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peer-connection.js
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peer-connection.js
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const RECONNECT_TIMEOUT = 3000
let iceServers = [{
"url": "stun:stun.l.google.com:19302",
"urls": "stun:stun.l.google.com:19302"
}, {
"url": "stun:global.stun.twilio.com:3478?transport=udp",
"urls": "stun:global.stun.twilio.com:3478?transport=udp"
}]
const PUBLISH_URL_BASE = 'https://pubsub.turbovpb.com/c/'
const SUBSCRIBE_URL_BASE = 'wss://pubsub.turbovpb.com/c/'
const WEBRTC_MODE = 'webrtc'
const WEBSOCKET_MODE = 'websocket'
const ENCRYPTION_KEY_LENGTH = 256
const ENCRYPTION_IV_BYTE_LENGTH = 12
const ENCRYPTION_ALGORITHM = 'AES-GCM'
const BASE64_URL_CHARACTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_'
class PeerConnection {
constructor(encryptionKey) {
this.encryptionKey = encryptionKey
// Create Peer ID
const array = new Uint8Array(16)
crypto.getRandomValues(array)
this.peerId = [...array].map(byte => byte.toString(16).padStart(2, '0')).join('')
// Create Session ID
crypto.getRandomValues(array)
this.sessionId = [...array].map(byte => byte.toString(16).padStart(2, '0')).join('')
this.peer = null
this.connections = []
this.connecting = false
this.onconnect = () => { }
this.ondisconnect = () => { }
this.onerror = () => { }
this.onmessage = () => { }
this.mode = WEBRTC_MODE
this.ws = null
}
static async create() {
const encryptionKey = await generateKey()
return new PeerConnection(encryptionKey)
}
async connect() {
if (this.connecting) {
return
}
this.connecting = true
await this._createPeer()
await this._connectPubSub()
this.connecting = false
}
async reconnect() {
if (!this.peer && !this.ws) {
return this.connect()
}
if (this.peer.disconnected === false) {
console.log('peer already connected')
return
} else if (!this.peer.destroyed) {
// Try reconnecting
const reconnected = await new Promise((resolve) => {
this.peer.once('open', () => resolve(true))
this.peer.once('close', () => resolve(false))
this.peer.once('error', () => resolve(false))
this.peer.once('disconnected', () => resolve(false))
setTimeout(() => resolve(false), RECONNECT_TIMEOUT)
try {
this.peer.reconnect()
} catch (err) {
resolve(false)
}
})
if (reconnected) {
console.log('reconnected existing peer')
return
} else {
console.warn('unable to reconnect peer, destroying and creating a new one')
this.peer.destroy()
}
}
this.peer.connect()
}
async getConnectionSecret() {
const exported = await exportKey(this.encryptionKey)
return `${this.peerId}&${exported}`
}
getSessionId() {
return this.sessionId
}
async destroy() {
console.log('destroying peer connection')
if (this.peer) {
this.peer.onerror = () => { }
this.peer.onclose = () => { }
this.peer.destroy()
}
if (this.ws) {
this.ws.onerror = () => { }
this.ws.onclose = () => { }
this.ws.close()
}
try {
await fetch(`${PUBLISH_URL_BASE}${this.sessionId}`, { method: 'DELETE' })
} catch (err) {
console.error('error deleting channels', err)
}
}
async sendMessage(message) {
if (this.mode === WEBRTC_MODE) {
const connectedPeers = this._getOpenConnections()
console.log(`sending message to ${connectedPeers.length} peer(s)`)
if (connectedPeers.length === 0) {
console.log('not sending message because there is no open connection for peer', this.peerId)
return
}
for (let conn of connectedPeers) {
if (conn.open) {
conn.send(message)
} else {
conn.once('open', () => {
conn.send(message)
})
}
}
} else {
const encrypted = await encrypt(this.encryptionKey, message)
if (this.isConnected()) {
console.log('sending message to pubsub via websocket')
this.ws.send(encrypted)
} else {
console.log('sending message to pubsub via HTTP POST')
try {
await fetch(`${PUBLISH_URL_BASE}${this.sessionId}/extension`, {
method: 'POST',
headers: {
'Content-Type': 'application/octet-stream'
},
body: encrypted
})
} catch (err) {
console.error('error sending message to pubsub', err)
// This will queue the message to be sent when the websocket opens
this.ws.send(encrypted)
}
}
}
}
isConnected() {
if (this.mode === WEBRTC_MODE) {
return this._getOpenConnections().length > 0
} else {
return this.ws && this.ws.readyState === WebSocket.OPEN
}
}
_getOpenConnections() {
return this.connections.filter(conn => {
return conn && conn.peerConnection && conn.peerConnection.iceConnectionState === 'connected'
})
}
async _createPeer() {
try {
// The response will be cached so we'll only request it once every 12 hours
const res = await fetch('https://nts.turbovpb.com/ice')
iceServers = await res.json()
iceServers = iceServers.slice(0, 2)
console.log('using ice servers', iceServers)
} catch (err) {
console.warn('unable to fetch ice servers', err)
}
const peer = new Peer(this.peerId, {
host: 'peerjs.turbovpb.com',
path: '/',
secure: true,
debug: 1,
pingInterval: 1000,
config: {
iceServers
}
})
this.peer = peer
peer.on('open', () => console.log(`peer ${this.peerId} listening for connections`))
peer.on('error', (err) => {
console.error(err)
this.onerror(err)
})
peer.on('close', () => {
console.log(`peer ${this.peerId} closed`)
this.onerror(new Error('Peer closed'))
})
peer.on('connection', async (conn) => {
this.connections.push(conn)
const connIndex = this.connections.length - 1
console.log(`peer ${this.peerId} got connection ${connIndex}`)
conn.on('close', () => {
console.log(`peer ${this.peerId} connection ${connIndex} closed`)
delete this.connections[connIndex]
})
conn.on('iceStateChanged', async (state) => {
console.log(`peer ${this.peerId} connection ${connIndex} state: ${state}`)
// TODO if the state is disconnected, should we let the content script know it's disconnected?
if (this.isConnected()) {
if (this.mode !== WEBRTC_MODE) {
console.log('switching to webrtc mode')
this.mode = WEBRTC_MODE
}
this.onconnect()
} else {
this.ondisconnect()
}
})
conn.on('error', (err) => {
console.log(`peer ${this.peerId} connection ${connIndex} error`, err)
delete this.connections[connIndex]
})
if (conn.serialization === 'json') {
conn.on('data', (message) => {
this.onmessage(message)
})
} else {
console.warn(`Peer connection for peerId ${peerId} serialization should be json but it is: ${conn.serialization}`)
this.onerror(new Error(`Peer using unexpected serialization format: ${conn.serialization}`))
}
})
}
async _connectPubSub() {
if (this.ws) {
if (this.ws.readyState === WebSocket.OPEN) {
console.log('websocket already connected')
return
}
this.ws.onclose = () => { }
this.ws.onerror = () => { }
this.ws.onopen = () => { }
this.ws.onmessage = () => { }
this.ws.close()
}
return new Promise((resolve, reject) => {
const url = `${SUBSCRIBE_URL_BASE}${this.peerId}/extension`
console.log('connecting to:', url)
this.ws = new ReconnectingWebSocket(url, [], {
minReconnectionDelay: 50,
maxReconnectionDelay: 1000,
connectionTimeout: 2000,
debug: true
})
this.ws.binaryType = 'arraybuffer'
let startTime = Date.now()
let openTime
this.ws.onopen = () => {
console.log(`websocket open (took ${Date.now() - startTime}ms)`)
openTime = Date.now()
resolve()
}
this.ws.onclose = () => {
console.log('websocket closed', openTime ? `(after ${Date.now() - openTime}ms)` : '')
startTime = Date.now()
if (this.mode === WEBSOCKET_MODE) {
this.ondisconnect()
}
reject(new Error('Websocket closed before it was opened'))
}
this.ws.onerror = ({ error, message }) => {
if (!error) {
error = new Error(`WebSocket Error: ${message}`)
}
if (this.mode === WEBSOCKET_MODE) {
this.onerror(error)
} else {
console.error('websocket error:', error)
}
reject(error)
}
this.ws.onmessage = async ({ data }) => {
// The mobile site will determine which mode to use
if (this.mode !== WEBSOCKET_MODE) {
console.log('switching to websocket mode')
this.mode = WEBSOCKET_MODE
}
try {
const message = await decrypt(this.encryptionKey, data)
this.onconnect()
this.onmessage(message)
} catch (err) {
console.error('got invalid message from pubsub', err)
}
}
})
}
}
async function generateKey() {
if (!crypto || !crypto.subtle) {
throw new Error(`SubtleCrypto API is required to generate key`)
}
return crypto.subtle.generateKey({
name: ENCRYPTION_ALGORITHM,
length: ENCRYPTION_KEY_LENGTH
}, true, ['encrypt', 'decrypt'])
}
async function exportKey(key) {
const buffer = await crypto.subtle.exportKey('raw', key)
return encodeBase64Url(buffer)
}
async function encrypt(encryptionKey, message) {
if (typeof message === 'object') {
message = JSON.stringify(message)
}
const buffer = (new TextEncoder()).encode(message)
const iv = crypto.getRandomValues(new Uint8Array(ENCRYPTION_IV_BYTE_LENGTH))
const ciphertext = new Uint8Array(await crypto.subtle.encrypt({
name: 'AES-GCM',
iv
}, encryptionKey, buffer))
const payload = new Uint8Array(ciphertext.byteLength + ENCRYPTION_IV_BYTE_LENGTH)
payload.set(ciphertext, 0)
payload.set(iv, ciphertext.byteLength)
return payload
}
async function decrypt(encryptionKey, arrayBuffer) {
const payload = new Uint8Array(arrayBuffer)
const ciphertext = payload.slice(0, 0 - ENCRYPTION_IV_BYTE_LENGTH)
const iv = payload.slice(0 - ENCRYPTION_IV_BYTE_LENGTH)
const plaintext = await crypto.subtle.decrypt({
name: 'AES-GCM',
iv
}, encryptionKey, ciphertext)
const string = (new TextDecoder()).decode(plaintext)
return JSON.parse(string)
}
// Based on https://github.com/herrjemand/Base64URL-ArrayBuffer/blob/master/lib/base64url-arraybuffer.js
function encodeBase64Url(arraybuffer) {
const bytes = new Uint8Array(arraybuffer)
let base64 = ''
for (let i = 0; i < bytes.length; i += 3) {
base64 += BASE64_URL_CHARACTERS[bytes[i] >> 2]
base64 += BASE64_URL_CHARACTERS[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)]
base64 += BASE64_URL_CHARACTERS[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)]
base64 += BASE64_URL_CHARACTERS[bytes[i + 2] & 63]
}
if ((bytes.length % 3) === 2) {
base64 = base64.substring(0, base64.length - 1)
} else if (bytes.length % 3 === 1) {
base64 = base64.substring(0, base64.length - 2)
}
return base64
}