/**
* Returns the hostname for this address.
*
* <p>If there is a security manager, this method first calls its <code>checkConnect</code> method
* with the hostname and <code>-1</code> as its arguments to see if the calling code is allowed to
* know the hostname for this IP address, i.e., to connect to the host. If the operation is not
* allowed, it will return the textual representation of the IP address.
*
* @return the host name for this IP address, or if the operation is not allowed by the security
* check, the textual representation of the IP address.
* @param check make security check if true
* @see SecurityManager#checkConnect
*/
private static String getHostFromNameService(InetAddress addr, boolean check) {
String host = null;
for (NameService nameService : nameServices) {
try {
// first lookup the hostname
host = nameService.getHostByAddr(addr.getAddress());
/* check to see if calling code is allowed to know
* the hostname for this IP address, ie, connect to the host
*/
if (check) {
SecurityManager sec = System.getSecurityManager();
if (sec != null) {
sec.checkConnect(host, -1);
}
}
/* now get all the IP addresses for this hostname,
* and make sure one of them matches the original IP
* address. We do this to try and prevent spoofing.
*/
InetAddress[] arr = InetAddress.getAllByName0(host, check);
boolean ok = false;
if (arr != null) {
for (int i = 0; !ok && i < arr.length; i++) {
ok = addr.equals(arr[i]);
}
}
// XXX: if it looks a spoof just return the address?
if (!ok) {
host = addr.getHostAddress();
return host;
}
break;
} catch (SecurityException e) {
host = addr.getHostAddress();
break;
} catch (UnknownHostException e) {
host = addr.getHostAddress();
// let next provider resolve the hostname
}
}
return host;
}
