Difference between revisions of "Cchost/developer/tutorial/Replacing the File Verifier"

The ccHost philosophy for file verifying is a whitelist - a list of file types to be accepted, all others rejected. At least one installation has chosen to implement a blacklist instead. The portable way to do this is to use ccHost's verify hook - basically a global variable.

The following code is a skeleton of how to hook the system. The actual blacklisting algorithm is left as an exercise for the reader. Put this code into a file <local_files>/lib/blacklist_validator.php:

   <?
 
   // the uploader looks for this variable:

   global $CC_UPLOAD_VALIDATOR;

   // set the global to our validator factory...

   $CC_UPLOAD_VALIDATOR = 'make_blacklist_validator';
 
   function make_blacklist_validator()
   {
       return new Blacklist_Validator(true); // set this to false if you don't want to 
                                             // delegate to the system's validator
   }

   /**
   * Blacklist_Validator 
   *
   * Replace (or override) the existing whitelist base verifier
   * with an alternate version
   *
   */
   class Blacklist_Validator 
   {
       var $old_validator;  // store a pointer to the system validator
       var $do_delegation;  // flag as to whether to delegate to the system.

       function Blacklist_Validator($do_delegation=true)
       {
           $this->do_delegation = $do_delegation;

           if( $this->do_delegation )
           {
              require_once('cchost_lib/ccextras/cc-pseudo-verify.inc');
              $this->old_validator = new CCPseudoVerifyAPI();
           }
       }

       function GetValidFileTypes(&$types)
       {
           if( $this->do_delegation )
           {
              $retval = $this->old_validator->GetValidFileTypes($types);
           }
           else
           {
              $retval = true;
           }

           $types[] = '*.*';
           return $retval;
       }

       function FileValidate(&$formatinfo)
       {
           if( $this->do_delegation )
           {
              $retval = $this->old_validator->FileValidate($formatinfo);
              if( $retval )
                 return true;
           }
           else
           {
               if( !is_array( $types ) )
                 $types = array();
               $retval = false;
           }

           $path = $formatinfo->GetFilePath();

           // things really break down if we don't have a
           // file extension so we just reject them out
           // of hand

           $got_ext = preg_match( '/\.([a-z0-9]+)$/', strtolower($path), $m );

           if( !$got_ext )
           {
               $formatinfo->SetErrors( _('Cannot determine file type'));
               return false;
           }

           /*********************************** 
            *   Edit the code below here...   *
            ***********************************/

           $retval = 1 ? true : false; // <<<---- your verification code goes here

           if( $retval )
           {
               $FI['tags']         = 'archive,' . $m[0];   // tags here will be added to 
               $FI['default-ext']  = $m[0];                // your default extension goes here
               $FI['media-type']   = 'archive';            // media type (e.g. video, audio, image, archive, etc.)
               $FI['mime_type']    = 'octect/stream';      // or whatever you think

               $formatinfo->SetData( $FI );
               $formatinfo->_errors = '';
           }

           return $retval;
       }

   }
   ?>