Add enableDataChannel option to peer

README.md

@@ -268,6 +268,7 @@ If `opts` is specified, then the default options (shown below) will be overridde
 ```
 {
   initiator: false,
+  enableDataChannel: true,
   channelConfig: {},
   channelName: '<random string>',
   config: { iceServers: [{ urls: 'stun:stun.l.google.com:19302' }, { urls: 'stun:global.stun.twilio.com:3478?transport=udp' }] },
@@ -286,6 +287,7 @@ If `opts` is specified, then the default options (shown below) will be overridde
 The options do the following:
 
 - `initiator` - set to `true` if this is the initiating peer
+- `enableDataChannel` - set to `false` if no data channel should be created for this peer
 - `channelConfig` - custom webrtc data channel configuration (used by [`createDataChannel`](https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/createDataChannel))
 - `channelName` - custom webrtc data channel name
 - `config` - custom webrtc configuration (used by [`RTCPeerConnection`](https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection) constructor)
@@ -456,6 +458,7 @@ Possible error codes:
 - `ERR_ICE_CONNECTION_FAILURE`
 - `ERR_SIGNALING`
 - `ERR_DATA_CHANNEL`
+- `ERR_DISABLED_DATA_CHANNEL`
 - `ERR_CONNECTION_FAILURE`
 
 

index.js

@@ -41,6 +41,7 @@ class Peer extends stream.Duplex {
       : null
 
     this.initiator = opts.initiator || false
+    this.enableDataChannel = opts.enableDataChannel ?? true
     this.channelConfig = opts.channelConfig || Peer.channelConfig
     this.channelNegotiated = this.channelConfig.negotiated
     this.config = Object.assign({}, Peer.config, opts.config)
@@ -137,13 +138,15 @@ class Peer extends stream.Duplex {
     // - onfingerprintfailure
     // - onnegotiationneeded
 
-    if (this.initiator || this.channelNegotiated) {
-      this._setupData({
-        channel: this._pc.createDataChannel(this.channelName, this.channelConfig)
-      })
-    } else {
-      this._pc.ondatachannel = event => {
-        this._setupData(event)
+    if (this.enableDataChannel) {
+      if (this.initiator || this.channelNegotiated) {
+        this._setupData({
+          channel: this._pc.createDataChannel(this.channelName, this.channelConfig)
+        })
+      } else {
+        this._pc.ondatachannel = event => {
+          this._setupData(event)
+        }
       }
     }
 
@@ -172,7 +175,7 @@ class Peer extends stream.Duplex {
   // HACK: it's possible channel.readyState is "closing" before peer.destroy() fires
   // https://bugs.chromium.org/p/chromium/issues/detail?id=882743
   get connected () {
-    return (this._connected && this._channel.readyState === 'open')
+    return (this._connected && this._channel && this._channel.readyState === 'open')
   }
 
   address () {
@@ -244,6 +247,7 @@ class Peer extends stream.Duplex {
    * @param {ArrayBufferView|ArrayBuffer|Buffer|string|Blob} chunk
    */
   send (chunk) {
+    if (!this.enableDataChannel) throw errCode(new Error('Cannot write if data channel is disabled'), 'ERR_DISABLED_DATA_CHANNEL')
     if (this.destroying) return
     if (this.destroyed) throw errCode(new Error('cannot send after peer is destroyed'), 'ERR_DESTROYED')
     this._channel.send(chunk)
@@ -500,6 +504,12 @@ class Peer extends stream.Duplex {
   }
 
   _setupData (event) {
+    if(!this.enableDataChannel)
+    {
+      // Configured to NOT use a data channel, calling setupData is invalid in this case.
+      return this.destroy(errCode(new Error('Tried to create data channel despite disabled data channel.'), 'ERR_DISABLED_DATA_CHANNEL'))
+    }
+
     if (!event.channel) {
       // In some situations `pc.createDataChannel()` returns `undefined` (in wrtc),
       // which is invalid behavior. Handle it gracefully.
@@ -548,11 +558,23 @@ class Peer extends stream.Duplex {
     }, CHANNEL_CLOSING_TIMEOUT)
   }
 
-  _read () {}
+  _read () {
+    if(!this.enableDataChannel)
+    {
+      // Calling read without data channel is invalid, throw error.
+      throw errCode(new Error('Cannot read with data channel not enabled.'), 'ERR_DISABLED_DATA_CHANNEL')
+    }
+  }
 
   _write (chunk, encoding, cb) {
     if (this.destroyed) return cb(errCode(new Error('cannot write after peer is destroyed'), 'ERR_DATA_CHANNEL'))
 
+    if(!this.enableDataChannel)
+    {
+      // Calling write without data channel is invalid, throw error.
+      return cb(errCode(new Error('Cannot write with data channel not enabled.'), 'ERR_DISABLED_DATA_CHANNEL'))
+    }
+
     if (this._connected) {
       try {
         this.send(chunk)

test/basic.js

@@ -272,3 +272,34 @@ test('ensure iceStateChange fires when connection failed', (t) => {
   peer.destroy()
   peer._pc.oniceconnectionstatechange()
 })
+
+test('ensure enableDataChannel is being respected', async (t) => {
+  t.plan(4)
+  const peer = new Peer({ config, initiator: true, wrtc: common.wrtc, enableDataChannel: false })
+
+  const onSignalPromise = new Promise((resolve,reject) => {
+    peer.on('signal', data => {
+      resolve(data);
+    });
+  });
+
+  t.throws(function(){peer.send("data")},"Sending data is not allowed with enableDataChannel set to false");
+  t.throws(function(){peer.write("data")},"Writing data is not allowed with enableDataChannel set to false");
+  t.throws(function(){peer.read()},"Reading data is not allowed with enableDataChannel set to false");
+
+  const data = await onSignalPromise;
+  const lines = data.sdp.split("\r\n");
+
+  // Determining whether we have found any media descriptions in SDP offer
+  // Since no data channel, or audio/video channel is being created, we shouldn't find any
+  let mLines = [];
+  lines.forEach(line => {
+    if(line.substring = "m=")
+    {
+      mLines.concat(line)
+    }
+  });
+  t.assert(mLines.length === 0, "No media descriptions have been created");
+
+  t.end();
+})