Add callback handler to report internal HTTP parsing errors(431, 400, 505)

docs/index.d.ts

@@ -329,6 +329,9 @@ export interface TemplatedApp {
     missingServerName(cb: (hostname: string) => void) : TemplatedApp;
     /** Attaches a "filter" function to track socket connections / disconnections */
     filter(cb: (res: HttpResponse, count: Number) => void | Promise<void>) : TemplatedApp;
+    /** Registers an HTTP parsing error handler that is called when malformed HTTP requests are encountered.
+     * The handler receives the request object (or null if request is too malformed), HTTP status code, and complete response body. */
+    log(cb: (req: HttpRequest | null, statusCode: number, responseBody: ArrayBuffer) => void | Promise<void>) : TemplatedApp;
     /** Closes all sockets including listen sockets. This will forcefully terminate all connections. */
     close() : TemplatedApp;
 }

examples/HttpParsingLogHandling.js

@@ -0,0 +1,30 @@
+const uWS = require('../src/uws.js');
+
+const app = uWS.App({
+  // Optional SSL configuration
+}).log((req, httpStatus, responseBody) => {
+  console.log('HTTP parsing error occurred with status:', httpStatus);
+
+  if (req) {
+    console.log('Request URL:', req.getUrl());
+    console.log('Request method:', req.getMethod());
+    console.log('Request headers:', req.getHeader('host'));
+  } else {
+    console.log('Request information not available (parsing failed early)');
+  }
+
+  // Log the response body that will be sent to the client
+  console.log('Response body length:', responseBody.byteLength);
+  console.log('Response preview:', Buffer.from(responseBody).toString().substring(0, 100) + '...');
+
+  // High-level program can now handle the error gracefully
+  // The socket will be closed automatically after this handler runs
+}).get('/*', (res, req) => {
+  res.end('Hello World!');
+}).listen(9001, (token) => {
+  if (token) {
+    console.log('Listening to port 9001 with HTTP parsing error handling');
+  } else {
+    console.log('Failed to listen to port 9001');
+  }
+});

src/AppWrapper.h

@@ -570,6 +570,45 @@ void uWS_App_filter(const FunctionCallbackInfo<Value> &args) {
     args.GetReturnValue().Set(args.This());
 }
 
+template <typename APP>
+void uWS_App_log(const FunctionCallbackInfo<Value> &args) {
+    APP *app = (APP *) args.This()->GetAlignedPointerFromInternalField(0);
+
+    /* Handler */
+    Callback checkedCallback(args.GetIsolate(), args[0]);
+    if (checkedCallback.isInvalid(args)) {
+        return;
+    }
+    UniquePersistent<Function> cb = checkedCallback.getFunction();
+
+    /* This function requires perContextData */
+    PerContextData *perContextData = (PerContextData *) Local<External>::Cast(args.Data())->Value();
+
+    app->log([cb = std::move(cb), perContextData](auto *req, int statusCode, std::string_view responseBody) {
+        Isolate *isolate = perContextData->isolate;
+        HandleScope hs(isolate);
+
+        Local<Object> reqObject;
+        if (req) {
+            reqObject = perContextData->reqTemplate[getAppTypeIndex<APP>()].Get(isolate)->Clone();
+            reqObject->SetAlignedPointerInInternalField(0, req);
+        } else {
+            reqObject = Local<Object>::Cast(Null(isolate));
+        }
+
+        Local<ArrayBuffer> responseBodyBuffer = ArrayBuffer_New(isolate, (void *) responseBody.data(), responseBody.length());
+
+        Local<Value> argv[] = {reqObject, Local<Value>::Cast(Integer::New(isolate, statusCode)), responseBodyBuffer};
+        CallJS(isolate, cb.Get(isolate), 3, argv);
+
+        /* Important: we clear the ArrayBuffer to make sure it is not invalidly used after return */
+        responseBodyBuffer->Detach();
+    });
+
+    args.GetReturnValue().Set(args.This());
+}
+
+
 template <typename APP>
 void uWS_App_domain(const FunctionCallbackInfo<Value> &args) {
     APP *app = (APP *) args.This()->GetAlignedPointerFromInternalField(0);
@@ -996,6 +1035,7 @@ void uWS_App(const FunctionCallbackInfo<Value> &args) {
         appTemplate->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "close", NewStringType::kNormal).ToLocalChecked(), FunctionTemplate::New(isolate, uWS_App_close<APP>, args.Data()));
         appTemplate->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "listen_unix", NewStringType::kNormal).ToLocalChecked(), FunctionTemplate::New(isolate, uWS_App_listen_unix<APP>, args.Data()));
         appTemplate->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "filter", NewStringType::kNormal).ToLocalChecked(), FunctionTemplate::New(isolate, uWS_App_filter<APP>, args.Data()));
+        appTemplate->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "log", NewStringType::kNormal).ToLocalChecked(), FunctionTemplate::New(isolate, uWS_App_log<APP>, args.Data()));
 
         /* load balancing */
         appTemplate->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "removeChildAppDescriptor", NewStringType::kNormal).ToLocalChecked(), FunctionTemplate::New(isolate, uWS_App_removeChildApp<APP>, args.Data()));