curl-localhost-test.php

<?php
$curl_localhost_test_success                = FALSE;
$curl_localhost_test_url                    = 'http://'.$_SERVER['HTTP_HOST'];
$curl_localhost_test_url_return_string_frag = 'html';

if(is_resource($_curl_test_resource = curl_init()))
{
    curl_setopt_array(
        $_curl_test_resource, array(
            CURLOPT_CONNECTTIMEOUT => 5, CURLOPT_TIMEOUT => 5,
            CURLOPT_URL            => $curl_localhost_test_url, CURLOPT_RETURNTRANSFER => TRUE,
            CURLOPT_FAILONERROR    => TRUE, CURLOPT_FORBID_REUSE => TRUE, CURLOPT_SSL_VERIFYPEER => TRUE
        )
    );
    if(stripos((string)curl_exec($_curl_test_resource), $curl_localhost_test_url_return_string_frag) !== FALSE)
        $curl_localhost_test_success = TRUE;
    curl_close($_curl_test_resource);
}

if(!$curl_localhost_test_success) {
    echo "cURL failed to connect to ". $curl_localhost_test_url;
} else {
    echo "cURL successfully connected to ". $curl_localhost_test_url;
}