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Re: getifaddrs(3) returns 2 AF_LINK instances for the same interface

David Young wrote:
On Fri, Apr 17, 2009 at 08:55:15PM +0100, Roy Marples wrote:
So something like this?

Index: sys/net/rtsock.c
RCS file: /cvsroot/src/sys/net/rtsock.c,v
retrieving revision 1.125
diff -u -p -r1.125 rtsock.c
--- sys/net/rtsock.c    2 Apr 2009 21:02:06 -0000       1.125
+++ sys/net/rtsock.c    17 Apr 2009 19:51:33 -0000
@@ -1061,7 +1061,8 @@ sysctl_iflist(int af, struct rt_walkarg
                IFADDR_FOREACH(ifa, ifp) {
-                       if (af && af != ifa->ifa_addr->sa_family)
+                       if (ifa == ifp->if_dl ||
+                           (af && af != ifa->ifa_addr->sa_family))
                        info.rti_info[RTAX_IFA] = ifa->ifa_addr;
                        info.rti_info[RTAX_NETMASK] = ifa->ifa_netmask;

The kernel copies out the interface information in an RTM_IFINFO
message, then each of the addresses in an RTM_NEWADDR message.  There
is overlap between the _IFINFO and _NEWADDR information, but it's not
a *total* overlap, so you really do have to copy out one _NEWADDR per

So what info is present in _NEWADDR that isn't in _IFINFO for ifp->if_dl?
How is userland supposed to pick the right AF_LINK or are they both right?

Have another look at the doco and source for getifaddrs(3).  I think
that if there is a bug, you will find it there.

I have checked and the last change of note was over 7 years ago.
So are you suggesting that getifaddrs(3) should ignore the _IFINFO message or somehow merge it into the _NEWADDR one - if it's present?



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