[resend with a slightly random pick of Cc:s - apologies if I ended up
choosing poorly]

The IPv6 multicast routing code implements RTM_GETROUTE, but only for a
dump request.  Retrieving a single MFC entry is not currently possible
via netlink.

While most of the data here can also be retrieved with SIOCGETSGCNT_IN6,
the lastused / RTA_EXPIRES is not included in the ioctl result (and we
need it in FRR.)

=> Implement single-entry RTM_GETROUTE by copying and adapting the IPv4
code.

Tested against FRRouting's (work-in-progress) IPv6 PIM implementation.

Cheers,


-David