Provides a local caching system for Flickr images to ensure they are viewable when clients have Flickr blocked.

Flickr Cacher

<?php

/*
Flickr Caching Script for WordPress
Description: Provides a local caching system for Flickr images to ensure they
are viewable when clients have Flickr blocked. 
Version: 1.0
Author: Matt Harris
Author URI: http://themattharris.com
License: MIT (http://www.opensource.org/licenses/mit-license.php)

  Copyright (c) 2009 Matt Harris

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
  
*/

/*
Usage
1. Place the file in your theme directory, e.g. wp-content/themes/mytheme/flickr.php
2. If necessary change the require path
3. On the page where you want flickr images put
    <?php $encoded = base64_encode( 'http://path/to/flickrimage.jpg'); ?>
    <img src="<?php echo get_bloginfo('template_directory') . '/flickr.php?hash=' . $encoded ?>">
4. To keep things healthy create a couple of cron jobs to:
    a. Clean out images which haven't been accessed for 5 weeks.
        http://yourdomain.com/wp-content/themes/mytheme/flickr.php?cleanup
*/

// if your wordpress content folder is not in the same location as wp-load you
// will need to alter this.
require(  dirname(
            dirname(
              dirname(
                dirname(__FILE__)   // your theme directory
              )                     // themes
            )                       // wp-content
          )                         // site root
          . '/wp-load.php' );

$path   = WP_CONTENT_DIR . '/uploads/flickr/';

function validImage( $url, &$head=FALSE ) {
  # Flickr returns a 200 OK even if the image doesn't exist.
  # Instead we look for the content-disposition header as it is only
  # included when an actual image is found.
  $head = wp_remote_head( $url );
  return isset( $head['headers']['content-disposition'] );
}

# retrieve the image from Flickr. Note we only do this if the url is on Flickr.
function getImage( $url, $filename ) {
  $pattern = "/https?:\/\/farm\d+.static.flickr.com\/.*/i";
  if ( preg_match( $pattern, $url ) > 0 ) {
    $handle = fopen( $filename, 'w');
    fwrite( $handle, wp_remote_fopen( $url ) );
    fclose( $handle );
  } else {
    print $url . " disallowed.";
    die();
  }
}

if ( isset( $_GET['refresh'] ) ) {
  $files = scandir( $path );
  foreach ($files as $file) {
    if ( is_file( $path . $file ) ) {
      $url = base64_decode( $file );
      
      if ( validImage( $url, $head ) )
      {
        # The last_modified date of the file is the datestamp set on Flickr of
        # when the file was created.
        # is the last_modified more recent than when we last checked the file?
        $last_mod = strtotime( $head['headers']['last-modified'] );
        $file_mod = filemtime( $path . $file );
        
        if ( $file_mod < $last_mod ) {
          getImage( $url, $path . $file );
        }
      }
    }
  }
}

if ( isset( $_GET['cleanup'] ) ) {
  $files = scandir( $path );
  foreach ($files as $file) {
    $expires = time() - ( 60 * 60 * 24 * 7 * 5 ); // 5 weeks ago
    if ( is_file( $path . $file ) and ( filemtime( $path . $file ) < $expires) ) {
      # delete the file
      @unlink( $path . $file );
    }
  }
}

if ( isset( $_GET['hash'] ) ) {
  # expects the url in base64_encoded format
  $hash   = strip_tags( stripslashes( $_GET['hash'] ) );
  $image  = $path . $hash;
  $url    = base64_decode( $hash );
  
  # we always do a stat on the image
  if ( validImage( $url, $head ) )
  {
    # check if we have an up-to-date copy of the image
    if ( file_exists($image) ) {
      # The last_modified date of the file is the datestamp set on Flickr of
      # when the file was created.
      # is the last_modified more recent than when we last checked the file?
      $last_mod = strtotime( $head['headers']['last-modified'] );
      $file_mod = filemtime( $path . $file );
    
      # if the file is out of date, remove it - it will be recached
      if ( $file_mod < $last_mod ) {
        @unlink( $path . $file );
      } else {
        # update the marker (note this only works if the user running the script
        # can write to the file
        @touch( $path . $file );
      }
    }
    
    if ( ! file_exists($image) ) {
      getImage( $url, $image );    
    }
    
    header("Content-Disposition: filename=\"$hash\"");
    header("Content-Length: " . filesize($image));
    header("Content-Type: $ContentType");
    readfile($image);
  }
}