Validate Google's reCaptcha code from php using cURL

Question

I'm trying to validate the reCaptcha code sent to my server using a cURL request. So far, this is the code:

function verifyReCaptcha($conn,$recaptchaCode){
    $curl = curl_init("https://www.google.com/recaptcha/api/siteverify");
    $data = ["secret"=>"XXXXXX","response"=>$recaptchaCode];
    curl_setopt_array($curl, array(
        CURLOPT_RETURNTRANSFER => 1,
        CURLOPT_HTTPHEADER => array('Accept: application/json'),
        CURLOPT_POST => 1,
        CURLOPT_POSTFIELDS => $data));
    $resp = curl_exec($curl);
    curl_close($curl);
    if ($resp == NULL){
        echo "Error: ".curl_errno($curl);
    } else {
        echo $resp;
    }
}

The response that I'm getting is null, and the error it gives is sometimes 0, sometimes blank. So I'm completely at a loss here. How should it be coded to work properly?

I'm following the documentation for reCaptcha here.

EDIT: I've already tried the solution posted here, but it does not work for me.

Answer 1

I managed to do it using file_get_contents, as I read in a related question. So I'll post my solution as an answer, for anyone who may be stranded like I was.

function verifyReCaptcha($recaptchaCode){
    $postdata = http_build_query(["secret"=>"XXXXXX","response"=>$recaptchaCode]);
    $opts = ['http' =>
        [
            'method'  => 'POST',
            'header'  => 'Content-type: application/x-www-form-urlencoded',
            'content' => $postdata
        ]
    ];
    $context  = stream_context_create($opts);
    $result = file_get_contents('https://www.google.com/recaptcha/api/siteverify', false, $context);
    $check = json_decode($result);
    return $check->success;
}

The solution is extracted almost verbatim from here.