Privacy Image Cache

pull/50/head
Tobias Hößl 2012-04-22 13:19:45 +00:00
parent 24acdb2e22
commit 33ccf200cb
2 changed files with 179 additions and 0 deletions

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Once activated, this addon acs as a proxy between the user and external image resources.
If external images are to be shown, like avatars or embedded images, the server retrieves the image and the local link is sent to the user.
By using this proxy, the server hosting the original image cannot retrieve personal information of the user like the IP address, User Agent or Cookies.
However, the remote server will be able to track the IP address of the server hosting the friendica installation.

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<?php
/**
* Name: Privacy Image Cache
* Version: 0.1
* Author: Tobias Hößl <https://github.com/CatoTH/>
*/
define("PRIVACY_IMAGE_CACHE_DEFAULT_TIME", 86400); // 1 Day
require_once('include/security.php');
function privacy_image_cache_install() {
register_hook('bbcode', 'addon/privacy_image_cache/privacy_image_cache.php', 'privacy_image_cache_bbcode_hook');
register_hook('display_item', 'addon/privacy_image_cache/privacy_image_cache.php', 'privacy_image_cache_display_item_hook');
register_hook('ping_xmlize', 'addon/privacy_image_cache/privacy_image_cache.php', 'privacy_image_cache_ping_xmlize_hook');
register_hook('cron', 'addon/privacy_image_cache/privacy_image_cache.php', 'privacy_image_cache_cron');
}
function privacy_image_cache_uninstall() {
unregister_hook('bbcode', 'addon/privacy_image_cache/privacy_image_cache.php', 'privacy_image_cache_bbcode_hook');
unregister_hook('display_item', 'addon/privacy_image_cache/privacy_image_cache.php', 'privacy_image_cache_display_item_hook');
unregister_hook('ping_xmlize', 'addon/privacy_image_cache/privacy_image_cache.php', 'privacy_image_cache_ping_xmlize_hook');
unregister_hook('cron', 'addon/privacy_image_cache/privacy_image_cache.php', 'privacy_image_cache_cron');
}
function privacy_image_cache_module() {}
function privacy_image_cache_init() {
$urlhash = 'pic:' . sha1($_REQUEST['url']);
$r = q("SELECT * FROM `photo` WHERE `resource-id` = '%s' LIMIT 1", $urlhash );
if (count($r)) {
$img_str = $r[0]['data'];
}
else {
require_once("Photo.php");
$img_str = fetch_url($_REQUEST['url'],true);
$img = new Photo($img_str);
if($img->is_valid()) {
$img->store(0, 0, $urlhash, $_REQUEST['url'], '', 100);
$img_str = $img->imageString();
}
}
header("Content-type: image/jpeg");
header("Expires: " . gmdate("D, d M Y H:i:s", time() + (3600*24)) . " GMT");
header("Cache-Control: max-age=" . (3600*24));
echo $img_str;
killme();
}
/**
* @param $url string
* @return boolean
*/
function privacy_image_cache_is_local_image($url) {
if ($url[0] == '/') return true;
$baseurl = get_app()->get_baseurl();
return (substr($url, 0, strlen($baseurl)) == $baseurl);
}
/**
* @param array $matches
* @return string
*/
function privacy_image_cache_img_cb($matches) {
if (privacy_image_cache_is_local_image($matches[2])) return $matches[2];
return $matches[1] . "/privacy_image_cache/?url=" . escape_tags(addslashes($matches[2])) . $matches[3];
}
/**
* @param App $a
* @param string $o
*/
function privacy_image_cache_bbcode_hook(&$a, &$o) {
$o = preg_replace_callback("/(<img [^>]*src *= *[\"'])([^\"']+)([\"'][^>]*>)/siU", "privacy_image_cache_img_cb", $o);
}
/**
* @param App $a
* @param string $o
*/
function privacy_image_cache_display_item_hook(&$a, &$o) {
if (isset($o["output"])) {
if (isset($o["output"]["thumb"]) && !privacy_image_cache_is_local_image($o["output"]["thumb"]))
$o["output"]["thumb"] = "/privacy_image_cache/?url=" . escape_tags(addslashes($o["output"]["thumb"]));
if (isset($o["output"]["author-avatar"]) && !privacy_image_cache_is_local_image($o["output"]["author-avatar"]))
$o["output"]["author-avatar"] = "/privacy_image_cache/?url=" . escape_tags(addslashes($o["output"]["author-avatar"]));
}
}
/**
* @param App $a
* @param string $o
*/
function privacy_image_cache_ping_xmlize_hook(&$a, &$o) {
if ($o["photo"] != "" && !privacy_image_cache_is_local_image($o["photo"]))
$o["photo"] = "/privacy_image_cache/?url=" . escape_tags(addslashes($o["photo"]));
}
/**
* @param App $a
* @param null|object $b
*/
function privacy_image_cache_cron(&$a, &$b) {
$cachetime = get_config('privacy_image_cache','cache_time');
if (!$cachetime) $cachetime = PRIVACY_IMAGE_CACHE_DEFAULT_TIME;
$last = get_config('pi_cache','last_delete');
$time = time();
if ($time < ($last + 3600)) return;
logger("Purging old Cache of the Privacy Image Cache", LOGGER_DEBUG);
q('DELETE FROM `photo` WHERE `uid` = 0 AND `resource-id` LIKE "pic:%%" AND `created` < NOW() - INTERVAL %d SECOND', $cachetime);
set_config('pi_cache', 'last_delete', $time);
}
/**
* @param App $a
* @param null|object $o
*/
function privacy_image_cache_plugin_admin(&$a, &$o){
$o = '<input type="hidden" name="form_security_token" value="' . get_form_security_token("picsave") . '">';
$cachetime = get_config('privacy_image_cache','cache_time');
if (!$cachetime) $cachetime = PRIVACY_IMAGE_CACHE_DEFAULT_TIME;
$cachetime_h = Ceil($cachetime / 3600);
$o .= '<label for="pic_cachetime">' . t('Lifetime of the cache (in hours)') . '</label>
<input id="pic_cachetime" name="cachetime" type="text" value="' . escape_tags($cachetime_h) . '"><br style="clear: both;">';
$o .= '<input type="submit" name="save" value="' . t('Save') . '">';
$o .= '<h4>' . t('Cache Statistics') . '</h4>';
$num = q('SELECT COUNT(*) num, SUM(LENGTH(data)) size FROM `photo` WHERE `uid`=0 AND `contact-id`=0 AND `resource-id` LIKE "pic:%%"');
$o .= '<label for="statictics_num">' . t('Number of items') . '</label><input style="color: gray;" id="statistics_num" disabled value="' . escape_tags($num[0]['num']) . '"><br style="clear: both;">';
$size = Ceil($num[0]['size'] / (1024 * 1024));
$o .= '<label for="statictics_size">' . t('Size of the cache') . '</label><input style="color: gray;" id="statistics_size" disabled value="' . $size . ' MB"><br style="clear: both;">';
$o .= '<input type="submit" name="delete_all" value="' . t('Delete the whole cache') . '">';
}
/**
* @param App $a
* @param null|object $o
*/
function privacy_image_cache_plugin_admin_post(&$a, &$o){
check_form_security_token_redirectOnErr('/admin/plugins/privacy_image_cache', 'picsave');
if (isset($_REQUEST['save'])) {
$cachetime_h = IntVal($_REQUEST['cachetime']);
if ($cachetime_h < 1) $cachetime_h = 1;
set_config('privacy_image_cache','cache_time', $cachetime_h * 3600);
}
if (isset($_REQUEST['delete_all'])) {
q('DELETE FROM `photo` WHERE `uid` = 0 AND `resource-id` LIKE "pic:%%"');
}
}