Webserver double freeing _currentHeaders on destruction

[mongozmaki]

Destructor of ESP8266WebServer double-frees _currentHeaders.
The problem is, that the destructor frees _currentHeaders and sets _headerKeysCount=0 and than calls close(), which checks if(!_headerKeysCount) (=true) and calls collectHeaders(0, 0) which frees _currentHeaders again (because it is not set to nullptr).
A fix would be to call close() in the beginning of the destructor.
A more extensive fix would be to call collectHeaders(0, 0) in begin() and not in close().

Code fixed:

ESP8266WebServer::~ESP8266WebServer() {
  //Close here
  close();
  if (_currentHeaders) {
    delete[]_currentHeaders;
  }
  _headerKeysCount = 0;
  RequestHandler* handler = _firstHandler;
  while (handler) {
    RequestHandler* next = handler->next();
    delete handler;
    handler = next;
  }
  //Not here
  //close();
}

Sketch

#include <Arduino.h>

void setup() {
Serial.begin(115200);
  {
    Serial.println("Creating server");
    ESP8266WebServer server;
    const char * headerkeys[] = { "If-None-Match" };
    Serial.println("Setting headers");
    //Crashes also without calling collectHeaders
    server.collectHeaders(headerkeys, 1);
    Serial.println("Begin server");
    server.begin();
    Serial.println("About to delete server");
  } //Deleted here
  Serial.println("Server deleted");
}

void loop() {
}

Debug Messages

Creating server
Setting headers
Begin server
About to delete server
*** CRASH ***

[d-a-v]

That would make a good pull-request.

[earlephilhower]

@mongozmaki Would you like to submit a PR for this?

It will also fix the same problem on the SecureServer, which uses this class' destructor.

[mongozmaki]

Yes, I tried creating a PR but didn't work for some reason. If I find a minor issue again, I will do that.
Thanks for the fix!

[earlephilhower]

No problem, @mongozmaki . I've referenced you in the change note, and appreciate the detailed error, repro instructions, and fix you did. Nothing for me to do, really. :)

Next one, when you push to your private forked repo, you can go to its github website and there should be a "submit pull request" button right at the top of the page (for about 5 mins after a push) which should get you going.