preg-match

I want to add a feature to my website to let users search the texts with RegEx . But, is it safe to let the users do something like that ? preg_match('/' . $user_input_regex . '/', $subject); There is a possible attack on this code called a ReDoS attack (Regular expression Denial of Service). The Regular expression Denial of Service (ReDoS) is a Denial of Service attack, that exploits the fact that most Regular Expression implementations may reach extreme situations that cause them to work very slowly (exponentially related to input size). An attacker can then cause a program using a Regular

I need to replace urls in the page taken by curl and add correct link to images and links. My php curl code is: <?php $result = '<a href="http://host.org"><img src="./sec.png"></a> <link href="./styles.css" rel="alternate stylesheet" type="text/css" /> <script type="text/javascript" src="./style.js"></script>'; echo $result; if (!preg_match('/src="https?:\/\/"/', $result)) { $result = preg_replace('/src="(http:\/\/([^\/]+)\/)?([^"]+)"/', "src=\"http://google.com/\\3\"", $result); } echo $result; if (!preg_match('/href="https?:\/\/"/', $result)) { $result = preg_replace('/href="(http:\/\/([^\/]

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center . I have a string : <div id="post_message_957119941"> I want to fetch only the numbers (957119941) from this string using preg_match . This shouldn't be too hard. $str = '<div id="post_message_957119941">'; if ( preg_match ( '/post_message_([0-9]+)/', $str, $matches ) ) { print_r($matches); } Output: Array ( [0] => post_message

Without using u flag the hex range that can be used is [\x{00}-\x{ff}] , but with u flag it goes up to a 4-byte value \x{7fffffff} ( [\x{00000000}-\x{7fffffff}] ). So if I execute the below code: preg_match("/[\x{00000000}-\x{80000000}]+/u", $str, $match); Will get this error : Warning: preg_match(): Compilation failed: character value in \x{...} sequence is too large So I can't match a letter like 𡃁 with equivalent hex value of f0 a1 83 81 . The question is not how to match these letters, but how this range & this boundary came from as u modifier should treat strings as UTF-16 PCRE supports

I am going to build a multilingual website with PHP and need to have a preg_match which passes all Unicode characters and numbers. i.e I need it to pass English letters, Spanish letters,Italian letters and as you may know I don't want to pass other characters like ' " _ - and ... I want some thing like this : $pattern='/^[unicode chars without \'-_;?]*$/u'; if(!preg_match($pattern, $url)) echo #error; Unicode property for letter is \pL so in preg_match : preg_match('/^\pL+$/u', $string); for an url you could add numbers \pN and dot: preg_match('/^[\pL\pN.]+/u', $string); 来源： https:/