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<?php
/**
* The content negotiator performs "text/html" or "application/xhtml+xml" switching.
* It does this through the public static function ContentNegotiator::process().
* By default, ContentNegotiator will comply to the Accept headers the clients
* sends along with the HTTP request, which is most likely "application/xhtml+xml"
* (see "Order of selection" below).
*
* Order of selection between html or xhtml is as follows:
* - if PHP has already sent the HTTP headers, default to "html" (we can't send HTTP Content-Type headers any longer)
* - if a GET variable ?forceFormat is set, it takes precedence (for testing purposes)
* - if the user agent is detected as W3C Validator we always deliver "xhtml"
* - if an HTTP Accept header is sent from the client, we respect its order (this is the most common case)
* - if none of the above matches, fallback is "html"
*
* ContentNegotiator doesn't enable you to send content as a true XML document
* through the "text/xml" or "application/xhtml+xml" Content-Type.
* Please see http://webkit.org/blog/68/understanding-html-xml-and-xhtml/ for further information.
*
* @package framework
* @subpackage control
*
* @todo Check for correct XHTML doctype in xhtml()
* @todo Allow for other HTML4 doctypes (e.g. Transitional) in html()
* @todo Make content replacement and doctype setting two separately configurable behaviours - some
* devs might know what they're doing and don't want contentnegotiator messing with their HTML4 doctypes,
* but still find it useful to have self-closing tags removed.
*/
class ContentNegotiator extends Object {
/**
* @config
* @var string
*/
private static $content_type = '';
/**
* @config
* @var string
*/
private static $encoding = 'utf-8';
/**
* @config
* @var boolean
*/
private static $enabled = false;
/**
* @config
* @var string
*/
private static $default_format = 'html';
/**
* Set the character set encoding for this page. By default it's utf-8, but you could change it to, say,
* windows-1252, to improve interoperability with extended characters being imported from windows excel.
*
* @deprecated 3.2 Use the "ContentNegotiator.encoding" config setting instead
*/
public static function set_encoding($encoding) {
Deprecation::notice('3.2', 'Use the "ContentNegotiator.encoding" config setting instead');
Config::inst()->update('ContentNegotiator', 'encoding', $encoding);
}
/**
* Return the character encoding set bhy ContentNegotiator::set_encoding(). It's recommended that all classes
* that need to specify the character set make use of this function.
*
* @deprecated 3.2 Use the "ContentNegotiator.encoding" config setting instead
*/
public static function get_encoding() {
Deprecation::notice('3.2', 'Use the "ContentNegotiator.encoding" config setting instead');
return Config::inst()->get('ContentNegotiator', 'encoding');
}
/**
* Enable content negotiation for all templates, not just those with the xml header.
*
* @deprecated 3.2 Use the "ContentNegotiator.enabled" config setting instead
*/
public static function enable() {
Deprecation::notice('3.2', 'Use the "ContentNegotiator.enabled" config setting instead');
Config::inst()->update('ContentNegotiator', 'enabled', true);
}
/**
* Disable content negotiation for all templates, not just those with the xml header.
*
* @deprecated 3.2 Use the "ContentNegotiator.enabled" config setting instead
*/
public static function disable() {
Deprecation::notice('3.2', 'Use the "ContentNegotiator.enabled" config setting instead');
Config::inst()->update('ContentNegotiator', 'enabled', false);
}
/**
* Returns true if negotation is enabled for the given response.
* By default, negotiation is only enabled for pages that have the xml header.
*/
public static function enabled_for($response) {
$contentType = $response->getHeader("Content-Type");
// Disable content negotation for other content types
if($contentType && substr($contentType, 0,9) != 'text/html'
&& substr($contentType, 0,21) != 'application/xhtml+xml') {
return false;
}
if(Config::inst()->get('ContentNegotiator', 'enabled')) return true;
else return (substr($response->getBody(),0,5) == '<' . '?xml');
}
public static function process(SS_HTTPResponse $response) {
if(!self::enabled_for($response)) return;
$mimes = array(
"xhtml" => "application/xhtml+xml",
"html" => "text/html",
);
$q = array();
if(headers_sent()) {
$chosenFormat = Config::inst()->get('ContentNegotiator', 'default_format');
} else if(isset($_GET['forceFormat'])) {
$chosenFormat = $_GET['forceFormat'];
} else {
// The W3C validator doesn't send an HTTP_ACCEPT header, but it can support xhtml. We put this special
// case in here so that designers don't get worried that their templates are HTML4.
if(isset($_SERVER['HTTP_USER_AGENT']) && substr($_SERVER['HTTP_USER_AGENT'], 0, 14) == 'W3C_Validator/') {
$chosenFormat = "xhtml";
} else {
foreach($mimes as $format => $mime) {
$regExp = '/' . str_replace(array('+','/'),array('\+','\/'), $mime) . '(;q=(\d+\.\d+))?/i';
if (isset($_SERVER['HTTP_ACCEPT']) && preg_match($regExp, $_SERVER['HTTP_ACCEPT'], $matches)) {
$preference = isset($matches[2]) ? $matches[2] : 1;
if(!isset($q[$preference])) $q[$preference] = $format;
}
}
if($q) {
// Get the preferred format
krsort($q);
$chosenFormat = reset($q);
} else {
$chosenFormat = Config::inst()->get('ContentNegotiator', 'default_format');
}
}
}
$negotiator = new ContentNegotiator();
$negotiator->$chosenFormat( $response );
}
/**
* Check user defined content type and use it, if it's empty use the strict application/xhtml+xml.
* Replaces a few common tags and entities with their XHTML representations (<br>, <img>, &nbsp;
* <input>, checked, selected).
*
* @param $response SS_HTTPResponse
* @return string
* @todo Search for more xhtml replacement
*/
public function xhtml(SS_HTTPResponse $response) {
$content = $response->getBody();
$encoding = Config::inst()->get('ContentNegotiator', 'encoding');
$contentType = Config::inst()->get('ContentNegotiator', 'content_type');
if (empty($contentType)) {
$response->addHeader("Content-Type", "application/xhtml+xml; charset=" . $encoding);
} else {
$response->addHeader("Content-Type", $contentType . "; charset=" . $encoding);
}
$response->addHeader("Vary" , "Accept");
// Fix base tag
$content = preg_replace('/<base href="([^"]*)"><!--\[if[[^\]*]\] \/><!\[endif\]-->/',
'<base href="$1" />', $content);
$content = str_replace('&nbsp;','&#160;', $content);
$content = str_replace('<br>','<br />', $content);
$content = str_replace('<hr>','<hr />', $content);
$content = preg_replace('#(<img[^>]*[^/>])>#i', '\\1/>', $content);
$content = preg_replace('#(<input[^>]*[^/>])>#i', '\\1/>', $content);
$content = preg_replace('#(<param[^>]*[^/>])>#i', '\\1/>', $content);
$content = preg_replace("#(\<option[^>]*[\s]+selected)(?!\s*\=)#si", "$1=\"selected\"$2", $content);
$content = preg_replace("#(\<input[^>]*[\s]+checked)(?!\s*\=)#si", "$1=\"checked\"$2", $content);
$response->setBody($content);
}
/*
* Check user defined content type and use it, if it's empty use the text/html.
* If find a XML header replaces it and existing doctypes with HTML4.01 Strict.
* Replaces self-closing tags like <img /> with unclosed solitary tags like <img>.
* Replaces all occurrences of "application/xhtml+xml" with "text/html" in the template.
* Removes "xmlns" attributes and any <?xml> Pragmas.
*/
public function html(SS_HTTPResponse $response) {
$encoding = Config::inst()->get('ContentNegotiator', 'encoding');
$contentType = Config::inst()->get('ContentNegotiator', 'content_type');
if (empty($contentType)) {
$response->addHeader("Content-Type", "text/html; charset=" . $encoding);
} else {
$response->addHeader("Content-Type", $contentType . "; charset=" . $encoding);
}
$response->addHeader("Vary", "Accept");
$content = $response->getBody();
$hasXMLHeader = (substr($content,0,5) == '<' . '?xml' );
// Fix base tag
$content = preg_replace('/<base href="([^"]*)" \/>/',
'<base href="$1"><!--[if lte IE 6]></base><![endif]-->', $content);
$content = preg_replace("#<\\?xml[^>]+\\?>\n?#", '', $content);
$content = str_replace(array('/>','xml:lang','application/xhtml+xml'),array('>','lang','text/html'), $content);
// Only replace the doctype in templates with the xml header
if($hasXMLHeader) {
$content = preg_replace('/<!DOCTYPE[^>]+>/',
'<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">',
$content);
}
$content = preg_replace('/<html xmlns="[^"]+"/','<html ', $content);
$response->setBody($content);
}
}
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