8158519: Incorrect network mask and broadcast address on Linux when there are multiple IPv4 addresses on an interface

[Langer, Christoph]

Hi Chris,

I now took time to look at your proposal based on ioctl calls. This looks very good. I came up with some modifications to your patch and created another webrev:

http://cr.openjdk.java.net/~clanger/webrevs/8158519.1/

This builds on Linux, AIX, Solaris and Mac and the basic test to list all network interfaces on these platforms still succeeds. I also tested on Linux that the bug reported by Doychin is fixed.

My changes in detail:
- picked up the suggestions of Dmitry, except for the IFF_POINTOPOINT check which I left untouched
- corrected further indentations and removed a debug fprintf output which was left
- changed the order of arguments for function addif (you may or may not like this, of course ;-))
- renamed ifr_netmaskP to ifr_subnetaddrP as I think this fits more here since the subnetaddr is converted to a netmask by computeMaskFromAddress (which you may or may not like, as well)
- AIX: need to use ifreqP->ifr_addr for SIOCGIFNETMASK since ifreqP->ifr_netmask is not available on this platform

From my point of view this change could be pushed now.

As for the general discussion getifaddrs vs. ioctl: I would like to continue refactoring the code ending up with 2 sets of enumInterfaces implementations. One getifaddrs based and the other ioctl based. And then I would introduce some #ifdef section which switches to the desired path per platform. I'll come up with a proposal for that after this change got pushed.

Thanks and Best regards
Christoph


> -----Original Message-----
> From: net-dev [mailto:net-dev-bounces at openjdk.java.net] On Behalf Of Dmitry
> Samersoff
> Sent: Donnerstag, 2. Juni 2016 19:35
> To: Chris Hegarty <chris.hegarty at oracle.com>; Doychin Bondzhev
> <doychin at dsoft-bg.com>; OpenJDK Network Dev list <net-
> dev at openjdk.java.net>
> Subject: Re: 8158519: Incorrect network mask and broadcast address on Linux
> when there are multiple IPv4 addresses on an interface
> 
> Chris,
> 
> Looks good for me. Only minor nits (no need to re-review).
> 
> 1040 missed space before {
> 
> 1158 please, add comment and {} around continue.
> 
> 1938  I'm not sure that check for IFF_POINTOPOINT is necessary (but
> don't mid to leave it). Do you know the case when both flags are set?
> 
> -Dmitry
> 
> On 2016-06-02 15:06, Chris Hegarty wrote:
> > Doychin, et al,
> >
> > I finally got time to look at the issue you reported and your suggested patch. I
> filed
> > 8158519 [1] to track the issue. I think your suggested patch may be ok, but I
> just
> > wanted to push on the ioctl approach. I found an alternative, and verified that
> it
> > works as expected. Please take a look, and verify in your environment.  Then
> we
> > need to weigh up the two separate approaches.
> >
> > http://cr.openjdk.java.net/~chegar/8158519.00/
> >
> > For the record, I don’t have any specific issue with using getifaddrs, I just
> wanted to
> > see if there was a less invasive change. That said, using getifaddrs could lead
> to
> > cleaner code, but we would need to check the situation on AIX ( which I don’t
> have
> > access to ).
> >
> > -Chris.
> >
> > [1] https://bugs.openjdk.java.net/browse/JDK-8158519
> >