On Fri, 19 Feb 2021 23:54:11 GMT, Alex Menkov <[email protected]> wrote:
>> test/jdk/com/sun/jdi/JdwpAttachTest.java line 183:
>>
>>> 181: boolean ipv6 =
>>> Boolean.parseBoolean(System.getProperty("java.net.preferIPv6Addresses"));
>>> 182: return ipv6 == (addr instanceof Inet6Address);
>>> 183: }
>>
>> In the CR you said:
>>
>>> But JDI framework respects "java.net.preferIPv6Addresses" system property
>>> (which by default is false), so connecting to empty host tries IPv4
>>> addresses 1st and tries IPv6 addresses only if connect to IPv4 failed.
>>
>> Are you referring to the JDI implementation, or the JDI test framework. In
>> any case, I had trouble locating this anywhere in the source.
>>
>> Also, "preferv6" doesn't mean that's what it ends up using. It just tries v6
>> first before deferring to v4 if v6 fails (or the opposite if it doesn't
>> prefer v6). I don't think you are capturing that part of the logic. What
>> happens if preferv6 is true but the connect to a v6 port fails. Should the
>> test try to connect to the v4 in that case?
>
>> In the CR you said:
>>
>> > But JDI framework respects "java.net.preferIPv6Addresses" system property
>> > (which by default is false), so connecting to empty host tries IPv4
>> > addresses 1st and tries IPv6 addresses only if connect to IPv4 failed.
>>
>> Are you referring to the JDI implementation, or the JDI test framework. In
>> any case, I had trouble locating this anywhere in the source.
>
> This is about JDI implementation (the test uses JDWP agent to attach -
> corresponding code is at
> src/jdk.jdwp.agent/share/native/libdt_socket/socketTransport.c)
>
>> Also, "preferv6" doesn't mean that's what it ends up using. It just tries v6
>> first before deferring to v4 if v6 fails (or the opposite if it doesn't
>> prefer v6). I don't think you are capturing that part of the logic. What
>> happens if preferv6 is true but the connect to a v6 port fails. Should the
>> test try to connect to the v4 in that case?
>
> Well. Lets consider the case when we have both IPv4 and IPv6 loopback
> addresses and "preferv6" is true (for "preferv6" == false it works opposite).
> The test does:
> 1. - listen on IPv6 loopback ("::1")
> - tries to attach to localhost
> JDI 1st tries IPv6, which is expected to succeed. If it fails, that
> means the test should fail too. Theoretically in the case test can
> successfully attach to some other process which listens on the same port IPv4
> loopback, but we expect the test to pass :)
> 2. - listen on IPv4 loopback (127.0.0.1)
> - tries to attach to localhost.
> JDI 1st tries IPv6, which is expected to fail, but if there is some
> other process which listens on the same port on IPv6 loopback, we get the
> error like described in the issue (handshake failure)
>
> So the logic is to test 1 and skip 2
Ok, that makes sense. Thanks
-------------
PR: https://git.openjdk.java.net/jdk/pull/2654
