Re: RFR[8242885]: 'PlainDatagramSocketImpl doesn’t allow for the sending of IPv6 datagrams on macOS with sizes between 65508-65527 bytes'

[Daniel Fuchs]

Hi Patrick,

test/jdk/java/net/DatagramSocket/SetGetSendBufferSize.java

   95         if(Platform.isOSX() && IPSupport.hasIPv6()) {
   96             try (var socket = supplier.open()){
   97                 assertTrue(socket.getSendBufferSize() >= 65507, name);
   98             }
   99         }

I'd suggest:

          if (Platform.isOSX()) {
              try (var socket = supplier.open()){
                  assertTrue(socket.getSendBufferSize() >= 65507, name);
                  if (IPSupport.hasIPv6() && !IPSupport.preferIPv4Stack()) {
                      assertEquals(socket.getSendBufferSize(), 65527, name);
                  }
              }
          }

test/jdk/java/net/DatagramSocket/SendReceiveMaxSize.java

The test has many issues, that you should be able to fix:

a. it tests for preferIPv6Addresses, but preferIPv6Addresses is
    always false.
b. to be able to send a datagram of size 65527, you need three
    things:
       a. the socket must be a dual socket.
          this depends on two conditions: hasIPv6 && !preferIPv4Stack
       b. the socket must be bound to an IPv6 address
       c. the remote address must be IPv6

I believe the test should be reworked to correctly test all these
things - and use the right combination of -Dprefer* to have a chance
to test all these scenarios.



test/jdk/java/nio/channels/DatagramChannel/SendReceiveMaxSize.java

This looks better, but `assertEquals(sendBuf, receiveBuf);`
probably doesn't do what you think it does. Please consider
the answers to these questions:

     1. what is the state of sendBuf at the point where you
        call assertEquals? What are its position and limit?
     2. same question for receiveBuf?
     3. what does assertEquals do to check that the two buffers
        are equals?

hope this helps,

-- daniel

On 09/07/2020 16:25, Patrick Concannon wrote:
> Hi,
> 
> Sorry for the delay.
> 
> Alan: I’ve changed `testInitialSendBufferSize` in the test 
> `test/java/net/DatagramSocket/SetGetSendBufferSize.java` to now check 
> the limit when the socket is IPv6 only. I’ve also updated the tests to 
> be end-to-end (rather than use the loopback) as requested.
> 
> Vyom: I’ve updated the fix to use int constants now in place of values.
> 
> webrev: http://cr.openjdk.java.net/~pconcannon/8242885/webrevs/webrev.01/
> 
> Kind regards,
> Patrick
>