Verify google reCAPTCHA with PHP. Clean and universal function.

verify.php

<?php
/*
  Decided to put this function as a gist itself, taken from this great comment
  https://gist.github.com/jonathanstark/dfb30bdfb522318fc819#gistcomment-2733991
*/
function validate_rechapcha($response){
	// Verifying the user's response (https://developers.google.com/recaptcha/docs/verify)
	$verifyURL = 'https://www.google.com/recaptcha/api/siteverify';
	
	// Collect and build POST data
	$post_data = http_build_query(
		array(
			'secret' => 'YOUR_SITE_KEY',
			'response' => $response,
			'remoteip' => (isset($_SERVER["HTTP_CF_CONNECTING_IP"]) ? $_SERVER["HTTP_CF_CONNECTING_IP"] : $_SERVER['REMOTE_ADDR'])
		)
	);
	
	// Send data on the best possible way
	if(function_exists('curl_init') && function_exists('curl_setopt') && function_exists('curl_exec')) {
		// Use cURL to get data 10x faster than using file_get_contents or other methods
		$ch =  curl_init($verifyURL);
			curl_setopt($ch, CURLOPT_POST, 1);
			curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);
			curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
			curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
			curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
			curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5);
			curl_setopt($ch, CURLOPT_TIMEOUT, 5);
			curl_setopt($ch, CURLOPT_HTTPHEADER, array('Accept: application/json', 'Content-type: application/x-www-form-urlencoded'));
			$response = curl_exec($ch);
		curl_close($ch);
	} else {
		// If server not have active cURL module, use file_get_contents
		$opts = array('http' =>
			array(
				'method'  => 'POST',
				'header'  => 'Content-type: application/x-www-form-urlencoded',
				'content' => $post_data
			)
		);
		$context  = stream_context_create($opts);
		$response = file_get_contents($verifyURL, false, $context);
	}

	// Verify all reponses and avoid PHP errors
	if($response) {
		$result = json_decode($response);
		if ($result->success===true) {
			return true;
		} else {
			return $result;
		}
	}

	// Dead end
	return false; 
}