includes/linkeddata/PageDataRequestHandler.php

   1 <?php
   2
   3 use MediaWiki\Http\HttpAcceptParser;
   4 use MediaWiki\Http\HttpAcceptNegotiator;
   5
   6 /**
   7  * Request handler implementing a data interface for mediawiki pages.
   8  *
   9  * @license GPL-2.0+
  10  * @author Daniel Kinzler
  11  * @author Amir Sarabadanai
  12  */
  13
  14 class PageDataRequestHandler {
  15
  16         /**
  17          * Checks whether the request is complete, i.e. whether it contains all information needed
  18          * to reply with page data.
  19          *
  20          * This does not check whether the request is valid and will actually produce a successful
  21          * response.
  22          *
  23          * @param string|null $title Page title
  24          * @param WebRequest $request
  25          *
  26          * @return bool
  27          * @throws HttpError
  28          */
  29         public function canHandleRequest( $title, WebRequest $request ) {
  30                 if ( $title === '' || $title === null ) {
  31                         if ( $request->getText( 'target', '' ) === '' ) {
  32                                 return false;
  33                         }
  34                 }
  35
  36                 return true;
  37         }
  38
  39         /**
  40          * Main method for handling requests.
  41          *
  42          * @param string $title Page title
  43          * @param WebRequest $request The request parameters. Known parameters are:
  44          *        - title: the page title
  45          *        - format: the format
  46          *        - oldid|revision: the revision ID
  47          * @param OutputPage $output
  48          *
  49          * @note: Instead of an output page, a WebResponse could be sufficient, but
  50          *        redirect logic is currently implemented in OutputPage.
  51          *
  52          * @throws HttpError
  53          */
  54         public function handleRequest( $title, WebRequest $request, OutputPage $output ) {
  55                 // No matter what: The response is always public
  56                 $output->getRequest()->response()->header( 'Access-Control-Allow-Origin: *' );
  57
  58                 $revision = 0;
  59
  60                 $title = $request->getText( 'target', $title );
  61                 $revision = $request->getInt( 'oldid', $revision );
  62                 $revision = $request->getInt( 'revision', $revision );
  63
  64                 if ( $title === null || $title === '' ) {
  65                         //TODO: different error message?
  66                         throw new HttpError( 400, wfMessage( 'pagedata-bad-title', $title ) );
  67                 }
  68
  69                 try {
  70                         $title = Title::newFromTextThrow( $title );
  71                 } catch ( MalformedTitleException $ex ) {
  72                         throw new HttpError( 400, wfMessage( 'pagedata-bad-title', $title ) );
  73                 }
  74
  75                 $this->httpContentNegotiation( $request, $output, $title, $revision );
  76         }
  77
  78         /**
  79          * Applies HTTP content negotiation.
  80          * If the negotiation is successful, this method will set the appropriate redirect
  81          * in the OutputPage object and return. Otherwise, an HttpError is thrown.
  82          *
  83          * @param WebRequest $request
  84          * @param OutputPage $output
  85          * @param Title $title
  86          * @param int $revision The desired revision
  87          *
  88          * @throws HttpError
  89          */
  90         public function httpContentNegotiation(
  91                 WebRequest $request,
  92                 OutputPage $output,
  93                 Title $title,
  94                 $revision = 0
  95         ) {
  96                 $contentHandler = ContentHandler::getForTitle( $title );
  97                 $mimeTypes = $contentHandler->getSupportedFormats();
  98
  99                 $headers = $request->getAllHeaders();
 100                 if ( isset( $headers['ACCEPT'] ) ) {
 101                         $parser = new HttpAcceptParser();
 102                         $accept = $parser->parseWeights( $headers['ACCEPT'] );
 103                 } else {
 104                         // anything goes
 105                         $accept = [
 106                                 '*' => 0.1 // just to make extra sure
 107                         ];
 108                         // prefer the default
 109                         $accept[$mimeTypes[0]] = 1;
 110                 }
 111
 112                 $negotiator = new HttpAcceptNegotiator( $mimeTypes );
 113                 $format = $negotiator->getBestSupportedKey( $accept, null );
 114
 115                 if ( $format === null ) {
 116                         $format = isset( $accept['text/html'] ) ? 'text/html' : null;
 117                 }
 118
 119                 if ( $format === null ) {
 120                         $msg = wfMessage( 'pagedata-not-acceptable', implode( ', ', $mimeTypes ) );
 121                         throw new HttpError( 406, $msg );
 122                 }
 123
 124                 $url = $this->getDocUrl( $title, $format, $revision );
 125                 $output->redirect( $url, 303 );
 126         }
 127
 128         /**
 129          * Returns a url representing the given title.
 130          *
 131          * @param Title $title
 132          * @param string|null $format The (normalized) format name, or ''
 133          * @param int $revision
 134          * @return string
 135          */
 136         private function getDocUrl( Title $title, $format = '', $revision = 0 ) {
 137                 $params = [];
 138
 139                 if ( $revision > 0 ) {
 140                         $params['oldid'] = $revision;
 141                 }
 142
 143                 if ( $format === 'text/html' ) {
 144                         return $title->getFullURL( $params );
 145                 }
 146
 147                 $params[ 'action' ] = 'raw';
 148
 149                 return $title->getFullURL( $params );
 150         }
 151
 152 }