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