User shall be able to get a notification which AsyncWebServerRequest is released

[amkrk]

When a data to be sent needs to be pulled from external MCU, a pointer into related AsyncWebServerRequest can be sent ESP->MCU, and then ESP<-MCU (response with the data).

When the data arrives at ESP user application code running on it can cast a pointer into AsyncWebServerRequest and use it for building AsyncWebServerResponse.

But the TCP connection and associated AsyncWebServerRequest can be released in a meantime (before ESP will get the data data from the MCU)...

In order to secure the case the pointer needs to be validated before casting it to AsyncWebServerRequest.

Application code shall then maintain a list of active AsyncWebServerRequest for this.

The change to ESPAsyncWebServer helps to do it. When the connection is released it passes the pointer into user's callback as a parameter, so user can remove the invalid pointe from the list.

Following can be example user's application code which makes it done:

https://github.com/me-no-dev/ESPAsyncWebServer/commit/39e9b67651255c5365e03ba1eea0579f018dd013

---

std::deque<AsyncWebServerRequest*> activeHttpRequests;

bool isRequestValid(AsyncWebServerRequest *request) { for(int i=0; i<activeHttpRequests.size(); i++) { if (activeHttpRequests[i]==request) return true; } return false; }

void httpClientRegister(AsyncWebServerRequest *request) { activeHttpRequests.push_back(request); }

void httpClientDisconnectionHandler(AsyncWebServerRequest request) // <- the callback needs 'this' (AsyncWebServerRequest) as a parameter, change the change to ESPAsyncWebServer code { std::deque<AsyncWebServerRequest*>::iterator it;

it = activeHttpRequests.begin();
while (it != activeHttpRequests.end()) {
    if (*it == request) break;
    it++;       
}

activeHttpRequests.erase(it);

}

void ApiOnBody(AsyncWebServerRequest *request, uint8_t *data, size_t len, size_t index, size_t total) //this is called when POST request comes to ESP over WiFi { ... httpClientRegister(request); request->onDisconnect(httpClientDisconnectionHandler); ... }

void sendApiResponseToHttpClient(const char* data) // the is called when ESP recives data from MCU { int32_t dataSeparatorOffset; AsyncWebServerRequest *request;

... get 'request' ptr value from msg incomming from MCU ...

if(!isRequestValid(request)) return; // too late, disconnected already

AsyncWebServerResponse *response = request->beginResponse(200, "text/xml", data); if(NULL!=response) request->send(response); }

[amkrk]

https://github.com/me-no-dev/ESPAsyncWebServer/commit/39e9b67651255c5365e03ba1eea0579f018dd013 solves it.

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