From 76847bbef197fdd2b644e842ad607ffd60995aba Mon Sep 17 00:00:00 2001
From: Lorenzo Blasa <lblasa@fb.com>
Date: Wed, 16 Mar 2022 02:26:42 -0700
Subject: [PATCH] Do not emit errors when unable to extract client query

Summary:
^

Usually, when launching Chrome, this error will take place a significat amount of times. By looking at the HTTP request, it is difficult to determine the origin other than being a Chrome extension.

There's no actionable items in Flipper, so do not emit the error.

Changelog: Do not emit errors when unable to extract client query

Reviewed By: antonk52

Differential Revision: D34898603

fbshipit-source-id: fbeb2db7ec2914669192cbebc2e6b15464e31827
---
 desktop/flipper-common/src/index.tsx          |  1 +
 desktop/flipper-common/src/utils/errors.tsx   |  8 ++++++++
 .../src/comms/ServerWebSocket.tsx             | 18 +++++++++++++-----
 .../comms/__tests__/ServerWebSocket.node.tsx  | 19 -------------------
 4 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/desktop/flipper-common/src/index.tsx b/desktop/flipper-common/src/index.tsx
index e5e1e1214..e014558f9 100644
--- a/desktop/flipper-common/src/index.tsx
+++ b/desktop/flipper-common/src/index.tsx
@@ -37,6 +37,7 @@ export {
 export {
   ConnectivityError,
   CancelledPromiseError,
+  UnableToExtractClientQueryError,
   UserUnauthorizedError,
   UserNotSignedInError,
   NoLongerConnectedToClientError,
diff --git a/desktop/flipper-common/src/utils/errors.tsx b/desktop/flipper-common/src/utils/errors.tsx
index 3eb9be44e..05f83e306 100644
--- a/desktop/flipper-common/src/utils/errors.tsx
+++ b/desktop/flipper-common/src/utils/errors.tsx
@@ -30,6 +30,14 @@ export function isConnectivityOrAuthError(
   );
 }
 
+export class UnableToExtractClientQueryError extends Error {
+  constructor(msg: string) {
+    super(msg);
+    this.name = 'UnableToExtractClientQueryError';
+  }
+  name: 'UnableToExtractClientQueryError';
+}
+
 export class CancelledPromiseError extends Error {
   constructor(msg: string) {
     super(msg);
diff --git a/desktop/flipper-server-core/src/comms/ServerWebSocket.tsx b/desktop/flipper-server-core/src/comms/ServerWebSocket.tsx
index 94cdf4d93..17a21bcdc 100644
--- a/desktop/flipper-server-core/src/comms/ServerWebSocket.tsx
+++ b/desktop/flipper-server-core/src/comms/ServerWebSocket.tsx
@@ -17,7 +17,7 @@ import WebSocket, {
 import {createServer as createHttpsServer} from 'https';
 import {createServer as createHttpServer} from 'http';
 import querystring from 'querystring';
-import {ClientQuery} from 'flipper-common';
+import {ClientQuery, UnableToExtractClientQueryError} from 'flipper-common';
 import {
   assertNotNull,
   parseClientQuery,
@@ -101,14 +101,22 @@ class ServerWebSocket extends ServerAdapter {
         try {
           this.onConnection(ws, request);
         } catch (error) {
+          // TODO: Investigate if we need to close the socket in the `error` listener
+          // DRI: @aigoncharov
+          ws.close(WSCloseCode.InternalError);
+
+          if (error instanceof UnableToExtractClientQueryError) {
+            // If we are unable to extract the client query, do not emit an error.
+            // It cannot be determined if the client is legitimately trying to establish
+            // a connection with Flipper or some other process is trying to connect to
+            // the port currently used by Flipper.
+            return;
+          }
           // If an exception is thrown, an `error` event is not emitted automatically.
           // We need to explicitly handle the error and emit an error manually.
           // If we leave it unhanled, the process just dies
           // https://replit.com/@aigoncharov/WS-error-handling#index.js
           ws.emit('error', error);
-          // TODO: Investigate if we need to close the socket in the `error` listener
-          // DRI: @aigoncharov
-          ws.close(WSCloseCode.InternalError);
         }
       },
     );
@@ -185,7 +193,7 @@ class ServerWebSocket extends ServerAdapter {
       console.warn(
         '[conn] Unable to extract the client query from the request URL.',
       );
-      throw new Error(
+      throw new UnableToExtractClientQueryError(
         '[conn] Unable to extract the client query from the request URL.',
       );
     }
diff --git a/desktop/flipper-server-core/src/comms/__tests__/ServerWebSocket.node.tsx b/desktop/flipper-server-core/src/comms/__tests__/ServerWebSocket.node.tsx
index 3eaa85e6c..2a244bd75 100644
--- a/desktop/flipper-server-core/src/comms/__tests__/ServerWebSocket.node.tsx
+++ b/desktop/flipper-server-core/src/comms/__tests__/ServerWebSocket.node.tsx
@@ -100,25 +100,6 @@ describe('ServerWebSocket', () => {
     expect(mockSEListener.onError).toBeCalledTimes(0); // no onError triggered, as start throws already
   });
 
-  test('calls listener onError if a connection attempt fails', async () => {
-    const mockSEListener = createMockSEListener();
-
-    server = new ServerWebSocket(mockSEListener);
-
-    const port = await server.start(0);
-
-    expect(mockSEListener.onError).toBeCalledTimes(0);
-    // We pass a conection URL without required params hoping that it is going to fail
-    wsClient = new WebSocket(`ws://localhost:${port}`);
-    await new Promise<void>((resolve) => {
-      wsClient!.onclose = () => {
-        resolve();
-      };
-    });
-    wsClient = undefined;
-    expect(mockSEListener.onError).toBeCalledTimes(1);
-  });
-
   test('calls listener onError if a message handling fails', async () => {
     const mockSEListener = createMockSEListener();