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From Paulex Yang <paulex.y...@gmail.com>
Subject Re: [jira] Updated: (HARMONY-73) java.net.InetAddress.getLocalHost() returns wrong host name for loopback address
Date Fri, 10 Feb 2006 05:54:44 GMT
As I commented in the JIRA, further study shows some interesting facts,

first, my prior patch is redundant, the actual bug is 
http://issues.apache.org/jira/browse/HARMONY-84.

second, there is another different behavior of getHostName() between RI 
and Harmony, but I consider it as RI's bug:

The java spec of getHostName() says:
<spec>*
Returns: *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.
</spec>

But the following test shows RI will return host name instead of IP 
address if the host name can be got without reverse name lookup.

<code>
public class HostNameTest{
    public static void main(String[] args) throws Exception{
        InetAddress addr = InetAddress.getByName("localhost");
        InetAddress addr2 = InetAddress.getByAddress(new byte[]{127, 0, 
0, 1});
        SecurityManager sm = new Inet_SecurityManager();
        System.setSecurityManager(sm);
        System.out.println(addr.getHostName());
        System.out.println(addr2.getHostName());
    }
   
    static class Inet_SecurityManager extends SecurityManager {
        public void checkConnect(String host, int port) {
         super.checkConnect(host,port);
        throw new SecurityException();
        }
    }
}
</code>

RI outputs:
localhost
127.0.0.1

Harmony outputs:
127.0.0.1
127.0.0.1

This time, Harmony win :-D .

Geir Magnusson Jr wrote:
> isn't "localhost" actually something in the local hosts file?  Don't 
> you want to look this up?
>
> Paulex Yang (JIRA) wrote:
>>      [ http://issues.apache.org/jira/browse/HARMONY-73?page=all ]
>>
>> Paulex Yang updated HARMONY-73:
>> -------------------------------
>>
>>     Attachment: InetAddress.patch
>>
>> A suggested modification is to add these two lines before Ln. 296 of 
>> java.net.InetAddress,
>> if(this == LOOPBACK){
>>      return "localhost";
>> }
>>
>> So that the getHostName() will return "localhost" instead of 
>> "127.0.0.1".
>>
>> The patch is attached.
>>>  java.net.InetAddress.getLocalHost() returns wrong host name for 
>>> loopback address
>>> ---------------------------------------------------------------------------------

>>>
>>>
>>>          Key: HARMONY-73
>>>          URL: http://issues.apache.org/jira/browse/HARMONY-73
>>>      Project: Harmony
>>>         Type: Bug
>>>   Components: Classlib
>>>     Reporter: Svetlana Samoilenko
>>>     Priority: Minor
>>>  Attachments: InetAddress.patch
>>>
>>> J2se 1.4.2 and 5.0 specifications for 
>>> java.net.InetAddress.getLocalHost() read, that if there is a 
>>> security manager, its checkConnect method is called with the local 
>>> host name and -1 as its arguments to see if the operation is 
>>> allowed. If the operation is not allowed, an InetAddress 
>>> representing the loopback address is returned as 
>>> hostname/hostaddress (as followed from toString() specification).
>>> The test listed below shows that the returned loopback address has 
>>> wrong hostname, "127.0.0.1" instead of "loopback".
>>> Inet_SecurityManager class is called twice and therefore host name 
>>> is substituted with hostaddress address.
>>> Code to reproduce: import java.net.*; public class test2 {     
>>> public static void main(String[] args) {         try {             
>>> System.setSecurityManager(new Inet_SecurityManager());
>>>             System.out.println("Loopback address = " + 
>>> InetAddress.getLocalHost());
>>>         } catch (Exception e){             
>>> System.out.println("Unexpected exception = " + e);         };     } 
>>> } class Inet_SecurityManager extends SecurityManager {     public 
>>> void checkConnect(String host, int port) {         
>>> super.checkConnect(host,port);         throw new SecurityException();
>>>     }
>>> }
>>> Steps to Reproduce: 1. Build Harmony (check-out on 2006-01-30) j2se 
>>> subset as described in README.txt. 2. Compile test2.java using BEA 
>>> 1.4 javac
>>>> javac -d . test2.java 
>>> 3. Run java using compatible VM (J9)
>>>> java -showversion test2 
>>> Output: C:\tmp>C:\jrockit-j2sdk1.4.2_04\bin\java.exe -showversion 
>>> test2 java version "1.4.2_04" Java(TM) 2 Runtime Environment, 
>>> Standard Edition (build 1.4.2_04-b05) BEA WebLogic JRockit(TM) 
>>> 1.4.2_04 JVM (build ari-31788-20040616-1132-win-ia32, Native 
>>> Threads, GC strategy: parallel) Inet_SecurityManager :host= nswssamoil1
>>> Inet_SecurityManager :port= -1
>>> Loopback address = localhost/127.0.0.1
>>> C:\tmp>C:\harmony\trunk\deploy\jre\bin\java -showversion test2 (c) 
>>> Copyright 1991, 2005 The Apache Software Foundation or its 
>>> licensors, as applicable. Inet_SecurityManager :host= nswssamoil1
>>> Inet_SecurityManager :port= -1
>>> Inet_SecurityManager :host= localhost
>>> Inet_SecurityManager :port= -1
>>> Loopback address = 127.0.0.1/127.0.0.1
>>> Suggested junit test case:
>>> ------------------------ InetAddressTest.java 
>>> ------------------------------------------------- import java.net.*; 
>>> import junit.framework.*; public class InetAddressTest extends 
>>> TestCase {     public static void main(String[] args) {         
>>> junit.textui.TestRunner.run(InetAddress.class);     }     public 
>>> void test_getLocalHost() {         try{                        
>>> System.setSecurityManager(new Inet_SecurityManager());             
>>> String hostname=InetAddress.getLocalHost().getHostName();           
>>>             assertEquals("localhost", hostname);
>>>         } catch (Exception e){             fail("Unexpected 
>>> exception = " + e);         };              } }
>>> class Inet_SecurityManager extends SecurityManager {     public void 
>>> checkConnect(String host, int port) {         
>>> super.checkConnect(host,port);         throw new SecurityException();
>>>     }
>>> } 
>>
>


-- 
Paulex Yang
China Software Development Lab
IBM



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