[0.19.x] Rest server can be terminated by client (#4531)

A client listening on a web socket can terminate the rest server
if it is badly behaved and doesn’t cleanly disconnect

Signed-off-by: Dave Kelsey <d_kelsey@uk.ibm.com>

Author: Dave Kelsey

packages/composer-rest-server/server/server.js

@@ -192,6 +192,14 @@ module.exports = function (composer) {
                 clientTracking: true
             });
 
+            // Add a dummy error handler for a ws connection so bad websocket client
+            // doesn't kill the rest server
+            wss.on('connection', (ws) => {
+                ws.on('error', () => {
+                    // do nothing
+                });
+            });
+
             // Add a broadcast method that sends data to all connected clients.
             wss.broadcast = (data) => {
                 wss.clients.forEach((client) => {

packages/composer-rest-server/test/server/server.js

@@ -23,6 +23,7 @@ const IdCard = require('composer-common').IdCard;
 const path = require('path');
 const server = require('../../server/server');
 const WebSocket = require('ws');
+const EventEmitter = require('events');
 
 const chai = require('chai');
 const should = chai.should();
@@ -341,4 +342,25 @@ describe('server', () => {
             });
     });
 
+    it('should register an error handler on connection to a websocket and it shoud no nothing when fired', () => {
+        composerConfig.websockets = true;
+        const stubWS = new EventEmitter();
+        const wsOnSpy = sinon.spy(stubWS, 'on');
+
+
+        return server(composerConfig)
+            .then((result) => {
+                result.app.should.exist;
+                result.server.should.exist;
+                const wss = result.app.get('wss');
+                wss.should.be.an.instanceOf(WebSocket.Server);
+                wss.emit('connection', stubWS);
+                sinon.assert.calledOnce(wsOnSpy);
+                sinon.assert.calledWith(wsOnSpy, 'error');
+
+                // fire the error event
+                stubWS.emit('error');
+            });
+    });
+
 });