library\XenForo\Helper\Facebook.php

Facebook.php

public static function getAccessToken($url, $code)
	{
		$options = XenForo_Application::get('options');

		if (!$options->facebookAppId)
		{
			return false;
		}

		try
		{
			$client = XenForo_Helper_Http::getClient('https://graph.facebook.com/v2.4/oauth/access_token');
			$client->setParameterPost(array(
				'client_id' => $options->facebookAppId,
				'redirect_uri' => $url,
				'client_secret' => $options->facebookAppSecret,
				'code' => $code
			));

			$response = $client->request('POST');

			$body = $response->getBody();
			if (preg_match('#^[{\[]#', $body))
			{
				$parts = json_decode($body, true);
			}
			else
			{
				$parts = XenForo_Application::parseQueryString($body);
			}

			return $parts;
		}
		catch (Zend_Http_Client_Exception $e)
		{
			return false;
		}
	}