Date: Mon, 23 Aug 2004 09:51:54 -0600 From: Greg Lewis <glewis@eyesbeyond.com> To: Brad Karp <bkarp+@cs.cmu.edu> Cc: freebsd-java@freebsd.org Subject: Re: getHostName() broken? Message-ID: <20040823155154.GA15838@misty.eyesbeyond.com> In-Reply-To: <20040820030209.9E7D643D1D@mx1.FreeBSD.org> References: <20040820030209.9E7D643D1D@mx1.FreeBSD.org>
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--r5Pyd7+fXNt84Ff3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Aug 19, 2004 at 11:01:30PM -0400, Brad Karp wrote: > I'm running 4.9-RELEASE, and have built the jdk1.4.2 port using revision 5 > of the FreeBSD patch kit. > > I have a visualization application written in Java by a colleague that I've > been running. The application shows nodes in a large-scale distributed system, > and allows clicking on a host to show its Internet hostname. > > The code uses getHostName() to do this. > > I find that these reverse DNS lookups *all* fail; getHostName() returns a > String that is a textual representation of the IP address. (There's no > security manager involved here, BTW. The reference for getHostName() says > the security manager may check for authorization on getHostName() calls, > but I've not changed my Java runtime's security policy from the defaults.) > > Further poking reveals that *no* outbound DNS queries (traffic destined for > UDP or TCP port 53) are being generated for these reverse name lookups! > > I'm perplexed. Can it really be that InetAddress.getHostName() is broken on > FreeBSD? Has anyone seen similar behavior, and if so, can you propose a > workaround, apart from linking in C code to do these reverse name lookups? Works for me. Test code attached. Here is the output: > java -cp . HostName 66.35.250.151 star.slashdot.org Are you sure resolution works for you normally? Can you run host(1) and check that lookups succeed for the hosts? -- Greg Lewis Email : glewis@eyesbeyond.com Eyes Beyond Web : http://www.eyesbeyond.com Information Technology FreeBSD : glewis@FreeBSD.org --r5Pyd7+fXNt84Ff3 Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="HostName.java" import java.net.*; class HostName { public static void main(String[] args) { try { InetAddress addr = InetAddress.getByName("66.35.250.151"); System.out.println(addr.getHostAddress()); System.out.println(addr.getHostName()); } catch (Throwable t) { t.printStackTrace(); } } } --r5Pyd7+fXNt84Ff3--
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