getLocalAddress().getHostAddress() returning an empty string

Thread view:

yawnmoth - 17 Nov 2006 18:00 GMT

Say I have the following:

(new Socket("some domain", 80).getLocalAddress().getHostAddress()

Are there conditions under which that can return an empty string? I
ask because I have a script that does that, among other things, and I
have some people telling me that it's not working for them - that it's
returning the empty string for them.

Any ideas would be appreciated - thanks!

Reply to this Message

Carl - 17 Nov 2006 20:25 GMT

> Say I have the following:
>
[quoted text clipped - 6 lines]
>
> Any ideas would be appreciated - thanks!

yawnmoth,

It would be easier to try to help if you post the code in context,
based on only this line it is hard to even guess what the problem is.
Are you sure the Socket is being successfully instantiated and not
throwing some exception?

Carl.

Reply to this Message

yawnmoth - 17 Nov 2006 21:17 GMT

> <snip>
> yawnmoth,
[quoted text clipped - 3 lines]
> Are you sure the Socket is being successfully instantiated and not
> throwing some exception?

Here's the context:

import java.applet.*;
import java.net.*;

public class HttpRequestor extends Applet
{
    public void start()
    {
        try
        {
            Socket sock = new Socket(getParameter("domain"),
Integer.parseInt(getParameter("port")));
            String path =
getParameter("path")+"&local="+sock.getLocalAddress().getHostAddress();
            String httpRequest = "GET "+path+" HTTP/1.0\r\nHost:
"+getParameter("domain")+"\r\n\r\n";
            sock.getOutputStream().write(httpRequest.getBytes());
            sock.getInputStream();
        }
        catch (Exception e)
        {
            //e.printStackTrace();
        }
    }
}

The Socket is clearly being created since, if it weren't, I wouldn't
get the HTTP request.

Is it possible that getLocalAddress().getHostAddress() simply doesn't
work on all versions of the JRE?

Reply to this Message

Manish Pandit - 17 Nov 2006 22:18 GMT

You're opening a connection from an Applet - Is this a trusted applet,
and is the server on which you're opening the port on the Applet host?

-cheers,
Manish

Reply to this Message

yawnmoth - 18 Nov 2006 00:46 GMT

> You're opening a connection from an Applet - Is this a trusted applet,
> and is the server on which you're opening the port on the Applet host?

Yes to the latter. With regard to the former... what is a trusted
applet vs. an untrusted one?

That said, in an attempt to diagnose this problem, I've started logging
requests made to the server side script, and while, most of the time,
the local parameter is set, it isn't always.

The fact, however, that an entry exists in the log at all suggests that
the request was made successfully.

Reply to this Message

Manish Pandit - 18 Nov 2006 05:52 GMT

I believe a trusted applet can make connections outside of the host it
originated from. You can google it out for more info.

Another thing I noticed - can you uncomment the exception handling
part, so you can see if there is one being thrown?

-cheers,
Manish

Reply to this Message

Chris Uppal - 18 Nov 2006 17:02 GMT

> Is it possible that getLocalAddress().getHostAddress() simply doesn't
> work on all versions of the JRE?

It doesn't appear to be possible for 1.4 or 1.5 to return an empty string
(judging by the source to the concrete subclasses of InetAddress: Inet4Address
and Inet6Address).

But what, say, the antediluvian MS JVM (or rather: "J"VM) does is anybody's
guess.

-- chris

Reply to this Message

getLocalAddress().getHostAddress() returning an empty string

Free Magazines