On Wed, 21 Jun 2023 15:45:41 GMT, Alan Bateman <[email protected]> wrote:
>>> IIUC what @deepa181 is saying, it looks like the "IPv4 socket being unable >>> to join an IPv4 multicast group" problems surfaced when we moved away from >>> PlainDatagramSocketImpl in JDK 17? Probably because the delegate created >>> does not factor in the ProtocolFamily and though we started with attempting >>> to have an "IPv4 multicast socket join an IPv4 group", we end up trying to >>> have an "IPv4/IPv6 dual-stack socket (the delegate) join an IPv4 group" >>> which AIX doesn't permit. >> >> IIRC It has never been possible to create a non-dual `MulticastSocket` / >> `DatagramSocket` without setting the property >> `-Djava.net.preferIPv4Stack=true`. The possibility to select a protocol >> family independently of this property is only available with >> `DatagramChannel`. > >> IIRC It has never been possible to create a non-dual `MulticastSocket` / >> `DatagramSocket` without setting the property >> `-Djava.net.preferIPv4Stack=true`. The possibility to select a protocol >> family independently of this property is only available with >> `DatagramChannel`. > > Right now, Net.canIPv6SocketJoinIPv4Group() returns false on AIX so it will > never attempt to join an IPv4 multicast group when the socket is IPv6. The > old DatagamSocketImpl didn't have an eager check, which makes me wonder what > AIX supports, it's not clear! Hi @AlanBateman , I ran the Jtreg tests on **jdk17** and observed the following tests passed unexpectedly when I set the **VM_OPTIONS to `-Djdk.net.usePlainDatagramSocketImpl=true`** 1. java/net/MulticastSocket/B6427403.java 2. java/net/MulticastSocket/NoLoopbackPackets.java 3. java/net/MulticastSocket/SetLoopbackMode.java 4. java/net/MulticastSocket/Test.java I am curious about how setting the `jdk.net.usePlainDatagramSocketImpl` property impacts their behavior. I would like to understand why they pass with this configuration and whether it has any implications. Could you please share your insights on this matter? I appreciate your assistance in understanding this behavior and ensuring the correctness of the tests. Thank you. ------------- PR Comment: https://git.openjdk.org/jdk/pull/14142#issuecomment-1663829993
