Automatic SDP negotiation (#103)

client/src/neko/base.ts

@@ -2,7 +2,14 @@ import EventEmitter from 'eventemitter3'
 import { OPCODE } from './data'
 import { EVENT, WebSocketEvents } from './events'
 
-import { WebSocketMessages, WebSocketPayloads, SignalProvidePayload, SignalCandidatePayload } from './messages'
+import {
+  WebSocketMessages,
+  WebSocketPayloads,
+  SignalProvidePayload,
+  SignalCandidatePayload,
+  SignalOfferPayload,
+  SignalAnswerMessage,
+} from './messages'
 
 export interface BaseEvents {
   info: (...message: any[]) => void
@@ -180,7 +187,7 @@ export abstract class BaseClient extends EventEmitter<BaseEvents> {
     this._ws!.send(JSON.stringify({ event, ...payload }))
   }
 
-  public async createPeer(sdp: string, lite: boolean, servers: RTCIceServer[]) {
+  public async createPeer(lite: boolean, servers: RTCIceServer[]) {
     this.emit('debug', `creating peer`)
     if (!this.socketOpen) {
       this.emit(
@@ -243,13 +250,32 @@ export abstract class BaseClient extends EventEmitter<BaseEvents> {
     }
 
     this._peer.ontrack = this.onTrack.bind(this)
-    this._peer.addTransceiver('audio', { direction: 'recvonly' })
-    this._peer.addTransceiver('video', { direction: 'recvonly' })
+
+    this._peer.onnegotiationneeded = async () => {
+      this.emit('warn', `negotiation is needed`)
+
+      const d = await this._peer!.createOffer()
+      this._peer!.setLocalDescription(d)
+
+      this._ws!.send(
+        JSON.stringify({
+          event: EVENT.SIGNAL.OFFER,
+          sdp: d.sdp,
+        }),
+      )
+    }
 
     this._channel = this._peer.createDataChannel('data')
     this._channel.onerror = this.onError.bind(this)
     this._channel.onmessage = this.onData.bind(this)
     this._channel.onclose = this.onDisconnected.bind(this, new Error('peer data channel closed'))
+  }
+
+  public async setRemoteOffer(sdp: string) {
+    if (!this._peer) {
+      this.emit('warn', `attempting to set remote offer while disconnected`)
+      return
+    }
 
     this._peer.setRemoteDescription({ type: 'offer', sdp })
 
@@ -274,7 +300,16 @@ export abstract class BaseClient extends EventEmitter<BaseEvents> {
     }
   }
 
-  private onMessage(e: MessageEvent) {
+  public async setRemoteAnswer(sdp: string) {
+    if (!this._peer) {
+      this.emit('warn', `attempting to set remote answer while disconnected`)
+      return
+    }
+
+    this._peer.setRemoteDescription({ type: 'answer', sdp })
+  }
+
+  private async onMessage(e: MessageEvent) {
     const { event, ...payload } = JSON.parse(e.data) as WebSocketMessages
 
     this.emit('debug', `received websocket event ${event} ${payload ? `with payload: ` : ''}`, payload)
@@ -282,7 +317,20 @@ export abstract class BaseClient extends EventEmitter<BaseEvents> {
     if (event === EVENT.SIGNAL.PROVIDE) {
       const { sdp, lite, ice, id } = payload as SignalProvidePayload
       this._id = id
-      this.createPeer(sdp, lite, ice)
+      await this.createPeer(lite, ice)
+      await this.setRemoteOffer(sdp)
+      return
+    }
+
+    if (event === EVENT.SIGNAL.OFFER) {
+      const { sdp } = payload as SignalOfferPayload
+      await this.setRemoteOffer(sdp)
+      return
+    }
+
+    if (event === EVENT.SIGNAL.ANSWER) {
+      const { sdp } = payload as SignalAnswerMessage
+      await this.setRemoteAnswer(sdp)
       return
     }
 

client/src/neko/events.ts

@@ -14,6 +14,7 @@ export const EVENT = {
     ERROR: 'system/error',
   },
   SIGNAL: {
+    OFFER: 'signal/offer',
     ANSWER: 'signal/answer',
     PROVIDE: 'signal/provide',
     CANDIDATE: 'signal/candidate',
@@ -81,7 +82,13 @@ export type ControlEvents =
 
 export type SystemEvents = typeof EVENT.SYSTEM.DISCONNECT
 export type MemberEvents = typeof EVENT.MEMBER.LIST | typeof EVENT.MEMBER.CONNECTED | typeof EVENT.MEMBER.DISCONNECTED
-export type SignalEvents = typeof EVENT.SIGNAL.ANSWER | typeof EVENT.SIGNAL.PROVIDE | typeof EVENT.SIGNAL.CANDIDATE
+
+export type SignalEvents =
+  | typeof EVENT.SIGNAL.OFFER
+  | typeof EVENT.SIGNAL.ANSWER
+  | typeof EVENT.SIGNAL.PROVIDE
+  | typeof EVENT.SIGNAL.CANDIDATE
+
 export type ChatEvents = typeof EVENT.CHAT.MESSAGE | typeof EVENT.CHAT.EMOTE
 export type ScreenEvents = typeof EVENT.SCREEN.CONFIGURATIONS | typeof EVENT.SCREEN.RESOLUTION | typeof EVENT.SCREEN.SET
 

client/src/neko/messages.ts

@@ -14,6 +14,7 @@ import { Member, ScreenConfigurations, ScreenResolution } from './types'
 export type WebSocketMessages =
   | WebSocketMessage
   | SignalProvideMessage
+  | SignalOfferMessage
   | SignalAnswerMessage
   | SignalCandidateMessage
   | MemberListMessage
@@ -26,6 +27,7 @@ export type WebSocketMessages =
 
 export type WebSocketPayloads =
   | SignalProvidePayload
+  | SignalOfferPayload
   | SignalAnswerPayload
   | SignalCandidatePayload
   | MemberListPayload
@@ -74,6 +76,14 @@ export interface SignalProvidePayload {
   sdp: string
 }
 
+// signal/offer
+export interface SignalOfferMessage extends WebSocketMessage, SignalOfferPayload {
+  event: typeof EVENT.SIGNAL.OFFER
+}
+export interface SignalOfferPayload {
+  sdp: string
+}
+
 // signal/answer
 export interface SignalAnswerMessage extends WebSocketMessage, SignalAnswerPayload {
   event: typeof EVENT.SIGNAL.ANSWER