From ee395a5a1947bb33b82ac17f3fa7e3d4d4e5d4b0 Mon Sep 17 00:00:00 2001
From: achingbrain <alex@achingbrain.net>
Date: Mon, 17 Jun 2024 10:38:21 +0100
Subject: [PATCH] fix: create RTCPeerConnection after dialing remote peer

Chrome limits how many RTCPeerConnections a given tab can instantiated
during it's lifetime - https://issues.chromium.org/issues/41378764

To delay hitting this limit, only create the dial-end RTCPeerConnection
once a relayed connection has successfully been opened to the dial
target, this prevents needlessly creating RTCPeerConnections when the
dial fails before they are actually used.

Fixes #2591
---
 .../src/private-to-private/initiate-connection.ts  | 10 ++++++----
 .../src/private-to-private/transport.ts            | 14 ++++++--------
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/packages/transport-webrtc/src/private-to-private/initiate-connection.ts b/packages/transport-webrtc/src/private-to-private/initiate-connection.ts
index 3350f0ac8c..3136558e44 100644
--- a/packages/transport-webrtc/src/private-to-private/initiate-connection.ts
+++ b/packages/transport-webrtc/src/private-to-private/initiate-connection.ts
@@ -1,7 +1,7 @@
 import { CodeError } from '@libp2p/interface'
 import { peerIdFromString } from '@libp2p/peer-id'
 import { pbStream } from 'it-protobuf-stream'
-import { type RTCPeerConnection, RTCSessionDescription } from '../webrtc/index.js'
+import { RTCPeerConnection, RTCSessionDescription } from '../webrtc/index.js'
 import { Message } from './pb/message.js'
 import { SIGNALING_PROTO_ID, splitAddr, type WebRTCTransportMetrics } from './transport.js'
 import { readCandidatesUntilConnected } from './util.js'
@@ -17,7 +17,7 @@ export interface IncomingStreamOpts extends IncomingStreamData {
 }
 
 export interface ConnectOptions extends LoggerOptions {
-  peerConnection: RTCPeerConnection
+  rtcConfiguration?: RTCConfiguration
   multiaddr: Multiaddr
   connectionManager: ConnectionManager
   transportManager: TransportManager
@@ -26,7 +26,7 @@ export interface ConnectOptions extends LoggerOptions {
   metrics?: WebRTCTransportMetrics
 }
 
-export async function initiateConnection ({ peerConnection, signal, metrics, multiaddr: ma, connectionManager, transportManager, log }: ConnectOptions): Promise<{ remoteAddress: Multiaddr }> {
+export async function initiateConnection ({ rtcConfiguration, signal, metrics, multiaddr: ma, connectionManager, transportManager, log }: ConnectOptions): Promise<{ remoteAddress: Multiaddr, peerConnection: RTCPeerConnection }> {
   const { baseAddr } = splitAddr(ma)
 
   metrics?.dialerEvents.increment({ open: true })
@@ -64,6 +64,7 @@ export async function initiateConnection ({ peerConnection, signal, metrics, mul
     })
 
     const messageStream = pbStream(stream).pb(Message)
+    const peerConnection = new RTCPeerConnection(rtcConfiguration)
 
     try {
       // we create the channel so that the RTCPeerConnection has a component for
@@ -150,7 +151,8 @@ export async function initiateConnection ({ peerConnection, signal, metrics, mul
       log.trace('initiator connected to remote address %s', ma)
 
       return {
-        remoteAddress: ma
+        remoteAddress: ma,
+        peerConnection
       }
     } catch (err: any) {
       peerConnection.close()
diff --git a/packages/transport-webrtc/src/private-to-private/transport.ts b/packages/transport-webrtc/src/private-to-private/transport.ts
index 89ad2ee48b..6e283dabb3 100644
--- a/packages/transport-webrtc/src/private-to-private/transport.ts
+++ b/packages/transport-webrtc/src/private-to-private/transport.ts
@@ -133,14 +133,7 @@ export class WebRTCTransport implements Transport, Startable {
   async dial (ma: Multiaddr, options: DialOptions): Promise<Connection> {
     this.log.trace('dialing address: %a', ma)
 
-    const peerConnection = new RTCPeerConnection(this.init.rtcConfiguration)
-    const muxerFactory = new DataChannelMuxerFactory(this.components, {
-      peerConnection,
-      dataChannelOptions: this.init.dataChannel
-    })
-
-    const { remoteAddress } = await initiateConnection({
-      peerConnection,
+    const { remoteAddress, peerConnection } = await initiateConnection({
       multiaddr: ma,
       dataChannelOptions: this.init.dataChannel,
       signal: options.signal,
@@ -156,6 +149,11 @@ export class WebRTCTransport implements Transport, Startable {
       metrics: this.metrics?.dialerEvents
     })
 
+    const muxerFactory = new DataChannelMuxerFactory(this.components, {
+      peerConnection,
+      dataChannelOptions: this.init.dataChannel
+    })
+
     const connection = await options.upgrader.upgradeOutbound(webRTCConn, {
       skipProtection: true,
       skipEncryption: true,