// 000712, steven@haryan.to
/*
an example of usage:
<? require "/path/to/this/file"; ?>
My validated bookmarks:
<ul>
<li><? disp_link("http://slashdot.org", "Slashdot"); ?>
<li><? disp_link("http://www.zope.org", "Zope"); ?>
<li><? disp_link("http://www.python.org", "Python"); ?>
<li><? disp_link("http://www.perl.com", "Perl"); ?>
<li><? disp_link("http://www.php.net", "Zend"); ?>
<li><? disp_link("http://www.perl.com/CPAN-local/", ""); ?>
</ul>
btw, yup, of course this code is under GPL.
*/
$debug = 0;
$timeout = 30; // give up if can't connect within 30 secs.
$check_freq = 5*60; // cache for 5 minutes.
session_register('statuses');
session_register('hostnames');
function flush_disp_link_cache() {
global $statuses;
global $hostnames;
$statuses = array();
$hostnames = array();
}
function disp_link($url, $text) {
global $debug;
global $timeout;
global $statuses;
global $hostnames;
global $check_freq;
$now = time();
$e = error_reporting(); error_reporting($e & (255-E_WARNING));
if (!preg_match('/^(http|https|ftp)://((?:w+.?)+):?(d*)/', $url, $m)) {
// it's a relative link, or absolute link with unsupported protocol
// so there's no need to check
$status = '';
if ($debug) { $status='DEBUG:UNCHECKED'; }
} else {
$proto=$m[1];
$hostname=strtolower($m[2]);
$port=$m[3];
// is the host an IP address?
if (preg_match('/^d+.d+.d+.d+/', $hostname)) {
$ip = $hostname;
} else { // it's not, so we have to resolve it first
// have we tried to resolve it not so long ago?
$from_cache=0;
if (isset($hostnames[$hostname])) {
if ($debug) {
echo "DEBUG: last resolve = ", $hostnames[$hostname][1], "<br>";
}
if ($now - $hostnames[$hostname][1] <= $check_freq) {
$ip = $hostnames[$hostname];
$from_cache=1;
}
}
if (!$from_cache) {
// we haven't, so resolve it
$ip = gethostbyname($hostname);
// if the hostname was not resolvable, gethostbyname returns
// its argument unchanged
if ($ip == $hostname) { $ip=''; }
// cache this resolve
$hostnames[$hostname]=array($ip,$now);
}
}
if (!$ip) { // was the hostname unresolvable?
$status = 'HOST NOT FOUND';
} else {
// get universal port number defaults, if not specified
if (!$port) {
if ($proto == 'http') { $port = 80; }
elseif ($proto == 'https') { $port = 443; }
elseif ($proto == 'ftp') { $port = 21; }
}
$key = "$ip:$port";
// have we checked the site not so long ago?
$from_cache=0;
if (isset($statuses[$key])) {
if ($debug) {
echo "DEBUG: last check = ",$statuses[$key][1], "<br>";
}
if ($now-$statuses[$key][1] <= $check_freq) {
$status = $statuses[$key][0];
$from_cache=1;
}
}
if (!$from_cache) {
// we haven't, so check it
if ($debug) {
echo "DEBUG: checking: proto=$proto, hostname=$hostname, ",
"ip=$ip, port=$port...<br>";
}
$fp = fsockopen($hostname, $port, &$errno, &$errstr, $timeout);
if ($debug) {
echo "DEBUG: connect result: fp=$fp, errno=$errno, errstr=$errstr<br>";
}
if ($fp) {
$status = "OK";
} else {
if (preg_match('/timed?[- ]?out/i', $errstr)) {
$status = "TIMEOUT";
} elseif (preg_match('/refused/i', $errstr)) {
$status = "OFF";
} else {
$status = "DOWN?";
}
}
// cache this check
$statuses[$key] = array($status, $now);
}
}
}
echo "<A HREF="$url">", ($text ? $text : htmlentities($url)), "</A>";
if ($status) { echo " ($status)"; }
error_reporting($e);
}
?>
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