A URL is a valid URL if at least one of the following conditions holds: The URL is a valid URI reference [RFC3986]. The URL is a valid IRI reference and it has no query component. [RFC3987]
Other easy way is use Node. JS DNS module. The DNS module provides a way of performing name resolutions, and with it you can verify if the url is valid or not.
You can use a native Filter Validator
filter_var($url, FILTER_VALIDATE_URL);
Validates value as URL (according to » http://www.faqs.org/rfcs/rfc2396), optionally with required components. Beware a valid URL may not specify the HTTP protocol http:// so further validation may be required to determine the URL uses an expected protocol, e.g. ssh:// or mailto:. Note that the function will only find ASCII URLs to be valid; internationalized domain names (containing non-ASCII characters) will fail.
Example:
if (filter_var($url, FILTER_VALIDATE_URL) === FALSE) {
die('Not a valid URL');
}
Here is the best tutorial I found over there:
http://www.w3schools.com/php/filter_validate_url.asp
<?php
$url = "http://www.qbaki.com";
// Remove all illegal characters from a url
$url = filter_var($url, FILTER_SANITIZE_URL);
// Validate url
if (filter_var($url, FILTER_VALIDATE_URL) !== false) {
echo("$url is a valid URL");
} else {
echo("$url is not a valid URL");
}
?>
Possible flags:
FILTER_FLAG_SCHEME_REQUIRED - URL must be RFC compliant (like http://example)
FILTER_FLAG_HOST_REQUIRED - URL must include host name (like http://www.example.com)
FILTER_FLAG_PATH_REQUIRED - URL must have a path after the domain name (like www.example.com/example1/)
FILTER_FLAG_QUERY_REQUIRED - URL must have a query string (like "example.php?name=Peter&age=37")
Using filter_var() will fail for urls with non-ascii chars, e.g. (http://pt.wikipedia.org/wiki/Guimarães). The following function encode all non-ascii chars (e.g. http://pt.wikipedia.org/wiki/Guimar%C3%A3es) before calling filter_var().
Hope this helps someone.
<?php
function validate_url($url) {
$path = parse_url($url, PHP_URL_PATH);
$encoded_path = array_map('urlencode', explode('/', $path));
$url = str_replace($path, implode('/', $encoded_path), $url);
return filter_var($url, FILTER_VALIDATE_URL) ? true : false;
}
// example
if(!validate_url("http://somedomain.com/some/path/file1.jpg")) {
echo "NOT A URL";
}
else {
echo "IS A URL";
}
function is_url($uri){
if(preg_match( '/^(http|https):\\/\\/[a-z0-9_]+([\\-\\.]{1}[a-z_0-9]+)*\\.[_a-z]{2,5}'.'((:[0-9]{1,5})?\\/.*)?$/i' ,$uri)){
return $uri;
}
else{
return false;
}
}
Personally I would like to use regular expression here. Bellow code perfectly worked for me.
$baseUrl = url('/'); // for my case https://www.xrepeater.com
$posted_url = "home";
// Test with one by one
/*$posted_url = "/home";
$posted_url = "xrepeater.com";
$posted_url = "www.xrepeater.com";
$posted_url = "http://www.xrepeater.com";
$posted_url = "https://www.xrepeater.com";
$posted_url = "https://xrepeater.com/services";
$posted_url = "xrepeater.dev/home/test";
$posted_url = "home/test";*/
$regularExpression = "((https?|ftp)\:\/\/)?"; // SCHEME Check
$regularExpression .= "([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?"; // User and Pass Check
$regularExpression .= "([a-z0-9-.]*)\.([a-z]{2,3})"; // Host or IP Check
$regularExpression .= "(\:[0-9]{2,5})?"; // Port Check
$regularExpression .= "(\/([a-z0-9+\$_-]\.?)+)*\/?"; // Path Check
$regularExpression .= "(\?[a-z+&\$_.-][a-z0-9;:@&%=+\/\$_.-]*)?"; // GET Query String Check
$regularExpression .= "(#[a-z_.-][a-z0-9+\$_.-]*)?"; // Anchor Check
if(preg_match("/^$regularExpression$/i", $posted_url)) {
if(preg_match("@^http|https://@i",$posted_url)) {
$final_url = preg_replace("@(http://)+@i",'http://',$posted_url);
// return "*** - ***Match : ".$final_url;
}
else {
$final_url = 'http://'.$posted_url;
// return "*** / ***Match : ".$final_url;
}
}
else {
if (substr($posted_url, 0, 1) === '/') {
// return "*** / ***Not Match :".$final_url."<br>".$baseUrl.$posted_url;
$final_url = $baseUrl.$posted_url;
}
else {
// return "*** - ***Not Match :".$posted_url."<br>".$baseUrl."/".$posted_url;
$final_url = $baseUrl."/".$final_url; }
}
Actually... filter_var($url, FILTER_VALIDATE_URL); doesn't work very well. When you type in a real url, it works but, it only checks for http:// so if you type something like "http://weirtgcyaurbatc", it will still say it's real.
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