includes/TemplateParser.php

   1 <?php
   2 use MediaWiki\MediaWikiServices;
   3
   4 /**
   5  * Handles compiling Mustache templates into PHP rendering functions
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; if not, write to the Free Software Foundation, Inc.,
  19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  20  * http://www.gnu.org/copyleft/gpl.html
  21  *
  22  * @file
  23  * @since 1.25
  24  */
  25 class TemplateParser {
  26         /**
  27          * @var string The path to the Mustache templates
  28          */
  29         protected $templateDir;
  30
  31         /**
  32          * @var callable[] Array of cached rendering functions
  33          */
  34         protected $renderers;
  35
  36         /**
  37          * @var bool Always compile template files
  38          */
  39         protected $forceRecompile = false;
  40
  41         /**
  42          * @param string $templateDir
  43          * @param bool $forceRecompile
  44          */
  45         public function __construct( $templateDir = null, $forceRecompile = false ) {
  46                 $this->templateDir = $templateDir ?: __DIR__ . '/templates';
  47                 $this->forceRecompile = $forceRecompile;
  48         }
  49
  50         /**
  51          * Constructs the location of the the source Mustache template
  52          * @param string $templateName The name of the template
  53          * @return string
  54          * @throws UnexpectedValueException If $templateName attempts upwards directory traversal
  55          */
  56         protected function getTemplateFilename( $templateName ) {
  57                 // Prevent upwards directory traversal using same methods as Title::secureAndSplit
  58                 if (
  59                         strpos( $templateName, '.' ) !== false &&
  60                         (
  61                                 $templateName === '.' || $templateName === '..' ||
  62                                 strpos( $templateName, './' ) === 0 ||
  63                                 strpos( $templateName, '../' ) === 0 ||
  64                                 strpos( $templateName, '/./' ) !== false ||
  65                                 strpos( $templateName, '/../' ) !== false ||
  66                                 substr( $templateName, -2 ) === '/.' ||
  67                                 substr( $templateName, -3 ) === '/..'
  68                         )
  69                 ) {
  70                         throw new UnexpectedValueException( "Malformed \$templateName: $templateName" );
  71                 }
  72
  73                 return "{$this->templateDir}/{$templateName}.mustache";
  74         }
  75
  76         /**
  77          * Returns a given template function if found, otherwise throws an exception.
  78          * @param string $templateName The name of the template (without file suffix)
  79          * @return callable
  80          * @throws RuntimeException
  81          */
  82         protected function getTemplate( $templateName ) {
  83                 // If a renderer has already been defined for this template, reuse it
  84                 if ( isset( $this->renderers[$templateName] ) &&
  85                         is_callable( $this->renderers[$templateName] )
  86                 ) {
  87                         return $this->renderers[$templateName];
  88                 }
  89
  90                 $filename = $this->getTemplateFilename( $templateName );
  91
  92                 if ( !file_exists( $filename ) ) {
  93                         throw new RuntimeException( "Could not locate template: {$filename}" );
  94                 }
  95
  96                 // Read the template file
  97                 $fileContents = file_get_contents( $filename );
  98
  99                 // Generate a quick hash for cache invalidation
 100                 $fastHash = md5( $fileContents );
 101
 102                 // Fetch a secret key for building a keyed hash of the PHP code
 103                 $config = MediaWikiServices::getInstance()->getMainConfig();
 104                 $secretKey = $config->get( 'SecretKey' );
 105
 106                 if ( $secretKey ) {
 107                         // See if the compiled PHP code is stored in cache.
 108                         $cache = ObjectCache::getLocalServerInstance( CACHE_ANYTHING );
 109                         $key = $cache->makeKey( 'template', $templateName, $fastHash );
 110                         $code = $this->forceRecompile ? null : $cache->get( $key );
 111
 112                         if ( !$code ) {
 113                                 $code = $this->compileForEval( $fileContents, $filename );
 114
 115                                 // Prefix the cached code with a keyed hash (64 hex chars) as an integrity check
 116                                 $cache->set( $key, hash_hmac( 'sha256', $code, $secretKey ) . $code );
 117                         } else {
 118                                 // Verify the integrity of the cached PHP code
 119                                 $keyedHash = substr( $code, 0, 64 );
 120                                 $code = substr( $code, 64 );
 121                                 if ( $keyedHash !== hash_hmac( 'sha256', $code, $secretKey ) ) {
 122                                         // Generate a notice if integrity check fails
 123                                         trigger_error( "Template failed integrity check: {$filename}" );
 124                                 }
 125                         }
 126                 // If there is no secret key available, don't use cache
 127                 } else {
 128                         $code = $this->compileForEval( $fileContents, $filename );
 129                 }
 130
 131                 $renderer = eval( $code );
 132                 if ( !is_callable( $renderer ) ) {
 133                         throw new RuntimeException( "Requested template, {$templateName}, is not callable" );
 134                 }
 135                 $this->renderers[$templateName] = $renderer;
 136                 return $renderer;
 137         }
 138
 139         /**
 140          * Wrapper for compile() function that verifies successful compilation and strips
 141          * out the '<?php' part so that the code is ready for eval()
 142          * @param string $fileContents Mustache code
 143          * @param string $filename Name of the template
 144          * @return string PHP code (without '<?php')
 145          * @throws RuntimeException
 146          */
 147         protected function compileForEval( $fileContents, $filename ) {
 148                 // Compile the template into PHP code
 149                 $code = $this->compile( $fileContents );
 150
 151                 if ( !$code ) {
 152                         throw new RuntimeException( "Could not compile template: {$filename}" );
 153                 }
 154
 155                 // Strip the "<?php" added by lightncandy so that it can be eval()ed
 156                 if ( substr( $code, 0, 5 ) === '<?php' ) {
 157                         $code = substr( $code, 5 );
 158                 }
 159
 160                 return $code;
 161         }
 162
 163         /**
 164          * Compile the Mustache code into PHP code using LightnCandy
 165          * @param string $code Mustache code
 166          * @return string PHP code (with '<?php')
 167          * @throws RuntimeException
 168          */
 169         protected function compile( $code ) {
 170                 if ( !class_exists( 'LightnCandy' ) ) {
 171                         throw new RuntimeException( 'LightnCandy class not defined' );
 172                 }
 173                 return LightnCandy::compile(
 174                         $code,
 175                         [
 176                                 // Do not add more flags here without discussion.
 177                                 // If you do add more flags, be sure to update unit tests as well.
 178                                 'flags' => LightnCandy::FLAG_ERROR_EXCEPTION,
 179                                 'basedir' => $this->templateDir,
 180                                 'fileext' => '.mustache',
 181                         ]
 182                 );
 183         }
 184
 185         /**
 186          * Returns HTML for a given template by calling the template function with the given args
 187          *
 188          * @code
 189          *     echo $templateParser->processTemplate(
 190          *         'ExampleTemplate',
 191          *         [
 192          *             'username' => $user->getName(),
 193          *             'message' => 'Hello!'
 194          *         ]
 195          *     );
 196          * @endcode
 197          * @param string $templateName The name of the template
 198          * @param mixed $args
 199          * @param array $scopes
 200          * @return string
 201          */
 202         public function processTemplate( $templateName, $args, array $scopes = [] ) {
 203                 $template = $this->getTemplate( $templateName );
 204                 return call_user_func( $template, $args, $scopes );
 205         }
 206 }