start some stuff on UDP

src/client/voice/VoiceConnectionUDPClient.js

@@ -3,9 +3,132 @@ const dns = require('dns');
 const Constants = require('../../util/Constants');
 const EventEmitter = require('events').EventEmitter;
 
+function parseLocalPacket(message) {
+  try {
+    const packet = new Buffer(message);
+    let address = '';
+    for (let i = 4; i < packet.indexOf(0, i); i++) {
+      address += String.fromCharCode(packet[i]);
+    }
+    const port = parseInt(packet.readUIntLE(packet.length - 2, 2).toString(10), 10);
+    return { address, port };
+  } catch (error) {
+    return { error };
+  }
+}
+
+/**
+ * Represents a UDP Client for a Voice Connection
+ * @extends {EventEmitter}
+ */
 class VoiceConnectionUDPClient extends EventEmitter {
-  constructor(voiceConnection, data) {
+  constructor(voiceConnection) {
     super();
+    /**
+     * The voice connection that this UDP client serves
+     * @type {VoiceConnection}
+     */
+    this.voiceConnection = voiceConnection;
+    /**
+     * The UDP socket
+     * @type {?Socket}
+     */
+    this.socket = null;
+    /**
+     * The address of the discord voice server
+     * @type {?string}
+     */
+    this.discordAddress = null;
+    /**
+     * The local IP address
+     * @type {?string}
+     */
+    this.localAddress = null;
+    /**
+     * The local port
+     * @type {?string}
+     */
+    this.localPort = null;
+  }
+  /**
+   * The port of the discord voice server
+   * @readonly
+   */
+  get discordPort() {
+    return this.voiceConnection.authentication.port;
+  }
+
+  /**
+   * Tries to resolve the voice server endpoint to an address
+   * @returns {Promise<string>}
+   */
+  findEndpointAddress() {
+    return new Promise((resolve, reject) => {
+      dns.lookup(this.voiceConnection.authentication.endpoint, (error, address) => {
+        if (error) {
+          reject(error);
+          return;
+        }
+        resolve(address);
+      });
+    });
+  }
+
+  /**
+   * Send a packet to the UDP client
+   * @param {Object} packet the packet to send
+   * @returns {Promise<Object>}
+   */
+  send(packet) {
+    return new Promise((resolve, reject) => {
+      if (this.socket) {
+        if (!this.address || !this.port) {
+          reject(new Error('malformed UDP address or port'));
+          return;
+        }
+        this.socket.send(packet, 0, packet.length, this.port, this.address, error => {
+          if (error) {
+            reject(error);
+          } else {
+            resolve(packet);
+          }
+        });
+      } else {
+        reject(new Error('tried to send a UDP packet but there is no socket available'));
+      }
+    });
+  }
+
+  createUDPSocket(address) {
+    this.discordAddress = address;
+    const socket = this.socket = udp.createSocket('udp4');
+
+    socket.once('message', message => {
+      const packet = parseLocalPacket(message);
+      if (packet.error) {
+        this.emit('error', packet.error);
+        return;
+      }
+
+      this.localAddress = packet.address;
+      this.localPort = packet.port;
+
+      this.voiceConnection.sockets.ws.sendPacket({
+        op: Constants.VoiceOPCodes.SELECT_PROTOCOL,
+        d: {
+          protocol: 'udp',
+          data: {
+            address: packet.address,
+            port: packet.port,
+            mode: 'xsalsa20_poly1305',
+          },
+        },
+      });
+    });
+
+    const blankMessage = new Buffer(70);
+    blankMessage.writeUIntBE(this.voiceConnection.authentication.ssrc, 0, 4);
+    this.send(blankMessage);
   }
 }