Behavior of DatagramChannel vs ByteBuffers bound to MemorySessions

[Cleber Muramoto]

Hello, I'd like to understand why a disconnected DatagramChannel does not
support direct buffers derived from MemorySegments created from shared
Arenas.

The connected code path uses IOUtil, which obtains the address via
JavaNioAccess and the disconnected one obtains the address
via ((sun.nio.ch.DirectBuffer)bb).address(), which undergoes MemorySession
validation semantics.

Example:

----
  var buffer =
Arena.ofShared().allocate(1024).asByteBuffer().putInt(42).flip();

  var dc = DatagramChannel.open();
  dc.bind(new InetSocketAddress(10000));
  dc.join(InetAddress.getByName("225.0.0.0"),
NetworkInterface.getByInetAddress(InetAddress.getLoopbackAddress()));

  // works
  dc.connect(new InetSocketAddress("225.0.0.0", 1024));
  dc.write(buffer);
  dc.disconnect();

  // UnsupportedOperationException
  dc.send(buffer.rewind(), new InetSocketAddress("225.0.0.0", 1024));
----

Regards
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