streams/mod/photo.php

<?php

require_once('include/security.php');
require_once('include/photo/photo_driver.php');

function photo_init(&$a) {

	$prvcachecontrol = false;

	switch(argc()) {
		case 4:
			$person = argv(3);
			$res    = argv(2);
			$type   = argv(1);
			break;
		case 2:
			$photo = argv(1);
			break;
		case 1:
		default:
			killme();
			// NOTREACHED
	}

	$observer_xchan = get_observer_hash();

	$default = get_default_profile_photo();

	if(isset($type)) {

		/**
		 * Profile photos - Access controls on default profile photos are not honoured since they need to be exchanged with remote sites.
		 * 
		 */

		if($type === 'profile') {
			switch($res) {

				case 'm':
					$resolution = 5;
					$default = get_default_profile_photo(80);
					break;
				case 's':
					$resolution = 6;
					$default = get_default_profile_photo(48);
					break;
				case 'l':
				default:
					$resolution = 4;
					break;
			}
		}

		$uid = $person;

		$r = q("SELECT * FROM photo WHERE scale = %d AND uid = %d AND photo_usage = %d LIMIT 1",
			intval($resolution),
			intval($uid),
			intval(PHOTO_PROFILE)
		);
		if(count($r)) {
			$data = dbunescbin($r[0]['data']);
			$mimetype = $r[0]['type'];
		}
		if(intval($r[0]['os_storage']))
			$data = file_get_contents($data);
		if(! isset($data)) {
			$data = file_get_contents($default);
			$mimetype = 'image/png';
		}
	}
	else {

		/**
		 * Other photos
		 */

	        /* Check for a cookie to indicate display pixel density, in order to detect high-resolution
		   displays. This procedure was derived from the "Retina Images" by Jeremey Worboys,
		   used in accordance with the Creative Commons Attribution 3.0 Unported License.
		   Project link: https://github.com/Retina-Images/Retina-Images
		   License link: http://creativecommons.org/licenses/by/3.0/
		*/
		$cookie_value = false;
		if (isset($_COOKIE['devicePixelRatio'])) {
		  $cookie_value = intval($_COOKIE['devicePixelRatio']);
		}
		else {
		  // Force revalidation of cache on next request
		  $cache_directive = 'no-cache';
		  $status = 'no cookie';
		}

		$resolution = 0;

		if(strpos($photo,'.') !== false)
			$photo = substr($photo,0,strpos($photo,'.'));
	
		if(substr($photo,-2,1) == '-') {
			$resolution = intval(substr($photo,-1,1));
			$photo = substr($photo,0,-2);
			// If viewing on a high-res screen, attempt to serve a higher resolution image:
			if ($resolution == 2 && ($cookie_value > 1))
			  {
			    $resolution = 1;
			  }
		}
		
		// If using resolution 1, make sure it exists before proceeding:
		if ($resolution == 1)
		  {
		    $r = q("SELECT uid FROM photo WHERE resource_id = '%s' AND scale = %d LIMIT 1",
			   dbesc($photo),
			   intval($resolution)
			   );
		    if (!($r))
		      $resolution = 2;
		  }

		$r = q("SELECT uid FROM photo WHERE resource_id = '%s' AND scale = %d LIMIT 1",
			dbesc($photo),
			intval($resolution)
		);
		if($r) {
			
			$allowed = (($r[0]['uid']) ? perm_is_allowed($r[0]['uid'],$observer_xchan,'view_storage') : true);

			$sql_extra = permissions_sql($r[0]['uid']);

			// Now we'll see if we can access the photo

			$r = q("SELECT * FROM photo WHERE resource_id = '%s' AND scale = %d $sql_extra LIMIT 1",
				dbesc($photo),
				intval($resolution)
			);

			if($r && $allowed) {
				$data = dbunescbin($r[0]['data']);
				$mimetype = $r[0]['type'];
				if(intval($r[0]['os_storage']))
					$data = file_get_contents($data);
			}
			else {

				// Does the picture exist? It may be a remote person with no credentials,
				// but who should otherwise be able to view it. Show a default image to let 
				// them know permissions was denied. It may be possible to view the image 
				// through an authenticated profile visit.
				// There won't be many completely unauthorised people seeing this because
				// they won't have the photo link, so there's a reasonable chance that the person
				// might be able to obtain permission to view it.

				$r = q("SELECT * FROM `photo` WHERE `resource_id` = '%s' AND `scale` = %d LIMIT 1",
					dbesc($photo),
					intval($resolution)
				);
 
				if($r) {
					logger('mod_photo: forbidden. ' . $a->query_string);
					$observer = $a->get_observer();
					logger('mod_photo: observer = ' . (($observer) ? $observer['xchan_addr'] : '(not authenticated)'));
					$data = file_get_contents('images/nosign.png');
					$mimetype = 'image/png';
					$prvcachecontrol = true;
				}
			}
		}
	}

	if(! isset($data)) {
		if(isset($resolution)) {
			switch($resolution) {

				case 4:
					$data = file_get_contents(get_default_profile_photo());
					$mimetype = 'image/png';
					break;
				case 5:
					$data = file_get_contents(get_default_profile_photo(80));
					$mimetype = 'image/png';
					break;
				case 6:
					$data = file_get_contents(get_default_profile_photo(48));
					$mimetype = 'image/png';
					break;
				default:
					killme();
					// NOTREACHED
					break;
			}
		}
	}

	if(isset($res) && intval($res) && $res < 500) {
		$ph = photo_factory($data, $mimetype);
		if($ph->is_valid()) {
			$ph->scaleImageSquare($res);
			$data = $ph->imageString();
			$mimetype = $ph->getType();
		}
	}

	// Writing in cachefile
	if (isset($cachefile) && $cachefile != '')
		file_put_contents($cachefile, $data);

	if(function_exists('header_remove')) {
		header_remove('Pragma');
		header_remove('pragma');
	}

	header("Content-type: " . $mimetype);

	if($prvcachecontrol) {

		// it is a private photo that they have no permission to view.
		// tell the browser not to cache it, in case they authenticate
		// and subsequently have permission to see it

		header("Cache-Control: no-store, no-cache, must-revalidate");

	}
	else {
		// The photo cache default is 1 day to provide a privacy trade-off,
		// as somebody reducing photo permissions on a photo that is already 
		// "in the wild" won't be able to stop the photo from being viewed
		// for this amount amount of time once it is in the browser cache.
		// The privacy expectations of your site members and their perception 
		// of privacy where it affects the entire project may be affected.
		// This has performance considerations but we highly recommend you 
		// leave it alone. 

		$cache = get_config('system','photo_cache_time');
		if(! $cache)
			$cache = (3600 * 24); // 1 day

	 	header("Expires: " . gmdate("D, d M Y H:i:s", time() + $cache) . " GMT");
		header("Cache-Control: max-age=" . $cache);

	}
	echo $data;
	killme();
	// NOTREACHED
}