[feature] Add ability to skip UTF-8 validation (#1928)

Add the `skipUTF8Validation` option to skip UTF-8 validation for text
and close messages.

Refs: #1878
Closes #1924

doc/ws.md

@@ -78,6 +78,9 @@ This class represents a WebSocket server. It extends the `EventEmitter`.
   - `clientTracking` {Boolean} Specifies whether or not to track clients.
   - `perMessageDeflate` {Boolean|Object} Enable/disable permessage-deflate.
   - `maxPayload` {Number} The maximum allowed message size in bytes.
+  - `skipUTF8Validation` {Boolean} Specifies whether or not to skip UTF-8
+    validation for text and close messages. Defaults to `false`. Set to `true`
+    only if clients are trusted.
 - `callback` {Function}
 
 Create a new server instance. One and only one of `port`, `server` or `noServer`
@@ -273,6 +276,9 @@ This class represents a WebSocket. It extends the `EventEmitter`.
   - `origin` {String} Value of the `Origin` or `Sec-WebSocket-Origin` header
     depending on the `protocolVersion`.
   - `maxPayload` {Number} The maximum allowed message size in bytes.
+  - `skipUTF8Validation` {Boolean} Specifies whether or not to skip UTF-8
+    validation for text and close messages. Defaults to `false`. Set to `true`
+    only if the server is trusted.
   - Any other option allowed in [http.request()][] or [https.request()][].
     Options given do not have any effect if parsed from the URL given with the
     `address` parameter.

lib/receiver.js

@@ -43,6 +43,7 @@ class Receiver extends Writable {
     this._extensions = options.extensions || {};
     this._isServer = !!options.isServer;
     this._maxPayload = options.maxPayload | 0;
+    this._skipUTF8Validation = !!options.skipUTF8Validation;
     this[kWebSocket] = undefined;
 
     this._bufferedBytes = 0;
@@ -505,7 +506,7 @@ class Receiver extends Writable {
       } else {
         const buf = concat(fragments, messageLength);
 
-        if (!isValidUTF8(buf)) {
+        if (!this._skipUTF8Validation && !isValidUTF8(buf)) {
           this._loop = false;
           return error(
             Error,
@@ -560,7 +561,7 @@ class Receiver extends Writable {
 
         const buf = data.slice(2);
 
-        if (!isValidUTF8(buf)) {
+        if (!this._skipUTF8Validation && !isValidUTF8(buf)) {
           return error(
             Error,
             'invalid UTF-8 sequence',

lib/websocket-server.js

@@ -46,6 +46,8 @@ class WebSocketServer extends EventEmitter {
    * @param {Number} [options.port] The port where to bind the server
    * @param {(http.Server|https.Server)} [options.server] A pre-created HTTP/S
    *     server to use
+   * @param {Boolean} [options.skipUTF8Validation=false] Specifies whether or
+   *     not to skip UTF-8 validation for text and close messages
    * @param {Function} [options.verifyClient] A hook to reject connections
    * @param {Function} [callback] A listener for the `listening` event
    */
@@ -54,6 +56,7 @@ class WebSocketServer extends EventEmitter {
 
     options = {
       maxPayload: 100 * 1024 * 1024,
+      skipUTF8Validation: false,
       perMessageDeflate: false,
       handleProtocols: null,
       clientTracking: true,
@@ -386,7 +389,10 @@ class WebSocketServer extends EventEmitter {
     socket.write(headers.concat('\r\n').join('\r\n'));
     socket.removeListener('error', socketOnError);
 
-    ws.setSocket(socket, head, this.options.maxPayload);
+    ws.setSocket(socket, head, {
+      maxPayload: this.options.maxPayload,
+      skipUTF8Validation: this.options.skipUTF8Validation
+    });
 
     if (this.clients) {
       this.clients.add(ws);

lib/websocket.js

@@ -180,15 +180,19 @@ class WebSocket extends EventEmitter {
    * @param {(net.Socket|tls.Socket)} socket The network socket between the
    *     server and client
    * @param {Buffer} head The first packet of the upgraded stream
-   * @param {Number} [maxPayload=0] The maximum allowed message size
+   * @param {Object} [options] Options object
+   * @param {Number} [options.maxPayload=0] The maximum allowed message size
+   * @param {Boolean} [options.skipUTF8Validation=false] Specifies whether or
+   *     not to skip UTF-8 validation for text and close messages
    * @private
    */
-  setSocket(socket, head, maxPayload) {
+  setSocket(socket, head, options = {}) {
     const receiver = new Receiver({
       binaryType: this.binaryType,
       extensions: this._extensions,
       isServer: this._isServer,
-      maxPayload
+      maxPayload: options.maxPayload,
+      skipUTF8Validation: options.skipUTF8Validation
     });
 
     this._sender = new Sender(socket, this._extensions);
@@ -575,12 +579,15 @@ module.exports = WebSocket;
  *     redirects
  * @param {Number} [options.maxRedirects=10] The maximum number of redirects
  *     allowed
+ * @param {Boolean} [options.skipUTF8Validation=false] Specifies whether or
+ *     not to skip UTF-8 validation for text and close messages
  * @private
  */
 function initAsClient(websocket, address, protocols, options) {
   const opts = {
     protocolVersion: protocolVersions[1],
     maxPayload: 100 * 1024 * 1024,
+    skipUTF8Validation: false,
     perMessageDeflate: true,
     followRedirects: false,
     maxRedirects: 10,
@@ -832,7 +839,10 @@ function initAsClient(websocket, address, protocols, options) {
         perMessageDeflate;
     }
 
-    websocket.setSocket(socket, head, opts.maxPayload);
+    websocket.setSocket(socket, head, {
+      maxPayload: opts.maxPayload,
+      skipUTF8Validation: opts.skipUTF8Validation
+    });
   });
 }
 

test/receiver.test.js

@@ -1059,4 +1059,28 @@ describe('Receiver', () => {
       }).forEach((buf) => receiver.write(buf));
     });
   });
+
+  it('honors the `skipUTF8Validation` option (1/2)', (done) => {
+    const receiver = new Receiver({ skipUTF8Validation: true });
+
+    receiver.on('message', (data, isBinary) => {
+      assert.deepStrictEqual(data, Buffer.from([0xf8]));
+      assert.ok(!isBinary);
+      done();
+    });
+
+    receiver.write(Buffer.from([0x81, 0x01, 0xf8]));
+  });
+
+  it('honors the `skipUTF8Validation` option (2/2)', (done) => {
+    const receiver = new Receiver({ skipUTF8Validation: true });
+
+    receiver.on('conclude', (code, data) => {
+      assert.strictEqual(code, 1000);
+      assert.deepStrictEqual(data, Buffer.from([0xf8]));
+      done();
+    });
+
+    receiver.write(Buffer.from([0x88, 0x03, 0x03, 0xe8, 0xf8]));
+  });
 });