On Thu, 16 Feb 2023 18:54:05 GMT, Daniel Jeliński <djelin...@openjdk.org> wrote:
>> You and me both. As I wrote in the giant comment, I did a lot of >> experimenting. In the end, what I determined was that if the IGMPLevel >> (IPv4) or MldLevel (IPv6) is set to 0 (None), then attempting to join a >> multicast group throws an exception. So that seemed like a reasonable thing >> that supportsMulticast() could measure. Nothing else I tried, including the >> existing GetAdaptersAddresses approach, indicated that multicast was >> disabled in those situations. >> >> Having said that, I'd be okay with ditching all of this code and just >> returning true unconditionally. It's unlikely that multicast would be >> disabled, and a single boolean isn't enough to express the actual setting >> anyway, since Windows apparently lets you disable receiving multicasts while >> still allowing you to send them. > > Ha! Apparently I have a machine where the implementation of > `supportsMulticast` implementation makes a difference. On my machine the test > `jdk/java/net/SocketOption/OptionsTest.java` is failing with: > > java.net.SocketException: Invalid argument: no further information > at java.base/sun.nio.ch.Net.setInterface6(Native Method) > at > java.base/sun.nio.ch.DatagramChannelImpl.setOption(DatagramChannelImpl.java:377) > at > java.base/sun.nio.ch.DatagramSocketAdaptor.setOption(DatagramSocketAdaptor.java:431) > at java.base/java.net.DatagramSocket.setOption(DatagramSocket.java:1207) > at OptionsTest.test(OptionsTest.java:155) > at OptionsTest.doMulticastSocketTests(OptionsTest.java:235) > at OptionsTest.main(OptionsTest.java:337) > ... > > It works with the current master. Will try to figure it out. > > BTW. did you try running jdk_net tests? I ran the tests for NetworkInterface specifically, though that reminds me that I need to open a bug report about fixpath mangling things incorrectly. I'll give the full jdk_net suite a run and see what happens. ------------- PR: https://git.openjdk.org/jdk/pull/12593
