From 14bda1a028b87b0a68da780b34d6c8fd8b5d5c2f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miroslav=20=C5=A0ediv=C3=BD?= <sedivy.miro@gmail.com>
Date: Sun, 27 Jun 2021 22:07:42 +0200
Subject: [PATCH] add ice restarts to reconnection logic.

---
 src/component/internal/connection.ts |  9 +++++++--
 src/component/internal/messages.ts   | 12 ++++++++++++
 src/component/internal/webrtc.ts     | 20 +++++++++++++++-----
 src/component/types/events.ts        |  1 +
 4 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/src/component/internal/connection.ts b/src/component/internal/connection.ts
index e6cde504..924006f5 100644
--- a/src/component/internal/connection.ts
+++ b/src/component/internal/connection.ts
@@ -86,18 +86,23 @@ export class NekoConnection extends EventEmitter<NekoConnectionEvents> {
 
       // try to downgrade quality if it happend many times
       if (++webrtcCongestion >= WEBRTC_RECONN_FAILED_ATTEMPTS) {
+        webrtcCongestion = 0
+
         const quality = this._webrtcQualityDowngrade(this._state.webrtc.video)
 
         // downgrade if lower video quality exists
         if (quality && this.webrtc.connected) {
           this.setVideo(quality)
-          webrtcCongestion = 0
+        }
+
+        // try to perform ice restart, if available
+        if (this.webrtc.open) {
+          this.websocket.send(EVENT.SIGNAL_RESTART)
           return
         }
 
         // try to reconnect
         this._webrtcReconnect()
-        webrtcCongestion = 0
       }
     })
   }
diff --git a/src/component/internal/messages.ts b/src/component/internal/messages.ts
index 8d52dc1c..3d24fab1 100644
--- a/src/component/internal/messages.ts
+++ b/src/component/internal/messages.ts
@@ -125,6 +125,18 @@ export class NekoMessages extends EventEmitter<NekoEvents> {
     Vue.set(this._state.connection.webrtc, 'video', video)
   }
 
+  protected async [EVENT.SIGNAL_RESTART]({ event, sdp }: message.SignalAnswer) {
+    this._log.debug('EVENT.SIGNAL_RESTART')
+    this.emit('connection.webrtc.sdp', 'remote', sdp)
+
+    const localSdp = await this._connection.webrtc.offer(sdp)
+    this._connection.websocket.send(EVENT.SIGNAL_ANSWER, {
+      sdp: localSdp,
+    })
+
+    this.emit('connection.webrtc.sdp', 'local', localSdp)
+  }
+
   protected [EVENT.SIGNAL_CANDIDATE]({ event, ...candidate }: message.SignalCandidate) {
     this._log.debug('EVENT.SIGNAL_CANDIDATE')
     this._connection.webrtc.setCandidate(candidate)
diff --git a/src/component/internal/webrtc.ts b/src/component/internal/webrtc.ts
index 28d0dd0c..49dd49d9 100644
--- a/src/component/internal/webrtc.ts
+++ b/src/component/internal/webrtc.ts
@@ -54,15 +54,16 @@ export class NekoWebRTC extends EventEmitter<NekoWebRTCEvents> {
     return typeof RTCPeerConnection !== 'undefined' && typeof RTCPeerConnection.prototype.addTransceiver !== 'undefined'
   }
 
-  get connected() {
+  get open() {
     return (
-      typeof this._peer !== 'undefined' &&
-      ['connected', 'checking', 'completed'].includes(this._state) &&
-      typeof this._channel !== 'undefined' &&
-      this._channel.readyState == 'open'
+      typeof this._peer !== 'undefined' && typeof this._channel !== 'undefined' && this._channel.readyState == 'open'
     )
   }
 
+  get connected() {
+    return this.open && ['connected', 'checking', 'completed'].includes(this._state)
+  }
+
   public async setCandidate(candidate: RTCIceCandidateInit) {
     if (!this._peer) {
       this._candidates.push(candidate)
@@ -137,6 +138,15 @@ export class NekoWebRTC extends EventEmitter<NekoWebRTCEvents> {
     this._peer.ondatachannel = this.onDataChannel.bind(this)
     this._peer.addTransceiver('audio', { direction: 'recvonly' })
     this._peer.addTransceiver('video', { direction: 'recvonly' })
+
+    return await this.offer(sdp)
+  }
+
+  public async offer(sdp: string) {
+    if (!this._peer) {
+      throw new Error('attempting to set offer for nonexistent peer')
+    }
+
     this._peer.setRemoteDescription({ type: 'offer', sdp })
 
     if (this._candidates.length > 0) {
diff --git a/src/component/types/events.ts b/src/component/types/events.ts
index 113c0a17..f58cec73 100644
--- a/src/component/types/events.ts
+++ b/src/component/types/events.ts
@@ -3,6 +3,7 @@ export const SYSTEM_ADMIN = 'system/admin'
 export const SYSTEM_DISCONNECT = 'system/disconnect'
 
 export const SIGNAL_REQUEST = 'signal/request'
+export const SIGNAL_RESTART = 'signal/restart'
 export const SIGNAL_ANSWER = 'signal/answer'
 export const SIGNAL_PROVIDE = 'signal/provide'
 export const SIGNAL_CANDIDATE = 'signal/candidate'