HEADSUP: arp-v2 has been committed

[Li, Qing]

Hi Tijl,

Good questions and see my comments below.

> 
> I'm looking into the Wine case, but don't have any experience with the
> implementation of routing tables, so I need to have a few things
> spelled out.
> 
> Wine currently uses:
> 
>  int mib[] = {CTL_NET, PF_ROUTE, 0, AF_INET, NET_RT_FLAGS,
RTF_LLINFO};
> 
> I take it this returns all the entries which have the RTF_LLINFO flag
> set? And to make this compile on CURRENT I have to change this into:
> 
> #ifdef RTF_LLINFO
>  int mib[] = {CTL_NET, PF_ROUTE, 0, AF_INET, NET_RT_FLAGS,
RTF_LLINFO};
> #else
>  int mib[] = {CTL_NET, PF_ROUTE, 0, AF_INET, NET_RT_FLAGS, 0};
> #endif
> 
> Is AF_INET really the correct address family? What about AF_LINK and
> AF_ARP? Is using NET_RT_FLAGS with flags mask 0 exactly the same as
> using NET_RT_DUMP?
> 

AF_INET is the correct address family, which indicates the L2 
information (a.k.a RTF_LLINFO previously) should be retrieved from
the IPv4 ARP table. If the AF family were instead AF_INET6, then the
L2 information would be coming from the ND6 cache. 

NET_RT_DUMP walks the entire routing tree. Specifying specific flags
and using the NET_RT_FLAGS opcode retrieves routing entries that have
those bits set.

NET_RT_FLAGS with mask 0 is an indication to the kernel the L2 table 
should be retrieved. 

I am glad you asked these questions because after re-examining my code, 
I realized I could make slight optimization and also need to perform 
additional check against erroneous input. 


> 
> Also, at some other place, Wine wants to retrieve gateway entries and
> it uses:
> 
>  int mib[6] = {CTL_NET, PF_ROUTE, 0, PF_INET, NET_RT_DUMP, 0};
>                                      ^ this should be AF_INET I think
> 
> After that it runs over all entries counting only those which have
> RTF_GATEWAY set and RTF_MULTICAST unset. Is the output of this
> different now in CURRENT?
>

No, the output of this command is still the same. NET_RT_DUMP obtains
the entire L3 table and filtering for RTF_GATEWAY non-multicast
routes have the same semantics. Those flags never apply to L2 entries.

-- Qing