[jcifs] jcifs problem and wins resolution

[Michael B. Allen]

On Thu, 26 Sep 2002 05:23:13 -0700
Joe Bentley <jbentley at zonelabs.com> wrote:

>  
> > My servlet runs on the SRVGE03 Windows 2000 Server PDC,
> > which also happens to be the DMB; IPCONFIG on SRVGE03 states also that
> > it is an H-node, and its Wins "client" configuration points to SRVGE02,
> > another
> > Windows 2000 Server DC running the Wins server service.
> > 
> > In conclusion:
> > I have the  \01\02__MSBROWSE__\02<01>  entry in my Wins Server
> > but even if I don't query the Wins Server:
> > I have the  \01\02__MSBROWSE__\02<01> registered on my network (if I type
> > NBTSTAT -n on SRVGE03 I see the entry)
> > and I should get this name via Broadcast !
> > 
> > I specified the following properties in my servlet:
> >         jcifs.Config.setProperty("jcifs.netbios.wins", "192.168.69.6");
> >         jcifs.Config.setProperty("jcifs.netbios.baddr", "192.168.69.255");
> >         jcifs.Config.setProperty("jcifs.resolveOrder", "WINS,DNS,BCAST");
> > 
> 
> I've noticed the same problem too.  It's because you are executing your code
> on the PDC and a host cannot broadcast to it self.  
> 
> The problem can also be reproduced doing following:
>   jcifs.Config.setProperty("jcifs.netbios.baddr", "127.0.0.1");
> 
> If you move your code off the DCs, it should work, providing that the baddr
> includes at least one DC.  Yeah I know it's a lame work around.  Let me know
> if you find a better answer.

Interesting! I'm not so sure there is another workaround though because I don't
think Java can bind to multiple interfaces.

> 
> That reminds me, the global jcifs.Config.setProperty("jcifs.netbios.baddr")
> design doesn't work for me.  I need to be able to pass a broadcast address
> into the SmbFile("smb://") call to locally override the jcifs.netbios.baddr
> setting.  My jCIFS code is sitting on a gateway machine where I need to
> broadcast to separate networks that may have over-lapping domain names.

Since I'm doing the URL overhaul I'll consider making baddr a query
string parameter like:

  smb://server/share/path?BADDR=192.168.10.255

> Currently a single-threaded synchronized block is required to protect the
> global baddr value before a broadcast call.
> 
> Here's an example:
> 
> class CIFSDriver {
> 
> 	public static String getDomainController(String domain,
> 		String broadcastAddress) {
> 
> 		InetAddress	baddr;
> 
> 		try {
> 			baddr = InetAddress.getByName(broadcastAddress);
> 		}
> 		catch (UnknownHostException e)
> 		{
> 			baddr = null;
> 		}
> 
> 		try {
> 			return NbtAddress.getByName(domain, 0x1c, null,
> 				baddr).getHostAddress();
> 		}
> 		catch (UnknownHostException e)
> 		{
> 			return null;
> 		}
> 	}
> 
> 	public synchronized static void listDomains(String broadcastAddress)
> 		throws Exception {
> 
> 		String oldAddr = jcifs.Config.getProperty("baddr");
> 		jcifs.Config.setProperty("baddr", broadcastAddress);
> 
> 		SmbFile connection = new SmbFile("smb://");
> 		String[] domains = connection.list();
> 		for (int i = 0; i < domains.length; i++)
> 			System.out.println(domains[i] + ":" +
> 				getDomainController(domains[i],
> broadcastAddress));
> 
> 		if (oldAddr != null)
> 			jcifs.Config.setProperty("baddr", oldAddr);
> 	}

I'm surprised this actually works. Another thing I will have to do
eventually is make it so that all (most) parameters can be set at runtime
rather than in static initializers.

> 
> 	public static void main(String[] args) throws Exception {
> 
> 		listDomains("192.168.50.255");
> 		listDomains("115.63.255.255");
> 	}
> }
> 
> -joe


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