esc_url.php

<?php

/**
 * Properly format a user-entered URL for use in an href or src attribute.
 * 
 * @param string $url User-entered URL
 * @return string Formatted URL
 */
function url_esc(string $url) : string
{
	$out = '';
	$query = '';
	$u = parse_url($url);

	if ( !empty($u['query']) ) {
		parse_str($u['query'], $qs);
		$query = '?' . http_build_query($qs, '&', '', PHP_QUERY_RFC3986);
	}

	$out .= !empty($u['scheme']) ? $u['scheme'].'://' : '';
	$out .= !empty($u['user']) ? $u['user'] . ( !empty($u['pass']) ? ':'.$u['pass'] : '') . '@' : '';
	$out .= $u['host'] ?? '';
	$out .= !empty($u['port']) ? ':'.$u['port'] : '';
	$out .= $u['path'] ?? '';
	$out .= $query;
	$out .= !empty($u['fragment']) ? '#'.$u['fragment'] : '';

	return filter_var($out, FILTER_SANITIZE_URL);
}

$foo = "https://user:pass@www.example.com:80/foo/bar.php?aa=דותן כהןׁ&cc=this is a variable#fragment";
var_dump($foo, url_esc($foo));

echo "\n";
$foo = "https://user@www.example.com/foo/bar.php?aa=דותן כהןׁ&cc=this is a variable#fragment";
var_dump($foo, url_esc($foo));

echo "\n";
$foo = "https://www.example.com/foo/bar.php?aa=דותן כהןׁ&cc=this is a variable#fragment";
var_dump($foo, url_esc($foo));

echo "\n";
$foo = "www.example.com/foo/bar.php?aa=דותן כהןׁ&cc=this is a variable#fragment";
var_dump($foo, url_esc($foo));

echo "\n";
$foo = "/foo/bar.php?aa=דותן כהןׁ&cc=this is a variable#fragment";
var_dump($foo, url_esc($foo));

echo "\n";
$foo = "foo/bar.php?aa=דותן כהןׁ&cc=this is a variable#fragment";
var_dump($foo, url_esc($foo));