fetch_rss( string $url ): MagpieRSS|false

412function fetch_rss ($url) {413	// initialize constants414	init();415 416	if ( !isset($url) ) {417		// error("fetch_rss called without a url");418		return false;419	}420 421	// if cache is disabled422	if ( !MAGPIE_CACHE_ON ) {423		// fetch file, and parse it424		$resp = _fetch_remote_file( $url );425		if ( is_success( $resp->status ) ) {426			return _response_to_rss( $resp );427		}428		else {429			// error("Failed to fetch $url and cache is off");430			return false;431		}432	}433	// else cache is ON434	else {435		// Flow436		// 1. check cache437		// 2. if there is a hit, make sure it's fresh438		// 3. if cached obj fails freshness check, fetch remote439		// 4. if remote fails, return stale object, or error440 441		$cache = new RSSCache( MAGPIE_CACHE_DIR, MAGPIE_CACHE_AGE );442 443		if (MAGPIE_DEBUG and $cache->ERROR) {444			debug($cache->ERROR, E_USER_WARNING);445		}446 447		$cache_status 	 = 0;		// response of check_cache448		$request_headers = array(); // HTTP headers to send with fetch449		$rss 			 = 0;		// parsed RSS object450		$errormsg		 = 0;		// errors, if any451 452		if (!$cache->ERROR) {453			// return cache HIT, MISS, or STALE454			$cache_status = $cache->check_cache( $url );455		}456 457		// if object cached, and cache is fresh, return cached obj458		if ( $cache_status == 'HIT' ) {459			$rss = $cache->get( $url );460			if ( isset($rss) and $rss ) {461				$rss->from_cache = 1;462				if ( MAGPIE_DEBUG > 1) {463				debug("MagpieRSS: Cache HIT", E_USER_NOTICE);464			}465				return $rss;466			}467		}468 469		// else attempt a conditional get470 471		// set up headers472		if ( $cache_status == 'STALE' ) {473			$rss = $cache->get( $url );474			if ( isset($rss->etag) and $rss->last_modified ) {475				$request_headers['If-None-Match'] = $rss->etag;476				$request_headers['If-Last-Modified'] = $rss->last_modified;477			}478		}479 480		$resp = _fetch_remote_file( $url, $request_headers );481 482		if (isset($resp) and $resp) {483			if ($resp->status == '304' ) {484				// we have the most current copy485				if ( MAGPIE_DEBUG > 1) {486					debug("Got 304 for $url");487				}488				// reset cache on 304 (at minutillo insistent prodding)489				$cache->set($url, $rss);490				return $rss;491			}