FancyCaptcha.class.php

   1 <?php
   2
   3 class FancyCaptcha extends SimpleCaptcha {
   4         /**
   5          * Check if the submitted form matches the captcha session data provided
   6          * by the plugin when the form was generated.
   7          *
   8          * @param WebRequest $request
   9          * @param array $info
  10          * @return bool
  11          */
  12         function keyMatch( $request, $info ) {
  13                 global $wgCaptchaSecret;
  14
  15                 $answer = $request->getVal( 'wpCaptchaWord' );
  16                 $digest = $wgCaptchaSecret . $info['salt'] . $answer . $wgCaptchaSecret . $info['salt'];
  17                 $answerHash = substr( md5( $digest ), 0, 16 );
  18
  19                 if( $answerHash == $info['hash'] ) {
  20                         wfDebug( "FancyCaptcha: answer hash matches expected {$info['hash']}\n" );
  21                         return true;
  22                 } else {
  23                         wfDebug( "FancyCaptcha: answer hashes to $answerHash, expected {$info['hash']}\n" );
  24                         return false;
  25                 }
  26         }
  27
  28         /**
  29          * Insert the captcha prompt into the edit form.
  30          */
  31         function getForm() {
  32                 $info = $this->pickImage();
  33                 if( !$info ) {
  34                         die( "out of captcha images; this shouldn't happen" );
  35                 }
  36
  37                 // Generate a random key for use of this captcha image in this session.
  38                 // This is needed so multiple edits in separate tabs or windows can
  39                 // go through without extra pain.
  40                 $index = $this->storeCaptcha( $info );
  41
  42                 wfDebug( "Captcha id $index using hash ${info['hash']}, salt ${info['salt']}.\n" );
  43
  44                 $title = Title::makeTitle( NS_SPECIAL, 'Captcha/image' );
  45
  46                 return "<p>" .
  47                         wfElement( 'img', array(
  48                                 'src'    => $title->getLocalUrl( 'wpCaptchaId=' . urlencode( $index ) ),
  49                                 'width'  => $info['width'],
  50                                 'height' => $info['height'],
  51                                 'alt'    => '' ) ) .
  52                         "</p>\n" .
  53                         wfElement( 'input', array(
  54                                 'type'  => 'hidden',
  55                                 'name'  => 'wpCaptchaId',
  56                                 'id'    => 'wpCaptchaId',
  57                                 'value' => $index ) ) .
  58                         "<p>" .
  59                         wfElement( 'input', array(
  60                                 'name' => 'wpCaptchaWord',
  61                                 'id'   => 'wpCaptchaWord',
  62                                 'tabindex' => 1 ) ) . // tab in before the edit textarea
  63                         "</p>\n";
  64         }
  65
  66         /**
  67          * Select a previously generated captcha image from the queue.
  68          * @fixme subject to race conditions if lots of files vanish
  69          * @return mixed tuple of (salt key, text hash) or false if no image to find
  70          */
  71         function pickImage() {
  72                 global $wgCaptchaDirectory, $wgCaptchaDirectoryLevels;
  73                 return $this->pickImageDir(
  74                         $wgCaptchaDirectory,
  75                         $wgCaptchaDirectoryLevels );
  76         }
  77
  78         function pickImageDir( $directory, $levels ) {
  79                 if( $levels ) {
  80                         $dirs = array();
  81
  82                         // Check which subdirs are actually present...
  83                         $dir = opendir( $directory );
  84                         while( false !== ($entry = readdir( $dir ) ) ) {
  85                                 if( ctype_xdigit( $entry ) && strlen( $entry ) == 1 ) {
  86                                         $dirs[] = $entry;
  87                                 }
  88                         }
  89                         closedir( $dir );
  90
  91                         $place = mt_rand( 0, count( $dirs ) - 1 );
  92                         // In case all dirs are not filled,
  93                         // cycle through next digits...
  94                         for( $j = 0; $j < count( $dirs ); $j++ ) {
  95                                 $char = $dirs[($place + $j) % count( $dirs )];
  96                                 $return = $this->pickImageDir( "$directory/$char", $levels - 1 );
  97                                 if( $return ) {
  98                                         return $return;
  99                                 }
 100                         }
 101                         // Didn't find any images in this directory... empty?
 102                         return false;
 103                 } else {
 104                         return $this->pickImageFromDir( $directory );
 105                 }
 106         }
 107
 108         function pickImageFromDir( $directory ) {
 109                 if( !is_dir( $directory ) ) {
 110                         return false;
 111                 }
 112                 $n = mt_rand( 0, $this->countFiles( $directory ) - 1 );
 113                 $dir = opendir( $directory );
 114
 115                 $count = 0;
 116
 117                 $entry = readdir( $dir );
 118                 $pick = false;
 119                 while( false !== $entry ) {
 120                         $entry = readdir( $dir );
 121                         if( preg_match( '/^image_([0-9a-f]+)_([0-9a-f]+)\\.png$/', $entry, $matches ) ) {
 122                                 $size = getimagesize( "$directory/$entry" );
 123                                 $pick = array(
 124                                         'salt' => $matches[1],
 125                                         'hash' => $matches[2],
 126                                         'width' => $size[0],
 127                                         'height' => $size[1],
 128                                         'viewed' => false,
 129                                 );
 130                                 if( $count++ == $n ) {
 131                                         break;
 132                                 }
 133                         }
 134                 }
 135                 closedir( $dir );
 136                 return $pick;
 137         }
 138
 139         /**
 140          * Count the number of files in a directory.
 141          * @return int
 142          */
 143         function countFiles( $dirname ) {
 144                 $dir = opendir( $dirname );
 145                 $count = 0;
 146                 while( false !== ($entry = readdir( $dir ) ) ) {
 147                         if( $entry != '.' && $entry != '..' ) {
 148                                 $count++;
 149                         }
 150                 }
 151                 closedir( $dir );
 152                 return $count;
 153         }
 154
 155         function showImage() {
 156                 global $wgOut, $wgRequest;
 157
 158                 $wgOut->disable();
 159
 160                 $info = $this->retrieveCaptcha();
 161                 if( $info ) {
 162                         if( $info['viewed'] ) {
 163                                 wfHttpError( 403, 'Access Forbidden', "Can't view captcha image a second time." );
 164                                 return false;
 165                         }
 166
 167                         $info['viewed'] = wfTimestamp();
 168                         $this->storeCaptcha( $info );
 169
 170                         $salt = $info['salt'];
 171                         $hash = $info['hash'];
 172                         $file = $this->imagePath( $salt, $hash );
 173
 174                         if( file_exists( $file ) ) {
 175                                 global $IP;
 176                                 require_once "$IP/includes/StreamFile.php";
 177                                 wfStreamFile( $file );
 178                                 return true;
 179                         }
 180                 }
 181                 wfHttpError( 500, 'Internal Error', 'Requested bogus captcha image' );
 182                 return false;
 183         }
 184
 185         function imagePath( $salt, $hash ) {
 186                 global $wgCaptchaDirectory, $wgCaptchaDirectoryLevels;
 187                 $file = $wgCaptchaDirectory;
 188                 $file .= DIRECTORY_SEPARATOR;
 189                 for( $i = 0; $i < $wgCaptchaDirectoryLevels; $i++ ) {
 190                         $file .= $hash{$i};
 191                         $file .= DIRECTORY_SEPARATOR;
 192                 }
 193                 $file .= "image_{$salt}_{$hash}.png";
 194                 return $file;
 195         }
 196
 197         /**
 198          * Show a message asking the user to enter a captcha on edit
 199          * The result will be treated as wiki text
 200          *
 201          * @param $action Action being performed
 202          * @return string
 203          */
 204         function getMessage( $action ) {
 205                 $name = 'fancycaptcha-' . $action;
 206                 $text = wfMsg( $name );
 207                 # Obtain a more tailored message, if possible, otherwise, fall back to
 208                 # the default for edits
 209                 return wfEmptyMsg( $name, $text ) ? wfMsg( 'fancycaptcha-edit' ) : $text;
 210         }
 211
 212 }