*From: *Chris Hegarty <chris.hega...@oracle.com> *Date: *Thu, May 16, 2019 at 3:52 AM *To: *Arthur Eubanks *Cc: *OpenJDK Network Dev list
Arthur, > > On 16 May 2019, at 00:24, Arthur Eubanks <aeuba...@google.com> wrote: > > webrev: http://cr.openjdk.java.net/~aeubanks/8224014/webrev.00/ > bug: https://bugs.openjdk.java.net/browse/JDK-8224014 > > In https://bugs.openjdk.java.net/browse/JDK-8220673, I missed > skipping test/jdk/java/net/NetworkInterface/IPv4Only.java when running in > an IPv6 only environment. It should have a call to > IPSupport.throwSkippedExceptionIfNonOperational(). > > > After the change for 8223532 in NetworkInterface.c, it is no longer > required that AF_INET sockets be able to be created, coupled with > -Djava.net.preferIPv4Stack=true, enumInterfaces may return NULL, which > in turn bubbles up to the Java layer, in this case getNetworkInterfaces, > as null ( rather than a collection containing the interfaces ). > > The specification for NetworkInterface::getNetworkInterfaces guarantees > that there be at least one element in the returned collection, but there > cannot be since the system is mis-configured ( the underlying platform > is IPv6-only coupled with -Djava.net.preferIPv4Stack=true ). The only > sensible thing for the NetworkInterface implementation to do is to throw > an exception ( which is perfectly fine as per its specification, > "java.net.SocketException: No network interfaces configured" ). > > Rather than skipping the test, which will clearly work, an alternative > is to ensure that an exception is thrown for this case, e.g. > > if (IPSupport.hasIPv4()) { > out.println("Testing IPv4"); > Enumeration<NetworkInterface> nifs = > NetworkInterface.getNetworkInterfaces(); > while (nifs.hasMoreElements()) { > NetworkInterface nif = nifs.nextElement(); > Enumeration<InetAddress> addrs = nif.getInetAddresses(); > while (addrs.hasMoreElements()) { > InetAddress hostAddr = addrs.nextElement(); > if ( hostAddr instanceof Inet6Address ){ > throw new RuntimeException( "NetworkInterfaceV6List > failed - found v6 address " + hostAddr.getHostAddress() ); > } > } > } > } else { > // No platform IPv4 support & -Djava.net.preferIPv4Stack=true > out.println("Testing without IPv4 support"); > try { > NetworkInterface.getNetworkInterfaces(); > } catch (SocketException expected) { > out.println("caught expected exception: " + expected); > } > > try { > NetworkInterface.networkInterfaces(); > } catch (SocketException expected) { > out.println("caught expected exception: " + expected); > } > } > > -Chris. > > Good idea, done. PTAL. Tested with and without IPv4 support. http://cr.openjdk.java.net/~aeubanks/8224014/webrev.01/index.html
