CURL issues in 8.3.7

[HeavenCore]

Description

The following code (unchanged for years) is suddenly breaking in PHP 8.3.7 64bit NTS on IIS 10

<?php         
        $ch  = curl_init();
        $httpHeaders = array("Cache-Control: no-cache");
        $postStr = "grant_type=authorization_code&code=REDACTED&redirect_uri=https%3A%2F%2Fwww.REDACTED.co.uk%2Ffoobar%2Fnhs-login%2F&client_id=REDACTED&client_assertion_type=urn%3Aietf%3Aparams%3Aoauth%3Aclient-assertion-type%3Ajwt-bearer&client_assertion=REDACTED";
		
            if ($postStr != "") {
                curl_setopt($ch, CURLOPT_POST, 1);
                curl_setopt($ch, CURLOPT_POSTFIELDS, $postStr);
            }

        curl_setopt($ch, CURLOPT_ENCODING, "");
        curl_setopt($ch, CURLOPT_HTTPHEADER, $httpHeaders);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
        curl_setopt($ch, CURLOPT_TIMEOUT, $timeoutInSeconds);
        curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1");

        $response->response = curl_exec($ch);

All of a sudden curl_exec() is returning false, more interestingly, curl_error($ch) returns an empty string!

Rolling back to PHP 8.3.3 fixes the problem and everything works as normal.

Digging a little deaper I added extra logging:

<?php      
    private function getCurlError($curlHandle) {
        $ermsg = parseString(curl_error($curlHandle));
        $ercode = parseString(curl_errno($curlHandle));
        $ermsgcode = parseString(curl_strerror($ercode));

        return "ErrorNo: " . $ercode . ", ErrorNoStr: " . $ermsgcode . ", " . $ermsg;
    } 

        //#### Fetch Results
        $response->responseCode = parseInt(curl_getinfo($ch, CURLINFO_HTTP_CODE));

        //#### Check Results
        if (!$response->response) {
            $response->errorStr = "HTTP Error: CURL RETURNED FALSE (" . $this->getCurlError($ch) . ") with status code " . $response->responseCode . ": " . $url;
            $response->result = false;
        } elseif ($response->responseCode < 200 || $response->responseCode > 299) {
            $response->errorStr = "HTTP Error: INVALID HTTP STATUS (" . $response->responseCode . " - expected 2xx): " . $url . " #### RESPONSE: " . $response->response;
            $response->result = false;
        } elseif (parseString($response->response) === "" || parseString($response->response) === "ERROR") {
            $response->errorStr = "HTTP Error: BAD RESPONSE (" . $response->response . "): " . $url;
            $response->result = false;
        } else {
            $response->response = parseString($response->response);
            $response->result = true;
        }

This gave me:

HTTP Error: CURL RETURNED FALSE (ErrorNo: 23, ErrorNoStr: Failed writing received data to disk/application, ) with status code 200

Note the http 200 - it looks like the CURL request is successfull, but CURL is returning false because of some disk writing issue?

PHP Version

PHP 8.3.7

Operating System

Windows 11 / WIndows Server 2016+

[HeavenCore]

I see a similar issue in composer github, they suggest removing CURLOPT_ENCODING, "" - PHP docoumentation says: "If an empty string, "", is set, a header containing all supported encoding types is sent." - that appears not to be the case in 8.3.7 - i'll test this now.

Edit 1: looks like CURL renamed it! https://curl.se/libcurl/c/CURLOPT_ACCEPT_ENCODING.html

Edit 2: OK, yes, removing curl_setopt($ch, CURLOPT_ENCODING, ""); does indeed fix the problem!

I think there are a few issues here:

1. PHP documenation here needs updating
2. curl_error() needs updating to give useful info instead of an empty string?
3. Why is curl_strerror() complaining about writing to disk if it's a header issue???
4. CURLOPT_ENCODING needs some TLC - either renaming to CURLOPT_ACCEPT_ENCODING or keeping as CURLOPT_ENCODING with some changes to ensure curl doesnt fallover if "" is passed as lots of people will be doing.

[shyim]

This has nothing to do with PHP. It's an upstream curl problem.
curl/curl#13209

[Girgias]

This is not a bug in PHP, thus closing.