feat: Add support for ARK: Survival Ascended using EOS protocol (#402)

* Add epic protocol

* Add support for ARK: Survival Ascended

- Using epic protocol

* Fix online player count

* Final cleanup

protocols/epic.js

@@ -0,0 +1,107 @@
+import Core from './core.js'
+import axios from 'axios'
+
+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.accessToken = null
+  }
+
+  async run (state) {
+    await this.getAccessToken()
+    await this.queryInfo(state)
+    await this.cleanup(state)
+  }
+
+  async getAccessToken () {
+    this.logger.debug('Requesting acess 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: ${url}`)
+    const response = await axios.post(url, body, { headers })
+    if (response.status !== 200) {
+      throw new Error('Failed to get OAuth token')
+    }
+
+    this.accessToken = response.data.access_token
+  }
+
+  async queryInfo (state) {
+    const url = `${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: ${url}`)
+    const response = await axios.post(url, body, { headers })
+    if (response.status !== 200) {
+      throw new Error('Failed to get server info')
+    }
+
+    const reader = response.data
+
+    // Epic returns a list of sessions, we need to find the one with the desired port.
+    const hasDesiredPort = (session) => session.attributes.ADDRESSBOUND_s === `0.0.0.0:${this.options.port}` ||
+      session.attributes.ADDRESSBOUND_s === `${this.options.address}:${this.options.port}`
+
+    const desiredServer = reader.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.maxplayers = desiredServer.settings.maxPublicPlayers
+
+    // If the game returns the player list, we can use it otherwise we use the total players.
+    if (desiredServer.totalPlayers === desiredServer.publicPlayers.length) {
+      for (const player of desiredServer.publicPlayers) {
+        state.players.push({
+          name: player.name,
+          raw: player
+        })
+      }
+    } else {
+      for (let i = 0; i < desiredServer.totalPlayers; i++) {
+        state.players.push('')
+      }
+    }
+
+    state.raw = desiredServer
+  }
+
+  async cleanup (state) {
+    this.accessToken = null
+  }
+}