Enable on headers handler to reject connection modifying headers param

lib/websocket-server.js

@@ -389,6 +389,13 @@ class WebSocketServer extends EventEmitter {
     socket.write(headers.concat('\r\n').join('\r\n'));
     socket.removeListener('error', socketOnError);
 
+    if (headers.length==0 || !headers[0].startsWith('HTTP/1.1 101 ')) { 
+      //An error status and headers were just send. Terminate the connection
+      socket.end();
+      //as the socket is not writable the code will not be used
+      return abortHandshake(socket, 500); 
+    }
+
     ws.setSocket(socket, head, {
       maxPayload: this.options.maxPayload,
       skipUTF8Validation: this.options.skipUTF8Validation

test/onheaeder-httperr.test.js

@@ -0,0 +1,53 @@
+/* eslint no-unused-vars: ["error", { "varsIgnorePattern": "^ws$" }] */
+
+'use strict';
+
+const WebSocket = require('..');
+
+
+describe('WebSocketServer', () => { 
+  it('successfully rejects a connection via error heders in on headers handler', (done) => {
+  const wss = new WebSocket.Server(
+    {
+      port: 0
+    },
+    () => {
+      const ws = new WebSocket(`ws://localhost:${wss.address().port}`);
+      wss.on('connection', (ws) => {
+        done(new Error("WSS: on connection?! We should not be here!"));
+        ws.close();
+        wss.close();
+      });
+      wss.on('headers', (headers,req)=>{
+        headers.length=0;
+        headers.push('HTTP/1.1 418 I\'m a teapot');
+        headers.push('Connection: close');
+      });
+
+      ws.on('open', () => {
+       done(new Error("WS: on connection?! We should not be here!"));
+       ws.close();
+       wss.close();
+      });
+      ws.on('error',(err)=>{
+        if (err instanceof Error) {
+          if (err.message.endsWith(' 418')) {
+            //end with no error
+            done();
+            ws.close();
+            wss.close();
+          } else {
+            done(new Error("WS: on err but err is not as expected!"));
+            ws.close();
+            wss.close();
+          }
+        } else {
+          done(new Error("WS: on err but err is not instance of Error!"));
+          ws.close();
+          wss.close();
+        }
+      });
+    }
+  );
+
+})});