Datagram socket leak

[Michael McMahon]

Right. That would work assuming createImpl() doesn't leave the socket open
if it throws an exception, which seems to be the case.

On 01/09/11 18:05, Salter, Thomas A wrote:
> Maybe I posted a bad patch, but my intent was to do the try-finally after checking for a non-null bind address.
>
>      public DatagramSocket(SocketAddress bindaddr) throws SocketException {
>          // create a datagram socket.
>          createImpl();
>          if (bindaddr != null) {
>            try {
>              bind(bindaddr);
>            } finally {
>                if( !isBound() )
>                    close();
>            }
>          }
>      }
>
> On a related note, I've also noticed that the Socket and ServerSocket constructors can throw without closing the implementation, but this only happens with IllegalArgumentException or other RuntimeExceptions.  I'm not sure what your policy is on cleaning up after runtime exceptions.
>
The SocketImpl finalizer does eventually clean up. But, I agree we 
shouldn't rely on that
especially in cases like the IAE explicitly thrown in the constructor. 
We'll include those
cases in the fix for this bug as well.

Michael.
> -----Original Message-----
> From: Michael McMahon [mailto:michael.x.mcmahon at oracle.com]
> Sent: Thursday, September 01, 2011 12:47 PM
> To: Salter, Thomas A
> Cc: net-dev at openjdk.java.net
> Subject: Re: Datagram socket leak
>
> Thomas,
>
> Thanks for pointing this out. We overlooked this in the recent change in
> this
> area. One thing though, in the second change to DatagramSocket we can't
> just check for isBound()  since the socket might legitimately be unbound
> (bindaddr is null). All I can think is that we catch the exception and
> re throw
> it, after closing,  rather than use a finally() in that case. I have
> created a bug report (7085981)
> to track this. I'll post a webrev for it soon.
>
> - Michael.
>
> On 29/08/11 20:01, Salter, Thomas A wrote:
>> Here's what I changed.  I'm working with the fcs source bundle for b147,  27_jun_2011, so I may not have the latest source base.
>>
>> Left base folder: new
>> Right base folder: b147
>>
>> File: src\share\classes\java\net\DatagramSocket.java
>> 186,189d185
>> <           finally {
>> <               if( !isBound() )
>> <                   close();
>> <           }
>> 234d229
>> <             try {
>> 236,239d230
>> <             } finally {
>> <                 if( !isBound() )
>> <                     close();
>> <             }
>>
>> File: src\share\classes\java\net\MulticastSocket.java
>> 165d164
>> <             try {
>> 167,170d165
>> <             } finally {
>> <                 if( !isBound() )
>> <                     close();
>> <             }
>>
>>
>>
>>
>> -----Original Message-----
>> From: Chris Hegarty [mailto:chris.hegarty at oracle.com]
>> Sent: Monday, August 29, 2011 2:33 PM
>> To: Salter, Thomas A
>> Cc: net-dev at openjdk.java.net
>> Subject: Re: Datagram socket leak
>>
>> Ah ok. I finally get it.
>>
>> In which case I think you original changes should be fine. Do you want
>> to make similar changes to MulticastSocket and post the diffs?
>>
>> Also, I think a testcase would be useful here. I know it's not strictly
>> specified that the socket should be closed if the constructor throws,
>> but it does seem desirable.
>>
>> -Chris.
>>
>> On 08/29/11 07:14 PM, Salter, Thomas A wrote:
>>> I believe you're referring to the close() in the catch clause following the call to getImpl().bind.  The problem I encountered was when the Datagram.bind threw an exception before it got that far.  In my case, the checkListen was throwing a SecurityException, but any of the earlier throws would cause the same problem.  The SecurityException wouldn't have been caught by the catch addressed by the CR in any case.  We encountered this while running the TCK.  One of its tests tries to create lots of sockets, all of them getting security violations until we hit a limit on the number of open sockets.
>>>
>>>        public synchronized void bind(SocketAddress addr) throws SocketException {
>>>            if (isClosed())
>>>                throw new SocketException("Socket is closed");
>>>            if (isBound())
>>>                throw new SocketException("already bound");
>>>            if (addr == null)
>>>                addr = new InetSocketAddress(0);
>>>            if (!(addr instanceof InetSocketAddress))
>>>                throw new IllegalArgumentException("Unsupported address type!");
>>>            InetSocketAddress epoint = (InetSocketAddress) addr;
>>>            if (epoint.isUnresolved())
>>>                throw new SocketException("Unresolved address");
>>>            InetAddress iaddr = epoint.getAddress();
>>>            int port = epoint.getPort();
>>>            checkAddress(iaddr, "bind");
>>>            SecurityManager sec = System.getSecurityManager();
>>>            if (sec != null) {
>>>                sec.checkListen(port);<<<<<<<<<<<<<<<<<<<<<<<<<<    This throws a SecurityException
>>>            }
>>>            try {
>>>                getImpl().bind(port, iaddr);
>>>            } catch (SocketException e) {
>>>                getImpl().close();
>>>                throw e;
>>>            }
>>>            bound = true;
>>>        }
>>>
>>> Tom.
>>>
>>>
>>> -----Original Message-----
>>> From: Chris Hegarty [mailto:chris.hegarty at oracle.com]
>>> Sent: Monday, August 29, 2011 1:56 PM
>>> To: Salter, Thomas A
>>> Cc: net-dev at openjdk.java.net
>>> Subject: Re: Datagram socket leak
>>>
>>> [take two!]
>>>
>>> Tom,
>>>
>>> This specific area of code was changed recently due to CR 7035556 [1],
>>> changeset [2], and this issue was discussed during the code review [3].
>>>
>>> Essentially, bind() already closes the impl internally before throwing
>>> the exception. Does this resolve the issue for you? Or do you still see
>>> potential to leak?
>>>
>>> -Chris
>>>
>>> [1] http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7035556
>>> [2] http://hg.openjdk.java.net/jdk8/tl/jdk/rev/07a12583d4ea
>>> [3] http://mail.openjdk.java.net/pipermail/net-dev/2011-July/003318.html
>>>
>>> On 08/29/11 03:27 PM, Salter, Thomas A wrote:
>>>> There appears to be a socket leak in both DatagramSocket and
>>>> MulticastSocket constructors. Both classes have constructors that create
>>>> a socket and then attempt to bind. The bind can fail with a variety of
>>>> exceptions none of which are caught by the constructor. Thus, the actual
>>>> system socket that was allocated by impl.create() is never closed.
>>>>
>>>> My fix was to wrap a try-finally around the bind call and call close()
>>>> if isBound is false.
>>>>
>>>> public DatagramSocket(SocketAddress bindaddr) throws SocketException {
>>>>
>>>> // create a datagram socket.
>>>>
>>>> createImpl();
>>>>
>>>> if (bindaddr != null) {
>>>>
>>>> try {
>>>>
>>>> bind(bindaddr);
>>>>
>>>> } finally {
>>>>
>>>> if( !isBound() )
>>>>
>>>> close();
>>>>
>>>> }
>>>>
>>>> }
>>>>
>>>> }
>>>>
>>>> Tom Salter
>>>>
>>>> Unisys Corporation
>>>>