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[contents] Add server side caching for all requests (If-Modified-Since) #889

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merged 1 commit into from
Nov 19, 2018
Merged

[contents] Add server side caching for all requests (If-Modified-Since) #889

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61 changes: 52 additions & 9 deletions lib/contents.php
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,21 @@
/**
* Gets contents from the Internet.
*
* **Content caching** (disabled in debug mode)
*
* A copy of the received content is stored in a local cache folder `server/` at
* {@see PATH_CACHE}. The `If-Modified-Since` header is added to the request, if
* the provided URL has been cached before.
*
* When the server responds with `304 Not Modified`, the cached data is returned.
* This will improve response times and reduce bandwidth for servers that support
* the `If-Modified-Since` header.
*
* Cached files are forcefully removed after 24 hours.
*
* @link https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Modified-Since
* If-Modified-Since
*
* @param string $url The URL.
* @param array $header (optional) A list of cURL header.
* For more information follow the links below.
Expand All @@ -29,6 +44,14 @@
function getContents($url, $header = array(), $opts = array()){
Debug::log('Reading contents from "' . $url . '"');

// Initialize cache
$cache = Cache::create('FileCache');
$cache->setPath(PATH_CACHE . 'server/');
$cache->purgeCache(86400); // 24 hours (forced)

$params = [$url];
$cache->setParameters($params);

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
Expand Down Expand Up @@ -64,9 +87,22 @@ function getContents($url, $header = array(), $opts = array()){
// We always want the response header as part of the data!
curl_setopt($ch, CURLOPT_HEADER, true);

// Build "If-Modified-Since" header
if(!Debug::isEnabled() && $time = $cache->getTime()) { // Skip if cache file doesn't exist
Debug::log('Adding If-Modified-Since');
curl_setopt($ch, CURLOPT_TIMEVALUE, $time);
curl_setopt($ch, CURLOPT_TIMECONDITION, CURL_TIMECOND_IFMODSINCE);
}

// Enables logging for the outgoing header
curl_setopt($ch, CURLINFO_HEADER_OUT, true);

$data = curl_exec($ch);
$curlError = curl_error($ch);
$curlErrno = curl_errno($ch);
$curlInfo = curl_getinfo($ch);

Debug::log('Outgoing header: ' . json_encode($curlInfo));

if($data === false)
Debug::log('Cant\'t download ' . $url . ' cUrl error: ' . $curlError . ' (' . $curlErrno . ')');
Expand All @@ -80,25 +116,32 @@ function getContents($url, $header = array(), $opts = array()){
$headers = parseResponseHeader($header);
$finalHeader = end($headers);

if($errorCode !== 200) {
curl_close($ch);

if(array_key_exists('Server', $finalHeader) && strpos($finalHeader['Server'], 'cloudflare') !== false) {
switch($errorCode) {
case 200: // Contents received
Debug::log('New contents received');
$data = substr($data, $headerSize);
$cache->saveData($data);
return $data;
case 304: // Not modified, use cached data
Debug::log('Contents not modified on host, returning cached data');
return $cache->loadData();
default:
if(array_key_exists('Server', $finalHeader) && strpos($finalHeader['Server'], 'cloudflare') !== false) {
returnServerError(<<< EOD
The server responded with a Cloudflare challenge, which is not supported by RSS-Bridge!
If this error persists longer than a week, please consider opening an issue on GitHub!
EOD
);
}
);
}

returnError(<<<EOD
returnError(<<<EOD
The requested resource cannot be found!
Please make sure your input parameters are correct!
EOD
, $errorCode);
, $errorCode);
}

curl_close($ch);
return substr($data, $headerSize);
}

/**
Expand Down