fix: Re-add support for clientError listeners (#1897)

lib/server.js

@@ -205,6 +205,8 @@ function Server(options) {
     });
 
     // Now the things we can't blindly proxy
+    proxyEventWhenListenerAdded('clientError', this, this.server);
+
     this.server.on('checkContinue', function onCheckContinue(req, res) {
         if (self.listeners('checkContinue').length > 0) {
             self.emit('checkContinue', req, res);
@@ -274,6 +276,33 @@ util.inherits(Server, EventEmitter);
 
 module.exports = Server;
 
+/**
+ * Only add a listener on the wrappedEmitter when a listener for the event is
+ * added to the wrapperEmitter. This is useful when just adding a listener to
+ * the wrappedEmittter overrides/disables a default behavior.
+ *
+ * @param {string} eventName - The name of the event to proxy
+ * @param {EventEmitter} wrapperEmitter - The emitter that proxies events from the wrappedEmitter
+ * @param {EventEmitter} wrappedEmitter - The proxied emitter
+ * @returns {undefined} NA
+ */
+function proxyEventWhenListenerAdded(
+    eventName,
+    wrapperEmitter,
+    wrappedEmitter
+) {
+    var isEventProxied = false;
+    wrapperEmitter.on('newListener', function onNewListener(handledEventName) {
+        if (handledEventName === eventName && !isEventProxied) {
+            isEventProxied = true;
+            wrappedEmitter.on(
+                eventName,
+                wrapperEmitter.emit.bind(wrapperEmitter, eventName)
+            );
+        }
+    });
+}
+
 ///--- Server lifecycle methods
 
 // eslint-disable-next-line jsdoc/check-param-names

test/server.test.js

@@ -33,6 +33,8 @@ var CLIENT;
 var FAST_CLIENT;
 var SERVER;
 
+var NODE_MAJOR_VERSION = process.versions.node.split('.')[0];
+
 if (SKIP_IP_V6) {
     console.warn('IPv6 tests are skipped: No IPv6 network is available');
 }
@@ -2820,3 +2822,133 @@ test('async handler should discard value', function(t) {
         t.end();
     });
 });
+
+test('Server returns 400 on invalid method', function(t) {
+    SERVER.get('/snickers/bar', function echoId(req, res, next) {
+        res.send();
+        next();
+    });
+
+    var opts = {
+        hostname: '127.0.0.1',
+        port: PORT,
+        path: '/snickers/bar',
+        method: 'CANDYBARS',
+        agent: false
+    };
+    http.request(opts, function(res) {
+        t.equal(res.statusCode, 400);
+        t.equal(res.statusMessage, 'Bad Request');
+        res.on('data', function() {
+            t.fail('Data was sent on 400 error');
+        });
+        res.on('end', function() {
+            t.end();
+        });
+    }).end();
+});
+
+test('Server returns 4xx when header size is too large', function(t) {
+    SERVER.get('/jellybeans', function echoId(req, res, next) {
+        res.send();
+        next();
+    });
+
+    var opts = {
+        hostname: '127.0.0.1',
+        port: PORT,
+        path: '/jellybeans',
+        method: 'GET',
+        agent: false,
+        headers: {
+            'jellybean-colors': 'purple,green,red,black,pink,'.repeat(1000)
+        }
+    };
+    http.request(opts, function(res) {
+        if (NODE_MAJOR_VERSION > '10') {
+            t.equal(res.statusCode, 431);
+            t.equal(res.statusMessage, 'Request Header Fields Too Large');
+        } else {
+            t.equal(res.statusCode, 400);
+            t.equal(res.statusMessage, 'Bad Request');
+        }
+        res.on('data', function() {
+            t.fail('Data was sent on 431 error');
+        });
+        res.on('end', function() {
+            t.end();
+        });
+    }).end();
+});
+
+test('Server supports adding custom clientError listener', function(t) {
+    SERVER.get('/popcorn', function echoId(req, res, next) {
+        res.send();
+        next();
+    });
+
+    SERVER.on('clientError', function(err, socket) {
+        if (err.code !== 'HPE_HEADER_OVERFLOW') {
+            t.fail('Expected HPE_HEADER_OVERFLOW but err.code was ' + err.code);
+        }
+        socket.write("HTTP/1.1 418 I'm a teapot\r\nConnection: close\r\n\r\n");
+        socket.destroy(err);
+    });
+
+    var opts = {
+        hostname: '127.0.0.1',
+        port: PORT,
+        path: '/popcorn',
+        method: 'GET',
+        agent: false,
+        headers: {
+            'jellybean-colors': 'purple,green,red,black,pink,'.repeat(1000)
+        }
+    };
+    http.request(opts, function(res) {
+        t.equal(res.statusCode, 418);
+        t.equal(res.statusMessage, "I'm a teapot");
+        res.on('data', function() {});
+        res.on('end', function() {
+            t.end();
+        });
+    }).end();
+});
+
+test('Server correctly handles multiple clientError listeners', function(t) {
+    SERVER.get('/popcorn', function echoId(req, res, next) {
+        res.send();
+        next();
+    });
+
+    let numListenerCalls = 0;
+    SERVER.on('clientError', function(err, socket) {
+        socket.write("HTTP/1.1 418 I'm a teapot\r\nConnection: close\r\n\r\n");
+        numListenerCalls += 1;
+    });
+    SERVER.on('clientError', function(err, socket) {
+        if (numListenerCalls !== 1) {
+            t.fail('listener was called ' + numListenerCalls + ' times');
+        }
+        socket.destroy(err);
+    });
+
+    var opts = {
+        hostname: '127.0.0.1',
+        port: PORT,
+        path: '/popcorn',
+        method: 'GET',
+        agent: false,
+        headers: {
+            'jellybean-colors': 'purple,green,red,black,pink,'.repeat(1000)
+        }
+    };
+    http.request(opts, function(res) {
+        t.equal(res.statusCode, 418);
+        t.equal(res.statusMessage, "I'm a teapot");
+        res.on('data', function() {});
+        res.on('end', function() {
+            t.end();
+        });
+    }).end();
+});