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Add Network::checkEtagModified method

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This commit is contained in:
Hypolite Petovan 2020-04-05 17:58:09 -04:00
parent 7899892351
commit f96d1fbd0b
1 changed files with 42 additions and 0 deletions
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42
src/Util/Network.php
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@ -910,4 +910,46 @@ class Network
return self::unparseURL($parsed); return self::unparseURL($parsed);
} }
/**
* Generates ETag and Last-Modified response headers and checks them against
* If-None-Match and If-Modified-Since request headers if present.
*
* Blocking function, sends 304 headers and exits if check passes.
*
* @param string $etag The page etag
* @param string $last_modified The page last modification UTC date
* @throws \Exception
*/
public static function checkEtagModified(string $etag, string $last_modified)
{
$last_modified = DateTimeFormat::utc($last_modified, 'D, d M Y H:i:s') . ' GMT';
/**
* @see http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.26
*/
$if_none_match = filter_input(INPUT_SERVER, 'HTTP_IF_NONE_MATCH');
$if_modified_since = filter_input(INPUT_SERVER, 'HTTP_IF_MODIFIED_SINCE');
$flag_not_modified = null;
if ($if_none_match) {
$result = [];
preg_match('/^(?:W\/")?([^"]+)"?$/i', $etag, $result);
$etagTrimmed = $result[1];
// Lazy exact ETag match, could check weak/strong ETags
$flag_not_modified = $if_none_match == '*' || strpos($if_none_match, $etagTrimmed) !== false;
}
if ($if_modified_since && (!$if_none_match || $flag_not_modified)) {
// Lazy exact Last-Modified match, could check If-Modified-Since validity
$flag_not_modified = $if_modified_since == $last_modified;
}
header('Etag: ' . $etag);
header('Last-Modified: ' . $last_modified);
if ($flag_not_modified) {
header("HTTP/1.1 304 Not Modified");
exit;
}
}
} }