torrent_extra_info.api.php

<?php

/**
 * @brief Function to display torrent extra information.
 */

class torrent
{
    // Private class members
    private $torrent;
    private $info;
    
    // Public error message, $error is set if load() returns false
    public $error;
    
    // Load torrent file data
    // $data - raw torrent file contents
    public function load( &$data )
    {
        $this->torrent = BEncode::decode( $data );

        if ( $this->torrent->get_type() == 'error' )
        {
            $this->error = $this->torrent->get_plain();
            return false;
        }
        else if ( $this->torrent->get_type() != 'dictionary' )
        {
            $this->error = 'The file was not a valid torrent file.';
            return false;
        }
        
        $this->info = $this->torrent->get_value('info');
        if ( !$this->info )
        {
            $this->error = 'Could not find info dictionary.';
            return false;
        }
        
        return true;
    }
    
    // Get comment
    // return - string
    public function getComment() {
        return $this->torrent->get_value('comment') ? $this->torrent->get_value('comment')->get_plain() : null;
    }
    
    // Get creatuion date
    // return - php date
    public function getCreationDate() {
        return  $this->torrent->get_value('creation date') ? $this->torrent->get_value('creation date')->get_plain() : null;
    }
    
    // Get created by
    // return - string
    public function getCreatedBy() {
        return $this->torrent->get_value('created by') ? $this->torrent->get_value('created by')->get_plain() : null;
    }
    
    // Get name
    // return - filename (single file torrent)
    //          directory (multi-file torrent)
    // see also - getFiles()
    public function getName() {
        return $this->info->get_value('name')->get_plain();
    }
    
    // Get piece length
    // return - int
    public function getPieceLength() {
        return $this->info->get_value('piece length')->get_plain();
    }
    
    // Get pieces
    // return - raw binary of peice hashes
    public function getPieces() {
        return $this->info->get_value('pieces')->get_plain();
    }
    
    // Get private flag
    // return - -1 public, implicit
    //           0 public, explicit
    //           1 private
    public function getPrivate() {
        if ( $this->info->get_value('private') )
        {
            return $this->info->get_value('private')->get_plain();
        }
        return -1;
    }
    
    // Get a list of files
    // return - array of Torrent_File
    public function getFiles() {
        // Load files
        $filelist = array();
        $length = $this->info->get_value('length');
        
        if ( $length )
        {
            $file = new Torrent_File();
            $file->name = $this->info->get_value('name')->get_plain();
            $file->length =  $this->info->get_value('length')->get_plain();
            array_push( $filelist, $file );
        }
        else if ( $this->info->get_value('files') )
        {
            $files = $this->info->get_value('files')->get_plain();
            while ( list( $key, $value ) = each( $files ) )
            {
                $file = new Torrent_File();

                $path = $value->get_value('path')->get_plain();
                while ( list( $key, $value2 ) = each( $path ) )
                {
                    $file->name .= "/" . $value2->get_plain();
                }
                $file->name = ltrim( $file->name, '/' );
                $file->length =  $value->get_value('length')->get_plain();

                array_push( $filelist, $file );
            }
        }
        
        return $filelist;
    }
    
    // Get a list of trackers
    // return - array of strings
    public function getTrackers() {
        // Load tracker list
        $trackerlist = array();
        
        if ( $this->torrent->get_value('announce-list') )
        {
            $trackers = $this->torrent->get_value('announce-list')->get_plain();
            while ( list( $key, $value ) = each( $trackers ) )
            {
                if ( is_array( $value->get_plain() ) ) {
                    while ( list( $key, $value2 ) = each( $value ) )
                    {
                        while ( list( $key, $value3 ) = each( $value2 ) )
                        {
                            array_push( $trackerlist, $value3->get_plain() );
                        }
                    }
                } else {
                    array_push( $trackerlist, $value->get_plain() );
                }
            }
        }
        else if ( $this->torrent->get_value('announce') )
        {
            array_push( $trackerlist, $this->torrent->get_value('announce')->get_plain() );
        }
        
        return $trackerlist;
    }
      
    // Helper function to make adding a tracker easier
    // $tracker_url - string
    public function addTracker( $tracker_url )
    {
        $trackers = $this->getTrackers();
        $trackers[] = $tracker_url;
        $this->setTrackers( $trackers );
    }
    
    // Replace the current trackers with the supplied list
    // $trackerlist - array of strings
    public function setTrackers( $trackerlist )
    {
        if ( count( $trackerlist ) >= 1 )
        {
            $this->torrent->remove('announce-list');
            $string = new BEncode_String( $trackerlist[0] );
            $this->torrent->set( 'announce', $string );
        }
            
        if ( count( $trackerlist ) > 1 )
        {
            $list = new BEncode_List();
            

            while ( list( $key, $value ) = each( $trackerlist ) )
            {
                $list2 = new BEncode_List();
                $string = new BEncode_String( $value );
                $list2->add( $string );
                $list->add( $list2 );
            }
            
            $this->torrent->set( 'announce-list', $list );
        }
    }
    
    // Update the list of files
    // $filelist - array of Torrent_File
    public function setFiles( $filelist )
    {
        // Load files
        $length = $this->info->get_value('length');

        if ( $length )
        {
            $filelist[0] = str_replace( '\\', '/', $filelist[0] );
            $string = new BEncode_String( $filelist[0] );
            $this->info->set( 'name', $string );
        }
        else if ( $this->info->get_value('files') )
        {
            $files = $this->info->get_value('files')->get_plain();
            for ( $i = 0; $i < count( $files ); ++$i )
            {
                $file_parts = split( '/', $filelist[$i] );
                $path = new BEncode_List();
                foreach ( $file_parts as $part )
                {
                    $string = new BEncode_String( $part );
                    $path->add( $string );
                }
                $files[$i]->set( 'path', $path );
            }
        }
    }
    
    // Set the comment field
    // $value - string
    public function setComment( $value )
    {
        $type = 'comment';
        $key = $this->torrent->get_value( $type );
        if ( $value == '' ) {
            $this->torrent->remove( $type );
        } elseif ( $key ) {
            $key->set( $value );
        } else {
            $string = new BEncode_String( $value );
            $this->torrent->set( $type, $string );
        }
    }
    
    // Set the created by field
    // $value - string
    public function setCreatedBy( $value )
    {
        $type = 'created by';
        $key = $this->torrent->get_value( $type );
        if ( $value == '' ) {
            $this->torrent->remove( $type );
        } elseif ( $key ) {
            $key->set( $value );
        } else {
            $string = new BEncode_String( $value );
            $this->torrent->set( $type, $string );
        }
    }
    
    
    // Set the creation date
    // $value - php date
    public function setCreationDate( $value )
    {
        $type = 'creation date';
        $key = $this->torrent->get_value( $type );
        if ( $value == '' ) {
            $this->torrent->remove( $type );
        } elseif ( $key ) {
            $key->set( $value );
        } else {
            $int = new BEncode_Int( $value );
            $this->torrent->set( $type, $int );
        }
    }
    
    // Change the private flag
    // $value - -1 public, implicit
    //           0 public, explicit
    //           1 private
    public function setPrivate( $value )
    {
        if ( $value == -1 ) {
            $this->info->remove( 'private' );
        } else {
            $int = new BEncode_Int( $value );
            $this->info->set( 'private', $int );
        }
    }
    
    // Bencode the torrent
    public function bencode()
    {
        return $this->torrent->encode();
    }
    
    // Return the torrent's hash
    public function getHash()
    {
        return strtoupper( sha1( $this->info->encode() ) );
    }
}

// Simple class to encapsulate filename and length
class Torrent_File
{
    public $name;
    public $length;
}


class BEncode
{
    public static function &decode( &$raw, &$offset=0 )
    {   
        if ( $offset >= strlen( $raw ) )
        {
            return new BEncode_Error( "Decoder exceeded max length." ) ;
        }
        
        $char = $raw[$offset];
        switch ( $char )
        {
            case 'i':
                $int = new BEncode_Int();
                $int->decode( $raw, $offset );
                return $int;
                
            case 'd':
                $dict = new BEncode_Dictionary();

                if ( $check = $dict->decode( $raw, $offset ) )
                {
                    return $check;
                }
                return $dict;
                
            case 'l':
                $list = new BEncode_List();
                $list->decode( $raw, $offset );
                return $list;
                
            case 'e':
                return new BEncode_End();
                
            case '0':
            case is_numeric( $char ):
                $str = new BEncode_String();
                $str->decode( $raw, $offset );
                return $str;

            default:
                return new BEncode_Error( "Decoder encountered unknown char '$char' at offset $offset." );
        }
    }
}

class BEncode_End
{
    public function get_type()
    {
        return 'end';
    }
}

class BEncode_Error
{
    private $error;
    
    public function BEncode_Error( $error )
    {
        $this->error = $error;
    }
    
    public function get_plain()
    {
        return $this->error;
    }
    
    public function get_type()
    {
        return 'error';
    }
}

class BEncode_Int
{
    private $value;
    
    public function BEncode_Int( $value = null )
    {
        $this->value = $value;
    }

    public function decode( &$raw, &$offset )
    {
            $end = strpos( $raw, 'e', $offset );
            $this->value = substr( $raw, ++$offset, $end - $offset );
            $offset += ( $end - $offset );
    }

    public function get_plain()
    {
        return $this->value;
    }

    public function get_type()
    {
        return 'int';
    }
    
    public function encode()
    {
        return "i{$this->value}e";
    }
    
    public function set( $value )
    {
        $this->value = $value;
    }
}

class BEncode_Dictionary
{
    public $value = array();
    
    public function decode( &$raw, &$offset )
    {
            $dictionary = array();

            while ( true )
            {
                $name = BEncode::decode( $raw, ++$offset );

                if ( $name->get_type() == 'end' )
                {
                    break;
                }
                else if ( $name->get_type() == 'error' )
                {
                    return $name;
                }
                else if ( $name->get_type() != 'string' )
                {
                    return new BEncode_Error( "Key name in dictionary was not a string." );
                }

                $value = BEncode::decode( $raw, ++$offset );

                if ( $value->get_type() == 'error' )
                {
                    return $value;
                }

                $dictionary[$name->get_plain()] = $value;
            }

            $this->value = $dictionary;
    }
    
    public function get_value( $key )
    {
        if ( isset( $this->value[$key] ) )
        {
            return $this->value[$key];
        }
        else
        {
            return null;
        }
    }
    
    public function encode()
    {
        $this->sort();

        $encoded = 'd';
        while ( list( $key, $value ) = each( $this->value ) )
        {
            $bstr = new BEncode_String();
            $bstr->set( $key );
            $encoded .= $bstr->encode();
            $encoded .= $value->encode();
        }
        $encoded .= 'e';
        return $encoded;
    }

    public function get_type()
    {
        return 'dictionary';
    }
    
    public function remove( $key )
    {
        unset( $this->value[$key] );
    }
    
    public function set( $key, $value )
    {
        $this->value[$key] = $value;
    }
    
    private function sort()
    {
        ksort( $this->value );
    }
    
    public function count()
    {
        return count( $this->value );
    }
}

class BEncode_List
{
    private $value = array();
    
    public function add( $bval )
    {
        array_push( $this->value, $bval );
    }

    public function decode( &$raw, &$offset )
    {
            $list = array();

            while ( true )
            {
                $value = BEncode::decode( $raw, ++$offset );

                if ( $value->get_type() == 'end' )
                {
                    break;
                }
                else if ( $value->get_type() == 'error' )
                {
                    return $value;
                }
                array_push( $list, $value );
            }

            $this->value = $list;
    }
    
    public function encode()
    {
        $encoded = 'l';
        
        for ( $i = 0; $i < count( $this->value ); ++$i )
        {
            $encoded .= $this->value[$i]->encode();
        }
        $encoded .= 'e';
        return $encoded;
    }
    
    public function get_plain()
    {
        return $this->value;
    }

    public function get_type()
    {
        return 'list';
    }
}

class BEncode_String
{
    private $value;
    
    public function BEncode_String( $value = null )
    {
        $this->value = $value;
    }
    
    public function decode( &$raw, &$offset )
    {
            $end = strpos( $raw, ':', $offset );
            $len = substr( $raw, $offset, $end - $offset );
            $offset += ($len + ($end - $offset));
            $end++;
            $this->value = substr( $raw, $end, $len );
    }
    
    public function get_plain()
    {
        return $this->value;
    }
    
    public function get_type()
    {
        return 'string';
    }
    
    public function encode()
    {
        $len = strlen( $this->value );
        return  "$len:{$this->value}";
    }
    
    public function set( $value )
    {
        $this->value = $value;
    }
}