<?php
/**
* CodeIgniter
*
* An open source application development framework for PHP
*
* This content is released under the MIT License (MIT)
*
* Copyright (c) 2014-2019 British Columbia Institute of Technology
* Copyright (c) 2019-2020 CodeIgniter Foundation
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission 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.
*
* @package CodeIgniter
* @author CodeIgniter Dev Team
* @copyright 2019-2020 CodeIgniter Foundation
* @license https://opensource.org/licenses/MIT MIT License
* @link https://codeigniter.com
* @since Version 4.0.0
* @filesource
*/
namespace CodeIgniter\HTTP;
use CodeIgniter\HTTP\Exceptions\HTTPException;
/**
* Class Negotiate
*
* Provides methods to negotiate with the HTTP headers to determine the best
* type match between what the application supports and what the requesting
* getServer wants.
*
* @see http://tools.ietf.org/html/rfc7231#section-5.3
* @package CodeIgniter\HTTP
*/
class Negotiate
{
/**
* Request
*
* @var \CodeIgniter\HTTP\RequestInterface|\CodeIgniter\HTTP\IncomingRequest
*/
protected $request;
//--------------------------------------------------------------------
/**
* Constructor
*
* @param \CodeIgniter\HTTP\RequestInterface $request
*/
public function __construct(RequestInterface $request = null)
{
if (! is_null($request))
{
$this->request = $request;
}
}
//--------------------------------------------------------------------
/**
* Stores the request instance to grab the headers from.
*
* @param RequestInterface $request
*
* @return $this
*/
public function setRequest(RequestInterface $request)
{
$this->request = $request;
return $this;
}
//--------------------------------------------------------------------
/**
* Determines the best content-type to use based on the $supported
* types the application says it supports, and the types requested
* by the client.
*
* If no match is found, the first, highest-ranking client requested
* type is returned.
*
* @param array $supported
* @param boolean $strictMatch If TRUE, will return an empty string when no match found.
* If FALSE, will return the first supported element.
*
* @return string
*/
public function media(array $supported, bool $strictMatch = false): string
{
return $this->getBestMatch($supported, $this->request->getHeaderLine('accept'), true, $strictMatch);
}
//--------------------------------------------------------------------
/**
* Determines the best charset to use based on the $supported
* types the application says it supports, and the types requested
* by the client.
*
* If no match is found, the first, highest-ranking client requested
* type is returned.
*
* @param array $supported
*
* @return string
*/
public function charset(array $supported): string
{
$match = $this->getBestMatch($supported, $this->request->getHeaderLine('accept-charset'), false, true);
// If no charset is shown as a match, ignore the directive
// as allowed by the RFC, and tell it a default value.
if (empty($match))
{
return 'utf-8';
}
return $match;
}
//--------------------------------------------------------------------
/**
* Determines the best encoding type to use based on the $supported
* types the application says it supports, and the types requested
* by the client.
*
* If no match is found, the first, highest-ranking client requested
* type is returned.
*
* @param array $supported
*
* @return string
*/
public function encoding(array $supported = []): string
{
array_push($supported, 'identity');
return $this->getBestMatch($supported, $this->request->getHeaderLine('accept-encoding'));
}
//--------------------------------------------------------------------
/**
* Determines the best language to use based on the $supported
* types the application says it supports, and the types requested
* by the client.
*
* If no match is found, the first, highest-ranking client requested
* type is returned.
*
* @param array $supported
*
* @return string
*/
public function language(array $supported): string
{
return $this->getBestMatch($supported, $this->request->getHeaderLine('accept-language'));
}
//--------------------------------------------------------------------
//--------------------------------------------------------------------
// Utility Methods
//--------------------------------------------------------------------
/**
* Does the grunt work of comparing any of the app-supported values
* against a given Accept* header string.
*
* Portions of this code base on Aura.Accept library.
*
* @param array $supported App-supported values
* @param string $header header string
* @param boolean $enforceTypes If TRUE, will compare media types and sub-types.
* @param boolean $strictMatch If TRUE, will return empty string on no match.
* If FALSE, will return the first supported element.
*
* @return string Best match
*/
protected function getBestMatch(array $supported, string $header = null, bool $enforceTypes = false, bool $strictMatch = false): string
{
if (empty($supported))
{
throw HTTPException::forEmptySupportedNegotiations();
}
if (empty($header))
{
return $strictMatch ? '' : $supported[0];
}
$acceptable = $this->parseHeader($header);
foreach ($acceptable as $accept)
{
// if acceptable quality is zero, skip it.
if ($accept['q'] === 0.0)
{
continue;
}
// if acceptable value is "anything", return the first available
if ($accept['value'] === '*' || $accept['value'] === '*/*')
{
return $supported[0];
}
// If an acceptable value is supported, return it
foreach ($supported as $available)
{
if ($this->match($accept, $available, $enforceTypes))
{
return $available;
}
}
}
// No matches? Return the first supported element.
return $strictMatch ? '' : $supported[0];
}
//--------------------------------------------------------------------
/**
* Parses an Accept* header into it's multiple values.
*
* This is based on code from Aura.Accept library.
*
* @param string $header
*
* @return array
*/
public function parseHeader(string $header): array
{
$results = [];
$acceptable = explode(',', $header);
foreach ($acceptable as $value)
{
$pairs = explode(';', $value);
$value = $pairs[0];
unset($pairs[0]);
$parameters = [];
foreach ($pairs as $pair)
{
$param = [];
preg_match(
'/^(?P<name>.+?)=(?P<quoted>"|\')?(?P<value>.*?)(?:\k<quoted>)?$/', $pair, $param
);
$parameters[trim($param['name'])] = trim($param['value']);
}
$quality = 1.0;
if (array_key_exists('q', $parameters))
{
$quality = $parameters['q'];
unset($parameters['q']);
}
$results[] = [
'value' => trim($value),
'q' => (float) $quality,
'params' => $parameters,
];
}
// Sort to get the highest results first
usort($results, function ($a, $b) {
if ($a['q'] === $b['q'])
{
$a_ast = substr_count($a['value'], '*');
$b_ast = substr_count($b['value'], '*');
// '*/*' has lower precedence than 'text/*',
// and 'text/*' has lower priority than 'text/plain'
//
// This seems backwards, but needs to be that way
// due to the way PHP7 handles ordering or array
// elements created by reference.
if ($a_ast > $b_ast)
{
return 1;
}
// If the counts are the same, but one element
// has more params than another, it has higher precedence.
//
// This seems backwards, but needs to be that way
// due to the way PHP7 handles ordering or array
// elements created by reference.
if ($a_ast === $b_ast)
{
return count($b['params']) - count($a['params']);
}
return 0;
}
// Still here? Higher q values have precedence.
return ($a['q'] > $b['q']) ? -1 : 1;
});
return $results;
}
//--------------------------------------------------------------------
/**
* Match-maker
*
* @param array $acceptable
* @param string $supported
* @param boolean $enforceTypes
* @return boolean
*/
protected function match(array $acceptable, string $supported, bool $enforceTypes = false): bool
{
$supported = $this->parseHeader($supported);
if (is_array($supported) && count($supported) === 1)
{
$supported = $supported[0];
}
// Is it an exact match?
if ($acceptable['value'] === $supported['value'])
{
return $this->matchParameters($acceptable, $supported);
}
// Do we need to compare types/sub-types? Only used
// by negotiateMedia().
if ($enforceTypes)
{
return $this->matchTypes($acceptable, $supported);
}
return false;
}
//--------------------------------------------------------------------
/**
* Checks two Accept values with matching 'values' to see if their
* 'params' are the same.
*
* @param array $acceptable
* @param array $supported
*
* @return boolean
*/
protected function matchParameters(array $acceptable, array $supported): bool
{
if (count($acceptable['params']) !== count($supported['params']))
{
return false;
}
foreach ($supported['params'] as $label => $value)
{
if (! isset($acceptable['params'][$label]) ||
$acceptable['params'][$label] !== $value)
{
return false;
}
}
return true;
}
//--------------------------------------------------------------------
/**
* Compares the types/subtypes of an acceptable Media type and
* the supported string.
*
* @param array $acceptable
* @param array $supported
*
* @return boolean
*/
public function matchTypes(array $acceptable, array $supported): bool
{
list($aType, $aSubType) = explode('/', $acceptable['value']);
list($sType, $sSubType) = explode('/', $supported['value']);
// If the types don't match, we're done.
if ($aType !== $sType)
{
return false;
}
// If there's an asterisk, we're cool
if ($aSubType === '*')
{
return true;
}
// Otherwise, subtypes must match also.
return $aSubType === $sSubType;
}
//--------------------------------------------------------------------
}
Lonnie Ezell