fix: properly handle prematurely closed requests

[zeeshanakram3]

addresses #4760

Problem

Sometimes a request can be prematurely closed by client or due to bad network conditions. Whenever that happens, an event handler on response object (res), manually closes the response by calling res.end(). However, the problem is that even if the response closes the the control flow is passed the request handlers which then tries to set headers on a closed response, and hence the error.

How to reproduce

In routeWrapper function, manually close the response by calling res.socket?.destory(),

  protected routeWrapper(handler: express.RequestHandler) {
    return async (req: express.Request, res: express.Response, next: express.NextFunction): Promise<void> => {
      // Fix for express-winston in order to also log prematurely closed requests
      
+     res.socket.?destroy()
      res.on('close', () => {
        res.locals.prematurelyClosed = !res.writableFinished
        res.end()
      })
      
+     await sleep(1000) // sleep for 1 second to make sure that request does not finish before socket destroy event is emitted
      try {
        await handler(req, res, next)
      } catch (err) {
        next(err)
      }
    }
  }

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1 Ignored Deployment

Name	Status	Preview	Updated (UTC)
pioneer-testnet	⬜️ Ignored (Inspect)		Jul 12, 2023 4:30am

[mnaamani]

This should not be necessary. My hunch is that the root cause of this behavior is the invocation of res.end() in the close event handler on line 26. It just looks wrong. I'll test and confirm

[mnaamani]

confirmed that by removing the res.end() and the newly added conditional on res.headerSent, invoking socket.destroy(), execution does not reach invokation of await handler(req, res, next).
Also confirmed the log correctly includes the meta information for prematurelyClosed:

2023-06-12 18:57:17 2023-06-12 14:57:17:5717 PublicApi http: HTTP GET /api/v1/status
2023-06-12 18:57:17 {
2023-06-12 18:57:17     "meta": {
2023-06-12 18:57:17         "req": {
2023-06-12 18:57:17             "url": "/api/v1/status",
2023-06-12 18:57:17             "headers": {
2023-06-12 18:57:17                 "host": "localhost:3334",
2023-06-12 18:57:17                 "user-agent": "curl/8.1.2",
2023-06-12 18:57:17                 "accept": "*/*"
2023-06-12 18:57:17             },
2023-06-12 18:57:17             "method": "GET",
2023-06-12 18:57:17             "httpVersion": "1.1",
2023-06-12 18:57:17             "originalUrl": "/api/v1/status",
2023-06-12 18:57:17             "query": {}
2023-06-12 18:57:17         },
2023-06-12 18:57:17         "res": {
2023-06-12 18:57:17             "statusCode": 200
2023-06-12 18:57:17         },
2023-06-12 18:57:17         "responseTime": 60,
2023-06-12 18:57:17         "prematurelyClosed": true
2023-06-12 18:57:17     }
2023-06-12 18:57:17 }

[mnaamani]

A simpler solution is to just not call res.end() in the closed event handler.