headers, method: 'POST', responseType: 'json' })

    return response.access_token
  }

  async getExternalAccessToken () {
    this.logger.debug('Requesting external access token ...')

    const deviceIdToken = await this._getDeviceIdToken()

    const url = `${this.epicApi}/auth/v1/oauth/token`

    const bodyParts = [
      'grant_type=external_auth',
      'external_auth_type=deviceid_access_token',
      `external_auth_token=${deviceIdToken}`,
      'nonce=ABCHFA3qgUCJ1XTPAoGDEF', // This is required but can be set to anything
      `deployment_id=${this.deploymentId}`,
      'display_name=User'
    ]

    const body = bodyParts.join('&')
    const headers = {
      Authorization: `Basic ${Buffer.from(`${this.clientId}:${this.clientSecret}`).toString('base64')}`,
      'Content-Type': 'application/x-www-form-urlencoded'
    }

    this.logger.debug(`POST: ${url}`)
    const response = await this.request({ url, body, headers, method: 'POST', responseType: 'json' })

    this.accessToken = response.access_token
  }

  async queryInfo (state) {
    const url = `${this.epicApi}/matchmaking/v1/${this.deploymentId}/filter`
    const body = {
      criteria: [
        {
          key: 'attributes.ADDRESS_s',
          op: 'EQUAL',
          value: this.options.address
        }
      ]
    }
    const headers = {
      'Content-Type': 'application/json',
      Accept: 'application/json',
      Authorization: `Bearer ${this.accessToken}`
    }

    this.logger.debug(`POST: ${url}`)
    const response = await this.request({ url, json: body, headers, method: 'POST', responseType: 'json' })

    // Epic returns a list of sessions, we need to find the one with the desired port.
    const hasDesiredPort = (session) => session.attributes.ADDRESSBOUND_s === `0.0.0.0:${this.options.port}` ||
      session.attributes.ADDRESSBOUND_s === `${this.options.address}:${this.options.port}` ||
      session.attributes.GAMESERVER_PORT_l === this.options.port

    const desiredServer = response.sessions.find(hasDesiredPort)

    if (!desiredServer) {
      throw new Error('Server not found')
    }

    state.name = desiredServer.attributes.CUSTOMSERVERNAME_s
    state.map = desiredServer.attributes.MAPNAME_s
    state.password = desiredServer.attributes.SERVERPASSWORD_b
    state.numplayers = desiredServer.totalPlayers
    state.maxplayers = desiredServer.settings.maxPublicPlayers

    for (const player of desiredServer.publicPlayers) {
      state.players.push({
        name: player.name,
        raw: player
      })
    }

    state.raw = desiredServer
  }

  async cleanup (state) {
    this.accessToken = null
  }
}