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'use strict';
const EventEmitter = require('events');
const secretbox = require('../util/Secretbox');
// The delay between packets when a user is considered to have stopped speaking
// https://github.com/discordjs/discord.js/issues/3524#issuecomment-540373200
const DISCORD_SPEAKING_DELAY = 250;
class Readable extends require('stream').Readable {
_read() {} // eslint-disable-line no-empty-function
}
class PacketHandler extends EventEmitter {
constructor(receiver) {
super();
this.nonce = Buffer.alloc(24);
this.receiver = receiver;
this.streams = new Map();
this.speakingTimeouts = new Map();
}
get connection() {
return this.receiver.connection;
}
_stoppedSpeaking(userID) {
const streamInfo = this.streams.get(userID);
if (streamInfo && streamInfo.end === 'silence') {
this.streams.delete(userID);
streamInfo.stream.push(null);
}
}
makeStream(user, end) {
if (this.streams.has(user)) return this.streams.get(user).stream;
const stream = new Readable();
stream.on('end', () => this.streams.delete(user));
this.streams.set(user, { stream, end });
return stream;
}
parseBuffer(buffer) {
const { secret_key, mode } = this.receiver.connection.authentication;
// Choose correct nonce depending on encryption
let end;
if (mode === 'xsalsa20_poly1305_lite') {
buffer.copy(this.nonce, 0, buffer.length - 4);
end = buffer.length - 4;
} else if (mode === 'xsalsa20_poly1305_suffix') {
buffer.copy(this.nonce, 0, buffer.length - 24);
end = buffer.length - 24;
} else {
buffer.copy(this.nonce, 0, 0, 12);
}
// Open packet
let packet = secretbox.methods.open(buffer.slice(12, end), this.nonce, secret_key);
if (!packet) return new Error('Failed to decrypt voice packet');
packet = Buffer.from(packet);
// Strip RTP Header Extensions (one-byte only)
if (packet[0] === 0xbe && packet[1] === 0xde && packet.length > 4) {
const headerExtensionLength = packet.readUInt16BE(2);
let offset = 4;
for (let i = 0; i < headerExtensionLength; i++) {
const byte = packet[offset];
offset++;
if (byte === 0) continue;
offset += 1 + (0b1111 & (byte >> 4));
}
// Skip over undocumented Discord byte
offset++;
packet = packet.slice(offset);
}
return packet;
}
push(buffer) {
const ssrc = buffer.readUInt32BE(8);
const userStat = this.connection.ssrcMap.get(ssrc);
if (!userStat) return;
let speakingTimeout = this.speakingTimeouts.get(ssrc);
if (typeof speakingTimeout === 'undefined') {
this.connection.onSpeaking({ user_id: userStat.userID, ssrc: ssrc, speaking: userStat.speaking });
speakingTimeout = this.receiver.connection.client.setTimeout(() => {
try {
this.connection.onSpeaking({ user_id: userStat.userID, ssrc: ssrc, speaking: 0 });
this.receiver.connection.client.clearTimeout(speakingTimeout);
this.speakingTimeouts.delete(ssrc);
} catch {
// Connection already closed, ignore
}
}, DISCORD_SPEAKING_DELAY);
this.speakingTimeouts.set(ssrc, speakingTimeout);
} else {
speakingTimeout.refresh();
}
let stream = this.streams.get(userStat.userID);
if (!stream) return;
stream = stream.stream;
const opusPacket = this.parseBuffer(buffer);
if (opusPacket instanceof Error) {
this.emit('error', opusPacket);
return;
}
stream.push(opusPacket);
}
}
module.exports = PacketHandler;
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