includes/linkeddata/PageDataRequestHandler.php

   1 <?php
   2
   3 use Wikimedia\Http\HttpAcceptParser;
   4 use Wikimedia\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 $subPage
  24          * @param WebRequest $request
  25          *
  26          * @return bool
  27          * @throws HttpError
  28          */
  29         public function canHandleRequest( $subPage, WebRequest $request ) {
  30                 if ( $subPage === '' || $subPage === null ) {
  31                         if ( $request->getText( 'target', '' ) === '' ) {
  32                                 return false;
  33                         } else {
  34                                 return true;
  35                         }
  36                 }
  37
  38                 $parts = explode( '/', $subPage, 2 );
  39                 if ( $parts !== 2 ) {
  40                         $slot = $parts[0];
  41                         if ( $slot === 'main' or $slot === '' ) {
  42                                 return true;
  43                         }
  44                 }
  45
  46                 return false;
  47         }
  48
  49         /**
  50          * Main method for handling requests.
  51          *
  52          * @param string $subPage
  53          * @param WebRequest $request The request parameters. Known parameters are:
  54          *        - title: the page title
  55          *        - format: the format
  56          *        - oldid|revision: the revision ID
  57          * @param OutputPage $output
  58          *
  59          * @note: Instead of an output page, a WebResponse could be sufficient, but
  60          *        redirect logic is currently implemented in OutputPage.
  61          *
  62          * @throws HttpError
  63          */
  64         public function handleRequest( $subPage, WebRequest $request, OutputPage $output ) {
  65                 // No matter what: The response is always public
  66                 $output->getRequest()->response()->header( 'Access-Control-Allow-Origin: *' );
  67
  68                 if ( !$this->canHandleRequest( $subPage, $request ) ) {
  69                         throw new HttpError( 400, wfMessage( 'pagedata-bad-title', $subPage ) );
  70                 }
  71
  72                 $revision = 0;
  73
  74                 $parts = explode( '/', $subPage, 2 );
  75                 if ( $subPage !== '' ) {
  76                         $title = $parts[1];
  77                 } else {
  78                         $title = $request->getText( 'target', '' );
  79                 }
  80
  81                 $revision = $request->getInt( 'oldid', $revision );
  82                 $revision = $request->getInt( 'revision', $revision );
  83
  84                 if ( $title === null || $title === '' ) {
  85                         //TODO: different error message?
  86                         throw new HttpError( 400, wfMessage( 'pagedata-bad-title', $title ) );
  87                 }
  88
  89                 try {
  90                         $title = Title::newFromTextThrow( $title );
  91                 } catch ( MalformedTitleException $ex ) {
  92                         throw new HttpError( 400, wfMessage( 'pagedata-bad-title', $title ) );
  93                 }
  94
  95                 $this->httpContentNegotiation( $request, $output, $title, $revision );
  96         }
  97
  98         /**
  99          * Applies HTTP content negotiation.
 100          * If the negotiation is successful, this method will set the appropriate redirect
 101          * in the OutputPage object and return. Otherwise, an HttpError is thrown.
 102          *
 103          * @param WebRequest $request
 104          * @param OutputPage $output
 105          * @param Title $title
 106          * @param int $revision The desired revision
 107          *
 108          * @throws HttpError
 109          */
 110         public function httpContentNegotiation(
 111                 WebRequest $request,
 112                 OutputPage $output,
 113                 Title $title,
 114                 $revision = 0
 115         ) {
 116                 $contentHandler = ContentHandler::getForTitle( $title );
 117                 $mimeTypes = $contentHandler->getSupportedFormats();
 118
 119                 $headers = $request->getAllHeaders();
 120                 if ( isset( $headers['ACCEPT'] ) ) {
 121                         $parser = new HttpAcceptParser();
 122                         $accept = $parser->parseWeights( $headers['ACCEPT'] );
 123                 } else {
 124                         // anything goes
 125                         $accept = [
 126                                 '*' => 0.1 // just to make extra sure
 127                         ];
 128                         // prefer the default
 129                         $accept[$mimeTypes[0]] = 1;
 130                 }
 131
 132                 $negotiator = new HttpAcceptNegotiator( $mimeTypes );
 133                 $format = $negotiator->getBestSupportedKey( $accept, null );
 134
 135                 if ( $format === null ) {
 136                         $format = isset( $accept['text/html'] ) ? 'text/html' : null;
 137                 }
 138
 139                 if ( $format === null ) {
 140                         $msg = wfMessage( 'pagedata-not-acceptable', implode( ', ', $mimeTypes ) );
 141                         throw new HttpError( 406, $msg );
 142                 }
 143
 144                 $url = $this->getDocUrl( $title, $format, $revision );
 145                 $output->redirect( $url, 303 );
 146         }
 147
 148         /**
 149          * Returns a url representing the given title.
 150          *
 151          * @param Title $title
 152          * @param string|null $format The (normalized) format name, or ''
 153          * @param int $revision
 154          * @return string
 155          */
 156         private function getDocUrl( Title $title, $format = '', $revision = 0 ) {
 157                 $params = [];
 158
 159                 if ( $revision > 0 ) {
 160                         $params['oldid'] = $revision;
 161                 }
 162
 163                 if ( $format === 'text/html' ) {
 164                         return $title->getFullURL( $params );
 165                 }
 166
 167                 $params[ 'action' ] = 'raw';
 168
 169                 return $title->getFullURL( $params );
 170         }
 171
 172 }