FIB MFC

[Julian Elischer]

Igor Sysoev wrote:
> On Thu, Jul 24, 2008 at 08:33:09AM -0700, Julian Elischer wrote:
> 


>> I was thinking that it might be possible to tag a socket to accept the 
>> fib of the packet coming in, but if we do this, we should decide
>> API to label a socket in this way..
> 
> I think it should be sysctl to globaly enable TCP FIB inheritance.
> API is already exists: sockopt(SO_SETFIB) for listening socket.

But a socket ALWAYS has a fib, even if you do nothing
because every process has a fib (usually 0)
so you need a new bit of state somewhere that means "inherit".
(I guess in the socket flags).

Possibly the FIB value of -1 when applied on a socket option might
signify that behaviour. (thus save us a new sockopt).
But such a value would revert to that of the process if the socket was 
not used as a listen socket. (or clear itself).

I have some MRT unhansements in hte pipeline and will include this if
I can.

BTW could you send me the diff for ipfw(8)?
I'll compare it with the one I'm about to commit.


> 
>> It is an excellent idea however, and I don't know why I didn't
>> do it already..
>>
>>> tcp4       0      0  192.168.1.100.80   XXXXXXXXXX      SYN_RCVD
>>> tcp4       0      0  192.168.1.100.80   XXXXXXXXXX      SYN_RCVD
>>> tcp4       0      0  192.168.1.100.80   XXXXXXXXXX      SYN_RCVD
>>>
>>> Can TCP connection inherit FIB from first SYN packet or not ?
>> no but it is a good idea.
> 
>