Infinite waiting for CURLOPT_WRITEFUNCTION in case of no response

Description

To reach an address that responds every 5 seconds, I use CURLOPT_WRITEFUNCTION. Since I want to maintain an infinite connection, I have CURLOPT_TIMEOUT => 0.

function writer($ch, $data) {
  handler($data);
  return strlen($data);
}

$ch = curl_init("$urlcam/cgi-bin/eventManager.cgi?action=attach&codes=[NewFile]&heartbeat=5");
curl_setopt_array($ch, [
        CURLOPT_CONNECTTIMEOUT => 20,
        CURLOPT_TIMEOUT => 0,
        CURLOPT_RETURNTRANSFER => 1,
        CURLOPT_WRITEFUNCTION => 'writer'
    ]);

$result = curl_exec($ch);
curl_close($ch);

The response looks like this:

--myboundary
Content-Type: text/plain
Content-Length: 9
Heartbeat
--myboundary
Content-Type: text/plain
Content-Length: 9
Heartbeat
...

Everything works as long as there is a response from the url. However, if the url stops responding, nothing happens. No error or warning. The PHP script will stay inside the "writer" function and never leave it.

For example, if you implement this functionality using fopen:

$resource = fopen("http://".$host.$uri, 'r', false, $context);
while (!feof($resource)) {
    print_r(date("d-m-Y H:i:s"));
    $line = fgets($resource);
    if (str_contains($line,"--myboundary")) {
        handler($response);
        $response = '';
    } else {
        $response.=$line;
    }
}

Then the print_r function will be called every minute. Yes, if the url is restored, the fopen connection will not be restored, but at least we can handle the error/state to restart the script. In the case of CURL, this cannot be done as nothing happens.

We need to add functionality to leave the function specified in CURLOPT_WRITEFUNCTION. I suppose you could take CURLOPT_CONNECTTIMEOUT and display an error if the WRITEFUNCTION has not received a response within that time.

PHP Version

8.1.23

Operating System

Ubuntu 20.04

L’issue fournit une reproduction en PHP avec curl_exec utilisant CURLOPT_WRITEFUNCTION et une URL diffusant indéfiniment ; commencez par reproduire le cas de réponse bloquée et suivre le traitement de l’option dans php-src. Comparez le comportement observé avec la sémantique demandée du timeout et des erreurs, et considérez le travail terminé lorsqu’une période sans réponse peut être détectée et gérée comme décrit.