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<?php
/**
* Copyright 2017 Facebook, Inc.
*
* You are hereby granted a non-exclusive, worldwide, royalty-free license to
* use, copy, modify, and distribute this software in source code or binary
* form for use in connection with the web services and APIs provided by
* Facebook.
*
* As with any software that integrates with the Facebook platform, your use
* of this software is subject to the Facebook Developer Principles and
* Policies [http://developers.facebook.com/policy/]. This copyright notice
* shall be included in all copies or substantial portions of the software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
*/
namespace Facebook\Url;
/**
* Class FacebookUrlDetectionHandler
*
* @package Facebook
*/
class FacebookUrlDetectionHandler implements UrlDetectionInterface
{
/**
* @inheritdoc
*/
public function getCurrentUrl()
{
return $this->getHttpScheme() . '://' . $this->getHostName() . $this->getServerVar('REQUEST_URI');
}
/**
* Get the currently active URL scheme.
*
* @return string
*/
protected function getHttpScheme()
{
return $this->isBehindSsl() ? 'https' : 'http';
}
/**
* Tries to detect if the server is running behind an SSL.
*
* @return boolean
*/
protected function isBehindSsl()
{
// Check for proxy first
$protocol = $this->getHeader('X_FORWARDED_PROTO');
if ($protocol) {
return $this->protocolWithActiveSsl($protocol);
}
$protocol = $this->getServerVar('HTTPS');
if ($protocol) {
return $this->protocolWithActiveSsl($protocol);
}
return (string)$this->getServerVar('SERVER_PORT') === '443';
}
/**
* Detects an active SSL protocol value.
*
* @param string $protocol
*
* @return boolean
*/
protected function protocolWithActiveSsl($protocol)
{
$protocol = strtolower((string)$protocol);
return in_array($protocol, ['on', '1', 'https', 'ssl'], true);
}
/**
* Tries to detect the host name of the server.
*
* Some elements adapted from
*
* @see https://github.com/symfony/HttpFoundation/blob/master/Request.php
*
* @return string
*/
protected function getHostName()
{
// Check for proxy first
$header = $this->getHeader('X_FORWARDED_HOST');
if ($header && $this->isValidForwardedHost($header)) {
$elements = explode(',', $header);
$host = $elements[count($elements) - 1];
} elseif (!$host = $this->getHeader('HOST')) {
if (!$host = $this->getServerVar('SERVER_NAME')) {
$host = $this->getServerVar('SERVER_ADDR');
}
}
// trim and remove port number from host
// host is lowercase as per RFC 952/2181
$host = strtolower(preg_replace('/:\d+$/', '', trim($host)));
// Port number
$scheme = $this->getHttpScheme();
$port = $this->getCurrentPort();
$appendPort = ':' . $port;
// Don't append port number if a normal port.
if (($scheme == 'http' && $port == '80') || ($scheme == 'https' && $port == '443')) {
$appendPort = '';
}
return $host . $appendPort;
}
protected function getCurrentPort()
{
// Check for proxy first
$port = $this->getHeader('X_FORWARDED_PORT');
if ($port) {
return (string)$port;
}
$protocol = (string)$this->getHeader('X_FORWARDED_PROTO');
if ($protocol === 'https') {
return '443';
}
return (string)$this->getServerVar('SERVER_PORT');
}
/**
* Returns the a value from the $_SERVER super global.
*
* @param string $key
*
* @return string
*/
protected function getServerVar($key)
{
return isset($_SERVER[$key]) ? $_SERVER[$key] : '';
}
/**
* Gets a value from the HTTP request headers.
*
* @param string $key
*
* @return string
*/
protected function getHeader($key)
{
return $this->getServerVar('HTTP_' . $key);
}
/**
* Checks if the value in X_FORWARDED_HOST is a valid hostname
* Could prevent unintended redirections
*
* @param string $header
*
* @return boolean
*/
protected function isValidForwardedHost($header)
{
$elements = explode(',', $header);
$host = $elements[count($elements) - 1];
return preg_match("/^([a-z\d](-*[a-z\d])*)(\.([a-z\d](-*[a-z\d])*))*$/i", $host) //valid chars check
&& 0 < strlen($host) && strlen($host) < 254 //overall length check
&& preg_match("/^[^\.]{1,63}(\.[^\.]{1,63})*$/", $host); //length of each label
}
}
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